diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig | 70 | ||||
| -rw-r--r-- | lib/crc32.c | 22 |
2 files changed, 61 insertions, 31 deletions
diff --git a/lib/Kconfig b/lib/Kconfig index 5a318f753b2f..8858030bebae 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -190,6 +190,9 @@ config CRC32 the kernel tree does. Such modules that use library CRC32/CRC32c functions require M here. +config ARCH_HAS_CRC32 + bool + config CRC32_SELFTEST tristate "CRC32 perform self test on init" depends on CRC32 @@ -202,24 +205,39 @@ config CRC32_SELFTEST choice prompt "CRC32 implementation" depends on CRC32 - default CRC32_SLICEBY8 + default CRC32_IMPL_ARCH_PLUS_SLICEBY8 if ARCH_HAS_CRC32 + default CRC32_IMPL_SLICEBY8 if !ARCH_HAS_CRC32 help - This option allows a kernel builder to override the default choice - of CRC32 algorithm. Choose the default ("slice by 8") unless you - know that you need one of the others. + This option allows you to override the default choice of CRC32 + implementation. Choose the default unless you know that you need one + of the others. -config CRC32_SLICEBY8 +config CRC32_IMPL_ARCH_PLUS_SLICEBY8 + bool "Arch-optimized, with fallback to slice-by-8" if ARCH_HAS_CRC32 + help + Use architecture-optimized implementation of CRC32. Fall back to + slice-by-8 in cases where the arch-optimized implementation cannot be + used, e.g. if the CPU lacks support for the needed instructions. + + This is the default when an arch-optimized implementation exists. + +config CRC32_IMPL_ARCH_PLUS_SLICEBY1 + bool "Arch-optimized, with fallback to slice-by-1" if ARCH_HAS_CRC32 + help + Use architecture-optimized implementation of CRC32, but fall back to + slice-by-1 instead of slice-by-8 in order to reduce the binary size. + +config CRC32_IMPL_SLICEBY8 bool "Slice by 8 bytes" help Calculate checksum 8 bytes at a time with a clever slicing algorithm. - This is the fastest algorithm, but comes with a 8KiB lookup table. - Most modern processors have enough cache to hold this table without - thrashing the cache. - - This is the default implementation choice. Choose this one unless - you have a good reason not to. + This is much slower than the architecture-optimized implementation of + CRC32 (if the selected arch has one), but it is portable and is the + fastest implementation when no arch-optimized implementation is + available. It uses an 8KiB lookup table. Most modern processors have + enough cache to hold this table without thrashing the cache. -config CRC32_SLICEBY4 +config CRC32_IMPL_SLICEBY4 bool "Slice by 4 bytes" help Calculate checksum 4 bytes at a time with a clever slicing algorithm. @@ -228,15 +246,15 @@ config CRC32_SLICEBY4 Only choose this option if you know what you are doing. -config CRC32_SARWATE - bool "Sarwate's Algorithm (one byte at a time)" +config CRC32_IMPL_SLICEBY1 + bool "Slice by 1 byte (Sarwate's algorithm)" help Calculate checksum a byte at a time using Sarwate's algorithm. This - is not particularly fast, but has a small 256 byte lookup table. + is not particularly fast, but has a small 1KiB lookup table. Only choose this option if you know what you are doing. -config CRC32_BIT +config CRC32_IMPL_BIT bool "Classic Algorithm (one bit at a time)" help Calculate checksum one bit at a time. This is VERY slow, but has @@ -246,6 +264,26 @@ config CRC32_BIT endchoice +config CRC32_ARCH + tristate + default CRC32 if CRC32_IMPL_ARCH_PLUS_SLICEBY8 || CRC32_IMPL_ARCH_PLUS_SLICEBY1 + +config CRC32_SLICEBY8 + bool + default y if CRC32_IMPL_SLICEBY8 || CRC32_IMPL_ARCH_PLUS_SLICEBY8 + +config CRC32_SLICEBY4 + bool + default y if CRC32_IMPL_SLICEBY4 + +config CRC32_SARWATE + bool + default y if CRC32_IMPL_SLICEBY1 || CRC32_IMPL_ARCH_PLUS_SLICEBY1 + +config CRC32_BIT + bool + default y if CRC32_IMPL_BIT + config CRC64 tristate "CRC64 functions" help diff --git a/lib/crc32.c b/lib/crc32.c index c67059b0082b..47151624332e 100644 --- a/lib/crc32.c +++ b/lib/crc32.c @@ -183,35 +183,27 @@ static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p, } #if CRC_LE_BITS == 1 -u32 __pure __weak crc32_le(u32 crc, unsigned char const *p, size_t len) +u32 __pure crc32_le_base(u32 crc, const u8 *p, size_t len) { return crc32_le_generic(crc, p, len, NULL, CRC32_POLY_LE); } -u32 __pure __weak __crc32c_le(u32 crc, unsigned char const *p, size_t len) +u32 __pure crc32c_le_base(u32 crc, const u8 *p, size_t len) { return crc32_le_generic(crc, p, len, NULL, CRC32C_POLY_LE); } #else -u32 __pure __weak crc32_le(u32 crc, unsigned char const *p, size_t len) +u32 __pure crc32_le_base(u32 crc, const u8 *p, size_t len) { return crc32_le_generic(crc, p, len, crc32table_le, CRC32_POLY_LE); } -u32 __pure __weak __crc32c_le(u32 crc, unsigned char const *p, size_t len) +u32 __pure crc32c_le_base(u32 crc, const u8 *p, size_t len) { return crc32_le_generic(crc, p, len, crc32ctable_le, CRC32C_POLY_LE); } #endif -EXPORT_SYMBOL(crc32_le); -EXPORT_SYMBOL(__crc32c_le); - -u32 __pure crc32_le_base(u32, unsigned char const *, size_t) __alias(crc32_le); EXPORT_SYMBOL(crc32_le_base); - -u32 __pure crc32c_le_base(u32, unsigned char const *, size_t) __alias(__crc32c_le); EXPORT_SYMBOL(crc32c_le_base); -u32 __pure crc32_be_base(u32, unsigned char const *, size_t) __alias(crc32_be); - /* * This multiplies the polynomials x and y modulo the given modulus. * This follows the "little-endian" CRC convention that the lsbit @@ -335,14 +327,14 @@ static inline u32 __pure crc32_be_generic(u32 crc, unsigned char const *p, } #if CRC_BE_BITS == 1 -u32 __pure __weak crc32_be(u32 crc, unsigned char const *p, size_t len) +u32 __pure crc32_be_base(u32 crc, const u8 *p, size_t len) { return crc32_be_generic(crc, p, len, NULL, CRC32_POLY_BE); } #else -u32 __pure __weak crc32_be(u32 crc, unsigned char const *p, size_t len) +u32 __pure crc32_be_base(u32 crc, const u8 *p, size_t len) { return crc32_be_generic(crc, p, len, crc32table_be, CRC32_POLY_BE); } #endif -EXPORT_SYMBOL(crc32_be); +EXPORT_SYMBOL(crc32_be_base); |