xref: /openbmc/linux/drivers/crypto/padlock-aes.c (revision 96de0e252cedffad61b3cb5e05662c591898e69a)
1 /*
2  * Cryptographic API.
3  *
4  * Support for VIA PadLock hardware crypto engine.
5  *
6  * Copyright (c) 2004  Michal Ludvig <michal@logix.cz>
7  *
8  * Key expansion routine taken from crypto/aes_generic.c
9  *
10  * This program is free software; you can redistribute it and/or modify
11  * it under the terms of the GNU General Public License as published by
12  * the Free Software Foundation; either version 2 of the License, or
13  * (at your option) any later version.
14  *
15  * ---------------------------------------------------------------------------
16  * Copyright (c) 2002, Dr Brian Gladman <brg@gladman.me.uk>, Worcester, UK.
17  * All rights reserved.
18  *
19  * LICENSE TERMS
20  *
21  * The free distribution and use of this software in both source and binary
22  * form is allowed (with or without changes) provided that:
23  *
24  *   1. distributions of this source code include the above copyright
25  *      notice, this list of conditions and the following disclaimer;
26  *
27  *   2. distributions in binary form include the above copyright
28  *      notice, this list of conditions and the following disclaimer
29  *      in the documentation and/or other associated materials;
30  *
31  *   3. the copyright holder's name is not used to endorse products
32  *      built using this software without specific written permission.
33  *
34  * ALTERNATIVELY, provided that this notice is retained in full, this product
35  * may be distributed under the terms of the GNU General Public License (GPL),
36  * in which case the provisions of the GPL apply INSTEAD OF those given above.
37  *
38  * DISCLAIMER
39  *
40  * This software is provided 'as is' with no explicit or implied warranties
41  * in respect of its properties, including, but not limited to, correctness
42  * and/or fitness for purpose.
43  * ---------------------------------------------------------------------------
44  */
45 
46 #include <crypto/algapi.h>
47 #include <linux/module.h>
48 #include <linux/init.h>
49 #include <linux/types.h>
50 #include <linux/errno.h>
51 #include <linux/interrupt.h>
52 #include <linux/kernel.h>
53 #include <asm/byteorder.h>
54 #include "padlock.h"
55 
56 #define AES_MIN_KEY_SIZE	16	/* in uint8_t units */
57 #define AES_MAX_KEY_SIZE	32	/* ditto */
58 #define AES_BLOCK_SIZE		16	/* ditto */
59 #define AES_EXTENDED_KEY_SIZE	64	/* in uint32_t units */
60 #define AES_EXTENDED_KEY_SIZE_B	(AES_EXTENDED_KEY_SIZE * sizeof(uint32_t))
61 
62 /* Control word. */
63 struct cword {
64 	unsigned int __attribute__ ((__packed__))
65 		rounds:4,
66 		algo:3,
67 		keygen:1,
68 		interm:1,
69 		encdec:1,
70 		ksize:2;
71 } __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
72 
73 /* Whenever making any changes to the following
74  * structure *make sure* you keep E, d_data
75  * and cword aligned on 16 Bytes boundaries!!! */
76 struct aes_ctx {
77 	struct {
