Re: [PATCH v3 5/5] module: Provide EXPORT_SYMBOL_GPL_FOR_MODULES() helper

[Petr Pavlu <petr.pavlu@suse.com>]

On 5/2/25 16:12, Peter Zijlstra wrote:
> Helper macro to more easily limit the export of a symbol to a given
> list of modules.
> 
> Eg:
> 
>   EXPORT_SYMBOL_GPL_FOR_MODULES(preempt_notifier_inc, "kvm");
> 
> will limit the use of said function to kvm.ko, any other module trying
> to use this symbol will refure to load (and get modpost build
> failures).
> 
> Requested-by: Masahiro Yamada <masahiroy@kernel.org>
> Requested-by: Christoph Hellwig <hch@infradead.org>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> [...]
> --- a/include/linux/export.h
> +++ b/include/linux/export.h
> @@ -24,11 +24,17 @@
>  	.long sym
>  #endif
>  
> -#define ___EXPORT_SYMBOL(sym, license, ns)		\
> +/*
> + * LLVM integrated assembler cam merge adjacent string literals (like
> + * C and GNU-as) passed to '.ascii', but not to '.asciz' and chokes on:
> + *
> + *   .asciz "MODULE_" "kvm" ;
> + */

Typo: "cam" -> "can't". I can correct it when picking up the series.

Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>

-- Petr

> +#define ___EXPORT_SYMBOL(sym, license, ns...)		\
>  	.section ".export_symbol","a"		ASM_NL	\
>  	__export_symbol_##sym:			ASM_NL	\
>  		.asciz license			ASM_NL	\
> -		.asciz ns			ASM_NL	\
> +		.ascii ns "\0"			ASM_NL	\
>  		__EXPORT_SYMBOL_REF(sym)	ASM_NL	\
>  	.previous
>  
> @@ -85,4 +91,6 @@
>  #define EXPORT_SYMBOL_NS(sym, ns)	__EXPORT_SYMBOL(sym, "", ns)
>  #define EXPORT_SYMBOL_NS_GPL(sym, ns)	__EXPORT_SYMBOL(sym, "GPL", ns)
>  
> +#define EXPORT_SYMBOL_GPL_FOR_MODULES(sym, mods) __EXPORT_SYMBOL(sym, "GPL", "module:" mods)
> +
>  #endif /* _LINUX_EXPORT_H */
> 
>