linux/arch/arm64/include/asm/stacktrace.h

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/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2012 ARM Ltd.
*/
#ifndef __ASM_STACKTRACE_H
#define __ASM_STACKTRACE_H
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <asm/memory.h>
#include <asm/ptrace.h>
arm64: kernel: Add arch-specific SDEI entry code and CPU masking The Software Delegated Exception Interface (SDEI) is an ARM standard for registering callbacks from the platform firmware into the OS. This is typically used to implement RAS notifications. Such notifications enter the kernel at the registered entry-point with the register values of the interrupted CPU context. Because this is not a CPU exception, it cannot reuse the existing entry code. (crucially we don't implicitly know which exception level we interrupted), Add the entry point to entry.S to set us up for calling into C code. If the event interrupted code that had interrupts masked, we always return to that location. Otherwise we pretend this was an IRQ, and use SDEI's complete_and_resume call to return to vbar_el1 + offset. This allows the kernel to deliver signals to user space processes. For KVM this triggers the world switch, a quick spin round vcpu_run, then back into the guest, unless there are pending signals. Add sdei_mask_local_cpu() calls to the smp_send_stop() code, this covers the panic() code-path, which doesn't invoke cpuhotplug notifiers. Because we can interrupt entry-from/exit-to another EL, we can't trust the value in sp_el0 or x29, even if we interrupted the kernel, in this case the code in entry.S will save/restore sp_el0 and use the value in __entry_task. When we have VMAP stacks we can interrupt the stack-overflow test, which stirs x0 into sp, meaning we have to have our own VMAP stacks. For now these are allocated when we probe the interface. Future patches will add refcounting hooks to allow the arch code to allocate them lazily. Signed-off-by: James Morse <james.morse@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-01-08 15:38:12 +00:00
#include <asm/sdei.h>
struct stackframe {
unsigned long fp;
unsigned long pc;
arm64: ftrace: fix a stack tracer's output under function graph tracer Function graph tracer modifies a return address (LR) in a stack frame to hook a function return. This will result in many useless entries (return_to_handler) showing up in a) a stack tracer's output b) perf call graph (with perf record -g) c) dump_backtrace (at panic et al.) For example, in case of a), $ echo function_graph > /sys/kernel/debug/tracing/current_tracer $ echo 1 > /proc/sys/kernel/stack_trace_enabled $ cat /sys/kernel/debug/tracing/stack_trace Depth Size Location (54 entries) ----- ---- -------- 0) 4504 16 gic_raise_softirq+0x28/0x150 1) 4488 80 smp_cross_call+0x38/0xb8 2) 4408 48 return_to_handler+0x0/0x40 3) 4360 32 return_to_handler+0x0/0x40 ... In case of b), $ echo function_graph > /sys/kernel/debug/tracing/current_tracer $ perf record -e mem:XXX:x -ag -- sleep 10 $ perf report ... | | |--0.22%-- 0x550f8 | | | 0x10888 | | | el0_svc_naked | | | sys_openat | | | return_to_handler | | | return_to_handler ... In case of c), $ echo function_graph > /sys/kernel/debug/tracing/current_tracer $ echo c > /proc/sysrq-trigger ... Call trace: [<ffffffc00044d3ac>] sysrq_handle_crash+0x24/0x30 [<ffffffc000092250>] return_to_handler+0x0/0x40 [<ffffffc000092250>] return_to_handler+0x0/0x40 ... This patch replaces such entries with real addresses preserved in current->ret_stack[] at unwind_frame(). This way, we can cover all the cases. Reviewed-by: Jungseok Lee <jungseoklee85@gmail.com> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> [will: fixed minor context changes conflicting with irq stack bits] Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-12-15 08:33:41 +00:00
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
arm64: fix unwind_frame() for filtered out fn for function graph tracing do_task_stat() calls get_wchan(), which further does unwind_frame(). unwind_frame() restores frame->pc to original value in case function graph tracer has modified a return address (LR) in a stack frame to hook a function return. However, if function graph tracer has hit a filtered function, then we can't unwind it as ftrace_push_return_trace() has biased the index(frame->graph) with a 'huge negative' offset(-FTRACE_NOTRACE_DEPTH). Moreover, arm64 stack walker defines index(frame->graph) as unsigned int, which can not compare a -ve number. Similar problem we can have with calling of walk_stackframe() from save_stack_trace_tsk() or dump_backtrace(). This patch fixes unwind_frame() to test the index for -ve value and restore index accordingly before we can restore frame->pc. Reproducer: cd /sys/kernel/debug/tracing/ echo schedule > set_graph_notrace echo 1 > options/display-graph echo wakeup > current_tracer ps -ef | grep -i agent Above commands result in: Unable to handle kernel paging request at virtual address ffff801bd3d1e000 pgd = ffff8003cbe97c00 [ffff801bd3d1e000] *pgd=0000000000000000, *pud=0000000000000000 Internal error: Oops: 96000006 [#1] SMP [...] CPU: 5 PID: 11696 Comm: ps Not tainted 4.11.0+ #33 [...] task: ffff8003c21ba000 task.stack: ffff8003cc6c0000 PC is at unwind_frame+0x12c/0x180 LR is at get_wchan+0xd4/0x134 pc : [<ffff00000808892c>] lr : [<ffff0000080860b8>] pstate: 60000145 sp : ffff8003cc6c3ab0 x29: ffff8003cc6c3ab0 x28: 0000000000000001 x27: 0000000000000026 x26: 0000000000000026 x25: 00000000000012d8 x24: 0000000000000000 x23: ffff8003c1c04000 x22: ffff000008c83000 x21: ffff8003c1c00000 x20: 000000000000000f x19: ffff8003c1bc0000 x18: 0000fffffc593690 x17: 0000000000000000 x16: 0000000000000001 x15: 0000b855670e2b60 x14: 0003e97f22cf1d0f x13: 0000000000000001 x12: 0000000000000000 x11: 00000000e8f4883e x10: 0000000154f47ec8 x9 : 0000000070f367c0 x8 : 0000000000000000 x7 : 00008003f7290000 x6 : 0000000000000018 x5 : 0000000000000000 x4 : ffff8003c1c03cb0 x3 : ffff8003c1c03ca0 x2 : 00000017ffe80000 x1 : ffff8003cc6c3af8 x0 : ffff8003d3e9e000 Process ps (pid: 11696, stack limit = 0xffff8003cc6c0000) Stack: (0xffff8003cc6c3ab0 to 0xffff8003cc6c4000) [...] [<ffff00000808892c>] unwind_frame+0x12c/0x180 [<ffff000008305008>] do_task_stat+0x864/0x870 [<ffff000008305c44>] proc_tgid_stat+0x3c/0x48 [<ffff0000082fde0c>] proc_single_show+0x5c/0xb8 [<ffff0000082b27e0>] seq_read+0x160/0x414 [<ffff000008289e6c>] __vfs_read+0x58/0x164 [<ffff00000828b164>] vfs_read+0x88/0x144 [<ffff00000828c2e8>] SyS_read+0x60/0xc0 [<ffff0000080834a0>] __sys_trace_return+0x0/0x4 Fixes: 20380bb390a4 (arm64: ftrace: fix a stack tracer's output under function graph tracer) Signed-off-by: Pratyush Anand <panand@redhat.com> Signed-off-by: Jerome Marchand <jmarchan@redhat.com> [catalin.marinas@arm.com: replace WARN_ON with WARN_ON_ONCE] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-02-05 13:28:01 +00:00
