From c6a7d97d57ef41477a85f4c0f48ea5243132ee1f Mon Sep 17 00:00:00 2001 From: Jon Medhurst Date: Thu, 9 Jun 2011 12:11:27 +0100 Subject: [PATCH] ARM: kprobes: Add hooks to override singlestep() 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 Acked-by: Nicolas Pitre --- arch/arm/include/asm/kprobes.h | 9 +++++---- arch/arm/kernel/kprobes-arm.c | 7 +++++++ arch/arm/kernel/kprobes-thumb.c | 16 ++++++++++++++++ arch/arm/kernel/kprobes.c | 8 +++----- 4 files changed, 31 insertions(+), 9 deletions(-) diff --git a/arch/arm/include/asm/kprobes.h b/arch/arm/include/asm/kprobes.h index 57d37d52d71..1e9ff56d40c 100644 --- a/arch/arm/include/asm/kprobes.h +++ b/arch/arm/include/asm/kprobes.h @@ -32,14 +32,15 @@ typedef u32 kprobe_opcode_t; struct kprobe; typedef void (kprobe_insn_handler_t)(struct kprobe *, struct pt_regs *); - typedef unsigned long (kprobe_check_cc)(unsigned long); +typedef void (kprobe_insn_singlestep_t)(struct kprobe *, struct pt_regs *); /* Architecture specific copy of original instruction. */ struct arch_specific_insn { - kprobe_opcode_t *insn; - kprobe_insn_handler_t *insn_handler; - kprobe_check_cc *insn_check_cc; + kprobe_opcode_t *insn; + kprobe_insn_handler_t *insn_handler; + kprobe_check_cc *insn_check_cc; + kprobe_insn_singlestep_t *insn_singlestep; }; struct prev_kprobe { diff --git a/arch/arm/kernel/kprobes-arm.c b/arch/arm/kernel/kprobes-arm.c index 0262b29163d..a1143e86a09 100644 --- a/arch/arm/kernel/kprobes-arm.c +++ b/arch/arm/kernel/kprobes-arm.c @@ -1494,6 +1494,12 @@ space_cccc_11xx(kprobe_opcode_t insn, struct arch_specific_insn *asi) return INSN_REJECTED; } +static void __kprobes arm_singlestep(struct kprobe *p, struct pt_regs *regs) +{ + regs->ARM_pc += 4; + p->ainsn.insn_handler(p, regs); +} + /* Return: * INSN_REJECTED If instruction is one not allowed to kprobe, * INSN_GOOD If instruction is supported and uses instruction slot, @@ -1509,6 +1515,7 @@ space_cccc_11xx(kprobe_opcode_t insn, struct arch_specific_insn *asi) enum kprobe_insn __kprobes arm_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi) { + asi->insn_singlestep = arm_singlestep; asi->insn_check_cc = kprobe_condition_checks[insn>>28]; asi->insn[1] = KPROBE_RETURN_INSTRUCTION; diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c index 24a188b1601..973c3eb1243 100644 --- a/arch/arm/kernel/kprobes-thumb.c +++ b/arch/arm/kernel/kprobes-thumb.c @@ -33,9 +33,24 @@ static unsigned long __kprobes thumb_check_cc(unsigned long cpsr) return true; } +static void __kprobes thumb16_singlestep(struct kprobe *p, struct pt_regs *regs) +{ + regs->ARM_pc += 2; + p->ainsn.insn_handler(p, regs); + regs->ARM_cpsr = it_advance(regs->ARM_cpsr); +} + +static void __kprobes thumb32_singlestep(struct kprobe *p, struct pt_regs *regs) +{ + regs->ARM_pc += 4; + p->ainsn.insn_handler(p, regs); + regs->ARM_cpsr = it_advance(regs->ARM_cpsr); +} + enum kprobe_insn __kprobes thumb16_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi) { + asi->insn_singlestep = thumb16_singlestep; asi->insn_check_cc = thumb_check_cc; return INSN_REJECTED; } @@ -43,6 +58,7 @@ thumb16_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi) enum kprobe_insn __kprobes thumb32_kprobe_decode_insn(kprobe_opcode_t insn, struct arch_specific_insn *asi) { + asi->insn_singlestep = thumb32_singlestep; asi->insn_check_cc = thumb_check_cc; return INSN_REJECTED; } diff --git a/arch/arm/kernel/kprobes.c b/arch/arm/kernel/kprobes.c index 0003dfd3b85..77b7c697480 100644 --- a/arch/arm/kernel/kprobes.c +++ b/arch/arm/kernel/kprobes.c @@ -227,12 +227,10 @@ singlestep_skip(struct kprobe *p, struct pt_regs *regs) #endif } -static void __kprobes singlestep(struct kprobe *p, struct pt_regs *regs, - struct kprobe_ctlblk *kcb) +static inline void __kprobes +singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) { - regs->ARM_pc += 4; - if (p->ainsn.insn_check_cc(regs->ARM_cpsr)) - p->ainsn.insn_handler(p, regs); + p->ainsn.insn_singlestep(p, regs); } /* -- 2.39.5