tools/bpf/resolve_btfids/main.c

   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 static int warnings;
 145
 146 static int eprintf(int level, int var, const char *fmt, ...)
 147 {
 148         va_list args;
 149         int ret = 0;
 150
 151         if (var >= level) {
 152                 va_start(args, fmt);
 153                 ret = vfprintf(stderr, fmt, args);
 154                 va_end(args);
 155         }
 156         return ret;
 157 }
 158
 159 #ifndef pr_fmt
 160 #define pr_fmt(fmt) fmt
 161 #endif
 162
 163 #define pr_debug(fmt, ...) \
 164         eprintf(1, verbose, pr_fmt(fmt), ##__VA_ARGS__)
 165 #define pr_debugN(n, fmt, ...) \
 166         eprintf(n, verbose, pr_fmt(fmt), ##__VA_ARGS__)
 167 #define pr_debug2(fmt, ...) pr_debugN(2, pr_fmt(fmt), ##__VA_ARGS__)
 168 #define pr_err(fmt, ...) \
 169         eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)
 170 #define pr_info(fmt, ...) \
 171         eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)
 172
 173 static bool is_btf_id(const char *name)
 174 {
 175         return name && !strncmp(name, BTF_ID_PREFIX, sizeof(BTF_ID_PREFIX) - 1);
 176 }
 177
 178 static struct btf_id *btf_id__find(struct rb_root *root, const char *name)
 179 {
 180         struct rb_node *p = root->rb_node;
 181         struct btf_id *id;
 182         int cmp;
 183
 184         while (p) {
 185                 id = rb_entry(p, struct btf_id, rb_node);
 186                 cmp = strcmp(id->name, name);
 187                 if (cmp < 0)
 188                         p = p->rb_left;
 189                 else if (cmp > 0)
 190                         p = p->rb_right;
 191                 else
 192                         return id;
 193         }
 194         return NULL;
 195 }
 196
 197 static struct btf_id *
 198 btf_id__add(struct rb_root *root, char *name, bool unique)
 199 {
 200         struct rb_node **p = &root->rb_node;
 201         struct rb_node *parent = NULL;
 202         struct btf_id *id;
 203         int cmp;
 204
 205         while (*p != NULL) {
 206                 parent = *p;
 207                 id = rb_entry(parent, struct btf_id, rb_node);
 208                 cmp = strcmp(id->name, name);
 209                 if (cmp < 0)
 210                         p = &(*p)->rb_left;
 211                 else if (cmp > 0)
 212                         p = &(*p)->rb_right;
 213                 else
 214                         return unique ? NULL : id;
 215         }
 216
 217         id = zalloc(sizeof(*id));
 218         if (id) {
 219                 pr_debug("adding symbol %s\n", name);
 220                 id->name = name;
 221                 rb_link_node(&id->rb_node, parent, p);
 222                 rb_insert_color(&id->rb_node, root);
 223         }
 224         return id;
 225 }
 226
 227 static char *get_id(const char *prefix_end)
 228 {
 229         /*
 230          * __BTF_ID__func__vfs_truncate__0
 231          * prefix_end =  ^
 232          * pos        =    ^
 233          */
 234         int len = strlen(prefix_end);
 235         int pos = sizeof("__") - 1;
 236         char *p, *id;
 237
 238         if (pos >= len)
 239                 return NULL;
 240
 241         id = strdup(prefix_end + pos);
 242         if (id) {
 243                 /*
 244                  * __BTF_ID__func__vfs_truncate__0
 245                  * id =            ^
 246                  *
 247                  * cut the unique id part
 248                  */
 249                 p = strrchr(id, '_');
 250                 p--;
 251                 if (*p != '_') {
 252                         free(id);
 253                         return NULL;
 254                 }
 255                 *p = '\0';
 256         }
 257         return id;
 258 }
 259
 260 static struct btf_id *add_set(struct object *obj, char *name, bool is_set8)
 261 {
 262         /*
 263          * __BTF_ID__set__name
 264          * name =    ^
 265          * id   =         ^
 266          */
 267         char *id = name + (is_set8 ? sizeof(BTF_SET8 "__") : sizeof(BTF_SET "__")) - 1;
 268         int len = strlen(name);
 269
 270         if (id >= name + len) {
 271                 pr_err("FAILED to parse set name: %s\n", name);
 272                 return NULL;
 273         }
 274
 275         return btf_id__add(&obj->sets, id, true);
 276 }
 277
 278 static struct btf_id *add_symbol(struct rb_root *root, char *name, size_t size)
 279 {
 280         char *id;
 281
 282         id = get_id(name + size);
 283         if (!id) {
 284                 pr_err("FAILED to parse symbol name: %s\n", name);
 285                 return NULL;
 286         }
 287
 288         return btf_id__add(root, id, false);
 289 }
 290
 291 /* Older libelf.h and glibc elf.h might not yet define the ELF compression types. */
 292 #ifndef SHF_COMPRESSED
 293 #define SHF_COMPRESSED (1 << 11) /* Section with compressed data. */
 294 #endif
 295
 296 /*
 297  * The data of compressed section should be aligned to 4
 298  * (for 32bit) or 8 (for 64 bit) bytes. The binutils ld
 299  * sets sh_addralign to 1, which makes libelf fail with
 300  * misaligned section error during the update:
 301  *    FAILED elf_update(WRITE): invalid section alignment
 302  *
 303  * While waiting for ld fix, we fix the compressed sections
 304  * sh_addralign value manualy.
