samples/bpf/bpf_load.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <stdio.h>
   3 #include <sys/types.h>
   4 #include <sys/stat.h>
   5 #include <fcntl.h>
   6 #include <libelf.h>
   7 #include <gelf.h>
   8 #include <errno.h>
   9 #include <unistd.h>
  10 #include <string.h>
  11 #include <stdbool.h>
  12 #include <stdlib.h>
  13 #include <linux/bpf.h>
  14 #include <linux/filter.h>
  15 #include <linux/perf_event.h>
  16 #include <linux/netlink.h>
  17 #include <linux/rtnetlink.h>
  18 #include <linux/types.h>
  19 #include <sys/types.h>
  20 #include <sys/socket.h>
  21 #include <sys/syscall.h>
  22 #include <sys/ioctl.h>
  23 #include <sys/mman.h>
  24 #include <poll.h>
  25 #include <ctype.h>
  26 #include <assert.h>
  27 #include <bpf/bpf.h>
  28 #include "bpf_load.h"
  29 #include "perf-sys.h"
  30
  31 #define DEBUGFS "/sys/kernel/debug/tracing/"
  32
  33 static char license[128];
  34 static int kern_version;
  35 static bool processed_sec[128];
  36 char bpf_log_buf[BPF_LOG_BUF_SIZE];
  37 int map_fd[MAX_MAPS];
  38 int prog_fd[MAX_PROGS];
  39 int event_fd[MAX_PROGS];
  40 int prog_cnt;
  41 int prog_array_fd = -1;
  42
  43 struct bpf_map_data map_data[MAX_MAPS];
  44 int map_data_count = 0;
  45
  46 static int populate_prog_array(const char *event, int prog_fd)
  47 {
  48         int ind = atoi(event), err;
  49
  50         err = bpf_map_update_elem(prog_array_fd, &ind, &prog_fd, BPF_ANY);
  51         if (err < 0) {
  52                 printf("failed to store prog_fd in prog_array\n");
  53                 return -1;
  54         }
  55         return 0;
  56 }
  57
  58 static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
  59 {
  60         bool is_socket = strncmp(event, "socket", 6) == 0;
  61         bool is_kprobe = strncmp(event, "kprobe/", 7) == 0;
  62         bool is_kretprobe = strncmp(event, "kretprobe/", 10) == 0;
  63         bool is_tracepoint = strncmp(event, "tracepoint/", 11) == 0;
  64         bool is_raw_tracepoint = strncmp(event, "raw_tracepoint/", 15) == 0;
  65         bool is_xdp = strncmp(event, "xdp", 3) == 0;
  66         bool is_perf_event = strncmp(event, "perf_event", 10) == 0;
  67         bool is_cgroup_skb = strncmp(event, "cgroup/skb", 10) == 0;
  68         bool is_cgroup_sk = strncmp(event, "cgroup/sock", 11) == 0;
  69         bool is_sockops = strncmp(event, "sockops", 7) == 0;
  70         bool is_sk_skb = strncmp(event, "sk_skb", 6) == 0;
  71         bool is_sk_msg = strncmp(event, "sk_msg", 6) == 0;
  72         size_t insns_cnt = size / sizeof(struct bpf_insn);
  73         enum bpf_prog_type prog_type;
  74         char buf[256];
  75         int fd, efd, err, id;
  76         struct perf_event_attr attr = {};
  77
  78         attr.type = PERF_TYPE_TRACEPOINT;
  79         attr.sample_type = PERF_SAMPLE_RAW;
  80         attr.sample_period = 1;
  81         attr.wakeup_events = 1;
  82
  83         if (is_socket) {
  84                 prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
  85         } else if (is_kprobe || is_kretprobe) {
  86                 prog_type = BPF_PROG_TYPE_KPROBE;
  87         } else if (is_tracepoint) {
  88                 prog_type = BPF_PROG_TYPE_TRACEPOINT;
  89         } else if (is_raw_tracepoint) {
  90                 prog_type = BPF_PROG_TYPE_RAW_TRACEPOINT;
  91         } else if (is_xdp) {
  92                 prog_type = BPF_PROG_TYPE_XDP;
  93         } else if (is_perf_event) {
  94                 prog_type = BPF_PROG_TYPE_PERF_EVENT;
  95         } else if (is_cgroup_skb) {
  96                 prog_type = BPF_PROG_TYPE_CGROUP_SKB;
  97         } else if (is_cgroup_sk) {
  98                 prog_type = BPF_PROG_TYPE_CGROUP_SOCK;
  99         } else if (is_sockops) {
 100                 prog_type = BPF_PROG_TYPE_SOCK_OPS;
 101         } else if (is_sk_skb) {
 102                 prog_type = BPF_PROG_TYPE_SK_SKB;
 103         } else if (is_sk_msg) {
 104                 prog_type = BPF_PROG_TYPE_SK_MSG;
 105         } else {
 106                 printf("Unknown event '%s'\n", event);
 107                 return -1;
 108         }
 109
 110         fd = bpf_load_program(prog_type, prog, insns_cnt, license, kern_version,
 111                               bpf_log_buf, BPF_LOG_BUF_SIZE);
 112         if (fd < 0) {
 113                 printf("bpf_load_program() err=%d\n%s", errno, bpf_log_buf);
 114                 return -1;
