Commit cbc0a40e authored by Keith Busch's avatar Keith Busch Committed by Jens Axboe
Browse files

lib: add rocksoft model crc64 



The NVM Express specification extended data integrity fields to 64 bits
using the Rocksoft parameters. Add the poly to the crc64 table
generation, and provide a generic library routine implementing the
algorithm.

The Rocksoft 64-bit CRC model parameters are as follows:
    Poly: 0xAD93D23594C93659
    Initial value: 0xFFFFFFFFFFFFFFFF
    Reflected Input: True
    Reflected Output: True
    Xor Final: 0xFFFFFFFFFFFFFFFF

Since this model used reflected bits, the implementation generates the
reflected table so the result is ordered consistently.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
Reviewed-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20220303201312.3255347-6-kbusch@kernel.org


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 7ee8809d

include/linux/crc64.h

+2 −0
Original line number Diff line number Diff line
@@ -8,4 +8,6 @@ 
#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);



#endif /* _LINUX_CRC64_H */

lib/crc64.c

+28 −0
Original line number Diff line number Diff line
@@ -22,6 +22,13 @@ 
 * 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,

 *

 * 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

 *

 * Copyright 2018 SUSE Linux.

 *   Author: Coly Li <colyli@suse.de>

 */
@@ -55,3 +62,24 @@ u64 __pure crc64_be(u64 crc, const void *p, size_t len) 
	return crc;

}

EXPORT_SYMBOL_GPL(crc64_be);



/**

 * crc64_rocksoft_generic - Calculate bitwise Rocksoft CRC64

 * @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

 */

u64 __pure crc64_rocksoft_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++];



	return ~crc;

}

EXPORT_SYMBOL_GPL(crc64_rocksoft_generic);

lib/gen_crc64table.c

+40 −11
Original line number Diff line number Diff line
@@ -17,10 +17,30 @@ 
#include <stdio.h>



#define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL

#define CRC64_ROCKSOFT_POLY 0x9A6C9329AC4BC9B5ULL



static uint64_t crc64_table[256] = {0};

static uint64_t crc64_rocksoft_table[256] = {0};



static void generate_crc64_table(void)

static void generate_reflected_crc64_table(uint64_t table[256], uint64_t poly)

{

	uint64_t i, j, c, crc;



	for (i = 0; i < 256; i++) {

		crc = 0ULL;

		c = i;



		for (j = 0; j < 8; j++) {

			if ((crc ^ (c >> j)) & 1)

				crc = (crc >> 1) ^ poly;

			else

				crc >>= 1;

		}

		table[i] = crc;

	}

}



static void generate_crc64_table(uint64_t table[256], uint64_t poly)

{

	uint64_t i, j, c, crc;
@@ -30,26 +50,22 @@ static void generate_crc64_table(void) 


		for (j = 0; j < 8; j++) {

			if ((crc ^ c) & 0x8000000000000000ULL)

				crc = (crc << 1) ^ CRC64_ECMA182_POLY;

				crc = (crc << 1) ^ poly;

			else

				crc <<= 1;

			c <<= 1;

		}



		crc64_table[i] = crc;

		table[i] = crc;

	}

}



static void print_crc64_table(void)

static void output_table(uint64_t table[256])

{

	int i;



	printf("/* this file is generated - do not edit */\n\n");

	printf("#include <linux/types.h>\n");

	printf("#include <linux/cache.h>\n\n");

	printf("static const u64 ____cacheline_aligned crc64table[256] = {\n");

	for (i = 0; i < 256; i++) {

		printf("\t0x%016" PRIx64 "ULL", crc64_table[i]);

		printf("\t0x%016" PRIx64 "ULL", table[i]);

		if (i & 0x1)

			printf(",\n");

		else
@@ -58,9 +74,22 @@ static void print_crc64_table(void) 
	printf("};\n");

}



static void print_crc64_tables(void)

{

	printf("/* this file is generated - do not edit */\n\n");

	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);

}



int main(int argc, char *argv[])

{

	generate_crc64_table();

	print_crc64_table();

	generate_crc64_table(crc64_table, CRC64_ECMA182_POLY);

	generate_reflected_crc64_table(crc64_rocksoft_table, CRC64_ROCKSOFT_POLY);

	print_crc64_tables();

	return 0;

}