From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756009AbbIBStD (ORCPT ); Wed, 2 Sep 2015 14:49:03 -0400 Received: from 2.236.17.93.rev.sfr.net ([93.17.236.2]:16852 "EHLO mailhub1.si.c-s.fr" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752597AbbIBStB (ORCPT ); Wed, 2 Sep 2015 14:49:01 -0400 Subject: Re: Strange reports of perf events on powerpc 83xx To: Joakim Tjernlund , "linuxppc-dev@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" , Paul Mackerras , Anton Blanchard , "sukadev@linux.vnet.ibm.com" References: <55DF17A3.7070009@c-s.fr> <1441203638.3349.203.camel@transmode.se> From: christophe leroy Message-ID: <55E74498.10904@c-s.fr> Date: Wed, 2 Sep 2015 20:48:56 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <1441203638.3349.203.camel@transmode.se> Content-Type: text/plain; charset=iso-8859-15; format=flowed Content-Transfer-Encoding: 8bit X-Antivirus: avast! (VPS 150902-0, 02/09/2015), Outbound message X-Antivirus-Status: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 02/09/2015 16:20, Joakim Tjernlund a écrit : > On Thu, 2015-08-27 at 15:58 +0200, leroy christophe wrote: >> Hi, >> >> Has anybody already used 'perf' tool on powerpc MPC83xx ? >> >> I have been succesfully using perf on MPC8xx, but on MPC83xx I get >> something strange. >> >> perf record/report reports addresses on user stack, as if it was mixing >> up D accesses and I accesses. >> >> Any idea of what the problem can be ? > We are also experiencing strange addresses on 83xx, did find the cause > of this problem? > > We are using Linux 4.1.0 I identified this afternoon that the issue comes from perf_instruction_pointer() which reads SPRN_SIAR instead of using the NIP register from the pt_regs struct According to the MPC8323 reference manual, there is no such register. I'm looking at the history in order to fully understand the reason. Looks like PPC_HAVE_PMU_SUPPORT is selected for all PPC_BOOK3S_32 allthought mpc832x has no PMU. Christophe > >> # Samples: 8K of event 'cpu-clock' >> # Event count (approx.): 2196000000 >> # >> # Overhead Command Shared Object Symbol >> # ........ ............ .................. >> ............................................ >> # >> 2.62% perf_reseau4 libpthread-2.18.so [.] __libc_send >> 2.56% perf_reseau4 [kernel.kallsyms] [k] __ip_make_skb >> 1.62% perf_reseau4 [kernel.kallsyms] [k] __ip_append_data.isra.39 >> 1.55% perf_reseau4 [kernel.kallsyms] [k] ip_finish_output >> 1.33% perf_reseau4 [unknown] [k] 0x7ffffd94 >> 1.33% perf_reseau4 [unknown] [k] 0x7ffffd95 >> 1.28% perf_reseau4 [unknown] [k] 0x7ffffd97 >> 1.26% perf_reseau4 [unknown] [k] 0x7ffffda3 >> 1.24% perf_reseau4 [unknown] [k] 0x7ffffd98 >> 1.22% perf_reseau4 [unknown] [k] 0x7ffffd92 >> 1.22% perf_reseau4 [unknown] [k] 0x7ffffd9b >> 1.22% perf_reseau4 [unknown] [k] 0x7ffffdaa >> 1.21% perf_reseau4 [unknown] [k] 0x7ffffd96 >> 1.18% perf_reseau4 [unknown] [k] 0x7ffffda7 >> 1.17% perf_reseau4 [unknown] [k] 0x7ffffd8d >> 1.17% perf_reseau4 [unknown] [k] 0x7ffffd99 >> 1.13% perf_reseau4 [unknown] [k] 0x7ffffd90 >> 1.13% perf_reseau4 [unknown] [k] 0x7ffffda2 >> 1.12% perf_reseau4 [kernel.kallsyms] [k] __local_bh_enable_ip >> 1.12% perf_reseau4 [unknown] [k] 0x7ffffd9c >> 1.12% perf_reseau4 [unknown] [k] 0x7ffffd9e >> 1.10% perf_reseau4 [unknown] [k] 0x7ffffda0 >> 1.08% perf_reseau4 [unknown] [k] 0x7ffffd9f >> 1.08% perf_reseau4 [unknown] [k] 0x7ffffda6 >> 1.05% perf_reseau4 [unknown] [k] 0x7ffffda8 >> 1.02% perf_reseau4 [unknown] [k] 0x7ffffd9a >> 1.01% perf_reseau4 [unknown] [k] 0x7ffffdb0 >> 1.00% perf_reseau4 [unknown] [k] 0x7ffffd89 >> 1.00% perf_reseau4 [unknown] [k] 0x7ffffd8b >> 1.00% perf_reseau4 [unknown] [k] 0x7ffffdac --- L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. https://www.avast.com/antivirus