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1// SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
2/*
3 * libfdt - Flat Device Tree manipulation
4 * Copyright (C) 2016 Free Electrons
5 * Copyright (C) 2016 NextThing Co.
6 */
7#include "libfdt_env.h"
8
9#include <fdt.h>
10#include <libfdt.h>
11
12#include "libfdt_internal.h"
13
14/**
15 * overlay_get_target_phandle - retrieves the target phandle of a fragment
16 * @fdto: pointer to the device tree overlay blob
17 * @fragment: node offset of the fragment in the overlay
18 *
19 * overlay_get_target_phandle() retrieves the target phandle of an
20 * overlay fragment when that fragment uses a phandle (target
21 * property) instead of a path (target-path property).
22 *
23 * returns:
24 * the phandle pointed by the target property
25 * 0, if the phandle was not found
26 * -1, if the phandle was malformed
27 */
28static uint32_t overlay_get_target_phandle(const void *fdto, int fragment)
29{
30 const fdt32_t *val;
31 int len;
32
33 val = fdt_getprop(fdto, fragment, "target", &len);
34 if (!val)
35 return 0;
36
37 if ((len != sizeof(*val)) || (fdt32_to_cpu(*val) == (uint32_t)-1))
38 return (uint32_t)-1;
39
40 return fdt32_to_cpu(*val);
41}
42
43/**
44 * overlay_get_target - retrieves the offset of a fragment's target
45 * @fdt: Base device tree blob
46 * @fdto: Device tree overlay blob
47 * @fragment: node offset of the fragment in the overlay
48 * @pathp: pointer which receives the path of the target (or NULL)
49 *
50 * overlay_get_target() retrieves the target offset in the base
51 * device tree of a fragment, no matter how the actual targeting is
52 * done (through a phandle or a path)
53 *
54 * returns:
55 * the targeted node offset in the base device tree
56 * Negative error code on error
57 */
58static int overlay_get_target(const void *fdt, const void *fdto,
59 int fragment, char const **pathp)
60{
61 uint32_t phandle;
62 const char *path = NULL;
63 int path_len = 0, ret;
64
65 /* Try first to do a phandle based lookup */
66 phandle = overlay_get_target_phandle(fdto, fragment);
67 if (phandle == (uint32_t)-1)
68 return -FDT_ERR_BADPHANDLE;
69
70 /* no phandle, try path */
71 if (!phandle) {
72 /* And then a path based lookup */
73 path = fdt_getprop(fdto, fragment, "target-path", &path_len);
74 if (path)
75 ret = fdt_path_offset(fdt, path);
76 else
77 ret = path_len;
78 } else
79 ret = fdt_node_offset_by_phandle(fdt, phandle);
80
81 /*
82 * If we haven't found either a target or a
83 * target-path property in a node that contains a
84 * __overlay__ subnode (we wouldn't be called
85 * otherwise), consider it a improperly written
86 * overlay
87 */
88 if (ret < 0 && path_len == -FDT_ERR_NOTFOUND)
89 ret = -FDT_ERR_BADOVERLAY;
90
91 /* return on error */
92 if (ret < 0)
93 return ret;
94
95 /* return pointer to path (if available) */
96 if (pathp)
97 *pathp = path ? path : NULL;
98
99 return ret;
100}
101
102/**
103 * overlay_phandle_add_offset - Increases a phandle by an offset
104 * @fdt: Base device tree blob
105 * @node: Device tree overlay blob
106 * @name: Name of the property to modify (phandle or linux,phandle)
107 * @delta: offset to apply
108 *
109 * overlay_phandle_add_offset() increments a node phandle by a given
110 * offset.
111 *
112 * returns:
113 * 0 on success.
114 * Negative error code on error
115 */
116static int overlay_phandle_add_offset(void *fdt, int node,
117 const char *name, uint32_t delta)
118{
119 const fdt32_t *val;
120 uint32_t adj_val;
121 int len;
122
123 val = fdt_getprop(fdt, node, name, &len);
124 if (!val)
125 return len;
126
127 if (len != sizeof(*val))
128 return -FDT_ERR_BADPHANDLE;
129
130 adj_val = fdt32_to_cpu(*val);
131 if ((adj_val + delta) < adj_val)
132 return -FDT_ERR_NOPHANDLES;
133
134 adj_val += delta;
135 if (adj_val == (uint32_t)-1)
136 return -FDT_ERR_NOPHANDLES;
137
138 return fdt_setprop_inplace_u32(fdt, node, name, adj_val);
139}
140
141/**
142 * overlay_adjust_node_phandles - Offsets the phandles of a node
143 * @fdto: Device tree overlay blob
144 * @node: Offset of the node we want to adjust
145 * @delta: Offset to shift the phandles of
146 *
147 * overlay_adjust_node_phandles() adds a constant to all the phandles
148 * of a given node. This is mainly use as part of the overlay
149 * application process, when we want to update all the overlay
150 * phandles to not conflict with the overlays of the base device tree.
151 *
152 * returns:
153 * 0 on success
154 * Negative error code on failure
155 */
156static int overlay_adjust_node_phandles(void *fdto, int node,
157 uint32_t delta)
158{
159 int child;
160 int ret;
161
162 ret = overlay_phandle_add_offset(fdto, node, "phandle", delta);
163 if (ret && ret != -FDT_ERR_NOTFOUND)
164 return ret;
165
166 ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta);
167 if (ret && ret != -FDT_ERR_NOTFOUND)
168 return ret;
169
170 fdt_for_each_subnode(child, fdto, node) {
171 ret = overlay_adjust_node_phandles(fdto, child, delta);
172 if (ret)
173 return ret;
174 }
175
176 return 0;
177}
178
179/**
180 * overlay_adjust_local_phandles - Adjust the phandles of a whole overlay
181 * @fdto: Device tree overlay blob
182 * @delta: Offset to shift the phandles of
183 *
184 * overlay_adjust_local_phandles() adds a constant to all the
185 * phandles of an overlay. This is mainly use as part of the overlay
186 * application process, when we want to update all the overlay
187 * phandles to not conflict with the overlays of the base device tree.
188 *
189 * returns:
190 * 0 on success
191 * Negative error code on failure
192 */
193static int overlay_adjust_local_phandles(void *fdto, uint32_t delta)
194{
195 /*
196 * Start adjusting the phandles from the overlay root
197 */
198 return overlay_adjust_node_phandles(fdto, 0, delta);
199}
200
201/**
202 * overlay_update_local_node_references - Adjust the overlay references
203 * @fdto: Device tree overlay blob
204 * @tree_node: Node offset of the node to operate on
205 * @fixup_node: Node offset of the matching local fixups node
206 * @delta: Offset to shift the phandles of
207 *
208 * overlay_update_local_nodes_references() update the phandles
209 * pointing to a node within the device tree overlay by adding a
210 * constant delta.
