From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758907AbXEaVih (ORCPT ); Thu, 31 May 2007 17:38:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752833AbXEaVia (ORCPT ); Thu, 31 May 2007 17:38:30 -0400 Received: from tomts16.bellnexxia.net ([209.226.175.4]:64761 "EHLO tomts16-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752666AbXEaVi3 (ORCPT ); Thu, 31 May 2007 17:38:29 -0400 Date: Thu, 31 May 2007 17:38:27 -0400 From: Mathieu Desnoyers To: Andrew Morton Cc: linux-kernel@vger.kernel.org Subject: Re: [patch 8/9] F00F bug fixup for i386 - use conditional calls Message-ID: <20070531213827.GD904@Krystal> References: <20070530140025.917261793@polymtl.ca> <20070530140229.491376274@polymtl.ca> <20070530133359.5a553e0c.akpm@linux-foundation.org> <20070531210755.GA904@Krystal> <20070531142138.60dbc8a9.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <20070531142138.60dbc8a9.akpm@linux-foundation.org> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 17:37:47 up 3 days, 6:16, 4 users, load average: 0.04, 0.22, 0.24 User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Andrew Morton (akpm@linux-foundation.org) wrote: > On Thu, 31 May 2007 17:07:55 -0400 > Mathieu Desnoyers wrote: > > > * Andrew Morton (akpm@linux-foundation.org) wrote: > > > > > > Use the faster conditional calls for F00F bug handling in do_page_fault. > > > > > > > > > > I guess this means that CONDCALL will be enabled on pretty much all i386, > > > in which case making the whole feature Kconfigurable is starting to look > > > marginal. > > > > > > Perhaps a better approach would have to made this change dependent upon > > > CONDCALL, rather than forcing it on. > > > > > > > Do you mean making X86_F00F_BUG depend on COND_CALL instead of selecting > > it ? > > yup > > > > > + if (cond_call(fix_f00f, do_f00f_workaround(regs, address))) > > > > + return; > > > > > > We do a cond_call() to an inlined function? That's a bit weird, isn't it? > > > > > > > Yes, but it works :) I will add this information to the documentation. > > But why does it work? Did the compiler generate an out-of-line copy > of the function? If so, we'll end up with multiple copies of the function if > there are other callers. If not, the `inline' was pointless. Yes, it's doing an out-of-line copy. Just like the compiler would have done if we place a call to an inline function within a if() { } block. -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68