linux-kernel - Re: [RFC] perf probe: Fix offline module name missmatch issue

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Message-ID: <571F2E3D.1010303@linux.vnet.ibm.com>
Date:	Tue, 26 Apr 2016 14:30:45 +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 offline module name missmatch issue

Thanks Masami,

On Tuesday 26 April 2016 07:49 AM, Masami Hiramatsu wrote:
> On Tue, 26 Apr 2016 06:24:38 +0900
> Masami Hiramatsu <mhiramat@...nel.org> wrote:
>>> +/*
>>> + * 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.
>>> + */
> BTW, is there no way to get the module name avoiding to access
> this "hidden" data structure?
> This looks very tricky way...

So this is the same approach kernel use to find module name when module is
loaded. Please refer this function for more detail:

kernel/module.c ::  static struct module *setup_load_info(...)

Regards,
Ravi