lib/bootconfig.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Extra Boot Config
   4  * Masami Hiramatsu <mhiramat@kernel.org>
   5  */
   6
   7 #define pr_fmt(fmt)    "bootconfig: " fmt
   8
   9 #include <linux/bootconfig.h>
  10 #include <linux/bug.h>
  11 #include <linux/ctype.h>
  12 #include <linux/errno.h>
  13 #include <linux/kernel.h>
  14 #include <linux/memblock.h>
  15 #include <linux/printk.h>
  16 #include <linux/string.h>
  17
  18 /*
  19  * Extra Boot Config (XBC) is given as tree-structured ascii text of
  20  * key-value pairs on memory.
  21  * xbc_parse() parses the text to build a simple tree. Each tree node is
  22  * simply a key word or a value. A key node may have a next key node or/and
  23  * a child node (both key and value). A value node may have a next value
  24  * node (for array).
  25  */
  26
  27 static struct xbc_node *xbc_nodes __initdata;
  28 static int xbc_node_num __initdata;
  29 static char *xbc_data __initdata;
  30 static size_t xbc_data_size __initdata;
  31 static struct xbc_node *last_parent __initdata;
  32 static const char *xbc_err_msg __initdata;
  33 static int xbc_err_pos __initdata;
  34 static int open_brace[XBC_DEPTH_MAX] __initdata;
  35 static int brace_index __initdata;
  36
  37 static int __init xbc_parse_error(const char *msg, const char *p)
  38 {
  39         xbc_err_msg = msg;
  40         xbc_err_pos = (int)(p - xbc_data);
  41
  42         return -EINVAL;
  43 }
  44
  45 /**
  46  * xbc_root_node() - Get the root node of extended boot config
  47  *
  48  * Return the address of root node of extended boot config. If the
  49  * extended boot config is not initiized, return NULL.
  50  */
  51 struct xbc_node * __init xbc_root_node(void)
  52 {
  53         if (unlikely(!xbc_data))
  54                 return NULL;
  55
  56         return xbc_nodes;
  57 }
  58
  59 /**
  60  * xbc_node_index() - Get the index of XBC node
  61  * @node: A target node of getting index.
  62  *
  63  * Return the index number of @node in XBC node list.
  64  */
  65 int __init xbc_node_index(struct xbc_node *node)
  66 {
  67         return node - &xbc_nodes[0];
  68 }
  69
  70 /**
  71  * xbc_node_get_parent() - Get the parent XBC node
  72  * @node: An XBC node.
  73  *
  74  * Return the parent node of @node. If the node is top node of the tree,
  75  * return NULL.
  76  */
  77 struct xbc_node * __init xbc_node_get_parent(struct xbc_node *node)
  78 {
  79         return node->parent == XBC_NODE_MAX ? NULL : &xbc_nodes[node->parent];
  80 }
  81
  82 /**
  83  * xbc_node_get_child() - Get the child XBC node
  84  * @node: An XBC node.
  85  *
  86  * Return the first child node of @node. If the node has no child, return
  87  * NULL.
  88  */
  89 struct xbc_node * __init xbc_node_get_child(struct xbc_node *node)
  90 {
  91         return node->child ? &xbc_nodes[node->child] : NULL;
  92 }
  93
  94 /**
  95  * xbc_node_get_next() - Get the next sibling XBC node
  96  * @node: An XBC node.
  97  *
  98  * Return the NEXT sibling node of @node. If the node has no next sibling,
  99  * return NULL. Note that even if this returns NULL, it doesn't mean @node
 100  * has no siblings. (You also has to check whether the parent's child node
 101  * is @node or not.)
 102  */
 103 struct xbc_node * __init xbc_node_get_next(struct xbc_node *node)
 104 {
 105         return node->next ? &xbc_nodes[node->next] : NULL;
 106 }
 107
 108 /**
 109  * xbc_node_get_data() - Get the data of XBC node
 110  * @node: An XBC node.
 111  *
 112  * Return the data (which is always a null terminated string) of @node.
 113  * If the node has invalid data, warn and return NULL.
