diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/kprobes.c | 153 |
1 files changed, 86 insertions, 67 deletions
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index 711fec8f6379..53ba6a5b6550 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -442,6 +442,34 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, /* Replace the return addr with trampoline addr */ *sara = (unsigned long) &kretprobe_trampoline; } + +static void __kprobes recursive_singlestep(struct kprobe *p, + struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ + save_previous_kprobe(kcb); + set_current_kprobe(p, regs, kcb); + kprobes_inc_nmissed_count(p); + prepare_singlestep(p, regs); + kcb->kprobe_status = KPROBE_REENTER; +} + +static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs, + struct kprobe_ctlblk *kcb) +{ +#if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM) + if (p->ainsn.boostable == 1 && !p->post_handler) { + /* Boost up -- we can execute copied instructions directly */ + reset_current_kprobe(); + regs->ip = (unsigned long)p->ainsn.insn; + preempt_enable_no_resched(); + return; + } +#endif + prepare_singlestep(p, regs); + kcb->kprobe_status = KPROBE_HIT_SS; +} + /* * We have reentered the kprobe_handler(), since another probe was hit while * within the handler. We save the original kprobes variables and just single @@ -450,13 +478,9 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) { - if (kcb->kprobe_status == KPROBE_HIT_SS && - *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { - regs->flags &= ~X86_EFLAGS_TF; - regs->flags |= kcb->kprobe_saved_flags; - return 0; + switch (kcb->kprobe_status) { + case KPROBE_HIT_SSDONE: #ifdef CONFIG_X86_64 - } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) { /* TODO: Provide re-entrancy from post_kprobes_handler() and * avoid exception stack corruption while single-stepping on * the instruction of the new probe. @@ -464,14 +488,26 @@ static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, arch_disarm_kprobe(p); regs->ip = (unsigned long)p->addr; reset_current_kprobe(); - return 1; + preempt_enable_no_resched(); + break; #endif + case KPROBE_HIT_ACTIVE: + recursive_singlestep(p, regs, kcb); + break; + case KPROBE_HIT_SS: + if (*p->ainsn.insn == BREAKPOINT_INSTRUCTION) { + regs->flags &= ~TF_MASK; + regs->flags |= kcb->kprobe_saved_flags; + return 0; + } else { + recursive_singlestep(p, regs, kcb); + } + break; + default: + /* impossible cases */ + WARN_ON(1); } - save_previous_kprobe(kcb); - set_current_kprobe(p, regs, kcb); - kprobes_inc_nmissed_count(p); - prepare_singlestep(p, regs); - kcb->kprobe_status = KPROBE_REENTER; + return 1; } @@ -481,83 +517,66 @@ static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, */ static int __kprobes kprobe_handler(struct pt_regs *regs) { - struct kprobe *p; - int ret = 0; kprobe_opcode_t *addr; + struct kprobe *p; struct kprobe_ctlblk *kcb; addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); + if (*addr != BREAKPOINT_INSTRUCTION) { + /* + * The breakpoint instruction was removed right + * after we hit it. Another cpu has removed + * either a probepoint or a debugger breakpoint + * at this address. In either case, no further + * handling of this interrupt is appropriate. + * Back up over the (now missing) int3 and run + * the original instruction. + */ + regs->ip = (unsigned long)addr; + return 1; + } /* * We don't want to be preempted for the entire - * duration of kprobe processing + * duration of kprobe processing. We conditionally + * re-enable preemption at the end of this function, + * and also in reenter_kprobe() and setup_singlestep(). */ preempt_disable(); - kcb = get_kprobe_ctlblk(); + kcb = get_kprobe_ctlblk(); p = get_kprobe(addr); + if (p) { - /* Check we're not actually recursing */ if (kprobe_running()) { - ret = reenter_kprobe(p, regs, kcb); - if (kcb->kprobe_status == KPROBE_REENTER) - { - ret = 1; - goto out; - } - goto preempt_out; + if (reenter_kprobe(p, regs, kcb)) + return 1; } else { set_current_kprobe(p, regs, kcb); kcb->kprobe_status = KPROBE_HIT_ACTIVE; - if (p->pre_handler && p->pre_handler(p, regs)) - { - /* handler set things up, skip ss setup */ - ret = 1; - goto out; - } - } - } else { - if (*addr != BREAKPOINT_INSTRUCTION) { + /* - * The breakpoint instruction was removed right - * after we hit it. Another cpu has removed - * either a probepoint or a debugger breakpoint - * at this address. In either case, no further - * handling of this interrupt is appropriate. - * Back up over the (now missing) int3 and run - * the original instruction. + * If we have no pre-handler or it returned 0, we + * continue with normal processing. If we have a + * pre-handler and it returned non-zero, it prepped + * for calling the break_handler below on re-entry + * for jprobe processing, so get out doing nothing + * more here. */ - regs->ip = (unsigned long)addr; - ret = 1; - goto preempt_out; + if (!p->pre_handler || !p->pre_handler(p, regs)) + setup_singlestep(p, regs, kcb); + return 1; } - if (kprobe_running()) { - p = __get_cpu_var(current_kprobe); - if (p->break_handler && p->break_handler(p, regs)) - goto ss_probe; + } else if (kprobe_running()) { + p = __get_cpu_var(current_kprobe); + if (p->break_handler && p->break_handler(p, regs)) { + setup_singlestep(p, regs, kcb); + return 1; } - /* Not one of ours: let kernel handle it */ - goto preempt_out; - } + } /* else: not a kprobe fault; let the kernel handle it */ -ss_probe: - ret = 1; -#if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM) - if (p->ainsn.boostable == 1 && !p->post_handler) { - /* Boost up -- we can execute copied instructions directly */ - reset_current_kprobe(); - regs->ip = (unsigned long)p->ainsn.insn; - goto preempt_out; - } -#endif - prepare_singlestep(p, regs); - kcb->kprobe_status = KPROBE_HIT_SS; - goto out; - -preempt_out: preempt_enable_no_resched(); -out: - return ret; + return 0; } /* |