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,
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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).
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15  * You should have received a copy of the GNU General Public License
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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 implementation.
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 #include <crypto/internal/simd.h>
36 
37 #include <asm/cpufeatures.h>
38 #include <asm/cpu_device_id.h>
39 #include <asm/simd.h>
40 
41 #define CHKSUM_BLOCK_SIZE	1
42 #define CHKSUM_DIGEST_SIZE	4
43 
44 #define PCLMUL_MIN_LEN		64L     /* minimum size of buffer
45 					 * for crc32_pclmul_le_16 */
46 #define SCALE_F			16L	/* size of xmm register */
47 #define SCALE_F_MASK		(SCALE_F - 1)
48 
49 u32 crc32_pclmul_le_16(unsigned char const *buffer, size_t len, u32 crc32);
50 
51 static u32 __attribute__((pure))
52 	crc32_pclmul_le(u32 crc, unsigned char const *p, size_t len)
53 {
54 	unsigned int iquotient;
55 	unsigned int iremainder;
56 	unsigned int prealign;
57 
58 	if (len < PCLMUL_MIN_LEN + SCALE_F_MASK || !crypto_simd_usable())
59 		return crc32_le(crc, p, len);
60 
61 	if ((long)p & SCALE_F_MASK) {
62 		/* align p to 16 byte */
63 		prealign = SCALE_F - ((long)p & SCALE_F_MASK);
64 
65 		crc = crc32_le(crc, p, prealign);
66 		len -= prealign;
67 		p = (unsigned char *)(((unsigned long)p + SCALE_F_MASK) &
68 				     ~SCALE_F_MASK);
69 	}
70 	iquotient = len & (~SCALE_F_MASK);
71 	iremainder = len & SCALE_F_MASK;
72 
73 	kernel_fpu_begin();
74 	crc = crc32_pclmul_le_16(p, iquotient, crc);
75 	kernel_fpu_end();
76 
77 	if (iremainder)
78 		crc = crc32_le(crc, p + iquotient, iremainder);
79 
80 	return crc;
81 }
82 
83 static int crc32_pclmul_cra_init(struct crypto_tfm *tfm)
84 {
85 	u32 *key = crypto_tfm_ctx(tfm);
86 
87 	*key = 0;
88 
89 	return 0;
90 }
91 
92 static int crc32_pclmul_setkey(struct crypto_shash *hash, const u8 *key,
93 			unsigned int keylen)
94 {
95 	u32 *mctx = crypto_shash_ctx(hash);
96 
97 	if (keylen != sizeof(u32))
98 		return -EINVAL;
99 	*mctx = le32_to_cpup((__le32 *)key);
100 	return 0;
101 }
102 
103 static int crc32_pclmul_init(struct shash_desc *desc)
104 {
105 	u32 *mctx = crypto_shash_ctx(desc->tfm);
106 	u32 *crcp = shash_desc_ctx(desc);
107 
108 	*crcp = *mctx;
109 
110 	return 0;
111 }
112 
113 static int crc32_pclmul_update(struct shash_desc *desc, const u8 *data,
114 			       unsigned int len)
115 {
116 	u32 *crcp = shash_desc_ctx(desc);
117 
118 	*crcp = crc32_pclmul_le(*crcp, data, len);
119 	return 0;
120 }
121 
122 /* No final XOR 0xFFFFFFFF, like crc32_le */
123 static int __crc32_pclmul_finup(u32 *crcp, const u8 *data, unsigned int len,
124 				u8 *out)
125 {
126 	*(__le32 *)out = cpu_to_le32(crc32_pclmul_le(*crcp, data, len));
127 	return 0;
128 }
129 
130 static int crc32_pclmul_finup(struct shash_desc *desc, const u8 *data,
131 			      unsigned int len, u8 *out)
132 {
133 	return __crc32_pclmul_finup(shash_desc_ctx(desc), data, len, out);
134 }
135 
136 static int crc32_pclmul_final(struct shash_desc *desc, u8 *out)
137 {
138 	u32 *crcp = shash_desc_ctx(desc);
139 
140 	*(__le32 *)out = cpu_to_le32p(crcp);
141 	return 0;
142 }
143 
144 static int crc32_pclmul_digest(struct shash_desc *desc, const u8 *data,
145 			       unsigned int len, u8 *out)
146 {
147 	return __crc32_pclmul_finup(crypto_shash_ctx(desc->tfm), data, len,
148 				    out);
149 }
150 
151 static struct shash_alg alg = {
152 	.setkey		= crc32_pclmul_setkey,
153 	.init		= crc32_pclmul_init,
154 	.update		= crc32_pclmul_update,
155 	.final		= crc32_pclmul_final,
156 	.finup		= crc32_pclmul_finup,
157 	.digest		= crc32_pclmul_digest,
158 	.descsize	= sizeof(u32),
159 	.digestsize	= CHKSUM_DIGEST_SIZE,
160 	.base		= {
161 			.cra_name		= "crc32",
162 			.cra_driver_name	= "crc32-pclmul",
163 			.cra_priority		= 200,
164 			.cra_flags		= CRYPTO_ALG_OPTIONAL_KEY,
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_MATCH_FEATURE(X86_FEATURE_PCLMULQDQ, NULL),
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