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/*
* Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
* CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
* CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
* http://www.intel.com/products/processor/manuals/
* Intel(R) 64 and IA-32 Architectures Software Developer's Manual
* Volume 2A: Instruction Set Reference, A-M
*
* Copyright (c) 2008 Austin Zhang <austin_zhang@linux.intel.com>
* Copyright (c) 2008 Kent Liu <kent.liu@intel.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <crypto/internal/hash.h>
#include <asm/cpufeature.h>
#define CHKSUM_BLOCK_SIZE 1
#define CHKSUM_DIGEST_SIZE 4
#define SCALE_F sizeof(unsigned long)
#ifdef CONFIG_X86_64
#define REX_PRE "0x48, "
#else
#define REX_PRE
#endif
static u32 crc32c_intel_le_hw_byte(u32 crc, unsigned char const *data, size_t length)
{
while (length--) {
__asm__ __volatile__(
".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
:"=S"(crc)
:"0"(crc), "c"(*data)
);
data++;
}
return crc;
}
static u32 __pure crc32c_intel_le_hw(u32 crc, unsigned char const *p, size_t len)
{
unsigned int iquotient = len / SCALE_F;
unsigned int iremainder = len % SCALE_F;
unsigned long *ptmp = (unsigned long *)p;
while (iquotient--) {
__asm__ __volatile__(
".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
:"=S"(crc)
:"0"(crc), "c"(*ptmp)
);
ptmp++;
}
if (iremainder)
crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp,
iremainder);
return crc;
}
/*
* Setting the seed allows arbitrary accumulators and flexible XOR policy
* If your algorithm starts with ~0, then XOR with ~0 before you set
* the seed.
*/
static int crc32c_intel_setkey(struct crypto_ahash *hash, const u8 *key,
unsigned int keylen)
{
u32 *mctx = crypto_ahash_ctx(hash);
if (keylen != sizeof(u32)) {
crypto_ahash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
return -EINVAL;
}
*mctx = le32_to_cpup((__le32 *)key);
return 0;
}
static int crc32c_intel_init(struct ahash_request *req)
{
u32 *mctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
u32 *crcp = ahash_request_ctx(req);
*crcp = *mctx;
return 0;
}
static int crc32c_intel_update(struct ahash_request *req)
{
struct crypto_hash_walk walk;
u32 *crcp = ahash_request_ctx(req);
u32 crc = *crcp;
int nbytes;
for (nbytes = crypto_hash_walk_first(req, &walk); nbytes;
nbytes = crypto_hash_walk_done(&walk, 0))
crc = crc32c_intel_le_hw(crc, walk.data, nbytes);
*crcp = crc;
return 0;
}
static int crc32c_intel_final(struct ahash_request *req)
{
u32 *crcp = ahash_request_ctx(req);
*(__le32 *)req->result = ~cpu_to_le32p(crcp);
return 0;
}
static int crc32c_intel_digest(struct ahash_request *req)
{
struct crypto_hash_walk walk;
u32 *mctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
u32 crc = *mctx;
int nbytes;
for (nbytes = crypto_hash_walk_first(req, &walk); nbytes;
nbytes = crypto_hash_walk_done(&walk, 0))
crc = crc32c_intel_le_hw(crc, walk.data, nbytes);
*(__le32 *)req->result = ~cpu_to_le32(crc);
return 0;
}
static int crc32c_intel_cra_init(struct crypto_tfm *tfm)
{
u32 *key = crypto_tfm_ctx(tfm);
*key = ~0;
tfm->crt_ahash.reqsize = sizeof(u32);
return 0;
}
static struct crypto_alg alg = {
.cra_name = "crc32c",
.cra_driver_name = "crc32c-intel",
.cra_priority = 200,
.cra_flags = CRYPTO_ALG_TYPE_AHASH,
.cra_blocksize = CHKSUM_BLOCK_SIZE,
.cra_alignmask = 3,
.cra_ctxsize = sizeof(u32),
.cra_module = THIS_MODULE,
.cra_list = LIST_HEAD_INIT(alg.cra_list),
.cra_init = crc32c_intel_cra_init,
.cra_type = &crypto_ahash_type,
.cra_u = {
.ahash = {
.digestsize = CHKSUM_DIGEST_SIZE,
.setkey = crc32c_intel_setkey,
.init = crc32c_intel_init,
.update = crc32c_intel_update,
.final = crc32c_intel_final,
.digest = crc32c_intel_digest,
}
}
};
static int __init crc32c_intel_mod_init(void)
{
if (cpu_has_xmm4_2)
return crypto_register_alg(&alg);
else
return -ENODEV;
}
static void __exit crc32c_intel_mod_fini(void)
{
crypto_unregister_alg(&alg);
}
module_init(crc32c_intel_mod_init);
module_exit(crc32c_intel_mod_fini);
MODULE_AUTHOR("Austin Zhang <austin.zhang@intel.com>, Kent Liu <kent.liu@intel.com>");
MODULE_DESCRIPTION("CRC32c (Castagnoli) optimization using Intel Hardware.");
MODULE_LICENSE("GPL");
MODULE_ALIAS("crc32c");
MODULE_ALIAS("crc32c-intel");
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