842.c

Go to the documentation of this file.

/*
 * Cryptographic API for the 842 compression algorithm.
 *
 * 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.
 *
 * This program is distributed in the hope that 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, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright (C) IBM Corporation, 2011
 *
 * Authors: Robert Jennings <[email protected]>
 *          Seth Jennings <[email protected]>
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/crypto.h>
#include <linux/vmalloc.h>
#include <linux/nx842.h>
#include <linux/lzo.h>
#include <linux/timer.h>

static int nx842_uselzo;

struct nx842_ctx {
    void *nx842_wmem; /* working memory for 842/lzo */
};

enum nx842_crypto_type {
    NX842_CRYPTO_TYPE_842,
    NX842_CRYPTO_TYPE_LZO
};

#define NX842_SENTINEL 0xdeadbeef

struct nx842_crypto_header {
    unsigned int sentinel; /* debug */
    enum nx842_crypto_type type;
};

static int nx842_init(struct crypto_tfm *tfm)
{
    struct nx842_ctx *ctx = crypto_tfm_ctx(tfm);
    int wmemsize;

    wmemsize = max_t(int, nx842_get_workmem_size(), LZO1X_MEM_COMPRESS);
    ctx->nx842_wmem = kmalloc(wmemsize, GFP_NOFS);
    if (!ctx->nx842_wmem)
        return -ENOMEM;

    return 0;
}

static void nx842_exit(struct crypto_tfm *tfm)
{
    struct nx842_ctx *ctx = crypto_tfm_ctx(tfm);

    kfree(ctx->nx842_wmem);
}

static void nx842_reset_uselzo(unsigned long data)
{
    nx842_uselzo = 0;
}

static DEFINE_TIMER(failover_timer, nx842_reset_uselzo, 0, 0);

static int nx842_crypto_compress(struct crypto_tfm *tfm, const u8 *src,
                unsigned int slen, u8 *dst, unsigned int *dlen)
{
    struct nx842_ctx *ctx = crypto_tfm_ctx(tfm);
    struct nx842_crypto_header *hdr;
    unsigned int tmp_len = *dlen;
    size_t lzodlen; /* needed for lzo */
    int err;

    *dlen = 0;
    hdr = (struct nx842_crypto_header *)dst;
    hdr->sentinel = NX842_SENTINEL; /* debug */
    dst += sizeof(struct nx842_crypto_header);
    tmp_len -= sizeof(struct nx842_crypto_header);
    lzodlen = tmp_len;

    if (likely(!nx842_uselzo)) {
        err = nx842_compress(src, slen, dst, &tmp_len, ctx->nx842_wmem);

        if (likely(!err)) {
            hdr->type = NX842_CRYPTO_TYPE_842;
            *dlen = tmp_len + sizeof(struct nx842_crypto_header);
            return 0;
        }

        /* hardware failed */
        nx842_uselzo = 1;

        /* set timer to check for hardware again in 1 second */
        mod_timer(&failover_timer, jiffies + msecs_to_jiffies(1000));
    }

    /* no hardware, use lzo */
    err = lzo1x_1_compress(src, slen, dst, &lzodlen, ctx->nx842_wmem);
    if (err != LZO_E_OK)
        return -EINVAL;

    hdr->type = NX842_CRYPTO_TYPE_LZO;
    *dlen = lzodlen + sizeof(struct nx842_crypto_header);
    return 0;
}

static int nx842_crypto_decompress(struct crypto_tfm *tfm, const u8 *src,
                  unsigned int slen, u8 *dst, unsigned int *dlen)
{
    struct nx842_ctx *ctx = crypto_tfm_ctx(tfm);
    struct nx842_crypto_header *hdr;
    unsigned int tmp_len = *dlen;
    size_t lzodlen; /* needed for lzo */
    int err;

    *dlen = 0;
    hdr = (struct nx842_crypto_header *)src;

    if (unlikely(hdr->sentinel != NX842_SENTINEL))
        return -EINVAL;

    src += sizeof(struct nx842_crypto_header);
    slen -= sizeof(struct nx842_crypto_header);

    if (likely(hdr->type == NX842_CRYPTO_TYPE_842)) {
        err = nx842_decompress(src, slen, dst, &tmp_len,
            ctx->nx842_wmem);
        if (err)
            return -EINVAL;
        *dlen = tmp_len;
    } else if (hdr->type == NX842_CRYPTO_TYPE_LZO) {
        lzodlen = tmp_len;
        err = lzo1x_decompress_safe(src, slen, dst, &lzodlen);
        if (err != LZO_E_OK)
            return -EINVAL;
        *dlen = lzodlen;
    } else
        return -EINVAL;

    return 0;
}

static struct crypto_alg alg = {
    .cra_name       = "842",
    .cra_flags      = CRYPTO_ALG_TYPE_COMPRESS,
    .cra_ctxsize        = sizeof(struct nx842_ctx),
    .cra_module     = THIS_MODULE,
    .cra_init       = nx842_init,
    .cra_exit       = nx842_exit,
    .cra_u          = { .compress = {
    .coa_compress       = nx842_crypto_compress,
    .coa_decompress     = nx842_crypto_decompress } }
};

static int __init nx842_mod_init(void)
{
    del_timer(&failover_timer);
    return crypto_register_alg(&alg);
}

static void __exit nx842_mod_exit(void)
{
    crypto_unregister_alg(&alg);
}

module_init(nx842_mod_init);
module_exit(nx842_mod_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("842 Compression Algorithm");