int graph;
arm64: ftrace: fix a stack tracer's output under function graph tracer Function graph tracer modifies a return address (LR) in a stack frame to hook a function return. This will result in many useless entries (return_to_handler) showing up in a) a stack tracer's output b) perf call graph (with perf record -g) c) dump_backtrace (at panic et al.) For example, in case of a), $ echo function_graph > /sys/kernel/debug/tracing/current_tracer $ echo 1 > /proc/sys/kernel/stack_trace_enabled $ cat /sys/kernel/debug/tracing/stack_trace Depth Size Location (54 entries) ----- ---- -------- 0) 4504 16 gic_raise_softirq+0x28/0x150 1) 4488 80 smp_cross_call+0x38/0xb8 2) 4408 48 return_to_handler+0x0/0x40 3) 4360 32 return_to_handler+0x0/0x40 ... In case of b), $ echo function_graph > /sys/kernel/debug/tracing/current_tracer $ perf record -e mem:XXX:x -ag -- sleep 10 $ perf report ... | | |--0.22%-- 0x550f8 | | | 0x10888 | | | el0_svc_naked | | | sys_openat | | | return_to_handler | | | return_to_handler ... In case of c), $ echo function_graph > /sys/kernel/debug/tracing/current_tracer $ echo c > /proc/sysrq-trigger ... Call trace: [<ffffffc00044d3ac>] sysrq_handle_crash+0x24/0x30 [<ffffffc000092250>] return_to_handler+0x0/0x40 [<ffffffc000092250>] return_to_handler+0x0/0x40 ... This patch replaces such entries with real addresses preserved in current->ret_stack[] at unwind_frame(). This way, we can cover all the cases. Reviewed-by: Jungseok Lee <jungseoklee85@gmail.com> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org> [will: fixed minor context changes conflicting with irq stack bits] Signed-off-by: Will Deacon <will.deacon@arm.com>
2015-12-15 08:33:41 +00:00
#endif
};
enum stack_type {
STACK_TYPE_UNKNOWN,
STACK_TYPE_TASK,
STACK_TYPE_IRQ,
STACK_TYPE_OVERFLOW,
STACK_TYPE_SDEI_NORMAL,
STACK_TYPE_SDEI_CRITICAL,
};
struct stack_info {
unsigned long low;
unsigned long high;
enum stack_type type;
};
extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame);
extern void walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
int (*fn)(struct stackframe *, void *), void *data);
extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk);
DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);
static inline bool on_irq_stack(unsigned long sp,
struct stack_info *info)
{
unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr);
unsigned long high = low + IRQ_STACK_SIZE;
if (!low)
return false;
if (sp < low || sp >= high)
return false;
if (info) {
info->low = low;
info->high = high;
info->type = STACK_TYPE_IRQ;
}
return true;
}
static inline bool on_task_stack(const struct task_struct *tsk,
unsigned long sp,
struct stack_info *info)
{
unsigned long low = (unsigned long)task_stack_page(tsk);
unsigned long high = low + THREAD_SIZE;
if (sp < low || sp >= high)
return false;
if (info) {
info->low = low;
info->high = high;
info->type = STACK_TYPE_TASK;
}
return true;
}
arm64: add VMAP_STACK overflow detection This patch adds stack overflow detection to arm64, usable when vmap'd stacks are in use. Overflow is detected in a small preamble executed for each exception entry, which checks whether there is enough space on the current stack for the general purpose registers to be saved. If there is not enough space, the overflow handler is invoked on a per-cpu overflow stack. This approach preserves the original exception information in ESR_EL1 (and where appropriate, FAR_EL1). Task and IRQ stacks are aligned to double their size, enabling overflow to be detected with a single bit test. For example, a 16K stack is aligned to 32K, ensuring that bit 14 of the SP must be zero. On an overflow (or underflow), this bit is flipped. Thus, overflow (of less than the size of the stack) can be detected by testing whether this bit is set. The overflow check is performed before any attempt is made to access the stack, avoiding recursive faults (and the loss of exception information these would entail). As logical operations cannot be performed on the SP directly, the SP is temporarily swapped with a general purpose register using arithmetic operations to enable the test to be performed. This gives us a useful error message on stack overflow, as can be trigger with the LKDTM overflow test: [ 305.388749] lkdtm: Performing direct entry OVERFLOW [ 305.395444] Insufficient stack space to handle exception! [ 305.395482] ESR: 0x96000047 -- DABT (current EL) [ 305.399890] FAR: 0xffff00000a5e7f30 [ 305.401315] Task stack: [0xffff00000a5e8000..0xffff00000a5ec000] [ 305.403815] IRQ stack: [0xffff000008000000..0xffff000008004000] [ 305.407035] Overflow stack: [0xffff80003efce4e0..0xffff80003efcf4e0] [ 305.409622] CPU: 0 PID: 1219 Comm: sh Not tainted 4.13.0-rc3-00021-g9636aea #5 [ 305.412785] Hardware name: linux,dummy-virt (DT) [ 305.415756] task: ffff80003d051c00 task.stack: ffff00000a5e8000 [ 305.419221] PC is at recursive_loop+0x10/0x48 [ 305.421637] LR is at recursive_loop+0x38/0x48 [ 305.423768] pc : [<ffff00000859f330>] lr : [<ffff00000859f358>] pstate: 40000145 [ 305.428020] sp : ffff00000a5e7f50 [ 305.430469] x29: ffff00000a5e8350 x28: ffff80003d051c00 [ 305.433191] x27: ffff000008981000 x26: ffff000008f80400 [ 305.439012] x25: ffff00000a5ebeb8 x24: ffff00000a5ebeb8 [ 305.440369] x23: ffff000008f80138 x22: 0000000000000009 [ 305.442241] x21: ffff80003ce65000 x20: ffff000008f80188 [ 305.444552] x19: 