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TOMOYO Linux Cross Reference
Linux/lib/842/842_compress.c

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  1 /*
  2  * 842 Software Compression
  3  *
  4  * Copyright (C) 2015 Dan Streetman, IBM Corp
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License as published by
  8  * the Free Software Foundation; either version 2 of the License, or
  9  * (at your option) any later version.
 10  *
 11  * This program is distributed in the hope that it will be useful,
 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  * GNU General Public License for more details.
 15  *
 16  * See 842.h for details of the 842 compressed format.
 17  */
 18 
 19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 20 #define MODULE_NAME "842_compress"
 21 
 22 #include <linux/hashtable.h>
 23 
 24 #include "842.h"
 25 #include "842_debugfs.h"
 26 
 27 #define SW842_HASHTABLE8_BITS   (10)
 28 #define SW842_HASHTABLE4_BITS   (11)
 29 #define SW842_HASHTABLE2_BITS   (10)
 30 
 31 /* By default, we allow compressing input buffers of any length, but we must
 32  * use the non-standard "short data" template so the decompressor can correctly
 33  * reproduce the uncompressed data buffer at the right length.  However the
 34  * hardware 842 compressor will not recognize the "short data" template, and
 35  * will fail to decompress any compressed buffer containing it (I have no idea
 36  * why anyone would want to use software to compress and hardware to decompress
 37  * but that's beside the point).  This parameter forces the compression
 38  * function to simply reject any input buffer that isn't a multiple of 8 bytes
 39  * long, instead of using the "short data" template, so that all compressed
 40  * buffers produced by this function will be decompressable by the 842 hardware
 41  * decompressor.  Unless you have a specific need for that, leave this disabled
 42  * so that any length buffer can be compressed.
 43  */
 44 static bool sw842_strict;
 45 module_param_named(strict, sw842_strict, bool, 0644);
 46 
 47 static u8 comp_ops[OPS_MAX][5] = { /* params size in bits */
 48         { I8, N0, N0, N0, 0x19 }, /* 8 */
 49         { I4, I4, N0, N0, 0x18 }, /* 18 */
 50         { I4, I2, I2, N0, 0x17 }, /* 25 */
 51         { I2, I2, I4, N0, 0x13 }, /* 25 */
 52         { I2, I2, I2, I2, 0x12 }, /* 32 */
 53         { I4, I2, D2, N0, 0x16 }, /* 33 */
 54         { I4, D2, I2, N0, 0x15 }, /* 33 */
 55         { I2, D2, I4, N0, 0x0e }, /* 33 */
 56         { D2, I2, I4, N0, 0x09 }, /* 33 */
 57         { I2, I2, I2, D2, 0x11 }, /* 40 */
 58         { I2, I2, D2, I2, 0x10 }, /* 40 */
 59         { I2, D2, I2, I2, 0x0d }, /* 40 */
 60         { D2, I2, I2, I2, 0x08 }, /* 40 */
 61         { I4, D4, N0, N0, 0x14 }, /* 41 */
 62         { D4, I4, N0, N0, 0x04 }, /* 41 */
 63         { I2, I2, D4, N0, 0x0f }, /* 48 */
 64         { I2, D2, I2, D2, 0x0c }, /* 48 */
 65         { I2, D4, I2, N0, 0x0b }, /* 48 */
 66         { D2, I2, I2, D2, 0x07 }, /* 48 */
 67         { D2, I2, D2, I2, 0x06 }, /* 48 */
 68         { D4, I2, I2, N0, 0x03 }, /* 48 */
 69         { I2, D2, D4, N0, 0x0a }, /* 56 */
 70         { D2, I2, D4, N0, 0x05 }, /* 56 */
 71         { D4, I2, D2, N0, 0x02 }, /* 56 */
 72         { D4, D2, I2, N0, 0x01 }, /* 56 */
 73         { D8, N0, N0, N0, 0x00 }, /* 64 */
 74 };
 75 
 76 struct sw842_hlist_node8 {
 77         struct hlist_node node;
 78         u64 data;
 79         u8 index;
 80 };
 81 
 82 struct sw842_hlist_node4 {
 83         struct hlist_node node;
 84         u32 data;
 85         u16 index;
 86 };
 87 
 88 struct sw842_hlist_node2 {
 89         struct hlist_node node;
 90         u16 data;
 91         u8 index;
 92 };
 93 
 94 #define INDEX_NOT_FOUND         (-1)
 95 #define INDEX_NOT_CHECKED       (-2)
 96 
 97 struct sw842_param {
 98         u8 *in;
 99         u8 *instart;
100         u64 ilen;
101         u8 *out;
102         u64 olen;
103         u8 bit;
104         u64 data8[1];
105         u32 data4[2];
