On Thu, 30 Jan 2025 at 04:54, Eric Biggers <ebiggers@xxxxxxxxxx> wrote: > > From: Eric Biggers <ebiggers@xxxxxxxxxx> > > This CRC64 variant comes from the NVME NVM Command Set Specification > (https://nvmexpress.org/wp-content/uploads/NVM-Express-NVM-Command-Set-Specification-1.0e-2024.07.29-Ratified.pdf). > > The "Rocksoft Model CRC Algorithm", published in 1993 and available at > https://www.zlib.net/crc_v3.txt, is a generalized CRC algorithm that can > calculate any variant of CRC, given a list of parameters such as > polynomial, bit order, etc. It is not a CRC variant. > > The NVME NVM Command Set Specification has a table that gives the > "Rocksoft Model Parameters" for the CRC variant it uses. When support > for this CRC variant was added to Linux, this table seems to have been > misinterpreted as naming the CRC variant the "Rocksoft" CRC. In fact, > the CRC variant is not explicitly named by the NVME spec. > > Most implementations of this CRC variant outside Linux have been calling > it CRC64-NVME. Therefore, update Linux to match. > > While at it, remove the superfluous "update" from the function name, so > crc64_rocksoft_update() is now just crc64_nvme(), matching most of the > other CRC library functions. > > Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> > --- > block/t10-pi.c | 2 +- > include/linux/crc64.h | 11 +++++++---- > lib/crc64.c | 10 +++++----- > lib/gen_crc64table.c | 10 +++++----- > 4 files changed, 18 insertions(+), 15 deletions(-) > Reviewed-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > diff --git a/block/t10-pi.c b/block/t10-pi.c > index 2d05421f0fa5..2577114ff20c 100644 > --- a/block/t10-pi.c > +++ b/block/t10-pi.c > @@ -208,11 +208,11 @@ static void t10_pi_type1_complete(struct request *rq, unsigned int nr_bytes) > } > } > > static __be64 ext_pi_crc64(u64 crc, void *data, unsigned int len) > { > - return cpu_to_be64(crc64_rocksoft_update(crc, data, len)); > + return cpu_to_be64(crc64_nvme(crc, data, len)); > } > > static void ext_pi_crc64_generate(struct blk_integrity_iter *iter, > struct blk_integrity *bi) > { > diff --git a/include/linux/crc64.h b/include/linux/crc64.h > index 7880aeab69d6..17cf5af3e78e 100644 > --- a/include/linux/crc64.h > +++ b/include/linux/crc64.h > @@ -6,20 +6,23 @@ > #define _LINUX_CRC64_H > > #include <linux/types.h> > > u64 __pure crc64_be(u64 crc, const void *p, size_t len); > -u64 __pure crc64_rocksoft_generic(u64 crc, const void *p, size_t len); > +u64 __pure crc64_nvme_generic(u64 crc, const void *p, size_t len); > > /** > - * crc64_rocksoft_update - Calculate bitwise Rocksoft CRC64 > + * crc64_nvme - Calculate CRC64-NVME > * @crc: seed value for computation. 0 for a new CRC calculation, or the > * previous crc64 value if computing incrementally. > * @p: pointer to buffer over which CRC64 is run > * @len: length of buffer @p > + * > + * This computes the CRC64 defined in the NVME NVM Command Set Specification, > + * *including the bitwise inversion at the beginning and end*. > */ > -static inline u64 crc64_rocksoft_update(u64 crc, const u8 *p, size_t len) > +static inline u64 crc64_nvme(u64 crc, const u8 *p, size_t len) > { > - return crc64_rocksoft_generic(crc, p, len); > + return crc64_nvme_generic(crc, p, len); > } > > #endif /* _LINUX_CRC64_H */ > diff --git a/lib/crc64.c b/lib/crc64.c > index b5136fb4c199..d6f3f245eede 100644 > --- a/lib/crc64.c > +++ b/lib/crc64.c > @@ -20,12 +20,12 @@ > * x^64 + x^62 + x^57 + x^55 + x^54 + x^53 + x^52 + x^47 + x^46 + x^45 + > * x^40 + x^39 + x^38 + x^37 + x^35 + x^33 + x^32 + x^31 + x^29 + x^27 + > * x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 + > * x^7 + x^4 + x + 1 > * > - * crc64rocksoft[256] table is from the Rocksoft specification polynomial > - * defined as, > + * crc64nvmetable[256] uses the CRC64 polynomial from the NVME NVM Command Set > + * Specification and uses least-significant-bit first bit order: > * > * x^64 + x^63 + x^61 + x^59 + x^58 + x^56 + x^55 + x^52 + x^49 + x^48 + x^47 + > * x^46 + x^44 + x^41 + x^37 + x^36 + x^34 + x^32 + x^31 + x^28 + x^26 + x^23 + > * x^22 + x^19 + x^16 + x^13 + x^12 + x^10 + x^9 + x^6 + x^4 + x^3 + 1 > * > @@ -61,18 +61,18 @@ u64 __pure crc64_be(u64 crc, const void *p, size_t len) > > return crc; > } > EXPORT_SYMBOL_GPL(crc64_be); > > -u64 __pure crc64_rocksoft_generic(u64 crc, const void *p, size_t len) > +u64 __pure crc64_nvme_generic(u64 crc, const void *p, size_t len) > { > const unsigned char *_p = p; > size_t i; > > crc = ~crc; > > for (i = 0; i < len; i++) > - crc = (crc >> 8) ^ crc64rocksofttable[(crc & 0xff) ^ *_p++]; > + crc = (crc >> 8) ^ crc64nvmetable[(crc & 0xff) ^ *_p++]; > > return ~crc; > } > -EXPORT_SYMBOL_GPL(crc64_rocksoft_generic); > +EXPORT_SYMBOL_GPL(crc64_nvme_generic); > diff --git a/lib/gen_crc64table.c b/lib/gen_crc64table.c > index 55e222acd0b8..e05a4230a0a0 100644 > --- a/lib/gen_crc64table.c > +++ b/lib/gen_crc64table.c > @@ -15,14 +15,14 @@ > */ > #include <inttypes.h> > #include <stdio.h> > > #define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL > -#define CRC64_ROCKSOFT_POLY 0x9A6C9329AC4BC9B5ULL > +#define CRC64_NVME_POLY 0x9A6C9329AC4BC9B5ULL > > static uint64_t crc64_table[256] = {0}; > -static uint64_t crc64_rocksoft_table[256] = {0}; > +static uint64_t crc64_nvme_table[256] = {0}; > > static void generate_reflected_crc64_table(uint64_t table[256], uint64_t poly) > { > uint64_t i, j, c, crc; > > @@ -80,16 +80,16 @@ static void print_crc64_tables(void) > printf("#include <linux/types.h>\n"); > printf("#include <linux/cache.h>\n\n"); > printf("static const u64 ____cacheline_aligned crc64table[256] = {\n"); > output_table(crc64_table); > > - printf("\nstatic const u64 ____cacheline_aligned crc64rocksofttable[256] = {\n"); > - output_table(crc64_rocksoft_table); > + printf("\nstatic const u64 ____cacheline_aligned crc64nvmetable[256] = {\n"); > + output_table(crc64_nvme_table); > } > > int main(int argc, char *argv[]) > { > generate_crc64_table(crc64_table, CRC64_ECMA182_POLY); > - generate_reflected_crc64_table(crc64_rocksoft_table, CRC64_ROCKSOFT_POLY); > + generate_reflected_crc64_table(crc64_nvme_table, CRC64_NVME_POLY); > print_crc64_tables(); > return 0; > } > -- > 2.48.1 >
