Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=fb8830e72d9bd86f1e7b6886cb1886c391130f86
Commit: fb8830e72d9bd86f1e7b6886cb1886c391130f86
Parent: 0723a69a63beec1ca6e792239ef75d0181387ef0
Author: Abhishek Sagar <[EMAIL PROTECTED]>
AuthorDate: Wed Jan 30 13:33:13 2008 +0100
Committer: Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Wed Jan 30 13:33:13 2008 +0100
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 <[EMAIL PROTECTED]>
Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
---
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 edc0a8e..f7ddbb8 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;
-
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