Messages in this thread Patch in this message | | | Date | Fri, 21 Mar 2008 15:32:29 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] Subject: kprobes-x86: correct post-eip value in post_hander() |
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* Ananth N Mavinakayanahalli <ananth@in.ibm.com> wrote:
> > thanks, i've added your patch to the .26 bucket of x86.git, but it > > would be nice to get an Ack/Nack from a kprobes person as well. > > Ingo, > > I've tested Yakov's more comprehensive patch on powerpc too. This has > my ack. > > Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
thanks, i've queued up the x86-only patch below for .26 merging. (that is all that is needed for x86, and no .25 urgency, right?)
Ingo
------------------> Subject: x86, kprobes: correct post-eip value in post_hander() From: "Yakov Lerner" <iler.ml@gmail.com> Date: Sun, 16 Mar 2008 03:21:21 -0500
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 post_handler().
Signed-off-by: Yakov Lerner <iler.ml@gmail.com> Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> --- arch/x86/kernel/kprobes.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
Index: linux-x86.q/arch/x86/kernel/kprobes.c =================================================================== --- linux-x86.q.orig/arch/x86/kernel/kprobes.c +++ linux-x86.q/arch/x86/kernel/kprobes.c @@ -858,15 +858,15 @@ static int __kprobes post_kprobe_handler 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) { restore_previous_kprobe(kcb);
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