xref: /linux/tools/bpf/resolve_btfids/main.c (revision 89aa02edaa30e4327ebc8fca9b80795bbfd4ce9b)
1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2 
3 /*
4  * resolve_btfids scans ELF object for .BTF_ids section and resolves
5  * its symbols with BTF ID values.
6  *
7  * Each symbol points to 4 bytes data and is expected to have
8  * following name syntax:
9  *
10  * __BTF_ID__<type>__<symbol>[__<id>]
11  *
12  * type is:
13  *
14  *   func    - lookup BTF_KIND_FUNC symbol with <symbol> name
15  *             and store its ID into the data:
16  *
17  *             __BTF_ID__func__vfs_close__1:
18  *             .zero 4
19  *
20  *   struct  - lookup BTF_KIND_STRUCT symbol with <symbol> name
21  *             and store its ID into the data:
22  *
23  *             __BTF_ID__struct__sk_buff__1:
24  *             .zero 4
25  *
26  *   union   - lookup BTF_KIND_UNION symbol with <symbol> name
27  *             and store its ID into the data:
28  *
29  *             __BTF_ID__union__thread_union__1:
30  *             .zero 4
31  *
32  *   typedef - lookup BTF_KIND_TYPEDEF symbol with <symbol> name
33  *             and store its ID into the data:
34  *
35  *             __BTF_ID__typedef__pid_t__1:
36  *             .zero 4
37  *
38  *   set     - store symbol size into first 4 bytes and sort following
39  *             ID list
40  *
41  *             __BTF_ID__set__list:
42  *             .zero 4
43  *             list:
44  *             __BTF_ID__func__vfs_getattr__3:
45  *             .zero 4
46  *             __BTF_ID__func__vfs_fallocate__4:
47  *             .zero 4
48  *
49  *   set8    - store symbol size into first 4 bytes and sort following
50  *             ID list
51  *
52  *             __BTF_ID__set8__list:
53  *             .zero 8
54  *             list:
55  *             __BTF_ID__func__vfs_getattr__3:
56  *             .zero 4
57  *	       .word (1 << 0) | (1 << 2)
58  *             __BTF_ID__func__vfs_fallocate__5:
59  *             .zero 4
60  *	       .word (1 << 3) | (1 << 1) | (1 << 2)
61  */
62 
63 #define  _GNU_SOURCE
64 #include <stdio.h>
65 #include <string.h>
66 #include <unistd.h>
67 #include <stdlib.h>
68 #include <libelf.h>
69 #include <gelf.h>
70 #include <sys/stat.h>
71 #include <fcntl.h>
72 #include <errno.h>
73 #include <linux/btf_ids.h>
74 #include <linux/rbtree.h>
75 #include <linux/zalloc.h>
76 #include <linux/err.h>
77 #include <bpf/btf.h>
78 #include <bpf/libbpf.h>
79 #include <subcmd/parse-options.h>
80 
81 #define BTF_IDS_SECTION	".BTF_ids"
82 #define BTF_ID_PREFIX	"__BTF_ID__"
83 
84 #define BTF_STRUCT	"struct"
85 #define BTF_UNION	"union"
86 #define BTF_TYPEDEF	"typedef"
87 #define BTF_FUNC	"func"
88 #define BTF_SET		"set"
89 #define BTF_SET8	"set8"
90 
91 #define ADDR_CNT	100
92 
93 #if __BYTE_ORDER == __LITTLE_ENDIAN
94 # define ELFDATANATIVE	ELFDATA2LSB
95 #elif __BYTE_ORDER == __BIG_ENDIAN
96 # define ELFDATANATIVE	ELFDATA2MSB
97 #else
98 # error "Unknown machine endianness!"
