[PATCH v2 00/18] Wire up CRC32 library functions to arch-optimized code

Eric Biggers
2024-10-25T19:15:43Z

This patchset is also available in git via:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux.git crc32-lib-v2

CRC32 is a family of common non-cryptographic integrity check algorithms
that are fairly fast with a portable C implementation and become far
faster still with the CRC32 or carryless multiplication instructions
that most CPUs have. 9 architectures already have optimized code for at
least some CRC32 variants; however, except for arm64 this optimized code
was only accessible through the crypto API, not the library functions.

This patchset fixes that so that the CRC32 library functions use the
optimized code. This allows users to just use the library instead of
the crypto API. This is much simpler and also improves performance due
to eliminating the crypto API overhead including an indirect call. Some
examples of updating users are included at the end of the patchset.

Note: crc32c() was a weird case. It was a library function layered on
top of the crypto API, which in turn is layered on top of the real
library functions. So while it was easy to use, it was still subject to
the crypto API overhead. This patchset provides CRC32C acceleration in
the real library functions directly.

The updated CRC32 library design is:

- Each arch's CRC32 code (all variants) is in arch/$ARCH/lib/crc32*.
This adopts what arm64 and riscv already did. Note, the crypto
directory is not used because CRC32 is not a cryptographic algorithm.

- Weak symbols are no longer used. Instead there are crc32*_base() and
crc32*_arch(), and the appropriate ones are called based on the
kconfig. This is similar to how the ChaCha20 library code works.

- Each arch's CRC32 code is enabled by default when CRC32 is enabled,
but it can now be disabled, controlled by the choice that previously
controlled the base implementation only. It can also now be built as
a module if CRC32 is a module too, in which case it will be
automatically loaded via direct symbol dependency when appropriate.

- Instead of lots of pointless glue code that wires up each CRC32
variant to the crypto API for each architecture, we now just rely on
the existing shash algorithms that use the library functions.

- As before, the library functions don't provide access to off-CPU
crypto accelerators. But these appear to have very little, if any,
real-world relevance for CRC32 which is very fast on CPUs.

Future work should apply a similar cleanup to crct10dif which is a
variant of CRC16.

I tested all arches in QEMU using CONFIG_CRC32_SELFTEST and the crypto
self-tests, except for mips which I couldn't figure out how to do.

This patchset has the following dependencies on recent patches, which
hopefully will be merged soon through the appropriate trees:

- "crypto - move crypto_simd_disabled_for_test to lib"
(https://lore.kernel.org/linux-crypto/20241018235343.425758-1-ebiggers@kernel.org/)
- "crypto: x86/crc32c - jump table elimination and other cleanups"
(https://lore.kernel.org/linux-crypto/20241014042447.50197-1-ebiggers@kernel.org/)
- "arm64: Speed up CRC-32 using PMULL instructions"
(https://lore.kernel.org/linux-crypto/20241018075347.2821102-5-ardb+git@google.com/)
- "crypto: Enable fuzz testing for arch code"
(https://lore.kernel.org/linux-crypto/20241016185722.400643-4-ardb+git@google.com/)
- "crypto: mips/crc32 - fix the CRC32C implementation"
(https://lore.kernel.org/linux-crypto/20241020180258.8060-1-ebiggers@kernel.org/)
- "bcachefs: Explicitly select CRYPTO from BCACHEFS_FS"
(https://lore.kernel.org/linux-bcachefs/20241023183521.3752681-1-ebiggers@kernel.org/)

Everything can be retrieved from git using the command given earlier.

Since this patchset touches many areas, getting it merged may be
difficult. One option is a pull request with the whole patchset
directly to Linus. Another is to have at least patches 1-4 taken
through the crypto tree in v6.13; then the arch patches can land
separately afterwards, followed by the rest.

Changed in v2:
- Added a way to determine if the arch-optimized code is actually
being used at runtime, and used this to register the appropriate
shash algorithms with crypto API.
- Added a patch that converts iSCSI to use the library.
- Listed a bcachefs patch as a dependency.
- Added Ard's Reviewed-by.

