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         err = libbpf_get_error(d);
 256         if (err)
 257                 return err;
 258
 259         bpf_object__for_each_map(map, obj) {
 260                 /* only generate definitions for memory-mapped internal maps */
 261                 if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
 262                         continue;
 263
 264                 sec = find_type_for_map(btf, map_ident);
 265
 266                 /* In some cases (e.g., sections like .rodata.cst16 containing
 267                  * compiler allocated string constants only) there will be
 268                  * special internal maps with no corresponding DATASEC BTF
 269                  * type. In such case, generate empty structs for each such
 270                  * map. It will still be memory-mapped and its contents
 271                  * accessible from user-space through BPF skeleton.
 272                  */
 273                 if (!sec) {
 274                         printf("        struct %s__%s {\n", obj_name, map_ident);
 275                         printf("        } *%s;\n", map_ident);
 276                 } else {
 277                         err = codegen_datasec_def(obj, btf, d, sec, obj_name);
 278                         if (err)
 279                                 goto out;
 280                 }
 281         }
 282
 283
 284 out:
 285         btf_dump__free(d);
 286         return err;
 287 }
 288
 289 static bool btf_is_ptr_to_func_proto(const struct btf *btf,
 290                                      const struct btf_type *v)
 291 {
 292         return btf_is_ptr(v) && btf_is_func_proto(btf__type_by_id(btf, v->type));
 293 }
 294
 295 static int codegen_subskel_datasecs(struct bpf_object *obj, const char *obj_name)
 296 {
 297         struct btf *btf = bpf_object__btf(obj);
 298         struct btf_dump *d;
 299         struct bpf_map *map;
 300         const struct btf_type *sec, *var;
 301         const struct btf_var_secinfo *sec_var;
 302         int i, err = 0, vlen;
 303         char map_ident[256], sec_ident[256];
 304         bool strip_mods = false, needs_typeof = false;
 305         const char *sec_name, *var_name;
 306         __u32 var_type_id;
 307
 308         d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
 309         if (!d)
 310                 return -errno;
 311
 312         bpf_object__for_each_map(map, obj) {
 313                 /* only generate definitions for memory-mapped internal maps */
 314                 if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
 315                         continue;
 316
 317                 sec = find_type_for_map(btf, map_ident);
 318                 if (!sec)
 319                         continue;
 320
 321                 sec_name = btf__name_by_offset(btf, sec->name_off);
 322                 if (!get_datasec_ident(sec_name, sec_ident, sizeof(sec_ident)))
 323                         continue;
 324
 325                 strip_mods = strcmp(sec_name, ".kconfig") != 0;
 326                 printf("        struct %s__%s {\n", obj_name, sec_ident);
 327
 328                 sec_var = btf_var_secinfos(sec);
 329                 vlen = btf_vlen(sec);
 330                 for (i = 0; i < vlen; i++, sec_var++) {
 331                         DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
 332                                 .indent_level = 2,
 333                                 .strip_mods = strip_mods,
 334                                 /* we'll print the name separately */
 335                                 .field_name = "",
 336                         );
 337
 338                         var = btf__type_by_id(btf, sec_var->type);
 339                         var_name = btf__name_by_offset(btf, var->name_off);
 340                         var_type_id = var->type;
 341
 342                         /* static variables are not exposed through BPF skeleton */
 343                         if (btf_var(var)->linkage == BTF_VAR_STATIC)
 344                                 continue;
 345
 346                         /* The datasec member has KIND_VAR but we want the
 347                          * underlying type of the variable (e.g. KIND_INT).
 348                          */
 349                         var = skip_mods_and_typedefs(btf, var->type, NULL);
 350
 351                         printf("\t\t");
 352                         /* Func and array members require special handling.
 353                          * Instead of producing `typename *var`, they produce
 354                          * `typeof(typename) *var`. This allows us to keep a
 355                          * similar syntax where the identifier is just prefixed
 356                          * by *, allowing us to ignore C declaration minutiae.
 357                          */
 358                         needs_typeof = btf_is_array(var) || btf_is_ptr_to_func_proto(btf, var);
 359                         if (needs_typeof)
 360                                 printf("typeof(");
 361
 362                         err = btf_dump__emit_type_decl(d, var_type_id, &opts);
 363                         if (err)
 364                                 goto out;
 365
 366                         if (needs_typeof)
 367                                 printf(")");
 368
 369                         printf(" *%s;\n", var_name);
 370                 }
 371                 printf("        } %s;\n", sec_ident);
 372         }
 373
 374 out:
 375         btf_dump__free(d);
 376         return err;
 377 }
 378
 379 static void codegen(const char *template, ...)
 380 {
 381         const char *src, *end;
 382         int skip_tabs = 0, n;
 383         char *s, *dst;
 384         va_list args;
 385         char c;
 386
 387         n = strlen(template);
 388         s = malloc(n + 1);
 389         if (!s)
 390                 exit(-1);
 391         src = template;
 392         dst = s;
 393
 394         /* find out "baseline" indentation to skip */
 395         while ((c = *src++)) {
 396                 if (c == '\t') {
 397                         skip_tabs++;
 398                 } else if (c == '\n') {
 399                         break;
 400                 } else {
 401                         p_err("unrecognized character at pos %td in template '%s': '%c'",
 402                               src - template - 1, template, c);
 403                         free(s);
 404                         exit(-1);
 405                 }
 406         }
 407
 408         while (*src) {
 409                 /* skip baseline indentation tabs */
 410                 for (n = skip_tabs; n > 0; n--, src++) {
 411                         if (*src != '\t') {
 412                                 p_err("not enough tabs at pos %td in template '%s'",
 413                                       src - template - 1, template);
 414                                 free(s);
 415                                 exit(-1);
 416                         }
 417                 }
 418                 /* trim trailing whitespace */
 419                 end = strchrnul(src, '\n');
 420                 for (n = end - src; n > 0 && isspace(src[n - 1]); n--)
 421                         ;
 422                 memcpy(dst, src, n);
 423                 dst += n;
 424                 if (*end)
 425                         *dst++ = '\n';
 426                 src = *end ? end + 1 : end;
 427         }
 428         *dst++ = '\0';
 429
 430         /* print out using adjusted template */
 431         va_start(args, template);
 432         n = vprintf(s, args);
 433         va_end(args);
 434
 435         free(s);
 436 }
 437
 438 static void print_hex(const char *data, int data_sz)
 439 {
 440         int i, len;
 441
 442         for (i = 0, len = 0; i < data_sz; i++) {
 443                 int w = data[i] ? 4 : 2;
 444
 445                 len += w;
 446                 if (len > 78) {
 447                         printf("\\\n");
 448                         len = w;
 449                 }
 450                 if (!data[i])
 451                         printf("\\0");
 452                 else
 453                         printf("\\x%02x", (unsigned char)data[i]);
 454         }
 455 }
 456
 457 static size_t bpf_map_mmap_sz(const struct bpf_map *map)
 458 {
 459         long page_sz = sysconf(_SC_PAGE_SIZE);
 460         size_t map_sz;
 461
 462         map_sz = (size_t)roundup(bpf_map__value_size(map), 8) * bpf_map__max_entries(map);
 463         map_sz = roundup(map_sz, page_sz);
 464         return map_sz;
 465 }
 466
 467 /* Emit type size asserts for all top-level fields in memory-mapped internal maps. */
 468 static void codegen_asserts(struct bpf_object *obj, const char *obj_name)
 469 {
 470         struct btf *btf = bpf_object__btf(obj);
 471         struct bpf_map *map;
 472         struct btf_var_secinfo *sec_var;
 473         int i, vlen;
 474         const struct btf_type *sec;
 475         char map_ident[256], var_ident[256];
 476
 477         if (!btf)
 478                 return;
 479
 480         codegen("\
 481                 \n\
 482                 __attribute__((unused)) static void                         \n\
 483                 %1$s__assert(struct %1$s *s __attribute__((unused)))        \n\
 484                 {                                                           \n\
 485                 #ifdef __cplusplus                                          \n\
 486                 #define _Static_assert static_assert                        \n\
 487                 #endif                                                      \n\
 488                 ", obj_name);
 489
 490         bpf_object__for_each_map(map, obj) {
 491                 if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
 492                         continue;
 493
 494                 sec = find_type_for_map(btf, map_ident);
 495                 if (!sec) {
 496                         /* best effort, couldn't find the type for this map */
 497                         continue;
 498                 }
 499
 500                 sec_var = btf_var_secinfos(sec);
 501                 vlen =  btf_vlen(sec);
 502
 503                 for (i = 0; i < vlen; i++, sec_var++) {
 504                         const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
 505                         const char *var_name = btf__name_by_offset(btf, var->name_off);
 506                         long var_size;
 507
 508                         /* static variables are not exposed through BPF skeleton */
 509                         if (btf_var(var)->linkage == BTF_VAR_STATIC)
 510                                 continue;
 511
 512                         var_size = btf__resolve_size(btf, var->type);
 513                         if (var_size < 0)
 514                                 continue;
 515
 516                         var_ident[0] = '\0';
 517                         strncat(var_ident, var_name, sizeof(var_ident) - 1);
 518                         sanitize_identifier(var_ident);
 519
 520                         printf("\t_Static_assert(sizeof(s->%s->%s) == %ld, \"unexpected size of '%s'\");\n",
 521                                map_ident, var_ident, var_size, var_ident);
 522                 }
 523         }
 524         codegen("\
 525                 \n\
 526                 #ifdef __cplusplus                                          \n\
 527                 #undef _Static_assert                                       \n\
 528                 #endif                                                      \n\
 529                 }                                                           \n\
 530                 ");
 531 }
 532
 533 static void codegen_attach_detach(struct bpf_object *obj, const char *obj_name)
 534 {
 535         struct bpf_program *prog;
 536
 537         bpf_object__for_each_program(prog, obj) {
 538                 const char *tp_name;
 539
 540                 codegen("\
 541                         \n\
 542                         \n\
 543                         static inline int                                           \n\
 544                         %1$s__%2$s__attach(struct %1$s *skel)                       \n\
 545                         {                                                           \n\
 546                                 int prog_fd = skel->progs.%2$s.prog_fd;             \n\
 547                         ", obj_name, bpf_program__name(prog));
 548
 549                 switch (bpf_program__type(prog)) {
 550                 case BPF_PROG_TYPE_RAW_TRACEPOINT:
 551                         tp_name = strchr(bpf_program__section_name(prog), '/') + 1;
 552                         printf("\tint fd = skel_raw_tracepoint_open(\"%s\", prog_fd);\n", tp_name);
 553                         break;
 554                 case BPF_PROG_TYPE_TRACING:
