[PATCH 0/4] RISC-V CRC optimizations

Eric Biggers
2025-02-16T23:00:31Z

This patchset is a replacement for
"[PATCH v4] riscv: Optimize crct10dif with Zbc extension"
(https://lore.kernel.org/r/20250211071101.181652-1-zhihang.shao.iscas@gmail.com/).
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