78 		struct cword encrypt;
79 		struct cword decrypt;
80 	} cword;
81 	u32 *D;
82 	int key_length;
83 	u32 E[AES_EXTENDED_KEY_SIZE]
84 		__attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
85 	u32 d_data[AES_EXTENDED_KEY_SIZE]
86 		__attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
87 };
88 
89 /* ====== Key management routines ====== */
90 
91 static inline uint32_t
92 generic_rotr32 (const uint32_t x, const unsigned bits)
93 {
94 	const unsigned n = bits % 32;
95 	return (x >> n) | (x << (32 - n));
96 }
97 
98 static inline uint32_t
99 generic_rotl32 (const uint32_t x, const unsigned bits)
100 {
101 	const unsigned n = bits % 32;
102 	return (x << n) | (x >> (32 - n));
103 }
104 
105 #define rotl generic_rotl32
106 #define rotr generic_rotr32
107 
108 /*
109  * #define byte(x, nr) ((unsigned char)((x) >> (nr*8)))
110  */
111 static inline uint8_t
112 byte(const uint32_t x, const unsigned n)
113 {
114 	return x >> (n << 3);
115 }
116 
117 #define E_KEY ctx->E
118 #define D_KEY ctx->D
119 
120 static uint8_t pow_tab[256];
121 static uint8_t log_tab[256];
122 static uint8_t sbx_tab[256];
123 static uint8_t isb_tab[256];
124 static uint32_t rco_tab[10];
125 static uint32_t ft_tab[4][256];
126 static uint32_t it_tab[4][256];
127 
128 static uint32_t fl_tab[4][256];
129 static uint32_t il_tab[4][256];
130 
131 static inline uint8_t
132 f_mult (uint8_t a, uint8_t b)
133 {
134 	uint8_t aa = log_tab[a], cc = aa + log_tab[b];
135 
136 	return pow_tab[cc + (cc < aa ? 1 : 0)];
137 }
138 
139 #define ff_mult(a,b)    (a && b ? f_mult(a, b) : 0)
140 
141 #define f_rn(bo, bi, n, k)					\
142     bo[n] =  ft_tab[0][byte(bi[n],0)] ^				\
143              ft_tab[1][byte(bi[(n + 1) & 3],1)] ^		\
144              ft_tab[2][byte(bi[(n + 2) & 3],2)] ^		\
145              ft_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)
146 
147 #define i_rn(bo, bi, n, k)					\
148     bo[n] =  it_tab[0][byte(bi[n],0)] ^				\
149              it_tab[1][byte(bi[(n + 3) & 3],1)] ^		\
150              it_tab[2][byte(bi[(n + 2) & 3],2)] ^		\
151              it_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)
152 
153 #define ls_box(x)				\
154     ( fl_tab[0][byte(x, 0)] ^			\
155       fl_tab[1][byte(x, 1)] ^			\
156       fl_tab[2][byte(x, 2)] ^			\
157       fl_tab[3][byte(x, 3)] )
158 
159 #define f_rl(bo, bi, n, k)					\
160     bo[n] =  fl_tab[0][byte(bi[n],0)] ^				\
161              fl_tab[1][byte(bi[(n + 1) & 3],1)] ^		\
162              fl_tab[2][byte(bi[(n + 2) & 3],2)] ^		\
163              fl_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)
164 
165 #define i_rl(bo, bi, n, k)					\
166     bo[n] =  il_tab[0][byte(bi[n],0)] ^				\
167              il_tab[1][byte(bi[(n + 3) & 3],1)] ^		\
168              il_tab[2][byte(bi[(n + 2) & 3],2)] ^		\
169              il_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)
170 
171 static void
172 gen_tabs (void)
173 {
174 	uint32_t i, t;
175 	uint8_t p, q;
176 
177 	/* log and power tables for GF(2**8) finite field with