 555                 case BPF_PROG_TYPE_LSM:
 556                         if (bpf_program__expected_attach_type(prog) == BPF_TRACE_ITER)
 557                                 printf("\tint fd = skel_link_create(prog_fd, 0, BPF_TRACE_ITER);\n");
 558                         else
 559                                 printf("\tint fd = skel_raw_tracepoint_open(NULL, prog_fd);\n");
 560                         break;
 561                 default:
 562                         printf("\tint fd = ((void)prog_fd, 0); /* auto-attach not supported */\n");
 563                         break;
 564                 }
 565                 codegen("\
 566                         \n\
 567                                                                                     \n\
 568                                 if (fd > 0)                                         \n\
 569                                         skel->links.%1$s_fd = fd;                   \n\
 570                                 return fd;                                          \n\
 571                         }                                                           \n\
 572                         ", bpf_program__name(prog));
 573         }
 574
 575         codegen("\
 576                 \n\
 577                                                                             \n\
 578                 static inline int                                           \n\
 579                 %1$s__attach(struct %1$s *skel)                             \n\
 580                 {                                                           \n\
 581                         int ret = 0;                                        \n\
 582                                                                             \n\
 583                 ", obj_name);
 584
 585         bpf_object__for_each_program(prog, obj) {
 586                 codegen("\
 587                         \n\
 588                                 ret = ret < 0 ? ret : %1$s__%2$s__attach(skel);   \n\
 589                         ", obj_name, bpf_program__name(prog));
 590         }
 591
 592         codegen("\
 593                 \n\
 594                         return ret < 0 ? ret : 0;                           \n\
 595                 }                                                           \n\
 596                                                                             \n\
 597                 static inline void                                          \n\
 598                 %1$s__detach(struct %1$s *skel)                             \n\
 599                 {                                                           \n\
 600                 ", obj_name);
 601
 602         bpf_object__for_each_program(prog, obj) {
 603                 codegen("\
 604                         \n\
 605                                 skel_closenz(skel->links.%1$s_fd);          \n\
 606                         ", bpf_program__name(prog));
 607         }
 608
 609         codegen("\
 610                 \n\
 611                 }                                                           \n\
 612                 ");
 613 }
 614
 615 static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
 616 {
 617         struct bpf_program *prog;
 618         struct bpf_map *map;
 619         char ident[256];
 620
 621         codegen("\
 622                 \n\
 623                 static void                                                 \n\
 624                 %1$s__destroy(struct %1$s *skel)                            \n\
 625                 {                                                           \n\
 626                         if (!skel)                                          \n\
 627                                 return;                                     \n\
 628                         %1$s__detach(skel);                                 \n\
 629                 ",
 630                 obj_name);
 631
 632         bpf_object__for_each_program(prog, obj) {
 633                 codegen("\
 634                         \n\
 635                                 skel_closenz(skel->progs.%1$s.prog_fd);     \n\
 636                         ", bpf_program__name(prog));
 637         }
 638
 639         bpf_object__for_each_map(map, obj) {
 640                 if (!get_map_ident(map, ident, sizeof(ident)))
 641                         continue;
 642                 if (bpf_map__is_internal(map) &&
 643                     (bpf_map__map_flags(map) & BPF_F_MMAPABLE))
 644                         printf("\tskel_free_map_data(skel->%1$s, skel->maps.%1$s.initial_value, %2$zd);\n",
 645                                ident, bpf_map_mmap_sz(map));
 646                 codegen("\
 647                         \n\
 648                                 skel_closenz(skel->maps.%1$s.map_fd);       \n\
 649                         ", ident);
 650         }
 651         codegen("\
 652                 \n\
 653                         skel_free(skel);                                    \n\
 654                 }                                                           \n\
 655                 ",
 656                 obj_name);
 657 }
 658
 659 static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *header_guard)
 660 {
 661         DECLARE_LIBBPF_OPTS(gen_loader_opts, opts);
 662         struct bpf_map *map;
 663         char ident[256];
 664         int err = 0;
 665
 666         err = bpf_object__gen_loader(obj, &opts);
 667         if (err)
 668                 return err;
 669
 670         err = bpf_object__load(obj);
 671         if (err) {
 672                 p_err("failed to load object file");
 673                 goto out;
 674         }
 675         /* If there was no error during load then gen_loader_opts
 676          * are populated with the loader program.
 677          */
 678
 679         /* finish generating 'struct skel' */
 680         codegen("\
 681                 \n\
 682                 };                                                          \n\
 683                 ", obj_name);
 684
 685
 686         codegen_attach_detach(obj, obj_name);
 687
 688         codegen_destroy(obj, obj_name);
 689
 690         codegen("\
 691                 \n\
 692                 static inline struct %1$s *                                 \n\
 693                 %1$s__open(void)                                            \n\
 694                 {                                                           \n\
 695                         struct %1$s *skel;                                  \n\
 696                                                                             \n\
 697                         skel = skel_alloc(sizeof(*skel));                   \n\
 698                         if (!skel)                                          \n\
 699                                 goto cleanup;                               \n\
 700                         skel->ctx.sz = (void *)&skel->links - (void *)skel; \n\
 701                 ",
 702                 obj_name, opts.data_sz);
 703         bpf_object__for_each_map(map, obj) {
 704                 const void *mmap_data = NULL;
 705                 size_t mmap_size = 0;
 706
 707                 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
 708                         continue;
 709
 710                 codegen("\
 711                 \n\
 712                         skel->%1$s = skel_prep_map_data((void *)\"\\        \n\
 713                 ", ident);
 714                 mmap_data = bpf_map__initial_value(map, &mmap_size);
 715                 print_hex(mmap_data, mmap_size);
 716                 codegen("\
 717                 \n\
 718                 \", %1$zd, %2$zd);                                          \n\
 719                         if (!skel->%3$s)                                    \n\
 720                                 goto cleanup;                               \n\
 721                         skel->maps.%3$s.initial_value = (__u64) (long) skel->%3$s;\n\
 722                 ", bpf_map_mmap_sz(map), mmap_size, ident);
 723         }
 724         codegen("\
 725                 \n\
 726                         return skel;                                        \n\
 727                 cleanup:                                                    \n\
 728                         %1$s__destroy(skel);                                \n\
 729                         return NULL;                                        \n\
 730                 }                                                           \n\
 731                                                                             \n\
 732                 static inline int                                           \n\
 733                 %1$s__load(struct %1$s *skel)                               \n\
 734                 {                                                           \n\
 735                         struct bpf_load_and_run_opts opts = {};             \n\
 736                         int err;                                            \n\
 737                                                                             \n\
 738                         opts.ctx = (struct bpf_loader_ctx *)skel;           \n\
 739                         opts.data_sz = %2$d;                                \n\
 740                         opts.data = (void *)\"\\                            \n\
 741                 ",
 742                 obj_name, opts.data_sz);
 743         print_hex(opts.data, opts.data_sz);
 744         codegen("\
 745                 \n\
 746                 \";                                                         \n\
 747                 ");
 748
 749         codegen("\
 750                 \n\
 751                         opts.insns_sz = %d;                                 \n\
 752                         opts.insns = (void *)\"\\                           \n\
 753                 ",
 754                 opts.insns_sz);
 755         print_hex(opts.insns, opts.insns_sz);
 756         codegen("\
 757                 \n\
 758                 \";                                                         \n\
 759                         err = bpf_load_and_run(&opts);                      \n\
 760                         if (err < 0)                                        \n\
 761                                 return err;                                 \n\
 762                 ", obj_name);
 763         bpf_object__for_each_map(map, obj) {
 764                 const char *mmap_flags;
 765
 766                 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
 767                         continue;
 768
 769                 if (bpf_map__map_flags(map) & BPF_F_RDONLY_PROG)
 770                         mmap_flags = "PROT_READ";
 771                 else
 772                         mmap_flags = "PROT_READ | PROT_WRITE";
 773
 774                 codegen("\
 775                 \n\
 776                         skel->%1$s = skel_finalize_map_data(&skel->maps.%1$s.initial_value,  \n\
 777                                                         %2$zd, %3$s, skel->maps.%1$s.map_fd);\n\
 778                         if (!skel->%1$s)                                    \n\
 779                                 return -ENOMEM;                             \n\
 780                         ",
 781                        ident, bpf_map_mmap_sz(map), mmap_flags);
 782         }
 783         codegen("\
 784                 \n\
 785                         return 0;                                           \n\
 786                 }                                                           \n\
 787                                                                             \n\
 788                 static inline struct %1$s *                                 \n\
 789                 %1$s__open_and_load(void)                                   \n\
 790                 {                                                           \n\
 791                         struct %1$s *skel;                                  \n\
 792                                                                             \n\
 793                         skel = %1$s__open();                                \n\
 794                         if (!skel)                                          \n\
 795                                 return NULL;                                \n\
 796                         if (%1$s__load(skel)) {                             \n\
 797                                 %1$s__destroy(skel);                        \n\
 798                                 return NULL;                                \n\
 799                         }                                                   \n\
 800                         return skel;                                        \n\
 801                 }                                                           \n\
