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/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_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 int z_erofs_load_lz4_config(struct super_block *sb,
  28                             struct erofs_super_block *dsb,
  29                             struct z_erofs_lz4_cfgs *lz4, int size)
  30 {
  31         struct erofs_sb_info *sbi = EROFS_SB(sb);
  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                            Z_EROFS_PCLUSTER_MAX_SIZE / EROFS_BLKSIZ) {
  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 erofs_pcpubuf_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                         get_page(victim);
 114                 } else {
 115                         victim = erofs_allocpage(pagepool,
 116                                                  GFP_KERNEL | __GFP_NOFAIL);
 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, unsigned int *inputmargin, int *maptype,
 126                         bool may_inplace)
 127 {
 128         struct z_erofs_decompress_req *rq = ctx->rq;
 129         unsigned int omargin, total, i, j;
 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                         DBG_BUGON(rq->in[i] == NULL);
 141                         for (j = 0; j < ctx->outpages - ctx->inpages + i; ++j)
 142                                 if (rq->out[j] == rq->in[i])
 143                                         goto docopy;
 144                 }
 145         }
 146
 147         if (ctx->inpages <= 1) {
 148                 *maptype = 0;
 149                 return inpage;
 150         }
 151         kunmap_atomic(inpage);
 152         might_sleep();
 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 = erofs_get_pcpubuf(ctx->inpages);
 163         if (!src) {
 164                 DBG_BUGON(1);
 165                 kunmap_atomic(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_atomic(*in);
 177                 memcpy(tmp, inpage + *inputmargin, page_copycnt);
 178                 kunmap_atomic(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 *out)
 209 {
 210         struct z_erofs_decompress_req *rq = ctx->rq;
 211         bool support_0padding = false, may_inplace = false;
 212         unsigned int inputmargin;
 213         u8 *headpage, *src;
 214         int ret, maptype;
 215
 216         DBG_BUGON(*rq->in == NULL);
 217         headpage = kmap_atomic(*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                                       EROFS_BLKSIZ - rq->pageofs_in));
 225                 if (ret) {
 226                         kunmap_atomic(headpage);
 227                         return ret;
 228                 }
 229                 may_inplace = !((rq->pageofs_in + rq->inputsize) &
 230                                 (EROFS_BLKSIZ - 1));
 231         }
 232
 233         inputmargin = rq->pageofs_in;
 234         src = z_erofs_lz4_handle_overlap(ctx, headpage, &inputmargin,
 235                                          &maptype, may_inplace);
 236         if (IS_ERR(src))
 237                 return PTR_ERR(src);
 238
 239         /* legacy format could compress extra data in a pcluster. */
 240         if (rq->partial_decoding || !support_0padding)
 241                 ret = LZ4_decompress_safe_partial(src + inputmargin, out,
 242                                 rq->inputsize, rq->outputsize, rq->outputsize);
 243         else
 244                 ret = LZ4_decompress_safe(src + inputmargin, out,
 245                                           rq->inputsize, rq->outputsize);
 246
 247         if (ret != rq->outputsize) {
 248                 erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
 249                           ret, rq->inputsize, inputmargin, rq->outputsize);
 250
 251                 print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
 252                                16, 1, src + inputmargin, rq->inputsize, true);
 253                 print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
 254                                16, 1, out, rq->outputsize, true);
 255
 256                 if (ret >= 0)
 257                         memset(out + ret, 0, rq->outputsize - ret);
 258                 ret = -EIO;
 259         } else {
 260                 ret = 0;
 261         }
 262
 263         if (maptype == 0) {
 264                 kunmap_atomic(headpage);
 265         } else if (maptype == 1) {
 266                 vm_unmap_ram(src, ctx->inpages);
 267         } else if (maptype == 2) {
 268                 erofs_put_pcpubuf(src);
 269         } else {
 270                 DBG_BUGON(1);
 271                 return -EFAULT;
 272         }
 273         return ret;
 274 }
