Re: [PATCH 10/18] objtool: Extricate ibt from stack validation

From: Josh Poimboeuf
Date: Thu Apr 14 2022 - 13:12:39 EST


On Thu, Apr 14, 2022 at 06:38:16PM +0200, Peter Zijlstra wrote:
> On Thu, Apr 14, 2022 at 08:44:49AM -0700, Josh Poimboeuf wrote:
>
> > Ok. That was subtle, it needs a comment or two. I had the distinct
> > feeling I was introducing a bug, then I got distracted ;-)
>
> Right, lemme try and not forget to write one ;-)

I'm rewriting the code anyway, I'll add some comments.

> > Doesn't the compiler give those special cases ENDBR anyway? Just
> > wondering why we avoid the warning for those.
>
> Sure, but this is about not scribbling that ENDBR with a NOP.

Right, but it only prints warnings for data sections, despite marking
others:

- dest = validate_ibt_reloc(file, reloc);
- if (is_data && dest && !dest->noendbr)
- warn_noendbr("data ", sec, reloc->offset, dest);


--
Josh