linux-kernel - [PATCH -tip 0/4][BUGFIX] Fix ftrace-based kprobes

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Date:	Wed, 05 Sep 2012 23:30:46 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org
Cc:	"H. Peter Anvin" <hpa@...ux.intel.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	yrl.pp-manager.tt@...achi.com
Subject: [PATCH -tip  0/4][BUGFIX] Fix ftrace-based kprobes 

Hi,

This series of patches fixes some bugs and corrects behaviors
of ftrace and ftrace-based kprobe.

As Fengguang reported at https://lkml.org/lkml/2012/8/24/45
ftrace-based kprobes and -mfentry option caused failures
on kprobe smoke test. This basically comes from the initial
design of ftrace-based kprobe which prohibits jprobe on
ftraced kprobe.
Without -mfentry support, this works well because NO mcount
call is at the first instruction of any function. However,
-mfentry calls it at the first one and it conflicts with
jprobe.

On this series, kprobe allows jprobe even if it is based on
ftrace. For this fix, I need following fixes.

- Make ftrace-handler interface same on x86/x86-64
  On x86, ftrace_regs_caller puts a same address on ip and 
  regs.ip, however those are different on x86-64. I've
  modified x86 to fit to x86-64 ABI.
- Fix kprobe ftrace handler for above ABI change
  Current kprobe_ftrace_handler expects ip == regs.ip, but
  it's not correct on x86-64 (and now on x86 too). This should
  be fixed.
- Use regs.ip for return address on ftrace
  From Steven, this change is suggested. Thanks!


Thank you,

---

Masami Hiramatsu (3):
      [BUGFIX] kprobes/x86: Fix to support jprobes on ftrace-based kprobe
      [BUGFIX] kprobes/x86: Fix kprobes to collectly handle IP on ftrace
      [BUGFIX] ftrace/x86: Adjust x86 regs.ip as like as x86-64

Steven Rostedt (1):
      ftrace/x86-64: Allow to change RIP in handlers


 arch/x86/kernel/entry_32.S |    3 +--
 arch/x86/kernel/entry_64.S |    4 ++++
 arch/x86/kernel/kprobes.c  |   43 +++++++++++++++++++++++++++++++------------
 kernel/kprobes.c           |    3 ---
 4 files changed, 36 insertions(+), 17 deletions(-)

-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@...achi.com

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