fs/erofs/decompressor.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2019 HUAWEI, Inc.
   4  *             https://www.huawei.com/
   5  * Copyright (C) 2024 Alibaba Cloud
   6  */
   7 #include "compress.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_lz4_decompress_ctx {
  20         struct z_erofs_decompress_req *rq;
  21         /* # of encoded, decoded pages */
  22         unsigned int inpages, outpages;
  23         /* decoded block total length (used for in-place decompression) */
  24         unsigned int oend;
  25 };
  26
  27 static int z_erofs_load_lz4_config(struct super_block *sb,
  28                             struct erofs_super_block *dsb, void *data, int size)
  29 {
  30         struct erofs_sb_info *sbi = EROFS_SB(sb);
  31         struct z_erofs_lz4_cfgs *lz4 = data;
  32         u16 distance;
  33
  34         if (lz4) {
  35                 if (size < sizeof(struct z_erofs_lz4_cfgs)) {
  36                         erofs_err(sb, "invalid lz4 cfgs, size=%u", size);
  37                         return -EINVAL;
  38                 }
  39                 distance = le16_to_cpu(lz4->max_distance);
  40
  41                 sbi->lz4.max_pclusterblks = le16_to_cpu(lz4->max_pclusterblks);
  42                 if (!sbi->lz4.max_pclusterblks) {
  43                         sbi->lz4.max_pclusterblks = 1;  /* reserved case */
  44                 } else if (sbi->lz4.max_pclusterblks >
  45                            erofs_blknr(sb, Z_EROFS_PCLUSTER_MAX_SIZE)) {
  46                         erofs_err(sb, "too large lz4 pclusterblks %u",
  47                                   sbi->lz4.max_pclusterblks);
  48                         return -EINVAL;
  49                 }
  50         } else {
  51                 distance = le16_to_cpu(dsb->u1.lz4_max_distance);
  52                 sbi->lz4.max_pclusterblks = 1;
  53         }
  54
  55         sbi->lz4.max_distance_pages = distance ?
  56                                         DIV_ROUND_UP(distance, PAGE_SIZE) + 1 :
  57                                         LZ4_MAX_DISTANCE_PAGES;
  58         return z_erofs_gbuf_growsize(sbi->lz4.max_pclusterblks);
  59 }
  60
  61 /*
  62  * Fill all gaps with bounce pages if it's a sparse page list. Also check if
  63  * all physical pages are consecutive, which can be seen for moderate CR.
  64  */
  65 static int z_erofs_lz4_prepare_dstpages(struct z_erofs_lz4_decompress_ctx *ctx,
  66                                         struct page **pagepool)
  67 {
  68         struct z_erofs_decompress_req *rq = ctx->rq;
  69         struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
  70         unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
  71                                            BITS_PER_LONG)] = { 0 };
  72         unsigned int lz4_max_distance_pages =
  73                                 EROFS_SB(rq->sb)->lz4.max_distance_pages;
  74         void *kaddr = NULL;
  75         unsigned int i, j, top;
  76
  77         top = 0;
  78         for (i = j = 0; i < ctx->outpages; ++i, ++j) {
  79                 struct page *const page = rq->out[i];
  80                 struct page *victim;
  81
  82                 if (j >= lz4_max_distance_pages)
  83                         j = 0;
  84
  85                 /* 'valid' bounced can only be tested after a complete round */
  86                 if (!rq->fillgaps && test_bit(j, bounced)) {
  87                         DBG_BUGON(i < lz4_max_distance_pages);
  88                         DBG_BUGON(top >= lz4_max_distance_pages);
  89                         availables[top++] = rq->out[i - lz4_max_distance_pages];
  90                 }
  91
  92                 if (page) {
  93                         __clear_bit(j, bounced);
  94                         if (!PageHighMem(page)) {
  95                                 if (!i) {
  96                                         kaddr = page_address(page);
  97                                         continue;
  98                                 }
  99                                 if (kaddr &&
 100                                     kaddr + PAGE_SIZE == page_address(page)) {
 101                                         kaddr += PAGE_SIZE;
 102                                         continue;
 103                                 }
 104                         }
 105                         kaddr = NULL;
 106                         continue;
 107                 }
 108                 kaddr = NULL;
 109                 __set_bit(j, bounced);
 110
 111                 if (top) {
 112                         victim = availables[--top];
 113                 } else {
