forked from Minki/linux
ee78fdc71d
Each time new section markers are added, kernel/vmlinux.ld.S is updated, and new extern char __start_foo[] definitions are scattered through the tree. Create asm/include/sections.h to collect these definitions (and include the existing asm-generic version). Signed-off-by: James Morse <james.morse@arm.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Tested-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
660 lines
17 KiB
C
660 lines
17 KiB
C
/*
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* arch/arm64/kernel/probes/kprobes.c
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*
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* Kprobes support for ARM64
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*
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* Copyright (C) 2013 Linaro Limited.
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* Author: Sandeepa Prabhu <sandeepa.prabhu@linaro.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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*/
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#include <linux/kasan.h>
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#include <linux/kernel.h>
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#include <linux/kprobes.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/stop_machine.h>
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#include <linux/stringify.h>
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#include <asm/traps.h>
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#include <asm/ptrace.h>
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#include <asm/cacheflush.h>
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#include <asm/debug-monitors.h>
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#include <asm/system_misc.h>
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#include <asm/insn.h>
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#include <asm/uaccess.h>
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#include <asm/irq.h>
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#include <asm/sections.h>
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#include "decode-insn.h"
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DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
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DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
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static void __kprobes
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post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *);
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static void __kprobes arch_prepare_ss_slot(struct kprobe *p)
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{
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/* prepare insn slot */
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p->ainsn.insn[0] = cpu_to_le32(p->opcode);
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flush_icache_range((uintptr_t) (p->ainsn.insn),
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(uintptr_t) (p->ainsn.insn) +
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MAX_INSN_SIZE * sizeof(kprobe_opcode_t));
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/*
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* Needs restoring of return address after stepping xol.
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*/
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p->ainsn.restore = (unsigned long) p->addr +
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sizeof(kprobe_opcode_t);
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}
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static void __kprobes arch_prepare_simulate(struct kprobe *p)
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{
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/* This instructions is not executed xol. No need to adjust the PC */
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p->ainsn.restore = 0;
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}
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static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs)
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{
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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if (p->ainsn.handler)
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p->ainsn.handler((u32)p->opcode, (long)p->addr, regs);
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/* single step simulated, now go for post processing */
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post_kprobe_handler(kcb, regs);
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}
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int __kprobes arch_prepare_kprobe(struct kprobe *p)
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{
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unsigned long probe_addr = (unsigned long)p->addr;
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extern char __start_rodata[];
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extern char __end_rodata[];
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if (probe_addr & 0x3)
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return -EINVAL;
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/* copy instruction */
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p->opcode = le32_to_cpu(*p->addr);
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if (in_exception_text(probe_addr))
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return -EINVAL;
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if (probe_addr >= (unsigned long) __start_rodata &&
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probe_addr <= (unsigned long) __end_rodata)
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return -EINVAL;
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/* decode instruction */
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switch (arm_kprobe_decode_insn(p->addr, &p->ainsn)) {
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case INSN_REJECTED: /* insn not supported */
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return -EINVAL;
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case INSN_GOOD_NO_SLOT: /* insn need simulation */
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p->ainsn.insn = NULL;
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break;
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case INSN_GOOD: /* instruction uses slot */
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p->ainsn.insn = get_insn_slot();
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if (!p->ainsn.insn)
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return -ENOMEM;
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break;
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};
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/* prepare the instruction */
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if (p->ainsn.insn)
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arch_prepare_ss_slot(p);
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else
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arch_prepare_simulate(p);
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return 0;
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}
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static int __kprobes patch_text(kprobe_opcode_t *addr, u32 opcode)
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{
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void *addrs[1];
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u32 insns[1];
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addrs[0] = (void *)addr;
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insns[0] = (u32)opcode;
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return aarch64_insn_patch_text(addrs, insns, 1);
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}
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/* arm kprobe: install breakpoint in text */
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void __kprobes arch_arm_kprobe(struct kprobe *p)
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{
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patch_text(p->addr, BRK64_OPCODE_KPROBES);
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}
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/* disarm kprobe: remove breakpoint from text */
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void __kprobes arch_disarm_kprobe(struct kprobe *p)
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{
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patch_text(p->addr, p->opcode);
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}
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void __kprobes arch_remove_kprobe(struct kprobe *p)
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{
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if (p->ainsn.insn) {
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free_insn_slot(p->ainsn.insn, 0);
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p->ainsn.insn = NULL;
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}
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}
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static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
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{
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kcb->prev_kprobe.kp = kprobe_running();
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kcb->prev_kprobe.status = kcb->kprobe_status;
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}
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static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
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{
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__this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
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kcb->kprobe_status = kcb->prev_kprobe.status;
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}
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static void __kprobes set_current_kprobe(struct kprobe *p)
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{
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__this_cpu_write(current_kprobe, p);
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}
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/*
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* When PSTATE.D is set (masked), then software step exceptions can not be
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* generated.
