1 /*
2 * libfdt - Flat Device Tree manipulation
3 * Copyright (C) 2016 Free Electrons
4 * Copyright (C) 2016 NextThing Co.
5 *
6 * libfdt is dual licensed: you can use it either under the terms of
7 * the GPL, or the BSD license, at your option.
8 *
9 * a) This library is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License as
11 * published by the Free Software Foundation; either version 2 of the
12 * License, or (at your option) any later version.
13 *
14 * This library is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public
20 * License along with this library; if not, write to the Free
21 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
22 * MA 02110-1301 USA
23 *
24 * Alternatively,
25 *
26 * b) Redistribution and use in source and binary forms, with or
27 * without modification, are permitted provided that the following
28 * conditions are met:
29 *
30 * 1. Redistributions of source code must retain the above
31 * copyright notice, this list of conditions and the following
32 * disclaimer.
33 * 2. Redistributions in binary form must reproduce the above
34 * copyright notice, this list of conditions and the following
35 * disclaimer in the documentation and/or other materials
36 * provided with the distribution.
37 *
38 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
39 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
40 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
41 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
42 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
43 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
48 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
49 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
50 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
51 */
52 #include "libfdt_env.h"
53
54 #include <fdt.h>
55 #include <libfdt.h>
56
57 #include "libfdt_internal.h"
58
59 /**
60 * overlay_get_target_phandle - retrieves the target phandle of a fragment
61 * @fdto: pointer to the device tree overlay blob
62 * @fragment: node offset of the fragment in the overlay
63 *
64 * overlay_get_target_phandle() retrieves the target phandle of an
65 * overlay fragment when that fragment uses a phandle (target
66 * property) instead of a path (target-path property).
67 *
68 * returns:
69 * the phandle pointed by the target property
70 * 0, if the phandle was not found
71 * -1, if the phandle was malformed
72 */
overlay_get_target_phandle(const void * fdto,int fragment)73 static uint32_t overlay_get_target_phandle(const void *fdto, int fragment)
74 {
75 const fdt32_t *val;
76 int len;
77
78 val = fdt_getprop(fdto, fragment, "target", &len);
79 if (!val)
80 return 0;
81
82 if ((len != sizeof(*val)) || (fdt32_to_cpu(*val) == (uint32_t)-1))
83 return (uint32_t)-1;
84
85 return fdt32_to_cpu(*val);
86 }
87
88 /**
89 * overlay_get_target - retrieves the offset of a fragment's target
90 * @fdt: Base device tree blob
91 * @fdto: Device tree overlay blob
92 * @fragment: node offset of the fragment in the overlay
93 * @pathp: pointer which receives the path of the target (or NULL)
94 *
95 * overlay_get_target() retrieves the target offset in the base
96 * device tree of a fragment, no matter how the actual targetting is
97 * done (through a phandle or a path)
98 *
99 * returns:
100 * the targetted node offset in the base device tree
101 * Negative error code on error
102 */
overlay_get_target(const void * fdt,const void * fdto,int fragment,char const ** pathp)103 static int overlay_get_target(const void *fdt, const void *fdto,
104 int fragment, char const **pathp)
105 {
106 uint32_t phandle;
107 const char *path = NULL;
108 int path_len = 0, ret;
109
110 /* Try first to do a phandle based lookup */
111 phandle = overlay_get_target_phandle(fdto, fragment);
112 if (phandle == (uint32_t)-1)
113 return -FDT_ERR_BADPHANDLE;
114
115 /* no phandle, try path */
116 if (!phandle) {
117 /* And then a path based lookup */
118 path = fdt_getprop(fdto, fragment, "target-path", &path_len);
119 if (path)
120 ret = fdt_path_offset(fdt, path);
121 else
122 ret = path_len;
123 } else
124 ret = fdt_node_offset_by_phandle(fdt, phandle);
125
126 /*
127 * If we haven't found either a target or a
128 * target-path property in a node that contains a
129 * __overlay__ subnode (we wouldn't be called
130 * otherwise), consider it a improperly written
131 * overlay
132 */
133 if (ret < 0 && path_len == -FDT_ERR_NOTFOUND)
134 ret = -FDT_ERR_BADOVERLAY;
135
136 /* return on error */
137 if (ret < 0)
138 return ret;
139
140 /* return pointer to path (if available) */
141 if (pathp)
142 *pathp = path ? path : NULL;
143
144 return ret;
145 }
146
147 /**
148 * overlay_phandle_add_offset - Increases a phandle by an offset
149 * @fdt: Base device tree blob
150 * @node: Device tree overlay blob
151 * @name: Name of the property to modify (phandle or linux,phandle)
152 * @delta: offset to apply
153 *
154 * overlay_phandle_add_offset() increments a node phandle by a given
155 * offset.
