tools/lib/bpf/libbpf.c

   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         struct bpf_map_def def;
 189         void *priv;
 190         bpf_map_clear_priv_t clear_priv;
 191 };
 192
 193 static LIST_HEAD(bpf_objects_list);
 194
 195 struct bpf_object {
 196         char license[64];
 197         u32 kern_version;
 198
 199         struct bpf_program *programs;
 200         size_t nr_programs;
 201         struct bpf_map *maps;
 202         size_t nr_maps;
 203
 204         bool loaded;
 205
 206         /*
 207          * Information when doing elf related work. Only valid if fd
 208          * is valid.
 209          */
 210         struct {
 211                 int fd;
 212                 void *obj_buf;
 213                 size_t obj_buf_sz;
 214                 Elf *elf;
 215                 GElf_Ehdr ehdr;
 216                 Elf_Data *symbols;
 217                 size_t strtabidx;
 218                 struct {
 219                         GElf_Shdr shdr;
 220                         Elf_Data *data;
 221                 } *reloc;
 222                 int nr_reloc;
 223                 int maps_shndx;
 224         } efile;
 225         /*
 226          * All loaded bpf_object is linked in a list, which is
 227          * hidden to caller. bpf_objects__<func> handlers deal with
 228          * all objects.
 229          */
 230         struct list_head list;
 231         char path[];
 232 };
 233 #define obj_elf_valid(o)        ((o)->efile.elf)
 234
 235 static void bpf_program__unload(struct bpf_program *prog)
 236 {
 237         int i;
 238
 239         if (!prog)
 240                 return;
 241
 242         /*
 243          * If the object is opened but the program was never loaded,
 244          * it is possible that prog->instances.nr == -1.
 245          */
 246         if (prog->instances.nr > 0) {
 247                 for (i = 0; i < prog->instances.nr; i++)
 248                         zclose(prog->instances.fds[i]);
 249         } else if (prog->instances.nr != -1) {
 250                 pr_warning("Internal error: instances.nr is %d\n",
 251                            prog->instances.nr);
 252         }
 253
 254         prog->instances.nr = -1;
 255         zfree(&prog->instances.fds);
 256 }
 257
 258 static void bpf_program__exit(struct bpf_program *prog)
 259 {
 260         if (!prog)
 261                 return;
 262
 263         if (prog->clear_priv)
 264                 prog->clear_priv(prog, prog->priv);
 265
 266         prog->priv = NULL;
 267         prog->clear_priv = NULL;
 268
 269         bpf_program__unload(prog);
 270         zfree(&prog->section_name);
 271         zfree(&prog->insns);
 272         zfree(&prog->reloc_desc);
 273
 274         prog->nr_reloc = 0;
 275         prog->insns_cnt = 0;
 276         prog->idx = -1;
 277 }
 278
 279 static int
 280 bpf_program__init(void *data, size_t size, char *name, int idx,
 281                     struct bpf_program *prog)
 282 {
 283         if (size < sizeof(struct bpf_insn)) {
 284                 pr_warning("corrupted section '%s'\n", name);
 285                 return -EINVAL;
 286         }
 287
 288         bzero(prog, sizeof(*prog));
 289
 290         prog->section_name = strdup(name);
 291         if (!prog->section_name) {
 292                 pr_warning("failed to alloc name for prog %s\n",
 293                            name);
 294                 goto errout;
 295         }
 296
 297         prog->insns = malloc(size);
 298         if (!prog->insns) {
 299                 pr_warning("failed to alloc insns for %s\n", name);
 300                 goto errout;
 301         }
 302         prog->insns_cnt = size / sizeof(struct bpf_insn);
 303         memcpy(prog->insns, data,
 304                prog->insns_cnt * sizeof(struct bpf_insn));
 305         prog->idx = idx;
 306         prog->instances.fds = NULL;
 307         prog->instances.nr = -1;
 308         prog->type = BPF_PROG_TYPE_KPROBE;
 309
 310         return 0;
 311 errout:
 312         bpf_program__exit(prog);
 313         return -ENOMEM;
 314 }
 315
 316 static int
 317 bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
 318                         char *name, int idx)
 319 {
 320         struct bpf_program prog, *progs;
 321         int nr_progs, err;
 322
 323         err = bpf_program__init(data, size, name, idx, &prog);
 324         if (err)
 325                 return err;
 326
 327         progs = obj->programs;
 328         nr_progs = obj->nr_programs;
 329
 330         progs = realloc(progs, sizeof(progs[0]) * (nr_progs + 1));
 331         if (!progs) {
 332                 /*
 333                  * In this case the original obj->programs
 334                  * is still valid, so don't need special treat for
 335                  * bpf_close_object().
 336                  */
 337                 pr_warning("failed to alloc a new program '%s'\n",
 338                            name);
 339                 bpf_program__exit(&prog);
 340                 return -ENOMEM;
 341         }
 342
 343         pr_debug("found program %s\n", prog.section_name);
 344         obj->programs = progs;
 345         obj->nr_programs = nr_progs + 1;
 346         prog.obj = obj;
 347         progs[nr_progs] = prog;
 348         return 0;
 349 }
 350
 351 static struct bpf_object *bpf_object__new(const char *path,
 352                                           void *obj_buf,
 353                                           size_t obj_buf_sz)
 354 {
 355         struct bpf_object *obj;
 356
 357         obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
 358         if (!obj) {
 359                 pr_warning("alloc memory failed for %s\n", path);
 360                 return ERR_PTR(-ENOMEM);
 361         }
 362
 363         strcpy(obj->path, path);
 364         obj->efile.fd = -1;
 365
 366         /*
 367          * Caller of this function should also calls
 368          * bpf_object__elf_finish() after data collection to return
 369          * obj_buf to user. If not, we should duplicate the buffer to
 370          * avoid user freeing them before elf finish.
