1/*
2 * Poly1305 authenticator algorithm, RFC7539, SIMD glue code
3 *
4 * Copyright (C) 2015 Martin Willi
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 */
11
12#include <crypto/algapi.h>
13#include <crypto/internal/hash.h>
14#include <crypto/poly1305.h>
15#include <linux/crypto.h>
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <asm/fpu/api.h>
19#include <asm/simd.h>
20
21struct poly1305_simd_desc_ctx {
22	struct poly1305_desc_ctx base;
23	/* derived key u set? */
24	bool uset;
25#ifdef CONFIG_AS_AVX2
26	/* derived keys r^3, r^4 set? */
27	bool wset;
28#endif
29	/* derived Poly1305 key r^2 */
30	u32 u[5];
31	/* ... silently appended r^3 and r^4 when using AVX2 */
32};
33
34asmlinkage void poly1305_block_sse2(u32 *h, const u8 *src,
35				    const u32 *r, unsigned int blocks);
36asmlinkage void poly1305_2block_sse2(u32 *h, const u8 *src, const u32 *r,
37				     unsigned int blocks, const u32 *u);
38#ifdef CONFIG_AS_AVX2
39asmlinkage void poly1305_4block_avx2(u32 *h, const u8 *src, const u32 *r,
40				     unsigned int blocks, const u32 *u);
41static bool poly1305_use_avx2;
42#endif
43
44static int poly1305_simd_init(struct shash_desc *desc)
45{
46	struct poly1305_simd_desc_ctx *sctx = shash_desc_ctx(desc);
47
48	sctx->uset = false;
49#ifdef CONFIG_AS_AVX2
50	sctx->wset = false;
51#endif
52
53	return crypto_poly1305_init(desc);
54}
55
56static void poly1305_simd_mult(u32 *a, const u32 *b)
57{
58	u8 m[POLY1305_BLOCK_SIZE];
59
60	memset(m, 0, sizeof(m));
61	/* The poly1305 block function adds a hi-bit to the accumulator which
62	 * we don't need for key multiplication; compensate for it. */
63	a[4] -= 1 << 24;
64	poly1305_block_sse2(a, m, b, 1);
65}
66
67static unsigned int poly1305_simd_blocks(struct poly1305_desc_ctx *dctx,
68					 const u8 *src, unsigned int srclen)
69{
70	struct poly1305_simd_desc_ctx *sctx;
71	unsigned int blocks, datalen;
72
73	BUILD_BUG_ON(offsetof(struct poly1305_simd_desc_ctx, base));
74	sctx = container_of(dctx, struct poly1305_simd_desc_ctx, base);
75
76	if (unlikely(!dctx->sset)) {
77		datalen = crypto_poly1305_setdesckey(dctx, src, srclen);
78		src += srclen - datalen;
79		srclen = datalen;
80	}
81
82#ifdef CONFIG_AS_AVX2
83	if (poly1305_use_avx2 && srclen >= POLY1305_BLOCK_SIZE * 4) {
84		if (unlikely(!sctx->wset)) {
85			if (!sctx->uset) {
86				memcpy(sctx->u, dctx->r, sizeof(sctx->u));
87				poly1305_simd_mult(sctx->u, dctx->r);
88				sctx->uset = true;
89			}
90			memcpy(sctx->u + 5, sctx->u, sizeof(sctx->u));
91			poly1305_simd_mult(sctx->u + 5, dctx->r);
92			memcpy(sctx->u + 10, sctx->u + 5, sizeof(sctx->u));
93			poly1305_simd_mult(sctx->u + 10, dctx->r);
94			sctx->wset = true;
95		}
96		blocks = srclen / (POLY1305_BLOCK_SIZE * 4);
97		poly1305_4block_avx2(dctx->h, src, dctx->r, blocks, sctx->u);
98		src += POLY1305_BLOCK_SIZE * 4 * blocks;
99		srclen -= POLY1305_BLOCK_SIZE * 4 * blocks;
100	}
101#endif
102	if (likely(srclen >= POLY1305_BLOCK_SIZE * 2)) {
103		if (unlikely(!sctx->uset)) {
