1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Glue code for SHA-1 implementation for SPE instructions (PPC)
4  *
5  * Based on generic implementation.
6  *
7  * Copyright (c) 2015 Markus Stockhausen <stockhausen@collogia.de>
8  */
9 
10 #include <crypto/internal/hash.h>
11 #include <linux/init.h>
12 #include <linux/module.h>
13 #include <linux/mm.h>
14 #include <linux/cryptohash.h>
15 #include <linux/types.h>
16 #include <crypto/sha.h>
17 #include <asm/byteorder.h>
18 #include <asm/switch_to.h>
19 #include <linux/hardirq.h>
20 
21 /*
22  * MAX_BYTES defines the number of bytes that are allowed to be processed
23  * between preempt_disable() and preempt_enable(). SHA1 takes ~1000
24  * operations per 64 bytes. e500 cores can issue two arithmetic instructions
25  * per clock cycle using one 32/64 bit unit (SU1) and one 32 bit unit (SU2).
26  * Thus 2KB of input data will need an estimated maximum of 18,000 cycles.
27  * Headroom for cache misses included. Even with the low end model clocked
28  * at 667 MHz this equals to a critical time window of less than 27us.
29  *
30  */
31 #define MAX_BYTES 2048
32 
33 extern void ppc_spe_sha1_transform(u32 *state, const u8 *src, u32 blocks);
34 
35 static void spe_begin(void)
36 {
37 	/* We just start SPE operations and will save SPE registers later. */
38 	preempt_disable();
39 	enable_kernel_spe();
40 }
41 
42 static void spe_end(void)
43 {
44 	disable_kernel_spe();
45 	/* reenable preemption */
46 	preempt_enable();
47 }
48 
49 static inline void ppc_sha1_clear_context(struct sha1_state *sctx)
50 {
51 	int count = sizeof(struct sha1_state) >> 2;
52 	u32 *ptr = (u32 *)sctx;
53 
54 	/* make sure we can clear the fast way */
55 	BUILD_BUG_ON(sizeof(struct sha1_state) % 4);
56 	do { *ptr++ = 0; } while (--count);
57 }
58 
59 static int ppc_spe_sha1_init(struct shash_desc *desc)
60 {
61 	struct sha1_state *sctx = shash_desc_ctx(desc);
62 
63 	sctx->state[0] = SHA1_H0;
64 	sctx->state[1] = SHA1_H1;
65 	sctx->state[2] = SHA1_H2;
66 	sctx->state[3] = SHA1_H3;
67 	sctx->state[4] = SHA1_H4;
68 	sctx->count = 0;
69 
70 	return 0;
71 }
72 
73 static int ppc_spe_sha1_update(struct shash_desc *desc, const u8 *data,
74 			unsigned int len)
75 {
76 	struct sha1_state *sctx = shash_desc_ctx(desc);
77 	const unsigned int offset = sctx->count & 0x3f;
78 	const unsigned int avail = 64 - offset;
79 	unsigned int bytes;
80 	const u8 *src = data;
81 
82 	if (avail > len) {
83 		sctx->count += len;
84 		memcpy((char *)sctx->buffer + offset, src, len);
85 		return 0;
86 	}
87 
88 	sctx->count += len;
89 
90 	if (offset) {
91 		memcpy((char *)sctx->buffer + offset, src, avail);
92 
93 		spe_begin();
94 		ppc_spe_sha1_transform(sctx->state, (const u8 *)sctx->buffer, 1);
95 		spe_end();
96 
97 		len -= avail;
98 		src += avail;
99 	}
100 
101 	while (len > 63) {
102 		bytes = (len > MAX_BYTES) ? MAX_BYTES : len;
103 		bytes = bytes & ~0x3f;
104 
105 		spe_begin();
106 		ppc_spe_sha1_transform(sctx->state, src, bytes >> 6);
107 		spe_end();
108 
109 		src += bytes;
110 		len -= bytes;
111 	};
112 
113 	memcpy((char *)sctx->buffer, src, len);
114 	return 0;
115 }
116 
117 static int ppc_spe_sha1_final(struct shash_desc *desc, u8 *out)
118 {
119 	struct sha1_state *sctx = shash_desc_ctx(desc);
120 	const unsigned int offset = sctx->count & 0x3f;
121 	char *p = (char *)sctx->buffer + offset;
122 	int padlen;
123 	__be64 *pbits = (__be64 *)(((char *)&sctx->buffer) + 56);
124 	__be32 *dst = (__be32 *)out;
125 
126 	padlen = 55 - offset;
127 	*p++ = 0x80;
128 
129 	spe_begin();
130 
131 	if (padlen < 0) {
132 		memset(p, 0x00, padlen + sizeof (u64));
133 		ppc_spe_sha1_transform(sctx->state, sctx->buffer, 1);
134 		p = (char *)sctx->buffer;
135 		padlen = 56;
136 	}
137 
138 	memset(p, 0, padlen);
139 	*pbits = cpu_to_be64(sctx->count << 3);
140 	ppc_spe_sha1_transform(sctx->state, sctx->buffer, 1);
141 
142 	spe_end();
143 
144 	dst[0] = cpu_to_be32(sctx->state[0]);
145 	dst[1] = cpu_to_be32(sctx->state[1]);
146 	dst[2] = cpu_to_be32(sctx->state[2]);
147 	dst[3] = cpu_to_be32(sctx->state[3]);
148 	dst[4] = cpu_to_be32(sctx->state[4]);
149 
150 	ppc_sha1_clear_context(sctx);
151 	return 0;
152 }
153 
154 static int ppc_spe_sha1_export(struct shash_desc *desc, void *out)
155 {
156 	struct sha1_state *sctx = shash_desc_ctx(desc);
157 
158 	memcpy(out, sctx, sizeof(*sctx));
159 	return 0;
160 }
161 
162 static int ppc_spe_sha1_import(struct shash_desc *desc, const void *in)
163 {
164 	struct sha1_state *sctx = shash_desc_ctx(desc);
165 
166 	memcpy(sctx, in, sizeof(*sctx));
167 	return 0;
168 }
169 
170 static struct shash_alg alg = {
171 	.digestsize	=	SHA1_DIGEST_SIZE,
172 	.init		=	ppc_spe_sha1_init,
173 	.update		=	ppc_spe_sha1_update,
174 	.final		=	ppc_spe_sha1_final,
175 	.export		=	ppc_spe_sha1_export,
176 	.import		=	ppc_spe_sha1_import,
177 	.descsize	=	sizeof(struct sha1_state),
178 	.statesize	=	sizeof(struct sha1_state),
179 	.base		=	{
180 		.cra_name	=	"sha1",
181 		.cra_driver_name=	"sha1-ppc-spe",
182 		.cra_priority	=	300,
183 		.cra_blocksize	=	SHA1_BLOCK_SIZE,
184 		.cra_module	=	THIS_MODULE,
185 	}
186 };
187 
188 static int __init ppc_spe_sha1_mod_init(void)
189 {
190 	return crypto_register_shash(&alg);
191 }
192 
193 static void __exit ppc_spe_sha1_mod_fini(void)
194 {
195 	crypto_unregister_shash(&alg);
196 }
197 
198 module_init(ppc_spe_sha1_mod_init);
199 module_exit(ppc_spe_sha1_mod_fini);
200 
201 MODULE_LICENSE("GPL");
202 MODULE_DESCRIPTION("SHA1 Secure Hash Algorithm, SPE optimized");
203 
204 MODULE_ALIAS_CRYPTO("sha1");
205 MODULE_ALIAS_CRYPTO("sha1-ppc-spe");
206