 371          */
 372         obj->efile.obj_buf = obj_buf;
 373         obj->efile.obj_buf_sz = obj_buf_sz;
 374         obj->efile.maps_shndx = -1;
 375
 376         obj->loaded = false;
 377
 378         INIT_LIST_HEAD(&obj->list);
 379         list_add(&obj->list, &bpf_objects_list);
 380         return obj;
 381 }
 382
 383 static void bpf_object__elf_finish(struct bpf_object *obj)
 384 {
 385         if (!obj_elf_valid(obj))
 386                 return;
 387
 388         if (obj->efile.elf) {
 389                 elf_end(obj->efile.elf);
 390                 obj->efile.elf = NULL;
 391         }
 392         obj->efile.symbols = NULL;
 393
 394         zfree(&obj->efile.reloc);
 395         obj->efile.nr_reloc = 0;
 396         zclose(obj->efile.fd);
 397         obj->efile.obj_buf = NULL;
 398         obj->efile.obj_buf_sz = 0;
 399 }
 400
 401 static int bpf_object__elf_init(struct bpf_object *obj)
 402 {
 403         int err = 0;
 404         GElf_Ehdr *ep;
 405
 406         if (obj_elf_valid(obj)) {
 407                 pr_warning("elf init: internal error\n");
 408                 return -LIBBPF_ERRNO__LIBELF;
 409         }
 410
 411         if (obj->efile.obj_buf_sz > 0) {
 412                 /*
 413                  * obj_buf should have been validated by
 414                  * bpf_object__open_buffer().
 415                  */
 416                 obj->efile.elf = elf_memory(obj->efile.obj_buf,
 417                                             obj->efile.obj_buf_sz);
 418         } else {
 419                 obj->efile.fd = open(obj->path, O_RDONLY);
 420                 if (obj->efile.fd < 0) {
 421                         pr_warning("failed to open %s: %s\n", obj->path,
 422                                         strerror(errno));
 423                         return -errno;
 424                 }
 425
 426                 obj->efile.elf = elf_begin(obj->efile.fd,
 427                                 LIBBPF_ELF_C_READ_MMAP,
 428                                 NULL);
 429         }
 430
 431         if (!obj->efile.elf) {
 432                 pr_warning("failed to open %s as ELF file\n",
 433                                 obj->path);
 434                 err = -LIBBPF_ERRNO__LIBELF;
 435                 goto errout;
 436         }
 437
 438         if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) {
 439                 pr_warning("failed to get EHDR from %s\n",
 440                                 obj->path);
 441                 err = -LIBBPF_ERRNO__FORMAT;
 442                 goto errout;
 443         }
 444         ep = &obj->efile.ehdr;
 445
 446         /* Old LLVM set e_machine to EM_NONE */
 447         if ((ep->e_type != ET_REL) || (ep->e_machine && (ep->e_machine != EM_BPF))) {
 448                 pr_warning("%s is not an eBPF object file\n",
 449                         obj->path);
 450                 err = -LIBBPF_ERRNO__FORMAT;
 451                 goto errout;
 452         }
 453
 454         return 0;
 455 errout:
 456         bpf_object__elf_finish(obj);
 457         return err;
 458 }
 459
 460 static int
 461 bpf_object__check_endianness(struct bpf_object *obj)
 462 {
 463         static unsigned int const endian = 1;
 464
 465         switch (obj->efile.ehdr.e_ident[EI_DATA]) {
 466         case ELFDATA2LSB:
 467                 /* We are big endian, BPF obj is little endian. */
 468                 if (*(unsigned char const *)&endian != 1)
 469                         goto mismatch;
 470                 break;
 471
 472         case ELFDATA2MSB:
 473                 /* We are little endian, BPF obj is big endian. */
 474                 if (*(unsigned char const *)&endian != 0)
 475                         goto mismatch;
 476                 break;
 477         default:
 478                 return -LIBBPF_ERRNO__ENDIAN;
 479         }
 480
 481         return 0;
 482
 483 mismatch:
 484         pr_warning("Error: endianness mismatch.\n");
 485         return -LIBBPF_ERRNO__ENDIAN;
 486 }
 487
 488 static int
 489 bpf_object__init_license(struct bpf_object *obj,
 490                          void *data, size_t size)
 491 {
 492         memcpy(obj->license, data,
 493                min(size, sizeof(obj->license) - 1));
 494         pr_debug("license of %s is %s\n", obj->path, obj->license);
 495         return 0;
 496 }
 497
 498 static int
 499 bpf_object__init_kversion(struct bpf_object *obj,
 500                           void *data, size_t size)
 501 {
 502         u32 kver;
 503
 504         if (size != sizeof(kver)) {
 505                 pr_warning("invalid kver section in %s\n", obj->path);
 506                 return -LIBBPF_ERRNO__FORMAT;
 507         }
 508         memcpy(&kver, data, sizeof(kver));
 509         obj->kern_version = kver;
 510         pr_debug("kernel version of %s is %x\n", obj->path,
 511                  obj->kern_version);
 512         return 0;
 513 }
 514
 515 static int
 516 bpf_object__init_maps(struct bpf_object *obj, void *data,
 517                       size_t size)
 518 {
 519         size_t nr_maps;
 520         int i;
 521
 522         nr_maps = size / sizeof(struct bpf_map_def);
 523         if (!data || !nr_maps) {
 524                 pr_debug("%s doesn't need map definition\n",
 525                          obj->path);
 526                 return 0;
 527         }
 528
 529         pr_debug("maps in %s: %zd bytes\n", obj->path, size);
 530
 531         obj->maps = calloc(nr_maps, sizeof(obj->maps[0]));
 532         if (!obj->maps) {
 533                 pr_warning("alloc maps for object failed\n");
 534                 return -ENOMEM;
 535         }
 536         obj->nr_maps = nr_maps;
 537
 538         for (i = 0; i < nr_maps; i++) {
 539                 struct bpf_map_def *def = &obj->maps[i].def;
 540
 541                 /*
 542                  * fill all fd with -1 so won't close incorrect
 543                  * fd (fd=0 is stdin) when failure (zclose won't close
 544                  * negative fd)).