106         u16 data2[4];
107         int index8[1];
108         int index4[2];
109         int index2[4];
110         DECLARE_HASHTABLE(htable8, SW842_HASHTABLE8_BITS);
111         DECLARE_HASHTABLE(htable4, SW842_HASHTABLE4_BITS);
112         DECLARE_HASHTABLE(htable2, SW842_HASHTABLE2_BITS);
113         struct sw842_hlist_node8 node8[1 << I8_BITS];
114         struct sw842_hlist_node4 node4[1 << I4_BITS];
115         struct sw842_hlist_node2 node2[1 << I2_BITS];
116 };
117 
118 #define get_input_data(p, o, b)                                         \
119         be##b##_to_cpu(get_unaligned((__be##b *)((p)->in + (o))))
120 
121 #define init_hashtable_nodes(p, b)      do {                    \
122         int _i;                                                 \
123         hash_init((p)->htable##b);                              \
124         for (_i = 0; _i < ARRAY_SIZE((p)->node##b); _i++) {     \
125                 (p)->node##b[_i].index = _i;                    \
126                 (p)->node##b[_i].data = 0;                      \
127                 INIT_HLIST_NODE(&(p)->node##b[_i].node);        \
128         }                                                       \
129 } while (0)
130 
131 #define find_index(p, b, n)     ({                                      \
132         struct sw842_hlist_node##b *_n;                                 \
133         p->index##b[n] = INDEX_NOT_FOUND;                               \
134         hash_for_each_possible(p->htable##b, _n, node, p->data##b[n]) { \
135                 if (p->data##b[n] == _n->data) {                        \
136                         p->index##b[n] = _n->index;                     \
137                         break;                                          \
138                 }                                                       \
139         }                                                               \
140         p->index##b[n] >= 0;                                            \
141 })
142 
143 #define check_index(p, b, n)                    \
144         ((p)->index##b[n] == INDEX_NOT_CHECKED  \
145          ? find_index(p, b, n)                  \
146          : (p)->index##b[n] >= 0)
147 
148 #define replace_hash(p, b, i, d)        do {                            \
149         struct sw842_hlist_node##b *_n = &(p)->node##b[(i)+(d)];        \
150         hash_del(&_n->node);                                            \
151         _n->data = (p)->data##b[d];                                     \
152         pr_debug("add hash index%x %x pos %x data %lx\n", b,            \
153                  (unsigned int)_n->index,                               \
154                  (unsigned int)((p)->in - (p)->instart),                \
155                  (unsigned long)_n->data);                              \
156         hash_add((p)->htable##b, &_n->node, _n->data);                  \
157 } while (0)
158 
159 static u8 bmask[8] = { 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe };
160 
161 static int add_bits(struct sw842_param *p, u64 d, u8 n);
162 
163 static int __split_add_bits(struct sw842_param *p, u64 d, u8 n, u8 s)
164 {
165         int ret;
166 
167         if (n <= s)
168                 return -EINVAL;
169 
170         ret = add_bits(p, d >> s, n - s);
171         if (ret)
172                 return ret;
173         return add_bits(p, d & GENMASK_ULL(s - 1, 0), s);
174 }
175 
176 static int add_bits(struct sw842_param *p, u64 d, u8 n)
177 {
178         int b = p->bit, bits = b + n, s = round_up(bits, 8) - bits;
179         u64 o;
180         u8 *out = p->out;
181 
182         pr_debug("add %u bits %lx\n", (unsigned char)n, (unsigned long)d);
183 
184         if (n > 64)
185                 return -EINVAL;
186 
187         /* split this up if writing to > 8 bytes (i.e. n == 64 && p->bit > 0),
188          * or if we're at the end of the output buffer and would write past end
189          */
190         if (bits > 64)
191                 return __split_add_bits(p, d, n, 32);