178 	   0x011b as modular polynomial - the simplest prmitive
179 	   root is 0x03, used here to generate the tables */
180 
181 	for (i = 0, p = 1; i < 256; ++i) {
182 		pow_tab[i] = (uint8_t) p;
183 		log_tab[p] = (uint8_t) i;
184 
185 		p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0);
186 	}
187 
188 	log_tab[1] = 0;
189 
190 	for (i = 0, p = 1; i < 10; ++i) {
191 		rco_tab[i] = p;
192 
193 		p = (p << 1) ^ (p & 0x80 ? 0x01b : 0);
194 	}
195 
196 	for (i = 0; i < 256; ++i) {
197 		p = (i ? pow_tab[255 - log_tab[i]] : 0);
198 		q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2));
199 		p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2));
200 		sbx_tab[i] = p;
201 		isb_tab[p] = (uint8_t) i;
202 	}
203 
204 	for (i = 0; i < 256; ++i) {
205 		p = sbx_tab[i];
206 
207 		t = p;
208 		fl_tab[0][i] = t;
209 		fl_tab[1][i] = rotl (t, 8);
210 		fl_tab[2][i] = rotl (t, 16);
211 		fl_tab[3][i] = rotl (t, 24);
212 
213 		t = ((uint32_t) ff_mult (2, p)) |
214 		    ((uint32_t) p << 8) |
215 		    ((uint32_t) p << 16) | ((uint32_t) ff_mult (3, p) << 24);
216 
217 		ft_tab[0][i] = t;
218 		ft_tab[1][i] = rotl (t, 8);
219 		ft_tab[2][i] = rotl (t, 16);
220 		ft_tab[3][i] = rotl (t, 24);
221 
222 		p = isb_tab[i];
223 
224 		t = p;
225 		il_tab[0][i] = t;
226 		il_tab[1][i] = rotl (t, 8);
227 		il_tab[2][i] = rotl (t, 16);
228 		il_tab[3][i] = rotl (t, 24);
229 
230 		t = ((uint32_t) ff_mult (14, p)) |
231 		    ((uint32_t) ff_mult (9, p) << 8) |
232 		    ((uint32_t) ff_mult (13, p) << 16) |
233 		    ((uint32_t) ff_mult (11, p) << 24);
234 
235 		it_tab[0][i] = t;
236 		it_tab[1][i] = rotl (t, 8);
237 		it_tab[2][i] = rotl (t, 16);
238 		it_tab[3][i] = rotl (t, 24);
239 	}
240 }
241 
242 #define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b)
243 
244 #define imix_col(y,x)       \
245     u   = star_x(x);        \
246     v   = star_x(u);        \
247     w   = star_x(v);        \
248     t   = w ^ (x);          \
249    (y)  = u ^ v ^ w;        \
250    (y) ^= rotr(u ^ t,  8) ^ \
251           rotr(v ^ t, 16) ^ \
252           rotr(t,24)
253 
254 /* initialise the key schedule from the user supplied key */
255 
256 #define loop4(i)                                    \
257 {   t = rotr(t,  8); t = ls_box(t) ^ rco_tab[i];    \
258     t ^= E_KEY[4 * i];     E_KEY[4 * i + 4] = t;    \
259     t ^= E_KEY[4 * i + 1]; E_KEY[4 * i + 5] = t;    \
260     t ^= E_KEY[4 * i + 2]; E_KEY[4 * i + 6] = t;    \
261     t ^= E_KEY[4 * i + 3]; E_KEY[4 * i + 7] = t;    \
262 }
263 
264 #define loop6(i)                                    \
265 {   t = rotr(t,  8); t = ls_box(t) ^ rco_tab[i];    \
266     t ^= E_KEY[6 * i];     E_KEY[6 * i + 6] = t;    \
267     t ^= E_KEY[6 * i + 1]; E_KEY[6 * i + 7] = t;    \
268     t ^= E_KEY[6 * i + 2]; E_KEY[6 * i + 8] = t;    \
269     t ^= E_KEY[6 * i + 3]; E_KEY[6 * i + 9] = t;    \
270     t ^= E_KEY[6 * i + 4]; E_KEY[6 * i + 10] = t;   \
271     t ^= E_KEY[6 * i + 5]; E_KEY[6 * i + 11] = t;   \
