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Commit 4b036d54 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt
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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: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent a5e37863

arch/x86/kernel/kprobes.c

+6 −3
Original line number Diff line number Diff line
@@ -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);