0000000000000013 x18: 0000000000000006 [ 305.446032] x17: 0000ffffa2601280 x16: ffff0000081fe0b8 [ 305.448252] x15: ffff000008ff546d x14: 000000000047a4c8 [ 305.450246] x13: ffff000008ff7872 x12: 0000000005f5e0ff [ 305.452953] x11: ffff000008ed2548 x10: 000000000005ee8d [ 305.454824] x9 : ffff000008545380 x8 : ffff00000a5e8770 [ 305.457105] x7 : 1313131313131313 x6 : 00000000000000e1 [ 305.459285] x5 : 0000000000000000 x4 : 0000000000000000 [ 305.461781] x3 : 0000000000000000 x2 : 0000000000000400 [ 305.465119] x1 : 0000000000000013 x0 : 0000000000000012 [ 305.467724] Kernel panic - not syncing: kernel stack overflow [ 305.470561] CPU: 0 PID: 1219 Comm: sh Not tainted 4.13.0-rc3-00021-g9636aea #5 [ 305.473325] Hardware name: linux,dummy-virt (DT) [ 305.475070] Call trace: [ 305.476116] [<ffff000008088ad8>] dump_backtrace+0x0/0x378 [ 305.478991] [<ffff000008088e64>] show_stack+0x14/0x20 [ 305.481237] [<ffff00000895a178>] dump_stack+0x98/0xb8 [ 305.483294] [<ffff0000080c3288>] panic+0x118/0x280 [ 305.485673] [<ffff0000080c2e9c>] nmi_panic+0x6c/0x70 [ 305.486216] [<ffff000008089710>] handle_bad_stack+0x118/0x128 [ 305.486612] Exception stack(0xffff80003efcf3a0 to 0xffff80003efcf4e0) [ 305.487334] f3a0: 0000000000000012 0000000000000013 0000000000000400 0000000000000000 [ 305.488025] f3c0: 0000000000000000 0000000000000000 00000000000000e1 1313131313131313 [ 305.488908] f3e0: ffff00000a5e8770 ffff000008545380 000000000005ee8d ffff000008ed2548 [ 305.489403] f400: 0000000005f5e0ff ffff000008ff7872 000000000047a4c8 ffff000008ff546d [ 305.489759] f420: ffff0000081fe0b8 0000ffffa2601280 0000000000000006 0000000000000013 [ 305.490256] f440: ffff000008f80188 ffff80003ce65000 0000000000000009 ffff000008f80138 [ 305.490683] f460: ffff00000a5ebeb8 ffff00000a5ebeb8 ffff000008f80400 ffff000008981000 [ 305.491051] f480: ffff80003d051c00 ffff00000a5e8350 ffff00000859f358 ffff00000a5e7f50 [ 305.491444] f4a0: ffff00000859f330 0000000040000145 0000000000000000 0000000000000000 [ 305.492008] f4c0: 0001000000000000 0000000000000000 ffff00000a5e8350 ffff00000859f330 [ 305.493063] [<ffff00000808205c>] __bad_stack+0x88/0x8c [ 305.493396] [<ffff00000859f330>] recursive_loop+0x10/0x48 [ 305.493731] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494088] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494425] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494649] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494898] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495205] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495453] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495708] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496000] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496302] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496644] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496894] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.497138] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.497325] [<ffff00000859f3dc>] lkdtm_OVERFLOW+0x14/0x20 [ 305.497506] [<ffff00000859f314>] lkdtm_do_action+0x1c/0x28 [ 305.497786] [<ffff00000859f178>] direct_entry+0xe0/0x170 [ 305.498095] [<ffff000008345568>] full_proxy_write+0x60/0xa8 [ 305.498387] [<ffff0000081fb7f4>] __vfs_write+0x1c/0x128 [ 305.498679] [<ffff0000081fcc68>] vfs_write+0xa0/0x1b0 [ 305.498926] [<ffff0000081fe0fc>] SyS_write+0x44/0xa0 [ 305.499182] Exception stack(0xffff00000a5ebec0 to 0xffff00000a5ec000) [ 305.499429] bec0: 0000000000000001 000000001c4cf5e0 0000000000000009 000000001c4cf5e0 [ 305.499674] bee0: 574f4c465245564f 0000000000000000 0000000000000000 8000000080808080 [ 305.499904] bf00: 0000000000000040 0000000000000038 fefefeff1b4bc2ff 7f7f7f7f7f7fff7f [ 305.500189] bf20: 0101010101010101 0000000000000000 000000000047a4c8 0000000000000038 [ 305.500712] bf40: 0000000000000000 0000ffffa2601280 0000ffffc63f6068 00000000004b5000 [ 305.501241] bf60: 0000000000000001 000000001c4cf5e0 0000000000000009 000000001c4cf5e0 [ 305.501791] bf80: 0000000000000020 0000000000000000 00000000004b5000 000000001c4cc458 [ 305.502314] bfa0: 0000000000000000 0000ffffc63f7950 000000000040a3c4 0000ffffc63f70e0 [ 305.502762] bfc0: 0000ffffa2601268 0000000080000000 0000000000000001 0000000000000040 [ 305.503207] bfe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 305.503680] [<ffff000008082fb0>] el0_svc_naked+0x24/0x28 [ 305.504720] Kernel Offset: disabled [ 305.505189] CPU features: 0x002082 [ 305.505473] Memory Limit: none [ 305.506181] ---[ end Kernel panic - not syncing: kernel stack overflow This patch was co-authored by Ard Biesheuvel and Mark Rutland. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Tested-by: Laura Abbott <labbott@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com>
2017-07-14 19:30:35 +00:00
#ifdef CONFIG_VMAP_STACK
DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);
static inline bool on_overflow_stack(unsigned long sp,
struct stack_info *info)
arm64: add VMAP_STACK overflow detection This patch adds stack overflow detection to arm64, usable when vmap'd stacks are in use. Overflow is detected in a small preamble executed for each exception entry, which checks whether there is enough space on the current stack for the general purpose registers to be saved. If there is not enough space, the overflow handler is invoked on a per-cpu overflow stack. This approach preserves the original exception information in ESR_EL1 (and where appropriate, FAR_EL1). Task and IRQ stacks are aligned to double their size, enabling overflow to be detected with a single bit test. For example, a 16K stack is aligned to 32K, ensuring that bit 14 of the SP must be zero. On an overflow (or underflow), this bit is flipped. Thus, overflow (of less than the size of the stack) can be detected by testing whether this bit is set. The overflow check is performed before any attempt is made to access the stack, avoiding recursive faults (and the loss of exception information these would entail). As logical operations cannot be performed on the SP directly, the SP is temporarily swapped with a general purpose register using arithmetic