1// SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-2-Clause)
2/*
3 * libfdt - Flat Device Tree manipulation
4 * Copyright (C) 2006 David Gibson, IBM Corporation.
5 */
6#include "libfdt_env.h"
7
8#include <fdt.h>
9#include <libfdt.h>
10
11#include "libfdt_internal.h"
12
13static int fdt_sw_probe_(void *fdt)
14{
15	if (!can_assume(VALID_INPUT)) {
16		if (fdt_magic(fdt) == FDT_MAGIC)
17			return -FDT_ERR_BADSTATE;
18		else if (fdt_magic(fdt) != FDT_SW_MAGIC)
19			return -FDT_ERR_BADMAGIC;
20	}
21
22	return 0;
23}
24
25#define FDT_SW_PROBE(fdt) \
26	{ \
27		int err; \
28		if ((err = fdt_sw_probe_(fdt)) != 0) \
29			return err; \
30	}
31
32/* 'memrsv' state:	Initial state after fdt_create()
33 *
34 * Allowed functions:
35 *	fdt_add_reservemap_entry()
36 *	fdt_finish_reservemap()		[moves to 'struct' state]
37 */
38static int fdt_sw_probe_memrsv_(void *fdt)
39{
40	int err = fdt_sw_probe_(fdt);
41	if (err)
42		return err;
43
44	if (!can_assume(VALID_INPUT) && fdt_off_dt_strings(fdt) != 0)
45		return -FDT_ERR_BADSTATE;
46	return 0;
47}
48
49#define FDT_SW_PROBE_MEMRSV(fdt) \
50	{ \
51		int err; \
52		if ((err = fdt_sw_probe_memrsv_(fdt)) != 0) \
53			return err; \
54	}
55
56/* 'struct' state:	Enter this state after fdt_finish_reservemap()
57 *
58 * Allowed functions:
59 *	fdt_begin_node()
60 *	fdt_end_node()
61 *	fdt_property*()
62 *	fdt_finish()			[moves to 'complete' state]
63 */
64static int fdt_sw_probe_struct_(void *fdt)
65{
66	int err = fdt_sw_probe_(fdt);
67	if (err)
68		return err;
69
70	if (!can_assume(VALID_INPUT) &&
71	    fdt_off_dt_strings(fdt) != fdt_totalsize(fdt))
72		return -FDT_ERR_BADSTATE;
73	return 0;
74}
75
76#define FDT_SW_PROBE_STRUCT(fdt) \
77	{ \
78		int err; \
79		if ((err = fdt_sw_probe_struct_(fdt)) != 0) \
80			return err; \
81	}
82
83static inline uint32_t sw_flags(void *fdt)
84{
85	/* assert: (fdt_magic(fdt) == FDT_SW_MAGIC) */
86	return fdt_last_comp_version(fdt);
87}
88
89/* 'complete' state:	Enter this state after fdt_finish()
90 *
91 * Allowed functions: none
92 */
93
94static void *fdt_grab_space_(void *fdt, size_t len)
95{
96	unsigned int offset = fdt_size_dt_struct(fdt);
97	unsigned int spaceleft;
98
99	spaceleft = fdt_totalsize(fdt) - fdt_off_dt_struct(fdt)
100		- fdt_size_dt_strings(fdt);
101
102	if ((offset + len < offset) || (offset + len > spaceleft))
103		return NULL;
104
105	fdt_set_size_dt_struct(fdt, offset + len);
106	return fdt_offset_ptr_w_(fdt, offset);
107}
108
109int fdt_create_with_flags(void *buf, int bufsize, uint32_t flags)
110{
111	const int hdrsize = FDT_ALIGN(sizeof(struct fdt_header),
112				      sizeof(struct fdt_reserve_entry));
113	void *fdt = buf;
114
115	if (bufsize < hdrsize)
116		return -FDT_ERR_NOSPACE;
117
118	if (flags & ~FDT_CREATE_FLAGS_ALL)
119		return -FDT_ERR_BADFLAGS;
120
121	memset(buf, 0, bufsize);
122
123	/*
124	 * magic and last_comp_version keep intermediate state during the fdt
125	 * creation process, which is replaced with the proper FDT format by
126	 * fdt_finish().
127	 *
128	 * flags should be accessed with sw_flags().
