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