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
next prev parent reply other threads:[~2013-11-27 11:27 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-26 20:37 [PATCH v2] use -fstack-protector-strong Kees Cook
2013-11-27 11:27 ` Ingo Molnar [this message]
2013-11-27 17:21 ` Kees Cook
2013-11-27 17:54 ` Ingo Molnar
2013-11-27 17:55 ` H. Peter Anvin
2013-11-27 18:11 ` Kees Cook
2013-12-17 0:57 ` Kees Cook
2013-12-17 11:29 ` Ingo Molnar
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