 802                                                                             \n\
 803                 ", obj_name);
 804
 805         codegen_asserts(obj, obj_name);
 806
 807         codegen("\
 808                 \n\
 809                                                                             \n\
 810                 #endif /* %s */                                             \n\
 811                 ",
 812                 header_guard);
 813         err = 0;
 814 out:
 815         return err;
 816 }
 817
 818 static void
 819 codegen_maps_skeleton(struct bpf_object *obj, size_t map_cnt, bool mmaped)
 820 {
 821         struct bpf_map *map;
 822         char ident[256];
 823         size_t i;
 824
 825         if (!map_cnt)
 826                 return;
 827
 828         codegen("\
 829                 \n\
 830                                                                         \n\
 831                         /* maps */                                  \n\
 832                         s->map_cnt = %zu;                           \n\
 833                         s->map_skel_sz = sizeof(*s->maps);          \n\
 834                         s->maps = (struct bpf_map_skeleton *)calloc(s->map_cnt, s->map_skel_sz);\n\
 835                         if (!s->maps) {                             \n\
 836                                 err = -ENOMEM;                      \n\
 837                                 goto err;                           \n\
 838                         }                                           \n\
 839                 ",
 840                 map_cnt
 841         );
 842         i = 0;
 843         bpf_object__for_each_map(map, obj) {
 844                 if (!get_map_ident(map, ident, sizeof(ident)))
 845                         continue;
 846
 847                 codegen("\
 848                         \n\
 849                                                                         \n\
 850                                 s->maps[%zu].name = \"%s\";         \n\
 851                                 s->maps[%zu].map = &obj->maps.%s;   \n\
 852                         ",
 853                         i, bpf_map__name(map), i, ident);
 854                 /* memory-mapped internal maps */
 855                 if (mmaped && is_internal_mmapable_map(map, ident, sizeof(ident))) {
 856                         printf("\ts->maps[%zu].mmaped = (void **)&obj->%s;\n",
 857                                 i, ident);
 858                 }
 859                 i++;
 860         }
 861 }
 862
 863 static void
 864 codegen_progs_skeleton(struct bpf_object *obj, size_t prog_cnt, bool populate_links)
 865 {
 866         struct bpf_program *prog;
 867         int i;
 868
 869         if (!prog_cnt)
 870                 return;
 871
 872         codegen("\
 873                 \n\
 874                                                                         \n\
 875                         /* programs */                              \n\
 876                         s->prog_cnt = %zu;                          \n\
 877                         s->prog_skel_sz = sizeof(*s->progs);        \n\
 878                         s->progs = (struct bpf_prog_skeleton *)calloc(s->prog_cnt, s->prog_skel_sz);\n\
 879                         if (!s->progs) {                            \n\
 880                                 err = -ENOMEM;                      \n\
 881                                 goto err;                           \n\
 882                         }                                           \n\
 883                 ",
 884                 prog_cnt
 885         );
 886         i = 0;
 887         bpf_object__for_each_program(prog, obj) {
 888                 codegen("\
 889                         \n\
 890                                                                         \n\
 891                                 s->progs[%1$zu].name = \"%2$s\";    \n\
 892                                 s->progs[%1$zu].prog = &obj->progs.%2$s;\n\
 893                         ",
 894                         i, bpf_program__name(prog));
 895
 896                 if (populate_links) {
 897                         codegen("\
 898                                 \n\
 899                                         s->progs[%1$zu].link = &obj->links.%2$s;\n\
 900                                 ",
 901                                 i, bpf_program__name(prog));
 902                 }
 903                 i++;
 904         }
 905 }
 906
 907 static int do_skeleton(int argc, char **argv)
 908 {
 909         char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")];
 910         size_t map_cnt = 0, prog_cnt = 0, file_sz, mmap_sz;
 911         DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
 912         char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
 913         struct bpf_object *obj = NULL;
 914         const char *file;
 915         char ident[256];
 916         struct bpf_program *prog;
 917         int fd, err = -1;
 918         struct bpf_map *map;
 919         struct btf *btf;
 920         struct stat st;
 921
 922         if (!REQ_ARGS(1)) {
 923                 usage();
 924                 return -1;
 925         }
 926         file = GET_ARG();
 927
 928         while (argc) {
 929                 if (!REQ_ARGS(2))
 930                         return -1;
 931
 932                 if (is_prefix(*argv, "name")) {
 933                         NEXT_ARG();
 934
 935                         if (obj_name[0] != '\0') {
 936                                 p_err("object name already specified");
 937                                 return -1;
 938                         }
 939
 940                         strncpy(obj_name, *argv, MAX_OBJ_NAME_LEN - 1);
 941                         obj_name[MAX_OBJ_NAME_LEN - 1] = '\0';
 942                 } else {
 943                         p_err("unknown arg %s", *argv);
 944                         return -1;
 945                 }
 946
 947                 NEXT_ARG();
 948         }
 949
 950         if (argc) {
 951                 p_err("extra unknown arguments");
 952                 return -1;
 953         }
 954
 955         if (stat(file, &st)) {
 956                 p_err("failed to stat() %s: %s", file, strerror(errno));
 957                 return -1;
 958         }
 959         file_sz = st.st_size;
 960         mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
 961         fd = open(file, O_RDONLY);
 962         if (fd < 0) {
 963                 p_err("failed to open() %s: %s", file, strerror(errno));
 964                 return -1;
 965         }
 966         obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
 967         if (obj_data == MAP_FAILED) {
 968                 obj_data = NULL;
 969                 p_err("failed to mmap() %s: %s", file, strerror(errno));
 970                 goto out;
 971         }
 972         if (obj_name[0] == '\0')
 973                 get_obj_name(obj_name, file);
 974         opts.object_name = obj_name;
 975         if (verifier_logs)
 976                 /* log_level1 + log_level2 + stats, but not stable UAPI */
 977                 opts.kernel_log_level = 1 + 2 + 4;
 978         obj = bpf_object__open_mem(obj_data, file_sz, &opts);
 979         err = libbpf_get_error(obj);
 980         if (err) {
 981                 char err_buf[256];
 982
 983                 libbpf_strerror(err, err_buf, sizeof(err_buf));
 984                 p_err("failed to open BPF object file: %s", err_buf);
 985                 obj = NULL;
 986                 goto out;
 987         }
 988
 989         bpf_object__for_each_map(map, obj) {
 990                 if (!get_map_ident(map, ident, sizeof(ident))) {
 991                         p_err("ignoring unrecognized internal map '%s'...",
 992                               bpf_map__name(map));
 993                         continue;
 994                 }
 995                 map_cnt++;
 996         }
 997         bpf_object__for_each_program(prog, obj) {
 998                 prog_cnt++;
 999         }
1000
1001         get_header_guard(header_guard, obj_name, "SKEL_H");
1002         if (use_loader) {
1003                 codegen("\
1004                 \n\
1005                 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */   \n\
1006                 /* THIS FILE IS AUTOGENERATED BY BPFTOOL! */                \n\
1007                 #ifndef %2$s                                                \n\
1008                 #define %2$s                                                \n\
1009                                                                             \n\
1010                 #include <bpf/skel_internal.h>                              \n\
1011                                                                             \n\
1012                 struct %1$s {                                               \n\
1013                         struct bpf_loader_ctx ctx;                          \n\
1014                 ",
1015                 obj_name, header_guard
1016                 );
1017         } else {
1018                 codegen("\
1019                 \n\
1020                 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */   \n\
1021                                                                             \n\
1022                 /* THIS FILE IS AUTOGENERATED BY BPFTOOL! */                \n\
1023                 #ifndef %2$s                                                \n\
1024                 #define %2$s                                                \n\
1025                                                                             \n\
1026                 #include <errno.h>                                          \n\
1027                 #include <stdlib.h>                                         \n\
1028                 #include <bpf/libbpf.h>                                     \n\
1029                                                                             \n\
1030                 struct %1$s {                                               \n\
1031                         struct bpf_object_skeleton *skeleton;               \n\
1032                         struct bpf_object *obj;                             \n\
1033                 ",
1034                 obj_name, header_guard
1035                 );
1036         }
1037
1038         if (map_cnt) {
1039                 printf("\tstruct {\n");
1040                 bpf_object__for_each_map(map, obj) {
1041                         if (!get_map_ident(map, ident, sizeof(ident)))
1042                                 continue;
1043                         if (use_loader)
1044                                 printf("\t\tstruct bpf_map_desc %s;\n", ident);
1045                         else
1046                                 printf("\t\tstruct bpf_map *%s;\n", ident);
1047                 }
1048                 printf("\t} maps;\n");
1049         }
1050
1051         if (prog_cnt) {
1052                 printf("\tstruct {\n");
1053                 bpf_object__for_each_program(prog, obj) {
1054                         if (use_loader)
1055                                 printf("\t\tstruct bpf_prog_desc %s;\n",
1056                                        bpf_program__name(prog));
1057                         else
1058                                 printf("\t\tstruct bpf_program *%s;\n",
1059                                        bpf_program__name(prog));
1060                 }
1061                 printf("\t} progs;\n");
1062                 printf("\tstruct {\n");
1063                 bpf_object__for_each_program(prog, obj) {
1064                         if (use_loader)
1065                                 printf("\t\tint %s_fd;\n",
1066                                        bpf_program__name(prog));
1067                         else
1068                                 printf("\t\tstruct bpf_link *%s;\n",
1069                                        bpf_program__name(prog));
1070                 }
1071                 printf("\t} links;\n");
1072         }
1073
1074         btf = bpf_object__btf(obj);
1075         if (btf) {
1076                 err = codegen_datasecs(obj, obj_name);
1077                 if (err)
1078                         goto out;
1079         }
1080         if (use_loader) {
1081                 err = gen_trace(obj, obj_name, header_guard);
1082                 goto out;
1083         }
1084
1085         codegen("\
1086                 \n\
1087                                                                             \n\
1088                 #ifdef __cplusplus                                          \n\
1089                         static inline struct %1$s *open(const struct bpf_object_open_opts *opts = nullptr);\n\
1090                         static inline struct %1$s *open_and_load();         \n\
1091                         static inline int load(struct %1$s *skel);          \n\
