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