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TOMOYO Linux Cross Reference
Linux/tools/bpf/resolve_btfids/main.c

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  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                 } else if (!strcmp(name, BTF_BASE_ELF_SEC)) {
413                         /* If a .BTF.base section is found, do not resolve
414                          * BTF ids relative to vmlinux; resolve relative
415                          * to the .BTF.base section instead.  btf__parse_split()
416                          * will take care of this once the base BTF it is
417                          * passed is NULL.
418                          */
419                         obj->base_btf_path = NULL;
420                 }
421 
422                 if (compressed_section_fix(elf, scn, &sh))
423                         return -1;
424         }
425 
426         return 0;
427 }
428 
429 static int symbols_collect(struct object *obj)
430 {
431         Elf_Scn *scn = NULL;
432         int n, i;
433         GElf_Shdr sh;
434         char *name;
435 
436         scn = elf_getscn(obj->efile.elf, obj->efile.symbols_shndx);
437         if (!scn)
438                 return -1;
439 
440         if (gelf_getshdr(scn, &sh) != &sh)
441                 return -1;
442 
443         n = sh.sh_size / sh.sh_entsize;
444 
445         /*
446          * Scan symbols and look for the ones starting with
447          * __BTF_ID__* over .BTF_ids section.
448          */
449         for (i = 0; i < n; i++) {
450                 char *prefix;
451                 struct btf_id *id;
452                 GElf_Sym sym;
453 
454                 if (!gelf_getsym(obj->efile.symbols, i, &sym))
455                         return -1;
456 
457                 if (sym.st_shndx != obj->efile.idlist_shndx)
458                         continue;
459 
460                 name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
461                                   sym.st_name);
462 
463                 if (!is_btf_id(name))
464                         continue;
465 
466                 /*
467                  * __BTF_ID__TYPE__vfs_truncate__0
468                  * prefix =  ^
469                  */
470                 prefix = name + sizeof(BTF_ID_PREFIX) - 1;
471 
472                 /* struct */
473                 if (!strncmp(prefix, BTF_STRUCT, sizeof(BTF_STRUCT) - 1)) {
474                         obj->nr_structs++;
475                         id = add_symbol(&obj->structs, prefix, sizeof(BTF_STRUCT) - 1);
476                 /* union  */
477                 } else if (!strncmp(prefix, BTF_UNION, sizeof(BTF_UNION) - 1)) {
478                         obj->nr_unions++;
479                         id = add_symbol(&obj->unions, prefix, sizeof(BTF_UNION) - 1);
480                 /* typedef */
481                 } else if (!strncmp(prefix, BTF_TYPEDEF, sizeof(BTF_TYPEDEF) - 1)) {
482                         obj->nr_typedefs++;
483                         id = add_symbol(&obj->typedefs, prefix, sizeof(BTF_TYPEDEF) - 1);
484                 /* func */
485                 } else if (!strncmp(prefix, BTF_FUNC, sizeof(BTF_FUNC) - 1)) {
486                         obj->nr_funcs++;
487                         id = add_symbol(&obj->funcs, prefix, sizeof(BTF_FUNC) - 1);
488                 /* set8 */
489                 } else if (!strncmp(prefix, BTF_SET8, sizeof(BTF_SET8) - 1)) {
490                         id = add_set(obj, prefix, true);
491                         /*
492                          * SET8 objects store list's count, which is encoded
493                          * in symbol's size, together with 'cnt' field hence
494                          * that - 1.
495                          */
496                         if (id) {
497                                 id->cnt = sym.st_size / sizeof(uint64_t) - 1;
498                                 id->is_set8 = true;
499                         }
500                 /* set */
501                 } else if (!strncmp(prefix, BTF_SET, sizeof(BTF_SET) - 1)) {
502                         id = add_set(obj, prefix, false);
503                         /*
504                          * SET objects store list's count, which is encoded
505                          * in symbol's size, together with 'cnt' field hence
506                          * that - 1.
507                          */
508                         if (id) {
509                                 id->cnt = sym.st_size / sizeof(int) - 1;
510                                 id->is_set = true;
511                         }
512                 } else {
513                         pr_err("FAILED unsupported prefix %s\n", prefix);
514                         return -1;
515                 }
516 
517                 if (!id)
518                         return -ENOMEM;
519 
520                 if (id->addr_cnt >= ADDR_CNT) {
521                         pr_err("FAILED symbol %s crossed the number of allowed lists\n",
522                                 id->name);
523                         return -1;
524                 }
525                 id->addr[id->addr_cnt++] = sym.st_value;
526         }
527 
528         return 0;
529 }
530 
531 static int symbols_resolve(struct object *obj)
532 {
533         int nr_typedefs = obj->nr_typedefs;
534         int nr_structs  = obj->nr_structs;
535         int nr_unions   = obj->nr_unions;
536         int nr_funcs    = obj->nr_funcs;
537         struct btf *base_btf = NULL;
538         int err, type_id;
539         struct btf *btf;
540         __u32 nr_types;
541 
542         if (obj->base_btf_path) {
543                 base_btf = btf__parse(obj->base_btf_path, NULL);
544                 err = libbpf_get_error(base_btf);
545                 if (err) {
546                         pr_err("FAILED: load base BTF from %s: %s\n",
547                                obj->base_btf_path, strerror(-err));
548                         return -1;
549                 }
550         }
551 
552         btf = btf__parse_split(obj->btf ?: obj->path, base_btf);
553         err = libbpf_get_error(btf);
554         if (err) {
555                 pr_err("FAILED: load BTF from %s: %s\n",
556                         obj->btf ?: obj->path, strerror(-err));
557                 goto out;
558         }
559 
560         err = -1;
561         nr_types = btf__type_cnt(btf);
562 
563         /*
564          * Iterate all the BTF types and search for collected symbol IDs.
