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Commit cb8eb776 authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'crc32' 



Daniel Borkmann says:

====================
crc32 combine improvements

So almost a month passed, and I don't want this to get lost
somewhere. I have applied the feedback given at that time to
this set, rebased plus tested it against latest net-next. I
decided to route this via netdev as it improves performance
upon library code that provides library bits for SCTP, i.e.
for non-linear skb csum handling in IPVS. Thus, resending
this for George before it gets lost.
====================

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 5433ba36 d8f1c477

include/linux/crc32.h

+15 −5
Original line number Diff line number Diff line
@@ -8,8 +8,8 @@ 
#include <linux/types.h>

#include <linux/bitrev.h>



extern u32  crc32_le(u32 crc, unsigned char const *p, size_t len);

extern u32  crc32_be(u32 crc, unsigned char const *p, size_t len);

u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len);

u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len);



/**

 * crc32_le_combine - Combine two crc32 check values into one. For two
@@ -29,9 +29,14 @@ extern u32 crc32_be(u32 crc, unsigned char const *p, size_t len); 
 * 	   with the same initializer as crc1, and crc2 seed was 0. See

 * 	   also crc32_combine_test().

 */

extern u32  crc32_le_combine(u32 crc1, u32 crc2, size_t len2);

u32 __attribute_const__ crc32_le_shift(u32 crc, size_t len);



extern u32  __crc32c_le(u32 crc, unsigned char const *p, size_t len);

static inline u32 crc32_le_combine(u32 crc1, u32 crc2, size_t len2)

{

	return crc32_le_shift(crc1, len2) ^ crc2;

}



u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len);



/**

 * __crc32c_le_combine - Combine two crc32c check values into one. For two
@@ -51,7 +56,12 @@ extern u32 __crc32c_le(u32 crc, unsigned char const *p, size_t len); 
 * 	   seeded with the same initializer as crc1, and crc2 seed

 * 	   was 0. See also crc32c_combine_test().

 */

extern u32  __crc32c_le_combine(u32 crc1, u32 crc2, size_t len2);

u32 __attribute_const__ __crc32c_le_shift(u32 crc, size_t len);



static inline u32 __crc32c_le_combine(u32 crc1, u32 crc2, size_t len2)

{

	return __crc32c_le_shift(crc1, len2) ^ crc2;

}



#define crc32(seed, data, length)  crc32_le(seed, (unsigned char const *)(data), length)

lib/crc32.c

+73 −80
Original line number Diff line number Diff line
@@ -50,34 +50,10 @@ MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>"); 
MODULE_DESCRIPTION("Various CRC32 calculations");

MODULE_LICENSE("GPL");



#define GF2_DIM		32



static u32 gf2_matrix_times(u32 *mat, u32 vec)

{

	u32 sum = 0;



	while (vec) {

		if (vec & 1)

			sum ^= *mat;

		vec >>= 1;

		mat++;

	}



	return sum;

}



static void gf2_matrix_square(u32 *square, u32 *mat)

{

	int i;



	for (i = 0; i < GF2_DIM; i++)

		square[i] = gf2_matrix_times(mat, mat[i]);

}



#if CRC_LE_BITS > 8 || CRC_BE_BITS > 8



/* implements slicing-by-4 or slicing-by-8 algorithm */

static inline u32

static inline u32 __pure

crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])

{

# ifdef __LITTLE_ENDIAN
@@ -155,51 +131,6 @@ crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256]) 
}

#endif



/* For conditions of distribution and use, see copyright notice in zlib.h */

static u32 crc32_generic_combine(u32 crc1, u32 crc2, size_t len2,

				 u32 polynomial)

{

	u32 even[GF2_DIM]; /* Even-power-of-two zeros operator */

	u32 odd[GF2_DIM];  /* Odd-power-of-two zeros operator  */

	u32 row;

	int i;



	if (len2 <= 0)

		return crc1;



	/* Put operator for one zero bit in odd */

	odd[0] = polynomial;

	row = 1;

	for (i = 1; i < GF2_DIM; i++) {

		odd[i] = row;

		row <<= 1;

	}



	gf2_matrix_square(even, odd); /* Put operator for two zero bits in even */

	gf2_matrix_square(odd, even); /* Put operator for four zero bits in odd */



	/* Apply len2 zeros to crc1 (first square will put the operator for one

	 * zero byte, eight zero bits, in even).

