From: Masami Hiramatsu <masami.hiramatsu...@hitachi.com> 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.zijls...@chello.nl> Cc: Frederic Weisbecker <fweis...@gmail.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: "H. Peter Anvin" <h...@zytor.com> Signed-off-by: Masami Hiramatsu <masami.hiramatsu...@hitachi.com> Signed-off-by: Steven Rostedt <rost...@goodmis.org> --- arch/x86/kernel/kprobes.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index 47ae102..f49f60c 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); -- 1.7.10.4
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