1 /* 2 * Common eBPF ELF object loading operations. 3 * 4 * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org> 5 * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com> 6 * Copyright (C) 2015 Huawei Inc. 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU Lesser General Public 10 * License as published by the Free Software Foundation; 11 * version 2.1 of the License (not later!) 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU Lesser General Public License for more details. 17 * 18 * You should have received a copy of the GNU Lesser General Public 19 * License along with this program; if not, see <http://www.gnu.org/licenses> 20 */ 21 22 #include <stdlib.h> 23 #include <stdio.h> 24 #include <stdarg.h> 25 #include <inttypes.h> 26 #include <string.h> 27 #include <unistd.h> 28 #include <fcntl.h> 29 #include <errno.h> 30 #include <asm/unistd.h> 31 #include <linux/kernel.h> 32 #include <linux/bpf.h> 33 #include <linux/list.h> 34 #include <libelf.h> 35 #include <gelf.h> 36 37 #include "libbpf.h" 38 #include "bpf.h" 39 40 #ifndef EM_BPF 41 #define EM_BPF 247 42 #endif 43 44 #define __printf(a, b) __attribute__((format(printf, a, b))) 45 46 __printf(1, 2) 47 static int __base_pr(const char *format, ...) 48 { 49 va_list args; 50 int err; 51 52 va_start(args, format); 53 err = vfprintf(stderr, format, args); 54 va_end(args); 55 return err; 56 } 57 58 static __printf(1, 2) libbpf_print_fn_t __pr_warning = __base_pr; 59 static __printf(1, 2) libbpf_print_fn_t __pr_info = __base_pr; 60 static __printf(1, 2) libbpf_print_fn_t __pr_debug; 61 62 #define __pr(func, fmt, ...) \ 63 do { \ 64 if ((func)) \ 65 (func)("libbpf: " fmt, ##__VA_ARGS__); \ 66 } while (0) 67 68 #define pr_warning(fmt, ...) __pr(__pr_warning, fmt, ##__VA_ARGS__) 69 #define pr_info(fmt, ...) __pr(__pr_info, fmt, ##__VA_ARGS__) 70 #define pr_debug(fmt, ...) __pr(__pr_debug, fmt, ##__VA_ARGS__) 71 72 void libbpf_set_print(libbpf_print_fn_t warn, 73 libbpf_print_fn_t info, 74 libbpf_print_fn_t debug) 75 { 76 __pr_warning = warn; 77 __pr_info = info; 78 __pr_debug = debug; 79 } 80 81 #define STRERR_BUFSIZE 128 82 83 #define ERRNO_OFFSET(e) ((e) - __LIBBPF_ERRNO__START) 84 #define ERRCODE_OFFSET(c) ERRNO_OFFSET(LIBBPF_ERRNO__##c) 85 #define NR_ERRNO (__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START) 86 87 static const char *libbpf_strerror_table[NR_ERRNO] = { 88 [ERRCODE_OFFSET(LIBELF)] = "Something wrong in libelf", 89 [ERRCODE_OFFSET(FORMAT)] = "BPF object format invalid", 90 [ERRCODE_OFFSET(KVERSION)] = "'version' section incorrect or lost", 91 [ERRCODE_OFFSET(ENDIAN)] = "Endian mismatch", 92 [ERRCODE_OFFSET(INTERNAL)] = "Internal error in libbpf", 93 [ERRCODE_OFFSET(RELOC)] = "Relocation failed", 94 [ERRCODE_OFFSET(VERIFY)] = "Kernel verifier blocks program loading", 95 [ERRCODE_OFFSET(PROG2BIG)] = "Program too big", 96 [ERRCODE_OFFSET(KVER)] = "Incorrect kernel version", 97 [ERRCODE_OFFSET(PROGTYPE)] = "Kernel doesn't support this program type", 98 }; 99 100 int libbpf_strerror(int err, char *buf, size_t size) 101 { 102 if (!buf || !size) 103 return -1; 104 105 err = err > 0 ? err : -err; 106 107 if (err < __LIBBPF_ERRNO__START) { 108 int ret; 109 110 ret = strerror_r(err, buf, size); 111 buf[size - 1] = '\0'; 112 return ret; 113 } 114 115 if (err < __LIBBPF_ERRNO__END) { 116 const char *msg; 117 118 msg = libbpf_strerror_table[ERRNO_OFFSET(err)]; 119 snprintf(buf, size, "%s", msg); 120 buf[size - 1] = '\0'; 121 return 0; 122 } 123 124 snprintf(buf, size, "Unknown libbpf error %d", err); 125 buf[size - 1] = '\0'; 126 return -1; 127 } 128 129 #define CHECK_ERR(action, err, out) do { \ 130 err = action; \ 131 if (err) \ 132 goto out; \ 133 } while(0) 134 135 136 /* Copied from tools/perf/util/util.h */ 137 #ifndef zfree 138 # define zfree(ptr) ({ free(*ptr); *ptr = NULL; }) 139 #endif 140 141 #ifndef zclose 142 # define zclose(fd) ({ \ 143 int ___err = 0; \ 144 if ((fd) >= 0) \ 145 ___err = close((fd)); \ 146 fd = -1; \ 147 ___err; }) 148 #endif 149 150 #ifdef HAVE_LIBELF_MMAP_SUPPORT 151 # define LIBBPF_ELF_C_READ_MMAP ELF_C_READ_MMAP 152 #else 153 # define LIBBPF_ELF_C_READ_MMAP ELF_C_READ 154 #endif 155 156 /* 157 * bpf_prog should be a better name but it has been used in 158 * linux/filter.h. 159 */ 160 struct bpf_program { 161 /* Index in elf obj file, for relocation use. */ 162 int idx; 163 char *section_name; 164 struct bpf_insn *insns; 165 size_t insns_cnt; 166 enum bpf_prog_type type; 167 168 struct { 169 int insn_idx; 170 int map_idx; 171 } *reloc_desc; 172 int nr_reloc; 173 174 struct { 175 int nr; 176 int *fds; 177 } instances; 178 bpf_program_prep_t preprocessor; 179 180 struct bpf_object *obj; 181 void *priv; 182 bpf_program_clear_priv_t clear_priv; 183 }; 184 185 struct bpf_map { 186 int fd; 187 char *name; 188 size_t offset; 189 struct bpf_map_def def; 190 void *priv; 191 bpf_map_clear_priv_t clear_priv; 192 }; 193 194 static LIST_HEAD(bpf_objects_list); 195 196 struct bpf_object { 197 char license[64]; 198 u32 kern_version; 199 200 struct bpf_program *programs; 201 size_t nr_programs; 202 struct bpf_map *maps; 203 size_t nr_maps; 204 205 bool loaded; 206 207 /* 208 * Information when doing elf related work. Only valid if fd 209 * is valid. 