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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: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2014-06-25 16:04:09 -07:00
parent 5433ba365f d8f1c4778e
commit cb8eb77663
2 changed files with 88 additions and 85 deletions
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20
include/linux/crc32.h
View File

@ -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)

153
lib/crc32.c
View File

@ -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)
{
return crc32_generic_combine(crc1, crc2, len2, CRCPOLY_LE);
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;
}
u32 __pure __crc32c_le_combine(u32 crc1, u32 crc2, size_t len2)
/**
* 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)
{
return crc32_generic_combine(crc1, crc2, len2, CRC32C_POLY_LE);
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;
}
EXPORT_SYMBOL(crc32_le);
EXPORT_SYMBOL(crc32_le_combine);
EXPORT_SYMBOL(__crc32c_le);
EXPORT_SYMBOL(__crc32c_le_combine);
u32 __attribute_const__ crc32_le_shift(u32 crc, size_t len)
{
return crc32_generic_shift(crc, len, CRCPOLY_LE);
}
u32 __attribute_const__ __crc32c_le_shift(u32 crc, size_t len)
{
return crc32_generic_shift(crc, len, CRC32C_POLY_LE);
}
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},