1 /*
2  * Glue code for SHA-256 implementation for SPE instructions (PPC)
3  *
4  * Based on generic implementation. The assembler module takes care
5  * about the SPE registers so it can run from interrupt context.
6  *
7  * Copyright (c) 2015 Markus Stockhausen <stockhausen@collogia.de>
8  *
9  * This program is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU General Public License as published by the Free
11  * Software Foundation; either version 2 of the License, or (at your option)
12  * any later version.
13  *
14  */
15 
16 #include <crypto/internal/hash.h>
17 #include <linux/init.h>
18 #include <linux/module.h>
19 #include <linux/mm.h>
20 #include <linux/cryptohash.h>
21 #include <linux/types.h>
22 #include <crypto/sha.h>
23 #include <asm/byteorder.h>
24 #include <asm/switch_to.h>
25 #include <linux/hardirq.h>
26 
27 /*
28  * MAX_BYTES defines the number of bytes that are allowed to be processed
29  * between preempt_disable() and preempt_enable(). SHA256 takes ~2,000
30  * operations per 64 bytes. e500 cores can issue two arithmetic instructions
31  * per clock cycle using one 32/64 bit unit (SU1) and one 32 bit unit (SU2).
32  * Thus 1KB of input data will need an estimated maximum of 18,000 cycles.
33  * Headroom for cache misses included. Even with the low end model clocked
34  * at 667 MHz this equals to a critical time window of less than 27us.
35  *
36  */
37 #define MAX_BYTES 1024
38 
39 extern void ppc_spe_sha256_transform(u32 *state, const u8 *src, u32 blocks);
40 
41 static void spe_begin(void)
42 {
43 	/* We just start SPE operations and will save SPE registers later. */
44 	preempt_disable();
45 	enable_kernel_spe();
46 }
47 
48 static void spe_end(void)
49 {
50 	disable_kernel_spe();
51 	/* reenable preemption */
52 	preempt_enable();
53 }
54 
55 static inline void ppc_sha256_clear_context(struct sha256_state *sctx)
56 {
57 	int count = sizeof(struct sha256_state) >> 2;
58 	u32 *ptr = (u32 *)sctx;
59 
60 	/* make sure we can clear the fast way */
61 	BUILD_BUG_ON(sizeof(struct sha256_state) % 4);
62 	do { *ptr++ = 0; } while (--count);
63 }
64 
65 static int ppc_spe_sha256_init(struct shash_desc *desc)
66 {
67 	struct sha256_state *sctx = shash_desc_ctx(desc);
68 
69 	sctx->state[0] = SHA256_H0;
70 	sctx->state[1] = SHA256_H1;
71 	sctx->state[2] = SHA256_H2;
72 	sctx->state[3] = SHA256_H3;
73 	sctx->state[4] = SHA256_H4;
74 	sctx->state[5] = SHA256_H5;
75 	sctx->state[6] = SHA256_H6;
76 	sctx->state[7] = SHA256_H7;
77 	sctx->count = 0;
78 
79 	return 0;
80 }
81 
82 static int ppc_spe_sha224_init(struct shash_desc *desc)
83 {
84 	struct sha256_state *sctx = shash_desc_ctx(desc);
85 
86 	sctx->state[0] = SHA224_H0;
87 	sctx->state[1] = SHA224_H1;
88 	sctx->state[2] = SHA224_H2;
89 	sctx->state[3] = SHA224_H3;
90 	sctx->state[4] = SHA224_H4;
91 	sctx->state[5] = SHA224_H5;
92 	sctx->state[6] = SHA224_H6;
93 	sctx->state[7] = SHA224_H7;
94 	sctx->count = 0;
95 
96 	return 0;
97 }
98 
99 static int ppc_spe_sha256_update(struct shash_desc *desc, const u8 *data,
100 			unsigned int len)
101 {
102 	struct sha256_state *sctx = shash_desc_ctx(desc);
103 	const unsigned int offset = sctx->count & 0x3f;
104 	const unsigned int avail = 64 - offset;
105 	unsigned int bytes;
106 	const u8 *src = data;
107 
108 	if (avail > len) {
109 		sctx->count += len;
110 		memcpy((char *)sctx->buf + offset, src, len);
111 		return 0;
112 	}
113 
114 	sctx->count += len;
115 
116 	if (offset) {
117 		memcpy((char *)sctx->buf + offset, src, avail);
118 
119 		spe_begin();
120 		ppc_spe_sha256_transform(sctx->state, (const u8 *)sctx->buf, 1);
121 		spe_end();
122 
123 		len -= avail;
124 		src += avail;
125 	}
126 
127 	while (len > 63) {
128 		/* cut input data into smaller blocks */
129 		bytes = (len > MAX_BYTES) ? MAX_BYTES : len;
130 		bytes = bytes & ~0x3f;
131 
132 		spe_begin();
133 		ppc_spe_sha256_transform(sctx->state, src, bytes >> 6);
134 		spe_end();
135 
136 		src += bytes;