565          */
566         for (type_id = 1; type_id < nr_types; type_id++) {
567                 const struct btf_type *type;
568                 struct rb_root *root;
569                 struct btf_id *id;
570                 const char *str;
571                 int *nr;
572 
573                 type = btf__type_by_id(btf, type_id);
574                 if (!type) {
575                         pr_err("FAILED: malformed BTF, can't resolve type for ID %d\n",
576                                 type_id);
577                         goto out;
578                 }
579 
580                 if (btf_is_func(type) && nr_funcs) {
581                         nr   = &nr_funcs;
582                         root = &obj->funcs;
583                 } else if (btf_is_struct(type) && nr_structs) {
584                         nr   = &nr_structs;
585                         root = &obj->structs;
586                 } else if (btf_is_union(type) && nr_unions) {
587                         nr   = &nr_unions;
588                         root = &obj->unions;
589                 } else if (btf_is_typedef(type) && nr_typedefs) {
590                         nr   = &nr_typedefs;
591                         root = &obj->typedefs;
592                 } else
593                         continue;
594 
595                 str = btf__name_by_offset(btf, type->name_off);
596                 if (!str) {
597                         pr_err("FAILED: malformed BTF, can't resolve name for ID %d\n",
598                                 type_id);
599                         goto out;
600                 }
601 
602                 id = btf_id__find(root, str);
603                 if (id) {
604                         if (id->id) {
605                                 pr_info("WARN: multiple IDs found for '%s': %d, %d - using %d\n",
606                                         str, id->id, type_id, id->id);
607                         } else {
608                                 id->id = type_id;
609                                 (*nr)--;
610                         }
611                 }
612         }
613 
614         err = 0;
615 out:
616         btf__free(base_btf);
617         btf__free(btf);
618         return err;
619 }
620 
621 static int id_patch(struct object *obj, struct btf_id *id)
622 {
623         Elf_Data *data = obj->efile.idlist;
624         int *ptr = data->d_buf;
625         int i;
626 
627         /* For set, set8, id->id may be 0 */
628         if (!id->id && !id->is_set && !id->is_set8)
629                 pr_err("WARN: resolve_btfids: unresolved symbol %s\n", id->name);
630 
631         for (i = 0; i < id->addr_cnt; i++) {
632                 unsigned long addr = id->addr[i];
633                 unsigned long idx = addr - obj->efile.idlist_addr;
634 
635                 pr_debug("patching addr %5lu: ID %7d [%s]\n",
636                          idx, id->id, id->name);
637 
638                 if (idx >= data->d_size) {
639                         pr_err("FAILED patching index %lu out of bounds %lu\n",
640                                 idx, data->d_size);
641                         return -1;
642                 }
643 
644                 idx = idx / sizeof(int);
645                 ptr[idx] = id->id;
646         }
647 
648         return 0;
649 }
650 
651 static int __symbols_patch(struct object *obj, struct rb_root *root)
652 {
653         struct rb_node *next;
654         struct btf_id *id;
655 
656         next = rb_first(root);
657         while (next) {
658                 id = rb_entry(next, struct btf_id, rb_node);
659 
660                 if (id_patch(obj, id))
661                         return -1;
662 
663                 next = rb_next(next);
664         }
665         return 0;
666 }
667 
668 static int cmp_id(const void *pa, const void *pb)
669 {
670         const int *a = pa, *b = pb;
671 
672         return *a - *b;
673 }
674 
675 static int sets_patch(struct object *obj)
676 {
677         Elf_Data *data = obj->efile.idlist;
678         struct rb_node *next;
679 
680         next = rb_first(&obj->sets);
681         while (next) {
682                 struct btf_id_set8 *set8;
683                 struct btf_id_set *set;
684                 unsigned long addr, off;
685                 struct btf_id *id;
686 
687                 id   = rb_entry(next, struct btf_id, rb_node);
688                 addr = id->addr[0];
689                 off = addr - obj->efile.idlist_addr;
690 
691                 /* sets are unique */
692                 if (id->addr_cnt != 1) {
693                         pr_err("FAILED malformed data for set '%s'\n",
694                                 id->name);
695                         return -1;
696                 }
697 
698                 if (id->is_set) {
699                         set = data->d_buf + off;
700                         qsort(set->ids, set->cnt, sizeof(set->ids[0]), cmp_id);
701                 } else {
702                         set8 = data->d_buf + off;
703                         /*
704                          * Make sure id is at the beginning of the pairs
705                          * struct, otherwise the below qsort would not work.
