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lib/crc32: remove other generic implementations

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Now that we've standardized on the byte-by-byte implementation of CRC32
as the only generic implementation (see previous commit for the
rationale), remove the code for the other implementations.

Tested with crc_kunit.

Link: https://lore.kernel.org/r/20250123212904.118683-3-ebiggers@kernel.org
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
This commit is contained in:
Eric Biggers 2025-01-23 13:29:04 -08:00
parent b0430f39de
commit 5e3c1c48fa
4 changed files with 42 additions and 363 deletions
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4
lib/Kconfig
View file

@ -189,7 +189,6 @@ config CRC32
tristate "CRC32/CRC32c functions"
default y
select BITREVERSE
select CRC32_SARWATE
help
This option is provided for the case where no in-kernel-tree
modules require CRC32/CRC32c functions, but a module built outside
@ -203,9 +202,6 @@ config CRC32_ARCH
tristate
default CRC32 if ARCH_HAS_CRC32 && CRC_OPTIMIZATIONS
config CRC32_SARWATE
bool
config CRC64
tristate "CRC64 functions"
help

231
lib/crc32.c
View file

@ -30,20 +30,6 @@
#include <linux/crc32poly.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/sched.h>
#include "crc32defs.h"
#if CRC_LE_BITS > 8
# define tole(x) ((__force u32) cpu_to_le32(x))
#else
# define tole(x) (x)
#endif
#if CRC_BE_BITS > 8
# define tobe(x) ((__force u32) cpu_to_be32(x))
#else
# define tobe(x) (x)
#endif
#include "crc32table.h"
@ -51,157 +37,20 @@ MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>");
MODULE_DESCRIPTION("Various CRC32 calculations");
MODULE_LICENSE("GPL");
#if CRC_LE_BITS > 8 || CRC_BE_BITS > 8
/* implements slicing-by-4 or slicing-by-8 algorithm */
static inline u32 __pure
crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
{
# ifdef __LITTLE_ENDIAN
# define DO_CRC(x) crc = t0[(crc ^ (x)) & 255] ^ (crc >> 8)
# define DO_CRC4 (t3[(q) & 255] ^ t2[(q >> 8) & 255] ^ \
t1[(q >> 16) & 255] ^ t0[(q >> 24) & 255])
# define DO_CRC8 (t7[(q) & 255] ^ t6[(q >> 8) & 255] ^ \
t5[(q >> 16) & 255] ^ t4[(q >> 24) & 255])
# else
# define DO_CRC(x) crc = t0[((crc >> 24) ^ (x)) & 255] ^ (crc << 8)
# define DO_CRC4 (t0[(q) & 255] ^ t1[(q >> 8) & 255] ^ \
t2[(q >> 16) & 255] ^ t3[(q >> 24) & 255])
# define DO_CRC8 (t4[(q) & 255] ^ t5[(q >> 8) & 255] ^ \
t6[(q >> 16) & 255] ^ t7[(q >> 24) & 255])
# endif
const u32 *b;
size_t rem_len;
# ifdef CONFIG_X86
size_t i;
# endif
const u32 *t0=tab[0], *t1=tab[1], *t2=tab[2], *t3=tab[3];
# if CRC_LE_BITS != 32
const u32 *t4 = tab[4], *t5 = tab[5], *t6 = tab[6], *t7 = tab[7];
# endif
u32 q;
/* Align it */
if (unlikely((long)buf & 3 && len)) {
do {
DO_CRC(*buf++);
} while ((--len) && ((long)buf)&3);
}
# if CRC_LE_BITS == 32
rem_len = len & 3;
len = len >> 2;
# else
rem_len = len & 7;
len = len >> 3;
# endif
b = (const u32 *)buf;
# ifdef CONFIG_X86
--b;
for (i = 0; i < len; i++) {
# else
for (--b; len; --len) {
# endif
q = crc ^ *++b; /* use pre increment for speed */
# if CRC_LE_BITS == 32
crc = DO_CRC4;
# else
crc = DO_CRC8;
q = *++b;
crc ^= DO_CRC4;
# endif
}
len = rem_len;
/* And the last few bytes */
if (len) {
u8 *p = (u8 *)(b + 1) - 1;
# ifdef CONFIG_X86
for (i = 0; i < len; i++)
DO_CRC(*++p); /* use pre increment for speed */
# else
do {
DO_CRC(*++p); /* use pre increment for speed */
} while (--len);
# endif
}
return crc;
#undef DO_CRC
#undef DO_CRC4
#undef DO_CRC8
}
#endif
/**
* crc32_le_generic() - Calculate bitwise little-endian Ethernet AUTODIN II
* CRC32/CRC32C
* @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for other
* uses, or the previous crc32/crc32c value if computing incrementally.
