From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933633AbbIVNfK (ORCPT ); Tue, 22 Sep 2015 09:35:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49986 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752771AbbIVNfH (ORCPT ); Tue, 22 Sep 2015 09:35:07 -0400 Date: Tue, 22 Sep 2015 10:35:04 -0300 From: Arnaldo Carvalho de Melo To: Wang Nan Cc: linux-kernel@vger.kernel.org, lizefan@huawei.com, pi3orama@163.com, Namhyung Kim , Jiri Olsa , Masami Hiramatsu Subject: Re: [PATCH] perf probe: Fix module probing with shortname Message-ID: <20150922133504.GA2580@redhat.com> References: <1442892872-33708-1-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1442892872-33708-1-git-send-email-wangnan0@huawei.com> X-Url: http://acmel.wordpress.com User-Agent: Mutt/1.5.20 (2009-12-10) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Tue, Sep 22, 2015 at 03:34:32AM +0000, Wang Nan escreveu: > After commit 3d39ac538629e4f00a6e1c38d46346f1b8e69505 ("perf machine: > No need to have two DSOs lists"), perf probe with module short name doesn't > work again. For example: > > # lsmod | grep e1000e > e1000e 233472 0 > > # cat /proc/modules | grep e1000e > e1000e 233472 0 - Live 0xffffffffa0073000 > > # cat /proc/kallsyms | grep '\' > ffffffffa0093860 t e1000e_up[e1000e] > > # perf probe -v -m e1000e --add e1000e_up > probe-definition(0): e1000e_up > symbol:e1000e_up file:(null) line:0 offset:0 return:0 lazy:(null) > 0 arguments > Failed to find module e1000e. > Could not open debuginfo. Try to use symbols. > Looking at the vmlinux_path (7 entries long) > Using /lib/modules/4.2.0-rc7+/build/vmlinux for symbols > e1000e_up is out of .text, skip it. > Error: Failed to add events. Reason: No such file or directory (Code: -2) > > This is caused by a misunderstood of dso->kernel in kernel_get_module_dso() > that, for kernel module, dso->kernel is DSO_TYPE_USER. dso->kernel is DSO_TYPE_KERNEL > iff dso is vmlinux. Kernel modules having DSO_TYPE_USER seems to be the bug, no? I'll try to check that... - Arnaldo > > This patch fix 'perf probe -m' with an ad-hoc way. > > After this patch: > > # perf probe -v -m e1000e --add e1000e_up > probe-definition(0): e1000e_up > symbol:e1000e_up file:(null) line:0 offset:0 return:0 lazy:(null) > 0 arguments > Open Debuginfo file: /lib/modules/4.2.0-rc7+/kernel/drivers/net/ethernet/intel/e1000e/e1000e.ko > Try to find probe point from debuginfo. > Matched function: e1000e_up > Probe point found: e1000e_up+0 > Found 1 probe_trace_events. > Opening /sys/kernel/debug/tracing//kprobe_events write=1 > Writing event: p:probe/e1000e_up e1000e:e1000e_up+0 > Added new event: > probe:e1000e_up (on e1000e_up in e1000e) > > You can now use it in all perf tools, such as: > > perf record -e probe:e1000e_up -aR sleep 1 > > # perf probe -l > Failed to find debug information for address ffffffffa0093860 > probe:e1000e_up (on e1000e_up in e1000e) > > Signed-off-by: Wang Nan > Cc: Arnaldo Carvalho de Melo > Cc: Namhyung Kim > Cc: Jiri Olsa > Cc: Masami Hiramatsu > --- > > I think there may be other places where dso->kernel is misused. > machine__process_kernel_mmap_event() may be one of them. If I understand > correctly, 'dso->kernel && is_kernel_module(dso->long_name)' should always > false theoretically. However, I don't have enough time to check whether that > code really cause problem. > > --- > tools/perf/util/probe-event.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c > index 2b78e8f..c7d6d3d 100644 > --- a/tools/perf/util/probe-event.c > +++ b/tools/perf/util/probe-event.c > @@ -270,7 +270,7 @@ static int kernel_get_module_dso(const char *module, struct dso **pdso) > > if (module) { > list_for_each_entry(dso, &host_machine->dsos.head, node) { > - if (!dso->kernel) > + if (dso->kernel) > continue; > if (strncmp(dso->short_name + 1, module, > dso->short_name_len - 2) == 0) > -- > 1.8.3.4