/*
* 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 Intel Corporation
* Authors: Austin Zhang <austin_zhang@linux.intel.com>
* Kent Liu <kent.liu@intel.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
#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>
#include <asm/cpu_device_id.h>
#include <asm/i387.h>
#include <asm/fpu-internal.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
#ifdef CONFIG_X86_64
/*
* use carryless multiply version of crc32c when buffer
* size is >= 512 (when eager fpu is enabled) or
* >= 1024 (when eager fpu is disabled) to account
* for fpu state save/restore overhead.
*/
#define CRC32C_PCL_BREAKEVEN_EAGERFPU 512
#define CRC32C_PCL_BREAKEVEN_NOEAGERFPU 1024
asmlinkage unsigned int crc_pcl(const u8 *buffer, int len,
unsigned int crc_init);
static int crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_EAGERFPU;
#if defined(X86_FEATURE_EAGER_FPU)
#define set_pcl_breakeven_point() \
do { \
if (!use_eager_fpu()) \
crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_NOEAGERFPU; \
} while (0)
#else
#define set_pcl_breakeven_point() \
(crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_NOEAGERFPU)
#endif
#endif /* CONFIG_X86_64 */
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_shash *hash, const u8 *key,
unsigned int keylen)
{
u32 *mctx = crypto_shash_ctx(hash);
if (keylen != sizeof(u32)) {
crypto_shash_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 shash_desc *desc)
{
u32 *mctx = crypto_shash_ctx(desc->tfm);
u32 *crcp = shash_desc_ctx(desc);
*crcp = *mctx;
return 0;
}
static int crc32c_intel_update(struct shash_desc *desc, const u8 *data,
unsigned int len)
{
u32 *crcp = shash_desc_ctx(desc);
*crcp = crc32c_intel_le_hw(*crcp, data, len);
return 0;
}
static int __crc32c_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
u8 *out)
{
*(__le32 *)out = ~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
return 0;
}
static int crc32c_intel_finup(struct shash_desc *desc, const u8 *data,
unsigned int len, u8 *out)
{
return __crc32c_intel_finup(shash_desc_ctx(desc), data, len, out);
}
static int crc32c_intel_final(struct shash_desc *desc, u8 *out)
{
u32 *crcp = shash_desc_ctx(desc);
*(__le32 *)out = ~cpu_to_le32p(crcp);
return 0;
}
static int crc32c_intel_digest(struct shash_desc *desc, const u8 *data,
unsigned int len, u8 *out)
{
return __crc32c_intel_finup(crypto_shash_ctx(desc->tfm), data, len,
out);
}
static int crc32c_intel_cra_init(struct crypto_tfm *tfm)
{
u32 *key = crypto_tfm_ctx(tfm);
*key = ~0;
return 0;
}
#ifdef CONFIG_X86_64
static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data,
unsigned int len)
{
u32 *crcp = shash_desc_ctx(desc);
/*
* use faster PCL version if datasize is large enough to
* overcome kernel fpu state save/restore overhead
*/
if (len >= crc32c_pcl_breakeven && irq_fpu_usable()) {
kernel_fpu_begin();
*crcp = crc_pcl(data, len, *crcp);
kernel_fpu_end();
} else
*crcp = crc32c_intel_le_hw(*crcp, data, len);
return 0;
}
static int __crc32c_pcl_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
u8 *out)
{
if (len >= crc32c_pcl_breakeven && irq_fpu_usable()) {
kernel_fpu_begin();
*(__le32 *)out = ~cpu_to_le32(crc_pcl(data, len, *crcp));
kernel_fpu_end();
} else
*(__le32 *)out =
~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
return 0;
}
static int crc32c_pcl_intel_finup(struct shash_desc *desc, const u8 *data,
unsigned int len, u8 *out)
{
return __crc32c_pcl_intel_finup(shash_desc_ctx(desc), data, len, out);
}
static int crc32c_pcl_intel_digest(struct shash_desc *desc, const u8 *data,
unsigned int len, u8 *out)
{
return __crc32c_pcl_intel_finup(crypto_shash_ctx(desc->tfm), data, len,
out);
}
#endif /* CONFIG_X86_64 */
static struct shash_alg alg = {
.setkey = crc32c_intel_setkey,
.init = crc32c_intel_init,
.update = crc32c_intel_update,
.final = crc32c_intel_final,
.finup = crc32c_intel_finup,
.digest = crc32c_intel_digest,
.descsize = sizeof(u32),
.digestsize = CHKSUM_DIGEST_SIZE,
.base = {
.cra_name = "crc32c",
.cra_driver_name = "crc32c-intel",
.cra_priority = 200,
.cra_blocksize = CHKSUM_BLOCK_SIZE,
.cra_ctxsize = sizeof(u32),
.cra_module = THIS_MODULE,
.cra_init = crc32c_intel_cra_init,
}
};
static const struct x86_cpu_id crc32c_cpu_id[] = {
X86_FEATURE_MATCH(X86_FEATURE_XMM4_2),
{}
};
MODULE_DEVICE_TABLE(x86cpu, crc32c_cpu_id);
static int __init crc32c_intel_mod_init(void)
{
if (!x86_match_cpu(crc32c_cpu_id))
return -ENODEV;
#ifdef CONFIG_X86_64
if (cpu_has_pclmulqdq) {
alg.update = crc32c_pcl_intel_update;
alg.finup = crc32c_pcl_intel_finup;
alg.digest = crc32c_pcl_intel_digest;
set_pcl_breakeven_point();
}
#endif
return crypto_register_shash(&alg);
}
static void __exit crc32c_intel_mod_fini(void)
{
crypto_unregister_shash(&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");