129	 */
130	fdt_set_magic(fdt, FDT_SW_MAGIC);
131	fdt_set_version(fdt, FDT_LAST_SUPPORTED_VERSION);
132	fdt_set_last_comp_version(fdt, flags);
133
134	fdt_set_totalsize(fdt,  bufsize);
135
136	fdt_set_off_mem_rsvmap(fdt, hdrsize);
137	fdt_set_off_dt_struct(fdt, fdt_off_mem_rsvmap(fdt));
138	fdt_set_off_dt_strings(fdt, 0);
139
140	return 0;
141}
142
143int fdt_create(void *buf, int bufsize)
144{
145	return fdt_create_with_flags(buf, bufsize, 0);
146}
147
148int fdt_resize(void *fdt, void *buf, int bufsize)
149{
150	size_t headsize, tailsize;
151	char *oldtail, *newtail;
152
153	FDT_SW_PROBE(fdt);
154
155	if (bufsize < 0)
156		return -FDT_ERR_NOSPACE;
157
158	headsize = fdt_off_dt_struct(fdt) + fdt_size_dt_struct(fdt);
159	tailsize = fdt_size_dt_strings(fdt);
160
161	if (!can_assume(VALID_DTB) &&
162	    headsize + tailsize > fdt_totalsize(fdt))
163		return -FDT_ERR_INTERNAL;
164
165	if ((headsize + tailsize) > (unsigned)bufsize)
166		return -FDT_ERR_NOSPACE;
167
168	oldtail = (char *)fdt + fdt_totalsize(fdt) - tailsize;
169	newtail = (char *)buf + bufsize - tailsize;
170
171	/* Two cases to avoid clobbering data if the old and new
172	 * buffers partially overlap */
173	if (buf <= fdt) {
174		memmove(buf, fdt, headsize);
175		memmove(newtail, oldtail, tailsize);
176	} else {
177		memmove(newtail, oldtail, tailsize);
178		memmove(buf, fdt, headsize);
179	}
180
181	fdt_set_totalsize(buf, bufsize);
182	if (fdt_off_dt_strings(buf))
183		fdt_set_off_dt_strings(buf, bufsize);
184
185	return 0;
186}
187
188int fdt_add_reservemap_entry(void *fdt, uint64_t addr, uint64_t size)
189{
190	struct fdt_reserve_entry *re;
191	int offset;
192
193	FDT_SW_PROBE_MEMRSV(fdt);
194
195	offset = fdt_off_dt_struct(fdt);
196	if ((offset + sizeof(*re)) > fdt_totalsize(fdt))
197		return -FDT_ERR_NOSPACE;
198
199	re = (struct fdt_reserve_entry *)((char *)fdt + offset);
200	re->address = cpu_to_fdt64(addr);
201	re->size = cpu_to_fdt64(size);
202
203	fdt_set_off_dt_struct(fdt, offset + sizeof(*re));
204
205	return 0;
206}
207
208int fdt_finish_reservemap(void *fdt)
209{
210	int err = fdt_add_reservemap_entry(fdt, 0, 0);
211
212	if (err)
213		return err;
214
215	fdt_set_off_dt_strings(fdt, fdt_totalsize(fdt));
216	return 0;
217}
218
219int fdt_begin_node(void *fdt, const char *name)
220{
221	struct fdt_node_header *nh;
222	int namelen;
223
224	FDT_SW_PROBE_STRUCT(fdt);
225
226	namelen = strlen(name) + 1;
227	nh = fdt_grab_space_(fdt, sizeof(*nh) + FDT_TAGALIGN(namelen));
228	if (! nh)
229		return -FDT_ERR_NOSPACE;
230
231	nh->tag = cpu_to_fdt32(FDT_BEGIN_NODE);
232	memcpy(nh->name, name, namelen);
233	return 0;
234}
235
236int fdt_end_node(void *fdt)
237{
238	fdt32_t *en;
239
240	FDT_SW_PROBE_STRUCT(fdt);
241
242	en = fdt_grab_space_(fdt, FDT_TAGSIZE);
243	if (! en)
244		return -FDT_ERR_NOSPACE;
245
246	*en = cpu_to_fdt32(FDT_END_NODE);
247	return 0;
248}
249
250static int fdt_add_string_(void *fdt, const char *s)
251{
252	char *strtab = (char *)fdt + fdt_totalsize(fdt);
253	unsigned int strtabsize = fdt_size_dt_strings(fdt);
254	unsigned int len = strlen(s) + 1;
255	unsigned int struct_top, offset;
256
257	offset = strtabsize + len;
258	struct_top = fdt_off_dt_struct(fdt) + fdt_size_dt_struct(fdt);
259	if (fdt_totalsize(fdt) - offset < struct_top)
260		return 0; /* no more room :( */
261
