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linux/arch/i386/kernel/kprobes.c

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Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
/*
* Kernel Probes (KProbes)
* arch/i386/kernel/kprobes.c
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (C) IBM Corporation, 2002, 2004
*
* 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel
* Probes initial implementation ( includes contributions from
* Rusty Russell).
* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
* interface to access function arguments.
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
* 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
* <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
* <prasanna@in.ibm.com> added function-return probes.
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
*/
#include <linux/kprobes.h>
#include <linux/ptrace.h>
#include <linux/preempt.h>
[PATCH] Move kprobe [dis]arming into arch specific code The architecture independent code of the current kprobes implementation is arming and disarming kprobes at registration time. The problem is that the code is assuming that arming and disarming is a just done by a simple write of some magic value to an address. This is problematic for ia64 where our instructions look more like structures, and we can not insert break points by just doing something like: *p->addr = BREAKPOINT_INSTRUCTION; The following patch to 2.6.12-rc4-mm2 adds two new architecture dependent functions: * void arch_arm_kprobe(struct kprobe *p) * void arch_disarm_kprobe(struct kprobe *p) and then adds the new functions for each of the architectures that already implement kprobes (spar64/ppc64/i386/x86_64). I thought arch_[dis]arm_kprobe was the most descriptive of what was really happening, but each of the architectures already had a disarm_kprobe() function that was really a "disarm and do some other clean-up items as needed when you stumble across a recursive kprobe." So... I took the liberty of changing the code that was calling disarm_kprobe() to call arch_disarm_kprobe(), and then do the cleanup in the block of code dealing with the recursive kprobe case. So far this patch as been tested on i386, x86_64, and ppc64, but still needs to be tested in sparc64. Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:25 +00:00
#include <asm/cacheflush.h>
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
#include <asm/kdebug.h>
#include <asm/desc.h>
[PATCH] kprobes: fix broken fault handling for i386 Provide proper kprobes fault handling, if a user-specified pre/post handlers tries to access user address space, through copy_from_user(), get_user() etc. The user-specified fault handler gets called only if the fault occurs while executing user-specified handlers. In such a case user-specified handler is allowed to fix it first, later if the user-specifed fault handler does not fix it, we try to fix it by calling fix_exception(). The user-specified handler will not be called if the fault happens when single stepping the original instruction, instead we reset the current probe and allow the system page fault handler to fix it up. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:22 +00:00
#include <asm/uaccess.h>
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
void jprobe_return_end(void);
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
/* insert a jmp code */
[PATCH] Switch Kprobes inline functions to __kprobes for i386 Andrew Morton pointed out that compiler might not inline the functions marked for inline in kprobes. There-by allowing the insertion of probes on these kprobes routines, which might cause recursion. This patch removes all such inline and adds them to kprobes section there by disallowing probes on all such routines. Some of the routines can even still be inlined, since these routines gets executed after the kprobes had done necessay setup for reentrancy. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-19 05:21:59 +00:00
static __always_inline void set_jmp_op(void *from, void *to)
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
{
struct __arch_jmp_op {
char op;
long raddr;
} __attribute__((packed)) *jop;
jop = (struct __arch_jmp_op *)from;
jop->raddr = (long)(to) - ((long)(from) + 5);
jop->op = RELATIVEJUMP_INSTRUCTION;
}
/*
* returns non-zero if opcodes can be boosted.
*/
[PATCH] kprobe: boost 2byte-opcodes on i386 Previous kprobe-booster patch has not handled any 2byte opcodes and prefixes. I checked whole IA32 opcode map and classified it. This patch enables kprobe to boost those 2byte opcodes and prefixes. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 07:25:19 +00:00
static __always_inline int can_boost(kprobe_opcode_t *opcodes)
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
{
[PATCH] kprobe: boost 2byte-opcodes on i386 Previous kprobe-booster patch has not handled any 2byte opcodes and prefixes. I checked whole IA32 opcode map and classified it. This patch enables kprobe to boost those 2byte opcodes and prefixes. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 07:25:19 +00:00
#define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \
(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \
(b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \
(b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \
(bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \
<< (row % 32))
/*
* Undefined/reserved opcodes, conditional jump, Opcode Extension
* Groups, and some special opcodes can not be boost.
*/
static const unsigned long twobyte_is_boostable[256 / 32] = {
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
/* ------------------------------- */
W(0x00, 0,0,1,1,0,0,1,0,1,1,0,0,0,0,0,0)| /* 00 */
W(0x10, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 10 */
W(0x20, 1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0)| /* 20 */
W(0x30, 0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 30 */
W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 40 */
W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 50 */
W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,0,0,1,1)| /* 60 */
W(0x70, 0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1), /* 70 */
W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 80 */
W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1), /* 90 */
W(0xa0, 1,1,0,1,1,1,0,0,1,1,0,1,1,1,0,1)| /* a0 */
W(0xb0, 1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1), /* b0 */
W(0xc0, 1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1)| /* c0 */
W(0xd0, 0,1,1,1,0,1,0,0,1,1,0,1,1,1,0,1), /* d0 */
W(0xe0, 0,1,1,0,0,1,0,0,1,1,0,1,1,1,0,1)| /* e0 */
W(0xf0, 0,1,1,1,0,1,0,0,1,1,1,0,1,1,1,0) /* f0 */
/* ------------------------------- */
/* 0 1 2 3 4 5 6 7 8 9 a b c d e f */
};
#undef W
kprobe_opcode_t opcode;
kprobe_opcode_t *orig_opcodes = opcodes;
retry:
if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
return 0;
opcode = *(opcodes++);
/* 2nd-byte opcode */
if (opcode == 0x0f) {
if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1)
return 0;
return test_bit(*opcodes, twobyte_is_boostable);
}
switch (opcode & 0xf0) {
case 0x60:
if (0x63 < opcode && opcode < 0x67)
goto retry; /* prefixes */
/* can't boost Address-size override and bound */
return (opcode != 0x62 && opcode != 0x67);
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
case 0x70:
return 0; /* can't boost conditional jump */
case 0xc0:
[PATCH] kprobe: boost 2byte-opcodes on i386 Previous kprobe-booster patch has not handled any 2byte opcodes and prefixes. I checked whole IA32 opcode map and classified it. This patch enables kprobe to boost those 2byte opcodes and prefixes. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 07:25:19 +00:00
/* can't boost software-interruptions */
return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf;
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
case 0xd0:
/* can boost AA* and XLAT */
return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7);
case 0xe0:
[PATCH] kprobe: boost 2byte-opcodes on i386 Previous kprobe-booster patch has not handled any 2byte opcodes and prefixes. I checked whole IA32 opcode map and classified it. This patch enables kprobe to boost those 2byte opcodes and prefixes. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 07:25:19 +00:00
/* can boost in/out and absolute jmps */
return ((opcode & 0x04) || opcode == 0xea);
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
case 0xf0:
[PATCH] kprobe: boost 2byte-opcodes on i386 Previous kprobe-booster patch has not handled any 2byte opcodes and prefixes. I checked whole IA32 opcode map and classified it. This patch enables kprobe to boost those 2byte opcodes and prefixes. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 07:25:19 +00:00
if ((opcode & 0x0c) == 0 && opcode != 0xf1)
goto retry; /* lock/rep(ne) prefix */
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
/* clear and set flags can be boost */
return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe));
default:
[PATCH] kprobe: boost 2byte-opcodes on i386 Previous kprobe-booster patch has not handled any 2byte opcodes and prefixes. I checked whole IA32 opcode map and classified it. This patch enables kprobe to boost those 2byte opcodes and prefixes. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 07:25:19 +00:00
if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e)
goto retry; /* prefixes */
/* can't boost CS override and call */
return (opcode != 0x2e && opcode != 0x9a);
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
}
}
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
/*
* returns non-zero if opcode modifies the interrupt flag.
