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c942fddf | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2da572c9 DS |
2 | /* |
3 | * 842 Software Decompression | |
4 | * | |
5 | * Copyright (C) 2015 Dan Streetman, IBM Corp | |
6 | * | |
2da572c9 DS |
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_decompress" | |
12 | ||
13 | #include "842.h" | |
14 | #include "842_debugfs.h" | |
15 | ||
16 | /* rolling fifo sizes */ | |
17 | #define I2_FIFO_SIZE (2 * (1 << I2_BITS)) | |
18 | #define I4_FIFO_SIZE (4 * (1 << I4_BITS)) | |
19 | #define I8_FIFO_SIZE (8 * (1 << I8_BITS)) | |
20 | ||
21 | static u8 decomp_ops[OPS_MAX][4] = { | |
22 | { D8, N0, N0, N0 }, | |
23 | { D4, D2, I2, N0 }, | |
24 | { D4, I2, D2, N0 }, | |
25 | { D4, I2, I2, N0 }, | |
26 | { D4, I4, N0, N0 }, | |
27 | { D2, I2, D4, N0 }, | |
28 | { D2, I2, D2, I2 }, | |
29 | { D2, I2, I2, D2 }, | |
30 | { D2, I2, I2, I2 }, | |
31 | { D2, I2, I4, N0 }, | |
32 | { I2, D2, D4, N0 }, | |
33 | { I2, D4, I2, N0 }, | |
34 | { I2, D2, I2, D2 }, | |
35 | { I2, D2, I2, I2 }, | |
36 | { I2, D2, I4, N0 }, | |
37 | { I2, I2, D4, N0 }, | |
38 | { I2, I2, D2, I2 }, | |
39 | { I2, I2, I2, D2 }, | |
40 | { I2, I2, I2, I2 }, | |
41 | { I2, I2, I4, N0 }, | |
42 | { I4, D4, N0, N0 }, | |
43 | { I4, D2, I2, N0 }, | |
44 | { I4, I2, D2, N0 }, | |
45 | { I4, I2, I2, N0 }, | |
46 | { I4, I4, N0, N0 }, | |
47 | { I8, N0, N0, N0 } | |
48 | }; | |
49 | ||
50 | struct sw842_param { | |
51 | u8 *in; | |
52 | u8 bit; | |
53 | u64 ilen; | |
54 | u8 *out; | |
55 | u8 *ostart; | |
56 | u64 olen; | |
57 | }; | |
58 | ||
59 | #define beN_to_cpu(d, s) \ | |
60 | ((s) == 2 ? be16_to_cpu(get_unaligned((__be16 *)d)) : \ | |
61 | (s) == 4 ? be32_to_cpu(get_unaligned((__be32 *)d)) : \ | |
62 | (s) == 8 ? be64_to_cpu(get_unaligned((__be64 *)d)) : \ | |
5ca636b9 | 63 | 0) |
2da572c9 DS |
64 | |
65 | static int next_bits(struct sw842_param *p, u64 *d, u8 n); | |
66 | ||
67 | static int __split_next_bits(struct sw842_param *p, u64 *d, u8 n, u8 s) | |
68 | { | |
69 | u64 tmp = 0; | |
70 | int ret; | |
71 | ||
72 | if (n <= s) { | |
73 | pr_debug("split_next_bits invalid n %u s %u\n", n, s); | |
74 | return -EINVAL; | |
75 | } | |
76 | ||
77 | ret = next_bits(p, &tmp, n - s); | |
78 | if (ret) | |
79 | return ret; | |
80 | ret = next_bits(p, d, s); | |
81 | if (ret) | |
82 | return ret; | |
83 | *d |= tmp << s; | |
84 | return 0; | |
85 | } | |
86 | ||
87 | static int next_bits(struct sw842_param *p, u64 *d, u8 n) | |
88 | { | |
89 | u8 *in = p->in, b = p->bit, bits = b + n; | |
90 | ||
91 | if (n > 64) { | |
92 | pr_debug("next_bits invalid n %u\n", n); | |
93 | return -EINVAL; | |
94 | } | |
95 | ||
96 | /* split this up if reading > 8 bytes, or if we're at the end of | |
97 | * the input buffer and would read past the end | |
98 | */ | |
99 | if (bits > 64) | |
100 | return __split_next_bits(p, d, n, 32); | |
101 | else if (p->ilen < 8 && bits > 32 && bits <= 56) | |
102 | return __split_next_bits(p, d, n, 16); | |