192         else if (p->olen < 8 && bits > 32 && bits <= 56)
193                 return __split_add_bits(p, d, n, 16);
194         else if (p->olen < 4 && bits > 16 && bits <= 24)
195                 return __split_add_bits(p, d, n, 8);
196 
197         if (DIV_ROUND_UP(bits, 8) > p->olen)
198                 return -ENOSPC;
199 
200         o = *out & bmask[b];
201         d <<= s;
202 
203         if (bits <= 8)
204                 *out = o | d;
205         else if (bits <= 16)
206                 put_unaligned(cpu_to_be16(o << 8 | d), (__be16 *)out);
207         else if (bits <= 24)
208                 put_unaligned(cpu_to_be32(o << 24 | d << 8), (__be32 *)out);
209         else if (bits <= 32)
210                 put_unaligned(cpu_to_be32(o << 24 | d), (__be32 *)out);
211         else if (bits <= 40)
212                 put_unaligned(cpu_to_be64(o << 56 | d << 24), (__be64 *)out);
213         else if (bits <= 48)
214                 put_unaligned(cpu_to_be64(o << 56 | d << 16), (__be64 *)out);
215         else if (bits <= 56)
216                 put_unaligned(cpu_to_be64(o << 56 | d << 8), (__be64 *)out);
217         else
218                 put_unaligned(cpu_to_be64(o << 56 | d), (__be64 *)out);
219 
220         p->bit += n;
221 
222         if (p->bit > 7) {
223                 p->out += p->bit / 8;
224                 p->olen -= p->bit / 8;
225                 p->bit %= 8;
226         }
227 
228         return 0;
229 }
230 
231 static int add_template(struct sw842_param *p, u8 c)
232 {
233         int ret, i, b = 0;
234         u8 *t = comp_ops[c];
235         bool inv = false;
236 
237         if (c >= OPS_MAX)
238                 return -EINVAL;
239 
240         pr_debug("template %x\n", t[4]);
241 
242         ret = add_bits(p, t[4], OP_BITS);
243         if (ret)
244                 return ret;
245 
246         for (i = 0; i < 4; i++) {
247                 pr_debug("op %x\n", t[i]);
248 
249                 switch (t[i] & OP_AMOUNT) {
250                 case OP_AMOUNT_8:
251                         if (b)
252                                 inv = true;
253                         else if (t[i] & OP_ACTION_INDEX)
254                                 ret = add_bits(p, p->index8[0], I8_BITS);
255                         else if (t[i] & OP_ACTION_DATA)
256                                 ret = add_bits(p, p->data8[0], 64);
257                         else
258                                 inv = true;
259                         break;
260                 case OP_AMOUNT_4:
261                         if (b == 2 && t[i] & OP_ACTION_DATA)
262                                 ret = add_bits(p, get_input_data(p, 2, 32), 32);
263                         else if (b != 0 && b != 4)
264                                 inv = true;
265                         else if (t[i] & OP_ACTION_INDEX)
266                                 ret = add_bits(p, p->index4[b >> 2], I4_BITS);
267                         else if (t[i] & OP_ACTION_DATA)
268                                 ret = add_bits(p, p->data4[b >> 2], 32);
269                         else
270                                 inv = true;
271                         break;
272                 case OP_AMOUNT_2:
273                         if (b != 0 && b != 2 && b != 4 && b != 6)
274                                 inv = true;
275                         if (t[i] & OP_ACTION_INDEX)
276                                 ret = add_bits(p, p->index2[b >> 1], I2_BITS);
277                         else if (t[i] & OP_ACTION_DATA)
278                                 ret = add_bits(p, p->data2[b >> 1], 16);
279                         else
280                                 inv = true;
281                         break;
282                 case OP_AMOUNT_0:
283                         inv = (b != 8) || !(t[i] & OP_ACTION_NOOP);
284                         break;
285                 default:
286                         inv = true;
287                         break;
288                 }
289 
290                 if (ret)