 305  */
 306 static int compressed_section_fix(Elf *elf, Elf_Scn *scn, GElf_Shdr *sh)
 307 {
 308         int expected = gelf_getclass(elf) == ELFCLASS32 ? 4 : 8;
 309
 310         if (!(sh->sh_flags & SHF_COMPRESSED))
 311                 return 0;
 312
 313         if (sh->sh_addralign == expected)
 314                 return 0;
 315
 316         pr_debug2(" - fixing wrong alignment sh_addralign %u, expected %u\n",
 317                   sh->sh_addralign, expected);
 318
 319         sh->sh_addralign = expected;
 320
 321         if (gelf_update_shdr(scn, sh) == 0) {
 322                 pr_err("FAILED cannot update section header: %s\n",
 323                         elf_errmsg(-1));
 324                 return -1;
 325         }
 326         return 0;
 327 }
 328
 329 static int elf_collect(struct object *obj)
 330 {
 331         Elf_Scn *scn = NULL;
 332         size_t shdrstrndx;
 333         GElf_Ehdr ehdr;
 334         int idx = 0;
 335         Elf *elf;
 336         int fd;
 337
 338         fd = open(obj->path, O_RDWR, 0666);
 339         if (fd == -1) {
 340                 pr_err("FAILED cannot open %s: %s\n",
 341                         obj->path, strerror(errno));
 342                 return -1;
 343         }
 344
 345         elf_version(EV_CURRENT);
 346
 347         elf = elf_begin(fd, ELF_C_RDWR_MMAP, NULL);
 348         if (!elf) {
 349                 close(fd);
 350                 pr_err("FAILED cannot create ELF descriptor: %s\n",
 351                         elf_errmsg(-1));
 352                 return -1;
 353         }
 354
 355         obj->efile.fd  = fd;
 356         obj->efile.elf = elf;
 357
 358         elf_flagelf(elf, ELF_C_SET, ELF_F_LAYOUT);
 359
 360         if (elf_getshdrstrndx(elf, &shdrstrndx) != 0) {
 361                 pr_err("FAILED cannot get shdr str ndx\n");
 362                 return -1;
 363         }
 364
 365         if (gelf_getehdr(obj->efile.elf, &ehdr) == NULL) {
 366                 pr_err("FAILED cannot get ELF header: %s\n",
 367                         elf_errmsg(-1));
 368                 return -1;
 369         }
 370         obj->efile.encoding = ehdr.e_ident[EI_DATA];
 371
 372         /*
 373          * Scan all the elf sections and look for save data
 374          * from .BTF_ids section and symbols.
