From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: linux-next: add utrace tree Date: Mon, 08 Feb 2010 01:30:10 -0800 Message-ID: <4B6FD9A2.8070008@zytor.com> References: <1264575134.4283.1983.camel@laptop> <1264600792.31321.464.camel@gandalf.stny.rr.com> <4B607B1A.3080007@zytor.com> <20100208065425.GB1290@ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from terminus.zytor.com ([198.137.202.10]:54785 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753355Ab0BHJfn (ORCPT ); Mon, 8 Feb 2010 04:35:43 -0500 In-Reply-To: <20100208065425.GB1290@ucw.cz> Sender: linux-next-owner@vger.kernel.org List-ID: To: Pavel Machek Cc: rostedt@goodmis.org, Linus Torvalds , Peter Zijlstra , Tom Tromey , Kyle Moffett , "Frank Ch. Eigler" , Oleg Nesterov , Andrew Morton , Stephen Rothwell , Fr??d??ric Weisbecker , LKML , Arnaldo Carvalho de Melo , linux-next@vger.kernel.org, utrace-devel@redhat.com, Thomas Gleixner , JimKeniston , Arjan van de Ven On 02/07/2010 10:54 PM, Pavel Machek wrote: >> >> No, it has nothing to do with ring. It has to do with modifying code >> that another CPU could be executing at the same time, and with modifying >> code on the same processor through another virtual alias (they are >> different issues.) The same issues apply regardless of the CPL of the >> processor. > > ...but these are always 'there could be cpu bugs around' issues, > right? Like amd k6. AFAICT x86 always supported self-modifying code > without any extra barriers needed... > *Self*-modifying code, yes. *Cross*-modifying code, no. -hpa