272 }
273 
274 #define loop8(i)                                    \
275 {   t = rotr(t,  8); ; t = ls_box(t) ^ rco_tab[i];  \
276     t ^= E_KEY[8 * i];     E_KEY[8 * i + 8] = t;    \
277     t ^= E_KEY[8 * i + 1]; E_KEY[8 * i + 9] = t;    \
278     t ^= E_KEY[8 * i + 2]; E_KEY[8 * i + 10] = t;   \
279     t ^= E_KEY[8 * i + 3]; E_KEY[8 * i + 11] = t;   \
280     t  = E_KEY[8 * i + 4] ^ ls_box(t);    \
281     E_KEY[8 * i + 12] = t;                \
282     t ^= E_KEY[8 * i + 5]; E_KEY[8 * i + 13] = t;   \
283     t ^= E_KEY[8 * i + 6]; E_KEY[8 * i + 14] = t;   \
284     t ^= E_KEY[8 * i + 7]; E_KEY[8 * i + 15] = t;   \
285 }
286 
287 /* Tells whether the ACE is capable to generate
288    the extended key for a given key_len. */
289 static inline int
290 aes_hw_extkey_available(uint8_t key_len)
291 {
292 	/* TODO: We should check the actual CPU model/stepping
293 	         as it's possible that the capability will be
294 	         added in the next CPU revisions. */
295 	if (key_len == 16)
296 		return 1;
297 	return 0;
298 }
299 
300 static inline struct aes_ctx *aes_ctx_common(void *ctx)
301 {
302 	unsigned long addr = (unsigned long)ctx;
303 	unsigned long align = PADLOCK_ALIGNMENT;
304 
305 	if (align <= crypto_tfm_ctx_alignment())
306 		align = 1;
307 	return (struct aes_ctx *)ALIGN(addr, align);
308 }
309 
310 static inline struct aes_ctx *aes_ctx(struct crypto_tfm *tfm)
311 {
312 	return aes_ctx_common(crypto_tfm_ctx(tfm));
313 }
314 
315 static inline struct aes_ctx *blk_aes_ctx(struct crypto_blkcipher *tfm)
316 {
317 	return aes_ctx_common(crypto_blkcipher_ctx(tfm));
318 }
319 
320 static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
321 		       unsigned int key_len)
322 {
323 	struct aes_ctx *ctx = aes_ctx(tfm);
324 	const __le32 *key = (const __le32 *)in_key;
325 	u32 *flags = &tfm->crt_flags;
326 	uint32_t i, t, u, v, w;
327 	uint32_t P[AES_EXTENDED_KEY_SIZE];
328 	uint32_t rounds;
329 
330 	if (key_len % 8) {
331 		*flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
332 		return -EINVAL;
333 	}
334 
335 	ctx->key_length = key_len;
336 
337 	/*
338 	 * If the hardware is capable of generating the extended key
339 	 * itself we must supply the plain key for both encryption
340 	 * and decryption.
341 	 */
342 	ctx->D = ctx->E;
343 
344 	E_KEY[0] = le32_to_cpu(key[0]);
345 	E_KEY[1] = le32_to_cpu(key[1]);
346 	E_KEY[2] = le32_to_cpu(key[2]);
347 	E_KEY[3] = le32_to_cpu(key[3]);
348 
349 	/* Prepare control words. */
350 	memset(&ctx->cword, 0, sizeof(ctx->cword));
351 
352 	ctx->cword.decrypt.encdec = 1;
353 	ctx->cword.encrypt.rounds = 10 + (key_len - 16) / 4;
354 	ctx->cword.decrypt.rounds = ctx->cword.encrypt.rounds;
355 	ctx->cword.encrypt.ksize = (key_len - 16) / 8;
356 	ctx->cword.decrypt.ksize = ctx->cword.encrypt.ksize;
357 
358 	/* Don't generate extended keys if the hardware can do it. */
359 	if (aes_hw_extkey_available(key_len))
360 		return 0;
361 
362 	ctx->D = ctx->d_data;
363 	ctx->cword.encrypt.keygen = 1;
