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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Functions for working with device tree overlays
4 *
5 * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
6 * Copyright (C) 2012 Texas Instruments Inc.
7 */
8
9#define pr_fmt(fmt) "OF: overlay: " fmt
10
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/of.h>
14#include <linux/of_device.h>
15#include <linux/of_fdt.h>
16#include <linux/string.h>
17#include <linux/ctype.h>
18#include <linux/errno.h>
19#include <linux/slab.h>
20#include <linux/libfdt.h>
21#include <linux/err.h>
22#include <linux/idr.h>
23
24#include "of_private.h"
25
26/**
27 * struct target - info about current target node as recursing through overlay
28 * @np: node where current level of overlay will be applied
29 * @in_livetree: @np is a node in the live devicetree
30 *
31 * Used in the algorithm to create the portion of a changeset that describes
32 * an overlay fragment, which is a devicetree subtree. Initially @np is a node
33 * in the live devicetree where the overlay subtree is targeted to be grafted
34 * into. When recursing to the next level of the overlay subtree, the target
35 * also recurses to the next level of the live devicetree, as long as overlay
36 * subtree node also exists in the live devicetree. When a node in the overlay
37 * subtree does not exist at the same level in the live devicetree, target->np
38 * points to a newly allocated node, and all subsequent targets in the subtree
39 * will be newly allocated nodes.
40 */
41struct target {
42 struct device_node *np;
43 bool in_livetree;
44};
45
46/**
47 * struct fragment - info about fragment nodes in overlay expanded device tree
48 * @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 kfree(target_path);
265
266 return new_prop;
267
268err_free_new_prop:
269 kfree(new_prop->name);
270 kfree(new_prop->value);
271 kfree(new_prop);
272err_free_target_path:
273 kfree(target_path);
274
275 return NULL;
276}
277
278/**
279 * add_changeset_property() - add @overlay_prop to overlay changeset
280 * @ovcs: overlay changeset
281 * @target: where @overlay_prop will be placed
282 * @overlay_prop: property to add or update, from overlay tree
283 * @is_symbols_prop: 1 if @overlay_prop is from node "/__symbols__"
284 *
285 * If @overlay_prop does not already exist in live devicetree, add changeset
286 * entry to add @overlay_prop in @target, else add changeset entry to update
287 * value of @overlay_prop.
288 *
289 * @target may be either in the live devicetree or in a new subtree that
290 * is contained in the changeset.
291 *
292 * Some special properties are not added or updated (no error returned):
293 * "name", "phandle", "linux,phandle".
294 *
295 * Properties "#address-cells" and "#size-cells" are not updated if they
296 * are already in the live tree, but if present in the live tree, the values
297 * in the overlay must match the values in the live tree.
298 *
299 * Update of property in symbols node is not allowed.
300 *
301 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
302 * invalid @overlay.
303 */
304static int add_changeset_property(struct overlay_changeset *ovcs,
305 struct target *target, struct property *overlay_prop,
306 bool is_symbols_prop)
307{
308 struct property *new_prop = NULL, *prop;
309 int ret = 0;
310
311 if (target->in_livetree)
312 if (!of_prop_cmp(overlay_prop->name, "name") ||
313 !of_prop_cmp(overlay_prop->name, "phandle") ||
314 !of_prop_cmp(overlay_prop->name, "linux,phandle"))
315 return 0;
316
317 if (target->in_livetree)
318 prop = of_find_property(target->np, overlay_prop->name, NULL);
319 else
320 prop = NULL;
321
322 if (prop) {
323 if (!of_prop_cmp(prop->name, "#address-cells")) {
324 if (!of_prop_val_eq(prop, overlay_prop)) {
325 pr_err("ERROR: changing value of #address-cells is not allowed in %pOF\n",
326 target->np);
327 ret = -EINVAL;
328 }
329 return ret;
330
331 } else if (!of_prop_cmp(prop->name, "#size-cells")) {
332 if (!of_prop_val_eq(prop, overlay_prop)) {
333 pr_err("ERROR: changing value of #size-cells is not allowed in %pOF\n",
334 target->np);
335 ret = -EINVAL;
336 }
337 return ret;
338 }
339 }
340
341 if (is_symbols_prop) {
342 if (prop)
343 return -EINVAL;
344 new_prop = dup_and_fixup_symbol_prop(ovcs, overlay_prop);
345 } else {
346 new_prop = __of_prop_dup(overlay_prop, GFP_KERNEL);
347 }
348
349 if (!new_prop)
350 return -ENOMEM;
351
352 if (!prop) {
353 if (!target->in_livetree) {
354 new_prop->next = target->np->deadprops;
355 target->np->deadprops = new_prop;
356 }
357 ret = of_changeset_add_property(&ovcs->cset, target->np,
358 new_prop);
359 } else {
360 ret = of_changeset_update_property(&ovcs->cset, target->np,
361 new_prop);
362 }
363
364 if (!of_node_check_flag(target->np, OF_OVERLAY))
365 pr_err("WARNING: memory leak will occur if overlay removed, property: %pOF/%s\n",
366 target->np, new_prop->name);
367
368 if (ret) {
369 kfree(new_prop->name);
370 kfree(new_prop->value);
371 kfree(new_prop);
372 }
373 return ret;
374}
375
376/**
377 * add_changeset_node() - add @node (and children) to overlay changeset
378 * @ovcs: overlay changeset
379 * @target: where @node will be placed in live tree or changeset
380 * @node: node from within overlay device tree fragment
381 *
382 * If @node does not already exist in @target, add changeset entry
383 * to add @node in @target.