operations to enable the test to be performed. This gives us a useful error message on stack overflow, as can be trigger with the LKDTM overflow test: [ 305.388749] lkdtm: Performing direct entry OVERFLOW [ 305.395444] Insufficient stack space to handle exception! [ 305.395482] ESR: 0x96000047 -- DABT (current EL) [ 305.399890] FAR: 0xffff00000a5e7f30 [ 305.401315] Task stack: [0xffff00000a5e8000..0xffff00000a5ec000] [ 305.403815] IRQ stack: [0xffff000008000000..0xffff000008004000] [ 305.407035] Overflow stack: [0xffff80003efce4e0..0xffff80003efcf4e0] [ 305.409622] CPU: 0 PID: 1219 Comm: sh Not tainted 4.13.0-rc3-00021-g9636aea #5 [ 305.412785] Hardware name: linux,dummy-virt (DT) [ 305.415756] task: ffff80003d051c00 task.stack: ffff00000a5e8000 [ 305.419221] PC is at recursive_loop+0x10/0x48 [ 305.421637] LR is at recursive_loop+0x38/0x48 [ 305.423768] pc : [<ffff00000859f330>] lr : [<ffff00000859f358>] pstate: 40000145 [ 305.428020] sp : ffff00000a5e7f50 [ 305.430469] x29: ffff00000a5e8350 x28: ffff80003d051c00 [ 305.433191] x27: ffff000008981000 x26: ffff000008f80400 [ 305.439012] x25: ffff00000a5ebeb8 x24: ffff00000a5ebeb8 [ 305.440369] x23: ffff000008f80138 x22: 0000000000000009 [ 305.442241] x21: ffff80003ce65000 x20: ffff000008f80188 [ 305.444552] x19: 0000000000000013 x18: 0000000000000006 [ 305.446032] x17: 0000ffffa2601280 x16: ffff0000081fe0b8 [ 305.448252] x15: ffff000008ff546d x14: 000000000047a4c8 [ 305.450246] x13: ffff000008ff7872 x12: 0000000005f5e0ff [ 305.452953] x11: ffff000008ed2548 x10: 000000000005ee8d [ 305.454824] x9 : ffff000008545380 x8 : ffff00000a5e8770 [ 305.457105] x7 : 1313131313131313 x6 : 00000000000000e1 [ 305.459285] x5 : 0000000000000000 x4 : 0000000000000000 [ 305.461781] x3 : 0000000000000000 x2 : 0000000000000400 [ 305.465119] x1 : 0000000000000013 x0 : 0000000000000012 [ 305.467724] Kernel panic - not syncing: kernel stack overflow [ 305.470561] CPU: 0 PID: 1219 Comm: sh Not tainted 4.13.0-rc3-00021-g9636aea #5 [ 305.473325] Hardware name: linux,dummy-virt (DT) [ 305.475070] Call trace: [ 305.476116] [<ffff000008088ad8>] dump_backtrace+0x0/0x378 [ 305.478991] [<ffff000008088e64>] show_stack+0x14/0x20 [ 305.481237] [<ffff00000895a178>] dump_stack+0x98/0xb8 [ 305.483294] [<ffff0000080c3288>] panic+0x118/0x280 [ 305.485673] [<ffff0000080c2e9c>] nmi_panic+0x6c/0x70 [ 305.486216] [<ffff000008089710>] handle_bad_stack+0x118/0x128 [ 305.486612] Exception stack(0xffff80003efcf3a0 to 0xffff80003efcf4e0) [ 305.487334] f3a0: 0000000000000012 0000000000000013 0000000000000400 0000000000000000 [ 305.488025] f3c0: 0000000000000000 0000000000000000 00000000000000e1 1313131313131313 [ 305.488908] f3e0: ffff00000a5e8770 ffff000008545380 000000000005ee8d ffff000008ed2548 [ 305.489403] f400: 0000000005f5e0ff ffff000008ff7872 000000000047a4c8 ffff000008ff546d [ 305.489759] f420: ffff0000081fe0b8 0000ffffa2601280 0000000000000006 0000000000000013 [ 305.490256] f440: ffff000008f80188 ffff80003ce65000 0000000000000009 ffff000008f80138 [ 305.490683] f460: ffff00000a5ebeb8 ffff00000a5ebeb8 ffff000008f80400 ffff000008981000 [ 305.491051] f480: ffff80003d051c00 ffff00000a5e8350 ffff00000859f358 ffff00000a5e7f50 [ 305.491444] f4a0: ffff00000859f330 0000000040000145 0000000000000000 0000000000000000 [ 305.492008] f4c0: 0001000000000000 0000000000000000 ffff00000a5e8350 ffff00000859f330 [ 305.493063] [<ffff00000808205c>] __bad_stack+0x88/0x8c [ 305.493396] [<ffff00000859f330>] recursive_loop+0x10/0x48 [ 305.493731] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494088] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494425] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494649] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494898] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495205] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495453] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495708] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496000] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496302] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496644] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496894] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.497138] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.497325] [<ffff00000859f3dc>] lkdtm_OVERFLOW+0x14/0x20 [ 305.497506] [<ffff00000859f314>] lkdtm_do_action+0x1c/0x28 [ 305.497786] [<ffff00000859f178>] direct_entry+0xe0/0x170 [ 305.498095] [<ffff000008345568>] full_proxy_write+0x60/0xa8 [ 305.498387] [<ffff0000081fb7f4>] __vfs_write+0x1c/0x128 [ 305.498679] [<ffff0000081fcc68>] vfs_write+0xa0/0x1b0 [ 305.498926] [<ffff0000081fe0fc>] SyS_write+0x44/0xa0 [ 305.499182] Exception stack(0xffff00000a5ebec0 to 0xffff00000a5ec000) [ 305.499429] bec0: 0000000000000001 000000001c4cf5e0 0000000000000009 000000001c4cf5e0 [ 305.499674] bee0: 574f4c465245564f 0000000000000000 0000000000000000 8000000080808080 [ 305.499904] bf00: 0000000000000040 0000000000000038 fefefeff1b4bc2ff 7f7f7f7f7f7fff7f [ 305.500189] bf20: 0101010101010101 0000000000000000 000000000047a4c8 0000000000000038 [ 305.500712] bf40: 0000000000000000 0000ffffa2601280 0000ffffc63f6068 00000000004b5000 [ 305.501241] bf60: 0000000000000001 000000001c4cf5e0 0000000000000009 000000001c4cf5e0 [ 305.501791] bf80: 0000000000000020 0000000000000000 00000000004b5000 000000001c4cc458 [ 305.502314] bfa0: 0000000000000000 0000ffffc63f7950 000000000040a3c4 0000ffffc63f70e0 [ 305.502762] bfc0: 0000ffffa2601268 0000000080000000 0000000000000001 0000000000000040 [ 305.503207] bfe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 305.503680] [<ffff000008082fb0>] el0_svc_naked+0x24/0x28 [ 305.504720] Kernel Offset: disabled [ 305.505189] CPU features: 0x002082 [ 305.505473] Memory Limit: none [ 305.506181] ---[ end Kernel panic - not syncing: kernel stack overflow This patch was co-authored by Ard Biesheuvel and Mark Rutland. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Tested-by: Laura Abbott <labbott@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com>
2017-07-14 19:30:35 +00:00
{
unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack);
