common/fdt_region.c

   1 // SPDX-License-Identifier: GPL-2.0+ OR BSD-2-Clause
   2 /*
   3  * libfdt - Flat Device Tree manipulation
   4  * Copyright (C) 2013 Google, Inc
   5  * Written by Simon Glass <sjg@chromium.org>
   6  */
   7
   8 #include <fdt_support.h>
   9 #include <linux/libfdt_env.h>
  10 #include <fdt_region.h>
  11
  12 #ifndef USE_HOSTCC
  13 #include <fdt.h>
  14 #include <linux/libfdt.h>
  15 #else
  16 #include "fdt_host.h"
  17 #endif
  18
  19 #define FDT_MAX_DEPTH   32
  20
  21 static int str_in_list(const char *str, char * const list[], int count)
  22 {
  23         int i;
  24
  25         for (i = 0; i < count; i++)
  26                 if (!strcmp(list[i], str))
  27                         return 1;
  28
  29         return 0;
  30 }
  31
  32 int fdt_find_regions(const void *fdt, char * const inc[], int inc_count,
  33                      char * const exc_prop[], int exc_prop_count,
  34                      struct fdt_region region[], int max_regions,
  35                      char *path, int path_len, int add_string_tab)
  36 {
  37         int stack[FDT_MAX_DEPTH] = { 0 };
  38         char *end;
  39         int nextoffset = 0;
  40         uint32_t tag;
  41         int count = 0;
  42         int start = -1;
  43         int depth = -1;
  44         int want = 0;
  45         int base = fdt_off_dt_struct(fdt);
  46
  47         end = path;
  48         *end = '\0';
  49         do {
  50                 const struct fdt_property *prop;
  51                 const char *name;
  52                 const char *str;
  53                 int include = 0;
  54                 int stop_at = 0;
  55                 int offset;
  56                 int len;
  57
  58                 offset = nextoffset;
  59                 tag = fdt_next_tag(fdt, offset, &nextoffset);
  60                 stop_at = nextoffset;
  61
  62                 switch (tag) {
  63                 case FDT_PROP:
  64                         include = want >= 2;
  65                         stop_at = offset;
  66                         prop = fdt_get_property_by_offset(fdt, offset, NULL);
  67                         str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
  68                         if (str_in_list(str, exc_prop, exc_prop_count))
  69                                 include = 0;
  70                         break;
  71
  72                 case FDT_NOP:
  73                         include = want >= 2;
  74                         stop_at = offset;
  75                         break;
  76
  77                 case FDT_BEGIN_NODE:
  78                         depth++;
  79                         if (depth == FDT_MAX_DEPTH)
  80                                 return -FDT_ERR_BADSTRUCTURE;
  81                         name = fdt_get_name(fdt, offset, &len);
  82                         if (end - path + 2 + len >= path_len)
  83                                 return -FDT_ERR_NOSPACE;
  84                         if (end != path + 1)
  85                                 *end++ = '/';
  86                         strcpy(end, name);
  87                         end += len;
  88                         stack[depth] = want;
  89                         if (want == 1)
  90                                 stop_at = offset;
  91                         if (str_in_list(path, inc, inc_count))
  92                                 want = 2;
  93                         else if (want)
  94                                 want--;
  95                         else
  96                                 stop_at = offset;
  97                         include = want;
  98                         break;
  99
 100                 case FDT_END_NODE:
 101                         /* Depth must never go below -1 */
 102                         if (depth < 0)
 103                                 return -FDT_ERR_BADSTRUCTURE;
 104                         include = want;
 105                         want = stack[depth--];
 106                         while (end > path && *--end != '/')
 107                                 ;
 108                         *end = '\0';
 109                         break;
 110
 111                 case FDT_END:
 112                         include = 1;
 113                         break;
 114                 }
 115
 116                 if (include && start == -1) {
 117                         /* Should we merge with previous? */
 118                         if (count && count <= max_regions &&
 119                             offset == region[count - 1].offset +
 120                                         region[count - 1].size - base)
 121                                 start = region[--count].offset - base;
 122                         else
 123                                 start = offset;
 124                 }
 125
 126                 if (!include && start != -1) {
 127                         if (count < max_regions) {
 128                                 region[count].offset = base + start;
 129                                 region[count].size = stop_at - start;
 130                         }
 131                         count++;
 132                         start = -1;
 133                 }
 134         } while (tag != FDT_END);
 135
 136         if (nextoffset != fdt_size_dt_struct(fdt))
 137                 return -FDT_ERR_BADLAYOUT;
 138
 139         /* Add a region for the END tag and the string table */
 140         if (count < max_regions) {
 141                 region[count].offset = base + start;
 142                 region[count].size = nextoffset - start;
 143                 if (add_string_tab)
 144                         region[count].size += fdt_size_dt_strings(fdt);
 145         }
 146         count++;
 147
 148         return count;
 149 }
 150
 151 /**
 152  * fdt_add_region() - Add a new region to our list
 153  * @info:       State information
 154  * @offset:     Start offset of region
 155  * @size:       Size of region
 156  *
 157  * The region is added if there is space, but in any case we increment the
 158  * count. If permitted, and the new region overlaps the last one, we merge
 159  * them.