211 *
212 * This is mainly used as part of a device tree application process,
213 * where you want the device tree overlays phandles to not conflict
214 * with the ones from the base device tree before merging them.
215 *
216 * returns:
217 * 0 on success
218 * Negative error code on failure
219 */
220static int overlay_update_local_node_references(void *fdto,
221 int tree_node,
222 int fixup_node,
223 uint32_t delta)
224{
225 int fixup_prop;
226 int fixup_child;
227 int ret;
228
229 fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
230 const fdt32_t *fixup_val;
231 const char *tree_val;
232 const char *name;
233 int fixup_len;
234 int tree_len;
235 int i;
236
237 fixup_val = fdt_getprop_by_offset(fdto, fixup_prop,
238 &name, &fixup_len);
239 if (!fixup_val)
240 return fixup_len;
241
242 if (fixup_len % sizeof(uint32_t))
243 return -FDT_ERR_BADOVERLAY;
244
245 tree_val = fdt_getprop(fdto, tree_node, name, &tree_len);
246 if (!tree_val) {
247 if (tree_len == -FDT_ERR_NOTFOUND)
248 return -FDT_ERR_BADOVERLAY;
249
250 return tree_len;
251 }
252
253 for (i = 0; i < (fixup_len / sizeof(uint32_t)); i++) {
254 fdt32_t adj_val;
255 uint32_t poffset;
256
257 poffset = fdt32_to_cpu(fixup_val[i]);
258
259 /*
260 * phandles to fixup can be unaligned.
261 *
262 * Use a memcpy for the architectures that do
263 * not support unaligned accesses.
264 */
265 memcpy(&adj_val, tree_val + poffset, sizeof(adj_val));
266
267 adj_val = cpu_to_fdt32(fdt32_to_cpu(adj_val) + delta);
268
269 ret = fdt_setprop_inplace_namelen_partial(fdto,
270 tree_node,
271 name,
272 strlen(name),
273 poffset,
274 &adj_val,
275 sizeof(adj_val));
276 if (ret == -FDT_ERR_NOSPACE)
277 return -FDT_ERR_BADOVERLAY;
278
279 if (ret)
280 return ret;
281 }
282 }
283
284 fdt_for_each_subnode(fixup_child, fdto, fixup_node) {
285 const char *fixup_child_name = fdt_get_name(fdto, fixup_child,
286 NULL);
287 int tree_child;
288
289 tree_child = fdt_subnode_offset(fdto, tree_node,
290 fixup_child_name);
291 if (tree_child == -FDT_ERR_NOTFOUND)
292 return -FDT_ERR_BADOVERLAY;
293 if (tree_child < 0)
294 return tree_child;
295
296 ret = overlay_update_local_node_references(fdto,
297 tree_child,
298 fixup_child,
299 delta);
300 if (ret)
301 return ret;
302 }
303
304 return 0;
305}
306
307/**
308 * overlay_update_local_references - Adjust the overlay references
309 * @fdto: Device tree overlay blob
310 * @delta: Offset to shift the phandles of
311 *
312 * overlay_update_local_references() update all the phandles pointing
313 * to a node within the device tree overlay by adding a constant
314 * delta to not conflict with the base overlay.
315 *
316 * This is mainly used as part of a device tree application process,
317 * where you want the device tree overlays phandles to not conflict
318 * with the ones from the base device tree before merging them.
319 *
320 * returns:
321 * 0 on success
322 * Negative error code on failure
323 */
324static int overlay_update_local_references(void *fdto, uint32_t delta)
325{
326 int fixups;
327
328 fixups = fdt_path_offset(fdto, "/__local_fixups__");
329 if (fixups < 0) {
330 /* There's no local phandles to adjust, bail out */
331 if (fixups == -FDT_ERR_NOTFOUND)
332 return 0;
333
334 return fixups;
335 }
336
337 /*
338 * Update our local references from the root of the tree
339 */
340 return overlay_update_local_node_references(fdto, 0, fixups,
341 delta);
342}
343
344/**
345 * overlay_fixup_one_phandle - Set an overlay phandle to the base one
346 * @fdt: Base Device Tree blob
347 * @fdto: Device tree overlay blob
348 * @symbols_off: Node offset of the symbols node in the base device tree
349 * @path: Path to a node holding a phandle in the overlay
350 * @path_len: number of path characters to consider
351 * @name: Name of the property holding the phandle reference in the overlay
352 * @name_len: number of name characters to consider
353 * @poffset: Offset within the overlay property where the phandle is stored
354 * @label: Label of the node referenced by the phandle
355 *
356 * overlay_fixup_one_phandle() resolves an overlay phandle pointing to
357 * a node in the base device tree.
358 *
359 * This is part of the device tree overlay application process, when
360 * you want all the phandles in the overlay to point to the actual
361 * base dt nodes.
362 *
363 * returns:
364 * 0 on success
365 * Negative error code on failure
366 */
367static int overlay_fixup_one_phandle(void *fdt, void *fdto,
368 int symbols_off,
369 const char *path, uint32_t path_len,
370 const char *name, uint32_t name_len,
371 int poffset, const char *label)
372{
373 const char *symbol_path;
374 uint32_t phandle;
375 fdt32_t phandle_prop;
376 int symbol_off, fixup_off;
377 int prop_len;
378
379 if (symbols_off < 0)
380 return symbols_off;
381
382 symbol_path = fdt_getprop(fdt, symbols_off, label,
383 &prop_len);
384 if (!symbol_path)
385 return prop_len;
386
387 symbol_off = fdt_path_offset(fdt, symbol_path);
388 if (symbol_off < 0)
389 return symbol_off;
390
391 phandle = fdt_get_phandle(fdt, symbol_off);
392 if (!phandle)
393 return -FDT_ERR_NOTFOUND;
394
395 fixup_off = fdt_path_offset_namelen(fdto, path, path_len);
396 if (fixup_off == -FDT_ERR_NOTFOUND)
397 return -FDT_ERR_BADOVERLAY;
398 if (fixup_off < 0)
399 return fixup_off;
400
401 phandle_prop = cpu_to_fdt32(phandle);
402 return fdt_setprop_inplace_namelen_partial(fdto, fixup_off,
403 name, name_len, poffset,
404 &phandle_prop,
405 sizeof(phandle_prop));
406};
407
408/**
409 * overlay_fixup_phandle - Set an overlay phandle to the base one
410 * @fdt: Base Device Tree blob
411 * @fdto: Device tree overlay blob
412 * @symbols_off: Node offset of the symbols node in the base device tree
413 * @property: Property offset in the overlay holding the list of fixups
414 *
415 * overlay_fixup_phandle() resolves all the overlay phandles pointed
416 * to in a __fixups__ property, and updates them to match the phandles
417 * in use in the base device tree.
