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
   9 #include <stdlib.h>
  10 #include <stdio.h>
  11 #include <stdarg.h>
  12 #include <inttypes.h>
  13 #include <string.h>
  14 #include <unistd.h>
  15 #include <fcntl.h>
  16 #include <errno.h>
  17 #include <asm/unistd.h>
  18 #include <linux/kernel.h>
  19 #include <linux/bpf.h>
  20 #include <linux/list.h>
  21 #include <libelf.h>
  22 #include <gelf.h>
  23
  24 #include "libbpf.h"
  25 #include "bpf.h"
  26
  27 #define __printf(a, b)  __attribute__((format(printf, a, b)))
  28
  29 __printf(1, 2)
  30 static int __base_pr(const char *format, ...)
  31 {
  32         va_list args;
  33         int err;
  34
  35         va_start(args, format);
  36         err = vfprintf(stderr, format, args);
  37         va_end(args);
  38         return err;
  39 }
  40
  41 static __printf(1, 2) libbpf_print_fn_t __pr_warning = __base_pr;
  42 static __printf(1, 2) libbpf_print_fn_t __pr_info = __base_pr;
  43 static __printf(1, 2) libbpf_print_fn_t __pr_debug;
  44
  45 #define __pr(func, fmt, ...)    \
  46 do {                            \
  47         if ((func))             \
  48                 (func)("libbpf: " fmt, ##__VA_ARGS__); \
  49 } while (0)
  50
  51 #define pr_warning(fmt, ...)    __pr(__pr_warning, fmt, ##__VA_ARGS__)
  52 #define pr_info(fmt, ...)       __pr(__pr_info, fmt, ##__VA_ARGS__)
  53 #define pr_debug(fmt, ...)      __pr(__pr_debug, fmt, ##__VA_ARGS__)
  54
  55 void libbpf_set_print(libbpf_print_fn_t warn,
  56                       libbpf_print_fn_t info,
  57                       libbpf_print_fn_t debug)
  58 {
  59         __pr_warning = warn;
  60         __pr_info = info;
  61         __pr_debug = debug;
  62 }
  63
  64 #define STRERR_BUFSIZE  128
  65
  66 #define ERRNO_OFFSET(e)         ((e) - __LIBBPF_ERRNO__START)
  67 #define ERRCODE_OFFSET(c)       ERRNO_OFFSET(LIBBPF_ERRNO__##c)
  68 #define NR_ERRNO        (__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START)
  69
  70 static const char *libbpf_strerror_table[NR_ERRNO] = {
  71         [ERRCODE_OFFSET(LIBELF)]        = "Something wrong in libelf",
  72         [ERRCODE_OFFSET(FORMAT)]        = "BPF object format invalid",
  73         [ERRCODE_OFFSET(KVERSION)]      = "'version' section incorrect or lost",
  74         [ERRCODE_OFFSET(ENDIAN)]        = "Endian missmatch",
  75         [ERRCODE_OFFSET(INTERNAL)]      = "Internal error in libbpf",
  76         [ERRCODE_OFFSET(RELOC)]         = "Relocation failed",
  77         [ERRCODE_OFFSET(VERIFY)]        = "Kernel verifier blocks program loading",
  78         [ERRCODE_OFFSET(PROG2BIG)]      = "Program too big",
  79         [ERRCODE_OFFSET(KVER)]          = "Incorrect kernel version",
  80 };
  81
  82 int libbpf_strerror(int err, char *buf, size_t size)
  83 {
  84         if (!buf || !size)
  85                 return -1;
  86
  87         err = err > 0 ? err : -err;
  88
  89         if (err < __LIBBPF_ERRNO__START) {
  90                 int ret;
  91
  92                 ret = strerror_r(err, buf, size);
  93                 buf[size - 1] = '\0';
  94                 return ret;
  95         }
  96
  97         if (err < __LIBBPF_ERRNO__END) {
  98                 const char *msg;
  99
 100                 msg = libbpf_strerror_table[ERRNO_OFFSET(err)];
 101                 snprintf(buf, size, "%s", msg);
 102                 buf[size - 1] = '\0';
 103                 return 0;
 104         }
 105
 106         snprintf(buf, size, "Unknown libbpf error %d", err);
 107         buf[size - 1] = '\0';
 108         return -1;
 109 }
 110
 111 #define CHECK_ERR(action, err, out) do {        \
 112         err = action;                   \
 113         if (err)                        \
 114                 goto out;               \
 115 } while(0)
 116
 117
 118 /* Copied from tools/perf/util/util.h */
 119 #ifndef zfree
 120 # define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
 121 #endif
 122
 123 #ifndef zclose
 124 # define zclose(fd) ({                  \
 125         int ___err = 0;                 \
 126         if ((fd) >= 0)                  \
 127                 ___err = close((fd));   \
 128         fd = -1;                        \
 129         ___err; })
 130 #endif
 131
 132 #ifdef HAVE_LIBELF_MMAP_SUPPORT
 133 # define LIBBPF_ELF_C_READ_MMAP ELF_C_READ_MMAP
 134 #else
 135 # define LIBBPF_ELF_C_READ_MMAP ELF_C_READ
 136 #endif
 137
 138 /*
 139  * bpf_prog should be a better name but it has been used in
 140  * linux/filter.h.