* @p: pointer to buffer over which CRC32/CRC32C is run
* @len: length of buffer @p
* @tab: little-endian Ethernet table
* @polynomial: CRC32/CRC32c LE polynomial
*/
static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,
size_t len, const u32 (*tab)[256],
u32 polynomial)
{
#if CRC_LE_BITS == 1
int i;
while (len--) {
crc ^= *p++;
for (i = 0; i < 8; i++)
crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
}
# elif CRC_LE_BITS == 2
while (len--) {
crc ^= *p++;
crc = (crc >> 2) ^ tab[0][crc & 3];
crc = (crc >> 2) ^ tab[0][crc & 3];
crc = (crc >> 2) ^ tab[0][crc & 3];
crc = (crc >> 2) ^ tab[0][crc & 3];
}
# elif CRC_LE_BITS == 4
while (len--) {
crc ^= *p++;
crc = (crc >> 4) ^ tab[0][crc & 15];
crc = (crc >> 4) ^ tab[0][crc & 15];
}
# elif CRC_LE_BITS == 8
/* aka Sarwate algorithm */
while (len--) {
crc ^= *p++;
crc = (crc >> 8) ^ tab[0][crc & 255];
}
# else
crc = (__force u32) __cpu_to_le32(crc);
crc = crc32_body(crc, p, len, tab);
crc = __le32_to_cpu((__force __le32)crc);
#endif
return crc;
}
#if CRC_LE_BITS == 1
u32 __pure crc32_le_base(u32 crc, const u8 *p, size_t len)
{
return crc32_le_generic(crc, p, len, NULL, CRC32_POLY_LE);
while (len--)
crc = (crc >> 8) ^ crc32table_le[(crc & 255) ^ *p++];
return crc;
}
u32 __pure crc32c_le_base(u32 crc, const u8 *p, size_t len)
{
return crc32_le_generic(crc, p, len, NULL, CRC32C_POLY_LE);
}
#else
u32 __pure crc32_le_base(u32 crc, const u8 *p, size_t len)
{
return crc32_le_generic(crc, p, len, crc32table_le, CRC32_POLY_LE);
}
u32 __pure crc32c_le_base(u32 crc, const u8 *p, size_t len)
{
return crc32_le_generic(crc, p, len, crc32ctable_le, CRC32C_POLY_LE);
}
#endif
EXPORT_SYMBOL(crc32_le_base);
u32 __pure crc32c_le_base(u32 crc, const u8 *p, size_t len)
{
while (len--)
crc = (crc >> 8) ^ crc32ctable_le[(crc & 255) ^ *p++];
return crc;
}
EXPORT_SYMBOL(crc32c_le_base);
/*
@ -277,64 +126,10 @@ u32 __attribute_const__ __crc32c_le_shift(u32 crc, size_t len)
EXPORT_SYMBOL(crc32_le_shift);
EXPORT_SYMBOL(__crc32c_le_shift);
/**
* crc32_be_generic() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32
* @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for
* other uses, or the previous crc32 value if computing incrementally.
* @p: pointer to buffer over which CRC32 is run
* @len: length of buffer @p
* @tab: big-endian Ethernet table
* @polynomial: CRC32 BE polynomial
*/
static inline u32 __pure crc32_be_generic(u32 crc, unsigned char const *p,
size_t len, const u32 (*tab)[256],
u32 polynomial)
u32 __pure crc32_be_base(u32 crc, const u8 *p, size_t len)
{
#if CRC_BE_BITS == 1
int i;
while (len--) {
crc ^= *p++ << 24;
for (i = 0; i < 8; i++)
crc =
(crc << 1) ^ ((crc & 0x80000000) ? polynomial :
0);
}
# elif CRC_BE_BITS == 2
while (len--) {
crc ^= *p++ << 24;
crc = (crc << 2) ^ tab[0][crc >> 30];
crc = (crc << 2) ^ tab[0][crc >> 30];
crc = (crc << 2) ^ tab[0][crc >> 30];
crc = (crc << 2) ^ tab[0][crc >> 30];
}
# elif CRC_BE_BITS == 4
while (len--) {
crc ^= *p++ << 24;
crc = (crc << 4) ^ tab[0][crc >> 28];
crc = (crc << 4) ^ tab[0][crc >> 28];
}
# elif CRC_BE_BITS == 8
while (len--) {
crc ^= *p++ << 24;
crc = (crc << 8) ^ tab[0][crc >> 24];
}
# else
crc = (__force u32) __cpu_to_be32(crc);
crc = crc32_body(crc, p, len, tab);
crc = __be32_to_cpu((__force __be32)crc);
# endif
while (len--)
crc = (crc << 8) ^ crc32table_be[(crc >> 24) ^ *p++];
return crc;
}
#if CRC_BE_BITS == 1
u32 __pure crc32_be_base(u32 crc, const u8 *p, size_t len)
{
return crc32_be_generic(crc, p, len, NULL, CRC32_POLY_BE);
}
#else
u32 __pure crc32_be_base(u32 crc, const u8 *p, size_t len)
{
return crc32_be_generic(crc, p, len, crc32table_be, CRC32_POLY_BE);
}
#endif
EXPORT_SYMBOL(crc32_be_base);

