From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751926AbdGOBnJ (ORCPT ); Fri, 14 Jul 2017 21:43:09 -0400 Received: from fldsmtpe03.verizon.com ([140.108.26.142]:11255 "EHLO fldsmtpe03.verizon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751341AbdGOB1J (ORCPT ); Fri, 14 Jul 2017 21:27:09 -0400 X-IronPort-Anti-Spam-Filtered: false From: "Levin, Alexander (Sasha Levin)" Cc: Masami Hiramatsu , Jiri Olsa , Namhyung Kim , Peter Zijlstra , Arnaldo Carvalho de Melo , "Levin, Alexander (Sasha Levin)" X-Host: challenger.odc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH for v4.9 LTS 30/87] perf probe: Fix to get correct modname from elf header Thread-Topic: [PATCH for v4.9 LTS 30/87] perf probe: Fix to get correct modname from elf header Thread-Index: AQHS/QlV1b4ATZivrk6p5paPEQ2ASg== Date: Sat, 15 Jul 2017 01:26:07 +0000 Message-ID: <20170715012538.10101-30-alexander.levin@verizon.com> References: <20170715012538.10101-1-alexander.levin@verizon.com> In-Reply-To: <20170715012538.10101-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v6F1hDT0023374 From: Masami Hiramatsu [ Upstream commit 1f2ed153b916c95a49a1ca9d7107738664224b7f ] Since 'perf probe' supports cross-arch probes, it is possible to analyze different arch kernel image which has different bits-per-long. In that case, it fails to get the module name because it uses the MOD_NAME_OFFSET macro based on the host machine bits-per-long, instead of the target arch bits-per-long. This fixes above issue by changing modname-offset based on the target archs bit width. This is ok because linux kernel uses LP64 model on 64bit arch. E.g. without this (on x86_64, and target module is arm32): $ perf probe -m build-arm/fs/configfs/configfs.ko -D configfs_lookup p:probe/configfs_lookup :configfs_lookup+0 ^-Here is an empty module name. With this fix, you can see correct module name: $ perf probe -m build-arm/fs/configfs/configfs.ko -D configfs_lookup p:probe/configfs_lookup configfs:configfs_lookup+0 Signed-off-by: Masami Hiramatsu Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/148337043836.6752.383495516397005695.stgit@devbox Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Sasha Levin --- tools/perf/util/probe-event.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index 1d9c02bc00f1..7f1420521ede 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -268,21 +268,6 @@ static bool kprobe_warn_out_range(const char *symbol, unsigned long address) } /* - * NOTE: - * '.gnu.linkonce.this_module' section of kernel module elf directly - * maps to 'struct module' from linux/module.h. This section contains - * actual module name which will be used by kernel after loading it. - * But, we cannot use 'struct module' here since linux/module.h is not - * exposed to user-space. Offset of 'name' has remained same from long - * time, so hardcoding it here. - */ -#ifdef __LP64__ -#define MOD_NAME_OFFSET 24 -#else -#define MOD_NAME_OFFSET 12 -#endif - -/* * @module can be module name of module file path. In case of path, * inspect elf and find out what is actual module name. * Caller has to free mod_name after using it. @@ -296,6 +281,7 @@ static char *find_module_name(const char *module) Elf_Data *data; Elf_Scn *sec; char *mod_name = NULL; + int name_offset; fd = open(module, O_RDONLY); if (fd < 0) @@ -317,7 +303,21 @@ static char *find_module_name(const char *module) if (!data || !data->d_buf) goto ret_err; - mod_name = strdup((char *)data->d_buf + MOD_NAME_OFFSET); + /* + * NOTE: + * '.gnu.linkonce.this_module' section of kernel module elf directly + * maps to 'struct module' from linux/module.h. This section contains + * actual module name which will be used by kernel after loading it. + * But, we cannot use 'struct module' here since linux/module.h is not + * exposed to user-space. Offset of 'name' has remained same from long + * time, so hardcoding it here. + */ + if (ehdr.e_ident[EI_CLASS] == ELFCLASS32) + name_offset = 12; + else /* expect ELFCLASS64 by default */ + name_offset = 24; + + mod_name = strdup((char *)data->d_buf + name_offset); ret_err: elf_end(elf); -- 2.11.0