 141  */
 142 struct bpf_program {
 143         /* Index in elf obj file, for relocation use. */
 144         int idx;
 145         char *section_name;
 146         struct bpf_insn *insns;
 147         size_t insns_cnt;
 148
 149         struct {
 150                 int insn_idx;
 151                 int map_idx;
 152         } *reloc_desc;
 153         int nr_reloc;
 154
 155         int fd;
 156
 157         struct bpf_object *obj;
 158         void *priv;
 159         bpf_program_clear_priv_t clear_priv;
 160 };
 161
 162 static LIST_HEAD(bpf_objects_list);
 163
 164 struct bpf_object {
 165         char license[64];
 166         u32 kern_version;
 167         void *maps_buf;
 168         size_t maps_buf_sz;
 169
 170         struct bpf_program *programs;
 171         size_t nr_programs;
 172         int *map_fds;
 173         /*
 174          * This field is required because maps_buf will be freed and
 175          * maps_buf_sz will be set to 0 after loaded.
 176          */
 177         size_t nr_map_fds;
 178         bool loaded;
 179
 180         /*
 181          * Information when doing elf related work. Only valid if fd
 182          * is valid.
 183          */
 184         struct {
 185                 int fd;
 186                 void *obj_buf;
 187                 size_t obj_buf_sz;
 188                 Elf *elf;
 189                 GElf_Ehdr ehdr;
 190                 Elf_Data *symbols;
 191                 struct {
 192                         GElf_Shdr shdr;
 193                         Elf_Data *data;
 194                 } *reloc;
 195                 int nr_reloc;
 196         } efile;
 197         /*
 198          * All loaded bpf_object is linked in a list, which is
 199          * hidden to caller. bpf_objects__<func> handlers deal with
 200          * all objects.
 201          */
 202         struct list_head list;
 203         char path[];
 204 };
 205 #define obj_elf_valid(o)        ((o)->efile.elf)
 206
 207 static void bpf_program__unload(struct bpf_program *prog)
 208 {
 209         if (!prog)
 210                 return;
 211
 212         zclose(prog->fd);
 213 }
 214
 215 static void bpf_program__exit(struct bpf_program *prog)
 216 {
 217         if (!prog)
 218                 return;
 219
 220         if (prog->clear_priv)
 221                 prog->clear_priv(prog, prog->priv);
 222
 223         prog->priv = NULL;
 224         prog->clear_priv = NULL;
 225
 226         bpf_program__unload(prog);
 227         zfree(&prog->section_name);
 228         zfree(&prog->insns);
 229         zfree(&prog->reloc_desc);
 230
 231         prog->nr_reloc = 0;
 232         prog->insns_cnt = 0;
 233         prog->idx = -1;
 234 }
 235
 236 static int
 237 bpf_program__init(void *data, size_t size, char *name, int idx,
 238                     struct bpf_program *prog)
 239 {
 240         if (size < sizeof(struct bpf_insn)) {
 241                 pr_warning("corrupted section '%s'\n", name);
 242                 return -EINVAL;
 243         }
 244
 245         bzero(prog, sizeof(*prog));
 246
 247         prog->section_name = strdup(name);
 248         if (!prog->section_name) {
 249                 pr_warning("failed to alloc name for prog %s\n",
 250                            name);
 251                 goto errout;
 252         }
 253
 254         prog->insns = malloc(size);
 255         if (!prog->insns) {
 256                 pr_warning("failed to alloc insns for %s\n", name);
 257                 goto errout;
 258         }
 259         prog->insns_cnt = size / sizeof(struct bpf_insn);
 260         memcpy(prog->insns, data,
 261                prog->insns_cnt * sizeof(struct bpf_insn));
 262         prog->idx = idx;
 263         prog->fd = -1;
 264
 265         return 0;
 266 errout:
 267         bpf_program__exit(prog);
 268         return -ENOMEM;
 269 }
 270
 271 static int
 272 bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
 273                         char *name, int idx)
 274 {
 275         struct bpf_program prog, *progs;
 276         int nr_progs, err;
 277
 278         err = bpf_program__init(data, size, name, idx, &prog);
 279         if (err)
 280                 return err;
 281
 282         progs = obj->programs;
 283         nr_progs = obj->nr_programs;
 284
 285         progs = realloc(progs, sizeof(progs[0]) * (nr_progs + 1));
 286         if (!progs) {
 287                 /*
 288                  * In this case the original obj->programs
 289                  * is still valid, so don't need special treat for
 290                  * bpf_close_object().
