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References: <20131219090353.14309.15496.stgit@kbuild-fedora.novalocal>	<20131219090409.14309.25677.stgit@kbuild-fedora.novalocal>	<CAGdX0WFKYHqXrVQ6LBw0YgH_H6cP=LZVCBe1iOvEXsHQPD8Zmg@mail.gmail.com>	<52B3AD7D.2020104@hitachi.com>
Date: Fri, 20 Dec 2013 03:07:00 -0000
Message-ID: <CAGdX0WENxTPhFDtcEW6LFhk1SNZc6mEK+JsCDOJmfK8_PS1rxg@mail.gmail.com>
Subject: Re: [PATCH -tip v6 06/22] [BUGFIX] x86: Prohibit probing on memcpy/memset
From: Jovi Zhangwei <jovi.zhangwei@gmail.com>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@kernel.org>, linux-arch@vger.kernel.org, 	Ananth N Mavinakayanahalli <ananth@in.ibm.com>, Sandeepa Prabhu <sandeepa.prabhu@linaro.org>, x86@kernel.org, 	lkml <linux-kernel@vger.kernel.org>, 	"Steven Rostedt (Red Hat)" <rostedt@goodmis.org>, Ingo Molnar <mingo@redhat.com>, systemtap@sourceware.org, 	"H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>, 	"David S. Miller" <davem@davemloft.net>
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X-SW-Source: 2013-q4/txt/msg00455.txt.bz2

On Fri, Dec 20, 2013 at 10:37 AM, Masami Hiramatsu
<masami.hiramatsu.pt@hitachi.com> wrote:
> Hi Jovi,
>
> (2013/12/19 18:37), Jovi Zhangwei wrote:
>> Hi Masami,
>>
>> On Thu, Dec 19, 2013 at 5:04 PM, Masami Hiramatsu
>> <masami.hiramatsu.pt@hitachi.com> wrote:
>>> memcpy/memset functions are fundamental functions and
>>> those are involved in kprobe's exception handling.
>>> Prohibit probing on them to avoid kernel crash.
>>>
>> Would you please let me know the LKML link of that bugfix, I cannot
>> find it in my LKML fold.
>
> Yeah, that was found in my testing environment.
>
>> No objection on this patch. :) just want to know more, It seems there
>> have no problem to probe memcpy in my box, maybe I didn't hit the
>> crash code path.
>
> Ah, I see. Originally the problem happened when I put a probe on
> __memcpy. And it looks the instances of memcpy and __memcpy are
> same on x86-64. Thus I decided to blacklist both. (memset/__memset too)
> Have you ever tried to probe __memcpy on your box?
>
Hmm, still no crash, __memcpy and __memset are both tested.

I use below kprobe related config:

CONFIG_KPROBES=y
CONFIG_JUMP_LABEL=y
CONFIG_OPTPROBES=y
CONFIG_KPROBES_ON_FTRACE=y

Thanks,

Jovi.