364 	ctx->cword.decrypt.keygen = 1;
365 
366 	switch (key_len) {
367 	case 16:
368 		t = E_KEY[3];
369 		for (i = 0; i < 10; ++i)
370 			loop4 (i);
371 		break;
372 
373 	case 24:
374 		E_KEY[4] = le32_to_cpu(key[4]);
375 		t = E_KEY[5] = le32_to_cpu(key[5]);
376 		for (i = 0; i < 8; ++i)
377 			loop6 (i);
378 		break;
379 
380 	case 32:
381 		E_KEY[4] = le32_to_cpu(key[4]);
382 		E_KEY[5] = le32_to_cpu(key[5]);
383 		E_KEY[6] = le32_to_cpu(key[6]);
384 		t = E_KEY[7] = le32_to_cpu(key[7]);
385 		for (i = 0; i < 7; ++i)
386 			loop8 (i);
387 		break;
388 	}
389 
390 	D_KEY[0] = E_KEY[0];
391 	D_KEY[1] = E_KEY[1];
392 	D_KEY[2] = E_KEY[2];
393 	D_KEY[3] = E_KEY[3];
394 
395 	for (i = 4; i < key_len + 24; ++i) {
396 		imix_col (D_KEY[i], E_KEY[i]);
397 	}
398 
399 	/* PadLock needs a different format of the decryption key. */
400 	rounds = 10 + (key_len - 16) / 4;
401 
402 	for (i = 0; i < rounds; i++) {
403 		P[((i + 1) * 4) + 0] = D_KEY[((rounds - i - 1) * 4) + 0];
404 		P[((i + 1) * 4) + 1] = D_KEY[((rounds - i - 1) * 4) + 1];
405 		P[((i + 1) * 4) + 2] = D_KEY[((rounds - i - 1) * 4) + 2];
406 		P[((i + 1) * 4) + 3] = D_KEY[((rounds - i - 1) * 4) + 3];
407 	}
408 
409 	P[0] = E_KEY[(rounds * 4) + 0];
410 	P[1] = E_KEY[(rounds * 4) + 1];
411 	P[2] = E_KEY[(rounds * 4) + 2];
412 	P[3] = E_KEY[(rounds * 4) + 3];
413 
414 	memcpy(D_KEY, P, AES_EXTENDED_KEY_SIZE_B);
415 
416 	return 0;
417 }
418 
419 /* ====== Encryption/decryption routines ====== */
420 
421 /* These are the real call to PadLock. */
422 static inline void padlock_xcrypt_ecb(const u8 *input, u8 *output, void *key,
423 				      void *control_word, u32 count)
424 {
425 	asm volatile ("pushfl; popfl");		/* enforce key reload. */
426 	asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"	/* rep xcryptecb */
427 		      : "+S"(input), "+D"(output)
428 		      : "d"(control_word), "b"(key), "c"(count));
429 }
430 
431 static inline u8 *padlock_xcrypt_cbc(const u8 *input, u8 *output, void *key,
432 				     u8 *iv, void *control_word, u32 count)
433 {
434 	/* Enforce key reload. */
435 	asm volatile ("pushfl; popfl");
436 	/* rep xcryptcbc */
437 	asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"
438 		      : "+S" (input), "+D" (output), "+a" (iv)
439 		      : "d" (control_word), "b" (key), "c" (count));
440 	return iv;
441 }
442 
443 static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
444 {
445 	struct aes_ctx *ctx = aes_ctx(tfm);
446 	padlock_xcrypt_ecb(in, out, ctx->E, &ctx->cword.encrypt, 1);
447 }
448 
449 static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
450 {
451 	struct aes_ctx *ctx = aes_ctx(tfm);
452 	padlock_xcrypt_ecb(in, out, ctx->D, &ctx->cword.decrypt, 1);
453 }
454 
455 static struct crypto_alg aes_alg = {
456 	.cra_name		=	"aes",
457 	.cra_driver_name	=	"aes-padlock",
458 	.cra_priority		=	PADLOCK_CRA_PRIORITY,
459 	.cra_flags		=	CRYPTO_ALG_TYPE_CIPHER,
460 	.cra_blocksize		=	AES_BLOCK_SIZE,
461 	.cra_ctxsize		=	sizeof(struct aes_ctx),
