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From: mingo@kernel.org (Ingo Molnar)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] use -fstack-protector-strong
Date: Wed, 27 Nov 2013 12:27:32 +0100	[thread overview]
Message-ID: <20131127112731.GA10435@gmail.com> (raw)
In-Reply-To: <20131126203727.GA352@www.outflux.net>


* Kees Cook <keescook@chromium.org> wrote:

> On a defconfig x86_64 build (with CONFIG_CC_STACKPROTECTOR enabled), the
> delta in size is just under 9% larger:
> 
>  -rwxrwxr-x 1 kees kees  22134340 Nov 26 10:28 vmlinux.gcc-4.8
>  -rwxrwxr-x 1 kees kees  22123870 Nov 26 10:40 vmlinux.gcc-4.9
>  -rwxrwxr-x 1 kees kees  24225118 Nov 26 10:42 vmlinux.gcc-4.9+strong

Please run it through 'size' so that we know the real text size 
increases.

If the cost of -fstack-protector-strong is really +9% in kernel text 
size then that's rather significant!

If this option blows up our performance critical codepaths as well 
then this will likely cause a runtime slowdown as well, in addition to 
the increase in I$ footprint. That needs to be measured.

CONFIG_CC_STACKPROTECTOR=y is relatively cheap today. For example on 
x86-64 defconfig:

      text    data    bss     dec       filename
  11378972    1455056 1191936 14025964  vmlinux  # CONFIG_CC_STACKPROTECTOR is not set
  11420243    1455056 1191936 14067235  vmlinux  CONFIG_CC_STACKPROTECTOR=y

that's a +0.3% cost currently.

Thanks,

	Ingo

WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: linux-kernel@vger.kernel.org,
	Nicolas Pitre <nicolas.pitre@linaro.org>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Russell King <linux@arm.linux.org.uk>,
	Thomas Gleixner <tglx@linutronix.de>,
	x86@kernel.org, Shawn Guo <shawn.guo@linaro.org>,
	Olof Johansson <olofj@chromium.org>,
	linux-arm-kernel@lists.infradead.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v2] use -fstack-protector-strong
Date: Wed, 27 Nov 2013 12:27:32 +0100	[thread overview]
Message-ID: <20131127112731.GA10435@gmail.com> (raw)
In-Reply-To: <20131126203727.GA352@www.outflux.net>


* Kees Cook <keescook@chromium.org> wrote:

> On a defconfig x86_64 build (with CONFIG_CC_STACKPROTECTOR enabled), the
> delta in size is just under 9% larger:
> 
>  -rwxrwxr-x 1 kees kees  22134340 Nov 26 10:28 vmlinux.gcc-4.8
>  -rwxrwxr-x 1 kees kees  22123870 Nov 26 10:40 vmlinux.gcc-4.9
>  -rwxrwxr-x 1 kees kees  24225118 Nov 26 10:42 vmlinux.gcc-4.9+strong

Please run it through 'size' so that we know the real text size 
increases.

If the cost of -fstack-protector-strong is really +9% in kernel text 
size then that's rather significant!

If this option blows up our performance critical codepaths as well 
then this will likely cause a runtime slowdown as well, in addition to 
the increase in I$ footprint. That needs to be measured.

CONFIG_CC_STACKPROTECTOR=y is relatively cheap today. For example on 
x86-64 defconfig:

      text    data    bss     dec       filename
  11378972    1455056 1191936 14025964  vmlinux  # CONFIG_CC_STACKPROTECTOR is not set
  11420243    1455056 1191936 14067235  vmlinux  CONFIG_CC_STACKPROTECTOR=y

that's a +0.3% cost currently.

Thanks,

	Ingo

  reply	other threads:[~2013-11-27 11:27 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-26 20:37 [PATCH v2] use -fstack-protector-strong Kees Cook
2013-11-26 20:37 ` Kees Cook
2013-11-27 11:27 ` Ingo Molnar [this message]
2013-11-27 11:27   ` Ingo Molnar
2013-11-27 17:21   ` Kees Cook
2013-11-27 17:21     ` Kees Cook
2013-11-27 17:54     ` Ingo Molnar
2013-11-27 17:54       ` Ingo Molnar
2013-11-27 17:55       ` H. Peter Anvin
2013-11-27 17:55         ` H. Peter Anvin
2013-11-27 18:11         ` Kees Cook
2013-11-27 18:11           ` Kees Cook
2013-12-17  0:57           ` Kees Cook
2013-12-17  0:57             ` Kees Cook
2013-12-17 11:29             ` Ingo Molnar
2013-12-17 11:29               ` Ingo Molnar

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