1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Glue code for AES 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/aes.h>
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/types.h>
15 #include <linux/errno.h>
16 #include <linux/crypto.h>
17 #include <asm/byteorder.h>
18 #include <asm/switch_to.h>
19 #include <crypto/algapi.h>
20 #include <crypto/internal/skcipher.h>
21 #include <crypto/xts.h>
22 #include <crypto/gf128mul.h>
23 #include <crypto/scatterwalk.h>
24
25 /*
26 * MAX_BYTES defines the number of bytes that are allowed to be processed
27 * between preempt_disable() and preempt_enable(). e500 cores can issue two
28 * instructions per clock cycle using one 32/64 bit unit (SU1) and one 32
29 * bit unit (SU2). One of these can be a memory access that is executed via
30 * a single load and store unit (LSU). XTS-AES-256 takes ~780 operations per
31 * 16 byte block or 25 cycles per byte. Thus 768 bytes of input data
32 * will need an estimated maximum of 20,000 cycles. Headroom for cache misses
33 * included. Even with the low end model clocked at 667 MHz this equals to a
34 * critical time window of less than 30us. The value has been chosen to
35 * process a 512 byte disk block in one or a large 1400 bytes IPsec network
36 * packet in two runs.
37 *
38 */
39 #define MAX_BYTES 768
40
41 struct ppc_aes_ctx {
42 u32 key_enc[AES_MAX_KEYLENGTH_U32];
43 u32 key_dec[AES_MAX_KEYLENGTH_U32];
44 u32 rounds;
45 };
46
47 struct ppc_xts_ctx {
48 u32 key_enc[AES_MAX_KEYLENGTH_U32];
49 u32 key_dec[AES_MAX_KEYLENGTH_U32];
50 u32 key_twk[AES_MAX_KEYLENGTH_U32];
51 u32 rounds;
52 };
53
spe_begin(void)54 static void spe_begin(void)
55 {
56 /* disable preemption and save users SPE registers if required */
57 preempt_disable();
58 enable_kernel_spe();
59 }
60
spe_end(void)61 static void spe_end(void)
62 {
63 disable_kernel_spe();
64 /* reenable preemption */
65 preempt_enable();
66 }
67
ppc_aes_setkey_skcipher(struct crypto_skcipher * tfm,const u8 * in_key,unsigned int key_len)68 static int ppc_aes_setkey_skcipher(struct crypto_skcipher *tfm,
69 const u8 *in_key, unsigned int key_len)
70 {
71 struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
72
73 switch (key_len) {
74 case AES_KEYSIZE_128:
75 ctx->rounds = 4;
76 ppc_expand_key_128(ctx->key_enc, in_key);
77 break;
78 case AES_KEYSIZE_192:
79 ctx->rounds = 5;
80 ppc_expand_key_192(ctx->key_enc, in_key);
81 break;
82 case AES_KEYSIZE_256:
83 ctx->rounds = 6;
84 ppc_expand_key_256(ctx->key_enc, in_key);
85 break;
86 default:
87 return -EINVAL;
88 }
89
90 ppc_generate_decrypt_key(ctx->key_dec, ctx->key_enc, key_len);
91
92 return 0;
93 }
94
ppc_xts_setkey(struct crypto_skcipher * tfm,const u8 * in_key,unsigned int key_len)95 static int ppc_xts_setkey(struct crypto_skcipher *tfm, const u8 *in_key,
96 unsigned int key_len)
97 {
98 struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
99 int err;
100
101 err = xts_verify_key(tfm, in_key, key_len);
102 if (err)
103 return err;
104
105 key_len >>= 1;
106
107 switch (key_len) {
108 case AES_KEYSIZE_128:
109 ctx->rounds = 4;
110 ppc_expand_key_128(ctx->key_enc, in_key);
111 ppc_expand_key_128(ctx->key_twk, in_key + AES_KEYSIZE_128);
112 break;
113 case AES_KEYSIZE_192:
114 ctx->rounds = 5;
115 ppc_expand_key_192(ctx->key_enc, in_key);
116 ppc_expand_key_192(ctx->key_twk, in_key + AES_KEYSIZE_192);
117 break;
118 case AES_KEYSIZE_256:
119 ctx->rounds = 6;
120 ppc_expand_key_256(ctx->key_enc, in_key);
121 ppc_expand_key_256(ctx->key_twk, in_key + AES_KEYSIZE_256);
