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Copy pathHash.cpp
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347 lines (303 loc) · 10.2 KB
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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
* Fletcher Checksums
* ------------------
*
* ZFS's 2nd and 4th order Fletcher checksums are defined by the following
* recurrence relations:
*
* a = a + f
* i i-1 i-1
*
* b = b + a
* i i-1 i
*
* c = c + b (fletcher-4 only)
* i i-1 i
*
* d = d + c (fletcher-4 only)
* i i-1 i
*
* Where
* a_0 = b_0 = c_0 = d_0 = 0
* and
* f_0 .. f_(n-1) are the input data.
*
* Using standard techniques, these translate into the following series:
*
* __n_ __n_
* \ | \ |
* a = > f b = > i * f
* n /___| n - i n /___| n - i
* i = 1 i = 1
*
*
* __n_ __n_
* \ | i*(i+1) \ | i*(i+1)*(i+2)
* c = > ------- f d = > ------------- f
* n /___| 2 n - i n /___| 6 n - i
* i = 1 i = 1
*
* For fletcher-2, the f_is are 64-bit, and [ab]_i are 64-bit accumulators.
* Since the additions are done mod (2^64), errors in the high bits may not
* be noticed. For this reason, fletcher-2 is deprecated.
*
* For fletcher-4, the f_is are 32-bit, and [abcd]_i are 64-bit accumulators.
* A conservative estimate of how big the buffer can get before we overflow
* can be estimated using f_i = 0xffffffff for all i:
*
* % bc
* f=2^32-1;d=0; for (i = 1; d<2^64; i++) { d += f*i*(i+1)*(i+2)/6 }; (i-1)*4
* 2264
* quit
* %
*
* So blocks of up to 2k will not overflow. Our largest block size is
* 128k, which has 32k 4-byte words, so we can compute the largest possible
* accumulators, then divide by 2^64 to figure the max amount of overflow:
*
* % bc
* a=b=c=d=0; f=2^32-1; for (i=1; i<=32*1024; i++) { a+=f; b+=a; c+=b; d+=c }
* a/2^64;b/2^64;c/2^64;d/2^64
* 0
* 0
* 1365
* 11186858
* quit
* %
*
* So a and b cannot overflow. To make sure each bit of input has some
* effect on the contents of c and d, we can look at what the factors of
* the coefficients in the equations for c_n and d_n are. The number of 2s
* in the factors determines the lowest set bit in the multiplier. Running
* through the cases for n*(n+1)/2 reveals that the highest power of 2 is
* 2^14, and for n*(n+1)*(n+2)/6 it is 2^15. So while some data may overflow
* the 64-bit accumulators, every bit of every f_i effects every accumulator,
* even for 128k blocks.
*
* If we wanted to make a stronger version of fletcher4 (fletcher4c?),
* we could do our calculations mod (2^32 - 1) by adding in the carries
* periodically, and store the number of carries in the top 32-bits.
*
* --------------------
* Checksum Performance
* --------------------
*
* There are two interesting components to checksum performance: cached and
* uncached performance. With cached data, fletcher-2 is about four times
* faster than fletcher-4. With uncached data, the performance difference is
* negligible, since the cost of a cache fill dominates the processing time.
* Even though fletcher-4 is slower than fletcher-2, it is still a pretty
* efficient pass over the data.
*
* In normal operation, the data which is being checksummed is in a buffer
* which has been filled either by:
*
* 1. a compression step, which will be mostly cached, or
* 2. a bcopy() or copyin(), which will be uncached (because the
* copy is cache-bypassing).
*
* For both cached and uncached data, both fletcher checksums are much faster
* than sha-256, and slower than 'off', which doesn't touch the data at all.
*/
#include "stdafx.h"
#include "Hash.h"
static void fletcher_2(const void* buf, uint64_t size, cksum_t* zcp)
{
const uint64_t* ip = (const uint64_t*)buf;
const uint64_t* ipend = ip + (size / sizeof(uint64_t));
uint64_t a0, b0, a1, b1;
for(a0 = b0 = a1 = b1 = 0; ip < ipend; ip += 2)
{
a0 += ip[0];
a1 += ip[1];
b0 += a0;
b1 += a1;
}
zcp->set(a0, a1, b0, b1);
}
static void fletcher_2_sse2(const void* buf, uint64_t size, cksum_t* zcp) // ~25% faster
{
const __m128i* p = (__m128i*)buf;
__m128i a = _mm_setzero_si128();
__m128i b = _mm_setzero_si128();
for(size_t i = 0, j = (size_t)(size >> 4); i < j; i++)
