1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Glue code for SHA-256 implementation for SPE instructions (PPC)
4  *
5  * Based on generic implementation. The assembler module takes care
6  * about the SPE registers so it can run from interrupt context.
7  *
8  * Copyright (c) 2015 Markus Stockhausen <stockhausen@collogia.de>
9  */
10 
11 #include <crypto/internal/hash.h>
12 #include <linux/init.h>
13 #include <linux/module.h>
14 #include <linux/mm.h>
15 #include <linux/types.h>
16 #include <crypto/sha2.h>
17 #include <crypto/sha256_base.h>
18 #include <asm/byteorder.h>
19 #include <asm/switch_to.h>
20 #include <linux/hardirq.h>
21 
22 /*
23  * MAX_BYTES defines the number of bytes that are allowed to be processed
24  * between preempt_disable() and preempt_enable(). SHA256 takes ~2,000
25  * operations per 64 bytes. e500 cores can issue two arithmetic instructions
26  * per clock cycle using one 32/64 bit unit (SU1) and one 32 bit unit (SU2).
27  * Thus 1KB of input data will need an estimated maximum of 18,000 cycles.
28  * Headroom for cache misses included. Even with the low end model clocked
29  * at 667 MHz this equals to a critical time window of less than 27us.
30  *
31  */
32 #define MAX_BYTES 1024
33 
34 extern void ppc_spe_sha256_transform(u32 *state, const u8 *src, u32 blocks);
35 
spe_begin(void)36 static void spe_begin(void)
37 {
38 	/* We just start SPE operations and will save SPE registers later. */
39 	preempt_disable();
40 	enable_kernel_spe();
41 }
42 
spe_end(void)43 static void spe_end(void)
44 {
45 	disable_kernel_spe();
46 	/* reenable preemption */
47 	preempt_enable();
48 }
49 
ppc_sha256_clear_context(struct sha256_state * sctx)50 static inline void ppc_sha256_clear_context(struct sha256_state *sctx)
51 {
52 	int count = sizeof(struct sha256_state) >> 2;
53 	u32 *ptr = (u32 *)sctx;
54 
55 	/* make sure we can clear the fast way */
56 	BUILD_BUG_ON(sizeof(struct sha256_state) % 4);
57 	do { *ptr++ = 0; } while (--count);
58 }
59 
ppc_spe_sha256_update(struct shash_desc * desc,const u8 * data,unsigned int len)60 static int ppc_spe_sha256_update(struct shash_desc *desc, const u8 *data,
61 			unsigned int len)
62 {
63 	struct sha256_state *sctx = shash_desc_ctx(desc);
64 	const unsigned int offset = sctx->count & 0x3f;
65 	const unsigned int avail = 64 - offset;
66 	unsigned int bytes;
67 	const u8 *src = data;
68 
69 	if (avail > len) {
70 		sctx->count += len;
71 		memcpy((char *)sctx->buf + offset, src, len);
72 		return 0;
73 	}
74 
75 	sctx->count += len;
76 
77 	if (offset) {
78 		memcpy((char *)sctx->buf + offset, src, avail);
79 
80 		spe_begin();
81 		ppc_spe_sha256_transform(sctx->state, (const u8 *)sctx->buf, 1);
82 		spe_end();
83 
84 		len -= avail;
85 		src += avail;
86 	}
87 
88 	while (len > 63) {
89 		/* cut input data into smaller blocks */
90 		bytes = (len > MAX_BYTES) ? MAX_BYTES : len;
91 		bytes = bytes & ~0x3f;
92 
93 		spe_begin();
94 		ppc_spe_sha256_transform(sctx->state, src, bytes >> 6);
95 		spe_end();
96 
97 		src += bytes;
98 		len -= bytes;
99 	}
100 
101 	memcpy((char *)sctx->buf, src, len);
102 	return 0;
103 }
104 
ppc_spe_sha256_final(struct shash_desc * desc,u8 * out)105 static int ppc_spe_sha256_final(struct shash_desc *desc, u8 *out)
106 {
107 	struct sha256_state *sctx = shash_desc_ctx(desc);
108 	const unsigned int offset = sctx->count & 0x3f;
109 	char *p = (char *)sctx->buf + offset;
110 	int padlen;
111 	__be64 *pbits = (__be64 *)(((char *)&sctx->buf) + 56);
112 	__be32 *dst = (__be32 *)out;
113 
114 	padlen = 55 - offset;
115 	*p++ = 0x80;
116 
117 	spe_begin();