unsigned long high = low + OVERFLOW_STACK_SIZE;
if (sp < low || sp >= high)
return false;
if (info) {
info->low = low;
info->high = high;
info->type = STACK_TYPE_OVERFLOW;
}
return true;
arm64: add VMAP_STACK overflow detection This patch adds stack overflow detection to arm64, usable when vmap'd stacks are in use. Overflow is detected in a small preamble executed for each exception entry, which checks whether there is enough space on the current stack for the general purpose registers to be saved. If there is not enough space, the overflow handler is invoked on a per-cpu overflow stack. This approach preserves the original exception information in ESR_EL1 (and where appropriate, FAR_EL1). Task and IRQ stacks are aligned to double their size, enabling overflow to be detected with a single bit test. For example, a 16K stack is aligned to 32K, ensuring that bit 14 of the SP must be zero. On an overflow (or underflow), this bit is flipped. Thus, overflow (of less than the size of the stack) can be detected by testing whether this bit is set. The overflow check is performed before any attempt is made to access the stack, avoiding recursive faults (and the loss of exception information these would entail). As logical operations cannot be performed on the SP directly, the SP is temporarily swapped with a general purpose register using arithmetic operations to enable the test to be performed. This gives us a useful error message on stack overflow, as can be trigger with the LKDTM overflow test: [ 305.388749] lkdtm: Performing direct entry OVERFLOW [ 305.395444] Insufficient stack space to handle exception! [ 305.395482] ESR: 0x96000047 -- DABT (current EL) [ 305.399890] FAR: 0xffff00000a5e7f30 [ 305.401315] Task stack: [0xffff00000a5e8000..0xffff00000a5ec000] [ 305.403815] IRQ stack: [0xffff000008000000..0xffff000008004000] [ 305.407035] Overflow stack: [0xffff80003efce4e0..0xffff80003efcf4e0] [ 305.409622] CPU: 0 PID: 1219 Comm: sh Not tainted 4.13.0-rc3-00021-g9636aea #5 [ 305.412785] Hardware name: linux,dummy-virt (DT) [ 305.415756] task: ffff80003d051c00 task.stack: ffff00000a5e8000 [ 305.419221] PC is at recursive_loop+0x10/0x48 [ 305.421637] LR is at recursive_loop+0x38/0x48 [ 305.423768] pc : [<ffff00000859f330>] lr : [<ffff00000859f358>] pstate: 40000145 [ 305.428020] sp : ffff00000a5e7f50 [ 305.430469] x29: ffff00000a5e8350 x28: ffff80003d051c00 [ 305.433191] x27: ffff000008981000 x26: ffff000008f80400 [ 305.439012] x25: ffff00000a5ebeb8 x24: ffff00000a5ebeb8 [ 305.440369] x23: ffff000008f80138 x22: 0000000000000009 [ 305.442241] x21: ffff80003ce65000 x20: ffff000008f80188 [ 305.444552] x19: 0000000000000013 x18: 0000000000000006 [ 305.446032] x17: 0000ffffa2601280 x16: ffff0000081fe0b8 [ 305.448252] x15: ffff000008ff546d x14: 000000000047a4c8 [ 305.450246] x13: ffff000008ff7872 x12: 0000000005f5e0ff [ 305.452953] x11: ffff000008ed2548 x10: 000000000005ee8d [ 305.454824] x9 : ffff000008545380 x8 : ffff00000a5e8770 [ 305.457105] x7 : 1313131313131313 x6 : 00000000000000e1 [ 305.459285] x5 : 0000000000000000 x4 : 0000000000000000 [ 305.461781] x3 : 0000000000000000 x2 : 0000000000000400 [ 305.465119] x1 : 0000000000000013 x0 : 0000000000000012 [ 305.467724] Kernel panic - not syncing: kernel stack overflow [ 305.470561] CPU: 0 PID: 1219 Comm: sh Not tainted 4.13.0-rc3-00021-g9636aea #5 [ 305.473325] Hardware name: linux,dummy-virt (DT) [ 305.475070] Call trace: [ 305.476116] [<ffff000008088ad8>] dump_backtrace+0x0/0x378 [ 305.478991] [<ffff000008088e64>] show_stack+0x14/0x20 [ 305.481237] [<ffff00000895a178>] dump_stack+0x98/0xb8 [ 305.483294] [<ffff0000080c3288>] panic+0x118/0x280 [ 305.485673] [<ffff0000080c2e9c>] nmi_panic+0x6c/0x70 [ 305.486216] [<ffff000008089710>] handle_bad_stack+0x118/0x128 [ 305.486612] Exception stack(0xffff80003efcf3a0 to 0xffff80003efcf4e0) [ 305.487334] f3a0: 0000000000000012 0000000000000013 0000000000000400 0000000000000000 [ 305.488025] f3c0: 0000000000000000 0000000000000000 00000000000000e1 1313131313131313 [ 305.488908] f3e0: ffff00000a5e8770 ffff000008545380 000000000005ee8d ffff000008ed2548 [ 305.489403] f400: 0000000005f5e0ff ffff000008ff7872 000000000047a4c8 ffff000008ff546d [ 305.489759] f420: ffff0000081fe0b8 0000ffffa2601280 0000000000000006 0000000000000013 [ 305.490256] f440: ffff000008f80188 ffff80003ce65000 0000000000000009 ffff000008f80138 [ 305.490683] f460: ffff00000a5ebeb8 ffff00000a5ebeb8 ffff000008f80400 ffff000008981000 [ 305.491051] f480: ffff80003d051c00 ffff00000a5e8350 ffff00000859f358 ffff00000a5e7f50 [ 305.491444] f4a0: ffff00000859f330 0000000040000145 0000000000000000 0000000000000000 [ 305.492008] f4c0: 0001000000000000 0000000000000000 ffff00000a5e8350 ffff00000859f330 [ 305.493063] [<ffff00000808205c>] __bad_stack+0x88/0x8c [ 305.493396] [<ffff00000859f330>] recursive_loop+0x10/0x48 [ 305.493731] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494088] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494425] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494649] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494898] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495205] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495453] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495708] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496000] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496302] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496644] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496894] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.497138] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.497325] [<ffff00000859f3dc>] lkdtm_OVERFLOW+0x14/0x20 [ 305.497506] [<ffff00000859f314>] lkdtm_do_action+0x1c/0x28 [ 305.497786] [<ffff00000859f178>] direct_entry+0xe0/0x170 [ 305.498095] [<ffff000008345568>] full_proxy_write+0x60/0xa8 [ 305.498387] [<ffff0000081fb7f4>] __vfs_write+0x1c/0x128 [ 305.498679] [<ffff0000081fcc68>] vfs_write+0xa0/0x1b0 [ 305.498926] [<ffff0000081fe0fc>] SyS_write+0x44/0xa0 [ 305.499182] Exception stack(0xffff00000a5ebec0 to 0xffff00000a5ec000) [ 305.499429] bec0: 0000000000000001 