	 */

	do {

		/* Apply zeros operator for this bit of len2 */

		gf2_matrix_square(even, odd);

		if (len2 & 1)

			crc1 = gf2_matrix_times(even, crc1);

		len2 >>= 1;

		/* If no more bits set, then done */

		if (len2 == 0)

			break;

		/* Another iteration of the loop with odd and even swapped */

		gf2_matrix_square(odd, even);

		if (len2 & 1)

			crc1 = gf2_matrix_times(odd, crc1);

		len2 >>= 1;

	} while (len2 != 0);



	crc1 ^= crc2;

	return crc1;

}



/**

 * crc32_le_generic() - Calculate bitwise little-endian Ethernet AUTODIN II
@@ -271,19 +202,81 @@ u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len) 
			(const u32 (*)[256])crc32ctable_le, CRC32C_POLY_LE);

}

#endif

u32 __pure crc32_le_combine(u32 crc1, u32 crc2, size_t len2)

EXPORT_SYMBOL(crc32_le);

EXPORT_SYMBOL(__crc32c_le);



/*

 * This multiplies the polynomials x and y modulo the given modulus.

 * This follows the "little-endian" CRC convention that the lsbit

 * represents the highest power of x, and the msbit represents x^0.

 */

static u32 __attribute_const__ gf2_multiply(u32 x, u32 y, u32 modulus)

{

	u32 product = x & 1 ? y : 0;

	int i;



	for (i = 0; i < 31; i++) {

		product = (product >> 1) ^ (product & 1 ? modulus : 0);

		x >>= 1;

		product ^= x & 1 ? y : 0;

	}



	return product;

}



/**

 * crc32_generic_shift - Append len 0 bytes to crc, in logarithmic time

 * @crc: The original little-endian CRC (i.e. lsbit is x^31 coefficient)

 * @len: The number of bytes. @crc is multiplied by x^(8*@len)

 * @polynomial: The modulus used to reduce the result to 32 bits.

 *

 * It's possible to parallelize CRC computations by computing a CRC

 * over separate ranges of a buffer, then summing them.

 * This shifts the given CRC by 8*len bits (i.e. produces the same effect

 * as appending len bytes of zero to the data), in time proportional

 * to log(len).

 */

static u32 __attribute_const__ crc32_generic_shift(u32 crc, size_t len,

						   u32 polynomial)

{

	u32 power = polynomial;	/* CRC of x^32 */

	int i;



	/* Shift up to 32 bits in the simple linear way */

	for (i = 0; i < 8 * (int)(len & 3); i++)

		crc = (crc >> 1) ^ (crc & 1 ? polynomial : 0);



	len >>= 2;

	if (!len)

		return crc;



	for (;;) {

		/* "power" is x^(2^i), modulo the polynomial */

		if (len & 1)

			crc = gf2_multiply(crc, power, polynomial);



		len >>= 1;

		if (!len)

			break;



		/* Square power, advancing to x^(2^(i+1)) */

		power = gf2_multiply(power, power, polynomial);

	}



	return crc;

}



u32 __attribute_const__ crc32_le_shift(u32 crc, size_t len)

{

	return crc32_generic_combine(crc1, crc2, len2, CRCPOLY_LE);

	return crc32_generic_shift(crc, len, CRCPOLY_LE);

}



u32 __pure __crc32c_le_combine(u32 crc1, u32 crc2, size_t len2)

u32 __attribute_const__ __crc32c_le_shift(u32 crc, size_t len)

{

	return crc32_generic_combine(crc1, crc2, len2, CRC32C_POLY_LE);

	return crc32_generic_shift(crc, len, CRC32C_POLY_LE);

}

EXPORT_SYMBOL(crc32_le);

EXPORT_SYMBOL(crc32_le_combine);

EXPORT_SYMBOL(__crc32c_le);

EXPORT_SYMBOL(__crc32c_le_combine);

EXPORT_SYMBOL(crc32_le_shift);

EXPORT_SYMBOL(__crc32c_le_shift);



/**

 * crc32_be_generic() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32
@@ -351,7 +344,7 @@ EXPORT_SYMBOL(crc32_be); 
#ifdef CONFIG_CRC32_SELFTEST



/* 4096 random bytes */

static u8 __attribute__((__aligned__(8))) test_buf[] =

static u8 const __aligned(8) test_buf[] __initconst =

{

	0x5b, 0x85, 0x21, 0xcb, 0x09, 0x68, 0x7d, 0x30,

	0xc7, 0x69, 0xd7, 0x30, 0x92, 0xde, 0x59, 0xe4,
@@ -875,7 +868,7 @@ static struct crc_test { 
	u32 crc_le;	/* expected crc32_le result */

	u32 crc_be;	/* expected crc32_be result */

	u32 crc32c_le;	/* expected crc32c_le result */

} test[] =

} const test[] __initconst =

{

	{0x674bf11d, 0x00000038, 0x00000542, 0x0af6d466, 0xd8b6e4c1, 0xf6e93d6c},

	{0x35c672c6, 0x0000003a, 0x000001aa, 0xc6d3dfba, 0x28aaf3ad, 0x0fe92aca},