tools/bpf/bpftool/gen.c

   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 <bpf/libbpf_internal.h>
  18 #include <sys/types.h>
  19 #include <sys/stat.h>
  20 #include <sys/mman.h>
  21 #include <bpf/btf.h>
  22
  23 #include "json_writer.h"
  24 #include "main.h"
  25
  26 #define MAX_OBJ_NAME_LEN 64
  27
  28 static void sanitize_identifier(char *name)
  29 {
  30         int i;
  31
  32         for (i = 0; name[i]; i++)
  33                 if (!isalnum(name[i]) && name[i] != '_')
  34                         name[i] = '_';
  35 }
  36
  37 static bool str_has_prefix(const char *str, const char *prefix)
  38 {
  39         return strncmp(str, prefix, strlen(prefix)) == 0;
  40 }
  41
  42 static bool str_has_suffix(const char *str, const char *suffix)
  43 {
  44         size_t i, n1 = strlen(str), n2 = strlen(suffix);
  45
  46         if (n1 < n2)
  47                 return false;
  48
  49         for (i = 0; i < n2; i++) {
  50                 if (str[n1 - i - 1] != suffix[n2 - i - 1])
  51                         return false;
  52         }
  53
  54         return true;
  55 }
  56
  57 static void get_obj_name(char *name, const char *file)
  58 {
  59         /* Using basename() GNU version which doesn't modify arg. */
  60         strncpy(name, basename(file), MAX_OBJ_NAME_LEN - 1);
  61         name[MAX_OBJ_NAME_LEN - 1] = '\0';
  62         if (str_has_suffix(name, ".o"))
  63                 name[strlen(name) - 2] = '\0';
  64         sanitize_identifier(name);
  65 }
  66
  67 static void get_header_guard(char *guard, const char *obj_name, const char *suffix)
  68 {
  69         int i;
  70
  71         sprintf(guard, "__%s_%s__", obj_name, suffix);
  72         for (i = 0; guard[i]; i++)
  73                 guard[i] = toupper(guard[i]);
  74 }
  75
  76 static bool get_map_ident(const struct bpf_map *map, char *buf, size_t buf_sz)
  77 {
  78         static const char *sfxs[] = { ".data", ".rodata", ".bss", ".kconfig" };
  79         const char *name = bpf_map__name(map);
  80         int i, n;
  81
  82         if (!bpf_map__is_internal(map)) {
  83                 snprintf(buf, buf_sz, "%s", name);
  84                 return true;
  85         }
  86
  87         for  (i = 0, n = ARRAY_SIZE(sfxs); i < n; i++) {
  88                 const char *sfx = sfxs[i], *p;
  89
  90                 p = strstr(name, sfx);
  91                 if (p) {
  92                         snprintf(buf, buf_sz, "%s", p + 1);
  93                         sanitize_identifier(buf);
  94                         return true;
  95                 }
  96         }
  97
  98         return false;
  99 }
 100
 101 static bool get_datasec_ident(const char *sec_name, char *buf, size_t buf_sz)
 102 {
 103         static const char *pfxs[] = { ".data", ".rodata", ".bss", ".kconfig" };
 104         int i, n;
 105
 106         for  (i = 0, n = ARRAY_SIZE(pfxs); i < n; i++) {
 107                 const char *pfx = pfxs[i];
 108
 109                 if (str_has_prefix(sec_name, pfx)) {
 110                         snprintf(buf, buf_sz, "%s", sec_name + 1);
 111                         sanitize_identifier(buf);
 112                         return true;
 113                 }
 114         }
 115
 116         return false;
 117 }
 118
 119 static void codegen_btf_dump_printf(void *ctx, const char *fmt, va_list args)
 120 {
 121         vprintf(fmt, args);
 122 }
 123
 124 static int codegen_datasec_def(struct bpf_object *obj,
 125                                struct btf *btf,
 126                                struct btf_dump *d,
 127                                const struct btf_type *sec,
 128                                const char *obj_name)
 129 {
 130         const char *sec_name = btf__name_by_offset(btf, sec->name_off);
 131         const struct btf_var_secinfo *sec_var = btf_var_secinfos(sec);
 132         int i, err, off = 0, pad_cnt = 0, vlen = btf_vlen(sec);
 133         char var_ident[256], sec_ident[256];
 134         bool strip_mods = false;
 135
 136         if (!get_datasec_ident(sec_name, sec_ident, sizeof(sec_ident)))
 137                 return 0;
 138
 139         if (strcmp(sec_name, ".kconfig") != 0)
 140                 strip_mods = true;
 141
 142         printf("        struct %s__%s {\n", obj_name, sec_ident);
 143         for (i = 0; i < vlen; i++, sec_var++) {
 144                 const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
 145                 const char *var_name = btf__name_by_offset(btf, var->name_off);
 146                 DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
 147                         .field_name = var_ident,
 148                         .indent_level = 2,
 149                         .strip_mods = strip_mods,
 150                 );
 151                 int need_off = sec_var->offset, align_off, align;
 152                 __u32 var_type_id = var->type;
 153
 154                 /* static variables are not exposed through BPF skeleton */
 155                 if (btf_var(var)->linkage == BTF_VAR_STATIC)
 156                         continue;
 157
 158                 if (off > need_off) {
 159                         p_err("Something is wrong for %s's variable #%d: need offset %d, already at %d.\n",
 160                               sec_name, i, need_off, off);
 161                         return -EINVAL;
 162                 }
 163
 164                 align = btf__align_of(btf, var->type);
 165                 if (align <= 0) {
 166                         p_err("Failed to determine alignment of variable '%s': %d",
 167                               var_name, align);
 168                         return -EINVAL;
 169                 }
 170                 /* Assume 32-bit architectures when generating data section
 171                  * struct memory layout. Given bpftool can't know which target
 172                  * host architecture it's emitting skeleton for, we need to be
 173                  * conservative and assume 32-bit one to ensure enough padding
 174                  * bytes are generated for pointer and long types. This will
 175                  * still work correctly for 64-bit architectures, because in
 176                  * the worst case we'll generate unnecessary padding field,
 177                  * which on 64-bit architectures is not strictly necessary and
 178                  * would be handled by natural 8-byte alignment. But it still
 179                  * will be a correct memory layout, based on recorded offsets
 180                  * in BTF.
 181                  */
 182                 if (align > 4)
 183                         align = 4;
 184
 185                 align_off = (off + align - 1) / align * align;
 186                 if (align_off != need_off) {
 187                         printf("\t\tchar __pad%d[%d];\n",
 188                                pad_cnt, need_off - off);
 189                         pad_cnt++;
 190                 }
 191
 192                 /* sanitize variable name, e.g., for static vars inside
 193                  * a function, it's name is '<function name>.<variable name>',
 194                  * which we'll turn into a '<function name>_<variable name>'
 195                  */
 196                 var_ident[0] = '\0';
 197                 strncat(var_ident, var_name, sizeof(var_ident) - 1);
 198                 sanitize_identifier(var_ident);
 199
 200                 printf("\t\t");
 201                 err = btf_dump__emit_type_decl(d, var_type_id, &opts);
 202                 if (err)
 203                         return err;
 204                 printf(";\n");
 205
 206                 off = sec_var->offset + sec_var->size;
 207         }
 208         printf("        } *%s;\n", sec_ident);
 209         return 0;
 210 }
 211
 212 static const struct btf_type *find_type_for_map(struct btf *btf, const char *map_ident)
 213 {
 214         int n = btf__type_cnt(btf), i;
 215         char sec_ident[256];
 216
 217         for (i = 1; i < n; i++) {
 218                 const struct btf_type *t = btf__type_by_id(btf, i);
 219                 const char *name;
 220
 221                 if (!btf_is_datasec(t))
 222                         continue;
 223
 224                 name = btf__str_by_offset(btf, t->name_off);
 225                 if (!get_datasec_ident(name, sec_ident, sizeof(sec_ident)))
 226                         continue;
 227
 228                 if (strcmp(sec_ident, map_ident) == 0)
 229                         return t;
 230         }
 231         return NULL;
 232 }
 233
 234 static bool is_internal_mmapable_map(const struct bpf_map *map, char *buf, size_t sz)
 235 {
 236         if (!bpf_map__is_internal(map) || !(bpf_map__map_flags(map) & BPF_F_MMAPABLE))
 237                 return false;
 238
 239         if (!get_map_ident(map, buf, sz))
 240                 return false;
 241
 242         return true;
 243 }
 244
 245 static int codegen_datasecs(struct bpf_object *obj, const char *obj_name)
 246 {
 247         struct btf *btf = bpf_object__btf(obj);
 248         struct btf_dump *d;
 249         struct bpf_map *map;
 250         const struct btf_type *sec;
 251         char map_ident[256];
 252         int err = 0;
 253
 254         d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
 255         if (!d)
 256                 return -errno;
 257
 258         bpf_object__for_each_map(map, obj) {
 259                 /* only generate definitions for memory-mapped internal maps */
 260                 if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
 261                         continue;
 262
 263                 sec = find_type_for_map(btf, map_ident);
 264
 265                 /* In some cases (e.g., sections like .rodata.cst16 containing
 266                  * compiler allocated string constants only) there will be
 267                  * special internal maps with no corresponding DATASEC BTF
 268                  * type. In such case, generate empty structs for each such
 269                  * map. It will still be memory-mapped and its contents
 270                  * accessible from user-space through BPF skeleton.