 291                  */
 292                 pr_warning("failed to alloc a new program '%s'\n",
 293                            name);
 294                 bpf_program__exit(&prog);
 295                 return -ENOMEM;
 296         }
 297
 298         pr_debug("found program %s\n", prog.section_name);
 299         obj->programs = progs;
 300         obj->nr_programs = nr_progs + 1;
 301         prog.obj = obj;
 302         progs[nr_progs] = prog;
 303         return 0;
 304 }
 305
 306 static struct bpf_object *bpf_object__new(const char *path,
 307                                           void *obj_buf,
 308                                           size_t obj_buf_sz)
 309 {
 310         struct bpf_object *obj;
 311
 312         obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
 313         if (!obj) {
 314                 pr_warning("alloc memory failed for %s\n", path);
 315                 return ERR_PTR(-ENOMEM);
 316         }
 317
 318         strcpy(obj->path, path);
 319         obj->efile.fd = -1;
 320
 321         /*
 322          * Caller of this function should also calls
 323          * bpf_object__elf_finish() after data collection to return
 324          * obj_buf to user. If not, we should duplicate the buffer to
 325          * avoid user freeing them before elf finish.
 326          */
 327         obj->efile.obj_buf = obj_buf;
 328         obj->efile.obj_buf_sz = obj_buf_sz;
 329
 330         obj->loaded = false;
 331
 332         INIT_LIST_HEAD(&obj->list);
 333         list_add(&obj->list, &bpf_objects_list);
 334         return obj;
 335 }
 336
 337 static void bpf_object__elf_finish(struct bpf_object *obj)
 338 {
 339         if (!obj_elf_valid(obj))
 340                 return;
 341
 342         if (obj->efile.elf) {
 343                 elf_end(obj->efile.elf);
 344                 obj->efile.elf = NULL;
 345         }
 346         obj->efile.symbols = NULL;
 347
 348         zfree(&obj->efile.reloc);
 349         obj->efile.nr_reloc = 0;
 350         zclose(obj->efile.fd);
 351         obj->efile.obj_buf = NULL;
 352         obj->efile.obj_buf_sz = 0;
 353 }
 354
 355 static int bpf_object__elf_init(struct bpf_object *obj)
 356 {
 357         int err = 0;
 358         GElf_Ehdr *ep;
 359
 360         if (obj_elf_valid(obj)) {
 361                 pr_warning("elf init: internal error\n");
 362                 return -LIBBPF_ERRNO__LIBELF;
 363         }
 364
 365         if (obj->efile.obj_buf_sz > 0) {
 366                 /*
 367                  * obj_buf should have been validated by
 368                  * bpf_object__open_buffer().
 369                  */
 370                 obj->efile.elf = elf_memory(obj->efile.obj_buf,
 371                                             obj->efile.obj_buf_sz);
 372         } else {
 373                 obj->efile.fd = open(obj->path, O_RDONLY);
 374                 if (obj->efile.fd < 0) {
 375                         pr_warning("failed to open %s: %s\n", obj->path,
 376                                         strerror(errno));
 377                         return -errno;
 378                 }
 379
 380                 obj->efile.elf = elf_begin(obj->efile.fd,
 381                                 LIBBPF_ELF_C_READ_MMAP,
 382                                 NULL);
 383         }
 384
 385         if (!obj->efile.elf) {
 386                 pr_warning("failed to open %s as ELF file\n",
 387                                 obj->path);
 388                 err = -LIBBPF_ERRNO__LIBELF;
 389                 goto errout;
 390         }
 391
 392         if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) {
 393                 pr_warning("failed to get EHDR from %s\n",
 394                                 obj->path);
 395                 err = -LIBBPF_ERRNO__FORMAT;
 396                 goto errout;
 397         }
 398         ep = &obj->efile.ehdr;
 399
 400         if ((ep->e_type != ET_REL) || (ep->e_machine != 0)) {
 401                 pr_warning("%s is not an eBPF object file\n",
 402                         obj->path);
 403                 err = -LIBBPF_ERRNO__FORMAT;
 404                 goto errout;
 405         }
 406
 407         return 0;
 408 errout:
 409         bpf_object__elf_finish(obj);
 410         return err;
 411 }
 412
 413 static int
 414 bpf_object__check_endianness(struct bpf_object *obj)
 415 {
 416         static unsigned int const endian = 1;
 417
 418         switch (obj->efile.ehdr.e_ident[EI_DATA]) {
 419         case ELFDATA2LSB:
 420                 /* We are big endian, BPF obj is little endian. */
 421                 if (*(unsigned char const *)&endian != 1)
 422                         goto mismatch;
 423                 break;
 424
 425         case ELFDATA2MSB:
 426                 /* We are little endian, BPF obj is big endian. */
 427                 if (*(unsigned char const *)&endian != 0)
 428                         goto mismatch;
 429                 break;
 430         default:
 431                 return -LIBBPF_ERRNO__ENDIAN;
 432         }
 433
 434         return 0;
 435
 436 mismatch:
 437         pr_warning("Error: endianness mismatch.\n");
