1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) 2 /* Copyright (C) 2019 Facebook */ 3 4 #ifndef _GNU_SOURCE 5 #define _GNU_SOURCE 6 #endif 7 #include <ctype.h> 8 #include <errno.h> 9 #include <fcntl.h> 10 #include <linux/err.h> 11 #include <stdbool.h> 12 #include <stdio.h> 13 #include <string.h> 14 #include <unistd.h> 15 #include <bpf/bpf.h> 16 #include <bpf/libbpf.h> 17 #include <sys/types.h> 18 #include <sys/stat.h> 19 #include <sys/mman.h> 20 #include <bpf/btf.h> 21 22 #include "json_writer.h" 23 #include "main.h" 24 25 #define MAX_OBJ_NAME_LEN 64 26 27 static void sanitize_identifier(char *name) 28 { 29 int i; 30 31 for (i = 0; name[i]; i++) 32 if (!isalnum(name[i]) && name[i] != '_') 33 name[i] = '_'; 34 } 35 36 static bool str_has_suffix(const char *str, const char *suffix) 37 { 38 size_t i, n1 = strlen(str), n2 = strlen(suffix); 39 40 if (n1 < n2) 41 return false; 42 43 for (i = 0; i < n2; i++) { 44 if (str[n1 - i - 1] != suffix[n2 - i - 1]) 45 return false; 46 } 47 48 return true; 49 } 50 51 static void get_obj_name(char *name, const char *file) 52 { 53 /* Using basename() GNU version which doesn't modify arg. */ 54 strncpy(name, basename(file), MAX_OBJ_NAME_LEN - 1); 55 name[MAX_OBJ_NAME_LEN - 1] = '\0'; 56 if (str_has_suffix(name, ".o")) 57 name[strlen(name) - 2] = '\0'; 58 sanitize_identifier(name); 59 } 60 61 static void get_header_guard(char *guard, const char *obj_name) 62 { 63 int i; 64 65 sprintf(guard, "__%s_SKEL_H__", obj_name); 66 for (i = 0; guard[i]; i++) 67 guard[i] = toupper(guard[i]); 68 } 69 70 static const char *get_map_ident(const struct bpf_map *map) 71 { 72 const char *name = bpf_map__name(map); 73 74 if (!bpf_map__is_internal(map)) 75 return name; 76 77 if (str_has_suffix(name, ".data")) 78 return "data"; 79 else if (str_has_suffix(name, ".rodata")) 80 return "rodata"; 81 else if (str_has_suffix(name, ".bss")) 82 return "bss"; 83 else if (str_has_suffix(name, ".kconfig")) 84 return "kconfig"; 85 else 86 return NULL; 87 } 88 89 static void codegen_btf_dump_printf(void *ctx, const char *fmt, va_list args) 90 { 91 vprintf(fmt, args); 92 } 93 94 static int codegen_datasec_def(struct bpf_object *obj, 95 struct btf *btf, 96 struct btf_dump *d, 97 const struct btf_type *sec, 98 const char *obj_name) 99 { 100 const char *sec_name = btf__name_by_offset(btf, sec->name_off); 101 const struct btf_var_secinfo *sec_var = btf_var_secinfos(sec); 102 int i, err, off = 0, pad_cnt = 0, vlen = btf_vlen(sec); 103 const char *sec_ident; 104 char var_ident[256]; 105 bool strip_mods = false; 106 107 if (strcmp(sec_name, ".data") == 0) { 108 sec_ident = "data"; 109 } else if (strcmp(sec_name, ".bss") == 0) { 110 sec_ident = "bss"; 111 } else if (strcmp(sec_name, ".rodata") == 0) { 112 sec_ident = "rodata"; 113 strip_mods = true; 114 } else if (strcmp(sec_name, ".kconfig") == 0) { 115 sec_ident = "kconfig"; 116 } else { 117 return 0; 118 } 119 120 printf(" struct %s__%s {\n", obj_name, sec_ident); 121 for (i = 0; i < vlen; i++, sec_var++) { 122 const struct btf_type *var = btf__type_by_id(btf, sec_var->type); 123 const char *var_name = btf__name_by_offset(btf, var->name_off); 124 DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts, 125 .field_name = var_ident, 126 .indent_level = 2, 127 .strip_mods = strip_mods, 128 ); 129 int need_off = sec_var->offset, align_off, align; 130 __u32 var_type_id = var->type; 131 132 if (off > need_off) { 133 p_err("Something is wrong for %s's variable #%d: need offset %d, already at %d.\n", 134 sec_name, i, need_off, off); 135 return -EINVAL; 136 } 137 138 align = btf__align_of(btf, var->type); 139 if (align <= 0) { 140 p_err("Failed to determine alignment of variable '%s': %d", 141 var_name, align); 142 return -EINVAL; 143 } 144 /* Assume 32-bit architectures when generating data section 145 * struct memory layout. Given bpftool can't know which target 146 * host architecture it's emitting skeleton for, we need to be 147 * conservative and assume 32-bit one to ensure enough padding 148 * bytes are generated for pointer and long types. This will 149 * still work correctly for 64-bit architectures, because in 150 * the worst case we'll generate unnecessary padding field, 151 * which on 64-bit architectures is not strictly necessary and 152 * would be handled by natural 8-byte alignment. But it still 153 * will be a correct memory layout, based on recorded offsets 154 * in BTF. 155 */ 156 if (align > 4) 157 align = 4; 158 159 align_off = (off + align - 1) / align * align; 160 if (align_off != need_off) { 161 printf("\t\tchar __pad%d[%d];\n", 162 pad_cnt, need_off - off); 163 pad_cnt++; 164 } 165 166 /* sanitize variable name, e.g., for static vars inside 167 * a function, it's name is '<function name>.<variable name>', 168 * which we'll turn into a '<function name>_<variable name>' 169 */ 170 var_ident[0] = '\0'; 171 strncat(var_ident, var_name, sizeof(var_ident) - 1); 172 sanitize_identifier(var_ident); 173 174 printf("\t\t"); 175 err = btf_dump__emit_type_decl(d, var_type_id, &opts); 176 if (err) 177 return err; 178 printf(";\n"); 179 180 off = sec_var->offset + sec_var->size; 181 } 182 printf(" } *%s;\n", sec_ident); 183 return 0; 184 } 185 186 static int codegen_datasecs(struct bpf_object *obj, const char *obj_name) 187 { 188 struct btf *btf = bpf_object__btf(obj); 189 int n = btf__get_nr_types(btf); 190 struct btf_dump *d; 191 int i, err = 0; 192 193 d = btf_dump__new(btf, NULL, NULL, codegen_btf_dump_printf); 194 if (IS_ERR(d)) 195 return PTR_ERR(d); 196 197 for (i = 1; i <= n; i++) { 198 const struct btf_type *t = btf__type_by_id(btf, i); 199 200 if (!btf_is_datasec(t)) 201 continue; 202 203 err = codegen_datasec_def(obj, btf, d, t, obj_name); 204 if (err) 205 goto out; 206 } 207 out: 208 btf_dump__free(d); 209 return err; 210 } 211 212 static void codegen(const char *template, ...) 