462 	.cra_alignmask		=	PADLOCK_ALIGNMENT - 1,
463 	.cra_module		=	THIS_MODULE,
464 	.cra_list		=	LIST_HEAD_INIT(aes_alg.cra_list),
465 	.cra_u			=	{
466 		.cipher = {
467 			.cia_min_keysize	=	AES_MIN_KEY_SIZE,
468 			.cia_max_keysize	=	AES_MAX_KEY_SIZE,
469 			.cia_setkey	   	= 	aes_set_key,
470 			.cia_encrypt	 	=	aes_encrypt,
471 			.cia_decrypt	  	=	aes_decrypt,
472 		}
473 	}
474 };
475 
476 static int ecb_aes_encrypt(struct blkcipher_desc *desc,
477 			   struct scatterlist *dst, struct scatterlist *src,
478 			   unsigned int nbytes)
479 {
480 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
481 	struct blkcipher_walk walk;
482 	int err;
483 
484 	blkcipher_walk_init(&walk, dst, src, nbytes);
485 	err = blkcipher_walk_virt(desc, &walk);
486 
487 	while ((nbytes = walk.nbytes)) {
488 		padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
489 				   ctx->E, &ctx->cword.encrypt,
490 				   nbytes / AES_BLOCK_SIZE);
491 		nbytes &= AES_BLOCK_SIZE - 1;
492 		err = blkcipher_walk_done(desc, &walk, nbytes);
493 	}
494 
495 	return err;
496 }
497 
498 static int ecb_aes_decrypt(struct blkcipher_desc *desc,
499 			   struct scatterlist *dst, struct scatterlist *src,
500 			   unsigned int nbytes)
501 {
502 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
503 	struct blkcipher_walk walk;
504 	int err;
505 
506 	blkcipher_walk_init(&walk, dst, src, nbytes);
507 	err = blkcipher_walk_virt(desc, &walk);
508 
509 	while ((nbytes = walk.nbytes)) {
510 		padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
511 				   ctx->D, &ctx->cword.decrypt,
512 				   nbytes / AES_BLOCK_SIZE);
513 		nbytes &= AES_BLOCK_SIZE - 1;
514 		err = blkcipher_walk_done(desc, &walk, nbytes);
515 	}
516 
517 	return err;
518 }
519 
520 static struct crypto_alg ecb_aes_alg = {
521 	.cra_name		=	"ecb(aes)",
522 	.cra_driver_name	=	"ecb-aes-padlock",
523 	.cra_priority		=	PADLOCK_COMPOSITE_PRIORITY,
524 	.cra_flags		=	CRYPTO_ALG_TYPE_BLKCIPHER,
525 	.cra_blocksize		=	AES_BLOCK_SIZE,
526 	.cra_ctxsize		=	sizeof(struct aes_ctx),
527 	.cra_alignmask		=	PADLOCK_ALIGNMENT - 1,
528 	.cra_type		=	&crypto_blkcipher_type,
529 	.cra_module		=	THIS_MODULE,
530 	.cra_list		=	LIST_HEAD_INIT(ecb_aes_alg.cra_list),
531 	.cra_u			=	{
532 		.blkcipher = {
533 			.min_keysize		=	AES_MIN_KEY_SIZE,
534 			.max_keysize		=	AES_MAX_KEY_SIZE,
535 			.setkey	   		= 	aes_set_key,
536 			.encrypt		=	ecb_aes_encrypt,
537 			.decrypt		=	ecb_aes_decrypt,
538 		}
539 	}
540 };
541 
542 static int cbc_aes_encrypt(struct blkcipher_desc *desc,
543 			   struct scatterlist *dst, struct scatterlist *src,
544 			   unsigned int nbytes)
545 {
546 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
547 	struct blkcipher_walk walk;
548 	int err;
549 
550 	blkcipher_walk_init(&walk, dst, src, nbytes);
551 	err = blkcipher_walk_virt(desc, &walk);
552 
553 	while ((nbytes = walk.nbytes)) {
554 		u8 *iv = padlock_xcrypt_cbc(walk.src.virt.addr,
555 					    walk.dst.virt.addr, ctx->E,
556 					    walk.iv, &ctx->cword.encrypt,