210 */ 211 struct { 212 int fd; 213 void *obj_buf; 214 size_t obj_buf_sz; 215 Elf *elf; 216 GElf_Ehdr ehdr; 217 Elf_Data *symbols; 218 size_t strtabidx; 219 struct { 220 GElf_Shdr shdr; 221 Elf_Data *data; 222 } *reloc; 223 int nr_reloc; 224 int maps_shndx; 225 } efile; 226 /* 227 * All loaded bpf_object is linked in a list, which is 228 * hidden to caller. bpf_objects__<func> handlers deal with 229 * all objects. 230 */ 231 struct list_head list; 232 233 void *priv; 234 bpf_object_clear_priv_t clear_priv; 235 236 char path[]; 237 }; 238 #define obj_elf_valid(o) ((o)->efile.elf) 239 240 static void bpf_program__unload(struct bpf_program *prog) 241 { 242 int i; 243 244 if (!prog) 245 return; 246 247 /* 248 * If the object is opened but the program was never loaded, 249 * it is possible that prog->instances.nr == -1. 250 */ 251 if (prog->instances.nr > 0) { 252 for (i = 0; i < prog->instances.nr; i++) 253 zclose(prog->instances.fds[i]); 254 } else if (prog->instances.nr != -1) { 255 pr_warning("Internal error: instances.nr is %d\n", 256 prog->instances.nr); 257 } 258 259 prog->instances.nr = -1; 260 zfree(&prog->instances.fds); 261 } 262 263 static void bpf_program__exit(struct bpf_program *prog) 264 { 265 if (!prog) 266 return; 267 268 if (prog->clear_priv) 269 prog->clear_priv(prog, prog->priv); 270 271 prog->priv = NULL; 272 prog->clear_priv = NULL; 273 274 bpf_program__unload(prog); 275 zfree(&prog->section_name); 276 zfree(&prog->insns); 277 zfree(&prog->reloc_desc); 278 279 prog->nr_reloc = 0; 280 prog->insns_cnt = 0; 281 prog->idx = -1; 282 } 283 284 static int 285 bpf_program__init(void *data, size_t size, char *name, int idx, 286 struct bpf_program *prog) 287 { 288 if (size < sizeof(struct bpf_insn)) { 289 pr_warning("corrupted section '%s'\n", name); 290 return -EINVAL; 291 } 292 293 bzero(prog, sizeof(*prog)); 294 295 prog->section_name = strdup(name); 296 if (!prog->section_name) { 297 pr_warning("failed to alloc name for prog %s\n", 298 name); 299 goto errout; 300 } 301 302 prog->insns = malloc(size); 303 if (!prog->insns) { 304 pr_warning("failed to alloc insns for %s\n", name); 305 goto errout; 306 } 307 prog->insns_cnt = size / sizeof(struct bpf_insn); 308 memcpy(prog->insns, data, 309 prog->insns_cnt * sizeof(struct bpf_insn)); 310 prog->idx = idx; 311 prog->instances.fds = NULL; 312 prog->instances.nr = -1; 313 prog->type = BPF_PROG_TYPE_KPROBE; 314 315 return 0; 316 errout: 317 bpf_program__exit(prog); 318 return -ENOMEM; 319 } 320 321 static int 322 bpf_object__add_program(struct bpf_object *obj, void *data, size_t size, 323 char *name, int idx) 324 { 325 struct bpf_program prog, *progs; 326 int nr_progs, err; 327 328 err = bpf_program__init(data, size, name, idx, &prog); 329 if (err) 330 return err; 331 332 progs = obj->programs; 333 nr_progs = obj->nr_programs; 334 335 progs = realloc(progs, sizeof(progs[0]) * (nr_progs + 1)); 336 if (!progs) { 337 /* 338 * In this case the original obj->programs 339 * is still valid, so don't need special treat for 340 * bpf_close_object(). 341 */ 342 pr_warning("failed to alloc a new program '%s'\n", 343 name); 344 bpf_program__exit(&prog); 345 return -ENOMEM; 346 } 347 348 pr_debug("found program %s\n", prog.section_name); 349 obj->programs = progs; 350 obj->nr_programs = nr_progs + 1; 351 prog.obj = obj; 352 progs[nr_progs] = prog; 353 return 0; 354 } 355 356 static struct bpf_object *bpf_object__new(const char *path, 357 void *obj_buf, 358 size_t obj_buf_sz) 359 { 360 struct bpf_object *obj; 361 362 obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1); 363 if (!obj) { 364 pr_warning("alloc memory failed for %s\n", path); 365 return ERR_PTR(-ENOMEM); 366 } 367 368 strcpy(obj->path, path); 369 obj->efile.fd = -1; 370 371 /* 372 * Caller of this function should also calls 373 * bpf_object__elf_finish() after data collection to return 374 * obj_buf to user. If not, we should duplicate the buffer to 375 * avoid user freeing them before elf finish. 