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 <linux/cpufeature.h>
8 #include <asm/switch_to.h>
9 
10 #define CHKSUM_BLOCK_SIZE	1
11 #define CHKSUM_DIGEST_SIZE	4
12 
13 #define VMX_ALIGN		16
14 #define VMX_ALIGN_MASK		(VMX_ALIGN-1)
15 
16 #define VECTOR_BREAKPOINT	512
17 
18 u32 __crc32c_vpmsum(u32 crc, unsigned char const *p, size_t len);
19 
20 static u32 crc32c_vpmsum(u32 crc, unsigned char const *p, size_t len)
21 {
22 	unsigned int prealign;
23 	unsigned int tail;
24 
25 	if (len < (VECTOR_BREAKPOINT + VMX_ALIGN) || in_interrupt())
26 		return __crc32c_le(crc, p, len);
27 
28 	if ((unsigned long)p & VMX_ALIGN_MASK) {
29 		prealign = VMX_ALIGN - ((unsigned long)p & VMX_ALIGN_MASK);
30 		crc = __crc32c_le(crc, p, prealign);
31 		len -= prealign;
32 		p += prealign;
33 	}
34 
35 	if (len & ~VMX_ALIGN_MASK) {
36 		preempt_disable();
37 		pagefault_disable();
38 		enable_kernel_altivec();
39 		crc = __crc32c_vpmsum(crc, p, len & ~VMX_ALIGN_MASK);
40 		disable_kernel_altivec();
41 		pagefault_enable();
42 		preempt_enable();
43 	}
44 
45 	tail = len & VMX_ALIGN_MASK;
46 	if (tail) {
47 		p += len & ~VMX_ALIGN_MASK;
48 		crc = __crc32c_le(crc, p, tail);
49 	}
50 
51 	return crc;
52 }
53 
54 static int crc32c_vpmsum_cra_init(struct crypto_tfm *tfm)
55 {
56 	u32 *key = crypto_tfm_ctx(tfm);
57 
58 	*key = ~0;
59 
60 	return 0;
61 }
62 
63 /*
64  * Setting the seed allows arbitrary accumulators and flexible XOR policy
65  * If your algorithm starts with ~0, then XOR with ~0 before you set
66  * the seed.
67  */
68 static int crc32c_vpmsum_setkey(struct crypto_shash *hash, const u8 *key,
69 			       unsigned int keylen)
70 {
71 	u32 *mctx = crypto_shash_ctx(hash);
72 
73 	if (keylen != sizeof(u32)) {
74 		crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
75 		return -EINVAL;
76 	}
77 	*mctx = le32_to_cpup((__le32 *)key);
78 	return 0;
79 }
80 
81 static int crc32c_vpmsum_init(struct shash_desc *desc)
82 {
83 	u32 *mctx = crypto_shash_ctx(desc->tfm);
84 	u32 *crcp = shash_desc_ctx(desc);
85 
86 	*crcp = *mctx;
87 
88 	return 0;
89 }
90 
91 static int crc32c_vpmsum_update(struct shash_desc *desc, const u8 *data,
92 			       unsigned int len)
93 {
94 	u32 *crcp = shash_desc_ctx(desc);
95 
96 	*crcp = crc32c_vpmsum(*crcp, data, len);
97 
98 	return 0;
99 }
100 
101 static int __crc32c_vpmsum_finup(u32 *crcp, const u8 *data, unsigned int len,
102 				u8 *out)
103 {
104 	*(__le32 *)out = ~cpu_to_le32(crc32c_vpmsum(*crcp, data, len));
105 
106 	return 0;
107 }
108 
109 static int crc32c_vpmsum_finup(struct shash_desc *desc, const u8 *data,
110 			      unsigned int len, u8 *out)
111 {
112 	return __crc32c_vpmsum_finup(shash_desc_ctx(desc), data, len, out);
113 }
114 
115 static int crc32c_vpmsum_final(struct shash_desc *desc, u8 *out)
116 {
117 	u32 *crcp = shash_desc_ctx(desc);
118 
119 	*(__le32 *)out = ~cpu_to_le32p(crcp);
120 
121 	return 0;
122 }
123 
124 static int crc32c_vpmsum_digest(struct shash_desc *desc, const u8 *data,
125 			       unsigned int len, u8 *out)
126 {
127 	return __crc32c_vpmsum_finup(crypto_shash_ctx(desc->tfm), data, len,
128 				     out);
129 }
130 
131 static struct shash_alg alg = {
132 	.setkey		= crc32c_vpmsum_setkey,
133 	.init		= crc32c_vpmsum_init,
134 	.update		= crc32c_vpmsum_update,
135 	.final		= crc32c_vpmsum_final,
136 	.finup		= crc32c_vpmsum_finup,
137 	.digest		= crc32c_vpmsum_digest,
138 	.descsize	= sizeof(u32),
139 	.digestsize	= CHKSUM_DIGEST_SIZE,
140 	.base		= {
141 		.cra_name		= "crc32c",
142 		.cra_driver_name	= "crc32c-vpmsum",
143 		.cra_priority		= 200,
144 		.cra_flags		= CRYPTO_ALG_OPTIONAL_KEY,
145 		.cra_blocksize		= CHKSUM_BLOCK_SIZE,
146 		.cra_ctxsize		= sizeof(u32),
147 		.cra_module		= THIS_MODULE,
148 		.cra_init		= crc32c_vpmsum_cra_init,
149 	}
150 };
151 
152 static int __init crc32c_vpmsum_mod_init(void)
153 {
154 	if (!cpu_has_feature(CPU_FTR_ARCH_207S))
155 		return -ENODEV;
156 
157 	return crypto_register_shash(&alg);
158 }
159 
160 static void __exit crc32c_vpmsum_mod_fini(void)
161 {
162 	crypto_unregister_shash(&alg);
163 }
164 
165 module_cpu_feature_match(PPC_MODULE_FEATURE_VEC_CRYPTO, crc32c_vpmsum_mod_init);
166 module_exit(crc32c_vpmsum_mod_fini);
167 
168 MODULE_AUTHOR("Anton Blanchard <anton@samba.org>");
169 MODULE_DESCRIPTION("CRC32C using vector polynomial multiply-sum instructions");
170 MODULE_LICENSE("GPL");
171 MODULE_ALIAS_CRYPTO("crc32c");
172 MODULE_ALIAS_CRYPTO("crc32c-vpmsum");
173