557 					    nbytes / AES_BLOCK_SIZE);
558 		memcpy(walk.iv, iv, AES_BLOCK_SIZE);
559 		nbytes &= AES_BLOCK_SIZE - 1;
560 		err = blkcipher_walk_done(desc, &walk, nbytes);
561 	}
562 
563 	return err;
564 }
565 
566 static int cbc_aes_decrypt(struct blkcipher_desc *desc,
567 			   struct scatterlist *dst, struct scatterlist *src,
568 			   unsigned int nbytes)
569 {
570 	struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
571 	struct blkcipher_walk walk;
572 	int err;
573 
574 	blkcipher_walk_init(&walk, dst, src, nbytes);
575 	err = blkcipher_walk_virt(desc, &walk);
576 
577 	while ((nbytes = walk.nbytes)) {
578 		padlock_xcrypt_cbc(walk.src.virt.addr, walk.dst.virt.addr,
579 				   ctx->D, walk.iv, &ctx->cword.decrypt,
580 				   nbytes / AES_BLOCK_SIZE);
581 		nbytes &= AES_BLOCK_SIZE - 1;
582 		err = blkcipher_walk_done(desc, &walk, nbytes);
583 	}
584 
585 	return err;
586 }
587 
588 static struct crypto_alg cbc_aes_alg = {
589 	.cra_name		=	"cbc(aes)",
590 	.cra_driver_name	=	"cbc-aes-padlock",
591 	.cra_priority		=	PADLOCK_COMPOSITE_PRIORITY,
592 	.cra_flags		=	CRYPTO_ALG_TYPE_BLKCIPHER,
593 	.cra_blocksize		=	AES_BLOCK_SIZE,
594 	.cra_ctxsize		=	sizeof(struct aes_ctx),
595 	.cra_alignmask		=	PADLOCK_ALIGNMENT - 1,
596 	.cra_type		=	&crypto_blkcipher_type,
597 	.cra_module		=	THIS_MODULE,
598 	.cra_list		=	LIST_HEAD_INIT(cbc_aes_alg.cra_list),
599 	.cra_u			=	{
600 		.blkcipher = {
601 			.min_keysize		=	AES_MIN_KEY_SIZE,
602 			.max_keysize		=	AES_MAX_KEY_SIZE,
603 			.ivsize			=	AES_BLOCK_SIZE,
604 			.setkey	   		= 	aes_set_key,
605 			.encrypt		=	cbc_aes_encrypt,
606 			.decrypt		=	cbc_aes_decrypt,
607 		}
608 	}
609 };
610 
611 static int __init padlock_init(void)
612 {
613 	int ret;
614 
615 	if (!cpu_has_xcrypt) {
616 		printk(KERN_ERR PFX "VIA PadLock not detected.\n");
617 		return -ENODEV;
618 	}
619 
620 	if (!cpu_has_xcrypt_enabled) {
621 		printk(KERN_ERR PFX "VIA PadLock detected, but not enabled. Hmm, strange...\n");
622 		return -ENODEV;
623 	}
624 
625 	gen_tabs();
626 	if ((ret = crypto_register_alg(&aes_alg)))
627 		goto aes_err;
628 
629 	if ((ret = crypto_register_alg(&ecb_aes_alg)))
630 		goto ecb_aes_err;
631 
632 	if ((ret = crypto_register_alg(&cbc_aes_alg)))
633 		goto cbc_aes_err;
634 
635 	printk(KERN_NOTICE PFX "Using VIA PadLock ACE for AES algorithm.\n");
636 
637 out:
638 	return ret;
639 
640 cbc_aes_err:
641 	crypto_unregister_alg(&ecb_aes_alg);
642 ecb_aes_err:
643 	crypto_unregister_alg(&aes_alg);
644 aes_err:
645 	printk(KERN_ERR PFX "VIA PadLock AES initialization failed.\n");
646 	goto out;
647 }
648 
649 static void __exit padlock_fini(void)
650 {
651 	crypto_unregister_alg(&cbc_aes_alg);
652 	crypto_unregister_alg(&ecb_aes_alg);
653 	crypto_unregister_alg(&aes_alg);
654 }
655 
656 module_init(padlock_init);
657 module_exit(padlock_fini);
658 
659 MODULE_DESCRIPTION("VIA PadLock AES algorithm support");
660 MODULE_LICENSE("GPL");
661 MODULE_AUTHOR("Michal Ludvig");
662 
663 MODULE_ALIAS("aes");
664