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  */
   6 #include "compress.h"
   7 #include <linux/lz4.h>
   8
   9 #ifndef LZ4_DISTANCE_MAX        /* history window size */
  10 #define LZ4_DISTANCE_MAX 65535  /* set to maximum value by default */
  11 #endif
  12
  13 #define LZ4_MAX_DISTANCE_PAGES  (DIV_ROUND_UP(LZ4_DISTANCE_MAX, PAGE_SIZE) + 1)
  14 #ifndef LZ4_DECOMPRESS_INPLACE_MARGIN
  15 #define LZ4_DECOMPRESS_INPLACE_MARGIN(srcsize)  (((srcsize) >> 8) + 32)
  16 #endif
  17
  18 struct z_erofs_lz4_decompress_ctx {
  19         struct z_erofs_decompress_req *rq;
  20         /* # of encoded, decoded pages */
  21         unsigned int inpages, outpages;
  22         /* decoded block total length (used for in-place decompression) */
  23         unsigned int oend;
  24 };
  25
  26 static int z_erofs_load_lz4_config(struct super_block *sb,
  27                             struct erofs_super_block *dsb, void *data, int size)
  28 {
  29         struct erofs_sb_info *sbi = EROFS_SB(sb);
  30         struct z_erofs_lz4_cfgs *lz4 = data;
  31         u16 distance;
  32
  33         if (lz4) {
  34                 if (size < sizeof(struct z_erofs_lz4_cfgs)) {
  35                         erofs_err(sb, "invalid lz4 cfgs, size=%u", size);
  36                         return -EINVAL;
  37                 }
  38                 distance = le16_to_cpu(lz4->max_distance);
  39
  40                 sbi->lz4.max_pclusterblks = le16_to_cpu(lz4->max_pclusterblks);
  41                 if (!sbi->lz4.max_pclusterblks) {
  42                         sbi->lz4.max_pclusterblks = 1;  /* reserved case */
  43                 } else if (sbi->lz4.max_pclusterblks >
  44                            erofs_blknr(sb, Z_EROFS_PCLUSTER_MAX_SIZE)) {
  45                         erofs_err(sb, "too large lz4 pclusterblks %u",
  46                                   sbi->lz4.max_pclusterblks);
  47                         return -EINVAL;
  48                 }
  49         } else {
  50                 distance = le16_to_cpu(dsb->u1.lz4_max_distance);
  51                 sbi->lz4.max_pclusterblks = 1;
  52         }
  53
  54         sbi->lz4.max_distance_pages = distance ?
  55                                         DIV_ROUND_UP(distance, PAGE_SIZE) + 1 :
  56                                         LZ4_MAX_DISTANCE_PAGES;
  57         return erofs_pcpubuf_growsize(sbi->lz4.max_pclusterblks);
  58 }
  59
  60 /*
  61  * Fill all gaps with bounce pages if it's a sparse page list. Also check if
  62  * all physical pages are consecutive, which can be seen for moderate CR.
  63  */
  64 static int z_erofs_lz4_prepare_dstpages(struct z_erofs_lz4_decompress_ctx *ctx,
  65                                         struct page **pagepool)
  66 {
  67         struct z_erofs_decompress_req *rq = ctx->rq;
  68         struct page *availables[LZ4_MAX_DISTANCE_PAGES] = { NULL };
  69         unsigned long bounced[DIV_ROUND_UP(LZ4_MAX_DISTANCE_PAGES,
  70                                            BITS_PER_LONG)] = { 0 };
  71         unsigned int lz4_max_distance_pages =
  72                                 EROFS_SB(rq->sb)->lz4.max_distance_pages;
  73         void *kaddr = NULL;
  74         unsigned int i, j, top;
  75
  76         top = 0;
  77         for (i = j = 0; i < ctx->outpages; ++i, ++j) {
  78                 struct page *const page = rq->out[i];
  79                 struct page *victim;
  80
  81                 if (j >= lz4_max_distance_pages)
  82                         j = 0;
  83
  84                 /* 'valid' bounced can only be tested after a complete round */
  85                 if (!rq->fillgaps && test_bit(j, bounced)) {
  86                         DBG_BUGON(i < lz4_max_distance_pages);
  87                         DBG_BUGON(top >= lz4_max_distance_pages);
  88                         availables[top++] = rq->out[i - lz4_max_distance_pages];
  89                 }
  90
  91                 if (page) {
  92                         __clear_bit(j, bounced);