 545                  */
 546                 obj->maps[i].fd = -1;
 547
 548                 /* Save map definition into obj->maps */
 549                 *def = ((struct bpf_map_def *)data)[i];
 550         }
 551         return 0;
 552 }
 553
 554 static int
 555 bpf_object__init_maps_name(struct bpf_object *obj)
 556 {
 557         int i;
 558         Elf_Data *symbols = obj->efile.symbols;
 559
 560         if (!symbols || obj->efile.maps_shndx < 0)
 561                 return -EINVAL;
 562
 563         for (i = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) {
 564                 GElf_Sym sym;
 565                 size_t map_idx;
 566                 const char *map_name;
 567
 568                 if (!gelf_getsym(symbols, i, &sym))
 569                         continue;
 570                 if (sym.st_shndx != obj->efile.maps_shndx)
 571                         continue;
 572
 573                 map_name = elf_strptr(obj->efile.elf,
 574                                       obj->efile.strtabidx,
 575                                       sym.st_name);
 576                 map_idx = sym.st_value / sizeof(struct bpf_map_def);
 577                 if (map_idx >= obj->nr_maps) {
 578                         pr_warning("index of map \"%s\" is buggy: %zu > %zu\n",
 579                                    map_name, map_idx, obj->nr_maps);
 580                         continue;
 581                 }
 582                 obj->maps[map_idx].name = strdup(map_name);
 583                 if (!obj->maps[map_idx].name) {
 584                         pr_warning("failed to alloc map name\n");
 585                         return -ENOMEM;
 586                 }
 587                 pr_debug("map %zu is \"%s\"\n", map_idx,
 588                          obj->maps[map_idx].name);
 589         }
 590         return 0;
 591 }
 592
 593 static int bpf_object__elf_collect(struct bpf_object *obj)
 594 {
 595         Elf *elf = obj->efile.elf;
 596         GElf_Ehdr *ep = &obj->efile.ehdr;
 597         Elf_Scn *scn = NULL;
 598         int idx = 0, err = 0;
 599
 600         /* Elf is corrupted/truncated, avoid calling elf_strptr. */
 601         if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) {
 602                 pr_warning("failed to get e_shstrndx from %s\n",
 603                            obj->path);
 604                 return -LIBBPF_ERRNO__FORMAT;
 605         }
 606
 607         while ((scn = elf_nextscn(elf, scn)) != NULL) {
 608                 char *name;
 609                 GElf_Shdr sh;
 610                 Elf_Data *data;
 611
 612                 idx++;
 613                 if (gelf_getshdr(scn, &sh) != &sh) {
 614                         pr_warning("failed to get section header from %s\n",
 615                                    obj->path);
 616                         err = -LIBBPF_ERRNO__FORMAT;
 617                         goto out;
 618                 }
 619
 620                 name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
 621                 if (!name) {
 622                         pr_warning("failed to get section name from %s\n",
 623                                    obj->path);
 624                         err = -LIBBPF_ERRNO__FORMAT;
 625                         goto out;
 626                 }
 627
 628                 data = elf_getdata(scn, 0);
 629                 if (!data) {
 630                         pr_warning("failed to get section data from %s(%s)\n",
 631                                    name, obj->path);
 632                         err = -LIBBPF_ERRNO__FORMAT;
 633                         goto out;
 634                 }
 635                 pr_debug("section %s, size %ld, link %d, flags %lx, type=%d\n",
 636                          name, (unsigned long)data->d_size,
 637                          (int)sh.sh_link, (unsigned long)sh.sh_flags,
 638                          (int)sh.sh_type);
 639
 640                 if (strcmp(name, "license") == 0)
 641                         err = bpf_object__init_license(obj,
 642                                                        data->d_buf,
 643                                                        data->d_size);
 644                 else if (strcmp(name, "version") == 0)
 645                         err = bpf_object__init_kversion(obj,
 646                                                         data->d_buf,
 647                                                         data->d_size);
 648                 else if (strcmp(name, "maps") == 0) {
 649                         err = bpf_object__init_maps(obj, data->d_buf,
 650                                                     data->d_size);
 651                         obj->efile.maps_shndx = idx;
 652                 } else if (sh.sh_type == SHT_SYMTAB) {
 653                         if (obj->efile.symbols) {
 654                                 pr_warning("bpf: multiple SYMTAB in %s\n",
 655                                            obj->path);
 656                                 err = -LIBBPF_ERRNO__FORMAT;
 657                         } else {
 658                                 obj->efile.symbols = data;
 659                                 obj->efile.strtabidx = sh.sh_link;
 660                         }
 661                 } else if ((sh.sh_type == SHT_PROGBITS) &&
 662                            (sh.sh_flags & SHF_EXECINSTR) &&
 663                            (data->d_size > 0)) {
 664                         err = bpf_object__add_program(obj, data->d_buf,
