linux-kernel - Re: [RFC 05/31] x86/compiler: Tweak __UNIQUE

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Message-ID: <20240903075634.GL4723@noisy.programming.kicks-ass.net>
Date: Tue, 3 Sep 2024 09:56:34 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
	x86@...nel.org, Miroslav Benes <mbenes@...e.cz>,
	Petr Mladek <pmladek@...e.com>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	Jiri Kosina <jikos@...nel.org>,
	Marcos Paulo de Souza <mpdesouza@...e.com>,
	Song Liu <song@...nel.org>
Subject: Re: [RFC 05/31] x86/compiler: Tweak __UNIQUE_ID naming

On Mon, Sep 02, 2024 at 08:59:48PM -0700, Josh Poimboeuf wrote:
> Add an underscore between the "name" and the counter so tooling can
> distinguish between the non-unique and unique portions of the symbol
> name.
> 
> This will come in handy for "objtool klp diff".
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
> ---
>  include/linux/compiler.h | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/compiler.h b/include/linux/compiler.h
> index 8c252e073bd8..d3f100821d45 100644
> --- a/include/linux/compiler.h
> +++ b/include/linux/compiler.h
> @@ -186,7 +186,11 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
>  	__asm__ ("" : "=r" (var) : "0" (var))
>  #endif
>  
> -#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
> +/* Format: __UNIQUE_ID_<name>_<__COUNTER__> */
> +#define __UNIQUE_ID(name)					\
> +	__PASTE(__UNIQUE_ID_,					\
> +	__PASTE(name,						\
> +	__PASTE(_, __COUNTER__)))

OK, that's just painful to read; how about so?

	__PASTE(__UNIQUE_ID_,					\
	        __PASTE(name,					\
		        __PASTE(_, __COUNTER)))

>  
>  /**
>   * data_race - mark an expression as containing intentional data races
> @@ -218,7 +222,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
>   */
>  #define ___ADDRESSABLE(sym, __attrs) \
>  	static void * __used __attrs \
> -	__UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)(uintptr_t)&sym;
> +	__UNIQUE_ID(__PASTE(addressable_, sym)) = (void *)(uintptr_t)&sym;

This change doesn't get mention ?

>  #define __ADDRESSABLE(sym) \
>  	___ADDRESSABLE(sym, __section(".discard.addressable"))
>  
> -- 
> 2.45.2
>