 271                  */
 272                 if (!sec) {
 273                         printf("        struct %s__%s {\n", obj_name, map_ident);
 274                         printf("        } *%s;\n", map_ident);
 275                 } else {
 276                         err = codegen_datasec_def(obj, btf, d, sec, obj_name);
 277                         if (err)
 278                                 goto out;
 279                 }
 280         }
 281
 282
 283 out:
 284         btf_dump__free(d);
 285         return err;
 286 }
 287
 288 static bool btf_is_ptr_to_func_proto(const struct btf *btf,
 289                                      const struct btf_type *v)
 290 {
 291         return btf_is_ptr(v) && btf_is_func_proto(btf__type_by_id(btf, v->type));
 292 }
 293
 294 static int codegen_subskel_datasecs(struct bpf_object *obj, const char *obj_name)
 295 {
 296         struct btf *btf = bpf_object__btf(obj);
 297         struct btf_dump *d;
 298         struct bpf_map *map;
 299         const struct btf_type *sec, *var;
 300         const struct btf_var_secinfo *sec_var;
 301         int i, err = 0, vlen;
 302         char map_ident[256], sec_ident[256];
 303         bool strip_mods = false, needs_typeof = false;
 304         const char *sec_name, *var_name;
 305         __u32 var_type_id;
 306
 307         d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
 308         if (!d)
 309                 return -errno;
 310
 311         bpf_object__for_each_map(map, obj) {
 312                 /* only generate definitions for memory-mapped internal maps */
 313                 if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
 314                         continue;
 315
 316                 sec = find_type_for_map(btf, map_ident);
 317                 if (!sec)
 318                         continue;
 319
 320                 sec_name = btf__name_by_offset(btf, sec->name_off);
 321                 if (!get_datasec_ident(sec_name, sec_ident, sizeof(sec_ident)))
 322                         continue;
 323
 324                 strip_mods = strcmp(sec_name, ".kconfig") != 0;
 325                 printf("        struct %s__%s {\n", obj_name, sec_ident);
 326
 327                 sec_var = btf_var_secinfos(sec);
 328                 vlen = btf_vlen(sec);
 329                 for (i = 0; i < vlen; i++, sec_var++) {
 330                         DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
 331                                 .indent_level = 2,
 332                                 .strip_mods = strip_mods,
 333                                 /* we'll print the name separately */
 334                                 .field_name = "",
 335                         );
 336
 337                         var = btf__type_by_id(btf, sec_var->type);
 338                         var_name = btf__name_by_offset(btf, var->name_off);
 339                         var_type_id = var->type;
 340
 341                         /* static variables are not exposed through BPF skeleton */
 342                         if (btf_var(var)->linkage == BTF_VAR_STATIC)
 343                                 continue;
 344
 345                         /* The datasec member has KIND_VAR but we want the
 346                          * underlying type of the variable (e.g. KIND_INT).
 347                          */
 348                         var = skip_mods_and_typedefs(btf, var->type, NULL);
 349
 350                         printf("\t\t");
 351                         /* Func and array members require special handling.
 352                          * Instead of producing `typename *var`, they produce
 353                          * `typeof(typename) *var`. This allows us to keep a
 354                          * similar syntax where the identifier is just prefixed
 355                          * by *, allowing us to ignore C declaration minutiae.
 356                          */
 357                         needs_typeof = btf_is_array(var) || btf_is_ptr_to_func_proto(btf, var);
 358                         if (needs_typeof)
 359                                 printf("typeof(");
 360
 361                         err = btf_dump__emit_type_decl(d, var_type_id, &opts);
 362                         if (err)
 363                                 goto out;
 364
 365                         if (needs_typeof)
 366                                 printf(")");
 367
 368                         printf(" *%s;\n", var_name);
 369                 }
 370                 printf("        } %s;\n", sec_ident);
 371         }
 372
 373 out:
 374         btf_dump__free(d);
 375         return err;
 376 }
 377
 378 static void codegen(const char *template, ...)
 379 {
 380         const char *src, *end;
 381         int skip_tabs = 0, n;
 382         char *s, *dst;
 383         va_list args;
 384         char c;
 385
 386         n = strlen(template);
 387         s = malloc(n + 1);
 388         if (!s)
 389                 exit(-1);
 390         src = template;
 391         dst = s;
 392
 393         /* find out "baseline" indentation to skip */
 394         while ((c = *src++)) {
 395                 if (c == '\t') {
 396                         skip_tabs++;
 397                 } else if (c == '\n') {
 398                         break;
 399                 } else {
 400                         p_err("unrecognized character at pos %td in template '%s': '%c'",
 401                               src - template - 1, template, c);
 402                         free(s);
 403                         exit(-1);
 404                 }
 405         }
 406
 407         while (*src) {
 408                 /* skip baseline indentation tabs */
 409                 for (n = skip_tabs; n > 0; n--, src++) {
 410                         if (*src != '\t') {
 411                                 p_err("not enough tabs at pos %td in template '%s'",
 412                                       src - template - 1, template);
 413                                 free(s);
 414                                 exit(-1);
 415                         }
 416                 }
 417                 /* trim trailing whitespace */
 418                 end = strchrnul(src, '\n');
 419                 for (n = end - src; n > 0 && isspace(src[n - 1]); n--)
 420                         ;
 421                 memcpy(dst, src, n);
 422                 dst += n;
 423                 if (*end)
 424                         *dst++ = '\n';
 425                 src = *end ? end + 1 : end;
 426         }
 427         *dst++ = '\0';
 428
 429         /* print out using adjusted template */
 430         va_start(args, template);
 431         n = vprintf(s, args);
 432         va_end(args);
 433
 434         free(s);
 435 }
 436
 437 static void print_hex(const char *data, int data_sz)
 438 {
 439         int i, len;
 440
 441         for (i = 0, len = 0; i < data_sz; i++) {
 442                 int w = data[i] ? 4 : 2;
 443
 444                 len += w;
 445                 if (len > 78) {
 446                         printf("\\\n");
 447                         len = w;
 448                 }
 449                 if (!data[i])
 450                         printf("\\0");
 451                 else
 452                         printf("\\x%02x", (unsigned char)data[i]);
 453         }
 454 }
 455
 456 static size_t bpf_map_mmap_sz(const struct bpf_map *map)
 457 {
 458         long page_sz = sysconf(_SC_PAGE_SIZE);
 459         size_t map_sz;
 460
 461         map_sz = (size_t)roundup(bpf_map__value_size(map), 8) * bpf_map__max_entries(map);
 462         map_sz = roundup(map_sz, page_sz);
 463         return map_sz;
 464 }
 465
 466 /* Emit type size asserts for all top-level fields in memory-mapped internal maps. */
 467 static void codegen_asserts(struct bpf_object *obj, const char *obj_name)
 468 {
 469         struct btf *btf = bpf_object__btf(obj);
 470         struct bpf_map *map;
 471         struct btf_var_secinfo *sec_var;
 472         int i, vlen;
 473         const struct btf_type *sec;
 474         char map_ident[256], var_ident[256];
 475
 476         if (!btf)
 477                 return;
 478
 479         codegen("\
 480                 \n\
 481                 __attribute__((unused)) static void                         \n\
 482                 %1$s__assert(struct %1$s *s __attribute__((unused)))        \n\
 483                 {                                                           \n\
 484                 #ifdef __cplusplus                                          \n\
 485                 #define _Static_assert static_assert                        \n\
 486                 #endif                                                      \n\
 487                 ", obj_name);
 488
 489         bpf_object__for_each_map(map, obj) {
 490                 if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
 491                         continue;
 492
 493                 sec = find_type_for_map(btf, map_ident);
 494                 if (!sec) {
 495                         /* best effort, couldn't find the type for this map */
 496                         continue;
 497                 }
 498
 499                 sec_var = btf_var_secinfos(sec);
 500                 vlen =  btf_vlen(sec);
 501
 502                 for (i = 0; i < vlen; i++, sec_var++) {
 503                         const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
 504                         const char *var_name = btf__name_by_offset(btf, var->name_off);
 505                         long var_size;
 506
 507                         /* static variables are not exposed through BPF skeleton */
 508                         if (btf_var(var)->linkage == BTF_VAR_STATIC)
 509                                 continue;
 510
 511                         var_size = btf__resolve_size(btf, var->type);
 512                         if (var_size < 0)
 513                                 continue;
 514
 515                         var_ident[0] = '\0';
 516                         strncat(var_ident, var_name, sizeof(var_ident) - 1);
 517                         sanitize_identifier(var_ident);
 518
 519                         printf("\t_Static_assert(sizeof(s->%s->%s) == %ld, \"unexpected size of '%s'\");\n",
 520                                map_ident, var_ident, var_size, var_ident);
 521                 }
 522         }
 523         codegen("\
 524                 \n\
 525                 #ifdef __cplusplus                                          \n\
 526                 #undef _Static_assert                                       \n\
 527                 #endif                                                      \n\
 528                 }                                                           \n\
 529                 ");
 530 }
 531
 532 static void codegen_attach_detach(struct bpf_object *obj, const char *obj_name)
 533 {
 534         struct bpf_program *prog;
 535
 536         bpf_object__for_each_program(prog, obj) {
 537                 const char *tp_name;
 538
 539                 codegen("\
 540                         \n\
 541                         \n\
 542                         static inline int                                           \n\
 543                         %1$s__%2$s__attach(struct %1$s *skel)                       \n\
 544                         {                                                           \n\
 545                                 int prog_fd = skel->progs.%2$s.prog_fd;             \n\
 546                         ", obj_name, bpf_program__name(prog));
 547
 548                 switch (bpf_program__type(prog)) {
 549                 case BPF_PROG_TYPE_RAW_TRACEPOINT:
 550                         tp_name = strchr(bpf_program__section_name(prog), '/') + 1;
 551                         printf("\tint fd = skel_raw_tracepoint_open(\"%s\", prog_fd);\n", tp_name);
 552                         break;
 553                 case BPF_PROG_TYPE_TRACING:
 554                 case BPF_PROG_TYPE_LSM:
 555                         if (bpf_program__expected_attach_type(prog) == BPF_TRACE_ITER)
 556                                 printf("\tint fd = skel_link_create(prog_fd, 0, BPF_TRACE_ITER);\n");
 557                         else
 558                                 printf("\tint fd = skel_raw_tracepoint_open(NULL, prog_fd);\n");
 559                         break;
 560                 default:
 561                         printf("\tint fd = ((void)prog_fd, 0); /* auto-attach not supported */\n");
 562                         break;
 563                 }
 564                 codegen("\
 565                         \n\
 566                                                                                     \n\
 567                                 if (fd > 0)                                         \n\
 568                                         skel->links.%1$s_fd = fd;                   \n\
 569                                 return fd;                                          \n\
 570                         }                                                           \n\
 571                         ", bpf_program__name(prog));
 572         }
 573
 574         codegen("\
 575                 \n\
 576                                                                             \n\
 577                 static inline int                                           \n\
 578                 %1$s__attach(struct %1$s *skel)                             \n\
 579                 {                                                           \n\
 580                         int ret = 0;                                        \n\
 581                                                                             \n\
 582                 ", obj_name);
 583
 584         bpf_object__for_each_program(prog, obj) {
 585                 codegen("\
 586                         \n\
 587                                 ret = ret < 0 ? ret : %1$s__%2$s__attach(skel);   \n\
 588                         ", obj_name, bpf_program__name(prog));
 589         }
 590
 591         codegen("\
 592                 \n\
 593                         return ret < 0 ? ret : 0;                           \n\
 594                 }                                                           \n\
 595                                                                             \n\
 596                 static inline void                                          \n\
 597                 %1$s__detach(struct %1$s *skel)                             \n\
 598                 {                                                           \n\
 599                 ", obj_name);
 600
 601         bpf_object__for_each_program(prog, obj) {
 602                 codegen("\
 603                         \n\
 604                                 skel_closenz(skel->links.%1$s_fd);          \n\
 605                         ", bpf_program__name(prog));
 606         }
 607
 608         codegen("\
 609                 \n\
 610                 }                                                           \n\
 611                 ");
 612 }
 613
 614 static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
 615 {
 616         struct bpf_program *prog;
 617         struct bpf_map *map;
 618         char ident[256];
 619
 620         codegen("\
 621                 \n\
 622                 static void                                                 \n\
 623                 %1$s__destroy(struct %1$s *skel)                            \n\
 624                 {                                                           \n\
 625                         if (!skel)                                          \n\
 626                                 return;                                     \n\
 627                         %1$s__detach(skel);                                 \n\
 628                 ",
 629                 obj_name);
 630
 631         bpf_object__for_each_program(prog, obj) {
 632                 codegen("\
 633                         \n\
 634                                 skel_closenz(skel->progs.%1$s.prog_fd);     \n\
 635                         ", bpf_program__name(prog));
 636         }
 637
 638         bpf_object__for_each_map(map, obj) {
 639                 if (!get_map_ident(map, ident, sizeof(ident)))
 640                         continue;
 641                 if (bpf_map__is_internal(map) &&
 642                     (bpf_map__map_flags(map) & BPF_F_MMAPABLE))
 643                         printf("\tskel_free_map_data(skel->%1$s, skel->maps.%1$s.initial_value, %2$zd);\n",
 644                                ident, bpf_map_mmap_sz(map));
 645                 codegen("\
 646                         \n\
 647                                 skel_closenz(skel->maps.%1$s.map_fd);       \n\
 648                         ", ident);
 649         }
 650         codegen("\
 651                 \n\
 652                         skel_free(skel);                                    \n\
 653                 }                                                           \n\
 654                 ",
 655                 obj_name);
 656 }
 657
 658 static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *header_guard)
 659 {
 660         DECLARE_LIBBPF_OPTS(gen_loader_opts, opts);
 661         struct bpf_map *map;
 662         char ident[256];
 663         int err = 0;
 664
 665         err = bpf_object__gen_loader(obj, &opts);
 666         if (err)
 667                 return err;
 668
 669         err = bpf_object__load(obj);
 670         if (err) {
 671                 p_err("failed to load object file");
 672                 goto out;
 673         }
 674         /* If there was no error during load then gen_loader_opts
 675          * are populated with the loader program.