 375          */
 376         while ((scn = elf_nextscn(elf, scn)) != NULL) {
 377                 Elf_Data *data;
 378                 GElf_Shdr sh;
 379                 char *name;
 380
 381                 idx++;
 382                 if (gelf_getshdr(scn, &sh) != &sh) {
 383                         pr_err("FAILED get section(%d) header\n", idx);
 384                         return -1;
 385                 }
 386
 387                 name = elf_strptr(elf, shdrstrndx, sh.sh_name);
 388                 if (!name) {
 389                         pr_err("FAILED get section(%d) name\n", idx);
 390                         return -1;
 391                 }
 392
 393                 data = elf_getdata(scn, 0);
 394                 if (!data) {
 395                         pr_err("FAILED to get section(%d) data from %s\n",
 396                                 idx, name);
 397                         return -1;
 398                 }
 399
 400                 pr_debug2("section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
 401                           idx, name, (unsigned long) data->d_size,
 402                           (int) sh.sh_link, (unsigned long) sh.sh_flags,
 403                           (int) sh.sh_type);
 404
 405                 if (sh.sh_type == SHT_SYMTAB) {
 406                         obj->efile.symbols       = data;
 407                         obj->efile.symbols_shndx = idx;
 408                         obj->efile.strtabidx     = sh.sh_link;
 409                 } else if (!strcmp(name, BTF_IDS_SECTION)) {
 410                         obj->efile.idlist       = data;
 411                         obj->efile.idlist_shndx = idx;
 412                         obj->efile.idlist_addr  = sh.sh_addr;
 413                 } else if (!strcmp(name, BTF_BASE_ELF_SEC)) {
 414                         /* If a .BTF.base section is found, do not resolve
 415                          * BTF ids relative to vmlinux; resolve relative
 416                          * to the .BTF.base section instead.  btf__parse_split()
 417                          * will take care of this once the base BTF it is
 418                          * passed is NULL.
 419                          */
 420                         obj->base_btf_path = NULL;
 421                 }
 422
 423                 if (compressed_section_fix(elf, scn, &sh))
 424                         return -1;
 425         }
 426
 427         return 0;
 428 }
 429
 430 static int symbols_collect(struct object *obj)
 431 {
 432         Elf_Scn *scn = NULL;
 433         int n, i;
 434         GElf_Shdr sh;
 435         char *name;
 436
 437         scn = elf_getscn(obj->efile.elf, obj->efile.symbols_shndx);
 438         if (!scn)
 439                 return -1;
 440
 441         if (gelf_getshdr(scn, &sh) != &sh)
 442                 return -1;
 443
 444         n = sh.sh_size / sh.sh_entsize;
 445
 446         /*
 447          * Scan symbols and look for the ones starting with
 448          * __BTF_ID__* over .BTF_ids section.
 449          */
 450         for (i = 0; i < n; i++) {
 451                 char *prefix;
 452                 struct btf_id *id;
 453                 GElf_Sym sym;
 454
 455                 if (!gelf_getsym(obj->efile.symbols, i, &sym))
 456                         return -1;
 457
 458                 if (sym.st_shndx != obj->efile.idlist_shndx)
 459                         continue;
 460
 461                 name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
 462                                   sym.st_name);
 463
 464                 if (!is_btf_id(name))
 465                         continue;
 466
 467                 /*
 468                  * __BTF_ID__TYPE__vfs_truncate__0
 469                  * prefix =  ^
 470                  */
 471                 prefix = name + sizeof(BTF_ID_PREFIX) - 1;
 472
 473                 /* struct */
 474                 if (!strncmp(prefix, BTF_STRUCT, sizeof(BTF_STRUCT) - 1)) {
 475                         obj->nr_structs++;
 476                         id = add_symbol(&obj->structs, prefix, sizeof(BTF_STRUCT) - 1);
 477                 /* union  */
 478                 } else if (!strncmp(prefix, BTF_UNION, sizeof(BTF_UNION) - 1)) {
 479                         obj->nr_unions++;
 480                         id = add_symbol(&obj->unions, prefix, sizeof(BTF_UNION) - 1);
 481                 /* typedef */
 482                 } else if (!strncmp(prefix, BTF_TYPEDEF, sizeof(BTF_TYPEDEF) - 1)) {
 483                         obj->nr_typedefs++;
 484                         id = add_symbol(&obj->typedefs, prefix, sizeof(BTF_TYPEDEF) - 1);
 485                 /* func */
 486                 } else if (!strncmp(prefix, BTF_FUNC, sizeof(BTF_FUNC) - 1)) {
 487                         obj->nr_funcs++;
 488                         id = add_symbol(&obj->funcs, prefix, sizeof(BTF_FUNC) - 1);
 489                 /* set8 */
 490                 } else if (!strncmp(prefix, BTF_SET8, sizeof(BTF_SET8) - 1)) {
 491                         id = add_set(obj, prefix, true);
 492                         /*
 493                          * SET8 objects store list's count, which is encoded
 494                          * in symbol's size, together with 'cnt' field hence
 495                          * that - 1.
