tools/lib/bpf/btf.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
ptr_to_u64
btf_add_type
btf_parse_hdr
btf_parse_str_sec
btf_type_size
btf_parse_type_sec
btf__get_nr_types
btf__type_by_id
btf_type_is_void
btf_type_is_void_or_null
btf__resolve_size
btf__resolve_type
btf__find_by_name
btf__free
btf__new
btf_check_endianness
btf__parse_elf
compare_vsi_off
btf_fixup_datasec
btf__finalize_data
btf__load
btf__fd
btf__get_raw_data
btf__name_by_offset
btf__get_from_id
btf__get_map_kv_tids
btf_ext_setup_info
btf_ext_setup_func_info
btf_ext_setup_line_info
btf_ext_setup_offset_reloc
btf_ext_parse_hdr
btf_ext__free
btf_ext__new
btf_ext__get_raw_data
btf_ext_reloc_info
btf_ext__reloc_func_info
btf_ext__reloc_line_info
btf_ext__func_info_rec_size
btf_ext__line_info_rec_size
btf__dedup
hash_combine
btf_dedup_table_add
btf_dedup_hypot_map_add
btf_dedup_clear_hypot_map
btf_dedup_free
btf_dedup_identity_hash_fn
btf_dedup_collision_hash_fn
btf_dedup_equal_fn
btf_dedup_new
btf_for_each_str_off
str_sort_by_content
str_sort_by_offset
btf_dedup_str_ptr_cmp
btf_str_mark_as_used
btf_str_remap_offset
btf_dedup_strings
btf_hash_common
btf_equal_common
btf_hash_int
btf_equal_int
btf_hash_enum
btf_equal_enum
btf_is_enum_fwd
btf_compat_enum
btf_hash_struct
btf_shallow_equal_struct
btf_hash_array
btf_equal_array
btf_compat_array
btf_hash_fnproto
btf_equal_fnproto
btf_compat_fnproto
btf_dedup_prim_type
btf_dedup_prim_types
is_type_mapped
resolve_type_id
resolve_fwd_id
btf_fwd_kind
btf_dedup_is_equiv
btf_dedup_merge_hypot_map
btf_dedup_struct_type
btf_dedup_struct_types
btf_dedup_ref_type
btf_dedup_ref_types
btf_dedup_compact_types
btf_dedup_remap_type_id
btf_dedup_remap_type
btf_dedup_remap_types
   1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
   2 /* Copyright (c) 2018 Facebook */
   3 
   4 #include <endian.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <fcntl.h>
   9 #include <unistd.h>
  10 #include <errno.h>
  11 #include <linux/err.h>
  12 #include <linux/btf.h>
  13 #include <gelf.h>
  14 #include "btf.h"
  15 #include "bpf.h"
  16 #include "libbpf.h"
  17 #include "libbpf_internal.h"
  18 #include "hashmap.h"
  19 
  20 #define BTF_MAX_NR_TYPES 0x7fffffff
  21 #define BTF_MAX_STR_OFFSET 0x7fffffff
  22 
  23 static struct btf_type btf_void;
  24 
  25 struct btf {
  26         union {
  27                 struct btf_header *hdr;
  28                 void *data;
  29         };
  30         struct btf_type **types;
  31         const char *strings;
  32         void *nohdr_data;
  33         __u32 nr_types;
  34         __u32 types_size;
  35         __u32 data_size;
  36         int fd;
  37 };
  38 
  39 static inline __u64 ptr_to_u64(const void *ptr)
  40 {
  41         return (__u64) (unsigned long) ptr;
  42 }
  43 
  44 static int btf_add_type(struct btf *btf, struct btf_type *t)
  45 {
  46         if (btf->types_size - btf->nr_types < 2) {
  47                 struct btf_type **new_types;
  48                 __u32 expand_by, new_size;
  49 
  50                 if (btf->types_size == BTF_MAX_NR_TYPES)
  51                         return -E2BIG;
  52 
  53                 expand_by = max(btf->types_size >> 2, 16);
  54                 new_size = min(BTF_MAX_NR_TYPES, btf->types_size + expand_by);
  55 
  56                 new_types = realloc(btf->types, sizeof(*new_types) * new_size);
  57                 if (!new_types)
  58                         return -ENOMEM;
  59 
  60                 if (btf->nr_types == 0)
  61                         new_types[0] = &btf_void;
  62 
  63                 btf->types = new_types;
  64                 btf->types_size = new_size;
  65         }
  66 
  67         btf->types[++(btf->nr_types)] = t;
  68 
  69         return 0;
  70 }
  71 
  72 static int btf_parse_hdr(struct btf *btf)
  73 {
  74         const struct btf_header *hdr = btf->hdr;
  75         __u32 meta_left;
  76 
  77         if (btf->data_size < sizeof(struct btf_header)) {
  78                 pr_debug("BTF header not found\n");
  79                 return -EINVAL;
  80         }
  81 
  82         if (hdr->magic != BTF_MAGIC) {
  83                 pr_debug("Invalid BTF magic:%x\n", hdr->magic);
  84                 return -EINVAL;
  85         }
  86 
  87         if (hdr->version != BTF_VERSION) {
  88                 pr_debug("Unsupported BTF version:%u\n", hdr->version);
  89                 return -ENOTSUP;
  90         }
  91 
  92         if (hdr->flags) {
  93                 pr_debug("Unsupported BTF flags:%x\n", hdr->flags);
  94                 return -ENOTSUP;
  95         }
  96 
  97         meta_left = btf->data_size - sizeof(*hdr);
  98         if (!meta_left) {
  99                 pr_debug("BTF has no data\n");
 100                 return -EINVAL;
 101         }
 102 
 103         if (meta_left < hdr->type_off) {
 104                 pr_debug("Invalid BTF type section offset:%u\n", hdr->type_off);
 105                 return -EINVAL;
 106         }
 107 
 108         if (meta_left < hdr->str_off) {
 109                 pr_debug("Invalid BTF string section offset:%u\n", hdr->str_off);
 110                 return -EINVAL;
 111         }
 112 
 113         if (hdr->type_off >= hdr->str_off) {
 114                 pr_debug("BTF type section offset >= string section offset. No type?\n");
 115                 return -EINVAL;
 116         }
 117 
 118         if (hdr->type_off & 0x02) {
 119                 pr_debug("BTF type section is not aligned to 4 bytes\n");
 120                 return -EINVAL;
 121         }
 122 
 123         btf->nohdr_data = btf->hdr + 1;
 124 
 125         return 0;
 126 }
 127 
 128 static int btf_parse_str_sec(struct btf *btf)
 129 {
 130         const struct btf_header *hdr = btf->hdr;
 131         const char *start = btf->nohdr_data + hdr->str_off;
 132         const char *end = start + btf->hdr->str_len;
 133 
 134         if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_STR_OFFSET ||
 135             start[0] || end[-1]) {
 136                 pr_debug("Invalid BTF string section\n");
 137                 return -EINVAL;
 138         }
 139 
 140         btf->strings = start;
 141 
 142         return 0;
 143 }
 144 
 145 static int btf_type_size(struct btf_type *t)
 146 {
 147         int base_size = sizeof(struct btf_type);
 148         __u16 vlen = btf_vlen(t);
 149 
 150         switch (btf_kind(t)) {
 151         case BTF_KIND_FWD:
 152         case BTF_KIND_CONST:
 153         case BTF_KIND_VOLATILE:
 154         case BTF_KIND_RESTRICT:
 155         case BTF_KIND_PTR:
 156         case BTF_KIND_TYPEDEF:
 157         case BTF_KIND_FUNC:
 158                 return base_size;
 159         case BTF_KIND_INT:
 160                 return base_size + sizeof(__u32);
 161         case BTF_KIND_ENUM:
 162                 return base_size + vlen * sizeof(struct btf_enum);
 163         case BTF_KIND_ARRAY:
 164                 return base_size + sizeof(struct btf_array);
 165         case BTF_KIND_STRUCT:
 166         case BTF_KIND_UNION:
 167                 return base_size + vlen * sizeof(struct btf_member);
 168         case BTF_KIND_FUNC_PROTO:
 169                 return base_size + vlen * sizeof(struct btf_param);
 170         case BTF_KIND_VAR:
 171                 return base_size + sizeof(struct btf_var);
 172         case BTF_KIND_DATASEC:
 173                 return base_size + vlen * sizeof(struct btf_var_secinfo);
 174         default:
 175                 pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
 176                 return -EINVAL;
 177         }
 178 }
 179 
 180 static int btf_parse_type_sec(struct btf *btf)
 181 {
 182         struct btf_header *hdr = btf->hdr;
 183         void *nohdr_data = btf->nohdr_data;
 184         void *next_type = nohdr_data + hdr->type_off;
 185         void *end_type = nohdr_data + hdr->str_off;
 186 
 187         while (next_type < end_type) {
 188                 struct btf_type *t = next_type;
 189                 int type_size;
 190                 int err;
 191 
 192                 type_size = btf_type_size(t);
 193                 if (type_size < 0)
 194                         return type_size;
 195                 next_type += type_size;
 196                 err = btf_add_type(btf, t);
 197                 if (err)
 198                         return err;
 199         }
 200 
 201         return 0;
 202 }
 203 
 204 __u32 btf__get_nr_types(const struct btf *btf)
 205 {
 206         return btf->nr_types;
 207 }
 208 
 209 const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
 210 {
 211         if (type_id > btf->nr_types)
 212                 return NULL;
 213 
 214         return btf->types[type_id];
 215 }
 216 
 217 static bool btf_type_is_void(const struct btf_type *t)
 218 {
 219         return t == &btf_void || btf_is_fwd(t);
 220 }
 221 
 222 static bool btf_type_is_void_or_null(const struct btf_type *t)
 223 {
 224         return !t || btf_type_is_void(t);
 225 }
 226 
 227 #define MAX_RESOLVE_DEPTH 32
 228 
 229 __s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
 230 {
 231         const struct btf_array *array;
 232         const struct btf_type *t;
 233         __u32 nelems = 1;
 234         __s64 size = -1;
 235         int i;
 236 
 237         t = btf__type_by_id(btf, type_id);
 238         for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t);
 239              i++) {
 240                 switch (btf_kind(t)) {
 241                 case BTF_KIND_INT:
 242                 case BTF_KIND_STRUCT:
 243                 case BTF_KIND_UNION:
 244                 case BTF_KIND_ENUM:
 245                 case BTF_KIND_DATASEC:
 246                         size = t->size;
 247                         goto done;
 248                 case BTF_KIND_PTR:
 249                         size = sizeof(void *);
 250                         goto done;
 251                 case BTF_KIND_TYPEDEF:
 252                 case BTF_KIND_VOLATILE:
 253                 case BTF_KIND_CONST:
 254                 case BTF_KIND_RESTRICT:
 255                 case BTF_KIND_VAR:
 256                         type_id = t->type;
 257                         break;
 258                 case BTF_KIND_ARRAY:
 259                         array = btf_array(t);
 260                         if (nelems && array->nelems > UINT32_MAX / nelems)
 261                                 return -E2BIG;
 262                         nelems *= array->nelems;
 263                         type_id = array->type;
 264                         break;
 265                 default:
 266                         return -EINVAL;
 267                 }
 268 
 269                 t = btf__type_by_id(btf, type_id);
 270         }
 271 
 272 done:
 273         if (size < 0)
 274                 return -EINVAL;
 275         if (nelems && size > UINT32_MAX / nelems)
 276                 return -E2BIG;
 277 
 278         return nelems * size;
 279 }
 280 
 281 int btf__resolve_type(const struct btf *btf, __u32 type_id)
 282 {
 283         const struct btf_type *t;
 284         int depth = 0;
 285 
 286         t = btf__type_by_id(btf, type_id);
 287         while (depth < MAX_RESOLVE_DEPTH &&
 288                !btf_type_is_void_or_null(t) &&
 289                (btf_is_mod(t) || btf_is_typedef(t) || btf_is_var(t))) {
 290                 type_id = t->type;
 291                 t = btf__type_by_id(btf, type_id);
 292                 depth++;
 293         }
 294 
 295         if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
 296                 return -EINVAL;
 297 
 298         return type_id;
 299 }
 300 
 301 __s32 btf__find_by_name(const struct btf *btf, const char *type_name)
 302 {
 303         __u32 i;
 304 
 305         if (!strcmp(type_name, "void"))
 306                 return 0;
 307 
 308         for (i = 1; i <= btf->nr_types; i++) {
 309                 const struct btf_type *t = btf->types[i];
 310                 const char *name = btf__name_by_offset(btf, t->name_off);
 311 
 312                 if (name && !strcmp(type_name, name))
 313                         return i;
 314         }
 315 
 316         return -ENOENT;
 317 }
 318 
 319 void btf__free(struct btf *btf)
 320 {
 321         if (!btf)
 322                 return;
 323 
 324         if (btf->fd != -1)
 325                 close(btf->fd);
 326 
 327         free(btf->data);
 328         free(btf->types);
 329         free(btf);
 330 }
 331 
 332 struct btf *btf__new(__u8 *data, __u32 size)
 333 {
 334         struct btf *btf;
 335         int err;
 336 
 337         btf = calloc(1, sizeof(struct btf));
 338         if (!btf)
 339                 return ERR_PTR(-ENOMEM);
 340 
 341         btf->fd = -1;
 342 
 343         btf->data = malloc(size);
 344         if (!btf->data) {
 345                 err = -ENOMEM;
 346                 goto done;
 347         }
 348 
 349         memcpy(btf->data, data, size);
 350         btf->data_size = size;
 351 
 352         err = btf_parse_hdr(btf);
 353         if (err)
 354                 goto done;
 355 
 356         err = btf_parse_str_sec(btf);
 357         if (err)
 358                 goto done;
 359 
 360         err = btf_parse_type_sec(btf);
 361 
 362 done:
 363         if (err) {
 364                 btf__free(btf);
 365                 return ERR_PTR(err);
 366         }
 367 
 368         return btf;
 369 }
 370 
 371 static bool btf_check_endianness(const GElf_Ehdr *ehdr)
 372 {
 373 #if __BYTE_ORDER == __LITTLE_ENDIAN
 374         return ehdr->e_ident[EI_DATA] == ELFDATA2LSB;
 375 #elif __BYTE_ORDER == __BIG_ENDIAN
 376         return ehdr->e_ident[EI_DATA] == ELFDATA2MSB;
 377 #else
 378 # error "Unrecognized __BYTE_ORDER__"
 379 #endif
 380 }
 381 
 382 struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
 383 {
 384         Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
 385         int err = 0, fd = -1, idx = 0;
 386         struct btf *btf = NULL;
 387         Elf_Scn *scn = NULL;
 388         Elf *elf = NULL;
 389         GElf_Ehdr ehdr;
 390 
 391         if (elf_version(EV_CURRENT) == EV_NONE) {
 392                 pr_warning("failed to init libelf for %s\n", path);
 393                 return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
 394         }
 395 
 396         fd = open(path, O_RDONLY);
 397         if (fd < 0) {
 398                 err = -errno;
 399                 pr_warning("failed to open %s: %s\n", path, strerror(errno));
 400                 return ERR_PTR(err);
 401         }
 402 
 403         err = -LIBBPF_ERRNO__FORMAT;
 404 
 405         elf = elf_begin(fd, ELF_C_READ, NULL);
 406         if (!elf) {
 407                 pr_warning("failed to open %s as ELF file\n", path);
 408                 goto done;
 409         }
 410         if (!gelf_getehdr(elf, &ehdr)) {
 411                 pr_warning("failed to get EHDR from %s\n", path);
 412                 goto done;
 413         }
 414         if (!btf_check_endianness(&ehdr)) {
 415                 pr_warning("non-native ELF endianness is not supported\n");
 416                 goto done;
 417         }
 418         if (!elf_rawdata(elf_getscn(elf, ehdr.e_shstrndx), NULL)) {
 419                 pr_warning("failed to get e_shstrndx from %s\n", path);
 420                 goto done;
 421         }
 422 
 423         while ((scn = elf_nextscn(elf, scn)) != NULL) {
 424                 GElf_Shdr sh;
 425                 char *name;
 426 
 427                 idx++;
 428                 if (gelf_getshdr(scn, &sh) != &sh) {
 429                         pr_warning("failed to get section(%d) header from %s\n",
 430                                    idx, path);
 431                         goto done;
 432                 }
 433                 name = elf_strptr(elf, ehdr.e_shstrndx, sh.sh_name);
 434                 if (!name) {
 435                         pr_warning("failed to get section(%d) name from %s\n",
 436                                    idx, path);
 437                         goto done;
 438                 }
 439                 if (strcmp(name, BTF_ELF_SEC) == 0) {
 440                         btf_data = elf_getdata(scn, 0);
 441                         if (!btf_data) {
 442                                 pr_warning("failed to get section(%d, %s) data from %s\n",
 443                                            idx, name, path);
 444                                 goto done;
 445                         }
 446                         continue;
 447                 } else if (btf_ext && strcmp(name, BTF_EXT_ELF_SEC) == 0) {
 448                         btf_ext_data = elf_getdata(scn, 0);
 449                         if (!btf_ext_data) {
 450                                 pr_warning("failed to get section(%d, %s) data from %s\n",
 451                                            idx, name, path);
 452                                 goto done;
 453                         }
 454                         continue;
 455                 }
 456         }
 457 
 458         err = 0;
 459 
 460         if (!btf_data) {
 461                 err = -ENOENT;
 462                 goto done;
 463         }
 464         btf = btf__new(btf_data->d_buf, btf_data->d_size);
 465         if (IS_ERR(btf))
 466                 goto done;
 467 
 468         if (btf_ext && btf_ext_data) {
 469                 *btf_ext = btf_ext__new(btf_ext_data->d_buf,
 470                                         btf_ext_data->d_size);
 471                 if (IS_ERR(*btf_ext))
 472                         goto done;
 473         } else if (btf_ext) {
 474                 *btf_ext = NULL;
 475         }
 476 done:
 477         if (elf)
 478                 elf_end(elf);
 479         close(fd);
 480 
 481         if (err)
 482                 return ERR_PTR(err);
 483         /*
 484          * btf is always parsed before btf_ext, so no need to clean up
 485          * btf_ext, if btf loading failed
 486          */
 487         if (IS_ERR(btf))
 488                 return btf;
 489         if (btf_ext && IS_ERR(*btf_ext)) {
 490                 btf__free(btf);
 491                 err = PTR_ERR(*btf_ext);
 492                 return ERR_PTR(err);
 493         }
 494         return btf;
 495 }
 496 
 497 static int compare_vsi_off(const void *_a, const void *_b)
 498 {
 499         const struct btf_var_secinfo *a = _a;
 500         const struct btf_var_secinfo *b = _b;
 501 
 502         return a->offset - b->offset;
 503 }
 504 
 505 static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
 506                              struct btf_type *t)
 507 {
 508         __u32 size = 0, off = 0, i, vars = btf_vlen(t);
 509         const char *name = btf__name_by_offset(btf, t->name_off);
 510         const struct btf_type *t_var;
 511         struct btf_var_secinfo *vsi;
 512         const struct btf_var *var;
 513         int ret;
 514 
 515         if (!name) {
 516                 pr_debug("No name found in string section for DATASEC kind.\n");
 517                 return -ENOENT;
 518         }
 519 
 520         ret = bpf_object__section_size(obj, name, &size);
 521         if (ret || !size || (t->size && t->size != size)) {
 522                 pr_debug("Invalid size for section %s: %u bytes\n", name, size);
 523                 return -ENOENT;
 524         }
 525 
 526         t->size = size;
 527 
 528         for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
 529                 t_var = btf__type_by_id(btf, vsi->type);
 530                 var = btf_var(t_var);
 531 
 532                 if (!btf_is_var(t_var)) {
 533                         pr_debug("Non-VAR type seen in section %s\n", name);
 534                         return -EINVAL;
 535                 }
 536 
 537                 if (var->linkage == BTF_VAR_STATIC)
 538                         continue;
 539 
 540                 name = btf__name_by_offset(btf, t_var->name_off);
 541                 if (!name) {
 542                         pr_debug("No name found in string section for VAR kind\n");
 543                         return -ENOENT;
 544                 }
 545 
 546                 ret = bpf_object__variable_offset(obj, name, &off);
 547                 if (ret) {
 548                         pr_debug("No offset found in symbol table for VAR %s\n",
 549                                  name);
 550                         return -ENOENT;
 551                 }
 552 
 553                 vsi->offset = off;
 554         }
 555 
 556         qsort(t + 1, vars, sizeof(*vsi), compare_vsi_off);
 557         return 0;
 558 }
 559 
 560 int btf__finalize_data(struct bpf_object *obj, struct btf *btf)
 561 {
 562         int err = 0;
 563         __u32 i;
 564 
 565         for (i = 1; i <= btf->nr_types; i++) {
 566                 struct btf_type *t = btf->types[i];
 567 
 568                 /* Loader needs to fix up some of the things compiler
 569                  * couldn't get its hands on while emitting BTF. This
 570                  * is section size and global variable offset. We use
 571                  * the info from the ELF itself for this purpose.