 676          */
 677
 678         /* finish generating 'struct skel' */
 679         codegen("\
 680                 \n\
 681                 };                                                          \n\
 682                 ", obj_name);
 683
 684
 685         codegen_attach_detach(obj, obj_name);
 686
 687         codegen_destroy(obj, obj_name);
 688
 689         codegen("\
 690                 \n\
 691                 static inline struct %1$s *                                 \n\
 692                 %1$s__open(void)                                            \n\
 693                 {                                                           \n\
 694                         struct %1$s *skel;                                  \n\
 695                                                                             \n\
 696                         skel = skel_alloc(sizeof(*skel));                   \n\
 697                         if (!skel)                                          \n\
 698                                 goto cleanup;                               \n\
 699                         skel->ctx.sz = (void *)&skel->links - (void *)skel; \n\
 700                 ",
 701                 obj_name, opts.data_sz);
 702         bpf_object__for_each_map(map, obj) {
 703                 const void *mmap_data = NULL;
 704                 size_t mmap_size = 0;
 705
 706                 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
 707                         continue;
 708
 709                 codegen("\
 710                 \n\
 711                         skel->%1$s = skel_prep_map_data((void *)\"\\        \n\
 712                 ", ident);
 713                 mmap_data = bpf_map__initial_value(map, &mmap_size);
 714                 print_hex(mmap_data, mmap_size);
 715                 codegen("\
 716                 \n\
 717                 \", %1$zd, %2$zd);                                          \n\
 718                         if (!skel->%3$s)                                    \n\
 719                                 goto cleanup;                               \n\
 720                         skel->maps.%3$s.initial_value = (__u64) (long) skel->%3$s;\n\
 721                 ", bpf_map_mmap_sz(map), mmap_size, ident);
 722         }
 723         codegen("\
 724                 \n\
 725                         return skel;                                        \n\
 726                 cleanup:                                                    \n\
 727                         %1$s__destroy(skel);                                \n\
 728                         return NULL;                                        \n\
 729                 }                                                           \n\
 730                                                                             \n\
 731                 static inline int                                           \n\
 732                 %1$s__load(struct %1$s *skel)                               \n\
 733                 {                                                           \n\
 734                         struct bpf_load_and_run_opts opts = {};             \n\
 735                         int err;                                            \n\
 736                                                                             \n\
 737                         opts.ctx = (struct bpf_loader_ctx *)skel;           \n\
 738                         opts.data_sz = %2$d;                                \n\
 739                         opts.data = (void *)\"\\                            \n\
 740                 ",
 741                 obj_name, opts.data_sz);
 742         print_hex(opts.data, opts.data_sz);
 743         codegen("\
 744                 \n\
 745                 \";                                                         \n\
 746                 ");
 747
 748         codegen("\
 749                 \n\
 750                         opts.insns_sz = %d;                                 \n\
 751                         opts.insns = (void *)\"\\                           \n\
 752                 ",
 753                 opts.insns_sz);
 754         print_hex(opts.insns, opts.insns_sz);
 755         codegen("\
 756                 \n\
 757                 \";                                                         \n\
 758                         err = bpf_load_and_run(&opts);                      \n\
 759                         if (err < 0)                                        \n\
 760                                 return err;                                 \n\
 761                 ", obj_name);
 762         bpf_object__for_each_map(map, obj) {
 763                 const char *mmap_flags;
 764
 765                 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
 766                         continue;
 767
 768                 if (bpf_map__map_flags(map) & BPF_F_RDONLY_PROG)
 769                         mmap_flags = "PROT_READ";
 770                 else
 771                         mmap_flags = "PROT_READ | PROT_WRITE";
 772
 773                 codegen("\
 774                 \n\
 775                         skel->%1$s = skel_finalize_map_data(&skel->maps.%1$s.initial_value,  \n\
 776                                                         %2$zd, %3$s, skel->maps.%1$s.map_fd);\n\
 777                         if (!skel->%1$s)                                    \n\
 778                                 return -ENOMEM;                             \n\
 779                         ",
 780                        ident, bpf_map_mmap_sz(map), mmap_flags);
 781         }
 782         codegen("\
 783                 \n\
 784                         return 0;                                           \n\
 785                 }                                                           \n\
 786                                                                             \n\
 787                 static inline struct %1$s *                                 \n\
 788                 %1$s__open_and_load(void)                                   \n\
 789                 {                                                           \n\
 790                         struct %1$s *skel;                                  \n\
 791                                                                             \n\
 792                         skel = %1$s__open();                                \n\
 793                         if (!skel)                                          \n\
 794                                 return NULL;                                \n\
 795                         if (%1$s__load(skel)) {                             \n\
 796                                 %1$s__destroy(skel);                        \n\
 797                                 return NULL;                                \n\
 798                         }                                                   \n\
 799                         return skel;                                        \n\
 800                 }                                                           \n\
 801                                                                             \n\
 802                 ", obj_name);
 803
 804         codegen_asserts(obj, obj_name);
 805
 806         codegen("\
 807                 \n\
 808                                                                             \n\
 809                 #endif /* %s */                                             \n\
 810                 ",
 811                 header_guard);
 812         err = 0;
 813 out:
 814         return err;
 815 }
 816
 817 static void
 818 codegen_maps_skeleton(struct bpf_object *obj, size_t map_cnt, bool mmaped)
 819 {
 820         struct bpf_map *map;
 821         char ident[256];
 822         size_t i;
 823
 824         if (!map_cnt)
 825                 return;
 826
 827         codegen("\
 828                 \n\
 829                                                                         \n\
 830                         /* maps */                                  \n\
 831                         s->map_cnt = %zu;                           \n\
 832                         s->map_skel_sz = sizeof(*s->maps);          \n\
 833                         s->maps = (struct bpf_map_skeleton *)calloc(s->map_cnt, s->map_skel_sz);\n\
 834                         if (!s->maps) {                             \n\
 835                                 err = -ENOMEM;                      \n\
 836                                 goto err;                           \n\
 837                         }                                           \n\
 838                 ",
 839                 map_cnt
 840         );
 841         i = 0;
 842         bpf_object__for_each_map(map, obj) {
 843                 if (!get_map_ident(map, ident, sizeof(ident)))
 844                         continue;
 845
 846                 codegen("\
 847                         \n\
 848                                                                         \n\
 849                                 s->maps[%zu].name = \"%s\";         \n\
 850                                 s->maps[%zu].map = &obj->maps.%s;   \n\
 851                         ",
 852                         i, bpf_map__name(map), i, ident);
 853                 /* memory-mapped internal maps */
 854                 if (mmaped && is_internal_mmapable_map(map, ident, sizeof(ident))) {
 855                         printf("\ts->maps[%zu].mmaped = (void **)&obj->%s;\n",
 856                                 i, ident);
 857                 }
 858                 i++;
 859         }
 860 }
 861
 862 static void
 863 codegen_progs_skeleton(struct bpf_object *obj, size_t prog_cnt, bool populate_links)
 864 {
 865         struct bpf_program *prog;
 866         int i;
 867
 868         if (!prog_cnt)
 869                 return;
 870
 871         codegen("\
 872                 \n\
 873                                                                         \n\
 874                         /* programs */                              \n\
 875                         s->prog_cnt = %zu;                          \n\
 876                         s->prog_skel_sz = sizeof(*s->progs);        \n\
 877                         s->progs = (struct bpf_prog_skeleton *)calloc(s->prog_cnt, s->prog_skel_sz);\n\
 878                         if (!s->progs) {                            \n\
 879                                 err = -ENOMEM;                      \n\
 880                                 goto err;                           \n\
 881                         }                                           \n\
 882                 ",
 883                 prog_cnt
 884         );
 885         i = 0;
 886         bpf_object__for_each_program(prog, obj) {
 887                 codegen("\
 888                         \n\
 889                                                                         \n\
 890                                 s->progs[%1$zu].name = \"%2$s\";    \n\
 891                                 s->progs[%1$zu].prog = &obj->progs.%2$s;\n\
 892                         ",
 893                         i, bpf_program__name(prog));
 894
 895                 if (populate_links) {
 896                         codegen("\
 897                                 \n\
 898                                         s->progs[%1$zu].link = &obj->links.%2$s;\n\
 899                                 ",
 900                                 i, bpf_program__name(prog));
 901                 }
 902                 i++;
 903         }
 904 }
 905
 906 static int do_skeleton(int argc, char **argv)
 907 {
 908         char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")];
 909         size_t map_cnt = 0, prog_cnt = 0, file_sz, mmap_sz;
 910         DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
 911         char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
 912         struct bpf_object *obj = NULL;
 913         const char *file;
 914         char ident[256];
 915         struct bpf_program *prog;
 916         int fd, err = -1;
 917         struct bpf_map *map;
 918         struct btf *btf;
 919         struct stat st;
 920
 921         if (!REQ_ARGS(1)) {
 922                 usage();
 923                 return -1;
 924         }