99 #endif
100 
101 struct btf_id {
102 	struct rb_node	 rb_node;
103 	char		*name;
104 	union {
105 		int	 id;
106 		int	 cnt;
107 	};
108 	int		 addr_cnt;
109 	bool		 is_set;
110 	bool		 is_set8;
111 	Elf64_Addr	 addr[ADDR_CNT];
112 };
113 
114 struct object {
115 	const char *path;
116 	const char *btf;
117 	const char *base_btf_path;
118 
119 	struct {
120 		int		 fd;
121 		Elf		*elf;
122 		Elf_Data	*symbols;
123 		Elf_Data	*idlist;
124 		int		 symbols_shndx;
125 		int		 idlist_shndx;
126 		size_t		 strtabidx;
127 		unsigned long	 idlist_addr;
128 		int		 encoding;
129 	} efile;
130 
131 	struct rb_root	sets;
132 	struct rb_root	structs;
133 	struct rb_root	unions;
134 	struct rb_root	typedefs;
135 	struct rb_root	funcs;
136 
137 	int nr_funcs;
138 	int nr_structs;
139 	int nr_unions;
140 	int nr_typedefs;
141 };
142 
143 static int verbose;
144 
145 static int eprintf(int level, int var, const char *fmt, ...)
146 {
147 	va_list args;
148 	int ret = 0;
149 
150 	if (var >= level) {
151 		va_start(args, fmt);
152 		ret = vfprintf(stderr, fmt, args);
153 		va_end(args);
154 	}
155 	return ret;
156 }
157 
158 #ifndef pr_fmt
159 #define pr_fmt(fmt) fmt
160 #endif
161 
162 #define pr_debug(fmt, ...) \
163 	eprintf(1, verbose, pr_fmt(fmt), ##__VA_ARGS__)
164 #define pr_debugN(n, fmt, ...) \
165 	eprintf(n, verbose, pr_fmt(fmt), ##__VA_ARGS__)
166 #define pr_debug2(fmt, ...) pr_debugN(2, pr_fmt(fmt), ##__VA_ARGS__)
167 #define pr_err(fmt, ...) \
168 	eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)
169 #define pr_info(fmt, ...) \
170 	eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)
171 
172 static bool is_btf_id(const char *name)
173 {
174 	return name && !strncmp(name, BTF_ID_PREFIX, sizeof(BTF_ID_PREFIX) - 1);
175 }
176 
177 static struct btf_id *btf_id__find(struct rb_root *root, const char *name)
178 {
179 	struct rb_node *p = root->rb_node;
180 	struct btf_id *id;
181 	int cmp;
182 
183 	while (p) {
184 		id = rb_entry(p, struct btf_id, rb_node);
185 		cmp = strcmp(id->name, name);
186 		if (cmp < 0)
187 			p = p->rb_left;
188 		else if (cmp > 0)
189 			p = p->rb_right;
190 		else
191 			return id;
192 	}
193 	return NULL;
194 }
195 
196 static struct btf_id *
197 btf_id__add(struct rb_root *root, char *name, bool unique)
198 {
199 	struct rb_node **p = &root->rb_node;
200 	struct rb_node *parent = NULL;
201 	struct btf_id *id;
202 	int cmp;
203 
204 	while (*p != NULL) {
205 		parent = *p;
206 		id = rb_entry(parent, struct btf_id, rb_node);
207 		cmp = strcmp(id->name, name);
208 		if (cmp < 0)
209 			p = &(*p)->rb_left;
210 		else if (cmp > 0)
211 			p = &(*p)->rb_right;
212 		else
213 			return unique ? NULL : id;
214 	}
215 
216 	id = zalloc(sizeof(*id));
217 	if (id) {
218 		pr_debug("adding symbol %s\n", name);
219 		id->name = name;
220 		rb_link_node(&id->rb_node, parent, p);
221 		rb_insert_color(&id->rb_node, root);
222 	}
223 	return id;
224 }
225 
226 static char *get_id(const char *prefix_end)
227 {
228 	/*
229 	 * __BTF_ID__func__vfs_truncate__0
230 	 * prefix_end =  ^
231 	 * pos        =    ^
232 	 */
233 	int len = strlen(prefix_end);
234 	int pos = sizeof("__") - 1;
235 	char *p, *id;
236 
237 	if (pos >= len)
238 		return NULL;
239 
240 	id = strdup(prefix_end + pos);
241 	if (id) {
242 		/*
243 		 * __BTF_ID__func__vfs_truncate__0
244 		 * id =            ^