000000001c4cf5e0 0000000000000009 000000001c4cf5e0 [ 305.499674] bee0: 574f4c465245564f 0000000000000000 0000000000000000 8000000080808080 [ 305.499904] bf00: 0000000000000040 0000000000000038 fefefeff1b4bc2ff 7f7f7f7f7f7fff7f [ 305.500189] bf20: 0101010101010101 0000000000000000 000000000047a4c8 0000000000000038 [ 305.500712] bf40: 0000000000000000 0000ffffa2601280 0000ffffc63f6068 00000000004b5000 [ 305.501241] bf60: 0000000000000001 000000001c4cf5e0 0000000000000009 000000001c4cf5e0 [ 305.501791] bf80: 0000000000000020 0000000000000000 00000000004b5000 000000001c4cc458 [ 305.502314] bfa0: 0000000000000000 0000ffffc63f7950 000000000040a3c4 0000ffffc63f70e0 [ 305.502762] bfc0: 0000ffffa2601268 0000000080000000 0000000000000001 0000000000000040 [ 305.503207] bfe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 305.503680] [<ffff000008082fb0>] el0_svc_naked+0x24/0x28 [ 305.504720] Kernel Offset: disabled [ 305.505189] CPU features: 0x002082 [ 305.505473] Memory Limit: none [ 305.506181] ---[ end Kernel panic - not syncing: kernel stack overflow This patch was co-authored by Ard Biesheuvel and Mark Rutland. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Tested-by: Laura Abbott <labbott@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com>
2017-07-14 19:30:35 +00:00
}
#else
static inline bool on_overflow_stack(unsigned long sp,
struct stack_info *info) { return false; }
arm64: add VMAP_STACK overflow detection This patch adds stack overflow detection to arm64, usable when vmap'd stacks are in use. Overflow is detected in a small preamble executed for each exception entry, which checks whether there is enough space on the current stack for the general purpose registers to be saved. If there is not enough space, the overflow handler is invoked on a per-cpu overflow stack. This approach preserves the original exception information in ESR_EL1 (and where appropriate, FAR_EL1). Task and IRQ stacks are aligned to double their size, enabling overflow to be detected with a single bit test. For example, a 16K stack is aligned to 32K, ensuring that bit 14 of the SP must be zero. On an overflow (or underflow), this bit is flipped. Thus, overflow (of less than the size of the stack) can be detected by testing whether this bit is set. The overflow check is performed before any attempt is made to access the stack, avoiding recursive faults (and the loss of exception information these would entail). As logical operations cannot be performed on the SP directly, the SP is temporarily swapped with a general purpose register using arithmetic operations to enable the test to be performed. This gives us a useful error message on stack overflow, as can be trigger with the LKDTM overflow test: [ 305.388749] lkdtm: Performing direct entry OVERFLOW [ 305.395444] Insufficient stack space to handle exception! [ 305.395482] ESR: 0x96000047 -- DABT (current EL) [ 305.399890] FAR: 0xffff00000a5e7f30 [ 305.401315] Task stack: [0xffff00000a5e8000..0xffff00000a5ec000] [ 305.403815] IRQ stack: [0xffff000008000000..0xffff000008004000] [ 305.407035] Overflow stack: [0xffff80003efce4e0..0xffff80003efcf4e0] [ 305.409622] CPU: 0 PID: 1219 Comm: sh Not tainted 4.13.0-rc3-00021-g9636aea #5 [ 305.412785] Hardware name: linux,dummy-virt (DT) [ 305.415756] task: ffff80003d051c00 task.stack: ffff00000a5e8000 [ 305.419221] PC is at recursive_loop+0x10/0x48 [ 305.421637] LR is at recursive_loop+0x38/0x48 [ 305.423768] pc : [<ffff00000859f330>] lr : [<ffff00000859f358>] pstate: 40000145 [ 305.428020] sp : ffff00000a5e7f50 [ 305.430469] x29: ffff00000a5e8350 x28: ffff80003d051c00 [ 305.433191] x27: ffff000008981000 x26: ffff000008f80400 [ 305.439012] x25: ffff00000a5ebeb8 x24: ffff00000a5ebeb8 [ 305.440369] x23: ffff000008f80138 x22: 0000000000000009 [ 305.442241] x21: ffff80003ce65000 x20: ffff000008f80188 [ 305.444552] x19: 0000000000000013 x18: 0000000000000006 [ 305.446032] x17: 0000ffffa2601280 x16: ffff0000081fe0b8 [ 305.448252] x15: ffff000008ff546d x14: 000000000047a4c8 [ 305.450246] x13: ffff000008ff7872 x12: 0000000005f5e0ff [ 305.452953] x11: ffff000008ed2548 x10: 000000000005ee8d [ 305.454824] x9 : ffff000008545380 x8 : ffff00000a5e8770 [ 305.457105] x7 : 1313131313131313 x6 : 00000000000000e1 [ 305.459285] x5 : 0000000000000000 x4 : 0000000000000000 [ 305.461781] x3 : 0000000000000000 x2 : 0000000000000400 [ 305.465119] x1 : 0000000000000013 x0 : 0000000000000012 [ 305.467724] Kernel panic - not syncing: kernel stack overflow [ 305.470561] CPU: 0 PID: 1219 Comm: sh Not tainted 4.13.0-rc3-00021-g9636aea #5 [ 305.473325] Hardware name: linux,dummy-virt (DT) [ 305.475070] Call trace: [ 305.476116] [<ffff000008088ad8>] dump_backtrace+0x0/0x378 [ 305.478991] [<ffff000008088e64>] show_stack+0x14/0x20 [ 305.481237] [<ffff00000895a178>] dump_stack+0x98/0xb8 [ 305.483294] [<ffff0000080c3288>] panic+0x118/0x280 [ 305.485673] [<ffff0000080c2e9c>] nmi_panic+0x6c/0x70 [ 305.486216] [<ffff000008089710>] handle_bad_stack+0x118/0x128 [ 305.486612] Exception stack(0xffff80003efcf3a0 to 0xffff80003efcf4e0) [ 305.487334] f3a0: 0000000000000012 0000000000000013 0000000000000400 0000000000000000 [ 305.488025] f3c0: 0000000000000000 0000000000000000 00000000000000e1 1313131313131313 [ 305.488908] f3e0: ffff00000a5e8770 ffff000008545380 000000000005ee8d ffff000008ed2548 [ 305.489403] f400: 0000000005f5e0ff ffff000008ff7872 000000000047a4c8 ffff000008ff546d [ 305.489759] f420: ffff0000081fe0b8 0000ffffa2601280 0000000000000006 0000000000000013 [ 305.490256] f440: ffff000008f80188 ffff80003ce65000 0000000000000009 ffff000008f80138 [ 305.490683] f460: ffff00000a5ebeb8 ffff00000a5ebeb8 ffff000008f80400 ffff000008981000 [ 305.491051] f480: ffff80003d051c00 ffff00000a5e8350 ffff00000859f358 ffff00000a5e7f50 [ 305.491444] f4a0: ffff00000859f330 0000000040000145 0000000000000000 0000000000000000 [ 305.492008] f4c0: 0001000000000000 0000000000000000 ffff00000a5e8350 ffff00000859f330 [ 305.493063] [<ffff00000808205c>] __bad_stack+0x88/0x8c [ 305.493396] [<ffff00000859f330>] recursive_loop+0x10/0x48 [ 