 115         }
 116
 117         prog_fd[prog_cnt++] = fd;
 118
 119         if (is_xdp || is_perf_event || is_cgroup_skb || is_cgroup_sk)
 120                 return 0;
 121
 122         if (is_socket || is_sockops || is_sk_skb || is_sk_msg) {
 123                 if (is_socket)
 124                         event += 6;
 125                 else
 126                         event += 7;
 127                 if (*event != '/')
 128                         return 0;
 129                 event++;
 130                 if (!isdigit(*event)) {
 131                         printf("invalid prog number\n");
 132                         return -1;
 133                 }
 134                 return populate_prog_array(event, fd);
 135         }
 136
 137         if (is_raw_tracepoint) {
 138                 efd = bpf_raw_tracepoint_open(event + 15, fd);
 139                 if (efd < 0) {
 140                         printf("tracepoint %s %s\n", event + 15, strerror(errno));
 141                         return -1;
 142                 }
 143                 event_fd[prog_cnt - 1] = efd;
 144                 return 0;
 145         }
 146
 147         if (is_kprobe || is_kretprobe) {
 148                 bool need_normal_check = true;
 149                 const char *event_prefix = "";
 150
 151                 if (is_kprobe)
 152                         event += 7;
 153                 else
 154                         event += 10;
 155
 156                 if (*event == 0) {
 157                         printf("event name cannot be empty\n");
 158                         return -1;
 159                 }
 160
 161                 if (isdigit(*event))
 162                         return populate_prog_array(event, fd);
 163
 164 #ifdef __x86_64__
 165                 if (strncmp(event, "sys_", 4) == 0) {
 166                         snprintf(buf, sizeof(buf),
 167                                  "echo '%c:__x64_%s __x64_%s' >> /sys/kernel/debug/tracing/kprobe_events",
 168                                  is_kprobe ? 'p' : 'r', event, event);
 169                         err = system(buf);
 170                         if (err >= 0) {
 171                                 need_normal_check = false;
 172                                 event_prefix = "__x64_";
 173                         }
 174                 }
 175 #endif
 176                 if (need_normal_check) {
 177                         snprintf(buf, sizeof(buf),
 178                                  "echo '%c:%s %s' >> /sys/kernel/debug/tracing/kprobe_events",
 179                                  is_kprobe ? 'p' : 'r', event, event);
 180                         err = system(buf);
 181                         if (err < 0) {
 182                                 printf("failed to create kprobe '%s' error '%s'\n",
 183                                        event, strerror(errno));
 184                                 return -1;
 185                         }
 186                 }
 187
 188                 strcpy(buf, DEBUGFS);
 189                 strcat(buf, "events/kprobes/");
 190                 strcat(buf, event_prefix);
 191                 strcat(buf, event);
 192                 strcat(buf, "/id");
 193         } else if (is_tracepoint) {
 194                 event += 11;
 195
 196                 if (*event == 0) {
 197                         printf("event name cannot be empty\n");
 198                         return -1;
 199                 }
 200                 strcpy(buf, DEBUGFS);
 201                 strcat(buf, "events/");
 202                 strcat(buf, event);
 203                 strcat(buf, "/id");
 204         }
 205
 206         efd = open(buf, O_RDONLY, 0);
 207         if (efd < 0) {
 208                 printf("failed to open event %s\n", event);
 209                 return -1;
 210         }
 211
 212         err = read(efd, buf, sizeof(buf));
 213         if (err < 0 || err >= sizeof(buf)) {
 214                 printf("read from '%s' failed '%s'\n", event, strerror(errno));
 215                 return -1;
 216         }
 217
 218         close(efd);
 219
 220         buf[err] = 0;
 221         id = atoi(buf);
 222         attr.config = id;
 223
 224         efd = sys_perf_event_open(&attr, -1/*pid*/, 0/*cpu*/, -1/*group_fd*/, 0);
 225         if (efd < 0) {
 226                 printf("event %d fd %d err %s\n", id, efd, strerror(errno));