 114                         victim = __erofs_allocpage(pagepool, rq->gfp, true);
 115                         if (!victim)
 116                                 return -ENOMEM;
 117                         set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
 118                 }
 119                 rq->out[i] = victim;
 120         }
 121         return kaddr ? 1 : 0;
 122 }
 123
 124 static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx,
 125                         void *inpage, void *out, unsigned int *inputmargin,
 126                         int *maptype, bool may_inplace)
 127 {
 128         struct z_erofs_decompress_req *rq = ctx->rq;
 129         unsigned int omargin, total, i;
 130         struct page **in;
 131         void *src, *tmp;
 132
 133         if (rq->inplace_io) {
 134                 omargin = PAGE_ALIGN(ctx->oend) - ctx->oend;
 135                 if (rq->partial_decoding || !may_inplace ||
 136                     omargin < LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize))
 137                         goto docopy;
 138
 139                 for (i = 0; i < ctx->inpages; ++i)
 140                         if (rq->out[ctx->outpages - ctx->inpages + i] !=
 141                             rq->in[i])
 142                                 goto docopy;
 143                 kunmap_local(inpage);
 144                 *maptype = 3;
 145                 return out + ((ctx->outpages - ctx->inpages) << PAGE_SHIFT);
 146         }
 147
 148         if (ctx->inpages <= 1) {
 149                 *maptype = 0;
 150                 return inpage;
 151         }
 152         kunmap_local(inpage);
 153         src = erofs_vm_map_ram(rq->in, ctx->inpages);
 154         if (!src)
 155                 return ERR_PTR(-ENOMEM);
 156         *maptype = 1;
 157         return src;
 158
 159 docopy:
 160         /* Or copy compressed data which can be overlapped to per-CPU buffer */
 161         in = rq->in;
 162         src = z_erofs_get_gbuf(ctx->inpages);
 163         if (!src) {
 164                 DBG_BUGON(1);
 165                 kunmap_local(inpage);
 166                 return ERR_PTR(-EFAULT);
 167         }
 168
 169         tmp = src;
 170         total = rq->inputsize;
 171         while (total) {
 172                 unsigned int page_copycnt =
 173                         min_t(unsigned int, total, PAGE_SIZE - *inputmargin);
 174
 175                 if (!inpage)
 176                         inpage = kmap_local_page(*in);
 177                 memcpy(tmp, inpage + *inputmargin, page_copycnt);
 178                 kunmap_local(inpage);
 179                 inpage = NULL;
 180                 tmp += page_copycnt;
 181                 total -= page_copycnt;
 182                 ++in;
 183                 *inputmargin = 0;
 184         }
 185         *maptype = 2;
 186         return src;
 187 }
 188
 189 /*
 190  * Get the exact inputsize with zero_padding feature.
 191  *  - For LZ4, it should work if zero_padding feature is on (5.3+);
 192  *  - For MicroLZMA, it'd be enabled all the time.
 193  */
 194 int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
 195                          unsigned int padbufsize)
 196 {
 197         const char *padend;
 198
 199         padend = memchr_inv(padbuf, 0, padbufsize);
 200         if (!padend)
 201                 return -EFSCORRUPTED;
 202         rq->inputsize -= padend - padbuf;
 203         rq->pageofs_in += padend - padbuf;
 204         return 0;
 205 }
 206
 207 static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx,
 208                                       u8 *dst)
 209 {
 210         struct z_erofs_decompress_req *rq = ctx->rq;
 211         bool support_0padding = false, may_inplace = false;
 212         unsigned int inputmargin;
 213         u8 *out, *headpage, *src;
 214         int ret, maptype;
 215
 216         DBG_BUGON(*rq->in == NULL);
 217         headpage = kmap_local_page(*rq->in);
 218
 219         /* LZ4 decompression inplace is only safe if zero_padding is enabled */
 220         if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
 221                 support_0padding = true;
 222                 ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
 223                                 min_t(unsigned int, rq->inputsize,
 224                                       rq->sb->s_blocksize - rq->pageofs_in));
 225                 if (ret) {
 226                         kunmap_local(headpage);
 227                         return ret;
 228                 }
 229                 may_inplace = !((rq->pageofs_in + rq->inputsize) &
 230                                 (rq->sb->s_blocksize - 1));
