linux-kernel - Re: [RFC] perf probe: Fix module probe issue if no dwarf support

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Date:	Tue, 26 Apr 2016 14:34:40 +0530
From:	Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com>
To:	Masami Hiramatsu <mhiramat@...nel.org>
Cc:	linux-kernel@...r.kernel.org, acme@...nel.org,
	peterz@...radead.org, mingo@...hat.com,
	alexander.shishkin@...ux.intel.com,
	masami.hiramatsu.pt@...achi.com, wangnan0@...wei.com,
	namhyung@...nel.org, srikar@...ux.vnet.ibm.com,
	naveen.n.rao@...ux.vnet.ibm.com
Subject: Re: [RFC] perf probe: Fix module probe issue if no dwarf support



On Tuesday 26 April 2016 02:59 AM, Masami Hiramatsu wrote:
> On Mon, 25 Apr 2016 16:08:28 +0530
> Ravi Bangoria <ravi.bangoria@...ux.vnet.ibm.com> wrote:
>
>> Perf is not able to register probe in kernel module when dwarf supprt
>> is not there(and so it goes for symtab). Perf passes full path of
>> module where only module name is required which is causing the problem.
>> This patch fixes this issue.
>>
>> Before applying patch:
>>
>>    $ dpkg -s libdw-dev
>>      dpkg-query: package 'libdw-dev' is not installed ...
>>
>>    $ ./perf probe -m /linux/samples/kobject/kobject-example.ko foo_show
>>      Added new event:
>>        probe:foo_show (on foo_show in /linux/samples/kobject/kobject-example.ko)
>>
>>      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 /linux/samples/kobject/kobject-example.ko:foo_show
>>
>> After applying patch:
>>
>>    $ ./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
>>
> Looks good to me :)
> However, it seems that this patch depends on your previous patch
> ("perf probe: Fix offline module name missmatch issue")
> In that case, could you make these a series of patches?
>
> Acked-by: Masami Hiramatsu <mhiramat@...nel.org>

Thanks Masami,

I've sent v2 with changes you suggested. Please review it.

Regards,
Ravi