Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753399AbbG2RrT (ORCPT ); Wed, 29 Jul 2015 13:47:19 -0400 Received: from mail-ig0-f173.google.com ([209.85.213.173]:33290 "EHLO mail-ig0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753130AbbG2RrR (ORCPT ); Wed, 29 Jul 2015 13:47:17 -0400 MIME-Version: 1.0 In-Reply-To: References: <1438148483-11932-1-git-send-email-brgerst@gmail.com> <1438148483-11932-5-git-send-email-brgerst@gmail.com> Date: Wed, 29 Jul 2015 10:47:17 -0700 X-Google-Sender-Auth: zqrBKFqfViLKU-GqpWPDBIDtjqw Message-ID: Subject: Re: [PATCH 4/8] x86/vm86: Use the normal pt_regs area for vm86 From: Linus Torvalds To: Brian Gerst Cc: Andy Lutomirski , X86 ML , "linux-kernel@vger.kernel.org" , Ingo Molnar , "H. Peter Anvin" , Denys Vlasenko 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: 1071 Lines: 21 On Wed, Jul 29, 2015 at 10:36 AM, Brian Gerst wrote: > > I think I remember now what the issue was. Since entering vm86 mode > uses force_iret(), the work_pending code path was being taken. I had > to move the call to save_v86_state out of here to handle_signal(), > otherwise it would just restore the 32-bit regs and exit the syscall > without ever entering vm86 mode. But that meant that the test for > kernel CS was seeing the vm86 regs instead of 32-bit regs, and was > failing because it didn't account for the VM bit (if the real-mode CS > looked like RPL 0). A fault would get stuck in a loop because it > couldn't exit to the signal handling code. Hmm. I think we'd want a big comment about that code then, and how it is only used for user-space (including vm86 mode). Linus -- 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/