From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8DF6C0044C for ; Wed, 7 Nov 2018 14:10:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 767F52085B for ; Wed, 7 Nov 2018 14:10:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 767F52085B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727945AbeKGXkn (ORCPT ); Wed, 7 Nov 2018 18:40:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58218 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726635AbeKGXkn (ORCPT ); Wed, 7 Nov 2018 18:40:43 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7F5FD31256B1; Wed, 7 Nov 2018 14:10:11 +0000 (UTC) Received: from krava (unknown [10.40.205.37]) by smtp.corp.redhat.com (Postfix) with SMTP id 32451662F3; Wed, 7 Nov 2018 14:10:07 +0000 (UTC) Date: Wed, 7 Nov 2018 15:10:06 +0100 From: Jiri Olsa To: leo.yan@linaro.org Cc: acme@redhat.com, Jiri Olsa , Mathieu Poirier , Coresight ML , linux-kernel@vger.kernel.org Subject: Re: Question: perf dso support for /proc/kallsyms Message-ID: <20181107141006.GD12870@krava> References: <20181102025516.GA25374@leoy-ThinkPad-X240s> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181102025516.GA25374@leoy-ThinkPad-X240s> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Wed, 07 Nov 2018 14:10:11 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 02, 2018 at 10:55:16AM +0800, leo.yan@linaro.org wrote: > Hi all, > > Now I found that if use the command 'perf script' for Arm CoreSight trace > data, it fails to parse kernel symbols if we don't specify kernel vmlinux > file. So when we don't specify kernel symbol files then perf tool will > roll back to use /proc/kallsyms for kernel symbols parsing, as result it will > run into below flow: yep, AFAIK if there's no vmlinux found we fallback to /proc/kallsyms > > thread__find_addr_map(thread, cpumode, MAP__FUNCTION, address, &al); > map__load(al.map); > dso__data_read_offset(al.map->dso, machine, offset, buffer, size); > `-> data_read_offset() so what is the actual error you see in the perf script? unresolved samples? could you please describe your config and workload? thanks, jirka > > I can observe the function data_read_offset() returns failure, this is caused > by checking the offset sanity "if (offset > dso->data.file_size)" (I pasted > the whole function code at below in case you want to get more context for it), > but if perf use "/proc/kallsyms" to load kernel symbols, the variable > 'dso->data.file_size' will be set to zero thus the sanity checking always > thinks the offset is out of the file size bound. > > Now I still don't understand how the dso/map support "/proc/kallsyms" and > have no idea to fix this issue, though I spent some time to look into it. > > Could you give some suggestion for this? Or even better if you have fixing > for this, I am glad to test at my side. > > static ssize_t data_read_offset(struct dso *dso, struct machine *machine, > u64 offset, u8 *data, ssize_t size) > { > if (data_file_size(dso, machine)) > return -1; > > /* Check the offset sanity. */ > if (offset > dso->data.file_size) > return -1; > > if (offset + size < offset) > return -1; > > return cached_read(dso, machine, offset, data, size); > } > > Thanks, > Leo Yan