1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * 842 Software Compression
4 *
5 * Copyright (C) 2015 Dan Streetman, IBM Corp
6 *
7 * See 842.h for details of the 842 compressed format.
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11#define MODULE_NAME "842_compress"
12
13#include <linux/hashtable.h>
14
15#include "842.h"
16#include "842_debugfs.h"
17
18#define SW842_HASHTABLE8_BITS	(10)
19#define SW842_HASHTABLE4_BITS	(11)
20#define SW842_HASHTABLE2_BITS	(10)
21
22/* By default, we allow compressing input buffers of any length, but we must
23 * use the non-standard "short data" template so the decompressor can correctly
24 * reproduce the uncompressed data buffer at the right length.  However the
25 * hardware 842 compressor will not recognize the "short data" template, and
26 * will fail to decompress any compressed buffer containing it (I have no idea
27 * why anyone would want to use software to compress and hardware to decompress
28 * but that's beside the point).  This parameter forces the compression
29 * function to simply reject any input buffer that isn't a multiple of 8 bytes
30 * long, instead of using the "short data" template, so that all compressed
31 * buffers produced by this function will be decompressable by the 842 hardware
32 * decompressor.  Unless you have a specific need for that, leave this disabled
33 * so that any length buffer can be compressed.
34 */
35static bool sw842_strict;
36module_param_named(strict, sw842_strict, bool, 0644);
37
38static u8 comp_ops[OPS_MAX][5] = { /* params size in bits */
39	{ I8, N0, N0, N0, 0x19 }, /* 8 */
40	{ I4, I4, N0, N0, 0x18 }, /* 18 */
41	{ I4, I2, I2, N0, 0x17 }, /* 25 */
42	{ I2, I2, I4, N0, 0x13 }, /* 25 */
43	{ I2, I2, I2, I2, 0x12 }, /* 32 */
44	{ I4, I2, D2, N0, 0x16 }, /* 33 */
45	{ I4, D2, I2, N0, 0x15 }, /* 33 */
46	{ I2, D2, I4, N0, 0x0e }, /* 33 */
47	{ D2, I2, I4, N0, 0x09 }, /* 33 */
48	{ I2, I2, I2, D2, 0x11 }, /* 40 */
49	{ I2, I2, D2, I2, 0x10 }, /* 40 */
50	{ I2, D2, I2, I2, 0x0d }, /* 40 */
51	{ D2, I2, I2, I2, 0x08 }, /* 40 */
52	{ I4, D4, N0, N0, 0x14 }, /* 41 */
53	{ D4, I4, N0, N0, 0x04 }, /* 41 */
54	{ I2, I2, D4, N0, 0x0f }, /* 48 */
55	{ I2, D2, I2, D2, 0x0c }, /* 48 */
56	{ I2, D4, I2, N0, 0x0b }, /* 48 */
57	{ D2, I2, I2, D2, 0x07 }, /* 48 */
58	{ D2, I2, D2, I2, 0x06 }, /* 48 */
59	{ D4, I2, I2, N0, 0x03 }, /* 48 */
60	{ I2, D2, D4, N0, 0x0a }, /* 56 */
61	{ D2, I2, D4, N0, 0x05 }, /* 56 */
62	{ D4, I2, D2, N0, 0x02 }, /* 56 */
63	{ D4, D2, I2, N0, 0x01 }, /* 56 */
64	{ D8, N0, N0, N0, 0x00 }, /* 64 */
65};
66
67struct sw842_hlist_node8 {
68	struct hlist_node node;
69	u64 data;
70	u8 index;
71};
72
73struct sw842_hlist_node4 {
74	struct hlist_node node;
75	u32 data;
76	u16 index;
77};
78
79struct sw842_hlist_node2 {
80	struct hlist_node node;
81	u16 data;
82	u8 index;
83};
84
85#define INDEX_NOT_FOUND		(-1)
86#define INDEX_NOT_CHECKED	(-2)
87
88struct sw842_param {
89	u8 *in;
90	u8 *instart;
91	u64 ilen;
92	u8 *out;
93	u64 olen;
94	u8 bit;
95	u64 data8[1];
96	u32 data4[2];
97	u16 data2[4];
98	int index8[1];
99	int index4[2];
100	int index2[4];
101	DECLARE_HASHTABLE(htable8, SW842_HASHTABLE8_BITS);
102	DECLARE_HASHTABLE(htable4, SW842_HASHTABLE4_BITS);
