From db97bc7f9997fef41b24c91f61c2f776d32d7ce3 Mon Sep 17 00:00:00 2001
From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Date: Thu, 27 May 2010 19:19:20 +0000
Subject: [PATCH] powerpc/kprobes: Remove resume_execution() in kprobes
emulate_step() in kprobe_handler() would've already determined if the
probed instruction can be emulated. We single-step in hardware only if
the instruction couldn't be emulated. resume_execution() therefore is
superfluous -- all we need is to fix up the instruction pointer after
single-stepping.
Thanks to Paul Mackerras for catching this.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
arch/powerpc/kernel/kprobes.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index c533525ca56a..bc47352deb1f 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -378,17 +378,6 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
* single-stepped a copy of the instruction. The address of this
* copy is p->ainsn.insn.
*/
-static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs)
-{
- int ret;
- unsigned int insn = *p->ainsn.insn;
-
- regs->nip = (unsigned long)p->addr;
- ret = emulate_step(regs, insn);
- if (ret == 0)
- regs->nip = (unsigned long)p->addr + 4;
-}
-
static int __kprobes post_kprobe_handler(struct pt_regs *regs)
{
struct kprobe *cur = kprobe_running();
@@ -406,7 +395,8 @@ static int __kprobes post_kprobe_handler(struct pt_regs *regs)
cur->post_handler(cur, regs, 0);
}
- resume_execution(cur, regs);
+ /* Adjust nip to after the single-stepped instruction */
+ regs->nip = (unsigned long)cur->addr + 4;
regs->msr |= kcb->kprobe_saved_msr;
/*Restore back the original saved kprobes variables and continue. */