 438         return -LIBBPF_ERRNO__ENDIAN;
 439 }
 440
 441 static int
 442 bpf_object__init_license(struct bpf_object *obj,
 443                          void *data, size_t size)
 444 {
 445         memcpy(obj->license, data,
 446                min(size, sizeof(obj->license) - 1));
 447         pr_debug("license of %s is %s\n", obj->path, obj->license);
 448         return 0;
 449 }
 450
 451 static int
 452 bpf_object__init_kversion(struct bpf_object *obj,
 453                           void *data, size_t size)
 454 {
 455         u32 kver;
 456
 457         if (size != sizeof(kver)) {
 458                 pr_warning("invalid kver section in %s\n", obj->path);
 459                 return -LIBBPF_ERRNO__FORMAT;
 460         }
 461         memcpy(&kver, data, sizeof(kver));
 462         obj->kern_version = kver;
 463         pr_debug("kernel version of %s is %x\n", obj->path,
 464                  obj->kern_version);
 465         return 0;
 466 }
 467
 468 static int
 469 bpf_object__init_maps(struct bpf_object *obj, void *data,
 470                       size_t size)
 471 {
 472         if (size == 0) {
 473                 pr_debug("%s doesn't need map definition\n",
 474                          obj->path);
 475                 return 0;
 476         }
 477
 478         obj->maps_buf = malloc(size);
 479         if (!obj->maps_buf) {
 480                 pr_warning("malloc maps failed: %s\n", obj->path);
 481                 return -ENOMEM;
 482         }
 483
 484         obj->maps_buf_sz = size;
 485         memcpy(obj->maps_buf, data, size);
 486         pr_debug("maps in %s: %ld bytes\n", obj->path, (long)size);
 487         return 0;
 488 }
 489
 490 static bool section_have_execinstr(struct bpf_object *obj, int idx)
 491 {
 492         Elf_Scn *scn;
 493         GElf_Shdr sh;
 494
 495         scn = elf_getscn(obj->efile.elf, idx);
 496         if (!scn)
 497                 return false;
 498
 499         if (gelf_getshdr(scn, &sh) != &sh)
 500                 return false;
 501
 502         if (sh.sh_flags & SHF_EXECINSTR)
 503                 return true;
 504
 505         return false;
 506 }
 507
 508 static int bpf_object__elf_collect(struct bpf_object *obj)
 509 {
 510         Elf *elf = obj->efile.elf;
 511         GElf_Ehdr *ep = &obj->efile.ehdr;
 512         Elf_Scn *scn = NULL;
 513         int idx = 0, err = 0;
 514
 515         /* Elf is corrupted/truncated, avoid calling elf_strptr. */
 516         if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) {
 517                 pr_warning("failed to get e_shstrndx from %s\n",
 518                            obj->path);
 519                 return -LIBBPF_ERRNO__FORMAT;
 520         }
 521
 522         while ((scn = elf_nextscn(elf, scn)) != NULL) {
 523                 char *name;
 524                 GElf_Shdr sh;
 525                 Elf_Data *data;
 526
 527                 idx++;
 528                 if (gelf_getshdr(scn, &sh) != &sh) {
 529                         pr_warning("failed to get section header from %s\n",
 530                                    obj->path);
 531                         err = -LIBBPF_ERRNO__FORMAT;
 532                         goto out;
 533                 }
 534
 535                 name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
 536                 if (!name) {
 537                         pr_warning("failed to get section name from %s\n",
 538                                    obj->path);
 539                         err = -LIBBPF_ERRNO__FORMAT;
 540                         goto out;
 541                 }
 542
 543                 data = elf_getdata(scn, 0);
 544                 if (!data) {
 545                         pr_warning("failed to get section data from %s(%s)\n",
 546                                    name, obj->path);
 547                         err = -LIBBPF_ERRNO__FORMAT;
 548                         goto out;
 549                 }
 550                 pr_debug("section %s, size %ld, link %d, flags %lx, type=%d\n",
 551                          name, (unsigned long)data->d_size,
 552                          (int)sh.sh_link, (unsigned long)sh.sh_flags,
 553                          (int)sh.sh_type);
 554
 555                 if (strcmp(name, "license") == 0)
 556                         err = bpf_object__init_license(obj,
 557                                                        data->d_buf,
 558                                                        data->d_size);
 559                 else if (strcmp(name, "version") == 0)
 560                         err = bpf_object__init_kversion(obj,
 561                                                         data->d_buf,
 562                                                         data->d_size);
 563                 else if (strcmp(name, "maps") == 0)
 564                         err = bpf_object__init_maps(obj, data->d_buf,
 565                                                     data->d_size);
 566                 else if (sh.sh_type == SHT_SYMTAB) {
 567                         if (obj->efile.symbols) {
 568                                 pr_warning("bpf: multiple SYMTAB in %s\n",