103	DECLARE_HASHTABLE(htable2, SW842_HASHTABLE2_BITS);
104	struct sw842_hlist_node8 node8[1 << I8_BITS];
105	struct sw842_hlist_node4 node4[1 << I4_BITS];
106	struct sw842_hlist_node2 node2[1 << I2_BITS];
107};
108
109#define get_input_data(p, o, b)						\
110	be##b##_to_cpu(get_unaligned((__be##b *)((p)->in + (o))))
111
112#define init_hashtable_nodes(p, b)	do {			\
113	int _i;							\
114	hash_init((p)->htable##b);				\
115	for (_i = 0; _i < ARRAY_SIZE((p)->node##b); _i++) {	\
116		(p)->node##b[_i].index = _i;			\
117		(p)->node##b[_i].data = 0;			\
118		INIT_HLIST_NODE(&(p)->node##b[_i].node);	\
119	}							\
120} while (0)
121
122#define find_index(p, b, n)	({					\
123	struct sw842_hlist_node##b *_n;					\
124	p->index##b[n] = INDEX_NOT_FOUND;				\
125	hash_for_each_possible(p->htable##b, _n, node, p->data##b[n]) {	\
126		if (p->data##b[n] == _n->data) {			\
127			p->index##b[n] = _n->index;			\
128			break;						\
129		}							\
130	}								\
131	p->index##b[n] >= 0;						\
132})
133
134#define check_index(p, b, n)			\
135	((p)->index##b[n] == INDEX_NOT_CHECKED	\
136	 ? find_index(p, b, n)			\
137	 : (p)->index##b[n] >= 0)
138
139#define replace_hash(p, b, i, d)	do {				\
140	struct sw842_hlist_node##b *_n = &(p)->node##b[(i)+(d)];	\
141	hash_del(&_n->node);						\
142	_n->data = (p)->data##b[d];					\
143	pr_debug("add hash index%x %x pos %x data %lx\n", b,		\
144		 (unsigned int)_n->index,				\
145		 (unsigned int)((p)->in - (p)->instart),		\
146		 (unsigned long)_n->data);				\
147	hash_add((p)->htable##b, &_n->node, _n->data);			\
148} while (0)
149
150static u8 bmask[8] = { 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe };
151
152static int add_bits(struct sw842_param *p, u64 d, u8 n);
153
154static int __split_add_bits(struct sw842_param *p, u64 d, u8 n, u8 s)
155{
156	int ret;
157
158	if (n <= s)
159		return -EINVAL;
160
161	ret = add_bits(p, d >> s, n - s);
162	if (ret)
163		return ret;
164	return add_bits(p, d & GENMASK_ULL(s - 1, 0), s);
165}
166
167static int add_bits(struct sw842_param *p, u64 d, u8 n)
168{
169	int b = p->bit, bits = b + n, s = round_up(bits, 8) - bits;
170	u64 o;
171	u8 *out = p->out;
172
173	pr_debug("add %u bits %lx\n", (unsigned char)n, (unsigned long)d);
174
175	if (n > 64)
176		return -EINVAL;
177
178	/* split this up if writing to > 8 bytes (i.e. n == 64 && p->bit > 0),
179	 * or if we're at the end of the output buffer and would write past end
180	 */
181	if (bits > 64)
182		return __split_add_bits(p, d, n, 32);
183	else if (p->olen < 8 && bits > 32 && bits <= 56)
184		return __split_add_bits(p, d, n, 16);
185	else if (p->olen < 4 && bits > 16 && bits <= 24)
186		return __split_add_bits(p, d, n, 8);
187
188	if (DIV_ROUND_UP(bits, 8) > p->olen)
189		return -ENOSPC;
190
191	o = *out & bmask[b];
192	d <<= s;
193
194	if (bits <= 8)
195		*out = o | d;
196	else if (bits <= 16)
197		put_unaligned(cpu_to_be16(o << 8 | d), (__be16 *)out);
198	else if (bits <= 24)
199		put_unaligned(cpu_to_be32(o << 24 | d << 8), (__be32 *)out);
200	else if (bits <= 32)
201		put_unaligned(cpu_to_be32(o << 24 | d), (__be32 *)out);
202	else if (bits <= 40)
203		put_unaligned(cpu_to_be64(o << 56 | d << 24), (__be64 *)out);
204	else if (bits <= 48)
