linux-kernel - Re: [PATCH 4/9] x86/alternative: Implement .retpoline

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Message-ID: <YW/SkCW9wSnFiivN@hirez.programming.kicks-ass.net>
Date:   Wed, 20 Oct 2021 10:25:52 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     x86@...nel.org, andrew.cooper3@...rix.com,
        linux-kernel@...r.kernel.org, alexei.starovoitov@...il.com,
        ndesaulniers@...gle.com
Subject: Re: [PATCH 4/9] x86/alternative: Implement .retpoline_sites support

On Tue, Oct 19, 2021 at 09:49:13AM -0700, Josh Poimboeuf wrote:

> @@ -1916,8 +1930,25 @@ static int read_static_call_tramps(struct objtool_file *file)
>  		list_for_each_entry(func, &sec->symbol_list, list) {
>  			if (func->bind == STB_GLOBAL &&
>  			    !strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
> -				     strlen(STATIC_CALL_TRAMP_PREFIX_STR)))
> +				     strlen(STATIC_CALL_TRAMP_PREFIX_STR))) {
>  				func->static_call_tramp = true;
> +			}
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int read_retpoline_thunks(struct objtool_file *file)
> +{
> +	struct section *sec;
> +	struct symbol *func;
> +
> +	for_each_sec(file, sec) {
> +		list_for_each_entry(func, &sec->symbol_list, list) {
> +			if (func->bind == STB_GLOBAL && arch_is_retpoline(func)) {
> +				func->retpoline = true;
> +			}
>  		}
>  	}

I've folded these two identical loops over all symbols into a single
classify_symbols() function.