 569                                            obj->path);
 570                                 err = -LIBBPF_ERRNO__FORMAT;
 571                         } else
 572                                 obj->efile.symbols = data;
 573                 } else if ((sh.sh_type == SHT_PROGBITS) &&
 574                            (sh.sh_flags & SHF_EXECINSTR) &&
 575                            (data->d_size > 0)) {
 576                         err = bpf_object__add_program(obj, data->d_buf,
 577                                                       data->d_size, name, idx);
 578                         if (err) {
 579                                 char errmsg[STRERR_BUFSIZE];
 580
 581                                 strerror_r(-err, errmsg, sizeof(errmsg));
 582                                 pr_warning("failed to alloc program %s (%s): %s",
 583                                            name, obj->path, errmsg);
 584                         }
 585                 } else if (sh.sh_type == SHT_REL) {
 586                         void *reloc = obj->efile.reloc;
 587                         int nr_reloc = obj->efile.nr_reloc + 1;
 588                         int sec = sh.sh_info; /* points to other section */
 589
 590                         /* Only do relo for section with exec instructions */
 591                         if (!section_have_execinstr(obj, sec)) {
 592                                 pr_debug("skip relo %s(%d) for section(%d)\n",
 593                                          name, idx, sec);
 594                                 continue;
 595                         }
 596
 597                         reloc = realloc(reloc,
 598                                         sizeof(*obj->efile.reloc) * nr_reloc);
 599                         if (!reloc) {
 600                                 pr_warning("realloc failed\n");
 601                                 err = -ENOMEM;
 602                         } else {
 603                                 int n = nr_reloc - 1;
 604
 605                                 obj->efile.reloc = reloc;
 606                                 obj->efile.nr_reloc = nr_reloc;
 607
 608                                 obj->efile.reloc[n].shdr = sh;
 609                                 obj->efile.reloc[n].data = data;
 610                         }
 611                 }
 612                 if (err)
 613                         goto out;
 614         }
 615 out:
 616         return err;
 617 }
 618
 619 static struct bpf_program *
 620 bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
 621 {
 622         struct bpf_program *prog;
 623         size_t i;
 624
 625         for (i = 0; i < obj->nr_programs; i++) {
 626                 prog = &obj->programs[i];
 627                 if (prog->idx == idx)
 628                         return prog;
 629         }
 630         return NULL;
 631 }
 632
 633 static int
 634 bpf_program__collect_reloc(struct bpf_program *prog,
 635                            size_t nr_maps, GElf_Shdr *shdr,
 636                            Elf_Data *data, Elf_Data *symbols)
 637 {
 638         int i, nrels;
 639
 640         pr_debug("collecting relocating info for: '%s'\n",
 641                  prog->section_name);
 642         nrels = shdr->sh_size / shdr->sh_entsize;
 643
 644         prog->reloc_desc = malloc(sizeof(*prog->reloc_desc) * nrels);
 645         if (!prog->reloc_desc) {
 646                 pr_warning("failed to alloc memory in relocation\n");
 647                 return -ENOMEM;
 648         }
 649         prog->nr_reloc = nrels;
 650
 651         for (i = 0; i < nrels; i++) {
 652                 GElf_Sym sym;
 653                 GElf_Rel rel;
 654                 unsigned int insn_idx;
 655                 struct bpf_insn *insns = prog->insns;
 656                 size_t map_idx;
 657
 658                 if (!gelf_getrel(data, i, &rel)) {
 659                         pr_warning("relocation: failed to get %d reloc\n", i);
 660                         return -LIBBPF_ERRNO__FORMAT;
 661                 }
 662
 663                 insn_idx = rel.r_offset / sizeof(struct bpf_insn);
 664                 pr_debug("relocation: insn_idx=%u\n", insn_idx);
 665
 666                 if (!gelf_getsym(symbols,
 667                                  GELF_R_SYM(rel.r_info),
 668                                  &sym)) {
 669                         pr_warning("relocation: symbol %"PRIx64" not found\n",
 670                                    GELF_R_SYM(rel.r_info));
 671                         return -LIBBPF_ERRNO__FORMAT;
 672                 }
 673
 674                 if (insns[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
 675                         pr_warning("bpf: relocation: invalid relo for insns[%d].code 0x%x\n",
 676                                    insn_idx, insns[insn_idx].code);
 677                         return -LIBBPF_ERRNO__RELOC;
 678                 }
 679
 680                 map_idx = sym.st_value / sizeof(struct bpf_map_def);
 681                 if (map_idx >= nr_maps) {
 682                         pr_warning("bpf relocation: map_idx %d large than %d\n",