 231         }
 232
 233         inputmargin = rq->pageofs_in;
 234         src = z_erofs_lz4_handle_overlap(ctx, headpage, dst, &inputmargin,
 235                                          &maptype, may_inplace);
 236         if (IS_ERR(src))
 237                 return PTR_ERR(src);
 238
 239         out = dst + rq->pageofs_out;
 240         /* legacy format could compress extra data in a pcluster. */
 241         if (rq->partial_decoding || !support_0padding)
 242                 ret = LZ4_decompress_safe_partial(src + inputmargin, out,
 243                                 rq->inputsize, rq->outputsize, rq->outputsize);
 244         else
 245                 ret = LZ4_decompress_safe(src + inputmargin, out,
 246                                           rq->inputsize, rq->outputsize);
 247
 248         if (ret != rq->outputsize) {
 249                 erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
 250                           ret, rq->inputsize, inputmargin, rq->outputsize);
 251                 if (ret >= 0)
 252                         memset(out + ret, 0, rq->outputsize - ret);
 253                 ret = -EFSCORRUPTED;
 254         } else {
 255                 ret = 0;
 256         }
 257
 258         if (maptype == 0) {
 259                 kunmap_local(headpage);
 260         } else if (maptype == 1) {
 261                 vm_unmap_ram(src, ctx->inpages);
 262         } else if (maptype == 2) {
 263                 z_erofs_put_gbuf(src);
 264         } else if (maptype != 3) {
 265                 DBG_BUGON(1);
 266                 return -EFAULT;
 267         }
 268         return ret;
 269 }
 270
 271 static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
 272                                   struct page **pagepool)
 273 {
 274         struct z_erofs_lz4_decompress_ctx ctx;
 275         unsigned int dst_maptype;
 276         void *dst;
 277         int ret;
 278
 279         ctx.rq = rq;
 280         ctx.oend = rq->pageofs_out + rq->outputsize;
 281         ctx.outpages = PAGE_ALIGN(ctx.oend) >> PAGE_SHIFT;
 282         ctx.inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
 283
 284         /* one optimized fast path only for non bigpcluster cases yet */
 285         if (ctx.inpages == 1 && ctx.outpages == 1 && !rq->inplace_io) {
 286                 DBG_BUGON(!*rq->out);
 287                 dst = kmap_local_page(*rq->out);
 288                 dst_maptype = 0;
 289                 goto dstmap_out;
 290         }
 291
 292         /* general decoding path which can be used for all cases */
 293         ret = z_erofs_lz4_prepare_dstpages(&ctx, pagepool);
 294         if (ret < 0) {
 295                 return ret;
 296         } else if (ret > 0) {
 297                 dst = page_address(*rq->out);
 298                 dst_maptype = 1;
 299         } else {
 300                 dst = erofs_vm_map_ram(rq->out, ctx.outpages);
 301                 if (!dst)
 302                         return -ENOMEM;
 303                 dst_maptype = 2;
 304         }
 305
 306 dstmap_out:
 307         ret = z_erofs_lz4_decompress_mem(&ctx, dst);
 308         if (!dst_maptype)
 309                 kunmap_local(dst);
 310         else if (dst_maptype == 2)
 311                 vm_unmap_ram(dst, ctx.outpages);
 312         return ret;
 313 }
 314
 315 static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
 316                                    struct page **pagepool)
 317 {
 318         const unsigned int nrpages_in =
 319                 PAGE_ALIGN(rq->pageofs_in + rq->inputsize) >> PAGE_SHIFT;
 320         const unsigned int nrpages_out =
 321                 PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
 322         const unsigned int bs = rq->sb->s_blocksize;
 323         unsigned int cur = 0, ni = 0, no, pi, po, insz, cnt;
 324         u8 *kin;
 325
 326         if (rq->outputsize > rq->inputsize)
 327                 return -EOPNOTSUPP;
 328         if (rq->alg == Z_EROFS_COMPRESSION_INTERLACED) {
 329                 cur = bs - (rq->pageofs_out & (bs - 1));
 330                 pi = (rq->pageofs_in + rq->inputsize - cur) & ~PAGE_MASK;
 331                 cur = min(cur, rq->outputsize);
 332                 if (cur && rq->out[0]) {
 333                         kin = kmap_local_page(rq->in[nrpages_in - 1]);
 334                         if (rq->out[0] == rq->in[nrpages_in - 1]) {
 335                                 memmove(kin + rq->pageofs_out, kin + pi, cur);
 336                                 flush_dcache_page(rq->out[0]);
 337                         } else {
 338                                 memcpy_to_page(rq->out[0], rq->pageofs_out,