 925         file = GET_ARG();
 926
 927         while (argc) {
 928                 if (!REQ_ARGS(2))
 929                         return -1;
 930
 931                 if (is_prefix(*argv, "name")) {
 932                         NEXT_ARG();
 933
 934                         if (obj_name[0] != '\0') {
 935                                 p_err("object name already specified");
 936                                 return -1;
 937                         }
 938
 939                         strncpy(obj_name, *argv, MAX_OBJ_NAME_LEN - 1);
 940                         obj_name[MAX_OBJ_NAME_LEN - 1] = '\0';
 941                 } else {
 942                         p_err("unknown arg %s", *argv);
 943                         return -1;
 944                 }
 945
 946                 NEXT_ARG();
 947         }
 948
 949         if (argc) {
 950                 p_err("extra unknown arguments");
 951                 return -1;
 952         }
 953
 954         if (stat(file, &st)) {
 955                 p_err("failed to stat() %s: %s", file, strerror(errno));
 956                 return -1;
 957         }
 958         file_sz = st.st_size;
 959         mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
 960         fd = open(file, O_RDONLY);
 961         if (fd < 0) {
 962                 p_err("failed to open() %s: %s", file, strerror(errno));
 963                 return -1;
 964         }
 965         obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
 966         if (obj_data == MAP_FAILED) {
 967                 obj_data = NULL;
 968                 p_err("failed to mmap() %s: %s", file, strerror(errno));
 969                 goto out;
 970         }
 971         if (obj_name[0] == '\0')
 972                 get_obj_name(obj_name, file);
 973         opts.object_name = obj_name;
 974         if (verifier_logs)
 975                 /* log_level1 + log_level2 + stats, but not stable UAPI */
 976                 opts.kernel_log_level = 1 + 2 + 4;
 977         obj = bpf_object__open_mem(obj_data, file_sz, &opts);
 978         if (!obj) {
 979                 char err_buf[256];
 980
 981                 err = -errno;
 982                 libbpf_strerror(err, err_buf, sizeof(err_buf));
 983                 p_err("failed to open BPF object file: %s", err_buf);
 984                 goto out;
 985         }
 986
 987         bpf_object__for_each_map(map, obj) {
 988                 if (!get_map_ident(map, ident, sizeof(ident))) {
 989                         p_err("ignoring unrecognized internal map '%s'...",
 990                               bpf_map__name(map));
 991                         continue;
 992                 }
 993                 map_cnt++;
 994         }
 995         bpf_object__for_each_program(prog, obj) {
 996                 prog_cnt++;
 997         }
 998
 999         get_header_guard(header_guard, obj_name, "SKEL_H");
1000         if (use_loader) {
1001                 codegen("\
1002                 \n\
1003                 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */   \n\
1004                 /* THIS FILE IS AUTOGENERATED BY BPFTOOL! */                \n\
1005                 #ifndef %2$s                                                \n\
1006                 #define %2$s                                                \n\
1007                                                                             \n\
1008                 #include <bpf/skel_internal.h>                              \n\
1009                                                                             \n\
1010                 struct %1$s {                                               \n\
1011                         struct bpf_loader_ctx ctx;                          \n\
1012                 ",
1013                 obj_name, header_guard
1014                 );
1015         } else {
1016                 codegen("\
1017                 \n\
1018                 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */   \n\
1019                                                                             \n\
1020                 /* THIS FILE IS AUTOGENERATED BY BPFTOOL! */                \n\
1021                 #ifndef %2$s                                                \n\
1022                 #define %2$s                                                \n\
1023                                                                             \n\
1024                 #include <errno.h>                                          \n\
1025                 #include <stdlib.h>                                         \n\
1026                 #include <bpf/libbpf.h>                                     \n\
1027                                                                             \n\
1028                 struct %1$s {                                               \n\
1029                         struct bpf_object_skeleton *skeleton;               \n\
1030                         struct bpf_object *obj;                             \n\
1031                 ",
1032                 obj_name, header_guard
1033                 );
1034         }
1035
1036         if (map_cnt) {
1037                 printf("\tstruct {\n");
1038                 bpf_object__for_each_map(map, obj) {
1039                         if (!get_map_ident(map, ident, sizeof(ident)))
1040                                 continue;
1041                         if (use_loader)
1042                                 printf("\t\tstruct bpf_map_desc %s;\n", ident);
1043                         else
1044                                 printf("\t\tstruct bpf_map *%s;\n", ident);
1045                 }
1046                 printf("\t} maps;\n");
1047         }
1048
1049         if (prog_cnt) {
1050                 printf("\tstruct {\n");
1051                 bpf_object__for_each_program(prog, obj) {
1052                         if (use_loader)
1053                                 printf("\t\tstruct bpf_prog_desc %s;\n",
1054                                        bpf_program__name(prog));
1055                         else
1056                                 printf("\t\tstruct bpf_program *%s;\n",
1057                                        bpf_program__name(prog));
1058                 }
1059                 printf("\t} progs;\n");
1060                 printf("\tstruct {\n");
1061                 bpf_object__for_each_program(prog, obj) {
1062                         if (use_loader)
1063                                 printf("\t\tint %s_fd;\n",
1064                                        bpf_program__name(prog));
1065                         else
1066                                 printf("\t\tstruct bpf_link *%s;\n",
1067                                        bpf_program__name(prog));
1068                 }
1069                 printf("\t} links;\n");
1070         }
1071
1072         btf = bpf_object__btf(obj);
1073         if (btf) {
1074                 err = codegen_datasecs(obj, obj_name);
1075                 if (err)
1076                         goto out;
1077         }
1078         if (use_loader) {
1079                 err = gen_trace(obj, obj_name, header_guard);
1080                 goto out;
1081         }
1082
1083         codegen("\
1084                 \n\
1085                                                                             \n\
1086                 #ifdef __cplusplus                                          \n\
1087                         static inline struct %1$s *open(const struct bpf_object_open_opts *opts = nullptr);\n\
1088                         static inline struct %1$s *open_and_load();         \n\
1089                         static inline int load(struct %1$s *skel);          \n\
1090                         static inline int attach(struct %1$s *skel);        \n\
1091                         static inline void detach(struct %1$s *skel);       \n\
1092                         static inline void destroy(struct %1$s *skel);      \n\
1093                         static inline const void *elf_bytes(size_t *sz);    \n\
1094                 #endif /* __cplusplus */                                    \n\
1095                 };                                                          \n\
1096                                                                             \n\
1097                 static void                                                 \n\
1098                 %1$s__destroy(struct %1$s *obj)                             \n\
1099                 {                                                           \n\
1100                         if (!obj)                                           \n\
1101                                 return;                                     \n\
1102                         if (obj->skeleton)                                  \n\
1103                                 bpf_object__destroy_skeleton(obj->skeleton);\n\
1104                         free(obj);                                          \n\
1105                 }                                                           \n\
1106                                                                             \n\
1107                 static inline int                                           \n\
1108                 %1$s__create_skeleton(struct %1$s *obj);                    \n\
1109                                                                             \n\
1110                 static inline struct %1$s *                                 \n\
1111                 %1$s__open_opts(const struct bpf_object_open_opts *opts)    \n\
1112                 {                                                           \n\
1113                         struct %1$s *obj;                                   \n\
1114                         int err;                                            \n\
1115                                                                             \n\
1116                         obj = (struct %1$s *)calloc(1, sizeof(*obj));       \n\
1117                         if (!obj) {                                         \n\
1118                                 errno = ENOMEM;                             \n\
1119                                 return NULL;                                \n\
1120                         }                                                   \n\
1121                                                                             \n\
1122                         err = %1$s__create_skeleton(obj);                   \n\
1123                         if (err)                                            \n\
1124                                 goto err_out;                               \n\
1125                                                                             \n\
1126                         err = bpf_object__open_skeleton(obj->skeleton, opts);\n\
1127                         if (err)                                            \n\
1128                                 goto err_out;                               \n\
1129                                                                             \n\
1130                         return obj;                                         \n\
1131                 err_out:                                                    \n\
1132                         %1$s__destroy(obj);                                 \n\
1133                         errno = -err;                                       \n\
1134                         return NULL;                                        \n\
1135                 }                                                           \n\
1136                                                                             \n\
1137                 static inline struct %1$s *                                 \n\
1138                 %1$s__open(void)                                            \n\
1139                 {                                                           \n\
1140                         return %1$s__open_opts(NULL);                       \n\
1141                 }                                                           \n\
1142                                                                             \n\
1143                 static inline int                                           \n\
1144                 %1$s__load(struct %1$s *obj)                                \n\
