kprobes/x86: Fix to support jprobes on ftrace-based kprobe
authorMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Wed, 5 Sep 2012 14:31:25 +0000 (23:31 +0900)
committerSteven Rostedt <rostedt@goodmis.org>
Fri, 14 Sep 2012 02:52:11 +0000 (22:52 -0400)
commitc6aaf4d0bb86e2154ea31a33804cec300611255f
tree34f973a7ee081daa773b8d4cea9cffaf28bf018a
parent47d5a5f88b9d25d6464c9b60c28f391e84e3ed65
kprobes/x86: Fix to support jprobes on ftrace-based kprobe

Fix kprobes/x86 to support jprobes on ftrace-based kprobes.
Because of -mfentry support of ftrace, ftrace is now put
on the beginning of function where jprobes are put.

Originally ftrace-based kprobes doesn't support jprobe
because it will change regs->ip and ftrace doesn't support
changing IP and ftrace itself doesn't conflict jprobe.
However, ftrace -mfentry support moves mcount call on the
top of functions where jprobes are put. This means that
jprobe always conflicts with ftrace-based kprobe and fails.

This patch allows ftrace-based kprobes to support jprobes
by allowing to modify regs->ip and kprobes breakpoint
handler also allows to skip singlestepping because there
is a ftrace call (not an original instruction).

Link: http://lkml.kernel.org/r/20120905143125.10329.90836.stgit@localhost.localdomain
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
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>
arch/x86/kernel/kprobes.c
kernel/kprobes.c