384 *
385 * If @node already exists in @target, and the existing node has
386 * a phandle, the overlay node is not allowed to have a phandle.
387 *
388 * If @node has child nodes, add the children recursively via
389 * build_changeset_next_level().
390 *
391 * NOTE_1: A live devicetree created from a flattened device tree (FDT) will
392 * not contain the full path in node->full_name. Thus an overlay
393 * created from an FDT also will not contain the full path in
394 * node->full_name. However, a live devicetree created from Open
395 * Firmware may have the full path in node->full_name.
396 *
397 * add_changeset_node() follows the FDT convention and does not include
398 * the full path in node->full_name. Even though it expects the overlay
399 * to not contain the full path, it uses kbasename() to remove the
400 * full path should it exist. It also uses kbasename() in comparisons
401 * to nodes in the live devicetree so that it can apply an overlay to
402 * a live devicetree created from Open Firmware.
403 *
404 * NOTE_2: Multiple mods of created nodes not supported.
405 *
406 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
407 * invalid @overlay.
408 */
409static int add_changeset_node(struct overlay_changeset *ovcs,
410 struct target *target, struct device_node *node)
411{
412 const char *node_kbasename;
413 const __be32 *phandle;
414 struct device_node *tchild;
415 struct target target_child;
416 int ret = 0, size;
417
418 node_kbasename = kbasename(node->full_name);
419
420 for_each_child_of_node(target->np, tchild)
421 if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name)))
422 break;
423
424 if (!tchild) {
425 tchild = __of_node_dup(NULL, node_kbasename);
426 if (!tchild)
427 return -ENOMEM;
428
429 tchild->parent = target->np;
430 tchild->name = __of_get_property(node, "name", NULL);
431
432 if (!tchild->name)
433 tchild->name = "<NULL>";
434
435 /* ignore obsolete "linux,phandle" */
436 phandle = __of_get_property(node, "phandle", &size);
437 if (phandle && (size == 4))
438 tchild->phandle = be32_to_cpup(phandle);
439
440 of_node_set_flag(tchild, OF_OVERLAY);
441
442 ret = of_changeset_attach_node(&ovcs->cset, tchild);
443 if (ret)
444 return ret;
445
446 target_child.np = tchild;
447 target_child.in_livetree = false;
448
449 ret = build_changeset_next_level(ovcs, &target_child, node);
450 of_node_put(tchild);
451 return ret;
452 }
453
454 if (node->phandle && tchild->phandle) {
455 ret = -EINVAL;
456 } else {
457 target_child.np = tchild;
458 target_child.in_livetree = target->in_livetree;
459 ret = build_changeset_next_level(ovcs, &target_child, node);
460 }
461 of_node_put(tchild);
462
463 return ret;
464}
465
466/**
467 * build_changeset_next_level() - add level of overlay changeset
468 * @ovcs: overlay changeset
469 * @target: where to place @overlay_node in live tree
470 * @overlay_node: node from within an overlay device tree fragment
471 *
472 * Add the properties (if any) and nodes (if any) from @overlay_node to the
473 * @ovcs->cset changeset. If an added node has child nodes, they will
474 * be added recursively.
475 *
476 * Do not allow symbols node to have any children.
477 *
478 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
479 * invalid @overlay_node.