 572                  */
 573                 if (btf_is_datasec(t)) {
 574                         err = btf_fixup_datasec(obj, btf, t);
 575                         if (err)
 576                                 break;
 577                 }
 578         }
 579 
 580         return err;
 581 }
 582 
 583 int btf__load(struct btf *btf)
 584 {
 585         __u32 log_buf_size = BPF_LOG_BUF_SIZE;
 586         char *log_buf = NULL;
 587         int err = 0;
 588 
 589         if (btf->fd >= 0)
 590                 return -EEXIST;
 591 
 592         log_buf = malloc(log_buf_size);
 593         if (!log_buf)
 594                 return -ENOMEM;
 595 
 596         *log_buf = 0;
 597 
 598         btf->fd = bpf_load_btf(btf->data, btf->data_size,
 599                                log_buf, log_buf_size, false);
 600         if (btf->fd < 0) {
 601                 err = -errno;
 602                 pr_warning("Error loading BTF: %s(%d)\n", strerror(errno), errno);
 603                 if (*log_buf)
 604                         pr_warning("%s\n", log_buf);
 605                 goto done;
 606         }
 607 
 608 done:
 609         free(log_buf);
 610         return err;
 611 }
 612 
 613 int btf__fd(const struct btf *btf)
 614 {
 615         return btf->fd;
 616 }
 617 
 618 const void *btf__get_raw_data(const struct btf *btf, __u32 *size)
 619 {
 620         *size = btf->data_size;
 621         return btf->data;
 622 }
 623 
 624 const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
 625 {
 626         if (offset < btf->hdr->str_len)
 627                 return &btf->strings[offset];
 628         else
 629                 return NULL;
 630 }
 631 
 632 int btf__get_from_id(__u32 id, struct btf **btf)
 633 {
 634         struct bpf_btf_info btf_info = { 0 };
 635         __u32 len = sizeof(btf_info);
 636         __u32 last_size;
 637         int btf_fd;
 638         void *ptr;
 639         int err;
 640 
 641         err = 0;
 642         *btf = NULL;
 643         btf_fd = bpf_btf_get_fd_by_id(id);
 644         if (btf_fd < 0)
 645                 return 0;
 646 
 647         /* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so
 648          * let's start with a sane default - 4KiB here - and resize it only if
 649          * bpf_obj_get_info_by_fd() needs a bigger buffer.
 650          */
 651         btf_info.btf_size = 4096;
 652         last_size = btf_info.btf_size;
 653         ptr = malloc(last_size);
 654         if (!ptr) {
 655                 err = -ENOMEM;
 656                 goto exit_free;
 657         }
 658 
 659         memset(ptr, 0, last_size);
 660         btf_info.btf = ptr_to_u64(ptr);
 661         err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
 662 
 663         if (!err && btf_info.btf_size > last_size) {
 664                 void *temp_ptr;
 665 
 666                 last_size = btf_info.btf_size;
 667                 temp_ptr = realloc(ptr, last_size);
 668                 if (!temp_ptr) {
 669                         err = -ENOMEM;
 670                         goto exit_free;
 671                 }
 672                 ptr = temp_ptr;
 673                 memset(ptr, 0, last_size);
 674                 btf_info.btf = ptr_to_u64(ptr);
 675                 err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
 676         }
 677 
 678         if (err || btf_info.btf_size > last_size) {
 679                 err = errno;
 680                 goto exit_free;
 681         }
 682 
 683         *btf = btf__new((__u8 *)(long)btf_info.btf, btf_info.btf_size);
 684         if (IS_ERR(*btf)) {
 685                 err = PTR_ERR(*btf);
 686                 *btf = NULL;
 687         }
 688 
 689 exit_free:
 690         close(btf_fd);
 691         free(ptr);
 692 
 693         return err;
 694 }
 695 
 696 int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
 697                          __u32 expected_key_size, __u32 expected_value_size,
 698                          __u32 *key_type_id, __u32 *value_type_id)
 699 {
 700         const struct btf_type *container_type;
 701         const struct btf_member *key, *value;
 702         const size_t max_name = 256;
 703         char container_name[max_name];
 704         __s64 key_size, value_size;
 705         __s32 container_id;
 706 
 707         if (snprintf(container_name, max_name, "____btf_map_%s", map_name) ==
 708             max_name) {
 709                 pr_warning("map:%s length of '____btf_map_%s' is too long\n",
 710                            map_name, map_name);
 711                 return -EINVAL;
 712         }
 713 
 714         container_id = btf__find_by_name(btf, container_name);
 715         if (container_id < 0) {
 716                 pr_debug("map:%s container_name:%s cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?\n",
 717                          map_name, container_name);
 718                 return container_id;
 719         }
 720 
 721         container_type = btf__type_by_id(btf, container_id);
 722         if (!container_type) {
 723                 pr_warning("map:%s cannot find BTF type for container_id:%u\n",
 724                            map_name, container_id);
 725                 return -EINVAL;
 726         }
 727 
 728         if (!btf_is_struct(container_type) || btf_vlen(container_type) < 2) {
 729                 pr_warning("map:%s container_name:%s is an invalid container struct\n",
 730                            map_name, container_name);
 731                 return -EINVAL;
 732         }
 733 
 734         key = btf_members(container_type);
 735         value = key + 1;
 736 
 737         key_size = btf__resolve_size(btf, key->type);
 738         if (key_size < 0) {
 739                 pr_warning("map:%s invalid BTF key_type_size\n", map_name);
 740                 return key_size;
 741         }
 742 
 743         if (expected_key_size != key_size) {
 744                 pr_warning("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
 745                            map_name, (__u32)key_size, expected_key_size);
 746                 return -EINVAL;
 747         }
 748 
 749         value_size = btf__resolve_size(btf, value->type);
 750         if (value_size < 0) {
 751                 pr_warning("map:%s invalid BTF value_type_size\n", map_name);
 752                 return value_size;
 753         }
 754 
 755         if (expected_value_size != value_size) {
 756                 pr_warning("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
 757                            map_name, (__u32)value_size, expected_value_size);
 758                 return -EINVAL;
 759         }
 760 
 761         *key_type_id = key->type;
 762         *value_type_id = value->type;
 763 
 764         return 0;
 765 }
 766 
 767 struct btf_ext_sec_setup_param {
 768         __u32 off;
 769         __u32 len;
 770         __u32 min_rec_size;
 771         struct btf_ext_info *ext_info;
 772         const char *desc;
 773 };
 774 
 775 static int btf_ext_setup_info(struct btf_ext *btf_ext,
 776                               struct btf_ext_sec_setup_param *ext_sec)
 777 {
 778         const struct btf_ext_info_sec *sinfo;
 779         struct btf_ext_info *ext_info;
 780         __u32 info_left, record_size;
 781         /* The start of the info sec (including the __u32 record_size). */
 782         void *info;
 783 
 784         if (ext_sec->len == 0)
 785                 return 0;
 786 
 787         if (ext_sec->off & 0x03) {
 788                 pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
 789                      ext_sec->desc);
 790                 return -EINVAL;
 791         }
 792 
 793         info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;
 794         info_left = ext_sec->len;
 795 
 796         if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {
 797                 pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
 798                          ext_sec->desc, ext_sec->off, ext_sec->len);
 799                 return -EINVAL;
 800         }
 801 
 802         /* At least a record size */
 803         if (info_left < sizeof(__u32)) {
 804                 pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
 805                 return -EINVAL;
 806         }
 807 
 808         /* The record size needs to meet the minimum standard */
 809         record_size = *(__u32 *)info;
 810         if (record_size < ext_sec->min_rec_size ||
 811             record_size & 0x03) {
 812                 pr_debug("%s section in .BTF.ext has invalid record size %u\n",
 813                          ext_sec->desc, record_size);
 814                 return -EINVAL;
 815         }
 816 
 817         sinfo = info + sizeof(__u32);
 818         info_left -= sizeof(__u32);
 819 
 820         /* If no records, return failure now so .BTF.ext won't be used. */
 821         if (!info_left) {
 822                 pr_debug("%s section in .BTF.ext has no records", ext_sec->desc);
 823                 return -EINVAL;
 824         }
 825 
 826         while (info_left) {
 827                 unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
 828                 __u64 total_record_size;
 829                 __u32 num_records;
 830 
 831                 if (info_left < sec_hdrlen) {
 832                         pr_debug("%s section header is not found in .BTF.ext\n",
 833                              ext_sec->desc);
 834                         return -EINVAL;
 835                 }
 836 
 837                 num_records = sinfo->num_info;
 838                 if (num_records == 0) {
 839                         pr_debug("%s section has incorrect num_records in .BTF.ext\n",
 840                              ext_sec->desc);
 841                         return -EINVAL;
 842                 }
 843 
 844                 total_record_size = sec_hdrlen +
 845                                     (__u64)num_records * record_size;
 846                 if (info_left < total_record_size) {
 847                         pr_debug("%s section has incorrect num_records in .BTF.ext\n",
 848                              ext_sec->desc);
 849                         return -EINVAL;
 850                 }
 851 
 852                 info_left -= total_record_size;
 853                 sinfo = (void *)sinfo + total_record_size;
 854         }
 855 
 856         ext_info = ext_sec->ext_info;
 857         ext_info->len = ext_sec->len - sizeof(__u32);
 858         ext_info->rec_size = record_size;
 859         ext_info->info = info + sizeof(__u32);
 860 
 861         return 0;
 862 }
 863 
 864 static int btf_ext_setup_func_info(struct btf_ext *btf_ext)
 865 {
 866         struct btf_ext_sec_setup_param param = {
 867                 .off = btf_ext->hdr->func_info_off,
 868                 .len = btf_ext->hdr->func_info_len,
 869                 .min_rec_size = sizeof(struct bpf_func_info_min),
 870                 .ext_info = &btf_ext->func_info,
 871                 .desc = "func_info"
 872         };
 873 
 874         return btf_ext_setup_info(btf_ext, &param);
 875 }
 876 
 877 static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
 878 {
 879         struct btf_ext_sec_setup_param param = {
 880                 .off = btf_ext->hdr->line_info_off,
 881                 .len = btf_ext->hdr->line_info_len,
 882                 .min_rec_size = sizeof(struct bpf_line_info_min),
 883                 .ext_info = &btf_ext->line_info,
 884                 .desc = "line_info",
 885         };
 886 
 887         return btf_ext_setup_info(btf_ext, &param);
 888 }
 889 
 890 static int btf_ext_setup_offset_reloc(struct btf_ext *btf_ext)
 891 {
 892         struct btf_ext_sec_setup_param param = {
