Re: [PATCH] uaccess: add noop untagged_addr definition

["Koenig, Christian" <Christian.Koenig@amd.com>]

Am 04.06.19 um 13:44 schrieb Andrey Konovalov:
> Architectures that support memory tagging have a need to perform untagging
> (stripping the tag) in various parts of the kernel. This patch adds an
> untagged_addr() macro, which is defined as noop for architectures that do
> not support memory tagging. The oncoming patch series will define it at
> least for sparc64 and arm64.
>
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
>   include/linux/mm.h | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0e8834ac32b7..949d43e9c0b6 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -99,6 +99,10 @@ extern int mmap_rnd_compat_bits __read_mostly;
>   #include <asm/pgtable.h>
>   #include <asm/processor.h>
>   
> +#ifndef untagged_addr
> +#define untagged_addr(addr) (addr)
> +#endif
> +

Maybe add a comment what tagging actually is? Cause that is not really 
obvious from the context.

Christian.

>   #ifndef __pa_symbol
>   #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
>   #endif