*/
[PATCH] Switch Kprobes inline functions to __kprobes for i386 Andrew Morton pointed out that compiler might not inline the functions marked for inline in kprobes. There-by allowing the insertion of probes on these kprobes routines, which might cause recursion. This patch removes all such inline and adds them to kprobes section there by disallowing probes on all such routines. Some of the routines can even still be inlined, since these routines gets executed after the kprobes had done necessay setup for reentrancy. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-19 05:21:59 +00:00
static int __kprobes is_IF_modifier(kprobe_opcode_t opcode)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
switch (opcode) {
case 0xfa: /* cli */
case 0xfb: /* sti */
case 0xcf: /* iret/iretd */
case 0x9d: /* popf/popfd */
return 1;
}
return 0;
}
[PATCH] kprobes: prevent possible race conditions i386 changes This patch contains the i386 architecture specific changes to prevent the possible race conditions. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:27 +00:00
int __kprobes arch_prepare_kprobe(struct kprobe *p)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
[PATCH] Kprobes causes NX protection fault on i686 SMP Fix a problem seen on i686 machine with NX support where the instruction could not be single stepped because of NX bit set on the memory pages allocated by kprobes module. This patch provides allocation of instruction solt so that the processor can execute the instruction from that location similar to x86_64 architecture. Thanks to Bibo and Masami for testing this patch. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-24 21:04:08 +00:00
/* insn: must be on special executable page on i386. */
p->ainsn.insn = get_insn_slot();
if (!p->ainsn.insn)
return -ENOMEM;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
[PATCH] Move kprobe [dis]arming into arch specific code The architecture independent code of the current kprobes implementation is arming and disarming kprobes at registration time. The problem is that the code is assuming that arming and disarming is a just done by a simple write of some magic value to an address. This is problematic for ia64 where our instructions look more like structures, and we can not insert break points by just doing something like: *p->addr = BREAKPOINT_INSTRUCTION; The following patch to 2.6.12-rc4-mm2 adds two new architecture dependent functions: * void arch_arm_kprobe(struct kprobe *p) * void arch_disarm_kprobe(struct kprobe *p) and then adds the new functions for each of the architectures that already implement kprobes (spar64/ppc64/i386/x86_64). I thought arch_[dis]arm_kprobe was the most descriptive of what was really happening, but each of the architectures already had a disarm_kprobe() function that was really a "disarm and do some other clean-up items as needed when you stumble across a recursive kprobe." So... I took the liberty of changing the code that was calling disarm_kprobe() to call arch_disarm_kprobe(), and then do the cleanup in the block of code dealing with the recursive kprobe case. So far this patch as been tested on i386, x86_64, and ppc64, but still needs to be tested in sparc64. Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:25 +00:00
p->opcode = *p->addr;
[PATCH] kprobe: boost 2byte-opcodes on i386 Previous kprobe-booster patch has not handled any 2byte opcodes and prefixes. I checked whole IA32 opcode map and classified it. This patch enables kprobe to boost those 2byte opcodes and prefixes. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 07:25:19 +00:00
if (can_boost(p->addr)) {
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
p->ainsn.boostable = 0;
} else {
p->ainsn.boostable = -1;
}
[PATCH] kprobes: changed from using spinlock to mutex Since Kprobes runtime exception handlers is now lock free as this code path is now using RCU to walk through the list, there is no need for the register/unregister{_kprobe} to use spin_{lock/unlock}_isr{save/restore}. The serialization during registration/unregistration is now possible using just a mutex. In the above process, this patch also fixes a minor memory leak for x86_64 and powerpc. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 04:52:43 +00:00
return 0;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
}
[PATCH] kprobes: prevent possible race conditions i386 changes This patch contains the i386 architecture specific changes to prevent the possible race conditions. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:27 +00:00
void __kprobes arch_arm_kprobe(struct kprobe *p)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
[PATCH] Move kprobe [dis]arming into arch specific code The architecture independent code of the current kprobes implementation is arming and disarming kprobes at registration time. The problem is that the code is assuming that arming and disarming is a just done by a simple write of some magic value to an address. This is problematic for ia64 where our instructions look more like structures, and we can not insert break points by just doing something like: *p->addr = BREAKPOINT_INSTRUCTION; The following patch to 2.6.12-rc4-mm2 adds two new architecture dependent functions: * void arch_arm_kprobe(struct kprobe *p) * void arch_disarm_kprobe(struct kprobe *p) and then adds the new functions for each of the architectures that already implement kprobes (spar64/ppc64/i386/x86_64). I thought arch_[dis]arm_kprobe was the most descriptive of what was really happening, but each of the architectures already had a disarm_kprobe() function that was really a "disarm and do some other clean-up items as needed when you stumble across a recursive kprobe." So... I took the liberty of changing the code that was calling disarm_kprobe() to call arch_disarm_kprobe(), and then do the cleanup in the block of code dealing with the recursive kprobe case. So far this patch as been tested on i386, x86_64, and ppc64, but still needs to be tested in sparc64. Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:25 +00:00
*p->addr = BREAKPOINT_INSTRUCTION;
flush_icache_range((unsigned long) p->addr,
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
}
[PATCH] kprobes: prevent possible race conditions i386 changes This patch contains the i386 architecture specific changes to prevent the possible race conditions. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:27 +00:00
void __kprobes arch_disarm_kprobe(struct kprobe *p)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
*p->addr = p->opcode;
[PATCH] Move kprobe [dis]arming into arch specific code The architecture independent code of the current kprobes implementation is arming and disarming kprobes at registration time. The problem is that the code is assuming that arming and disarming is a just done by a simple write of some magic value to an address. This is problematic for ia64 where our instructions look more like structures, and we can not insert break points by just doing something like: *p->addr = BREAKPOINT_INSTRUCTION; The following patch to 2.6.12-rc4-mm2 adds two new architecture dependent functions: * void arch_arm_kprobe(struct kprobe *p) * void arch_disarm_kprobe(struct kprobe *p) and then adds the new functions for each of the architectures that already implement kprobes (spar64/ppc64/i386/x86_64). I thought arch_[dis]arm_kprobe was the most descriptive of what was really happening, but each of the architectures already had a disarm_kprobe() function that was really a "disarm and do some other clean-up items as needed when you stumble across a recursive kprobe." So... I took the liberty of changing the code that was calling disarm_kprobe() to call arch_disarm_kprobe(), and then do the cleanup in the block of code dealing with the recursive kprobe case. So far this patch as been tested on i386, x86_64, and ppc64, but still needs to be tested in sparc64. Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:25 +00:00
flush_icache_range((unsigned long) p->addr,
(unsigned long) p->addr + sizeof(kprobe_opcode_t));
}
[PATCH] Kprobes causes NX protection fault on i686 SMP Fix a problem seen on i686 machine with NX support where the instruction could not be single stepped because of NX bit set on the memory pages allocated by kprobes module. This patch provides allocation of instruction solt so that the processor can execute the instruction from that location similar to x86_64 architecture. Thanks to Bibo and Masami for testing this patch. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-24 21:04:08 +00:00
void __kprobes arch_remove_kprobe(struct kprobe *p)
{
[PATCH] sem2mutex: kprobes Semaphore to mutex conversion. The conversion was generated via scripts, and the result was validated automatically via a script as well. Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-23 11:00:35 +00:00
mutex_lock(&kprobe_mutex);
[PATCH] kprobes: enable booster on the preemptible kernel When we are unregistering a kprobe-booster, we can't release its instruction buffer immediately on the preemptive kernel, because some processes might be preempted on the buffer. The freeze_processes() and thaw_processes() functions can clean most of processes up from the buffer. There are still some non-frozen threads who have the PF_NOFREEZE flag. If those threads are sleeping (not preempted) at the known place outside the buffer, we can ensure safety of freeing. However, the processing of this check routine takes a long time. So, this patch introduces the garbage collection mechanism of insn_slot. It also introduces the "dirty" flag to free_insn_slot because of efficiency. The "clean" instruction slots (dirty flag is cleared) are released immediately. But the "dirty" slots which are used by boosted kprobes, are marked as garbages. collect_garbage_slots() will be invoked to release "dirty" slots if there are more than INSNS_PER_PAGE garbage slots or if there are no unused slots. Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "bibo,mao" <bibo.mao@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Yumiko Sugita <yumiko.sugita.yf@hitachi.com> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 04:38:11 +00:00
free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1));
[PATCH] sem2mutex: kprobes Semaphore to mutex conversion. The conversion was generated via scripts, and the result was validated automatically via a script as well. Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-23 11:00:35 +00:00
mutex_unlock(&kprobe_mutex);
[PATCH] Kprobes causes NX protection fault on i686 SMP Fix a problem seen on i686 machine with NX support where the instruction could not be single stepped because of NX bit set on the memory pages allocated by kprobes module. This patch provides allocation of instruction solt so that the processor can execute the instruction from that location similar to x86_64 architecture. Thanks to Bibo and Masami for testing this patch. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-24 21:04:08 +00:00
}
[PATCH] Switch Kprobes inline functions to __kprobes for i386 Andrew Morton pointed out that compiler might not inline the functions marked for inline in kprobes. There-by allowing the insertion of probes on these kprobes routines, which might cause recursion. This patch removes all such inline and adds them to kprobes section there by disallowing probes on all such routines. Some of the routines can even still be inlined, since these routines gets executed after the kprobes had done necessay setup for reentrancy. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-19 05:21:59 +00:00
static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
{
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
kcb->prev_kprobe.kp = kprobe_running();
kcb->prev_kprobe.status = kcb->kprobe_status;
kcb->prev_kprobe.old_eflags = kcb->kprobe_old_eflags;
kcb->prev_kprobe.saved_eflags = kcb->kprobe_saved_eflags;
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
}
