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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>
This commit is contained in:
Masami Hiramatsu 2012-09-05 23:31:12 +09:00 committed by Steven Rostedt
parent a5e37863ab
commit 4b036d54bf
1 changed files with 6 additions and 3 deletions
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9
arch/x86/kernel/kprobes.c
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@ -1072,7 +1072,8 @@ void __kprobes kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
if (kprobe_running()) { if (kprobe_running()) {
kprobes_inc_nmissed_count(p); kprobes_inc_nmissed_count(p);
} else { } 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); __this_cpu_write(current_kprobe, p);
kcb->kprobe_status = KPROBE_HIT_ACTIVE; 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); p->pre_handler(p, regs);
if (unlikely(p->post_handler)) { 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; regs->ip = ip + MCOUNT_INSN_SIZE;
kcb->kprobe_status = KPROBE_HIT_SSDONE; kcb->kprobe_status = KPROBE_HIT_SSDONE;
p->post_handler(p, regs, 0); p->post_handler(p, regs, 0);
} }
__this_cpu_write(current_kprobe, NULL); __this_cpu_write(current_kprobe, NULL);
regs->ip = ip; /* Recover for next callback */
} }
end: end:
local_irq_restore(flags); local_irq_restore(flags);