Eric Biggers (18):
lib/crc32: drop leading underscores from __crc32c_le_base
lib/crc32: improve support for arch-specific overrides
lib/crc32: expose whether the lib is really optimized at runtime
crypto: crc32 - don't unnecessarily register arch algorithms
arm/crc32: expose CRC32 functions through lib
loongarch/crc32: expose CRC32 functions through lib
mips/crc32: expose CRC32 functions through lib
powerpc/crc32: expose CRC32 functions through lib
s390/crc32: expose CRC32 functions through lib
sparc/crc32: expose CRC32 functions through lib
x86/crc32: update prototype for crc_pcl()
x86/crc32: update prototype for crc32_pclmul_le_16()
x86/crc32: expose CRC32 functions through lib
lib/crc32: make crc32c() go directly to lib
ext4: switch to using the crc32c library
jbd2: switch to using the crc32c library
f2fs: switch to using the crc32 library
scsi: target: iscsi: switch to using the crc32c library

arch/arm/Kconfig | 1 +
arch/arm/configs/milbeaut_m10v_defconfig | 1 -
arch/arm/configs/multi_v7_defconfig | 1 -
arch/arm/crypto/Kconfig | 14 -
arch/arm/crypto/Makefile | 2 -
arch/arm/crypto/crc32-ce-glue.c | 247 ------------
arch/arm/lib/Makefile | 3 +
.../crc32-ce-core.S => lib/crc32-core.S} | 0
arch/arm/lib/crc32-glue.c | 118 ++++++
arch/arm64/Kconfig | 1 +
arch/arm64/lib/Makefile | 3 +-
arch/arm64/lib/crc32-glue.c | 30 +-
arch/loongarch/Kconfig | 1 +
arch/loongarch/configs/loongson3_defconfig | 1 -
arch/loongarch/crypto/Kconfig | 9 -
arch/loongarch/crypto/Makefile | 2 -
arch/loongarch/crypto/crc32-loongarch.c | 300 ---------------
arch/loongarch/lib/Makefile | 2 +
arch/loongarch/lib/crc32-loongarch.c | 130 +++++++
arch/mips/Kconfig | 5 +-
arch/mips/configs/eyeq5_defconfig | 1 -
arch/mips/configs/eyeq6_defconfig | 1 -
arch/mips/configs/generic/32r6.config | 2 -
arch/mips/configs/generic/64r6.config | 1 -
arch/mips/crypto/Kconfig | 9 -
arch/mips/crypto/Makefile | 2 -
arch/mips/crypto/crc32-mips.c | 354 ------------------
arch/mips/lib/Makefile | 2 +
arch/mips/lib/crc32-mips.c | 187 +++++++++
arch/powerpc/Kconfig | 1 +
arch/powerpc/configs/powernv_defconfig | 1 -
arch/powerpc/configs/ppc64_defconfig | 1 -
arch/powerpc/crypto/Kconfig | 15 +-
arch/powerpc/crypto/Makefile | 2 -
arch/powerpc/crypto/crc32c-vpmsum_glue.c | 173 ---------
arch/powerpc/crypto/crct10dif-vpmsum_asm.S | 2 +-
arch/powerpc/lib/Makefile | 3 +
arch/powerpc/lib/crc32-glue.c | 86 +++++
.../{crypto => lib}/crc32-vpmsum_core.S | 0
.../{crypto => lib}/crc32c-vpmsum_asm.S | 0
arch/riscv/Kconfig | 1 +
arch/riscv/lib/Makefile | 3 +-
arch/riscv/lib/{crc32.c => crc32-riscv.c} | 30 +-
arch/s390/Kconfig | 1 +
arch/s390/configs/debug_defconfig | 1 -
arch/s390/configs/defconfig | 1 -
arch/s390/crypto/Kconfig | 12 -
arch/s390/crypto/Makefile | 2 -
arch/s390/crypto/crc32-vx.c | 306 ---------------
arch/s390/lib/Makefile | 3 +
arch/s390/lib/crc32-glue.c | 86 +++++
arch/s390/{crypto => lib}/crc32-vx.h | 0
