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linux-hardened/lib/xxhash.c
Nick Terrell 5d2405227a lib: Add xxhash module 
Adds xxhash kernel module with xxh32 and xxh64 hashes. xxhash is an
extremely fast non-cryptographic hash algorithm for checksumming.
The zstd compression and decompression modules added in the next patch
require xxhash. I extracted it out from zstd since it is useful on its
own. I copied the code from the upstream XXHash source repository and
translated it into kernel style. I ran benchmarks and tests in the kernel
and tests in userland.

I benchmarked xxhash as a special character device. I ran in four modes,
no-op, xxh32, xxh64, and crc32. The no-op mode simply copies the data to
kernel space and ignores it. The xxh32, xxh64, and crc32 modes compute
hashes on the copied data. I also ran it with four different buffer sizes.
The benchmark file is located in the upstream zstd source repository under
`contrib/linux-kernel/xxhash_test.c` [1].

I ran the benchmarks on a Ubuntu 14.04 VM with 2 cores and 4 GiB of RAM.
The VM is running on a MacBook Pro with a 3.1 GHz Intel Core i7 processor,
16 GB of RAM, and a SSD. I benchmarked using the file `filesystem.squashfs`
from `ubuntu-16.10-desktop-amd64.iso`, which is 1,536,217,088 B large.
Run the following commands for the benchmark:

    modprobe xxhash_test
    mknod xxhash_test c 245 0
    time cp filesystem.squashfs xxhash_test

The time is reported by the time of the userland `cp`.
The GB/s is computed with

    1,536,217,008 B / time(buffer size, hash)

which includes the time to copy from userland.
The Normalized GB/s is computed with

    1,536,217,088 B / (time(buffer size, hash) - time(buffer size, none)).

| Buffer Size (B) | Hash  | Time (s) | GB/s | Adjusted GB/s |
|-----------------|-------|----------|------|---------------|
|            1024 | none  |    0.408 | 3.77 |             - |
|            1024 | xxh32 |    0.649 | 2.37 |          6.37 |
|            1024 | xxh64 |    0.542 | 2.83 |         11.46 |
|            1024 | crc32 |    1.290 | 1.19 |          1.74 |
|            4096 | none  |    0.380 | 4.04 |             - |
|            4096 | xxh32 |    0.645 | 2.38 |          5.79 |
|            4096 | xxh64 |    0.500 | 3.07 |         12.80 |
|            4096 | crc32 |    1.168 | 1.32 |          1.95 |
|            8192 | none  |    0.351 | 4.38 |             - |
|            8192 | xxh32 |    0.614 | 2.50 |          5.84 |
|            8192 | xxh64 |    0.464 | 3.31 |         13.60 |
|            8192 | crc32 |    1.163 | 1.32 |          1.89 |
|           16384 | none  |    0.346 | 4.43 |             - |
|           16384 | xxh32 |    0.590 | 2.60 |          6.30 |
|           16384 | xxh64 |    0.466 | 3.30 |         12.80 |
|           16384 | crc32 |    1.183 | 1.30 |          1.84 |

Tested in userland using the test-suite in the zstd repo under
`contrib/linux-kernel/test/XXHashUserlandTest.cpp` [2] by mocking the
kernel functions. A line in each branch of every function in `xxhash.c`
was commented out to ensure that the test-suite fails. Additionally
tested while testing zstd and with SMHasher [3].

[1] https://phabricator.intern.facebook.com/P57526246
[2] https://github.com/facebook/zstd/blob/dev/contrib/linux-kernel/test/XXHashUserlandTest.cpp
[3] https://github.com/aappleby/smhasher

zstd source repository: https://github.com/facebook/zstd
XXHash source repository: https://github.com/cyan4973/xxhash

Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
2017-08-15 09:02:07 -07:00

500 lines
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/*
* xxHash - Extremely Fast Hash algorithm
* Copyright (C) 2012-2016, Yann Collet.
*
* BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License version 2 as published by the
* Free Software Foundation. This program is dual-licensed; you may select
* either version 2 of the GNU General Public License ("GPL") or BSD license
* ("BSD").
*
* You can contact the author at:
* - xxHash homepage: http://cyan4973.github.io/xxHash/
* - xxHash source repository: https://github.com/Cyan4973/xxHash
*/
#include <asm/unaligned.h>
#include <linux/errno.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/xxhash.h>
/*-*************************************
* Macros
**************************************/
#define xxh_rotl32(x, r) ((x << r) | (x >> (32 - r)))
#define xxh_rotl64(x, r) ((x << r) | (x >> (64 - r)))
#ifdef __LITTLE_ENDIAN
# define XXH_CPU_LITTLE_ENDIAN 1
#else
# define XXH_CPU_LITTLE_ENDIAN 0
#endif
/*-*************************************
* Constants
**************************************/
static const uint32_t PRIME32_1 = 2654435761U;
static const uint32_t PRIME32_2 = 2246822519U;
static const uint32_t PRIME32_3 = 3266489917U;
static const uint32_t PRIME32_4 = 668265263U;
static const uint32_t PRIME32_5 = 374761393U;
static const uint64_t PRIME64_1 = 11400714785074694791ULL;
static const uint64_t PRIME64_2 = 14029467366897019727ULL;
static const uint64_t PRIME64_3 = 1609587929392839161ULL;
static const uint64_t PRIME64_4 = 9650029242287828579ULL;
static const uint64_t PRIME64_5 = 2870177450012600261ULL;
/*-**************************
* Utils
***************************/
void xxh32_copy_state(struct xxh32_state *dst, const struct xxh32_state *src)
{
memcpy(dst, src, sizeof(*dst));
}
EXPORT_SYMBOL(xxh32_copy_state);
void xxh64_copy_state(struct xxh64_state *dst, const struct xxh64_state *src)
{
memcpy(dst, src, sizeof(*dst));
}
EXPORT_SYMBOL(xxh64_copy_state);
/*-***************************
* Simple Hash Functions
****************************/
static uint32_t xxh32_round(uint32_t seed, const uint32_t input)
{
seed += input * PRIME32_2;
seed = xxh_rotl32(seed, 13);
seed *= PRIME32_1;
return seed;
}
uint32_t xxh32(const void *input, const size_t len, const uint32_t seed)
{
const uint8_t *p = (const uint8_t *)input;
const uint8_t *b_end = p + len;
uint32_t h32;
if (len >= 16) {
const uint8_t *const limit = b_end - 16;
uint32_t v1 = seed + PRIME32_1 + PRIME32_2;
uint32_t v2 = seed + PRIME32_2;
uint32_t v3 = seed + 0;
uint32_t v4 = seed - PRIME32_1;
do {
v1 = xxh32_round(v1, get_unaligned_le32(p));
p += 4;
v2 = xxh32_round(v2, get_unaligned_le32(p));
p += 4;
v3 = xxh32_round(v3, get_unaligned_le32(p));
p += 4;
v4 = xxh32_round(v4, get_unaligned_le32(p));
p += 4;
} while (p <= limit);
h32 = xxh_rotl32(v1, 1) + xxh_rotl32(v2, 7) +
xxh_rotl32(v3, 12) + xxh_rotl32(v4, 18);
} else {
h32 = seed + PRIME32_5;
}
h32 += (uint32_t)len;
while (p + 4 <= b_end) {
h32 += get_unaligned_le32(p) * PRIME32_3;
h32 = xxh_rotl32(h32, 17) * PRIME32_4;
p += 4;
}
while (p < b_end) {
h32 += (*p) * PRIME32_5;
h32 = xxh_rotl32(h32, 11) * PRIME32_1;
p++;
}
h32 ^= h32 >> 15;
h32 *= PRIME32_2;
h32 ^= h32 >> 13;
h32 *= PRIME32_3;
h32 ^= h32 >> 16;
return h32;
}
EXPORT_SYMBOL(xxh32);
static uint64_t xxh64_round(uint64_t acc, const uint64_t input)
{
acc += input * PRIME64_2;
acc = xxh_rotl64(acc, 31);
acc *= PRIME64_1;
return acc;
}
static uint64_t xxh64_merge_round(uint64_t acc, uint64_t val)
{
val = xxh64_round(0, val);
acc ^= val;
acc = acc * PRIME64_1 + PRIME64_4;
return acc;
}