418 *
419 * This is part of the device tree overlay application process, when
420 * you want all the phandles in the overlay to point to the actual
421 * base dt nodes.
422 *
423 * returns:
424 * 0 on success
425 * Negative error code on failure
426 */
427static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
428 int property)
429{
430 const char *value;
431 const char *label;
432 int len;
433
434 value = fdt_getprop_by_offset(fdto, property,
435 &label, &len);
436 if (!value) {
437 if (len == -FDT_ERR_NOTFOUND)
438 return -FDT_ERR_INTERNAL;
439
440 return len;
441 }
442
443 do {
444 const char *path, *name, *fixup_end;
445 const char *fixup_str = value;
446 uint32_t path_len, name_len;
447 uint32_t fixup_len;
448 char *sep, *endptr;
449 int poffset, ret;
450
451 fixup_end = memchr(value, '\0', len);
452 if (!fixup_end)
453 return -FDT_ERR_BADOVERLAY;
454 fixup_len = fixup_end - fixup_str;
455
456 len -= fixup_len + 1;
457 value += fixup_len + 1;
458
459 path = fixup_str;
460 sep = memchr(fixup_str, ':', fixup_len);
461 if (!sep || *sep != ':')
462 return -FDT_ERR_BADOVERLAY;
463
464 path_len = sep - path;
465 if (path_len == (fixup_len - 1))
466 return -FDT_ERR_BADOVERLAY;
467
468 fixup_len -= path_len + 1;
469 name = sep + 1;
470 sep = memchr(name, ':', fixup_len);
471 if (!sep || *sep != ':')
472 return -FDT_ERR_BADOVERLAY;
473
474 name_len = sep - name;
475 if (!name_len)
476 return -FDT_ERR_BADOVERLAY;
477
478 poffset = strtoul(sep + 1, &endptr, 10);
479 if ((*endptr != '\0') || (endptr <= (sep + 1)))
480 return -FDT_ERR_BADOVERLAY;
481
482 ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
483 path, path_len, name, name_len,
484 poffset, label);
485 if (ret)
486 return ret;
487 } while (len > 0);
488
489 return 0;
490}
491
492/**
493 * overlay_fixup_phandles - Resolve the overlay phandles to the base
494 * device tree
495 * @fdt: Base Device Tree blob
496 * @fdto: Device tree overlay blob
497 *
498 * overlay_fixup_phandles() resolves all the overlay phandles pointing
499 * to nodes in the base device tree.
500 *
501 * This is one of the steps of the device tree overlay application
502 * process, when you want all the phandles in the overlay to point to
503 * the actual base dt nodes.
504 *
505 * returns:
506 * 0 on success
507 * Negative error code on failure
508 */
509static int overlay_fixup_phandles(void *fdt, void *fdto)
510{
511 int fixups_off, symbols_off;
512 int property;
513
514 /* We can have overlays without any fixups */
515 fixups_off = fdt_path_offset(fdto, "/__fixups__");
516 if (fixups_off == -FDT_ERR_NOTFOUND)
517 return 0; /* nothing to do */
518 if (fixups_off < 0)
519 return fixups_off;
520
521 /* And base DTs without symbols */
522 symbols_off = fdt_path_offset(fdt, "/__symbols__");
523 if ((symbols_off < 0 && (symbols_off != -FDT_ERR_NOTFOUND)))
524 return symbols_off;
525
526 fdt_for_each_property_offset(property, fdto, fixups_off) {
527 int ret;
528
529 ret = overlay_fixup_phandle(fdt, fdto, symbols_off, property);
530 if (ret)
531 return ret;
532 }
533
534 return 0;
535}
536
537/**
538 * overlay_apply_node - Merges a node into the base device tree
539 * @fdt: Base Device Tree blob
540 * @target: Node offset in the base device tree to apply the fragment to
541 * @fdto: Device tree overlay blob
542 * @node: Node offset in the overlay holding the changes to merge
543 *
544 * overlay_apply_node() merges a node into a target base device tree
545 * node pointed.
546 *
547 * This is part of the final step in the device tree overlay
548 * application process, when all the phandles have been adjusted and
549 * resolved and you just have to merge overlay into the base device
550 * tree.
551 *
552 * returns:
553 * 0 on success
554 * Negative error code on failure
555 */
556static int overlay_apply_node(void *fdt, int target,
557 void *fdto, int node)
558{
559 int property;
560 int subnode;
561
562 fdt_for_each_property_offset(property, fdto, node) {
563 const char *name;
564 const void *prop;
565 int prop_len;
566 int ret;
567
568 prop = fdt_getprop_by_offset(fdto, property, &name,
569 &prop_len);
570 if (prop_len == -FDT_ERR_NOTFOUND)
571 return -FDT_ERR_INTERNAL;
572 if (prop_len < 0)
573 return prop_len;
574
575 ret = fdt_setprop(fdt, target, name, prop, prop_len);
576 if (ret)
577 return ret;
578 }
579
580 fdt_for_each_subnode(subnode, fdto, node) {
581 const char *name = fdt_get_name(fdto, subnode, NULL);
582 int nnode;
583 int ret;
584
585 nnode = fdt_add_subnode(fdt, target, name);
586 if (nnode == -FDT_ERR_EXISTS) {
587 nnode = fdt_subnode_offset(fdt, target, name);
588 if (nnode == -FDT_ERR_NOTFOUND)
589 return -FDT_ERR_INTERNAL;
590 }
591
592 if (nnode < 0)
593 return nnode;
594
595 ret = overlay_apply_node(fdt, nnode, fdto, subnode);
596 if (ret)
597 return ret;
598 }
599
600 return 0;
601}
602
603/**
604 * overlay_merge - Merge an overlay into its base device tree
605 * @fdt: Base Device Tree blob
606 * @fdto: Device tree overlay blob
607 *
608 * overlay_merge() merges an overlay into its base device tree.
609 *
610 * This is the next to last step in the device tree overlay application
611 * process, when all the phandles have been adjusted and resolved and
612 * you just have to merge overlay into the base device tree.