213 { 214 const char *src, *end; 215 int skip_tabs = 0, n; 216 char *s, *dst; 217 va_list args; 218 char c; 219 220 n = strlen(template); 221 s = malloc(n + 1); 222 if (!s) 223 exit(-1); 224 src = template; 225 dst = s; 226 227 /* find out "baseline" indentation to skip */ 228 while ((c = *src++)) { 229 if (c == '\t') { 230 skip_tabs++; 231 } else if (c == '\n') { 232 break; 233 } else { 234 p_err("unrecognized character at pos %td in template '%s'", 235 src - template - 1, template); 236 free(s); 237 exit(-1); 238 } 239 } 240 241 while (*src) { 242 /* skip baseline indentation tabs */ 243 for (n = skip_tabs; n > 0; n--, src++) { 244 if (*src != '\t') { 245 p_err("not enough tabs at pos %td in template '%s'", 246 src - template - 1, template); 247 free(s); 248 exit(-1); 249 } 250 } 251 /* trim trailing whitespace */ 252 end = strchrnul(src, '\n'); 253 for (n = end - src; n > 0 && isspace(src[n - 1]); n--) 254 ; 255 memcpy(dst, src, n); 256 dst += n; 257 if (*end) 258 *dst++ = '\n'; 259 src = *end ? end + 1 : end; 260 } 261 *dst++ = '\0'; 262 263 /* print out using adjusted template */ 264 va_start(args, template); 265 n = vprintf(s, args); 266 va_end(args); 267 268 free(s); 269 } 270 271 static int do_skeleton(int argc, char **argv) 272 { 273 char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")]; 274 size_t i, map_cnt = 0, prog_cnt = 0, file_sz, mmap_sz; 275 DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts); 276 char obj_name[MAX_OBJ_NAME_LEN], *obj_data; 277 struct bpf_object *obj = NULL; 278 const char *file, *ident; 279 struct bpf_program *prog; 280 int fd, len, err = -1; 281 struct bpf_map *map; 282 struct btf *btf; 283 struct stat st; 284 285 if (!REQ_ARGS(1)) { 286 usage(); 287 return -1; 288 } 289 file = GET_ARG(); 290 291 if (argc) { 292 p_err("extra unknown arguments"); 293 return -1; 294 } 295 296 if (stat(file, &st)) { 297 p_err("failed to stat() %s: %s", file, strerror(errno)); 298 return -1; 299 } 300 file_sz = st.st_size; 301 mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE)); 302 fd = open(file, O_RDONLY); 303 if (fd < 0) { 304 p_err("failed to open() %s: %s", file, strerror(errno)); 305 return -1; 306 } 307 obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0); 308 if (obj_data == MAP_FAILED) { 309 obj_data = NULL; 310 p_err("failed to mmap() %s: %s", file, strerror(errno)); 311 goto out; 312 } 313 get_obj_name(obj_name, file); 314 opts.object_name = obj_name; 315 obj = bpf_object__open_mem(obj_data, file_sz, &opts); 316 if (IS_ERR(obj)) { 317 char err_buf[256]; 318 319 libbpf_strerror(PTR_ERR(obj), err_buf, sizeof(err_buf)); 320 p_err("failed to open BPF object file: %s", err_buf); 321 obj = NULL; 322 goto out; 323 } 324 325 bpf_object__for_each_map(map, obj) { 326 ident = get_map_ident(map); 327 if (!ident) { 328 p_err("ignoring unrecognized internal map '%s'...", 329 bpf_map__name(map)); 330 continue; 331 } 332 map_cnt++; 333 } 334 bpf_object__for_each_program(prog, obj) { 335 prog_cnt++; 336 } 337 338 get_header_guard(header_guard, obj_name); 339 codegen("\ 340 \n\ 