 114  */
 115 const char * __init xbc_node_get_data(struct xbc_node *node)
 116 {
 117         int offset = node->data & ~XBC_VALUE;
 118
 119         if (WARN_ON(offset >= xbc_data_size))
 120                 return NULL;
 121
 122         return xbc_data + offset;
 123 }
 124
 125 static bool __init
 126 xbc_node_match_prefix(struct xbc_node *node, const char **prefix)
 127 {
 128         const char *p = xbc_node_get_data(node);
 129         int len = strlen(p);
 130
 131         if (strncmp(*prefix, p, len))
 132                 return false;
 133
 134         p = *prefix + len;
 135         if (*p == '.')
 136                 p++;
 137         else if (*p != '\0')
 138                 return false;
 139         *prefix = p;
 140
 141         return true;
 142 }
 143
 144 /**
 145  * xbc_node_find_subkey() - Find a subkey node which matches given key
 146  * @parent: An XBC node.
 147  * @key: A key string.
 148  *
 149  * Search a key node under @parent which matches @key. The @key can contain
 150  * several words jointed with '.'. If @parent is NULL, this searches the
 151  * node from whole tree. Return NULL if no node is matched.
 152  */
 153 struct xbc_node * __init
 154 xbc_node_find_subkey(struct xbc_node *parent, const char *key)
 155 {
 156         struct xbc_node *node;
 157
 158         if (parent)
 159                 node = xbc_node_get_subkey(parent);
 160         else
 161                 node = xbc_root_node();
 162
 163         while (node && xbc_node_is_key(node)) {
 164                 if (!xbc_node_match_prefix(node, &key))
 165                         node = xbc_node_get_next(node);
 166                 else if (*key != '\0')
 167                         node = xbc_node_get_subkey(node);
 168                 else
 169                         break;
 170         }
 171
 172         return node;
 173 }
 174
 175 /**
 176  * xbc_node_find_value() - Find a value node which matches given key
 177  * @parent: An XBC node.
 178  * @key: A key string.
 179  * @vnode: A container pointer of found XBC node.
 180  *
 181  * Search a value node under @parent whose (parent) key node matches @key,
 182  * store it in *@vnode, and returns the value string.
 183  * The @key can contain several words jointed with '.'. If @parent is NULL,
 184  * this searches the node from whole tree. Return the value string if a
 185  * matched key found, return NULL if no node is matched.
 186  * Note that this returns 0-length string and stores NULL in *@vnode if the
 187  * key has no value. And also it will return the value of the first entry if
 188  * the value is an array.
 189  */
 190 const char * __init
 191 xbc_node_find_value(struct xbc_node *parent, const char *key,
 192                     struct xbc_node **vnode)
 193 {
 194         struct xbc_node *node = xbc_node_find_subkey(parent, key);
 195
 196         if (!node || !xbc_node_is_key(node))
 197                 return NULL;
 198
 199         node = xbc_node_get_child(node);
 200         if (node && !xbc_node_is_value(node))
 201                 return NULL;
 202
 203         if (vnode)
 204                 *vnode = node;
 205
 206         return node ? xbc_node_get_data(node) : "";
 207 }
 208
 209 /**
 210  * xbc_node_compose_key_after() - Compose partial key string of the XBC node
 211  * @root: Root XBC node
 212  * @node: Target XBC node.
 213  * @buf: A buffer to store the key.
 214  * @size: The size of the @buf.
 215  *
 216  * Compose the partial key of the @node into @buf, which is starting right
 217  * after @root (@root is not included.) If @root is NULL, this returns full
 218  * key words of @node.
 219  * Returns the total length of the key stored in @buf. Returns -EINVAL
 220  * if @node is NULL or @root is not the ancestor of @node or @root is @node,
 221  * or returns -ERANGE if the key depth is deeper than max depth.
 222  * This is expected to be used with xbc_find_node() to list up all (child)
 223  * keys under given key.
 224  */
 225 int __init xbc_node_compose_key_after(struct xbc_node *root,
 226                                       struct xbc_node *node,
 227                                       char *buf, size_t size)
 228 {
 229         u16 keys[XBC_DEPTH_MAX];
 230         int depth = 0, ret = 0, total = 0;
 231
 232         if (!node || node == root)
 233                 return -EINVAL;
 234
 235         if (xbc_node_is_value(node))
 236                 node = xbc_node_get_parent(node);
 237
 238         while (node && node != root) {
 239                 keys[depth++] = xbc_node_index(node);
 240                 if (depth == XBC_DEPTH_MAX)
 241                         return -ERANGE;
 242                 node = xbc_node_get_parent(node);
 243         }
 244         if (!node && root)
 245                 return -EINVAL;
 246
 247         while (--depth >= 0) {
 248                 node = xbc_nodes + keys[depth];
 249                 ret = snprintf(buf, size, "%s%s", xbc_node_get_data(node),
 250                                depth ? "." : "");
 251                 if (ret < 0)
 252                         return ret;
 253                 if (ret > size) {
 254                         size = 0;
 255                 } else {
 256                         size -= ret;
 257                         buf += ret;
 258                 }
 259                 total += ret;
 260         }
 261
 262         return total;
 263 }
 264
 265 /**
 266  * xbc_node_find_next_leaf() - Find the next leaf node under given node
 267  * @root: An XBC root node
 268  * @node: An XBC node which starts from.
