linux-kernel - Re: [PATCH 1/2] objtool: fix the check for dead_end function with multiple sibliing calls

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Message-ID: <20251103210153.GJ3245006@noisy.programming.kicks-ass.net>
Date: Mon, 3 Nov 2025 22:01:53 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: xur@...gle.com
Cc: Josh Poimboeuf <jpoimboe@...nel.org>, linux-kernel@...r.kernel.org,
	Sriraman Tallam <tmsriram@...gle.com>,
	Han Shen <shenhan@...gle.com>,
	Krzysztof Pszeniczny <kpszeniczny@...gle.com>
Subject: Re: [PATCH 1/2] objtool: fix the check for dead_end function with
 multiple sibliing calls

On Mon, Nov 03, 2025 at 06:51:53PM +0000, xur@...gle.com wrote:
> From: Rong Xu <xur@...gle.com>
> 
> If a function has multiple sibling calls, the dead_end check should
> only return true if all sibling call targets are also dead_end
> functions.

Cute, however did you find this?

> Signed-off-by: Rong Xu <xur@...gle.com>
> Reviewed-by: Sriraman Tallam <tmsriram@...gle.com>
> Reviewed-by: Han Shen <shenhan@...gle.com>
> Reviewed-by: Krzysztof Pszeniczny <kpszeniczny@...gle.com>
> ---
>  tools/objtool/check.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index 9004fbc067693..c2ee3c3a84a62 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -314,7 +314,13 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
>  				return false;
>  			}
>  
> -			return __dead_end_function(file, insn_func(dest), recursion+1);
> +			/*
> +			 * A function can have multiple sibling calls. All of
> +			 * them need to be dead ends for the function to be a
> +			 * dead end too.
> +			 */
> +			if (!__dead_end_function(file, insn_func(dest), recursion+1))
> +				return false;
>  		}
>  	}
>  
> 
> base-commit: 6146a0f1dfae5d37442a9ddcba012add260bceb0
> -- 
> 2.51.2.997.g839fc31de9-goog
>