summaryrefslogtreecommitdiff
path: root/lib/842/842_compress.c
blob: 4051339bdfbda6e6869d7f7c669672ba65f3d3f1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
/*
 * 842 Software Compression
 *
 * Copyright (C) 2015 Dan Streetman, IBM Corp
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * See 842.h for details of the 842 compressed format.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#define MODULE_NAME "842_compress"

#include <linux/hashtable.h>

#include "842.h"
#include "842_debugfs.h"

#define SW842_HASHTABLE8_BITS	(10)
#define SW842_HASHTABLE4_BITS	(11)
#define SW842_HASHTABLE2_BITS	(10)

/* By default, we allow compressing input buffers of any length, but we must
 * use the non-standard "short data" template so the decompressor can correctly
 * reproduce the uncompressed data buffer at the right length.  However the
 * hardware 842 compressor will not recognize the "short data" template, and
 * will fail to decompress any compressed buffer containing it (I have no idea
 * why anyone would want to use software to compress and hardware to decompress
 * but that's beside the point).  This parameter forces the compression
 * function to simply reject any input buffer that isn't a multiple of 8 bytes
 * long, instead of using the "short data" template, so that all compressed
 * buffers produced by this function will be decompressable by the 842 hardware
 * decompressor.  Unless you have a specific need for that, leave this disabled
 * so that any length buffer can be compressed.
 */
static bool sw842_strict;
module_param_named(strict, sw842_strict, bool, 0644);

static u8 comp_ops[OPS_MAX][5] = { /* params size in bits */
	{ I8, N0, N0, N0, 0x19 }, /* 8 */
	{ I4, I4, N0, N0, 0x18 }, /* 18 */
	{ I4, I2, I2, N0, 0x17 }, /* 25 */
	{ I2, I2, I4, N0, 0x13 }, /* 25 */
	{ I2, I2, I2, I2, 0x12 }, /* 32 */
	{ I4, I2, D2, N0, 0x16 }, /* 33 */
	{ I4, D2, I2, N0, 0x15 }, /* 33 */
	{ I2, D2, I4, N0, 0x0e }, /* 33 */
	{ D2, I2, I4, N0, 0x09 }, /* 33 */
	{ I2, I2, I2, D2, 0x11 }, /* 40 */
	{ I2, I2, D2, I2, 0x10 }, /* 40 */
	{ I2, D2, I2, I2, 0x0d }, /* 40 */
	{ D2, I2, I2, I2, 0x08 }, /* 40 */
	{ I4, D4, N0, N0, 0x14 }, /* 41 */
	{ D4, I4, N0, N0, 0x04 }, /* 41 */
	{ I2, I2, D4, N0, 0x0f }, /* 48 */
	{ I2, D2, I2, D2, 0x0c }, /* 48 */
	{ I2, D4, I2, N0, 0x0b }, /* 48 */
	{ D2, I2, I2, D2, 0x07 }, /* 48 */
	{ D2, I2, D2, I2, 0x06 }, /* 48 */
	{ D4, I2, I2, N0, 0x03 }, /* 48 */
	{ I2, D2, D4, N0, 0x0a }, /* 56 */
	{ D2, I2, D4, N0, 0x05 }, /* 56 */
	{ D4, I2, D2, N0, 0x02 }, /* 56 */
	{ D4, D2, I2, N0, 0x01 }, /* 56 */
	{ D8, N0, N0, N0, 0x00 }, /* 64 */
};

struct sw842_hlist_node8 {
	struct hlist_node node;
	u64 data;
	u8 index;
};

struct sw842_hlist_node4 {
	struct hlist_node node;
	u32 data;
	u16 index;
};

struct sw842_hlist_node2 {
	struct hlist_node node;
	u16 data;
	u8 index;
};