613 *
614 * returns:
615 * 0 on success
616 * Negative error code on failure
617 */
618static int overlay_merge(void *fdt, void *fdto)
619{
620 int fragment;
621
622 fdt_for_each_subnode(fragment, fdto, 0) {
623 int overlay;
624 int target;
625 int ret;
626
627 /*
628 * Each fragments will have an __overlay__ node. If
629 * they don't, it's not supposed to be merged
630 */
631 overlay = fdt_subnode_offset(fdto, fragment, "__overlay__");
632 if (overlay == -FDT_ERR_NOTFOUND)
633 continue;
634
635 if (overlay < 0)
636 return overlay;
637
638 target = overlay_get_target(fdt, fdto, fragment, NULL);
639 if (target < 0)
640 return target;
641
642 ret = overlay_apply_node(fdt, target, fdto, overlay);
643 if (ret)
644 return ret;
645 }
646
647 return 0;
648}
649
650static int get_path_len(const void *fdt, int nodeoffset)
651{
652 int len = 0, namelen;
653 const char *name;
654
655 FDT_RO_PROBE(fdt);
656
657 for (;;) {
658 name = fdt_get_name(fdt, nodeoffset, &namelen);
659 if (!name)
660 return namelen;
661
662 /* root? we're done */
663 if (namelen == 0)
664 break;
665
666 nodeoffset = fdt_parent_offset(fdt, nodeoffset);
667 if (nodeoffset < 0)
668 return nodeoffset;
669 len += namelen + 1;
670 }
671
672 /* in case of root pretend it's "/" */
673 if (len == 0)
674 len++;
675 return len;
676}
677
678/**
679 * overlay_symbol_update - Update the symbols of base tree after a merge
680 * @fdt: Base Device Tree blob
681 * @fdto: Device tree overlay blob
682 *
683 * overlay_symbol_update() updates the symbols of the base tree with the
684 * symbols of the applied overlay
685 *
686 * This is the last step in the device tree overlay application
687 * process, allowing the reference of overlay symbols by subsequent
688 * overlay operations.
689 *
690 * returns:
691 * 0 on success
692 * Negative error code on failure
693 */
694static int overlay_symbol_update(void *fdt, void *fdto)
695{
696 int root_sym, ov_sym, prop, path_len, fragment, target;
697 int len, frag_name_len, ret, rel_path_len;
698 const char *s, *e;
699 const char *path;
700 const char *name;
701 const char *frag_name;
702 const char *rel_path;
703 const char *target_path;
704 char *buf;
705 void *p;
706
707 ov_sym = fdt_subnode_offset(fdto, 0, "__symbols__");
708
709 /* if no overlay symbols exist no problem */
710 if (ov_sym < 0)
711 return 0;
712
713 root_sym = fdt_subnode_offset(fdt, 0, "__symbols__");
714
715 /* it no root symbols exist we should create them */
716 if (root_sym == -FDT_ERR_NOTFOUND)
717 root_sym = fdt_add_subnode(fdt, 0, "__symbols__");
718
719 /* any error is fatal now */
720 if (root_sym < 0)
721 return root_sym;
722
723 /* iterate over each overlay symbol */
724 fdt_for_each_property_offset(prop, fdto, ov_sym) {
725 path = fdt_getprop_by_offset(fdto, prop, &name, &path_len);
726 if (!path)
727 return path_len;
728
729 /* verify it's a string property (terminated by a single \0) */
730 if (path_len < 1 || memchr(path, '\0', path_len) != &path[path_len - 1])
731 return -FDT_ERR_BADVALUE;
732
733 /* keep end marker to avoid strlen() */
734 e = path + path_len;
735
736 /* format: /<fragment-name>/__overlay__/<relative-subnode-path> */
737
738 if (*path != '/')
739 return -FDT_ERR_BADVALUE;
740
741 /* get fragment name first */
742 s = strchr(path + 1, '/');
743 if (!s)
744 return -FDT_ERR_BADOVERLAY;
745
746 frag_name = path + 1;
747 frag_name_len = s - path - 1;
748
749 /* verify format; safe since "s" lies in \0 terminated prop */
750 len = sizeof("/__overlay__/") - 1;
751 if ((e - s) < len || memcmp(s, "/__overlay__/", len))
752 return -FDT_ERR_BADOVERLAY;
753
754 rel_path = s + len;
755 rel_path_len = e - rel_path;
756
757 /* find the fragment index in which the symbol lies */
758 ret = fdt_subnode_offset_namelen(fdto, 0, frag_name,
759 frag_name_len);
760 /* not found? */
761 if (ret < 0)
762 return -FDT_ERR_BADOVERLAY;
763 fragment = ret;
764
765 /* an __overlay__ subnode must exist */
766 ret = fdt_subnode_offset(fdto, fragment, "__overlay__");
767 if (ret < 0)
768 return -FDT_ERR_BADOVERLAY;
769
770 /* get the target of the fragment */
771 ret = overlay_get_target(fdt, fdto, fragment, &target_path);
772 if (ret < 0)
773 return ret;
774 target = ret;
775
776 /* if we have a target path use */
777 if (!target_path) {
778 ret = get_path_len(fdt, target);
779 if (ret < 0)
780 return ret;
781 len = ret;
782 } else {
783 len = strlen(target_path);
784 }
785
786 ret = fdt_setprop_placeholder(fdt, root_sym, name,
787 len + (len > 1) + rel_path_len + 1, &p);
788 if (ret < 0)
789 return ret;
790
791 if (!target_path) {
792 /* again in case setprop_placeholder changed it */
793 ret = overlay_get_target(fdt, fdto, fragment, &target_path);
794 if (ret < 0)
795 return ret;
796 target = ret;
797 }
798
799 buf = p;
800 if (len > 1) { /* target is not root */
801 if (!target_path) {
802 ret = fdt_get_path(fdt, target, buf, len + 1);
803 if (ret < 0)
804 return ret;
805 } else
806 memcpy(buf, target_path, len + 1);
807
808 } else
809 len--;
810
811 buf[len] = '/';
812 memcpy(buf + len + 1, rel_path, rel_path_len);
813 buf[len + 1 + rel_path_len] = '\0';
814 }
815
816 return 0;
817}
818
819int fdt_overlay_apply(void *fdt, void *fdto)
820{
821 uint32_t delta;
822 int ret;
823
824 FDT_RO_PROBE(fdt);
825 FDT_RO_PROBE(fdto);
826
827 ret = fdt_find_max_phandle(fdt, &delta);
828 if (ret)
829 goto err;
830
831 ret = overlay_adjust_local_phandles(fdto, delta);
832 if (ret)
833 goto err;
834
835 ret = overlay_update_local_references(fdto, delta);
836 if (ret)
837 goto err;
838
839 ret = overlay_fixup_phandles(fdt, fdto);
840 if (ret)
841 goto err;
842
843 ret = overlay_merge(fdt, fdto);
844 if (ret)
845 goto err;
846
847 ret = overlay_symbol_update(fdt, fdto);
848 if (ret)
849 goto err;
850
851 /*
852 * The overlay has been damaged, erase its magic.
853 */
854 fdt_set_magic(fdto, ~0);
855
856 return 0;
857
858err:
859 /*
860 * The overlay might have been damaged, erase its magic.
861 */
862 fdt_set_magic(fdto, ~0);
863
864 /*
865 * The base device tree might have been damaged, erase its
866 * magic.
867 */
868 fdt_set_magic(fdt, ~0);
869
870 return ret;
871}
1// SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
2/*
3 * libfdt - Flat Device Tree manipulation
4 * Copyright (C) 2016 Free Electrons
5 * Copyright (C) 2016 NextThing Co.
