1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2019 HUAWEI, Inc.
4 * https://www.huawei.com/
5 */
6 #include "compress.h"
7 #include <linux/module.h>
8 #include <linux/lz4.h>
9
10 #ifndef LZ4_DISTANCE_MAX /* history window size */
11 #define LZ4_DISTANCE_MAX 65535 /* set to maximum value by default */
12 #endif
13
14 #define LZ4_MAX_DISTANCE_PAGES (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
15 #ifndef LZ4_DECOMPRESS_INPLACE_MARGIN
16 #define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize) (((srcsize) >> 8) + 32)
17 #endif
18
19 struct z_erofs_decompressor {
20 /*
21 * if destpages have sparsed pages, fill them with bounce pages.
22 * it also check whether destpages indicate continuous physical memory.
23 */
24 int (*prepare_destpages)(struct z_erofs_decompress_req *rq,
25 struct list_head *pagepool);
26 int (*decompress)(struct z_erofs_decompress_req *rq, u8 *out);
27 char *name;
28 };
29
z_erofs_load_lz4_config(struct super_block * sb,struct erofs_super_block * dsb,struct z_erofs_lz4_cfgs * lz4,int size)30 int z_erofs_load_lz4_config(struct super_block *sb,
31 struct erofs_super_block *dsb,
32 struct z_erofs_lz4_cfgs *lz4, int size)
33 {
34 struct erofs_sb_info *sbi = EROFS_SB(sb);
35 u16 distance;
36
37 if (lz4) {
38 if (size < sizeof(struct z_erofs_lz4_cfgs)) {
39 erofs_err(sb, "invalid lz4 cfgs, size=%u", size);
40 return -EINVAL;
41 }
42 distance = le16_to_cpu(lz4->max_distance);
43
44 sbi->lz4.max_pclusterblks = le16_to_cpu(lz4->max_pclusterblks);
45 if (!sbi->lz4.max_pclusterblks) {
46 sbi->lz4.max_pclusterblks = 1; /* reserved case */
47 } else if (sbi->lz4.max_pclusterblks >
48 Z_EROFS_PCLUSTER_MAX_SIZE / EROFS_BLKSIZ) {
49 erofs_err(sb, "too large lz4 pclusterblks %u",
50 sbi->lz4.max_pclusterblks);
51 return -EINVAL;
52 } else if (sbi->lz4.max_pclusterblks >= 2) {
53 erofs_info(sb, "EXPERIMENTAL big pcluster feature in use. Use at your own risk!");
54 }
55 } else {
56 distance = le16_to_cpu(dsb->u1.lz4_max_distance);
57 sbi->lz4.max_pclusterblks = 1;
58 }
59
60 sbi->lz4.max_distance_pages = distance ?
61 DIV_ROUND_UP(distance, PAGE_SIZE) + 1 :
62 LZ4_MAX_DISTANCE_PAGES;
63 return erofs_pcpubuf_growsize(sbi->lz4.max_pclusterblks);
64 }
65
z_erofs_lz4_prepare_destpages(struct z_erofs_decompress_req * rq,struct list_head * pagepool)66 static int z_erofs_lz4_prepare_destpages(struct z_erofs_decompress_req *rq,
67 struct list_head *pagepool)
68 {
69 const unsigned int nr =
70 PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
71 struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
72 unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
73 BITS_PER_LONG)] = { 0 };
74 unsigned int lz4_max_distance_pages =
75 EROFS_SB(rq->sb)->lz4.max_distance_pages;
76 void *kaddr = NULL;
77 unsigned int i, j, top;
78
79 top = 0;
80 for (i = j = 0; i < nr; ++i, ++j) {
81 struct page *const page = rq->out[i];
82 struct page *victim;
83
84 if (j >= lz4_max_distance_pages)
85 j = 0;
86
87 /* 'valid' bounced can only be tested after a complete round */
88 if (test_bit(j, bounced)) {
89 DBG_BUGON(i < lz4_max_distance_pages);
90 DBG_BUGON(top >= lz4_max_distance_pages);
91 availables[top++] = rq->out[i - lz4_max_distance_pages];
92 }
93
94 if (page) {
95 __clear_bit(j, bounced);
96 if (kaddr) {
97 if (kaddr + PAGE_SIZE == page_address(page))
98 kaddr += PAGE_SIZE;
99 else
100 kaddr = NULL;
101 } else if (!i) {
102 kaddr = page_address(page);
103 }
104 continue;
105 }
106 kaddr = NULL;
107 __set_bit(j, bounced);
108
109 if (top) {
110 victim = availables[--top];
111 get_page(victim);
112 } else {
113 victim = erofs_allocpage(pagepool,
114 GFP_KERNEL | __GFP_NOFAIL);
115 set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
116 }
117 rq->out[i] = victim;
118 }
119 return kaddr ? 1 : 0;
120 }
121
z_erofs_handle_inplace_io(struct z_erofs_decompress_req * rq,void * inpage,unsigned int * inputmargin,int * maptype,bool support_0padding)122 static void *z_erofs_handle_inplace_io(struct z_erofs_decompress_req *rq,
