root/drivers/of/overlay.c

DEFINITIONS

1. devicetree_corrupt
2. of_overlay_mutex_lock
3. of_overlay_mutex_unlock
4. of_overlay_notifier_register
5. of_overlay_notifier_unregister
6. overlay_notify
7. dup_and_fixup_symbol_prop
8. add_changeset_property
9. add_changeset_node
10. build_changeset_next_level
11. build_changeset_symbols_node
12. find_dup_cset_node_entry
13. find_dup_cset_prop
14. changeset_dup_entry_check
15. build_changeset
16. find_target
17. init_overlay_changeset
18. free_overlay_changeset
19. of_overlay_apply
20. of_overlay_fdt_apply
21. find_node
22. node_overlaps_later_cs
23. overlay_removal_is_ok
24. of_overlay_remove
25. of_overlay_remove_all

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Functions for working with device tree overlays
   4  *
   5  * Copyright (C) 2012 Pantelis Antoniou <panto@antoniou-consulting.com>
   6  * Copyright (C) 2012 Texas Instruments Inc.
   7  */
   8 
   9 #define pr_fmt(fmt)     "OF: overlay: " fmt
  10 
  11 #include <linux/kernel.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/of_device.h>
  15 #include <linux/of_fdt.h>
  16 #include <linux/string.h>
  17 #include <linux/ctype.h>
  18 #include <linux/errno.h>
  19 #include <linux/slab.h>
  20 #include <linux/libfdt.h>
  21 #include <linux/err.h>
  22 #include <linux/idr.h>
  23 
  24 #include "of_private.h"
  25 
  26 /**
  27  * struct target - info about current target node as recursing through overlay
  28  * @np:                 node where current level of overlay will be applied
  29  * @in_livetree:        @np is a node in the live devicetree
  30  *
  31  * Used in the algorithm to create the portion of a changeset that describes
  32  * an overlay fragment, which is a devicetree subtree.  Initially @np is a node
  33  * in the live devicetree where the overlay subtree is targeted to be grafted
  34  * into.  When recursing to the next level of the overlay subtree, the target
  35  * also recurses to the next level of the live devicetree, as long as overlay
  36  * subtree node also exists in the live devicetree.  When a node in the overlay
  37  * subtree does not exist at the same level in the live devicetree, target->np
  38  * points to a newly allocated node, and all subsequent targets in the subtree
  39  * will be newly allocated nodes.
  40  */
  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 *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  */
  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  */
  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 
 108 void of_overlay_mutex_lock(void)
 109 {
 110         mutex_lock(&of_overlay_phandle_mutex);
 111 }
 112 
 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  */
 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  */
 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 
 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 (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  */
 199 static 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 
 268 err_free_new_prop:
 269         kfree(new_prop->name);
 270         kfree(new_prop->value);
 271         kfree(new_prop);
 272 err_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  */
 304 static 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  */
 409 static 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  */
 481 static 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  */
 513 static 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 
 532 static 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 
 565 static 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  */
 611 static 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  */
 636 static 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  */
 689 static 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  */
 732 static 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 
 837 err_free_fragments:
 838         kfree(fragments);
 839 err_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 
 847 static 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 
 915 static 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         of_populate_phandle_cache();
 980 
 981         ret = __of_changeset_apply_notify(&ovcs->cset);
 982         if (ret)
 983                 pr_err("overlay apply changeset entry notify error %d\n", ret);
 984         /* notify failure is not fatal, continue */
 985 
 986         list_add_tail(&ovcs->ovcs_list, &ovcs_list);
 987         *ovcs_id = ovcs->id;
 988 
 989         ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_APPLY);
 990         if (ret_tmp) {
 991                 pr_err("overlay changeset post-apply notify error %d\n",
 992                        ret_tmp);
 993                 if (!ret)
 994                         ret = ret_tmp;
 995         }
 996 
 997         goto out_unlock;
 998 
 999 err_free_tree:
1000         kfree(fdt);
1001         kfree(tree);
1002 
1003 err_free_overlay_changeset:
1004         free_overlay_changeset(ovcs);
1005 
1006 out_unlock:
1007         mutex_unlock(&of_mutex);
1008         of_overlay_mutex_unlock();
1009 
1010 out:
1011         pr_debug("%s() err=%d\n", __func__, ret);
1012 
1013         return ret;
1014 }
1015 
1016 int of_overlay_fdt_apply(const void *overlay_fdt, u32 overlay_fdt_size,
1017                          int *ovcs_id)
1018 {
1019         const void *new_fdt;
1020         int ret;
1021         u32 size;
1022         struct device_node *overlay_root;
1023 
1024         *ovcs_id = 0;
1025         ret = 0;
1026 
1027         if (overlay_fdt_size < sizeof(struct fdt_header) ||
1028             fdt_check_header(overlay_fdt)) {
1029                 pr_err("Invalid overlay_fdt header\n");
1030                 return -EINVAL;
1031         }
1032 
1033         size = fdt_totalsize(overlay_fdt);
1034         if (overlay_fdt_size < size)
1035                 return -EINVAL;
1036 
1037         /*
1038          * Must create permanent copy of FDT because of_fdt_unflatten_tree()
1039          * will create pointers to the passed in FDT in the unflattened tree.
