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Re: [PATCH -tip v6 06/22] [BUGFIX] x86: Prohibit probing on memcpy/memset
- From: Jovi Zhangwei <jovi dot zhangwei at gmail dot com>
- To: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- Cc: Ingo Molnar <mingo at kernel dot org>, linux-arch at vger dot kernel dot org, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Sandeepa Prabhu <sandeepa dot prabhu at linaro dot org>, x86 at kernel dot org, lkml <linux-kernel at vger dot kernel dot org>, "Steven Rostedt (Red Hat)" <rostedt at goodmis dot org>, Ingo Molnar <mingo at redhat dot com>, systemtap at sourceware dot org, "H. Peter Anvin" <hpa at zytor dot com>, Thomas Gleixner <tglx at linutronix dot de>, "David S. Miller" <davem at davemloft dot net>
- Date: Fri, 20 Dec 2013 11:07:51 +0800
- Subject: Re: [PATCH -tip v6 06/22] [BUGFIX] x86: Prohibit probing on memcpy/memset
- Authentication-results: sourceware.org; auth=none
- References: <20131219090353 dot 14309 dot 15496 dot stgit at kbuild-fedora dot novalocal> <20131219090409 dot 14309 dot 25677 dot stgit at kbuild-fedora dot novalocal> <CAGdX0WFKYHqXrVQ6LBw0YgH_H6cP=LZVCBe1iOvEXsHQPD8Zmg at mail dot gmail dot com> <52B3AD7D dot 2020104 at hitachi dot com>
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.