  93                         if (!PageHighMem(page)) {
  94                                 if (!i) {
  95                                         kaddr = page_address(page);
  96                                         continue;
  97                                 }
  98                                 if (kaddr &&
  99                                     kaddr + PAGE_SIZE == page_address(page)) {
 100                                         kaddr += PAGE_SIZE;
 101                                         continue;
 102                                 }
 103                         }
 104                         kaddr = NULL;
 105                         continue;
 106                 }
 107                 kaddr = NULL;
 108                 __set_bit(j, bounced);
 109
 110                 if (top) {
 111                         victim = availables[--top];
 112                         get_page(victim);
 113                 } else {
 114                         victim = erofs_allocpage(pagepool,
 115                                                  GFP_KERNEL | __GFP_NOFAIL);
 116                         set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
 117                 }
 118                 rq->out[i] = victim;
 119         }
 120         return kaddr ? 1 : 0;
 121 }
 122
 123 static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx,
 124                         void *inpage, unsigned int *inputmargin, int *maptype,
 125                         bool may_inplace)
 126 {
 127         struct z_erofs_decompress_req *rq = ctx->rq;
 128         unsigned int omargin, total, i, j;
 129         struct page **in;
 130         void *src, *tmp;
 131
 132         if (rq->inplace_io) {
 133                 omargin = PAGE_ALIGN(ctx->oend) - ctx->oend;
 134                 if (rq->partial_decoding || !may_inplace ||
 135                     omargin < LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize))
 136                         goto docopy;
 137
 138                 for (i = 0; i < ctx->inpages; ++i) {
 139                         DBG_BUGON(rq->in[i] == NULL);
 140                         for (j = 0; j < ctx->outpages - ctx->inpages + i; ++j)
 141                                 if (rq->out[j] == rq->in[i])
 142                                         goto docopy;
 143                 }
 144         }
 145
 146         if (ctx->inpages <= 1) {
 147                 *maptype = 0;
 148                 return inpage;
 149         }
 150         kunmap_local(inpage);
 151         might_sleep();
 152         src = erofs_vm_map_ram(rq->in, ctx->inpages);
 153         if (!src)
 154                 return ERR_PTR(-ENOMEM);
 155         *maptype = 1;
 156         return src;
 157
 158 docopy:
 159         /* Or copy compressed data which can be overlapped to per-CPU buffer */
 160         in = rq->in;
 161         src = erofs_get_pcpubuf(ctx->inpages);
 162         if (!src) {
 163                 DBG_BUGON(1);
 164                 kunmap_local(inpage);
 165                 return ERR_PTR(-EFAULT);
 166         }
 167
 168         tmp = src;
 169         total = rq->inputsize;
 170         while (total) {
 171                 unsigned int page_copycnt =
 172                         min_t(unsigned int, total, PAGE_SIZE - *inputmargin);
 173
 174                 if (!inpage)
 175                         inpage = kmap_local_page(*in);
 176                 memcpy(tmp, inpage + *inputmargin, page_copycnt);
 177                 kunmap_local(inpage);
 178                 inpage = NULL;
 179                 tmp += page_copycnt;
 180                 total -= page_copycnt;
 181                 ++in;
 182                 *inputmargin = 0;
 183         }
 184         *maptype = 2;
 185         return src;
 186 }
 187
 188 /*
 189  * Get the exact inputsize with zero_padding feature.
 190  *  - For LZ4, it should work if zero_padding feature is on (5.3+);
 191  *  - For MicroLZMA, it'd be enabled all the time.