 227                 return -1;
 228         }
 229         event_fd[prog_cnt - 1] = efd;
 230         err = ioctl(efd, PERF_EVENT_IOC_ENABLE, 0);
 231         if (err < 0) {
 232                 printf("ioctl PERF_EVENT_IOC_ENABLE failed err %s\n",
 233                        strerror(errno));
 234                 return -1;
 235         }
 236         err = ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd);
 237         if (err < 0) {
 238                 printf("ioctl PERF_EVENT_IOC_SET_BPF failed err %s\n",
 239                        strerror(errno));
 240                 return -1;
 241         }
 242
 243         return 0;
 244 }
 245
 246 static int load_maps(struct bpf_map_data *maps, int nr_maps,
 247                      fixup_map_cb fixup_map)
 248 {
 249         int i, numa_node;
 250
 251         for (i = 0; i < nr_maps; i++) {
 252                 if (fixup_map) {
 253                         fixup_map(&maps[i], i);
 254                         /* Allow userspace to assign map FD prior to creation */
 255                         if (maps[i].fd != -1) {
 256                                 map_fd[i] = maps[i].fd;
 257                                 continue;
 258                         }
 259                 }
 260
 261                 numa_node = maps[i].def.map_flags & BPF_F_NUMA_NODE ?
 262                         maps[i].def.numa_node : -1;
 263
 264                 if (maps[i].def.type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
 265                     maps[i].def.type == BPF_MAP_TYPE_HASH_OF_MAPS) {
 266                         int inner_map_fd = map_fd[maps[i].def.inner_map_idx];
 267
 268                         map_fd[i] = bpf_create_map_in_map_node(maps[i].def.type,
 269                                                         maps[i].name,
 270                                                         maps[i].def.key_size,
 271                                                         inner_map_fd,
 272                                                         maps[i].def.max_entries,
 273                                                         maps[i].def.map_flags,
 274                                                         numa_node);
 275                 } else {
 276                         map_fd[i] = bpf_create_map_node(maps[i].def.type,
 277                                                         maps[i].name,
 278                                                         maps[i].def.key_size,
 279                                                         maps[i].def.value_size,
 280                                                         maps[i].def.max_entries,
 281                                                         maps[i].def.map_flags,
 282                                                         numa_node);
 283                 }
 284                 if (map_fd[i] < 0) {
 285                         printf("failed to create a map: %d %s\n",
 286                                errno, strerror(errno));
 287                         return 1;
 288                 }
 289                 maps[i].fd = map_fd[i];
 290
 291                 if (maps[i].def.type == BPF_MAP_TYPE_PROG_ARRAY)
 292                         prog_array_fd = map_fd[i];
 293         }
 294         return 0;
 295 }
 296
 297 static int get_sec(Elf *elf, int i, GElf_Ehdr *ehdr, char **shname,
 298                    GElf_Shdr *shdr, Elf_Data **data)
 299 {
 300         Elf_Scn *scn;
 301
 302         scn = elf_getscn(elf, i);
 303         if (!scn)
 304                 return 1;
 305
 306         if (gelf_getshdr(scn, shdr) != shdr)
 307                 return 2;
 308
 309         *shname = elf_strptr(elf, ehdr->e_shstrndx, shdr->sh_name);
 310         if (!*shname || !shdr->sh_size)
 311                 return 3;
 312
 313         *data = elf_getdata(scn, 0);
 314         if (!*data || elf_getdata(scn, *data) != NULL)
 315                 return 4;
 316
 317         return 0;
 318 }
 319
 320 static int parse_relo_and_apply(Elf_Data *data, Elf_Data *symbols,
 321                                 GElf_Shdr *shdr, struct bpf_insn *insn,
 322                                 struct bpf_map_data *maps, int nr_maps)
 323 {
 324         int i, nrels;
 325
 326         nrels = shdr->sh_size / shdr->sh_entsize;
 327
 328         for (i = 0; i < nrels; i++) {
 329                 GElf_Sym sym;
 330                 GElf_Rel rel;
