linux-kernel - Re: [PATCH v2 07/10] objtool: check: Allow save/restore hint in non standard function symbols

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Message-ID: <alpine.LSU.2.21.2004011552290.15809@pobox.suse.cz>
Date:   Wed, 1 Apr 2020 15:54:03 +0200 (CEST)
From:   Miroslav Benes <mbenes@...e.cz>
To:     Julien Thierry <jthierry@...hat.com>
cc:     linux-kernel@...r.kernel.org, jpoimboe@...hat.com,
        peterz@...radead.org, raphael.gault@....com
Subject: Re: [PATCH v2 07/10] objtool: check: Allow save/restore hint in non
 standard function symbols

On Fri, 27 Mar 2020, Julien Thierry wrote:

> The kernel code base provides CODE_SYM_START/END to declare assembly
> code sequences that don't follow function standard calling conventions.
> 
> As non-C/non-standard code, these sequences can very much benefit from
> unwind hints. However, when a restore unwind_hint is used in a
> non-function code sequence, objtool will crash when looking for the
> corresponding save hint.
> 
> Record the code symbol an instruction belongs to and look for save hints
> belonging to the same code symbol as the restore hint.
> 
> Signed-off-by: Julien Thierry <jthierry@...hat.com>

Looks ok, but save/restore hints are about to go away. See 
https://lore.kernel.org/lkml/20200331222703.GH2452@worktop.programming.kicks-ass.net/

Miroslav