1145                 {                                                           \n\
1146                         return bpf_object__load_skeleton(obj->skeleton);    \n\
1147                 }                                                           \n\
1148                                                                             \n\
1149                 static inline struct %1$s *                                 \n\
1150                 %1$s__open_and_load(void)                                   \n\
1151                 {                                                           \n\
1152                         struct %1$s *obj;                                   \n\
1153                         int err;                                            \n\
1154                                                                             \n\
1155                         obj = %1$s__open();                                 \n\
1156                         if (!obj)                                           \n\
1157                                 return NULL;                                \n\
1158                         err = %1$s__load(obj);                              \n\
1159                         if (err) {                                          \n\
1160                                 %1$s__destroy(obj);                         \n\
1161                                 errno = -err;                               \n\
1162                                 return NULL;                                \n\
1163                         }                                                   \n\
1164                         return obj;                                         \n\
1165                 }                                                           \n\
1166                                                                             \n\
1167                 static inline int                                           \n\
1168                 %1$s__attach(struct %1$s *obj)                              \n\
1169                 {                                                           \n\
1170                         return bpf_object__attach_skeleton(obj->skeleton);  \n\
1171                 }                                                           \n\
1172                                                                             \n\
1173                 static inline void                                          \n\
1174                 %1$s__detach(struct %1$s *obj)                              \n\
1175                 {                                                           \n\
1176                         bpf_object__detach_skeleton(obj->skeleton);         \n\
1177                 }                                                           \n\
1178                 ",
1179                 obj_name
1180         );
1181
1182         codegen("\
1183                 \n\
1184                                                                             \n\
1185                 static inline const void *%1$s__elf_bytes(size_t *sz);      \n\
1186                                                                             \n\
1187                 static inline int                                           \n\
1188                 %1$s__create_skeleton(struct %1$s *obj)                     \n\
1189                 {                                                           \n\
1190                         struct bpf_object_skeleton *s;                      \n\
1191                         int err;                                            \n\
1192                                                                             \n\
1193                         s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\
1194                         if (!s) {                                           \n\
1195                                 err = -ENOMEM;                              \n\
1196                                 goto err;                                   \n\
1197                         }                                                   \n\
1198                                                                             \n\
1199                         s->sz = sizeof(*s);                                 \n\
1200                         s->name = \"%1$s\";                                 \n\
1201                         s->obj = &obj->obj;                                 \n\
1202                 ",
1203                 obj_name
1204         );
1205
1206         codegen_maps_skeleton(obj, map_cnt, true /*mmaped*/);
1207         codegen_progs_skeleton(obj, prog_cnt, true /*populate_links*/);
1208
1209         codegen("\
1210                 \n\
1211                                                                             \n\
1212                         s->data = (void *)%2$s__elf_bytes(&s->data_sz);     \n\
1213                                                                             \n\
1214                         obj->skeleton = s;                                  \n\
1215                         return 0;                                           \n\
1216                 err:                                                        \n\
1217                         bpf_object__destroy_skeleton(s);                    \n\
1218                         return err;                                         \n\
1219                 }                                                           \n\
1220                                                                             \n\
1221                 static inline const void *%2$s__elf_bytes(size_t *sz)       \n\
1222                 {                                                           \n\
1223                         *sz = %1$d;                                         \n\
1224                         return (const void *)\"\\                           \n\
1225                 "
1226                 , file_sz, obj_name);
1227
1228         /* embed contents of BPF object file */
1229         print_hex(obj_data, file_sz);
1230
1231         codegen("\
1232                 \n\
1233                 \";                                                         \n\
1234                 }                                                           \n\
1235                                                                             \n\
1236                 #ifdef __cplusplus                                          \n\
1237                 struct %1$s *%1$s::open(const struct bpf_object_open_opts *opts) { return %1$s__open_opts(opts); }\n\
1238                 struct %1$s *%1$s::open_and_load() { return %1$s__open_and_load(); }    \n\
1239                 int %1$s::load(struct %1$s *skel) { return %1$s__load(skel); }          \n\
1240                 int %1$s::attach(struct %1$s *skel) { return %1$s__attach(skel); }      \n\
1241                 void %1$s::detach(struct %1$s *skel) { %1$s__detach(skel); }            \n\
1242                 void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); }          \n\
1243                 const void *%1$s::elf_bytes(size_t *sz) { return %1$s__elf_bytes(sz); } \n\
1244                 #endif /* __cplusplus */                                    \n\
1245                                                                             \n\
1246                 ",
1247                 obj_name);
1248
1249         codegen_asserts(obj, obj_name);
1250
1251         codegen("\
1252                 \n\
1253                                                                             \n\
1254                 #endif /* %1$s */                                           \n\
1255                 ",
1256                 header_guard);
1257         err = 0;
1258 out:
1259         bpf_object__close(obj);
1260         if (obj_data)
1261                 munmap(obj_data, mmap_sz);
1262         close(fd);
1263         return err;
1264 }
1265
1266 /* Subskeletons are like skeletons, except they don't own the bpf_object,
1267  * associated maps, links, etc. Instead, they know about the existence of
1268  * variables, maps, programs and are able to find their locations
1269  * _at runtime_ from an already loaded bpf_object.
1270  *
1271  * This allows for library-like BPF objects to have userspace counterparts
1272  * with access to their own items without having to know anything about the
1273  * final BPF object that the library was linked into.
1274  */
1275 static int do_subskeleton(int argc, char **argv)
1276 {
1277         char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SUBSKEL_H__")];
1278         size_t i, len, file_sz, map_cnt = 0, prog_cnt = 0, mmap_sz, var_cnt = 0, var_idx = 0;
1279         DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
1280         char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
1281         struct bpf_object *obj = NULL;
1282         const char *file, *var_name;
1283         char ident[256];
1284         int fd, err = -1, map_type_id;
1285         const struct bpf_map *map;
1286         struct bpf_program *prog;
1287         struct btf *btf;
1288         const struct btf_type *map_type, *var_type;
1289         const struct btf_var_secinfo *var;
1290         struct stat st;
1291
1292         if (!REQ_ARGS(1)) {
1293                 usage();
1294                 return -1;
1295         }
1296         file = GET_ARG();
1297
1298         while (argc) {
1299                 if (!REQ_ARGS(2))
1300                         return -1;
1301
1302                 if (is_prefix(*argv, "name")) {
1303                         NEXT_ARG();
1304
1305                         if (obj_name[0] != '\0') {
1306                                 p_err("object name already specified");
1307                                 return -1;
1308                         }
1309
1310                         strncpy(obj_name, *argv, MAX_OBJ_NAME_LEN - 1);
1311                         obj_name[MAX_OBJ_NAME_LEN - 1] = '\0';
1312                 } else {
1313                         p_err("unknown arg %s", *argv);
1314                         return -1;
1315                 }
1316
1317                 NEXT_ARG();
1318         }
1319
1320         if (argc) {
1321                 p_err("extra unknown arguments");
1322                 return -1;
1323         }
1324
1325         if (use_loader) {
1326                 p_err("cannot use loader for subskeletons");
1327                 return -1;
1328         }
1329
1330         if (stat(file, &st)) {
1331                 p_err("failed to stat() %s: %s", file, strerror(errno));
1332                 return -1;
1333         }
1334         file_sz = st.st_size;
1335         mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
1336         fd = open(file, O_RDONLY);
1337         if (fd < 0) {
1338                 p_err("failed to open() %s: %s", file, strerror(errno));
1339                 return -1;
1340         }
1341         obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
1342         if (obj_data == MAP_FAILED) {
1343                 obj_data = NULL;
1344                 p_err("failed to mmap() %s: %s", file, strerror(errno));
1345                 goto out;
1346         }
1347         if (obj_name[0] == '\0')
1348                 get_obj_name(obj_name, file);
1349
1350         /* The empty object name allows us to use bpf_map__name and produce
1351          * ELF section names out of it. (".data" instead of "obj.data")
1352          */
1353         opts.object_name = "";
1354         obj = bpf_object__open_mem(obj_data, file_sz, &opts);
1355         if (!obj) {
1356                 char err_buf[256];
1357
1358                 libbpf_strerror(errno, err_buf, sizeof(err_buf));
1359                 p_err("failed to open BPF object file: %s", err_buf);
1360                 obj = NULL;
1361                 goto out;
1362         }
1363
1364         btf = bpf_object__btf(obj);
1365         if (!btf) {
1366                 err = -1;
1367                 p_err("need btf type information for %s", obj_name);
1368                 goto out;
1369         }
1370
1371         bpf_object__for_each_program(prog, obj) {
1372                 prog_cnt++;
1373         }
1374
1375         /* First, count how many variables we have to find.
1376          * We need this in advance so the subskel can allocate the right
1377          * amount of storage.