245 		 *
246 		 * cut the unique id part
247 		 */
248 		p = strrchr(id, '_');
249 		p--;
250 		if (*p != '_') {
251 			free(id);
252 			return NULL;
253 		}
254 		*p = '\0';
255 	}
256 	return id;
257 }
258 
259 static struct btf_id *add_set(struct object *obj, char *name, bool is_set8)
260 {
261 	/*
262 	 * __BTF_ID__set__name
263 	 * name =    ^
264 	 * id   =         ^
265 	 */
266 	char *id = name + (is_set8 ? sizeof(BTF_SET8 "__") : sizeof(BTF_SET "__")) - 1;
267 	int len = strlen(name);
268 
269 	if (id >= name + len) {
270 		pr_err("FAILED to parse set name: %s\n", name);
271 		return NULL;
272 	}
273 
274 	return btf_id__add(&obj->sets, id, true);
275 }
276 
277 static struct btf_id *add_symbol(struct rb_root *root, char *name, size_t size)
278 {
279 	char *id;
280 
281 	id = get_id(name + size);
282 	if (!id) {
283 		pr_err("FAILED to parse symbol name: %s\n", name);
284 		return NULL;
285 	}
286 
287 	return btf_id__add(root, id, false);
288 }
289 
290 /* Older libelf.h and glibc elf.h might not yet define the ELF compression types. */
291 #ifndef SHF_COMPRESSED
292 #define SHF_COMPRESSED (1 << 11) /* Section with compressed data. */
293 #endif
294 
295 /*
296  * The data of compressed section should be aligned to 4
297  * (for 32bit) or 8 (for 64 bit) bytes. The binutils ld
298  * sets sh_addralign to 1, which makes libelf fail with
299  * misaligned section error during the update:
300  *    FAILED elf_update(WRITE): invalid section alignment
301  *
302  * While waiting for ld fix, we fix the compressed sections
303  * sh_addralign value manualy.
304  */
305 static int compressed_section_fix(Elf *elf, Elf_Scn *scn, GElf_Shdr *sh)
306 {
307 	int expected = gelf_getclass(elf) == ELFCLASS32 ? 4 : 8;
308 
309 	if (!(sh->sh_flags & SHF_COMPRESSED))
310 		return 0;
311 
312 	if (sh->sh_addralign == expected)
313 		return 0;
314 
315 	pr_debug2(" - fixing wrong alignment sh_addralign %u, expected %u\n",
316 		  sh->sh_addralign, expected);
317 
318 	sh->sh_addralign = expected;
319 
320 	if (gelf_update_shdr(scn, sh) == 0) {
321 		pr_err("FAILED cannot update section header: %s\n",
322 			elf_errmsg(-1));
323 		return -1;
324 	}
325 	return 0;
326 }
327 
328 static int elf_collect(struct object *obj)
329 {
330 	Elf_Scn *scn = NULL;
331 	size_t shdrstrndx;
332 	GElf_Ehdr ehdr;
333 	int idx = 0;
334 	Elf *elf;
335 	int fd;
336 
337 	fd = open(obj->path, O_RDWR, 0666);
338 	if (fd == -1) {
339 		pr_err("FAILED cannot open %s: %s\n",
340 			obj->path, strerror(errno));
341 		return -1;
342 	}
343 
344 	elf_version(EV_CURRENT);
345 
346 	elf = elf_begin(fd, ELF_C_RDWR_MMAP, NULL);
347 	if (!elf) {
348 		close(fd);
349 		pr_err("FAILED cannot create ELF descriptor: %s\n",
350 			elf_errmsg(-1));
351 		return -1;
352 	}
353 
354 	obj->efile.fd  = fd;
355 	obj->efile.elf = elf;
356 
357 	elf_flagelf(elf, ELF_C_SET, ELF_F_LAYOUT);
358 
359 	if (elf_getshdrstrndx(elf, &shdrstrndx) != 0) {
360 		pr_err("FAILED cannot get shdr str ndx\n");
361 		return -1;
362 	}
363 
364 	if (gelf_getehdr(obj->efile.elf, &ehdr) == NULL) {
365 		pr_err("FAILED cannot get ELF header: %s\n",
366 			elf_errmsg(-1));
367 		return -1;
368 	}
369 	obj->efile.encoding = ehdr.e_ident[EI_DATA];
370 
371 	/*
372 	 * Scan all the elf sections and look for save data
373 	 * from .BTF_ids section and symbols.