156 *
157 * returns:
158 * 0 on success.
159 * Negative error code on error
160 */
overlay_phandle_add_offset(void * fdt,int node,const char * name,uint32_t delta)161 static int overlay_phandle_add_offset(void *fdt, int node,
162 const char *name, uint32_t delta)
163 {
164 const fdt32_t *val;
165 uint32_t adj_val;
166 int len;
167
168 val = fdt_getprop(fdt, node, name, &len);
169 if (!val)
170 return len;
171
172 if (len != sizeof(*val))
173 return -FDT_ERR_BADPHANDLE;
174
175 adj_val = fdt32_to_cpu(*val);
176 if ((adj_val + delta) < adj_val)
177 return -FDT_ERR_NOPHANDLES;
178
179 adj_val += delta;
180 if (adj_val == (uint32_t)-1)
181 return -FDT_ERR_NOPHANDLES;
182
183 return fdt_setprop_inplace_u32(fdt, node, name, adj_val);
184 }
185
186 /**
187 * overlay_adjust_node_phandles - Offsets the phandles of a node
188 * @fdto: Device tree overlay blob
189 * @node: Offset of the node we want to adjust
190 * @delta: Offset to shift the phandles of
191 *
192 * overlay_adjust_node_phandles() adds a constant to all the phandles
193 * of a given node. This is mainly use as part of the overlay
194 * application process, when we want to update all the overlay
195 * phandles to not conflict with the overlays of the base device tree.
196 *
197 * returns:
198 * 0 on success
199 * Negative error code on failure
200 */
overlay_adjust_node_phandles(void * fdto,int node,uint32_t delta)201 static int overlay_adjust_node_phandles(void *fdto, int node,
202 uint32_t delta)
203 {
204 int child;
205 int ret;
206
207 ret = overlay_phandle_add_offset(fdto, node, "phandle", delta);
208 if (ret && ret != -FDT_ERR_NOTFOUND)
209 return ret;
210
211 ret = overlay_phandle_add_offset(fdto, node, "linux,phandle", delta);
212 if (ret && ret != -FDT_ERR_NOTFOUND)
213 return ret;
214
215 fdt_for_each_subnode(child, fdto, node) {
216 ret = overlay_adjust_node_phandles(fdto, child, delta);
217 if (ret)
218 return ret;
219 }
220
221 return 0;
222 }
223
224 /**
225 * overlay_adjust_local_phandles - Adjust the phandles of a whole overlay
226 * @fdto: Device tree overlay blob
227 * @delta: Offset to shift the phandles of
228 *
229 * overlay_adjust_local_phandles() adds a constant to all the
230 * phandles of an overlay. This is mainly use as part of the overlay
231 * application process, when we want to update all the overlay
232 * phandles to not conflict with the overlays of the base device tree.
233 *
234 * returns:
235 * 0 on success
236 * Negative error code on failure
237 */
overlay_adjust_local_phandles(void * fdto,uint32_t delta)238 static int overlay_adjust_local_phandles(void *fdto, uint32_t delta)
239 {
240 /*
241 * Start adjusting the phandles from the overlay root
242 */
243 return overlay_adjust_node_phandles(fdto, 0, delta);
244 }
245
246 /**
247 * overlay_update_local_node_references - Adjust the overlay references
248 * @fdto: Device tree overlay blob
249 * @tree_node: Node offset of the node to operate on
250 * @fixup_node: Node offset of the matching local fixups node
251 * @delta: Offset to shift the phandles of
252 *
253 * overlay_update_local_nodes_references() update the phandles
254 * pointing to a node within the device tree overlay by adding a
255 * constant delta.
256 *
257 * This is mainly used as part of a device tree application process,
258 * where you want the device tree overlays phandles to not conflict
259 * with the ones from the base device tree before merging them.
