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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Functions for working with device tree overlays
4 *
5 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
6 * Copyright (C) 2012 Texas Instruments Inc.
7 */
8
9#define pr_fmt(fmt) "OF: overlay: " fmt
10
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/of.h>
14#include <linux/of_device.h>
15#include <linux/of_fdt.h>
16#include <linux/string.h>
17#include <linux/ctype.h>
18#include <linux/errno.h>
19#include <linux/slab.h>
20#include <linux/libfdt.h>
21#include <linux/err.h>
22#include <linux/idr.h>
23
24#include "of_private.h"
25
26/**
27 * struct target - info about current target node as recursing through overlay
28 * @np: node where current level of overlay will be applied
29 * @in_livetree: @np is a node in the live devicetree
30 *
31 * Used in the algorithm to create the portion of a changeset that describes
32 * an overlay fragment, which is a devicetree subtree. Initially @np is a node
33 * in the live devicetree where the overlay subtree is targeted to be grafted
34 * into. When recursing to the next level of the overlay subtree, the target
35 * also recurses to the next level of the live devicetree, as long as overlay
36 * subtree node also exists in the live devicetree. When a node in the overlay
37 * subtree does not exist at the same level in the live devicetree, target->np
38 * points to a newly allocated node, and all subsequent targets in the subtree
39 * will be newly allocated nodes.
40 */
41struct target {
42 struct device_node *np;
43 bool in_livetree;
44};
45
46/**
47 * struct fragment - info about fragment nodes in overlay expanded device tree
48 * @overlay: pointer to the __overlay__ node
49 * @target: target of the overlay operation
50 */
51struct fragment {
52 struct device_node *overlay;
53 struct device_node *target;
54};
55
56/**
57 * struct overlay_changeset
58 * @id: changeset identifier
59 * @ovcs_list: list on which we are located
60 * @new_fdt: Memory allocated to hold unflattened aligned FDT
61 * @overlay_mem: the memory chunk that contains @overlay_root
62 * @overlay_root: expanded device tree that contains the fragment nodes
63 * @notify_state: most recent notify action used on overlay
64 * @count: count of fragment structures
65 * @fragments: fragment nodes in the overlay expanded device tree
66 * @symbols_fragment: last element of @fragments[] is the __symbols__ node
67 * @cset: changeset to apply fragments to live device tree
68 */
69struct overlay_changeset {
70 int id;
71 struct list_head ovcs_list;
72 const void *new_fdt;
73 const void *overlay_mem;
74 struct device_node *overlay_root;
75 enum of_overlay_notify_action notify_state;
76 int count;
77 struct fragment *fragments;
78 bool symbols_fragment;
79 struct of_changeset cset;
80};
81
82/* flags are sticky - once set, do not reset */
83static int devicetree_state_flags;
84#define DTSF_APPLY_FAIL 0x01
85#define DTSF_REVERT_FAIL 0x02
86
87/*
88 * If a changeset apply or revert encounters an error, an attempt will
89 * be made to undo partial changes, but may fail. If the undo fails
90 * we do not know the state of the devicetree.
91 */
92static int devicetree_corrupt(void)
93{
94 return devicetree_state_flags &
95 (DTSF_APPLY_FAIL | DTSF_REVERT_FAIL);
96}
97
98static int build_changeset_next_level(struct overlay_changeset *ovcs,
99 struct target *target, const struct device_node *overlay_node);
100
101/*
102 * of_resolve_phandles() finds the largest phandle in the live tree.
103 * of_overlay_apply() may add a larger phandle to the live tree.
104 * Do not allow race between two overlays being applied simultaneously:
105 * mutex_lock(&of_overlay_phandle_mutex)
106 * of_resolve_phandles()
107 * of_overlay_apply()
108 * mutex_unlock(&of_overlay_phandle_mutex)
109 */
110static DEFINE_MUTEX(of_overlay_phandle_mutex);
111
112void of_overlay_mutex_lock(void)
113{
114 mutex_lock(&of_overlay_phandle_mutex);
115}
116
117void of_overlay_mutex_unlock(void)
118{
119 mutex_unlock(&of_overlay_phandle_mutex);
120}
121
122static LIST_HEAD(ovcs_list);
123static DEFINE_IDR(ovcs_idr);
124
125static BLOCKING_NOTIFIER_HEAD(overlay_notify_chain);
126
127/**
128 * of_overlay_notifier_register() - Register notifier for overlay operations
129 * @nb: Notifier block to register
130 *
131 * Register for notification on overlay operations on device tree nodes. The
132 * reported actions definied by @of_reconfig_change. The notifier callback
133 * furthermore receives a pointer to the affected device tree node.
134 *
135 * Note that a notifier callback is not supposed to store pointers to a device
136 * tree node or its content beyond @OF_OVERLAY_POST_REMOVE corresponding to the
137 * respective node it received.
