From: David Mosberger-Tang <David.Mosberger@acm.org>
To: linux-ia64@vger.kernel.org
Subject: Re: Fix asm constraint in put_user
Date: Mon, 21 Nov 2005 22:38:18 +0000 [thread overview]
Message-ID: <ed5aea430511211438i3d6187a9if61750bb73ae8583@mail.gmail.com> (raw)
In-Reply-To: <je7jb2nigc.fsf@sykes.suse.de>
On 11/21/05, Andreas Schwab <schwab@suse.de> wrote:
> There is nothing worth clobbering here. The memory written to is
> completely separate to anything GCC knows about. The old version didn't
> clobber either.
That's usually true, but I don't think it's always true. Consider the
case where put_user() is used to write kernel memory (which happens in
the ia32 emulation layer, for example). I agree it's probably
extremely unlikely for this to trigger a real problem (especially
considering that the kernel is compiled without strict aliasing) but
still, the safe thing to do would be to add a "memory" clobber if
there is no better alternative.
--david
--
Mosberger Consulting LLC, voice/fax: 510-744-9372,
http://www.mosberger-consulting.com/
35706 Runckel Lane, Fremont, CA 94536
next prev parent reply other threads:[~2005-11-21 22:38 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-21 15:12 Fix asm constraint in put_user Andreas Schwab
2005-11-21 16:08 ` David Mosberger-Tang
2005-11-21 16:48 ` Andreas Schwab
2005-11-21 19:03 ` James E Wilson
2005-11-21 20:32 ` Andreas Schwab
2005-11-21 21:26 ` Andreas Schwab
2005-11-21 22:11 ` Luck, Tony
2005-11-21 22:38 ` David Mosberger-Tang [this message]
2005-11-23 6:02 ` James E Wilson
2005-11-23 22:08 ` James E Wilson
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