480 */
481static int build_changeset_next_level(struct overlay_changeset *ovcs,
482 struct target *target, const struct device_node *overlay_node)
483{
484 struct device_node *child;
485 struct property *prop;
486 int ret;
487
488 for_each_property_of_node(overlay_node, prop) {
489 ret = add_changeset_property(ovcs, target, prop, 0);
490 if (ret) {
491 pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
492 target->np, prop->name, ret);
493 return ret;
494 }
495 }
496
497 for_each_child_of_node(overlay_node, child) {
498 ret = add_changeset_node(ovcs, target, child);
499 if (ret) {
500 pr_debug("Failed to apply node @%pOF/%pOFn, err=%d\n",
501 target->np, child, ret);
502 of_node_put(child);
503 return ret;
504 }
505 }
506
507 return 0;
508}
509
510/*
511 * Add the properties from __overlay__ node to the @ovcs->cset changeset.
512 */
513static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
514 struct target *target,
515 const struct device_node *overlay_symbols_node)
516{
517 struct property *prop;
518 int ret;
519
520 for_each_property_of_node(overlay_symbols_node, prop) {
521 ret = add_changeset_property(ovcs, target, prop, 1);
522 if (ret) {
523 pr_debug("Failed to apply symbols prop @%pOF/%s, err=%d\n",
524 target->np, prop->name, ret);
525 return ret;
526 }
527 }
528
529 return 0;
530}
531
532static int find_dup_cset_node_entry(struct overlay_changeset *ovcs,
533 struct of_changeset_entry *ce_1)
534{
535 struct of_changeset_entry *ce_2;
536 char *fn_1, *fn_2;
537 int node_path_match;
538
539 if (ce_1->action != OF_RECONFIG_ATTACH_NODE &&
540 ce_1->action != OF_RECONFIG_DETACH_NODE)
541 return 0;
542
543 ce_2 = ce_1;
544 list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
545 if ((ce_2->action != OF_RECONFIG_ATTACH_NODE &&
546 ce_2->action != OF_RECONFIG_DETACH_NODE) ||
547 of_node_cmp(ce_1->np->full_name, ce_2->np->full_name))
548 continue;
549
550 fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
551 fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
552 node_path_match = !strcmp(fn_1, fn_2);
553 kfree(fn_1);
554 kfree(fn_2);
555 if (node_path_match) {
556 pr_err("ERROR: multiple fragments add and/or delete node %pOF\n",
557 ce_1->np);
558 return -EINVAL;
559 }
560 }
561
562 return 0;
563}
564
565static int find_dup_cset_prop(struct overlay_changeset *ovcs,
566 struct of_changeset_entry *ce_1)
567{
568 struct of_changeset_entry *ce_2;
569 char *fn_1, *fn_2;
570 int node_path_match;
571
572 if (ce_1->action != OF_RECONFIG_ADD_PROPERTY &&
573 ce_1->action != OF_RECONFIG_REMOVE_PROPERTY &&
574 ce_1->action != OF_RECONFIG_UPDATE_PROPERTY)
575 return 0;
576
577 ce_2 = ce_1;
578 list_for_each_entry_continue(ce_2, &ovcs->cset.entries, node) {
579 if ((ce_2->action != OF_RECONFIG_ADD_PROPERTY &&
580 ce_2->action != OF_RECONFIG_REMOVE_PROPERTY &&
581 ce_2->action != OF_RECONFIG_UPDATE_PROPERTY) ||
582 of_node_cmp(ce_1->np->full_name, ce_2->np->full_name))
583 continue;
584
585 fn_1 = kasprintf(GFP_KERNEL, "%pOF", ce_1->np);
586 fn_2 = kasprintf(GFP_KERNEL, "%pOF", ce_2->np);
587 node_path_match = !strcmp(fn_1, fn_2);
588 kfree(fn_1);
589 kfree(fn_2);
590 if (node_path_match &&
591 !of_prop_cmp(ce_1->prop->name, ce_2->prop->name)) {
592 pr_err("ERROR: multiple fragments add, update, and/or delete property %pOF/%s\n",
593 ce_1->np, ce_1->prop->name);
594 return -EINVAL;
595 }
596 }
597
598 return 0;
599}
600
601/**
602 * changeset_dup_entry_check() - check for duplicate entries
603 * @ovcs: Overlay changeset
604 *
605 * Check changeset @ovcs->cset for multiple {add or delete} node entries for
606 * the same node or duplicate {add, delete, or update} properties entries
607 * for the same property.
