Re: [PATCH 2/2] lib/test_bits.c: Add tests for GENMASK_U128()

[Anshuman Khandual <anshuman.khandual@arm.com>]

On 7/24/24 16:15, Arnd Bergmann wrote:
> On Wed, Jul 24, 2024, at 12:31, Anshuman Khandual wrote:
>> This adds GENMASK_U128() tests although currently only 64 bit wide masks
>> are being tested.
>>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>>  lib/test_bits.c | 21 +++++++++++++++++++++
>>  1 file changed, 21 insertions(+)
>>
>> diff --git a/lib/test_bits.c b/lib/test_bits.c
>> index 01313980f175..2515ddc34409 100644
>> --- a/lib/test_bits.c
>> +++ b/lib/test_bits.c
>> @@ -39,6 +39,24 @@ static void genmask_ull_test(struct kunit *test)
>>  #endif
>>  }
>>
>> +static void genmask_u128_test(struct kunit *test)
>> +{
>> +	/* Tests mask generation only when the mask width is within 64 bits */
>> +	KUNIT_EXPECT_EQ(test, 0x0000000000ff0000ULL, GENMASK_U128(87, 80) >> 64);
>> +	KUNIT_EXPECT_EQ(test, 0x0000000000ffffffULL, GENMASK_U128(87, 64) >> 64);
>> +	KUNIT_EXPECT_EQ(test, 0x0000000000000001ULL, GENMASK_U128(0, 0));
> 
> This looks like it would need an #ifdef check for either
> __SIZEOF_INT128__ or CONFIG_ARCH_SUPPORTS_INT128, otherwise
> it will fail to build on all 32-bit architectures and possibly
> old compiler versions on some 64-bit ones. I think I checked
> in the past which targets support __u128, but I don't remember
> the result.

Sure, will go with CONFIG_ARCH_SUPPORTS_INT128 and add required #ifdefs here.