From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754972AbZAFKJd (ORCPT ); Tue, 6 Jan 2009 05:09:33 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751332AbZAFKJV (ORCPT ); Tue, 6 Jan 2009 05:09:21 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:44387 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753118AbZAFKJU (ORCPT ); Tue, 6 Jan 2009 05:09:20 -0500 Date: Tue, 6 Jan 2009 11:09:06 +0100 From: Ingo Molnar To: Hiroshi Shimamoto Cc: Thomas Gleixner , "H. Peter Anvin" , linux-kernel@vger.kernel.org Subject: Re: [RFC -tip 0/4] x86: reduce fixup of uaccess Message-ID: <20090106100906.GA14185@elte.hu> References: <4962CAAE.6090300@ct.jp.nec.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4962CAAE.6090300@ct.jp.nec.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Hiroshi Shimamoto wrote: > This is my second try to reduce fixup code size for exceptions of uaccess. > > This patch series reduces fixup code for exceptions of uaccess in signal. > > I gave up to make direct jump to end of function when an exception occurs. > However, I thought fixup code could be reduced. The concept is that to add > uaccess_err in thread_info and set it to -EFAULT on exception, finally check > this value on the last of function. > > Is this good to reduce code size? > > The code size reductions are below; > $ size *signal*.o.* > text data bss dec hex filename > 4741 0 0 4741 1285 ia32_signal.o.new > 6006 0 0 6006 1776 ia32_signal.o.old > 3577 0 0 3577 df9 signal.o.new > 4540 0 0 4540 11bc signal.o.old > 3855 0 0 3855 f0f signal32.o.new > 4876 0 0 4876 130c signal32.o.old looks very nice! Since kernel execution is i-cache-cold in the typical case, this will probably transform into a performance improvement as well. Ingo