123 void *inpage, unsigned int *inputmargin, int *maptype,
124 bool support_0padding)
125 {
126 unsigned int nrpages_in, nrpages_out;
127 unsigned int ofull, oend, inputsize, total, i, j;
128 struct page **in;
129 void *src, *tmp;
130
131 inputsize = rq->inputsize;
132 nrpages_in = PAGE_ALIGN(inputsize) >> PAGE_SHIFT;
133 oend = rq->pageofs_out + rq->outputsize;
134 ofull = PAGE_ALIGN(oend);
135 nrpages_out = ofull >> PAGE_SHIFT;
136
137 if (rq->inplace_io) {
138 if (rq->partial_decoding || !support_0padding ||
139 ofull - oend < LZ4_DECOMPRESS_INPLACE_MARGIN(inputsize))
140 goto docopy;
141
142 for (i = 0; i < nrpages_in; ++i) {
143 DBG_BUGON(rq->in[i] == NULL);
144 for (j = 0; j < nrpages_out - nrpages_in + i; ++j)
145 if (rq->out[j] == rq->in[i])
146 goto docopy;
147 }
148 }
149
150 if (nrpages_in <= 1) {
151 *maptype = 0;
152 return inpage;
153 }
154 kunmap_atomic(inpage);
155 might_sleep();
156 src = erofs_vm_map_ram(rq->in, nrpages_in);
157 if (!src)
158 return ERR_PTR(-ENOMEM);
159 *maptype = 1;
160 return src;
161
162 docopy:
163 /* Or copy compressed data which can be overlapped to per-CPU buffer */
164 in = rq->in;
165 src = erofs_get_pcpubuf(nrpages_in);
166 if (!src) {
167 DBG_BUGON(1);
168 kunmap_atomic(inpage);
169 return ERR_PTR(-EFAULT);
170 }
171
172 tmp = src;
173 total = rq->inputsize;
174 while (total) {
175 unsigned int page_copycnt =
176 min_t(unsigned int, total, PAGE_SIZE - *inputmargin);
177
178 if (!inpage)
179 inpage = kmap_atomic(*in);
180 memcpy(tmp, inpage + *inputmargin, page_copycnt);
181 kunmap_atomic(inpage);
182 inpage = NULL;
183 tmp += page_copycnt;
184 total -= page_copycnt;
185 ++in;
186 *inputmargin = 0;
187 }
188 *maptype = 2;
189 return src;
190 }
191
z_erofs_lz4_decompress(struct z_erofs_decompress_req * rq,u8 * out)192 static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq, u8 *out)
193 {
194 unsigned int inputmargin;
195 u8 *headpage, *src;
196 bool support_0padding;
197 int ret, maptype;
198
199 DBG_BUGON(*rq->in == NULL);
200 headpage = kmap_atomic(*rq->in);
201 inputmargin = 0;
202 support_0padding = false;
203
204 /* decompression inplace is only safe when 0padding is enabled */
205 if (erofs_sb_has_lz4_0padding(EROFS_SB(rq->sb))) {
206 support_0padding = true;
207
208 while (!headpage[inputmargin & ~PAGE_MASK])
209 if (!(++inputmargin & ~PAGE_MASK))
210 break;
211
212 if (inputmargin >= rq->inputsize) {
213 kunmap_atomic(headpage);
214 return -EIO;
215 }
216 }
217
218 rq->inputsize -= inputmargin;
219 src = z_erofs_handle_inplace_io(rq, headpage, &inputmargin, &maptype,
220 support_0padding);
221 if (IS_ERR(src))
222 return PTR_ERR(src);
223
224 /* legacy format could compress extra data in a pcluster. */
225 if (rq->partial_decoding || !support_0padding)
226 ret = LZ4_decompress_safe_partial(src + inputmargin, out,
227 rq->inputsize, rq->outputsize, rq->outputsize);
228 else
229 ret = LZ4_decompress_safe(src + inputmargin, out,
230 rq->inputsize, rq->outputsize);
231
232 if (ret != rq->outputsize) {
233 erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
234 ret, rq->inputsize, inputmargin, rq->outputsize);
235
236 WARN_ON(1);
237 print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
238 16, 1, src + inputmargin, rq->inputsize, true);
239 print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
240 16, 1, out, rq->outputsize, true);
241
242 if (ret >= 0)
243 memset(out + ret, 0, rq->outputsize - ret);
244 ret = -EIO;
245 }
246
247 if (maptype == 0) {
248 kunmap_atomic(src);
249 } else if (maptype == 1) {
250 vm_unmap_ram(src, PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT);
251 } else if (maptype == 2) {
252 erofs_put_pcpubuf(src);
253 } else {
254 DBG_BUGON(1);
255 return -EFAULT;
256 }
257 return ret;
258 }
259
260 static struct z_erofs_decompressor decompressors[] = {
261 [Z_EROFS_COMPRESSION_SHIFTED] = {
262 .name = "shifted"
263 },
264 [Z_EROFS_COMPRESSION_LZ4] = {
265 .prepare_destpages = z_erofs_lz4_prepare_destpages,
266 .decompress = z_erofs_lz4_decompress,