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* SPSR's D bit shows the value of PSTATE.D immediately before the
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* exception was taken. PSTATE.D is set while entering into any exception
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* mode, however software clears it for any normal (none-debug-exception)
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* mode in the exception entry. Therefore, when we are entering into kprobe
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* breakpoint handler from any normal mode then SPSR.D bit is already
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* cleared, however it is set when we are entering from any debug exception
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* mode.
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* Since we always need to generate single step exception after a kprobe
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* breakpoint exception therefore we need to clear it unconditionally, when
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* we become sure that the current breakpoint exception is for kprobe.
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*/
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static void __kprobes
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spsr_set_debug_flag(struct pt_regs *regs, int mask)
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{
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unsigned long spsr = regs->pstate;
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if (mask)
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spsr |= PSR_D_BIT;
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else
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spsr &= ~PSR_D_BIT;
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regs->pstate = spsr;
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}
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/*
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* Interrupts need to be disabled before single-step mode is set, and not
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* reenabled until after single-step mode ends.
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* Without disabling interrupt on local CPU, there is a chance of
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* interrupt occurrence in the period of exception return and start of
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* out-of-line single-step, that result in wrongly single stepping
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* into the interrupt handler.
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*/
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static void __kprobes kprobes_save_local_irqflag(struct kprobe_ctlblk *kcb,
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struct pt_regs *regs)
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{
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kcb->saved_irqflag = regs->pstate;
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regs->pstate |= PSR_I_BIT;
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}
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static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb,
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struct pt_regs *regs)
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{
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if (kcb->saved_irqflag & PSR_I_BIT)
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regs->pstate |= PSR_I_BIT;
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else
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regs->pstate &= ~PSR_I_BIT;
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}
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static void __kprobes
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set_ss_context(struct kprobe_ctlblk *kcb, unsigned long addr)
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{
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kcb->ss_ctx.ss_pending = true;
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kcb->ss_ctx.match_addr = addr + sizeof(kprobe_opcode_t);
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}
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static void __kprobes clear_ss_context(struct kprobe_ctlblk *kcb)
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{
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kcb->ss_ctx.ss_pending = false;
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kcb->ss_ctx.match_addr = 0;
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}
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static void __kprobes setup_singlestep(struct kprobe *p,
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struct pt_regs *regs,
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struct kprobe_ctlblk *kcb, int reenter)
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{
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unsigned long slot;
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if (reenter) {
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save_previous_kprobe(kcb);
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set_current_kprobe(p);
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kcb->kprobe_status = KPROBE_REENTER;
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} else {
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kcb->kprobe_status = KPROBE_HIT_SS;
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}
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if (p->ainsn.insn) {
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/* prepare for single stepping */
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slot = (unsigned long)p->ainsn.insn;
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set_ss_context(kcb, slot); /* mark pending ss */
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spsr_set_debug_flag(regs, 0);
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/* IRQs and single stepping do not mix well. */
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kprobes_save_local_irqflag(kcb, regs);
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kernel_enable_single_step(regs);
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instruction_pointer_set(regs, slot);
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} else {
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/* insn simulation */
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arch_simulate_insn(p, regs);
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}
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}
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static int __kprobes reenter_kprobe(struct kprobe *p,
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struct pt_regs *regs,
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struct kprobe_ctlblk *kcb)
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{
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switch (kcb->kprobe_status) {
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case KPROBE_HIT_SSDONE:
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case KPROBE_HIT_ACTIVE:
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kprobes_inc_nmissed_count(p);
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setup_singlestep(p, regs, kcb, 1);
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break;
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case KPROBE_HIT_SS:
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case KPROBE_REENTER:
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pr_warn("Unrecoverable kprobe detected at %p.\n", p->addr);
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dump_kprobe(p);
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BUG();
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break;
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default:
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WARN_ON(1);
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return 0;
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}
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return 1;
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}
