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