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    Subject[PATCH] Subject: kprobes-x86: correct post-eip value in post_hander()

    I was trying to get the address of instruction to be executed
    next after the kprobed instruction. But regs->eip in post_handler()
    contains value which is useless to the user. It's pre-corrected value.
    This value is difficult to use without access to resume_execution(), which
    is not exported anyway.
    I moved the invocation of post_handler() to *after* resume_execution().
    Now regs->eip contains meaningful value in post_handler().

    I do not think this change breaks any backward-compatibility.
    To make meaning of the old value, post_handler() would need access to
    resume_execution() which is not exported. I have difficulty to believe
    that previous, uncorrected, regs->eip can be meaningfully used in

    Signed-off-by: Yakov Lerner <>
    arch/x86/kernel/kprobes.c | 8 ++++----
    1 files changed, 4 insertions(+), 4 deletions(-)

    diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
    index 34a5912..60392e2 100644
    --- a/arch/x86/kernel/kprobes.c
    +++ b/arch/x86/kernel/kprobes.c
    @@ -858,15 +858,15 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs)
    if (!cur)
    return 0;

    + resume_execution(cur, regs, kcb);
    + regs->flags |= kcb->kprobe_saved_flags;
    + trace_hardirqs_fixup_flags(regs->flags);
    if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) {
    kcb->kprobe_status = KPROBE_HIT_SSDONE;
    cur->post_handler(cur, regs, 0);

    - resume_execution(cur, regs, kcb);
    - regs->flags |= kcb->kprobe_saved_flags;
    - trace_hardirqs_fixup_flags(regs->flags);
    /* Restore back the original saved kprobes variables and continue. */
    if (kcb->kprobe_status == KPROBE_REENTER) {

     \ /
      Last update: 2008-03-16 09:25    [W:0.021 / U:13.224 seconds]
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