122 break;
123 default:
124 return -EINVAL;
125 }
126
127 ppc_generate_decrypt_key(ctx->key_dec, ctx->key_enc, key_len);
128
129 return 0;
130 }
131
ppc_ecb_crypt(struct skcipher_request * req,bool enc)132 static int ppc_ecb_crypt(struct skcipher_request *req, bool enc)
133 {
134 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
135 struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
136 struct skcipher_walk walk;
137 unsigned int nbytes;
138 int err;
139
140 err = skcipher_walk_virt(&walk, req, false);
141
142 while ((nbytes = walk.nbytes) != 0) {
143 nbytes = min_t(unsigned int, nbytes, MAX_BYTES);
144 nbytes = round_down(nbytes, AES_BLOCK_SIZE);
145
146 spe_begin();
147 if (enc)
148 ppc_encrypt_ecb(walk.dst.virt.addr, walk.src.virt.addr,
149 ctx->key_enc, ctx->rounds, nbytes);
150 else
151 ppc_decrypt_ecb(walk.dst.virt.addr, walk.src.virt.addr,
152 ctx->key_dec, ctx->rounds, nbytes);
153 spe_end();
154
155 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
156 }
157
158 return err;
159 }
160
ppc_ecb_encrypt(struct skcipher_request * req)161 static int ppc_ecb_encrypt(struct skcipher_request *req)
162 {
163 return ppc_ecb_crypt(req, true);
164 }
165
ppc_ecb_decrypt(struct skcipher_request * req)166 static int ppc_ecb_decrypt(struct skcipher_request *req)
167 {
168 return ppc_ecb_crypt(req, false);
169 }
170
ppc_cbc_crypt(struct skcipher_request * req,bool enc)171 static int ppc_cbc_crypt(struct skcipher_request *req, bool enc)
172 {
173 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
174 struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
175 struct skcipher_walk walk;
176 unsigned int nbytes;
177 int err;
178
179 err = skcipher_walk_virt(&walk, req, false);
180
181 while ((nbytes = walk.nbytes) != 0) {
182 nbytes = min_t(unsigned int, nbytes, MAX_BYTES);
183 nbytes = round_down(nbytes, AES_BLOCK_SIZE);
184
185 spe_begin();
186 if (enc)
187 ppc_encrypt_cbc(walk.dst.virt.addr, walk.src.virt.addr,
188 ctx->key_enc, ctx->rounds, nbytes,
189 walk.iv);
190 else
191 ppc_decrypt_cbc(walk.dst.virt.addr, walk.src.virt.addr,
192 ctx->key_dec, ctx->rounds, nbytes,
193 walk.iv);
194 spe_end();
195
196 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
197 }
198
199 return err;
200 }
201
ppc_cbc_encrypt(struct skcipher_request * req)202 static int ppc_cbc_encrypt(struct skcipher_request *req)
203 {
204 return ppc_cbc_crypt(req, true);
205 }
206
ppc_cbc_decrypt(struct skcipher_request * req)207 static int ppc_cbc_decrypt(struct skcipher_request *req)
208 {
209 return ppc_cbc_crypt(req, false);
210 }
211
ppc_ctr_crypt(struct skcipher_request * req)212 static int ppc_ctr_crypt(struct skcipher_request *req)
213 {
214 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
215 struct ppc_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
216 struct skcipher_walk walk;
217 unsigned int nbytes;
218 int err;
219
220 err = skcipher_walk_virt(&walk, req, false);
221
222 while ((nbytes = walk.nbytes) != 0) {
223 nbytes = min_t(unsigned int, nbytes, MAX_BYTES);
224 if (nbytes < walk.total)
225 nbytes = round_down(nbytes, AES_BLOCK_SIZE);
226
227 spe_begin();
228 ppc_crypt_ctr(walk.dst.virt.addr, walk.src.virt.addr,
229 ctx->key_enc, ctx->rounds, nbytes, walk.iv);
230 spe_end();
231
232 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
233 }
234
235 return err;
236 }
237
ppc_xts_crypt(struct skcipher_request * req,bool enc)238 static int ppc_xts_crypt(struct skcipher_request *req, bool enc)
239 {
240 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
