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