From: Ingo Molnar <mingo@elte.hu>
To: Dave Jones <davej@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
esandeen@redhat.com, cebbert@redhat.com,
Arjan van de Ven <arjan@infradead.org>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: Unnecessary overhead with stack protector.
Date: Thu, 15 Oct 2009 21:07:20 +0200 [thread overview]
Message-ID: <20091015190720.GA19467@elte.hu> (raw)
In-Reply-To: <20091015183540.GA8098@redhat.com>
(Cc:-ed Arjan too.)
* Dave Jones <davej@redhat.com> wrote:
> 113c5413cf9051cc50b88befdc42e3402bb92115 introduced a change that made
> CC_STACKPROTECTOR_ALL not-selectable if someone enables
> CC_STACKPROTECTOR.
>
> We've noticed in Fedora that this has introduced noticable overhead on
> some functions, including those which don't even have any on-stack
> variables.
>
> According to the gcc manpage, -fstack-protector will protect functions
> with as little as 8 bytes of stack usage. So we're introducing a huge
> amount of overhead, to close a small amount of vulnerability (the >0
> && <8 case).
>
> The overhead as it stands right now means this whole option is
> unusable for a distro kernel without reverting the above commit.
Exactly what workload showed overhead, and how much?
Ingo
next prev parent reply other threads:[~2009-10-15 19:08 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-15 18:35 Unnecessary overhead with stack protector Dave Jones
2009-10-15 19:07 ` Ingo Molnar [this message]
2009-10-21 15:50 ` Eric Sandeen
2009-10-21 18:00 ` Arjan van de Ven
2009-10-21 18:59 ` Eric Sandeen
2009-10-21 19:09 ` Eric Sandeen
2009-10-21 19:24 ` Eric Sandeen
2009-10-21 21:08 ` Chuck Ebbert
2009-10-21 19:16 ` XFS stack overhead Ingo Molnar
2009-10-21 19:21 ` Eric Sandeen
2009-10-21 20:22 ` Chuck Ebbert
2009-10-22 1:26 ` Unnecessary overhead with stack protector Andrew Morton
2009-10-26 16:30 ` Chuck Ebbert
2009-10-26 16:37 ` Andrew Morton
2009-10-26 16:56 ` Chuck Ebbert
2009-10-26 20:03 ` Ingo Molnar
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