1 #include <linux/crc32.h>
2 #include <crypto/internal/hash.h>
3 #include <linux/init.h>
4 #include <linux/module.h>
5 #include <linux/string.h>
6 #include <linux/kernel.h>
7 #include <asm/switch_to.h>
8 
9 #define CHKSUM_BLOCK_SIZE	1
10 #define CHKSUM_DIGEST_SIZE	4
11 
12 #define VMX_ALIGN		16
13 #define VMX_ALIGN_MASK		(VMX_ALIGN-1)
14 
15 #define VECTOR_BREAKPOINT	512
16 
17 u32 __crc32c_vpmsum(u32 crc, unsigned char const *p, size_t len);
18 
19 static u32 crc32c_vpmsum(u32 crc, unsigned char const *p, size_t len)
20 {
21 	unsigned int prealign;
22 	unsigned int tail;
23 
24 	if (len < (VECTOR_BREAKPOINT + VMX_ALIGN) || in_interrupt())
25 		return __crc32c_le(crc, p, len);
26 
27 	if ((unsigned long)p & VMX_ALIGN_MASK) {
28 		prealign = VMX_ALIGN - ((unsigned long)p & VMX_ALIGN_MASK);
29 		crc = __crc32c_le(crc, p, prealign);
30 		len -= prealign;
31 		p += prealign;
32 	}
33 
34 	if (len & ~VMX_ALIGN_MASK) {
35 		pagefault_disable();
36 		enable_kernel_altivec();
37 		crc = __crc32c_vpmsum(crc, p, len & ~VMX_ALIGN_MASK);
38 		pagefault_enable();
39 	}
40 
41 	tail = len & VMX_ALIGN_MASK;
42 	if (tail) {
43 		p += len & ~VMX_ALIGN_MASK;
44 		crc = __crc32c_le(crc, p, tail);
45 	}
46 
47 	return crc;
48 }
49 
50 static int crc32c_vpmsum_cra_init(struct crypto_tfm *tfm)
51 {
52 	u32 *key = crypto_tfm_ctx(tfm);
53 
54 	*key = 0;
55 
56 	return 0;
57 }
58 
59 /*
60  * Setting the seed allows arbitrary accumulators and flexible XOR policy
61  * If your algorithm starts with ~0, then XOR with ~0 before you set
62  * the seed.
63  */
64 static int crc32c_vpmsum_setkey(struct crypto_shash *hash, const u8 *key,
65 			       unsigned int keylen)
66 {
67 	u32 *mctx = crypto_shash_ctx(hash);
68 
69 	if (keylen != sizeof(u32)) {
70 		crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
71 		return -EINVAL;
72 	}
73 	*mctx = le32_to_cpup((__le32 *)key);
74 	return 0;
75 }
76 
77 static int crc32c_vpmsum_init(struct shash_desc *desc)
78 {
79 	u32 *mctx = crypto_shash_ctx(desc->tfm);
80 	u32 *crcp = shash_desc_ctx(desc);
81 
82 	*crcp = *mctx;
83 
84 	return 0;
85 }
86 
87 static int crc32c_vpmsum_update(struct shash_desc *desc, const u8 *data,
88 			       unsigned int len)
89 {
90 	u32 *crcp = shash_desc_ctx(desc);
91 
92 	*crcp = crc32c_vpmsum(*crcp, data, len);
93 
94 	return 0;
95 }
96 
97 static int __crc32c_vpmsum_finup(u32 *crcp, const u8 *data, unsigned int len,
98 				u8 *out)
99 {
100 	*(__le32 *)out = ~cpu_to_le32(crc32c_vpmsum(*crcp, data, len));
101 
102 	return 0;
103 }
104 
105 static int crc32c_vpmsum_finup(struct shash_desc *desc, const u8 *data,
106 			      unsigned int len, u8 *out)
107 {
108 	return __crc32c_vpmsum_finup(shash_desc_ctx(desc), data, len, out);
109 }
110 
111 static int crc32c_vpmsum_final(struct shash_desc *desc, u8 *out)
112 {
113 	u32 *crcp = shash_desc_ctx(desc);
114 
115 	*(__le32 *)out = ~cpu_to_le32p(crcp);
116 
117 	return 0;
118 }
119 
120 static int crc32c_vpmsum_digest(struct shash_desc *desc, const u8 *data,
121 			       unsigned int len, u8 *out)
122 {
123 	return __crc32c_vpmsum_finup(crypto_shash_ctx(desc->tfm), data, len,
124 				     out);
125 }
126 
127 static struct shash_alg alg = {
128 	.setkey		= crc32c_vpmsum_setkey,
129 	.init		= crc32c_vpmsum_init,
130 	.update		= crc32c_vpmsum_update,
131 	.final		= crc32c_vpmsum_final,
132 	.finup		= crc32c_vpmsum_finup,
133 	.digest		= crc32c_vpmsum_digest,
134 	.descsize	= sizeof(u32),
135 	.digestsize	= CHKSUM_DIGEST_SIZE,
136 	.base		= {
137 		.cra_name		= "crc32c",
138 		.cra_driver_name	= "crc32c-vpmsum",
139 		.cra_priority		= 200,
140 		.cra_blocksize		= CHKSUM_BLOCK_SIZE,
141 		.cra_ctxsize		= sizeof(u32),
142 		.cra_module		= THIS_MODULE,
143 		.cra_init		= crc32c_vpmsum_cra_init,
144 	}
145 };
146 
147 static int __init crc32c_vpmsum_mod_init(void)
148 {
149 	if (!cpu_has_feature(CPU_FTR_ARCH_207S))
150 		return -ENODEV;
151 
152 	return crypto_register_shash(&alg);
153 }
154 
155 static void __exit crc32c_vpmsum_mod_fini(void)
156 {
157 	crypto_unregister_shash(&alg);
158 }
159 
160 module_init(crc32c_vpmsum_mod_init);
161 module_exit(crc32c_vpmsum_mod_fini);
162 
163 MODULE_AUTHOR("Anton Blanchard <anton@samba.org>");
164 MODULE_DESCRIPTION("CRC32C using vector polynomial multiply-sum instructions");
165 MODULE_LICENSE("GPL");
166 MODULE_ALIAS_CRYPTO("crc32c");
167 MODULE_ALIAS_CRYPTO("crc32c-vpmsum");
168