RISC-V CRC optimizations

This patchset is a replacement for
"[PATCH v4] riscv: Optimize crct10dif with Zbc extension"
(https://lore.kernel.org/r/[email protected]/).
It adopts the approach that I'm taking for x86 where code is shared among CRC variants. It replaces the existing Zbc optimized CRC32 functions, then adds Zbc optimized CRC-T10DIF and CRC64 functions.

This new code should be significantly faster than the current Zbc optimized CRC32 code and the previously proposed CRC-T10DIF code. It uses "folding" instead of just Barrett reduction, and it also implements Barrett reduction more efficiently.

This applies to crc-next at
https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git/log/?h=crc-next.
It depends on other patches that are queued there for 6.15, so I plan to take it through there if there are no objections.

Tested with crc_kunit in QEMU (set CONFIG_CRC_KUNIT_TEST=y and CONFIG_CRC_BENCHMARK=y), both 32-bit and 64-bit. I don't have real Zbc capable hardware to benchmark this on, but the new code should work very well; similar optimizations work very well on other architectures.

Eric Biggers (4):
riscv/crc: add "template" for Zbc optimized CRC functions riscv/crc32: reimplement the CRC32 functions using new template riscv/crc-t10dif: add Zbc optimized CRC-T10DIF function riscv/crc64: add Zbc optimized CRC64 functions

 arch/riscv/Kconfig                  |   2 +
 arch/riscv/lib/Makefile             |   5 +
 arch/riscv/lib/crc-clmul-consts.h   | 122 +++++++++++
 arch/riscv/lib/crc-clmul-template.h | 265 ++++++++++++++++++++++++
 arch/riscv/lib/crc-clmul.h          |  23 +++
 arch/riscv/lib/crc-t10dif.c         |  24 +++
 arch/riscv/lib/crc16_msb.c          |  18 ++
 arch/riscv/lib/crc32-riscv.c        | 310 ----------------------------
 arch/riscv/lib/crc32.c              |  53 +++++
 arch/riscv/lib/crc32_lsb.c          |  18 ++
 arch/riscv/lib/crc32_msb.c          |  18 ++
 arch/riscv/lib/crc64.c              |  34 +++
 arch/riscv/lib/crc64_lsb.c          |  18 ++
 arch/riscv/lib/crc64_msb.c          |  18 ++
 scripts/gen-crc-consts.py           |  55 ++++-
 15 files changed, 672 insertions(+), 311 deletions(-)
 create mode 100644 arch/riscv/lib/crc-clmul-consts.h
 create mode 100644 arch/riscv/lib/crc-clmul-template.h
 create mode 100644 arch/riscv/lib/crc-clmul.h
 create mode 100644 arch/riscv/lib/crc-t10dif.c
 create mode 100644 arch/riscv/lib/crc16_msb.c
 delete mode 100644 arch/riscv/lib/crc32-riscv.c
 create mode 100644 arch/riscv/lib/crc32.c
 create mode 100644 arch/riscv/lib/crc32_lsb.c
 create mode 100644 arch/riscv/lib/crc32_msb.c
 create mode 100644 arch/riscv/lib/crc64.c
 create mode 100644 arch/riscv/lib/crc64_lsb.c
 create mode 100644 arch/riscv/lib/crc64_msb.c

base-commit: cf1ea3a7c1f63cba7d1dd313ee3accde0c0c8988

2.48.1