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 (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 (kaddr) {
  95                                 if (kaddr + PAGE_SIZE == page_address(page))
  96                                         kaddr += PAGE_SIZE;
  97                                 else
  98                                         kaddr = NULL;
  99                         } else if (!i) {
 100                                 kaddr = page_address(page);
 101                         }
 102                         continue;
 103                 }
 104                 kaddr = NULL;
 105                 __set_bit(j, bounced);
 106
 107                 if (top) {
 108                         victim = availables[--top];
 109                         get_page(victim);
 110                 } else {
 111                         victim = erofs_allocpage(pagepool,
 112                                                  GFP_KERNEL | __GFP_NOFAIL);
 113                         set_page_private(victim, Z_EROFS_SHORTLIVED_PAGE);
 114                 }
 115                 rq->out[i] = victim;
 116         }
 117         return kaddr ? 1 : 0;
 118 }
 119
 120 static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx,
 121                         void *inpage, unsigned int *inputmargin, int *maptype,
 122                         bool may_inplace)
 123 {
 124         struct z_erofs_decompress_req *rq = ctx->rq;
 125         unsigned int omargin, total, i, j;
 126         struct page **in;
 127         void *src, *tmp;
 128
 129         if (rq->inplace_io) {
 130                 omargin = PAGE_ALIGN(ctx->oend) - ctx->oend;
 131                 if (rq->partial_decoding || !may_inplace ||
 132                     omargin < LZ4_DECOMPRESS_INPLACE_MARGIN(rq->inputsize))
 133                         goto docopy;
 134
 135                 for (i = 0; i < ctx->inpages; ++i) {
 136                         DBG_BUGON(rq->in[i] == NULL);
 137                         for (j = 0; j < ctx->outpages - ctx->inpages + i; ++j)
 138                                 if (rq->out[j] == rq->in[i])
 139                                         goto docopy;
 140                 }
 141         }
 142
 143         if (ctx->inpages <= 1) {
 144                 *maptype = 0;
 145                 return inpage;
 146         }
 147         kunmap_atomic(inpage);
 148         might_sleep();
 149         src = erofs_vm_map_ram(rq->in, ctx->inpages);
 150         if (!src)
 151                 return ERR_PTR(-ENOMEM);
 152         *maptype = 1;
 153         return src;
 154
 155 docopy:
 156         /* Or copy compressed data which can be overlapped to per-CPU buffer */
 157         in = rq->in;
 158         src = erofs_get_pcpubuf(ctx->inpages);
 159         if (!src) {
 160                 DBG_BUGON(1);
 161                 kunmap_atomic(inpage);
 162                 return ERR_PTR(-EFAULT);
 163         }
 164
 165         tmp = src;
 166         total = rq->inputsize;
 167         while (total) {
 168                 unsigned int page_copycnt =
 169                         min_t(unsigned int, total, PAGE_SIZE - *inputmargin);
 170
 171                 if (!inpage)
 172                         inpage = kmap_atomic(*in);
 173                 memcpy(tmp, inpage + *inputmargin, page_copycnt);
 174                 kunmap_atomic(inpage);
 175                 inpage = NULL;
 176                 tmp += page_copycnt;
 177                 total -= page_copycnt;
 178                 ++in;
 179                 *inputmargin = 0;
 180         }
 181         *maptype = 2;
 182         return src;
 183 }
 184
 185 /*
 186  * Get the exact inputsize with zero_padding feature.
 187  *  - For LZ4, it should work if zero_padding feature is on (5.3+);
 188  *  - For MicroLZMA, it'd be enabled all the time.