267 .name = "lz4"
268 },
269 };
270
copy_from_pcpubuf(struct page ** out,const char * dst,unsigned short pageofs_out,unsigned int outputsize)271 static void copy_from_pcpubuf(struct page **out, const char *dst,
272 unsigned short pageofs_out,
273 unsigned int outputsize)
274 {
275 const char *end = dst + outputsize;
276 const unsigned int righthalf = PAGE_SIZE - pageofs_out;
277 const char *cur = dst - pageofs_out;
278
279 while (cur < end) {
280 struct page *const page = *out++;
281
282 if (page) {
283 char *buf = kmap_atomic(page);
284
285 if (cur >= dst) {
286 memcpy(buf, cur, min_t(uint, PAGE_SIZE,
287 end - cur));
288 } else {
289 memcpy(buf + pageofs_out, cur + pageofs_out,
290 min_t(uint, righthalf, end - cur));
291 }
292 kunmap_atomic(buf);
293 }
294 cur += PAGE_SIZE;
295 }
296 }
297
z_erofs_decompress_generic(struct z_erofs_decompress_req * rq,struct list_head * pagepool)298 static int z_erofs_decompress_generic(struct z_erofs_decompress_req *rq,
299 struct list_head *pagepool)
300 {
301 const unsigned int nrpages_out =
302 PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
303 const struct z_erofs_decompressor *alg = decompressors + rq->alg;
304 unsigned int dst_maptype;
305 void *dst;
306 int ret;
307
308 /* two optimized fast paths only for non bigpcluster cases yet */
309 if (rq->inputsize <= PAGE_SIZE) {
310 if (nrpages_out == 1 && !rq->inplace_io) {
311 DBG_BUGON(!*rq->out);
312 dst = kmap_atomic(*rq->out);
313 dst_maptype = 0;
314 goto dstmap_out;
315 }
316
317 /*
318 * For the case of small output size (especially much less
319 * than PAGE_SIZE), memcpy the decompressed data rather than
320 * compressed data is preferred.
321 */
322 if (rq->outputsize <= PAGE_SIZE * 7 / 8) {
323 dst = erofs_get_pcpubuf(1);
324 if (IS_ERR(dst))
325 return PTR_ERR(dst);
326
327 rq->inplace_io = false;
328 ret = alg->decompress(rq, dst);
329 if (!ret)
330 copy_from_pcpubuf(rq->out, dst, rq->pageofs_out,
331 rq->outputsize);
332
333 erofs_put_pcpubuf(dst);
334 return ret;
335 }
336 }
337
338 /* general decoding path which can be used for all cases */
339 ret = alg->prepare_destpages(rq, pagepool);
340 if (ret < 0)
341 return ret;
342 if (ret) {
343 dst = page_address(*rq->out);
344 dst_maptype = 1;
345 goto dstmap_out;
346 }
347
348 dst = erofs_vm_map_ram(rq->out, nrpages_out);
349 if (!dst)
350 return -ENOMEM;
351 dst_maptype = 2;
352
353 dstmap_out:
354 ret = alg->decompress(rq, dst + rq->pageofs_out);
355
356 if (!dst_maptype)
357 kunmap_atomic(dst);
358 else if (dst_maptype == 2)
359 vm_unmap_ram(dst, nrpages_out);
360 return ret;
361 }
362
z_erofs_shifted_transform(const struct z_erofs_decompress_req * rq,struct list_head * pagepool)363 static int z_erofs_shifted_transform(const struct z_erofs_decompress_req *rq,
364 struct list_head *pagepool)
365 {
366 const unsigned int nrpages_out =
367 PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
368 const unsigned int righthalf = PAGE_SIZE - rq->pageofs_out;
369 unsigned char *src, *dst;
370
371 if (nrpages_out > 2) {
372 DBG_BUGON(1);
373 return -EIO;
374 }
375
376 if (rq->out[0] == *rq->in) {
377 DBG_BUGON(nrpages_out != 1);
378 return 0;
379 }
380
381 src = kmap_atomic(*rq->in);
382 if (rq->out[0]) {
383 dst = kmap_atomic(rq->out[0]);
384 memcpy(dst + rq->pageofs_out, src, righthalf);
385 kunmap_atomic(dst);
386 }
387
388 if (nrpages_out == 2) {
389 DBG_BUGON(!rq->out[1]);
390 if (rq->out[1] == *rq->in) {
391 memmove(src, src + righthalf, rq->pageofs_out);
392 } else {
393 dst = kmap_atomic(rq->out[1]);
394 memcpy(dst, src + righthalf, rq->pageofs_out);
395 kunmap_atomic(dst);
396 }
397 }
398 kunmap_atomic(src);
399 return 0;
400 }
401
z_erofs_decompress(struct z_erofs_decompress_req * rq,struct list_head * pagepool)402 int z_erofs_decompress(struct z_erofs_decompress_req *rq,
403 struct list_head *pagepool)
404 {
405 if (rq->alg == Z_EROFS_COMPRESSION_SHIFTED)
406 return z_erofs_shifted_transform(rq, pagepool);
407 return z_erofs_decompress_generic(rq, pagepool);
408 }
409