138 */
139int of_overlay_notifier_register(struct notifier_block *nb)
140{
141 return blocking_notifier_chain_register(&overlay_notify_chain, nb);
142}
143EXPORT_SYMBOL_GPL(of_overlay_notifier_register);
144
145/**
146 * of_overlay_notifier_unregister() - Unregister notifier for overlay operations
147 * @nb: Notifier block to unregister
148 */
149int of_overlay_notifier_unregister(struct notifier_block *nb)
150{
151 return blocking_notifier_chain_unregister(&overlay_notify_chain, nb);
152}
153EXPORT_SYMBOL_GPL(of_overlay_notifier_unregister);
154
155static int overlay_notify(struct overlay_changeset *ovcs,
156 enum of_overlay_notify_action action)
157{
158 struct of_overlay_notify_data nd;
159 int i, ret;
160
161 ovcs->notify_state = action;
162
163 for (i = 0; i < ovcs->count; i++) {
164 struct fragment *fragment = &ovcs->fragments[i];
165
166 nd.target = fragment->target;
167 nd.overlay = fragment->overlay;
168
169 ret = blocking_notifier_call_chain(&overlay_notify_chain,
170 action, &nd);
171 if (notifier_to_errno(ret)) {
172 ret = notifier_to_errno(ret);
173 pr_err("overlay changeset %s notifier error %d, target: %pOF\n",
174 of_overlay_action_name(action), ret, nd.target);
175 return ret;
176 }
177 }
178
179 return 0;
180}
181
182/*
183 * The values of properties in the "/__symbols__" node are paths in
184 * the ovcs->overlay_root. When duplicating the properties, the paths
185 * need to be adjusted to be the correct path for the live device tree.
186 *
187 * The paths refer to a node in the subtree of a fragment node's "__overlay__"
188 * node, for example "/fragment@0/__overlay__/symbol_path_tail",
189 * where symbol_path_tail can be a single node or it may be a multi-node path.
190 *
191 * The duplicated property value will be modified by replacing the
192 * "/fragment_name/__overlay/" portion of the value with the target
193 * path from the fragment node.
194 */
195static struct property *dup_and_fixup_symbol_prop(
196 struct overlay_changeset *ovcs, const struct property *prop)
197{
198 struct fragment *fragment;
199 struct property *new_prop;
200 struct device_node *fragment_node;
201 struct device_node *overlay_node;
202 const char *path;
203 const char *path_tail;
204 const char *target_path;
205 int k;
206 int overlay_name_len;
207 int path_len;
208 int path_tail_len;
209 int target_path_len;
210
211 if (!prop->value)
212 return NULL;
213 if (strnlen(prop->value, prop->length) >= prop->length)
214 return NULL;
215 path = prop->value;
216 path_len = strlen(path);
217
218 if (path_len < 1)
219 return NULL;
220 fragment_node = __of_find_node_by_path(ovcs->overlay_root, path + 1);
221 overlay_node = __of_find_node_by_path(fragment_node, "__overlay__/");
222 of_node_put(fragment_node);
223 of_node_put(overlay_node);
224
225 for (k = 0; k < ovcs->count; k++) {
226 fragment = &ovcs->fragments[k];
227 if (fragment->overlay == overlay_node)
228 break;
229 }
230 if (k >= ovcs->count)
231 return NULL;
232
233 overlay_name_len = snprintf(NULL, 0, "%pOF", fragment->overlay);
234
235 if (overlay_name_len > path_len)
236 return NULL;
237 path_tail = path + overlay_name_len;
238 path_tail_len = strlen(path_tail);
239
240 target_path = kasprintf(GFP_KERNEL, "%pOF", fragment->target);
241 if (!target_path)
242 return NULL;
243 target_path_len = strlen(target_path);
244
245 new_prop = kzalloc(sizeof(*new_prop), GFP_KERNEL);
246 if (!new_prop)
247 goto err_free_target_path;
248
249 new_prop->name = kstrdup(prop->name, GFP_KERNEL);
250 new_prop->length = target_path_len + path_tail_len + 1;
251 new_prop->value = kzalloc(new_prop->length, GFP_KERNEL);
252 if (!new_prop->name || !new_prop->value)
253 goto err_free_new_prop;
254
255 strcpy(new_prop->value, target_path);
256 strcpy(new_prop->value + target_path_len, path_tail);
257
258 of_property_set_flag(new_prop, OF_DYNAMIC);
259
260 kfree(target_path);
261
262 return new_prop;
263
264err_free_new_prop:
265 kfree(new_prop->name);
266 kfree(new_prop->value);
267 kfree(new_prop);
268err_free_target_path:
269 kfree(target_path);
270
271 return NULL;
272}
273
274/**
275 * add_changeset_property() - add @overlay_prop to overlay changeset
276 * @ovcs: overlay changeset
277 * @target: where @overlay_prop will be placed
278 * @overlay_prop: property to add or update, from overlay tree
279 * @is_symbols_prop: 1 if @overlay_prop is from node "/__symbols__"
280 *
281 * If @overlay_prop does not already exist in live devicetree, add changeset
282 * entry to add @overlay_prop in @target, else add changeset entry to update
283 * value of @overlay_prop.
284 *
285 * @target may be either in the live devicetree or in a new subtree that
286 * is contained in the changeset.
287 *
288 * Some special properties are not added or updated (no error returned):
289 * "name", "phandle", "linux,phandle".
290 *
291 * Properties "#address-cells" and "#size-cells" are not updated if they
292 * are already in the live tree, but if present in the live tree, the values
293 * in the overlay must match the values in the live tree.
294 *
295 * Update of property in symbols node is not allowed.
296 *
297 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
298 * invalid @overlay.
