linux-kernel - Re: [RFC v5 04/57] objtool: check: Ignore empty alternative groups

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Message-ID: <20200121163011.tk5koyg24gzuhoaa@treble>
Date:   Tue, 21 Jan 2020 10:30:11 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Julien Thierry <jthierry@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        peterz@...radead.org, raphael.gault@....com,
        catalin.marinas@....com, will@...nel.org
Subject: Re: [RFC v5 04/57] objtool: check: Ignore empty alternative groups

On Thu, Jan 09, 2020 at 04:02:07PM +0000, Julien Thierry wrote:
> Atlernative section can contain entries for alternatives with no
> instructions. Objtool will currently crash when handling such an entry.
> 
> Just skip that entry, but still give a warning to discourage useless
> entries.
> 
> Signed-off-by: Julien Thierry <jthierry@...hat.com>
> ---
>  tools/objtool/check.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index 5968e6f08891..27e5380e0e0b 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -866,6 +866,13 @@ static int add_special_section_alts(struct objtool_file *file)
>  		}
>  
>  		if (special_alt->group) {
> +			if (!special_alt->orig_len) {
> +				WARN("empty alternative entry at %s+0x%lx",
> +				     orig_insn->sec->name,
> +				     orig_insn->offset);
> +				continue;
> +			}
> +

I think WARN_FUNC() can be used here instead.

-- 
Josh