linux-kernel - Re: [RFC 28/31] x86/alternative: Create symbols for special section entries

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Message-ID: <20240906165331.u2vlaurjfotxci6h@treble>
Date: Fri, 6 Sep 2024 09:53:31 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Borislav Petkov <bp@...en8.de>
Cc: Peter Zijlstra <peterz@...radead.org>, live-patching@...r.kernel.org,
	linux-kernel@...r.kernel.org, x86@...nel.org,
	Miroslav Benes <mbenes@...e.cz>, Petr Mladek <pmladek@...e.com>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	Jiri Kosina <jikos@...nel.org>,
	Marcos Paulo de Souza <mpdesouza@...e.com>,
	Song Liu <song@...nel.org>, Michael Matz <matz@...e.de>
Subject: Re: [RFC 28/31] x86/alternative: Create symbols for special section
 entries

On Fri, Sep 06, 2024 at 12:19:09PM +0200, Borislav Petkov wrote:
> Right, I was talking to Michael about it yesterday, CCed.
> 
> He suggested that you might be better off creating these annotations by
> sticking the required info in a section instead of generating symbols.
> 
> I.e.,
> 
> .pushsection .klp_objects
>  .size \\name\\@, \\end - .\n"
>  ...
> .popsection

".size" directive references a "name" symbol, did you mean it would just
annotate the entry like so?

  .pushsection .klp_objects
  .long \\start - .
  .long \\end - .
  .popsection

That's definitely possible, but it's much less cleaner for objtool diff,
which works by cloning symbols and their dependencies.

If the symbols are your concern, they could easily be stripped with a
trivial change to scripts/kallsyms.c:is_ignored_symbol() as Peter
suggested.

-- 
Josh