[PATCH] Switch Kprobes inline functions to __kprobes for i386 Andrew Morton pointed out that compiler might not inline the functions marked for inline in kprobes. There-by allowing the insertion of probes on these kprobes routines, which might cause recursion. This patch removes all such inline and adds them to kprobes section there by disallowing probes on all such routines. Some of the routines can even still be inlined, since these routines gets executed after the kprobes had done necessay setup for reentrancy. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-19 05:21:59 +00:00
static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
{
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
__get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp;
kcb->kprobe_status = kcb->prev_kprobe.status;
kcb->kprobe_old_eflags = kcb->prev_kprobe.old_eflags;
kcb->kprobe_saved_eflags = kcb->prev_kprobe.saved_eflags;
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
}
[PATCH] Switch Kprobes inline functions to __kprobes for i386 Andrew Morton pointed out that compiler might not inline the functions marked for inline in kprobes. There-by allowing the insertion of probes on these kprobes routines, which might cause recursion. This patch removes all such inline and adds them to kprobes section there by disallowing probes on all such routines. Some of the routines can even still be inlined, since these routines gets executed after the kprobes had done necessay setup for reentrancy. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-19 05:21:59 +00:00
static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs,
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
struct kprobe_ctlblk *kcb)
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
{
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
__get_cpu_var(current_kprobe) = p;
kcb->kprobe_saved_eflags = kcb->kprobe_old_eflags
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
= (regs->eflags & (TF_MASK | IF_MASK));
if (is_IF_modifier(p->opcode))
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
kcb->kprobe_saved_eflags &= ~IF_MASK;
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
}
[PATCH] Switch Kprobes inline functions to __kprobes for i386 Andrew Morton pointed out that compiler might not inline the functions marked for inline in kprobes. There-by allowing the insertion of probes on these kprobes routines, which might cause recursion. This patch removes all such inline and adds them to kprobes section there by disallowing probes on all such routines. Some of the routines can even still be inlined, since these routines gets executed after the kprobes had done necessay setup for reentrancy. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-19 05:21:59 +00:00
static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
regs->eflags |= TF_MASK;
regs->eflags &= ~IF_MASK;
/*single step inline if the instruction is an int3*/
if (p->opcode == BREAKPOINT_INSTRUCTION)
regs->eip = (unsigned long)p->addr;
else
[PATCH] Kprobes causes NX protection fault on i686 SMP Fix a problem seen on i686 machine with NX support where the instruction could not be single stepped because of NX bit set on the memory pages allocated by kprobes module. This patch provides allocation of instruction solt so that the processor can execute the instruction from that location similar to x86_64 architecture. Thanks to Bibo and Masami for testing this patch. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-24 21:04:08 +00:00
regs->eip = (unsigned long)p->ainsn.insn;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
}
[PATCH] Kprobes: Use RCU for (un)register synchronization - arch changes Changes to the arch kprobes infrastructure to take advantage of the locking changes introduced by usage of RCU for synchronization. All handlers are now run without any locks held, so they have to be re-entrant or provide their own synchronization. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:14 +00:00
/* Called with kretprobe_lock held */
[PATCH] kprobes: prevent possible race conditions i386 changes This patch contains the i386 architecture specific changes to prevent the possible race conditions. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:27 +00:00
void __kprobes arch_prepare_kretprobe(struct kretprobe *rp,
struct pt_regs *regs)
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
{
unsigned long *sara = (unsigned long *)&regs->esp;
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
[PATCH] kprobe whitespace cleanup Whitespace is used to indent, this patch cleans up these sentences by kernel coding style. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:33 +00:00
struct kretprobe_instance *ri;
if ((ri = get_free_rp_inst(rp)) != NULL) {
ri->rp = rp;
ri->task = current;
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
ri->ret_addr = (kprobe_opcode_t *) *sara;
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
/* Replace the return addr with trampoline addr */
*sara = (unsigned long) &kretprobe_trampoline;
[PATCH] kprobe whitespace cleanup Whitespace is used to indent, this patch cleans up these sentences by kernel coding style. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:33 +00:00
add_rp_inst(ri);
} else {
rp->nmissed++;
}
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
}
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
/*
* Interrupts are disabled on entry as trap3 is an interrupt gate and they
* remain disabled thorough out this function.
*/
[PATCH] kprobes: prevent possible race conditions i386 changes This patch contains the i386 architecture specific changes to prevent the possible race conditions. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:27 +00:00
static int __kprobes kprobe_handler(struct pt_regs *regs)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
struct kprobe *p;
int ret = 0;
[PATCH] kprobe handler: discard user space trap Currently kprobe handler traps only happen in kernel space, so function kprobe_exceptions_notify should skip traps which happen in user space. This patch modifies this, and it is based on 2.6.16-rc4. Signed-off-by: bibo mao <bibo.mao@intel.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: <hiramatu@sdl.hitachi.co.jp> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:21 +00:00
kprobe_opcode_t *addr;
[PATCH] Kprobes: preempt_disable/enable() simplification Reorganize the preempt_disable/enable calls to eliminate the extra preempt depth. Changes based on Paul McKenney's review suggestions for the kprobes RCU changeset. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:14 +00:00
struct kprobe_ctlblk *kcb;
[PATCH] kprobe handler: discard user space trap Currently kprobe handler traps only happen in kernel space, so function kprobe_exceptions_notify should skip traps which happen in user space. This patch modifies this, and it is based on 2.6.16-rc4. Signed-off-by: bibo mao <bibo.mao@intel.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: <hiramatu@sdl.hitachi.co.jp> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:21 +00:00
addr = (kprobe_opcode_t *)(regs->eip - sizeof(kprobe_opcode_t));
[PATCH] Kprobes: preempt_disable/enable() simplification Reorganize the preempt_disable/enable calls to eliminate the extra preempt depth. Changes based on Paul McKenney's review suggestions for the kprobes RCU changeset. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:14 +00:00
/*
* We don't want to be preempted for the entire
* duration of kprobe processing
*/
preempt_disable();
kcb = get_kprobe_ctlblk();
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
/* Check we're not actually recursing */
if (kprobe_running()) {
p = get_kprobe(addr);
if (p) {
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
if (kcb->kprobe_status == KPROBE_HIT_SS &&
[PATCH] kprobes: fix bug when probed on task and isr functions This patch fixes a race condition where in system used to hang or sometime crash within minutes when kprobes are inserted on ISR routine and a task routine. The fix has been stress tested on i386, ia64, pp64 and on x86_64. To reproduce the problem insert kprobes on schedule() and do_IRQ() functions and you should see hang or system crash. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Acked-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:35 +00:00
*p->ainsn.insn == BREAKPOINT_INSTRUCTION) {
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
regs->eflags &= ~TF_MASK;
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
regs->eflags |= kcb->kprobe_saved_eflags;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
goto no_kprobe;
}
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
/* We have reentered the kprobe_handler(), since
* another probe was hit while within the handler.
* We here save the original kprobes variables and
* just single step on the instruction of the new probe
* without calling any user handlers.
*/
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
save_previous_kprobe(kcb);
set_current_kprobe(p, regs, kcb);
[PATCH] kprobes: increment kprobe missed count for multiprobes When multiple probes are registered at the same address and if due to some recursion (probe getting triggered within a probe handler), we skip calling pre_handlers and just increment nmissed field. The below patch make sure it walks the list for multiple probes case. Without the below patch we get incorrect results of nmissed count for multiple probe case. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-12-12 08:37:34 +00:00
kprobes_inc_nmissed_count(p);
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
prepare_singlestep(p, regs);
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
kcb->kprobe_status = KPROBE_REENTER;
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
return 1;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
} else {
[PATCH] kprobes: fix race in recovery of reentrant probe There is a window where a probe gets removed right after the probe is hit on some different cpu. In this case probe handlers can't find a matching probe instance related to break address. In this case we need to read the original instruction at break address to see if that is not a break/int3 instruction and recover safely. Previous code had a bug where we were not checking for the above race in case of reentrant probes and the below patch fixes this race. Tested on IA64, Powerpc, x86_64. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-11 20:17:42 +00:00
if (*addr != BREAKPOINT_INSTRUCTION) {
/* The breakpoint instruction was removed by
* another cpu right after we hit, no further
* handling of this interrupt is appropriate
*/
regs->eip -= sizeof(kprobe_opcode_t);
ret = 1;
goto no_kprobe;
}
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
p = __get_cpu_var(current_kprobe);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
if (p->break_handler && p->break_handler(p, regs)) {
goto ss_probe;
}
}
goto no_kprobe;
}
p = get_kprobe(addr);
if (!p) {
if (*addr != BREAKPOINT_INSTRUCTION) {
/*
* The breakpoint instruction was removed right
* after we hit it. Another cpu has removed
* either a probepoint or a debugger breakpoint
* at this address. In either case, no further
* handling of this interrupt is appropriate.
[PATCH] kprobes: fix handling of simultaneous probe hit/unregister This patch fixes a bug in kprobes's handling of a corner case on i386 and x86_64. On an SMP system, if one CPU unregisters a kprobe just after another CPU hits that probepoint, kprobe_handler() on the latter CPU sees that the kprobe has been unregistered, and attempts to let the CPU continue as if the probepoint hadn't been hit. The bug is that on i386 and x86_64, we were neglecting to set the IP back to the beginning of the probed instruction. This could cause an oops or crash. This bug doesn't exist on ppc64 and ia64, where a breakpoint instruction leaves the IP pointing to the beginning of the instruction. I don't know about sparc64. (Dave, could you please advise?) This fix has been tested on i386 and x86_64 SMP systems. To reproduce the problem, set one CPU to work registering and unregistering a kprobe repeatedly, and another CPU pounding the probepoint in a tight loop. Acked-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Jim Keniston <jkenisto@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:34 +00:00
* Back up over the (now missing) int3 and run
* the original instruction.
