diff options
| author | Abhishek Sagar <sagar.abhishek@gmail.com> | 2008-01-30 13:33:13 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-01-30 13:33:13 +0100 |
| commit | fb8830e72d9bd86f1e7b6886cb1886c391130f86 (patch) | |
| tree | 1be87ec5258d9b6cf3ab877c3b3e723db8f98aad | |
| parent | 0723a69a63beec1ca6e792239ef75d0181387ef0 (diff) | |
x86: fix singlestep handling in reenter_kprobe
Highlight peculiar cases in singles-step kprobe handling.
In reenter_kprobe(), a breakpoint in KPROBE_HIT_SS case can only occur
when single-stepping a breakpoint on which a probe was installed. Since
such probes are single-stepped inline, identifying these cases is
unambiguous. All other cases leading up to KPROBE_HIT_SS are possible
bugs. Identify and WARN_ON such cases.
Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| -rw-r--r-- | arch/x86/kernel/kprobes.c | 28 |
1 files changed, 13 insertions, 15 deletions
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index edc0a8e5924..f7ddbb8c3fe 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -443,17 +443,6 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, *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) { @@ -492,20 +481,29 @@ static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, break; #endif case KPROBE_HIT_ACTIVE: - recursive_singlestep(p, regs, 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; break; case KPROBE_HIT_SS: - if (*p->ainsn.insn == BREAKPOINT_INSTRUCTION) { + if (p == kprobe_running()) { regs->flags &= ~TF_MASK; regs->flags |= kcb->kprobe_saved_flags; return 0; } else { - recursive_singlestep(p, regs, kcb); + /* A probe has been hit in the codepath leading up + * to, or just after, single-stepping of a probed + * instruction. This entire codepath should strictly + * reside in .kprobes.text section. Raise a warning + * to highlight this peculiar case. + */ } - break; default: /* impossible cases */ WARN_ON(1); + return 0; } return 1; |