From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751414AbbEAQTH (ORCPT ); Fri, 1 May 2015 12:19:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41741 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751304AbbEAQTG (ORCPT ); Fri, 1 May 2015 12:19:06 -0400 Message-ID: <5543A774.5010501@redhat.com> Date: Fri, 01 May 2015 12:19:00 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Andy Lutomirski CC: =?UTF-8?B?RnLpppjpp7tpYyBXZWlzYmVja2Vy?= , X86 , "linux-kernel@vger.kernel.org" , Thomas Gleixner , Denys Vlasenko Subject: Re: context tracking vs. syscall_trace_leave & do_notify_resume loop References: <5542D730.2050903@redhat.com> <5543A302.1020205@redhat.com> <5543A680.9050106@redhat.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/01/2015 12:16 PM, Andy Lutomirski wrote: > On Fri, May 1, 2015 at 9:14 AM, Rik van Riel wrote: >> On 05/01/2015 12:05 PM, Andy Lutomirski wrote: >>> On Fri, May 1, 2015 at 9:00 AM, Rik van Riel wrote: >> >>>> I suspect we probably only need two possible function >>>> calls at syscall exit time: >>>> >>>> 1) A function that is called with interrupts still >>>> enabled, testing flags that could be set again >>>> if something happens (eg. preemption) between >>>> when the function is called, and we return to >>>> user space. >>>> >>>> 2) A function that is called after the point of >>>> no return, with interrupts disabled, which >>>> does (mostly) small things that only happen >>>> once. > C can have loops just as easily as assembly can :) I still don't see > why we need magic asm code to schedule and deliver signals. We > certainly need to have valid pt_regs to deliver signals, but that's > easy and much cheaper than it used to be. Oh, I never said it would all have to be in assembly :) I would love to see the stuff in entry.S greatly simplified. -- All rights reversed