1092                         static inline int attach(struct %1$s *skel);        \n\
1093                         static inline void detach(struct %1$s *skel);       \n\
1094                         static inline void destroy(struct %1$s *skel);      \n\
1095                         static inline const void *elf_bytes(size_t *sz);    \n\
1096                 #endif /* __cplusplus */                                    \n\
1097                 };                                                          \n\
1098                                                                             \n\
1099                 static void                                                 \n\
1100                 %1$s__destroy(struct %1$s *obj)                             \n\
1101                 {                                                           \n\
1102                         if (!obj)                                           \n\
1103                                 return;                                     \n\
1104                         if (obj->skeleton)                                  \n\
1105                                 bpf_object__destroy_skeleton(obj->skeleton);\n\
1106                         free(obj);                                          \n\
1107                 }                                                           \n\
1108                                                                             \n\
1109                 static inline int                                           \n\
1110                 %1$s__create_skeleton(struct %1$s *obj);                    \n\
1111                                                                             \n\
1112                 static inline struct %1$s *                                 \n\
1113                 %1$s__open_opts(const struct bpf_object_open_opts *opts)    \n\
1114                 {                                                           \n\
1115                         struct %1$s *obj;                                   \n\
1116                         int err;                                            \n\
1117                                                                             \n\
1118                         obj = (struct %1$s *)calloc(1, sizeof(*obj));       \n\
1119                         if (!obj) {                                         \n\
1120                                 errno = ENOMEM;                             \n\
1121                                 return NULL;                                \n\
1122                         }                                                   \n\
1123                                                                             \n\
1124                         err = %1$s__create_skeleton(obj);                   \n\
1125                         if (err)                                            \n\
1126                                 goto err_out;                               \n\
1127                                                                             \n\
1128                         err = bpf_object__open_skeleton(obj->skeleton, opts);\n\
1129                         if (err)                                            \n\
1130                                 goto err_out;                               \n\
1131                                                                             \n\
1132                         return obj;                                         \n\
1133                 err_out:                                                    \n\
1134                         %1$s__destroy(obj);                                 \n\
1135                         errno = -err;                                       \n\
1136                         return NULL;                                        \n\
1137                 }                                                           \n\
1138                                                                             \n\
1139                 static inline struct %1$s *                                 \n\
1140                 %1$s__open(void)                                            \n\
1141                 {                                                           \n\
1142                         return %1$s__open_opts(NULL);                       \n\
1143                 }                                                           \n\
1144                                                                             \n\
1145                 static inline int                                           \n\
1146                 %1$s__load(struct %1$s *obj)                                \n\
1147                 {                                                           \n\
1148                         return bpf_object__load_skeleton(obj->skeleton);    \n\
1149                 }                                                           \n\
1150                                                                             \n\
1151                 static inline struct %1$s *                                 \n\
1152                 %1$s__open_and_load(void)                                   \n\
1153                 {                                                           \n\
1154                         struct %1$s *obj;                                   \n\
1155                         int err;                                            \n\
1156                                                                             \n\
1157                         obj = %1$s__open();                                 \n\
1158                         if (!obj)                                           \n\
1159                                 return NULL;                                \n\
1160                         err = %1$s__load(obj);                              \n\
1161                         if (err) {                                          \n\
1162                                 %1$s__destroy(obj);                         \n\
1163                                 errno = -err;                               \n\
1164                                 return NULL;                                \n\
1165                         }                                                   \n\
1166                         return obj;                                         \n\
1167                 }                                                           \n\
1168                                                                             \n\
1169                 static inline int                                           \n\
1170                 %1$s__attach(struct %1$s *obj)                              \n\
1171                 {                                                           \n\
1172                         return bpf_object__attach_skeleton(obj->skeleton);  \n\
1173                 }                                                           \n\
1174                                                                             \n\
1175                 static inline void                                          \n\
1176                 %1$s__detach(struct %1$s *obj)                              \n\
1177                 {                                                           \n\
1178                         bpf_object__detach_skeleton(obj->skeleton);         \n\
1179                 }                                                           \n\
1180                 ",
1181                 obj_name
1182         );
1183
1184         codegen("\
1185                 \n\
1186                                                                             \n\
1187                 static inline const void *%1$s__elf_bytes(size_t *sz);      \n\
1188                                                                             \n\
1189                 static inline int                                           \n\
1190                 %1$s__create_skeleton(struct %1$s *obj)                     \n\
1191                 {                                                           \n\
1192                         struct bpf_object_skeleton *s;                      \n\
1193                         int err;                                            \n\
1194                                                                             \n\
1195                         s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\
1196                         if (!s) {                                           \n\
1197                                 err = -ENOMEM;                              \n\
1198                                 goto err;                                   \n\
1199                         }                                                   \n\
1200                                                                             \n\
1201                         s->sz = sizeof(*s);                                 \n\
1202                         s->name = \"%1$s\";                                 \n\
1203                         s->obj = &obj->obj;                                 \n\
1204                 ",
1205                 obj_name
1206         );
1207
1208         codegen_maps_skeleton(obj, map_cnt, true /*mmaped*/);
1209         codegen_progs_skeleton(obj, prog_cnt, true /*populate_links*/);
1210
1211         codegen("\
1212                 \n\
1213                                                                             \n\
1214                         s->data = (void *)%2$s__elf_bytes(&s->data_sz);     \n\
1215                                                                             \n\
1216                         obj->skeleton = s;                                  \n\
1217                         return 0;                                           \n\
1218                 err:                                                        \n\
1219                         bpf_object__destroy_skeleton(s);                    \n\
1220                         return err;                                         \n\
1221                 }                                                           \n\
1222                                                                             \n\
1223                 static inline const void *%2$s__elf_bytes(size_t *sz)       \n\
1224                 {                                                           \n\
1225                         *sz = %1$d;                                         \n\
1226                         return (const void *)\"\\                           \n\
1227                 "
1228                 , file_sz, obj_name);
1229
1230         /* embed contents of BPF object file */
1231         print_hex(obj_data, file_sz);
1232
1233         codegen("\
1234                 \n\
1235                 \";                                                         \n\
1236                 }                                                           \n\
1237                                                                             \n\
1238                 #ifdef __cplusplus                                          \n\
1239                 struct %1$s *%1$s::open(const struct bpf_object_open_opts *opts) { return %1$s__open_opts(opts); }\n\
1240                 struct %1$s *%1$s::open_and_load() { return %1$s__open_and_load(); }    \n\
1241                 int %1$s::load(struct %1$s *skel) { return %1$s__load(skel); }          \n\
1242                 int %1$s::attach(struct %1$s *skel) { return %1$s__attach(skel); }      \n\
1243                 void %1$s::detach(struct %1$s *skel) { %1$s__detach(skel); }            \n\
1244                 void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); }          \n\
1245                 const void *%1$s::elf_bytes(size_t *sz) { return %1$s__elf_bytes(sz); } \n\
1246                 #endif /* __cplusplus */                                    \n\
1247                                                                             \n\
1248                 ",
1249                 obj_name);
1250
1251         codegen_asserts(obj, obj_name);
1252
1253         codegen("\
1254                 \n\
1255                                                                             \n\
1256                 #endif /* %1$s */                                           \n\
1257                 ",
1258                 header_guard);
1259         err = 0;
1260 out:
1261         bpf_object__close(obj);
1262         if (obj_data)
1263                 munmap(obj_data, mmap_sz);
1264         close(fd);
1265         return err;
1266 }
1267
1268 /* Subskeletons are like skeletons, except they don't own the bpf_object,
1269  * associated maps, links, etc. Instead, they know about the existence of
1270  * variables, maps, programs and are able to find their locations
1271  * _at runtime_ from an already loaded bpf_object.