341 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\ 342 \n\ 343 /* THIS FILE IS AUTOGENERATED! */ \n\ 344 #ifndef %2$s \n\ 345 #define %2$s \n\ 346 \n\ 347 #include <stdlib.h> \n\ 348 #include <bpf/libbpf.h> \n\ 349 \n\ 350 struct %1$s { \n\ 351 struct bpf_object_skeleton *skeleton; \n\ 352 struct bpf_object *obj; \n\ 353 ", 354 obj_name, header_guard 355 ); 356 357 if (map_cnt) { 358 printf("\tstruct {\n"); 359 bpf_object__for_each_map(map, obj) { 360 ident = get_map_ident(map); 361 if (!ident) 362 continue; 363 printf("\t\tstruct bpf_map *%s;\n", ident); 364 } 365 printf("\t} maps;\n"); 366 } 367 368 if (prog_cnt) { 369 printf("\tstruct {\n"); 370 bpf_object__for_each_program(prog, obj) { 371 printf("\t\tstruct bpf_program *%s;\n", 372 bpf_program__name(prog)); 373 } 374 printf("\t} progs;\n"); 375 printf("\tstruct {\n"); 376 bpf_object__for_each_program(prog, obj) { 377 printf("\t\tstruct bpf_link *%s;\n", 378 bpf_program__name(prog)); 379 } 380 printf("\t} links;\n"); 381 } 382 383 btf = bpf_object__btf(obj); 384 if (btf) { 385 err = codegen_datasecs(obj, obj_name); 386 if (err) 387 goto out; 388 } 389 390 codegen("\ 391 \n\ 392 }; \n\ 393 \n\ 394 static void \n\ 395 %1$s__destroy(struct %1$s *obj) \n\ 396 { \n\ 397 if (!obj) \n\ 398 return; \n\ 399 if (obj->skeleton) \n\ 400 bpf_object__destroy_skeleton(obj->skeleton);\n\ 401 free(obj); \n\ 402 } \n\ 403 \n\ 404 static inline int \n\ 405 %1$s__create_skeleton(struct %1$s *obj); \n\ 406 \n\ 407 static inline struct %1$s * \n\ 408 %1$s__open_opts(const struct bpf_object_open_opts *opts) \n\ 409 { \n\ 410 struct %1$s *obj; \n\ 411 \n\ 412 obj = (struct %1$s *)calloc(1, sizeof(*obj)); \n\ 413 if (!obj) \n\ 414 return NULL; \n\ 415 if (%1$s__create_skeleton(obj)) \n\ 416 goto err; \n\ 417 if (bpf_object__open_skeleton(obj->skeleton, opts)) \n\ 418 goto err; \n\ 419 \n\ 420 return obj; \n\ 421 err: \n\ 422 %1$s__destroy(obj); \n\ 423 return NULL; \n\ 424 } \n\ 425 \n\ 426 static inline struct %1$s * \n\ 427 %1$s__open(void) \n\ 428 { \n\ 429 return %1$s__open_opts(NULL); \n\ 430 } \n\ 431 \n\ 432 static inline int \n\ 433 %1$s__load(struct %1$s *obj) \n\ 434 { \n\ 435 return bpf_object__load_skeleton(obj->skeleton); \n\ 436 } \n\ 437 \n\ 438 static inline struct %1$s * \n\ 439 %1$s__open_and_load(void) \n\ 440 { \n\ 441 struct %1$s *obj; \n\ 442 \n\ 443 obj = %1$s__open(); \n\ 444 if (!obj) \n\ 445 return NULL; \n\ 446 if (%1$s__load(obj)) { \n\ 447 %1$s__destroy(obj); \n\ 448 return NULL; \n\ 449 } \n\ 450 return obj; \n\ 451 } \n\ 452 \n\ 453 static inline int \n\ 454 %1$s__attach(struct %1$s *obj) \n\ 455 { \n\ 456 return bpf_object__attach_skeleton(obj->skeleton); \n\ 457 } \n\ 458 \n\ 459 static inline void \n\ 460 %1$s__detach(struct %1$s *obj) \n\ 461 { \n\ 462 return bpf_object__detach_skeleton(obj->skeleton); \n\ 463 } \n\ 464 ", 465 obj_name 466 ); 467 468 codegen("\ 469 \n\ 470 \n\ 471 static inline int \n\ 472 %1$s__create_skeleton(struct %1$s *obj) \n\ 473 { \n\ 474 struct bpf_object_skeleton *s; \n\ 475 \n\ 476 s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\ 477 if (!s) \n\ 478 return -1; \n\ 479 obj->skeleton = s; \n\ 480 \n\ 481 s->sz = sizeof(*s); \n\ 482 s->name = \"%1$s\"; \n\ 483 s->obj = &obj->obj; \n\ 484 ", 485 obj_name 486 ); 487 if (map_cnt) { 488 codegen("\ 489 \n\ 490 \n\ 491 /* maps */ \n\ 492 s->map_cnt = %zu; \n\ 493 s->map_skel_sz = sizeof(*s->maps); \n\ 494 s->maps = (struct bpf_map_skeleton *)calloc(s->map_cnt, s->map_skel_sz);\n\ 495 if (!s->maps) \n\ 496 goto err; \n\ 497 ", 498 map_cnt 499 ); 500 i = 0; 501 bpf_object__for_each_map(map, obj) { 502 ident = get_map_ident(map); 503 504 if (!ident) 505 continue; 506 507 codegen("\ 508 \n\ 509 \n\ 510 s->maps[%zu].name = \"%s\"; \n\ 511 s->maps[%zu].map = &obj->maps.%s; \n\ 512 ", 513 i, bpf_map__name(map), i, ident); 514 /* memory-mapped internal maps */ 515 if (bpf_map__is_internal(map) && 516 (bpf_map__def(map)->map_flags & BPF_F_MMAPABLE)) { 517 printf("\ts->maps[%zu].mmaped = (void **)&obj->%s;\n", 518 i, ident); 519 } 520 i++; 521 } 522 } 523 if (prog_cnt) { 524 codegen("\ 525 \n\ 526 \n\ 527 /* programs */ \n\ 528 s->prog_cnt = %zu; \n\ 529 s->prog_skel_sz = sizeof(*s->progs); \n\ 530 s->progs = (struct bpf_prog_skeleton *)calloc(s->prog_cnt, s->prog_skel_sz);\n\ 531 if (!s->progs) \n\ 532 goto err; \n\ 533 ", 534 prog_cnt 535 ); 536 i = 0; 537 bpf_object__for_each_program(prog, obj) { 538 codegen("\ 539 \n\ 540 \n\ 541 s->progs[%1$zu].name = \"%2$s\"; \n\ 542 s->progs[%1$zu].prog = &obj->progs.%2$s;\n\ 543 s->progs[%1$zu].link = &obj->links.%2$s;\n\ 544 ", 545 i, bpf_program__name(prog)); 546 i++; 547 } 548 } 549 codegen("\ 550 \n\ 551 \n\ 552 s->data_sz = %d; \n\ 553 s->data = (void *)\"\\ \n\ 554 ", 555 file_sz); 556 557 /* embed contents of BPF object file */ 558 for (i = 0, len = 0; i < file_sz; i++) { 559 int w = obj_data[i] ? 4 : 2; 560 561 len += w; 562 if (len > 78) { 563 printf("\\\n"); 564 len = w; 565 } 566 if (!obj_data[i]) 567 printf("\\0"); 568 else 569 printf("\\x%02x", (unsigned char)obj_data[i]); 570 } 571 572 codegen("\ 573 \n\ 574 \"; \n\ 575 \n\ 576 return 0; \n\ 577 err: \n\ 578 bpf_object__destroy_skeleton(s); \n\ 579 return -1; \n\ 580 } \n\ 581 \n\ 582 #endif /* %s */ \n\ 583 ", 584 header_guard); 585 err = 0; 586 out: 587 bpf_object__close(obj); 588 if (obj_data) 589 munmap(obj_data, mmap_sz); 590 close(fd); 591 return err; 592 } 593 594 static int do_help(int argc, char **argv) 595 { 596 if (json_output) { 597 jsonw_null(json_wtr); 598 return 0; 599 } 600 601 fprintf(stderr, 602 "Usage: %1$s %2$s skeleton FILE\n" 603 " %1$s %2$s help\n" 604 "\n" 605 " " HELP_SPEC_OPTIONS "\n" 606 "", 607 bin_name, "gen"); 608 609 return 0; 610 } 611 612 static const struct cmd cmds[] = { 613 { "skeleton", do_skeleton }, 614 { "help", do_help }, 615 { 0 } 616 }; 617 618 int do_gen(int argc, char **argv) 619 { 620 return cmd_select(cmds, argc, argv, do_help); 621 } 622