376 */ 377 obj->efile.obj_buf = obj_buf; 378 obj->efile.obj_buf_sz = obj_buf_sz; 379 obj->efile.maps_shndx = -1; 380 381 obj->loaded = false; 382 383 INIT_LIST_HEAD(&obj->list); 384 list_add(&obj->list, &bpf_objects_list); 385 return obj; 386 } 387 388 static void bpf_object__elf_finish(struct bpf_object *obj) 389 { 390 if (!obj_elf_valid(obj)) 391 return; 392 393 if (obj->efile.elf) { 394 elf_end(obj->efile.elf); 395 obj->efile.elf = NULL; 396 } 397 obj->efile.symbols = NULL; 398 399 zfree(&obj->efile.reloc); 400 obj->efile.nr_reloc = 0; 401 zclose(obj->efile.fd); 402 obj->efile.obj_buf = NULL; 403 obj->efile.obj_buf_sz = 0; 404 } 405 406 static int bpf_object__elf_init(struct bpf_object *obj) 407 { 408 int err = 0; 409 GElf_Ehdr *ep; 410 411 if (obj_elf_valid(obj)) { 412 pr_warning("elf init: internal error\n"); 413 return -LIBBPF_ERRNO__LIBELF; 414 } 415 416 if (obj->efile.obj_buf_sz > 0) { 417 /* 418 * obj_buf should have been validated by 419 * bpf_object__open_buffer(). 420 */ 421 obj->efile.elf = elf_memory(obj->efile.obj_buf, 422 obj->efile.obj_buf_sz); 423 } else { 424 obj->efile.fd = open(obj->path, O_RDONLY); 425 if (obj->efile.fd < 0) { 426 pr_warning("failed to open %s: %s\n", obj->path, 427 strerror(errno)); 428 return -errno; 429 } 430 431 obj->efile.elf = elf_begin(obj->efile.fd, 432 LIBBPF_ELF_C_READ_MMAP, 433 NULL); 434 } 435 436 if (!obj->efile.elf) { 437 pr_warning("failed to open %s as ELF file\n", 438 obj->path); 439 err = -LIBBPF_ERRNO__LIBELF; 440 goto errout; 441 } 442 443 if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) { 444 pr_warning("failed to get EHDR from %s\n", 445 obj->path); 446 err = -LIBBPF_ERRNO__FORMAT; 447 goto errout; 448 } 449 ep = &obj->efile.ehdr; 450 451 /* Old LLVM set e_machine to EM_NONE */ 452 if ((ep->e_type != ET_REL) || (ep->e_machine && (ep->e_machine != EM_BPF))) { 453 pr_warning("%s is not an eBPF object file\n", 454 obj->path); 455 err = -LIBBPF_ERRNO__FORMAT; 456 goto errout; 457 } 458 459 return 0; 460 errout: 461 bpf_object__elf_finish(obj); 462 return err; 463 } 464 465 static int 466 bpf_object__check_endianness(struct bpf_object *obj) 467 { 468 static unsigned int const endian = 1; 469 470 switch (obj->efile.ehdr.e_ident[EI_DATA]) { 471 case ELFDATA2LSB: 472 /* We are big endian, BPF obj is little endian. */ 473 if (*(unsigned char const *)&endian != 1) 474 goto mismatch; 475 break; 476 477 case ELFDATA2MSB: 478 /* We are little endian, BPF obj is big endian. */ 479 if (*(unsigned char const *)&endian != 0) 480 goto mismatch; 481 break; 482 default: 483 return -LIBBPF_ERRNO__ENDIAN; 484 } 485 486 return 0; 487 488 mismatch: 489 pr_warning("Error: endianness mismatch.\n"); 490 return -LIBBPF_ERRNO__ENDIAN; 491 } 492 493 static int 494 bpf_object__init_license(struct bpf_object *obj, 495 void *data, size_t size) 496 { 497 memcpy(obj->license, data, 498 min(size, sizeof(obj->license) - 1)); 499 pr_debug("license of %s is %s\n", obj->path, obj->license); 500 return 0; 501 } 502 503 static int 504 bpf_object__init_kversion(struct bpf_object *obj, 505 void *data, size_t size) 506 { 507 u32 kver; 508 509 if (size != sizeof(kver)) { 510 pr_warning("invalid kver section in %s\n", obj->path); 511 return -LIBBPF_ERRNO__FORMAT; 512 } 513 memcpy(&kver, data, sizeof(kver)); 514 obj->kern_version = kver; 515 pr_debug("kernel version of %s is %x\n", obj->path, 516 obj->kern_version); 517 return 0; 518 } 519 520 static int 521 bpf_object__validate_maps(struct bpf_object *obj) 522 { 523 int i; 524 525 /* 526 * If there's only 1 map, the only error case should have been 527 * catched in bpf_object__init_maps(). 528 */ 529 if (!obj->maps || !obj->nr_maps || (obj->nr_maps == 1)) 530 return 0; 531 532 for (i = 1; i < obj->nr_maps; i++) { 533 const struct bpf_map *a = &obj->maps[i - 1]; 534 const struct bpf_map *b = &obj->maps[i]; 535 536 if (b->offset - a->offset < sizeof(struct bpf_map_def)) { 537 pr_warning("corrupted map section in %s: map \"%s\" too small\n", 538 obj->path, a->name); 539 return -EINVAL; 540 } 541 } 542 return 0; 543 } 544 545 static int compare_bpf_map(const void *_a, const void *_b) 546 { 547 const struct bpf_map *a = _a; 548 const struct bpf_map *b = _b; 549 550 return a->offset - b->offset; 551 } 552 553 static int 554 bpf_object__init_maps(struct bpf_object *obj) 555 { 556 int i, map_idx, nr_maps = 0; 557 Elf_Scn *scn; 558 Elf_Data *data; 559 Elf_Data *symbols = obj->efile.symbols; 560 561 if (obj->efile.maps_shndx < 0) 562 return -EINVAL; 563 if (!symbols) 564 return -EINVAL; 565 566 scn = elf_getscn(obj->efile.elf, obj->efile.maps_shndx); 567 if (scn) 568 data = elf_getdata(scn, NULL); 569 if (!scn || !data) { 570 pr_warning("failed to get Elf_Data from map section %d\n", 571 obj->efile.maps_shndx); 572 return -EINVAL; 573 } 574 575 /* 576 * Count number of maps. Each map has a name. 577 * Array of maps is not supported: only the first element is 578 * considered. 579 * 580 * TODO: Detect array of map and report error. 