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
*/
[PATCH] kprobes: fix handling of simultaneous probe hit/unregister This patch fixes a bug in kprobes's handling of a corner case on i386 and x86_64. On an SMP system, if one CPU unregisters a kprobe just after another CPU hits that probepoint, kprobe_handler() on the latter CPU sees that the kprobe has been unregistered, and attempts to let the CPU continue as if the probepoint hadn't been hit. The bug is that on i386 and x86_64, we were neglecting to set the IP back to the beginning of the probed instruction. This could cause an oops or crash. This bug doesn't exist on ppc64 and ia64, where a breakpoint instruction leaves the IP pointing to the beginning of the instruction. I don't know about sparc64. (Dave, could you please advise?) This fix has been tested on i386 and x86_64 SMP systems. To reproduce the problem, set one CPU to work registering and unregistering a kprobe repeatedly, and another CPU pounding the probepoint in a tight loop. Acked-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Jim Keniston <jkenisto@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:34 +00:00
regs->eip -= sizeof(kprobe_opcode_t);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
ret = 1;
}
/* Not one of ours: let kernel handle it */
goto no_kprobe;
}
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
set_current_kprobe(p, regs, kcb);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
if (p->pre_handler && p->pre_handler(p, regs))
/* handler has already set things up, so skip ss setup */
return 1;
[PATCH] Kprobe: multi kprobe posthandler for booster If there are multi kprobes on the same probepoint, there will be one extra aggr_kprobe on the head of kprobe list. The aggr_kprobe has aggr_post_handler/aggr_break_handler whether the other kprobe post_hander/break_handler is NULL or not. This patch modifies this, only when there is one or more kprobe in the list whose post_handler is not NULL, post_handler of aggr_kprobe will be set as aggr_post_handler. [soshima@redhat.com: !CONFIG_PREEMPT fix] Signed-off-by: bibo, mao <bibo.mao@intel.com> Cc: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Satoshi Oshima <soshima@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26 07:25:22 +00:00
ss_probe:
[PATCH] kprobes: enable booster on the preemptible kernel When we are unregistering a kprobe-booster, we can't release its instruction buffer immediately on the preemptive kernel, because some processes might be preempted on the buffer. The freeze_processes() and thaw_processes() functions can clean most of processes up from the buffer. There are still some non-frozen threads who have the PF_NOFREEZE flag. If those threads are sleeping (not preempted) at the known place outside the buffer, we can ensure safety of freeing. However, the processing of this check routine takes a long time. So, this patch introduces the garbage collection mechanism of insn_slot. It also introduces the "dirty" flag to free_insn_slot because of efficiency. The "clean" instruction slots (dirty flag is cleared) are released immediately. But the "dirty" slots which are used by boosted kprobes, are marked as garbages. collect_garbage_slots() will be invoked to release "dirty" slots if there are more than INSNS_PER_PAGE garbage slots or if there are no unused slots. Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "bibo,mao" <bibo.mao@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Yumiko Sugita <yumiko.sugita.yf@hitachi.com> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 04:38:11 +00:00
#if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM)
[PATCH] kprobe-booster: disable in preemptible kernel The kprobe-booster's safety check against preemption does not work well now, because the preemption count has been modified by read_rcu_lock() in atomic_notifier_call_chain() before we check it. So, I'd like to prevent boosting kprobe temporarily if the kernel is preemptable. Now we are searching for the good solution. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-30 10:03:21 +00:00
if (p->ainsn.boostable == 1 && !p->post_handler){
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
/* Boost up -- we can execute copied instructions directly */
reset_current_kprobe();
regs->eip = (unsigned long)p->ainsn.insn;
preempt_enable_no_resched();
return 1;
}
[PATCH] kprobe-booster: disable in preemptible kernel The kprobe-booster's safety check against preemption does not work well now, because the preemption count has been modified by read_rcu_lock() in atomic_notifier_call_chain() before we check it. So, I'd like to prevent boosting kprobe temporarily if the kernel is preemptable. Now we are searching for the good solution. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-30 10:03:21 +00:00
#endif
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
prepare_singlestep(p, regs);
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
kcb->kprobe_status = KPROBE_HIT_SS;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
return 1;
no_kprobe:
[PATCH] Kprobes: preempt_disable/enable() simplification Reorganize the preempt_disable/enable calls to eliminate the extra preempt depth. Changes based on Paul McKenney's review suggestions for the kprobes RCU changeset. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:14 +00:00
preempt_enable_no_resched();
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
return ret;
}
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
/*
* For function-return probes, init_kprobes() establishes a probepoint
* here. When a retprobed function returns, this probe is hit and
* trampoline_probe_handler() runs, calling the kretprobe's handler.
*/
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
void __kprobes kretprobe_trampoline_holder(void)
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
{
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
asm volatile ( ".global kretprobe_trampoline\n"
[PATCH] kprobe whitespace cleanup Whitespace is used to indent, this patch cleans up these sentences by kernel coding style. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:33 +00:00
"kretprobe_trampoline: \n"
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
" pushf\n"
[PATCH] kretprobe: fix kretprobe-booster to save regs and set status There are two bugs in the kretprobe-booster. 1) It doesn't make room for gs registers. 2) It doesn't change status of the current kprobe. This status will effect the fault handling. This patch fixes these bugs and, additionally, saves skipped registers for compatibility with the original kretprobe. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-09 01:44:49 +00:00
/* skip cs, eip, orig_eax */
" subl $12, %esp\n"
[PATCH] i386: Convert i386 PDA code to use %fs Convert the PDA code to use %fs rather than %gs as the segment for per-processor data. This is because some processors show a small but measurable performance gain for reloading a NULL segment selector (as %fs generally is in user-space) versus a non-NULL one (as %gs generally is). On modern processors the difference is very small, perhaps undetectable. Some old AMD "K6 3D+" processors are noticably slower when %fs is used rather than %gs; I have no idea why this might be, but I think they're sufficiently rare that it doesn't matter much. This patch also fixes the math emulator, which had not been adjusted to match the changed struct pt_regs. [frederik.deweerdt@gmail.com: fixit with gdb] [mingo@elte.hu: Fix KVM too] Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Andi Kleen <ak@suse.de> Cc: Ian Campbell <Ian.Campbell@XenSource.com> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Zachary Amsden <zach@vmware.com> Cc: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org>
2007-02-13 12:26:20 +00:00
" pushl %fs\n"
[PATCH] kretprobe: fix kretprobe-booster to save regs and set status There are two bugs in the kretprobe-booster. 1) It doesn't make room for gs registers. 2) It doesn't change status of the current kprobe. This status will effect the fault handling. This patch fixes these bugs and, additionally, saves skipped registers for compatibility with the original kretprobe. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-09 01:44:49 +00:00
" pushl %ds\n"
" pushl %es\n"
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
" pushl %eax\n"
" pushl %ebp\n"
" pushl %edi\n"
" pushl %esi\n"
" pushl %edx\n"
" pushl %ecx\n"
" pushl %ebx\n"
" movl %esp, %eax\n"
" call trampoline_handler\n"
/* move eflags to cs */
[PATCH] kretprobe: fix kretprobe-booster to save regs and set status There are two bugs in the kretprobe-booster. 1) It doesn't make room for gs registers. 2) It doesn't change status of the current kprobe. This status will effect the fault handling. This patch fixes these bugs and, additionally, saves skipped registers for compatibility with the original kretprobe. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-09 01:44:49 +00:00
" movl 52(%esp), %edx\n"
" movl %edx, 48(%esp)\n"
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
/* save true return address on eflags */
[PATCH] kretprobe: fix kretprobe-booster to save regs and set status There are two bugs in the kretprobe-booster. 1) It doesn't make room for gs registers. 2) It doesn't change status of the current kprobe. This status will effect the fault handling. This patch fixes these bugs and, additionally, saves skipped registers for compatibility with the original kretprobe. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-09 01:44:49 +00:00
" movl %eax, 52(%esp)\n"
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
" popl %ebx\n"
" popl %ecx\n"
" popl %edx\n"
" popl %esi\n"
" popl %edi\n"
" popl %ebp\n"
" popl %eax\n"
[PATCH] i386: Convert i386 PDA code to use %fs Convert the PDA code to use %fs rather than %gs as the segment for per-processor data. This is because some processors show a small but measurable performance gain for reloading a NULL segment selector (as %fs generally is in user-space) versus a non-NULL one (as %gs generally is). On modern processors the difference is very small, perhaps undetectable. Some old AMD "K6 3D+" processors are noticably slower when %fs is used rather than %gs; I have no idea why this might be, but I think they're sufficiently rare that it doesn't matter much. This patch also fixes the math emulator, which had not been adjusted to match the changed struct pt_regs. [frederik.deweerdt@gmail.com: fixit with gdb] [mingo@elte.hu: Fix KVM too] Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Signed-off-by: Andi Kleen <ak@suse.de> Cc: Ian Campbell <Ian.Campbell@XenSource.com> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Zachary Amsden <zach@vmware.com> Cc: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org>
2007-02-13 12:26:20 +00:00
/* skip eip, orig_eax, es, ds, fs */
[PATCH] kretprobe: fix kretprobe-booster to save regs and set status There are two bugs in the kretprobe-booster. 1) It doesn't make room for gs registers. 2) It doesn't change status of the current kprobe. This status will effect the fault handling. This patch fixes these bugs and, additionally, saves skipped registers for compatibility with the original kretprobe. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-09 01:44:49 +00:00
" addl $20, %esp\n"
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
" popf\n"
" ret\n");
}
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
/*
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
* Called from kretprobe_trampoline
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
*/
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
fastcall void *__kprobes trampoline_handler(struct pt_regs *regs)
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
{
[PATCH] kprobe whitespace cleanup Whitespace is used to indent, this patch cleans up these sentences by kernel coding style. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:33 +00:00