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static void __kprobes
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post_kprobe_handler(struct kprobe_ctlblk *kcb, struct pt_regs *regs)
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{
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struct kprobe *cur = kprobe_running();
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if (!cur)
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return;
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/* return addr restore if non-branching insn */
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if (cur->ainsn.restore != 0)
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instruction_pointer_set(regs, cur->ainsn.restore);
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/* restore back original saved kprobe variables and continue */
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if (kcb->kprobe_status == KPROBE_REENTER) {
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restore_previous_kprobe(kcb);
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return;
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}
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/* call post handler */
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kcb->kprobe_status = KPROBE_HIT_SSDONE;
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if (cur->post_handler) {
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/* post_handler can hit breakpoint and single step
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* again, so we enable D-flag for recursive exception.
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*/
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cur->post_handler(cur, regs, 0);
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}
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reset_current_kprobe();
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}
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int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr)
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{
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struct kprobe *cur = kprobe_running();
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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switch (kcb->kprobe_status) {
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case KPROBE_HIT_SS:
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case KPROBE_REENTER:
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/*
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* We are here because the instruction being single
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* stepped caused a page fault. We reset the current
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* kprobe and the ip points back to the probe address
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* and allow the page fault handler to continue as a
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* normal page fault.
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*/
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instruction_pointer_set(regs, (unsigned long) cur->addr);
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if (!instruction_pointer(regs))
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BUG();
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kernel_disable_single_step();
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if (kcb->kprobe_status == KPROBE_REENTER)
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restore_previous_kprobe(kcb);
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else
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reset_current_kprobe();
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break;
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case KPROBE_HIT_ACTIVE:
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case KPROBE_HIT_SSDONE:
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/*
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* We increment the nmissed count for accounting,
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* we can also use npre/npostfault count for accounting
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* these specific fault cases.
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*/
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kprobes_inc_nmissed_count(cur);
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/*
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* We come here because instructions in the pre/post
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* handler caused the page_fault, this could happen
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* if handler tries to access user space by
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* copy_from_user(), get_user() etc. Let the
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* user-specified handler try to fix it first.
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*/
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if (cur->fault_handler && cur->fault_handler(cur, regs, fsr))
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return 1;
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/*
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* In case the user-specified fault handler returned
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* zero, try to fix up.
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*/
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if (fixup_exception(regs))
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return 1;
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}
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return 0;
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}
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int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
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unsigned long val, void *data)
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{
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return NOTIFY_DONE;
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}
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static void __kprobes kprobe_handler(struct pt_regs *regs)
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{
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struct kprobe *p, *cur_kprobe;
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struct kprobe_ctlblk *kcb;
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unsigned long addr = instruction_pointer(regs);
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kcb = get_kprobe_ctlblk();
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cur_kprobe = kprobe_running();
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p = get_kprobe((kprobe_opcode_t *) addr);
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if (p) {
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if (cur_kprobe) {
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if (reenter_kprobe(p, regs, kcb))
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return;
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} else {
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/* Probe hit */
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set_current_kprobe(p);
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kcb->kprobe_status = KPROBE_HIT_ACTIVE;
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/*
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* If we have no pre-handler or it returned 0, we
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* continue with normal processing. If we have a
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* pre-handler and it returned non-zero, it prepped
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* for calling the break_handler below on re-entry,
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* so get out doing nothing more here.
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*
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* pre_handler can hit a breakpoint and can step thru
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* before return, keep PSTATE D-flag enabled until
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* pre_handler return back.