6 */
7#include "libfdt_env.h"
8
9#include <fdt.h>
10#include <libfdt.h>
11
12#include "libfdt_internal.h"
13
14/**
15 * overlay_get_target_phandle - retrieves the target phandle of a fragment
16 * @fdto: pointer to the device tree overlay blob
17 * @fragment: node offset of the fragment in the overlay
18 *
19 * overlay_get_target_phandle() retrieves the target phandle of an
20 * overlay fragment when that fragment uses a phandle (target
21 * property) instead of a path (target-path property).
22 *
23 * returns:
24 * the phandle pointed by the target property
25 * 0, if the phandle was not found
26 * -1, if the phandle was malformed
27 */
28static uint32_t overlay_get_target_phandle(const void *fdto, int fragment)
29{
30 const fdt32_t *val;
31 int len;
32
33 val = fdt_getprop(fdto, fragment, "target", &len);
34 if (!val)
35 return 0;
36
37 if ((len != sizeof(*val)) || (fdt32_to_cpu(*val) == (uint32_t)-1))
38 return (uint32_t)-1;
39
40 return fdt32_to_cpu(*val);
41}
42
43/**
44 * overlay_get_target - retrieves the offset of a fragment's target
45 * @fdt: Base device tree blob
46 * @fdto: Device tree overlay blob
47 * @fragment: node offset of the fragment in the overlay
48 * @pathp: pointer which receives the path of the target (or NULL)
49 *
50 * overlay_get_target() retrieves the target offset in the base
51 * device tree of a fragment, no matter how the actual targeting is
52 * done (through a phandle or a path)
53 *
54 * returns:
55 * the targeted node offset in the base device tree
56 * Negative error code on error
57 */
58static int overlay_get_target(const void *fdt, const void *fdto,
59 int fragment, char const **pathp)
60{
61 uint32_t phandle;
62 const char *path = NULL;
63 int path_len = 0, ret;
64
65 /* Try first to do a phandle based lookup */
66 phandle = overlay_get_target_phandle(fdto, fragment);
67 if (phandle == (uint32_t)-1)
68 return -FDT_ERR_BADPHANDLE;
69
70 /* no phandle, try path */
71 if (!phandle) {
72 /* And then a path based lookup */
73 path = fdt_getprop(fdto, fragment, "target-path", &path_len);
74 if (path)
75 ret = fdt_path_offset(fdt, path);
76 else
77 ret = path_len;
78 } else
79 ret = fdt_node_offset_by_phandle(fdt, phandle);
80
81 /*
82 * If we haven't found either a target or a
83 * target-path property in a node that contains a
84 * __overlay__ subnode (we wouldn't be called
85 * otherwise), consider it a improperly written
86 * overlay
87 */
88 if (ret < 0 && path_len == -FDT_ERR_NOTFOUND)
89 ret = -FDT_ERR_BADOVERLAY;
90
91 /* return on error */
92 if (ret < 0)
93 return ret;
94
95 /* return pointer to path (if available) */
96 if (pathp)
97 *pathp = path ? path : NULL;
98
99 return ret;
100}
101
102/**
103 * overlay_phandle_add_offset - Increases a phandle by an offset
104 * @fdt: Base device tree blob
105 * @node: Device tree overlay blob
106 * @name: Name of the property to modify (phandle or linux,phandle)
107 * @delta: offset to apply
108 *
109 * overlay_phandle_add_offset() increments a node phandle by a given
110 * offset.
111 *
112 * returns:
113 * 0 on success.
114 * Negative error code on error
115 */
116static int overlay_phandle_add_offset(void *fdt, int node,
117 const char *name, uint32_t delta)
118{
119 const fdt32_t *val;
120 uint32_t adj_val;
121 int len;
122
123 val = fdt_getprop(fdt, node, name, &len);
124 if (!val)
125 return len;
126
127 if (len != sizeof(*val))
128 return -FDT_ERR_BADPHANDLE;
129
130 adj_val = fdt32_to_cpu(*val);
131 if ((adj_val + delta) < adj_val)
132 return -FDT_ERR_NOPHANDLES;
133
134 adj_val += delta;
135 if (adj_val == (uint32_t)-1)
136 return -FDT_ERR_NOPHANDLES;
137
138 return fdt_setprop_inplace_u32(fdt, node, name, adj_val);
139}
140
141/**
142 * overlay_adjust_node_phandles - Offsets the phandles of a node
143 * @fdto: Device tree overlay blob
144 * @node: Offset of the node we want to adjust
145 * @delta: Offset to shift the phandles of
146 *
147 * overlay_adjust_node_phandles() adds a constant to all the phandles
148 * of a given node. This is mainly use as part of the overlay
149 * application process, when we want to update all the overlay
150 * phandles to not conflict with the overlays of the base device tree.
151 *
152 * returns:
153 * 0 on success
154 * Negative error code on failure
155 */
156static int overlay_adjust_node_phandles(void *fdto, int node,
157 uint32_t delta)
158{
159 int child;
160 int ret;
161
162 ret = overlay_phandle_add_offset(fdto, node, "phandle", delta);
163 if (ret && ret != -FDT_ERR_NOTFOUND)
164 return ret;
165
166 ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta);
167 if (ret && ret != -FDT_ERR_NOTFOUND)
168 return ret;
169
170 fdt_for_each_subnode(child, fdto, node) {
171 ret = overlay_adjust_node_phandles(fdto, child, delta);
172 if (ret)
173 return ret;
174 }
175
176 return 0;
177}
178
179/**
180 * overlay_adjust_local_phandles - Adjust the phandles of a whole overlay
181 * @fdto: Device tree overlay blob
182 * @delta: Offset to shift the phandles of
183 *
184 * overlay_adjust_local_phandles() adds a constant to all the
185 * phandles of an overlay. This is mainly use as part of the overlay
186 * application process, when we want to update all the overlay
187 * phandles to not conflict with the overlays of the base device tree.
188 *
189 * returns:
190 * 0 on success
191 * Negative error code on failure
192 */
193static int overlay_adjust_local_phandles(void *fdto, uint32_t delta)
194{
195 /*
196 * Start adjusting the phandles from the overlay root
197 */
198 return overlay_adjust_node_phandles(fdto, 0, delta);
199}
200
201/**
202 * overlay_update_local_node_references - Adjust the overlay references
203 * @fdto: Device tree overlay blob
204 * @tree_node: Node offset of the node to operate on
205 * @fixup_node: Node offset of the matching local fixups node
206 * @delta: Offset to shift the phandles of
207 *
208 * overlay_update_local_nodes_references() update the phandles
209 * pointing to a node within the device tree overlay by adding a
210 * constant delta.
211 *
212 * This is mainly used as part of a device tree application process,
213 * where you want the device tree overlays phandles to not conflict
214 * with the ones from the base device tree before merging them.