1040          */
1041         new_fdt = kmemdup(overlay_fdt, size, GFP_KERNEL);
1042         if (!new_fdt)
1043                 return -ENOMEM;
1044 
1045         of_fdt_unflatten_tree(new_fdt, NULL, &overlay_root);
1046         if (!overlay_root) {
1047                 pr_err("unable to unflatten overlay_fdt\n");
1048                 ret = -EINVAL;
1049                 goto out_free_new_fdt;
1050         }
1051 
1052         ret = of_overlay_apply(new_fdt, overlay_root, ovcs_id);
1053         if (ret < 0) {
1054                 /*
1055                  * new_fdt and overlay_root now belong to the overlay
1056                  * changeset.
1057                  * overlay changeset code is responsible for freeing them.
1058                  */
1059                 goto out;
1060         }
1061 
1062         return 0;
1063 
1064 
1065 out_free_new_fdt:
1066         kfree(new_fdt);
1067 
1068 out:
1069         return ret;
1070 }
1071 EXPORT_SYMBOL_GPL(of_overlay_fdt_apply);
1072 
1073 /*
1074  * Find @np in @tree.
1075  *
1076  * Returns 1 if @np is @tree or is contained in @tree, else 0
1077  */
1078 static int find_node(struct device_node *tree, struct device_node *np)
1079 {
1080         struct device_node *child;
1081 
1082         if (tree == np)
1083                 return 1;
1084 
1085         for_each_child_of_node(tree, child) {
1086                 if (find_node(child, np)) {
1087                         of_node_put(child);
1088                         return 1;
1089                 }
1090         }
1091 
1092         return 0;
1093 }
1094 
1095 /*
1096  * Is @remove_ce_node a child of, a parent of, or the same as any
1097  * node in an overlay changeset more topmost than @remove_ovcs?
1098  *
1099  * Returns 1 if found, else 0
1100  */
1101 static int node_overlaps_later_cs(struct overlay_changeset *remove_ovcs,
1102                 struct device_node *remove_ce_node)
1103 {
1104         struct overlay_changeset *ovcs;
1105         struct of_changeset_entry *ce;
1106 
1107         list_for_each_entry_reverse(ovcs, &ovcs_list, ovcs_list) {
1108                 if (ovcs == remove_ovcs)
1109                         break;
1110 
1111                 list_for_each_entry(ce, &ovcs->cset.entries, node) {
1112                         if (find_node(ce->np, remove_ce_node)) {
1113                                 pr_err("%s: #%d overlaps with #%d @%pOF\n",
1114                                         __func__, remove_ovcs->id, ovcs->id,
1115                                         remove_ce_node);
1116                                 return 1;
1117                         }
1118                         if (find_node(remove_ce_node, ce->np)) {
1119                                 pr_err("%s: #%d overlaps with #%d @%pOF\n",
1120                                         __func__, remove_ovcs->id, ovcs->id,
1121                                         remove_ce_node);
1122                                 return 1;
1123                         }
1124                 }
1125         }
1126 
1127         return 0;
1128 }
1129 
1130 /*
1131  * We can safely remove the overlay only if it's the top-most one.
1132  * Newly applied overlays are inserted at the tail of the overlay list,
1133  * so a top most overlay is the one that is closest to the tail.
1134  *
1135  * The topmost check is done by exploiting this property. For each
1136  * affected device node in the log list we check if this overlay is
1137  * the one closest to the tail. If another overlay has affected this
1138  * device node and is closest to the tail, then removal is not permited.
1139  */
1140 static int overlay_removal_is_ok(struct overlay_changeset *remove_ovcs)
1141 {
1142         struct of_changeset_entry *remove_ce;
1143 
1144         list_for_each_entry(remove_ce, &remove_ovcs->cset.entries, node) {
1145                 if (node_overlaps_later_cs(remove_ovcs, remove_ce->np)) {
1146                         pr_err("overlay #%d is not topmost\n", remove_ovcs->id);
1147                         return 0;
1148                 }
1149         }
1150 
1151         return 1;
1152 }
1153 
1154 /**
1155  * of_overlay_remove() - Revert and free an overlay changeset
1156  * @ovcs_id:    Pointer to overlay changeset id
1157  *
1158  * Removes an overlay if it is permissible.  @ovcs_id was previously returned
1159  * by of_overlay_fdt_apply().
