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