Re: [PATCH 2/2] recordmcount: Handle sections with no non-weak symbols

Christophe Leroy
2022-05-04T17:53:01Z

Le 04/05/2022 à 19:06, Steven Rostedt a écrit :
> On Wed, 4 May 2022 16:50:58 +0000
> Christophe Leroy <christophe.leroy@csgroup.eu> wrote:
>
>> In vmlinux, relocations are resolved, trampolines are installed for
>> unreachable destinations and you don't anymore have a section with all
>> the relocations to mcount. It means 'recordmcount' or whatever tool we
>> use will have to read the code to find all direct calls to mcount, then
>> find all trampolines to mcount then find all calls to those trampolines.
>
> OK, so what you are saying is that in the object file, we can see the
> site that calls mcount, but when it is linked, it may not call mcount,
> but instead it will call a trampoline that will call mcount, thus the
> tool will need to find these calls to the trampolines that call mcount
> as well as the locations that call mcount directly.
>
> Did I get that right?
>

Yes it is what I'm trying to say.

Christophe