#define INDEX_NOT_FOUND		(-1)
#define INDEX_NOT_CHECKED	(-2)

struct sw842_param {
	u8 *in;
	u8 *instart;
	u64 ilen;
	u8 *out;
	u64 olen;
	u8 bit;
	u64 data8[1];
	u32 data4[2];
	u16 data2[4];
	int index8[1];
	int index4[2];
	int index2[4];
	DECLARE_HASHTABLE(htable8, SW842_HASHTABLE8_BITS);
	DECLARE_HASHTABLE(htable4, SW842_HASHTABLE4_BITS);
	DECLARE_HASHTABLE(htable2, SW842_HASHTABLE2_BITS);
	struct sw842_hlist_node8 node8[1 << I8_BITS];
	struct sw842_hlist_node4 node4[1 << I4_BITS];
	struct sw842_hlist_node2 node2[1 << I2_BITS];
};

#define get_input_data(p, o, b)						\
	be##b##_to_cpu(get_unaligned((__be##b *)((p)->in + (o))))

#define init_hashtable_nodes(p, b)	do {			\
	int _i;							\
	hash_init((p)->htable##b);				\
	for (_i = 0; _i < ARRAY_SIZE((p)->node##b); _i++) {	\
		(p)->node##b[_i].index = _i;			\
		(p)->node##b[_i].data = 0;			\
		INIT_HLIST_NODE(&(p)->node##b[_i].node);	\
	}							\
} while (0)

#define find_index(p, b, n)	({					\
	struct sw842_hlist_node##b *_n;					\
	p->index##b[n] = INDEX_NOT_FOUND;				\
	hash_for_each_possible(p->htable##b, _n, node, p->data##b[n]) {	\
		if (p->data##b[n] == _n->data) {			\
			p->index##b[n] = _n->index;			\
			break;						\
		}							\
	}								\
	p->index##b[n] >= 0;						\
})

#define check_index(p, b, n)			\
	((p)->index##b[n] == INDEX_NOT_CHECKED	\
	 ? find_index(p, b, n)			\
	 : (p)->index##b[n] >= 0)

#define replace_hash(p, b, i, d)	do {				\
	struct sw842_hlist_node##b *_n = &(p)->node##b[(i)+(d)];	\
	hash_del(&_n->node);						\
	_n->data = (p)->data##b[d];					\
	pr_debug("add hash index%x %x pos %x data %lx\n", b,		\
		 (unsigned int)_n->index,				\
		 (unsigned int)((p)->in - (p)->instart),		\
		 (unsigned long)_n->data);				\
	hash_add((p)->htable##b, &_n->node, _n->data);			\
} while (0)

static u8 bmask[8] = { 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe };

static int add_bits(struct sw842_param *p, u64 d, u8 n);

static int __split_add_bits(struct sw842_param *p, u64 d, u8 n, u8 s)
{
	int ret;

	if (n <= s)
		return -EINVAL;

	ret = add_bits(p, d >> s, n - s);
	if (ret)
		return ret;
	return add_bits(p, d & GENMASK_ULL(s - 1, 0), s);
}

static int add_bits(struct sw842_param *p, u64 d, u8 n)
{
	int b = p->bit, bits = b + n, s = round_up(bits, 8) - bits;
	u64 o;
	u8 *out = p->out;

	pr_debug("add %u bits %lx\n", (unsigned char)n, (unsigned long)d);

	if (n > 64)
		return -EINVAL;

	/* split this up if writing to > 8 bytes (i.e. n == 64 && p->bit > 0),
	 * or if we're at the end of the output buffer and would write past end
	 */
	if (bits > 64)
		return __split_add_bits(p, d, n, 32);
	else if (p->olen < 8 && bits > 32 && bits <= 56)
		return __split_add_bits(p, d, n, 16);
	else if (p->olen < 4 && bits > 16 && bits <= 24)
		return __split_add_bits(p, d, n, 8);

	if (DIV_ROUND_UP(bits, 8) > p->olen)
		return -ENOSPC;

	o = *out & bmask[b];
	d <<= s;