260 *
261 * returns:
262 * 0 on success
263 * Negative error code on failure
264 */
overlay_update_local_node_references(void * fdto,int tree_node,int fixup_node,uint32_t delta)265 static int overlay_update_local_node_references(void *fdto,
266 int tree_node,
267 int fixup_node,
268 uint32_t delta)
269 {
270 int fixup_prop;
271 int fixup_child;
272 int ret;
273
274 fdt_for_each_property_offset(fixup_prop, fdto, fixup_node) {
275 const fdt32_t *fixup_val;
276 const char *tree_val;
277 const char *name;
278 int fixup_len;
279 int tree_len;
280 int i;
281
282 fixup_val = fdt_getprop_by_offset(fdto, fixup_prop,
283 &name, &fixup_len);
284 if (!fixup_val)
285 return fixup_len;
286
287 if (fixup_len % sizeof(uint32_t))
288 return -FDT_ERR_BADOVERLAY;
289
290 tree_val = fdt_getprop(fdto, tree_node, name, &tree_len);
291 if (!tree_val) {
292 if (tree_len == -FDT_ERR_NOTFOUND)
293 return -FDT_ERR_BADOVERLAY;
294
295 return tree_len;
296 }
297
298 for (i = 0; i < (fixup_len / sizeof(uint32_t)); i++) {
299 fdt32_t adj_val;
300 uint32_t poffset;
301
302 poffset = fdt32_to_cpu(fixup_val[i]);
303
304 /*
305 * phandles to fixup can be unaligned.
306 *
307 * Use a memcpy for the architectures that do
308 * not support unaligned accesses.
309 */
310 memcpy(&adj_val, tree_val + poffset, sizeof(adj_val));
311
312 adj_val = cpu_to_fdt32(fdt32_to_cpu(adj_val) + delta);
313
314 ret = fdt_setprop_inplace_namelen_partial(fdto,
315 tree_node,
316 name,
317 strlen(name),
318 poffset,
319 &adj_val,
320 sizeof(adj_val));
321 if (ret == -FDT_ERR_NOSPACE)
322 return -FDT_ERR_BADOVERLAY;
323
324 if (ret)
325 return ret;
326 }
327 }
328
329 fdt_for_each_subnode(fixup_child, fdto, fixup_node) {
330 const char *fixup_child_name = fdt_get_name(fdto, fixup_child,
331 NULL);
332 int tree_child;
333
334 tree_child = fdt_subnode_offset(fdto, tree_node,
335 fixup_child_name);
336 if (tree_child == -FDT_ERR_NOTFOUND)
337 return -FDT_ERR_BADOVERLAY;
338 if (tree_child < 0)
339 return tree_child;
340
341 ret = overlay_update_local_node_references(fdto,
342 tree_child,
343 fixup_child,
344 delta);
345 if (ret)
346 return ret;
347 }
348
349 return 0;
350 }
351
352 /**
353 * overlay_update_local_references - Adjust the overlay references
354 * @fdto: Device tree overlay blob
355 * @delta: Offset to shift the phandles of
356 *
357 * overlay_update_local_references() update all the phandles pointing
358 * to a node within the device tree overlay by adding a constant
359 * delta to not conflict with the base overlay.
360 *
361 * This is mainly used as part of a device tree application process,
362 * where you want the device tree overlays phandles to not conflict
363 * with the ones from the base device tree before merging them.
364 *
365 * returns:
366 * 0 on success
367 * Negative error code on failure
368 */
overlay_update_local_references(void * fdto,uint32_t delta)369 static int overlay_update_local_references(void *fdto, uint32_t delta)
370 {
371 int fixups;
372
373 fixups = fdt_path_offset(fdto, "/__local_fixups__");
374 if (fixups < 0) {
375 /* There's no local phandles to adjust, bail out */
376 if (fixups == -FDT_ERR_NOTFOUND)
377 return 0;
378
379 return fixups;
380 }
381
382 /*
383 * Update our local references from the root of the tree
384 */
385 return overlay_update_local_node_references(fdto, 0, fixups,
386 delta);
387 }
388
389 /**
390 * overlay_fixup_one_phandle - Set an overlay phandle to the base one
391 * @fdt: Base Device Tree blob
392 * @fdto: Device tree overlay blob
393 * @symbols_off: Node offset of the symbols node in the base device tree
394 * @path: Path to a node holding a phandle in the overlay
395 * @path_len: number of path characters to consider
396 * @name: Name of the property holding the phandle reference in the overlay
397 * @name_len: number of name characters to consider
398 * @poffset: Offset within the overlay property where the phandle is stored
399 * @label: Label of the node referenced by the phandle
400 *
401 * overlay_fixup_one_phandle() resolves an overlay phandle pointing to
402 * a node in the base device tree.
