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/cpufeatures.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 
48 u32 crc32_pclmul_le_16(unsigned char const *buffer, size_t len, u32 crc32);
49 
50 static 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 
82 static 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 
91 static 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 
104 static 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 
114 static 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 */
124 static 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 
131 static 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 
137 static 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 
145 static 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 
152 static 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 
172 static const struct x86_cpu_id crc32pclmul_cpu_id[] = {
173 	X86_FEATURE_MATCH(X86_FEATURE_PCLMULQDQ),
174 	{}
175 };
176 MODULE_DEVICE_TABLE(x86cpu, crc32pclmul_cpu_id);
177 
178 
179 static 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 
189 static void __exit crc32_pclmul_mod_fini(void)
190 {
191 	crypto_unregister_shash(&alg);
192 }
193 
194 module_init(crc32_pclmul_mod_init);
195 module_exit(crc32_pclmul_mod_fini);
196 
197 MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
198 MODULE_LICENSE("GPL");
199 
200 MODULE_ALIAS_CRYPTO("crc32");
201 MODULE_ALIAS_CRYPTO("crc32-pclmul");
202