1/* GPL HEADER START
2 *
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 only,
7 * as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12 * General Public License version 2 for more details (a copy is included
13 * in the LICENSE file that accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License
16 * version 2 along with this program; If not, see http://www.gnu.org/licenses
17 *
18 * Please  visit http://www.xyratex.com/contact if you need additional
19 * information or have any questions.
20 *
21 * GPL HEADER END
22 */
23
24/*
25 * Copyright 2012 Xyratex Technology Limited
26 *
27 * Wrappers for kernel crypto shash api to pclmulqdq crc32 imlementation.
28 */
29#include <linux/init.h>
30#include <linux/module.h>
31#include <linux/string.h>
32#include <linux/kernel.h>
33#include <linux/crc32.h>
34#include <crypto/internal/hash.h>
35
36#include <asm/cpufeature.h>
37#include <asm/cpu_device_id.h>
38#include <asm/fpu/api.h>
39
40#define CHKSUM_BLOCK_SIZE	1
41#define CHKSUM_DIGEST_SIZE	4
42
43#define PCLMUL_MIN_LEN		64L     /* minimum size of buffer
44					 * for crc32_pclmul_le_16 */
45#define SCALE_F			16L	/* size of xmm register */
46#define SCALE_F_MASK		(SCALE_F - 1)
47
48u32 crc32_pclmul_le_16(unsigned char const *buffer, size_t len, u32 crc32);
49
50static u32 __attribute__((pure))
51	crc32_pclmul_le(u32 crc, unsigned char const *p, size_t len)
52{
53	unsigned int iquotient;
54	unsigned int iremainder;
55	unsigned int prealign;
56
57	if (len < PCLMUL_MIN_LEN + SCALE_F_MASK || !irq_fpu_usable())
58		return crc32_le(crc, p, len);
59
60	if ((long)p & SCALE_F_MASK) {
61		/* align p to 16 byte */
62		prealign = SCALE_F - ((long)p & SCALE_F_MASK);
63
64		crc = crc32_le(crc, p, prealign);
65		len -= prealign;
66		p = (unsigned char *)(((unsigned long)p + SCALE_F_MASK) &
67				     ~SCALE_F_MASK);
68	}
69	iquotient = len & (~SCALE_F_MASK);
70	iremainder = len & SCALE_F_MASK;
71
72	kernel_fpu_begin();
73	crc = crc32_pclmul_le_16(p, iquotient, crc);
74	kernel_fpu_end();
75
76	if (iremainder)
77		crc = crc32_le(crc, p + iquotient, iremainder);
78
79	return crc;
80}
81
82static int crc32_pclmul_cra_init(struct crypto_tfm *tfm)
83{
84	u32 *key = crypto_tfm_ctx(tfm);
85
86	*key = 0;
87
88	return 0;
89}
90
91static int crc32_pclmul_setkey(struct crypto_shash *hash, const u8 *key,
92			unsigned int keylen)
93{
94	u32 *mctx = crypto_shash_ctx(hash);
95
96	if (keylen != sizeof(u32)) {
97		crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
98		return -EINVAL;
99	}
100	*mctx = le32_to_cpup((__le32 *)key);
101	return 0;
102}
103
104static int crc32_pclmul_init(struct shash_desc *desc)
105{
106	u32 *mctx = crypto_shash_ctx(desc->tfm);
107	u32 *crcp = shash_desc_ctx(desc);
108
109	*crcp = *mctx;
110
111	return 0;
112}
113
114static int crc32_pclmul_update(struct shash_desc *desc, const u8 *data,
115			       unsigned int len)
116{
117	u32 *crcp = shash_desc_ctx(desc);
118
119	*crcp = crc32_pclmul_le(*crcp, data, len);
120	return 0;
121}
122
123/* No final XOR 0xFFFFFFFF, like crc32_le */
124static int __crc32_pclmul_finup(u32 *crcp, const u8 *data, unsigned int len,
125				u8 *out)
126{
127	*(__le32 *)out = cpu_to_le32(crc32_pclmul_le(*crcp, data, len));
128	return 0;
129}
130
131static int crc32_pclmul_finup(struct shash_desc *desc, const u8 *data,
132			      unsigned int len, u8 *out)
133{
134	return __crc32_pclmul_finup(shash_desc_ctx(desc), data, len, out);
135}
136
137static int crc32_pclmul_final(struct shash_desc *desc, u8 *out)
138{
139	u32 *crcp = shash_desc_ctx(desc);
140
141	*(__le32 *)out = cpu_to_le32p(crcp);
142	return 0;
143}
144
145static int crc32_pclmul_digest(struct shash_desc *desc, const u8 *data,
146			       unsigned int len, u8 *out)
147{
148	return __crc32_pclmul_finup(crypto_shash_ctx(desc->tfm), data, len,
149				    out);
150}
151
152static struct shash_alg alg = {
153	.setkey		= crc32_pclmul_setkey,
154	.init		= crc32_pclmul_init,
155	.update		= crc32_pclmul_update,
156	.final		= crc32_pclmul_final,
157	.finup		= crc32_pclmul_finup,
158	.digest		= crc32_pclmul_digest,
159	.descsize	= sizeof(u32),
160	.digestsize	= CHKSUM_DIGEST_SIZE,
161	.base		= {
162			.cra_name		= "crc32",
163			.cra_driver_name	= "crc32-pclmul",
164			.cra_priority		= 200,
165			.cra_blocksize		= CHKSUM_BLOCK_SIZE,
166			.cra_ctxsize		= sizeof(u32),
167			.cra_module		= THIS_MODULE,
168			.cra_init		= crc32_pclmul_cra_init,
169	}
170};
171
172static const struct x86_cpu_id crc32pclmul_cpu_id[] = {
173	X86_FEATURE_MATCH(X86_FEATURE_PCLMULQDQ),
174	{}
175};
176MODULE_DEVICE_TABLE(x86cpu, crc32pclmul_cpu_id);
177
178
179static int __init crc32_pclmul_mod_init(void)
180{
181
182	if (!x86_match_cpu(crc32pclmul_cpu_id)) {
183		pr_info("PCLMULQDQ-NI instructions are not detected.\n");
184		return -ENODEV;
185	}
186	return crypto_register_shash(&alg);
187}
188
189static void __exit crc32_pclmul_mod_fini(void)
190{
191	crypto_unregister_shash(&alg);
192}
193
194module_init(crc32_pclmul_mod_init);
195module_exit(crc32_pclmul_mod_fini);
196
197MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
198MODULE_LICENSE("GPL");
199
200MODULE_ALIAS_CRYPTO("crc32");
201MODULE_ALIAS_CRYPTO("crc32-pclmul");
202