linux-kernel - Re: [PATCH 2/2] lib/test_bits.c: Add tests for GENMASK

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Message-ID: <f1c8ba93-f490-47ca-a2ea-74bb1e3c7ffd@arm.com>
Date: Wed, 24 Jul 2024 17:30:16 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 Yury Norov <yury.norov@...il.com>,
 Rasmus Villemoes <linux@...musvillemoes.dk>,
 Linux-Arch <linux-arch@...r.kernel.org>
Subject: Re: [PATCH 2/2] lib/test_bits.c: Add tests for GENMASK_U128()



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@...ux-foundation.org>
>> Cc: linux-kernel@...r.kernel.org
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@....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.