 339                                                kin + pi, cur);
 340                         }
 341                         kunmap_local(kin);
 342                 }
 343                 rq->outputsize -= cur;
 344         }
 345
 346         for (; rq->outputsize; rq->pageofs_in = 0, cur += PAGE_SIZE, ni++) {
 347                 insz = min(PAGE_SIZE - rq->pageofs_in, rq->outputsize);
 348                 rq->outputsize -= insz;
 349                 if (!rq->in[ni])
 350                         continue;
 351                 kin = kmap_local_page(rq->in[ni]);
 352                 pi = 0;
 353                 do {
 354                         no = (rq->pageofs_out + cur + pi) >> PAGE_SHIFT;
 355                         po = (rq->pageofs_out + cur + pi) & ~PAGE_MASK;
 356                         DBG_BUGON(no >= nrpages_out);
 357                         cnt = min(insz - pi, PAGE_SIZE - po);
 358                         if (rq->out[no] == rq->in[ni]) {
 359                                 memmove(kin + po,
 360                                         kin + rq->pageofs_in + pi, cnt);
 361                                 flush_dcache_page(rq->out[no]);
 362                         } else if (rq->out[no]) {
 363                                 memcpy_to_page(rq->out[no], po,
 364                                                kin + rq->pageofs_in + pi, cnt);
 365                         }
 366                         pi += cnt;
 367                 } while (pi < insz);
 368                 kunmap_local(kin);
 369         }
 370         DBG_BUGON(ni > nrpages_in);
 371         return 0;
 372 }
 373
 374 int z_erofs_stream_switch_bufs(struct z_erofs_stream_dctx *dctx, void **dst,
 375                                void **src, struct page **pgpl)
 376 {
 377         struct z_erofs_decompress_req *rq = dctx->rq;
 378         struct super_block *sb = rq->sb;
 379         struct page **pgo, *tmppage;
 380         unsigned int j;
 381
 382         if (!dctx->avail_out) {
 383                 if (++dctx->no >= dctx->outpages || !rq->outputsize) {
 384                         erofs_err(sb, "insufficient space for decompressed data");
 385                         return -EFSCORRUPTED;
 386                 }
 387
 388                 if (dctx->kout)
 389                         kunmap_local(dctx->kout);
 390                 dctx->avail_out = min(rq->outputsize, PAGE_SIZE - rq->pageofs_out);
 391                 rq->outputsize -= dctx->avail_out;
 392                 pgo = &rq->out[dctx->no];
 393                 if (!*pgo && rq->fillgaps) {            /* deduped */
 394                         *pgo = erofs_allocpage(pgpl, rq->gfp);
 395                         if (!*pgo) {
 396                                 dctx->kout = NULL;
 397                                 return -ENOMEM;
 398                         }
 399                         set_page_private(*pgo, Z_EROFS_SHORTLIVED_PAGE);
 400                 }
 401                 if (*pgo) {
 402                         dctx->kout = kmap_local_page(*pgo);
 403                         *dst = dctx->kout + rq->pageofs_out;
 404                 } else {
 405                         *dst = dctx->kout = NULL;
 406                 }
 407                 rq->pageofs_out = 0;
 408         }
 409
 410         if (dctx->inbuf_pos == dctx->inbuf_sz && rq->inputsize) {
 411                 if (++dctx->ni >= dctx->inpages) {
 412                         erofs_err(sb, "invalid compressed data");
 413                         return -EFSCORRUPTED;
 414                 }
 415                 if (dctx->kout) /* unlike kmap(), take care of the orders */
 416                         kunmap_local(dctx->kout);
 417                 kunmap_local(dctx->kin);
 418
 419                 dctx->inbuf_sz = min_t(u32, rq->inputsize, PAGE_SIZE);
 420                 rq->inputsize -= dctx->inbuf_sz;
 421                 dctx->kin = kmap_local_page(rq->in[dctx->ni]);
 422                 *src = dctx->kin;
 423                 dctx->bounced = false;
 424                 if (dctx->kout) {
 425                         j = (u8 *)*dst - dctx->kout;
 426                         dctx->kout = kmap_local_page(rq->out[dctx->no]);
 427                         *dst = dctx->kout + j;
 428                 }
 429                 dctx->inbuf_pos = 0;
 430         }
 431
 432         /*
 433          * Handle overlapping: Use the given bounce buffer if the input data is
 434          * under processing; Or utilize short-lived pages from the on-stack page
 435          * pool, where pages are shared among the same request.  Note that only
 436          * a few inplace I/O pages need to be doubled.
