Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030338AbbDWQul (ORCPT ); Thu, 23 Apr 2015 12:50:41 -0400 Received: from mail-la0-f52.google.com ([209.85.215.52]:34033 "EHLO mail-la0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966600AbbDWQui (ORCPT ); Thu, 23 Apr 2015 12:50:38 -0400 MIME-Version: 1.0 In-Reply-To: References: <63da6d778f69fd0f1345d9287f6764d58be519fa.1427482099.git.luto@kernel.org> <5538C1C5.7010408@redhat.com> <20150423101840.GC28327@pd.tnic> <5538C8E3.60009@redhat.com> <20150423104401.GF28327@pd.tnic> From: Andy Lutomirski Date: Thu, 23 Apr 2015 09:50:17 -0700 Message-ID: Subject: Re: [tip:x86/vdso] x86/vdso32/syscall.S: Do not load __USER32_DS to %ss To: Denys Vlasenko Cc: Borislav Petkov , Denys Vlasenko , Brian Gerst , Steven Rostedt , Oleg Nesterov , Ingo Molnar , "H. Peter Anvin" , Linus Torvalds , Andy Lutomirski , Will Drewry , =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= , Alexei Starovoitov , Linux Kernel Mailing List , Kees Cook , Thomas Gleixner , "linux-tip-commits@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: 720 Lines: 22 On Thu, Apr 23, 2015 at 9:41 AM, Denys Vlasenko wrote: > An alternative fix would be, if we decided to schedule > in an interrupt, check %ss for zero and reload it > with __KERNEL_DS before schedule. For anyone who has the right hardware (not me!), a possible reproducer is here: https://git.kernel.org/cgit/linux/kernel/git/luto/misc-tests.git/ make && taskset -c 0 ./sysret_ss_attrs_32 --Andy -- Andy Lutomirski AMA Capital Management, LLC -- 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/