 160  */
 161 static int fdt_add_region(struct fdt_region_state *info, int offset, int size)
 162 {
 163         struct fdt_region *reg;
 164
 165         reg = info->region ? &info->region[info->count - 1] : NULL;
 166         if (info->can_merge && info->count &&
 167             info->count <= info->max_regions &&
 168             reg && offset <= reg->offset + reg->size) {
 169                 reg->size = offset + size - reg->offset;
 170         } else if (info->count++ < info->max_regions) {
 171                 if (reg) {
 172                         reg++;
 173                         reg->offset = offset;
 174                         reg->size = size;
 175                 }
 176         } else {
 177                 return -1;
 178         }
 179
 180         return 0;
 181 }
 182
 183 static int region_list_contains_offset(struct fdt_region_state *info,
 184                                        const void *fdt, int target)
 185 {
 186         struct fdt_region *reg;
 187         int num;
 188
 189         target += fdt_off_dt_struct(fdt);
 190         for (reg = info->region, num = 0; num < info->count; reg++, num++) {
 191                 if (target >= reg->offset && target < reg->offset + reg->size)
 192                         return 1;
 193         }
 194
 195         return 0;
 196 }
 197
 198 /**
 199  * fdt_add_alias_regions() - Add regions covering the aliases that we want
 200  *
 201  * The /aliases node is not automatically included by fdtgrep unless the
 202  * command-line arguments cause to be included (or not excluded). However
 203  * aliases are special in that we generally want to include those which
 204  * reference a node that fdtgrep includes.
 205  *
 206  * In fact we want to include only aliases for those nodes still included in
 207  * the fdt, and drop the other aliases since they point to nodes that will not
 208  * be present.
 209  *
 210  * This function scans the aliases and adds regions for those which we want
 211  * to keep.
 212  *
 213  * @fdt: Device tree to scan
 214  * @region: List of regions
 215  * @count: Number of regions in the list so far (i.e. starting point for this
 216  *      function)
 217  * @max_regions: Maximum number of regions in @region list
 218  * @info: Place to put the region state
 219  * @return number of regions after processing, or -FDT_ERR_NOSPACE if we did
 220  * not have enough room in the regions table for the regions we wanted to add.
 221  */
 222 int fdt_add_alias_regions(const void *fdt, struct fdt_region *region, int count,
 223                           int max_regions, struct fdt_region_state *info)
 224 {
 225         int base = fdt_off_dt_struct(fdt);
 226         int node, node_end, offset;
 227         int did_alias_header;
 228
 229         node = fdt_subnode_offset(fdt, 0, "aliases");
 230         if (node < 0)
 231                 return -FDT_ERR_NOTFOUND;
 232
 233         /*
 234          * Find the next node so that we know where the /aliases node ends. We
 235          * need special handling if /aliases is the last node.