 893                 .off = btf_ext->hdr->offset_reloc_off,
 894                 .len = btf_ext->hdr->offset_reloc_len,
 895                 .min_rec_size = sizeof(struct bpf_offset_reloc),
 896                 .ext_info = &btf_ext->offset_reloc_info,
 897                 .desc = "offset_reloc",
 898         };
 899 
 900         return btf_ext_setup_info(btf_ext, &param);
 901 }
 902 
 903 static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
 904 {
 905         const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
 906 
 907         if (data_size < offsetofend(struct btf_ext_header, hdr_len) ||
 908             data_size < hdr->hdr_len) {
 909                 pr_debug("BTF.ext header not found");
 910                 return -EINVAL;
 911         }
 912 
 913         if (hdr->magic != BTF_MAGIC) {
 914                 pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic);
 915                 return -EINVAL;
 916         }
 917 
 918         if (hdr->version != BTF_VERSION) {
 919                 pr_debug("Unsupported BTF.ext version:%u\n", hdr->version);
 920                 return -ENOTSUP;
 921         }
 922 
 923         if (hdr->flags) {
 924                 pr_debug("Unsupported BTF.ext flags:%x\n", hdr->flags);
 925                 return -ENOTSUP;
 926         }
 927 
 928         if (data_size == hdr->hdr_len) {
 929                 pr_debug("BTF.ext has no data\n");
 930                 return -EINVAL;
 931         }
 932 
 933         return 0;
 934 }
 935 
 936 void btf_ext__free(struct btf_ext *btf_ext)
 937 {
 938         if (!btf_ext)
 939                 return;
 940         free(btf_ext->data);
 941         free(btf_ext);
 942 }
 943 
 944 struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
 945 {
 946         struct btf_ext *btf_ext;
 947         int err;
 948 
 949         err = btf_ext_parse_hdr(data, size);
 950         if (err)
 951                 return ERR_PTR(err);
 952 
 953         btf_ext = calloc(1, sizeof(struct btf_ext));
 954         if (!btf_ext)
 955                 return ERR_PTR(-ENOMEM);
 956 
 957         btf_ext->data_size = size;
 958         btf_ext->data = malloc(size);
 959         if (!btf_ext->data) {
 960                 err = -ENOMEM;
 961                 goto done;
 962         }
 963         memcpy(btf_ext->data, data, size);
 964 
 965         if (btf_ext->hdr->hdr_len <
 966             offsetofend(struct btf_ext_header, line_info_len))
 967                 goto done;
 968         err = btf_ext_setup_func_info(btf_ext);
 969         if (err)
 970                 goto done;
 971 
 972         err = btf_ext_setup_line_info(btf_ext);
 973         if (err)
 974                 goto done;
 975 
 976         if (btf_ext->hdr->hdr_len <
 977             offsetofend(struct btf_ext_header, offset_reloc_len))
 978                 goto done;
 979         err = btf_ext_setup_offset_reloc(btf_ext);
 980         if (err)
 981                 goto done;
 982 
 983 done:
 984         if (err) {
 985                 btf_ext__free(btf_ext);
 986                 return ERR_PTR(err);
 987         }
 988 
 989         return btf_ext;
 990 }
 991 
 992 const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size)
 993 {
 994         *size = btf_ext->data_size;
 995         return btf_ext->data;
 996 }
 997 
 998 static int btf_ext_reloc_info(const struct btf *btf,
 999                               const struct btf_ext_info *ext_info,
1000                               const char *sec_name, __u32 insns_cnt,
1001                               void **info, __u32 *cnt)
1002 {
1003         __u32 sec_hdrlen = sizeof(struct btf_ext_info_sec);
1004         __u32 i, record_size, existing_len, records_len;
1005         struct btf_ext_info_sec *sinfo;
1006         const char *info_sec_name;
1007         __u64 remain_len;
1008         void *data;
1009 
1010         record_size = ext_info->rec_size;
1011         sinfo = ext_info->info;
1012         remain_len = ext_info->len;
1013         while (remain_len > 0) {
1014                 records_len = sinfo->num_info * record_size;
1015                 info_sec_name = btf__name_by_offset(btf, sinfo->sec_name_off);
1016                 if (strcmp(info_sec_name, sec_name)) {
1017                         remain_len -= sec_hdrlen + records_len;
1018                         sinfo = (void *)sinfo + sec_hdrlen + records_len;
1019                         continue;
1020                 }
1021 
1022                 existing_len = (*cnt) * record_size;
1023                 data = realloc(*info, existing_len + records_len);
1024                 if (!data)
1025                         return -ENOMEM;
1026 
1027                 memcpy(data + existing_len, sinfo->data, records_len);
1028                 /* adjust insn_off only, the rest data will be passed
1029                  * to the kernel.
1030                  */
1031                 for (i = 0; i < sinfo->num_info; i++) {
1032                         __u32 *insn_off;
1033 
1034                         insn_off = data + existing_len + (i * record_size);
1035                         *insn_off = *insn_off / sizeof(struct bpf_insn) +
1036                                 insns_cnt;
1037                 }
1038                 *info = data;
1039                 *cnt += sinfo->num_info;
1040                 return 0;
1041         }
1042 
1043         return -ENOENT;
1044 }
1045 
1046 int btf_ext__reloc_func_info(const struct btf *btf,
1047                              const struct btf_ext *btf_ext,
1048                              const char *sec_name, __u32 insns_cnt,
1049                              void **func_info, __u32 *cnt)
1050 {
1051         return btf_ext_reloc_info(btf, &btf_ext->func_info, sec_name,
1052                                   insns_cnt, func_info, cnt);
1053 }
1054 
1055 int btf_ext__reloc_line_info(const struct btf *btf,
1056                              const struct btf_ext *btf_ext,
1057                              const char *sec_name, __u32 insns_cnt,
1058                              void **line_info, __u32 *cnt)
1059 {
1060         return btf_ext_reloc_info(btf, &btf_ext->line_info, sec_name,
1061                                   insns_cnt, line_info, cnt);
1062 }
1063 
1064 __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext)
1065 {
1066         return btf_ext->func_info.rec_size;
1067 }
1068 
1069 __u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext)
1070 {
1071         return btf_ext->line_info.rec_size;
1072 }
1073 
1074 struct btf_dedup;
1075 
1076 static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
1077                                        const struct btf_dedup_opts *opts);
1078 static void btf_dedup_free(struct btf_dedup *d);
1079 static int btf_dedup_strings(struct btf_dedup *d);
1080 static int btf_dedup_prim_types(struct btf_dedup *d);
1081 static int btf_dedup_struct_types(struct btf_dedup *d);
1082 static int btf_dedup_ref_types(struct btf_dedup *d);
1083 static int btf_dedup_compact_types(struct btf_dedup *d);
1084 static int btf_dedup_remap_types(struct btf_dedup *d);
1085 
1086 /*
1087  * Deduplicate BTF types and strings.
1088  *
1089  * BTF dedup algorithm takes as an input `struct btf` representing `.BTF` ELF
1090  * section with all BTF type descriptors and string data. It overwrites that
1091  * memory in-place with deduplicated types and strings without any loss of
1092  * information. If optional `struct btf_ext` representing '.BTF.ext' ELF section
1093  * is provided, all the strings referenced from .BTF.ext section are honored
1094  * and updated to point to the right offsets after deduplication.
1095  *
1096  * If function returns with error, type/string data might be garbled and should
1097  * be discarded.
1098  *
1099  * More verbose and detailed description of both problem btf_dedup is solving,
1100  * as well as solution could be found at:
1101  * https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
1102  *
1103  * Problem description and justification
1104  * =====================================
1105  *
1106  * BTF type information is typically emitted either as a result of conversion
1107  * from DWARF to BTF or directly by compiler. In both cases, each compilation
1108  * unit contains information about a subset of all the types that are used
1109  * in an application. These subsets are frequently overlapping and contain a lot
1110  * of duplicated information when later concatenated together into a single
1111  * binary. This algorithm ensures that each unique type is represented by single
1112  * BTF type descriptor, greatly reducing resulting size of BTF data.
1113  *
1114  * Compilation unit isolation and subsequent duplication of data is not the only
1115  * problem. The same type hierarchy (e.g., struct and all the type that struct
1116  * references) in different compilation units can be represented in BTF to
1117  * various degrees of completeness (or, rather, incompleteness) due to
1118  * struct/union forward declarations.
1119  *
1120  * Let's take a look at an example, that we'll use to better understand the
1121  * problem (and solution). Suppose we have two compilation units, each using
1122  * same `struct S`, but each of them having incomplete type information about
1123  * struct's fields:
1124  *
1125  * // CU #1:
1126  * struct S;
1127  * struct A {
1128  *      int a;
1129  *      struct A* self;
1130  *      struct S* parent;
1131  * };
1132  * struct B;
1133  * struct S {
1134  *      struct A* a_ptr;
1135  *      struct B* b_ptr;
1136  * };
1137  *
1138  * // CU #2:
1139  * struct S;
1140  * struct A;
1141  * struct B {
1142  *      int b;
1143  *      struct B* self;
1144  *      struct S* parent;
1145  * };
1146  * struct S {
1147  *      struct A* a_ptr;
1148  *      struct B* b_ptr;
1149  * };
1150  *
1151  * In case of CU #1, BTF data will know only that `struct B` exist (but no
1152  * more), but will know the complete type information about `struct A`. While
1153  * for CU #2, it will know full type information about `struct B`, but will
1154  * only know about forward declaration of `struct A` (in BTF terms, it will
1155  * have `BTF_KIND_FWD` type descriptor with name `B`).
1156  *
1157  * This compilation unit isolation means that it's possible that there is no
1158  * single CU with complete type information describing structs `S`, `A`, and
1159  * `B`. Also, we might get tons of duplicated and redundant type information.
1160  *
1161  * Additional complication we need to keep in mind comes from the fact that
1162  * types, in general, can form graphs containing cycles, not just DAGs.
1163  *
1164  * While algorithm does deduplication, it also merges and resolves type
1165  * information (unless disabled throught `struct btf_opts`), whenever possible.
1166  * E.g., in the example above with two compilation units having partial type
1167  * information for structs `A` and `B`, the output of algorithm will emit
1168  * a single copy of each BTF type that describes structs `A`, `B`, and `S`
1169  * (as well as type information for `int` and pointers), as if they were defined
1170  * in a single compilation unit as:
1171  *
1172  * struct A {
1173  *      int a;
1174  *      struct A* self;
1175  *      struct S* parent;
1176  * };
1177  * struct B {
1178  *      int b;
1179  *      struct B* self;
1180  *      struct S* parent;
1181  * };
1182  * struct S {
1183  *      struct A* a_ptr;
1184  *      struct B* b_ptr;
1185  * };
1186  *
1187  * Algorithm summary
1188  * =================
1189  *
1190  * Algorithm completes its work in 6 separate passes:
1191  *
1192  * 1. Strings deduplication.