205		put_unaligned(cpu_to_be64(o << 56 | d << 16), (__be64 *)out);
206	else if (bits <= 56)
207		put_unaligned(cpu_to_be64(o << 56 | d << 8), (__be64 *)out);
208	else
209		put_unaligned(cpu_to_be64(o << 56 | d), (__be64 *)out);
210
211	p->bit += n;
212
213	if (p->bit > 7) {
214		p->out += p->bit / 8;
215		p->olen -= p->bit / 8;
216		p->bit %= 8;
217	}
218
219	return 0;
220}
221
222static int add_template(struct sw842_param *p, u8 c)
223{
224	int ret, i, b = 0;
225	u8 *t = comp_ops[c];
226	bool inv = false;
227
228	if (c >= OPS_MAX)
229		return -EINVAL;
230
231	pr_debug("template %x\n", t[4]);
232
233	ret = add_bits(p, t[4], OP_BITS);
234	if (ret)
235		return ret;
236
237	for (i = 0; i < 4; i++) {
238		pr_debug("op %x\n", t[i]);
239
240		switch (t[i] & OP_AMOUNT) {
241		case OP_AMOUNT_8:
242			if (b)
243				inv = true;
244			else if (t[i] & OP_ACTION_INDEX)
245				ret = add_bits(p, p->index8[0], I8_BITS);
246			else if (t[i] & OP_ACTION_DATA)
247				ret = add_bits(p, p->data8[0], 64);
248			else
249				inv = true;
250			break;
251		case OP_AMOUNT_4:
252			if (b == 2 && t[i] & OP_ACTION_DATA)
253				ret = add_bits(p, get_input_data(p, 2, 32), 32);
254			else if (b != 0 && b != 4)
255				inv = true;
256			else if (t[i] & OP_ACTION_INDEX)
257				ret = add_bits(p, p->index4[b >> 2], I4_BITS);
258			else if (t[i] & OP_ACTION_DATA)
259				ret = add_bits(p, p->data4[b >> 2], 32);
260			else
261				inv = true;
262			break;
263		case OP_AMOUNT_2:
264			if (b != 0 && b != 2 && b != 4 && b != 6)
265				inv = true;
266			if (t[i] & OP_ACTION_INDEX)
267				ret = add_bits(p, p->index2[b >> 1], I2_BITS);
268			else if (t[i] & OP_ACTION_DATA)
269				ret = add_bits(p, p->data2[b >> 1], 16);
270			else
271				inv = true;
272			break;
273		case OP_AMOUNT_0:
274			inv = (b != 8) || !(t[i] & OP_ACTION_NOOP);
275			break;
276		default:
277			inv = true;
278			break;
279		}
280
281		if (ret)
282			return ret;
283
284		if (inv) {
285			pr_err("Invalid templ %x op %d : %x %x %x %x\n",
286			       c, i, t[0], t[1], t[2], t[3]);
287			return -EINVAL;
288		}
289
290		b += t[i] & OP_AMOUNT;
291	}
292
293	if (b != 8) {
294		pr_err("Invalid template %x len %x : %x %x %x %x\n",
295		       c, b, t[0], t[1], t[2], t[3]);
296		return -EINVAL;
297	}
298
299	if (sw842_template_counts)
300		atomic_inc(&template_count[t[4]]);
301
302	return 0;
303}
304
305static int add_repeat_template(struct sw842_param *p, u8 r)
306{
307	int ret;
308
309	/* repeat param is 0-based */
310	if (!r || --r > REPEAT_BITS_MAX)
311		return -EINVAL;
312
313	ret = add_bits(p, OP_REPEAT, OP_BITS);
314	if (ret)
315		return ret;
316
317	ret = add_bits(p, r, REPEAT_BITS);
318	if (ret)
319		return ret;
320
321	if (sw842_template_counts)
322		atomic_inc(&template_repeat_count);
323
324	return 0;
325}
326
327static int add_short_data_template(struct sw842_param *p, u8 b)
328{
329	int ret, i;
330
331	if (!b || b > SHORT_DATA_BITS_MAX)
332		return -EINVAL;
333
334	ret = add_bits(p, OP_SHORT_DATA, OP_BITS);
335	if (ret)
336		return ret;
337
338	ret = add_bits(p, b, SHORT_DATA_BITS);
339	if (ret)
340		return ret;
341
342	for (i = 0; i < b; i++) {
343		ret = add_bits(p, p->in[i], 8);
344		if (ret)
345			return ret;
346	}
347
348	if (sw842_template_counts)
