linux-kernel - Re: [PATCH][GIT PULL][v2.6.32] tracing/x86: Add check to detect GCC messing with mcount prologue

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20091125162556.GA14233@elte.hu>
Date:	Wed, 25 Nov 2009 17:25:56 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	Jakub Jelinek <jakub@...hat.com>, Andrew Haley <aph@...hat.com>,
	"H.J. Lu" <hjl.tools@...il.com>, rostedt@...dmis.org,
	"H. Peter Anvin" <hpa@...or.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	feng.tang@...el.com, Peter Zijlstra <peterz@...radead.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	David Daney <ddaney@...iumnetworks.com>,
	Richard Guenther <richard.guenther@...il.com>,
	gcc <gcc@....gnu.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH][GIT PULL][v2.6.32] tracing/x86: Add check to detect GCC
 messing with mcount prologue


* Thomas Gleixner <tglx@...utronix.de> wrote:

> On Wed, 25 Nov 2009, Ingo Molnar wrote:
> > * Thomas Gleixner <tglx@...utronix.de> wrote:
> > 
> > > On Tue, 24 Nov 2009, Jakub Jelinek wrote:
> > > 
> > > > On Tue, Nov 24, 2009 at 03:55:49PM +0100, Thomas Gleixner wrote:
> > > > > > you should compile your code with -maccumulate-outgoing-args, and there's
> > > > > > no need to use -mtune=generic.  Is that right?
> > > > > 
> > > > > Seems to work. What other side effects has that ?
> > > > 
> > > > Faster code, significant increase in code size though.  Note that on many
> > > > architectures it is the only supported model.
> > > 
> > > Just checked on the affected -marchs. The increase in code size is 
> > > about 3% which is not that bad and definitely acceptable for the 
> > > tracing case. Will zap the -mtune=generic patch and use 
> > > -maccumulate-outgoing-args instead.
> > 
> > hm, 3% sounds quite large :( dyn-ftrace is enabled in distro configs, so 
> > 3% is a big deal IMO.
> 
> Distro-configs have -mtune=generic anyway. So it's not changing
> anything for them.
> 
> I'm talking about the -march flags which result in that weird code
> (pentium-mmx ....).

ok!

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/