Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754155AbaD2Dqk (ORCPT ); Mon, 28 Apr 2014 23:46:40 -0400 Received: from terminus.zytor.com ([198.137.202.10]:54921 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751872AbaD2Dqj (ORCPT ); Mon, 28 Apr 2014 23:46:39 -0400 Message-ID: <535F205F.9040101@zytor.com> Date: Mon, 28 Apr 2014 20:45:35 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: "H. Peter Anvin" , Andrew Lutomirski CC: comex , Linux Kernel Mailing List , Linus Torvalds , Ingo Molnar , Alexander van Heukelum , Konrad Rzeszutek Wilk , Boris Ostrovsky , Borislav Petkov , Arjan van de Ven , Brian Gerst , Alexandre Julliard , Andi Kleen , Thomas Gleixner Subject: Re: [PATCH] x86-64: espfix for 64-bit mode *PROTOTYPE* References: <1398120472-6190-1-git-send-email-hpa@linux.intel.com> <535EDEC5.7030209@zytor.com> <535EDF67.3090501@linux.intel.com> <535F108C.9010001@linux.intel.com> In-Reply-To: <535F108C.9010001@linux.intel.com> X-Enigmail-Version: 1.6 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 04/28/2014 07:38 PM, H. Peter Anvin wrote: > On 04/28/2014 05:20 PM, Andrew Lutomirski wrote: >> >> ldttest segfaults on 3.13 and 3.14 for me. It reboots (triple fault?) >> on your branch. It even said this: >> >> qemu-system-x86_64: 9pfs:virtfs_reset: One or more uncluncked fids >> found during reset >> >> I have no idea what an uncluncked fd is :) >> > > It means 9p wasn't properly shut down. > OK, so I found a bug in ldttest.c -- it sets CS to an LDT segment, but it never sets SS to an LDT segment. This means that it should really have zero footprint versus the espfix code, and implies that we instead have another bug involved. Why the espfix code should have any effect whatsoever is a mystery, however... if it indeed does? I have uploaded a fixed ldttest.c, but it seems we might be chasing more than that... -hpa -- 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/