 192  */
 193 int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
 194                          unsigned int padbufsize)
 195 {
 196         const char *padend;
 197
 198         padend = memchr_inv(padbuf, 0, padbufsize);
 199         if (!padend)
 200                 return -EFSCORRUPTED;
 201         rq->inputsize -= padend - padbuf;
 202         rq->pageofs_in += padend - padbuf;
 203         return 0;
 204 }
 205
 206 static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx,
 207                                       u8 *out)
 208 {
 209         struct z_erofs_decompress_req *rq = ctx->rq;
 210         bool support_0padding = false, may_inplace = false;
 211         unsigned int inputmargin;
 212         u8 *headpage, *src;
 213         int ret, maptype;
 214
 215         DBG_BUGON(*rq->in == NULL);
 216         headpage = kmap_local_page(*rq->in);
 217
 218         /* LZ4 decompression inplace is only safe if zero_padding is enabled */
 219         if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
 220                 support_0padding = true;
 221                 ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
 222                                 min_t(unsigned int, rq->inputsize,
 223                                       rq->sb->s_blocksize - rq->pageofs_in));
 224                 if (ret) {
 225                         kunmap_local(headpage);
 226                         return ret;
 227                 }
 228                 may_inplace = !((rq->pageofs_in + rq->inputsize) &
 229                                 (rq->sb->s_blocksize - 1));
 230         }
 231
 232         inputmargin = rq->pageofs_in;
 233         src = z_erofs_lz4_handle_overlap(ctx, headpage, &inputmargin,
 234                                          &maptype, may_inplace);
 235         if (IS_ERR(src))
 236                 return PTR_ERR(src);
 237
 238         /* legacy format could compress extra data in a pcluster. */
 239         if (rq->partial_decoding || !support_0padding)
 240                 ret = LZ4_decompress_safe_partial(src + inputmargin, out,
 241                                 rq->inputsize, rq->outputsize, rq->outputsize);
 242         else
 243                 ret = LZ4_decompress_safe(src + inputmargin, out,
 244                                           rq->inputsize, rq->outputsize);
 245
 246         if (ret != rq->outputsize) {
 247                 erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
 248                           ret, rq->inputsize, inputmargin, rq->outputsize);
 249
 250                 print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
 251                                16, 1, src + inputmargin, rq->inputsize, true);
 252                 print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
 253                                16, 1, out, rq->outputsize, true);
 254
 255                 if (ret >= 0)
 256                         memset(out + ret, 0, rq->outputsize - ret);
 257                 ret = -EIO;
 258         } else {
 259                 ret = 0;
 260         }
 261
 262         if (maptype == 0) {
 263                 kunmap_local(headpage);
 264         } else if (maptype == 1) {
 265                 vm_unmap_ram(src, ctx->inpages);
 266         } else if (maptype == 2) {
 267                 erofs_put_pcpubuf(src);
 268         } else {
 269                 DBG_BUGON(1);
 270                 return -EFAULT;
 271         }
 272         return ret;
 273 }
 274
 275 static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
 276                                   struct page **pagepool)
 277 {
 278         struct z_erofs_lz4_decompress_ctx ctx;
 279         unsigned int dst_maptype;
 280         void *dst;
 281         int ret;
 282
 283         ctx.rq = rq;
 284         ctx.oend = rq->pageofs_out + rq->outputsize;
 285         ctx.outpages = PAGE_ALIGN(ctx.oend) >> PAGE_SHIFT;
 286         ctx.inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
 287
 288         /* one optimized fast path only for non bigpcluster cases yet */
 289         if (ctx.inpages == 1 && ctx.outpages == 1 && !rq->inplace_io) {
 290                 DBG_BUGON(!*rq->out);
 291                 dst = kmap_local_page(*rq->out);
 292                 dst_maptype = 0;
 293                 goto dstmap_out;
 294         }
 295
 296         /* general decoding path which can be used for all cases */
 297         ret = z_erofs_lz4_prepare_dstpages(&ctx, pagepool);
 298         if (ret < 0) {
 299                 return ret;
 300         } else if (ret > 0) {
 301                 dst = page_address(*rq->out);
 302                 dst_maptype = 1;
 303         } else {
 304                 dst = erofs_vm_map_ram(rq->out, ctx.outpages);
 305                 if (!dst)
 306                         return -ENOMEM;
 307                 dst_maptype = 2;
 308         }
 309
 310 dstmap_out:
 311         ret = z_erofs_lz4_decompress_mem(&ctx, dst + rq->pageofs_out);
 312         if (!dst_maptype)
 313                 kunmap_local(dst);
 314         else if (dst_maptype == 2)
 315                 vm_unmap_ram(dst, ctx.outpages);
 316         return ret;
 317 }
 318
 319 static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