 269  *
 270  * Search the next leaf node (which means the terminal key node) of @node
 271  * under @root node (including @root node itself).
 272  * Return the next node or NULL if next leaf node is not found.
 273  */
 274 struct xbc_node * __init xbc_node_find_next_leaf(struct xbc_node *root,
 275                                                  struct xbc_node *node)
 276 {
 277         struct xbc_node *next;
 278
 279         if (unlikely(!xbc_data))
 280                 return NULL;
 281
 282         if (!node) {    /* First try */
 283                 node = root;
 284                 if (!node)
 285                         node = xbc_nodes;
 286         } else {
 287                 /* Leaf node may have a subkey */
 288                 next = xbc_node_get_subkey(node);
 289                 if (next) {
 290                         node = next;
 291                         goto found;
 292                 }
 293
 294                 if (node == root)       /* @root was a leaf, no child node. */
 295                         return NULL;
 296
 297                 while (!node->next) {
 298                         node = xbc_node_get_parent(node);
 299                         if (node == root)
 300                                 return NULL;
 301                         /* User passed a node which is not uder parent */
 302                         if (WARN_ON(!node))
 303                                 return NULL;
 304                 }
 305                 node = xbc_node_get_next(node);
 306         }
 307
 308 found:
 309         while (node && !xbc_node_is_leaf(node))
 310                 node = xbc_node_get_child(node);
 311
 312         return node;
 313 }
 314
 315 /**
 316  * xbc_node_find_next_key_value() - Find the next key-value pair nodes
 317  * @root: An XBC root node
 318  * @leaf: A container pointer of XBC node which starts from.
 319  *
 320  * Search the next leaf node (which means the terminal key node) of *@leaf
 321  * under @root node. Returns the value and update *@leaf if next leaf node
 322  * is found, or NULL if no next leaf node is found.
 323  * Note that this returns 0-length string if the key has no value, or
 324  * the value of the first entry if the value is an array.
 325  */
 326 const char * __init xbc_node_find_next_key_value(struct xbc_node *root,
 327                                                  struct xbc_node **leaf)
 328 {
 329         /* tip must be passed */
 330         if (WARN_ON(!leaf))
 331                 return NULL;
 332
 333         *leaf = xbc_node_find_next_leaf(root, *leaf);
 334         if (!*leaf)
 335                 return NULL;
 336         if ((*leaf)->child)
 337                 return xbc_node_get_data(xbc_node_get_child(*leaf));
 338         else
 339                 return "";      /* No value key */
 340 }
 341
 342 /* XBC parse and tree build */
 343
 344 static int __init xbc_init_node(struct xbc_node *node, char *data, u32 flag)
 345 {
 346         unsigned long offset = data - xbc_data;
 347
 348         if (WARN_ON(offset >= XBC_DATA_MAX))
 349                 return -EINVAL;
 350
 351         node->data = (u16)offset | flag;
 352         node->child = 0;
 353         node->next = 0;
 354
 355         return 0;
 356 }
 357
 358 static struct xbc_node * __init xbc_add_node(char *data, u32 flag)
 359 {
 360         struct xbc_node *node;
 361
 362         if (xbc_node_num == XBC_NODE_MAX)
 363                 return NULL;
 364
 365         node = &xbc_nodes[xbc_node_num++];
 366         if (xbc_init_node(node, data, flag) < 0)
 367                 return NULL;
 368
 369         return node;
 370 }
 371
 372 static inline __init struct xbc_node *xbc_last_sibling(struct xbc_node *node)
 373 {
 374         while (node->next)
 375                 node = xbc_node_get_next(node);
