Re: [PATCH] uaccess: add noop untagged_addr definition

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

Am 04.06.19 um 13:48 schrieb Andrey Konovalov:
> On Tue, Jun 4, 2019 at 1:46 PM Koenig, Christian
> <Christian.Koenig@amd.com> wrote:
>> 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.
> Hi,
>
> Do you mean a comment in the code or an explanation in the patch description?

The code, the patch description actually sounds good to me.

Christian.

>
> Thanks!
>
>> Christian.
>>
>>>    #ifndef __pa_symbol
>>>    #define __pa_symbol(x)  __pa(RELOC_HIDE((unsigned long)(x), 0))
>>>    #endif