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_shifted_transform(struct z_erofs_decompress_req *rq, 321 struct page **pagepool) 322 { 323 const unsigned int nrpages_out = 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 unsigned char *src, *dst; 329 330 if (nrpages_out > 2) { 331 DBG_BUGON(1); 332 return -EIO; 333 } 334 335 if (rq->out[0] == *rq->in) { 336 DBG_BUGON(nrpages_out != 1); 337 return 0; 338 } 339 340 src = kmap_atomic(*rq->in) + rq->pageofs_in; 341 if (rq->out[0]) { 342 dst = kmap_atomic(rq->out[0]); 343 memcpy(dst + rq->pageofs_out, src, righthalf); 344 kunmap_atomic(dst); 345 } 346 347 if (nrpages_out == 2) { 348 DBG_BUGON(!rq->out[1]); 349 if (rq->out[1] == *rq->in) { 350 memmove(src, src + righthalf, lefthalf); 351 } else { 352 dst = kmap_atomic(rq->out[1]); 353 memcpy(dst, src + righthalf, lefthalf); 354 kunmap_atomic(dst); 355 } 356 } 357 kunmap_atomic(src); 358 return 0; 359 } 360 361 static struct z_erofs_decompressor decompressors[] = { 362 [Z_EROFS_COMPRESSION_SHIFTED] = { 363 .decompress = z_erofs_shifted_transform, 364 .name = "shifted" 365 }, 366 [Z_EROFS_COMPRESSION_LZ4] = { 367 .decompress = z_erofs_lz4_decompress, 368 .name = "lz4" 369 }, 370 #ifdef CONFIG_EROFS_FS_ZIP_LZMA 371 [Z_EROFS_COMPRESSION_LZMA] = { 372 .decompress = z_erofs_lzma_decompress, 373 .name = "lzma" 374 }, 375 #endif 376 }; 377 378 int z_erofs_decompress(struct z_erofs_decompress_req *rq, 379 struct page **pagepool) 380 { 381 return decompressors[rq->alg].decompress(rq, pagepool); 382 } 383