 496                          */
 497                         if (id) {
 498                                 id->cnt = sym.st_size / sizeof(uint64_t) - 1;
 499                                 id->is_set8 = true;
 500                         }
 501                 /* set */
 502                 } else if (!strncmp(prefix, BTF_SET, sizeof(BTF_SET) - 1)) {
 503                         id = add_set(obj, prefix, false);
 504                         /*
 505                          * SET objects store list's count, which is encoded
 506                          * in symbol's size, together with 'cnt' field hence
 507                          * that - 1.
 508                          */
 509                         if (id) {
 510                                 id->cnt = sym.st_size / sizeof(int) - 1;
 511                                 id->is_set = true;
 512                         }
 513                 } else {
 514                         pr_err("FAILED unsupported prefix %s\n", prefix);
 515                         return -1;
 516                 }
 517
 518                 if (!id)
 519                         return -ENOMEM;
 520
 521                 if (id->addr_cnt >= ADDR_CNT) {
 522                         pr_err("FAILED symbol %s crossed the number of allowed lists\n",
 523                                 id->name);
 524                         return -1;
 525                 }
 526                 id->addr[id->addr_cnt++] = sym.st_value;
 527         }
 528
 529         return 0;
 530 }
 531
 532 static int symbols_resolve(struct object *obj)
 533 {
 534         int nr_typedefs = obj->nr_typedefs;
 535         int nr_structs  = obj->nr_structs;
 536         int nr_unions   = obj->nr_unions;
 537         int nr_funcs    = obj->nr_funcs;
 538         struct btf *base_btf = NULL;
 539         int err, type_id;
 540         struct btf *btf;
 541         __u32 nr_types;
 542
 543         if (obj->base_btf_path) {
 544                 base_btf = btf__parse(obj->base_btf_path, NULL);
 545                 err = libbpf_get_error(base_btf);
 546                 if (err) {
 547                         pr_err("FAILED: load base BTF from %s: %s\n",
 548                                obj->base_btf_path, strerror(-err));
 549                         return -1;
 550                 }
 551         }
 552
 553         btf = btf__parse_split(obj->btf ?: obj->path, base_btf);
 554         err = libbpf_get_error(btf);
 555         if (err) {
 556                 pr_err("FAILED: load BTF from %s: %s\n",
 557                         obj->btf ?: obj->path, strerror(-err));
 558                 goto out;
 559         }
 560
 561         err = -1;
 562         nr_types = btf__type_cnt(btf);
 563
 564         /*
 565          * Iterate all the BTF types and search for collected symbol IDs.
 566          */
 567         for (type_id = 1; type_id < nr_types; type_id++) {
 568                 const struct btf_type *type;
 569                 struct rb_root *root;
 570                 struct btf_id *id;
 571                 const char *str;
 572                 int *nr;
 573
 574                 type = btf__type_by_id(btf, type_id);
 575                 if (!type) {
 576                         pr_err("FAILED: malformed BTF, can't resolve type for ID %d\n",
 577                                 type_id);
 578                         goto out;
 579                 }
 580
 581                 if (btf_is_func(type) && nr_funcs) {
 582                         nr   = &nr_funcs;
 583                         root = &obj->funcs;
 584                 } else if (btf_is_struct(type) && nr_structs) {
 585                         nr   = &nr_structs;
 586                         root = &obj->structs;
 587                 } else if (btf_is_union(type) && nr_unions) {
 588                         nr   = &nr_unions;
 589                         root = &obj->unions;
 590                 } else if (btf_is_typedef(type) && nr_typedefs) {
 591                         nr   = &nr_typedefs;
 592                         root = &obj->typedefs;
 593                 } else
 594                         continue;
 595
 596                 str = btf__name_by_offset(btf, type->name_off);
 597                 if (!str) {
 598                         pr_err("FAILED: malformed BTF, can't resolve name for ID %d\n",
 599                                 type_id);
 600                         goto out;
 601                 }
 602