	if (bits <= 8)
		*out = o | d;
	else if (bits <= 16)
		put_unaligned(cpu_to_be16(o << 8 | d), (__be16 *)out);
	else if (bits <= 24)
		put_unaligned(cpu_to_be32(o << 24 | d << 8), (__be32 *)out);
	else if (bits <= 32)
		put_unaligned(cpu_to_be32(o << 24 | d), (__be32 *)out);
	else if (bits <= 40)
		put_unaligned(cpu_to_be64(o << 56 | d << 24), (__be64 *)out);
	else if (bits <= 48)
		put_unaligned(cpu_to_be64(o << 56 | d << 16), (__be64 *)out);
	else if (bits <= 56)
		put_unaligned(cpu_to_be64(o << 56 | d << 8), (__be64 *)out);
	else
		put_unaligned(cpu_to_be64(o << 56 | d), (__be64 *)out);

	p->bit += n;

	if (p->bit > 7) {
		p->out += p->bit / 8;
		p->olen -= p->bit / 8;
		p->bit %= 8;
	}

	return 0;
}

static int add_template(struct sw842_param *p, u8 c)
{
	int ret, i, b = 0;
	u8 *t = comp_ops[c];
	bool inv = false;

	if (c >= OPS_MAX)
		return -EINVAL;

	pr_debug("template %x\n", t[4]);

	ret = add_bits(p, t[4], OP_BITS);
	if (ret)
		return ret;

	for (i = 0; i < 4; i++) {
		pr_debug("op %x\n", t[i]);

		switch (t[i] & OP_AMOUNT) {
		case OP_AMOUNT_8:
			if (b)
				inv = true;
			else if (t[i] & OP_ACTION_INDEX)
				ret = add_bits(p, p->index8[0], I8_BITS);
			else if (t[i] & OP_ACTION_DATA)
				ret = add_bits(p, p->data8[0], 64);
			else
				inv = true;
			break;
		case OP_AMOUNT_4:
			if (b == 2 && t[i] & OP_ACTION_DATA)
				ret = add_bits(p, get_input_data(p, 2, 32), 32);
			else if (b != 0 && b != 4)
				inv = true;
			else if (t[i] & OP_ACTION_INDEX)
				ret = add_bits(p, p->index4[b >> 2], I4_BITS);
			else if (t[i] & OP_ACTION_DATA)
				ret = add_bits(p, p->data4[b >> 2], 32);
			else
				inv = true;
			break;
		case OP_AMOUNT_2:
			if (b != 0 && b != 2 && b != 4 && b != 6)
				inv = true;
			if (t[i] & OP_ACTION_INDEX)
				ret = add_bits(p, p->index2[b >> 1], I2_BITS);
			else if (t[i] & OP_ACTION_DATA)
				ret = add_bits(p, p->data2[b >> 1], 16);
			else
				inv = true;
			break;
		case OP_AMOUNT_0:
			inv = (b != 8) || !(t[i] & OP_ACTION_NOOP);
			break;
		default:
			inv = true;
			break;
		}

		if (ret)
			return ret;

		if (inv) {
			pr_err("Invalid templ %x op %d : %x %x %x %x\n",
			       c, i, t[0], t[1], t[2], t[3]);
			return -EINVAL;
		}

		b += t[i] & OP_AMOUNT;
	}

	if (b != 8) {
		pr_err("Invalid template %x len %x : %x %x %x %x\n",
		       c, b, t[0], t[1], t[2], t[3]);
		return -EINVAL;
	}

	if (sw842_template_counts)
		atomic_inc(&template_count[t[4]]);

	return 0;
}

static int add_repeat_template(struct sw842_param *p, u8 r)
{
	int ret;