arch/s390/{crypto => lib}/crc32be-vx.c | 0
arch/s390/{crypto => lib}/crc32le-vx.c | 0
arch/sparc/Kconfig | 1 +
arch/sparc/crypto/Kconfig | 10 -
arch/sparc/crypto/Makefile | 4 -
arch/sparc/crypto/crc32c_glue.c | 184 ---------
arch/sparc/lib/Makefile | 2 +
arch/sparc/lib/crc32_glue.c | 86 +++++
arch/sparc/{crypto => lib}/crc32c_asm.S | 2 +-
arch/x86/Kconfig | 1 +
arch/x86/crypto/Kconfig | 22 --
arch/x86/crypto/Makefile | 7 -
arch/x86/crypto/crc32-pclmul_glue.c | 202 ----------
arch/x86/crypto/crc32c-intel_glue.c | 250 -------------
arch/x86/lib/Makefile | 4 +
arch/x86/lib/crc32-glue.c | 116 ++++++
.../crc32-pclmul_asm.S => lib/crc32-pclmul.S} | 19 +-
.../crc32c-3way.S} | 63 ++--
crypto/crc32_generic.c | 8 +-
crypto/crc32c_generic.c | 12 +-
drivers/target/iscsi/Kconfig | 3 +-
drivers/target/iscsi/iscsi_target.c | 153 +++-----
drivers/target/iscsi/iscsi_target_login.c | 50 ---
drivers/target/iscsi/iscsi_target_login.h | 1 -
drivers/target/iscsi/iscsi_target_nego.c | 21 +-
fs/ext4/Kconfig | 3 +-
fs/ext4/ext4.h | 25 +-
fs/ext4/super.c | 15 -
fs/f2fs/Kconfig | 3 +-
fs/f2fs/f2fs.h | 19 +-
fs/f2fs/super.c | 15 -
fs/jbd2/Kconfig | 2 -
fs/jbd2/journal.c | 25 +-
include/linux/crc32.h | 50 ++-
include/linux/crc32c.h | 7 +-
include/linux/jbd2.h | 31 +-
include/target/iscsi/iscsi_target_core.h | 3 -
lib/Kconfig | 80 ++--
lib/Makefile | 1 -
lib/crc32.c | 29 +-
lib/crc32test.c | 2 +-
lib/libcrc32c.c | 74 ----
94 files changed, 1128 insertions(+), 2637 deletions(-)
delete mode 100644 arch/arm/crypto/crc32-ce-glue.c
rename arch/arm/{crypto/crc32-ce-core.S => lib/crc32-core.S} (100%)
create mode 100644 arch/arm/lib/crc32-glue.c
delete mode 100644 arch/loongarch/crypto/crc32-loongarch.c
create mode 100644 arch/loongarch/lib/crc32-loongarch.c
delete mode 100644 arch/mips/crypto/crc32-mips.c
create mode 100644 arch/mips/lib/crc32-mips.c
delete mode 100644 arch/powerpc/crypto/crc32c-vpmsum_glue.c
create mode 100644 arch/powerpc/lib/crc32-glue.c
rename arch/powerpc/{crypto => lib}/crc32-vpmsum_core.S (100%)
rename arch/powerpc/{crypto => lib}/crc32c-vpmsum_asm.S (100%)
rename arch/riscv/lib/{crc32.c => crc32-riscv.c} (90%)
delete mode 100644 arch/s390/crypto/crc32-vx.c
create mode 100644 arch/s390/lib/crc32-glue.c
rename arch/s390/{crypto => lib}/crc32-vx.h (100%)
rename arch/s390/{crypto => lib}/crc32be-vx.c (100%)
rename arch/s390/{crypto => lib}/crc32le-vx.c (100%)
delete mode 100644 arch/sparc/crypto/crc32c_glue.c
create mode 100644 arch/sparc/lib/crc32_glue.c
rename arch/sparc/{crypto => lib}/crc32c_asm.S (92%)
delete mode 100644 arch/x86/crypto/crc32-pclmul_glue.c
delete mode 100644 arch/x86/crypto/crc32c-intel_glue.c
create mode 100644 arch/x86/lib/crc32-glue.c
rename arch/x86/{crypto/crc32-pclmul_asm.S => lib/crc32-pclmul.S} (95%)
rename arch/x86/{crypto/crc32c-pcl-intel-asm_64.S => lib/crc32c-3way.S} (92%)
delete mode 100644 lib/libcrc32c.c

--
2.47.0