Re: [PATCH] x86, kasan: Fix build failure on KASAN=y && KMEMCHECK=y kernels

[Borislav Petkov <bp@alien8.de>]

On Fri, Oct 16, 2015 at 02:28:53PM +0300, Andrey Ryabinin wrote:
> Declaration of memcpy is hidden under #ifndef CONFIG_KMEMCHECK.
> In asm/efi.h we under #ifdef CONFIG_KASAN we #undef memcpy
> thus following happens:
> 
> In file included from arch/x86/kernel/setup.c:96:0:
> ./arch/x86/include/asm/desc.h: In function ‘native_write_idt_entry’:
> ./arch/x86/include/asm/desc.h:122:2: error: implicit declaration of function ‘memcpy’ [-Werror=implicit-function-declaration]
>   memcpy(&idt[entry], gate, sizeof(*gate));
>   ^
>   cc1: some warnings being treated as errors
>   make[2]: *** [arch/x86/kernel/setup.o] Error 1
> 
> We will get rid of that #undef in asm/efi.h eventually.
> But in the meanwhile move memcpy() declaration out ifdefs
> to fix build.
> 

Looks ok to me. I guess this should go together with the efi.h fix.

> Reported-by: Borislav Petkov <bp@alien8.de>

	...-and-tested-by: me

> Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
> ---
>  arch/x86/include/asm/string_64.h | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
> index e466119..ff8b9a1 100644
> --- a/arch/x86/include/asm/string_64.h
> +++ b/arch/x86/include/asm/string_64.h
> @@ -27,12 +27,11 @@ static __always_inline void *__inline_memcpy(void *to, const void *from, size_t
>     function. */
>  
>  #define __HAVE_ARCH_MEMCPY 1
> +extern void *memcpy(void *to, const void *from, size_t len);
>  extern void *__memcpy(void *to, const void *from, size_t len);
>  
>  #ifndef CONFIG_KMEMCHECK
> -#if (__GNUC__ == 4 && __GNUC_MINOR__ >= 3) || __GNUC__ > 4
> -extern void *memcpy(void *to, const void *from, size_t len);
> -#else
> +#if (__GNUC__ == 4 && __GNUC_MINOR__ < 3) || __GNUC__ < 4
>  #define memcpy(dst, src, len)					\
>  ({								\
>  	size_t __len = (len);					\
> -- 
> 2.4.9

Thanks.

-- 
Regards/Gruss,
    Boris.

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