 320                                    struct page **pagepool)
 321 {
 322         const unsigned int inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
 323         const unsigned int outpages =
 324                 PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
 325         const unsigned int righthalf = min_t(unsigned int, rq->outputsize,
 326                                              PAGE_SIZE - rq->pageofs_out);
 327         const unsigned int lefthalf = rq->outputsize - righthalf;
 328         const unsigned int interlaced_offset =
 329                 rq->alg == Z_EROFS_COMPRESSION_SHIFTED ? 0 : rq->pageofs_out;
 330         u8 *src;
 331
 332         if (outpages > 2 && rq->alg == Z_EROFS_COMPRESSION_SHIFTED) {
 333                 DBG_BUGON(1);
 334                 return -EFSCORRUPTED;
 335         }
 336
 337         if (rq->out[0] == *rq->in) {
 338                 DBG_BUGON(rq->pageofs_out);
 339                 return 0;
 340         }
 341
 342         src = kmap_local_page(rq->in[inpages - 1]) + rq->pageofs_in;
 343         if (rq->out[0])
 344                 memcpy_to_page(rq->out[0], rq->pageofs_out,
 345                                src + interlaced_offset, righthalf);
 346
 347         if (outpages > inpages) {
 348                 DBG_BUGON(!rq->out[outpages - 1]);
 349                 if (rq->out[outpages - 1] != rq->in[inpages - 1]) {
 350                         memcpy_to_page(rq->out[outpages - 1], 0, src +
 351                                         (interlaced_offset ? 0 : righthalf),
 352                                        lefthalf);
 353                 } else if (!interlaced_offset) {
 354                         memmove(src, src + righthalf, lefthalf);
 355                         flush_dcache_page(rq->in[inpages - 1]);
 356                 }
 357         }
 358         kunmap_local(src);
 359         return 0;
 360 }
 361
 362 const struct z_erofs_decompressor erofs_decompressors[] = {
 363         [Z_EROFS_COMPRESSION_SHIFTED] = {
 364                 .decompress = z_erofs_transform_plain,
 365                 .name = "shifted"
 366         },
 367         [Z_EROFS_COMPRESSION_INTERLACED] = {
 368                 .decompress = z_erofs_transform_plain,
 369                 .name = "interlaced"
 370         },
 371         [Z_EROFS_COMPRESSION_LZ4] = {
 372                 .config = z_erofs_load_lz4_config,
 373                 .decompress = z_erofs_lz4_decompress,
 374                 .name = "lz4"
 375         },
 376 #ifdef CONFIG_EROFS_FS_ZIP_LZMA
 377         [Z_EROFS_COMPRESSION_LZMA] = {
 378                 .config = z_erofs_load_lzma_config,
 379                 .decompress = z_erofs_lzma_decompress,
 380                 .name = "lzma"
 381         },
 382 #endif
 383 #ifdef CONFIG_EROFS_FS_ZIP_DEFLATE
 384         [Z_EROFS_COMPRESSION_DEFLATE] = {
 385                 .config = z_erofs_load_deflate_config,
 386                 .decompress = z_erofs_deflate_decompress,
 387                 .name = "deflate"
 388         },
 389 #endif
 390 };
 391
 392 int z_erofs_parse_cfgs(struct super_block *sb, struct erofs_super_block *dsb)
 393 {
 394         struct erofs_sb_info *sbi = EROFS_SB(sb);
 395         struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
 396         unsigned int algs, alg;
 397         erofs_off_t offset;
 398         int size, ret = 0;
 399
 400         if (!erofs_sb_has_compr_cfgs(sbi)) {
 401                 sbi->available_compr_algs = Z_EROFS_COMPRESSION_LZ4;
 402                 return z_erofs_load_lz4_config(sb, dsb, NULL, 0);
 403         }
 404
 405         sbi->available_compr_algs = le16_to_cpu(dsb->u1.available_compr_algs);
 406         if (sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS) {
 407                 erofs_err(sb, "unidentified algorithms %x, please upgrade kernel",
 408                           sbi->available_compr_algs & ~Z_EROFS_ALL_COMPR_ALGS);
 409                 return -EOPNOTSUPP;
 410         }
 411
 412         erofs_init_metabuf(&buf, sb);
 413         offset = EROFS_SUPER_OFFSET + sbi->sb_size;
 414         alg = 0;
 415         for (algs = sbi->available_compr_algs; algs; algs >>= 1, ++alg) {
 416                 void *data;
 417
 418                 if (!(algs & 1))
 419                         continue;
 420
 421                 data = erofs_read_metadata(sb, &buf, &offset, &size);
 422                 if (IS_ERR(data)) {
 423                         ret = PTR_ERR(data);
 424                         break;
 425                 }
 426
 427                 if (alg >= ARRAY_SIZE(erofs_decompressors) ||
 428                     !erofs_decompressors[alg].config) {
 429                         erofs_err(sb, "algorithm %d isn't enabled on this kernel",
 430                                   alg);
 431                         ret = -EOPNOTSUPP;
 432                 } else {
 433                         ret = erofs_decompressors[alg].config(sb,
 434                                         dsb, data, size);
 435                 }
 436
 437                 kfree(data);
 438                 if (ret)
 439                         break;
 440         }
 441         erofs_put_metabuf(&buf);
 442         return ret;
 443 }