// SPDX-License-Identifier: GPL-2.0-only
/*
 * GHASH using the RISC-V vector crypto extensions
 *
 * Copyright (C) 2023 VRULL GmbH
 * Author: Heiko Stuebner <heiko.stuebner@vrull.eu>
 *
 * Copyright (C) 2023 SiFive, Inc.
 * Author: Jerry Shih <jerry.shih@sifive.com>
 */

#include <asm/simd.h>
#include <asm/vector.h>
#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>
#include <crypto/ghash.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/simd.h>
#include <crypto/utils.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>

asmlinkage void ghash_zvkg(be128 *accumulator, const be128 *key, const u8 *data,
                           size_t len);

struct riscv64_ghash_tfm_ctx {
        be128 key;
};

struct riscv64_ghash_desc_ctx {
        be128 accumulator;
};

static int riscv64_ghash_setkey(struct crypto_shash *tfm, const u8 *key,
                                unsigned int keylen)
{
        struct riscv64_ghash_tfm_ctx *tctx = crypto_shash_ctx(tfm);

        if (keylen != GHASH_BLOCK_SIZE)
                return -EINVAL;

        memcpy(&tctx->key, key, GHASH_BLOCK_SIZE);

        return 0;
}

static int riscv64_ghash_init(struct shash_desc *desc)
{
        struct riscv64_ghash_desc_ctx *dctx = shash_desc_ctx(desc);

        *dctx = (struct riscv64_ghash_desc_ctx){};

        return 0;
}

static inline void
riscv64_ghash_blocks(const struct riscv64_ghash_tfm_ctx *tctx,
                     struct riscv64_ghash_desc_ctx *dctx,
                     const u8 *src, size_t srclen)
{
        /* The srclen is nonzero and a multiple of 16. */
        if (crypto_simd_usable()) {
                kernel_vector_begin();
                ghash_zvkg(&dctx->accumulator, &tctx->key, src, srclen);
                kernel_vector_end();
        } else {
                do {
                        crypto_xor((u8 *)&dctx->accumulator, src,
                                   GHASH_BLOCK_SIZE);
                        gf128mul_lle(&dctx->accumulator, &tctx->key);
                        src += GHASH_BLOCK_SIZE;
                        srclen -= GHASH_BLOCK_SIZE;
                } while (srclen);
        }
}

static int riscv64_ghash_update(struct shash_desc *desc, const u8 *src,
                                unsigned int srclen)
{
        const struct riscv64_ghash_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
        struct riscv64_ghash_desc_ctx *dctx = shash_desc_ctx(desc);

        riscv64_ghash_blocks(tctx, dctx, src,
                             round_down(srclen, GHASH_BLOCK_SIZE));
        return srclen - round_down(srclen, GHASH_BLOCK_SIZE);
}

static int riscv64_ghash_finup(struct shash_desc *desc, const u8 *src,
                               unsigned int len, u8 *out)
{
        const struct riscv64_ghash_tfm_ctx *tctx = crypto_shash_ctx(desc->tfm);
        struct riscv64_ghash_desc_ctx *dctx = shash_desc_ctx(desc);

        if (len) {
                u8 buf[GHASH_BLOCK_SIZE] = {};

                memcpy(buf, src, len);
                riscv64_ghash_blocks(tctx, dctx, buf, GHASH_BLOCK_SIZE);
                memzero_explicit(buf, sizeof(buf));
        }

        memcpy(out, &dctx->accumulator, GHASH_DIGEST_SIZE);
        return 0;
}

static struct shash_alg riscv64_ghash_alg = {
        .init = riscv64_ghash_init,
        .update = riscv64_ghash_update,
        .finup = riscv64_ghash_finup,
        .setkey = riscv64_ghash_setkey,
        .descsize = sizeof(struct riscv64_ghash_desc_ctx),
        .digestsize = GHASH_DIGEST_SIZE,
        .base = {
                .cra_blocksize = GHASH_BLOCK_SIZE,
                .cra_ctxsize = sizeof(struct riscv64_ghash_tfm_ctx),
                .cra_priority = 300,
                .cra_flags = CRYPTO_AHASH_ALG_BLOCK_ONLY,
                .cra_name = "ghash",
                .cra_driver_name = "ghash-riscv64-zvkg",
                .cra_module = THIS_MODULE,
        },
};

static int __init riscv64_ghash_mod_init(void)
{
        if (riscv_isa_extension_available(NULL, ZVKG) &&
            riscv_vector_vlen() >= 128)
                return crypto_register_shash(&riscv64_ghash_alg);

        return -ENODEV;
}

static void __exit riscv64_ghash_mod_exit(void)
{
        crypto_unregister_shash(&riscv64_ghash_alg);
}

module_init(riscv64_ghash_mod_init);
module_exit(riscv64_ghash_mod_exit);

MODULE_DESCRIPTION("GHASH (RISC-V accelerated)");
MODULE_AUTHOR("Heiko Stuebner <heiko.stuebner@vrull.eu>");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CRYPTO("ghash");