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Re: 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: Mon, 23 Dec 2013 12:51:07 +0800
- Subject: Re: 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> <CAGdX0WENxTPhFDtcEW6LFhk1SNZc6mEK+JsCDOJmfK8_PS1rxg at mail dot gmail dot com> <52B3CABE dot 1080903 at hitachi dot com> <CAGdX0WEev84sOyu-uzkDOmQFi_=mza7cPzyC0VkRZe0fD_1+jQ at mail dot gmail dot com> <52B40C00 dot 2060401 at hitachi dot com>
On Fri, Dec 20, 2013 at 5:21 PM, Masami Hiramatsu
<masami.hiramatsu.pt@hitachi.com> wrote:
> (2013/12/20 17:31), Jovi Zhangwei wrote:
>> On Fri, Dec 20, 2013 at 12:42 PM, Masami Hiramatsu
>> <masami.hiramatsu.pt@hitachi.com> wrote:
>>> (2013/12/20 12:07), Jovi Zhangwei wrote:
>>>> 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
>>>
>>> Hmm, I've added some debugging options.
>>>
>>> CONFIG_SLUB_DEBUG=y
>>> CONFIG_X86_DEBUGCTLMSR=y
>>> CONFIG_PNP_DEBUG_MESSAGES=y
>>> CONFIG_DEBUG_INFO=y
>>> CONFIG_DEBUG_FS=y
>>> CONFIG_DEBUG_KERNEL=y
>>> CONFIG_DEBUG_STACK_USAGE=y
>>> CONFIG_DEBUG_MEMORY_INIT=y
>>> CONFIG_DEBUG_STACKOVERFLOW=y
>>> CONFIG_DEBUG_SPINLOCK=y
>>> CONFIG_DEBUG_MUTEXES=y
>>> CONFIG_DEBUG_LOCK_ALLOC=y
>>> CONFIG_DEBUG_LOCKDEP=y
>>> CONFIG_DEBUG_BUGVERBOSE=y
>>> CONFIG_DEBUG_RODATA=y
>>> CONFIG_DEBUG_BOOT_PARAMS=y
>>>
>>> I guess some of them might cause it.
>>>
>> I recompiled the kernel with those config enabled, unfortunately still no crash,
>> I tested on 3.13.0-rc4, a fedora kvm box.
>
> Hmm, it's very odd. I'm running 3.13.0-rc4 x86-64 on the fedora
> kvm box too. here is the full of my kconfig.
>
That configuration is still working for me, no crash for memcpy kprobe test.
I also posted my kernel configration at:
https://gist.github.com/ktap/8091293
I compared two configs, no clue found yet.
Thanks,
Jovi