uint64_t xxh64(const void *input, const size_t len, const uint64_t seed)
{
const uint8_t *p = (const uint8_t *)input;
const uint8_t *const b_end = p + len;
uint64_t h64;
if (len >= 32) {
const uint8_t *const limit = b_end - 32;
uint64_t v1 = seed + PRIME64_1 + PRIME64_2;
uint64_t v2 = seed + PRIME64_2;
uint64_t v3 = seed + 0;
uint64_t v4 = seed - PRIME64_1;
do {
v1 = xxh64_round(v1, get_unaligned_le64(p));
p += 8;
v2 = xxh64_round(v2, get_unaligned_le64(p));
p += 8;
v3 = xxh64_round(v3, get_unaligned_le64(p));
p += 8;
v4 = xxh64_round(v4, get_unaligned_le64(p));
p += 8;
} while (p <= limit);
h64 = xxh_rotl64(v1, 1) + xxh_rotl64(v2, 7) +
xxh_rotl64(v3, 12) + xxh_rotl64(v4, 18);
h64 = xxh64_merge_round(h64, v1);
h64 = xxh64_merge_round(h64, v2);
h64 = xxh64_merge_round(h64, v3);
h64 = xxh64_merge_round(h64, v4);
} else {
h64 = seed + PRIME64_5;
}
h64 += (uint64_t)len;
while (p + 8 <= b_end) {
const uint64_t k1 = xxh64_round(0, get_unaligned_le64(p));
h64 ^= k1;
h64 = xxh_rotl64(h64, 27) * PRIME64_1 + PRIME64_4;
p += 8;
}
if (p + 4 <= b_end) {
h64 ^= (uint64_t)(get_unaligned_le32(p)) * PRIME64_1;
h64 = xxh_rotl64(h64, 23) * PRIME64_2 + PRIME64_3;
p += 4;
}
while (p < b_end) {
h64 ^= (*p) * PRIME64_5;
h64 = xxh_rotl64(h64, 11) * PRIME64_1;
p++;
}
h64 ^= h64 >> 33;
h64 *= PRIME64_2;
h64 ^= h64 >> 29;
h64 *= PRIME64_3;
h64 ^= h64 >> 32;
return h64;
}
EXPORT_SYMBOL(xxh64);
/*-**************************************************
* Advanced Hash Functions
***************************************************/
void xxh32_reset(struct xxh32_state *statePtr, const uint32_t seed)
{
/* use a local state for memcpy() to avoid strict-aliasing warnings */
struct xxh32_state state;
memset(&state, 0, sizeof(state));
state.v1 = seed + PRIME32_1 + PRIME32_2;
state.v2 = seed + PRIME32_2;
state.v3 = seed + 0;
state.v4 = seed - PRIME32_1;
memcpy(statePtr, &state, sizeof(state));
}
EXPORT_SYMBOL(xxh32_reset);
void xxh64_reset(struct xxh64_state *statePtr, const uint64_t seed)
{
/* use a local state for memcpy() to avoid strict-aliasing warnings */
struct xxh64_state state;
memset(&state, 0, sizeof(state));
state.v1 = seed + PRIME64_1 + PRIME64_2;
state.v2 = seed + PRIME64_2;
state.v3 = seed + 0;
state.v4 = seed - PRIME64_1;
memcpy(statePtr, &state, sizeof(state));
}
EXPORT_SYMBOL(xxh64_reset);
int xxh32_update(struct xxh32_state *state, const void *input, const size_t len)
{
const uint8_t *p = (const uint8_t *)input;
const uint8_t *const b_end = p + len;
if (input == NULL)
return -EINVAL;
state->total_len_32 += (uint32_t)len;
state->large_len |= (len >= 16) | (state->total_len_32 >= 16);
if (state->memsize + len < 16) { /* fill in tmp buffer */
memcpy((uint8_t *)(state->mem32) + state->memsize, input, len);
state->memsize += (uint32_t)len;
return 0;
}
if (state->memsize) { /* some data left from previous update */
const uint32_t *p32 = state->mem32;
memcpy((uint8_t *)(state->mem32) + state->memsize, input,
16 - state->memsize);
state->v1 = xxh32_round(state->v1, get_unaligned_le32(p32));
p32++;
state->v2 = xxh32_round(state->v2, get_unaligned_le32(p32));
p32++;
state->v3 = xxh32_round(state->v3, get_unaligned_le32(p32));
p32++;
state->v4 = xxh32_round(state->v4, get_unaligned_le32(p32));
p32++;
p += 16-state->memsize;
state->memsize = 0;
}
if (p <= b_end - 16) {
const uint8_t *const limit = b_end - 16;
uint32_t v1 = state->v1;
uint32_t v2 = state->v2;
uint32_t v3 = state->v3;
uint32_t v4 = state->v4;
do {
v1 = xxh32_round(v1, get_unaligned_le32(p));
p += 4;
v2 = xxh32_round(v2, get_unaligned_le32(p));
p += 4;
v3 = xxh32_round(v3, get_unaligned_le32(p));
p += 4;
v4 = xxh32_round(v4, get_unaligned_le32(p));
p += 4;
} while (p <= limit);
state->v1 = v1;
state->v2 = v2;
state->v3 = v3;
