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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_GIT 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 1763CC04AB6 for ; Tue, 28 May 2019 17:51:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E9C79217F9 for ; Tue, 28 May 2019 17:51:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559065885; bh=46Q44svXPUpVD4scPAxbsdIVi99vSJJDbwx5cLTkPsc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=czz448FimcO1GceghgU31Yc9Jy6C2XB+prJO9Hd2tvOOziImeSa4a+Wzein8AeikL 6Tg6cOF75Xe1ScDrJOsqg+FCENrlFzazrBmR/Lv3nCJnD46NlFkqCVhkkWlflRQKJn krYHR10A6/A2FONY8XvDuzuO4kS/Y51xruh1gNZM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727857AbfE1RvY (ORCPT ); Tue, 28 May 2019 13:51:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:55080 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726827AbfE1RvV (ORCPT ); Tue, 28 May 2019 13:51:21 -0400 Received: from quaco.ghostprotocols.net (unknown [179.97.35.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6BEF52187F; Tue, 28 May 2019 17:51:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559065880; bh=46Q44svXPUpVD4scPAxbsdIVi99vSJJDbwx5cLTkPsc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fTS159N6G/2WmlT44uc51LoUqnfk2+G9bwBYM6ARX+mSeupOKt2qFxtzkwoMnOoux haf03k6l6iy07YjfBj1Ss7wedTWlKR33INH72JymlH6PRWVUpW8DaLkjuVz+8aBCyD IaJlmNAbASiVsxE4uKnWC2JsjwYGH/X/vSW0yLDo= From: Arnaldo Carvalho de Melo To: Ingo Molnar , Thomas Gleixner Cc: Jiri Olsa , Namhyung Kim , Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Thomas Richter , Hendrik Brueckner , Heiko Carstens , Arnaldo Carvalho de Melo Subject: [PATCH 13/14] perf record: Fix s390 missing module symbol and warning for non-root users Date: Tue, 28 May 2019 14:50:19 -0300 Message-Id: <20190528175020.13343-14-acme@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190528175020.13343-1-acme@kernel.org> References: <20190528175020.13343-1-acme@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Richter Command 'perf record' and 'perf report' on a system without kernel debuginfo packages uses /proc/kallsyms and /proc/modules to find addresses for kernel and module symbols. On x86 this works for root and non-root users. On s390, when invoked as non-root user, many of the following warnings are shown and module symbols are missing: proc/{kallsyms,modules} inconsistency while looking for "[sha1_s390]" module! Command 'perf record' creates a list of module start addresses by parsing the output of /proc/modules and creates a PERF_RECORD_MMAP record for the kernel and each module. The following function call sequence is executed: machine__create_kernel_maps machine__create_module modules__parse machine__create_module --> for each line in /proc/modules arch__fix_module_text_start Function arch__fix_module_text_start() is s390 specific. It opens file /sys/module//sections/.text to extract the module's .text section start address. On s390 the module loader prepends a header before the first section, whereas on x86 the module's text section address is identical the the module's load address. However module section files are root readable only. For non-root the read operation fails and machine__create_module() returns an error. Command perf record does not generate any PERF_RECORD_MMAP record for loaded modules. Later command perf report complains about missing module maps. To fix this function arch__fix_module_text_start() always returns success. For root users there is no change, for non-root users the module's load address is used as module's text start address (the prepended header then counts as part of the text section). This enable non-root users to use module symbols and avoid the warning when perf report is executed. Output before: [tmricht@m83lp54 perf]$ ./perf report -D | fgrep MMAP 0 0x168 [0x50]: PERF_RECORD_MMAP ... x [kernel.kallsyms]_text Output after: [tmricht@m83lp54 perf]$ ./perf report -D | fgrep MMAP 0 0x168 [0x50]: PERF_RECORD_MMAP ... x [kernel.kallsyms]_text 0 0x1b8 [0x98]: PERF_RECORD_MMAP ... x /lib/modules/.../autofs4.ko.xz 0 0x250 [0xa8]: PERF_RECORD_MMAP ... x /lib/modules/.../sha_common.ko.xz 0 0x2f8 [0x98]: PERF_RECORD_MMAP ... x /lib/modules/.../des_generic.ko.xz Signed-off-by: Thomas Richter Reviewed-by: Hendrik Brueckner Cc: Heiko Carstens Link: http://lkml.kernel.org/r/20190522144601.50763-4-tmricht@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/arch/s390/util/machine.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/tools/perf/arch/s390/util/machine.c b/tools/perf/arch/s390/util/machine.c index 0b2054007314..a19690a17291 100644 --- a/tools/perf/arch/s390/util/machine.c +++ b/tools/perf/arch/s390/util/machine.c @@ -5,16 +5,19 @@ #include "util.h" #include "machine.h" #include "api/fs/fs.h" +#include "debug.h" int arch__fix_module_text_start(u64 *start, const char *name) { + u64 m_start = *start; char path[PATH_MAX]; snprintf(path, PATH_MAX, "module/%.*s/sections/.text", (int)strlen(name) - 2, name + 1); - - if (sysfs__read_ull(path, (unsigned long long *)start) < 0) - return -1; + if (sysfs__read_ull(path, (unsigned long long *)start) < 0) { + pr_debug2("Using module %s start:%#lx\n", path, m_start); + *start = m_start; + } return 0; } -- 2.20.1