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");
102