1378          */
1379         bpf_object__for_each_map(map, obj) {
1380                 if (!get_map_ident(map, ident, sizeof(ident)))
1381                         continue;
1382
1383                 /* Also count all maps that have a name */
1384                 map_cnt++;
1385
1386                 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
1387                         continue;
1388
1389                 map_type_id = bpf_map__btf_value_type_id(map);
1390                 if (map_type_id <= 0) {
1391                         err = map_type_id;
1392                         goto out;
1393                 }
1394                 map_type = btf__type_by_id(btf, map_type_id);
1395
1396                 var = btf_var_secinfos(map_type);
1397                 len = btf_vlen(map_type);
1398                 for (i = 0; i < len; i++, var++) {
1399                         var_type = btf__type_by_id(btf, var->type);
1400
1401                         if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
1402                                 continue;
1403
1404                         var_cnt++;
1405                 }
1406         }
1407
1408         get_header_guard(header_guard, obj_name, "SUBSKEL_H");
1409         codegen("\
1410         \n\
1411         /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */           \n\
1412                                                                             \n\
1413         /* THIS FILE IS AUTOGENERATED! */                                   \n\
1414         #ifndef %2$s                                                        \n\
1415         #define %2$s                                                        \n\
1416                                                                             \n\
1417         #include <errno.h>                                                  \n\
1418         #include <stdlib.h>                                                 \n\
1419         #include <bpf/libbpf.h>                                             \n\
1420                                                                             \n\
1421         struct %1$s {                                                       \n\
1422                 struct bpf_object *obj;                                     \n\
1423                 struct bpf_object_subskeleton *subskel;                     \n\
1424         ", obj_name, header_guard);
1425
1426         if (map_cnt) {
1427                 printf("\tstruct {\n");
1428                 bpf_object__for_each_map(map, obj) {
1429                         if (!get_map_ident(map, ident, sizeof(ident)))
1430                                 continue;
1431                         printf("\t\tstruct bpf_map *%s;\n", ident);
1432                 }
1433                 printf("\t} maps;\n");
1434         }
1435
1436         if (prog_cnt) {
1437                 printf("\tstruct {\n");
1438                 bpf_object__for_each_program(prog, obj) {
1439                         printf("\t\tstruct bpf_program *%s;\n",
1440                                 bpf_program__name(prog));
1441                 }
1442                 printf("\t} progs;\n");
1443         }
1444
1445         err = codegen_subskel_datasecs(obj, obj_name);
1446         if (err)
1447                 goto out;
1448
1449         /* emit code that will allocate enough storage for all symbols */
1450         codegen("\
1451                 \n\
1452                                                                             \n\
1453                 #ifdef __cplusplus                                          \n\
1454                         static inline struct %1$s *open(const struct bpf_object *src);\n\
1455                         static inline void destroy(struct %1$s *skel);      \n\
1456                 #endif /* __cplusplus */                                    \n\
1457                 };                                                          \n\
1458                                                                             \n\
1459                 static inline void                                          \n\
1460                 %1$s__destroy(struct %1$s *skel)                            \n\
1461                 {                                                           \n\
1462                         if (!skel)                                          \n\
1463                                 return;                                     \n\
1464                         if (skel->subskel)                                  \n\
1465                                 bpf_object__destroy_subskeleton(skel->subskel);\n\
1466                         free(skel);                                         \n\
1467                 }                                                           \n\
1468                                                                             \n\
1469                 static inline struct %1$s *                                 \n\
1470                 %1$s__open(const struct bpf_object *src)                    \n\
1471                 {                                                           \n\
1472                         struct %1$s *obj;                                   \n\
1473                         struct bpf_object_subskeleton *s;                   \n\
1474                         int err;                                            \n\
1475                                                                             \n\
1476                         obj = (struct %1$s *)calloc(1, sizeof(*obj));       \n\
1477                         if (!obj) {                                         \n\
1478                                 err = -ENOMEM;                              \n\
1479                                 goto err;                                   \n\
1480                         }                                                   \n\
1481                         s = (struct bpf_object_subskeleton *)calloc(1, sizeof(*s));\n\
1482                         if (!s) {                                           \n\
1483                                 err = -ENOMEM;                              \n\
1484                                 goto err;                                   \n\
1485                         }                                                   \n\
1486                         s->sz = sizeof(*s);                                 \n\
1487                         s->obj = src;                                       \n\
1488                         s->var_skel_sz = sizeof(*s->vars);                  \n\
1489                         obj->subskel = s;                                   \n\
1490                                                                             \n\
1491                         /* vars */                                          \n\
1492                         s->var_cnt = %2$d;                                  \n\
1493                         s->vars = (struct bpf_var_skeleton *)calloc(%2$d, sizeof(*s->vars));\n\
1494                         if (!s->vars) {                                     \n\
1495                                 err = -ENOMEM;                              \n\
1496                                 goto err;                                   \n\
1497                         }                                                   \n\
1498                 ",
1499                 obj_name, var_cnt
1500         );
1501
1502         /* walk through each symbol and emit the runtime representation */
1503         bpf_object__for_each_map(map, obj) {
1504                 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
1505                         continue;
1506
1507                 map_type_id = bpf_map__btf_value_type_id(map);
1508                 if (map_type_id <= 0)
1509                         /* skip over internal maps with no type*/
1510                         continue;
1511
1512                 map_type = btf__type_by_id(btf, map_type_id);
1513                 var = btf_var_secinfos(map_type);
1514                 len = btf_vlen(map_type);
1515                 for (i = 0; i < len; i++, var++) {
1516                         var_type = btf__type_by_id(btf, var->type);
1517                         var_name = btf__name_by_offset(btf, var_type->name_off);
1518
1519                         if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
1520                                 continue;
1521
1522                         /* Note that we use the dot prefix in .data as the
1523                          * field access operator i.e. maps%s becomes maps.data
1524                          */
1525                         codegen("\
1526                         \n\
1527                                                                             \n\
1528                                 s->vars[%3$d].name = \"%1$s\";              \n\
1529                                 s->vars[%3$d].map = &obj->maps.%2$s;        \n\
1530                                 s->vars[%3$d].addr = (void **) &obj->%2$s.%1$s;\n\
1531                         ", var_name, ident, var_idx);
1532
1533                         var_idx++;
1534                 }
1535         }
1536
1537         codegen_maps_skeleton(obj, map_cnt, false /*mmaped*/);
1538         codegen_progs_skeleton(obj, prog_cnt, false /*links*/);
1539
1540         codegen("\
1541                 \n\
1542                                                                             \n\
1543                         err = bpf_object__open_subskeleton(s);              \n\
1544                         if (err)                                            \n\
1545                                 goto err;                                   \n\
1546                                                                             \n\
1547                         return obj;                                         \n\
1548                 err:                                                        \n\
1549                         %1$s__destroy(obj);                                 \n\
1550                         errno = -err;                                       \n\
1551                         return NULL;                                        \n\
1552                 }                                                           \n\
1553                                                                             \n\
1554                 #ifdef __cplusplus                                          \n\
1555                 struct %1$s *%1$s::open(const struct bpf_object *src) { return %1$s__open(src); }\n\
1556                 void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); }\n\
1557                 #endif /* __cplusplus */                                    \n\
1558                                                                             \n\
1559                 #endif /* %2$s */                                           \n\
1560                 ",
1561                 obj_name, header_guard);
1562         err = 0;
1563 out:
1564         bpf_object__close(obj);
1565         if (obj_data)
1566                 munmap(obj_data, mmap_sz);
1567         close(fd);
1568         return err;
1569 }
1570
1571 static int do_object(int argc, char **argv)
1572 {
1573         struct bpf_linker *linker;
1574         const char *output_file, *file;
1575         int err = 0;
1576
1577         if (!REQ_ARGS(2)) {
1578                 usage();
1579                 return -1;
1580         }
1581
1582         output_file = GET_ARG();
1583
1584         linker = bpf_linker__new(output_file, NULL);
1585         if (!linker) {
1586                 p_err("failed to create BPF linker instance");
1587                 return -1;
1588         }
1589
1590         while (argc) {
1591                 file = GET_ARG();
1592
1593                 err = bpf_linker__add_file(linker, file, NULL);
1594                 if (err) {
1595                         p_err("failed to link '%s': %s (%d)", file, strerror(errno), errno);
1596                         goto out;
1597                 }
1598         }
1599
1600         err = bpf_linker__finalize(linker);
1601         if (err) {
1602                 p_err("failed to finalize ELF file: %s (%d)", strerror(errno), errno);
1603                 goto out;
1604         }
1605
1606         err = 0;
1607 out:
1608         bpf_linker__free(linker);
1609         return err;
1610 }
1611
1612 static int do_help(int argc, char **argv)
1613 {
1614         if (json_output) {
1615                 jsonw_null(json_wtr);
