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
 34extern void ppc_spe_sha256_transform(u32 *state, const u8 *src, u32 blocks);
 35
 36static 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
 43static void spe_end(void)
 44{
 45	disable_kernel_spe();
 46	/* reenable preemption */
 47	preempt_enable();
 48}
 49
 50static 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
 60static 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
105static 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
145static 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
166static 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
174static 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
182static 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
216static int __init ppc_spe_sha256_mod_init(void)
217{
218	return crypto_register_shashes(algs, ARRAY_SIZE(algs));
219}
220
221static void __exit ppc_spe_sha256_mod_fini(void)
222{
223	crypto_unregister_shashes(algs, ARRAY_SIZE(algs));
224}
225
226module_init(ppc_spe_sha256_mod_init);
227module_exit(ppc_spe_sha256_mod_fini);
228
229MODULE_LICENSE("GPL");
230MODULE_DESCRIPTION("SHA-224 and SHA-256 Secure Hash Algorithm, SPE optimized");
231
232MODULE_ALIAS_CRYPTO("sha224");
233MODULE_ALIAS_CRYPTO("sha224-ppc-spe");
234MODULE_ALIAS_CRYPTO("sha256");
235MODULE_ALIAS_CRYPTO("sha256-ppc-spe");