581 */ 582 for (i = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) { 583 GElf_Sym sym; 584 585 if (!gelf_getsym(symbols, i, &sym)) 586 continue; 587 if (sym.st_shndx != obj->efile.maps_shndx) 588 continue; 589 nr_maps++; 590 } 591 592 /* Alloc obj->maps and fill nr_maps. */ 593 pr_debug("maps in %s: %d maps in %zd bytes\n", obj->path, 594 nr_maps, data->d_size); 595 596 if (!nr_maps) 597 return 0; 598 599 obj->maps = calloc(nr_maps, sizeof(obj->maps[0])); 600 if (!obj->maps) { 601 pr_warning("alloc maps for object failed\n"); 602 return -ENOMEM; 603 } 604 obj->nr_maps = nr_maps; 605 606 /* 607 * fill all fd with -1 so won't close incorrect 608 * fd (fd=0 is stdin) when failure (zclose won't close 609 * negative fd)). 610 */ 611 for (i = 0; i < nr_maps; i++) 612 obj->maps[i].fd = -1; 613 614 /* 615 * Fill obj->maps using data in "maps" section. 616 */ 617 for (i = 0, map_idx = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) { 618 GElf_Sym sym; 619 const char *map_name; 620 struct bpf_map_def *def; 621 622 if (!gelf_getsym(symbols, i, &sym)) 623 continue; 624 if (sym.st_shndx != obj->efile.maps_shndx) 625 continue; 626 627 map_name = elf_strptr(obj->efile.elf, 628 obj->efile.strtabidx, 629 sym.st_name); 630 obj->maps[map_idx].offset = sym.st_value; 631 if (sym.st_value + sizeof(struct bpf_map_def) > data->d_size) { 632 pr_warning("corrupted maps section in %s: last map \"%s\" too small\n", 633 obj->path, map_name); 634 return -EINVAL; 635 } 636 637 obj->maps[map_idx].name = strdup(map_name); 638 if (!obj->maps[map_idx].name) { 639 pr_warning("failed to alloc map name\n"); 640 return -ENOMEM; 641 } 642 pr_debug("map %d is \"%s\"\n", map_idx, 643 obj->maps[map_idx].name); 644 def = (struct bpf_map_def *)(data->d_buf + sym.st_value); 645 obj->maps[map_idx].def = *def; 646 map_idx++; 647 } 648 649 qsort(obj->maps, obj->nr_maps, sizeof(obj->maps[0]), compare_bpf_map); 650 return bpf_object__validate_maps(obj); 651 } 652 653 static int bpf_object__elf_collect(struct bpf_object *obj) 654 { 655 Elf *elf = obj->efile.elf; 656 GElf_Ehdr *ep = &obj->efile.ehdr; 657 Elf_Scn *scn = NULL; 658 int idx = 0, err = 0; 659 660 /* Elf is corrupted/truncated, avoid calling elf_strptr. */ 661 if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) { 662 pr_warning("failed to get e_shstrndx from %s\n", 663 obj->path); 664 return -LIBBPF_ERRNO__FORMAT; 665 } 666 667 while ((scn = elf_nextscn(elf, scn)) != NULL) { 668 char *name; 669 GElf_Shdr sh; 670 Elf_Data *data; 671 672 idx++; 673 if (gelf_getshdr(scn, &sh) != &sh) { 674 pr_warning("failed to get section header from %s\n", 675 obj->path); 676 err = -LIBBPF_ERRNO__FORMAT; 677 goto out; 678 } 679 680 name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name); 681 if (!name) { 682 pr_warning("failed to get section name from %s\n", 683 obj->path); 684 err = -LIBBPF_ERRNO__FORMAT; 685 goto out; 686 } 687 688 data = elf_getdata(scn, 0); 689 if (!data) { 690 pr_warning("failed to get section data from %s(%s)\n", 691 name, obj->path); 692 err = -LIBBPF_ERRNO__FORMAT; 693 goto out; 694 } 695 pr_debug("section %s, size %ld, link %d, flags %lx, type=%d\n", 696 name, (unsigned long)data->d_size, 697 (int)sh.sh_link, (unsigned long)sh.sh_flags, 698 (int)sh.sh_type); 699 700 if (strcmp(name, "license") == 0) 701 err = bpf_object__init_license(obj, 702 data->d_buf, 703 data->d_size); 704 else if (strcmp(name, "version") == 0) 705 err = bpf_object__init_kversion(obj, 706 data->d_buf, 707 data->d_size); 708 else if (strcmp(name, "maps") == 0) 709 obj->efile.maps_shndx = idx; 710 else if (sh.sh_type == SHT_SYMTAB) { 711 if (obj->efile.symbols) { 712 pr_warning("bpf: multiple SYMTAB in %s\n", 713 obj->path); 714 err = -LIBBPF_ERRNO__FORMAT; 715 } else { 716 obj->efile.symbols = data; 717 obj->efile.strtabidx = sh.sh_link; 718 } 719 } else if ((sh.sh_type == SHT_PROGBITS) && 720 (sh.sh_flags & SHF_EXECINSTR) && 721 (data->d_size > 0)) { 722 err = bpf_object__add_program(obj, data->d_buf, 723 data->d_size, name, idx); 724 if (err) { 725 char errmsg[STRERR_BUFSIZE]; 726 727 strerror_r(-err, errmsg, sizeof(errmsg)); 728 pr_warning("failed to alloc program %s (%s): %s", 729 name, obj->path, errmsg); 730 } 731 } else if (sh.sh_type == SHT_REL) { 732 void *reloc = obj->efile.reloc; 733 int nr_reloc = obj->efile.nr_reloc + 1; 734 735 reloc = realloc(reloc, 736 sizeof(*obj->efile.reloc) * nr_reloc); 737 if (!reloc) { 738 pr_warning("realloc failed\n"); 739 err = -ENOMEM; 740 } else { 741 int n = nr_reloc - 1; 742 743 obj->efile.reloc = reloc; 744 obj->efile.nr_reloc = nr_reloc; 745 746 obj->efile.reloc[n].shdr = sh; 747 obj->efile.reloc[n].data = data; 748 } 749 } 750 if (err) 751 goto out; 752 } 753 754 if (!obj->efile.strtabidx || obj->efile.strtabidx >= idx) { 755 pr_warning("Corrupted ELF file: index of strtab invalid\n"); 756 return LIBBPF_ERRNO__FORMAT; 757 } 758 if (obj->efile.maps_shndx >= 0) 759 