 376
 377         return node;
 378 }
 379
 380 static inline __init struct xbc_node *xbc_last_child(struct xbc_node *node)
 381 {
 382         while (node->child)
 383                 node = xbc_node_get_child(node);
 384
 385         return node;
 386 }
 387
 388 static struct xbc_node * __init __xbc_add_sibling(char *data, u32 flag, bool head)
 389 {
 390         struct xbc_node *sib, *node = xbc_add_node(data, flag);
 391
 392         if (node) {
 393                 if (!last_parent) {
 394                         /* Ignore @head in this case */
 395                         node->parent = XBC_NODE_MAX;
 396                         sib = xbc_last_sibling(xbc_nodes);
 397                         sib->next = xbc_node_index(node);
 398                 } else {
 399                         node->parent = xbc_node_index(last_parent);
 400                         if (!last_parent->child || head) {
 401                                 node->next = last_parent->child;
 402                                 last_parent->child = xbc_node_index(node);
 403                         } else {
 404                                 sib = xbc_node_get_child(last_parent);
 405                                 sib = xbc_last_sibling(sib);
 406                                 sib->next = xbc_node_index(node);
 407                         }
 408                 }
 409         } else
 410                 xbc_parse_error("Too many nodes", data);
 411
 412         return node;
 413 }
 414
 415 static inline struct xbc_node * __init xbc_add_sibling(char *data, u32 flag)
 416 {
 417         return __xbc_add_sibling(data, flag, false);
 418 }
 419
 420 static inline struct xbc_node * __init xbc_add_head_sibling(char *data, u32 flag)
 421 {
 422         return __xbc_add_sibling(data, flag, true);
 423 }
 424
 425 static inline __init struct xbc_node *xbc_add_child(char *data, u32 flag)
 426 {
 427         struct xbc_node *node = xbc_add_sibling(data, flag);
 428
 429         if (node)
 430                 last_parent = node;
 431
 432         return node;
 433 }
 434
 435 static inline __init bool xbc_valid_keyword(char *key)
 436 {
 437         if (key[0] == '\0')
 438                 return false;
 439
 440         while (isalnum(*key) || *key == '-' || *key == '_')
 441                 key++;
 442
 443         return *key == '\0';
 444 }
 445
 446 static char *skip_comment(char *p)
 447 {
 448         char *ret;
 449
 450         ret = strchr(p, '\n');
 451         if (!ret)
 452                 ret = p + strlen(p);
 453         else
 454                 ret++;
 455
 456         return ret;
 457 }
 458
 459 static char *skip_spaces_until_newline(char *p)
 460 {
 461         while (isspace(*p) && *p != '\n')
 462                 p++;
 463         return p;
 464 }
 465
 466 static int __init __xbc_open_brace(char *p)
 467 {
 468         /* Push the last key as open brace */
 469         open_brace[brace_index++] = xbc_node_index(last_parent);
 470         if (brace_index >= XBC_DEPTH_MAX)
 471                 return xbc_parse_error("Exceed max depth of braces", p);
 472
 473         return 0;
 474 }
 475
 476 static int __init __xbc_close_brace(char *p)
 477 {
 478         brace_index--;
 479         if (!last_parent || brace_index < 0 ||
 480             (open_brace[brace_index] != xbc_node_index(last_parent)))
 481                 return xbc_parse_error("Unexpected closing brace", p);
 482
 483         if (brace_index == 0)
 484                 last_parent = NULL;
 485         else
 486                 last_parent = &xbc_nodes[open_brace[brace_index - 1]];
 487
 488         return 0;
 489 }
 490
 491 /*
 492  * Return delimiter or error, no node added. As same as lib/cmdline.c,
 493  * you can use " around spaces, but can't escape " for value.
