fdt_region.c 19 KB

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