241 struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
242 struct skcipher_walk walk;
243 unsigned int nbytes;
244 int err;
245 u32 *twk;
246
247 err = skcipher_walk_virt(&walk, req, false);
248 twk = ctx->key_twk;
249
250 while ((nbytes = walk.nbytes) != 0) {
251 nbytes = min_t(unsigned int, nbytes, MAX_BYTES);
252 nbytes = round_down(nbytes, AES_BLOCK_SIZE);
253
254 spe_begin();
255 if (enc)
256 ppc_encrypt_xts(walk.dst.virt.addr, walk.src.virt.addr,
257 ctx->key_enc, ctx->rounds, nbytes,
258 walk.iv, twk);
259 else
260 ppc_decrypt_xts(walk.dst.virt.addr, walk.src.virt.addr,
261 ctx->key_dec, ctx->rounds, nbytes,
262 walk.iv, twk);
263 spe_end();
264
265 twk = NULL;
266 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
267 }
268
269 return err;
270 }
271
ppc_xts_encrypt(struct skcipher_request * req)272 static int ppc_xts_encrypt(struct skcipher_request *req)
273 {
274 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
275 struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
276 int tail = req->cryptlen % AES_BLOCK_SIZE;
277 int offset = req->cryptlen - tail - AES_BLOCK_SIZE;
278 struct skcipher_request subreq;
279 u8 b[2][AES_BLOCK_SIZE];
280 int err;
281
282 if (req->cryptlen < AES_BLOCK_SIZE)
283 return -EINVAL;
284
285 if (tail) {
286 subreq = *req;
287 skcipher_request_set_crypt(&subreq, req->src, req->dst,
288 req->cryptlen - tail, req->iv);
289 req = &subreq;
290 }
291
292 err = ppc_xts_crypt(req, true);
293 if (err || !tail)
294 return err;
295
296 scatterwalk_map_and_copy(b[0], req->dst, offset, AES_BLOCK_SIZE, 0);
297 memcpy(b[1], b[0], tail);
298 scatterwalk_map_and_copy(b[0], req->src, offset + AES_BLOCK_SIZE, tail, 0);
299
300 spe_begin();
301 ppc_encrypt_xts(b[0], b[0], ctx->key_enc, ctx->rounds, AES_BLOCK_SIZE,
302 req->iv, NULL);
303 spe_end();
304
305 scatterwalk_map_and_copy(b[0], req->dst, offset, AES_BLOCK_SIZE + tail, 1);
306
307 return 0;
308 }
309
ppc_xts_decrypt(struct skcipher_request * req)310 static int ppc_xts_decrypt(struct skcipher_request *req)
311 {
312 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
313 struct ppc_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
314 int tail = req->cryptlen % AES_BLOCK_SIZE;
315 int offset = req->cryptlen - tail - AES_BLOCK_SIZE;
316 struct skcipher_request subreq;
317 u8 b[3][AES_BLOCK_SIZE];
318 le128 twk;
319 int err;
320
321 if (req->cryptlen < AES_BLOCK_SIZE)
322 return -EINVAL;
323
324 if (tail) {
325 subreq = *req;
326 skcipher_request_set_crypt(&subreq, req->src, req->dst,
327 offset, req->iv);
328 req = &subreq;
329 }
330
331 err = ppc_xts_crypt(req, false);
332 if (err || !tail)
333 return err;
334
335 scatterwalk_map_and_copy(b[1], req->src, offset, AES_BLOCK_SIZE + tail, 0);
336
337 spe_begin();
338 if (!offset)
339 ppc_encrypt_ecb(req->iv, req->iv, ctx->key_twk, ctx->rounds,
340 AES_BLOCK_SIZE);
341
342 gf128mul_x_ble(&twk, (le128 *)req->iv);
343
344 ppc_decrypt_xts(b[1], b[1], ctx->key_dec, ctx->rounds, AES_BLOCK_SIZE,
345 (u8 *)&twk, NULL);
346 memcpy(b[0], b[2], tail);
347 memcpy(b[0] + tail, b[1] + tail, AES_BLOCK_SIZE - tail);
348 ppc_decrypt_xts(b[0], b[0], ctx->key_dec, ctx->rounds, AES_BLOCK_SIZE,
349 req->iv, NULL);
350 spe_end();
351
352 scatterwalk_map_and_copy(b[0], req->dst, offset, AES_BLOCK_SIZE + tail, 1);
353
354 return 0;
355 }
356
357 /*
358 * Algorithm definitions. Disabling alignment (cra_alignmask=0) was chosen
359 * because the e500 platform can handle unaligned reads/writes very efficiently.
