From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757137AbZBKTuu (ORCPT ); Wed, 11 Feb 2009 14:50:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755985AbZBKTul (ORCPT ); Wed, 11 Feb 2009 14:50:41 -0500 Received: from terminus.zytor.com ([198.137.202.10]:35507 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755957AbZBKTul (ORCPT ); Wed, 11 Feb 2009 14:50:41 -0500 Message-ID: <49932BF4.2040008@zytor.com> Date: Wed, 11 Feb 2009 11:50:12 -0800 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Brian Gerst CC: "H. Peter Anvin" , Tejun Heo , Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] x86: Pass in pt_regs pointer for syscalls that need it References: <1234277507-4987-1-git-send-email-brgerst@gmail.com> <1234277507-4987-3-git-send-email-brgerst@gmail.com> <49931067.4090802@kernel.org> <73c1f2160902111027s2509f31fq732907bde8db775e@mail.gmail.com> In-Reply-To: <73c1f2160902111027s2509f31fq732907bde8db775e@mail.gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Brian Gerst wrote: > > I guess I could go back to extracting the args from the pt_regs struct > given just the pointer. How do you intend to handle system calls in > your changes (normal ones, not needing pt_regs)? > My plan was to by default load up the three first arguments in (%eax, %edx, %ecx) followed by the remaining arguments on the stack... I currently have it as a reorganized struct pt_regs, but I'm still trying to figure out if it would make more sense from a correctness and performance perspective to instead have duplicates of these entries. For the pt_regs-using registers, they would need a tiny trampoline, looking like: leal 16(%esp),%eax jmp -hpa