Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756759AbZKRWwj (ORCPT ); Wed, 18 Nov 2009 17:52:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753904AbZKRWwi (ORCPT ); Wed, 18 Nov 2009 17:52:38 -0500 Received: from terminus.zytor.com ([198.137.202.10]:60594 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753343AbZKRWwi (ORCPT ); Wed, 18 Nov 2009 17:52:38 -0500 Message-ID: <4B047A81.3060104@zytor.com> Date: Wed, 18 Nov 2009 14:51:45 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.4pre) Gecko/20091014 Fedora/3.0-2.8.b4.fc11 Thunderbird/3.0b4 MIME-Version: 1.0 To: Jason Baron CC: linux-kernel@vger.kernel.org, mingo@elte.hu, mathieu.desnoyers@polymtl.ca, tglx@linutronix.de, rostedt@goodmis.org, andi@firstfloor.org, roland@redhat.com, rth@redhat.com, mhiramat@redhat.com Subject: Re: [RFC PATCH 0/6] jump label v3 References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 713 Lines: 17 On 11/18/2009 02:43 PM, Jason Baron wrote: > > I'm using an atomic 5 byte no-op for x86_64 and a long jump for 32-bit x86. > My understanding is that not all 32-bit processors have an atomic 5 byte no-op, > and thus using a long jump or jump 0, for the off case is the safest. > 67 66 8D 74 00 (lea si,[si+0]) should work as a 32-bit atomic NOP. It's not necessarily the fastest, though (I have no data on that.) Similarly, 66 66 66 66 90 should also work. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/