1193  * 2. Primitive types deduplication (int, enum, fwd).
1194  * 3. Struct/union types deduplication.
1195  * 4. Reference types deduplication (pointers, typedefs, arrays, funcs, func
1196  *    protos, and const/volatile/restrict modifiers).
1197  * 5. Types compaction.
1198  * 6. Types remapping.
1199  *
1200  * Algorithm determines canonical type descriptor, which is a single
1201  * representative type for each truly unique type. This canonical type is the
1202  * one that will go into final deduplicated BTF type information. For
1203  * struct/unions, it is also the type that algorithm will merge additional type
1204  * information into (while resolving FWDs), as it discovers it from data in
1205  * other CUs. Each input BTF type eventually gets either mapped to itself, if
1206  * that type is canonical, or to some other type, if that type is equivalent
1207  * and was chosen as canonical representative. This mapping is stored in
1208  * `btf_dedup->map` array. This map is also used to record STRUCT/UNION that
1209  * FWD type got resolved to.
1210  *
1211  * To facilitate fast discovery of canonical types, we also maintain canonical
1212  * index (`btf_dedup->dedup_table`), which maps type descriptor's signature hash
1213  * (i.e., hashed kind, name, size, fields, etc) into a list of canonical types
1214  * that match that signature. With sufficiently good choice of type signature
1215  * hashing function, we can limit number of canonical types for each unique type
1216  * signature to a very small number, allowing to find canonical type for any
1217  * duplicated type very quickly.
1218  *
1219  * Struct/union deduplication is the most critical part and algorithm for
1220  * deduplicating structs/unions is described in greater details in comments for
1221  * `btf_dedup_is_equiv` function.
1222  */
1223 int btf__dedup(struct btf *btf, struct btf_ext *btf_ext,
1224                const struct btf_dedup_opts *opts)
1225 {
1226         struct btf_dedup *d = btf_dedup_new(btf, btf_ext, opts);
1227         int err;
1228 
1229         if (IS_ERR(d)) {
1230                 pr_debug("btf_dedup_new failed: %ld", PTR_ERR(d));
1231                 return -EINVAL;
1232         }
1233 
1234         err = btf_dedup_strings(d);
1235         if (err < 0) {
1236                 pr_debug("btf_dedup_strings failed:%d\n", err);
1237                 goto done;
1238         }
1239         err = btf_dedup_prim_types(d);
1240         if (err < 0) {
1241                 pr_debug("btf_dedup_prim_types failed:%d\n", err);
1242                 goto done;
1243         }
1244         err = btf_dedup_struct_types(d);
1245         if (err < 0) {
1246                 pr_debug("btf_dedup_struct_types failed:%d\n", err);
1247                 goto done;
1248         }
1249         err = btf_dedup_ref_types(d);
1250         if (err < 0) {
1251                 pr_debug("btf_dedup_ref_types failed:%d\n", err);
1252                 goto done;
1253         }
1254         err = btf_dedup_compact_types(d);
1255         if (err < 0) {
1256                 pr_debug("btf_dedup_compact_types failed:%d\n", err);
1257                 goto done;
1258         }
1259         err = btf_dedup_remap_types(d);
1260         if (err < 0) {
1261                 pr_debug("btf_dedup_remap_types failed:%d\n", err);
1262                 goto done;
1263         }
1264 
1265 done:
1266         btf_dedup_free(d);
1267         return err;
1268 }
1269 
1270 #define BTF_UNPROCESSED_ID ((__u32)-1)
1271 #define BTF_IN_PROGRESS_ID ((__u32)-2)
1272 
1273 struct btf_dedup {
1274         /* .BTF section to be deduped in-place */
1275         struct btf *btf;
1276         /*
1277          * Optional .BTF.ext section. When provided, any strings referenced
1278          * from it will be taken into account when deduping strings
1279          */
1280         struct btf_ext *btf_ext;
1281         /*
1282          * This is a map from any type's signature hash to a list of possible
1283          * canonical representative type candidates. Hash collisions are
1284          * ignored, so even types of various kinds can share same list of
1285          * candidates, which is fine because we rely on subsequent
1286          * btf_xxx_equal() checks to authoritatively verify type equality.
1287          */
1288         struct hashmap *dedup_table;
1289         /* Canonical types map */
1290         __u32 *map;
1291         /* Hypothetical mapping, used during type graph equivalence checks */
1292         __u32 *hypot_map;
1293         __u32 *hypot_list;
1294         size_t hypot_cnt;
1295         size_t hypot_cap;
1296         /* Various option modifying behavior of algorithm */
1297         struct btf_dedup_opts opts;
1298 };
1299 
1300 struct btf_str_ptr {
1301         const char *str;
1302         __u32 new_off;
1303         bool used;
1304 };
1305 
1306 struct btf_str_ptrs {
1307         struct btf_str_ptr *ptrs;
1308         const char *data;
1309         __u32 cnt;
1310         __u32 cap;
1311 };
1312 
1313 static long hash_combine(long h, long value)
1314 {
1315         return h * 31 + value;
1316 }
1317 
1318 #define for_each_dedup_cand(d, node, hash) \
1319         hashmap__for_each_key_entry(d->dedup_table, node, (void *)hash)
1320 
1321 static int btf_dedup_table_add(struct btf_dedup *d, long hash, __u32 type_id)
1322 {
1323         return hashmap__append(d->dedup_table,
1324                                (void *)hash, (void *)(long)type_id);
1325 }
1326 
1327 static int btf_dedup_hypot_map_add(struct btf_dedup *d,
1328                                    __u32 from_id, __u32 to_id)
1329 {
1330         if (d->hypot_cnt == d->hypot_cap) {
1331                 __u32 *new_list;
1332 
1333                 d->hypot_cap += max(16, d->hypot_cap / 2);
1334                 new_list = realloc(d->hypot_list, sizeof(__u32) * d->hypot_cap);
1335                 if (!new_list)
1336                         return -ENOMEM;
1337                 d->hypot_list = new_list;
1338         }
1339         d->hypot_list[d->hypot_cnt++] = from_id;
1340         d->hypot_map[from_id] = to_id;
1341         return 0;
1342 }
1343 
1344 static void btf_dedup_clear_hypot_map(struct btf_dedup *d)
1345 {
1346         int i;
1347 
1348         for (i = 0; i < d->hypot_cnt; i++)
1349                 d->hypot_map[d->hypot_list[i]] = BTF_UNPROCESSED_ID;
1350         d->hypot_cnt = 0;
1351 }
1352 
1353 static void btf_dedup_free(struct btf_dedup *d)
1354 {
1355         hashmap__free(d->dedup_table);
1356         d->dedup_table = NULL;
1357 
1358         free(d->map);
1359         d->map = NULL;
1360 
1361         free(d->hypot_map);
1362         d->hypot_map = NULL;
1363 
1364         free(d->hypot_list);
1365         d->hypot_list = NULL;
1366 
1367         free(d);
1368 }
1369 
1370 static size_t btf_dedup_identity_hash_fn(const void *key, void *ctx)
1371 {
1372         return (size_t)key;
1373 }
1374 
1375 static size_t btf_dedup_collision_hash_fn(const void *key, void *ctx)
1376 {
1377         return 0;
1378 }
1379 
1380 static bool btf_dedup_equal_fn(const void *k1, const void *k2, void *ctx)
1381 {
1382         return k1 == k2;
1383 }
1384 
1385 static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
1386                                        const struct btf_dedup_opts *opts)
1387 {
1388         struct btf_dedup *d = calloc(1, sizeof(struct btf_dedup));
1389         hashmap_hash_fn hash_fn = btf_dedup_identity_hash_fn;
1390         int i, err = 0;
1391 
1392         if (!d)
1393                 return ERR_PTR(-ENOMEM);
1394 
1395         d->opts.dont_resolve_fwds = opts && opts->dont_resolve_fwds;
1396         /* dedup_table_size is now used only to force collisions in tests */
1397         if (opts && opts->dedup_table_size == 1)
1398                 hash_fn = btf_dedup_collision_hash_fn;
1399 
1400         d->btf = btf;
1401         d->btf_ext = btf_ext;
1402 
1403         d->dedup_table = hashmap__new(hash_fn, btf_dedup_equal_fn, NULL);
1404         if (IS_ERR(d->dedup_table)) {
1405                 err = PTR_ERR(d->dedup_table);
1406                 d->dedup_table = NULL;
1407                 goto done;
1408         }
1409 
1410         d->map = malloc(sizeof(__u32) * (1 + btf->nr_types));
1411         if (!d->map) {
1412                 err = -ENOMEM;
1413                 goto done;
1414         }
1415         /* special BTF "void" type is made canonical immediately */
1416         d->map[0] = 0;
1417         for (i = 1; i <= btf->nr_types; i++) {
1418                 struct btf_type *t = d->btf->types[i];
1419 
1420                 /* VAR and DATASEC are never deduped and are self-canonical */
1421                 if (btf_is_var(t) || btf_is_datasec(t))
1422                         d->map[i] = i;
1423                 else
1424                         d->map[i] = BTF_UNPROCESSED_ID;
1425         }
1426 
1427         d->hypot_map = malloc(sizeof(__u32) * (1 + btf->nr_types));
1428         if (!d->hypot_map) {
1429                 err = -ENOMEM;
1430                 goto done;
1431         }
1432         for (i = 0; i <= btf->nr_types; i++)
1433                 d->hypot_map[i] = BTF_UNPROCESSED_ID;
1434 
1435 done:
1436         if (err) {
1437                 btf_dedup_free(d);
1438                 return ERR_PTR(err);
1439         }
1440 
1441         return d;
1442 }
1443 
1444 typedef int (*str_off_fn_t)(__u32 *str_off_ptr, void *ctx);
1445 
1446 /*
1447  * Iterate over all possible places in .BTF and .BTF.ext that can reference
1448  * string and pass pointer to it to a provided callback `fn`.