1272  *
1273  * This allows for library-like BPF objects to have userspace counterparts
1274  * with access to their own items without having to know anything about the
1275  * final BPF object that the library was linked into.
1276  */
1277 static int do_subskeleton(int argc, char **argv)
1278 {
1279         char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SUBSKEL_H__")];
1280         size_t i, len, file_sz, map_cnt = 0, prog_cnt = 0, mmap_sz, var_cnt = 0, var_idx = 0;
1281         DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
1282         char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
1283         struct bpf_object *obj = NULL;
1284         const char *file, *var_name;
1285         char ident[256];
1286         int fd, err = -1, map_type_id;
1287         const struct bpf_map *map;
1288         struct bpf_program *prog;
1289         struct btf *btf;
1290         const struct btf_type *map_type, *var_type;
1291         const struct btf_var_secinfo *var;
1292         struct stat st;
1293
1294         if (!REQ_ARGS(1)) {
1295                 usage();
1296                 return -1;
1297         }
1298         file = GET_ARG();
1299
1300         while (argc) {
1301                 if (!REQ_ARGS(2))
1302                         return -1;
1303
1304                 if (is_prefix(*argv, "name")) {
1305                         NEXT_ARG();
1306
1307                         if (obj_name[0] != '\0') {
1308                                 p_err("object name already specified");
1309                                 return -1;
1310                         }
1311
1312                         strncpy(obj_name, *argv, MAX_OBJ_NAME_LEN - 1);
1313                         obj_name[MAX_OBJ_NAME_LEN - 1] = '\0';
1314                 } else {
1315                         p_err("unknown arg %s", *argv);
1316                         return -1;
1317                 }
1318
1319                 NEXT_ARG();
1320         }
1321
1322         if (argc) {
1323                 p_err("extra unknown arguments");
1324                 return -1;
1325         }
1326
1327         if (use_loader) {
1328                 p_err("cannot use loader for subskeletons");
1329                 return -1;
1330         }
1331
1332         if (stat(file, &st)) {
1333                 p_err("failed to stat() %s: %s", file, strerror(errno));
1334                 return -1;
1335         }
1336         file_sz = st.st_size;
1337         mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
1338         fd = open(file, O_RDONLY);
1339         if (fd < 0) {
1340                 p_err("failed to open() %s: %s", file, strerror(errno));
1341                 return -1;
1342         }
1343         obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
1344         if (obj_data == MAP_FAILED) {
1345                 obj_data = NULL;
1346                 p_err("failed to mmap() %s: %s", file, strerror(errno));
1347                 goto out;
1348         }
1349         if (obj_name[0] == '\0')
1350                 get_obj_name(obj_name, file);
1351
1352         /* The empty object name allows us to use bpf_map__name and produce
1353          * ELF section names out of it. (".data" instead of "obj.data")
1354          */
1355         opts.object_name = "";
1356         obj = bpf_object__open_mem(obj_data, file_sz, &opts);
1357         if (!obj) {
1358                 char err_buf[256];
1359
1360                 libbpf_strerror(errno, err_buf, sizeof(err_buf));
1361                 p_err("failed to open BPF object file: %s", err_buf);
1362                 obj = NULL;
1363                 goto out;
1364         }
1365
1366         btf = bpf_object__btf(obj);
1367         if (!btf) {
1368                 err = -1;
1369                 p_err("need btf type information for %s", obj_name);
1370                 goto out;
1371         }
1372
1373         bpf_object__for_each_program(prog, obj) {
1374                 prog_cnt++;
1375         }
1376
1377         /* First, count how many variables we have to find.
1378          * We need this in advance so the subskel can allocate the right
1379          * amount of storage.
1380          */
1381         bpf_object__for_each_map(map, obj) {
1382                 if (!get_map_ident(map, ident, sizeof(ident)))
1383                         continue;
1384
1385                 /* Also count all maps that have a name */
1386                 map_cnt++;
1387
1388                 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
1389                         continue;
1390
1391                 map_type_id = bpf_map__btf_value_type_id(map);
1392                 if (map_type_id <= 0) {
1393                         err = map_type_id;
1394                         goto out;
1395                 }
1396                 map_type = btf__type_by_id(btf, map_type_id);
1397
1398                 var = btf_var_secinfos(map_type);
1399                 len = btf_vlen(map_type);
1400                 for (i = 0; i < len; i++, var++) {
1401                         var_type = btf__type_by_id(btf, var->type);
1402
1403                         if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
1404                                 continue;
1405
1406                         var_cnt++;
1407                 }
1408         }
1409
1410         get_header_guard(header_guard, obj_name, "SUBSKEL_H");
1411         codegen("\
1412         \n\
1413         /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */           \n\
1414                                                                             \n\
1415         /* THIS FILE IS AUTOGENERATED! */                                   \n\
1416         #ifndef %2$s                                                        \n\
1417         #define %2$s                                                        \n\
1418                                                                             \n\
1419         #include <errno.h>                                                  \n\
1420         #include <stdlib.h>                                                 \n\
1421         #include <bpf/libbpf.h>                                             \n\
1422                                                                             \n\
1423         struct %1$s {                                                       \n\
1424                 struct bpf_object *obj;                                     \n\
1425                 struct bpf_object_subskeleton *subskel;                     \n\
1426         ", obj_name, header_guard);
1427
1428         if (map_cnt) {
1429                 printf("\tstruct {\n");
1430                 bpf_object__for_each_map(map, obj) {
1431                         if (!get_map_ident(map, ident, sizeof(ident)))
1432                                 continue;
1433                         printf("\t\tstruct bpf_map *%s;\n", ident);
1434                 }
1435                 printf("\t} maps;\n");
1436         }
1437
1438         if (prog_cnt) {
1439                 printf("\tstruct {\n");
1440                 bpf_object__for_each_program(prog, obj) {
1441                         printf("\t\tstruct bpf_program *%s;\n",
1442                                 bpf_program__name(prog));
1443                 }
1444                 printf("\t} progs;\n");
1445         }
1446
1447         err = codegen_subskel_datasecs(obj, obj_name);
1448         if (err)
1449                 goto out;
1450
1451         /* emit code that will allocate enough storage for all symbols */
1452         codegen("\
1453                 \n\
1454                                                                             \n\
1455                 #ifdef __cplusplus                                          \n\
1456                         static inline struct %1$s *open(const struct bpf_object *src);\n\
1457                         static inline void destroy(struct %1$s *skel);      \n\
1458                 #endif /* __cplusplus */                                    \n\
1459                 };                                                          \n\
1460                                                                             \n\
1461                 static inline void                                          \n\
1462                 %1$s__destroy(struct %1$s *skel)                            \n\
1463                 {                                                           \n\
1464                         if (!skel)                                          \n\
1465                                 return;                                     \n\
1466                         if (skel->subskel)                                  \n\
1467                                 bpf_object__destroy_subskeleton(skel->subskel);\n\
1468                         free(skel);                                         \n\
1469                 }                                                           \n\
1470                                                                             \n\
1471                 static inline struct %1$s *                                 \n\
1472                 %1$s__open(const struct bpf_object *src)                    \n\
1473                 {                                                           \n\
1474                         struct %1$s *obj;                                   \n\
1475                         struct bpf_object_subskeleton *s;                   \n\
1476                         int err;                                            \n\
1477                                                                             \n\
1478                         obj = (struct %1$s *)calloc(1, sizeof(*obj));       \n\
1479                         if (!obj) {                                         \n\
1480                                 err = -ENOMEM;                              \n\
1481                                 goto err;                                   \n\
1482                         }                                                   \n\
1483                         s = (struct bpf_object_subskeleton *)calloc(1, sizeof(*s));\n\
1484                         if (!s) {                                           \n\
1485                                 err = -ENOMEM;                              \n\
1486                                 goto err;                                   \n\
1487                         }                                                   \n\
1488                         s->sz = sizeof(*s);                                 \n\
1489                         s->obj = src;                                       \n\
1490                         s->var_skel_sz = sizeof(*s->vars);                  \n\
1491                         obj->subskel = s;                                   \n\
1492                                                                             \n\
1493                         /* vars */                                          \n\
1494                         s->var_cnt = %2$d;                                  \n\
1495                         s->vars = (struct bpf_var_skeleton *)calloc(%2$d, sizeof(*s->vars));\n\
1496                         if (!s->vars) {                                     \n\
1497                                 err = -ENOMEM;                              \n\
1498                                 goto err;                                   \n\
1499                         }                                                   \n\
1500                 ",
1501                 obj_name, var_cnt
1502         );
1503
1504         /* walk through each symbol and emit the runtime representation */
1505         bpf_object__for_each_map(map, obj) {
1506                 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
1507                         continue;
1508
1509                 map_type_id = bpf_map__btf_value_type_id(map);
1510                 if (map_type_id <= 0)
1511                         /* skip over internal maps with no type*/
1512                         continue;
1513
1514                 map_type = btf__type_by_id(btf, map_type_id);
1515                 var = btf_var_secinfos(map_type);
1516                 len = btf_vlen(map_type);
1517                 for (i = 0; i < len; i++, var++) {
1518                         var_type = btf__type_by_id(btf, var->type);
1519                         var_name = btf__name_by_offset(btf, var_type->name_off);
1520
1521                         if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
1522                                 continue;
1523
1524                         /* Note that we use the dot prefix in .data as the