103 | else if (p->ilen < 4 && bits > 16 && bits <= 24) | |
104 | return __split_next_bits(p, d, n, 8); | |
105 | ||
106 | if (DIV_ROUND_UP(bits, 8) > p->ilen) | |
107 | return -EOVERFLOW; | |
108 | ||
109 | if (bits <= 8) | |
110 | *d = *in >> (8 - bits); | |
111 | else if (bits <= 16) | |
112 | *d = be16_to_cpu(get_unaligned((__be16 *)in)) >> (16 - bits); | |
113 | else if (bits <= 32) | |
114 | *d = be32_to_cpu(get_unaligned((__be32 *)in)) >> (32 - bits); | |
115 | else | |
116 | *d = be64_to_cpu(get_unaligned((__be64 *)in)) >> (64 - bits); | |
117 | ||
118 | *d &= GENMASK_ULL(n - 1, 0); | |
119 | ||
120 | p->bit += n; | |
121 | ||
122 | if (p->bit > 7) { | |
123 | p->in += p->bit / 8; | |
124 | p->ilen -= p->bit / 8; | |
125 | p->bit %= 8; | |
126 | } | |
127 | ||
128 | return 0; | |
129 | } | |
130 | ||
131 | static int do_data(struct sw842_param *p, u8 n) | |
132 | { | |
133 | u64 v; | |
134 | int ret; | |
135 | ||
136 | if (n > p->olen) | |
137 | return -ENOSPC; | |
138 | ||
139 | ret = next_bits(p, &v, n * 8); | |
140 | if (ret) | |
141 | return ret; | |
142 | ||
143 | switch (n) { | |
144 | case 2: | |
145 | put_unaligned(cpu_to_be16((u16)v), (__be16 *)p->out); | |
146 | break; | |
147 | case 4: | |
148 | put_unaligned(cpu_to_be32((u32)v), (__be32 *)p->out); | |
149 | break; | |
150 | case 8: | |
151 | put_unaligned(cpu_to_be64((u64)v), (__be64 *)p->out); | |
152 | break; | |
153 | default: | |
154 | return -EINVAL; | |
155 | } | |
156 | ||
157 | p->out += n; | |
158 | p->olen -= n; | |
159 | ||
160 | return 0; | |
161 | } | |
162 | ||
163 | static int __do_index(struct sw842_param *p, u8 size, u8 bits, u64 fsize) | |
164 | { | |
165 | u64 index, offset, total = round_down(p->out - p->ostart, 8); | |
166 | int ret; | |
167 | ||
168 | ret = next_bits(p, &index, bits); | |
169 | if (ret) | |
170 | return ret; | |
171 | ||
172 | offset = index * size; | |
173 | ||
174 | /* a ring buffer of fsize is used; correct the offset */ | |
175 | if (total > fsize) { | |
176 | /* this is where the current fifo is */ | |
177 | u64 section = round_down(total, fsize); | |
178 | /* the current pos in the fifo */ | |
ca7fc7e9 | 179 | u64 pos = total - section; |
2da572c9 DS |
180 | |
181 | /* if the offset is past/at the pos, we need to | |
182 | * go back to the last fifo section | |
183 | */ | |
184 | if (offset >= pos) | |
185 | section -= fsize; | |
186 | ||
187 | offset += section; | |
188 | } | |
189 | ||
190 | if (offset + size > total) { | |
191 | pr_debug("index%x %lx points past end %lx\n", size, | |
192 | (unsigned long)offset, (unsigned long)total); | |
193 | return -EINVAL; | |
194 | } | |
195 | ||
5ca636b9 DS |
196 | if (size != 2 && size != 4 && size != 8) |
197 | WARN(1, "__do_index invalid size %x\n", size); | |
198 | else | |
199 | pr_debug("index%x to %lx off %lx adjoff %lx tot %lx data %lx\n", | |
200 | size, (unsigned long)index, | |
201 | (unsigned long)(index * size), (unsigned long)offset, | |