 603                 id = btf_id__find(root, str);
 604                 if (id) {
 605                         if (id->id) {
 606                                 pr_info("WARN: multiple IDs found for '%s': %d, %d - using %d\n",
 607                                         str, id->id, type_id, id->id);
 608                                 warnings++;
 609                         } else {
 610                                 id->id = type_id;
 611                                 (*nr)--;
 612                         }
 613                 }
 614         }
 615
 616         err = 0;
 617 out:
 618         btf__free(base_btf);
 619         btf__free(btf);
 620         return err;
 621 }
 622
 623 static int id_patch(struct object *obj, struct btf_id *id)
 624 {
 625         Elf_Data *data = obj->efile.idlist;
 626         int *ptr = data->d_buf;
 627         int i;
 628
 629         /* For set, set8, id->id may be 0 */
 630         if (!id->id && !id->is_set && !id->is_set8) {
 631                 pr_err("WARN: resolve_btfids: unresolved symbol %s\n", id->name);
 632                 warnings++;
 633         }
 634
 635         for (i = 0; i < id->addr_cnt; i++) {
 636                 unsigned long addr = id->addr[i];
 637                 unsigned long idx = addr - obj->efile.idlist_addr;
 638
 639                 pr_debug("patching addr %5lu: ID %7d [%s]\n",
 640                          idx, id->id, id->name);
 641
 642                 if (idx >= data->d_size) {
 643                         pr_err("FAILED patching index %lu out of bounds %lu\n",
 644                                 idx, data->d_size);
 645                         return -1;
 646                 }
 647
 648                 idx = idx / sizeof(int);
 649                 ptr[idx] = id->id;
 650         }
 651
 652         return 0;
 653 }
 654
 655 static int __symbols_patch(struct object *obj, struct rb_root *root)
 656 {
 657         struct rb_node *next;
 658         struct btf_id *id;
 659
 660         next = rb_first(root);
 661         while (next) {
 662                 id = rb_entry(next, struct btf_id, rb_node);
 663
 664                 if (id_patch(obj, id))
 665                         return -1;
 666
 667                 next = rb_next(next);
 668         }
 669         return 0;
 670 }
 671
 672 static int cmp_id(const void *pa, const void *pb)
 673 {
 674         const int *a = pa, *b = pb;
 675
 676         return *a - *b;
 677 }
 678
 679 static int sets_patch(struct object *obj)
 680 {
 681         Elf_Data *data = obj->efile.idlist;
 682         struct rb_node *next;
 683
 684         next = rb_first(&obj->sets);
 685         while (next) {
 686                 struct btf_id_set8 *set8 = NULL;
 687                 struct btf_id_set *set = NULL;
 688                 unsigned long addr, off;
 689                 struct btf_id *id;
 690
 691                 id   = rb_entry(next, struct btf_id, rb_node);
 692                 addr = id->addr[0];
 693                 off = addr - obj->efile.idlist_addr;
 694
 695                 /* sets are unique */
 696                 if (id->addr_cnt != 1) {
 697                         pr_err("FAILED malformed data for set '%s'\n",
 698                                 id->name);
 699                         return -1;
 700                 }
 701
 702                 if (id->is_set) {
 703                         set = data->d_buf + off;
 704                         qsort(set->ids, set->cnt, sizeof(set->ids[0]), cmp_id);
 705                 } else {
 706                         set8 = data->d_buf + off;
 707                         /*
 708                          * Make sure id is at the beginning of the pairs
 709                          * struct, otherwise the below qsort would not work.
 710                          */
 711                         BUILD_BUG_ON((u32 *)set8->pairs != &set8->pairs[0].id);
 712                         qsort(set8->pairs, set8->cnt, sizeof(set8->pairs[0]), cmp_id);
 713
 714                         /*
 715                          * When ELF endianness does not match endianness of the
 716                          * host, libelf will do the translation when updating
 717                          * the ELF. This, however, corrupts SET8 flags which are
 718                          * already in the target endianness. So, let's bswap
 719                          * them to the host endianness and libelf will then
 720                          * correctly translate everything.