299 */
300static int add_changeset_property(struct overlay_changeset *ovcs,
301 struct target *target, struct property *overlay_prop,
302 bool is_symbols_prop)
303{
304 struct property *new_prop = NULL, *prop;
305 int ret = 0;
306
307 if (target->in_livetree)
308 if (!of_prop_cmp(overlay_prop->name, "name") ||
309 !of_prop_cmp(overlay_prop->name, "phandle") ||
310 !of_prop_cmp(overlay_prop->name, "linux,phandle"))
311 return 0;
312
313 if (target->in_livetree)
314 prop = of_find_property(target->np, overlay_prop->name, NULL);
315 else
316 prop = NULL;
317
318 if (prop) {
319 if (!of_prop_cmp(prop->name, "#address-cells")) {
320 if (!of_prop_val_eq(prop, overlay_prop)) {
321 pr_err("ERROR: changing value of #address-cells is not allowed in %pOF\n",
322 target->np);
323 ret = -EINVAL;
324 }
325 return ret;
326
327 } else if (!of_prop_cmp(prop->name, "#size-cells")) {
328 if (!of_prop_val_eq(prop, overlay_prop)) {
329 pr_err("ERROR: changing value of #size-cells is not allowed in %pOF\n",
330 target->np);
331 ret = -EINVAL;
332 }
333 return ret;
334 }
335 }
336
337 if (is_symbols_prop) {
338 if (prop)
339 return -EINVAL;
340 new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
341 } else {
342 new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
343 }
344
345 if (!new_prop)
346 return -ENOMEM;
347
348 if (!prop) {
349 if (!target->in_livetree) {
350 new_prop->next = target->np->deadprops;
351 target->np->deadprops = new_prop;
352 }
353 ret = of_changeset_add_property(&ovcs->cset, target->np,
354 new_prop);
355 } else {
356 ret = of_changeset_update_property(&ovcs->cset, target->np,
357 new_prop);
358 }
359
360 if (!of_node_check_flag(target->np, OF_OVERLAY))
361 pr_err("WARNING: memory leak will occur if overlay removed, property: %pOF/%s\n",
362 target->np, new_prop->name);
363
364 if (ret) {
365 kfree(new_prop->name);
366 kfree(new_prop->value);
367 kfree(new_prop);
368 }
369 return ret;
370}
371
372/**
373 * add_changeset_node() - add @node (and children) to overlay changeset
374 * @ovcs: overlay changeset
375 * @target: where @node will be placed in live tree or changeset
376 * @node: node from within overlay device tree fragment
377 *
378 * If @node does not already exist in @target, add changeset entry
379 * to add @node in @target.
380 *
381 * If @node already exists in @target, and the existing node has
382 * a phandle, the overlay node is not allowed to have a phandle.
383 *
384 * If @node has child nodes, add the children recursively via
385 * build_changeset_next_level().
386 *
387 * NOTE_1: A live devicetree created from a flattened device tree (FDT) will
388 * not contain the full path in node->full_name. Thus an overlay
389 * created from an FDT also will not contain the full path in
390 * node->full_name. However, a live devicetree created from Open
391 * Firmware may have the full path in node->full_name.
392 *
393 * add_changeset_node() follows the FDT convention and does not include
394 * the full path in node->full_name. Even though it expects the overlay
395 * to not contain the full path, it uses kbasename() to remove the
396 * full path should it exist. It also uses kbasename() in comparisons
397 * to nodes in the live devicetree so that it can apply an overlay to
398 * a live devicetree created from Open Firmware.
399 *
400 * NOTE_2: Multiple mods of created nodes not supported.
401 *
402 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
403 * invalid @overlay.
404 */
405static int add_changeset_node(struct overlay_changeset *ovcs,
406 struct target *target, struct device_node *node)
407{
408 const char *node_kbasename;
409 const __be32 *phandle;
410 struct device_node *tchild;
411 struct target target_child;
412 int ret = 0, size;
413
414 node_kbasename = kbasename(node->full_name);
415
416 for_each_child_of_node(target->np, tchild)
417 if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name)))
418 break;
419
420 if (!tchild) {
421 tchild = __of_node_dup(NULL, node_kbasename);
422 if (!tchild)
423 return -ENOMEM;
424
425 tchild->parent = target->np;
426 tchild->name = __of_get_property(node, "name", NULL);
427
428 if (!tchild->name)
429 tchild->name = "<NULL>";
430
431 /* ignore obsolete "linux,phandle" */
432 phandle = __of_get_property(node, "phandle", &size);
433 if (phandle && (size == 4))
434 tchild->phandle = be32_to_cpup(phandle);
435
436 of_node_set_flag(tchild, OF_OVERLAY);
437
438 ret = of_changeset_attach_node(&ovcs->cset, tchild);
439 if (ret)
440 return ret;
441
442 target_child.np = tchild;
443 target_child.in_livetree = false;
444
445 ret = build_changeset_next_level(ovcs, &target_child, node);
446 of_node_put(tchild);
447 return ret;
448 }
449
450 if (node->phandle && tchild->phandle) {
451 ret = -EINVAL;
452 } else {
453 target_child.np = tchild;
454 target_child.in_livetree = target->in_livetree;
455 ret = build_changeset_next_level(ovcs, &target_child, node);
456 }
457 of_node_put(tchild);
458
459 return ret;
460}
461
462/**
463 * build_changeset_next_level() - add level of overlay changeset
464 * @ovcs: overlay changeset
465 * @target: where to place @overlay_node in live tree
466 * @overlay_node: node from within an overlay device tree fragment
467 *
468 * Add the properties (if any) and nodes (if any) from @overlay_node to the
469 * @ovcs->cset changeset. If an added node has child nodes, they will
470 * be added recursively.
471 *
472 * Do not allow symbols node to have any children.
473 *
474 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
475 * invalid @overlay_node.