{
__m128i r = _mm_load_si128(&p[i]);
a = _mm_add_epi64(a, r);
b = _mm_add_epi64(b, a);
}
zcp->set(a.m128i_u64[0], a.m128i_u64[1], b.m128i_u64[0], b.m128i_u64[1]);
}
static void fletcher_4(const void* buf, uint64_t size, cksum_t* zcp)
{
const uint32_t* ip = (const uint32_t*)buf;
const uint32_t* ipend = ip + (size / sizeof(uint32_t));
uint64_t a, b, c, d;
for(a = b = c = d = 0; ip < ipend; ip++)
{
a += ip[0];
b += a;
c += b;
d += c;
}
zcp->set(a, b, c, d);
}
/*
#define Ch(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
#define Maj(x, y, z) (((x) & (y)) ^ ((z) & ((x) ^ (y))))
#define Rot32(x, s) (((x) >> s) | ((x) << (32 - s)))
#define SIGMA0(x) (Rot32(x, 2) ^ Rot32(x, 13) ^ Rot32(x, 22))
#define SIGMA1(x) (Rot32(x, 6) ^ Rot32(x, 11) ^ Rot32(x, 25))
#define sigma0(x) (Rot32(x, 7) ^ Rot32(x, 18) ^ ((x) >> 3))
#define sigma1(x) (Rot32(x, 17) ^ Rot32(x, 19) ^ ((x) >> 10))
static const uint32_t SHA256_K[64] = {
0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
};
static void SHA256Transform(uint32_t *H, const uint8_t *cp)
{
uint32_t a, b, c, d, e, f, g, h, t, T1, T2, W[64];
for (t = 0; t < 16; t++, cp += 4)
W[t] = (cp[0] << 24) | (cp[1] << 16) | (cp[2] << 8) | cp[3];
for (t = 16; t < 64; t++)
W[t] = sigma1(W[t - 2]) + W[t - 7] +
sigma0(W[t - 15]) + W[t - 16];
a = H[0]; b = H[1]; c = H[2]; d = H[3];
e = H[4]; f = H[5]; g = H[6]; h = H[7];
for (t = 0; t < 64; t++) {
T1 = h + SIGMA1(e) + Ch(e, f, g) + SHA256_K[t] + W[t];
T2 = SIGMA0(a) + Maj(a, b, c);
h = g; g = f; f = e; e = d + T1;
d = c; c = b; b = a; a = T1 + T2;
}
H[0] += a; H[1] += b; H[2] += c; H[3] += d;
H[4] += e; H[5] += f; H[6] += g; H[7] += h;
}
static void sha256(const void *buf, uint64_t size, cksum_t *zcp)
{
uint32_t H[8] = { 0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19 };
uint8_t pad[128];
int padsize = size & 63;
int i;
for (i = 0; i < size - padsize; i += 64)
SHA256Transform(H, (uint8_t *)buf + i);
for (i = 0; i < padsize; i++)
pad[i] = ((uint8_t *)buf)[i];
for (pad[padsize++] = 0x80; (padsize & 63) != 56; padsize++)
pad[padsize] = 0;
for (i = 0; i < 8; i++)
pad[padsize++] = (size << 3) >> (56 - 8 * i);
for (i = 0; i < padsize; i += 64)
SHA256Transform(H, pad + i);
zcp->set(
(uint64_t)H[0] << 32 | H[1],
(uint64_t)H[2] << 32 | H[3],
(uint64_t)H[4] << 32 | H[5],
(uint64_t)H[6] << 32 | H[7]);
}
*/
static void sha256(const void* buf, uint64_t size, cksum_t* zcp)
{
HCRYPTPROV hCryptProv;
HCRYPTHASH hHash;
if(CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT))
{
if(CryptCreateHash(hCryptProv, CALG_SHA_256, 0, 0, &hHash))
{
if(CryptHashData(hHash, (BYTE*)buf, (DWORD)size, 0))
{
DWORD dwHashLen = sizeof(cksum_t);
if(CryptGetHashParam(hHash, HP_HASHVAL, (BYTE*)zcp, &dwHashLen, 0))
{
zcp->word[0] = BSWAP_64(zcp->word[0]);
zcp->word[1] = BSWAP_64(zcp->word[1]);
zcp->word[2] = BSWAP_64(zcp->word[2]);
zcp->word[3] = BSWAP_64(zcp->word[3]);
}
}
}
}
CryptDestroyHash(hHash);
CryptReleaseContext(hCryptProv, 0);
}
typedef void (*cksum_func_t)(const void* buf, uint64_t size, cksum_t* zcp);
static struct cksum_func_struct
{
cksum_func_t f[ZIO_CHECKSUM_FUNCTIONS];
struct cksum_func_struct()
{
f[ZIO_CHECKSUM_INHERIT] = NULL;
f[ZIO_CHECKSUM_ON] = fletcher_2;
f[ZIO_CHECKSUM_OFF] = NULL;
f[ZIO_CHECKSUM_LABEL] = sha256;
f[ZIO_CHECKSUM_GANG_HEADER] = sha256;
f[ZIO_CHECKSUM_ZILOG] = fletcher_2;
f[ZIO_CHECKSUM_FLETCHER_2] = fletcher_2;
f[ZIO_CHECKSUM_FLETCHER_4] = fletcher_4;
f[ZIO_CHECKSUM_SHA256] = sha256;
f[ZIO_CHECKSUM_ZILOG2] = fletcher_4;
int buff[4];
__cpuid(buff, 0x80000000);
if((DWORD)buff[0] >= 1)
{
__cpuid(buff, 1);
if(buff[3] & (1 << 26)) // SSE2
{
f[ZIO_CHECKSUM_ON] = fletcher_2_sse2;
f[ZIO_CHECKSUM_ZILOG] = fletcher_2_sse2;
f[ZIO_CHECKSUM_FLETCHER_2] = fletcher_2_sse2;
}
}
}
} s_cksum_func;
void ZFS::hash(const void* buf, uint64_t size, cksum_t* zcp, uint8_t cksum_type)
{
memset(zcp, 0, sizeof(*zcp));
if(cksum_type < sizeof(s_cksum_func.f) / sizeof(s_cksum_func.f[0]))
{
cksum_func_t f = s_cksum_func.f[cksum_type];
if(f != NULL)
{
f(buf, size, zcp);
}
}
}