linux-kernel - Re: [PATCH -tip v6 06/22] [BUGFIX] x86: Prohibit probing on memcpy/memset

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Message-ID: <52B3CABE.1080903@hitachi.com>
Date:	Fri, 20 Dec 2013 13:42:38 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Jovi Zhangwei <jovi.zhangwei@...il.com>
Cc:	Ingo Molnar <mingo@...nel.org>, linux-arch@...r.kernel.org,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Sandeepa Prabhu <sandeepa.prabhu@...aro.org>, x86@...nel.org,
	lkml <linux-kernel@...r.kernel.org>,
	"Steven Rostedt (Red Hat)" <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...hat.com>, systemtap@...rceware.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH -tip v6 06/22] [BUGFIX] x86: Prohibit probing on memcpy/memset

(2013/12/20 12:07), Jovi Zhangwei wrote:
> On Fri, Dec 20, 2013 at 10:37 AM, Masami Hiramatsu
> <masami.hiramatsu.pt@...achi.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@...achi.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.

Thank you,

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


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