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2024-12-01lib/crc32: expose whether the lib is really optimized at runtimeEric Biggers
Make the CRC32 library export a function crc32_optimizations() which returns flags that indicate which CRC32 functions are actually executing optimized code at runtime. This will be used to determine whether the crc32[c]-$arch shash algorithms should be registered in the crypto API. btrfs could also start using these flags instead of the hack that it currently uses where it parses the crypto_shash_driver_name. Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20241202010844.144356-4-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com>
2024-12-01lib/crc32: improve support for arch-specific overridesEric Biggers
Currently the CRC32 library functions are defined as weak symbols, and the arm64 and riscv architectures override them. This method of arch-specific overrides has the limitation that it only works when both the base and arch code is built-in. Also, it makes the arch-specific code be silently not used if it is accidentally built with lib-y instead of obj-y; unfortunately the RISC-V code does this. This commit reorganizes the code to have explicit *_arch() functions that are called when they are enabled, similar to how some of the crypto library code works (e.g. chacha_crypt() calls chacha_crypt_arch()). Make the existing kconfig choice for the CRC32 implementation also control whether the arch-optimized implementation (if one is available) is enabled or not. Make it enabled by default if CRC32 is also enabled. The result is that arch-optimized CRC32 library functions will be included automatically when appropriate, but it is now possible to disable them. They can also now be built as a loadable module if the CRC32 library functions happen to be used only by loadable modules, in which case the arch and base CRC32 modules will be automatically loaded via direct symbol dependency when appropriate. Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20241202010844.144356-3-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@google.com>