305.493731] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494088] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494425] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494649] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494898] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495205] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495453] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495708] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496000] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496302] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496644] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496894] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.497138] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.497325] [<ffff00000859f3dc>] lkdtm_OVERFLOW+0x14/0x20 [ 305.497506] [<ffff00000859f314>] lkdtm_do_action+0x1c/0x28 [ 305.497786] [<ffff00000859f178>] direct_entry+0xe0/0x170 [ 305.498095] [<ffff000008345568>] full_proxy_write+0x60/0xa8 [ 305.498387] [<ffff0000081fb7f4>] __vfs_write+0x1c/0x128 [ 305.498679] [<ffff0000081fcc68>] vfs_write+0xa0/0x1b0 [ 305.498926] [<ffff0000081fe0fc>] SyS_write+0x44/0xa0 [ 305.499182] Exception stack(0xffff00000a5ebec0 to 0xffff00000a5ec000) [ 305.499429] bec0: 0000000000000001 000000001c4cf5e0 0000000000000009 000000001c4cf5e0 [ 305.499674] bee0: 574f4c465245564f 0000000000000000 0000000000000000 8000000080808080 [ 305.499904] bf00: 0000000000000040 0000000000000038 fefefeff1b4bc2ff 7f7f7f7f7f7fff7f [ 305.500189] bf20: 0101010101010101 0000000000000000 000000000047a4c8 0000000000000038 [ 305.500712] bf40: 0000000000000000 0000ffffa2601280 0000ffffc63f6068 00000000004b5000 [ 305.501241] bf60: 0000000000000001 000000001c4cf5e0 0000000000000009 000000001c4cf5e0 [ 305.501791] bf80: 0000000000000020 0000000000000000 00000000004b5000 000000001c4cc458 [ 305.502314] bfa0: 0000000000000000 0000ffffc63f7950 000000000040a3c4 0000ffffc63f70e0 [ 305.502762] bfc0: 0000ffffa2601268 0000000080000000 0000000000000001 0000000000000040 [ 305.503207] bfe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 305.503680] [<ffff000008082fb0>] el0_svc_naked+0x24/0x28 [ 305.504720] Kernel Offset: disabled [ 305.505189] CPU features: 0x002082 [ 305.505473] Memory Limit: none [ 305.506181] ---[ end Kernel panic - not syncing: kernel stack overflow This patch was co-authored by Ard Biesheuvel and Mark Rutland. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Tested-by: Laura Abbott <labbott@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com>
2017-07-14 19:30:35 +00:00
#endif
/*
* We can only safely access per-cpu stacks from current in a non-preemptible
* context.
*/
static inline bool on_accessible_stack(const struct task_struct *tsk,
unsigned long sp,
struct stack_info *info)
{
if (on_task_stack(tsk, sp, info))
return true;
if (tsk != current || preemptible())
return false;
if (on_irq_stack(sp, info))
return true;
if (on_overflow_stack(sp, info))
arm64: add VMAP_STACK overflow detection This patch adds stack overflow detection to arm64, usable when vmap'd stacks are in use. Overflow is detected in a small preamble executed for each exception entry, which checks whether there is enough space on the current stack for the general purpose registers to be saved. If there is not enough space, the overflow handler is invoked on a per-cpu overflow stack. This approach preserves the original exception information in ESR_EL1 (and where appropriate, FAR_EL1). Task and IRQ stacks are aligned to double their size, enabling overflow to be detected with a single bit test. For example, a 16K stack is aligned to 32K, ensuring that bit 14 of the SP must be zero. On an overflow (or underflow), this bit is flipped. Thus, overflow (of less than the size of the stack) can be detected by testing whether this bit is set. The overflow check is performed before any attempt is made to access the stack, avoiding recursive faults (and the loss of exception information these would entail). As logical operations cannot be performed on the SP directly, the SP is temporarily swapped with a general purpose register using arithmetic operations to enable the test to be performed. This gives us a useful error message on stack overflow, as can be trigger with the LKDTM overflow test: [ 305.388749] lkdtm: Performing direct entry OVERFLOW [ 305.395444] Insufficient stack space to handle exception! [ 305.395482] ESR: 0x96000047 -- DABT (current EL) [ 305.399890] FAR: 0xffff00000a5e7f30 [ 305.401315] Task stack: [0xffff00000a5e8000..0xffff00000a5ec000] [ 305.403815] IRQ stack: [0xffff000008000000..0xffff000008004000] [ 305.407035] Overflow stack: [0xffff80003efce4e0..0xffff80003efcf4e0] [ 305.409622] CPU: 0 PID: 1219 Comm: sh Not tainted 4.13.0-rc3-00021-g9636aea #5 [ 305.412785] Hardware name: linux,dummy-virt (DT) [ 305.415756] task: ffff80003d051c00 task.stack: ffff00000a5e8000 [ 305.419221] PC is at recursive_loop+0x10/0x48 [ 305.421637] LR is at recursive_loop+0x38/0x48 [ 305.423768] pc : [<ffff00000859f330>] lr : [<ffff00000859f358>] pstate: 40000145 [ 305.428020] sp : ffff00000a5e7f50 [ 305.430469] x29: ffff00000a5e8350 x28: ffff80003d051c00 [ 305.433191] x27: ffff000008981000 x26: ffff000008f80400 [ 305.439012] x25: ffff00000a5ebeb8 x24: ffff00000a5ebeb8 [ 305.440369] x23: ffff000008f80138 x22: 0000000000000009 [ 305.442241] x21: ffff80003ce65000 x20: ffff000008f80188 [ 305.444552] x19: 0000000000000013 x18: 0000000000000006 [ 305.446032] x17: 0000ffffa2601280 x16: ffff0000081fe0b8 [ 305.448252] x15: ffff000008ff546d x14: 000000000047a4c8 [ 305.450246] x13: ffff000008ff7872 x12: 0000000005f5e0ff [ 305.452953] x11: ffff000008ed2548 x10: 000000000005ee8d [ 305.454824] x9 : ffff000008545380 x8 : ffff00000a5e8770 [ 305.457105] x7 : 1313131313131313 x6 : 00000000000000e1 [ 305.459285] x5 : 0000000000000000 x4 : 0000000000000000 [ 305.461781] x3 : 0000000000000000 x2 : 0000000000000400 [ 305.465119] x1 : 0000000000000013 x0 : 0000000000000012 [ 305.467724] Kernel panic - not syncing: kernel stack overflow [ 305.470561] CPU: 0 PID: 1219 Comm: sh Not tainted 4.13.0-rc3-00021-g9636aea #5 [ 305.473325] Hardware name: linux,dummy-virt (DT) [ 305.475070] Call