struct kretprobe_instance *ri = NULL;
[PATCH] kretprobe spinlock deadlock patch kprobe_flush_task() possibly calls kfree function during holding kretprobe_lock spinlock, if kfree function is probed by kretprobe that will incur spinlock deadlock. This patch moves kfree function out scope of kretprobe_lock. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:35 +00:00
struct hlist_head *head, empty_rp;
[PATCH] kprobe whitespace cleanup Whitespace is used to indent, this patch cleans up these sentences by kernel coding style. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:33 +00:00
struct hlist_node *node, *tmp;
[PATCH] Kprobes: Use RCU for (un)register synchronization - arch changes Changes to the arch kprobes infrastructure to take advantage of the locking changes introduced by usage of RCU for synchronization. All handlers are now run without any locks held, so they have to be re-entrant or provide their own synchronization. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:14 +00:00
unsigned long flags, orig_ret_address = 0;
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline;
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
[PATCH] kretprobe spinlock deadlock patch kprobe_flush_task() possibly calls kfree function during holding kretprobe_lock spinlock, if kfree function is probed by kretprobe that will incur spinlock deadlock. This patch moves kfree function out scope of kretprobe_lock. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:35 +00:00
INIT_HLIST_HEAD(&empty_rp);
[PATCH] Kprobes: Use RCU for (un)register synchronization - arch changes Changes to the arch kprobes infrastructure to take advantage of the locking changes introduced by usage of RCU for synchronization. All handlers are now run without any locks held, so they have to be re-entrant or provide their own synchronization. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:14 +00:00
spin_lock_irqsave(&kretprobe_lock, flags);
[PATCH] kprobe whitespace cleanup Whitespace is used to indent, this patch cleans up these sentences by kernel coding style. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:33 +00:00
head = kretprobe_inst_table_head(current);
[PATCH] kretprobe: fix kretprobe-booster to save regs and set status There are two bugs in the kretprobe-booster. 1) It doesn't make room for gs registers. 2) It doesn't change status of the current kprobe. This status will effect the fault handling. This patch fixes these bugs and, additionally, saves skipped registers for compatibility with the original kretprobe. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-09 01:44:49 +00:00
/* fixup registers */
[PATCH] i386: Kprobe rpl fix Kprobes bugfix for paravirt compatibility - RPL on the CS when inserting BPs must match running kernel. Signed-off-by: Zachary Amsden <zach@vmware.com> Signed-off-by: Andi Kleen <ak@suse.de> CC: Eric Biederman <ebiederm@xmission.com>
2007-02-13 12:26:21 +00:00
regs->xcs = __KERNEL_CS | get_kernel_rpl();
[PATCH] kretprobe: fix kretprobe-booster to save regs and set status There are two bugs in the kretprobe-booster. 1) It doesn't make room for gs registers. 2) It doesn't change status of the current kprobe. This status will effect the fault handling. This patch fixes these bugs and, additionally, saves skipped registers for compatibility with the original kretprobe. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-09 01:44:49 +00:00
regs->eip = trampoline_address;
regs->orig_eax = 0xffffffff;
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
/*
* It is possible to have multiple instances associated with a given
* task either because an multiple functions in the call path
* have a return probe installed on them, and/or more then one return
* return probe was registered for a target function.
*
* We can handle this because:
* - instances are always inserted at the head of the list
* - when multiple return probes are registered for the same
[PATCH] kprobe whitespace cleanup Whitespace is used to indent, this patch cleans up these sentences by kernel coding style. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:33 +00:00
* function, the first instance's ret_addr will point to the
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
* real return address, and all the rest will point to
* kretprobe_trampoline
*/
hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
[PATCH] kprobe whitespace cleanup Whitespace is used to indent, this patch cleans up these sentences by kernel coding style. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:33 +00:00
if (ri->task != current)
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
/* another task is sharing our hash bucket */
[PATCH] kprobe whitespace cleanup Whitespace is used to indent, this patch cleans up these sentences by kernel coding style. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:33 +00:00
continue;
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
if (ri->rp && ri->rp->handler){
__get_cpu_var(current_kprobe) = &ri->rp->kp;
[PATCH] kretprobe: fix kretprobe-booster to save regs and set status There are two bugs in the kretprobe-booster. 1) It doesn't make room for gs registers. 2) It doesn't change status of the current kprobe. This status will effect the fault handling. This patch fixes these bugs and, additionally, saves skipped registers for compatibility with the original kretprobe. Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-11-09 01:44:49 +00:00
get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
ri->rp->handler(ri, regs);
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
__get_cpu_var(current_kprobe) = NULL;
}
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
orig_ret_address = (unsigned long)ri->ret_addr;
[PATCH] kretprobe spinlock deadlock patch kprobe_flush_task() possibly calls kfree function during holding kretprobe_lock spinlock, if kfree function is probed by kretprobe that will incur spinlock deadlock. This patch moves kfree function out scope of kretprobe_lock. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:35 +00:00
recycle_rp_inst(ri, &empty_rp);
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
if (orig_ret_address != trampoline_address)
/*
* This is the real return address. Any other
* instances associated with this task are for
* other calls deeper on the call stack
*/
break;
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
}
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
[PATCH] Kprobes: Use RCU for (un)register synchronization - arch changes Changes to the arch kprobes infrastructure to take advantage of the locking changes introduced by usage of RCU for synchronization. All handlers are now run without any locks held, so they have to be re-entrant or provide their own synchronization. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:14 +00:00
spin_unlock_irqrestore(&kretprobe_lock, flags);
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
[PATCH] kretprobe spinlock deadlock patch kprobe_flush_task() possibly calls kfree function during holding kretprobe_lock spinlock, if kfree function is probed by kretprobe that will incur spinlock deadlock. This patch moves kfree function out scope of kretprobe_lock. Signed-off-by: bibo, mao <bibo.mao@intel.com> Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02 09:17:35 +00:00
hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
hlist_del(&ri->hlist);
kfree(ri);
}
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
return (void*)orig_ret_address;
[PATCH] kprobes: function-return probes This patch adds function-return probes to kprobes for the i386 architecture. This enables you to establish a handler to be run when a function returns. 1. API Two new functions are added to kprobes: int register_kretprobe(struct kretprobe *rp); void unregister_kretprobe(struct kretprobe *rp); 2. Registration and unregistration 2.1 Register To register a function-return probe, the user populates the following fields in a kretprobe object and calls register_kretprobe() with the kretprobe address as an argument: kp.addr - the function's address handler - this function is run after the ret instruction executes, but before control returns to the return address in the caller. maxactive - The maximum number of instances of the probed function that can be active concurrently. For example, if the function is non- recursive and is called with a spinlock or mutex held, maxactive = 1 should be enough. If the function is non-recursive and can never relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should be enough. maxactive is used to determine how many kretprobe_instance objects to allocate for this particular probed function. If maxactive <= 0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 * NR_CPUS) else maxactive=NR_CPUS) For example: struct kretprobe rp; rp.kp.addr = /* entrypoint address */ rp.handler = /*return probe handler */ rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */ register_kretprobe(&rp); The following field may also be of interest: nmissed - Initialized to zero when the function-return probe is registered, and incremented every time the probed function is entered but there is no kretprobe_instance object available for establishing the function-return probe (i.e., because maxactive was set too low). 2.2 Unregister To unregiter a function-return probe, the user calls unregister_kretprobe() with the same kretprobe object as registered previously. If a probed function is running when the return probe is unregistered, the function will return as expected, but the handler won't be run. 3. Limitations 3.1 This patch supports only the i386 architecture, but patches for x86_64 and ppc64 are anticipated soon. 3.2 Return probes operates by replacing the return address in the stack (or in a known register, such as the lr register for ppc). This may cause __builtin_return_address(0), when invoked from the return-probed function, to return the address of the return-probes trampoline. 3.3 This implementation uses the "Multiprobes at an address" feature in 2.6.12-rc3-mm3. 3.4 Due to a limitation in multi-probes, you cannot currently establish a return probe and a jprobe on the same function. A patch to remove this limitation is being tested. This feature is required by SystemTap (http://sourceware.org/systemtap), and reflects ideas contributed by several SystemTap developers, including Will Cohen and Ananth Mavinakayanahalli. Signed-off-by: Hien Nguyen <hien@us.ibm.com> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Frederik Deweerdt <frederik.deweerdt@laposte.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:19 +00:00
}
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
/*
* Called after single-stepping. p->addr is the address of the
* instruction whose first byte has been replaced by the "int 3"
* instruction. To avoid the SMP problems that can occur when we
* temporarily put back the original opcode to single-step, we
* single-stepped a copy of the instruction. The address of this
* copy is p->ainsn.insn.
*
* This function prepares to return from the post-single-step
* interrupt. We have to fix up the stack as follows:
*
* 0) Except in the case of absolute or indirect jump or call instructions,
* the new eip is relative to the copied instruction. We need to make
* it relative to the original instruction.
*
* 1) If the single-stepped instruction was pushfl, then the TF and IF
* flags are set in the just-pushed eflags, and may need to be cleared.
*
* 2) If the single-stepped instruction was a call, the return address
* that is atop the stack is the address following the copied instruction.
* We need to make it the address following the original instruction.
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
*
* This function also checks instruction size for preparing direct execution.
