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Date:   Thu, 13 Apr 2023 16:19:10 +0200 (CEST)
From:   Miroslav Benes <mbenes@suse.cz>
To:     Josh Poimboeuf <jpoimboe@kernel.org>
cc:     x86@kernel.org, linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v2 8/9] objtool: Detect missing __noreturn annotations
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References: <cover.1681325924.git.jpoimboe@kernel.org> <0f630a0eb4585ab4114e4eecaa6f166a1fd81d49.1681325924.git.jpoimboe@kernel.org>
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> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -4485,7 +4485,8 @@ static int validate_sls(struct objtool_file *file)
>  
>  static int validate_reachable_instructions(struct objtool_file *file)
>  {
> -	struct instruction *insn;
> +	struct instruction *insn, *prev_insn;
> +	struct symbol *call_dest;
>  	int warnings = 0;
>  
>  	if (file->ignore_unreachables)
> @@ -4495,6 +4496,17 @@ static int validate_reachable_instructions(struct objtool_file *file)
>  		if (insn->visited || ignore_unreachable_insn(file, insn))
>  			continue;
>  
> +		prev_insn = prev_insn_same_sec(file, insn);
> +		if (prev_insn && prev_insn->dead_end) {
> +			call_dest = insn_call_dest(prev_insn);
> +			if (call_dest) {
> +				WARN_INSN(insn, "%s() is missing a __noreturn annotation",
> +					  call_dest->name);
> +				warnings++;
> +				continue;

A nit but this and

> +			}
> +		}
> +
>  		WARN_INSN(insn, "unreachable instruction");
>  		warnings++;

this makes me thinking. Wouldn't it be confusing to anyone that there is 
no correspondence between warnings and a number of actual reported 
warnings through WARN_INSN()? In the future when there would be a usage 
for warnings. It does not really matter now.

Miroslav