 331                 unsigned int insn_idx;
 332                 bool match = false;
 333                 int j, map_idx;
 334
 335                 gelf_getrel(data, i, &rel);
 336
 337                 insn_idx = rel.r_offset / sizeof(struct bpf_insn);
 338
 339                 gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym);
 340
 341                 if (insn[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
 342                         printf("invalid relo for insn[%d].code 0x%x\n",
 343                                insn_idx, insn[insn_idx].code);
 344                         return 1;
 345                 }
 346                 insn[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
 347
 348                 /* Match FD relocation against recorded map_data[] offset */
 349                 for (map_idx = 0; map_idx < nr_maps; map_idx++) {
 350                         if (maps[map_idx].elf_offset == sym.st_value) {
 351                                 match = true;
 352                                 break;
 353                         }
 354                 }
 355                 if (match) {
 356                         insn[insn_idx].imm = maps[map_idx].fd;
 357                 } else {
 358                         printf("invalid relo for insn[%d] no map_data match\n",
 359                                insn_idx);
 360                         return 1;
 361                 }
 362         }
 363
 364         return 0;
 365 }
 366
 367 static int cmp_symbols(const void *l, const void *r)
 368 {
 369         const GElf_Sym *lsym = (const GElf_Sym *)l;
 370         const GElf_Sym *rsym = (const GElf_Sym *)r;
 371
 372         if (lsym->st_value < rsym->st_value)
 373                 return -1;
 374         else if (lsym->st_value > rsym->st_value)
 375                 return 1;
 376         else
 377                 return 0;
 378 }
 379
 380 static int load_elf_maps_section(struct bpf_map_data *maps, int maps_shndx,
 381                                  Elf *elf, Elf_Data *symbols, int strtabidx)
 382 {
 383         int map_sz_elf, map_sz_copy;
 384         bool validate_zero = false;
 385         Elf_Data *data_maps;
 386         int i, nr_maps;
 387         GElf_Sym *sym;
 388         Elf_Scn *scn;
 389         int copy_sz;
 390
 391         if (maps_shndx < 0)
 392                 return -EINVAL;
 393         if (!symbols)
 394                 return -EINVAL;
 395
 396         /* Get data for maps section via elf index */
 397         scn = elf_getscn(elf, maps_shndx);
 398         if (scn)
 399                 data_maps = elf_getdata(scn, NULL);
 400         if (!scn || !data_maps) {
 401                 printf("Failed to get Elf_Data from maps section %d\n",
 402                        maps_shndx);
 403                 return -EINVAL;
 404         }
 405
 406         /* For each map get corrosponding symbol table entry */
 407         sym = calloc(MAX_MAPS+1, sizeof(GElf_Sym));
 408         for (i = 0, nr_maps = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) {
 409                 assert(nr_maps < MAX_MAPS+1);
 410                 if (!gelf_getsym(symbols, i, &sym[nr_maps]))
 411                         continue;
 412                 if (sym[nr_maps].st_shndx != maps_shndx)
 413                         continue;
 414                 /* Only increment iif maps section */
 415                 nr_maps++;
 416         }
 417
 418         /* Align to map_fd[] order, via sort on offset in sym.st_value */
 419         qsort(sym, nr_maps, sizeof(GElf_Sym), cmp_symbols);
 420
 421         /* Keeping compatible with ELF maps section changes
 422          * ------------------------------------------------
 423          * The program size of struct bpf_load_map_def is known by loader
 424          * code, but struct stored in ELF file can be different.
 425          *
 426          * Unfortunately sym[i].st_size is zero.  To calculate the
 427          * struct size stored in the ELF file, assume all struct have
 428          * the same size, and simply divide with number of map
 429          * symbols.
 430          */
 431         map_sz_elf = data_maps->d_size / nr_maps;
 432         map_sz_copy = sizeof(struct bpf_load_map_def);
 433         if (map_sz_elf < map_sz_copy) {
 434                 /*
 435                  * Backward compat, loading older ELF file with
 436                  * smaller struct, keeping remaining bytes zero.