1449  */
1450 static int btf_for_each_str_off(struct btf_dedup *d, str_off_fn_t fn, void *ctx)
1451 {
1452         void *line_data_cur, *line_data_end;
1453         int i, j, r, rec_size;
1454         struct btf_type *t;
1455 
1456         for (i = 1; i <= d->btf->nr_types; i++) {
1457                 t = d->btf->types[i];
1458                 r = fn(&t->name_off, ctx);
1459                 if (r)
1460                         return r;
1461 
1462                 switch (btf_kind(t)) {
1463                 case BTF_KIND_STRUCT:
1464                 case BTF_KIND_UNION: {
1465                         struct btf_member *m = btf_members(t);
1466                         __u16 vlen = btf_vlen(t);
1467 
1468                         for (j = 0; j < vlen; j++) {
1469                                 r = fn(&m->name_off, ctx);
1470                                 if (r)
1471                                         return r;
1472                                 m++;
1473                         }
1474                         break;
1475                 }
1476                 case BTF_KIND_ENUM: {
1477                         struct btf_enum *m = btf_enum(t);
1478                         __u16 vlen = btf_vlen(t);
1479 
1480                         for (j = 0; j < vlen; j++) {
1481                                 r = fn(&m->name_off, ctx);
1482                                 if (r)
1483                                         return r;
1484                                 m++;
1485                         }
1486                         break;
1487                 }
1488                 case BTF_KIND_FUNC_PROTO: {
1489                         struct btf_param *m = btf_params(t);
1490                         __u16 vlen = btf_vlen(t);
1491 
1492                         for (j = 0; j < vlen; j++) {
1493                                 r = fn(&m->name_off, ctx);
1494                                 if (r)
1495                                         return r;
1496                                 m++;
1497                         }
1498                         break;
1499                 }
1500                 default:
1501                         break;
1502                 }
1503         }
1504 
1505         if (!d->btf_ext)
1506                 return 0;
1507 
1508         line_data_cur = d->btf_ext->line_info.info;
1509         line_data_end = d->btf_ext->line_info.info + d->btf_ext->line_info.len;
1510         rec_size = d->btf_ext->line_info.rec_size;
1511 
1512         while (line_data_cur < line_data_end) {
1513                 struct btf_ext_info_sec *sec = line_data_cur;
1514                 struct bpf_line_info_min *line_info;
1515                 __u32 num_info = sec->num_info;
1516 
1517                 r = fn(&sec->sec_name_off, ctx);
1518                 if (r)
1519                         return r;
1520 
1521                 line_data_cur += sizeof(struct btf_ext_info_sec);
1522                 for (i = 0; i < num_info; i++) {
1523                         line_info = line_data_cur;
1524                         r = fn(&line_info->file_name_off, ctx);
1525                         if (r)
1526                                 return r;
1527                         r = fn(&line_info->line_off, ctx);
1528                         if (r)
1529                                 return r;
1530                         line_data_cur += rec_size;
1531                 }
1532         }
1533 
1534         return 0;
1535 }
1536 
1537 static int str_sort_by_content(const void *a1, const void *a2)
1538 {
1539         const struct btf_str_ptr *p1 = a1;
1540         const struct btf_str_ptr *p2 = a2;
1541 
1542         return strcmp(p1->str, p2->str);
1543 }
1544 
1545 static int str_sort_by_offset(const void *a1, const void *a2)
1546 {
1547         const struct btf_str_ptr *p1 = a1;
1548         const struct btf_str_ptr *p2 = a2;
1549 
1550         if (p1->str != p2->str)
1551                 return p1->str < p2->str ? -1 : 1;
1552         return 0;
1553 }
1554 
1555 static int btf_dedup_str_ptr_cmp(const void *str_ptr, const void *pelem)
1556 {
1557         const struct btf_str_ptr *p = pelem;
1558 
1559         if (str_ptr != p->str)
1560                 return (const char *)str_ptr < p->str ? -1 : 1;
1561         return 0;
1562 }
1563 
1564 static int btf_str_mark_as_used(__u32 *str_off_ptr, void *ctx)
1565 {
1566         struct btf_str_ptrs *strs;
1567         struct btf_str_ptr *s;
1568 
1569         if (*str_off_ptr == 0)
1570                 return 0;
1571 
1572         strs = ctx;
1573         s = bsearch(strs->data + *str_off_ptr, strs->ptrs, strs->cnt,
1574                     sizeof(struct btf_str_ptr), btf_dedup_str_ptr_cmp);
1575         if (!s)
1576                 return -EINVAL;
1577         s->used = true;
1578         return 0;
1579 }
1580 
1581 static int btf_str_remap_offset(__u32 *str_off_ptr, void *ctx)
1582 {
1583         struct btf_str_ptrs *strs;
1584         struct btf_str_ptr *s;
1585 
1586         if (*str_off_ptr == 0)
1587                 return 0;
1588 
1589         strs = ctx;
1590         s = bsearch(strs->data + *str_off_ptr, strs->ptrs, strs->cnt,
1591                     sizeof(struct btf_str_ptr), btf_dedup_str_ptr_cmp);
1592         if (!s)
1593                 return -EINVAL;
1594         *str_off_ptr = s->new_off;
1595         return 0;
1596 }
1597 
1598 /*
1599  * Dedup string and filter out those that are not referenced from either .BTF
1600  * or .BTF.ext (if provided) sections.
1601  *
1602  * This is done by building index of all strings in BTF's string section,
1603  * then iterating over all entities that can reference strings (e.g., type
1604  * names, struct field names, .BTF.ext line info, etc) and marking corresponding
1605  * strings as used. After that all used strings are deduped and compacted into
1606  * sequential blob of memory and new offsets are calculated. Then all the string
1607  * references are iterated again and rewritten using new offsets.
1608  */
1609 static int btf_dedup_strings(struct btf_dedup *d)
1610 {
1611         const struct btf_header *hdr = d->btf->hdr;
1612         char *start = (char *)d->btf->nohdr_data + hdr->str_off;
1613         char *end = start + d->btf->hdr->str_len;
1614         char *p = start, *tmp_strs = NULL;
1615         struct btf_str_ptrs strs = {
1616                 .cnt = 0,
1617                 .cap = 0,
1618                 .ptrs = NULL,
1619                 .data = start,
1620         };
1621         int i, j, err = 0, grp_idx;
1622         bool grp_used;
1623 
1624         /* build index of all strings */
1625         while (p < end) {
1626                 if (strs.cnt + 1 > strs.cap) {
1627                         struct btf_str_ptr *new_ptrs;
1628 
1629                         strs.cap += max(strs.cnt / 2, 16);
1630                         new_ptrs = realloc(strs.ptrs,
1631                                            sizeof(strs.ptrs[0]) * strs.cap);
1632                         if (!new_ptrs) {
1633                                 err = -ENOMEM;
1634                                 goto done;
1635                         }
1636                         strs.ptrs = new_ptrs;
1637                 }
1638 
1639                 strs.ptrs[strs.cnt].str = p;
1640                 strs.ptrs[strs.cnt].used = false;
1641 
1642                 p += strlen(p) + 1;
1643                 strs.cnt++;
1644         }
1645 
1646         /* temporary storage for deduplicated strings */
1647         tmp_strs = malloc(d->btf->hdr->str_len);
1648         if (!tmp_strs) {
1649                 err = -ENOMEM;
1650                 goto done;
1651         }
1652 
1653         /* mark all used strings */
1654         strs.ptrs[0].used = true;
1655         err = btf_for_each_str_off(d, btf_str_mark_as_used, &strs);
1656         if (err)
1657                 goto done;
1658 
1659         /* sort strings by context, so that we can identify duplicates */
1660         qsort(strs.ptrs, strs.cnt, sizeof(strs.ptrs[0]), str_sort_by_content);
1661 
1662         /*
1663          * iterate groups of equal strings and if any instance in a group was
1664          * referenced, emit single instance and remember new offset
1665          */
1666         p = tmp_strs;
1667         grp_idx = 0;
1668         grp_used = strs.ptrs[0].used;
1669         /* iterate past end to avoid code duplication after loop */
1670         for (i = 1; i <= strs.cnt; i++) {
1671                 /*
1672                  * when i == strs.cnt, we want to skip string comparison and go
1673                  * straight to handling last group of strings (otherwise we'd
1674                  * need to handle last group after the loop w/ duplicated code)
1675                  */
1676                 if (i < strs.cnt &&
1677                     !strcmp(strs.ptrs[i].str, strs.ptrs[grp_idx].str)) {
1678                         grp_used = grp_used || strs.ptrs[i].used;
1679                         continue;
1680                 }
1681 
1682                 /*
1683                  * this check would have been required after the loop to handle
1684                  * last group of strings, but due to <= condition in a loop
1685                  * we avoid that duplication
1686                  */
1687                 if (grp_used) {
1688                         int new_off = p - tmp_strs;
1689                         __u32 len = strlen(strs.ptrs[grp_idx].str);
1690 
1691                         memmove(p, strs.ptrs[grp_idx].str, len + 1);
1692                         for (j = grp_idx; j < i; j++)
1693                                 strs.ptrs[j].new_off = new_off;
1694                         p += len + 1;
1695                 }
1696 
1697                 if (i < strs.cnt) {
1698                         grp_idx = i;
1699                         grp_used = strs.ptrs[i].used;
1700                 }
1701         }
1702 
1703         /* replace original strings with deduped ones */
1704         d->btf->hdr->str_len = p - tmp_strs;
1705         memmove(start, tmp_strs, d->btf->hdr->str_len);
1706         end = start + d->btf->hdr->str_len;
1707 
1708         /* restore original order for further binary search lookups */
1709         qsort(strs.ptrs, strs.cnt, sizeof(strs.ptrs[0]), str_sort_by_offset);
1710 
1711         /* remap string offsets */
1712         err = btf_for_each_str_off(d, btf_str_remap_offset, &strs);
1713         if (err)
1714                 goto done;
1715 
1716         d->btf->hdr->str_len = end - start;
1717 
1718 done:
1719         free(tmp_strs);
1720         free(strs.ptrs);
1721         return err;
1722 }
1723 
1724 static long btf_hash_common(struct btf_type *t)
1725 {
1726         long h;
1727 
1728         h = hash_combine(0, t->name_off);
1729         h = hash_combine(h, t->info);
1730         h = hash_combine(h, t->size);
1731         return h;
1732 }
1733 
1734 static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
1735 {
1736         return t1->name_off == t2->name_off &&
1737                t1->info == t2->info &&
1738                t1->size == t2->size;
1739 }
1740 
1741 /* Calculate type signature hash of INT. */
1742 static long btf_hash_int(struct btf_type *t)
1743 {
1744         __u32 info = *(__u32 *)(t + 1);
1745         long h;
1746 
1747         h = btf_hash_common(t);
1748         h = hash_combine(h, info);
1749         return h;
1750 }
1751 
1752 /* Check structural equality of two INTs. */
1753 static bool btf_equal_int(struct btf_type *t1, struct btf_type *t2)
1754 {
1755         __u32 info1, info2;
1756 
1757         if (!btf_equal_common(t1, t2))
1758                 return false;
1759         info1 = *(__u32 *)(t1 + 1);
1760         info2 = *(__u32 *)(t2 + 1);
1761         return info1 == info2;
1762 }
1763 
1764 /* Calculate type signature hash of ENUM. */
1765 static long btf_hash_enum(struct btf_type *t)
1766 {
1767         long h;
1768 
1769         /* don't hash vlen and enum members to support enum fwd resolving */
1770         h = hash_combine(0, t->name_off);
1771         h = hash_combine(h, t->info & ~0xffff);
1772         h = hash_combine(h, t->size);
1773         return h;
1774 }
1775 
1776 /* Check structural equality of two ENUMs. */
1777 static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
1778 {
1779         const struct btf_enum *m1, *m2;
1780         __u16 vlen;
1781         int i;
1782 
1783         if (!btf_equal_common(t1, t2))
1784                 return false;
1785 
1786         vlen = btf_vlen(t1);
1787         m1 = btf_enum(t1);
1788         m2 = btf_enum(t2);
1789         for (i = 0; i < vlen; i++) {
1790                 if (m1->name_off != m2->name_off || m1->val != m2->val)
1791                         return false;
1792                 m1++;
1793                 m2++;
1794         }
1795         return true;
1796 }
1797 
1798 static inline bool btf_is_enum_fwd(struct btf_type *t)
1799 {
1800         return btf_is_enum(t) && btf_vlen(t) == 0;
1801 }
1802 
1803 static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
1804 {
1805         if (!btf_is_enum_fwd(t1) && !btf_is_enum_fwd(t2))
1806                 return btf_equal_enum(t1, t2);
1807         /* ignore vlen when comparing */
1808         return t1->name_off == t2->name_off &&
1809                (t1->info & ~0xffff) == (t2->info & ~0xffff) &&
1810                t1->size == t2->size;
1811 }
1812 
1813 /*
1814  * Calculate type signature hash of STRUCT/UNION, ignoring referenced type IDs,
1815  * as referenced type IDs equivalence is established separately during type
1816  * graph equivalence check algorithm.
