sha1_ssse3_glue.c

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/*
 * Cryptographic API.
 *
 * Glue code for the SHA1 Secure Hash Algorithm assembler implementation using
 * Supplemental SSE3 instructions.
 *
 * This file is based on sha1_generic.c
 *
 * Copyright (c) Alan Smithee.
 * Copyright (c) Andrew McDonald <[email protected]>
 * Copyright (c) Jean-Francois Dive <[email protected]>
 * Copyright (c) Mathias Krause <[email protected]>
 *
 * 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.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <crypto/internal/hash.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/cryptohash.h>
#include <linux/types.h>
#include <crypto/sha.h>
#include <asm/byteorder.h>
#include <asm/i387.h>
#include <asm/xcr.h>
#include <asm/xsave.h>


asmlinkage void sha1_transform_ssse3(u32 *digest, const char *data,
                     unsigned int rounds);
#ifdef CONFIG_AS_AVX
asmlinkage void sha1_transform_avx(u32 *digest, const char *data,
                   unsigned int rounds);
#endif

static asmlinkage void (*sha1_transform_asm)(u32 *, const char *, unsigned int);


static int sha1_ssse3_init(struct shash_desc *desc)
{
    struct sha1_state *sctx = shash_desc_ctx(desc);

    *sctx = (struct sha1_state){
        .state = { SHA1_H0, SHA1_H1, SHA1_H2, SHA1_H3, SHA1_H4 },
    };

    return 0;
}

static int __sha1_ssse3_update(struct shash_desc *desc, const u8 *data,
                   unsigned int len, unsigned int partial)
{
    struct sha1_state *sctx = shash_desc_ctx(desc);
    unsigned int done = 0;

    sctx->count += len;

    if (partial) {
        done = SHA1_BLOCK_SIZE - partial;
        memcpy(sctx->buffer + partial, data, done);
        sha1_transform_asm(sctx->state, sctx->buffer, 1);
    }

    if (len - done >= SHA1_BLOCK_SIZE) {
        const unsigned int rounds = (len - done) / SHA1_BLOCK_SIZE;

        sha1_transform_asm(sctx->state, data + done, rounds);
        done += rounds * SHA1_BLOCK_SIZE;
    }

    memcpy(sctx->buffer, data + done, len - done);

    return 0;
}

static int sha1_ssse3_update(struct shash_desc *desc, const u8 *data,
                 unsigned int len)
{
    struct sha1_state *sctx = shash_desc_ctx(desc);
    unsigned int partial = sctx->count % SHA1_BLOCK_SIZE;
    int res;

    /* Handle the fast case right here */
    if (partial + len < SHA1_BLOCK_SIZE) {
        sctx->count += len;
        memcpy(sctx->buffer + partial, data, len);

        return 0;
    }

    if (!irq_fpu_usable()) {
        res = crypto_sha1_update(desc, data, len);
    } else {
        kernel_fpu_begin();
        res = __sha1_ssse3_update(desc, data, len, partial);
        kernel_fpu_end();
    }

    return res;
}


/* Add padding and return the message digest. */
static int sha1_ssse3_final(struct shash_desc *desc, u8 *out)
{
    struct sha1_state *sctx = shash_desc_ctx(desc);
    unsigned int i, index, padlen;
    __be32 *dst = (__be32 *)out;
    __be64 bits;
    static const u8 padding[SHA1_BLOCK_SIZE] = { 0x80, };

    bits = cpu_to_be64(sctx->count << 3);

    /* Pad out to 56 mod 64 and append length */
    index = sctx->count % SHA1_BLOCK_SIZE;
    padlen = (index < 56) ? (56 - index) : ((SHA1_BLOCK_SIZE+56) - index);
    if (!irq_fpu_usable()) {
        crypto_sha1_update(desc, padding, padlen);
        crypto_sha1_update(desc, (const u8 *)&bits, sizeof(bits));
    } else {
        kernel_fpu_begin();
        /* We need to fill a whole block for __sha1_ssse3_update() */
        if (padlen <= 56) {
            sctx->count += padlen;
            memcpy(sctx->buffer + index, padding, padlen);
        } else {
            __sha1_ssse3_update(desc, padding, padlen, index);
        }
        __sha1_ssse3_update(desc, (const u8 *)&bits, sizeof(bits), 56);
        kernel_fpu_end();
    }

    /* Store state in digest */
    for (i = 0; i < 5; i++)
        dst[i] = cpu_to_be32(sctx->state[i]);

    /* Wipe context */
    memset(sctx, 0, sizeof(*sctx));

    return 0;
}

static int sha1_ssse3_export(struct shash_desc *desc, void *out)
{
    struct sha1_state *sctx = shash_desc_ctx(desc);

    memcpy(out, sctx, sizeof(*sctx));

    return 0;
}

static int sha1_ssse3_import(struct shash_desc *desc, const void *in)
{
    struct sha1_state *sctx = shash_desc_ctx(desc);

    memcpy(sctx, in, sizeof(*sctx));

    return 0;
}

static struct shash_alg alg = {
    .digestsize =   SHA1_DIGEST_SIZE,
    .init       =   sha1_ssse3_init,
    .update     =   sha1_ssse3_update,
    .final      =   sha1_ssse3_final,
    .export     =   sha1_ssse3_export,
    .import     =   sha1_ssse3_import,
    .descsize   =   sizeof(struct sha1_state),
    .statesize  =   sizeof(struct sha1_state),
    .base       =   {
        .cra_name   =   "sha1",
        .cra_driver_name=   "sha1-ssse3",
        .cra_priority   =   150,
        .cra_flags  =   CRYPTO_ALG_TYPE_SHASH,
        .cra_blocksize  =   SHA1_BLOCK_SIZE,
        .cra_module =   THIS_MODULE,
    }
};

#ifdef CONFIG_AS_AVX
static bool __init avx_usable(void)
{
    u64 xcr0;

    if (!cpu_has_avx || !cpu_has_osxsave)
        return false;

    xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
    if ((xcr0 & (XSTATE_SSE | XSTATE_YMM)) != (XSTATE_SSE | XSTATE_YMM)) {
        pr_info("AVX detected but unusable.\n");

        return false;
    }

    return true;
}
#endif

static int __init sha1_ssse3_mod_init(void)
{
    /* test for SSSE3 first */
    if (cpu_has_ssse3)
        sha1_transform_asm = sha1_transform_ssse3;

#ifdef CONFIG_AS_AVX
    /* allow AVX to override SSSE3, it's a little faster */
    if (avx_usable())
        sha1_transform_asm = sha1_transform_avx;
#endif

    if (sha1_transform_asm) {
        pr_info("Using %s optimized SHA-1 implementation\n",
                sha1_transform_asm == sha1_transform_ssse3 ? "SSSE3"
                                                           : "AVX");
        return crypto_register_shash(&alg);
    }
    pr_info("Neither AVX nor SSSE3 is available/usable.\n");

    return -ENODEV;
}

static void __exit sha1_ssse3_mod_fini(void)
{
    crypto_unregister_shash(&alg);
}

module_init(sha1_ssse3_mod_init);
module_exit(sha1_ssse3_mod_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("SHA1 Secure Hash Algorithm, Supplemental SSE3 accelerated");

MODULE_ALIAS("sha1");