 437                  */
 438                 map_sz_copy = map_sz_elf;
 439         } else if (map_sz_elf > map_sz_copy) {
 440                 /*
 441                  * Forward compat, loading newer ELF file with larger
 442                  * struct with unknown features. Assume zero means
 443                  * feature not used.  Thus, validate rest of struct
 444                  * data is zero.
 445                  */
 446                 validate_zero = true;
 447         }
 448
 449         /* Memcpy relevant part of ELF maps data to loader maps */
 450         for (i = 0; i < nr_maps; i++) {
 451                 struct bpf_load_map_def *def;
 452                 unsigned char *addr, *end;
 453                 const char *map_name;
 454                 size_t offset;
 455
 456                 map_name = elf_strptr(elf, strtabidx, sym[i].st_name);
 457                 maps[i].name = strdup(map_name);
 458                 if (!maps[i].name) {
 459                         printf("strdup(%s): %s(%d)\n", map_name,
 460                                strerror(errno), errno);
 461                         free(sym);
 462                         return -errno;
 463                 }
 464
 465                 /* Symbol value is offset into ELF maps section data area */
 466                 offset = sym[i].st_value;
 467                 def = (struct bpf_load_map_def *)(data_maps->d_buf + offset);
 468                 maps[i].elf_offset = offset;
 469                 memset(&maps[i].def, 0, sizeof(struct bpf_load_map_def));
 470                 memcpy(&maps[i].def, def, map_sz_copy);
 471
 472                 /* Verify no newer features were requested */
 473                 if (validate_zero) {
 474                         addr = (unsigned char*) def + map_sz_copy;
 475                         end  = (unsigned char*) def + map_sz_elf;
 476                         for (; addr < end; addr++) {
 477                                 if (*addr != 0) {
 478                                         free(sym);
 479                                         return -EFBIG;
 480                                 }
 481                         }
 482                 }
 483         }
 484
 485         free(sym);
 486         return nr_maps;
 487 }
 488
 489 static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
 490 {
 491         int fd, i, ret, maps_shndx = -1, strtabidx = -1;
 492         Elf *elf;
 493         GElf_Ehdr ehdr;
 494         GElf_Shdr shdr, shdr_prog;
 495         Elf_Data *data, *data_prog, *data_maps = NULL, *symbols = NULL;
 496         char *shname, *shname_prog;
 497         int nr_maps = 0;
 498
 499         /* reset global variables */
 500         kern_version = 0;
 501         memset(license, 0, sizeof(license));
 502         memset(processed_sec, 0, sizeof(processed_sec));
 503
 504         if (elf_version(EV_CURRENT) == EV_NONE)
 505                 return 1;
 506
 507         fd = open(path, O_RDONLY, 0);
 508         if (fd < 0)
 509                 return 1;
 510
 511         elf = elf_begin(fd, ELF_C_READ, NULL);
 512
 513         if (!elf)
 514                 return 1;
 515
 516         if (gelf_getehdr(elf, &ehdr) != &ehdr)
 517                 return 1;
 518
 519         /* clear all kprobes */
 520         i = system("echo \"\" > /sys/kernel/debug/tracing/kprobe_events");
 521
 522         /* scan over all elf sections to get license and map info */
 523         for (i = 1; i < ehdr.e_shnum; i++) {
 524
 525                 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
 526                         continue;
 527
 528                 if (0) /* helpful for llvm debugging */
 529                         printf("section %d:%s data %p size %zd link %d flags %d\n",
 530                                i, shname, data->d_buf, data->d_size,
 531                                shdr.sh_link, (int) shdr.sh_flags);
 532
 533                 if (strcmp(shname, "license") == 0) {
 534                         processed_sec[i] = true;
 535                         memcpy(license, data->d_buf, data->d_size);
 536                 } else if (strcmp(shname, "version") == 0) {
 537                         processed_sec[i] = true;
 538                         if (data->d_size != sizeof(int)) {
 539                                 printf("invalid size of version section %zd\n",
 540                                        data->d_size);
 541                                 return 1;
 542                         }
 543                         memcpy(&kern_version, data->d_buf, sizeof(int));
 544                 } else if (strcmp(shname, "maps") == 0) {
 545                         int j;
 546