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
*/
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
static void __kprobes resume_execution(struct kprobe *p,
struct pt_regs *regs, struct kprobe_ctlblk *kcb)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
unsigned long *tos = (unsigned long *)&regs->esp;
[PATCH] Kprobes causes NX protection fault on i686 SMP Fix a problem seen on i686 machine with NX support where the instruction could not be single stepped because of NX bit set on the memory pages allocated by kprobes module. This patch provides allocation of instruction solt so that the processor can execute the instruction from that location similar to x86_64 architecture. Thanks to Bibo and Masami for testing this patch. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-24 21:04:08 +00:00
unsigned long copy_eip = (unsigned long)p->ainsn.insn;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
unsigned long orig_eip = (unsigned long)p->addr;
[PATCH] kprobes: clean up resume_execute() Clean up kprobe's resume_execute() for i386 arch. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:13 +00:00
regs->eflags &= ~TF_MASK;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
switch (p->ainsn.insn[0]) {
case 0x9c: /* pushfl */
*tos &= ~(TF_MASK | IF_MASK);
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
*tos |= kcb->kprobe_old_eflags;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
break;
[PATCH] kprobe: fix resume execution on i386 Fix resume_execution() to handle iret and absolute jump opcode correctly on i386. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-28 01:39:55 +00:00
case 0xc2: /* iret/ret/lret */
case 0xc3:
[PATCH] Kprobes: Incorrect handling of probes on ret/lret instruction Kprobes could not handle the insertion of a probe on the ret/lret instruction and used to oops after single stepping since kprobes was modifying eip/rip incorrectly. Adjustment of eip/rip is not required after single stepping in case of ret/lret instruction, because eip/rip points to the correct location after execution of the ret/lret instruction. This patch fixes the above problem. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-05 23:15:40 +00:00
case 0xca:
[PATCH] kprobe: fix resume execution on i386 Fix resume_execution() to handle iret and absolute jump opcode correctly on i386. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-28 01:39:55 +00:00
case 0xcb:
case 0xcf:
[PATCH] kprobes: clean up resume_execute() Clean up kprobe's resume_execute() for i386 arch. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:13 +00:00
case 0xea: /* jmp absolute -- eip is correct */
/* eip is already adjusted, no more changes required */
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
p->ainsn.boostable = 1;
[PATCH] kprobes: clean up resume_execute() Clean up kprobe's resume_execute() for i386 arch. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:13 +00:00
goto no_change;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
case 0xe8: /* call relative - Fix return addr */
*tos = orig_eip + (*tos - copy_eip);
break;
[PATCH] kprobe: fix resume execution on i386 Fix resume_execution() to handle iret and absolute jump opcode correctly on i386. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-28 01:39:55 +00:00
case 0x9a: /* call absolute -- same as call absolute, indirect */
*tos = orig_eip + (*tos - copy_eip);
goto no_change;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
case 0xff:
if ((p->ainsn.insn[1] & 0x30) == 0x10) {
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
/*
[PATCH] kprobe: fix resume execution on i386 Fix resume_execution() to handle iret and absolute jump opcode correctly on i386. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Jim Keniston <jkenisto@us.ibm.com> Cc: Yumiko Sugita <sugita@sdl.hitachi.co.jp> Cc: Satoshi Oshima <soshima@redhat.com> Cc: Hideo Aoki <haoki@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-28 01:39:55 +00:00
* call absolute, indirect
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
* Fix return addr; eip is correct.
* But this is not boostable
*/
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
*tos = orig_eip + (*tos - copy_eip);
[PATCH] kprobes: clean up resume_execute() Clean up kprobe's resume_execute() for i386 arch. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:13 +00:00
goto no_change;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
} else if (((p->ainsn.insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */
((p->ainsn.insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
/* eip is correct. And this is boostable */
p->ainsn.boostable = 1;
[PATCH] kprobes: clean up resume_execute() Clean up kprobe's resume_execute() for i386 arch. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:13 +00:00
goto no_change;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
}
default:
break;
}
[PATCH] x86: kprobes-booster Current kprobe copies the original instruction at the probe point and replaces it with a breakpoint instruction (int3). When the kernel hits the probe point, kprobe handler is invoked. And the copied instruction is single-step executed on the copied buffer (not on the original address) by kprobe. After that, the kprobe checks registers and modify it (if need) as if the instructions was executed on the original address. My proposal is based on the fact there are many instructions which do NOT require the register modification after the single-step execution. When the copied instruction is a kind of them, kprobe just jumps back to the next instruction after single-step execution. If so, why don't we execute those instructions directly? With kprobe-booster patch, kprobes will execute a copied instruction directly and (if need) jump back to original code. This direct execution is executed when the kprobe don't have both post_handler and break_handler, and the copied instruction can be executed directly. I sorted instructions which can be executed directly or not; - Call instructions are NG(can not be executed directly). We should correct the return address pushed into top of stack. - Indirect instructions except for absolute indirect-jumps are NG. Those instructions changes EIP randomly. We should check EIP and correct it. - Instructions that change EIP beyond the range of the instruction buffer are NG. - Instructions that change EIP to tail 5 bytes of the instruction buffer (it is the size of a jump instruction). We must write a jump instruction which backs to original kernel code in the instruction buffer. - Break point instruction is NG. We should not touch EIP and pass to other handlers. - Absolute direct/indirect jumps are OK.- Conditional Jumps are NG. - Halt and software-interruptions are NG. Because it will stay on the instruction buffer of kprobes. - Prefixes are NG. - Unknown/reserved opcode is NG. - Other 1 byte instructions are OK. But those instructions need a jump back code. - 2 bytes instructions are mapped sparsely. So, in this release, this patch don't boost those instructions. >From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software Developer's Manual Vol.2 B, I determined that following opcodes are not boostable. - 0FH (2byte escape) - 70H - 7FH (Jump on condition) - 9AH (Call) and 9CH (Pushf) - C0H-C1H (Grp 2: includes reserved opcode) - C6H-C7H (Grp11: includes reserved opcode) - CCH-CEH (Software-interrupt) - D0H-D3H (Grp2: includes reserved opcode) - D6H (Reserved) - D8H-DFH (Coprocessor) - E0H-E3H (loop/conditional jump) - E8H (Call) - F0H-F3H (Prefixes and reserved) - F4H (Halt) - F6H-F7H (Grp3: includes reserved opcode) - FEH-FFH(Grp4,5: includes reserved opcode) Kprobe-booster checks whether target instruction can be boosted (can be executed directly) at arch_copy_kprobe() function. If the target instruction can be boosted, it clears "boostable" flag. If not, it sets "boostable" flag -1. This is disabled status. In resume_execution() function, If "boostable" flag is cleared, kprobe-booster measures the size of the target instruction and sets "boostable" flag 1. In kprobe_handler(), kprobe checks the "boostable" flag. If the flag is 1, it resets current kprobe and executes instruction buffer directly instead of single stepping. When unregistering a boosted kprobe, it calls synchronize_sched() after "int3" is removed. So we can ensure followings after the synchronize_sched() called. - interrupt handlers are finished on all CPUs. - instruction buffer is not executed on all CPUs. And we can release the boosted kprobe safely. And also, on preemptible kernel, the booster is not enabled where the kernel preemption is enabled. So, there are no preempted threads on the instruction buffer. The description of kretprobe-booster: ==================================== In the normal operation, kretprobe make a target function return to trampoline code. And a kprobe (called trampoline_probe) have been inserted at the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to original return address. Kretprobe-booster patch removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. And tranpoline code returns to original return address. This new trampoline code stores and restores registers, so the kretprobe handler is still able to access those registers. Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch reduces it to 0.6 usec/probe(*). Also current kretprobe has about 2.0 usec/probe(*) overhead. Kprobe-booster patch reduces it to 1.3 usec/probe(*), and the combination of both kprobe-booster patch and kretprobe-booster patch reduces it to 0.9 usec/probe(*). I expect the combination of both patches can reduce half of a probing overhead. Performance numbers strongly depend on the processor model. Andrew Morton wrote: > These preempt tricks look rather nasty. Can you please describe what the > problem is, precisely? And how this code avoids it? Perhaps we can find > something cleaner. The problem is how to remove the copied instructions of the kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y). Kprobes basically executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)copied instructioin(single step) (5)kprobe_posthandler() (6)preempt_enable() (7)return to the original code During the execution of copied instruction, preemption is disabled (from step (2) to (6)). When unregistering the probes, Kprobe waits for RCU quiescent state by using synchronize_sched() after removing int3 instruction. Thus we can ensure the copied instruction is not executed. On the other hand, kprobe-booster executes the following actions; (1)int3 (2)preempt_disable() (3)kprobe_prehandler() (4)preempt_enable() <-- this one is added by my patch (5)copied instruction(direct execution) (6)jmp back to the original code The problem is that we have no way to prevent preemption on step (5) or (6). We cannot call preempt_disable() after step (6), because there are no rooms to do that. Thus, some other processes may be preempted at step(5) or (6) on preemptable kernel. And I couldn't find the easy way to ensure that other processes' stack do *not* have the address of them. (I thought some way to do that, but those are very costly.) So currently, I simply boost the kprobe only when the probe point is already preemption disabled. > Also, the patch adds a preempt_enable() but I don't see a corresponding > preempt_disable(). Am I missing something? It is corresponding to the preempt_disable() in the top of kprobe_handler(). I copied the code of kprobe_handler() here: static int __kprobes kprobe_handler(struct pt_regs *regs) { struct kprobe *p; int ret = 0; kprobe_opcode_t *addr = NULL; unsigned long *lp; struct kprobe_ctlblk *kcb; /* * We don't want to be preempted for the entire * duration of kprobe processing */ preempt_disable(); <-- HERE kcb = get_kprobe_ctlblk(); Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:17 +00:00
if (p->ainsn.boostable == 0) {
if ((regs->eip > copy_eip) &&
(regs->eip - copy_eip) + 5 < MAX_INSN_SIZE) {
/*
* These instructions can be executed directly if it
* jumps back to correct address.
