Re: [PATCH 5/5] lib/crc: arm: Enable arm64's NEON intrinsics implementation of crc64

Ard Biesheuvel
2026-04-01T16:48:50Z

On Wed, 1 Apr 2026, at 00:41, Eric Biggers wrote:
> On Mon, Mar 30, 2026 at 04:46:36PM +0200, Ard Biesheuvel wrote:
>> Enable big-endian support only on GCC - the code generated by Clang is
>> horribly broken.
> [...]
>> +#if defined(CONFIG_ARM) && defined(CONFIG_CC_IS_CLANG)
>> +static inline uint64x2_t pmull64(uint64x2_t a, uint64x2_t b)
>> +{
>> + uint64_t l = vgetq_lane_u64(a, 0);
>> + uint64_t m = vgetq_lane_u64(b, 0);
>> + uint64x2_t result;
>> +
>> + asm("vmull.p64 %q0, %1, %2" : "=w"(result) : "w"(l), "w"(m));
>> +
>> + return result;
>> +}
>
> Perhaps omit big endian support, and use the inline asm implementation
> of these functions with both gcc and clang? The more unique
> combinations need to be tested to cover all the code, the higher the
> chance of one being missed in testing.
>

Yeah that should work.

> Also, leaving shared code in lib/crc/arm64/ will be confusing. How
> about lib/crc/arm-common/, and crc64_nvme_arm64_c => crc64_nvme_neon()?
> Or even just put crc64-neon.c directly in lib/crc/.
>

Yeah the latter seems the most straight-forward.