 665                                                       data->d_size, name, idx);
 666                         if (err) {
 667                                 char errmsg[STRERR_BUFSIZE];
 668
 669                                 strerror_r(-err, errmsg, sizeof(errmsg));
 670                                 pr_warning("failed to alloc program %s (%s): %s",
 671                                            name, obj->path, errmsg);
 672                         }
 673                 } else if (sh.sh_type == SHT_REL) {
 674                         void *reloc = obj->efile.reloc;
 675                         int nr_reloc = obj->efile.nr_reloc + 1;
 676
 677                         reloc = realloc(reloc,
 678                                         sizeof(*obj->efile.reloc) * nr_reloc);
 679                         if (!reloc) {
 680                                 pr_warning("realloc failed\n");
 681                                 err = -ENOMEM;
 682                         } else {
 683                                 int n = nr_reloc - 1;
 684
 685                                 obj->efile.reloc = reloc;
 686                                 obj->efile.nr_reloc = nr_reloc;
 687
 688                                 obj->efile.reloc[n].shdr = sh;
 689                                 obj->efile.reloc[n].data = data;
 690                         }
 691                 }
 692                 if (err)
 693                         goto out;
 694         }
 695
 696         if (!obj->efile.strtabidx || obj->efile.strtabidx >= idx) {
 697                 pr_warning("Corrupted ELF file: index of strtab invalid\n");
 698                 return LIBBPF_ERRNO__FORMAT;
 699         }
 700         if (obj->efile.maps_shndx >= 0)
 701                 err = bpf_object__init_maps_name(obj);
 702 out:
 703         return err;
 704 }
 705
 706 static struct bpf_program *
 707 bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
 708 {
 709         struct bpf_program *prog;
 710         size_t i;
 711
 712         for (i = 0; i < obj->nr_programs; i++) {
 713                 prog = &obj->programs[i];
 714                 if (prog->idx == idx)
 715                         return prog;
 716         }
 717         return NULL;
 718 }
 719
 720 static int
 721 bpf_program__collect_reloc(struct bpf_program *prog,
 722                            size_t nr_maps, GElf_Shdr *shdr,
 723                            Elf_Data *data, Elf_Data *symbols,
 724                            int maps_shndx)
 725 {
 726         int i, nrels;
 727
 728         pr_debug("collecting relocating info for: '%s'\n",
 729                  prog->section_name);
 730         nrels = shdr->sh_size / shdr->sh_entsize;
 731
 732         prog->reloc_desc = malloc(sizeof(*prog->reloc_desc) * nrels);
 733         if (!prog->reloc_desc) {
 734                 pr_warning("failed to alloc memory in relocation\n");
 735                 return -ENOMEM;
 736         }
 737         prog->nr_reloc = nrels;
 738
 739         for (i = 0; i < nrels; i++) {
 740                 GElf_Sym sym;
 741                 GElf_Rel rel;
 742                 unsigned int insn_idx;
 743                 struct bpf_insn *insns = prog->insns;
 744                 size_t map_idx;
 745
 746                 if (!gelf_getrel(data, i, &rel)) {
 747                         pr_warning("relocation: failed to get %d reloc\n", i);
 748                         return -LIBBPF_ERRNO__FORMAT;
 749                 }
 750
 751                 if (!gelf_getsym(symbols,
 752                                  GELF_R_SYM(rel.r_info),
 753                                  &sym)) {
 754                         pr_warning("relocation: symbol %"PRIx64" not found\n",
 755                                    GELF_R_SYM(rel.r_info));
 756                         return -LIBBPF_ERRNO__FORMAT;
 757                 }
 758
 759                 if (sym.st_shndx != maps_shndx) {
 760                         pr_warning("Program '%s' contains non-map related relo data pointing to section %u\n",
 761                                    prog->section_name, sym.st_shndx);
 762                         return -LIBBPF_ERRNO__RELOC;
 763                 }
 764
 765                 insn_idx = rel.r_offset / sizeof(struct bpf_insn);
 766                 pr_debug("relocation: insn_idx=%u\n", insn_idx);
 767
 768                 if (insns[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
 769                         pr_warning("bpf: relocation: invalid relo for insns[%d].code 0x%x\n",
 770                                    insn_idx, insns[insn_idx].code);
 771                         return -LIBBPF_ERRNO__RELOC;
 772                 }
 773
 774                 map_idx = sym.st_value / sizeof(struct bpf_map_def);
 775                 if (map_idx >= nr_maps) {
 776                         pr_warning("bpf relocation: map_idx %d large than %d\n",
 777                                    (int)map_idx, (int)nr_maps - 1);
 778                         return -LIBBPF_ERRNO__RELOC;
 779                 }
 780
 781                 prog->reloc_desc[i].insn_idx = insn_idx;
 782                 prog->reloc_desc[i].map_idx = map_idx;
 783         }
 784         return 0;
 785 }
 786
 787 static int
 788 bpf_object__create_maps(struct bpf_object *obj)
 789 {
 790         unsigned int i;
 791
 792         for (i = 0; i < obj->nr_maps; i++) {
 793                 struct bpf_map_def *def = &obj->maps[i].def;
 794                 int *pfd = &obj->maps[i].fd;
 795
 796                 *pfd = bpf_create_map(def->type,