state->v4 = v4;
}
if (p < b_end) {
memcpy(state->mem32, p, (size_t)(b_end-p));
state->memsize = (uint32_t)(b_end-p);
}
return 0;
}
EXPORT_SYMBOL(xxh32_update);
uint32_t xxh32_digest(const struct xxh32_state *state)
{
const uint8_t *p = (const uint8_t *)state->mem32;
const uint8_t *const b_end = (const uint8_t *)(state->mem32) +
state->memsize;
uint32_t h32;
if (state->large_len) {
h32 = xxh_rotl32(state->v1, 1) + xxh_rotl32(state->v2, 7) +
xxh_rotl32(state->v3, 12) + xxh_rotl32(state->v4, 18);
} else {
h32 = state->v3 /* == seed */ + PRIME32_5;
}
h32 += state->total_len_32;
while (p + 4 <= b_end) {
h32 += get_unaligned_le32(p) * PRIME32_3;
h32 = xxh_rotl32(h32, 17) * PRIME32_4;
p += 4;
}
while (p < b_end) {
h32 += (*p) * PRIME32_5;
h32 = xxh_rotl32(h32, 11) * PRIME32_1;
p++;
}
h32 ^= h32 >> 15;
h32 *= PRIME32_2;
h32 ^= h32 >> 13;
h32 *= PRIME32_3;
h32 ^= h32 >> 16;
return h32;
}
EXPORT_SYMBOL(xxh32_digest);
int xxh64_update(struct xxh64_state *state, const void *input, const size_t len)
{
const uint8_t *p = (const uint8_t *)input;
const uint8_t *const b_end = p + len;
if (input == NULL)
return -EINVAL;
state->total_len += len;
if (state->memsize + len < 32) { /* fill in tmp buffer */
memcpy(((uint8_t *)state->mem64) + state->memsize, input, len);
state->memsize += (uint32_t)len;
return 0;
}
if (state->memsize) { /* tmp buffer is full */
uint64_t *p64 = state->mem64;
memcpy(((uint8_t *)p64) + state->memsize, input,
32 - state->memsize);
state->v1 = xxh64_round(state->v1, get_unaligned_le64(p64));
p64++;
state->v2 = xxh64_round(state->v2, get_unaligned_le64(p64));
p64++;
state->v3 = xxh64_round(state->v3, get_unaligned_le64(p64));
p64++;
state->v4 = xxh64_round(state->v4, get_unaligned_le64(p64));
p += 32 - state->memsize;
state->memsize = 0;
}
if (p + 32 <= b_end) {
const uint8_t *const limit = b_end - 32;
uint64_t v1 = state->v1;
uint64_t v2 = state->v2;
uint64_t v3 = state->v3;
uint64_t v4 = state->v4;
do {
v1 = xxh64_round(v1, get_unaligned_le64(p));
p += 8;
v2 = xxh64_round(v2, get_unaligned_le64(p));
p += 8;
v3 = xxh64_round(v3, get_unaligned_le64(p));
p += 8;
v4 = xxh64_round(v4, get_unaligned_le64(p));
p += 8;
} while (p <= limit);
state->v1 = v1;
state->v2 = v2;
state->v3 = v3;
state->v4 = v4;
}
if (p < b_end) {
memcpy(state->mem64, p, (size_t)(b_end-p));
state->memsize = (uint32_t)(b_end - p);
}
return 0;
}
EXPORT_SYMBOL(xxh64_update);
uint64_t xxh64_digest(const struct xxh64_state *state)
{
const uint8_t *p = (const uint8_t *)state->mem64;
const uint8_t *const b_end = (const uint8_t *)state->mem64 +
state->memsize;
uint64_t h64;
if (state->total_len >= 32) {
const uint64_t v1 = state->v1;
const uint64_t v2 = state->v2;
const uint64_t v3 = state->v3;
const uint64_t v4 = state->v4;
h64 = xxh_rotl64(v1, 1) + xxh_rotl64(v2, 7) +
xxh_rotl64(v3, 12) + xxh_rotl64(v4, 18);
h64 = xxh64_merge_round(h64, v1);
h64 = xxh64_merge_round(h64, v2);
h64 = xxh64_merge_round(h64, v3);
h64 = xxh64_merge_round(h64, v4);
} else {
h64 = state->v3 + PRIME64_5;
}
h64 += (uint64_t)state->total_len;
while (p + 8 <= b_end) {
const uint64_t k1 = xxh64_round(0, get_unaligned_le64(p));
h64 ^= k1;
h64 = xxh_rotl64(h64, 27) * PRIME64_1 + PRIME64_4;
p += 8;
}
if (p + 4 <= b_end) {
h64 ^= (uint64_t)(get_unaligned_le32(p)) * PRIME64_1;
h64 = xxh_rotl64(h64, 23) * PRIME64_2 + PRIME64_3;
p += 4;
}
while (p < b_end) {
h64 ^= (*p) * PRIME64_5;
h64 = xxh_rotl64(h64, 11) * PRIME64_1;
p++;
}
h64 ^= h64 >> 33;
h64 *= PRIME64_2;
h64 ^= h64 >> 29;
h64 *= PRIME64_3;
h64 ^= h64 >> 32;
return h64;
}
EXPORT_SYMBOL(xxh64_digest);
MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION("xxHash");
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