Re: [PATCH v2 1/5] arm64: kasan: allow to init memory when setting tags

[Catalin Marinas]

On Mon, Mar 08, 2021 at 04:55:14PM +0100, Andrey Konovalov wrote:
> @@ -68,10 +69,16 @@ static inline void mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
>  		 * 'asm volatile' is required to prevent the compiler to move
>  		 * the statement outside of the loop.
>  		 */
> -		asm volatile(__MTE_PREAMBLE "stg %0, [%0]"
> -			     :
> -			     : "r" (curr)
> -			     : "memory");
> +		if (init)
> +			asm volatile(__MTE_PREAMBLE "stzg %0, [%0]"
> +				     :
> +				     : "r" (curr)
> +				     : "memory");
> +		else
> +			asm volatile(__MTE_PREAMBLE "stg %0, [%0]"
> +				     :
> +				     : "r" (curr)
> +				     : "memory");
>  
>  		curr += MTE_GRANULE_SIZE;
>  	} while (curr != end);

Is 'init' always a built-in constant here? If not, checking it once
outside the loop may be better (or check the code generation, maybe the
compiler is smart enough).

-- 
Catalin