 683                                    (int)map_idx, (int)nr_maps - 1);
 684                         return -LIBBPF_ERRNO__RELOC;
 685                 }
 686
 687                 prog->reloc_desc[i].insn_idx = insn_idx;
 688                 prog->reloc_desc[i].map_idx = map_idx;
 689         }
 690         return 0;
 691 }
 692
 693 static int
 694 bpf_object__create_maps(struct bpf_object *obj)
 695 {
 696         unsigned int i;
 697         size_t nr_maps;
 698         int *pfd;
 699
 700         nr_maps = obj->maps_buf_sz / sizeof(struct bpf_map_def);
 701         if (!obj->maps_buf || !nr_maps) {
 702                 pr_debug("don't need create maps for %s\n",
 703                          obj->path);
 704                 return 0;
 705         }
 706
 707         obj->map_fds = malloc(sizeof(int) * nr_maps);
 708         if (!obj->map_fds) {
 709                 pr_warning("realloc perf_bpf_map_fds failed\n");
 710                 return -ENOMEM;
 711         }
 712         obj->nr_map_fds = nr_maps;
 713
 714         /* fill all fd with -1 */
 715         memset(obj->map_fds, -1, sizeof(int) * nr_maps);
 716
 717         pfd = obj->map_fds;
 718         for (i = 0; i < nr_maps; i++) {
 719                 struct bpf_map_def def;
 720
 721                 def = *(struct bpf_map_def *)(obj->maps_buf +
 722                                 i * sizeof(struct bpf_map_def));
 723
 724                 *pfd = bpf_create_map(def.type,
 725                                       def.key_size,
 726                                       def.value_size,
 727                                       def.max_entries);
 728                 if (*pfd < 0) {
 729                         size_t j;
 730                         int err = *pfd;
 731
 732                         pr_warning("failed to create map: %s\n",
 733                                    strerror(errno));
 734                         for (j = 0; j < i; j++)
 735                                 zclose(obj->map_fds[j]);
 736                         obj->nr_map_fds = 0;
 737                         zfree(&obj->map_fds);
 738                         return err;
 739                 }
 740                 pr_debug("create map: fd=%d\n", *pfd);
 741                 pfd++;
 742         }
 743
 744         zfree(&obj->maps_buf);
 745         obj->maps_buf_sz = 0;
 746         return 0;
 747 }
 748
 749 static int
 750 bpf_program__relocate(struct bpf_program *prog, int *map_fds)
 751 {
 752         int i;
 753
 754         if (!prog || !prog->reloc_desc)
 755                 return 0;
 756
 757         for (i = 0; i < prog->nr_reloc; i++) {
 758                 int insn_idx, map_idx;
 759                 struct bpf_insn *insns = prog->insns;
 760
 761                 insn_idx = prog->reloc_desc[i].insn_idx;
 762                 map_idx = prog->reloc_desc[i].map_idx;
 763
 764                 if (insn_idx >= (int)prog->insns_cnt) {
 765                         pr_warning("relocation out of range: '%s'\n",
 766                                    prog->section_name);
 767                         return -LIBBPF_ERRNO__RELOC;
 768                 }
 769                 insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
 770                 insns[insn_idx].imm = map_fds[map_idx];
 771         }
 772
 773         zfree(&prog->reloc_desc);
 774         prog->nr_reloc = 0;
 775         return 0;
 776 }
 777
 778
 779 static int
 780 bpf_object__relocate(struct bpf_object *obj)
 781 {
 782         struct bpf_program *prog;
 783         size_t i;
 784         int err;
 785
 786         for (i = 0; i < obj->nr_programs; i++) {
 787                 prog = &obj->programs[i];
 788
 789                 err = bpf_program__relocate(prog, obj->map_fds);
 790                 if (err) {
 791                         pr_warning("failed to relocate '%s'\n",
 792                                    prog->section_name);
 793                         return err;
 794                 }
 795         }
 796         return 0;
 797 }
 798
 799 static int bpf_object__collect_reloc(struct bpf_object *obj)
 800 {
 801         int i, err;
 802
 803         if (!obj_elf_valid(obj)) {
 804                 pr_warning("Internal error: elf object is closed\n");
 805                 return -LIBBPF_ERRNO__INTERNAL;
 806         }
 807
 808         for (i = 0; i < obj->efile.nr_reloc; i++) {
 809                 GElf_Shdr *shdr = &obj->efile.reloc[i].shdr;
 810                 Elf_Data *data = obj->efile.reloc[i].data;
 811                 int idx = shdr->sh_info;
 812                 struct bpf_program *prog;
 813                 size_t nr_maps = obj->maps_buf_sz /
 814                                  sizeof(struct bpf_map_def);
 815
 816                 if (shdr->sh_type != SHT_REL) {
 817                         pr_warning("internal error at %d\n", __LINE__);
 818                         return -LIBBPF_ERRNO__INTERNAL;
 819                 }
 820
 821                 prog = bpf_object__find_prog_by_idx(obj, idx);
 822                 if (!prog) {
 823                         pr_warning("relocation failed: no %d section\n",
 824                                    idx);