476 */
477static int build_changeset_next_level(struct overlay_changeset *ovcs,
478 struct target *target, const struct device_node *overlay_node)
479{
480 struct device_node *child;
481 struct property *prop;
482 int ret;
483
484 for_each_property_of_node(overlay_node, prop) {
485 ret = add_changeset_property(ovcs, target, prop, 0);
486 if (ret) {
487 pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
488 target->np, prop->name, ret);
489 return ret;
490 }
491 }
492
493 for_each_child_of_node(overlay_node, child) {
494 ret = add_changeset_node(ovcs, target, child);
495 if (ret) {
496 pr_debug("Failed to apply node @%pOF/%pOFn, err=%d\n",
497 target->np, child, ret);
498 of_node_put(child);
499 return ret;
500 }
501 }
502
503 return 0;
504}
505
506/*
507 * Add the properties from __overlay__ node to the @ovcs->cset changeset.
508 */
509static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
510 struct target *target,
511 const struct device_node *overlay_symbols_node)
512{
513 struct property *prop;
514 int ret;
515
516 for_each_property_of_node(overlay_symbols_node, prop) {
517 ret = add_changeset_property(ovcs, target, prop, 1);
518 if (ret) {
519 pr_debug("Failed to apply symbols prop @%pOF/%s, err=%d\n",
520 target->np, prop->name, ret);
521 return ret;
522 }
523 }
524
525 return 0;
526}
527
528static int find_dup_cset_node_entry(struct overlay_changeset *ovcs,
529 struct of_changeset_entry *ce_1)
530{
531 struct of_changeset_entry *ce_2;
532 char *fn_1, *fn_2;
533 int node_path_match;
534
535 if (ce_1->action != OF_RECONFIG_ATTACH_NODE &&
536 ce_1->action != OF_RECONFIG_DETACH_NODE)
537 return 0;
538
539 ce_2 = ce_1;
540 list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
541 if ((ce_2->action != OF_RECONFIG_ATTACH_NODE &&
542 ce_2->action != OF_RECONFIG_DETACH_NODE) ||
543 of_node_cmp(ce_1->np->full_name, ce_2->np->full_name))
544 continue;
545
546 fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
547 fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
548 node_path_match = !fn_1 || !fn_2 || !strcmp(fn_1, fn_2);
549 kfree(fn_1);
550 kfree(fn_2);
551 if (node_path_match) {
552 pr_err("ERROR: multiple fragments add and/or delete node %pOF\n",
553 ce_1->np);
554 return -EINVAL;
555 }
556 }
557
558 return 0;
559}
560
561static int find_dup_cset_prop(struct overlay_changeset *ovcs,
562 struct of_changeset_entry *ce_1)
563{
564 struct of_changeset_entry *ce_2;
565 char *fn_1, *fn_2;
566 int node_path_match;
567
568 if (ce_1->action != OF_RECONFIG_ADD_PROPERTY &&
569 ce_1->action != OF_RECONFIG_REMOVE_PROPERTY &&
570 ce_1->action != OF_RECONFIG_UPDATE_PROPERTY)
571 return 0;
572
573 ce_2 = ce_1;
574 list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
575 if ((ce_2->action != OF_RECONFIG_ADD_PROPERTY &&
576 ce_2->action != OF_RECONFIG_REMOVE_PROPERTY &&
577 ce_2->action != OF_RECONFIG_UPDATE_PROPERTY) ||
578 of_node_cmp(ce_1->np->full_name, ce_2->np->full_name))
579 continue;
580
581 fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
582 fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
583 node_path_match = !fn_1 || !fn_2 || !strcmp(fn_1, fn_2);
584 kfree(fn_1);
585 kfree(fn_2);
586 if (node_path_match &&
587 !of_prop_cmp(ce_1->prop->name, ce_2->prop->name)) {
588 pr_err("ERROR: multiple fragments add, update, and/or delete property %pOF/%s\n",
589 ce_1->np, ce_1->prop->name);
590 return -EINVAL;
591 }
592 }
593
594 return 0;
595}
596
597/**
598 * changeset_dup_entry_check() - check for duplicate entries
599 * @ovcs: Overlay changeset
600 *
601 * Check changeset @ovcs->cset for multiple {add or delete} node entries for
602 * the same node or duplicate {add, delete, or update} properties entries
603 * for the same property.
604 *
605 * Return: 0 on success, or -EINVAL if duplicate changeset entry found.
606 */
607static int changeset_dup_entry_check(struct overlay_changeset *ovcs)
608{
609 struct of_changeset_entry *ce_1;
610 int dup_entry = 0;
611
612 list_for_each_entry(ce_1, &ovcs->cset.entries, node) {
613 dup_entry |= find_dup_cset_node_entry(ovcs, ce_1);
614 dup_entry |= find_dup_cset_prop(ovcs, ce_1);
615 }
616
617 return dup_entry ? -EINVAL : 0;
618}
619
620/**
621 * build_changeset() - populate overlay changeset in @ovcs from @ovcs->fragments
622 * @ovcs: Overlay changeset
623 *
624 * Create changeset @ovcs->cset to contain the nodes and properties of the
625 * overlay device tree fragments in @ovcs->fragments[]. If an error occurs,
626 * any portions of the changeset that were successfully created will remain
627 * in @ovcs->cset.
628 *
629 * Return: 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
630 * invalid overlay in @ovcs->fragments[].