215 *
216 * returns:
217 * 0 on success
218 * Negative error code on failure
219 */
220static int overlay_update_local_node_references(void *fdto,
221 int tree_node,
222 int fixup_node,
223 uint32_t delta)
224{
225 int fixup_prop;
226 int fixup_child;
227 int ret;
228
229 fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
230 const fdt32_t *fixup_val;
231 const char *tree_val;
232 const char *name;
233 int fixup_len;
234 int tree_len;
235 int i;
236
237 fixup_val = fdt_getprop_by_offset(fdto, fixup_prop,
238 &name, &fixup_len);
239 if (!fixup_val)
240 return fixup_len;
241
242 if (fixup_len % sizeof(uint32_t))
243 return -FDT_ERR_BADOVERLAY;
244
245 tree_val = fdt_getprop(fdto, tree_node, name, &tree_len);
246 if (!tree_val) {
247 if (tree_len == -FDT_ERR_NOTFOUND)
248 return -FDT_ERR_BADOVERLAY;
249
250 return tree_len;
251 }
252
253 for (i = 0; i < (fixup_len / sizeof(uint32_t)); i++) {
254 fdt32_t adj_val;
255 uint32_t poffset;
256
257 poffset = fdt32_to_cpu(fixup_val[i]);
258
259 /*
260 * phandles to fixup can be unaligned.
261 *
262 * Use a memcpy for the architectures that do
263 * not support unaligned accesses.
264 */
265 memcpy(&adj_val, tree_val + poffset, sizeof(adj_val));
266
267 adj_val = cpu_to_fdt32(fdt32_to_cpu(adj_val) + delta);
268
269 ret = fdt_setprop_inplace_namelen_partial(fdto,
270 tree_node,
271 name,
272 strlen(name),
273 poffset,
274 &adj_val,
275 sizeof(adj_val));
276 if (ret == -FDT_ERR_NOSPACE)
277 return -FDT_ERR_BADOVERLAY;
278
279 if (ret)
280 return ret;
281 }
282 }
283
284 fdt_for_each_subnode(fixup_child, fdto, fixup_node) {
285 const char *fixup_child_name = fdt_get_name(fdto, fixup_child,
286 NULL);
287 int tree_child;
288
289 tree_child = fdt_subnode_offset(fdto, tree_node,
290 fixup_child_name);
291 if (tree_child == -FDT_ERR_NOTFOUND)
292 return -FDT_ERR_BADOVERLAY;
293 if (tree_child < 0)
294 return tree_child;
295
296 ret = overlay_update_local_node_references(fdto,
297 tree_child,
298 fixup_child,
299 delta);
300 if (ret)
301 return ret;
302 }
303
304 return 0;
305}
306
307/**
308 * overlay_update_local_references - Adjust the overlay references
309 * @fdto: Device tree overlay blob
310 * @delta: Offset to shift the phandles of
311 *
312 * overlay_update_local_references() update all the phandles pointing
313 * to a node within the device tree overlay by adding a constant
314 * delta to not conflict with the base overlay.
315 *
316 * This is mainly used as part of a device tree application process,
317 * where you want the device tree overlays phandles to not conflict
318 * with the ones from the base device tree before merging them.
319 *
320 * returns:
321 * 0 on success
322 * Negative error code on failure
323 */
324static int overlay_update_local_references(void *fdto, uint32_t delta)
325{
326 int fixups;
327
328 fixups = fdt_path_offset(fdto, "/__local_fixups__");
329 if (fixups < 0) {
330 /* There's no local phandles to adjust, bail out */
331 if (fixups == -FDT_ERR_NOTFOUND)
332 return 0;
333
334 return fixups;
335 }
336
337 /*
338 * Update our local references from the root of the tree
339 */
340 return overlay_update_local_node_references(fdto, 0, fixups,
341 delta);
342}
343
344/**
345 * overlay_fixup_one_phandle - Set an overlay phandle to the base one
346 * @fdt: Base Device Tree blob
347 * @fdto: Device tree overlay blob
348 * @symbols_off: Node offset of the symbols node in the base device tree
349 * @path: Path to a node holding a phandle in the overlay
350 * @path_len: number of path characters to consider
351 * @name: Name of the property holding the phandle reference in the overlay
352 * @name_len: number of name characters to consider
353 * @poffset: Offset within the overlay property where the phandle is stored
354 * @label: Label of the node referenced by the phandle
355 *
356 * overlay_fixup_one_phandle() resolves an overlay phandle pointing to
357 * a node in the base device tree.
358 *
359 * This is part of the device tree overlay application process, when
360 * you want all the phandles in the overlay to point to the actual
361 * base dt nodes.
362 *
363 * returns:
364 * 0 on success
365 * Negative error code on failure
366 */
367static int overlay_fixup_one_phandle(void *fdt, void *fdto,
368 int symbols_off,
369 const char *path, uint32_t path_len,
370 const char *name, uint32_t name_len,
371 int poffset, const char *label)
372{
373 const char *symbol_path;
374 uint32_t phandle;
375 fdt32_t phandle_prop;
376 int symbol_off, fixup_off;
377 int prop_len;
378
379 if (symbols_off < 0)
380 return symbols_off;
381
382 symbol_path = fdt_getprop(fdt, symbols_off, label,
383 &prop_len);
384 if (!symbol_path)
385 return prop_len;
386
387 symbol_off = fdt_path_offset(fdt, symbol_path);
388 if (symbol_off < 0)
389 return symbol_off;
390
391 phandle = fdt_get_phandle(fdt, symbol_off);
392 if (!phandle)
393 return -FDT_ERR_NOTFOUND;
394
395 fixup_off = fdt_path_offset_namelen(fdto, path, path_len);
396 if (fixup_off == -FDT_ERR_NOTFOUND)
397 return -FDT_ERR_BADOVERLAY;
398 if (fixup_off < 0)
399 return fixup_off;
400
401 phandle_prop = cpu_to_fdt32(phandle);
402 return fdt_setprop_inplace_namelen_partial(fdto, fixup_off,
403 name, name_len, poffset,
404 &phandle_prop,
405 sizeof(phandle_prop));
406};
407
408/**
409 * overlay_fixup_phandle - Set an overlay phandle to the base one
410 * @fdt: Base Device Tree blob
411 * @fdto: Device tree overlay blob
412 * @symbols_off: Node offset of the symbols node in the base device tree
413 * @property: Property offset in the overlay holding the list of fixups
414 *
415 * overlay_fixup_phandle() resolves all the overlay phandles pointed
416 * to in a __fixups__ property, and updates them to match the phandles
417 * in use in the base device tree.
418 *
419 * This is part of the device tree overlay application process, when
420 * you want all the phandles in the overlay to point to the actual
421 * base dt nodes.