 189  */
 190 int z_erofs_fixup_insize(struct z_erofs_decompress_req *rq, const char *padbuf,
 191                          unsigned int padbufsize)
 192 {
 193         const char *padend;
 194
 195         padend = memchr_inv(padbuf, 0, padbufsize);
 196         if (!padend)
 197                 return -EFSCORRUPTED;
 198         rq->inputsize -= padend - padbuf;
 199         rq->pageofs_in += padend - padbuf;
 200         return 0;
 201 }
 202
 203 static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx,
 204                                       u8 *out)
 205 {
 206         struct z_erofs_decompress_req *rq = ctx->rq;
 207         bool support_0padding = false, may_inplace = false;
 208         unsigned int inputmargin;
 209         u8 *headpage, *src;
 210         int ret, maptype;
 211
 212         DBG_BUGON(*rq->in == NULL);
 213         headpage = kmap_atomic(*rq->in);
 214
 215         /* LZ4 decompression inplace is only safe if zero_padding is enabled */
 216         if (erofs_sb_has_zero_padding(EROFS_SB(rq->sb))) {
 217                 support_0padding = true;
 218                 ret = z_erofs_fixup_insize(rq, headpage + rq->pageofs_in,
 219                                 min_t(unsigned int, rq->inputsize,
 220                                       EROFS_BLKSIZ - rq->pageofs_in));
 221                 if (ret) {
 222                         kunmap_atomic(headpage);
 223                         return ret;
 224                 }
 225                 may_inplace = !((rq->pageofs_in + rq->inputsize) &
 226                                 (EROFS_BLKSIZ - 1));
 227         }
 228
 229         inputmargin = rq->pageofs_in;
 230         src = z_erofs_lz4_handle_overlap(ctx, headpage, &inputmargin,
 231                                          &maptype, may_inplace);
 232         if (IS_ERR(src))
 233                 return PTR_ERR(src);
 234
 235         /* legacy format could compress extra data in a pcluster. */
 236         if (rq->partial_decoding || !support_0padding)
 237                 ret = LZ4_decompress_safe_partial(src + inputmargin, out,
 238                                 rq->inputsize, rq->outputsize, rq->outputsize);
 239         else
 240                 ret = LZ4_decompress_safe(src + inputmargin, out,
 241                                           rq->inputsize, rq->outputsize);
 242
 243         if (ret != rq->outputsize) {
 244                 erofs_err(rq->sb, "failed to decompress %d in[%u, %u] out[%u]",
 245                           ret, rq->inputsize, inputmargin, rq->outputsize);
 246
 247                 print_hex_dump(KERN_DEBUG, "[ in]: ", DUMP_PREFIX_OFFSET,
 248                                16, 1, src + inputmargin, rq->inputsize, true);
 249                 print_hex_dump(KERN_DEBUG, "[out]: ", DUMP_PREFIX_OFFSET,
 250                                16, 1, out, rq->outputsize, true);
 251
 252                 if (ret >= 0)
 253                         memset(out + ret, 0, rq->outputsize - ret);
 254                 ret = -EIO;
 255         } else {
 256                 ret = 0;
 257         }
 258
 259         if (maptype == 0) {
 260                 kunmap_atomic(headpage);
 261         } else if (maptype == 1) {
 262                 vm_unmap_ram(src, ctx->inpages);
 263         } else if (maptype == 2) {
 264                 erofs_put_pcpubuf(src);
 265         } else {
 266                 DBG_BUGON(1);
 267                 return -EFAULT;
 268         }
 269         return ret;
 270 }
 271
 272 static int z_erofs_lz4_decompress(struct z_erofs_decompress_req *rq,
 273                                   struct page **pagepool)
 274 {
 275         struct z_erofs_lz4_decompress_ctx ctx;
 276         unsigned int dst_maptype;
 277         void *dst;
 278         int ret;
 279