349		atomic_inc(&template_short_data_count);
350
351	return 0;
352}
353
354static int add_zeros_template(struct sw842_param *p)
355{
356	int ret = add_bits(p, OP_ZEROS, OP_BITS);
357
358	if (ret)
359		return ret;
360
361	if (sw842_template_counts)
362		atomic_inc(&template_zeros_count);
363
364	return 0;
365}
366
367static int add_end_template(struct sw842_param *p)
368{
369	int ret = add_bits(p, OP_END, OP_BITS);
370
371	if (ret)
372		return ret;
373
374	if (sw842_template_counts)
375		atomic_inc(&template_end_count);
376
377	return 0;
378}
379
380static bool check_template(struct sw842_param *p, u8 c)
381{
382	u8 *t = comp_ops[c];
383	int i, match, b = 0;
384
385	if (c >= OPS_MAX)
386		return false;
387
388	for (i = 0; i < 4; i++) {
389		if (t[i] & OP_ACTION_INDEX) {
390			if (t[i] & OP_AMOUNT_2)
391				match = check_index(p, 2, b >> 1);
392			else if (t[i] & OP_AMOUNT_4)
393				match = check_index(p, 4, b >> 2);
394			else if (t[i] & OP_AMOUNT_8)
395				match = check_index(p, 8, 0);
396			else
397				return false;
398			if (!match)
399				return false;
400		}
401
402		b += t[i] & OP_AMOUNT;
403	}
404
405	return true;
406}
407
408static void get_next_data(struct sw842_param *p)
409{
410	p->data8[0] = get_input_data(p, 0, 64);
411	p->data4[0] = get_input_data(p, 0, 32);
412	p->data4[1] = get_input_data(p, 4, 32);
413	p->data2[0] = get_input_data(p, 0, 16);
414	p->data2[1] = get_input_data(p, 2, 16);
415	p->data2[2] = get_input_data(p, 4, 16);
416	p->data2[3] = get_input_data(p, 6, 16);
417}
418
419/* update the hashtable entries.
420 * only call this after finding/adding the current template
421 * the dataN fields for the current 8 byte block must be already updated
422 */
423static void update_hashtables(struct sw842_param *p)
424{
425	u64 pos = p->in - p->instart;
426	u64 n8 = (pos >> 3) % (1 << I8_BITS);
427	u64 n4 = (pos >> 2) % (1 << I4_BITS);
428	u64 n2 = (pos >> 1) % (1 << I2_BITS);
429
430	replace_hash(p, 8, n8, 0);
431	replace_hash(p, 4, n4, 0);
432	replace_hash(p, 4, n4, 1);
433	replace_hash(p, 2, n2, 0);
434	replace_hash(p, 2, n2, 1);
435	replace_hash(p, 2, n2, 2);
436	replace_hash(p, 2, n2, 3);
437}
438
439/* find the next template to use, and add it
440 * the p->dataN fields must already be set for the current 8 byte block
441 */
442static int process_next(struct sw842_param *p)
443{
444	int ret, i;
445
446	p->index8[0] = INDEX_NOT_CHECKED;
447	p->index4[0] = INDEX_NOT_CHECKED;
448	p->index4[1] = INDEX_NOT_CHECKED;
449	p->index2[0] = INDEX_NOT_CHECKED;
450	p->index2[1] = INDEX_NOT_CHECKED;
451	p->index2[2] = INDEX_NOT_CHECKED;
452	p->index2[3] = INDEX_NOT_CHECKED;
453
454	/* check up to OPS_MAX - 1; last op is our fallback */
455	for (i = 0; i < OPS_MAX - 1; i++) {
456		if (check_template(p, i))
457			break;
458	}
459
460	ret = add_template(p, i);
461	if (ret)
462		return ret;
463
464	return 0;
465}
466
467/**
468 * sw842_compress
469 *
470 * Compress the uncompressed buffer of length @ilen at @in to the output buffer
471 * @out, using no more than @olen bytes, using the 842 compression format.
472 *
473 * Returns: 0 on success, error on failure.  The @olen parameter
474 * will contain the number of output bytes written on success, or
475 * 0 on error.