1525                          * field access operator i.e. maps%s becomes maps.data
1526                          */
1527                         codegen("\
1528                         \n\
1529                                                                             \n\
1530                                 s->vars[%3$d].name = \"%1$s\";              \n\
1531                                 s->vars[%3$d].map = &obj->maps.%2$s;        \n\
1532                                 s->vars[%3$d].addr = (void **) &obj->%2$s.%1$s;\n\
1533                         ", var_name, ident, var_idx);
1534
1535                         var_idx++;
1536                 }
1537         }
1538
1539         codegen_maps_skeleton(obj, map_cnt, false /*mmaped*/);
1540         codegen_progs_skeleton(obj, prog_cnt, false /*links*/);
1541
1542         codegen("\
1543                 \n\
1544                                                                             \n\
1545                         err = bpf_object__open_subskeleton(s);              \n\
1546                         if (err)                                            \n\
1547                                 goto err;                                   \n\
1548                                                                             \n\
1549                         return obj;                                         \n\
1550                 err:                                                        \n\
1551                         %1$s__destroy(obj);                                 \n\
1552                         errno = -err;                                       \n\
1553                         return NULL;                                        \n\
1554                 }                                                           \n\
1555                                                                             \n\
1556                 #ifdef __cplusplus                                          \n\
1557                 struct %1$s *%1$s::open(const struct bpf_object *src) { return %1$s__open(src); }\n\
1558                 void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); }\n\
1559                 #endif /* __cplusplus */                                    \n\
1560                                                                             \n\
1561                 #endif /* %2$s */                                           \n\
1562                 ",
1563                 obj_name, header_guard);
1564         err = 0;
1565 out:
1566         bpf_object__close(obj);
1567         if (obj_data)
1568                 munmap(obj_data, mmap_sz);
1569         close(fd);
1570         return err;
1571 }
1572
1573 static int do_object(int argc, char **argv)
1574 {
1575         struct bpf_linker *linker;
1576         const char *output_file, *file;
1577         int err = 0;
1578
1579         if (!REQ_ARGS(2)) {
1580                 usage();
1581                 return -1;
1582         }
1583
1584         output_file = GET_ARG();
1585
1586         linker = bpf_linker__new(output_file, NULL);
1587         if (!linker) {
1588                 p_err("failed to create BPF linker instance");
1589                 return -1;
1590         }
1591
1592         while (argc) {
1593                 file = GET_ARG();
1594
1595                 err = bpf_linker__add_file(linker, file, NULL);
1596                 if (err) {
1597                         p_err("failed to link '%s': %s (%d)", file, strerror(errno), errno);
1598                         goto out;
1599                 }
1600         }
1601
1602         err = bpf_linker__finalize(linker);
1603         if (err) {
1604                 p_err("failed to finalize ELF file: %s (%d)", strerror(errno), errno);
1605                 goto out;
1606         }
1607
1608         err = 0;
1609 out:
1610         bpf_linker__free(linker);
1611         return err;
1612 }
1613
1614 static int do_help(int argc, char **argv)
1615 {
1616         if (json_output) {
1617                 jsonw_null(json_wtr);
1618                 return 0;
1619         }
1620
1621         fprintf(stderr,
1622                 "Usage: %1$s %2$s object OUTPUT_FILE INPUT_FILE [INPUT_FILE...]\n"
1623                 "       %1$s %2$s skeleton FILE [name OBJECT_NAME]\n"
1624                 "       %1$s %2$s subskeleton FILE [name OBJECT_NAME]\n"
1625                 "       %1$s %2$s min_core_btf INPUT OUTPUT OBJECT [OBJECT...]\n"
1626                 "       %1$s %2$s help\n"
1627                 "\n"
1628                 "       " HELP_SPEC_OPTIONS " |\n"
1629                 "                    {-L|--use-loader} }\n"
1630                 "",
1631                 bin_name, "gen");
1632
1633         return 0;
1634 }
1635
1636 static int btf_save_raw(const struct btf *btf, const char *path)
1637 {
1638         const void *data;
1639         FILE *f = NULL;
1640         __u32 data_sz;
1641         int err = 0;
1642
1643         data = btf__raw_data(btf, &data_sz);
1644         if (!data)
1645                 return -ENOMEM;
1646
1647         f = fopen(path, "wb");
1648         if (!f)
1649                 return -errno;
1650
1651         if (fwrite(data, 1, data_sz, f) != data_sz)
1652                 err = -errno;
1653
1654         fclose(f);
1655         return err;
1656 }
1657
1658 struct btfgen_info {
1659         struct btf *src_btf;
1660         struct btf *marked_btf; /* btf structure used to mark used types */
1661 };
1662
1663 static size_t btfgen_hash_fn(const void *key, void *ctx)
1664 {
1665         return (size_t)key;
1666 }
1667
1668 static bool btfgen_equal_fn(const void *k1, const void *k2, void *ctx)
1669 {
1670         return k1 == k2;
1671 }
1672
1673 static void *u32_as_hash_key(__u32 x)
1674 {
1675         return (void *)(uintptr_t)x;
1676 }
1677
1678 static void btfgen_free_info(struct btfgen_info *info)
1679 {
1680         if (!info)
1681                 return;
1682
1683         btf__free(info->src_btf);
1684         btf__free(info->marked_btf);
1685
1686         free(info);
1687 }
1688
1689 static struct btfgen_info *
1690 btfgen_new_info(const char *targ_btf_path)
1691 {
1692         struct btfgen_info *info;
1693         int err;
1694
1695         info = calloc(1, sizeof(*info));
1696         if (!info)
1697                 return NULL;
1698
1699         info->src_btf = btf__parse(targ_btf_path, NULL);
1700         if (!info->src_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         info->marked_btf = btf__parse(targ_btf_path, NULL);
1707         if (!info->marked_btf) {
1708                 err = -errno;
1709                 p_err("failed parsing '%s' BTF file: %s", targ_btf_path, strerror(errno));
1710                 goto err_out;
1711         }
1712
1713         return info;
1714
1715 err_out:
1716         btfgen_free_info(info);
1717         errno = -err;
1718         return NULL;
1719 }
1720
1721 #define MARKED UINT32_MAX
1722
1723 static void btfgen_mark_member(struct btfgen_info *info, int type_id, int idx)
1724 {
1725         const struct btf_type *t = btf__type_by_id(info->marked_btf, type_id);
1726         struct btf_member *m = btf_members(t) + idx;
1727
1728         m->name_off = MARKED;
1729 }
1730
1731 static int
1732 btfgen_mark_type(struct btfgen_info *info, unsigned int type_id, bool follow_pointers)
1733 {
1734         const struct btf_type *btf_type = btf__type_by_id(info->src_btf, type_id);
1735         struct btf_type *cloned_type;
1736         struct btf_param *param;
1737         struct btf_array *array;
1738         int err, i;
1739
1740         if (type_id == 0)
1741                 return 0;
1742
1743         /* mark type on cloned BTF as used */
1744         cloned_type = (struct btf_type *) btf__type_by_id(info->marked_btf, type_id);
1745         cloned_type->name_off = MARKED;
1746
1747         /* recursively mark other types needed by it */
1748         switch (btf_kind(btf_type)) {
1749         case BTF_KIND_UNKN:
1750         case BTF_KIND_INT:
1751         case BTF_KIND_FLOAT:
1752         case BTF_KIND_ENUM:
1753         case BTF_KIND_ENUM64:
1754         case BTF_KIND_STRUCT:
1755         case BTF_KIND_UNION:
1756                 break;
1757         case BTF_KIND_PTR:
1758                 if (follow_pointers) {
1759                         err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1760                         if (err)
1761                                 return err;
1762                 }
1763                 break;
1764         case BTF_KIND_CONST:
1765         case BTF_KIND_RESTRICT:
1766         case BTF_KIND_VOLATILE:
1767         case BTF_KIND_TYPEDEF:
1768                 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1769                 if (err)
1770                         return err;
1771                 break;
1772         case BTF_KIND_ARRAY:
1773                 array = btf_array(btf_type);
1774
1775                 /* mark array type */
1776                 err = btfgen_mark_type(info, array->type, follow_pointers);
1777                 /* mark array's index type */
1778                 err = err ? : btfgen_mark_type(info, array->index_type, follow_pointers);
1779                 if (err)
1780                         return err;
1781                 break;
1782         case BTF_KIND_FUNC_PROTO:
1783                 /* mark ret type */
1784                 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1785                 if (err)
1786                         return err;
1787
1788                 /* mark parameters types */
1789                 param = btf_params(btf_type);
1790                 for (i = 0; i < btf_vlen(btf_type); i++) {
1791                         err = btfgen_mark_type(info, param->type, follow_pointers);
1792                         if (err)
1793                                 return err;
1794                         param++;
1795                 }
1796                 break;
1797         /* tells if some other type needs to be handled */
1798         default:
1799                 p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
1800                 return -EINVAL;
1801         }
1802
1803         return 0;
1804 }
1805
1806 static int btfgen_record_field_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1807 {
1808         struct btf *btf = info->src_btf;
1809         const struct btf_type *btf_type;
1810         struct btf_member *btf_member;
1811         struct btf_array *array;
1812         unsigned int type_id = targ_spec->root_type_id;
1813         int idx, err;
1814
1815         /* mark root type */
1816         btf_type = btf__type_by_id(btf, type_id);
1817         err = btfgen_mark_type(info, type_id, false);
1818         if (err)
1819                 return err;
1820
1821         /* mark types for complex types (arrays, unions, structures) */
1822         for (int i = 1; i < targ_spec->raw_len; i++) {
1823                 /* skip typedefs and mods */
1824                 while (btf_is_mod(btf_type) || btf_is_typedef(btf_type)) {
1825                         type_id = btf_type->type;
1826                         btf_type = btf__type_by_id(btf, type_id);
1827                 }
1828
1829                 switch (btf_kind(btf_type)) {
1830                 case BTF_KIND_STRUCT:
1831                 case BTF_KIND_UNION:
1832                         idx = targ_spec->raw_spec[i];
1833                         btf_member = btf_members(btf_type) + idx;
1834
1835                         /* mark member */
1836                         btfgen_mark_member(info, type_id, idx);
1837
1838                         /* mark member's type */
1839                         type_id = btf_member->type;
1840                         btf_type = btf__type_by_id(btf, type_id);
1841                         err = btfgen_mark_type(info, type_id, false);
1842                         if (err)
1843                                 return err;
1844                         break;
1845                 case BTF_KIND_ARRAY:
1846                         array = btf_array(btf_type);
1847                         type_id = array->type;
1848                         btf_type = btf__type_by_id(btf, type_id);
1849                         break;
1850                 default:
1851                         p_err("unsupported kind: %s (%d)",
1852                               btf_kind_str(btf_type), btf_type->type);
1853                         return -EINVAL;
1854                 }
1855         }
1856
1857         return 0;
1858 }
1859
1860 /* Mark types, members, and member types. Compared to btfgen_record_field_relo,
1861  * this function does not rely on the target spec for inferring members, but
1862  * uses the associated BTF.