403 *
404 * This is part of the device tree overlay application process, when
405 * you want all the phandles in the overlay to point to the actual
406 * base dt nodes.
407 *
408 * returns:
409 * 0 on success
410 * Negative error code on failure
411 */
overlay_fixup_one_phandle(void * fdt,void * fdto,int symbols_off,const char * path,uint32_t path_len,const char * name,uint32_t name_len,int poffset,const char * label)412 static int overlay_fixup_one_phandle(void *fdt, void *fdto,
413 int symbols_off,
414 const char *path, uint32_t path_len,
415 const char *name, uint32_t name_len,
416 int poffset, const char *label)
417 {
418 const char *symbol_path;
419 uint32_t phandle;
420 fdt32_t phandle_prop;
421 int symbol_off, fixup_off;
422 int prop_len;
423
424 if (symbols_off < 0)
425 return symbols_off;
426
427 symbol_path = fdt_getprop(fdt, symbols_off, label,
428 &prop_len);
429 if (!symbol_path)
430 return prop_len;
431
432 symbol_off = fdt_path_offset(fdt, symbol_path);
433 if (symbol_off < 0)
434 return symbol_off;
435
436 phandle = fdt_get_phandle(fdt, symbol_off);
437 if (!phandle)
438 return -FDT_ERR_NOTFOUND;
439
440 fixup_off = fdt_path_offset_namelen(fdto, path, path_len);
441 if (fixup_off == -FDT_ERR_NOTFOUND)
442 return -FDT_ERR_BADOVERLAY;
443 if (fixup_off < 0)
444 return fixup_off;
445
446 phandle_prop = cpu_to_fdt32(phandle);
447 return fdt_setprop_inplace_namelen_partial(fdto, fixup_off,
448 name, name_len, poffset,
449 &phandle_prop,
450 sizeof(phandle_prop));
451 };
452
453 unsigned long strtoul(const char *nptr, char **endptr, int base);
454
455 /**
456 * overlay_fixup_phandle - Set an overlay phandle to the base one
457 * @fdt: Base Device Tree blob
458 * @fdto: Device tree overlay blob
459 * @symbols_off: Node offset of the symbols node in the base device tree
460 * @property: Property offset in the overlay holding the list of fixups
461 *
462 * overlay_fixup_phandle() resolves all the overlay phandles pointed
463 * to in a __fixups__ property, and updates them to match the phandles
464 * in use in the base device tree.
465 *
466 * This is part of the device tree overlay application process, when
467 * you want all the phandles in the overlay to point to the actual
468 * base dt nodes.