 236          */
 237         node_end = fdt_next_subnode(fdt, node);
 238         if (node_end == -FDT_ERR_NOTFOUND)
 239                 /* Move back to the FDT_END_NODE tag of '/' */
 240                 node_end = fdt_size_dt_struct(fdt) - sizeof(fdt32_t) * 2;
 241         else if (node_end < 0) /* other error */
 242                 return node_end;
 243         node_end -= sizeof(fdt32_t);  /* Move to FDT_END_NODE tag of /aliases */
 244
 245         did_alias_header = 0;
 246         info->region = region;
 247         info->count = count;
 248         info->can_merge = 0;
 249         info->max_regions = max_regions;
 250
 251         for (offset = fdt_first_property_offset(fdt, node);
 252              offset >= 0;
 253              offset = fdt_next_property_offset(fdt, offset)) {
 254                 const struct fdt_property *prop;
 255                 const char *name;
 256                 int target, next;
 257
 258                 prop = fdt_get_property_by_offset(fdt, offset, NULL);
 259                 name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
 260                 target = fdt_path_offset(fdt, name);
 261                 if (!region_list_contains_offset(info, fdt, target))
 262                         continue;
 263                 next = fdt_next_property_offset(fdt, offset);
 264                 if (next < 0)
 265                         next = node_end;
 266
 267                 if (!did_alias_header) {
 268                         fdt_add_region(info, base + node, 12);
 269                         did_alias_header = 1;
 270                 }
 271                 fdt_add_region(info, base + offset, next - offset);
 272         }
 273
 274         /* Add the FDT_END_NODE tag */
 275         if (did_alias_header)
 276                 fdt_add_region(info, base + node_end, sizeof(fdt32_t));
 277
 278         return info->count < max_regions ? info->count : -FDT_ERR_NOSPACE;
 279 }
 280
 281 /**
 282  * fdt_include_supernodes() - Include supernodes required by this node
 283  * @info:       State information
 284  * @depth:      Current stack depth
 285  *
 286  * When we decided to include a node or property which is not at the top
 287  * level, this function forces the inclusion of higher level nodes. For
 288  * example, given this tree:
 289  *
 290  * / {
 291  *     testing {
 292  *     }
 293  * }
 294  *
 295  * If we decide to include testing then we need the root node to have a valid
 296  * tree. This function adds those regions.
 297  */
 298 static int fdt_include_supernodes(struct fdt_region_state *info, int depth)
 299 {
 300         int base = fdt_off_dt_struct(info->fdt);
 301         int start, stop_at;
 302         int i;
 303
 304         /*
 305          * Work down the stack looking for supernodes that we didn't include.
 306          * The algortihm here is actually pretty simple, since we know that
 307          * no previous subnode had to include these nodes, or if it did, we
 308          * marked them as included (on the stack) already.
 309          */
 310         for (i = 0; i <= depth; i++) {
 311                 if (!info->stack[i].included) {
 312                         start = info->stack[i].offset;
 313
 314                         /* Add the FDT_BEGIN_NODE tag of this supernode */
 315                         fdt_next_tag(info->fdt, start, &stop_at);
 316                         if (fdt_add_region(info, base + start, stop_at - start))
 317                                 return -1;
 318
 319                         /* Remember that this supernode is now included */
 320                         info->stack[i].included = 1;
 321                         info->can_merge = 1;
 322                 }
 323
 324                 /* Force (later) generation of the FDT_END_NODE tag */
 325                 if (!info->stack[i].want)
 326                         info->stack[i].want = WANT_NODES_ONLY;
 327         }
 328
 329         return 0;
 330 }
 331
 332 enum {
 333         FDT_DONE_NOTHING,
 334         FDT_DONE_MEM_RSVMAP,
 335         FDT_DONE_STRUCT,
 336         FDT_DONE_END,
 337         FDT_DONE_STRINGS,
 338         FDT_DONE_ALL,
 339 };
 340
 341 int fdt_first_region(const void *fdt,
 342                 int (*h_include)(void *priv, const void *fdt, int offset,
 343                                  int type, const char *data, int size),
 344                 void *priv, struct fdt_region *region,
 345                 char *path, int path_len, int flags,
 346                 struct fdt_region_state *info)
 347 {
 348         struct fdt_region_ptrs *p = &info->ptrs;
 349
 350         /* Set up our state */
 351         info->fdt = fdt;
 352         info->can_merge = 1;
 353         info->max_regions = 1;
 354         info->start = -1;
 355         p->want = WANT_NOTHING;
 356         p->end = path;
 357         *p->end = '\0';
 358         p->nextoffset = 0;
 359         p->depth = -1;
 360         p->done = FDT_DONE_NOTHING;
 361
 362         return fdt_next_region(fdt, h_include, priv, region,
 363                                path, path_len, flags, info);
 364 }
 365
 366 /***********************************************************************
 367  *
 368  *      Theory of operation
 369  *
 370  * Note: in this description 'included' means that a node (or other part
 371  * of the tree) should be included in the region list, i.e. it will have
 372  * a region which covers its part of the tree.