202 | (unsigned long)total, | |
203 | (unsigned long)beN_to_cpu(&p->ostart[offset], size)); | |
2da572c9 DS |
204 | |
205 | memcpy(p->out, &p->ostart[offset], size); | |
206 | p->out += size; | |
207 | p->olen -= size; | |
208 | ||
209 | return 0; | |
210 | } | |
211 | ||
f7ead7b4 | 212 | static int do_index(struct sw842_param *p, u8 n) |
2da572c9 DS |
213 | { |
214 | switch (n) { | |
215 | case 2: | |
216 | return __do_index(p, 2, I2_BITS, I2_FIFO_SIZE); | |
217 | case 4: | |
218 | return __do_index(p, 4, I4_BITS, I4_FIFO_SIZE); | |
219 | case 8: | |
220 | return __do_index(p, 8, I8_BITS, I8_FIFO_SIZE); | |
221 | default: | |
222 | return -EINVAL; | |
223 | } | |
224 | } | |
225 | ||
f7ead7b4 | 226 | static int do_op(struct sw842_param *p, u8 o) |
2da572c9 DS |
227 | { |
228 | int i, ret = 0; | |
229 | ||
230 | if (o >= OPS_MAX) | |
231 | return -EINVAL; | |
232 | ||
233 | for (i = 0; i < 4; i++) { | |
234 | u8 op = decomp_ops[o][i]; | |
235 | ||
236 | pr_debug("op is %x\n", op); | |
237 | ||
238 | switch (op & OP_ACTION) { | |
239 | case OP_ACTION_DATA: | |
240 | ret = do_data(p, op & OP_AMOUNT); | |
241 | break; | |
242 | case OP_ACTION_INDEX: | |
243 | ret = do_index(p, op & OP_AMOUNT); | |
244 | break; | |
245 | case OP_ACTION_NOOP: | |
246 | break; | |
247 | default: | |
fc4fa6e1 | 248 | pr_err("Internal error, invalid op %x\n", op); |
2da572c9 DS |
249 | return -EINVAL; |
250 | } | |
251 | ||
252 | if (ret) | |
253 | return ret; | |
254 | } | |
255 | ||
256 | if (sw842_template_counts) | |
257 | atomic_inc(&template_count[o]); | |
258 | ||
259 | return 0; | |
260 | } | |
261 | ||
262 | /** | |
263 | * sw842_decompress | |
264 | * | |
265 | * Decompress the 842-compressed buffer of length @ilen at @in | |
266 | * to the output buffer @out, using no more than @olen bytes. | |
267 | * | |
268 | * The compressed buffer must be only a single 842-compressed buffer, | |
269 | * with the standard format described in the comments in 842.h | |
270 | * Processing will stop when the 842 "END" template is detected, | |
271 | * not the end of the buffer. | |
272 | * | |
273 | * Returns: 0 on success, error on failure. The @olen parameter | |
274 | * will contain the number of output bytes written on success, or | |
275 | * 0 on error. | |
276 | */ | |
277 | int sw842_decompress(const u8 *in, unsigned int ilen, | |
278 | u8 *out, unsigned int *olen) | |
279 | { | |
280 | struct sw842_param p; | |
281 | int ret; | |
282 | u64 op, rep, tmp, bytes, total; | |
ea0b3984 | 283 | u64 crc; |
2da572c9 DS |
284 | |
285 | p.in = (u8 *)in; | |
286 | p.bit = 0; | |
287 | p.ilen = ilen; | |
288 | p.out = out; | |
289 | p.ostart = out; | |
290 | p.olen = *olen; | |
291 | ||
292 | total = p.olen; | |
293 | ||
294 | *olen = 0; | |
295 | ||
296 | do { | |
297 | ret = next_bits(&p, &op, OP_BITS); | |
298 | if (ret) | |
299 | return ret; | |
300 | ||
301 | pr_debug("template is %lx\n", (unsigned long)op); | |
302 | ||
303 | switch (op) { | |
