From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934010AbcALNJV (ORCPT ); Tue, 12 Jan 2016 08:09:21 -0500 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:48218 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753379AbcALNJU (ORCPT ); Tue, 12 Jan 2016 08:09:20 -0500 Date: Tue, 12 Jan 2016 13:08:15 +0000 From: One Thousand Gnomes To: Peter Zijlstra Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Stephane Eranian , Namhyung Kim , LKML , Jiri Olsa , Namhyung Kim , Adrian Hunter , "ak@linux.intel.com" Subject: Re: [RFC] perf record: missing buildid for callstack modules Message-ID: <20160112130815.77c1a4fa@lxorguk.ukuu.org.uk> In-Reply-To: <20160112113521.GC6357@twins.programming.kicks-ass.net> References: <20160107215945.GA19314@kernel.org> <80F05A66-6943-499A-B402-96249953CD15@gmail.com> <20160107234746.GB19314@kernel.org> <20160108181942.GB20576@kernel.org> <20160111173036.GA6344@twins.programming.kicks-ass.net> <20160112103943.GA6310@gmail.com> <20160112113521.GC6357@twins.programming.kicks-ass.net> Organization: Intel Corporation X-Mailer: Claws Mail 3.12.0 (GTK+ 2.24.29; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > And we cannot, at mmap() time, 'assume' the file is ELF and try prodding > into it to find a buildid or whatnot. And you cannot at any time assume that something like NFS won't change the page contents under you. In fact it's valid (but completely insane) to use MAP_DISCARD to throw away part of your program and page it back in again so that a daemon on the other side of the NFS can change the code you are executing 8) Alan