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Subject[PATCH 2/3] x86: add reenter_kprobe helper
From:  Harvey Harrison <harvey.harrison@gmail.com>

[ mhiramat@redhat.com: updated it to latest x86.git ]

Factor common X86_32, X86_64 kprobe reenter logic from deeply
indented section to helper function.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
---

arch/x86/kernel/kprobes.c | 26 +++++++++++++++-----------
1 file changed, 15 insertions(+), 11 deletions(-)

Index: b/arch/x86/kernel/kprobes.c
===================================================================
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -427,6 +427,20 @@ void __kprobes arch_prepare_kretprobe(st
/* Replace the return addr with trampoline addr */
*sara = (unsigned long) &kretprobe_trampoline;
}
+/*
+ * We have reentered the kprobe_handler(), since another probe was hit while
+ * within the handler. We save the original kprobes variables and just single
+ * step on the instruction of the new probe without calling any user handlers.
+ */
+static void __kprobes reenter_kprobe(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;
+}

/*
* Interrupts are disabled on entry as trap3 is an interrupt gate and they
@@ -471,17 +485,7 @@ static int __kprobes kprobe_handler(stru
goto no_kprobe;
#endif
}
- /* We have reentered the kprobe_handler(), since
- * another probe was hit while within the handler.
- * We here save the original kprobes variables and
- * just single step on the instruction of the new probe
- * without calling any user handlers.
- */
- save_previous_kprobe(kcb);
- set_current_kprobe(p, regs, kcb);
- kprobes_inc_nmissed_count(p);
- prepare_singlestep(p, regs);
- kcb->kprobe_status = KPROBE_REENTER;
+ reenter_kprobe(p, regs, kcb);
return 1;
} else {
if (*addr != BREAKPOINT_INSTRUCTION) {
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com, masami.hiramatsu.pt@hitachi.com


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