291                         return ret;
292 
293                 if (inv) {
294                         pr_err("Invalid templ %x op %d : %x %x %x %x\n",
295                                c, i, t[0], t[1], t[2], t[3]);
296                         return -EINVAL;
297                 }
298 
299                 b += t[i] & OP_AMOUNT;
300         }
301 
302         if (b != 8) {
303                 pr_err("Invalid template %x len %x : %x %x %x %x\n",
304                        c, b, t[0], t[1], t[2], t[3]);
305                 return -EINVAL;
306         }
307 
308         if (sw842_template_counts)
309                 atomic_inc(&template_count[t[4]]);
310 
311         return 0;
312 }
313 
314 static int add_repeat_template(struct sw842_param *p, u8 r)
315 {
316         int ret;
317 
318         /* repeat param is 0-based */
319         if (!r || --r > REPEAT_BITS_MAX)
320                 return -EINVAL;
321 
322         ret = add_bits(p, OP_REPEAT, OP_BITS);
323         if (ret)
324                 return ret;
325 
326         ret = add_bits(p, r, REPEAT_BITS);
327         if (ret)
328                 return ret;
329 
330         if (sw842_template_counts)
331                 atomic_inc(&template_repeat_count);
332 
333         return 0;
334 }
335 
336 static int add_short_data_template(struct sw842_param *p, u8 b)
337 {
338         int ret, i;
339 
340         if (!b || b > SHORT_DATA_BITS_MAX)
341                 return -EINVAL;
342 
343         ret = add_bits(p, OP_SHORT_DATA, OP_BITS);
344         if (ret)
345                 return ret;
346 
347         ret = add_bits(p, b, SHORT_DATA_BITS);
348         if (ret)
349                 return ret;
350 
351         for (i = 0; i < b; i++) {
352                 ret = add_bits(p, p->in[i], 8);
353                 if (ret)
354                         return ret;
355         }
356 
357         if (sw842_template_counts)
358                 atomic_inc(&template_short_data_count);
359 
360         return 0;
361 }
362 
363 static int add_zeros_template(struct sw842_param *p)
364 {
365         int ret = add_bits(p, OP_ZEROS, OP_BITS);
366 
367         if (ret)
368                 return ret;
369 
370         if (sw842_template_counts)
371                 atomic_inc(&template_zeros_count);
372 
373         return 0;
374 }
375 
376 static int add_end_template(struct sw842_param *p)
377 {
378         int ret = add_bits(p, OP_END, OP_BITS);
379 
380         if (ret)
381                 return ret;
382 
383         if (sw842_template_counts)
384                 atomic_inc(&template_end_count);
385 
386         return 0;
387 }
388 
389 static bool check_template(struct sw842_param *p, u8 c)
390 {
391         u8 *t = comp_ops[c];
392         int i, match, b = 0;
393 
394         if (c >= OPS_MAX)
395                 return false;
396 
397         for (i = 0; i < 4; i++) {
398                 if (t[i] & OP_ACTION_INDEX) {
399                         if (t[i] & OP_AMOUNT_2)
400                                 match = check_index(p, 2, b >> 1);
401                         else if (t[i] & OP_AMOUNT_4)
402                                 match = check_index(p, 4, b >> 2);
403                         else if (t[i] & OP_AMOUNT_8)
404                                 match = check_index(p, 8, 0);
405                         else
406                                 return false;
407                         if (!match)
408                                 return false;
409                 }
410 
411                 b += t[i] & OP_AMOUNT;
412         }
413 
414         return true;
415 }
416 
417 static void get_next_data(struct sw842_param *p)
418 {
419         p->data8[0] = get_input_data(p, 0, 64);
420         p->data4[0] = get_input_data(p, 0, 32);
421         p->data4[1] = get_input_data(p, 4, 32);
422         p->data2[0] = get_input_data(p, 0, 16);
423         p->data2[1] = get_input_data(p, 2, 16);
424         p->data2[2] = get_input_data(p, 4, 16);
425         p->data2[3] = get_input_data(p, 6, 16);
426 }
427 
428 /* update the hashtable entries.