err = bpf_object__init_maps(obj); 760 out: 761 return err; 762 } 763 764 static struct bpf_program * 765 bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx) 766 { 767 struct bpf_program *prog; 768 size_t i; 769 770 for (i = 0; i < obj->nr_programs; i++) { 771 prog = &obj->programs[i]; 772 if (prog->idx == idx) 773 return prog; 774 } 775 return NULL; 776 } 777 778 static int 779 bpf_program__collect_reloc(struct bpf_program *prog, 780 size_t nr_maps, GElf_Shdr *shdr, 781 Elf_Data *data, Elf_Data *symbols, 782 int maps_shndx) 783 { 784 int i, nrels; 785 786 pr_debug("collecting relocating info for: '%s'\n", 787 prog->section_name); 788 nrels = shdr->sh_size / shdr->sh_entsize; 789 790 prog->reloc_desc = malloc(sizeof(*prog->reloc_desc) * nrels); 791 if (!prog->reloc_desc) { 792 pr_warning("failed to alloc memory in relocation\n"); 793 return -ENOMEM; 794 } 795 prog->nr_reloc = nrels; 796 797 for (i = 0; i < nrels; i++) { 798 GElf_Sym sym; 799 GElf_Rel rel; 800 unsigned int insn_idx; 801 struct bpf_insn *insns = prog->insns; 802 size_t map_idx; 803 804 if (!gelf_getrel(data, i, &rel)) { 805 pr_warning("relocation: failed to get %d reloc\n", i); 806 return -LIBBPF_ERRNO__FORMAT; 807 } 808 809 if (!gelf_getsym(symbols, 810 GELF_R_SYM(rel.r_info), 811 &sym)) { 812 pr_warning("relocation: symbol %"PRIx64" not found\n", 813 GELF_R_SYM(rel.r_info)); 814 return -LIBBPF_ERRNO__FORMAT; 815 } 816 817 if (sym.st_shndx != maps_shndx) { 818 pr_warning("Program '%s' contains non-map related relo data pointing to section %u\n", 819 prog->section_name, sym.st_shndx); 820 return -LIBBPF_ERRNO__RELOC; 821 } 822 823 insn_idx = rel.r_offset / sizeof(struct bpf_insn); 824 pr_debug("relocation: insn_idx=%u\n", insn_idx); 825 826 if (insns[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) { 827 pr_warning("bpf: relocation: invalid relo for insns[%d].code 0x%x\n", 828 insn_idx, insns[insn_idx].code); 829 return -LIBBPF_ERRNO__RELOC; 830 } 831 832 map_idx = sym.st_value / sizeof(struct bpf_map_def); 833 if (map_idx >= nr_maps) { 834 pr_warning("bpf relocation: map_idx %d large than %d\n", 835 (int)map_idx, (int)nr_maps - 1); 836 return -LIBBPF_ERRNO__RELOC; 837 } 838 839 prog->reloc_desc[i].insn_idx = insn_idx; 840 prog->reloc_desc[i].map_idx = map_idx; 841 } 842 return 0; 843 } 844 845 static int 846 bpf_object__create_maps(struct bpf_object *obj) 847 { 848 unsigned int i; 849 850 for (i = 0; i < obj->nr_maps; i++) { 851 struct bpf_map_def *def = &obj->maps[i].def; 852 int *pfd = &obj->maps[i].fd; 853 854 *pfd = bpf_create_map(def->type, 855 def->key_size, 856 def->value_size, 857 def->max_entries, 858 0); 859 if (*pfd < 0) { 860 size_t j; 861 int err = *pfd; 862 863 pr_warning("failed to create map: %s\n", 864 strerror(errno)); 865 for (j = 0; j < i; j++) 866 zclose(obj->maps[j].fd); 867 return err; 868 } 869 pr_debug("create map %s: fd=%d\n", obj->maps[i].name, *pfd); 870 } 871 872 return 0; 873 } 874 875 static int 876 bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj) 877 { 878 int i; 879 880 if (!prog || !prog->reloc_desc) 881 return 0; 882 883 for (i = 0; i < prog->nr_reloc; i++) { 884 int insn_idx, map_idx; 885 struct bpf_insn *insns = prog->insns; 886 887 insn_idx = prog->reloc_desc[i].insn_idx; 888 map_idx = prog->reloc_desc[i].map_idx; 889 890 if (insn_idx >= (int)prog->insns_cnt) { 891 pr_warning("relocation out of range: '%s'\n", 892 prog->section_name); 893 return -LIBBPF_ERRNO__RELOC; 894 } 895 insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD; 896 insns[insn_idx].imm = obj->maps[map_idx].fd; 897 } 898 899 zfree(&prog->reloc_desc); 900 prog->nr_reloc = 0; 901 return 0; 902 } 903 904 905 static int 906 bpf_object__relocate(struct bpf_object *obj) 907 { 908 struct bpf_program *prog; 909 size_t i; 910 int err; 911 912 for (i = 0; i < obj->nr_programs; i++) { 913 prog = &obj->programs[i]; 914 915 err = bpf_program__relocate(prog, obj); 916 if (err) { 917 pr_warning("failed to relocate '%s'\n", 918 prog->section_name); 919 return err; 920 } 921 } 922 return 0; 923 } 924 925 static int bpf_object__collect_reloc(struct bpf_object *obj) 926 { 927 int i, err; 928 929 if (!obj_elf_valid(obj)) { 930 pr_warning("Internal error: elf object is closed\n"); 931 return -LIBBPF_ERRNO__INTERNAL; 932 } 933 934 for (i = 0; i < obj->efile.nr_reloc; i++) { 935 GElf_Shdr *shdr = &obj->efile.reloc[i].shdr; 936 Elf_Data *data = obj->efile.reloc[i].data; 937 int idx = shdr->sh_info; 938 struct bpf_program *prog; 939 size_t nr_maps = obj->nr_maps; 940 941 if (shdr->sh_type != SHT_REL) { 942 pr_warning("internal error at %d\n", __LINE__); 943 return -LIBBPF_ERRNO__INTERNAL; 944 } 945 946 prog = bpf_object__find_prog_by_idx(obj, idx); 947 if (!prog) { 948 pr_warning("relocation failed: no %d section\n", 949 