From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753874AbaCJRsg (ORCPT ); Mon, 10 Mar 2014 13:48:36 -0400 Received: from mga02.intel.com ([134.134.136.20]:36895 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751041AbaCJRse (ORCPT ); Mon, 10 Mar 2014 13:48:34 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,625,1389772800"; d="scan'208";a="469708004" Message-ID: <531DFAF0.9070806@linux.intel.com> Date: Mon, 10 Mar 2014 10:48:32 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: Andy Lutomirski CC: Linus Torvalds , Linux Kernel Mailing List , Stefani Seibold , Andreas Brief , Martin Runge Subject: Re: [x86, vdso] BUG: unable to handle kernel paging request at d34bd000 References: <20140307013833.GD8427@localhost> <1394176888.1018.3.camel@wall-e.seibold.net> <1394229220.20013.13.camel@wall-e.seibold.net> <1394354848.1002.37.camel@wall-e.seibold.net> <531D044C.2090303@linux.intel.com> <531DD35A.5060202@linux.intel.com> <531DF549.2090403@linux.intel.com> <531DF896.8010305@linux.intel.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/10/2014 10:46 AM, Andy Lutomirski wrote: >> >> Yes, we'd have to switch the vdso to using syscall access. Doing that >> from inside a system call is... "interesting". > > It's a little less interesting if it just involves changing a vma. > It's still tricky, though -- would each struct mm have its own struct > file for the vvar page? Can this be done with some > vm_operations_struct magic? There are possible races, too, though -- > another thread could access the thing concurrently with a syscall. > Hint: where is your RIP? Where is the RIP of other processes? -hpa