118 
119 	if (padlen < 0) {
120 		memset(p, 0x00, padlen + sizeof (u64));
121 		ppc_spe_sha256_transform(sctx->state, sctx->buf, 1);
122 		p = (char *)sctx->buf;
123 		padlen = 56;
124 	}
125 
126 	memset(p, 0, padlen);
127 	*pbits = cpu_to_be64(sctx->count << 3);
128 	ppc_spe_sha256_transform(sctx->state, sctx->buf, 1);
129 
130 	spe_end();
131 
132 	dst[0] = cpu_to_be32(sctx->state[0]);
133 	dst[1] = cpu_to_be32(sctx->state[1]);
134 	dst[2] = cpu_to_be32(sctx->state[2]);
135 	dst[3] = cpu_to_be32(sctx->state[3]);
136 	dst[4] = cpu_to_be32(sctx->state[4]);
137 	dst[5] = cpu_to_be32(sctx->state[5]);
138 	dst[6] = cpu_to_be32(sctx->state[6]);
139 	dst[7] = cpu_to_be32(sctx->state[7]);
140 
141 	ppc_sha256_clear_context(sctx);
142 	return 0;
143 }
144 
ppc_spe_sha224_final(struct shash_desc * desc,u8 * out)145 static int ppc_spe_sha224_final(struct shash_desc *desc, u8 *out)
146 {
147 	__be32 D[SHA256_DIGEST_SIZE >> 2];
148 	__be32 *dst = (__be32 *)out;
149 
150 	ppc_spe_sha256_final(desc, (u8 *)D);
151 
152 	/* avoid bytewise memcpy */
153 	dst[0] = D[0];
154 	dst[1] = D[1];
155 	dst[2] = D[2];
156 	dst[3] = D[3];
157 	dst[4] = D[4];
158 	dst[5] = D[5];
159 	dst[6] = D[6];
160 
161 	/* clear sensitive data */
162 	memzero_explicit(D, SHA256_DIGEST_SIZE);
163 	return 0;
164 }
165 
ppc_spe_sha256_export(struct shash_desc * desc,void * out)166 static int ppc_spe_sha256_export(struct shash_desc *desc, void *out)
167 {
168 	struct sha256_state *sctx = shash_desc_ctx(desc);
169 
170 	memcpy(out, sctx, sizeof(*sctx));
171 	return 0;
172 }
173 
ppc_spe_sha256_import(struct shash_desc * desc,const void * in)174 static int ppc_spe_sha256_import(struct shash_desc *desc, const void *in)
175 {
176 	struct sha256_state *sctx = shash_desc_ctx(desc);
177 
178 	memcpy(sctx, in, sizeof(*sctx));
179 	return 0;
180 }
181 
182 static struct shash_alg algs[2] = { {
183 	.digestsize	=	SHA256_DIGEST_SIZE,
184 	.init		=	sha256_base_init,
185 	.update		=	ppc_spe_sha256_update,
186 	.final		=	ppc_spe_sha256_final,
187 	.export		=	ppc_spe_sha256_export,
188 	.import		=	ppc_spe_sha256_import,
189 	.descsize	=	sizeof(struct sha256_state),
190 	.statesize	=	sizeof(struct sha256_state),
191 	.base		=	{
192 		.cra_name	=	"sha256",
193 		.cra_driver_name=	"sha256-ppc-spe",
194 		.cra_priority	=	300,
195 		.cra_blocksize	=	SHA256_BLOCK_SIZE,
196 		.cra_module	=	THIS_MODULE,
197 	}
198 }, {
199 	.digestsize	=	SHA224_DIGEST_SIZE,
200 	.init		=	sha224_base_init,
201 	.update		=	ppc_spe_sha256_update,
202 	.final		=	ppc_spe_sha224_final,
203 	.export		=	ppc_spe_sha256_export,
204 	.import		=	ppc_spe_sha256_import,
205 	.descsize	=	sizeof(struct sha256_state),
206 	.statesize	=	sizeof(struct sha256_state),
207 	.base		=	{
208 		.cra_name	=	"sha224",
209 		.cra_driver_name=	"sha224-ppc-spe",
210 		.cra_priority	=	300,
211 		.cra_blocksize	=	SHA224_BLOCK_SIZE,
212 		.cra_module	=	THIS_MODULE,
213 	}
214 } };
215 
ppc_spe_sha256_mod_init(void)216 static int __init ppc_spe_sha256_mod_init(void)
217 {
218 	return crypto_register_shashes(algs, ARRAY_SIZE(algs));
219 }
220 
ppc_spe_sha256_mod_fini(void)221 static void __exit ppc_spe_sha256_mod_fini(void)
222 {
223 	crypto_unregister_shashes(algs, ARRAY_SIZE(algs));
224 }
225 
226 module_init(ppc_spe_sha256_mod_init);
227 module_exit(ppc_spe_sha256_mod_fini);
228 
229 MODULE_LICENSE("GPL");
230 MODULE_DESCRIPTION("SHA-224 and SHA-256 Secure Hash Algorithm, SPE optimized");
231 
232 MODULE_ALIAS_CRYPTO("sha224");
233 MODULE_ALIAS_CRYPTO("sha224-ppc-spe");
234 MODULE_ALIAS_CRYPTO("sha256");
235 MODULE_ALIAS_CRYPTO("sha256-ppc-spe");
236