608 *
609 * Returns 0 on success, or -EINVAL if duplicate changeset entry found.
610 */
611static int changeset_dup_entry_check(struct overlay_changeset *ovcs)
612{
613 struct of_changeset_entry *ce_1;
614 int dup_entry = 0;
615
616 list_for_each_entry(ce_1, &ovcs->cset.entries, node) {
617 dup_entry |= find_dup_cset_node_entry(ovcs, ce_1);
618 dup_entry |= find_dup_cset_prop(ovcs, ce_1);
619 }
620
621 return dup_entry ? -EINVAL : 0;
622}
623
624/**
625 * build_changeset() - populate overlay changeset in @ovcs from @ovcs->fragments
626 * @ovcs: Overlay changeset
627 *
628 * Create changeset @ovcs->cset to contain the nodes and properties of the
629 * overlay device tree fragments in @ovcs->fragments[]. If an error occurs,
630 * any portions of the changeset that were successfully created will remain
631 * in @ovcs->cset.
632 *
633 * Returns 0 on success, -ENOMEM if memory allocation failure, or -EINVAL if
634 * invalid overlay in @ovcs->fragments[].
635 */
636static int build_changeset(struct overlay_changeset *ovcs)
637{
638 struct fragment *fragment;
639 struct target target;
640 int fragments_count, i, ret;
641
642 /*
643 * if there is a symbols fragment in ovcs->fragments[i] it is
644 * the final element in the array
645 */
646 if (ovcs->symbols_fragment)
647 fragments_count = ovcs->count - 1;
648 else
649 fragments_count = ovcs->count;
650
651 for (i = 0; i < fragments_count; i++) {
652 fragment = &ovcs->fragments[i];
653
654 target.np = fragment->target;
655 target.in_livetree = true;
656 ret = build_changeset_next_level(ovcs, &target,
657 fragment->overlay);
658 if (ret) {
659 pr_debug("fragment apply failed '%pOF'\n",
660 fragment->target);
661 return ret;
662 }
663 }
664
665 if (ovcs->symbols_fragment) {
666 fragment = &ovcs->fragments[ovcs->count - 1];
667
668 target.np = fragment->target;
669 target.in_livetree = true;
670 ret = build_changeset_symbols_node(ovcs, &target,
671 fragment->overlay);
672 if (ret) {
673 pr_debug("symbols fragment apply failed '%pOF'\n",
674 fragment->target);
675 return ret;
676 }
677 }
678
679 return changeset_dup_entry_check(ovcs);
680}
681
682/*
683 * Find the target node using a number of different strategies
684 * in order of preference:
685 *
686 * 1) "target" property containing the phandle of the target
687 * 2) "target-path" property containing the path of the target
688 */
689static struct device_node *find_target(struct device_node *info_node)
690{
691 struct device_node *node;
692 const char *path;
693 u32 val;
694 int ret;
695
696 ret = of_property_read_u32(info_node, "target", &val);
697 if (!ret) {
698 node = of_find_node_by_phandle(val);
699 if (!node)
700 pr_err("find target, node: %pOF, phandle 0x%x not found\n",
701 info_node, val);
702 return node;
703 }
704
705 ret = of_property_read_string(info_node, "target-path", &path);
706 if (!ret) {
707 node = of_find_node_by_path(path);
708 if (!node)
709 pr_err("find target, node: %pOF, path '%s' not found\n",
710 info_node, path);
711 return node;
712 }
713
714 pr_err("find target, node: %pOF, no target property\n", info_node);
715
716 return NULL;
717}
718
719/**
720 * init_overlay_changeset() - initialize overlay changeset from overlay tree
721 * @ovcs: Overlay changeset to build
722 * @fdt: the FDT that was unflattened to create @tree
723 * @tree: Contains all the overlay fragments and overlay fixup nodes
724 *
725 * Initialize @ovcs. Populate @ovcs->fragments with node information from
726 * the top level of @tree. The relevant top level nodes are the fragment
727 * nodes and the __symbols__ node. Any other top level node will be ignored.
728 *
729 * Returns 0 on success, -ENOMEM if memory allocation failure, -EINVAL if error
730 * detected in @tree, or -ENOSPC if idr_alloc() error.
731 */
732static int init_overlay_changeset(struct overlay_changeset *ovcs,
733 const void *fdt, struct device_node *tree)
734{
735 struct device_node *node, *overlay_node;
736 struct fragment *fragment;
737 struct fragment *fragments;
738 int cnt, id, ret;
739
740 /*
741 * Warn for some issues. Can not return -EINVAL for these until
742 * of_unittest_apply_overlay() is fixed to pass these checks.