1817  */
1818 static long btf_hash_struct(struct btf_type *t)
1819 {
1820         const struct btf_member *member = btf_members(t);
1821         __u32 vlen = btf_vlen(t);
1822         long h = btf_hash_common(t);
1823         int i;
1824 
1825         for (i = 0; i < vlen; i++) {
1826                 h = hash_combine(h, member->name_off);
1827                 h = hash_combine(h, member->offset);
1828                 /* no hashing of referenced type ID, it can be unresolved yet */
1829                 member++;
1830         }
1831         return h;
1832 }
1833 
1834 /*
1835  * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
1836  * IDs. This check is performed during type graph equivalence check and
1837  * referenced types equivalence is checked separately.
1838  */
1839 static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
1840 {
1841         const struct btf_member *m1, *m2;
1842         __u16 vlen;
1843         int i;
1844 
1845         if (!btf_equal_common(t1, t2))
1846                 return false;
1847 
1848         vlen = btf_vlen(t1);
1849         m1 = btf_members(t1);
1850         m2 = btf_members(t2);
1851         for (i = 0; i < vlen; i++) {
1852                 if (m1->name_off != m2->name_off || m1->offset != m2->offset)
1853                         return false;
1854                 m1++;
1855                 m2++;
1856         }
1857         return true;
1858 }
1859 
1860 /*
1861  * Calculate type signature hash of ARRAY, including referenced type IDs,
1862  * under assumption that they were already resolved to canonical type IDs and
1863  * are not going to change.
1864  */
1865 static long btf_hash_array(struct btf_type *t)
1866 {
1867         const struct btf_array *info = btf_array(t);
1868         long h = btf_hash_common(t);
1869 
1870         h = hash_combine(h, info->type);
1871         h = hash_combine(h, info->index_type);
1872         h = hash_combine(h, info->nelems);
1873         return h;
1874 }
1875 
1876 /*
1877  * Check exact equality of two ARRAYs, taking into account referenced
1878  * type IDs, under assumption that they were already resolved to canonical
1879  * type IDs and are not going to change.
1880  * This function is called during reference types deduplication to compare
1881  * ARRAY to potential canonical representative.
1882  */
1883 static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
1884 {
1885         const struct btf_array *info1, *info2;
1886 
1887         if (!btf_equal_common(t1, t2))
1888                 return false;
1889 
1890         info1 = btf_array(t1);
1891         info2 = btf_array(t2);
1892         return info1->type == info2->type &&
1893                info1->index_type == info2->index_type &&
1894                info1->nelems == info2->nelems;
1895 }
1896 
1897 /*
1898  * Check structural compatibility of two ARRAYs, ignoring referenced type
1899  * IDs. This check is performed during type graph equivalence check and
1900  * referenced types equivalence is checked separately.
1901  */
1902 static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
1903 {
1904         if (!btf_equal_common(t1, t2))
1905                 return false;
1906 
1907         return btf_array(t1)->nelems == btf_array(t2)->nelems;
1908 }
1909 
1910 /*
1911  * Calculate type signature hash of FUNC_PROTO, including referenced type IDs,
1912  * under assumption that they were already resolved to canonical type IDs and
1913  * are not going to change.
1914  */
1915 static long btf_hash_fnproto(struct btf_type *t)
1916 {
1917         const struct btf_param *member = btf_params(t);
1918         __u16 vlen = btf_vlen(t);
1919         long h = btf_hash_common(t);
1920         int i;
1921 
1922         for (i = 0; i < vlen; i++) {
1923                 h = hash_combine(h, member->name_off);
1924                 h = hash_combine(h, member->type);
1925                 member++;
1926         }
1927         return h;
1928 }
1929 
1930 /*
1931  * Check exact equality of two FUNC_PROTOs, taking into account referenced
1932  * type IDs, under assumption that they were already resolved to canonical
1933  * type IDs and are not going to change.
1934  * This function is called during reference types deduplication to compare
1935  * FUNC_PROTO to potential canonical representative.
1936  */
1937 static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
1938 {
1939         const struct btf_param *m1, *m2;
1940         __u16 vlen;
1941         int i;
1942 
1943         if (!btf_equal_common(t1, t2))
1944                 return false;
1945 
1946         vlen = btf_vlen(t1);
1947         m1 = btf_params(t1);
1948         m2 = btf_params(t2);
1949         for (i = 0; i < vlen; i++) {
1950                 if (m1->name_off != m2->name_off || m1->type != m2->type)
1951                         return false;
1952                 m1++;
1953                 m2++;
1954         }
1955         return true;
1956 }
1957 
1958 /*
1959  * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
1960  * IDs. This check is performed during type graph equivalence check and
1961  * referenced types equivalence is checked separately.
1962  */
1963 static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
1964 {
1965         const struct btf_param *m1, *m2;
1966         __u16 vlen;
1967         int i;
1968 
1969         /* skip return type ID */
1970         if (t1->name_off != t2->name_off || t1->info != t2->info)
1971                 return false;
1972 
1973         vlen = btf_vlen(t1);
1974         m1 = btf_params(t1);
1975         m2 = btf_params(t2);
1976         for (i = 0; i < vlen; i++) {
1977                 if (m1->name_off != m2->name_off)
1978                         return false;
1979                 m1++;
1980                 m2++;
1981         }
1982         return true;
1983 }
1984 
1985 /*
1986  * Deduplicate primitive types, that can't reference other types, by calculating
1987  * their type signature hash and comparing them with any possible canonical
1988  * candidate. If no canonical candidate matches, type itself is marked as
1989  * canonical and is added into `btf_dedup->dedup_table` as another candidate.
1990  */
1991 static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
1992 {
1993         struct btf_type *t = d->btf->types[type_id];
1994         struct hashmap_entry *hash_entry;
1995         struct btf_type *cand;
1996         /* if we don't find equivalent type, then we are canonical */
1997         __u32 new_id = type_id;
1998         __u32 cand_id;
1999         long h;
2000 
2001         switch (btf_kind(t)) {
2002         case BTF_KIND_CONST:
2003         case BTF_KIND_VOLATILE:
2004         case BTF_KIND_RESTRICT:
2005         case BTF_KIND_PTR:
2006         case BTF_KIND_TYPEDEF:
2007         case BTF_KIND_ARRAY:
2008         case BTF_KIND_STRUCT:
2009         case BTF_KIND_UNION:
2010         case BTF_KIND_FUNC:
2011         case BTF_KIND_FUNC_PROTO:
2012         case BTF_KIND_VAR:
2013         case BTF_KIND_DATASEC:
2014                 return 0;
2015 
2016         case BTF_KIND_INT:
2017                 h = btf_hash_int(t);
2018                 for_each_dedup_cand(d, hash_entry, h) {
2019                         cand_id = (__u32)(long)hash_entry->value;
2020                         cand = d->btf->types[cand_id];
2021                         if (btf_equal_int(t, cand)) {
2022                                 new_id = cand_id;
2023                                 break;
2024                         }
2025                 }
2026                 break;
2027 
2028         case BTF_KIND_ENUM:
2029                 h = btf_hash_enum(t);
2030                 for_each_dedup_cand(d, hash_entry, h) {
2031                         cand_id = (__u32)(long)hash_entry->value;
2032                         cand = d->btf->types[cand_id];
2033                         if (btf_equal_enum(t, cand)) {
2034                                 new_id = cand_id;
2035                                 break;
2036                         }
2037                         if (d->opts.dont_resolve_fwds)
2038                                 continue;
2039                         if (btf_compat_enum(t, cand)) {
2040                                 if (btf_is_enum_fwd(t)) {
2041                                         /* resolve fwd to full enum */
2042                                         new_id = cand_id;
2043                                         break;
2044                                 }
2045                                 /* resolve canonical enum fwd to full enum */
2046                                 d->map[cand_id] = type_id;
2047                         }
2048                 }
2049                 break;
2050 
2051         case BTF_KIND_FWD:
2052                 h = btf_hash_common(t);
2053                 for_each_dedup_cand(d, hash_entry, h) {
2054                         cand_id = (__u32)(long)hash_entry->value;
2055                         cand = d->btf->types[cand_id];
2056                         if (btf_equal_common(t, cand)) {
2057                                 new_id = cand_id;
2058                                 break;
2059                         }
2060                 }
2061                 break;
2062 
2063         default:
2064                 return -EINVAL;
2065         }
2066 
2067         d->map[type_id] = new_id;
2068         if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
2069                 return -ENOMEM;
2070 
2071         return 0;
2072 }
2073 
2074 static int btf_dedup_prim_types(struct btf_dedup *d)
2075 {
2076         int i, err;
2077 
2078         for (i = 1; i <= d->btf->nr_types; i++) {
2079                 err = btf_dedup_prim_type(d, i);
2080                 if (err)
2081                         return err;
2082         }
2083         return 0;
2084 }
2085 
2086 /*
2087  * Check whether type is already mapped into canonical one (could be to itself).