 373  *
 374  * This function maintains some state from the last time it is called.
 375  * It checks the next part of the tree that it is supposed to look at
 376  * (p.nextoffset) to see if that should be included or not. When it
 377  * finds something to include, it sets info->start to its offset. This
 378  * marks the start of the region we want to include.
 379  *
 380  * Once info->start is set to the start (i.e. not -1), we continue
 381  * scanning until we find something that we don't want included. This
 382  * will be the end of a region. At this point we can close off the
 383  * region and add it to the list. So we do so, and reset info->start
 384  * to -1.
 385  *
 386  * One complication here is that we want to merge regions. So when we
 387  * come to add another region later, we may in fact merge it with the
 388  * previous one if one ends where the other starts.
 389  *
 390  * The function fdt_add_region() will return -1 if it fails to add the
 391  * region, because we already have a region ready to be returned, and
 392  * the new one cannot be merged in with it. In this case, we must return
 393  * the region we found, and wait for another call to this function.
 394  * When it comes, we will repeat the processing of the tag and again
 395  * try to add a region. This time it will succeed.
 396  *
 397  * The current state of the pointers (stack, offset, etc.) is maintained
 398  * in a ptrs member. At the start of every loop iteration we make a copy
 399  * of it.  The copy is then updated as the tag is processed. Only if we
 400  * get to the end of the loop iteration (and successfully call
 401  * fdt_add_region() if we need to) can we commit the changes we have
 402  * made to these pointers. For example, if we see an FDT_END_NODE tag,
 403  * we will decrement the depth value. But if we need to add a region
 404  * for this tag (let's say because the previous tag is included and this
 405  * FDT_END_NODE tag is not included) then we will only commit the result
 406  * if we were able to add the region. That allows us to retry again next
 407  * time.
 408  *
 409  * We keep track of a variable called 'want' which tells us what we want
 410  * to include when there is no specific information provided by the
 411  * h_include function for a particular property. This basically handles
 412  * the inclusion of properties which are pulled in by virtue of the node
 413  * they are in. So if you include a node, its properties are also
 414  * included.  In this case 'want' will be WANT_NODES_AND_PROPS. The
 415  * FDT_REG_DIRECT_SUBNODES feature also makes use of 'want'. While we
 416  * are inside the subnode, 'want' will be set to WANT_NODES_ONLY, so
 417  * that only the subnode's FDT_BEGIN_NODE and FDT_END_NODE tags will be
 418  * included, and properties will be skipped. If WANT_NOTHING is
 419  * selected, then we will just rely on what the h_include() function
 420  * tells us.
 421  *
 422  * Using 'want' we work out 'include', which tells us whether this
 423  * current tag should be included or not. As you can imagine, if the
 424  * value of 'include' changes, that means we are on a boundary between
 425  * nodes to include and nodes to exclude. At this point we either close
 426  * off a previous region and add it to the list, or mark the start of a
 427  * new region.
 428  *
 429  * Apart from the nodes, we have mem_rsvmap, the FDT_END tag and the
 430  * string list. Each of these dealt with as a whole (i.e. we create a
 431  * region for each if it is to be included). For mem_rsvmap we don't
 432  * allow it to merge with the first struct region. For the stringlist,
 433  * we don't allow it to merge with the last struct region (which
 434  * contains at minimum the FDT_END tag).