 825                         return -LIBBPF_ERRNO__RELOC;
 826                 }
 827
 828                 err = bpf_program__collect_reloc(prog, nr_maps,
 829                                                  shdr, data,
 830                                                  obj->efile.symbols);
 831                 if (err)
 832                         return err;
 833         }
 834         return 0;
 835 }
 836
 837 static int
 838 load_program(struct bpf_insn *insns, int insns_cnt,
 839              char *license, u32 kern_version, int *pfd)
 840 {
 841         int ret;
 842         char *log_buf;
 843
 844         if (!insns || !insns_cnt)
 845                 return -EINVAL;
 846
 847         log_buf = malloc(BPF_LOG_BUF_SIZE);
 848         if (!log_buf)
 849                 pr_warning("Alloc log buffer for bpf loader error, continue without log\n");
 850
 851         ret = bpf_load_program(BPF_PROG_TYPE_KPROBE, insns,
 852                                insns_cnt, license, kern_version,
 853                                log_buf, BPF_LOG_BUF_SIZE);
 854
 855         if (ret >= 0) {
 856                 *pfd = ret;
 857                 ret = 0;
 858                 goto out;
 859         }
 860
 861         ret = -LIBBPF_ERRNO__LOAD;
 862         pr_warning("load bpf program failed: %s\n", strerror(errno));
 863
 864         if (log_buf && log_buf[0] != '\0') {
 865                 ret = -LIBBPF_ERRNO__VERIFY;
 866                 pr_warning("-- BEGIN DUMP LOG ---\n");
 867                 pr_warning("\n%s\n", log_buf);
 868                 pr_warning("-- END LOG --\n");
 869         } else {
 870                 if (insns_cnt >= BPF_MAXINSNS) {
 871                         pr_warning("Program too large (%d insns), at most %d insns\n",
 872                                    insns_cnt, BPF_MAXINSNS);
 873                         ret = -LIBBPF_ERRNO__PROG2BIG;
 874                 } else if (log_buf) {
 875                         pr_warning("log buffer is empty\n");
 876                         ret = -LIBBPF_ERRNO__KVER;
 877                 }
 878         }
 879
 880 out:
 881         free(log_buf);
 882         return ret;
 883 }
 884
 885 static int
 886 bpf_program__load(struct bpf_program *prog,
 887                   char *license, u32 kern_version)
 888 {
 889         int err, fd;
 890
 891         err = load_program(prog->insns, prog->insns_cnt,
 892                            license, kern_version, &fd);
 893         if (!err)
 894                 prog->fd = fd;
 895
 896         if (err)
 897                 pr_warning("failed to load program '%s'\n",
 898                            prog->section_name);
 899         zfree(&prog->insns);
 900         prog->insns_cnt = 0;
 901         return err;
 902 }
 903
 904 static int
 905 bpf_object__load_progs(struct bpf_object *obj)
 906 {
 907         size_t i;
 908         int err;
 909
 910         for (i = 0; i < obj->nr_programs; i++) {
 911                 err = bpf_program__load(&obj->programs[i],
 912                                         obj->license,
 913                                         obj->kern_version);
 914                 if (err)
 915                         return err;
 916         }
 917         return 0;
 918 }
 919
 920 static int bpf_object__validate(struct bpf_object *obj)
 921 {
 922         if (obj->kern_version == 0) {
 923                 pr_warning("%s doesn't provide kernel version\n",
 924                            obj->path);
 925                 return -LIBBPF_ERRNO__KVERSION;
 926         }
 927         return 0;
 928 }
 929
 930 static struct bpf_object *
 931 __bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz)
 932 {
 933         struct bpf_object *obj;
 934         int err;
 935
 936         if (elf_version(EV_CURRENT) == EV_NONE) {
 937                 pr_warning("failed to init libelf for %s\n", path);
 938                 return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
 939         }
 940
 941         obj = bpf_object__new(path, obj_buf, obj_buf_sz);
 942         if (IS_ERR(obj))
 943                 return obj;
 944
 945         CHECK_ERR(bpf_object__elf_init(obj), err, out);
 946         CHECK_ERR(bpf_object__check_endianness(obj), err, out);
 947         CHECK_ERR(bpf_object__elf_collect(obj), err, out);
 948         CHECK_ERR(bpf_object__collect_reloc(obj), err, out);
 949         CHECK_ERR(bpf_object__validate(obj), err, out);
 950
 951         bpf_object__elf_finish(obj);
 952         return obj;
 953 out:
 954         bpf_object__close(obj);
 955         return ERR_PTR(err);
 956 }
 957
 958 struct bpf_object *bpf_object__open(const char *path)
 959 {
 960         /* param validation */
 961         if (!path)
 962                 return NULL;
 963
 964         pr_debug("loading %s\n", path);
 965
 966         return __bpf_object__open(path, NULL, 0);
 967 }
 968
 969 struct bpf_object *bpf_object__open_buffer(void *obj_buf,
 970                                            size_t obj_buf_sz,
 971                                            const char *name)
 972 {
 973         char tmp_name[64];
 974
 975         /* param validation */
