From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757081Ab2LNSsW (ORCPT ); Fri, 14 Dec 2012 13:48:22 -0500 Received: from terminus.zytor.com ([198.137.202.10]:48920 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756687Ab2LNSsV (ORCPT ); Fri, 14 Dec 2012 13:48:21 -0500 Message-ID: <50CB7459.7010107@zytor.com> Date: Fri, 14 Dec 2012 10:47:53 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Andy Lutomirski CC: Pavel Emelyanov , aarcange@redhat.com, ak@linux.intel.com, Stefani Seibold , x86@kernel.org, linux-kernel@vger.kernel.org, criu@openvz.org, mingo@redhat.com, john.stultz@linaro.org, tglx@linutronix.de Subject: Re: [CRIU] [PATCH] Add VDSO time function support for x86 32-bit kernel References: <1355343572-23074-1-git-send-email-stefani@seibold.net> <50C9148C.4040308@zytor.com> <1355378005.24283.11.camel@wall-e> <1d3061cb-76d0-4e42-9b75-a975b05384ec@email.android.com> <1355379433.24701.1.camel@wall-e> <1355383038.18653.2.camel@wall-e> <50CA6E4C.6000305@zytor.com> <50CA81A4.9040702@zytor.com> <50CA85BD.7070502@zytor.com> <8c3585bc-fc7d-4826-913c-f4581494d91d@email.android.com> <50CAE485.5020608@parallels.com> <50CB716D.6020501@zytor.com> In-Reply-To: X-Enigmail-Version: 1.4.6 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 12/14/2012 10:44 AM, Andy Lutomirski wrote: >> >> mremap() should work. At the same time, the code itself is not going to >> have any stability guarantees between kernel versions -- it obviously >> cannot. > > We could guarantee that the symbols in the vdso resolve to particular > offsets within the vdso. (Yes, this is ugly.) > > Does criu support checkpointing with one version of a shared library > and restoring with another? If there are no textrels (or whatever the > relocation type that actually modifies text as opposed to just the plt > or got) then, in principle, it should be doable. Otherwise some > kernel help will be needed to checkpoint reliably on one kernel and > restore somewhere else. > > (This isn't a regression -- it's already broken.) > The real issue is that happens if the process is checkpointed while inside the vdso and now eip/rip or a stack frame points into the vdso. This is not impossible or even unlikely, especially on 32 bits it is downright likely. -hpa