 721                          */
 722                         if (obj->efile.encoding != ELFDATANATIVE) {
 723                                 int i;
 724
 725                                 set8->flags = bswap_32(set8->flags);
 726                                 for (i = 0; i < set8->cnt; i++) {
 727                                         set8->pairs[i].flags =
 728                                                 bswap_32(set8->pairs[i].flags);
 729                                 }
 730                         }
 731                 }
 732
 733                 pr_debug("sorting  addr %5lu: cnt %6d [%s]\n",
 734                          off, id->is_set ? set->cnt : set8->cnt, id->name);
 735
 736                 next = rb_next(next);
 737         }
 738         return 0;
 739 }
 740
 741 static int symbols_patch(struct object *obj)
 742 {
 743         off_t err;
 744
 745         if (__symbols_patch(obj, &obj->structs)  ||
 746             __symbols_patch(obj, &obj->unions)   ||
 747             __symbols_patch(obj, &obj->typedefs) ||
 748             __symbols_patch(obj, &obj->funcs)    ||
 749             __symbols_patch(obj, &obj->sets))
 750                 return -1;
 751
 752         if (sets_patch(obj))
 753                 return -1;
 754
 755         /* Set type to ensure endian translation occurs. */
 756         obj->efile.idlist->d_type = ELF_T_WORD;
 757
 758         elf_flagdata(obj->efile.idlist, ELF_C_SET, ELF_F_DIRTY);
 759
 760         err = elf_update(obj->efile.elf, ELF_C_WRITE);
 761         if (err < 0) {
 762                 pr_err("FAILED elf_update(WRITE): %s\n",
 763                         elf_errmsg(-1));
 764         }
 765
 766         pr_debug("update %s for %s\n",
 767                  err >= 0 ? "ok" : "failed", obj->path);
 768         return err < 0 ? -1 : 0;
 769 }
 770
 771 static const char * const resolve_btfids_usage[] = {
 772         "resolve_btfids [<options>] <ELF object>",
 773         NULL
 774 };
 775
 776 int main(int argc, const char **argv)
 777 {
 778         struct object obj = {
 779                 .efile = {
 780                         .idlist_shndx  = -1,
 781                         .symbols_shndx = -1,
 782                 },
 783                 .structs  = RB_ROOT,
 784                 .unions   = RB_ROOT,
 785                 .typedefs = RB_ROOT,
 786                 .funcs    = RB_ROOT,
 787                 .sets     = RB_ROOT,
 788         };
 789         bool fatal_warnings = false;
 790         struct option btfid_options[] = {
 791                 OPT_INCR('v', "verbose", &verbose,
 792                          "be more verbose (show errors, etc)"),
 793                 OPT_STRING(0, "btf", &obj.btf, "BTF data",
 794                            "BTF data"),
 795                 OPT_STRING('b', "btf_base", &obj.base_btf_path, "file",
 796                            "path of file providing base BTF"),
 797                 OPT_BOOLEAN(0, "fatal_warnings", &fatal_warnings,
 798                             "turn warnings into errors"),
 799                 OPT_END()
 800         };
 801         int err = -1;
 802
 803         argc = parse_options(argc, argv, btfid_options, resolve_btfids_usage,
 804                              PARSE_OPT_STOP_AT_NON_OPTION);
 805         if (argc != 1)
 806                 usage_with_options(resolve_btfids_usage, btfid_options);
 807
 808         obj.path = argv[0];
 809
 810         if (elf_collect(&obj))
 811                 goto out;
 812
 813         /*
 814          * We did not find .BTF_ids section or symbols section,
 815          * nothing to do..
 816          */
 817         if (obj.efile.idlist_shndx == -1 ||
 818             obj.efile.symbols_shndx == -1) {
 819                 pr_debug("Cannot find .BTF_ids or symbols sections, nothing to do\n");
 820                 err = 0;
 821                 goto out;
 822         }
 823
 824         if (symbols_collect(&obj))
 825                 goto out;
 826
 827         if (symbols_resolve(&obj))
 828                 goto out;
 829
 830         if (symbols_patch(&obj))
 831                 goto out;
 832
 833         if (!(fatal_warnings && warnings))
 834                 err = 0;
 835 out:
 836         if (obj.efile.elf) {
 837                 elf_end(obj.efile.elf);
 838                 close(obj.efile.fd);
 839         }
 840         return err;
 841 }