 280         ctx.rq = rq;
 281         ctx.oend = rq->pageofs_out + rq->outputsize;
 282         ctx.outpages = PAGE_ALIGN(ctx.oend) >> PAGE_SHIFT;
 283         ctx.inpages = PAGE_ALIGN(rq->inputsize) >> PAGE_SHIFT;
 284
 285         /* one optimized fast path only for non bigpcluster cases yet */
 286         if (ctx.inpages == 1 && ctx.outpages == 1 && !rq->inplace_io) {
 287                 DBG_BUGON(!*rq->out);
 288                 dst = kmap_atomic(*rq->out);
 289                 dst_maptype = 0;
 290                 goto dstmap_out;
 291         }
 292
 293         /* general decoding path which can be used for all cases */
 294         ret = z_erofs_lz4_prepare_dstpages(&ctx, pagepool);
 295         if (ret < 0) {
 296                 return ret;
 297         } else if (ret > 0) {
 298                 dst = page_address(*rq->out);
 299                 dst_maptype = 1;
 300         } else {
 301                 dst = erofs_vm_map_ram(rq->out, ctx.outpages);
 302                 if (!dst)
 303                         return -ENOMEM;
 304                 dst_maptype = 2;
 305         }
 306
 307 dstmap_out:
 308         ret = z_erofs_lz4_decompress_mem(&ctx, dst + rq->pageofs_out);
 309         if (!dst_maptype)
 310                 kunmap_atomic(dst);
 311         else if (dst_maptype == 2)
 312                 vm_unmap_ram(dst, ctx.outpages);
 313         return ret;
 314 }
 315
 316 static int z_erofs_shifted_transform(struct z_erofs_decompress_req *rq,
 317                                      struct page **pagepool)
 318 {
 319         const unsigned int nrpages_out =
 320                 PAGE_ALIGN(rq->pageofs_out + rq->outputsize) >> PAGE_SHIFT;
 321         const unsigned int righthalf = min_t(unsigned int, rq->outputsize,
 322                                              PAGE_SIZE - rq->pageofs_out);
 323         const unsigned int lefthalf = rq->outputsize - righthalf;
 324         unsigned char *src, *dst;
 325
 326         if (nrpages_out > 2) {
 327                 DBG_BUGON(1);
 328                 return -EIO;
 329         }
 330
 331         if (rq->out[0] == *rq->in) {
 332                 DBG_BUGON(nrpages_out != 1);
 333                 return 0;
 334         }
 335
 336         src = kmap_atomic(*rq->in) + rq->pageofs_in;
 337         if (rq->out[0]) {
 338                 dst = kmap_atomic(rq->out[0]);
 339                 memcpy(dst + rq->pageofs_out, src, righthalf);
 340                 kunmap_atomic(dst);
 341         }
 342
 343         if (nrpages_out == 2) {
 344                 DBG_BUGON(!rq->out[1]);
 345                 if (rq->out[1] == *rq->in) {
 346                         memmove(src, src + righthalf, lefthalf);
 347                 } else {
 348                         dst = kmap_atomic(rq->out[1]);
 349                         memcpy(dst, src + righthalf, lefthalf);
 350                         kunmap_atomic(dst);
 351                 }
 352         }
 353         kunmap_atomic(src);
 354         return 0;
 355 }
 356
 357 static struct z_erofs_decompressor decompressors[] = {
 358         [Z_EROFS_COMPRESSION_SHIFTED] = {
 359                 .decompress = z_erofs_shifted_transform,
 360                 .name = "shifted"
 361         },
 362         [Z_EROFS_COMPRESSION_LZ4] = {
 363                 .decompress = z_erofs_lz4_decompress,
 364                 .name = "lz4"
 365         },
 366 #ifdef CONFIG_EROFS_FS_ZIP_LZMA
 367         [Z_EROFS_COMPRESSION_LZMA] = {
 368                 .decompress = z_erofs_lzma_decompress,
 369                 .name = "lzma"
 370         },
 371 #endif
 372 };
 373
 374 int z_erofs_decompress(struct z_erofs_decompress_req *rq,
 375                        struct page **pagepool)
 376 {
 377         return decompressors[rq->alg].decompress(rq, pagepool);
 378 }