trace: [ 305.476116] [<ffff000008088ad8>] dump_backtrace+0x0/0x378 [ 305.478991] [<ffff000008088e64>] show_stack+0x14/0x20 [ 305.481237] [<ffff00000895a178>] dump_stack+0x98/0xb8 [ 305.483294] [<ffff0000080c3288>] panic+0x118/0x280 [ 305.485673] [<ffff0000080c2e9c>] nmi_panic+0x6c/0x70 [ 305.486216] [<ffff000008089710>] handle_bad_stack+0x118/0x128 [ 305.486612] Exception stack(0xffff80003efcf3a0 to 0xffff80003efcf4e0) [ 305.487334] f3a0: 0000000000000012 0000000000000013 0000000000000400 0000000000000000 [ 305.488025] f3c0: 0000000000000000 0000000000000000 00000000000000e1 1313131313131313 [ 305.488908] f3e0: ffff00000a5e8770 ffff000008545380 000000000005ee8d ffff000008ed2548 [ 305.489403] f400: 0000000005f5e0ff ffff000008ff7872 000000000047a4c8 ffff000008ff546d [ 305.489759] f420: ffff0000081fe0b8 0000ffffa2601280 0000000000000006 0000000000000013 [ 305.490256] f440: ffff000008f80188 ffff80003ce65000 0000000000000009 ffff000008f80138 [ 305.490683] f460: ffff00000a5ebeb8 ffff00000a5ebeb8 ffff000008f80400 ffff000008981000 [ 305.491051] f480: ffff80003d051c00 ffff00000a5e8350 ffff00000859f358 ffff00000a5e7f50 [ 305.491444] f4a0: ffff00000859f330 0000000040000145 0000000000000000 0000000000000000 [ 305.492008] f4c0: 0001000000000000 0000000000000000 ffff00000a5e8350 ffff00000859f330 [ 305.493063] [<ffff00000808205c>] __bad_stack+0x88/0x8c [ 305.493396] [<ffff00000859f330>] recursive_loop+0x10/0x48 [ 305.493731] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494088] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494425] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494649] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.494898] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495205] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495453] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.495708] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496000] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496302] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496644] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.496894] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.497138] [<ffff00000859f358>] recursive_loop+0x38/0x48 [ 305.497325] [<ffff00000859f3dc>] lkdtm_OVERFLOW+0x14/0x20 [ 305.497506] [<ffff00000859f314>] lkdtm_do_action+0x1c/0x28 [ 305.497786] [<ffff00000859f178>] direct_entry+0xe0/0x170 [ 305.498095] [<ffff000008345568>] full_proxy_write+0x60/0xa8 [ 305.498387] [<ffff0000081fb7f4>] __vfs_write+0x1c/0x128 [ 305.498679] [<ffff0000081fcc68>] vfs_write+0xa0/0x1b0 [ 305.498926] [<ffff0000081fe0fc>] SyS_write+0x44/0xa0 [ 305.499182] Exception stack(0xffff00000a5ebec0 to 0xffff00000a5ec000) [ 305.499429] bec0: 0000000000000001 000000001c4cf5e0 0000000000000009 000000001c4cf5e0 [ 305.499674] bee0: 574f4c465245564f 0000000000000000 0000000000000000 8000000080808080 [ 305.499904] bf00: 0000000000000040 0000000000000038 fefefeff1b4bc2ff 7f7f7f7f7f7fff7f [ 305.500189] bf20: 0101010101010101 0000000000000000 000000000047a4c8 0000000000000038 [ 305.500712] bf40: 0000000000000000 0000ffffa2601280 0000ffffc63f6068 00000000004b5000 [ 305.501241] bf60: 0000000000000001 000000001c4cf5e0 0000000000000009 000000001c4cf5e0 [ 305.501791] bf80: 0000000000000020 0000000000000000 00000000004b5000 000000001c4cc458 [ 305.502314] bfa0: 0000000000000000 0000ffffc63f7950 000000000040a3c4 0000ffffc63f70e0 [ 305.502762] bfc0: 0000ffffa2601268 0000000080000000 0000000000000001 0000000000000040 [ 305.503207] bfe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 [ 305.503680] [<ffff000008082fb0>] el0_svc_naked+0x24/0x28 [ 305.504720] Kernel Offset: disabled [ 305.505189] CPU features: 0x002082 [ 305.505473] Memory Limit: none [ 305.506181] ---[ end Kernel panic - not syncing: kernel stack overflow This patch was co-authored by Ard Biesheuvel and Mark Rutland. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Tested-by: Laura Abbott <labbott@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: James Morse <james.morse@arm.com>
2017-07-14 19:30:35 +00:00
return true;
if (on_sdei_stack(sp, info))
arm64: kernel: Add arch-specific SDEI entry code and CPU masking The Software Delegated Exception Interface (SDEI) is an ARM standard for registering callbacks from the platform firmware into the OS. This is typically used to implement RAS notifications. Such notifications enter the kernel at the registered entry-point with the register values of the interrupted CPU context. Because this is not a CPU exception, it cannot reuse the existing entry code. (crucially we don't implicitly know which exception level we interrupted), Add the entry point to entry.S to set us up for calling into C code. If the event interrupted code that had interrupts masked, we always return to that location. Otherwise we pretend this was an IRQ, and use SDEI's complete_and_resume call to return to vbar_el1 + offset. This allows the kernel to deliver signals to user space processes. For KVM this triggers the world switch, a quick spin round vcpu_run, then back into the guest, unless there are pending signals. Add sdei_mask_local_cpu() calls to the smp_send_stop() code, this covers the panic() code-path, which doesn't invoke cpuhotplug notifiers. Because we can interrupt entry-from/exit-to another EL, we can't trust the value in sp_el0 or x29, even if we interrupted the kernel, in this case the code in entry.S will save/restore sp_el0 and use the value in __entry_task. When we have VMAP stacks we can interrupt the stack-overflow test, which stirs x0 into sp, meaning we have to have our own VMAP stacks. For now these are allocated when we probe the interface. Future patches will add refcounting hooks to allow the arch code to allocate them lazily. Signed-off-by: James Morse <james.morse@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-01-08 15:38:12 +00:00
return true;
return false;
}
static inline void start_backtrace(struct stackframe *frame,
unsigned long fp, unsigned long pc)
{
frame->fp = fp;
frame->pc = pc;
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
frame->graph = 0;
#endif
}
#endif /* __ASM_STACKTRACE_H */