262	memcpy(strtab - offset, s, len);
263	fdt_set_size_dt_strings(fdt, strtabsize + len);
264	return -offset;
265}
266
267/* Must only be used to roll back in case of error */
268static void fdt_del_last_string_(void *fdt, const char *s)
269{
270	int strtabsize = fdt_size_dt_strings(fdt);
271	int len = strlen(s) + 1;
272
273	fdt_set_size_dt_strings(fdt, strtabsize - len);
274}
275
276static int fdt_find_add_string_(void *fdt, const char *s, int *allocated)
277{
278	char *strtab = (char *)fdt + fdt_totalsize(fdt);
279	int strtabsize = fdt_size_dt_strings(fdt);
280	const char *p;
281
282	*allocated = 0;
283
284	p = fdt_find_string_(strtab - strtabsize, strtabsize, s);
285	if (p)
286		return p - strtab;
287
288	*allocated = 1;
289
290	return fdt_add_string_(fdt, s);
291}
292
293int fdt_property_placeholder(void *fdt, const char *name, int len, void **valp)
294{
295	struct fdt_property *prop;
296	int nameoff;
297	int allocated;
298
299	FDT_SW_PROBE_STRUCT(fdt);
300
301	/* String de-duplication can be slow, _NO_NAME_DEDUP skips it */
302	if (sw_flags(fdt) & FDT_CREATE_FLAG_NO_NAME_DEDUP) {
303		allocated = 1;
304		nameoff = fdt_add_string_(fdt, name);
305	} else {
306		nameoff = fdt_find_add_string_(fdt, name, &allocated);
307	}
308	if (nameoff == 0)
309		return -FDT_ERR_NOSPACE;
310
311	prop = fdt_grab_space_(fdt, sizeof(*prop) + FDT_TAGALIGN(len));
312	if (! prop) {
313		if (allocated)
314			fdt_del_last_string_(fdt, name);
315		return -FDT_ERR_NOSPACE;
316	}
317
318	prop->tag = cpu_to_fdt32(FDT_PROP);
319	prop->nameoff = cpu_to_fdt32(nameoff);
320	prop->len = cpu_to_fdt32(len);
321	*valp = prop->data;
322	return 0;
323}
324
325int fdt_property(void *fdt, const char *name, const void *val, int len)
326{
327	void *ptr;
328	int ret;
329
330	ret = fdt_property_placeholder(fdt, name, len, &ptr);
331	if (ret)
332		return ret;
333	memcpy(ptr, val, len);
334	return 0;
335}
336
337int fdt_finish(void *fdt)
338{
339	char *p = (char *)fdt;
340	fdt32_t *end;
341	int oldstroffset, newstroffset;
342	uint32_t tag;
343	int offset, nextoffset;
344
345	FDT_SW_PROBE_STRUCT(fdt);
346
347	/* Add terminator */
348	end = fdt_grab_space_(fdt, sizeof(*end));
349	if (! end)
350		return -FDT_ERR_NOSPACE;
351	*end = cpu_to_fdt32(FDT_END);
352
353	/* Relocate the string table */
354	oldstroffset = fdt_totalsize(fdt) - fdt_size_dt_strings(fdt);
355	newstroffset = fdt_off_dt_struct(fdt) + fdt_size_dt_struct(fdt);
356	memmove(p + newstroffset, p + oldstroffset, fdt_size_dt_strings(fdt));
357	fdt_set_off_dt_strings(fdt, newstroffset);
358
359	/* Walk the structure, correcting string offsets */
360	offset = 0;
361	while ((tag = fdt_next_tag(fdt, offset, &nextoffset)) != FDT_END) {
362		if (tag == FDT_PROP) {
363			struct fdt_property *prop =
364				fdt_offset_ptr_w_(fdt, offset);
365			int nameoff;
366
367			nameoff = fdt32_to_cpu(prop->nameoff);
368			nameoff += fdt_size_dt_strings(fdt);
369			prop->nameoff = cpu_to_fdt32(nameoff);
370		}
371		offset = nextoffset;
372	}
373	if (nextoffset < 0)
374		return nextoffset;
375
376	/* Finally, adjust the header */
377	fdt_set_totalsize(fdt, newstroffset + fdt_size_dt_strings(fdt));
378
379	/* And fix up fields that were keeping intermediate state. */
380	fdt_set_last_comp_version(fdt, FDT_LAST_COMPATIBLE_VERSION);
381	fdt_set_magic(fdt, FDT_MAGIC);
382
383	return 0;
384}
385