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// SPDX-License-Identifier: GPL-2.0-only
/*
* ChaCha20 using the RISC-V vector crypto extensions
*
* Copyright (C) 2023 SiFive, Inc.
* Author: Jerry Shih <jerry.shih@sifive.com>
*/
#include <asm/simd.h>
#include <asm/vector.h>
#include <crypto/internal/chacha.h>
#include <crypto/internal/skcipher.h>
#include <linux/linkage.h>
#include <linux/module.h>
asmlinkage void chacha20_zvkb(const u32 key[8], const u8 *in, u8 *out,
size_t len, const u32 iv[4]);
static int riscv64_chacha20_crypt(struct skcipher_request *req)
{
u32 iv[CHACHA_IV_SIZE / sizeof(u32)];
u8 block_buffer[CHACHA_BLOCK_SIZE];
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
const struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
struct skcipher_walk walk;
unsigned int nbytes;
unsigned int tail_bytes;
int err;
iv[0] = get_unaligned_le32(req->iv);
iv[1] = get_unaligned_le32(req->iv + 4);
iv[2] = get_unaligned_le32(req->iv + 8);
iv[3] = get_unaligned_le32(req->iv + 12);
err = skcipher_walk_virt(&walk, req, false);
while (walk.nbytes) {
nbytes = walk.nbytes & ~(CHACHA_BLOCK_SIZE - 1);
tail_bytes = walk.nbytes & (CHACHA_BLOCK_SIZE - 1);
kernel_vector_begin();
if (nbytes) {
chacha20_zvkb(ctx->key, walk.src.virt.addr,
walk.dst.virt.addr, nbytes, iv);
iv[0] += nbytes / CHACHA_BLOCK_SIZE;
}
if (walk.nbytes == walk.total && tail_bytes > 0) {
memcpy(block_buffer, walk.src.virt.addr + nbytes,
tail_bytes);
chacha20_zvkb(ctx->key, block_buffer, block_buffer,
CHACHA_BLOCK_SIZE, iv);
memcpy(walk.dst.virt.addr + nbytes, block_buffer,
tail_bytes);
tail_bytes = 0;
}
kernel_vector_end();
err = skcipher_walk_done(&walk, tail_bytes);
}
return err;
}
static struct skcipher_alg riscv64_chacha_alg = {
.setkey = chacha20_setkey,
.encrypt = riscv64_chacha20_crypt,
.decrypt = riscv64_chacha20_crypt,
.min_keysize = CHACHA_KEY_SIZE,
.max_keysize = CHACHA_KEY_SIZE,
.ivsize = CHACHA_IV_SIZE,
.chunksize = CHACHA_BLOCK_SIZE,
.walksize = 4 * CHACHA_BLOCK_SIZE,
.base = {
.cra_blocksize = 1,
.cra_ctxsize = sizeof(struct chacha_ctx),
.cra_priority = 300,
.cra_name = "chacha20",
.cra_driver_name = "chacha20-riscv64-zvkb",
.cra_module = THIS_MODULE,
},
};
static int __init riscv64_chacha_mod_init(void)
{
if (riscv_isa_extension_available(NULL, ZVKB) &&
riscv_vector_vlen() >= 128)
return crypto_register_skcipher(&riscv64_chacha_alg);
return -ENODEV;
}
static void __exit riscv64_chacha_mod_exit(void)
{
crypto_unregister_skcipher(&riscv64_chacha_alg);
}
module_init(riscv64_chacha_mod_init);
module_exit(riscv64_chacha_mod_exit);
MODULE_DESCRIPTION("ChaCha20 (RISC-V accelerated)");
MODULE_AUTHOR("Jerry Shih <jerry.shih@sifive.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS_CRYPTO("chacha20");
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