304 | case OP_REPEAT: | |
305 | ret = next_bits(&p, &rep, REPEAT_BITS); | |
306 | if (ret) | |
307 | return ret; | |
308 | ||
309 | if (p.out == out) /* no previous bytes */ | |
310 | return -EINVAL; | |
311 | ||
312 | /* copy rep + 1 */ | |
313 | rep++; | |
314 | ||
315 | if (rep * 8 > p.olen) | |
316 | return -ENOSPC; | |
317 | ||
318 | while (rep-- > 0) { | |
319 | memcpy(p.out, p.out - 8, 8); | |
320 | p.out += 8; | |
321 | p.olen -= 8; | |
322 | } | |
323 | ||
324 | if (sw842_template_counts) | |
325 | atomic_inc(&template_repeat_count); | |
326 | ||
327 | break; | |
328 | case OP_ZEROS: | |
329 | if (8 > p.olen) | |
330 | return -ENOSPC; | |
331 | ||
332 | memset(p.out, 0, 8); | |
333 | p.out += 8; | |
334 | p.olen -= 8; | |
335 | ||
336 | if (sw842_template_counts) | |
337 | atomic_inc(&template_zeros_count); | |
338 | ||
339 | break; | |
340 | case OP_SHORT_DATA: | |
341 | ret = next_bits(&p, &bytes, SHORT_DATA_BITS); | |
342 | if (ret) | |
343 | return ret; | |
344 | ||
345 | if (!bytes || bytes > SHORT_DATA_BITS_MAX) | |
346 | return -EINVAL; | |
347 | ||
348 | while (bytes-- > 0) { | |
349 | ret = next_bits(&p, &tmp, 8); | |
350 | if (ret) | |
351 | return ret; | |
352 | *p.out = (u8)tmp; | |
353 | p.out++; | |
354 | p.olen--; | |
355 | } | |
356 | ||
357 | if (sw842_template_counts) | |
358 | atomic_inc(&template_short_data_count); | |
359 | ||
360 | break; | |
361 | case OP_END: | |
362 | if (sw842_template_counts) | |
363 | atomic_inc(&template_end_count); | |
364 | ||
365 | break; | |
366 | default: /* use template */ | |
367 | ret = do_op(&p, op); | |
368 | if (ret) | |
369 | return ret; | |
370 | break; | |
371 | } | |
372 | } while (op != OP_END); | |
373 | ||
ea0b3984 HM |
374 | /* |
375 | * crc(0:31) is saved in compressed data starting with the | |
376 | * next bit after End of stream template. | |
377 | */ | |
378 | ret = next_bits(&p, &crc, CRC_BITS); | |
379 | if (ret) | |
380 | return ret; | |
381 | ||
382 | /* | |
383 | * Validate CRC saved in compressed data. | |
384 | */ | |
385 | if (crc != (u64)crc32_be(0, out, total - p.olen)) { | |
386 | pr_debug("CRC mismatch for decompression\n"); | |
387 | return -EINVAL; | |
388 | } | |
389 | ||
2da572c9 DS |
390 | if (unlikely((total - p.olen) > UINT_MAX)) |
391 | return -ENOSPC; | |
392 | ||
393 | *olen = total - p.olen; | |
394 | ||
395 | return 0; | |
396 | } | |
397 | EXPORT_SYMBOL_GPL(sw842_decompress); | |
398 | ||
399 | static int __init sw842_init(void) | |
400 | { | |
401 | if (sw842_template_counts) | |
402 | sw842_debugfs_create(); | |
403 | ||
404 | return 0; | |
405 | } | |
406 | module_init(sw842_init); | |
407 | ||
408 | static void __exit sw842_exit(void) | |
409 | { | |
410 | if (sw842_template_counts) | |
411 | sw842_debugfs_remove(); | |
412 | } | |
413 | module_exit(sw842_exit); | |
414 | ||
415 | MODULE_LICENSE("GPL"); | |
416 | MODULE_DESCRIPTION("Software 842 Decompressor"); | |
417 | MODULE_AUTHOR("Dan Streetman <ddstreet@ieee.org>"); |