xref: /linux/lib/bootconfig.c (revision 8137a49e1567726eb10fcf55ad141ac19804ca6b)
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_child() - Find a child node which matches given key
146  * @parent: An XBC node.
147  * @key: A key string.
148  *
149  * Search a 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_child(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_child(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(__pa(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 }
922