631 */
632static int build_changeset(struct overlay_changeset *ovcs)
633{
634 struct fragment *fragment;
635 struct target target;
636 int fragments_count, i, ret;
637
638 /*
639 * if there is a symbols fragment in ovcs->fragments[i] it is
640 * the final element in the array
641 */
642 if (ovcs->symbols_fragment)
643 fragments_count = ovcs->count - 1;
644 else
645 fragments_count = ovcs->count;
646
647 for (i = 0; i < fragments_count; i++) {
648 fragment = &ovcs->fragments[i];
649
650 target.np = fragment->target;
651 target.in_livetree = true;
652 ret = build_changeset_next_level(ovcs, &target,
653 fragment->overlay);
654 if (ret) {
655 pr_debug("fragment apply failed '%pOF'\n",
656 fragment->target);
657 return ret;
658 }
659 }
660
661 if (ovcs->symbols_fragment) {
662 fragment = &ovcs->fragments[ovcs->count - 1];
663
664 target.np = fragment->target;
665 target.in_livetree = true;
666 ret = build_changeset_symbols_node(ovcs, &target,
667 fragment->overlay);
668 if (ret) {
669 pr_debug("symbols fragment apply failed '%pOF'\n",
670 fragment->target);
671 return ret;
672 }
673 }
674
675 return changeset_dup_entry_check(ovcs);
676}
677
678/*
679 * Find the target node using a number of different strategies
680 * in order of preference:
681 *
682 * 1) "target" property containing the phandle of the target
683 * 2) "target-path" property containing the path of the target
684 */
685static struct device_node *find_target(struct device_node *info_node,
686 struct device_node *target_base)
687{
688 struct device_node *node;
689 char *target_path;
690 const char *path;
691 u32 val;
692 int ret;
693
694 ret = of_property_read_u32(info_node, "target", &val);
695 if (!ret) {
696 node = of_find_node_by_phandle(val);
697 if (!node)
698 pr_err("find target, node: %pOF, phandle 0x%x not found\n",
699 info_node, val);
700 return node;
701 }
702
703 ret = of_property_read_string(info_node, "target-path", &path);
704 if (!ret) {
705 if (target_base) {
706 target_path = kasprintf(GFP_KERNEL, "%pOF%s", target_base, path);
707 if (!target_path)
708 return NULL;
709 node = of_find_node_by_path(target_path);
710 if (!node) {
711 pr_err("find target, node: %pOF, path '%s' not found\n",
712 info_node, target_path);
713 }
714 kfree(target_path);
715 } else {
716 node = of_find_node_by_path(path);
717 if (!node) {
718 pr_err("find target, node: %pOF, path '%s' not found\n",
719 info_node, path);
720 }
721 }
722 return node;
723 }
724
725 pr_err("find target, node: %pOF, no target property\n", info_node);
726
727 return NULL;
728}
729
730/**
731 * init_overlay_changeset() - initialize overlay changeset from overlay tree
732 * @ovcs: Overlay changeset to build
733 * @target_base: Point to the target node to apply overlay
734 *
735 * Initialize @ovcs. Populate @ovcs->fragments with node information from
736 * the top level of @overlay_root. The relevant top level nodes are the
737 * fragment nodes and the __symbols__ node. Any other top level node will
738 * be ignored. Populate other @ovcs fields.
739 *
740 * Return: 0 on success, -ENOMEM if memory allocation failure, -EINVAL if error
741 * detected in @overlay_root. On error return, the caller of
742 * init_overlay_changeset() must call free_overlay_changeset().
743 */
744static int init_overlay_changeset(struct overlay_changeset *ovcs,
745 struct device_node *target_base)
746{
747 struct device_node *node, *overlay_node;
748 struct fragment *fragment;
749 struct fragment *fragments;
750 int cnt, ret;
751
752 /*
753 * None of the resources allocated by this function will be freed in
754 * the error paths. Instead the caller of this function is required
755 * to call free_overlay_changeset() (which will free the resources)
756 * if error return.
757 */
758
759 /*
760 * Warn for some issues. Can not return -EINVAL for these until
761 * of_unittest_apply_overlay() is fixed to pass these checks.
762 */
763 if (!of_node_check_flag(ovcs->overlay_root, OF_DYNAMIC))
764 pr_debug("%s() ovcs->overlay_root is not dynamic\n", __func__);
765
766 if (!of_node_check_flag(ovcs->overlay_root, OF_DETACHED))
767 pr_debug("%s() ovcs->overlay_root is not detached\n", __func__);
768
769 if (!of_node_is_root(ovcs->overlay_root))
770 pr_debug("%s() ovcs->overlay_root is not root\n", __func__);
771
772 cnt = 0;
773
774 /* fragment nodes */
775 for_each_child_of_node(ovcs->overlay_root, node) {
776 overlay_node = of_get_child_by_name(node, "__overlay__");
777 if (overlay_node) {
778 cnt++;
779 of_node_put(overlay_node);
780 }
781 }
782
783 node = of_get_child_by_name(ovcs->overlay_root, "__symbols__");
784 if (node) {
785 cnt++;
786 of_node_put(node);
787 }
788
789 fragments = kcalloc(cnt, sizeof(*fragments), GFP_KERNEL);
790 if (!fragments) {
791 ret = -ENOMEM;
792 goto err_out;
793 }
794 ovcs->fragments = fragments;
795
796 cnt = 0;
797 for_each_child_of_node(ovcs->overlay_root, node) {
798 overlay_node = of_get_child_by_name(node, "__overlay__");
799 if (!overlay_node)
800 continue;
801
802 fragment = &fragments[cnt];