422 *
423 * returns:
424 * 0 on success
425 * Negative error code on failure
426 */
427static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
428 int property)
429{
430 const char *value;
431 const char *label;
432 int len;
433
434 value = fdt_getprop_by_offset(fdto, property,
435 &label, &len);
436 if (!value) {
437 if (len == -FDT_ERR_NOTFOUND)
438 return -FDT_ERR_INTERNAL;
439
440 return len;
441 }
442
443 do {
444 const char *path, *name, *fixup_end;
445 const char *fixup_str = value;
446 uint32_t path_len, name_len;
447 uint32_t fixup_len;
448 char *sep, *endptr;
449 int poffset, ret;
450
451 fixup_end = memchr(value, '\0', len);
452 if (!fixup_end)
453 return -FDT_ERR_BADOVERLAY;
454 fixup_len = fixup_end - fixup_str;
455
456 len -= fixup_len + 1;
457 value += fixup_len + 1;
458
459 path = fixup_str;
460 sep = memchr(fixup_str, ':', fixup_len);
461 if (!sep || *sep != ':')
462 return -FDT_ERR_BADOVERLAY;
463
464 path_len = sep - path;
465 if (path_len == (fixup_len - 1))
466 return -FDT_ERR_BADOVERLAY;
467
468 fixup_len -= path_len + 1;
469 name = sep + 1;
470 sep = memchr(name, ':', fixup_len);
471 if (!sep || *sep != ':')
472 return -FDT_ERR_BADOVERLAY;
473
474 name_len = sep - name;
475 if (!name_len)
476 return -FDT_ERR_BADOVERLAY;
477
478 poffset = strtoul(sep + 1, &endptr, 10);
479 if ((*endptr != '\0') || (endptr <= (sep + 1)))
480 return -FDT_ERR_BADOVERLAY;
481
482 ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
483 path, path_len, name, name_len,
484 poffset, label);
485 if (ret)
486 return ret;
487 } while (len > 0);
488
489 return 0;
490}
491
492/**
493 * overlay_fixup_phandles - Resolve the overlay phandles to the base
494 * device tree
495 * @fdt: Base Device Tree blob
496 * @fdto: Device tree overlay blob
497 *
498 * overlay_fixup_phandles() resolves all the overlay phandles pointing
499 * to nodes in the base device tree.
500 *
501 * This is one of the steps of the device tree overlay application
502 * process, when you want all the phandles in the overlay to point to
503 * the actual base dt nodes.
504 *
505 * returns:
506 * 0 on success
507 * Negative error code on failure
508 */
509static int overlay_fixup_phandles(void *fdt, void *fdto)
510{
511 int fixups_off, symbols_off;
512 int property;
513
514 /* We can have overlays without any fixups */
515 fixups_off = fdt_path_offset(fdto, "/__fixups__");
516 if (fixups_off == -FDT_ERR_NOTFOUND)
517 return 0; /* nothing to do */
518 if (fixups_off < 0)
519 return fixups_off;
520
521 /* And base DTs without symbols */
522 symbols_off = fdt_path_offset(fdt, "/__symbols__");
523 if ((symbols_off < 0 && (symbols_off != -FDT_ERR_NOTFOUND)))
524 return symbols_off;
525
526 fdt_for_each_property_offset(property, fdto, fixups_off) {
527 int ret;
528
529 ret = overlay_fixup_phandle(fdt, fdto, symbols_off, property);
530 if (ret)
531 return ret;
532 }
533
534 return 0;
535}
536
537/**
538 * overlay_apply_node - Merges a node into the base device tree
539 * @fdt: Base Device Tree blob
540 * @target: Node offset in the base device tree to apply the fragment to
541 * @fdto: Device tree overlay blob
542 * @node: Node offset in the overlay holding the changes to merge
543 *
544 * overlay_apply_node() merges a node into a target base device tree
545 * node pointed.
546 *
547 * This is part of the final step in the device tree overlay
548 * application process, when all the phandles have been adjusted and
549 * resolved and you just have to merge overlay into the base device
550 * tree.
551 *
552 * returns:
553 * 0 on success
554 * Negative error code on failure
555 */
556static int overlay_apply_node(void *fdt, int target,
557 void *fdto, int node)
558{
559 int property;
560 int subnode;
561
562 fdt_for_each_property_offset(property, fdto, node) {
563 const char *name;
564 const void *prop;
565 int prop_len;
566 int ret;
567
568 prop = fdt_getprop_by_offset(fdto, property, &name,
569 &prop_len);
570 if (prop_len == -FDT_ERR_NOTFOUND)
571 return -FDT_ERR_INTERNAL;
572 if (prop_len < 0)
573 return prop_len;
574
575 ret = fdt_setprop(fdt, target, name, prop, prop_len);
576 if (ret)
577 return ret;
578 }
579
580 fdt_for_each_subnode(subnode, fdto, node) {
581 const char *name = fdt_get_name(fdto, subnode, NULL);
582 int nnode;
583 int ret;
584
585 nnode = fdt_add_subnode(fdt, target, name);
586 if (nnode == -FDT_ERR_EXISTS) {
587 nnode = fdt_subnode_offset(fdt, target, name);
588 if (nnode == -FDT_ERR_NOTFOUND)
589 return -FDT_ERR_INTERNAL;
590 }
591
592 if (nnode < 0)
593 return nnode;
594
595 ret = overlay_apply_node(fdt, nnode, fdto, subnode);
596 if (ret)
597 return ret;
598 }
599
600 return 0;
601}
602
603/**
604 * overlay_merge - Merge an overlay into its base device tree
605 * @fdt: Base Device Tree blob
606 * @fdto: Device tree overlay blob
607 *
608 * overlay_merge() merges an overlay into its base device tree.
609 *
610 * This is the next to last step in the device tree overlay application
611 * process, when all the phandles have been adjusted and resolved and
612 * you just have to merge overlay into the base device tree.