743 */
744 if (!of_node_check_flag(tree, OF_DYNAMIC))
745 pr_debug("%s() tree is not dynamic\n", __func__);
746
747 if (!of_node_check_flag(tree, OF_DETACHED))
748 pr_debug("%s() tree is not detached\n", __func__);
749
750 if (!of_node_is_root(tree))
751 pr_debug("%s() tree is not root\n", __func__);
752
753 ovcs->overlay_tree = tree;
754 ovcs->fdt = fdt;
755
756 INIT_LIST_HEAD(&ovcs->ovcs_list);
757
758 of_changeset_init(&ovcs->cset);
759
760 id = idr_alloc(&ovcs_idr, ovcs, 1, 0, GFP_KERNEL);
761 if (id <= 0)
762 return id;
763
764 cnt = 0;
765
766 /* fragment nodes */
767 for_each_child_of_node(tree, node) {
768 overlay_node = of_get_child_by_name(node, "__overlay__");
769 if (overlay_node) {
770 cnt++;
771 of_node_put(overlay_node);
772 }
773 }
774
775 node = of_get_child_by_name(tree, "__symbols__");
776 if (node) {
777 cnt++;
778 of_node_put(node);
779 }
780
781 fragments = kcalloc(cnt, sizeof(*fragments), GFP_KERNEL);
782 if (!fragments) {
783 ret = -ENOMEM;
784 goto err_free_idr;
785 }
786
787 cnt = 0;
788 for_each_child_of_node(tree, node) {
789 overlay_node = of_get_child_by_name(node, "__overlay__");
790 if (!overlay_node)
791 continue;
792
793 fragment = &fragments[cnt];
794 fragment->overlay = overlay_node;
795 fragment->target = find_target(node);
796 if (!fragment->target) {
797 of_node_put(fragment->overlay);
798 ret = -EINVAL;
799 goto err_free_fragments;
800 }
801
802 cnt++;
803 }
804
805 /*
806 * if there is a symbols fragment in ovcs->fragments[i] it is
807 * the final element in the array
808 */
809 node = of_get_child_by_name(tree, "__symbols__");
810 if (node) {
811 ovcs->symbols_fragment = 1;
812 fragment = &fragments[cnt];
813 fragment->overlay = node;
814 fragment->target = of_find_node_by_path("/__symbols__");
815
816 if (!fragment->target) {
817 pr_err("symbols in overlay, but not in live tree\n");
818 ret = -EINVAL;
819 goto err_free_fragments;
820 }
821
822 cnt++;
823 }
824
825 if (!cnt) {
826 pr_err("no fragments or symbols in overlay\n");
827 ret = -EINVAL;
828 goto err_free_fragments;
829 }
830
831 ovcs->id = id;
832 ovcs->count = cnt;
833 ovcs->fragments = fragments;
834
835 return 0;
836
837err_free_fragments:
838 kfree(fragments);
839err_free_idr:
840 idr_remove(&ovcs_idr, id);
841
842 pr_err("%s() failed, ret = %d\n", __func__, ret);
843
844 return ret;
845}
846
847static void free_overlay_changeset(struct overlay_changeset *ovcs)
848{
849 int i;
850
851 if (ovcs->cset.entries.next)
852 of_changeset_destroy(&ovcs->cset);
853
854 if (ovcs->id)
855 idr_remove(&ovcs_idr, ovcs->id);
856
857 for (i = 0; i < ovcs->count; i++) {
858 of_node_put(ovcs->fragments[i].target);
859 of_node_put(ovcs->fragments[i].overlay);
860 }
861 kfree(ovcs->fragments);
862 /*
863 * There should be no live pointers into ovcs->overlay_tree and
864 * ovcs->fdt due to the policy that overlay notifiers are not allowed
865 * to retain pointers into the overlay devicetree.
866 */
867 kfree(ovcs->overlay_tree);
868 kfree(ovcs->fdt);
869 kfree(ovcs);
870}
871
872/*
873 * internal documentation
874 *
875 * of_overlay_apply() - Create and apply an overlay changeset
876 * @fdt: the FDT that was unflattened to create @tree
877 * @tree: Expanded overlay device tree
878 * @ovcs_id: Pointer to overlay changeset id
879 *
880 * Creates and applies an overlay changeset.
881 *
882 * If an error occurs in a pre-apply notifier, then no changes are made
883 * to the device tree.