*/
set_jmp_op((void *)regs->eip,
(void *)orig_eip + (regs->eip - copy_eip));
p->ainsn.boostable = 1;
} else {
p->ainsn.boostable = -1;
}
}
[PATCH] kprobes: clean up resume_execute() Clean up kprobe's resume_execute() for i386 arch. Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:13 +00:00
regs->eip = orig_eip + (regs->eip - copy_eip);
no_change:
return;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
}
/*
* Interrupts are disabled on entry as trap1 is an interrupt gate and they
[PATCH] Kprobes: Use RCU for (un)register synchronization - arch changes Changes to the arch kprobes infrastructure to take advantage of the locking changes introduced by usage of RCU for synchronization. All handlers are now run without any locks held, so they have to be re-entrant or provide their own synchronization. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:14 +00:00
* remain disabled thoroughout this function.
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
*/
[PATCH] Switch Kprobes inline functions to __kprobes for i386 Andrew Morton pointed out that compiler might not inline the functions marked for inline in kprobes. There-by allowing the insertion of probes on these kprobes routines, which might cause recursion. This patch removes all such inline and adds them to kprobes section there by disallowing probes on all such routines. Some of the routines can even still be inlined, since these routines gets executed after the kprobes had done necessay setup for reentrancy. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-19 05:21:59 +00:00
static int __kprobes post_kprobe_handler(struct pt_regs *regs)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
if (!cur)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
return 0;
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
kcb->kprobe_status = KPROBE_HIT_SSDONE;
cur->post_handler(cur, regs, 0);
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
}
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
resume_execution(cur, regs, kcb);
regs->eflags |= kcb->kprobe_saved_eflags;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
/*Restore back the original saved kprobes variables and continue. */
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
if (kcb->kprobe_status == KPROBE_REENTER) {
restore_previous_kprobe(kcb);
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
goto out;
}
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
reset_current_kprobe();
[PATCH] kprobes: Temporary disarming of reentrant probe for i386 This patch includes i386 architecture specific changes to support temporary disarming on reentrancy of probes. Signed-of-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-23 07:09:37 +00:00
out:
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
preempt_enable_no_resched();
/*
* if somebody else is singlestepping across a probe point, eflags
* will have TF set, in which case, continue the remaining processing
* of do_debug, as if this is not a probe hit.
*/
if (regs->eflags & TF_MASK)
return 0;
return 1;
}
[PATCH] Switch Kprobes inline functions to __kprobes for i386 Andrew Morton pointed out that compiler might not inline the functions marked for inline in kprobes. There-by allowing the insertion of probes on these kprobes routines, which might cause recursion. This patch removes all such inline and adds them to kprobes section there by disallowing probes on all such routines. Some of the routines can even still be inlined, since these routines gets executed after the kprobes had done necessay setup for reentrancy. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-19 05:21:59 +00:00
static int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
struct kprobe *cur = kprobe_running();
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
[PATCH] kprobes: fix broken fault handling for i386 Provide proper kprobes fault handling, if a user-specified pre/post handlers tries to access user address space, through copy_from_user(), get_user() etc. The user-specified fault handler gets called only if the fault occurs while executing user-specified handlers. In such a case user-specified handler is allowed to fix it first, later if the user-specifed fault handler does not fix it, we try to fix it by calling fix_exception(). The user-specified handler will not be called if the fault happens when single stepping the original instruction, instead we reset the current probe and allow the system page fault handler to fix it up. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:22 +00:00
switch(kcb->kprobe_status) {
case KPROBE_HIT_SS:
case KPROBE_REENTER:
/*
* We are here because the instruction being single
* stepped caused a page fault. We reset the current
* kprobe and the eip points back to the probe address
* and allow the page fault handler to continue as a
* normal page fault.
*/
regs->eip = (unsigned long)cur->addr;
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
regs->eflags |= kcb->kprobe_old_eflags;
[PATCH] kprobes: fix broken fault handling for i386 Provide proper kprobes fault handling, if a user-specified pre/post handlers tries to access user address space, through copy_from_user(), get_user() etc. The user-specified fault handler gets called only if the fault occurs while executing user-specified handlers. In such a case user-specified handler is allowed to fix it first, later if the user-specifed fault handler does not fix it, we try to fix it by calling fix_exception(). The user-specified handler will not be called if the fault happens when single stepping the original instruction, instead we reset the current probe and allow the system page fault handler to fix it up. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:22 +00:00
if (kcb->kprobe_status == KPROBE_REENTER)
restore_previous_kprobe(kcb);
else
reset_current_kprobe();
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
preempt_enable_no_resched();
[PATCH] kprobes: fix broken fault handling for i386 Provide proper kprobes fault handling, if a user-specified pre/post handlers tries to access user address space, through copy_from_user(), get_user() etc. The user-specified fault handler gets called only if the fault occurs while executing user-specified handlers. In such a case user-specified handler is allowed to fix it first, later if the user-specifed fault handler does not fix it, we try to fix it by calling fix_exception(). The user-specified handler will not be called if the fault happens when single stepping the original instruction, instead we reset the current probe and allow the system page fault handler to fix it up. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:22 +00:00
break;
case KPROBE_HIT_ACTIVE:
case KPROBE_HIT_SSDONE:
/*
* We increment the nmissed count for accounting,
* we can also use npre/npostfault count for accouting
* these specific fault cases.
*/
kprobes_inc_nmissed_count(cur);
/*
* We come here because instructions in the pre/post
* handler caused the page_fault, this could happen
* if handler tries to access user space by
* copy_from_user(), get_user() etc. Let the
* user-specified handler try to fix it first.
*/
if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr))
return 1;
/*
* In case the user-specified fault handler returned
* zero, try to fix up.
*/
if (fixup_exception(regs))
return 1;
/*
* fixup_exception() could not handle it,
* Let do_page_fault() fix it.
*/
break;
default:
break;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
}
return 0;
}
/*
* Wrapper routine to for handling exceptions.
*/
[PATCH] kprobes: prevent possible race conditions i386 changes This patch contains the i386 architecture specific changes to prevent the possible race conditions. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:27 +00:00
int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
struct die_args *args = (struct die_args *)data;
[PATCH] Kprobes: rearrange preempt_disable/enable() calls The following set of patches are aimed at improving kprobes scalability. We currently serialize kprobe registration, unregistration and handler execution using a single spinlock - kprobe_lock. With these changes, kprobe handlers can run without any locks held. It also allows for simultaneous kprobe handler executions on different processors as we now track kprobe execution on a per processor basis. It is now necessary that the handlers be re-entrant since handlers can run concurrently on multiple processors. All changes have been tested on i386, ia64, ppc64 and x86_64, while sparc64 has been compile tested only. The patches can be viewed as 3 logical chunks: patch 1: Reorder preempt_(dis/en)able calls patches 2-7: Introduce per_cpu data areas to track kprobe execution patches 8-9: Use RCU to synchronize kprobe (un)registration and handler execution. Thanks to Maneesh Soni, James Keniston and Anil Keshavamurthy for their review and suggestions. Thanks again to Anil, Hien Nguyen and Kevin Stafford for testing the patches. This patch: Reorder preempt_disable/enable() calls in arch kprobes files in preparation to introduce locking changes. No functional changes introduced by this patch. Signed-off-by: Ananth N Mavinakayahanalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:07 +00:00
int ret = NOTIFY_DONE;
[PATCH] i386: don't try kprobes for v8086 mode Never allow int3 traps from V8086 mode to enter the kprobes handler. Signed-off-by: Zachary Amsden <zach@vmware.com> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 09:04:30 +00:00
if (args->regs && user_mode_vm(args->regs))
[PATCH] kprobe handler: discard user space trap Currently kprobe handler traps only happen in kernel space, so function kprobe_exceptions_notify should skip traps which happen in user space. This patch modifies this, and it is based on 2.6.16-rc4. Signed-off-by: bibo mao <bibo.mao@intel.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: "Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com> Cc: <hiramatu@sdl.hitachi.co.jp> Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:21 +00:00
return ret;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
switch (val) {
case DIE_INT3:
if (kprobe_handler(args->regs))
[PATCH] Kprobes: rearrange preempt_disable/enable() calls The following set of patches are aimed at improving kprobes scalability. We currently serialize kprobe registration, unregistration and handler execution using a single spinlock - kprobe_lock. With these changes, kprobe handlers can run without any locks held. It also allows for simultaneous kprobe handler executions on different processors as we now track kprobe execution on a per processor basis. It is now necessary that the handlers be re-entrant since handlers can run concurrently on multiple processors. All changes have been tested on i386, ia64, ppc64 and x86_64, while sparc64 has been compile tested only. The patches can be viewed as 3 logical chunks: patch 1: Reorder preempt_(dis/en)able calls patches 2-7: Introduce per_cpu data areas to track kprobe execution patches 8-9: Use RCU to synchronize kprobe (un)registration and handler execution. Thanks to Maneesh Soni, James Keniston and Anil Keshavamurthy for their review and suggestions. Thanks again to Anil, Hien Nguyen and Kevin Stafford for testing the patches. This patch: Reorder preempt_disable/enable() calls in arch kprobes files in preparation to introduce locking changes. No functional changes introduced by this patch. Signed-off-by: Ananth N Mavinakayahanalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:07 +00:00