706                          */
707                         BUILD_BUG_ON((u32 *)set8->pairs != &set8->pairs[0].id);
708                         qsort(set8->pairs, set8->cnt, sizeof(set8->pairs[0]), cmp_id);
709 
710                         /*
711                          * When ELF endianness does not match endianness of the
712                          * host, libelf will do the translation when updating
713                          * the ELF. This, however, corrupts SET8 flags which are
714                          * already in the target endianness. So, let's bswap
715                          * them to the host endianness and libelf will then
716                          * correctly translate everything.
717                          */
718                         if (obj->efile.encoding != ELFDATANATIVE) {
719                                 int i;
720 
721                                 set8->flags = bswap_32(set8->flags);
722                                 for (i = 0; i < set8->cnt; i++) {
723                                         set8->pairs[i].flags =
724                                                 bswap_32(set8->pairs[i].flags);
725                                 }
726                         }
727                 }
728 
729                 pr_debug("sorting  addr %5lu: cnt %6d [%s]\n",
730                          off, id->is_set ? set->cnt : set8->cnt, id->name);
731 
732                 next = rb_next(next);
733         }
734         return 0;
735 }
736 
737 static int symbols_patch(struct object *obj)
738 {
739         off_t err;
740 
741         if (__symbols_patch(obj, &obj->structs)  ||
742             __symbols_patch(obj, &obj->unions)   ||
743             __symbols_patch(obj, &obj->typedefs) ||
744             __symbols_patch(obj, &obj->funcs)    ||
745             __symbols_patch(obj, &obj->sets))
746                 return -1;
747 
748         if (sets_patch(obj))
749                 return -1;
750 
751         /* Set type to ensure endian translation occurs. */
752         obj->efile.idlist->d_type = ELF_T_WORD;
753 
754         elf_flagdata(obj->efile.idlist, ELF_C_SET, ELF_F_DIRTY);
755 
756         err = elf_update(obj->efile.elf, ELF_C_WRITE);
757         if (err < 0) {
758                 pr_err("FAILED elf_update(WRITE): %s\n",
759                         elf_errmsg(-1));
760         }
761 
762         pr_debug("update %s for %s\n",
763                  err >= 0 ? "ok" : "failed", obj->path);
764         return err < 0 ? -1 : 0;
765 }
766 
767 static const char * const resolve_btfids_usage[] = {
768         "resolve_btfids [<options>] <ELF object>",
769         NULL
770 };
771 
772 int main(int argc, const char **argv)
773 {
774         struct object obj = {
775                 .efile = {
776                         .idlist_shndx  = -1,
777                         .symbols_shndx = -1,
778                 },
779                 .structs  = RB_ROOT,
780                 .unions   = RB_ROOT,
781                 .typedefs = RB_ROOT,
782                 .funcs    = RB_ROOT,
783                 .sets     = RB_ROOT,
784         };
785         struct option btfid_options[] = {
786                 OPT_INCR('v', "verbose", &verbose,
787                          "be more verbose (show errors, etc)"),
788                 OPT_STRING(0, "btf", &obj.btf, "BTF data",
789                            "BTF data"),
790                 OPT_STRING('b', "btf_base", &obj.base_btf_path, "file",
791                            "path of file providing base BTF"),
792                 OPT_END()
793         };
794         int err = -1;
795 
796         argc = parse_options(argc, argv, btfid_options, resolve_btfids_usage,
797                              PARSE_OPT_STOP_AT_NON_OPTION);
798         if (argc != 1)
799                 usage_with_options(resolve_btfids_usage, btfid_options);
800 
801         obj.path = argv[0];
802 
803         if (elf_collect(&obj))
804                 goto out;
805 
806         /*
807          * We did not find .BTF_ids section or symbols section,
808          * nothing to do..
809          */
810         if (obj.efile.idlist_shndx == -1 ||
811             obj.efile.symbols_shndx == -1) {
812                 pr_debug("Cannot find .BTF_ids or symbols sections, nothing to do\n");
813                 err = 0;
814                 goto out;
815         }
816 
817         if (symbols_collect(&obj))
818                 goto out;
819 
820         if (symbols_resolve(&obj))
821                 goto out;
822 
823         if (symbols_patch(&obj))
824                 goto out;
825 
826         err = 0;
827 out:
828         if (obj.efile.elf) {
829                 elf_end(obj.efile.elf);
830                 close(obj.efile.fd);
831         }
832         return err;
833 }
834 

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