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authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>2012-09-05 23:31:12 +0900
committerSteven Rostedt <rostedt@goodmis.org>2012-09-13 22:52:09 -0400
commit4b036d54bf849a75d0103b33d92a53f89ecb9315 (patch)
treea3951c4c6b585f15e02634993cde58986f848443
parenta5e37863ab31d78faddff15675c89979792bc0bd (diff)
kprobes/x86: Fix kprobes to collectly handle IP on ftrace
Current kprobe_ftrace_handler expects regs->ip == ip, but it is incorrect (originally on x86-64). Actually, ftrace handler sets regs->ip = ip + MCOUNT_INSN_SIZE. kprobe_ftrace_handler must take care for that. Link: http://lkml.kernel.org/r/20120905143112.10329.72069.stgit@localhost.localdomain Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--arch/x86/kernel/kprobes.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 47ae1023a93c..f49f60cca40d 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -1072,7 +1072,8 @@ void __kprobes kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
if (kprobe_running()) {
kprobes_inc_nmissed_count(p);
} else {
- regs->ip += sizeof(kprobe_opcode_t);
+ /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
+ regs->ip = ip + sizeof(kprobe_opcode_t);
__this_cpu_write(current_kprobe, p);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
@@ -1080,13 +1081,15 @@ void __kprobes kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
p->pre_handler(p, regs);
if (unlikely(p->post_handler)) {
- /* Emulate singlestep as if there is a 5byte nop */
+ /*
+ * Emulate singlestep (and also recover regs->ip)
+ * as if there is a 5byte nop
+ */
regs->ip = ip + MCOUNT_INSN_SIZE;
kcb->kprobe_status = KPROBE_HIT_SSDONE;
p->post_handler(p, regs, 0);
}
__this_cpu_write(current_kprobe, NULL);
- regs->ip = ip; /* Recover for next callback */
}
end:
local_irq_restore(flags);