803 fragment->overlay = overlay_node;
804 fragment->target = find_target(node, target_base);
805 if (!fragment->target) {
806 of_node_put(fragment->overlay);
807 ret = -EINVAL;
808 of_node_put(node);
809 goto err_out;
810 }
811
812 cnt++;
813 }
814
815 /*
816 * if there is a symbols fragment in ovcs->fragments[i] it is
817 * the final element in the array
818 */
819 node = of_get_child_by_name(ovcs->overlay_root, "__symbols__");
820 if (node) {
821 ovcs->symbols_fragment = 1;
822 fragment = &fragments[cnt];
823 fragment->overlay = node;
824 fragment->target = of_find_node_by_path("/__symbols__");
825
826 if (!fragment->target) {
827 pr_err("symbols in overlay, but not in live tree\n");
828 ret = -EINVAL;
829 of_node_put(node);
830 goto err_out;
831 }
832
833 cnt++;
834 }
835
836 if (!cnt) {
837 pr_err("no fragments or symbols in overlay\n");
838 ret = -EINVAL;
839 goto err_out;
840 }
841
842 ovcs->count = cnt;
843
844 return 0;
845
846err_out:
847 pr_err("%s() failed, ret = %d\n", __func__, ret);
848
849 return ret;
850}
851
852static void free_overlay_changeset(struct overlay_changeset *ovcs)
853{
854 int i;
855
856 if (ovcs->cset.entries.next)
857 of_changeset_destroy(&ovcs->cset);
858
859 if (ovcs->id) {
860 idr_remove(&ovcs_idr, ovcs->id);
861 list_del(&ovcs->ovcs_list);
862 ovcs->id = 0;
863 }
864
865
866 for (i = 0; i < ovcs->count; i++) {
867 of_node_put(ovcs->fragments[i].target);
868 of_node_put(ovcs->fragments[i].overlay);
869 }
870 kfree(ovcs->fragments);
871
872 /*
873 * There should be no live pointers into ovcs->overlay_mem and
874 * ovcs->new_fdt due to the policy that overlay notifiers are not
875 * allowed to retain pointers into the overlay devicetree other
876 * than during the window from OF_OVERLAY_PRE_APPLY overlay
877 * notifiers until the OF_OVERLAY_POST_REMOVE overlay notifiers.
878 *
879 * A memory leak will occur here if within the window.
880 */
881
882 if (ovcs->notify_state == OF_OVERLAY_INIT ||
883 ovcs->notify_state == OF_OVERLAY_POST_REMOVE) {
884 kfree(ovcs->overlay_mem);
885 kfree(ovcs->new_fdt);
886 }
887 kfree(ovcs);
888}
889
890/*
891 * internal documentation
892 *
893 * of_overlay_apply() - Create and apply an overlay changeset
894 * @ovcs: overlay changeset
895 * @base: point to the target node to apply overlay
896 *
897 * Creates and applies an overlay changeset.
898 *
899 * If an error is returned by an overlay changeset pre-apply notifier
900 * then no further overlay changeset pre-apply notifier will be called.
901 *
902 * If an error is returned by an overlay changeset post-apply notifier
903 * then no further overlay changeset post-apply notifier will be called.
904 *
905 * If more than one notifier returns an error, then the last notifier
906 * error to occur is returned.
907 *
908 * If an error occurred while applying the overlay changeset, then an
909 * attempt is made to revert any changes that were made to the
910 * device tree. If there were any errors during the revert attempt
911 * then the state of the device tree can not be determined, and any
912 * following attempt to apply or remove an overlay changeset will be
913 * refused.
914 *
915 * Returns 0 on success, or a negative error number. On error return,
916 * the caller of of_overlay_apply() must call free_overlay_changeset().
917 */
918
919static int of_overlay_apply(struct overlay_changeset *ovcs,
920 struct device_node *base)
921{
922 int ret = 0, ret_revert, ret_tmp;
923
924 ret = of_resolve_phandles(ovcs->overlay_root);
925 if (ret)
926 goto out;
927
928 ret = init_overlay_changeset(ovcs, base);
929 if (ret)
930 goto out;
931
932 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
933 if (ret)
934 goto out;
935
936 ret = build_changeset(ovcs);
937 if (ret)
938 goto out;
939
940 ret_revert = 0;
941 ret = __of_changeset_apply_entries(&ovcs->cset, &ret_revert);
942 if (ret) {
943 if (ret_revert) {
944 pr_debug("overlay changeset revert error %d\n",
945 ret_revert);
946 devicetree_state_flags |= DTSF_APPLY_FAIL;
947 }
948 goto out;
949 }
950
951 ret = __of_changeset_apply_notify(&ovcs->cset);
952 if (ret)
953 pr_err("overlay apply changeset entry notify error %d\n", ret);
954 /* notify failure is not fatal, continue */
955
956 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY);
957 if (ret_tmp)
958 if (!ret)
959 ret = ret_tmp;
960
961out:
962 pr_debug("%s() err=%d\n", __func__, ret);
963
964 return ret;
965}
966
967/**
968 * of_overlay_fdt_apply() - Create and apply an overlay changeset
969 * @overlay_fdt: pointer to overlay FDT
970 * @overlay_fdt_size: number of bytes in @overlay_fdt
971 * @ret_ovcs_id: pointer for returning created changeset id
972 * @base: pointer for the target node to apply overlay
973 *
974 * Creates and applies an overlay changeset.
975 *
976 * See of_overlay_apply() for important behavior information.
977 *
978 * Return: 0 on success, or a negative error number. *@ret_ovcs_id is set to
979 * the value of overlay changeset id, which can be passed to of_overlay_remove()
980 * to remove the overlay.