429  * only call this after finding/adding the current template
430  * the dataN fields for the current 8 byte block must be already updated
431  */
432 static void update_hashtables(struct sw842_param *p)
433 {
434         u64 pos = p->in - p->instart;
435         u64 n8 = (pos >> 3) % (1 << I8_BITS);
436         u64 n4 = (pos >> 2) % (1 << I4_BITS);
437         u64 n2 = (pos >> 1) % (1 << I2_BITS);
438 
439         replace_hash(p, 8, n8, 0);
440         replace_hash(p, 4, n4, 0);
441         replace_hash(p, 4, n4, 1);
442         replace_hash(p, 2, n2, 0);
443         replace_hash(p, 2, n2, 1);
444         replace_hash(p, 2, n2, 2);
445         replace_hash(p, 2, n2, 3);
446 }
447 
448 /* find the next template to use, and add it
449  * the p->dataN fields must already be set for the current 8 byte block
450  */
451 static int process_next(struct sw842_param *p)
452 {
453         int ret, i;
454 
455         p->index8[0] = INDEX_NOT_CHECKED;
456         p->index4[0] = INDEX_NOT_CHECKED;
457         p->index4[1] = INDEX_NOT_CHECKED;
458         p->index2[0] = INDEX_NOT_CHECKED;
459         p->index2[1] = INDEX_NOT_CHECKED;
460         p->index2[2] = INDEX_NOT_CHECKED;
461         p->index2[3] = INDEX_NOT_CHECKED;
462 
463         /* check up to OPS_MAX - 1; last op is our fallback */
464         for (i = 0; i < OPS_MAX - 1; i++) {
465                 if (check_template(p, i))
466                         break;
467         }
468 
469         ret = add_template(p, i);
470         if (ret)
471                 return ret;
472 
473         return 0;
474 }
475 
476 /**
477  * sw842_compress
478  *
479  * Compress the uncompressed buffer of length @ilen at @in to the output buffer
480  * @out, using no more than @olen bytes, using the 842 compression format.
481  *
482  * Returns: 0 on success, error on failure.  The @olen parameter
483  * will contain the number of output bytes written on success, or
484  * 0 on error.
