From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger-Tang Date: Mon, 21 Nov 2005 22:38:18 +0000 Subject: Re: Fix asm constraint in put_user Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On 11/21/05, Andreas Schwab 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