469 *
470 * returns:
471 * 0 on success
472 * Negative error code on failure
473 */
overlay_fixup_phandle(void * fdt,void * fdto,int symbols_off,int property)474 static int overlay_fixup_phandle(void *fdt, void *fdto, int symbols_off,
475 int property)
476 {
477 const char *value;
478 const char *label;
479 int len;
480
481 value = fdt_getprop_by_offset(fdto, property,
482 &label, &len);
483 if (!value) {
484 if (len == -FDT_ERR_NOTFOUND)
485 return -FDT_ERR_INTERNAL;
486
487 return len;
488 }
489
490 do {
491 const char *path, *name, *fixup_end;
492 const char *fixup_str = value;
493 uint32_t path_len, name_len;
494 uint32_t fixup_len;
495 char *sep, *endptr;
496 int poffset, ret;
497
498 fixup_end = memchr(value, '\0', len);
499 if (!fixup_end)
500 return -FDT_ERR_BADOVERLAY;
501 fixup_len = fixup_end - fixup_str;
502
503 len -= fixup_len + 1;
504 value += fixup_len + 1;
505
506 path = fixup_str;
507 sep = memchr(fixup_str, ':', fixup_len);
508 if (!sep || *sep != ':')
509 return -FDT_ERR_BADOVERLAY;
510
511 path_len = sep - path;
512 if (path_len == (fixup_len - 1))
513 return -FDT_ERR_BADOVERLAY;
514
515 fixup_len -= path_len + 1;
516 name = sep + 1;
517 sep = memchr(name, ':', fixup_len);
518 if (!sep || *sep != ':')
519 return -FDT_ERR_BADOVERLAY;
520
521 name_len = sep - name;
522 if (!name_len)
523 return -FDT_ERR_BADOVERLAY;
524
525 poffset = strtoul(sep + 1, &endptr, 10);
526 if ((*endptr != '\0') || (endptr <= (sep + 1)))
527 return -FDT_ERR_BADOVERLAY;
528
529 ret = overlay_fixup_one_phandle(fdt, fdto, symbols_off,
530 path, path_len, name, name_len,
531 poffset, label);
532 if (ret)
533 return ret;
534 } while (len > 0);
535
536 return 0;
537 }
538
539 /**
540 * overlay_fixup_phandles - Resolve the overlay phandles to the base
541 * device tree
542 * @fdt: Base Device Tree blob
543 * @fdto: Device tree overlay blob
544 *
545 * overlay_fixup_phandles() resolves all the overlay phandles pointing
546 * to nodes in the base device tree.
547 *
548 * This is one of the steps of the device tree overlay application
549 * process, when you want all the phandles in the overlay to point to
550 * the actual base dt nodes.
551 *
552 * returns:
553 * 0 on success
554 * Negative error code on failure
555 */
overlay_fixup_phandles(void * fdt,void * fdto)556 static int overlay_fixup_phandles(void *fdt, void *fdto)
557 {
558 int fixups_off, symbols_off;
559 int property;
560
561 /* We can have overlays without any fixups */
562 fixups_off = fdt_path_offset(fdto, "/__fixups__");
563 if (fixups_off == -FDT_ERR_NOTFOUND)
564 return 0; /* nothing to do */
565 if (fixups_off < 0)
566 return fixups_off;
567
568 /* And base DTs without symbols */
569 symbols_off = fdt_path_offset(fdt, "/__symbols__");
570 if ((symbols_off < 0 && (symbols_off != -FDT_ERR_NOTFOUND)))
571 return symbols_off;
572
573 fdt_for_each_property_offset(property, fdto, fixups_off) {
574 int ret;
575
576 ret = overlay_fixup_phandle(fdt, fdto, symbols_off, property);
577 if (ret)
578 return ret;
579 }
580
581 return 0;
582 }
583
584 /**
585 * overlay_apply_node - Merges a node into the base device tree
586 * @fdt: Base Device Tree blob
587 * @target: Node offset in the base device tree to apply the fragment to
588 * @fdto: Device tree overlay blob
589 * @node: Node offset in the overlay holding the changes to merge
590 *
591 * overlay_apply_node() merges a node into a target base device tree
592 * node pointed.
593 *
594 * This is part of the final step in the device tree overlay
595 * application process, when all the phandles have been adjusted and
596 * resolved and you just have to merge overlay into the base device
597 * tree.
598 *
599 * returns:
600 * 0 on success
601 * Negative error code on failure
602 */
overlay_apply_node(void * fdt,int target,void * fdto,int node)603 static int overlay_apply_node(void *fdt, int target,
604 void *fdto, int node)
605 {
606 int property;
607 int subnode;
608
609 fdt_for_each_property_offset(property, fdto, node) {
610 const char *name;
611 const void *prop;
612 int prop_len;
613 int ret;
614
615 prop = fdt_getprop_by_offset(fdto, property, &name,
616 &prop_len);
617 if (prop_len == -FDT_ERR_NOTFOUND)
618 return -FDT_ERR_INTERNAL;
619 if (prop_len < 0)
620 return prop_len;
621
622 ret = fdt_setprop(fdt, target, name, prop, prop_len);
623 if (ret)
624 return ret;
625 }
626
627 fdt_for_each_subnode(subnode, fdto, node) {
628 const char *name = fdt_get_name(fdto, subnode, NULL);
629 int nnode;
630 int ret;
631
632 nnode = fdt_add_subnode(fdt, target, name);
633 if (nnode == -FDT_ERR_EXISTS) {
634 nnode = fdt_subnode_offset(fdt, target, name);
635 if (nnode == -FDT_ERR_NOTFOUND)
636 return -FDT_ERR_INTERNAL;
637 }
638
639 if (nnode < 0)
640 return nnode;
641
642 ret = overlay_apply_node(fdt, nnode, fdto, subnode);
643 if (ret)
644 return ret;
645 }
646
647 return 0;
648 }
649
650 /**
651 * overlay_merge - Merge an overlay into its base device tree
652 * @fdt: Base Device Tree blob
653 * @fdto: Device tree overlay blob
654 *
655 * overlay_merge() merges an overlay into its base device tree.
