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Date:   Tue, 23 Nov 2021 22:16:36 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Joe Lawrence <joe.lawrence@redhat.com>
Cc:     Miroslav Benes <mbenes@suse.cz>, joao@overdrivepizza.com,
        nstange@suse.de, pmladek@suse.cz, jpoimboe@redhat.com,
        live-patching@vger.kernel.org
Subject: Re: CET/IBT support and live-patches
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On Tue, Nov 23, 2021 at 03:58:51PM -0500, Joe Lawrence wrote:

> Yep, kpatch-build uses its own klp-relocation conversion and not kallsyms.
> 
> I'm not familiar with CET/IBT, but it sounds like if a function pointer
> is not taken at build time (or maybe some other annotation), the
> compiler won't generate the needed endbr landing spot in said function?

Currently it does, but then I'm having objtool scribble it on purpose.

>  And that would be a problem for modules using kallsyms lookup to get to
> said function.

Which is ofcourse the whole purpose of the exercise. If it's not
exported you don't get to call it via a back-door :-) This should kill a
whole heap of dodgy modules quite dead I hope.