Commit 067bc871 authored by Eric Biggers's avatar Eric Biggers
Browse files

lib/crc64: add support for arch-optimized implementations 



Add support for architecture-optimized implementations of the CRC64
library functions, following the approach taken for the CRC32 and
CRC-T10DIF library functions.

Also take the opportunity to tweak the function prototypes:
- Use 'const void *' for the lib entry points (since this is easier for
  users) but 'const u8 *' for the underlying arch and generic functions
  (since this is easier for the implementations of these functions).
- Don't bother with __pure.  It's an unusual optimization that doesn't
  help properly written code.  It's a weird quirk we can do without.

Reviewed-by: default avatarArd Biesheuvel <ardb@kernel.org>
Reviewed-by: default avatar"Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: default avatarKeith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20250130035130.180676-6-ebiggers@kernel.org


Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
parent 23709bd3

include/linux/crc64.h

+22 −4
Original line number Diff line number Diff line
@@ -7,8 +7,24 @@ 


#include <linux/types.h>



u64 __pure crc64_be(u64 crc, const void *p, size_t len);

u64 __pure crc64_nvme_generic(u64 crc, const void *p, size_t len);

u64 crc64_be_arch(u64 crc, const u8 *p, size_t len);

u64 crc64_be_generic(u64 crc, const u8 *p, size_t len);

u64 crc64_nvme_arch(u64 crc, const u8 *p, size_t len);

u64 crc64_nvme_generic(u64 crc, const u8 *p, size_t len);



/**

 * crc64_be - Calculate bitwise big-endian ECMA-182 CRC64

 * @crc: seed value for computation. 0 or (u64)~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

 */

static inline u64 crc64_be(u64 crc, const void *p, size_t len)

{

	if (IS_ENABLED(CONFIG_CRC64_ARCH))

		return crc64_be_arch(crc, p, len);

	return crc64_be_generic(crc, p, len);

}



/**

 * crc64_nvme - Calculate CRC64-NVME
@@ -20,9 +36,11 @@ u64 __pure crc64_nvme_generic(u64 crc, const void *p, size_t len); 
 * 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_nvme(u64 crc, const u8 *p, size_t len)

static inline u64 crc64_nvme(u64 crc, const void *p, size_t len)

{

	return crc64_nvme_generic(crc, p, len);

	if (IS_ENABLED(CONFIG_CRC64_ARCH))

		return ~crc64_nvme_arch(~crc, p, len);

	return ~crc64_nvme_generic(~crc, p, len);

}



#endif /* _LINUX_CRC64_H */

lib/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -201,6 +201,13 @@ config CRC64 
	  the kernel tree does. Such modules that use library CRC64

	  functions require M here.



config ARCH_HAS_CRC64

	bool



config CRC64_ARCH

	tristate

	default CRC64 if ARCH_HAS_CRC64 && CRC_OPTIMIZATIONS



config CRC4

	tristate "CRC4 functions"

	help

lib/crc64.c

+8 −28
Original line number Diff line number Diff line
@@ -41,38 +41,18 @@ 
MODULE_DESCRIPTION("CRC64 calculations");

MODULE_LICENSE("GPL v2");



/**

 * crc64_be - Calculate bitwise big-endian ECMA-182 CRC64

 * @crc: seed value for computation. 0 or (u64)~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_be(u64 crc, const void *p, size_t len)

u64 crc64_be_generic(u64 crc, const u8 *p, size_t len)

{

	size_t i, t;



	const unsigned char *_p = p;



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

		t = ((crc >> 56) ^ (*_p++)) & 0xFF;

		crc = crc64table[t] ^ (crc << 8);

	}



	while (len--)

		crc = (crc << 8) ^ crc64table[(crc >> 56) ^ *p++];

	return crc;

}

EXPORT_SYMBOL_GPL(crc64_be);

EXPORT_SYMBOL_GPL(crc64_be_generic);



u64 __pure crc64_nvme_generic(u64 crc, const void *p, size_t len)

u64 crc64_nvme_generic(u64 crc, const u8 *p, size_t len)

{

	const unsigned char *_p = p;

	size_t i;



	crc = ~crc;



	for (i = 0; i < len; i++)

		crc = (crc >> 8) ^ crc64nvmetable[(crc & 0xff) ^ *_p++];



	return ~crc;

	while (len--)

		crc = (crc >> 8) ^ crc64nvmetable[(crc & 0xff) ^ *p++];

	return crc;

}

EXPORT_SYMBOL_GPL(crc64_nvme_generic);