 494  */
 495 static int __init __xbc_parse_value(char **__v, char **__n)
 496 {
 497         char *p, *v = *__v;
 498         int c, quotes = 0;
 499
 500         v = skip_spaces(v);
 501         while (*v == '#') {
 502                 v = skip_comment(v);
 503                 v = skip_spaces(v);
 504         }
 505         if (*v == '"' || *v == '\'') {
 506                 quotes = *v;
 507                 v++;
 508         }
 509         p = v - 1;
 510         while ((c = *++p)) {
 511                 if (!isprint(c) && !isspace(c))
 512                         return xbc_parse_error("Non printable value", p);
 513                 if (quotes) {
 514                         if (c != quotes)
 515                                 continue;
 516                         quotes = 0;
 517                         *p++ = '\0';
 518                         p = skip_spaces_until_newline(p);
 519                         c = *p;
 520                         if (c && !strchr(",;\n#}", c))
 521                                 return xbc_parse_error("No value delimiter", p);
 522                         if (*p)
 523                                 p++;
 524                         break;
 525                 }
 526                 if (strchr(",;\n#}", c)) {
 527                         *p++ = '\0';
 528                         v = strim(v);
 529                         break;
 530                 }
 531         }
 532         if (quotes)
 533                 return xbc_parse_error("No closing quotes", p);
 534         if (c == '#') {
 535                 p = skip_comment(p);
 536                 c = '\n';       /* A comment must be treated as a newline */
 537         }
 538         *__n = p;
 539         *__v = v;
 540
 541         return c;
 542 }
 543
 544 static int __init xbc_parse_array(char **__v)
 545 {
 546         struct xbc_node *node;
 547         char *next;
 548         int c = 0;
 549
 550         if (last_parent->child)
 551                 last_parent = xbc_node_get_child(last_parent);
 552
 553         do {
 554                 c = __xbc_parse_value(__v, &next);
 555                 if (c < 0)
 556                         return c;
 557
 558                 node = xbc_add_child(*__v, XBC_VALUE);
 559                 if (!node)
 560                         return -ENOMEM;
 561                 *__v = next;
 562         } while (c == ',');
 563         node->child = 0;
 564
 565         return c;
 566 }
 567
 568 static inline __init
 569 struct xbc_node *find_match_node(struct xbc_node *node, char *k)
 570 {
 571         while (node) {
 572                 if (!strcmp(xbc_node_get_data(node), k))
 573                         break;
 574                 node = xbc_node_get_next(node);
 575         }
 576         return node;
 577 }
 578
 579 static int __init __xbc_add_key(char *k)
 580 {
 581         struct xbc_node *node, *child;
 582
 583         if (!xbc_valid_keyword(k))
 584                 return xbc_parse_error("Invalid keyword", k);
 585
 586         if (unlikely(xbc_node_num == 0))
 587                 goto add_node;
 588
 589         if (!last_parent)       /* the first level */
 590                 node = find_match_node(xbc_nodes, k);
 591         else {
 592                 child = xbc_node_get_child(last_parent);
 593                 /* Since the value node is the first child, skip it. */
 594                 if (child && xbc_node_is_value(child))
 595                         child = xbc_node_get_next(child);
 596                 node = find_match_node(child, k);
 597         }
 598
 599         if (node)
 600                 last_parent = node;
 601         else {
 602 add_node:
 603                 node = xbc_add_child(k, XBC_KEY);
 604                 if (!node)
 605                         return -ENOMEM;
 606         }
 607         return 0;
 608 }
 609
 610 static int __init __xbc_parse_keys(char *k)
 611 {
 612         char *p;
 613         int ret;
 614
 615         k = strim(k);
 616         while ((p = strchr(k, '.'))) {
 617                 *p++ = '\0';
 618                 ret = __xbc_add_key(k);
 619                 if (ret)
 620                         return ret;
 621                 k = p;
 622         }
 623
 624         return __xbc_add_key(k);
 625 }
 626
 627 static int __init xbc_parse_kv(char **k, char *v, int op)
 628 {
 629         struct xbc_node *prev_parent = last_parent;
 630         struct xbc_node *child;
 631         char *next;
 632         int c, ret;
 633
 634         ret = __xbc_parse_keys(*k);
 635         if (ret)
 636                 return ret;
 637
 638         c = __xbc_parse_value(&v, &next);
 639         if (c < 0)
 640                 return c;
 641
 642         child = xbc_node_get_child(last_parent);