1160  *
1161  * If an error occurred while attempting to revert the overlay changeset,
1162  * then an attempt is made to re-apply any changeset entry that was
1163  * reverted.  If an error occurs on re-apply then the state of the device
1164  * tree can not be determined, and any following attempt to apply or remove
1165  * an overlay changeset will be refused.
1166  *
1167  * A non-zero return value will not revert the changeset if error is from:
1168  *   - parameter checks
1169  *   - overlay changeset pre-remove notifier
1170  *   - overlay changeset entry revert
1171  *
1172  * If an error is returned by an overlay changeset pre-remove notifier
1173  * then no further overlay changeset pre-remove notifier will be called.
1174  *
1175  * If more than one notifier returns an error, then the last notifier
1176  * error to occur is returned.
1177  *
1178  * A non-zero return value will revert the changeset if error is from:
1179  *   - overlay changeset entry notifier
1180  *   - overlay changeset post-remove notifier
1181  *
1182  * If an error is returned by an overlay changeset post-remove notifier
1183  * then no further overlay changeset post-remove notifier will be called.
1184  *
1185  * Returns 0 on success, or a negative error number.  *ovcs_id is set to
1186  * zero after reverting the changeset, even if a subsequent error occurs.
1187  */
1188 int of_overlay_remove(int *ovcs_id)
1189 {
1190         struct overlay_changeset *ovcs;
1191         int ret, ret_apply, ret_tmp;
1192 
1193         ret = 0;
1194 
1195         if (devicetree_corrupt()) {
1196                 pr_err("suspect devicetree state, refuse to remove overlay\n");
1197                 ret = -EBUSY;
1198                 goto out;
1199         }
1200 
1201         mutex_lock(&of_mutex);
1202 
1203         ovcs = idr_find(&ovcs_idr, *ovcs_id);
1204         if (!ovcs) {
1205                 ret = -ENODEV;
1206                 pr_err("remove: Could not find overlay #%d\n", *ovcs_id);
1207                 goto out_unlock;
1208         }
1209 
1210         if (!overlay_removal_is_ok(ovcs)) {
1211                 ret = -EBUSY;
1212                 goto out_unlock;
1213         }
1214 
1215         ret = overlay_notify(ovcs, OF_OVERLAY_PRE_REMOVE);
1216         if (ret) {
1217                 pr_err("overlay changeset pre-remove notify error %d\n", ret);
1218                 goto out_unlock;
1219         }
1220 
1221         list_del(&ovcs->ovcs_list);
1222 
1223         /*
1224          * Disable phandle cache.  Avoids race condition that would arise
1225          * from removing cache entry when the associated node is deleted.
1226          */
1227         of_free_phandle_cache();
1228 
1229         ret_apply = 0;
1230         ret = __of_changeset_revert_entries(&ovcs->cset, &ret_apply);
1231 
1232         of_populate_phandle_cache();
1233 
1234         if (ret) {
1235                 if (ret_apply)
1236                         devicetree_state_flags |= DTSF_REVERT_FAIL;
1237                 goto out_unlock;
1238         }
1239 
1240         ret = __of_changeset_revert_notify(&ovcs->cset);
1241         if (ret)
1242                 pr_err("overlay remove changeset entry notify error %d\n", ret);
1243         /* notify failure is not fatal, continue */
1244 
1245         *ovcs_id = 0;
1246 
1247         ret_tmp = overlay_notify(ovcs, OF_OVERLAY_POST_REMOVE);
1248         if (ret_tmp) {
1249                 pr_err("overlay changeset post-remove notify error %d\n",
1250                        ret_tmp);
1251                 if (!ret)
1252                         ret = ret_tmp;
1253         }
1254 
1255         free_overlay_changeset(ovcs);
1256 
1257 out_unlock:
1258         mutex_unlock(&of_mutex);
1259 
1260 out:
1261         pr_debug("%s() err=%d\n", __func__, ret);
1262 
1263         return ret;
1264 }
1265 EXPORT_SYMBOL_GPL(of_overlay_remove);
1266 
1267 /**
1268  * of_overlay_remove_all() - Reverts and frees all overlay changesets
1269  *
1270  * Removes all overlays from the system in the correct order.
1271  *
1272  * Returns 0 on success, or a negative error number
1273  */
1274 int of_overlay_remove_all(void)
1275 {
1276         struct overlay_changeset *ovcs, *ovcs_n;
1277         int ret;
1278 
1279         /* the tail of list is guaranteed to be safe to remove */
1280         list_for_each_entry_safe_reverse(ovcs, ovcs_n, &ovcs_list, ovcs_list) {
1281                 ret = of_overlay_remove(&ovcs->id);
1282                 if (ret)
1283                         return ret;
1284         }
1285 
1286         return 0;
1287 }
1288 EXPORT_SYMBOL_GPL(of_overlay_remove_all);