884 *
885
886 * A non-zero return value will not have created the changeset if error is from:
887 * - parameter checks
888 * - building the changeset
889 * - overlay changeset pre-apply notifier
890 *
891 * If an error is returned by an overlay changeset pre-apply notifier
892 * then no further overlay changeset pre-apply notifier will be called.
893 *
894 * A non-zero return value will have created the changeset if error is from:
895 * - overlay changeset entry notifier
896 * - overlay changeset post-apply notifier
897 *
898 * If an error is returned by an overlay changeset post-apply notifier
899 * then no further overlay changeset post-apply notifier will be called.
900 *
901 * If more than one notifier returns an error, then the last notifier
902 * error to occur is returned.
903 *
904 * If an error occurred while applying the overlay changeset, then an
905 * attempt is made to revert any changes that were made to the
906 * device tree. If there were any errors during the revert attempt
907 * then the state of the device tree can not be determined, and any
908 * following attempt to apply or remove an overlay changeset will be
909 * refused.
910 *
911 * Returns 0 on success, or a negative error number. Overlay changeset
912 * id is returned to *ovcs_id.
913 */
914
915static int of_overlay_apply(const void *fdt, struct device_node *tree,
916 int *ovcs_id)
917{
918 struct overlay_changeset *ovcs;
919 int ret = 0, ret_revert, ret_tmp;
920
921 /*
922 * As of this point, fdt and tree belong to the overlay changeset.
923 * overlay changeset code is responsible for freeing them.
924 */
925
926 if (devicetree_corrupt()) {
927 pr_err("devicetree state suspect, refuse to apply overlay\n");
928 kfree(fdt);
929 kfree(tree);
930 ret = -EBUSY;
931 goto out;
932 }
933
934 ovcs = kzalloc(sizeof(*ovcs), GFP_KERNEL);
935 if (!ovcs) {
936 kfree(fdt);
937 kfree(tree);
938 ret = -ENOMEM;
939 goto out;
940 }
941
942 of_overlay_mutex_lock();
943 mutex_lock(&of_mutex);
944
945 ret = of_resolve_phandles(tree);
946 if (ret)
947 goto err_free_tree;
948
949 ret = init_overlay_changeset(ovcs, fdt, tree);
950 if (ret)
951 goto err_free_tree;
952
953 /*
954 * after overlay_notify(), ovcs->overlay_tree related pointers may have
955 * leaked to drivers, so can not kfree() tree, aka ovcs->overlay_tree;
956 * and can not free fdt, aka ovcs->fdt
957 */
958 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_APPLY);
959 if (ret) {
960 pr_err("overlay changeset pre-apply notify error %d\n", ret);
961 goto err_free_overlay_changeset;
962 }
963
964 ret = build_changeset(ovcs);
965 if (ret)
966 goto err_free_overlay_changeset;
967
968 ret_revert = 0;
969 ret = __of_changeset_apply_entries(&ovcs->cset, &ret_revert);
970 if (ret) {
971 if (ret_revert) {
972 pr_debug("overlay changeset revert error %d\n",
973 ret_revert);
974 devicetree_state_flags |= DTSF_APPLY_FAIL;
975 }
976 goto err_free_overlay_changeset;
977 }
978
979 ret = __of_changeset_apply_notify(&ovcs->cset);
980 if (ret)
981 pr_err("overlay apply changeset entry notify error %d\n", ret);
982 /* notify failure is not fatal, continue */
983
984 list_add_tail(&ovcs->ovcs_list, &ovcs_list);
985 *ovcs_id = ovcs->id;
986
987 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY);
988 if (ret_tmp) {
989 pr_err("overlay changeset post-apply notify error %d\n",
990 ret_tmp);
991 if (!ret)
992 ret = ret_tmp;
993 }
994
995 goto out_unlock;
996
997err_free_tree:
998 kfree(fdt);
999 kfree(tree);
1000
1001err_free_overlay_changeset:
1002 free_overlay_changeset(ovcs);
1003
1004out_unlock:
1005 mutex_unlock(&of_mutex);
1006 of_overlay_mutex_unlock();
1007
1008out:
1009 pr_debug("%s() err=%d\n", __func__, ret);
1010
1011 return ret;
1012}
1013
1014int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
1015 int *ovcs_id)
1016{
1017 const void *new_fdt;
1018 int ret;
1019 u32 size;
1020 struct device_node *overlay_root;
1021
1022 *ovcs_id = 0;
1023 ret = 0;
1024
1025 if (overlay_fdt_size < sizeof(struct fdt_header) ||
1026 fdt_check_header(overlay_fdt)) {
1027 pr_err("Invalid overlay_fdt header\n");
1028 return -EINVAL;
1029 }
1030
1031 size = fdt_totalsize(overlay_fdt);
1032 if (overlay_fdt_size < size)
1033 return -EINVAL;
1034
1035 /*
1036 * Must create permanent copy of FDT because of_fdt_unflatten_tree()
1037 * will create pointers to the passed in FDT in the unflattened tree.