	/* repeat param is 0-based */
	if (!r || --r > REPEAT_BITS_MAX)
		return -EINVAL;

	ret = add_bits(p, OP_REPEAT, OP_BITS);
	if (ret)
		return ret;

	ret = add_bits(p, r, REPEAT_BITS);
	if (ret)
		return ret;

	if (sw842_template_counts)
		atomic_inc(&template_repeat_count);

	return 0;
}

static int add_short_data_template(struct sw842_param *p, u8 b)
{
	int ret, i;

	if (!b || b > SHORT_DATA_BITS_MAX)
		return -EINVAL;

	ret = add_bits(p, OP_SHORT_DATA, OP_BITS);
	if (ret)
		return ret;

	ret = add_bits(p, b, SHORT_DATA_BITS);
	if (ret)
		return ret;

	for (i = 0; i < b; i++) {
		ret = add_bits(p, p->in[i], 8);
		if (ret)
			return ret;
	}

	if (sw842_template_counts)
		atomic_inc(&template_short_data_count);

	return 0;
}

static int add_zeros_template(struct sw842_param *p)
{
	int ret = add_bits(p, OP_ZEROS, OP_BITS);

	if (ret)
		return ret;

	if (sw842_template_counts)
		atomic_inc(&template_zeros_count);

	return 0;
}

static int add_end_template(struct sw842_param *p)
{
	int ret = add_bits(p, OP_END, OP_BITS);

	if (ret)
		return ret;

	if (sw842_template_counts)
		atomic_inc(&template_end_count);

	return 0;
}

static bool check_template(struct sw842_param *p, u8 c)
{
	u8 *t = comp_ops[c];
	int i, match, b = 0;

	if (c >= OPS_MAX)
		return false;

	for (i = 0; i < 4; i++) {
		if (t[i] & OP_ACTION_INDEX) {
			if (t[i] & OP_AMOUNT_2)
				match = check_index(p, 2, b >> 1);
			else if (t[i] & OP_AMOUNT_4)
				match = check_index(p, 4, b >> 2);
			else if (t[i] & OP_AMOUNT_8)
				match = check_index(p, 8, 0);
			else
				return false;
			if (!match)
				return false;
		}

		b += t[i] & OP_AMOUNT;
	}

	return true;
}

static void get_next_data(struct sw842_param *p)
{
	p->data8[0] = get_input_data(p, 0, 64);
	p->data4[0] = get_input_data(p, 0, 32);
	p->data4[1] = get_input_data(p, 4, 32);
	p->data2[0] = get_input_data(p, 0, 16);
	p->data2[1] = get_input_data(p, 2, 16);
	p->data2[2] = get_input_data(p, 4, 16);
	p->data2[3] = get_input_data(p, 6, 16);
}

/* update the hashtable entries.
 * only call this after finding/adding the current template
 * the dataN fields for the current 8 byte block must be already updated
 */
static void update_hashtables(struct sw842_param *p)
{
	u64 pos = p->in - p->instart;
	u64 n8 = (pos >> 3) % (1 << I8_BITS);
	u64 n4 = (pos >> 2) % (1 << I4_BITS);
	u64 n2 = (pos >> 1) % (1 << I2_BITS);

	replace_hash(p, 8, n8, 0);
	replace_hash(p, 4, n4, 0);
	replace_hash(p, 4, n4, 1);
	replace_hash(p, 2, n2, 0);
	replace_hash(p, 2, n2, 1);
	replace_hash(p, 2, n2, 2);
	replace_hash(p, 2, n2, 3);
}

/* find the next template to use, and add it
 * the p->dataN fields must already be set for the current 8 byte block
 */
static int process_next(struct sw842_param *p)
{
	int ret, i;

	p->index8[0] = INDEX_NOT_CHECKED;
	p->index4[0] = INDEX_NOT_CHECKED;
	p->index4[1] = INDEX_NOT_CHECKED;
	p->index2[0] = INDEX_NOT_CHECKED;
	p->index2[1] = INDEX_NOT_CHECKED;
	p->index2[2] = INDEX_NOT_CHECKED;
	p->index2[3] = INDEX_NOT_CHECKED;