374 	 */
375 	while ((scn = elf_nextscn(elf, scn)) != NULL) {
376 		Elf_Data *data;
377 		GElf_Shdr sh;
378 		char *name;
379 
380 		idx++;
381 		if (gelf_getshdr(scn, &sh) != &sh) {
382 			pr_err("FAILED get section(%d) header\n", idx);
383 			return -1;
384 		}
385 
386 		name = elf_strptr(elf, shdrstrndx, sh.sh_name);
387 		if (!name) {
388 			pr_err("FAILED get section(%d) name\n", idx);
389 			return -1;
390 		}
391 
392 		data = elf_getdata(scn, 0);
393 		if (!data) {
394 			pr_err("FAILED to get section(%d) data from %s\n",
395 				idx, name);
396 			return -1;
397 		}
398 
399 		pr_debug2("section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
400 			  idx, name, (unsigned long) data->d_size,
401 			  (int) sh.sh_link, (unsigned long) sh.sh_flags,
402 			  (int) sh.sh_type);
403 
404 		if (sh.sh_type == SHT_SYMTAB) {
405 			obj->efile.symbols       = data;
406 			obj->efile.symbols_shndx = idx;
407 			obj->efile.strtabidx     = sh.sh_link;
408 		} else if (!strcmp(name, BTF_IDS_SECTION)) {
409 			obj->efile.idlist       = data;
410 			obj->efile.idlist_shndx = idx;
411 			obj->efile.idlist_addr  = sh.sh_addr;
412 		}
413 
414 		if (compressed_section_fix(elf, scn, &sh))
415 			return -1;
416 	}
417 
418 	return 0;
419 }
420 
421 static int symbols_collect(struct object *obj)
422 {
423 	Elf_Scn *scn = NULL;
424 	int n, i;
425 	GElf_Shdr sh;
426 	char *name;
427 
428 	scn = elf_getscn(obj->efile.elf, obj->efile.symbols_shndx);
429 	if (!scn)
430 		return -1;
431 
432 	if (gelf_getshdr(scn, &sh) != &sh)
433 		return -1;
434 
435 	n = sh.sh_size / sh.sh_entsize;
436 
437 	/*
438 	 * Scan symbols and look for the ones starting with
439 	 * __BTF_ID__* over .BTF_ids section.
440 	 */
441 	for (i = 0; i < n; i++) {
442 		char *prefix;
443 		struct btf_id *id;
444 		GElf_Sym sym;
445 
446 		if (!gelf_getsym(obj->efile.symbols, i, &sym))
447 			return -1;
448 
449 		if (sym.st_shndx != obj->efile.idlist_shndx)
450 			continue;
451 
452 		name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
453 				  sym.st_name);
454 
455 		if (!is_btf_id(name))
456 			continue;
457 
458 		/*
459 		 * __BTF_ID__TYPE__vfs_truncate__0
460 		 * prefix =  ^
461 		 */
462 		prefix = name + sizeof(BTF_ID_PREFIX) - 1;
463 
464 		/* struct */
465 		if (!strncmp(prefix, BTF_STRUCT, sizeof(BTF_STRUCT) - 1)) {
466 			obj->nr_structs++;
467 			id = add_symbol(&obj->structs, prefix, sizeof(BTF_STRUCT) - 1);
468 		/* union  */
469 		} else if (!strncmp(prefix, BTF_UNION, sizeof(BTF_UNION) - 1)) {
470 			obj->nr_unions++;
471 			id = add_symbol(&obj->unions, prefix, sizeof(BTF_UNION) - 1);
472 		/* typedef */
473 		} else if (!strncmp(prefix, BTF_TYPEDEF, sizeof(BTF_TYPEDEF) - 1)) {
474 			obj->nr_typedefs++;
475 			id = add_symbol(&obj->typedefs, prefix, sizeof(BTF_TYPEDEF) - 1);
476 		/* func */
477 		} else if (!strncmp(prefix, BTF_FUNC, sizeof(BTF_FUNC) - 1)) {
478 			obj->nr_funcs++;
479 			id = add_symbol(&obj->funcs, prefix, sizeof(BTF_FUNC) - 1);
480 		/* set8 */
481 		} else if (!strncmp(prefix, BTF_SET8, sizeof(BTF_SET8) - 1)) {
482 			id = add_set(obj, prefix, true);
483 			/*
484 			 * SET8 objects store list's count, which is encoded
485 			 * in symbol's size, together with 'cnt' field hence
486 			 * that - 1.