 643         if (child && xbc_node_is_value(child)) {
 644                 if (op == '=')
 645                         return xbc_parse_error("Value is redefined", v);
 646                 if (op == ':') {
 647                         unsigned short nidx = child->next;
 648
 649                         xbc_init_node(child, v, XBC_VALUE);
 650                         child->next = nidx;     /* keep subkeys */
 651                         goto array;
 652                 }
 653                 /* op must be '+' */
 654                 last_parent = xbc_last_child(child);
 655         }
 656         /* The value node should always be the first child */
 657         if (!xbc_add_head_sibling(v, XBC_VALUE))
 658                 return -ENOMEM;
 659
 660 array:
 661         if (c == ',') { /* Array */
 662                 c = xbc_parse_array(&next);
 663                 if (c < 0)
 664                         return c;
 665         }
 666
 667         last_parent = prev_parent;
 668
 669         if (c == '}') {
 670                 ret = __xbc_close_brace(next - 1);
 671                 if (ret < 0)
 672                         return ret;
 673         }
 674
 675         *k = next;
 676
 677         return 0;
 678 }
 679
 680 static int __init xbc_parse_key(char **k, char *n)
 681 {
 682         struct xbc_node *prev_parent = last_parent;
 683         int ret;
 684
 685         *k = strim(*k);
 686         if (**k != '\0') {
 687                 ret = __xbc_parse_keys(*k);
 688                 if (ret)
 689                         return ret;
 690                 last_parent = prev_parent;
 691         }
 692         *k = n;
 693
 694         return 0;
 695 }
 696
 697 static int __init xbc_open_brace(char **k, char *n)
 698 {
 699         int ret;
 700
 701         ret = __xbc_parse_keys(*k);
 702         if (ret)
 703                 return ret;
 704         *k = n;
 705
 706         return __xbc_open_brace(n - 1);
 707 }
 708
 709 static int __init xbc_close_brace(char **k, char *n)
 710 {
 711         int ret;
 712
 713         ret = xbc_parse_key(k, n);
 714         if (ret)
 715                 return ret;
 716         /* k is updated in xbc_parse_key() */
 717
 718         return __xbc_close_brace(n - 1);
 719 }
 720
 721 static int __init xbc_verify_tree(void)
 722 {
 723         int i, depth, len, wlen;
 724         struct xbc_node *n, *m;
 725
 726         /* Brace closing */
 727         if (brace_index) {
 728                 n = &xbc_nodes[open_brace[brace_index]];
 729                 return xbc_parse_error("Brace is not closed",
 730                                         xbc_node_get_data(n));
 731         }
 732
 733         /* Empty tree */
 734         if (xbc_node_num == 0) {
 735                 xbc_parse_error("Empty config", xbc_data);
 736                 return -ENOENT;
 737         }
 738
 739         for (i = 0; i < xbc_node_num; i++) {
 740                 if (xbc_nodes[i].next > xbc_node_num) {
 741                         return xbc_parse_error("No closing brace",
 742                                 xbc_node_get_data(xbc_nodes + i));
 743                 }
 744         }
 745
 746         /* Key tree limitation check */
 747         n = &xbc_nodes[0];
 748         depth = 1;
 749         len = 0;
 750
 751         while (n) {
 752                 wlen = strlen(xbc_node_get_data(n)) + 1;
 753                 len += wlen;
 754                 if (len > XBC_KEYLEN_MAX)
 755                         return xbc_parse_error("Too long key length",
 756                                 xbc_node_get_data(n));
 757
 758                 m = xbc_node_get_child(n);
 759                 if (m && xbc_node_is_key(m)) {
 760                         n = m;
 761                         depth++;
 762                         if (depth > XBC_DEPTH_MAX)
 763                                 return xbc_parse_error("Too many key words",
 764                                                 xbc_node_get_data(n));
 765                         continue;
 766                 }
 767                 len -= wlen;
 768                 m = xbc_node_get_next(n);
 769                 while (!m) {
 770                         n = xbc_node_get_parent(n);
 771                         if (!n)
 772                                 break;
 773                         len -= strlen(xbc_node_get_data(n)) + 1;
 774                         depth--;
 775                         m = xbc_node_get_next(n);
 776                 }
 777                 n = m;
 778         }
 779
 780         return 0;
 781 }
 782
 783 /**
 784  * xbc_destroy_all() - Clean up all parsed bootconfig
 785  *
 786  * This clears all data structures of parsed bootconfig on memory.
 787  * If you need to reuse xbc_init() with new boot config, you can
 788  * use this.