1038 */
1039 new_fdt = kmemdup(overlay_fdt, size, GFP_KERNEL);
1040 if (!new_fdt)
1041 return -ENOMEM;
1042
1043 of_fdt_unflatten_tree(new_fdt, NULL, &overlay_root);
1044 if (!overlay_root) {
1045 pr_err("unable to unflatten overlay_fdt\n");
1046 ret = -EINVAL;
1047 goto out_free_new_fdt;
1048 }
1049
1050 ret = of_overlay_apply(new_fdt, overlay_root, ovcs_id);
1051 if (ret < 0) {
1052 /*
1053 * new_fdt and overlay_root now belong to the overlay
1054 * changeset.
1055 * overlay changeset code is responsible for freeing them.
1056 */
1057 goto out;
1058 }
1059
1060 return 0;
1061
1062
1063out_free_new_fdt:
1064 kfree(new_fdt);
1065
1066out:
1067 return ret;
1068}
1069EXPORT_SYMBOL_GPL(of_overlay_fdt_apply);
1070
1071/*
1072 * Find @np in @tree.
1073 *
1074 * Returns 1 if @np is @tree or is contained in @tree, else 0
1075 */
1076static int find_node(struct device_node *tree, struct device_node *np)
1077{
1078 struct device_node *child;
1079
1080 if (tree == np)
1081 return 1;
1082
1083 for_each_child_of_node(tree, child) {
1084 if (find_node(child, np)) {
1085 of_node_put(child);
1086 return 1;
1087 }
1088 }
1089
1090 return 0;
1091}
1092
1093/*
1094 * Is @remove_ce_node a child of, a parent of, or the same as any
1095 * node in an overlay changeset more topmost than @remove_ovcs?
1096 *
1097 * Returns 1 if found, else 0
1098 */
1099static int node_overlaps_later_cs(struct overlay_changeset *remove_ovcs,
1100 struct device_node *remove_ce_node)
1101{
1102 struct overlay_changeset *ovcs;
1103 struct of_changeset_entry *ce;
1104
1105 list_for_each_entry_reverse(ovcs, &ovcs_list, ovcs_list) {
1106 if (ovcs == remove_ovcs)
1107 break;
1108
1109 list_for_each_entry(ce, &ovcs->cset.entries, node) {
1110 if (find_node(ce->np, remove_ce_node)) {
1111 pr_err("%s: #%d overlaps with #%d @%pOF\n",
1112 __func__, remove_ovcs->id, ovcs->id,
1113 remove_ce_node);
1114 return 1;
1115 }
1116 if (find_node(remove_ce_node, ce->np)) {
1117 pr_err("%s: #%d overlaps with #%d @%pOF\n",
1118 __func__, remove_ovcs->id, ovcs->id,
1119 remove_ce_node);
1120 return 1;
1121 }
1122 }
1123 }
1124
1125 return 0;
1126}
1127
1128/*
1129 * We can safely remove the overlay only if it's the top-most one.
1130 * Newly applied overlays are inserted at the tail of the overlay list,
1131 * so a top most overlay is the one that is closest to the tail.
1132 *
1133 * The topmost check is done by exploiting this property. For each
1134 * affected device node in the log list we check if this overlay is
1135 * the one closest to the tail. If another overlay has affected this
1136 * device node and is closest to the tail, then removal is not permited.
1137 */
1138static int overlay_removal_is_ok(struct overlay_changeset *remove_ovcs)
1139{
1140 struct of_changeset_entry *remove_ce;
1141
1142 list_for_each_entry(remove_ce, &remove_ovcs->cset.entries, node) {
1143 if (node_overlaps_later_cs(remove_ovcs, remove_ce->np)) {
1144 pr_err("overlay #%d is not topmost\n", remove_ovcs->id);
1145 return 0;
1146 }
1147 }
1148
1149 return 1;
1150}
1151
1152/**
1153 * of_overlay_remove() - Revert and free an overlay changeset
1154 * @ovcs_id: Pointer to overlay changeset id
1155 *
1156 * Removes an overlay if it is permissible. @ovcs_id was previously returned
1157 * by of_overlay_fdt_apply().