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*/
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if (!p->pre_handler || !p->pre_handler(p, regs)) {
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setup_singlestep(p, regs, kcb, 0);
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return;
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}
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}
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} else if ((le32_to_cpu(*(kprobe_opcode_t *) addr) ==
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BRK64_OPCODE_KPROBES) && cur_kprobe) {
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/* We probably hit a jprobe. Call its break handler. */
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if (cur_kprobe->break_handler &&
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cur_kprobe->break_handler(cur_kprobe, regs)) {
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setup_singlestep(cur_kprobe, regs, kcb, 0);
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return;
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}
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}
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/*
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* The breakpoint instruction was removed right
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* after we hit it. Another cpu has removed
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* either a probepoint or a debugger breakpoint
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* at this address. In either case, no further
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* handling of this interrupt is appropriate.
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* Return back to original instruction, and continue.
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*/
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}
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static int __kprobes
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kprobe_ss_hit(struct kprobe_ctlblk *kcb, unsigned long addr)
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{
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if ((kcb->ss_ctx.ss_pending)
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&& (kcb->ss_ctx.match_addr == addr)) {
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clear_ss_context(kcb); /* clear pending ss */
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return DBG_HOOK_HANDLED;
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}
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/* not ours, kprobes should ignore it */
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return DBG_HOOK_ERROR;
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}
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int __kprobes
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kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr)
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{
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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int retval;
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/* return error if this is not our step */
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retval = kprobe_ss_hit(kcb, instruction_pointer(regs));
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if (retval == DBG_HOOK_HANDLED) {
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kprobes_restore_local_irqflag(kcb, regs);
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kernel_disable_single_step();
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post_kprobe_handler(kcb, regs);
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}
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return retval;
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}
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int __kprobes
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kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr)
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{
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kprobe_handler(regs);
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return DBG_HOOK_HANDLED;
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}
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int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
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{
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struct jprobe *jp = container_of(p, struct jprobe, kp);
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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kcb->jprobe_saved_regs = *regs;
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/*
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* Since we can't be sure where in the stack frame "stacked"
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* pass-by-value arguments are stored we just don't try to
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* duplicate any of the stack. Do not use jprobes on functions that
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* use more than 64 bytes (after padding each to an 8 byte boundary)
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* of arguments, or pass individual arguments larger than 16 bytes.
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*/
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instruction_pointer_set(regs, (unsigned long) jp->entry);
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preempt_disable();