656 *
657 * This is the next to last step in the device tree overlay application
658 * process, when all the phandles have been adjusted and resolved and
659 * you just have to merge overlay into the base device tree.
660 *
661 * returns:
662 * 0 on success
663 * Negative error code on failure
664 */
overlay_merge(void * fdt,void * fdto)665 static int overlay_merge(void *fdt, void *fdto)
666 {
667 int fragment;
668
669 fdt_for_each_subnode(fragment, fdto, 0) {
670 int overlay;
671 int target;
672 int ret;
673
674 /*
675 * Each fragments will have an __overlay__ node. If
676 * they don't, it's not supposed to be merged
677 */
678 overlay = fdt_subnode_offset(fdto, fragment, "__overlay__");
679 if (overlay == -FDT_ERR_NOTFOUND)
680 continue;
681
682 if (overlay < 0)
683 return overlay;
684
685 target = overlay_get_target(fdt, fdto, fragment, NULL);
686 if (target < 0)
687 return target;
688
689 ret = overlay_apply_node(fdt, target, fdto, overlay);
690 if (ret)
691 return ret;
692 }
693
694 return 0;
695 }
696
get_path_len(const void * fdt,int nodeoffset)697 static int get_path_len(const void *fdt, int nodeoffset)
698 {
699 int len = 0, namelen;
700 const char *name;
701
702 FDT_CHECK_HEADER(fdt);
703
704 for (;;) {
705 name = fdt_get_name(fdt, nodeoffset, &namelen);
706 if (!name)
707 return namelen;
708
709 /* root? we're done */
710 if (namelen == 0)
711 break;
712
713 nodeoffset = fdt_parent_offset(fdt, nodeoffset);
714 if (nodeoffset < 0)
715 return nodeoffset;
716 len += namelen + 1;
717 }
718
719 /* in case of root pretend it's "/" */
720 if (len == 0)
721 len++;
722 return len;
723 }
724
725 /**
726 * overlay_symbol_update - Update the symbols of base tree after a merge
727 * @fdt: Base Device Tree blob
728 * @fdto: Device tree overlay blob
729 *
730 * overlay_symbol_update() updates the symbols of the base tree with the
731 * symbols of the applied overlay
732 *
733 * This is the last step in the device tree overlay application
734 * process, allowing the reference of overlay symbols by subsequent
735 * overlay operations.
736 *
737 * returns:
738 * 0 on success
739 * Negative error code on failure
740 */
overlay_symbol_update(void * fdt,void * fdto)741 static int overlay_symbol_update(void *fdt, void *fdto)
742 {
743 int root_sym, ov_sym, prop, path_len, fragment, target;
744 int len, frag_name_len, ret, rel_path_len;
745 const char *s, *e;
746 const char *path;
747 const char *name;
748 const char *frag_name;
749 const char *rel_path;
750 const char *target_path;
751 char *buf;
752 void *p;
753
754 ov_sym = fdt_subnode_offset(fdto, 0, "__symbols__");
755
756 /* if no overlay symbols exist no problem */
757 if (ov_sym < 0)
758 return 0;
759
760 root_sym = fdt_subnode_offset(fdt, 0, "__symbols__");
761
762 /* it no root symbols exist we should create them */
763 if (root_sym == -FDT_ERR_NOTFOUND)
764 root_sym = fdt_add_subnode(fdt, 0, "__symbols__");
765
766 /* any error is fatal now */
767 if (root_sym < 0)
768 return root_sym;
769
770 /* iterate over each overlay symbol */
771 fdt_for_each_property_offset(prop, fdto, ov_sym) {
772 path = fdt_getprop_by_offset(fdto, prop, &name, &path_len);
773 if (!path)
774 return path_len;
775
776 /* verify it's a string property (terminated by a single \0) */