 797                                       def->key_size,
 798                                       def->value_size,
 799                                       def->max_entries);
 800                 if (*pfd < 0) {
 801                         size_t j;
 802                         int err = *pfd;
 803
 804                         pr_warning("failed to create map: %s\n",
 805                                    strerror(errno));
 806                         for (j = 0; j < i; j++)
 807                                 zclose(obj->maps[j].fd);
 808                         return err;
 809                 }
 810                 pr_debug("create map: fd=%d\n", *pfd);
 811         }
 812
 813         return 0;
 814 }
 815
 816 static int
 817 bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
 818 {
 819         int i;
 820
 821         if (!prog || !prog->reloc_desc)
 822                 return 0;
 823
 824         for (i = 0; i < prog->nr_reloc; i++) {
 825                 int insn_idx, map_idx;
 826                 struct bpf_insn *insns = prog->insns;
 827
 828                 insn_idx = prog->reloc_desc[i].insn_idx;
 829                 map_idx = prog->reloc_desc[i].map_idx;
 830
 831                 if (insn_idx >= (int)prog->insns_cnt) {
 832                         pr_warning("relocation out of range: '%s'\n",
 833                                    prog->section_name);
 834                         return -LIBBPF_ERRNO__RELOC;
 835                 }
 836                 insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
 837                 insns[insn_idx].imm = obj->maps[map_idx].fd;
 838         }
 839
 840         zfree(&prog->reloc_desc);
 841         prog->nr_reloc = 0;
 842         return 0;
 843 }
 844
 845
 846 static int
 847 bpf_object__relocate(struct bpf_object *obj)
 848 {
 849         struct bpf_program *prog;
 850         size_t i;
 851         int err;
 852
 853         for (i = 0; i < obj->nr_programs; i++) {
 854                 prog = &obj->programs[i];
 855
 856                 err = bpf_program__relocate(prog, obj);
 857                 if (err) {
 858                         pr_warning("failed to relocate '%s'\n",
 859                                    prog->section_name);
 860                         return err;
 861                 }
 862         }
 863         return 0;
 864 }
 865
 866 static int bpf_object__collect_reloc(struct bpf_object *obj)
 867 {
 868         int i, err;
 869
 870         if (!obj_elf_valid(obj)) {
 871                 pr_warning("Internal error: elf object is closed\n");
 872                 return -LIBBPF_ERRNO__INTERNAL;
 873         }
 874
 875         for (i = 0; i < obj->efile.nr_reloc; i++) {
 876                 GElf_Shdr *shdr = &obj->efile.reloc[i].shdr;
 877                 Elf_Data *data = obj->efile.reloc[i].data;
 878                 int idx = shdr->sh_info;
 879                 struct bpf_program *prog;
 880                 size_t nr_maps = obj->nr_maps;
 881
 882                 if (shdr->sh_type != SHT_REL) {
 883                         pr_warning("internal error at %d\n", __LINE__);
 884                         return -LIBBPF_ERRNO__INTERNAL;
 885                 }
 886
 887                 prog = bpf_object__find_prog_by_idx(obj, idx);
 888                 if (!prog) {
 889                         pr_warning("relocation failed: no %d section\n",
 890                                    idx);
 891                         return -LIBBPF_ERRNO__RELOC;
 892                 }
 893
 894                 err = bpf_program__collect_reloc(prog, nr_maps,
 895                                                  shdr, data,
 896                                                  obj->efile.symbols,
 897                                                  obj->efile.maps_shndx);
 898                 if (err)
 899                         return err;
 900         }
 901         return 0;
 902 }
 903
 904 static int
 905 load_program(enum bpf_prog_type type, struct bpf_insn *insns,
 906              int insns_cnt, char *license, u32 kern_version, int *pfd)
 907 {
 908         int ret;
 909         char *log_buf;
 910
 911         if (!insns || !insns_cnt)
 912                 return -EINVAL;
 913
 914         log_buf = malloc(BPF_LOG_BUF_SIZE);
 915         if (!log_buf)
 916                 pr_warning("Alloc log buffer for bpf loader error, continue without log\n");
 917
 918         ret = bpf_load_program(type, insns, insns_cnt, license,
 919                                kern_version, log_buf, BPF_LOG_BUF_SIZE);
 920
 921         if (ret >= 0) {
 922                 *pfd = ret;
 923                 ret = 0;
 924                 goto out;
 925         }
 926
 927         ret = -LIBBPF_ERRNO__LOAD;
 928         pr_warning("load bpf program failed: %s\n", strerror(errno));
 929
 930         if (log_buf && log_buf[0] != '\0') {
 931                 ret = -LIBBPF_ERRNO__VERIFY;
 932                 pr_warning("-- BEGIN DUMP LOG ---\n");
 933                 pr_warning("\n%s\n", log_buf);
 934                 pr_warning("-- END LOG --\n");
 935         } else if (insns_cnt >= BPF_MAXINSNS) {
 936                 pr_warning("Program too large (%d insns), at most %d insns\n",
 937                            insns_cnt, BPF_MAXINSNS);
 938                 ret = -LIBBPF_ERRNO__PROG2BIG;
 939         } else {
 940                 /* Wrong program type? */
 941                 if (type != BPF_PROG_TYPE_KPROBE) {
 942                         int fd;
 943
 944                         fd = bpf_load_program(BPF_PROG_TYPE_KPROBE, insns,
