From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Andrew Morton <akpm@linux-foundation.org>,
20190819234111.9019-8-keescook@chromium.org
Cc: Kees Cook <keescook@chromium.org>,
Peter Zijlstra <peterz@infradead.org>,
Drew Davenport <ddavenport@chromium.org>,
Arnd Bergmann <arnd@arndb.de>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
Feng Tang <feng.tang@intel.com>, Petr Mladek <pmladek@suse.com>,
Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
Borislav Petkov <bp@suse.de>, YueHaibing <yuehaibing@huawei.com>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 7/7] bug: Move WARN_ON() "cut here" into exception handler
Date: Fri, 23 Aug 2019 16:26:59 +0200 [thread overview]
Message-ID: <86003539-18ec-f2ff-a46f-764edb820dcd@c-s.fr> (raw)
In-Reply-To: <20190822155611.a1a6e26db99ba0876ba9c8bd@linux-foundation.org>
Le 23/08/2019 à 00:56, Andrew Morton a écrit :
> On Tue, 20 Aug 2019 09:47:55 -0700 Kees Cook <keescook@chromium.org> wrote:
>
>> Reply-To: 20190819234111.9019-8-keescook@chromium.org
>
> Really?
That seems correct, that's the "[PATCH 7/7] bug: Move WARN_ON() "cut
here" into exception handler" from the series at
https://lkml.org/lkml/2019/8/19/1155
>
>> Subject: [PATCH v2 7/7] bug: Move WARN_ON() "cut here" into exception handler
>
> It's strange to receive a standalone [7/7] patch.
Iaw the Reply_To, I understand it as an update of the 7th patch of the
series.
>
>> Date: Tue, 20 Aug 2019 09:47:55 -0700
>> Sender: linux-kernel-owner@vger.kernel.org
>>
>> The original clean up of "cut here" missed the WARN_ON() case (that
>> does not have a printk message), which was fixed recently by adding
>> an explicit printk of "cut here". This had the downside of adding a
>> printk() to every WARN_ON() caller, which reduces the utility of using
>> an instruction exception to streamline the resulting code. By making
>> this a new BUGFLAG, all of these can be removed and "cut here" can be
>> handled by the exception handler.
>>
>> This was very pronounced on PowerPC, but the effect can be seen on
>> x86 as well. The resulting text size of a defconfig build shows some
>> small savings from this patch:
>>
>> text data bss dec hex filename
>> 19691167 5134320 1646664 26472151 193eed7 vmlinux.before
>> 19676362 5134260 1663048 26473670 193f4c6 vmlinux.after
>>
>> This change also opens the door for creating something like BUG_MSG(),
>> where a custom printk() before issuing BUG(), without confusing the "cut
>> here" line.
>
> I can't get this to apply to anything, so I guess that [1/7]-[6/7]
> mattered ;)
On my side it applies cleanly on top of patch 1-6 of the series.
Christophe
>
>> Reported-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> Fixes: Fixes: 6b15f678fb7d ("include/asm-generic/bug.h: fix "cut here" for WARN_ON for __WARN_TAINT architectures")
>
> I'm seeing double.
>
>> Signed-off-by: Kees Cook <keescook@chromium.org>
WARNING: multiple messages have this Message-ID (diff)
From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Andrew Morton <akpm@linux-foundation.org>,
20190819234111.9019-8-keescook@chromium.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Drew Davenport <ddavenport@chromium.org>,
Arnd Bergmann <arnd@arndb.de>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
Feng Tang <feng.tang@intel.com>, Petr Mladek <pmladek@suse.com>,
Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
Borislav Petkov <bp@suse.de>, YueHaibing <yuehaibing@huawei.com>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 7/7] bug: Move WARN_ON() "cut here" into exception handler
Date: Fri, 23 Aug 2019 16:26:59 +0200 [thread overview]
Message-ID: <86003539-18ec-f2ff-a46f-764edb820dcd@c-s.fr> (raw)
Message-ID: <20190823142659.9F-KtwOXswPwSJU_LChgXXu8Cqh8BU91w2-8tgwWmLE@z> (raw)
In-Reply-To: <20190822155611.a1a6e26db99ba0876ba9c8bd@linux-foundation.org>
Le 23/08/2019 à 00:56, Andrew Morton a écrit :
> On Tue, 20 Aug 2019 09:47:55 -0700 Kees Cook <keescook@chromium.org> wrote:
>
>> Reply-To: 20190819234111.9019-8-keescook@chromium.org
>
> Really?
That seems correct, that's the "[PATCH 7/7] bug: Move WARN_ON() "cut
here" into exception handler" from the series at
https://lkml.org/lkml/2019/8/19/1155
>
>> Subject: [PATCH v2 7/7] bug: Move WARN_ON() "cut here" into exception handler
>
> It's strange to receive a standalone [7/7] patch.
Iaw the Reply_To, I understand it as an update of the 7th patch of the
series.
>
>> Date: Tue, 20 Aug 2019 09:47:55 -0700
>> Sender: linux-kernel-owner@vger.kernel.org
>>
>> The original clean up of "cut here" missed the WARN_ON() case (that
>> does not have a printk message), which was fixed recently by adding
>> an explicit printk of "cut here". This had the downside of adding a
>> printk() to every WARN_ON() caller, which reduces the utility of using
>> an instruction exception to streamline the resulting code. By making
>> this a new BUGFLAG, all of these can be removed and "cut here" can be
>> handled by the exception handler.
>>
>> This was very pronounced on PowerPC, but the effect can be seen on
>> x86 as well. The resulting text size of a defconfig build shows some
>> small savings from this patch:
>>
>> text data bss dec hex filename
>> 19691167 5134320 1646664 26472151 193eed7 vmlinux.before
>> 19676362 5134260 1663048 26473670 193f4c6 vmlinux.after
>>
>> This change also opens the door for creating something like BUG_MSG(),
>> where a custom printk() before issuing BUG(), without confusing the "cut
>> here" line.
>
> I can't get this to apply to anything, so I guess that [1/7]-[6/7]
> mattered ;)
On my side it applies cleanly on top of patch 1-6 of the series.
Christophe
>
>> Reported-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> Fixes: Fixes: 6b15f678fb7d ("include/asm-generic/bug.h: fix "cut here" for WARN_ON for __WARN_TAINT architectures")
>
> I'm seeing double.
>
>> Signed-off-by: Kees Cook <keescook@chromium.org>
next prev parent reply other threads:[~2019-08-23 14:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-20 16:47 [PATCH v2 7/7] bug: Move WARN_ON() "cut here" into exception handler Kees Cook
2019-08-22 22:56 ` Andrew Morton
2019-08-22 22:56 ` Andrew Morton
2019-08-23 14:26 ` Christophe Leroy [this message]
2019-08-23 14:26 ` Christophe Leroy
2019-08-24 19:08 ` Kees Cook
2019-08-29 4:55 ` Christophe Leroy
2019-08-29 16:12 ` Kees Cook
2019-08-23 14:56 ` Christophe Leroy
2019-09-09 16:05 ` Sergey Senozhatsky
2019-09-10 8:59 ` Kees Cook
2019-09-10 9:16 ` Sergey Senozhatsky
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