487 			 */
488 			if (id) {
489 				id->cnt = sym.st_size / sizeof(uint64_t) - 1;
490 				id->is_set8 = true;
491 			}
492 		/* set */
493 		} else if (!strncmp(prefix, BTF_SET, sizeof(BTF_SET) - 1)) {
494 			id = add_set(obj, prefix, false);
495 			/*
496 			 * SET objects store list's count, which is encoded
497 			 * in symbol's size, together with 'cnt' field hence
498 			 * that - 1.
499 			 */
500 			if (id) {
501 				id->cnt = sym.st_size / sizeof(int) - 1;
502 				id->is_set = true;
503 			}
504 		} else {
505 			pr_err("FAILED unsupported prefix %s\n", prefix);
506 			return -1;
507 		}
508 
509 		if (!id)
510 			return -ENOMEM;
511 
512 		if (id->addr_cnt >= ADDR_CNT) {
513 			pr_err("FAILED symbol %s crossed the number of allowed lists\n",
514 				id->name);
515 			return -1;
516 		}
517 		id->addr[id->addr_cnt++] = sym.st_value;
518 	}
519 
520 	return 0;
521 }
522 
523 static int symbols_resolve(struct object *obj)
524 {
525 	int nr_typedefs = obj->nr_typedefs;
526 	int nr_structs  = obj->nr_structs;
527 	int nr_unions   = obj->nr_unions;
528 	int nr_funcs    = obj->nr_funcs;
529 	struct btf *base_btf = NULL;
530 	int err, type_id;
531 	struct btf *btf;
532 	__u32 nr_types;
533 
534 	if (obj->base_btf_path) {
535 		base_btf = btf__parse(obj->base_btf_path, NULL);
536 		err = libbpf_get_error(base_btf);
537 		if (err) {
538 			pr_err("FAILED: load base BTF from %s: %s\n",
539 			       obj->base_btf_path, strerror(-err));
540 			return -1;
541 		}
542 	}
543 
544 	btf = btf__parse_split(obj->btf ?: obj->path, base_btf);
545 	err = libbpf_get_error(btf);
546 	if (err) {
547 		pr_err("FAILED: load BTF from %s: %s\n",
548 			obj->btf ?: obj->path, strerror(-err));
549 		goto out;
550 	}
551 
552 	err = -1;
553 	nr_types = btf__type_cnt(btf);
554 
555 	/*
556 	 * Iterate all the BTF types and search for collected symbol IDs.
