Re: [PATCH -tip] x86/asm: Use %a instead of %c(%%rip) in rip_rel_ptr()

["H. Peter Anvin" <hpa@zytor.com>]

On 5/4/25 11:43, Uros Bizjak wrote:
> The "a" asm operand modifier substitutes a memory reference, with the
> actual operand treated as address.  For x86_64, when a symbol is
> provided, the "a" modifier emits "sym(%rip)" instead of "sym".
> 
> No functional changes intended.
> 
> Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Ard Biesheuvel <ardb@kernel.org>
> ---
>   arch/x86/include/asm/asm.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
> index f963848024a5..d7610b99b8d8 100644
> --- a/arch/x86/include/asm/asm.h
> +++ b/arch/x86/include/asm/asm.h
> @@ -116,7 +116,7 @@
>   #ifndef __ASSEMBLER__
>   static __always_inline __pure void *rip_rel_ptr(void *p)
>   {
> -	asm("leaq %c1(%%rip), %0" : "=r"(p) : "i"(p));
> +	asm("leaq %a1, %0" : "=r"(p) : "i"(p));
>   
>   	return p;
>   }

Also, this function really should be __attribute_const__ rather than __pure.

Acked-by: H. Peter Anvin (Intel) <hpa@zytor.com>