From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752868AbaBXRgx (ORCPT ); Mon, 24 Feb 2014 12:36:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36227 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752316AbaBXRgv (ORCPT ); Mon, 24 Feb 2014 12:36:51 -0500 Date: Mon, 24 Feb 2014 18:36:40 +0100 From: Jiri Olsa To: Will Deacon Cc: adrian.hunter@intel.com, acme@redhat.com, a.p.zijlstra@chello.nl, linux-kernel@vger.kernel.org Subject: Re: [perf tool] record failure with 3.14-rc4 Message-ID: <20140224173639.GA7597@krava.brq.redhat.com> References: <20140224172440.GF2553@mudshark.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140224172440.GF2553@mudshark.cambridge.arm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 24, 2014 at 05:24:41PM +0000, Will Deacon wrote: > Hi guys, > > If I try to run perf record as a non-root user, I end up with the following > (unhelpful) error: > > $ perf record -e cycles ls > [...] > Not enough memory for reading perf file header > > This is because the addresses in /proc/kallsyms always read as 0x0 when > viewed by a non-privileged user, causing kallsyms__get_function_start to > return 0x0 in args.start. machine__create_kernel_maps then treats this as > an error an returns -1 to perf_session__create_kernel_maps, causing > perf_session__new to fail and perf to exit. > > The perf tool code in 3.13 is perfectly happy creating maps at 0x0, but I > can see this has changed quite substantially in the recent merge window. > > Any ideas? We could fix kallsyms__get_function_start to return < 0 on > failure then fix the checks in the callers. Adrian? hi, not sure it's related, but i sent out rfc some time ago for similar bad error messages: http://marc.info/?l=linux-kernel&m=138572558210216&w=2 maybe it could be updated for your case as well, I'll try to check deeply later jirka