From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754869Ab1GEWWY (ORCPT ); Tue, 5 Jul 2011 18:22:24 -0400 Received: from lennier.cc.vt.edu ([198.82.162.213]:47266 "EHLO lennier.cc.vt.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754206Ab1GEWWW (ORCPT ); Tue, 5 Jul 2011 18:22:22 -0400 X-Mailer: exmh version 2.7.2 01/07/2005 with nmh-1.3-dev To: Frederic Weisbecker Cc: Jan Beulich , Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Arnaldo Carvalho de Melo , LKML , "H. Peter Anvin" Subject: Re: [PATCH 5/6] x86: Remove useless unwinder backlink from irq regs saving In-Reply-To: Your message of "Mon, 04 Jul 2011 15:22:23 +0200." <20110704132158.GA5551@somewhere> From: Valdis.Kletnieks@vt.edu References: <1309624184-9790-1-git-send-email-fweisbec@gmail.com> <1309624184-9790-6-git-send-email-fweisbec@gmail.com> <4E1187E4020000780004BF2C@nat28.tlf.novell.com> <20110704132158.GA5551@somewhere> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1309904488_18528P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Tue, 05 Jul 2011 18:21:28 -0400 Message-ID: <61768.1309904488@turing-police.cc.vt.edu> X-Mirapoint-Received-SPF: 198.82.161.152 auth3.smtp.vt.edu Valdis.Kletnieks@vt.edu 2 pass X-Junkmail-Info: (0) X-Junkmail-Status: score=10/50, host=zidane.cc.vt.edu X-Junkmail-Signature-Raw: score=unknown, refid=str=0001.0A020201.4E138E6C.00AE,ss=1,fgs=0, ip=0.0.0.0, so=2010-07-22 22:03:31, dmn=2009-09-10 00:05:08, mode=multiengine X-Junkmail-IWF: false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --==_Exmh_1309904488_18528P Content-Type: text/plain; charset=us-ascii On Mon, 04 Jul 2011 15:22:23 +0200, Frederic Weisbecker said: > On Mon, Jul 04, 2011 at 08:29:08AM +0100, Jan Beulich wrote: > > >>> On 02.07.11 at 18:29, Frederic Weisbecker wrote: > > > The unwinder backlink in interrupt entry is very useless. > > > It's actually not part of the stack frame chain and thus is > > > never used. > > > > I very much doubt this - see dump_trace()'s comment in its IRQ-stack > > related code portion (and the corresponding use of irq_stack_end[-1]). > > > > Jan > > Good point. I misunderstood that. > > But then I believe I accidentally fixed it back in > "x86: Don't use frame pointer to save old stack on irq entry" by > pushing %rsi instead in the new stack. It contains the backlink to > the old stack. > > If we keep the macro as-is, I'll add a comment to explain further > what is involved there. Ahh.. I was wondering why there wasn't suddenly a very lonely popq out there... :) --==_Exmh_1309904488_18528P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) Comment: Exmh version 2.5 07/13/2001 iD8DBQFOE45ocC3lWbTT17ARAtHHAJ99FxIHzak73r8p/IfHFg1Uaj6aLQCg662k PDlq/BBgcxYMu3NKjXVwLcs= =zeKm -----END PGP SIGNATURE----- --==_Exmh_1309904488_18528P--