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pause_graph_tracing();
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return 1;
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}
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void __kprobes jprobe_return(void)
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{
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struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
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/*
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* Jprobe handler return by entering break exception,
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* encoded same as kprobe, but with following conditions
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* -a special PC to identify it from the other kprobes.
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* -restore stack addr to original saved pt_regs
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*/
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asm volatile(" mov sp, %0 \n"
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"jprobe_return_break: brk %1 \n"
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:
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: "r" (kcb->jprobe_saved_regs.sp),
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"I" (BRK64_ESR_KPROBES)
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: "memory");
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|
|
unreachable();
|
|
}
|
|
|
|
int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
|
|
{
|
|
struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
|
|
long stack_addr = kcb->jprobe_saved_regs.sp;
|
|
long orig_sp = kernel_stack_pointer(regs);
|
|
struct jprobe *jp = container_of(p, struct jprobe, kp);
|
|
extern const char jprobe_return_break[];
|
|
|
|
if (instruction_pointer(regs) != (u64) jprobe_return_break)
|
|
return 0;
|
|
|
|
if (orig_sp != stack_addr) {
|
|
struct pt_regs *saved_regs =
|
|
(struct pt_regs *)kcb->jprobe_saved_regs.sp;
|
|
pr_err("current sp %lx does not match saved sp %lx\n",
|
|
orig_sp, stack_addr);
|
|
pr_err("Saved registers for jprobe %p\n", jp);
|
|
show_regs(saved_regs);
|
|
pr_err("Current registers\n");
|
|
show_regs(regs);
|
|
BUG();
|
|
}
|
|
unpause_graph_tracing();
|
|
*regs = kcb->jprobe_saved_regs;
|
|
preempt_enable_no_resched();
|
|
return 1;
|
|
}
|
|
|
|
bool arch_within_kprobe_blacklist(unsigned long addr)
|
|
{
|
|
if ((addr >= (unsigned long)__kprobes_text_start &&
|
|
addr < (unsigned long)__kprobes_text_end) ||
|
|
(addr >= (unsigned long)__entry_text_start &&
|
|
addr < (unsigned long)__entry_text_end) ||
|
|
(addr >= (unsigned long)__idmap_text_start &&
|
|
addr < (unsigned long)__idmap_text_end) ||
|
|
!!search_exception_tables(addr))
|
|
return true;
|
|
|
|
if (!is_kernel_in_hyp_mode()) {
|
|
if ((addr >= (unsigned long)__hyp_text_start &&
|
|
addr < (unsigned long)__hyp_text_end) ||
|
|
(addr >= (unsigned long)__hyp_idmap_text_start &&
|
|
addr < (unsigned long)__hyp_idmap_text_end))
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs)
|
|
{
|
|
struct kretprobe_instance *ri = NULL;
|
|
struct hlist_head *head, empty_rp;
|
|
struct hlist_node *tmp;
|
|
unsigned long flags, orig_ret_address = 0;
|
|
unsigned long trampoline_address =
|
|
(unsigned long)&kretprobe_trampoline;
|
|
kprobe_opcode_t *correct_ret_addr = NULL;
|
|
|
|
INIT_HLIST_HEAD(&empty_rp);
|
|
kretprobe_hash_lock(current, &head, &flags);
|
|
|
|
/*
|
|
* It is possible to have multiple instances associated with a given
|
|
* task either because multiple functions in the call path have
|
|
* return probes installed on them, and/or more than one
|
|
* return probe was registered for a target function.
|
|
*
|
|
* We can handle this because:
|
|
* - instances are always pushed into the head of the list
|
|
* - when multiple return probes are registered for the same
|
|
* function, the (chronologically) first instance's ret_addr
|
|
* will be the real return address, and all the rest will
|
|
* point to kretprobe_trampoline.
|
|
*/
|
|
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
|
|
if (ri->task != current)
|
|
/* another task is sharing our hash bucket */
|
|
continue;
|
|
|
|
orig_ret_address = (unsigned long)ri->ret_addr;
|
|
|
|
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;
|
|
}
|
|
|
|
kretprobe_assert(ri, orig_ret_address, trampoline_address);
|
|
|
|
correct_ret_addr = ri->ret_addr;
|
|
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
|
|
if (ri->task != current)
|
|
/* another task is sharing our hash bucket */
|
|
continue;
|
|
|
|
orig_ret_address = (unsigned long)ri->ret_addr;
|
|
if (ri->rp && ri->rp->handler) {
|
|
__this_cpu_write(current_kprobe, &ri->rp->kp);
|
|
get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
|
|
ri->ret_addr = correct_ret_addr;
|
|
ri->rp->handler(ri, regs);
|
|
__this_cpu_write(current_kprobe, NULL);
|
|
}
|
|
|
|
recycle_rp_inst(ri, &empty_rp);
|
|
|
|
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;
|
|
}
|
|
|
|
kretprobe_hash_unlock(current, &flags);
|
|
|
|
hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
|
|
hlist_del(&ri->hlist);
|
|
kfree(ri);
|
|
}
|
|
return (void *)orig_ret_address;
|
|
}
|
|
|
|
void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
|
|
struct pt_regs *regs)
|
|
{
|
|
ri->ret_addr = (kprobe_opcode_t *)regs->regs[30];
|
|
|
|
/* replace return addr (x30) with trampoline */
|
|
regs->regs[30] = (long)&kretprobe_trampoline;
|
|
}
|
|
|
|
int __kprobes arch_trampoline_kprobe(struct kprobe *p)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
int __init arch_init_kprobes(void)
|
|
{
|
|
return 0;
|
|
}
|