1158 *
1159 * If an error occurred while attempting to revert the overlay changeset,
1160 * then an attempt is made to re-apply any changeset entry that was
1161 * reverted. If an error occurs on re-apply then the state of the device
1162 * tree can not be determined, and any following attempt to apply or remove
1163 * an overlay changeset will be refused.
1164 *
1165 * A non-zero return value will not revert the changeset if error is from:
1166 * - parameter checks
1167 * - overlay changeset pre-remove notifier
1168 * - overlay changeset entry revert
1169 *
1170 * If an error is returned by an overlay changeset pre-remove notifier
1171 * then no further overlay changeset pre-remove notifier will be called.
1172 *
1173 * If more than one notifier returns an error, then the last notifier
1174 * error to occur is returned.
1175 *
1176 * A non-zero return value will revert the changeset if error is from:
1177 * - overlay changeset entry notifier
1178 * - overlay changeset post-remove notifier
1179 *
1180 * If an error is returned by an overlay changeset post-remove notifier
1181 * then no further overlay changeset post-remove notifier will be called.
1182 *
1183 * Returns 0 on success, or a negative error number. *ovcs_id is set to
1184 * zero after reverting the changeset, even if a subsequent error occurs.
1185 */
1186int of_overlay_remove(int *ovcs_id)
1187{
1188 struct overlay_changeset *ovcs;
1189 int ret, ret_apply, ret_tmp;
1190
1191 ret = 0;
1192
1193 if (devicetree_corrupt()) {
1194 pr_err("suspect devicetree state, refuse to remove overlay\n");
1195 ret = -EBUSY;
1196 goto out;
1197 }
1198
1199 mutex_lock(&of_mutex);
1200
1201 ovcs = idr_find(&ovcs_idr, *ovcs_id);
1202 if (!ovcs) {
1203 ret = -ENODEV;
1204 pr_err("remove: Could not find overlay #%d\n", *ovcs_id);
1205 goto out_unlock;
1206 }
1207
1208 if (!overlay_removal_is_ok(ovcs)) {
1209 ret = -EBUSY;
1210 goto out_unlock;
1211 }
1212
1213 ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE);
1214 if (ret) {
1215 pr_err("overlay changeset pre-remove notify error %d\n", ret);
1216 goto out_unlock;
1217 }
1218
1219 list_del(&ovcs->ovcs_list);
1220
1221 ret_apply = 0;
1222 ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
1223 if (ret) {
1224 if (ret_apply)
1225 devicetree_state_flags |= DTSF_REVERT_FAIL;
1226 goto out_unlock;
1227 }
1228
1229 ret = __of_changeset_revert_notify(&ovcs->cset);
1230 if (ret)
1231 pr_err("overlay remove changeset entry notify error %d\n", ret);
1232 /* notify failure is not fatal, continue */
1233
1234 *ovcs_id = 0;
1235
1236 ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE);
1237 if (ret_tmp) {
1238 pr_err("overlay changeset post-remove notify error %d\n",
1239 ret_tmp);
1240 if (!ret)
1241 ret = ret_tmp;
1242 }
1243
1244 free_overlay_changeset(ovcs);
1245
1246out_unlock:
1247 mutex_unlock(&of_mutex);
1248
1249out:
1250 pr_debug("%s() err=%d\n", __func__, ret);
1251
1252 return ret;
1253}
1254EXPORT_SYMBOL_GPL(of_overlay_remove);
1255
1256/**
1257 * of_overlay_remove_all() - Reverts and frees all overlay changesets
1258 *
1259 * Removes all overlays from the system in the correct order.
1260 *
1261 * Returns 0 on success, or a negative error number
1262 */
1263int of_overlay_remove_all(void)
1264{
1265 struct overlay_changeset *ovcs, *ovcs_n;
1266 int ret;
1267
1268 /* the tail of list is guaranteed to be safe to remove */
1269 list_for_each_entry_safe_reverse(ovcs, ovcs_n, &ovcs_list, ovcs_list) {
1270 ret = of_overlay_remove(&ovcs->id);
1271 if (ret)
1272 return ret;
1273 }
1274
1275 return 0;
1276}
1277EXPORT_SYMBOL_GPL(of_overlay_remove_all);