557 	 */
558 	for (type_id = 1; type_id < nr_types; type_id++) {
559 		const struct btf_type *type;
560 		struct rb_root *root;
561 		struct btf_id *id;
562 		const char *str;
563 		int *nr;
564 
565 		type = btf__type_by_id(btf, type_id);
566 		if (!type) {
567 			pr_err("FAILED: malformed BTF, can't resolve type for ID %d\n",
568 				type_id);
569 			goto out;
570 		}
571 
572 		if (btf_is_func(type) && nr_funcs) {
573 			nr   = &nr_funcs;
574 			root = &obj->funcs;
575 		} else if (btf_is_struct(type) && nr_structs) {
576 			nr   = &nr_structs;
577 			root = &obj->structs;
578 		} else if (btf_is_union(type) && nr_unions) {
579 			nr   = &nr_unions;
580 			root = &obj->unions;
581 		} else if (btf_is_typedef(type) && nr_typedefs) {
582 			nr   = &nr_typedefs;
583 			root = &obj->typedefs;
584 		} else
585 			continue;
586 
587 		str = btf__name_by_offset(btf, type->name_off);
588 		if (!str) {
589 			pr_err("FAILED: malformed BTF, can't resolve name for ID %d\n",
590 				type_id);
591 			goto out;
592 		}
593 
594 		id = btf_id__find(root, str);
595 		if (id) {
596 			if (id->id) {
597 				pr_info("WARN: multiple IDs found for '%s': %d, %d - using %d\n",
598 					str, id->id, type_id, id->id);
599 			} else {
600 				id->id = type_id;
601 				(*nr)--;
602 			}
603 		}
604 	}
605 
606 	err = 0;
607 out:
608 	btf__free(base_btf);
609 	btf__free(btf);
610 	return err;
611 }
612 
613 static int id_patch(struct object *obj, struct btf_id *id)
614 {
615 	Elf_Data *data = obj->efile.idlist;
616 	int *ptr = data->d_buf;
617 	int i;
618 
619 	/* For set, set8, id->id may be 0 */
620 	if (!id->id && !id->is_set && !id->is_set8)
621 		pr_err("WARN: resolve_btfids: unresolved symbol %s\n", id->name);
622 
623 	for (i = 0; i < id->addr_cnt; i++) {
624 		unsigned long addr = id->addr[i];
625 		unsigned long idx = addr - obj->efile.idlist_addr;
626 
627 		pr_debug("patching addr %5lu: ID %7d [%s]\n",
628 			 idx, id->id, id->name);
629 
630 		if (idx >= data->d_size) {
631 			pr_err("FAILED patching index %lu out of bounds %lu\n",
632 				idx, data->d_size);
633 			return -1;
634 		}
635 
636 		idx = idx / sizeof(int);
637 		ptr[idx] = id->id;
638 	}
639 
640 	return 0;
641 }
642 
643 static int __symbols_patch(struct object *obj, struct rb_root *root)
644 {
645 	struct rb_node *next;
646 	struct btf_id *id;
647 
648 	next = rb_first(root);
649 	while (next) {
650 		id = rb_entry(next, struct btf_id, rb_node);
651 
652 		if (id_patch(obj, id))
653 			return -1;
654 
655 		next = rb_next(next);
656 	}
657 	return 0;
658 }
659 
660 static int cmp_id(const void *pa, const void *pb)
661 {
662 	const int *a = pa, *b = pb;
663 
664 	return *a - *b;
665 }
666 
667 static int sets_patch(struct object *obj)
668 {
669 	Elf_Data *data = obj->efile.idlist;
670 	struct rb_node *next;
671 
672 	next = rb_first(&obj->sets);
673 	while (next) {
674 		struct btf_id_set8 *set8;
675 		struct btf_id_set *set;
676 		unsigned long addr, off;
677 		struct btf_id *id;
678 
679 		id   = rb_entry(next, struct btf_id, rb_node);
680 		addr = id->addr[0];
681 		off = addr - obj->efile.idlist_addr;
682 
683 		/* sets are unique */
684 		if (id->addr_cnt != 1) {
685 			pr_err("FAILED malformed data for set '%s'\n",
686 				id->name);
687 			return -1;
688 		}
689 
690 		if (id->is_set) {
691 			set = data->d_buf + off;
692 			qsort(set->ids, set->cnt, sizeof(set->ids[0]), cmp_id);
693 		} else {
694 			set8 = data->d_buf + off;
695 			/*
696 			 * Make sure id is at the beginning of the pairs
697 			 * struct, otherwise the below qsort would not work.
698 			 */
699 			BUILD_BUG_ON(set8->pairs != &set8->pairs[0].id);
700 			qsort(set8->pairs, set8->cnt, sizeof(set8->pairs[0]), cmp_id);
701 
702 			/*
703 			 * When ELF endianness does not match endianness of the
704 			 * host, libelf will do the translation when updating
705 			 * the ELF. This, however, corrupts SET8 flags which are
706 			 * already in the target endianness. So, let's bswap
707 			 * them to the host endianness and libelf will then
708 			 * correctly translate everything.
