// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Glue Code for 3-way parallel assembler optimized version of Twofish
 *
 * Copyright (c) 2011 Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
 */

#include <asm/cpu_device_id.h>
#include <crypto/algapi.h>
#include <crypto/twofish.h>
#include <linux/crypto.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/types.h>

#include "twofish.h"
#include "ecb_cbc_helpers.h"

EXPORT_SYMBOL_GPL(__twofish_enc_blk_3way);
EXPORT_SYMBOL_GPL(twofish_dec_blk_3way);

static int twofish_setkey_skcipher(struct crypto_skcipher *tfm,
                                   const u8 *key, unsigned int keylen)
{
        return twofish_setkey(&tfm->base, key, keylen);
}

static inline void twofish_enc_blk_3way(const void *ctx, u8 *dst, const u8 *src)
{
        __twofish_enc_blk_3way(ctx, dst, src, false);
}

void twofish_dec_blk_cbc_3way(const void *ctx, u8 *dst, const u8 *src)
{
        u8 buf[2][TF_BLOCK_SIZE];
        const u8 *s = src;

        if (dst == src)
                s = memcpy(buf, src, sizeof(buf));
        twofish_dec_blk_3way(ctx, dst, src);
        crypto_xor(dst + TF_BLOCK_SIZE, s, sizeof(buf));

}
EXPORT_SYMBOL_GPL(twofish_dec_blk_cbc_3way);

static int ecb_encrypt(struct skcipher_request *req)
{
        ECB_WALK_START(req, TF_BLOCK_SIZE, -1);
        ECB_BLOCK(3, twofish_enc_blk_3way);
        ECB_BLOCK(1, twofish_enc_blk);
        ECB_WALK_END();
}

static int ecb_decrypt(struct skcipher_request *req)
{
        ECB_WALK_START(req, TF_BLOCK_SIZE, -1);
        ECB_BLOCK(3, twofish_dec_blk_3way);
        ECB_BLOCK(1, twofish_dec_blk);
        ECB_WALK_END();
}

static int cbc_encrypt(struct skcipher_request *req)
{
        CBC_WALK_START(req, TF_BLOCK_SIZE, -1);
        CBC_ENC_BLOCK(twofish_enc_blk);
        CBC_WALK_END();
}

static int cbc_decrypt(struct skcipher_request *req)
{
        CBC_WALK_START(req, TF_BLOCK_SIZE, -1);
        CBC_DEC_BLOCK(3, twofish_dec_blk_cbc_3way);
        CBC_DEC_BLOCK(1, twofish_dec_blk);
        CBC_WALK_END();
}

static struct skcipher_alg tf_skciphers[] = {
        {
                .base.cra_name          = "ecb(twofish)",
                .base.cra_driver_name   = "ecb-twofish-3way",
                .base.cra_priority      = 300,
                .base.cra_blocksize     = TF_BLOCK_SIZE,
                .base.cra_ctxsize       = sizeof(struct twofish_ctx),
                .base.cra_module        = THIS_MODULE,
                .min_keysize            = TF_MIN_KEY_SIZE,
                .max_keysize            = TF_MAX_KEY_SIZE,
                .setkey                 = twofish_setkey_skcipher,
                .encrypt                = ecb_encrypt,
                .decrypt                = ecb_decrypt,
        }, {
                .base.cra_name          = "cbc(twofish)",
                .base.cra_driver_name   = "cbc-twofish-3way",
                .base.cra_priority      = 300,
                .base.cra_blocksize     = TF_BLOCK_SIZE,
                .base.cra_ctxsize       = sizeof(struct twofish_ctx),
                .base.cra_module        = THIS_MODULE,
                .min_keysize            = TF_MIN_KEY_SIZE,
                .max_keysize            = TF_MAX_KEY_SIZE,
                .ivsize                 = TF_BLOCK_SIZE,
                .setkey                 = twofish_setkey_skcipher,
                .encrypt                = cbc_encrypt,
                .decrypt                = cbc_decrypt,
        },
};

static bool is_blacklisted_cpu(void)
{
        if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
                return false;

        switch (boot_cpu_data.x86_vfm) {
        case INTEL_ATOM_BONNELL:
        case INTEL_ATOM_BONNELL_MID:
        case INTEL_ATOM_SALTWELL:
                /*
                 * On Atom, twofish-3way is slower than original assembler
                 * implementation. Twofish-3way trades off some performance in
                 * storing blocks in 64bit registers to allow three blocks to
                 * be processed parallel. Parallel operation then allows gaining
                 * more performance than was trade off, on out-of-order CPUs.
                 * However Atom does not benefit from this parallelism and
                 * should be blacklisted.
                 */
                return true;
        }

        if (boot_cpu_data.x86 == 0x0f) {
                /*
                 * On Pentium 4, twofish-3way is slower than original assembler
                 * implementation because excessive uses of 64bit rotate and
                 * left-shifts (which are really slow on P4) needed to store and
                 * handle 128bit block in two 64bit registers.
                 */
                return true;
        }

        return false;
}

static int force;
module_param(force, int, 0);
MODULE_PARM_DESC(force, "Force module load, ignore CPU blacklist");

static int __init twofish_3way_init(void)
{
        if (!force && is_blacklisted_cpu()) {
                printk(KERN_INFO
                        "twofish-x86_64-3way: performance on this CPU "
                        "would be suboptimal: disabling "
                        "twofish-x86_64-3way.\n");
                return -ENODEV;
        }

        return crypto_register_skciphers(tf_skciphers,
                                         ARRAY_SIZE(tf_skciphers));
}

static void __exit twofish_3way_fini(void)
{
        crypto_unregister_skciphers(tf_skciphers, ARRAY_SIZE(tf_skciphers));
}

module_init(twofish_3way_init);
module_exit(twofish_3way_fini);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Twofish Cipher Algorithm, 3-way parallel asm optimized");
MODULE_ALIAS_CRYPTO("twofish");
MODULE_ALIAS_CRYPTO("twofish-asm");