 435  *
 436  *********************************************************************/
 437
 438 int fdt_next_region(const void *fdt,
 439                 int (*h_include)(void *priv, const void *fdt, int offset,
 440                                  int type, const char *data, int size),
 441                 void *priv, struct fdt_region *region,
 442                 char *path, int path_len, int flags,
 443                 struct fdt_region_state *info)
 444 {
 445         int base = fdt_off_dt_struct(fdt);
 446         int last_node = 0;
 447         const char *str;
 448
 449         info->region = region;
 450         info->count = 0;
 451         if (info->ptrs.done < FDT_DONE_MEM_RSVMAP &&
 452             (flags & FDT_REG_ADD_MEM_RSVMAP)) {
 453                 /* Add the memory reserve map into its own region */
 454                 if (fdt_add_region(info, fdt_off_mem_rsvmap(fdt),
 455                                    fdt_off_dt_struct(fdt) -
 456                                    fdt_off_mem_rsvmap(fdt)))
 457                         return 0;
 458                 info->can_merge = 0;    /* Don't allow merging with this */
 459                 info->ptrs.done = FDT_DONE_MEM_RSVMAP;
 460         }
 461
 462         /*
 463          * Work through the tags one by one, deciding whether each needs to
 464          * be included or not. We set the variable 'include' to indicate our
 465          * decision. 'want' is used to track what we want to include - it
 466          * allows us to pick up all the properties (and/or subnode tags) of
 467          * a node.
 468          */
 469         while (info->ptrs.done < FDT_DONE_STRUCT) {
 470                 const struct fdt_property *prop;
 471                 struct fdt_region_ptrs p;
 472                 const char *name;
 473                 int include = 0;
 474                 int stop_at = 0;
 475                 uint32_t tag;
 476                 int offset;
 477                 int val;
 478                 int len;
 479
 480                 /*
 481                  * Make a copy of our pointers. If we make it to the end of
 482                  * this block then we will commit them back to info->ptrs.
 483                  * Otherwise we can try again from the same starting state
 484                  * next time we are called.
 485                  */
 486                 p = info->ptrs;
 487
 488                 /*
 489                  * Find the tag, and the offset of the next one. If we need to
 490                  * stop including tags, then by default we stop *after*
 491                  * including the current tag
 492                  */
 493                 offset = p.nextoffset;
 494                 tag = fdt_next_tag(fdt, offset, &p.nextoffset);
 495                 stop_at = p.nextoffset;
 496
 497                 switch (tag) {
 498                 case FDT_PROP:
 499                         stop_at = offset;
 500                         prop = fdt_get_property_by_offset(fdt, offset, NULL);
 501                         str = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
 502                         val = h_include(priv, fdt, last_node, FDT_IS_PROP, str,
 503                                             strlen(str) + 1);
 504                         if (val == -1) {
 505                                 include = p.want >= WANT_NODES_AND_PROPS;
 506                         } else {
 507                                 include = val;
 508                                 /*
 509                                  * Make sure we include the } for this block.
 510                                  * It might be more correct to have this done
 511                                  * by the call to fdt_include_supernodes() in
 512                                  * the case where it adds the node we are
 513                                  * currently in, but this is equivalent.
 514                                  */
 515                                 if ((flags & FDT_REG_SUPERNODES) && val &&
 516                                     !p.want)
 517                                         p.want = WANT_NODES_ONLY;
 518                         }
 519
 520                         /* Value grepping is not yet supported */
 521                         break;
 522
 523                 case FDT_NOP:
 524                         include = p.want >= WANT_NODES_AND_PROPS;
 525                         stop_at = offset;
 526                         break;
 527
 528                 case FDT_BEGIN_NODE:
 529                         last_node = offset;
 530                         p.depth++;
 531                         if (p.depth == FDT_MAX_DEPTH)
 532                                 return -FDT_ERR_BADSTRUCTURE;
 533                         name = fdt_get_name(fdt, offset, &len);
 534                         if (p.end - path + 2 + len >= path_len)
 535                                 return -FDT_ERR_NOSPACE;
 536
 537                         /* Build the full path of this node */
 538                         if (p.end != path + 1)
 539                                 *p.end++ = '/';
 540                         strcpy(p.end, name);
 541                         p.end += len;
 542                         info->stack[p.depth].want = p.want;
 543                         info->stack[p.depth].offset = offset;
 544
 545                         /*
 546                          * If we are not intending to include this node unless
 547                          * it matches, make sure we stop *before* its tag.