360 * This improves IPsec thoughput by another few percent. Additionally we assume
361 * that AES context is always aligned to at least 8 bytes because it is created
362 * with kmalloc() in the crypto infrastructure
363 */
364
365 static struct skcipher_alg aes_skcipher_algs[] = {
366 {
367 .base.cra_name = "ecb(aes)",
368 .base.cra_driver_name = "ecb-ppc-spe",
369 .base.cra_priority = 300,
370 .base.cra_blocksize = AES_BLOCK_SIZE,
371 .base.cra_ctxsize = sizeof(struct ppc_aes_ctx),
372 .base.cra_module = THIS_MODULE,
373 .min_keysize = AES_MIN_KEY_SIZE,
374 .max_keysize = AES_MAX_KEY_SIZE,
375 .setkey = ppc_aes_setkey_skcipher,
376 .encrypt = ppc_ecb_encrypt,
377 .decrypt = ppc_ecb_decrypt,
378 }, {
379 .base.cra_name = "cbc(aes)",
380 .base.cra_driver_name = "cbc-ppc-spe",
381 .base.cra_priority = 300,
382 .base.cra_blocksize = AES_BLOCK_SIZE,
383 .base.cra_ctxsize = sizeof(struct ppc_aes_ctx),
384 .base.cra_module = THIS_MODULE,
385 .min_keysize = AES_MIN_KEY_SIZE,
386 .max_keysize = AES_MAX_KEY_SIZE,
387 .ivsize = AES_BLOCK_SIZE,
388 .setkey = ppc_aes_setkey_skcipher,
389 .encrypt = ppc_cbc_encrypt,
390 .decrypt = ppc_cbc_decrypt,
391 }, {
392 .base.cra_name = "ctr(aes)",
393 .base.cra_driver_name = "ctr-ppc-spe",
394 .base.cra_priority = 300,
395 .base.cra_blocksize = 1,
396 .base.cra_ctxsize = sizeof(struct ppc_aes_ctx),
397 .base.cra_module = THIS_MODULE,
398 .min_keysize = AES_MIN_KEY_SIZE,
399 .max_keysize = AES_MAX_KEY_SIZE,
400 .ivsize = AES_BLOCK_SIZE,
401 .setkey = ppc_aes_setkey_skcipher,
402 .encrypt = ppc_ctr_crypt,
403 .decrypt = ppc_ctr_crypt,
404 .chunksize = AES_BLOCK_SIZE,
405 }, {
406 .base.cra_name = "xts(aes)",
407 .base.cra_driver_name = "xts-ppc-spe",
408 .base.cra_priority = 300,
409 .base.cra_blocksize = AES_BLOCK_SIZE,
410 .base.cra_ctxsize = sizeof(struct ppc_xts_ctx),
411 .base.cra_module = THIS_MODULE,
412 .min_keysize = AES_MIN_KEY_SIZE * 2,
413 .max_keysize = AES_MAX_KEY_SIZE * 2,
414 .ivsize = AES_BLOCK_SIZE,
415 .setkey = ppc_xts_setkey,
416 .encrypt = ppc_xts_encrypt,
417 .decrypt = ppc_xts_decrypt,
418 }
419 };
420
ppc_aes_mod_init(void)421 static int __init ppc_aes_mod_init(void)
422 {
423 return crypto_register_skciphers(aes_skcipher_algs,
424 ARRAY_SIZE(aes_skcipher_algs));
425 }
426
ppc_aes_mod_fini(void)427 static void __exit ppc_aes_mod_fini(void)
428 {
429 crypto_unregister_skciphers(aes_skcipher_algs,
430 ARRAY_SIZE(aes_skcipher_algs));
431 }
432
433 module_init(ppc_aes_mod_init);
434 module_exit(ppc_aes_mod_fini);
435
436 MODULE_LICENSE("GPL");
437 MODULE_DESCRIPTION("AES-ECB/CBC/CTR/XTS, SPE optimized");
438
439 MODULE_ALIAS_CRYPTO("aes");
440 MODULE_ALIAS_CRYPTO("ecb(aes)");
441 MODULE_ALIAS_CRYPTO("cbc(aes)");
442 MODULE_ALIAS_CRYPTO("ctr(aes)");
443 MODULE_ALIAS_CRYPTO("xts(aes)");
444 MODULE_ALIAS_CRYPTO("aes-ppc-spe");
445