Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754582AbaD2Drf (ORCPT ); Mon, 28 Apr 2014 23:47:35 -0400 Received: from mga02.intel.com ([134.134.136.20]:4553 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754441AbaD2Dre (ORCPT ); Mon, 28 Apr 2014 23:47:34 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,948,1389772800"; d="scan'208";a="502660947" Message-ID: <535F20D3.1050407@linux.intel.com> Date: Mon, 28 Apr 2014 20:47:31 -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> <535F205F.9040101@zytor.com> In-Reply-To: <535F205F.9040101@zytor.com> 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 08:45 PM, H. Peter Anvin wrote: > > 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... > In particular, I was already wondered how we avoid an "upside down swapgs" with a #GP on IRET. The answer might be that we don't... -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/