 976         if (!obj_buf || obj_buf_sz <= 0)
 977                 return NULL;
 978
 979         if (!name) {
 980                 snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
 981                          (unsigned long)obj_buf,
 982                          (unsigned long)obj_buf_sz);
 983                 tmp_name[sizeof(tmp_name) - 1] = '\0';
 984                 name = tmp_name;
 985         }
 986         pr_debug("loading object '%s' from buffer\n",
 987                  name);
 988
 989         return __bpf_object__open(name, obj_buf, obj_buf_sz);
 990 }
 991
 992 int bpf_object__unload(struct bpf_object *obj)
 993 {
 994         size_t i;
 995
 996         if (!obj)
 997                 return -EINVAL;
 998
 999         for (i = 0; i < obj->nr_map_fds; i++)
1000                 zclose(obj->map_fds[i]);
1001         zfree(&obj->map_fds);
1002         obj->nr_map_fds = 0;
1003
1004         for (i = 0; i < obj->nr_programs; i++)
1005                 bpf_program__unload(&obj->programs[i]);
1006
1007         return 0;
1008 }
1009
1010 int bpf_object__load(struct bpf_object *obj)
1011 {
1012         int err;
1013
1014         if (!obj)
1015                 return -EINVAL;
1016
1017         if (obj->loaded) {
1018                 pr_warning("object should not be loaded twice\n");
1019                 return -EINVAL;
1020         }
1021
1022         obj->loaded = true;
1023
1024         CHECK_ERR(bpf_object__create_maps(obj), err, out);
1025         CHECK_ERR(bpf_object__relocate(obj), err, out);
1026         CHECK_ERR(bpf_object__load_progs(obj), err, out);
1027
1028         return 0;
1029 out:
1030         bpf_object__unload(obj);
1031         pr_warning("failed to load object '%s'\n", obj->path);
1032         return err;
1033 }
1034
1035 void bpf_object__close(struct bpf_object *obj)
1036 {
1037         size_t i;
1038
1039         if (!obj)
1040                 return;
1041
1042         bpf_object__elf_finish(obj);
1043         bpf_object__unload(obj);
1044
1045         zfree(&obj->maps_buf);
1046
1047         if (obj->programs && obj->nr_programs) {
1048                 for (i = 0; i < obj->nr_programs; i++)
1049                         bpf_program__exit(&obj->programs[i]);
1050         }
1051         zfree(&obj->programs);
1052
1053         list_del(&obj->list);
1054         free(obj);
1055 }
1056
1057 struct bpf_object *
1058 bpf_object__next(struct bpf_object *prev)
1059 {
1060         struct bpf_object *next;
1061
1062         if (!prev)
1063                 next = list_first_entry(&bpf_objects_list,
1064                                         struct bpf_object,
1065                                         list);
1066         else
1067                 next = list_next_entry(prev, list);
1068
1069         /* Empty list is noticed here so don't need checking on entry. */
1070         if (&next->list == &bpf_objects_list)
1071                 return NULL;
1072
1073         return next;
1074 }
1075
1076 const char *
1077 bpf_object__get_name(struct bpf_object *obj)
1078 {
1079         if (!obj)
1080                 return ERR_PTR(-EINVAL);
1081         return obj->path;
1082 }
1083
1084 unsigned int
1085 bpf_object__get_kversion(struct bpf_object *obj)
1086 {
1087         if (!obj)
1088                 return 0;
1089         return obj->kern_version;
1090 }
1091
1092 struct bpf_program *
1093 bpf_program__next(struct bpf_program *prev, struct bpf_object *obj)
1094 {
1095         size_t idx;
1096
1097         if (!obj->programs)
1098                 return NULL;
1099         /* First handler */
1100         if (prev == NULL)
1101                 return &obj->programs[0];
1102
1103         if (prev->obj != obj) {
1104                 pr_warning("error: program handler doesn't match object\n");
1105                 return NULL;
1106         }
1107
1108         idx = (prev - obj->programs) + 1;
1109         if (idx >= obj->nr_programs)
1110                 return NULL;
1111         return &obj->programs[idx];
1112 }
1113
1114 int bpf_program__set_private(struct bpf_program *prog,
1115                              void *priv,
1116                              bpf_program_clear_priv_t clear_priv)
1117 {
1118         if (prog->priv && prog->clear_priv)
1119                 prog->clear_priv(prog, prog->priv);
1120
1121         prog->priv = priv;
1122         prog->clear_priv = clear_priv;
1123         return 0;
1124 }
1125
1126 int bpf_program__get_private(struct bpf_program *prog, void **ppriv)
1127 {
1128         *ppriv = prog->priv;
1129         return 0;
1130 }
1131
1132 const char *bpf_program__title(struct bpf_program *prog, bool needs_copy)
1133 {
1134         const char *title;
1135
1136         title = prog->section_name;
1137         if (needs_copy) {
1138                 title = strdup(title);
1139                 if (!title) {
1140                         pr_warning("failed to strdup program title\n");
1141                         return ERR_PTR(-ENOMEM);
1142                 }
1143         }
1144
1145         return title;
1146 }
1147
1148 int bpf_program__fd(struct bpf_program *prog)
1149 {
1150         return prog->fd;
1151 }