613 *
614 * returns:
615 * 0 on success
616 * Negative error code on failure
617 */
618static int overlay_merge(void *fdt, void *fdto)
619{
620 int fragment;
621
622 fdt_for_each_subnode(fragment, fdto, 0) {
623 int overlay;
624 int target;
625 int ret;
626
627 /*
628 * Each fragments will have an __overlay__ node. If
629 * they don't, it's not supposed to be merged
630 */
631 overlay = fdt_subnode_offset(fdto, fragment, "__overlay__");
632 if (overlay == -FDT_ERR_NOTFOUND)
633 continue;
634
635 if (overlay < 0)
636 return overlay;
637
638 target = overlay_get_target(fdt, fdto, fragment, NULL);
639 if (target < 0)
640 return target;
641
642 ret = overlay_apply_node(fdt, target, fdto, overlay);
643 if (ret)
644 return ret;
645 }
646
647 return 0;
648}
649
650static int get_path_len(const void *fdt, int nodeoffset)
651{
652 int len = 0, namelen;
653 const char *name;
654
655 FDT_RO_PROBE(fdt);
656
657 for (;;) {
658 name = fdt_get_name(fdt, nodeoffset, &namelen);
659 if (!name)
660 return namelen;
661
662 /* root? we're done */
663 if (namelen == 0)
664 break;
665
666 nodeoffset = fdt_parent_offset(fdt, nodeoffset);
667 if (nodeoffset < 0)
668 return nodeoffset;
669 len += namelen + 1;
670 }
671
672 /* in case of root pretend it's "/" */
673 if (len == 0)
674 len++;
675 return len;
676}
677
678/**
679 * overlay_symbol_update - Update the symbols of base tree after a merge
680 * @fdt: Base Device Tree blob
681 * @fdto: Device tree overlay blob
682 *
683 * overlay_symbol_update() updates the symbols of the base tree with the
684 * symbols of the applied overlay
685 *
686 * This is the last step in the device tree overlay application
687 * process, allowing the reference of overlay symbols by subsequent
688 * overlay operations.
689 *
690 * returns:
691 * 0 on success
692 * Negative error code on failure
693 */
694static int overlay_symbol_update(void *fdt, void *fdto)
695{
696 int root_sym, ov_sym, prop, path_len, fragment, target;
697 int len, frag_name_len, ret, rel_path_len;
698 const char *s, *e;
699 const char *path;
700 const char *name;
701 const char *frag_name;
702 const char *rel_path;
703 const char *target_path;
704 char *buf;
705 void *p;
706
707 ov_sym = fdt_subnode_offset(fdto, 0, "__symbols__");
708
709 /* if no overlay symbols exist no problem */
710 if (ov_sym < 0)
711 return 0;
712
713 root_sym = fdt_subnode_offset(fdt, 0, "__symbols__");
714
715 /* it no root symbols exist we should create them */
716 if (root_sym == -FDT_ERR_NOTFOUND)
717 root_sym = fdt_add_subnode(fdt, 0, "__symbols__");
718
719 /* any error is fatal now */
720 if (root_sym < 0)
721 return root_sym;
722
723 /* iterate over each overlay symbol */
724 fdt_for_each_property_offset(prop, fdto, ov_sym) {
725 path = fdt_getprop_by_offset(fdto, prop, &name, &path_len);
726 if (!path)
727 return path_len;
728
729 /* verify it's a string property (terminated by a single \0) */
730 if (path_len < 1 || memchr(path, '\0', path_len) != &path[path_len - 1])
731 return -FDT_ERR_BADVALUE;
732
733 /* keep end marker to avoid strlen() */
734 e = path + path_len;
735
736 if (*path != '/')
737 return -FDT_ERR_BADVALUE;
738
739 /* get fragment name first */
740 s = strchr(path + 1, '/');
741 if (!s) {
742 /* Symbol refers to something that won't end
743 * up in the target tree */
744 continue;
745 }
746
747 frag_name = path + 1;
748 frag_name_len = s - path - 1;
749
750 /* verify format; safe since "s" lies in \0 terminated prop */
751 len = sizeof("/__overlay__/") - 1;
752 if ((e - s) > len && (memcmp(s, "/__overlay__/", len) == 0)) {
753 /* /<fragment-name>/__overlay__/<relative-subnode-path> */
754 rel_path = s + len;
755 rel_path_len = e - rel_path - 1;
756 } else if ((e - s) == len
757 && (memcmp(s, "/__overlay__", len - 1) == 0)) {
758 /* /<fragment-name>/__overlay__ */
759 rel_path = "";
760 rel_path_len = 0;
761 } else {
762 /* Symbol refers to something that won't end
763 * up in the target tree */
764 continue;
765 }
766
767 /* find the fragment index in which the symbol lies */
768 ret = fdt_subnode_offset_namelen(fdto, 0, frag_name,
769 frag_name_len);
770 /* not found? */
771 if (ret < 0)
772 return -FDT_ERR_BADOVERLAY;
773 fragment = ret;
774
775 /* an __overlay__ subnode must exist */
776 ret = fdt_subnode_offset(fdto, fragment, "__overlay__");
777 if (ret < 0)
778 return -FDT_ERR_BADOVERLAY;
779
780 /* get the target of the fragment */
781 ret = overlay_get_target(fdt, fdto, fragment, &target_path);
782 if (ret < 0)
783 return ret;
784 target = ret;
785
786 /* if we have a target path use */
787 if (!target_path) {
788 ret = get_path_len(fdt, target);
789 if (ret < 0)
790 return ret;
791 len = ret;
792 } else {
793 len = strlen(target_path);
794 }
795
796 ret = fdt_setprop_placeholder(fdt, root_sym, name,
797 len + (len > 1) + rel_path_len + 1, &p);
798 if (ret < 0)
799 return ret;
800
801 if (!target_path) {
802 /* again in case setprop_placeholder changed it */
803 ret = overlay_get_target(fdt, fdto, fragment, &target_path);
804 if (ret < 0)
805 return ret;
806 target = ret;
807 }
808
809 buf = p;
810 if (len > 1) { /* target is not root */
811 if (!target_path) {
812 ret = fdt_get_path(fdt, target, buf, len + 1);
813 if (ret < 0)
814 return ret;
815 } else
816 memcpy(buf, target_path, len + 1);
817
818 } else
819 len--;
820
821 buf[len] = '/';
822 memcpy(buf + len + 1, rel_path, rel_path_len);
823 buf[len + 1 + rel_path_len] = '\0';
824 }
825
826 return 0;
827}
828
829int fdt_overlay_apply(void *fdt, void *fdto)
830{
831 uint32_t delta;
832 int ret;
833
834 FDT_RO_PROBE(fdt);
835 FDT_RO_PROBE(fdto);
836
837 ret = fdt_find_max_phandle(fdt, &delta);
838 if (ret)
839 goto err;
840
841 ret = overlay_adjust_local_phandles(fdto, delta);
842 if (ret)
843 goto err;
844
845 ret = overlay_update_local_references(fdto, delta);
846 if (ret)
847 goto err;
848
849 ret = overlay_fixup_phandles(fdt, fdto);
850 if (ret)
851 goto err;
852
853 ret = overlay_merge(fdt, fdto);
854 if (ret)
855 goto err;
856
857 ret = overlay_symbol_update(fdt, fdto);
858 if (ret)
859 goto err;
860
861 /*
862 * The overlay has been damaged, erase its magic.
863 */
864 fdt_set_magic(fdto, ~0);
865
866 return 0;
867
868err:
869 /*
870 * The overlay might have been damaged, erase its magic.
871 */
872 fdt_set_magic(fdto, ~0);
873
874 /*
875 * The base device tree might have been damaged, erase its
876 * magic.
877 */
878 fdt_set_magic(fdt, ~0);
879
880 return ret;
881}