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);
1284