59
lib/crc32defs.h
View file

@ -1,59 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0 */
/* Try to choose an implementation variant via Kconfig */
#ifdef CONFIG_CRC32_SLICEBY8
# define CRC_LE_BITS 64
# define CRC_BE_BITS 64
#endif
#ifdef CONFIG_CRC32_SLICEBY4
# define CRC_LE_BITS 32
# define CRC_BE_BITS 32
#endif
#ifdef CONFIG_CRC32_SARWATE
# define CRC_LE_BITS 8
# define CRC_BE_BITS 8
#endif
#ifdef CONFIG_CRC32_BIT
# define CRC_LE_BITS 1
# define CRC_BE_BITS 1
#endif
/*
* How many bits at a time to use. Valid values are 1, 2, 4, 8, 32 and 64.
* For less performance-sensitive, use 4 or 8 to save table size.
* For larger systems choose same as CPU architecture as default.
* This works well on X86_64, SPARC64 systems. This may require some
* elaboration after experiments with other architectures.
*/
#ifndef CRC_LE_BITS
# ifdef CONFIG_64BIT
# define CRC_LE_BITS 64
# else
# define CRC_LE_BITS 32
# endif
#endif
#ifndef CRC_BE_BITS
# ifdef CONFIG_64BIT
# define CRC_BE_BITS 64
# else
# define CRC_BE_BITS 32
# endif
#endif
/*
* Little-endian CRC computation. Used with serial bit streams sent
* lsbit-first. Be sure to use cpu_to_le32() to append the computed CRC.
*/
#if CRC_LE_BITS > 64 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \
CRC_LE_BITS & CRC_LE_BITS-1
# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32, 64}"
#endif
/*
* Big-endian CRC computation. Used with serial bit streams sent
* msbit-first. Be sure to use cpu_to_be32() to append the computed CRC.
*/
#if CRC_BE_BITS > 64 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \
CRC_BE_BITS & CRC_BE_BITS-1
# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32, 64}"
#endif