1863  *
1864  * The `behind_ptr` argument is used to stop marking of composite types reached
1865  * through a pointer. This way, we can keep BTF size in check while providing
1866  * reasonable match semantics.
1867  */
1868 static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool behind_ptr)
1869 {
1870         const struct btf_type *btf_type;
1871         struct btf *btf = info->src_btf;
1872         struct btf_type *cloned_type;
1873         int i, err;
1874
1875         if (type_id == 0)
1876                 return 0;
1877
1878         btf_type = btf__type_by_id(btf, type_id);
1879         /* mark type on cloned BTF as used */
1880         cloned_type = (struct btf_type *)btf__type_by_id(info->marked_btf, type_id);
1881         cloned_type->name_off = MARKED;
1882
1883         switch (btf_kind(btf_type)) {
1884         case BTF_KIND_UNKN:
1885         case BTF_KIND_INT:
1886         case BTF_KIND_FLOAT:
1887         case BTF_KIND_ENUM:
1888         case BTF_KIND_ENUM64:
1889                 break;
1890         case BTF_KIND_STRUCT:
1891         case BTF_KIND_UNION: {
1892                 struct btf_member *m = btf_members(btf_type);
1893                 __u16 vlen = btf_vlen(btf_type);
1894
1895                 if (behind_ptr)
1896                         break;
1897
1898                 for (i = 0; i < vlen; i++, m++) {
1899                         /* mark member */
1900                         btfgen_mark_member(info, type_id, i);
1901
1902                         /* mark member's type */
1903                         err = btfgen_mark_type_match(info, m->type, false);
1904                         if (err)
1905                                 return err;
1906                 }
1907                 break;
1908         }
1909         case BTF_KIND_CONST:
1910         case BTF_KIND_FWD:
1911         case BTF_KIND_RESTRICT:
1912         case BTF_KIND_TYPEDEF:
1913         case BTF_KIND_VOLATILE:
1914                 return btfgen_mark_type_match(info, btf_type->type, behind_ptr);
1915         case BTF_KIND_PTR:
1916                 return btfgen_mark_type_match(info, btf_type->type, true);
1917         case BTF_KIND_ARRAY: {
1918                 struct btf_array *array;
1919
1920                 array = btf_array(btf_type);
1921                 /* mark array type */
1922                 err = btfgen_mark_type_match(info, array->type, false);
1923                 /* mark array's index type */
1924                 err = err ? : btfgen_mark_type_match(info, array->index_type, false);
1925                 if (err)
1926                         return err;
1927                 break;
1928         }
1929         case BTF_KIND_FUNC_PROTO: {
1930                 __u16 vlen = btf_vlen(btf_type);
1931                 struct btf_param *param;
1932
1933                 /* mark ret type */
1934                 err = btfgen_mark_type_match(info, btf_type->type, false);
1935                 if (err)
1936                         return err;
1937
1938                 /* mark parameters types */
1939                 param = btf_params(btf_type);
1940                 for (i = 0; i < vlen; i++) {
1941                         err = btfgen_mark_type_match(info, param->type, false);
1942                         if (err)
1943                                 return err;
1944                         param++;
1945                 }
1946                 break;
1947         }
1948         /* tells if some other type needs to be handled */
1949         default:
1950                 p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
1951                 return -EINVAL;
1952         }
1953
1954         return 0;
1955 }
1956
1957 /* Mark types, members, and member types. Compared to btfgen_record_field_relo,
1958  * this function does not rely on the target spec for inferring members, but
1959  * uses the associated BTF.
1960  */
1961 static int btfgen_record_type_match_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1962 {
1963         return btfgen_mark_type_match(info, targ_spec->root_type_id, false);
1964 }
1965
1966 static int btfgen_record_type_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1967 {
1968         return btfgen_mark_type(info, targ_spec->root_type_id, true);
1969 }
1970
1971 static int btfgen_record_enumval_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1972 {
1973         return btfgen_mark_type(info, targ_spec->root_type_id, false);
1974 }
1975
1976 static int btfgen_record_reloc(struct btfgen_info *info, struct bpf_core_spec *res)
1977 {
1978         switch (res->relo_kind) {
1979         case BPF_CORE_FIELD_BYTE_OFFSET:
1980         case BPF_CORE_FIELD_BYTE_SIZE:
1981         case BPF_CORE_FIELD_EXISTS:
1982         case BPF_CORE_FIELD_SIGNED:
1983         case BPF_CORE_FIELD_LSHIFT_U64:
1984         case BPF_CORE_FIELD_RSHIFT_U64:
1985                 return btfgen_record_field_relo(info, res);
1986         case BPF_CORE_TYPE_ID_LOCAL: /* BPF_CORE_TYPE_ID_LOCAL doesn't require kernel BTF */
1987                 return 0;
1988         case BPF_CORE_TYPE_ID_TARGET:
1989         case BPF_CORE_TYPE_EXISTS:
1990         case BPF_CORE_TYPE_SIZE:
1991                 return btfgen_record_type_relo(info, res);
1992         case BPF_CORE_TYPE_MATCHES:
1993                 return btfgen_record_type_match_relo(info, res);
1994         case BPF_CORE_ENUMVAL_EXISTS:
1995         case BPF_CORE_ENUMVAL_VALUE:
1996                 return btfgen_record_enumval_relo(info, res);
1997         default:
1998                 return -EINVAL;
1999         }
2000 }
2001
2002 static struct bpf_core_cand_list *
2003 btfgen_find_cands(const struct btf *local_btf, const struct btf *targ_btf, __u32 local_id)
2004 {
2005         const struct btf_type *local_type;
2006         struct bpf_core_cand_list *cands = NULL;
2007         struct bpf_core_cand local_cand = {};
2008         size_t local_essent_len;
2009         const char *local_name;
2010         int err;
2011
2012         local_cand.btf = local_btf;
2013         local_cand.id = local_id;
2014
2015         local_type = btf__type_by_id(local_btf, local_id);
2016         if (!local_type) {
2017                 err = -EINVAL;
2018                 goto err_out;
2019         }
2020
2021         local_name = btf__name_by_offset(local_btf, local_type->name_off);
2022         if (!local_name) {
2023                 err = -EINVAL;
2024                 goto err_out;
2025         }
2026         local_essent_len = bpf_core_essential_name_len(local_name);
2027
2028         cands = calloc(1, sizeof(*cands));
2029         if (!cands)
2030                 return NULL;
2031
2032         err = bpf_core_add_cands(&local_cand, local_essent_len, targ_btf, "vmlinux", 1, cands);
2033         if (err)
2034                 goto err_out;
2035
2036         return cands;
2037
2038 err_out:
2039         bpf_core_free_cands(cands);
2040         errno = -err;
2041         return NULL;
2042 }
2043
2044 /* Record relocation information for a single BPF object */
2045 static int btfgen_record_obj(struct btfgen_info *info, const char *obj_path)
2046 {
2047         const struct btf_ext_info_sec *sec;
2048         const struct bpf_core_relo *relo;
2049         const struct btf_ext_info *seg;
2050         struct hashmap_entry *entry;
2051         struct hashmap *cand_cache = NULL;
2052         struct btf_ext *btf_ext = NULL;
2053         unsigned int relo_idx;
2054         struct btf *btf = NULL;
2055         size_t i;
2056         int err;
2057
2058         btf = btf__parse(obj_path, &btf_ext);
2059         if (!btf) {
2060                 err = -errno;
2061                 p_err("failed to parse BPF object '%s': %s", obj_path, strerror(errno));
2062                 return err;
2063         }
2064
2065         if (!btf_ext) {
2066                 p_err("failed to parse BPF object '%s': section %s not found",
2067                       obj_path, BTF_EXT_ELF_SEC);
2068                 err = -EINVAL;
2069                 goto out;
2070         }
2071
2072         if (btf_ext->core_relo_info.len == 0) {
2073                 err = 0;
2074                 goto out;
2075         }
2076
2077         cand_cache = hashmap__new(btfgen_hash_fn, btfgen_equal_fn, NULL);
2078         if (IS_ERR(cand_cache)) {
2079                 err = PTR_ERR(cand_cache);
2080                 goto out;
2081         }
2082
2083         seg = &btf_ext->core_relo_info;
2084         for_each_btf_ext_sec(seg, sec) {
2085                 for_each_btf_ext_rec(seg, sec, relo_idx, relo) {
2086                         struct bpf_core_spec specs_scratch[3] = {};
2087                         struct bpf_core_relo_res targ_res = {};
2088                         struct bpf_core_cand_list *cands = NULL;
2089                         const void *type_key = u32_as_hash_key(relo->type_id);
2090                         const char *sec_name = btf__name_by_offset(btf, sec->sec_name_off);
2091
2092                         if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
2093                             !hashmap__find(cand_cache, type_key, (void **)&cands)) {
2094                                 cands = btfgen_find_cands(btf, info->src_btf, relo->type_id);
2095                                 if (!cands) {
2096                                         err = -errno;
