crc32c-intel.c

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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 Intel Corporation
 * Authors: Austin Zhang <[email protected]>
 *          Kent Liu <[email protected]>
 *
 * 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>

#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_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;
}

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;
    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 <[email protected]>, Kent Liu <[email protected]>");
MODULE_DESCRIPTION("CRC32c (Castagnoli) optimization using Intel Hardware.");
MODULE_LICENSE("GPL");

MODULE_ALIAS("crc32c");
MODULE_ALIAS("crc32c-intel");