From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757344AbZBKP7t (ORCPT ); Wed, 11 Feb 2009 10:59:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753143AbZBKP7k (ORCPT ); Wed, 11 Feb 2009 10:59:40 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:34834 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752831AbZBKP7k (ORCPT ); Wed, 11 Feb 2009 10:59:40 -0500 Date: Wed, 11 Feb 2009 16:59:26 +0100 From: Ingo Molnar To: Tejun Heo Cc: Brian Gerst , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] x86: Pass in pt_regs pointer for syscalls that need it Message-ID: <20090211155926.GA26194@elte.hu> References: <1234277507-4987-1-git-send-email-brgerst@gmail.com> <1234277507-4987-3-git-send-email-brgerst@gmail.com> <4992812B.1050800@kernel.org> <73c1f2160902110631j68e58202h3e49288cfe613d66@mail.gmail.com> <4992E396.6000205@kernel.org> <4992E551.4060901@gmail.com> <73c1f2160902110659i776e1d89qc23d89363881572e@mail.gmail.com> <4992E92C.5000000@gmail.com> <73c1f2160902110710u77a563bftf09c460fab6f9136@mail.gmail.com> <4992EB62.3000501@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4992EB62.3000501@gmail.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 * Tejun Heo wrote: > Brian Gerst wrote: > > x86-64 doesn't have the tail-call problem because it doesn't use the > > pt_regs on stack trick for syscall args. All the args are passed in > > registers. > > Yeah, I was saying that we can do about the same thing on x86_32 by > passing in pointer to pt_regs and defining proper syscall wrappers. > It will cost a bit of performance by increasing register pressure tho. Do you mean converting: ptregscall int sys_execve(struct pt_regs *regs, char __user *u_filename, char __user * __user *argv, char __user * __user *envp) to: ptregscall int sys_execve(struct pt_regs *regs) { char __user *u_filename = syscall_arg1(regs); char __user * __user *argv = syscall_arg2(regs); char __user * __user *envp = syscall_arg3(regs); etc.? Ingo