root/arch/x86/crypto/crc32c-intel.c

DEFINITIONS

1. crc32c_intel_le_hw_byte
2. crc32c_intel_le_hw
3. crc32c_intel_setkey
4. crc32c_intel_init
5. crc32c_intel_update
6. crc32c_intel_final
7. crc32c_intel_digest
8. crc32c_intel_cra_init
9. crc32c_intel_mod_init
10. crc32c_intel_mod_fini

/*
 * 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");