 945                                               insns_cnt, license, kern_version,
 946                                               NULL, 0);
 947                         if (fd >= 0) {
 948                                 close(fd);
 949                                 ret = -LIBBPF_ERRNO__PROGTYPE;
 950                                 goto out;
 951                         }
 952                 }
 953
 954                 if (log_buf)
 955                         ret = -LIBBPF_ERRNO__KVER;
 956         }
 957
 958 out:
 959         free(log_buf);
 960         return ret;
 961 }
 962
 963 static int
 964 bpf_program__load(struct bpf_program *prog,
 965                   char *license, u32 kern_version)
 966 {
 967         int err = 0, fd, i;
 968
 969         if (prog->instances.nr < 0 || !prog->instances.fds) {
 970                 if (prog->preprocessor) {
 971                         pr_warning("Internal error: can't load program '%s'\n",
 972                                    prog->section_name);
 973                         return -LIBBPF_ERRNO__INTERNAL;
 974                 }
 975
 976                 prog->instances.fds = malloc(sizeof(int));
 977                 if (!prog->instances.fds) {
 978                         pr_warning("Not enough memory for BPF fds\n");
 979                         return -ENOMEM;
 980                 }
 981                 prog->instances.nr = 1;
 982                 prog->instances.fds[0] = -1;
 983         }
 984
 985         if (!prog->preprocessor) {
 986                 if (prog->instances.nr != 1) {
 987                         pr_warning("Program '%s' is inconsistent: nr(%d) != 1\n",
 988                                    prog->section_name, prog->instances.nr);
 989                 }
 990                 err = load_program(prog->type, prog->insns, prog->insns_cnt,
 991                                    license, kern_version, &fd);
 992                 if (!err)
 993                         prog->instances.fds[0] = fd;
 994                 goto out;
 995         }
 996
 997         for (i = 0; i < prog->instances.nr; i++) {
 998                 struct bpf_prog_prep_result result;
 999                 bpf_program_prep_t preprocessor = prog->preprocessor;
1000
1001                 bzero(&result, sizeof(result));
1002                 err = preprocessor(prog, i, prog->insns,
1003                                    prog->insns_cnt, &result);
1004                 if (err) {
1005                         pr_warning("Preprocessing the %dth instance of program '%s' failed\n",
1006                                    i, prog->section_name);
1007                         goto out;
1008                 }
1009
1010                 if (!result.new_insn_ptr || !result.new_insn_cnt) {
1011                         pr_debug("Skip loading the %dth instance of program '%s'\n",
1012                                  i, prog->section_name);
1013                         prog->instances.fds[i] = -1;
1014                         if (result.pfd)
1015                                 *result.pfd = -1;
1016                         continue;
1017                 }
1018
1019                 err = load_program(prog->type, result.new_insn_ptr,
1020                                    result.new_insn_cnt,
1021                                    license, kern_version, &fd);
1022
1023                 if (err) {
1024                         pr_warning("Loading the %dth instance of program '%s' failed\n",
1025                                         i, prog->section_name);
1026                         goto out;
1027                 }
1028
1029                 if (result.pfd)
1030                         *result.pfd = fd;
1031                 prog->instances.fds[i] = fd;
1032         }
1033 out:
1034         if (err)
1035                 pr_warning("failed to load program '%s'\n",
1036                            prog->section_name);
1037         zfree(&prog->insns);
1038         prog->insns_cnt = 0;
1039         return err;
1040 }
1041
1042 static int
1043 bpf_object__load_progs(struct bpf_object *obj)
1044 {
1045         size_t i;
1046         int err;
1047
1048         for (i = 0; i < obj->nr_programs; i++) {
1049                 err = bpf_program__load(&obj->programs[i],
1050                                         obj->license,
1051                                         obj->kern_version);
1052                 if (err)
1053                         return err;
1054         }
1055         return 0;
1056 }
1057
1058 static int bpf_object__validate(struct bpf_object *obj)
1059 {
1060         if (obj->kern_version == 0) {
1061                 pr_warning("%s doesn't provide kernel version\n",
1062                            obj->path);
1063                 return -LIBBPF_ERRNO__KVERSION;
1064         }
1065         return 0;
1066 }
1067
1068 static struct bpf_object *
1069 __bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz)
1070 {
1071         struct bpf_object *obj;
1072         int err;
1073
1074         if (elf_version(EV_CURRENT) == EV_NONE) {
1075                 pr_warning("failed to init libelf for %s\n", path);
1076                 return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
1077         }
1078
1079         obj = bpf_object__new(path, obj_buf, obj_buf_sz);
1080         if (IS_ERR(obj))
1081                 return obj;
1082
1083         CHECK_ERR(bpf_object__elf_init(obj), err, out);
1084         CHECK_ERR(bpf_object__check_endianness(obj), err, out);
