linux-kernel - Re: [PATCH modules-next v10 00/13] kallsyms: reliable symbol->address lookup with /proc/kallmodsyms

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Message-ID: <ZEeO_rWL4bDh5vui@alley>
Date:   Tue, 25 Apr 2023 10:27:42 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Luis Chamberlain <mcgrof@...nel.org>
Cc:     Josh Poimboeuf <jpoimboe@...nel.org>,
        Nick Alcock <nick.alcock@...cle.com>, masahiroy@...nel.org,
        linux-modules@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        linux-kernel@...r.kernel.org, arnd@...db.de,
        akpm@...ux-foundation.org, eugene.loh@...cle.com,
        kris.van.hees@...cle.com, live-patching@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH modules-next v10 00/13] kallsyms: reliable
 symbol->address lookup with /proc/kallmodsyms

On Mon 2023-04-24 12:47:39, Luis Chamberlain wrote:
> On Fri, Apr 07, 2023 at 04:21:18PM -0700, Josh Poimboeuf wrote:
> > Anyway, I was nodding along with the above cover letter until I got to
> > the third paragraph.
> > 
> > A "built-in kernel module" is not actually a module, as it's built in to
> > vmlinux.  I suspect the point is that if you rebuild with a different
> > config, it might become a module.  But many other changes could also
> > occur with a changed config, including changed inlining decisions and
> > GCC IPA optimization function renaming, in which case the symbol might
> > no longer exist with the new config.
> 
> Yes it does not matter, for his tooling effort it was just to be able
> to map a possible module to a symbol so tooling can display this to
> disambiguate.

Note that the same symbol name might be used many times even within
one module. The module might be linked from more .o files. And
more .o files might have a local symbol with the same name.

I think that the best solution is to associate the symbol with
the file name and line. These is very useful information in general.

Best Regards,
Petr