104			memcpy(sctx->u, dctx->r, sizeof(sctx->u));
105			poly1305_simd_mult(sctx->u, dctx->r);
106			sctx->uset = true;
107		}
108		blocks = srclen / (POLY1305_BLOCK_SIZE * 2);
109		poly1305_2block_sse2(dctx->h, src, dctx->r, blocks, sctx->u);
110		src += POLY1305_BLOCK_SIZE * 2 * blocks;
111		srclen -= POLY1305_BLOCK_SIZE * 2 * blocks;
112	}
113	if (srclen >= POLY1305_BLOCK_SIZE) {
114		poly1305_block_sse2(dctx->h, src, dctx->r, 1);
115		srclen -= POLY1305_BLOCK_SIZE;
116	}
117	return srclen;
118}
119
120static int poly1305_simd_update(struct shash_desc *desc,
121				const u8 *src, unsigned int srclen)
122{
123	struct poly1305_desc_ctx *dctx = shash_desc_ctx(desc);
124	unsigned int bytes;
125
126	/* kernel_fpu_begin/end is costly, use fallback for small updates */
127	if (srclen <= 288 || !may_use_simd())
128		return crypto_poly1305_update(desc, src, srclen);
129
130	kernel_fpu_begin();
131
132	if (unlikely(dctx->buflen)) {
133		bytes = min(srclen, POLY1305_BLOCK_SIZE - dctx->buflen);
134		memcpy(dctx->buf + dctx->buflen, src, bytes);
135		src += bytes;
136		srclen -= bytes;
137		dctx->buflen += bytes;
138
139		if (dctx->buflen == POLY1305_BLOCK_SIZE) {
140			poly1305_simd_blocks(dctx, dctx->buf,
141					     POLY1305_BLOCK_SIZE);
142			dctx->buflen = 0;
143		}
144	}
145
146	if (likely(srclen >= POLY1305_BLOCK_SIZE)) {
147		bytes = poly1305_simd_blocks(dctx, src, srclen);
148		src += srclen - bytes;
149		srclen = bytes;
150	}
151
152	kernel_fpu_end();
153
154	if (unlikely(srclen)) {
155		dctx->buflen = srclen;
156		memcpy(dctx->buf, src, srclen);
157	}
158
159	return 0;
160}
161
162static struct shash_alg alg = {
163	.digestsize	= POLY1305_DIGEST_SIZE,
164	.init		= poly1305_simd_init,
165	.update		= poly1305_simd_update,
166	.final		= crypto_poly1305_final,
167	.setkey		= crypto_poly1305_setkey,
168	.descsize	= sizeof(struct poly1305_simd_desc_ctx),
169	.base		= {
170		.cra_name		= "poly1305",
171		.cra_driver_name	= "poly1305-simd",
172		.cra_priority		= 300,
173		.cra_flags		= CRYPTO_ALG_TYPE_SHASH,
174		.cra_alignmask		= sizeof(u32) - 1,
175		.cra_blocksize		= POLY1305_BLOCK_SIZE,
176		.cra_module		= THIS_MODULE,
177	},
178};
179
180static int __init poly1305_simd_mod_init(void)
181{
182	if (!cpu_has_xmm2)
183		return -ENODEV;
184
185#ifdef CONFIG_AS_AVX2
186	poly1305_use_avx2 = cpu_has_avx && cpu_has_avx2 &&
187			    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL);
188	alg.descsize = sizeof(struct poly1305_simd_desc_ctx);
189	if (poly1305_use_avx2)
190		alg.descsize += 10 * sizeof(u32);
191#endif
192	return crypto_register_shash(&alg);
193}
194
195static void __exit poly1305_simd_mod_exit(void)
196{
197	crypto_unregister_shash(&alg);
198}
199
200module_init(poly1305_simd_mod_init);
201module_exit(poly1305_simd_mod_exit);
202
203MODULE_LICENSE("GPL");
204MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
205MODULE_DESCRIPTION("Poly1305 authenticator");
206MODULE_ALIAS_CRYPTO("poly1305");
207MODULE_ALIAS_CRYPTO("poly1305-simd");
208