137 		len -= bytes;
138 	};
139 
140 	memcpy((char *)sctx->buf, src, len);
141 	return 0;
142 }
143 
144 static int ppc_spe_sha256_final(struct shash_desc *desc, u8 *out)
145 {
146 	struct sha256_state *sctx = shash_desc_ctx(desc);
147 	const unsigned int offset = sctx->count & 0x3f;
148 	char *p = (char *)sctx->buf + offset;
149 	int padlen;
150 	__be64 *pbits = (__be64 *)(((char *)&sctx->buf) + 56);
151 	__be32 *dst = (__be32 *)out;
152 
153 	padlen = 55 - offset;
154 	*p++ = 0x80;
155 
156 	spe_begin();
157 
158 	if (padlen < 0) {
159 		memset(p, 0x00, padlen + sizeof (u64));
160 		ppc_spe_sha256_transform(sctx->state, sctx->buf, 1);
161 		p = (char *)sctx->buf;
162 		padlen = 56;
163 	}
164 
165 	memset(p, 0, padlen);
166 	*pbits = cpu_to_be64(sctx->count << 3);
167 	ppc_spe_sha256_transform(sctx->state, sctx->buf, 1);
168 
169 	spe_end();
170 
171 	dst[0] = cpu_to_be32(sctx->state[0]);
172 	dst[1] = cpu_to_be32(sctx->state[1]);
173 	dst[2] = cpu_to_be32(sctx->state[2]);
174 	dst[3] = cpu_to_be32(sctx->state[3]);
175 	dst[4] = cpu_to_be32(sctx->state[4]);
176 	dst[5] = cpu_to_be32(sctx->state[5]);
177 	dst[6] = cpu_to_be32(sctx->state[6]);
178 	dst[7] = cpu_to_be32(sctx->state[7]);
179 
180 	ppc_sha256_clear_context(sctx);
181 	return 0;
182 }
183 
184 static int ppc_spe_sha224_final(struct shash_desc *desc, u8 *out)
185 {
186 	u32 D[SHA256_DIGEST_SIZE >> 2];
187 	__be32 *dst = (__be32 *)out;
188 
189 	ppc_spe_sha256_final(desc, (u8 *)D);
190 
191 	/* avoid bytewise memcpy */
192 	dst[0] = D[0];
193 	dst[1] = D[1];
194 	dst[2] = D[2];
195 	dst[3] = D[3];
196 	dst[4] = D[4];
197 	dst[5] = D[5];
198 	dst[6] = D[6];
199 
200 	/* clear sensitive data */
201 	memzero_explicit(D, SHA256_DIGEST_SIZE);
202 	return 0;
203 }
204 
205 static int ppc_spe_sha256_export(struct shash_desc *desc, void *out)
206 {
207 	struct sha256_state *sctx = shash_desc_ctx(desc);
208 
209 	memcpy(out, sctx, sizeof(*sctx));
210 	return 0;
211 }
212 
213 static int ppc_spe_sha256_import(struct shash_desc *desc, const void *in)
214 {
215 	struct sha256_state *sctx = shash_desc_ctx(desc);
216 
217 	memcpy(sctx, in, sizeof(*sctx));
218 	return 0;
219 }
220 
221 static struct shash_alg algs[2] = { {
222 	.digestsize	=	SHA256_DIGEST_SIZE,
223 	.init		=	ppc_spe_sha256_init,
224 	.update		=	ppc_spe_sha256_update,
225 	.final		=	ppc_spe_sha256_final,
226 	.export		=	ppc_spe_sha256_export,
227 	.import		=	ppc_spe_sha256_import,
228 	.descsize	=	sizeof(struct sha256_state),
229 	.statesize	=	sizeof(struct sha256_state),
230 	.base		=	{
231 		.cra_name	=	"sha256",
232 		.cra_driver_name=	"sha256-ppc-spe",
233 		.cra_priority	=	300,
234 		.cra_flags	=	CRYPTO_ALG_TYPE_SHASH,
235 		.cra_blocksize	=	SHA256_BLOCK_SIZE,
236 		.cra_module	=	THIS_MODULE,
237 	}
238 }, {
239 	.digestsize	=	SHA224_DIGEST_SIZE,
240 	.init		=	ppc_spe_sha224_init,
241 	.update		=	ppc_spe_sha256_update,
242 	.final		=	ppc_spe_sha224_final,
243 	.export		=	ppc_spe_sha256_export,
244 	.import		=	ppc_spe_sha256_import,
245 	.descsize	=	sizeof(struct sha256_state),
246 	.statesize	=	sizeof(struct sha256_state),
247 	.base		=	{
248 		.cra_name	=	"sha224",
249 		.cra_driver_name=	"sha224-ppc-spe",
250 		.cra_priority	=	300,
251 		.cra_flags	=	CRYPTO_ALG_TYPE_SHASH,
252 		.cra_blocksize	=	SHA224_BLOCK_SIZE,
253 		.cra_module	=	THIS_MODULE,
254 	}
255 } };
256 
257 static int __init ppc_spe_sha256_mod_init(void)
258 {
259 	return crypto_register_shashes(algs, ARRAY_SIZE(algs));
260 }
261 
262 static void __exit ppc_spe_sha256_mod_fini(void)
263 {
264 	crypto_unregister_shashes(algs, ARRAY_SIZE(algs));
265 }
266 
267 module_init(ppc_spe_sha256_mod_init);
268 module_exit(ppc_spe_sha256_mod_fini);
269 
270 MODULE_LICENSE("GPL");
271 MODULE_DESCRIPTION("SHA-224 and SHA-256 Secure Hash Algorithm, SPE optimized");
272 
273 MODULE_ALIAS_CRYPTO("sha224");
274 MODULE_ALIAS_CRYPTO("sha224-ppc-spe");
275 MODULE_ALIAS_CRYPTO("sha256");
276 MODULE_ALIAS_CRYPTO("sha256-ppc-spe");
277