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c6a7d97d57
When a probe fires we must single-step the instruction which was replaced by a breakpoint. As the steps to do this vary between ARM and Thumb instructions we need a way to customise single-stepping. This is done by adding a new hook called insn_singlestep to arch_specific_insn which is initialised by the instruction decoding functions. These single-step hooks must update PC and call the instruction handler. For Thumb instructions an additional step of updating ITSTATE is needed. We do this after calling the handler because some handlers will need to test if they are running in an IT block. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
65 lines
1.7 KiB
C
65 lines
1.7 KiB
C
/*
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* arch/arm/kernel/kprobes-thumb.c
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*
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* Copyright (C) 2011 Jon Medhurst <tixy@yxit.co.uk>.
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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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#include <linux/kernel.h>
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#include <linux/kprobes.h>
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#include "kprobes.h"
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/*
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* True if current instruction is in an IT block.
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*/
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#define in_it_block(cpsr) ((cpsr & 0x06000c00) != 0x00000000)
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/*
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* Return the condition code to check for the currently executing instruction.
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* This is in ITSTATE<7:4> which is in CPSR<15:12> but is only valid if
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* in_it_block returns true.
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*/
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#define current_cond(cpsr) ((cpsr >> 12) & 0xf)
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static unsigned long __kprobes thumb_check_cc(unsigned long cpsr)
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{
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if (unlikely(in_it_block(cpsr)))
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return kprobe_condition_checks[current_cond(cpsr)](cpsr);
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return true;
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}
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static void __kprobes thumb16_singlestep(struct kprobe *p, struct pt_regs *regs)
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{
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regs->ARM_pc += 2;
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p->ainsn.insn_handler(p, regs);
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regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
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}
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static void __kprobes thumb32_singlestep(struct kprobe *p, struct pt_regs *regs)
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{
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regs->ARM_pc += 4;
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p->ainsn.insn_handler(p, regs);
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regs->ARM_cpsr = it_advance(regs->ARM_cpsr);
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}
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enum kprobe_insn __kprobes
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thumb16_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
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{
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asi->insn_singlestep = thumb16_singlestep;
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asi->insn_check_cc = thumb_check_cc;
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return INSN_REJECTED;
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}
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enum kprobe_insn __kprobes
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thumb32_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi)
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{
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asi->insn_singlestep = thumb32_singlestep;
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asi->insn_check_cc = thumb_check_cc;
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return INSN_REJECTED;
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}
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