981 *
982 * On error return, the changeset may be partially applied. This is especially
983 * likely if an OF_OVERLAY_POST_APPLY notifier returns an error. In this case
984 * the caller should call of_overlay_remove() with the value in *@ret_ovcs_id.
985 */
986
987int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
988 int *ret_ovcs_id, struct device_node *base)
989{
990 void *new_fdt;
991 void *new_fdt_align;
992 void *overlay_mem;
993 int ret;
994 u32 size;
995 struct overlay_changeset *ovcs;
996
997 *ret_ovcs_id = 0;
998
999 if (devicetree_corrupt()) {
1000 pr_err("devicetree state suspect, refuse to apply overlay\n");
1001 return -EBUSY;
1002 }
1003
1004 if (overlay_fdt_size < sizeof(struct fdt_header) ||
1005 fdt_check_header(overlay_fdt)) {
1006 pr_err("Invalid overlay_fdt header\n");
1007 return -EINVAL;
1008 }
1009
1010 size = fdt_totalsize(overlay_fdt);
1011 if (overlay_fdt_size < size)
1012 return -EINVAL;
1013
1014 ovcs = kzalloc(sizeof(*ovcs), GFP_KERNEL);
1015 if (!ovcs)
1016 return -ENOMEM;
1017
1018 of_overlay_mutex_lock();
1019 mutex_lock(&of_mutex);
1020
1021 /*
1022 * ovcs->notify_state must be set to OF_OVERLAY_INIT before allocating
1023 * ovcs resources, implicitly set by kzalloc() of ovcs
1024 */
1025
1026 ovcs->id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL);
1027 if (ovcs->id <= 0) {
1028 ret = ovcs->id;
1029 goto err_free_ovcs;
1030 }
1031
1032 INIT_LIST_HEAD(&ovcs->ovcs_list);
1033 list_add_tail(&ovcs->ovcs_list, &ovcs_list);
1034 of_changeset_init(&ovcs->cset);
1035
1036 /*
1037 * Must create permanent copy of FDT because of_fdt_unflatten_tree()
1038 * will create pointers to the passed in FDT in the unflattened tree.
1039 */
1040 new_fdt = kmalloc(size + FDT_ALIGN_SIZE, GFP_KERNEL);
1041 if (!new_fdt) {
1042 ret = -ENOMEM;
1043 goto err_free_ovcs;
1044 }
1045 ovcs->new_fdt = new_fdt;
1046
1047 new_fdt_align = PTR_ALIGN(new_fdt, FDT_ALIGN_SIZE);
1048 memcpy(new_fdt_align, overlay_fdt, size);
1049
1050 overlay_mem = of_fdt_unflatten_tree(new_fdt_align, NULL,
1051 &ovcs->overlay_root);
1052 if (!overlay_mem) {
1053 pr_err("unable to unflatten overlay_fdt\n");
1054 ret = -EINVAL;
1055 goto err_free_ovcs;
1056 }
1057 ovcs->overlay_mem = overlay_mem;
1058
1059 ret = of_overlay_apply(ovcs, base);
1060 /*
1061 * If of_overlay_apply() error, calling free_overlay_changeset() may
1062 * result in a memory leak if the apply partly succeeded, so do NOT
1063 * goto err_free_ovcs. Instead, the caller of of_overlay_fdt_apply()
1064 * can call of_overlay_remove();
1065 */
1066 *ret_ovcs_id = ovcs->id;
1067 goto out_unlock;
1068
1069err_free_ovcs:
1070 free_overlay_changeset(ovcs);
1071
1072out_unlock:
1073 mutex_unlock(&of_mutex);
1074 of_overlay_mutex_unlock();
1075 return ret;
1076}
1077EXPORT_SYMBOL_GPL(of_overlay_fdt_apply);
1078
1079/*
1080 * Find @np in @tree.
1081 *
1082 * Returns 1 if @np is @tree or is contained in @tree, else 0
1083 */
1084static int find_node(struct device_node *tree, struct device_node *np)
1085{
1086 struct device_node *child;
1087
1088 if (tree == np)
1089 return 1;
1090
1091 for_each_child_of_node(tree, child) {
1092 if (find_node(child, np)) {
1093 of_node_put(child);
1094 return 1;
1095 }
1096 }
1097
1098 return 0;
1099}
1100
1101/*
1102 * Is @remove_ce_node a child of, a parent of, or the same as any
1103 * node in an overlay changeset more topmost than @remove_ovcs?
1104 *
1105 * Returns 1 if found, else 0
1106 */
1107static int node_overlaps_later_cs(struct overlay_changeset *remove_ovcs,
1108 struct device_node *remove_ce_node)
1109{
1110 struct overlay_changeset *ovcs;
1111 struct of_changeset_entry *ce;
1112
1113 list_for_each_entry_reverse(ovcs, &ovcs_list, ovcs_list) {
1114 if (ovcs == remove_ovcs)
1115 break;
1116
1117 list_for_each_entry(ce, &ovcs->cset.entries, node) {
1118 if (find_node(ce->np, remove_ce_node)) {
1119 pr_err("%s: #%d overlaps with #%d @%pOF\n",
1120 __func__, remove_ovcs->id, ovcs->id,
1121 remove_ce_node);
1122 return 1;
1123 }
1124 if (find_node(remove_ce_node, ce->np)) {
1125 pr_err("%s: #%d overlaps with #%d @%pOF\n",
1126 __func__, remove_ovcs->id, ovcs->id,
1127 remove_ce_node);
1128 return 1;
1129 }
1130 }
1131 }
1132
1133 return 0;
1134}
1135
1136/*
1137 * We can safely remove the overlay only if it's the top-most one.