476 */
477int sw842_compress(const u8 *in, unsigned int ilen,
478		   u8 *out, unsigned int *olen, void *wmem)
479{
480	struct sw842_param *p = (struct sw842_param *)wmem;
481	int ret;
482	u64 last, next, pad, total;
483	u8 repeat_count = 0;
484	u32 crc;
485
486	BUILD_BUG_ON(sizeof(*p) > SW842_MEM_COMPRESS);
487
488	init_hashtable_nodes(p, 8);
489	init_hashtable_nodes(p, 4);
490	init_hashtable_nodes(p, 2);
491
492	p->in = (u8 *)in;
493	p->instart = p->in;
494	p->ilen = ilen;
495	p->out = out;
496	p->olen = *olen;
497	p->bit = 0;
498
499	total = p->olen;
500
501	*olen = 0;
502
503	/* if using strict mode, we can only compress a multiple of 8 */
504	if (sw842_strict && (ilen % 8)) {
505		pr_err("Using strict mode, can't compress len %d\n", ilen);
506		return -EINVAL;
507	}
508
509	/* let's compress at least 8 bytes, mkay? */
510	if (unlikely(ilen < 8))
511		goto skip_comp;
512
513	/* make initial 'last' different so we don't match the first time */
514	last = ~get_unaligned((u64 *)p->in);
515
516	while (p->ilen > 7) {
517		next = get_unaligned((u64 *)p->in);
518
519		/* must get the next data, as we need to update the hashtable
520		 * entries with the new data every time
521		 */
522		get_next_data(p);
523
524		/* we don't care about endianness in last or next;
525		 * we're just comparing 8 bytes to another 8 bytes,
526		 * they're both the same endianness
527		 */
528		if (next == last) {
529			/* repeat count bits are 0-based, so we stop at +1 */
530			if (++repeat_count <= REPEAT_BITS_MAX)
531				goto repeat;
532		}
533		if (repeat_count) {
534			ret = add_repeat_template(p, repeat_count);
535			repeat_count = 0;
536			if (next == last) /* reached max repeat bits */
537				goto repeat;
538		}
539
540		if (next == 0)
541			ret = add_zeros_template(p);
542		else
543			ret = process_next(p);
544
545		if (ret)
546			return ret;
547
548repeat:
549		last = next;
550		update_hashtables(p);
551		p->in += 8;
552		p->ilen -= 8;
553	}
554
555	if (repeat_count) {
556		ret = add_repeat_template(p, repeat_count);
557		if (ret)
558			return ret;
559	}
560
561skip_comp:
562	if (p->ilen > 0) {
563		ret = add_short_data_template(p, p->ilen);
564		if (ret)
565			return ret;
566
567		p->in += p->ilen;
568		p->ilen = 0;
569	}
570
571	ret = add_end_template(p);
572	if (ret)
573		return ret;
574
575	/*
576	 * crc(0:31) is appended to target data starting with the next
577	 * bit after End of stream template.
578	 * nx842 calculates CRC for data in big-endian format. So doing
579	 * same here so that sw842 decompression can be used for both
580	 * compressed data.
581	 */
582	crc = crc32_be(0, in, ilen);
583	ret = add_bits(p, crc, CRC_BITS);
584	if (ret)
585		return ret;
586
587	if (p->bit) {
588		p->out++;
589		p->olen--;
590		p->bit = 0;
591	}
592
593	/* pad compressed length to multiple of 8 */
594	pad = (8 - ((total - p->olen) % 8)) % 8;
595	if (pad) {
596		if (pad > p->olen) /* we were so close! */
597			return -ENOSPC;
598		memset(p->out, 0, pad);
599		p->out += pad;
600		p->olen -= pad;
601	}
602
603	if (unlikely((total - p->olen) > UINT_MAX))
604		return -ENOSPC;
605
606	*olen = total - p->olen;
607
608	return 0;
609}
610EXPORT_SYMBOL_GPL(sw842_compress);
611
612static int __init sw842_init(void)
613{
614	if (sw842_template_counts)
615		sw842_debugfs_create();
616
617	return 0;
618}
619module_init(sw842_init);
620
621static void __exit sw842_exit(void)
622{
623	if (sw842_template_counts)
624		sw842_debugfs_remove();
625}
626module_exit(sw842_exit);
627
628MODULE_LICENSE("GPL");
629MODULE_DESCRIPTION("Software 842 Compressor");
630MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
631