 789  */
 790 void __init xbc_destroy_all(void)
 791 {
 792         xbc_data = NULL;
 793         xbc_data_size = 0;
 794         xbc_node_num = 0;
 795         memblock_free_ptr(xbc_nodes, sizeof(struct xbc_node) * XBC_NODE_MAX);
 796         xbc_nodes = NULL;
 797         brace_index = 0;
 798 }
 799
 800 /**
 801  * xbc_init() - Parse given XBC file and build XBC internal tree
 802  * @buf: boot config text
 803  * @emsg: A pointer of const char * to store the error message
 804  * @epos: A pointer of int to store the error position
 805  *
 806  * This parses the boot config text in @buf. @buf must be a
 807  * null terminated string and smaller than XBC_DATA_MAX.
 808  * Return the number of stored nodes (>0) if succeeded, or -errno
 809  * if there is any error.
 810  * In error cases, @emsg will be updated with an error message and
 811  * @epos will be updated with the error position which is the byte offset
 812  * of @buf. If the error is not a parser error, @epos will be -1.
 813  */
 814 int __init xbc_init(char *buf, const char **emsg, int *epos)
 815 {
 816         char *p, *q;
 817         int ret, c;
 818
 819         if (epos)
 820                 *epos = -1;
 821
 822         if (xbc_data) {
 823                 if (emsg)
 824                         *emsg = "Bootconfig is already initialized";
 825                 return -EBUSY;
 826         }
 827
 828         ret = strlen(buf);
 829         if (ret > XBC_DATA_MAX - 1 || ret == 0) {
 830                 if (emsg)
 831                         *emsg = ret ? "Config data is too big" :
 832                                 "Config data is empty";
 833                 return -ERANGE;
 834         }
 835
 836         xbc_nodes = memblock_alloc(sizeof(struct xbc_node) * XBC_NODE_MAX,
 837                                    SMP_CACHE_BYTES);
 838         if (!xbc_nodes) {
 839                 if (emsg)
 840                         *emsg = "Failed to allocate bootconfig nodes";
 841                 return -ENOMEM;
 842         }
 843         memset(xbc_nodes, 0, sizeof(struct xbc_node) * XBC_NODE_MAX);
 844         xbc_data = buf;
 845         xbc_data_size = ret + 1;
 846         last_parent = NULL;
 847
 848         p = buf;
 849         do {
 850                 q = strpbrk(p, "{}=+;:\n#");
 851                 if (!q) {
 852                         p = skip_spaces(p);
 853                         if (*p != '\0')
 854                                 ret = xbc_parse_error("No delimiter", p);
 855                         break;
 856                 }
 857
 858                 c = *q;
 859                 *q++ = '\0';
 860                 switch (c) {
 861                 case ':':
 862                 case '+':
 863                         if (*q++ != '=') {
 864                                 ret = xbc_parse_error(c == '+' ?
 865                                                 "Wrong '+' operator" :
 866                                                 "Wrong ':' operator",
 867                                                         q - 2);
 868                                 break;
 869                         }
 870                         fallthrough;
 871                 case '=':
 872                         ret = xbc_parse_kv(&p, q, c);
 873                         break;
 874                 case '{':
 875                         ret = xbc_open_brace(&p, q);
 876                         break;
 877                 case '#':
 878                         q = skip_comment(q);
 879                         fallthrough;
 880                 case ';':
 881                 case '\n':
 882                         ret = xbc_parse_key(&p, q);
 883                         break;
 884                 case '}':
 885                         ret = xbc_close_brace(&p, q);
 886                         break;
 887                 }
 888         } while (!ret);
 889
 890         if (!ret)
 891                 ret = xbc_verify_tree();
 892
 893         if (ret < 0) {
 894                 if (epos)
 895                         *epos = xbc_err_pos;
 896                 if (emsg)
 897                         *emsg = xbc_err_msg;
 898                 xbc_destroy_all();
 899         } else
 900                 ret = xbc_node_num;
 901
 902         return ret;
 903 }
 904
 905 /**
 906  * xbc_debug_dump() - Dump current XBC node list
 907  *
 908  * Dump the current XBC node list on printk buffer for debug.
 909  */
 910 void __init xbc_debug_dump(void)
 911 {
 912         int i;
 913
 914         for (i = 0; i < xbc_node_num; i++) {
 915                 pr_debug("[%d] %s (%s) .next=%d, .child=%d .parent=%d\n", i,
 916                         xbc_node_get_data(xbc_nodes + i),
 917                         xbc_node_is_value(xbc_nodes + i) ? "value" : "key",
 918                         xbc_nodes[i].next, xbc_nodes[i].child,
 919                         xbc_nodes[i].parent);
 920         }
 921 }