111
lib/gen_crc32table.c
View file

@ -2,30 +2,11 @@
#include <stdio.h>
#include "../include/linux/crc32poly.h"
#include "../include/generated/autoconf.h"
#include "crc32defs.h"
#include <inttypes.h>
#define ENTRIES_PER_LINE 4
#if CRC_LE_BITS > 8
# define LE_TABLE_ROWS (CRC_LE_BITS/8)
# define LE_TABLE_SIZE 256
#else
# define LE_TABLE_ROWS 1
# define LE_TABLE_SIZE (1 << CRC_LE_BITS)
#endif
#if CRC_BE_BITS > 8
# define BE_TABLE_ROWS (CRC_BE_BITS/8)
# define BE_TABLE_SIZE 256
#else
# define BE_TABLE_ROWS 1
# define BE_TABLE_SIZE (1 << CRC_BE_BITS)
#endif
static uint32_t crc32table_le[LE_TABLE_ROWS][256];
static uint32_t crc32table_be[BE_TABLE_ROWS][256];
static uint32_t crc32ctable_le[LE_TABLE_ROWS][256];
static uint32_t crc32table_le[256];
static uint32_t crc32table_be[256];
static uint32_t crc32ctable_le[256];
/**
* crc32init_le() - allocate and initialize LE table data
@ -34,25 +15,17 @@ static uint32_t crc32ctable_le[LE_TABLE_ROWS][256];
* fact that crctable[i^j] = crctable[i] ^ crctable[j].
*
*/
static void crc32init_le_generic(const uint32_t polynomial,
uint32_t (*tab)[256])
static void crc32init_le_generic(const uint32_t polynomial, uint32_t tab[256])
{
unsigned i, j;
uint32_t crc = 1;
tab[0][0] = 0;
tab[0] = 0;
for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) {
for (i = 128; i; i >>= 1) {
crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
tab[0][i + j] = crc ^ tab[0][j];
}
for (i = 0; i < LE_TABLE_SIZE; i++) {
crc = tab[0][i];
for (j = 1; j < LE_TABLE_ROWS; j++) {
crc = tab[0][crc & 0xff] ^ (crc >> 8);
tab[j][i] = crc;
}
for (j = 0; j < 256; j += 2 * i)
tab[i + j] = crc ^ tab[j];
}
}
@ -74,34 +47,22 @@ static void crc32init_be(void)
unsigned i, j;
uint32_t crc = 0x80000000;
crc32table_be[0][0] = 0;
crc32table_be[0] = 0;
for (i = 1; i < BE_TABLE_SIZE; i <<= 1) {
for (i = 1; i < 256; i <<= 1) {
crc = (crc << 1) ^ ((crc & 0x80000000) ? CRC32_POLY_BE : 0);
for (j = 0; j < i; j++)
crc32table_be[0][i + j] = crc ^ crc32table_be[0][j];
}
for (i = 0; i < BE_TABLE_SIZE; i++) {
crc = crc32table_be[0][i];
for (j = 1; j < BE_TABLE_ROWS; j++) {
crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8);
crc32table_be[j][i] = crc;
}
crc32table_be[i + j] = crc ^ crc32table_be[j];
}
}
static void output_table(uint32_t (*table)[256], int rows, int len, char *trans)
static void output_table(const uint32_t table[256])
{
int i, j;
int i;
for (j = 0 ; j < rows; j++) {
printf("{");
for (i = 0; i < len - 1; i++) {
if (i % ENTRIES_PER_LINE == 0)
printf("\n");
printf("%s(0x%8.8xL), ", trans, table[j][i]);
}
printf("%s(0x%8.8xL)},\n", trans, table[j][len - 1]);
for (i = 0; i < 256; i += 4) {
printf("\t0x%08x, 0x%08x, 0x%08x, 0x%08x,\n",
table[i], table[i + 1], table[i + 2], table[i + 3]);
}
}
@ -109,34 +70,20 @@ int main(int argc, char** argv)
{
printf("/* this file is generated - do not edit */\n\n");
if (CRC_LE_BITS > 1) {
crc32init_le();
printf("static const u32 ____cacheline_aligned "
"crc32table_le[%d][%d] = {",
LE_TABLE_ROWS, LE_TABLE_SIZE);
output_table(crc32table_le, LE_TABLE_ROWS,
LE_TABLE_SIZE, "tole");
printf("};\n");
}
crc32init_le();
printf("static const u32 ____cacheline_aligned crc32table_le[256] = {\n");
output_table(crc32table_le);
printf("};\n");
if (CRC_BE_BITS > 1) {
crc32init_be();
printf("static const u32 ____cacheline_aligned "
"crc32table_be[%d][%d] = {",
BE_TABLE_ROWS, BE_TABLE_SIZE);
output_table(crc32table_be, LE_TABLE_ROWS,
BE_TABLE_SIZE, "tobe");
printf("};\n");
}
if (CRC_LE_BITS > 1) {
crc32cinit_le();
printf("static const u32 ____cacheline_aligned "
"crc32ctable_le[%d][%d] = {",
LE_TABLE_ROWS, LE_TABLE_SIZE);
output_table(crc32ctable_le, LE_TABLE_ROWS,
LE_TABLE_SIZE, "tole");
printf("};\n");
}
crc32init_be();
printf("static const u32 ____cacheline_aligned crc32table_be[256] = {\n");
output_table(crc32table_be);
printf("};\n");
crc32cinit_le();
printf("static const u32 ____cacheline_aligned crc32ctable_le[256] = {\n");
output_table(crc32ctable_le);
printf("};\n");
return 0;
}