2097                                         goto out;
2098                                 }
2099
2100                                 err = hashmap__set(cand_cache, type_key, cands, NULL, NULL);
2101                                 if (err)
2102                                         goto out;
2103                         }
2104
2105                         err = bpf_core_calc_relo_insn(sec_name, relo, relo_idx, btf, cands,
2106                                                       specs_scratch, &targ_res);
2107                         if (err)
2108                                 goto out;
2109
2110                         /* specs_scratch[2] is the target spec */
2111                         err = btfgen_record_reloc(info, &specs_scratch[2]);
2112                         if (err)
2113                                 goto out;
2114                 }
2115         }
2116
2117 out:
2118         btf__free(btf);
2119         btf_ext__free(btf_ext);
2120
2121         if (!IS_ERR_OR_NULL(cand_cache)) {
2122                 hashmap__for_each_entry(cand_cache, entry, i) {
2123                         bpf_core_free_cands(entry->value);
2124                 }
2125                 hashmap__free(cand_cache);
2126         }
2127
2128         return err;
2129 }
2130
2131 static int btfgen_remap_id(__u32 *type_id, void *ctx)
2132 {
2133         unsigned int *ids = ctx;
2134
2135         *type_id = ids[*type_id];
2136
2137         return 0;
2138 }
2139
2140 /* Generate BTF from relocation information previously recorded */
2141 static struct btf *btfgen_get_btf(struct btfgen_info *info)
2142 {
2143         struct btf *btf_new = NULL;
2144         unsigned int *ids = NULL;
2145         unsigned int i, n = btf__type_cnt(info->marked_btf);
2146         int err = 0;
2147
2148         btf_new = btf__new_empty();
2149         if (!btf_new) {
2150                 err = -errno;
2151                 goto err_out;
2152         }
2153
2154         ids = calloc(n, sizeof(*ids));
2155         if (!ids) {
2156                 err = -errno;
2157                 goto err_out;
2158         }
2159
2160         /* first pass: add all marked types to btf_new and add their new ids to the ids map */
2161         for (i = 1; i < n; i++) {
2162                 const struct btf_type *cloned_type, *type;
2163                 const char *name;
2164                 int new_id;
2165
2166                 cloned_type = btf__type_by_id(info->marked_btf, i);
2167
2168                 if (cloned_type->name_off != MARKED)
2169                         continue;
2170
2171                 type = btf__type_by_id(info->src_btf, i);
2172
2173                 /* add members for struct and union */
2174                 if (btf_is_composite(type)) {
2175                         struct btf_member *cloned_m, *m;
2176                         unsigned short vlen;
2177                         int idx_src;
2178
2179                         name = btf__str_by_offset(info->src_btf, type->name_off);
2180
2181                         if (btf_is_struct(type))
2182                                 err = btf__add_struct(btf_new, name, type->size);
2183                         else
2184                                 err = btf__add_union(btf_new, name, type->size);
2185
2186                         if (err < 0)
2187                                 goto err_out;
2188                         new_id = err;
2189
2190                         cloned_m = btf_members(cloned_type);
2191                         m = btf_members(type);
2192                         vlen = btf_vlen(cloned_type);
2193                         for (idx_src = 0; idx_src < vlen; idx_src++, cloned_m++, m++) {
2194                                 /* add only members that are marked as used */
2195                                 if (cloned_m->name_off != MARKED)
2196                                         continue;
2197
2198                                 name = btf__str_by_offset(info->src_btf, m->name_off);
2199                                 err = btf__add_field(btf_new, name, m->type,
2200                                                      btf_member_bit_offset(cloned_type, idx_src),
2201                                                      btf_member_bitfield_size(cloned_type, idx_src));
2202                                 if (err < 0)
2203                                         goto err_out;
2204                         }
2205                 } else {
2206                         err = btf__add_type(btf_new, info->src_btf, type);
2207                         if (err < 0)
2208                                 goto err_out;
2209                         new_id = err;
2210                 }
2211
2212                 /* add ID mapping */
2213                 ids[i] = new_id;
2214         }
2215
2216         /* second pass: fix up type ids */
2217         for (i = 1; i < btf__type_cnt(btf_new); i++) {
2218                 struct btf_type *btf_type = (struct btf_type *) btf__type_by_id(btf_new, i);
2219
2220                 err = btf_type_visit_type_ids(btf_type, btfgen_remap_id, ids);
2221                 if (err)
2222                         goto err_out;
2223         }
2224
2225         free(ids);
2226         return btf_new;
2227
2228 err_out:
2229         btf__free(btf_new);
2230         free(ids);
2231         errno = -err;
2232         return NULL;
2233 }
2234
2235 /* Create minimized BTF file for a set of BPF objects.
2236  *
2237  * The BTFGen algorithm is divided in two main parts: (1) collect the
2238  * BTF types that are involved in relocations and (2) generate the BTF
2239  * object using the collected types.
2240  *
2241  * In order to collect the types involved in the relocations, we parse
2242  * the BTF and BTF.ext sections of the BPF objects and use
2243  * bpf_core_calc_relo_insn() to get the target specification, this
2244  * indicates how the types and fields are used in a relocation.
2245  *
2246  * Types are recorded in different ways according to the kind of the
2247  * relocation. For field-based relocations only the members that are
2248  * actually used are saved in order to reduce the size of the generated
2249  * BTF file. For type-based relocations empty struct / unions are
2250  * generated and for enum-based relocations the whole type is saved.
2251  *
2252  * The second part of the algorithm generates the BTF object. It creates
2253  * an empty BTF object and fills it with the types recorded in the
2254  * previous step. This function takes care of only adding the structure
2255  * and union members that were marked as used and it also fixes up the
2256  * type IDs on the generated BTF object.
2257  */
2258 static int minimize_btf(const char *src_btf, const char *dst_btf, const char *objspaths[])
2259 {
2260         struct btfgen_info *info;
2261         struct btf *btf_new = NULL;
2262         int err, i;
2263
2264         info = btfgen_new_info(src_btf);
2265         if (!info) {
2266                 err = -errno;
2267                 p_err("failed to allocate info structure: %s", strerror(errno));
2268                 goto out;
2269         }
2270
2271         for (i = 0; objspaths[i] != NULL; i++) {
2272                 err = btfgen_record_obj(info, objspaths[i]);
2273                 if (err) {
2274                         p_err("error recording relocations for %s: %s", objspaths[i],
2275                               strerror(errno));
2276                         goto out;
2277                 }
2278         }
2279
2280         btf_new = btfgen_get_btf(info);
2281         if (!btf_new) {
2282                 err = -errno;
2283                 p_err("error generating BTF: %s", strerror(errno));
2284                 goto out;
2285         }
2286
2287         err = btf_save_raw(btf_new, dst_btf);
2288         if (err) {
2289                 p_err("error saving btf file: %s", strerror(errno));
2290                 goto out;
2291         }
2292
2293 out:
2294         btf__free(btf_new);
2295         btfgen_free_info(info);
2296
2297         return err;
2298 }
2299
2300 static int do_min_core_btf(int argc, char **argv)
2301 {
2302         const char *input, *output, **objs;
2303         int i, err;
2304
2305         if (!REQ_ARGS(3)) {
2306                 usage();
2307                 return -1;
2308         }
2309
2310         input = GET_ARG();
2311         output = GET_ARG();
2312
2313         objs = (const char **) calloc(argc + 1, sizeof(*objs));
2314         if (!objs) {
2315                 p_err("failed to allocate array for object names");
2316                 return -ENOMEM;
2317         }
2318
2319         i = 0;
2320         while (argc)
2321                 objs[i++] = GET_ARG();
2322
2323         err = minimize_btf(input, output, objs);
2324         free(objs);
2325         return err;
2326 }
2327
2328 static const struct cmd cmds[] = {
2329         { "object",             do_object },
2330         { "skeleton",           do_skeleton },
2331         { "subskeleton",        do_subskeleton },
2332         { "min_core_btf",       do_min_core_btf},
2333         { "help",               do_help },
2334         { 0 }
2335 };
2336
2337 int do_gen(int argc, char **argv)
2338 {
2339         return cmd_select(cmds, argc, argv, do_help);
2340 }