ret = NOTIFY_STOP;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
break;
case DIE_DEBUG:
if (post_kprobe_handler(args->regs))
[PATCH] Kprobes: rearrange preempt_disable/enable() calls The following set of patches are aimed at improving kprobes scalability. We currently serialize kprobe registration, unregistration and handler execution using a single spinlock - kprobe_lock. With these changes, kprobe handlers can run without any locks held. It also allows for simultaneous kprobe handler executions on different processors as we now track kprobe execution on a per processor basis. It is now necessary that the handlers be re-entrant since handlers can run concurrently on multiple processors. All changes have been tested on i386, ia64, ppc64 and x86_64, while sparc64 has been compile tested only. The patches can be viewed as 3 logical chunks: patch 1: Reorder preempt_(dis/en)able calls patches 2-7: Introduce per_cpu data areas to track kprobe execution patches 8-9: Use RCU to synchronize kprobe (un)registration and handler execution. Thanks to Maneesh Soni, James Keniston and Anil Keshavamurthy for their review and suggestions. Thanks again to Anil, Hien Nguyen and Kevin Stafford for testing the patches. This patch: Reorder preempt_disable/enable() calls in arch kprobes files in preparation to introduce locking changes. No functional changes introduced by this patch. Signed-off-by: Ananth N Mavinakayahanalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:07 +00:00
ret = NOTIFY_STOP;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
break;
case DIE_GPF:
case DIE_PAGE_FAULT:
[PATCH] Kprobes: preempt_disable/enable() simplification Reorganize the preempt_disable/enable calls to eliminate the extra preempt depth. Changes based on Paul McKenney's review suggestions for the kprobes RCU changeset. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:14 +00:00
/* kprobe_running() needs smp_processor_id() */
preempt_disable();
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
if (kprobe_running() &&
kprobe_fault_handler(args->regs, args->trapnr))
[PATCH] Kprobes: rearrange preempt_disable/enable() calls The following set of patches are aimed at improving kprobes scalability. We currently serialize kprobe registration, unregistration and handler execution using a single spinlock - kprobe_lock. With these changes, kprobe handlers can run without any locks held. It also allows for simultaneous kprobe handler executions on different processors as we now track kprobe execution on a per processor basis. It is now necessary that the handlers be re-entrant since handlers can run concurrently on multiple processors. All changes have been tested on i386, ia64, ppc64 and x86_64, while sparc64 has been compile tested only. The patches can be viewed as 3 logical chunks: patch 1: Reorder preempt_(dis/en)able calls patches 2-7: Introduce per_cpu data areas to track kprobe execution patches 8-9: Use RCU to synchronize kprobe (un)registration and handler execution. Thanks to Maneesh Soni, James Keniston and Anil Keshavamurthy for their review and suggestions. Thanks again to Anil, Hien Nguyen and Kevin Stafford for testing the patches. This patch: Reorder preempt_disable/enable() calls in arch kprobes files in preparation to introduce locking changes. No functional changes introduced by this patch. Signed-off-by: Ananth N Mavinakayahanalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:07 +00:00
ret = NOTIFY_STOP;
[PATCH] Kprobes: preempt_disable/enable() simplification Reorganize the preempt_disable/enable calls to eliminate the extra preempt depth. Changes based on Paul McKenney's review suggestions for the kprobes RCU changeset. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:14 +00:00
preempt_enable();
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
break;
default:
break;
}
[PATCH] Kprobes: rearrange preempt_disable/enable() calls The following set of patches are aimed at improving kprobes scalability. We currently serialize kprobe registration, unregistration and handler execution using a single spinlock - kprobe_lock. With these changes, kprobe handlers can run without any locks held. It also allows for simultaneous kprobe handler executions on different processors as we now track kprobe execution on a per processor basis. It is now necessary that the handlers be re-entrant since handlers can run concurrently on multiple processors. All changes have been tested on i386, ia64, ppc64 and x86_64, while sparc64 has been compile tested only. The patches can be viewed as 3 logical chunks: patch 1: Reorder preempt_(dis/en)able calls patches 2-7: Introduce per_cpu data areas to track kprobe execution patches 8-9: Use RCU to synchronize kprobe (un)registration and handler execution. Thanks to Maneesh Soni, James Keniston and Anil Keshavamurthy for their review and suggestions. Thanks again to Anil, Hien Nguyen and Kevin Stafford for testing the patches. This patch: Reorder preempt_disable/enable() calls in arch kprobes files in preparation to introduce locking changes. No functional changes introduced by this patch. Signed-off-by: Ananth N Mavinakayahanalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:07 +00:00
return ret;
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
}
[PATCH] kprobes: prevent possible race conditions i386 changes This patch contains the i386 architecture specific changes to prevent the possible race conditions. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:27 +00:00
int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
struct jprobe *jp = container_of(p, struct jprobe, kp);
unsigned long addr;
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
kcb->jprobe_saved_regs = *regs;
kcb->jprobe_saved_esp = &regs->esp;
addr = (unsigned long)(kcb->jprobe_saved_esp);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
/*
* TBD: As Linus pointed out, gcc assumes that the callee
* owns the argument space and could overwrite it, e.g.
* tailcall optimization. So, to be absolutely safe
* we also save and restore enough stack bytes to cover
* the argument area.
*/
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr,
MIN_STACK_SIZE(addr));
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
regs->eflags &= ~IF_MASK;
regs->eip = (unsigned long)(jp->entry);
return 1;
}
[PATCH] kprobes: prevent possible race conditions i386 changes This patch contains the i386 architecture specific changes to prevent the possible race conditions. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:27 +00:00
void __kprobes jprobe_return(void)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
asm volatile (" xchgl %%ebx,%%esp \n"
" int3 \n"
" .globl jprobe_return_end \n"
" jprobe_return_end: \n"
" nop \n"::"b"
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
(kcb->jprobe_saved_esp):"memory");
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
}
[PATCH] kprobes: prevent possible race conditions i386 changes This patch contains the i386 architecture specific changes to prevent the possible race conditions. Signed-off-by: Prasanna S Panchamukhi <prasanna@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-06 22:19:27 +00:00
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
{
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
u8 *addr = (u8 *) (regs->eip - 1);
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_esp);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
struct jprobe *jp = container_of(p, struct jprobe, kp);
if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) {
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
if (&regs->esp != kcb->jprobe_saved_esp) {
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
struct pt_regs *saved_regs =
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
container_of(kcb->jprobe_saved_esp,
struct pt_regs, esp);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
printk("current esp %p does not match saved esp %p\n",
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
&regs->esp, kcb->jprobe_saved_esp);
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
printk("Saved registers for jprobe %p\n", jp);
show_registers(saved_regs);
printk("Current registers\n");
show_registers(regs);
BUG();
}
[PATCH] Kprobes: Track kprobe on a per_cpu basis - i386 changes I386 changes to track kprobe execution on a per-cpu basis. We now track the kprobe state machine independently on each cpu, using an arch specific kprobe control block. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:08 +00:00
*regs = kcb->jprobe_saved_regs;
memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack,
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
MIN_STACK_SIZE(stack_addr));
[PATCH] Kprobes: preempt_disable/enable() simplification Reorganize the preempt_disable/enable calls to eliminate the extra preempt depth. Changes based on Paul McKenney's review suggestions for the kprobes RCU changeset. Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 09:00:14 +00:00
preempt_enable_no_resched();
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 22:20:36 +00:00
return 1;
}
return 0;
}
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
[PATCH] kprobes: fix namespace problem and sparc64 build The following renames arch_init, a kprobes function for performing any architecture specific initialization, to arch_init_kprobes in order to cleanup the namespace. Also, this patch adds arch_init_kprobes to sparc64 to fix the sparc64 kprobes build from the last return probe patch. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-06 01:54:50 +00:00
int __init arch_init_kprobes(void)
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
{
[PATCH] kretprobe: kretprobe-booster In normal operation, kretprobe makes a target function return to trampoline code. A kprobe (called trampoline_probe) has been inserted in the trampoline code. When the kernel hits this kprobe, it calls kretprobe's handler and it returns to the original return address. Kretprobe-booster removes the trampoline_probe. It allows the trampoline code to call kretprobe's handler directly instead of invoking kprobe. The trampoline code returns to the original return address. (changelog from Chuck Ebbert <76306.1226@compuserve.com> - thanks ;)) Signed-off-by: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-26 09:38:19 +00:00
return 0;
[PATCH] Return probe redesign: i386 specific changes The following patch contains the i386 specific changes for the new return probe design. Changes include: * Removing the architecture specific functions for querying a return probe instance off a stack address * Complete rework onf arch_prepare_kretprobe() and trampoline_probe_handler() * Removing trampoline_post_handler() * Adding arch_init() so that now we handle registering the return probe trampoline instead of kernel/kprobes.c doing it Signed-off-by: Rusty Lynch <rusty.lynch@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 22:17:09 +00:00
}
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