 437          */
 438         if (!dctx->bounced && rq->out[dctx->no] == rq->in[dctx->ni]) {
 439                 memcpy(dctx->bounce, *src, dctx->inbuf_sz);
 440                 *src = dctx->bounce;
 441                 dctx->bounced = true;
 442         }
 443
 444         for (j = dctx->ni + 1; j < dctx->inpages; ++j) {
 445                 if (rq->out[dctx->no] != rq->in[j])
 446                         continue;
 447                 tmppage = erofs_allocpage(pgpl, rq->gfp);
 448                 if (!tmppage)
 449                         return -ENOMEM;
 450                 set_page_private(tmppage, Z_EROFS_SHORTLIVED_PAGE);
 451                 copy_highpage(tmppage, rq->in[j]);
 452                 rq->in[j] = tmppage;
 453         }
 454         return 0;
 455 }
 456
 457 const struct z_erofs_decompressor *z_erofs_decomp[] = {
 458         [Z_EROFS_COMPRESSION_SHIFTED] = &(const struct z_erofs_decompressor) {
 459                 .decompress = z_erofs_transform_plain,
 460                 .name = "shifted"
 461         },
 462         [Z_EROFS_COMPRESSION_INTERLACED] = &(const struct z_erofs_decompressor) {
 463                 .decompress = z_erofs_transform_plain,
 464                 .name = "interlaced"
 465         },
 466         [Z_EROFS_COMPRESSION_LZ4] = &(const struct z_erofs_decompressor) {
 467                 .config = z_erofs_load_lz4_config,
 468                 .decompress = z_erofs_lz4_decompress,
 469                 .init = z_erofs_gbuf_init,
 470                 .exit = z_erofs_gbuf_exit,
 471                 .name = "lz4"
 472         },
 473 #ifdef CONFIG_EROFS_FS_ZIP_LZMA
 474         [Z_EROFS_COMPRESSION_LZMA] = &z_erofs_lzma_decomp,
 475 #endif
 476 #ifdef CONFIG_EROFS_FS_ZIP_DEFLATE
 477         [Z_EROFS_COMPRESSION_DEFLATE] = &z_erofs_deflate_decomp,
 478 #endif
 479 #ifdef CONFIG_EROFS_FS_ZIP_ZSTD
 480         [Z_EROFS_COMPRESSION_ZSTD] = &z_erofs_zstd_decomp,
 481 #endif
 482 };
 483
 484 int z_erofs_parse_cfgs(struct super_block *sb, struct erofs_super_block *dsb)
 485 {
 486         struct erofs_sb_info *sbi = EROFS_SB(sb);
 487         struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
 488         unsigned int algs, alg;
 489         erofs_off_t offset;
 490         int size, ret = 0;
 491
 492         if (!erofs_sb_has_compr_cfgs(sbi)) {
 493                 sbi->available_compr_algs = 1 << Z_EROFS_COMPRESSION_LZ4;
 494                 return z_erofs_load_lz4_config(sb, dsb, NULL, 0);
 495         }
 496
 497         sbi->available_compr_algs = le16_to_cpu(dsb->u1.available_compr_algs);
 498         if (sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS) {
 499                 erofs_err(sb, "unidentified algorithms %x, please upgrade kernel",
 500                           sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS);
 501                 return -EOPNOTSUPP;
 502         }
 503
 504         erofs_init_metabuf(&buf, sb);
 505         offset = EROFS_SUPER_OFFSET + sbi->sb_size;
 506         alg = 0;
 507         for (algs = sbi->available_compr_algs; algs; algs >>= 1, ++alg) {
 508                 const struct z_erofs_decompressor *dec = z_erofs_decomp[alg];
 509                 void *data;
 510
 511                 if (!(algs & 1))
 512                         continue;
 513
 514                 data = erofs_read_metadata(sb, &buf, &offset, &size);
 515                 if (IS_ERR(data)) {
 516                         ret = PTR_ERR(data);
 517                         break;
 518                 }
 519
 520                 if (alg < Z_EROFS_COMPRESSION_MAX && dec && dec->config) {
 521                         ret = dec->config(sb, dsb, data, size);
 522                 } else {
 523                         erofs_err(sb, "algorithm %d isn't enabled on this kernel",
 524                                   alg);
 525                         ret = -EOPNOTSUPP;
 526                 }
 527                 kfree(data);
 528                 if (ret)
 529                         break;
 530         }
 531         erofs_put_metabuf(&buf);
 532         return ret;
 533 }
 534
 535 int __init z_erofs_init_decompressor(void)
 536 {
 537         int i, err;
 538
 539         for (i = 0; i < Z_EROFS_COMPRESSION_MAX; ++i) {
 540                 err = z_erofs_decomp[i] ? z_erofs_decomp[i]->init() : 0;
 541                 if (err) {
 542                         while (i--)
 543                                 if (z_erofs_decomp[i])
 544                                         z_erofs_decomp[i]->exit();
 545                         return err;
 546                 }
 547         }
 548         return 0;
 549 }
 550
 551 void z_erofs_exit_decompressor(void)
 552 {
 553         int i;
 554
 555         for (i = 0; i < Z_EROFS_COMPRESSION_MAX; ++i)
 556                 if (z_erofs_decomp[i])
 557                         z_erofs_decomp[i]->exit();
 558 }