idx); 950 return -LIBBPF_ERRNO__RELOC; 951 } 952 953 err = bpf_program__collect_reloc(prog, nr_maps, 954 shdr, data, 955 obj->efile.symbols, 956 obj->efile.maps_shndx); 957 if (err) 958 return err; 959 } 960 return 0; 961 } 962 963 static int 964 load_program(enum bpf_prog_type type, struct bpf_insn *insns, 965 int insns_cnt, char *license, u32 kern_version, int *pfd) 966 { 967 int ret; 968 char *log_buf; 969 970 if (!insns || !insns_cnt) 971 return -EINVAL; 972 973 log_buf = malloc(BPF_LOG_BUF_SIZE); 974 if (!log_buf) 975 pr_warning("Alloc log buffer for bpf loader error, continue without log\n"); 976 977 ret = bpf_load_program(type, insns, insns_cnt, license, 978 kern_version, log_buf, BPF_LOG_BUF_SIZE); 979 980 if (ret >= 0) { 981 *pfd = ret; 982 ret = 0; 983 goto out; 984 } 985 986 ret = -LIBBPF_ERRNO__LOAD; 987 pr_warning("load bpf program failed: %s\n", strerror(errno)); 988 989 if (log_buf && log_buf[0] != '\0') { 990 ret = -LIBBPF_ERRNO__VERIFY; 991 pr_warning("-- BEGIN DUMP LOG ---\n"); 992 pr_warning("\n%s\n", log_buf); 993 pr_warning("-- END LOG --\n"); 994 } else if (insns_cnt >= BPF_MAXINSNS) { 995 pr_warning("Program too large (%d insns), at most %d insns\n", 996 insns_cnt, BPF_MAXINSNS); 997 ret = -LIBBPF_ERRNO__PROG2BIG; 998 } else { 999 /* Wrong program type? */ 1000 if (type != BPF_PROG_TYPE_KPROBE) { 1001 int fd; 1002 1003 fd = bpf_load_program(BPF_PROG_TYPE_KPROBE, insns, 1004 insns_cnt, license, kern_version, 1005 NULL, 0); 1006 if (fd >= 0) { 1007 close(fd); 1008 ret = -LIBBPF_ERRNO__PROGTYPE; 1009 goto out; 1010 } 1011 } 1012 1013 if (log_buf) 1014 ret = -LIBBPF_ERRNO__KVER; 1015 } 1016 1017 out: 1018 free(log_buf); 1019 return ret; 1020 } 1021 1022 static int 1023 bpf_program__load(struct bpf_program *prog, 1024 char *license, u32 kern_version) 1025 { 1026 int err = 0, fd, i; 1027 1028 if (prog->instances.nr < 0 || !prog->instances.fds) { 1029 if (prog->preprocessor) { 1030 pr_warning("Internal error: can't load program '%s'\n", 1031 prog->section_name); 1032 return -LIBBPF_ERRNO__INTERNAL; 1033 } 1034 1035 prog->instances.fds = malloc(sizeof(int)); 1036 if (!prog->instances.fds) { 1037 pr_warning("Not enough memory for BPF fds\n"); 1038 return -ENOMEM; 1039 } 1040 prog->instances.nr = 1; 1041 prog->instances.fds[0] = -1; 1042 } 1043 1044 if (!prog->preprocessor) { 1045 if (prog->instances.nr != 1) { 1046 pr_warning("Program '%s' is inconsistent: nr(%d) != 1\n", 1047 prog->section_name, prog->instances.nr); 1048 } 1049 err = load_program(prog->type, prog->insns, prog->insns_cnt, 1050 license, kern_version, &fd); 1051 if (!err) 1052 prog->instances.fds[0] = fd; 1053 goto out; 1054 } 1055 1056 for (i = 0; i < prog->instances.nr; i++) { 1057 struct bpf_prog_prep_result result; 1058 bpf_program_prep_t preprocessor = prog->preprocessor; 1059 1060 bzero(&result, sizeof(result)); 1061 err = preprocessor(prog, i, prog->insns, 1062 prog->insns_cnt, &result); 1063 if (err) { 1064 pr_warning("Preprocessing the %dth instance of program '%s' failed\n", 1065 i, prog->section_name); 1066 goto out; 1067 } 1068 1069 if (!result.new_insn_ptr || !result.new_insn_cnt) { 1070 pr_debug("Skip loading the %dth instance of program '%s'\n", 1071 i, prog->section_name); 1072 prog->instances.fds[i] = -1; 1073 if (result.pfd) 1074 *result.pfd = -1; 1075 continue; 1076 } 1077 1078 err = load_program(prog->type, result.new_insn_ptr, 1079 result.new_insn_cnt, 1080 license, kern_version, &fd); 1081 1082 if (err) { 1083 pr_warning("Loading the %dth instance of program '%s' failed\n", 1084 i, prog->section_name); 1085 goto out; 1086 } 1087 1088 if (result.pfd) 1089 *result.pfd = fd; 1090 prog->instances.fds[i] = fd; 1091 } 1092 out: 1093 if (err) 1094 pr_warning("failed to load program '%s'\n", 1095 prog->section_name); 1096 zfree(&prog->insns); 1097 prog->insns_cnt = 0; 1098 return err; 1099 } 1100 1101 static int 1102 bpf_object__load_progs(struct bpf_object *obj) 1103 { 1104 size_t i; 1105 int err; 1106 1107 for (i = 0; i < obj->nr_programs; i++) { 1108 err = bpf_program__load(&obj->programs[i], 1109 obj->license, 1110 obj->kern_version); 1111 if (err) 1112 return err; 1113 } 1114 return 0; 1115 } 1116 1117 static int bpf_object__validate(struct bpf_object *obj) 1118 { 1119 if (obj->kern_version == 0) { 1120 pr_warning("%s doesn't provide kernel version\n", 1121 obj->path); 1122 return -LIBBPF_ERRNO__KVERSION; 1123 } 1124 return 0; 1125 } 1126 1127 static struct bpf_object * 1128 __bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz) 1129 { 1130 struct bpf_object *obj; 1131 int err; 1132 1133 if (elf_version(EV_CURRENT) == EV_NONE) { 1134 pr_warning("failed to init libelf for %s\n", path); 1135 return ERR_PTR(-LIBBPF_ERRNO__LIBELF); 1136 } 1137 1138 obj = bpf_object__new(path, obj_buf, obj_buf_sz); 