	/* check up to OPS_MAX - 1; last op is our fallback */
	for (i = 0; i < OPS_MAX - 1; i++) {
		if (check_template(p, i))
			break;
	}

	ret = add_template(p, i);
	if (ret)
		return ret;

	return 0;
}

/**
 * sw842_compress
 *
 * Compress the uncompressed buffer of length @ilen at @in to the output buffer
 * @out, using no more than @olen bytes, using the 842 compression format.
 *
 * Returns: 0 on success, error on failure.  The @olen parameter
 * will contain the number of output bytes written on success, or
 * 0 on error.
 */
int sw842_compress(const u8 *in, unsigned int ilen,
		   u8 *out, unsigned int *olen, void *wmem)
{
	struct sw842_param *p = (struct sw842_param *)wmem;
	int ret;
	u64 last, next, pad, total;
	u8 repeat_count = 0;
	u32 crc;

	BUILD_BUG_ON(sizeof(*p) > SW842_MEM_COMPRESS);

	init_hashtable_nodes(p, 8);
	init_hashtable_nodes(p, 4);
	init_hashtable_nodes(p, 2);

	p->in = (u8 *)in;
	p->instart = p->in;
	p->ilen = ilen;
	p->out = out;
	p->olen = *olen;
	p->bit = 0;

	total = p->olen;

	*olen = 0;

	/* if using strict mode, we can only compress a multiple of 8 */
	if (sw842_strict && (ilen % 8)) {
		pr_err("Using strict mode, can't compress len %d\n", ilen);
		return -EINVAL;
	}

	/* let's compress at least 8 bytes, mkay? */
	if (unlikely(ilen < 8))
		goto skip_comp;

	/* make initial 'last' different so we don't match the first time */
	last = ~get_unaligned((u64 *)p->in);

	while (p->ilen > 7) {
		next = get_unaligned((u64 *)p->in);

		/* must get the next data, as we need to update the hashtable
		 * entries with the new data every time
		 */
		get_next_data(p);

		/* we don't care about endianness in last or next;
		 * we're just comparing 8 bytes to another 8 bytes,
		 * they're both the same endianness
		 */
		if (next == last) {
			/* repeat count bits are 0-based, so we stop at +1 */
			if (++repeat_count <= REPEAT_BITS_MAX)
				goto repeat;
		}
		if (repeat_count) {
			ret = add_repeat_template(p, repeat_count);
			repeat_count = 0;
			if (next == last) /* reached max repeat bits */
				goto repeat;
		}

		if (next == 0)
			ret = add_zeros_template(p);
		else
			ret = process_next(p);

		if (ret)
			return ret;

repeat:
		last = next;
		update_hashtables(p);
		p->in += 8;
		p->ilen -= 8;
	}

	if (repeat_count) {
		ret = add_repeat_template(p, repeat_count);
		if (ret)
			return ret;
	}

skip_comp:
	if (p->ilen > 0) {
		ret = add_short_data_template(p, p->ilen);
		if (ret)
			return ret;

		p->in += p->ilen;
		p->ilen = 0;
	}

	ret = add_end_template(p);
	if (ret)
		return ret;

	/*
	 * crc(0:31) is appended to target data starting with the next
	 * bit after End of stream template.
	 * nx842 calculates CRC for data in big-endian format. So doing
	 * same here so that sw842 decompression can be used for both
	 * compressed data.
	 */
	crc = crc32_be(0, in, ilen);
	ret = add_bits(p, crc, CRC_BITS);
	if (ret)
		return ret;

	if (p->bit) {
		p->out++;
		p->olen--;
		p->bit = 0;
	}

	/* pad compressed length to multiple of 8 */
	pad = (8 - ((total - p->olen) % 8)) % 8;
	if (pad) {
		if (pad > p->olen) /* we were so close! */
			return -ENOSPC;
		memset(p->out, 0, pad);
		p->out += pad;
		p->olen -= pad;
	}

	if (unlikely((total - p->olen) > UINT_MAX))
		return -ENOSPC;

	*olen = total - p->olen;

	return 0;
}
EXPORT_SYMBOL_GPL(sw842_compress);

static int __init sw842_init(void)
{
	if (sw842_template_counts)
		sw842_debugfs_create();

	return 0;
}
module_init(sw842_init);

static void __exit sw842_exit(void)
{
	if (sw842_template_counts)
		sw842_debugfs_remove();
}
module_exit(sw842_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Software 842 Compressor");
MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");