linux-kernel - Re: [PATCH 1/2] x86/efi: Optimize away setup

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Date:   Mon, 5 Sep 2016 13:37:25 +0100
From:   Matt Fleming <matt@...eblueprint.co.uk>
To:     Lukas Wunner <lukas@...ner.de>
Cc:     linux-efi@...r.kernel.org,
        Andreas Noever <andreas.noever@...il.com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH 1/2] x86/efi: Optimize away setup_gop32/64 if unused

On Mon, 22 Aug, at 12:01:21PM, Lukas Wunner wrote:
> Eliminate the 64 bit code path when compiling for x86_32, and vice-versa
> the 32 bit code path when compiling for x86_64 with mixed mode disabled.
> 
> Size of gop.o text section:
> CONFIG_X86_32:                         1758 before, 1299 after
> CONFIG_X86_64 && !CONFIG_EFI_MIXED:    2201 before, 1406 after
> CONFIG_X86_64 &&  CONFIG_EFI_MIXED:    2201 before and after
> 
> Signed-off-by: Lukas Wunner <lukas@...ner.de>
> Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> ---
>  arch/x86/include/asm/efi.h | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
> index 6b06939..1bda245 100644
> --- a/arch/x86/include/asm/efi.h
> +++ b/arch/x86/include/asm/efi.h
> @@ -207,14 +207,16 @@ struct efi_config {
>  
>  __pure const struct efi_config *__efi_early(void);
>  
> +#define efi_is_64bit()							\
> +	(IS_ENABLED(CONFIG_X86_64) && (!IS_ENABLED(CONFIG_EFI_MIXED)	\
> +				       || __efi_early()->is64))
> +
>  #define efi_call_early(f, ...)						\
>  	__efi_early()->call(__efi_early()->f, __VA_ARGS__);
>  
>  #define __efi_call_early(f, ...)					\
>  	__efi_early()->call((unsigned long)f, __VA_ARGS__);
>  
> -#define efi_is_64bit()		__efi_early()->is64
> -
>  extern bool efi_reboot_required(void);
>  
>  #else

Could you make this into a more readable static inline? e.g. something
like this,

static inline bool efi_is_64bit(void)
{
	if (!IS_ENABLED(CONFIG_X86_64))
		return false;

	if (!IS_ENABLED(CONFIG_EFI_MIXED) || __efi_early()->is64)
		return true;

	return false;
}