1139 if (IS_ERR(obj)) 1140 return obj; 1141 1142 CHECK_ERR(bpf_object__elf_init(obj), err, out); 1143 CHECK_ERR(bpf_object__check_endianness(obj), err, out); 1144 CHECK_ERR(bpf_object__elf_collect(obj), err, out); 1145 CHECK_ERR(bpf_object__collect_reloc(obj), err, out); 1146 CHECK_ERR(bpf_object__validate(obj), err, out); 1147 1148 bpf_object__elf_finish(obj); 1149 return obj; 1150 out: 1151 bpf_object__close(obj); 1152 return ERR_PTR(err); 1153 } 1154 1155 struct bpf_object *bpf_object__open(const char *path) 1156 { 1157 /* param validation */ 1158 if (!path) 1159 return NULL; 1160 1161 pr_debug("loading %s\n", path); 1162 1163 return __bpf_object__open(path, NULL, 0); 1164 } 1165 1166 struct bpf_object *bpf_object__open_buffer(void *obj_buf, 1167 size_t obj_buf_sz, 1168 const char *name) 1169 { 1170 char tmp_name[64]; 1171 1172 /* param validation */ 1173 if (!obj_buf || obj_buf_sz <= 0) 1174 return NULL; 1175 1176 if (!name) { 1177 snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx", 1178 (unsigned long)obj_buf, 1179 (unsigned long)obj_buf_sz); 1180 tmp_name[sizeof(tmp_name) - 1] = '\0'; 1181 name = tmp_name; 1182 } 1183 pr_debug("loading object '%s' from buffer\n", 1184 name); 1185 1186 return __bpf_object__open(name, obj_buf, obj_buf_sz); 1187 } 1188 1189 int bpf_object__unload(struct bpf_object *obj) 1190 { 1191 size_t i; 1192 1193 if (!obj) 1194 return -EINVAL; 1195 1196 for (i = 0; i < obj->nr_maps; i++) 1197 zclose(obj->maps[i].fd); 1198 1199 for (i = 0; i < obj->nr_programs; i++) 1200 bpf_program__unload(&obj->programs[i]); 1201 1202 return 0; 1203 } 1204 1205 int bpf_object__load(struct bpf_object *obj) 1206 { 1207 int err; 1208 1209 if (!obj) 1210 return -EINVAL; 1211 1212 if (obj->loaded) { 1213 pr_warning("object should not be loaded twice\n"); 1214 return -EINVAL; 1215 } 1216 1217 obj->loaded = true; 1218 1219 CHECK_ERR(bpf_object__create_maps(obj), err, out); 1220 CHECK_ERR(bpf_object__relocate(obj), err, out); 1221 CHECK_ERR(bpf_object__load_progs(obj), err, out); 1222 1223 return 0; 1224 out: 1225 bpf_object__unload(obj); 1226 pr_warning("failed to load object '%s'\n", obj->path); 1227 return err; 1228 } 1229 1230 void bpf_object__close(struct bpf_object *obj) 1231 { 1232 size_t i; 1233 1234 if (!obj) 1235 return; 1236 1237 if (obj->clear_priv) 1238 obj->clear_priv(obj, obj->priv); 1239 1240 bpf_object__elf_finish(obj); 1241 bpf_object__unload(obj); 1242 1243 for (i = 0; i < obj->nr_maps; i++) { 1244 zfree(&obj->maps[i].name); 1245 if (obj->maps[i].clear_priv) 1246 obj->maps[i].clear_priv(&obj->maps[i], 1247 obj->maps[i].priv); 1248 obj->maps[i].priv = NULL; 1249 obj->maps[i].clear_priv = NULL; 1250 } 1251 zfree(&obj->maps); 1252 obj->nr_maps = 0; 1253 1254 if (obj->programs && obj->nr_programs) { 1255 for (i = 0; i < obj->nr_programs; i++) 1256 bpf_program__exit(&obj->programs[i]); 1257 } 1258 zfree(&obj->programs); 1259 1260 list_del(&obj->list); 1261 free(obj); 1262 } 1263 1264 struct bpf_object * 1265 bpf_object__next(struct bpf_object *prev) 1266 { 1267 struct bpf_object *next; 1268 1269 if (!prev) 1270 next = list_first_entry(&bpf_objects_list, 1271 struct bpf_object, 1272 list); 1273 else 1274 next = list_next_entry(prev, list); 1275 1276 /* Empty list is noticed here so don't need checking on entry. */ 1277 if (&next->list == &bpf_objects_list) 1278 return NULL; 1279 1280 return next; 1281 } 1282 1283 const char *bpf_object__name(struct bpf_object *obj) 1284 { 1285 return obj ? obj->path : ERR_PTR(-EINVAL); 1286 } 1287 1288 unsigned int bpf_object__kversion(struct bpf_object *obj) 1289 { 1290 return obj ? obj->kern_version : 0; 1291 } 1292 1293 int bpf_object__set_priv(struct bpf_object *obj, void *priv, 1294 bpf_object_clear_priv_t clear_priv) 1295 { 1296 if (obj->priv && obj->clear_priv) 1297 obj->clear_priv(obj, obj->priv); 1298 1299 obj->priv = priv; 1300 obj->clear_priv = clear_priv; 1301 return 0; 1302 } 1303 1304 void *bpf_object__priv(struct bpf_object *obj) 1305 { 1306 return obj ? obj->priv : ERR_PTR(-EINVAL); 1307 } 1308 1309 struct bpf_program * 1310 bpf_program__next(struct bpf_program *prev, struct bpf_object *obj) 1311 { 1312 size_t idx; 1313 1314 if (!obj->programs) 1315 return NULL; 1316 /* First handler */ 1317 if (prev == NULL) 1318 return &obj->programs[0]; 1319 1320 if (prev->obj != obj) { 1321 pr_warning("error: program handler doesn't match object\n"); 1322 return NULL; 1323 } 1324 1325 idx = (prev - obj->programs) + 1; 1326 if (idx >= obj->nr_programs) 1327 return NULL; 1328 return &obj->programs[idx]; 1329 } 1330 1331 int bpf_program__set_priv(struct bpf_program *prog, void *priv, 1332 bpf_program_clear_priv_t clear_priv) 1333 { 1334 if (prog->priv && prog->clear_priv) 1335 prog->clear_priv(prog, prog->priv); 1336 1337 prog->priv = priv; 1338 prog->clear_priv = clear_priv; 1339 return 0; 1340 } 1341 1342 void *bpf_program__priv(struct bpf_program *prog) 1343 { 1344 return prog ? prog->priv : ERR_PTR(-EINVAL); 1345 } 1346 1347 const char *bpf_program__title(struct bpf_program *prog, bool needs_copy) 1348 { 1349 const char *title; 1350 1351 title = prog->section_name; 1352 if (needs_copy) { 1353 title = strdup(title); 1354 if (!title) { 1355 pr_warning("failed to strdup program title\n"); 1356 return ERR_PTR(-ENOMEM); 1357 } 1358 } 1359 1360 return title; 1361 } 1362 1363 int bpf_program__fd(struct bpf_program *prog) 1364 { 1365 return bpf_program__nth_fd(prog, 0); 1366 } 1367 1368 int bpf_program__set_prep(struct bpf_program *prog, int nr_instances, 1369 bpf_program_prep_t prep) 1370 { 1371 int *instances_fds; 1372 1373 if (nr_instances <= 0 || !prep) 1374 return -EINVAL; 1375 1376 if (prog->instances.nr > 0 || prog->instances.fds) { 1377 pr_warning("Can't set pre-processor after loading\n"); 1378 return -EINVAL; 1379 } 1380 1381 instances_fds = malloc(sizeof(int) * nr_instances); 1382 if (!instances_fds) { 1383 pr_warning("alloc memory failed for fds\n"); 1384 return -ENOMEM; 1385 } 1386 1387 /* fill all fd with -1 */ 1388 memset(instances_fds, -1, sizeof(int) * nr_instances); 1389 1390 prog->instances.nr = nr_instances; 1391 prog->instances.fds = instances_fds; 1392 prog->preprocessor = prep; 1393 return 0; 1394 } 1395 1396 int bpf_program__nth_fd(struct bpf_program *prog, int n) 1397 { 1398 int fd; 1399 1400 if (n >= prog->instances.nr || n < 0) { 1401 pr_warning("Can't get the %dth fd from program %s: only %d instances\n", 1402 n, prog->section_name, prog->instances.nr); 1403 return -EINVAL; 1404 } 1405 1406 fd = prog->instances.fds[n]; 1407 if (fd < 0) { 1408 pr_warning("%dth instance of program '%s' is invalid\n", 1409 n, prog->section_name); 1410 return -ENOENT; 1411 } 1412 1413 return fd; 1414 } 1415 1416 static void bpf_program__set_type(struct bpf_program *prog, 1417 enum bpf_prog_type type) 1418 { 1419 prog->type = type; 1420 } 1421 1422 int bpf_program__set_tracepoint(struct bpf_program *prog) 1423 { 1424 if (!prog) 1425 return -EINVAL; 1426 bpf_program__set_type(prog, BPF_PROG_TYPE_TRACEPOINT); 1427 return 0; 1428 } 1429 1430 int bpf_program__set_kprobe(struct bpf_program *prog) 1431 { 1432 if (!prog) 1433 return -EINVAL; 1434 bpf_program__set_type(prog, BPF_PROG_TYPE_KPROBE); 1435 return 0; 1436 } 1437 1438 static bool bpf_program__is_type(struct bpf_program *prog, 1439 enum bpf_prog_type type) 1440 { 1441 return prog ? (prog->type == type) : false; 1442 } 1443 1444 bool bpf_program__is_tracepoint(struct bpf_program *prog) 1445 { 1446 return bpf_program__is_type(prog, BPF_PROG_TYPE_TRACEPOINT); 1447 } 1448 1449 bool bpf_program__is_kprobe(struct bpf_program *prog) 1450 { 1451 return bpf_program__is_type(prog, BPF_PROG_TYPE_KPROBE); 1452 } 1453 1454 int bpf_map__fd(struct bpf_map *map) 1455 { 1456 return map ? map->fd : -EINVAL; 1457 } 1458 1459 const struct bpf_map_def *bpf_map__def(struct bpf_map *map) 1460 { 1461 return map ? &map->def : ERR_PTR(-EINVAL); 1462 } 1463 1464 const char *bpf_map__name(struct bpf_map *map) 1465 { 1466 return map ? map->name : NULL; 1467 } 1468 1469 int bpf_map__set_priv(struct bpf_map *map, void *priv, 1470 bpf_map_clear_priv_t clear_priv) 1471 { 1472 if (!map) 1473 return -EINVAL; 1474 1475 if (map->priv) { 1476 if (map->clear_priv) 1477 map->clear_priv(map, map->priv); 1478 } 1479 1480 map->priv = priv; 1481 map->clear_priv = clear_priv; 1482 return 0; 1483 } 1484 1485 void *bpf_map__priv(struct bpf_map *map) 1486 { 1487 return map ? map->priv : ERR_PTR(-EINVAL); 1488 } 1489 1490 struct bpf_map * 1491 bpf_map__next(struct bpf_map *prev, struct bpf_object *obj) 1492 { 1493 size_t idx; 1494 struct bpf_map *s, *e; 1495 1496 if (!obj || !obj->maps) 1497 return NULL; 1498 1499 s = obj->maps; 1500 e = obj->maps + obj->nr_maps; 1501 1502 if (prev == NULL) 1503 return s; 1504 1505 if ((prev < s) || (prev >= e)) { 1506 pr_warning("error in %s: map handler doesn't belong to object\n", 1507 __func__); 1508 return NULL; 1509 } 1510 1511 idx = (prev - obj->maps) + 1; 1512 if (idx >= obj->nr_maps) 1513 return NULL; 1514 return &obj->maps[idx]; 1515 } 1516 1517 struct bpf_map * 1518 bpf_object__find_map_by_name(struct bpf_object *obj, const char *name) 1519 { 1520 struct bpf_map *pos; 1521 1522 bpf_map__for_each(pos, obj) { 1523 if (pos->name && !strcmp(pos->name, name)) 1524 return pos; 1525 } 1526 return NULL; 1527 } 1528 1529 struct bpf_map * 1530 bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset) 1531 { 1532 int i; 1533 1534 for (i = 0; i < obj->nr_maps; i++) { 1535 if (obj->maps[i].offset == offset) 1536 return &obj->maps[i]; 1537 } 1538 return ERR_PTR(-ENOENT); 1539 } 1540