1085         CHECK_ERR(bpf_object__elf_collect(obj), err, out);
1086         CHECK_ERR(bpf_object__collect_reloc(obj), err, out);
1087         CHECK_ERR(bpf_object__validate(obj), err, out);
1088
1089         bpf_object__elf_finish(obj);
1090         return obj;
1091 out:
1092         bpf_object__close(obj);
1093         return ERR_PTR(err);
1094 }
1095
1096 struct bpf_object *bpf_object__open(const char *path)
1097 {
1098         /* param validation */
1099         if (!path)
1100                 return NULL;
1101
1102         pr_debug("loading %s\n", path);
1103
1104         return __bpf_object__open(path, NULL, 0);
1105 }
1106
1107 struct bpf_object *bpf_object__open_buffer(void *obj_buf,
1108                                            size_t obj_buf_sz,
1109                                            const char *name)
1110 {
1111         char tmp_name[64];
1112
1113         /* param validation */
1114         if (!obj_buf || obj_buf_sz <= 0)
1115                 return NULL;
1116
1117         if (!name) {
1118                 snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
1119                          (unsigned long)obj_buf,
1120                          (unsigned long)obj_buf_sz);
1121                 tmp_name[sizeof(tmp_name) - 1] = '\0';
1122                 name = tmp_name;
1123         }
1124         pr_debug("loading object '%s' from buffer\n",
1125                  name);
1126
1127         return __bpf_object__open(name, obj_buf, obj_buf_sz);
1128 }
1129
1130 int bpf_object__unload(struct bpf_object *obj)
1131 {
1132         size_t i;
1133
1134         if (!obj)
1135                 return -EINVAL;
1136
1137         for (i = 0; i < obj->nr_maps; i++)
1138                 zclose(obj->maps[i].fd);
1139
1140         for (i = 0; i < obj->nr_programs; i++)
1141                 bpf_program__unload(&obj->programs[i]);
1142
1143         return 0;
1144 }
1145
1146 int bpf_object__load(struct bpf_object *obj)
1147 {
1148         int err;
1149
1150         if (!obj)
1151                 return -EINVAL;
1152
1153         if (obj->loaded) {
1154                 pr_warning("object should not be loaded twice\n");
1155                 return -EINVAL;
1156         }
1157
1158         obj->loaded = true;
1159
1160         CHECK_ERR(bpf_object__create_maps(obj), err, out);
1161         CHECK_ERR(bpf_object__relocate(obj), err, out);
1162         CHECK_ERR(bpf_object__load_progs(obj), err, out);
1163
1164         return 0;
1165 out:
1166         bpf_object__unload(obj);
1167         pr_warning("failed to load object '%s'\n", obj->path);
1168         return err;
1169 }
1170
1171 void bpf_object__close(struct bpf_object *obj)
1172 {
1173         size_t i;
1174
1175         if (!obj)
1176                 return;
1177
1178         bpf_object__elf_finish(obj);
1179         bpf_object__unload(obj);
1180
1181         for (i = 0; i < obj->nr_maps; i++) {
1182                 zfree(&obj->maps[i].name);
1183                 if (obj->maps[i].clear_priv)
1184                         obj->maps[i].clear_priv(&obj->maps[i],
1185                                                 obj->maps[i].priv);
1186                 obj->maps[i].priv = NULL;
1187                 obj->maps[i].clear_priv = NULL;
1188         }
1189         zfree(&obj->maps);
1190         obj->nr_maps = 0;
1191
1192         if (obj->programs && obj->nr_programs) {
1193                 for (i = 0; i < obj->nr_programs; i++)
1194                         bpf_program__exit(&obj->programs[i]);
1195         }
1196         zfree(&obj->programs);
1197
1198         list_del(&obj->list);
1199         free(obj);
1200 }
1201
1202 struct bpf_object *
1203 bpf_object__next(struct bpf_object *prev)
1204 {
1205         struct bpf_object *next;
1206
1207         if (!prev)
1208                 next = list_first_entry(&bpf_objects_list,
1209                                         struct bpf_object,
1210                                         list);
1211         else
1212                 next = list_next_entry(prev, list);
1213
1214         /* Empty list is noticed here so don't need checking on entry. */
1215         if (&next->list == &bpf_objects_list)
1216                 return NULL;
1217
1218         return next;
1219 }
1220
1221 const char *bpf_object__name(struct bpf_object *obj)
1222 {
1223         return obj ? obj->path : ERR_PTR(-EINVAL);
1224 }
1225
1226 unsigned int bpf_object__kversion(struct bpf_object *obj)
1227 {
1228         return obj ? obj->kern_version : 0;
1229 }
1230
1231 struct bpf_program *
1232 bpf_program__next(struct bpf_program *prev, struct bpf_object *obj)
1233 {
1234         size_t idx;
1235
1236         if (!obj->programs)
1237                 return NULL;
1238         /* First handler */
1239         if (prev == NULL)
1240                 return &obj->programs[0];
1241
1242         if (prev->obj != obj) {
1243                 pr_warning("error: program handler doesn't match object\n");
1244                 return NULL;
1245         }
1246
1247         idx = (prev - obj->programs) + 1;
1248         if (idx >= obj->nr_programs)
1249                 return NULL;
1250         return &obj->programs[idx];
1251 }
1252
1253 int bpf_program__set_priv(struct bpf_program *prog, void *priv,
1254                           bpf_program_clear_priv_t clear_priv)
1255 {
1256         if (prog->priv && prog->clear_priv)
1257                 prog->clear_priv(prog, prog->priv);
1258
1259         prog->priv = priv;
1260         prog->clear_priv = clear_priv;
1261         return 0;
1262 }
1263