1616                 return 0;
1617         }
1618
1619         fprintf(stderr,
1620                 "Usage: %1$s %2$s object OUTPUT_FILE INPUT_FILE [INPUT_FILE...]\n"
1621                 "       %1$s %2$s skeleton FILE [name OBJECT_NAME]\n"
1622                 "       %1$s %2$s subskeleton FILE [name OBJECT_NAME]\n"
1623                 "       %1$s %2$s min_core_btf INPUT OUTPUT OBJECT [OBJECT...]\n"
1624                 "       %1$s %2$s help\n"
1625                 "\n"
1626                 "       " HELP_SPEC_OPTIONS " |\n"
1627                 "                    {-L|--use-loader} }\n"
1628                 "",
1629                 bin_name, "gen");
1630
1631         return 0;
1632 }
1633
1634 static int btf_save_raw(const struct btf *btf, const char *path)
1635 {
1636         const void *data;
1637         FILE *f = NULL;
1638         __u32 data_sz;
1639         int err = 0;
1640
1641         data = btf__raw_data(btf, &data_sz);
1642         if (!data)
1643                 return -ENOMEM;
1644
1645         f = fopen(path, "wb");
1646         if (!f)
1647                 return -errno;
1648
1649         if (fwrite(data, 1, data_sz, f) != data_sz)
1650                 err = -errno;
1651
1652         fclose(f);
1653         return err;
1654 }
1655
1656 struct btfgen_info {
1657         struct btf *src_btf;
1658         struct btf *marked_btf; /* btf structure used to mark used types */
1659 };
1660
1661 static size_t btfgen_hash_fn(long key, void *ctx)
1662 {
1663         return key;
1664 }
1665
1666 static bool btfgen_equal_fn(long k1, long k2, void *ctx)
1667 {
1668         return k1 == k2;
1669 }
1670
1671 static void btfgen_free_info(struct btfgen_info *info)
1672 {
1673         if (!info)
1674                 return;
1675
1676         btf__free(info->src_btf);
1677         btf__free(info->marked_btf);
1678
1679         free(info);
1680 }
1681
1682 static struct btfgen_info *
1683 btfgen_new_info(const char *targ_btf_path)
1684 {
1685         struct btfgen_info *info;
1686         int err;
1687
1688         info = calloc(1, sizeof(*info));
1689         if (!info)
1690                 return NULL;
1691
1692         info->src_btf = btf__parse(targ_btf_path, NULL);
1693         if (!info->src_btf) {
1694                 err = -errno;
1695                 p_err("failed parsing '%s' BTF file: %s", targ_btf_path, strerror(errno));
1696                 goto err_out;
1697         }
1698
1699         info->marked_btf = btf__parse(targ_btf_path, NULL);
1700         if (!info->marked_btf) {
1701                 err = -errno;
1702                 p_err("failed parsing '%s' BTF file: %s", targ_btf_path, strerror(errno));
1703                 goto err_out;
1704         }
1705
1706         return info;
1707
1708 err_out:
1709         btfgen_free_info(info);
1710         errno = -err;
1711         return NULL;
1712 }
1713
1714 #define MARKED UINT32_MAX
1715
1716 static void btfgen_mark_member(struct btfgen_info *info, int type_id, int idx)
1717 {
1718         const struct btf_type *t = btf__type_by_id(info->marked_btf, type_id);
1719         struct btf_member *m = btf_members(t) + idx;
1720
1721         m->name_off = MARKED;
1722 }
1723
1724 static int
1725 btfgen_mark_type(struct btfgen_info *info, unsigned int type_id, bool follow_pointers)
1726 {
1727         const struct btf_type *btf_type = btf__type_by_id(info->src_btf, type_id);
1728         struct btf_type *cloned_type;
1729         struct btf_param *param;
1730         struct btf_array *array;
1731         int err, i;
1732
1733         if (type_id == 0)
1734                 return 0;
1735
1736         /* mark type on cloned BTF as used */
1737         cloned_type = (struct btf_type *) btf__type_by_id(info->marked_btf, type_id);
1738         cloned_type->name_off = MARKED;
1739
1740         /* recursively mark other types needed by it */
1741         switch (btf_kind(btf_type)) {
1742         case BTF_KIND_UNKN:
1743         case BTF_KIND_INT:
1744         case BTF_KIND_FLOAT:
1745         case BTF_KIND_ENUM:
1746         case BTF_KIND_ENUM64:
1747         case BTF_KIND_STRUCT:
1748         case BTF_KIND_UNION:
1749                 break;
1750         case BTF_KIND_PTR:
1751                 if (follow_pointers) {
1752                         err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1753                         if (err)
1754                                 return err;
1755                 }
1756                 break;
1757         case BTF_KIND_CONST:
1758         case BTF_KIND_RESTRICT:
1759         case BTF_KIND_VOLATILE:
1760         case BTF_KIND_TYPEDEF:
1761                 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1762                 if (err)
1763                         return err;
1764                 break;
1765         case BTF_KIND_ARRAY:
1766                 array = btf_array(btf_type);
1767
1768                 /* mark array type */
1769                 err = btfgen_mark_type(info, array->type, follow_pointers);
1770                 /* mark array's index type */
1771                 err = err ? : btfgen_mark_type(info, array->index_type, follow_pointers);
1772                 if (err)
1773                         return err;
1774                 break;
1775         case BTF_KIND_FUNC_PROTO:
1776                 /* mark ret type */
1777                 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1778                 if (err)
1779                         return err;
1780
1781                 /* mark parameters types */
1782                 param = btf_params(btf_type);
1783                 for (i = 0; i < btf_vlen(btf_type); i++) {
1784                         err = btfgen_mark_type(info, param->type, follow_pointers);
1785                         if (err)
1786                                 return err;
1787                         param++;
1788                 }
1789                 break;
1790         /* tells if some other type needs to be handled */
1791         default:
1792                 p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
1793                 return -EINVAL;
1794         }
1795
1796         return 0;
1797 }
1798
1799 static int btfgen_record_field_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1800 {
1801         struct btf *btf = info->src_btf;
1802         const struct btf_type *btf_type;
1803         struct btf_member *btf_member;
1804         struct btf_array *array;
1805         unsigned int type_id = targ_spec->root_type_id;
1806         int idx, err;
1807
1808         /* mark root type */
1809         btf_type = btf__type_by_id(btf, type_id);
1810         err = btfgen_mark_type(info, type_id, false);
1811         if (err)
1812                 return err;
1813
1814         /* mark types for complex types (arrays, unions, structures) */
1815         for (int i = 1; i < targ_spec->raw_len; i++) {
1816                 /* skip typedefs and mods */
1817                 while (btf_is_mod(btf_type) || btf_is_typedef(btf_type)) {
1818                         type_id = btf_type->type;
1819                         btf_type = btf__type_by_id(btf, type_id);
1820                 }
1821
1822                 switch (btf_kind(btf_type)) {
1823                 case BTF_KIND_STRUCT:
1824                 case BTF_KIND_UNION:
1825                         idx = targ_spec->raw_spec[i];
1826                         btf_member = btf_members(btf_type) + idx;
1827
1828                         /* mark member */
1829                         btfgen_mark_member(info, type_id, idx);
1830
1831                         /* mark member's type */
1832                         type_id = btf_member->type;
1833                         btf_type = btf__type_by_id(btf, type_id);
1834                         err = btfgen_mark_type(info, type_id, false);
1835                         if (err)
1836                                 return err;
1837                         break;
1838                 case BTF_KIND_ARRAY:
1839                         array = btf_array(btf_type);
1840                         type_id = array->type;
1841                         btf_type = btf__type_by_id(btf, type_id);
1842                         break;
1843                 default:
1844                         p_err("unsupported kind: %s (%d)",
1845                               btf_kind_str(btf_type), btf_type->type);
1846                         return -EINVAL;
1847                 }
1848         }
1849
1850         return 0;
1851 }
1852
1853 /* Mark types, members, and member types. Compared to btfgen_record_field_relo,
1854  * this function does not rely on the target spec for inferring members, but
1855  * uses the associated BTF.
1856  *
1857  * The `behind_ptr` argument is used to stop marking of composite types reached
1858  * through a pointer. This way, we can keep BTF size in check while providing
1859  * reasonable match semantics.
1860  */
1861 static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool behind_ptr)
1862 {
1863         const struct btf_type *btf_type;
1864         struct btf *btf = info->src_btf;
1865         struct btf_type *cloned_type;
1866         int i, err;
1867
1868         if (type_id == 0)
1869                 return 0;
1870
1871         btf_type = btf__type_by_id(btf, type_id);
1872         /* mark type on cloned BTF as used */
1873         cloned_type = (struct btf_type *)btf__type_by_id(info->marked_btf, type_id);
1874         cloned_type->name_off = MARKED;
1875
1876         switch (btf_kind(btf_type)) {
1877         case BTF_KIND_UNKN:
1878         case BTF_KIND_INT:
1879         case BTF_KIND_FLOAT:
1880         case BTF_KIND_ENUM:
1881         case BTF_KIND_ENUM64:
1882                 break;
1883         case BTF_KIND_STRUCT:
1884         case BTF_KIND_UNION: {
1885                 struct btf_member *m = btf_members(btf_type);
1886                 __u16 vlen = btf_vlen(btf_type);
1887
1888                 if (behind_ptr)
1889                         break;
1890
1891                 for (i = 0; i < vlen; i++, m++) {
1892                         /* mark member */
1893                         btfgen_mark_member(info, type_id, i);
1894
1895                         /* mark member's type */
1896                         err = btfgen_mark_type_match(info, m->type, false);
1897                         if (err)
1898                                 return err;
1899                 }
1900                 break;
1901         }
1902         case BTF_KIND_CONST:
1903         case BTF_KIND_FWD:
1904         case BTF_KIND_RESTRICT:
1905         case BTF_KIND_TYPEDEF:
1906         case BTF_KIND_VOLATILE:
1907                 return btfgen_mark_type_match(info, btf_type->type, behind_ptr);
1908         case BTF_KIND_PTR:
1909                 return btfgen_mark_type_match(info, btf_type->type, true);
1910         case BTF_KIND_ARRAY: {
1911                 struct btf_array *array;
1912
1913                 array = btf_array(btf_type);
1914                 /* mark array type */
1915                 err = btfgen_mark_type_match(info, array->type, false);
1916                 /* mark array's index type */
1917                 err = err ? : btfgen_mark_type_match(info, array->index_type, false);
1918                 if (err)
1919                         return err;
1920                 break;
1921         }
1922         case BTF_KIND_FUNC_PROTO: {
1923                 __u16 vlen = btf_vlen(btf_type);
1924                 struct btf_param *param;
1925
1926                 /* mark ret type */
1927                 err = btfgen_mark_type_match(info, btf_type->type, false);
1928                 if (err)
1929                         return err;
1930
1931                 /* mark parameters types */
1932                 param = btf_params(btf_type);
1933                 for (i = 0; i < vlen; i++) {
1934                         err = btfgen_mark_type_match(info, param->type, false);
1935                         if (err)
1936                                 return err;
1937                         param++;
1938                 }
1939                 break;
1940         }
1941         /* tells if some other type needs to be handled */
1942         default:
1943                 p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
1944                 return -EINVAL;
1945         }
1946
1947         return 0;
1948 }
1949
1950 /* Mark types, members, and member types. Compared to btfgen_record_field_relo,
1951  * this function does not rely on the target spec for inferring members, but
1952  * uses the associated BTF.