777 if (path_len < 1 || memchr(path, '\0', path_len) != &path[path_len - 1])
778 return -FDT_ERR_BADVALUE;
779
780 /* keep end marker to avoid strlen() */
781 e = path + path_len;
782
783 /* format: /<fragment-name>/__overlay__/<relative-subnode-path> */
784
785 if (*path != '/')
786 return -FDT_ERR_BADVALUE;
787
788 /* get fragment name first */
789 s = strchr(path + 1, '/');
790 if (!s)
791 return -FDT_ERR_BADOVERLAY;
792
793 frag_name = path + 1;
794 frag_name_len = s - path - 1;
795
796 /* verify format; safe since "s" lies in \0 terminated prop */
797 len = sizeof("/__overlay__/") - 1;
798 if ((e - s) < len || memcmp(s, "/__overlay__/", len))
799 return -FDT_ERR_BADOVERLAY;
800
801 rel_path = s + len;
802 rel_path_len = e - rel_path;
803
804 /* find the fragment index in which the symbol lies */
805 ret = fdt_subnode_offset_namelen(fdto, 0, frag_name,
806 frag_name_len);
807 /* not found? */
808 if (ret < 0)
809 return -FDT_ERR_BADOVERLAY;
810 fragment = ret;
811
812 /* an __overlay__ subnode must exist */
813 ret = fdt_subnode_offset(fdto, fragment, "__overlay__");
814 if (ret < 0)
815 return -FDT_ERR_BADOVERLAY;
816
817 /* get the target of the fragment */
818 ret = overlay_get_target(fdt, fdto, fragment, &target_path);
819 if (ret < 0)
820 return ret;
821 target = ret;
822
823 /* if we have a target path use */
824 if (!target_path) {
825 ret = get_path_len(fdt, target);
826 if (ret < 0)
827 return ret;
828 len = ret;
829 } else {
830 len = strlen(target_path);
831 }
832
833 ret = fdt_setprop_placeholder(fdt, root_sym, name,
834 len + (len > 1) + rel_path_len + 1, &p);
835 if (ret < 0)
836 return ret;
837
838 if (!target_path) {
839 /* again in case setprop_placeholder changed it */
840 ret = overlay_get_target(fdt, fdto, fragment, &target_path);
841 if (ret < 0)
842 return ret;
843 target = ret;
844 }
845
846 buf = p;
847 if (len > 1) { /* target is not root */
848 if (!target_path) {
849 ret = fdt_get_path(fdt, target, buf, len + 1);
850 if (ret < 0)
851 return ret;
852 } else
853 memcpy(buf, target_path, len + 1);
854
855 } else
856 len--;
857
858 buf[len] = '/';
859 memcpy(buf + len + 1, rel_path, rel_path_len);
860 buf[len + 1 + rel_path_len] = '\0';
861 }
862
863 return 0;
864 }
865
fdt_overlay_apply(void * fdt,void * fdto)866 int fdt_overlay_apply(void *fdt, void *fdto)
867 {
868 uint32_t delta = fdt_get_max_phandle(fdt);
869 int ret;
870
871 FDT_CHECK_HEADER(fdt);
872 FDT_CHECK_HEADER(fdto);
873
874 ret = overlay_adjust_local_phandles(fdto, delta);
875 if (ret)
876 goto err;
877
878 ret = overlay_update_local_references(fdto, delta);
879 if (ret)
880 goto err;
881
882 ret = overlay_fixup_phandles(fdt, fdto);
883 if (ret)
884 goto err;
885
886 ret = overlay_merge(fdt, fdto);
887 if (ret)
888 goto err;
889
890 ret = overlay_symbol_update(fdt, fdto);
891 if (ret)
892 goto err;
893
894 /*
895 * The overlay has been damaged, erase its magic.
896 */
897 fdt_set_magic(fdto, ~0);
898
899 return 0;
900
901 err:
902 /*
903 * The overlay might have been damaged, erase its magic.
904 */
905 fdt_set_magic(fdto, ~0);
906
907 /*
908 * The base device tree might have been damaged, erase its
909 * magic.
910 */
911 fdt_set_magic(fdt, ~0);
912
913 return ret;
914 }
915