1264 void *bpf_program__priv(struct bpf_program *prog)
1265 {
1266         return prog ? prog->priv : ERR_PTR(-EINVAL);
1267 }
1268
1269 const char *bpf_program__title(struct bpf_program *prog, bool needs_copy)
1270 {
1271         const char *title;
1272
1273         title = prog->section_name;
1274         if (needs_copy) {
1275                 title = strdup(title);
1276                 if (!title) {
1277                         pr_warning("failed to strdup program title\n");
1278                         return ERR_PTR(-ENOMEM);
1279                 }
1280         }
1281
1282         return title;
1283 }
1284
1285 int bpf_program__fd(struct bpf_program *prog)
1286 {
1287         return bpf_program__nth_fd(prog, 0);
1288 }
1289
1290 int bpf_program__set_prep(struct bpf_program *prog, int nr_instances,
1291                           bpf_program_prep_t prep)
1292 {
1293         int *instances_fds;
1294
1295         if (nr_instances <= 0 || !prep)
1296                 return -EINVAL;
1297
1298         if (prog->instances.nr > 0 || prog->instances.fds) {
1299                 pr_warning("Can't set pre-processor after loading\n");
1300                 return -EINVAL;
1301         }
1302
1303         instances_fds = malloc(sizeof(int) * nr_instances);
1304         if (!instances_fds) {
1305                 pr_warning("alloc memory failed for fds\n");
1306                 return -ENOMEM;
1307         }
1308
1309         /* fill all fd with -1 */
1310         memset(instances_fds, -1, sizeof(int) * nr_instances);
1311
1312         prog->instances.nr = nr_instances;
1313         prog->instances.fds = instances_fds;
1314         prog->preprocessor = prep;
1315         return 0;
1316 }
1317
1318 int bpf_program__nth_fd(struct bpf_program *prog, int n)
1319 {
1320         int fd;
1321
1322         if (n >= prog->instances.nr || n < 0) {
1323                 pr_warning("Can't get the %dth fd from program %s: only %d instances\n",
1324                            n, prog->section_name, prog->instances.nr);
1325                 return -EINVAL;
1326         }
1327
1328         fd = prog->instances.fds[n];
1329         if (fd < 0) {
1330                 pr_warning("%dth instance of program '%s' is invalid\n",
1331                            n, prog->section_name);
1332                 return -ENOENT;
1333         }
1334
1335         return fd;
1336 }
1337
1338 static void bpf_program__set_type(struct bpf_program *prog,
1339                                   enum bpf_prog_type type)
1340 {
1341         prog->type = type;
1342 }
1343
1344 int bpf_program__set_tracepoint(struct bpf_program *prog)
1345 {
1346         if (!prog)
1347                 return -EINVAL;
1348         bpf_program__set_type(prog, BPF_PROG_TYPE_TRACEPOINT);
1349         return 0;
1350 }
1351
1352 int bpf_program__set_kprobe(struct bpf_program *prog)
1353 {
1354         if (!prog)
1355                 return -EINVAL;
1356         bpf_program__set_type(prog, BPF_PROG_TYPE_KPROBE);
1357         return 0;
1358 }
1359
1360 static bool bpf_program__is_type(struct bpf_program *prog,
1361                                  enum bpf_prog_type type)
1362 {
1363         return prog ? (prog->type == type) : false;
1364 }
1365
1366 bool bpf_program__is_tracepoint(struct bpf_program *prog)
1367 {
1368         return bpf_program__is_type(prog, BPF_PROG_TYPE_TRACEPOINT);
1369 }
1370
1371 bool bpf_program__is_kprobe(struct bpf_program *prog)
1372 {
1373         return bpf_program__is_type(prog, BPF_PROG_TYPE_KPROBE);
1374 }
1375
1376 int bpf_map__fd(struct bpf_map *map)
1377 {
1378         return map ? map->fd : -EINVAL;
1379 }
1380
1381 const struct bpf_map_def *bpf_map__def(struct bpf_map *map)
1382 {
1383         return map ? &map->def : ERR_PTR(-EINVAL);
1384 }
1385
1386 const char *bpf_map__name(struct bpf_map *map)
1387 {
1388         return map ? map->name : NULL;
1389 }
1390
1391 int bpf_map__set_priv(struct bpf_map *map, void *priv,
1392                      bpf_map_clear_priv_t clear_priv)
1393 {
1394         if (!map)
1395                 return -EINVAL;
1396
1397         if (map->priv) {
1398                 if (map->clear_priv)
1399                         map->clear_priv(map, map->priv);
1400         }
1401
1402         map->priv = priv;
1403         map->clear_priv = clear_priv;
1404         return 0;
1405 }
1406
1407 void *bpf_map__priv(struct bpf_map *map)
1408 {
1409         return map ? map->priv : ERR_PTR(-EINVAL);
1410 }
1411
1412 struct bpf_map *
1413 bpf_map__next(struct bpf_map *prev, struct bpf_object *obj)
1414 {
1415         size_t idx;
1416         struct bpf_map *s, *e;
1417
1418         if (!obj || !obj->maps)
1419                 return NULL;
1420
1421         s = obj->maps;
1422         e = obj->maps + obj->nr_maps;
1423
1424         if (prev == NULL)
1425                 return s;
1426
1427         if ((prev < s) || (prev >= e)) {
1428                 pr_warning("error in %s: map handler doesn't belong to object\n",
1429                            __func__);
1430                 return NULL;
1431         }
1432
1433         idx = (prev - obj->maps) + 1;
1434         if (idx >= obj->nr_maps)
1435                 return NULL;
1436         return &obj->maps[idx];
1437 }
1438
1439 struct bpf_map *
1440 bpf_object__find_map_by_name(struct bpf_object *obj, const char *name)
1441 {
1442         struct bpf_map *pos;
1443
1444         bpf_map__for_each(pos, obj) {
1445                 if (pos->name && !strcmp(pos->name, name))
1446                         return pos;
1447         }
1448         return NULL;
1449 }