 275
 276 static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
 277                                   struct page **pagepool)
 278 {
 279         struct z_erofs_lz4_decompress_ctx ctx;
 280         unsigned int dst_maptype;
 281         void *dst;
 282         int ret;
 283
 284         ctx.rq = rq;
 285         ctx.oend = rq->pageofs_out + rq->outputsize;
 286         ctx.outpages = PAGE_ALIGN(ctx.oend) >> PAGE_SHIFT;
 287         ctx.inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
 288
 289         /* one optimized fast path only for non bigpcluster cases yet */
 290         if (ctx.inpages == 1 && ctx.outpages == 1 && !rq->inplace_io) {
 291                 DBG_BUGON(!*rq->out);
 292                 dst = kmap_atomic(*rq->out);
 293                 dst_maptype = 0;
 294                 goto dstmap_out;
 295         }
 296
 297         /* general decoding path which can be used for all cases */
 298         ret = z_erofs_lz4_prepare_dstpages(&ctx, pagepool);
 299         if (ret < 0) {
 300                 return ret;
 301         } else if (ret > 0) {
 302                 dst = page_address(*rq->out);
 303                 dst_maptype = 1;
 304         } else {
 305                 dst = erofs_vm_map_ram(rq->out, ctx.outpages);
 306                 if (!dst)
 307                         return -ENOMEM;
 308                 dst_maptype = 2;
 309         }
 310
 311 dstmap_out:
 312         ret = z_erofs_lz4_decompress_mem(&ctx, dst + rq->pageofs_out);
 313         if (!dst_maptype)
 314                 kunmap_atomic(dst);
 315         else if (dst_maptype == 2)
 316                 vm_unmap_ram(dst, ctx.outpages);
 317         return ret;
 318 }
 319
 320 static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq,
 321                                    struct page **pagepool)
 322 {
 323         const unsigned int inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
 324         const unsigned int outpages =
 325                 PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
 326         const unsigned int righthalf = min_t(unsigned int, rq->outputsize,
 327                                              PAGE_SIZE - rq->pageofs_out);
 328         const unsigned int lefthalf = rq->outputsize - righthalf;
 329         const unsigned int interlaced_offset =
 330                 rq->alg == Z_EROFS_COMPRESSION_SHIFTED ? 0 : rq->pageofs_out;
 331         unsigned char *src, *dst;
 332
 333         if (outpages > 2 && rq->alg == Z_EROFS_COMPRESSION_SHIFTED) {
 334                 DBG_BUGON(1);
 335                 return -EFSCORRUPTED;
 336         }
 337
 338         if (rq->out[0] == *rq->in) {
 339                 DBG_BUGON(rq->pageofs_out);
 340                 return 0;
 341         }
 342
 343         src = kmap_local_page(rq->in[inpages - 1]) + rq->pageofs_in;
 344         if (rq->out[0]) {
 345                 dst = kmap_local_page(rq->out[0]);
 346                 memcpy(dst + rq->pageofs_out, src + interlaced_offset,
 347                        righthalf);
 348                 kunmap_local(dst);
 349         }
 350
 351         if (outpages > inpages) {
 352                 DBG_BUGON(!rq->out[outpages - 1]);
 353                 if (rq->out[outpages - 1] != rq->in[inpages - 1]) {
 354                         dst = kmap_local_page(rq->out[outpages - 1]);
 355                         memcpy(dst, interlaced_offset ? src :
 356                                         (src + righthalf), lefthalf);
 357                         kunmap_local(dst);
 358                 } else if (!interlaced_offset) {
 359                         memmove(src, src + righthalf, lefthalf);
 360                 }
 361         }
 362         kunmap_local(src);
 363         return 0;
 364 }
 365
 366 static struct z_erofs_decompressor decompressors[] = {
 367         [Z_EROFS_COMPRESSION_SHIFTED] = {
 368                 .decompress = z_erofs_transform_plain,
 369                 .name = "shifted"
 370         },
 371         [Z_EROFS_COMPRESSION_INTERLACED] = {
 372                 .decompress = z_erofs_transform_plain,
 373                 .name = "interlaced"
 374         },
 375         [Z_EROFS_COMPRESSION_LZ4] = {
 376                 .decompress = z_erofs_lz4_decompress,
 377                 .name = "lz4"
 378         },
 379 #ifdef CONFIG_EROFS_FS_ZIP_LZMA
 380         [Z_EROFS_COMPRESSION_LZMA] = {
 381                 .decompress = z_erofs_lzma_decompress,
 382                 .name = "lzma"
 383         },
 384 #endif
 385 };
 386
 387 int z_erofs_decompress(struct z_erofs_decompress_req *rq,
 388                        struct page **pagepool)
 389 {
 390         return decompressors[rq->alg].decompress(rq, pagepool);
 391 }