 548                          */
 549                         if (p.want == WANT_NODES_ONLY ||
 550                             !(flags & (FDT_REG_DIRECT_SUBNODES |
 551                                        FDT_REG_ALL_SUBNODES))) {
 552                                 stop_at = offset;
 553                                 p.want = WANT_NOTHING;
 554                         }
 555                         val = h_include(priv, fdt, offset, FDT_IS_NODE, path,
 556                                         p.end - path + 1);
 557
 558                         /* Include this if requested */
 559                         if (val) {
 560                                 p.want = (flags & FDT_REG_ALL_SUBNODES) ?
 561                                         WANT_ALL_NODES_AND_PROPS :
 562                                         WANT_NODES_AND_PROPS;
 563                         }
 564
 565                         /* If not requested, decay our 'p.want' value */
 566                         else if (p.want) {
 567                                 if (p.want != WANT_ALL_NODES_AND_PROPS)
 568                                         p.want--;
 569
 570                         /* Not including this tag, so stop now */
 571                         } else {
 572                                 stop_at = offset;
 573                         }
 574
 575                         /*
 576                          * Decide whether to include this tag, and update our
 577                          * stack with the state for this node
 578                          */
 579                         include = p.want;
 580                         info->stack[p.depth].included = include;
 581                         break;
 582
 583                 case FDT_END_NODE:
 584                         include = p.want;
 585                         if (p.depth < 0)
 586                                 return -FDT_ERR_BADSTRUCTURE;
 587
 588                         /*
 589                          * If we don't want this node, stop right away, unless
 590                          * we are including subnodes
 591                          */
 592                         if (!p.want && !(flags & FDT_REG_DIRECT_SUBNODES))
 593                                 stop_at = offset;
 594                         p.want = info->stack[p.depth].want;
 595                         p.depth--;
 596                         while (p.end > path && *--p.end != '/')
 597                                 ;
 598                         *p.end = '\0';
 599                         break;
 600
 601                 case FDT_END:
 602                         /* We always include the end tag */
 603                         include = 1;
 604                         p.done = FDT_DONE_STRUCT;
 605                         break;
 606                 }
 607
 608                 /* If this tag is to be included, mark it as region start */
 609                 if (include && info->start == -1) {
 610                         /* Include any supernodes required by this one */
 611                         if (flags & FDT_REG_SUPERNODES) {
 612                                 if (fdt_include_supernodes(info, p.depth))
 613                                         return 0;
 614                         }
 615                         info->start = offset;
 616                 }
 617
 618                 /*
 619                  * If this tag is not to be included, finish up the current
 620                  * region.
 621                  */
 622                 if (!include && info->start != -1) {
 623                         if (fdt_add_region(info, base + info->start,
 624                                            stop_at - info->start))
 625                                 return 0;
 626                         info->start = -1;
 627                         info->can_merge = 1;
 628                 }
 629
 630                 /* If we have made it this far, we can commit our pointers */
 631                 info->ptrs = p;
 632         }
 633
 634         /* Add a region for the END tag and a separate one for string table */
 635         if (info->ptrs.done < FDT_DONE_END) {
 636                 if (info->ptrs.nextoffset != fdt_size_dt_struct(fdt))
 637                         return -FDT_ERR_BADSTRUCTURE;
 638
 639                 if (fdt_add_region(info, base + info->start,
 640                                    info->ptrs.nextoffset - info->start))
 641                         return 0;
 642                 info->ptrs.done++;
 643         }
 644         if (info->ptrs.done < FDT_DONE_STRINGS) {
 645                 if (flags & FDT_REG_ADD_STRING_TAB) {
 646                         info->can_merge = 0;
 647                         if (fdt_off_dt_strings(fdt) <
 648                             base + info->ptrs.nextoffset)
 649                                 return -FDT_ERR_BADLAYOUT;
 650                         if (fdt_add_region(info, fdt_off_dt_strings(fdt),
 651                                            fdt_size_dt_strings(fdt)))
 652                                 return 0;
 653                 }
 654                 info->ptrs.done++;
 655         }
 656
 657         return info->count > 0 ? 0 : -FDT_ERR_NOTFOUND;
 658 }