Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964836AbbGYTdb (ORCPT ); Sat, 25 Jul 2015 15:33:31 -0400 Received: from mail-lb0-f173.google.com ([209.85.217.173]:36327 "EHLO mail-lb0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964778AbbGYTda (ORCPT ); Sat, 25 Jul 2015 15:33:30 -0400 MIME-Version: 1.0 In-Reply-To: <55B3D715.2020308@redhat.com> References: <1437745668-31802-1-git-send-email-dvlasenk@redhat.com> <1437745668-31802-2-git-send-email-dvlasenk@redhat.com> <55B3D715.2020308@redhat.com> From: Andy Lutomirski Date: Sat, 25 Jul 2015 12:33:08 -0700 Message-ID: Subject: Re: [PATCH 2/3] x86/asm/entry/32: Remove most of SYSCALL32 code, part 1 To: Denys Vlasenko Cc: Ingo Molnar , Linus Torvalds , "Krzysztof A. Sobiecki" , Steven Rostedt , Borislav Petkov , "H. Peter Anvin" , Oleg Nesterov , Frederic Weisbecker , Alexei Starovoitov , Will Drewry , Kees Cook , X86 ML , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1797 Lines: 46 On Sat, Jul 25, 2015 at 11:36 AM, Denys Vlasenko wrote: > On 07/24/2015 07:50 PM, Andy Lutomirski wrote: >> On Fri, Jul 24, 2015 at 6:47 AM, Denys Vlasenko wrote: >>> SYSCALL32 code is nearly identical to SYSCALL32, except for initial >>> section. Merge them. >>> >>> The removal is split into two parts, to make review eaiser. This is part 1. >>> >>> auditsys_entry_common and auditsys_exit macros are indented one more tab without >>> any changes. This prevents diff from becoming unreadable. >>> They will be removed in part 2. >> >> I need to read these more closely, which is, at present, exceeding my >> ability to look at asm. (See the big NMI thread.) I'll look soon. > > The "sysenter_fix_flags" thingy prevented the diff from being > a pure delete, so it is not as clear as I hoped. > > What patch is doing is actually very simple. It "amputates" > entire SYSENTER code path after it finished creating partially > filled pt_regs, loaded arg6 and dealt with EFLAGS sanitization - > after this is done, the state is identical to the similar > state in SYSCALL code, so we can just use SYSCALL code from that moment > onward! :) > I certainly agree that your patches are a nice cleanup. I just want to make sure there isn't something subtle and undocumented going on there. > >> Meanwhile, this code is incredibly fragile wrt syscall restart. >> (Syscall restart on compat is really weird.) > > Weird in what way? See: https://lkml.kernel.org/g/20110821084230.GI2203@ZenIV.linux.org.uk --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/