Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752227AbcDZO1A (ORCPT ); Tue, 26 Apr 2016 10:27:00 -0400 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:38436 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751986AbcDZO06 (ORCPT ); Tue, 26 Apr 2016 10:26:58 -0400 X-IBM-Helo: d23dlp02.au.ibm.com X-IBM-MailFrom: ravi.bangoria@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org From: Ravi Bangoria To: linux-kernel@vger.kernel.org Cc: acme@kernel.org, peterz@infradead.org, mingo@redhat.com, alexander.shishkin@linux.intel.com, mhiramat@kernel.org, wangnan0@huawei.com, namhyung@kernel.org, srikar@linux.vnet.ibm.com, naveen.n.rao@linux.vnet.ibm.com, Ravi Bangoria Subject: [PATCH 2/2] perf probe: Fix offline module name missmatch issue Date: Tue, 26 Apr 2016 19:55:41 +0530 Message-Id: <1461680741-12517-2-git-send-email-ravi.bangoria@linux.vnet.ibm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1461680741-12517-1-git-send-email-ravi.bangoria@linux.vnet.ibm.com> References: <1461680741-12517-1-git-send-email-ravi.bangoria@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16042614-1618-0000-0000-00004586703B Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3432 Lines: 119 Perf can add a probe on kernel module which has not been loaded yet. Current implementation finds module name from path. But if filename is different from actual module name then perf fails to register probe while loading module because of mismatch in names. For example, samples/kobject/kobject-example.ko is loaded as kobject_example. Before applying patch: $ sudo ./perf probe -m /linux/samples/kobject/kobject-example.ko foo_show Added new event: probe:foo_show (on foo_show in kobject-example) You can now use it in all perf tools, such as: perf record -e probe:foo_show -aR sleep 1 $ cat /sys/kernel/debug/tracing/kprobe_events p:probe/foo_show kobject-example:foo_show $ insmod kobject-example.ko $ lsmod Module Size Used by kobject_example 16384 0 Generate read to /sys/kernel/kobject_example/foo while recording data with below command $ sudo ./perf record -e probe:foo_show -a [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.093 MB perf.data ] $./perf report --stdio -F overhead,comm,dso,sym Error: The perf.data.old file has no samples! After applying patch: $ sudo ./perf probe -m /linux/samples/kobject/kobject-example.ko foo_show Added new event: probe:foo_show (on foo_show in kobject_example) You can now use it in all perf tools, such as: perf record -e probe:foo_show -aR sleep 1 $ sudo cat /sys/kernel/debug/tracing/kprobe_events p:probe/foo_show kobject_example:foo_show $ insmod kobject-example.ko $ lsmod Module Size Used by kobject_example 16384 0 Generate read to /sys/kernel/kobject_example/foo while recording data with below command $ sudo ./perf record -e probe:foo_show -a [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.097 MB perf.data (8 samples) ] $ sudo ./perf report --stdio -F overhead,comm,dso,sym ... # Samples: 8 of event 'probe:foo_show' # Event count (approx.): 8 # # Overhead Command Shared Object Symbol # ........ ....... ................. ............ # 100.00% cat [kobject_example] [k] foo_show Signed-off-by: Ravi Bangoria --- tools/perf/util/probe-event.c | 19 +++++-------------- 1 file changed, 5 insertions(+), 14 deletions(-) diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c index d58de20..26803e1 100644 --- a/tools/perf/util/probe-event.c +++ b/tools/perf/util/probe-event.c @@ -642,32 +642,23 @@ static int add_module_to_probe_trace_events(struct probe_trace_event *tevs, int ntevs, const char *module) { int i, ret = 0; - char *tmp; + char *mod_name = NULL; if (!module) return 0; - tmp = strrchr(module, '/'); - if (tmp) { - /* This is a module path -- get the module name */ - module = strdup(tmp + 1); - if (!module) - return -ENOMEM; - tmp = strchr(module, '.'); - if (tmp) - *tmp = '\0'; - tmp = (char *)module; /* For free() */ - } + mod_name = find_module_name(module); for (i = 0; i < ntevs; i++) { - tevs[i].point.module = strdup(module); + tevs[i].point.module = + strdup(mod_name ? mod_name : module); if (!tevs[i].point.module) { ret = -ENOMEM; break; } } - free(tmp); + free(mod_name); return ret; } -- 1.9.1