On Fri, Nov 29, 2024 at 05:16:42PM +0100, Ard Biesheuvel wrote: > On Mon, 25 Nov 2024 at 05:12, Eric Biggers <ebiggers@xxxxxxxxxx> wrote: > > > > This patchset is also available in git via: > > > > git fetch https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git crc-x86-v1 > > > > This patchset applies on top of my other recent CRC patchsets > > https://lore.kernel.org/r/20241103223154.136127-1-ebiggers@xxxxxxxxxx/ and > > https://lore.kernel.org/r/20241117002244.105200-1-ebiggers@xxxxxxxxxx/ . > > Consider it a preview for what may be coming next, as my priority is > > getting those two other patchsets merged first. > > > > This patchset adds a new assembly macro that expands into the body of a > > CRC function for x86 for the specified number of bits, bit order, vector > > length, and AVX level. There's also a new script that generates the > > constants needed by this function, given a CRC generator polynomial. > > > > This approach allows easily wiring up an x86-optimized implementation of > > any variant of CRC-8, CRC-16, CRC-32, or CRC-64, including full support > > for VPCLMULQDQ. On long messages the resulting functions are up to 4x > > faster than the existing PCLMULQDQ optimized functions when they exist, > > or up to 29x faster than the existing table-based functions. > > > > This patchset starts by wiring up the new macro for crc32_le, > > crc_t10dif, and crc32_be. Later I'd also like to wire up crc64_be and > > crc64_rocksoft, once the design of the library functions for those has > > been fixed to be like what I'm doing for crc32* and crc_t10dif. > > > > A similar approach of sharing code between CRC variants, and vector > > lengths when applicable, should work for other architectures. The CRC > > constant generation script should be mostly reusable. > > > > Eric Biggers (6): > > x86: move zmm exclusion list into CPU feature flag > > scripts/crc: add gen-crc-consts.py > > x86/crc: add "template" for [V]PCLMULQDQ based CRC functions > > x86/crc32: implement crc32_le using new template > > x86/crc-t10dif: implement crc_t10dif using new template > > x86/crc32: implement crc32_be using new template > > > > Good stuff! > > Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > > Would indeed be nice to get CRC-64 implemented this way as well, so we > can use it on both x86 and arm64. Thanks! The template actually supports CRC-64 already (both LSB and MSB-first variants) and I've tested it in userspace. I just haven't wired it up to the kernel's CRC-64 functions yet. - Eric