1953  */
1954 static int btfgen_record_type_match_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1955 {
1956         return btfgen_mark_type_match(info, targ_spec->root_type_id, false);
1957 }
1958
1959 static int btfgen_record_type_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1960 {
1961         return btfgen_mark_type(info, targ_spec->root_type_id, true);
1962 }
1963
1964 static int btfgen_record_enumval_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1965 {
1966         return btfgen_mark_type(info, targ_spec->root_type_id, false);
1967 }
1968
1969 static int btfgen_record_reloc(struct btfgen_info *info, struct bpf_core_spec *res)
1970 {
1971         switch (res->relo_kind) {
1972         case BPF_CORE_FIELD_BYTE_OFFSET:
1973         case BPF_CORE_FIELD_BYTE_SIZE:
1974         case BPF_CORE_FIELD_EXISTS:
1975         case BPF_CORE_FIELD_SIGNED:
1976         case BPF_CORE_FIELD_LSHIFT_U64:
1977         case BPF_CORE_FIELD_RSHIFT_U64:
1978                 return btfgen_record_field_relo(info, res);
1979         case BPF_CORE_TYPE_ID_LOCAL: /* BPF_CORE_TYPE_ID_LOCAL doesn't require kernel BTF */
1980                 return 0;
1981         case BPF_CORE_TYPE_ID_TARGET:
1982         case BPF_CORE_TYPE_EXISTS:
1983         case BPF_CORE_TYPE_SIZE:
1984                 return btfgen_record_type_relo(info, res);
1985         case BPF_CORE_TYPE_MATCHES:
1986                 return btfgen_record_type_match_relo(info, res);
1987         case BPF_CORE_ENUMVAL_EXISTS:
1988         case BPF_CORE_ENUMVAL_VALUE:
1989                 return btfgen_record_enumval_relo(info, res);
1990         default:
1991                 return -EINVAL;
1992         }
1993 }
1994
1995 static struct bpf_core_cand_list *
1996 btfgen_find_cands(const struct btf *local_btf, const struct btf *targ_btf, __u32 local_id)
1997 {
1998         const struct btf_type *local_type;
1999         struct bpf_core_cand_list *cands = NULL;
2000         struct bpf_core_cand local_cand = {};
2001         size_t local_essent_len;
2002         const char *local_name;
2003         int err;
2004
2005         local_cand.btf = local_btf;
2006         local_cand.id = local_id;
2007
2008         local_type = btf__type_by_id(local_btf, local_id);
2009         if (!local_type) {
2010                 err = -EINVAL;
2011                 goto err_out;
2012         }
2013
2014         local_name = btf__name_by_offset(local_btf, local_type->name_off);
2015         if (!local_name) {
2016                 err = -EINVAL;
2017                 goto err_out;
2018         }
2019         local_essent_len = bpf_core_essential_name_len(local_name);
2020
2021         cands = calloc(1, sizeof(*cands));
2022         if (!cands)
2023                 return NULL;
2024
2025         err = bpf_core_add_cands(&local_cand, local_essent_len, targ_btf, "vmlinux", 1, cands);
2026         if (err)
2027                 goto err_out;
2028
2029         return cands;
2030
2031 err_out:
2032         bpf_core_free_cands(cands);
2033         errno = -err;
2034         return NULL;
2035 }
2036
2037 /* Record relocation information for a single BPF object */
2038 static int btfgen_record_obj(struct btfgen_info *info, const char *obj_path)
2039 {
2040         const struct btf_ext_info_sec *sec;
2041         const struct bpf_core_relo *relo;
2042         const struct btf_ext_info *seg;
2043         struct hashmap_entry *entry;
2044         struct hashmap *cand_cache = NULL;
2045         struct btf_ext *btf_ext = NULL;
2046         unsigned int relo_idx;
2047         struct btf *btf = NULL;
2048         size_t i;
2049         int err;
2050
2051         btf = btf__parse(obj_path, &btf_ext);
2052         if (!btf) {
2053                 err = -errno;
2054                 p_err("failed to parse BPF object '%s': %s", obj_path, strerror(errno));
2055                 return err;
2056         }
2057
2058         if (!btf_ext) {
2059                 p_err("failed to parse BPF object '%s': section %s not found",
2060                       obj_path, BTF_EXT_ELF_SEC);
2061                 err = -EINVAL;
2062                 goto out;
2063         }
2064
2065         if (btf_ext->core_relo_info.len == 0) {
2066                 err = 0;
2067                 goto out;
2068         }
2069
2070         cand_cache = hashmap__new(btfgen_hash_fn, btfgen_equal_fn, NULL);
2071         if (IS_ERR(cand_cache)) {
2072                 err = PTR_ERR(cand_cache);
2073                 goto out;
2074         }
2075
2076         seg = &btf_ext->core_relo_info;
2077         for_each_btf_ext_sec(seg, sec) {
2078                 for_each_btf_ext_rec(seg, sec, relo_idx, relo) {
2079                         struct bpf_core_spec specs_scratch[3] = {};
2080                         struct bpf_core_relo_res targ_res = {};
2081                         struct bpf_core_cand_list *cands = NULL;
2082                         const char *sec_name = btf__name_by_offset(btf, sec->sec_name_off);
2083
2084                         if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
2085                             !hashmap__find(cand_cache, relo->type_id, &cands)) {
2086                                 cands = btfgen_find_cands(btf, info->src_btf, relo->type_id);
2087                                 if (!cands) {
2088                                         err = -errno;
2089                                         goto out;
2090                                 }
2091
2092                                 err = hashmap__set(cand_cache, relo->type_id, cands,
2093                                                    NULL, NULL);
2094                                 if (err)
2095                                         goto out;
2096                         }
2097
2098                         err = bpf_core_calc_relo_insn(sec_name, relo, relo_idx, btf, cands,
2099                                                       specs_scratch, &targ_res);
2100                         if (err)
2101                                 goto out;
2102
2103                         /* specs_scratch[2] is the target spec */
2104                         err = btfgen_record_reloc(info, &specs_scratch[2]);
2105                         if (err)
2106                                 goto out;
2107                 }
2108         }
2109
2110 out:
2111         btf__free(btf);
2112         btf_ext__free(btf_ext);
2113
2114         if (!IS_ERR_OR_NULL(cand_cache)) {
2115                 hashmap__for_each_entry(cand_cache, entry, i) {
2116                         bpf_core_free_cands(entry->pvalue);
2117                 }
2118                 hashmap__free(cand_cache);
2119         }
2120
2121         return err;
2122 }
2123
2124 static int btfgen_remap_id(__u32 *type_id, void *ctx)
2125 {
2126         unsigned int *ids = ctx;
2127
2128         *type_id = ids[*type_id];
2129
2130         return 0;
2131 }
2132
2133 /* Generate BTF from relocation information previously recorded */
2134 static struct btf *btfgen_get_btf(struct btfgen_info *info)
2135 {
2136         struct btf *btf_new = NULL;
2137         unsigned int *ids = NULL;
2138         unsigned int i, n = btf__type_cnt(info->marked_btf);
2139         int err = 0;
2140
2141         btf_new = btf__new_empty();
2142         if (!btf_new) {
2143                 err = -errno;
2144                 goto err_out;
2145         }
2146
2147         ids = calloc(n, sizeof(*ids));
2148         if (!ids) {
2149                 err = -errno;
2150                 goto err_out;
2151         }
2152
2153         /* first pass: add all marked types to btf_new and add their new ids to the ids map */
2154         for (i = 1; i < n; i++) {
2155                 const struct btf_type *cloned_type, *type;
2156                 const char *name;
2157                 int new_id;
2158
2159                 cloned_type = btf__type_by_id(info->marked_btf, i);
2160
2161                 if (cloned_type->name_off != MARKED)
2162                         continue;
2163
2164                 type = btf__type_by_id(info->src_btf, i);
2165
2166                 /* add members for struct and union */
2167                 if (btf_is_composite(type)) {
2168                         struct btf_member *cloned_m, *m;
2169                         unsigned short vlen;
2170                         int idx_src;
2171
2172                         name = btf__str_by_offset(info->src_btf, type->name_off);
2173
2174                         if (btf_is_struct(type))
2175                                 err = btf__add_struct(btf_new, name, type->size);
2176                         else
2177                                 err = btf__add_union(btf_new, name, type->size);
2178
2179                         if (err < 0)
2180                                 goto err_out;
2181                         new_id = err;
2182
2183                         cloned_m = btf_members(cloned_type);
2184                         m = btf_members(type);
2185                         vlen = btf_vlen(cloned_type);
2186                         for (idx_src = 0; idx_src < vlen; idx_src++, cloned_m++, m++) {
2187                                 /* add only members that are marked as used */
2188                                 if (cloned_m->name_off != MARKED)
2189                                         continue;
2190
2191                                 name = btf__str_by_offset(info->src_btf, m->name_off);
2192                                 err = btf__add_field(btf_new, name, m->type,
2193                                                      btf_member_bit_offset(cloned_type, idx_src),
2194                                                      btf_member_bitfield_size(cloned_type, idx_src));
2195                                 if (err < 0)
2196                                         goto err_out;
2197                         }
2198                 } else {
2199                         err = btf__add_type(btf_new, info->src_btf, type);
2200                         if (err < 0)
2201                                 goto err_out;
2202                         new_id = err;
2203                 }
2204
2205                 /* add ID mapping */
2206                 ids[i] = new_id;
2207         }
2208
2209         /* second pass: fix up type ids */
2210         for (i = 1; i < btf__type_cnt(btf_new); i++) {
2211                 struct btf_type *btf_type = (struct btf_type *) btf__type_by_id(btf_new, i);
2212
2213                 err = btf_type_visit_type_ids(btf_type, btfgen_remap_id, ids);
2214                 if (err)
2215                         goto err_out;
2216         }
2217
2218         free(ids);
2219         return btf_new;
2220
2221 err_out:
2222         btf__free(btf_new);
2223         free(ids);
2224         errno = -err;
2225         return NULL;
2226 }
2227
2228 /* Create minimized BTF file for a set of BPF objects.
2229  *
2230  * The BTFGen algorithm is divided in two main parts: (1) collect the
2231  * BTF types that are involved in relocations and (2) generate the BTF
2232  * object using the collected types.
2233  *
2234  * In order to collect the types involved in the relocations, we parse
2235  * the BTF and BTF.ext sections of the BPF objects and use
2236  * bpf_core_calc_relo_insn() to get the target specification, this
2237  * indicates how the types and fields are used in a relocation.
2238  *
2239  * Types are recorded in different ways according to the kind of the
2240  * relocation. For field-based relocations only the members that are
2241  * actually used are saved in order to reduce the size of the generated
2242  * BTF file. For type-based relocations empty struct / unions are
2243  * generated and for enum-based relocations the whole type is saved.
2244  *
2245  * The second part of the algorithm generates the BTF object. It creates
2246  * an empty BTF object and fills it with the types recorded in the
2247  * previous step. This function takes care of only adding the structure
2248  * and union members that were marked as used and it also fixes up the
2249  * type IDs on the generated BTF object.
2250  */
2251 static int minimize_btf(const char *src_btf, const char *dst_btf, const char *objspaths[])
2252 {
2253         struct btfgen_info *info;
2254         struct btf *btf_new = NULL;
2255         int err, i;
2256
2257         info = btfgen_new_info(src_btf);
2258         if (!info) {
2259                 err = -errno;
2260                 p_err("failed to allocate info structure: %s", strerror(errno));
2261                 goto out;
2262         }
2263
2264         for (i = 0; objspaths[i] != NULL; i++) {
2265                 err = btfgen_record_obj(info, objspaths[i]);
2266                 if (err) {
2267                         p_err("error recording relocations for %s: %s", objspaths[i],
2268                               strerror(errno));
2269                         goto out;
2270                 }
2271         }
2272
2273         btf_new = btfgen_get_btf(info);
2274         if (!btf_new) {
2275                 err = -errno;
2276                 p_err("error generating BTF: %s", strerror(errno));
2277                 goto out;
2278         }
2279
2280         err = btf_save_raw(btf_new, dst_btf);
2281         if (err) {
2282                 p_err("error saving btf file: %s", strerror(errno));
2283                 goto out;
2284         }
2285
2286 out:
2287         btf__free(btf_new);
2288         btfgen_free_info(info);
2289
2290         return err;
2291 }
2292
2293 static int do_min_core_btf(int argc, char **argv)
2294 {
2295         const char *input, *output, **objs;
2296         int i, err;
2297
2298         if (!REQ_ARGS(3)) {
2299                 usage();
2300                 return -1;
2301         }
2302
2303         input = GET_ARG();
2304         output = GET_ARG();
2305
2306         objs = (const char **) calloc(argc + 1, sizeof(*objs));
2307         if (!objs) {
2308                 p_err("failed to allocate array for object names");
2309                 return -ENOMEM;
2310         }
2311
2312         i = 0;
2313         while (argc)
2314                 objs[i++] = GET_ARG();
2315
2316         err = minimize_btf(input, output, objs);
2317         free(objs);
2318         return err;
2319 }
2320
2321 static const struct cmd cmds[] = {
2322         { "object",             do_object },
2323         { "skeleton",           do_skeleton },
2324         { "subskeleton",        do_subskeleton },
2325         { "min_core_btf",       do_min_core_btf},
2326         { "help",               do_help },
2327         { 0 }
2328 };
2329
2330 int do_gen(int argc, char **argv)
2331 {
2332         return cmd_select(cmds, argc, argv, do_help);
2333 }