1138 * Newly applied overlays are inserted at the tail of the overlay list,
1139 * so a top most overlay is the one that is closest to the tail.
1140 *
1141 * The topmost check is done by exploiting this property. For each
1142 * affected device node in the log list we check if this overlay is
1143 * the one closest to the tail. If another overlay has affected this
1144 * device node and is closest to the tail, then removal is not permitted.
1145 */
1146static int overlay_removal_is_ok(struct overlay_changeset *remove_ovcs)
1147{
1148 struct of_changeset_entry *remove_ce;
1149
1150 list_for_each_entry(remove_ce, &remove_ovcs->cset.entries, node) {
1151 if (node_overlaps_later_cs(remove_ovcs, remove_ce->np)) {
1152 pr_err("overlay #%d is not topmost\n", remove_ovcs->id);
1153 return 0;
1154 }
1155 }
1156
1157 return 1;
1158}
1159
1160/**
1161 * of_overlay_remove() - Revert and free an overlay changeset
1162 * @ovcs_id: Pointer to overlay changeset id
1163 *
1164 * Removes an overlay if it is permissible. @ovcs_id was previously returned
1165 * by of_overlay_fdt_apply().
1166 *
1167 * If an error occurred while attempting to revert the overlay changeset,
1168 * then an attempt is made to re-apply any changeset entry that was
1169 * reverted. If an error occurs on re-apply then the state of the device
1170 * tree can not be determined, and any following attempt to apply or remove
1171 * an overlay changeset will be refused.
1172 *
1173 * A non-zero return value will not revert the changeset if error is from:
1174 * - parameter checks
1175 * - overlay changeset pre-remove notifier
1176 * - overlay changeset entry revert
1177 *
1178 * If an error is returned by an overlay changeset pre-remove notifier
1179 * then no further overlay changeset pre-remove notifier will be called.
1180 *
1181 * If more than one notifier returns an error, then the last notifier
1182 * error to occur is returned.
1183 *
1184 * A non-zero return value will revert the changeset if error is from:
1185 * - overlay changeset entry notifier
1186 * - overlay changeset post-remove notifier
1187 *
1188 * If an error is returned by an overlay changeset post-remove notifier
1189 * then no further overlay changeset post-remove notifier will be called.
1190 *
1191 * Return: 0 on success, or a negative error number. *@ovcs_id is set to
1192 * zero after reverting the changeset, even if a subsequent error occurs.
1193 */
1194int of_overlay_remove(int *ovcs_id)
1195{
1196 struct overlay_changeset *ovcs;
1197 int ret, ret_apply, ret_tmp;
1198
1199 if (devicetree_corrupt()) {
1200 pr_err("suspect devicetree state, refuse to remove overlay\n");
1201 ret = -EBUSY;
1202 goto out;
1203 }
1204
1205 mutex_lock(&of_mutex);
1206
1207 ovcs = idr_find(&ovcs_idr, *ovcs_id);
1208 if (!ovcs) {
1209 ret = -ENODEV;
1210 pr_err("remove: Could not find overlay #%d\n", *ovcs_id);
1211 goto err_unlock;
1212 }
1213
1214 if (!overlay_removal_is_ok(ovcs)) {
1215 ret = -EBUSY;
1216 goto err_unlock;
1217 }
1218
1219 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE);
1220 if (ret)
1221 goto err_unlock;
1222
1223 ret_apply = 0;
1224 ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
1225 if (ret) {
1226 if (ret_apply)
1227 devicetree_state_flags |= DTSF_REVERT_FAIL;
1228 goto err_unlock;
1229 }
1230
1231 ret = __of_changeset_revert_notify(&ovcs->cset);
1232 if (ret)
1233 pr_err("overlay remove changeset entry notify error %d\n", ret);
1234 /* notify failure is not fatal, continue */
1235
1236 *ovcs_id = 0;
1237
1238 /*
1239 * Note that the overlay memory will be kfree()ed by
1240 * free_overlay_changeset() even if the notifier for
1241 * OF_OVERLAY_POST_REMOVE returns an error.
1242 */
1243 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE);
1244 if (ret_tmp)
1245 if (!ret)
1246 ret = ret_tmp;
1247
1248 free_overlay_changeset(ovcs);
1249
1250err_unlock:
1251 /*
1252 * If jumped over free_overlay_changeset(), then did not kfree()
1253 * overlay related memory. This is a memory leak unless a subsequent
1254 * of_overlay_remove() of this overlay is successful.
1255 */
1256 mutex_unlock(&of_mutex);
1257
1258out:
1259 pr_debug("%s() err=%d\n", __func__, ret);
1260
1261 return ret;
1262}
1263EXPORT_SYMBOL_GPL(of_overlay_remove);
1264
1265/**
1266 * of_overlay_remove_all() - Reverts and frees all overlay changesets
1267 *
1268 * Removes all overlays from the system in the correct order.
1269 *
1270 * Return: 0 on success, or a negative error number
1271 */
1272int of_overlay_remove_all(void)
1273{
1274 struct overlay_changeset *ovcs, *ovcs_n;
1275 int ret;
1276
1277 /* the tail of list is guaranteed to be safe to remove */
1278 list_for_each_entry_safe_reverse(ovcs, ovcs_n, &ovcs_list, ovcs_list) {
1279 ret = of_overlay_remove(&ovcs->id);
1280 if (ret)
1281 return ret;
1282 }
1283
1284 return 0;
1285}
1286EXPORT_SYMBOL_GPL(of_overlay_remove_all);