1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * ChaCha20 using the RISC-V vector crypto extensions
  4 *
  5 * Copyright (C) 2023 SiFive, Inc.
  6 * Author: Jerry Shih <jerry.shih@sifive.com>
  7 */
  8
  9#include <asm/simd.h>
 10#include <asm/vector.h>
 11#include <crypto/internal/chacha.h>
 12#include <crypto/internal/skcipher.h>
 13#include <linux/linkage.h>
 14#include <linux/module.h>
 15
 16asmlinkage void chacha20_zvkb(const u32 key[8], const u8 *in, u8 *out,
 17			      size_t len, const u32 iv[4]);
 18
 19static int riscv64_chacha20_crypt(struct skcipher_request *req)
 20{
 21	u32 iv[CHACHA_IV_SIZE / sizeof(u32)];
 22	u8 block_buffer[CHACHA_BLOCK_SIZE];
 23	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 24	const struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
 25	struct skcipher_walk walk;
 26	unsigned int nbytes;
 27	unsigned int tail_bytes;
 28	int err;
 29
 30	iv[0] = get_unaligned_le32(req->iv);
 31	iv[1] = get_unaligned_le32(req->iv + 4);
 32	iv[2] = get_unaligned_le32(req->iv + 8);
 33	iv[3] = get_unaligned_le32(req->iv + 12);
 34
 35	err = skcipher_walk_virt(&walk, req, false);
 36	while (walk.nbytes) {
 37		nbytes = walk.nbytes & ~(CHACHA_BLOCK_SIZE - 1);
 38		tail_bytes = walk.nbytes & (CHACHA_BLOCK_SIZE - 1);
 39		kernel_vector_begin();
 40		if (nbytes) {
 41			chacha20_zvkb(ctx->key, walk.src.virt.addr,
 42				      walk.dst.virt.addr, nbytes, iv);
 43			iv[0] += nbytes / CHACHA_BLOCK_SIZE;
 44		}
 45		if (walk.nbytes == walk.total && tail_bytes > 0) {
 46			memcpy(block_buffer, walk.src.virt.addr + nbytes,
 47			       tail_bytes);
 48			chacha20_zvkb(ctx->key, block_buffer, block_buffer,
 49				      CHACHA_BLOCK_SIZE, iv);
 50			memcpy(walk.dst.virt.addr + nbytes, block_buffer,
 51			       tail_bytes);
 52			tail_bytes = 0;
 53		}
 54		kernel_vector_end();
 55
 56		err = skcipher_walk_done(&walk, tail_bytes);
 57	}
 58
 59	return err;
 60}
 61
 62static struct skcipher_alg riscv64_chacha_alg = {
 63	.setkey = chacha20_setkey,
 64	.encrypt = riscv64_chacha20_crypt,
 65	.decrypt = riscv64_chacha20_crypt,
 66	.min_keysize = CHACHA_KEY_SIZE,
 67	.max_keysize = CHACHA_KEY_SIZE,
 68	.ivsize = CHACHA_IV_SIZE,
 69	.chunksize = CHACHA_BLOCK_SIZE,
 70	.walksize = 4 * CHACHA_BLOCK_SIZE,
 71	.base = {
 72		.cra_blocksize = 1,
 73		.cra_ctxsize = sizeof(struct chacha_ctx),
 74		.cra_priority = 300,
 75		.cra_name = "chacha20",
 76		.cra_driver_name = "chacha20-riscv64-zvkb",
 77		.cra_module = THIS_MODULE,
 78	},
 79};
 80
 81static int __init riscv64_chacha_mod_init(void)
 82{
 83	if (riscv_isa_extension_available(NULL, ZVKB) &&
 84	    riscv_vector_vlen() >= 128)
 85		return crypto_register_skcipher(&riscv64_chacha_alg);
 86
 87	return -ENODEV;
 88}
 89
 90static void __exit riscv64_chacha_mod_exit(void)
 91{
 92	crypto_unregister_skcipher(&riscv64_chacha_alg);
 93}
 94
 95module_init(riscv64_chacha_mod_init);
 96module_exit(riscv64_chacha_mod_exit);
 97
 98MODULE_DESCRIPTION("ChaCha20 (RISC-V accelerated)");
 99MODULE_AUTHOR("Jerry Shih <jerry.shih@sifive.com>");
100MODULE_LICENSE("GPL");
101MODULE_ALIAS_CRYPTO("chacha20");