485  */
486 int sw842_compress(const u8 *in, unsigned int ilen,
487                    u8 *out, unsigned int *olen, void *wmem)
488 {
489         struct sw842_param *p = (struct sw842_param *)wmem;
490         int ret;
491         u64 last, next, pad, total;
492         u8 repeat_count = 0;
493         u32 crc;
494 
495         BUILD_BUG_ON(sizeof(*p) > SW842_MEM_COMPRESS);
496 
497         init_hashtable_nodes(p, 8);
498         init_hashtable_nodes(p, 4);
499         init_hashtable_nodes(p, 2);
500 
501         p->in = (u8 *)in;
502         p->instart = p->in;
503         p->ilen = ilen;
504         p->out = out;
505         p->olen = *olen;
506         p->bit = 0;
507 
508         total = p->olen;
509 
510         *olen = 0;
511 
512         /* if using strict mode, we can only compress a multiple of 8 */
513         if (sw842_strict && (ilen % 8)) {
514                 pr_err("Using strict mode, can't compress len %d\n", ilen);
515                 return -EINVAL;
516         }
517 
518         /* let's compress at least 8 bytes, mkay? */
519         if (unlikely(ilen < 8))
520                 goto skip_comp;
521 
522         /* make initial 'last' different so we don't match the first time */
523         last = ~get_unaligned((u64 *)p->in);
524 
525         while (p->ilen > 7) {
526                 next = get_unaligned((u64 *)p->in);
527 
528                 /* must get the next data, as we need to update the hashtable
529                  * entries with the new data every time
530                  */
531                 get_next_data(p);
532 
533                 /* we don't care about endianness in last or next;
534                  * we're just comparing 8 bytes to another 8 bytes,
535                  * they're both the same endianness
536                  */
537                 if (next == last) {
538                         /* repeat count bits are 0-based, so we stop at +1 */
539                         if (++repeat_count <= REPEAT_BITS_MAX)
540                                 goto repeat;
541                 }
542                 if (repeat_count) {
543                         ret = add_repeat_template(p, repeat_count);
544                         repeat_count = 0;
545                         if (next == last) /* reached max repeat bits */
546                                 goto repeat;
547                 }
548 
549                 if (next == 0)
550                         ret = add_zeros_template(p);
551                 else
552                         ret = process_next(p);
553 
554                 if (ret)
555                         return ret;
556 
557 repeat:
558                 last = next;
559                 update_hashtables(p);
560                 p->in += 8;
561                 p->ilen -= 8;
562         }
563 
564         if (repeat_count) {
565                 ret = add_repeat_template(p, repeat_count);
566                 if (ret)
567                         return ret;
568         }
569 
570 skip_comp:
571         if (p->ilen > 0) {
572                 ret = add_short_data_template(p, p->ilen);
573                 if (ret)
574                         return ret;
575 
576                 p->in += p->ilen;
577                 p->ilen = 0;
578         }
579 
580         ret = add_end_template(p);
581         if (ret)
582                 return ret;
583 
584         /*
585          * crc(0:31) is appended to target data starting with the next
586          * bit after End of stream template.
587          * nx842 calculates CRC for data in big-endian format. So doing
588          * same here so that sw842 decompression can be used for both
589          * compressed data.
590          */
591         crc = crc32_be(0, in, ilen);
592         ret = add_bits(p, crc, CRC_BITS);
593         if (ret)
594                 return ret;
595 
596         if (p->bit) {
597                 p->out++;
598                 p->olen--;
599                 p->bit = 0;
600         }
601 
602         /* pad compressed length to multiple of 8 */
603         pad = (8 - ((total - p->olen) % 8)) % 8;
604         if (pad) {
605                 if (pad > p->olen) /* we were so close! */
606                         return -ENOSPC;
607                 memset(p->out, 0, pad);
608                 p->out += pad;
609                 p->olen -= pad;
610         }
611 
612         if (unlikely((total - p->olen) > UINT_MAX))
613                 return -ENOSPC;
614 
615         *olen = total - p->olen;
616 
617         return 0;
618 }
619 EXPORT_SYMBOL_GPL(sw842_compress);
620 
621 static int __init sw842_init(void)
622 {
623         if (sw842_template_counts)
624                 sw842_debugfs_create();
625 
626         return 0;
627 }
628 module_init(sw842_init);
629 
630 static void __exit sw842_exit(void)
631 {
632         if (sw842_template_counts)
633                 sw842_debugfs_remove();
634 }
635 module_exit(sw842_exit);
636 
637 MODULE_LICENSE("GPL");
638 MODULE_DESCRIPTION("Software 842 Compressor");
639 MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>");
640 

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