Subject: Re: [RFC] perf probe: Fix offline module name missmatch issue
To: Masami Hiramatsu <mhiramat@kernel.org>
References: <1461580708-15169-1-git-send-email-ravi.bangoria@linux.vnet.ibm.com>
 <20160426062438.aea663884cf5bd95f766f2d5@kernel.org>
 <20160426111916.50d03e047aaed8112b235686@kernel.org>
Cc: linux-kernel@vger.kernel.org, acme@kernel.org, peterz@infradead.org,
        mingo@redhat.com, alexander.shishkin@linux.intel.com,
        masami.hiramatsu.pt@hitachi.com, wangnan0@huawei.com,
        namhyung@kernel.org, srikar@linux.vnet.ibm.com,
        naveen.n.rao@linux.vnet.ibm.com
From: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Message-ID: <571F2E3D.1010303@linux.vnet.ibm.com>
Date: Tue, 26 Apr 2016 14:30:45 +0530
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.5.1
MIME-Version: 1.0
In-Reply-To: <20160426111916.50d03e047aaed8112b235686@kernel.org>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 939
Lines: 25

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@kernel.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