Re: [PATCH 0/3] selftests: Remove duplicate CPUID wrappers

[Reinette Chatre]

Hi Shuah,

On 2/4/2022 3:39 PM, Shuah Khan wrote:
> On 2/4/22 12:17 PM, Reinette Chatre wrote:
>> A few tests that require running CPUID do so with a private
>> implementation of a wrapper for CPUID. This duplication of
>> the CPUID wrapper should be avoided but having one is also
>> unnecessary because of the existence of a macro that can
>> be used instead.
>>
>> This series replaces private CPUID wrappers with calls
>> to the __cpuid_count() macro from cpuid.h as made available
>> by gcc and clang/llvm.
>>
>> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
>> Cc: Ram Pai <linuxram@xxxxxxxxxx>
>> Cc: Sandipan Das <sandipan@xxxxxxxxxxxxx>
>> Cc: Florian Weimer <fweimer@xxxxxxxxxx>
>> Cc: "Desnes A. Nunes do Rosario" <desnesn@xxxxxxxxxxxxxxxxxx>
>> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
>> Cc: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx>
>> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
>> Cc: Michal Suchanek <msuchanek@xxxxxxx>
>> Cc: linux-mm@xxxxxxxxx
>> Cc: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
>> Cc: Borislav Petkov <bp@xxxxxxx>
>> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
>> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
>> Cc: x86@xxxxxxxxxx
>> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
>>
>> Reinette Chatre (3):
>>    selftests/vm/pkeys: Use existing __cpuid_count() macro
>>    selftests/x86/amx: Use existing __cpuid_count() macro
>>    selftests/x86/corrupt_xstate_header: Use existing __cpuid_count()
>>      macro
>>
>>   tools/testing/selftests/vm/pkey-x86.h         | 22 +++---------------
>>   tools/testing/selftests/x86/amx.c             | 23 +++++--------------
>>   .../selftests/x86/corrupt_xstate_header.c     | 17 ++------------
>>   3 files changed, 11 insertions(+), 51 deletions(-)
>>
> 
> I am all for this cleanup. However, I am not finding __cpuid_count()
> marco on my system with gcc:
> 
> gcc --version
> gcc (Ubuntu 11.2.0-7ubuntu2) 11.2.0
> 
> My concern is regression on older gcc versions.

Please see this message from our earlier thread where you were able
to find it on your system:
https://lore.kernel.org/linux-kselftest/63293c72-55ca-9446-35eb-74aff4c8ba5d@xxxxxxxxxxxxxxxxxxx/

As mentioned in that thread, on my system it arrived via user space's
libgcc-dev package. This does not seem to be the first time including
files from this source - I did a quick check and from what I can tell
existing kselftest includes like stdarg.h, stdbool.h, stdatomic.h,
unwind.h, x86intrin.h ... arrive via libgcc-dev.

Reinette