709 			 */
710 			if (obj->efile.encoding != ELFDATANATIVE) {
711 				int i;
712 
713 				set8->flags = bswap_32(set8->flags);
714 				for (i = 0; i < set8->cnt; i++) {
715 					set8->pairs[i].flags =
716 						bswap_32(set8->pairs[i].flags);
717 				}
718 			}
719 		}
720 
721 		pr_debug("sorting  addr %5lu: cnt %6d [%s]\n",
722 			 off, id->is_set ? set->cnt : set8->cnt, id->name);
723 
724 		next = rb_next(next);
725 	}
726 	return 0;
727 }
728 
729 static int symbols_patch(struct object *obj)
730 {
731 	off_t err;
732 
733 	if (__symbols_patch(obj, &obj->structs)  ||
734 	    __symbols_patch(obj, &obj->unions)   ||
735 	    __symbols_patch(obj, &obj->typedefs) ||
736 	    __symbols_patch(obj, &obj->funcs)    ||
737 	    __symbols_patch(obj, &obj->sets))
738 		return -1;
739 
740 	if (sets_patch(obj))
741 		return -1;
742 
743 	/* Set type to ensure endian translation occurs. */
744 	obj->efile.idlist->d_type = ELF_T_WORD;
745 
746 	elf_flagdata(obj->efile.idlist, ELF_C_SET, ELF_F_DIRTY);
747 
748 	err = elf_update(obj->efile.elf, ELF_C_WRITE);
749 	if (err < 0) {
750 		pr_err("FAILED elf_update(WRITE): %s\n",
751 			elf_errmsg(-1));
752 	}
753 
754 	pr_debug("update %s for %s\n",
755 		 err >= 0 ? "ok" : "failed", obj->path);
756 	return err < 0 ? -1 : 0;
757 }
758 
759 static const char * const resolve_btfids_usage[] = {
760 	"resolve_btfids [<options>] <ELF object>",
761 	NULL
762 };
763 
764 int main(int argc, const char **argv)
765 {
766 	struct object obj = {
767 		.efile = {
768 			.idlist_shndx  = -1,
769 			.symbols_shndx = -1,
770 		},
771 		.structs  = RB_ROOT,
772 		.unions   = RB_ROOT,
773 		.typedefs = RB_ROOT,
774 		.funcs    = RB_ROOT,
775 		.sets     = RB_ROOT,
776 	};
777 	struct option btfid_options[] = {
778 		OPT_INCR('v', "verbose", &verbose,
779 			 "be more verbose (show errors, etc)"),
780 		OPT_STRING(0, "btf", &obj.btf, "BTF data",
781 			   "BTF data"),
782 		OPT_STRING('b', "btf_base", &obj.base_btf_path, "file",
783 			   "path of file providing base BTF"),
784 		OPT_END()
785 	};
786 	int err = -1;
787 
788 	argc = parse_options(argc, argv, btfid_options, resolve_btfids_usage,
789 			     PARSE_OPT_STOP_AT_NON_OPTION);
790 	if (argc != 1)
791 		usage_with_options(resolve_btfids_usage, btfid_options);
792 
793 	obj.path = argv[0];
794 
795 	if (elf_collect(&obj))
796 		goto out;
797 
798 	/*
799 	 * We did not find .BTF_ids section or symbols section,
800 	 * nothing to do..
801 	 */
802 	if (obj.efile.idlist_shndx == -1 ||
803 	    obj.efile.symbols_shndx == -1) {
804 		pr_debug("Cannot find .BTF_ids or symbols sections, nothing to do\n");
805 		err = 0;
806 		goto out;
807 	}
808 
809 	if (symbols_collect(&obj))
810 		goto out;
811 
812 	if (symbols_resolve(&obj))
813 		goto out;
814 
815 	if (symbols_patch(&obj))
816 		goto out;
817 
818 	err = 0;
819 out:
820 	if (obj.efile.elf) {
821 		elf_end(obj.efile.elf);
822 		close(obj.efile.fd);
823 	}
824 	return err;
825 }
826