 547                         maps_shndx = i;
 548                         data_maps = data;
 549                         for (j = 0; j < MAX_MAPS; j++)
 550                                 map_data[j].fd = -1;
 551                 } else if (shdr.sh_type == SHT_SYMTAB) {
 552                         strtabidx = shdr.sh_link;
 553                         symbols = data;
 554                 }
 555         }
 556
 557         ret = 1;
 558
 559         if (!symbols) {
 560                 printf("missing SHT_SYMTAB section\n");
 561                 goto done;
 562         }
 563
 564         if (data_maps) {
 565                 nr_maps = load_elf_maps_section(map_data, maps_shndx,
 566                                                 elf, symbols, strtabidx);
 567                 if (nr_maps < 0) {
 568                         printf("Error: Failed loading ELF maps (errno:%d):%s\n",
 569                                nr_maps, strerror(-nr_maps));
 570                         goto done;
 571                 }
 572                 if (load_maps(map_data, nr_maps, fixup_map))
 573                         goto done;
 574                 map_data_count = nr_maps;
 575
 576                 processed_sec[maps_shndx] = true;
 577         }
 578
 579         /* process all relo sections, and rewrite bpf insns for maps */
 580         for (i = 1; i < ehdr.e_shnum; i++) {
 581                 if (processed_sec[i])
 582                         continue;
 583
 584                 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
 585                         continue;
 586
 587                 if (shdr.sh_type == SHT_REL) {
 588                         struct bpf_insn *insns;
 589
 590                         /* locate prog sec that need map fixup (relocations) */
 591                         if (get_sec(elf, shdr.sh_info, &ehdr, &shname_prog,
 592                                     &shdr_prog, &data_prog))
 593                                 continue;
 594
 595                         if (shdr_prog.sh_type != SHT_PROGBITS ||
 596                             !(shdr_prog.sh_flags & SHF_EXECINSTR))
 597                                 continue;
 598
 599                         insns = (struct bpf_insn *) data_prog->d_buf;
 600                         processed_sec[i] = true; /* relo section */
 601
 602                         if (parse_relo_and_apply(data, symbols, &shdr, insns,
 603                                                  map_data, nr_maps))
 604                                 continue;
 605                 }
 606         }
 607
 608         /* load programs */
 609         for (i = 1; i < ehdr.e_shnum; i++) {
 610
 611                 if (processed_sec[i])
 612                         continue;
 613
 614                 if (get_sec(elf, i, &ehdr, &shname, &shdr, &data))
 615                         continue;
 616
 617                 if (memcmp(shname, "kprobe/", 7) == 0 ||
 618                     memcmp(shname, "kretprobe/", 10) == 0 ||
 619                     memcmp(shname, "tracepoint/", 11) == 0 ||
 620                     memcmp(shname, "raw_tracepoint/", 15) == 0 ||
 621                     memcmp(shname, "xdp", 3) == 0 ||
 622                     memcmp(shname, "perf_event", 10) == 0 ||
 623                     memcmp(shname, "socket", 6) == 0 ||
 624                     memcmp(shname, "cgroup/", 7) == 0 ||
 625                     memcmp(shname, "sockops", 7) == 0 ||
 626                     memcmp(shname, "sk_skb", 6) == 0 ||
 627                     memcmp(shname, "sk_msg", 6) == 0) {
 628                         ret = load_and_attach(shname, data->d_buf,
 629                                               data->d_size);
 630                         if (ret != 0)
 631                                 goto done;
 632                 }
 633         }
 634
 635 done:
 636         close(fd);
 637         return ret;
 638 }
 639
 640 int load_bpf_file(char *path)
 641 {
 642         return do_load_bpf_file(path, NULL);
 643 }
 644
 645 int load_bpf_file_fixup_map(const char *path, fixup_map_cb fixup_map)
 646 {
 647         return do_load_bpf_file(path, fixup_map);
 648 }
 649
 650 void read_trace_pipe(void)
 651 {
 652         int trace_fd;
 653
 654         trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
 655         if (trace_fd < 0)
 656                 return;
 657
 658         while (1) {
 659                 static char buf[4096];
 660                 ssize_t sz;
 661
 662                 sz = read(trace_fd, buf, sizeof(buf));
 663                 if (sz > 0) {
 664                         buf[sz] = 0;
 665                         puts(buf);
 666                 }
 667         }
 668 }