2088  */
2089 static inline bool is_type_mapped(struct btf_dedup *d, uint32_t type_id)
2090 {
2091         return d->map[type_id] <= BTF_MAX_NR_TYPES;
2092 }
2093 
2094 /*
2095  * Resolve type ID into its canonical type ID, if any; otherwise return original
2096  * type ID. If type is FWD and is resolved into STRUCT/UNION already, follow
2097  * STRUCT/UNION link and resolve it into canonical type ID as well.
2098  */
2099 static inline __u32 resolve_type_id(struct btf_dedup *d, __u32 type_id)
2100 {
2101         while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
2102                 type_id = d->map[type_id];
2103         return type_id;
2104 }
2105 
2106 /*
2107  * Resolve FWD to underlying STRUCT/UNION, if any; otherwise return original
2108  * type ID.
2109  */
2110 static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
2111 {
2112         __u32 orig_type_id = type_id;
2113 
2114         if (!btf_is_fwd(d->btf->types[type_id]))
2115                 return type_id;
2116 
2117         while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
2118                 type_id = d->map[type_id];
2119 
2120         if (!btf_is_fwd(d->btf->types[type_id]))
2121                 return type_id;
2122 
2123         return orig_type_id;
2124 }
2125 
2126 
2127 static inline __u16 btf_fwd_kind(struct btf_type *t)
2128 {
2129         return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
2130 }
2131 
2132 /*
2133  * Check equivalence of BTF type graph formed by candidate struct/union (we'll
2134  * call it "candidate graph" in this description for brevity) to a type graph
2135  * formed by (potential) canonical struct/union ("canonical graph" for brevity
2136  * here, though keep in mind that not all types in canonical graph are
2137  * necessarily canonical representatives themselves, some of them might be
2138  * duplicates or its uniqueness might not have been established yet).
2139  * Returns:
2140  *  - >0, if type graphs are equivalent;
2141  *  -  0, if not equivalent;
2142  *  - <0, on error.
2143  *
2144  * Algorithm performs side-by-side DFS traversal of both type graphs and checks
2145  * equivalence of BTF types at each step. If at any point BTF types in candidate
2146  * and canonical graphs are not compatible structurally, whole graphs are
2147  * incompatible. If types are structurally equivalent (i.e., all information
2148  * except referenced type IDs is exactly the same), a mapping from `canon_id` to
2149  * a `cand_id` is recored in hypothetical mapping (`btf_dedup->hypot_map`).
2150  * If a type references other types, then those referenced types are checked
2151  * for equivalence recursively.
2152  *
2153  * During DFS traversal, if we find that for current `canon_id` type we
2154  * already have some mapping in hypothetical map, we check for two possible
2155  * situations:
2156  *   - `canon_id` is mapped to exactly the same type as `cand_id`. This will
2157  *     happen when type graphs have cycles. In this case we assume those two
2158  *     types are equivalent.
2159  *   - `canon_id` is mapped to different type. This is contradiction in our
2160  *     hypothetical mapping, because same graph in canonical graph corresponds
2161  *     to two different types in candidate graph, which for equivalent type
2162  *     graphs shouldn't happen. This condition terminates equivalence check
2163  *     with negative result.
2164  *
2165  * If type graphs traversal exhausts types to check and find no contradiction,
2166  * then type graphs are equivalent.
2167  *
2168  * When checking types for equivalence, there is one special case: FWD types.
2169  * If FWD type resolution is allowed and one of the types (either from canonical
2170  * or candidate graph) is FWD and other is STRUCT/UNION (depending on FWD's kind
2171  * flag) and their names match, hypothetical mapping is updated to point from
2172  * FWD to STRUCT/UNION. If graphs will be determined as equivalent successfully,
2173  * this mapping will be used to record FWD -> STRUCT/UNION mapping permanently.
2174  *
2175  * Technically, this could lead to incorrect FWD to STRUCT/UNION resolution,
2176  * if there are two exactly named (or anonymous) structs/unions that are
2177  * compatible structurally, one of which has FWD field, while other is concrete
2178  * STRUCT/UNION, but according to C sources they are different structs/unions
2179  * that are referencing different types with the same name. This is extremely
2180  * unlikely to happen, but btf_dedup API allows to disable FWD resolution if
2181  * this logic is causing problems.
2182  *
2183  * Doing FWD resolution means that both candidate and/or canonical graphs can
2184  * consists of portions of the graph that come from multiple compilation units.
2185  * This is due to the fact that types within single compilation unit are always
2186  * deduplicated and FWDs are already resolved, if referenced struct/union
2187  * definiton is available. So, if we had unresolved FWD and found corresponding
2188  * STRUCT/UNION, they will be from different compilation units. This
2189  * consequently means that when we "link" FWD to corresponding STRUCT/UNION,
2190  * type graph will likely have at least two different BTF types that describe
2191  * same type (e.g., most probably there will be two different BTF types for the
2192  * same 'int' primitive type) and could even have "overlapping" parts of type
2193  * graph that describe same subset of types.
2194  *
2195  * This in turn means that our assumption that each type in canonical graph
2196  * must correspond to exactly one type in candidate graph might not hold
2197  * anymore and will make it harder to detect contradictions using hypothetical
2198  * map. To handle this problem, we allow to follow FWD -> STRUCT/UNION
2199  * resolution only in canonical graph. FWDs in candidate graphs are never
2200  * resolved. To see why it's OK, let's check all possible situations w.r.t. FWDs
2201  * that can occur:
2202  *   - Both types in canonical and candidate graphs are FWDs. If they are
2203  *     structurally equivalent, then they can either be both resolved to the
2204  *     same STRUCT/UNION or not resolved at all. In both cases they are
2205  *     equivalent and there is no need to resolve FWD on candidate side.
2206  *   - Both types in canonical and candidate graphs are concrete STRUCT/UNION,
2207  *     so nothing to resolve as well, algorithm will check equivalence anyway.
2208  *   - Type in canonical graph is FWD, while type in candidate is concrete
2209  *     STRUCT/UNION. In this case candidate graph comes from single compilation
2210  *     unit, so there is exactly one BTF type for each unique C type. After
2211  *     resolving FWD into STRUCT/UNION, there might be more than one BTF type
2212  *     in canonical graph mapping to single BTF type in candidate graph, but
2213  *     because hypothetical mapping maps from canonical to candidate types, it's
2214  *     alright, and we still maintain the property of having single `canon_id`
2215  *     mapping to single `cand_id` (there could be two different `canon_id`
2216  *     mapped to the same `cand_id`, but it's not contradictory).
2217  *   - Type in canonical graph is concrete STRUCT/UNION, while type in candidate
2218  *     graph is FWD. In this case we are just going to check compatibility of
2219  *     STRUCT/UNION and corresponding FWD, and if they are compatible, we'll
2220  *     assume that whatever STRUCT/UNION FWD resolves to must be equivalent to
2221  *     a concrete STRUCT/UNION from canonical graph. If the rest of type graphs
2222  *     turn out equivalent, we'll re-resolve FWD to concrete STRUCT/UNION from
2223  *     canonical graph.
2224  */
2225 static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
2226                               __u32 canon_id)
2227 {
2228         struct btf_type *cand_type;
2229         struct btf_type *canon_type;
2230         __u32 hypot_type_id;
2231         __u16 cand_kind;
2232         __u16 canon_kind;
2233         int i, eq;
2234 
2235         /* if both resolve to the same canonical, they must be equivalent */
2236         if (resolve_type_id(d, cand_id) == resolve_type_id(d, canon_id))
2237                 return 1;
2238 
2239         canon_id = resolve_fwd_id(d, canon_id);
2240 
2241         hypot_type_id = d->hypot_map[canon_id];
2242         if (hypot_type_id <= BTF_MAX_NR_TYPES)
2243                 return hypot_type_id == cand_id;
2244 
2245         if (btf_dedup_hypot_map_add(d, canon_id, cand_id))
2246                 return -ENOMEM;
2247 
2248         cand_type = d->btf->types[cand_id];
2249         canon_type = d->btf->types[canon_id];
2250         cand_kind = btf_kind(cand_type);
2251         canon_kind = btf_kind(canon_type);
2252 
2253         if (cand_type->name_off != canon_type->name_off)
2254                 return 0;
2255 
2256         /* FWD <--> STRUCT/UNION equivalence check, if enabled */
2257         if (!d->opts.dont_resolve_fwds
2258             && (cand_kind == BTF_KIND_FWD || canon_kind == BTF_KIND_FWD)
2259             && cand_kind != canon_kind) {
2260                 __u16 real_kind;
2261                 __u16 fwd_kind;
2262 
2263                 if (cand_kind == BTF_KIND_FWD) {
2264                         real_kind = canon_kind;
2265                         fwd_kind = btf_fwd_kind(cand_type);
2266                 } else {
2267                         real_kind = cand_kind;
2268                         fwd_kind = btf_fwd_kind(canon_type);
2269                 }
2270                 return fwd_kind == real_kind;
2271         }
2272 
2273         if (cand_kind != canon_kind)
2274                 return 0;
2275 
2276         switch (cand_kind) {
2277         case BTF_KIND_INT:
2278                 return btf_equal_int(cand_type, canon_type);
2279 
2280         case BTF_KIND_ENUM:
2281                 if (d->opts.dont_resolve_fwds)
2282                         return btf_equal_enum(cand_type, canon_type);
2283                 else
2284                         return btf_compat_enum(cand_type, canon_type);
2285 
2286         case BTF_KIND_FWD:
2287                 return btf_equal_common(cand_type, canon_type);
2288 
2289         case BTF_KIND_CONST:
2290         case BTF_KIND_VOLATILE:
2291         case BTF_KIND_RESTRICT:
2292         case BTF_KIND_PTR:
2293         case BTF_KIND_TYPEDEF:
2294         case BTF_KIND_FUNC:
2295                 if (cand_type->info != canon_type->info)
2296                         return 0;
2297                 return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
2298 
2299         case BTF_KIND_ARRAY: {
2300                 const struct btf_array *cand_arr, *canon_arr;
2301 
2302                 if (!btf_compat_array(cand_type, canon_type))
2303                         return 0;
2304                 cand_arr = btf_array(cand_type);
2305                 canon_arr = btf_array(canon_type);
2306                 eq = btf_dedup_is_equiv(d,
2307                         cand_arr->index_type, canon_arr->index_type);
2308                 if (eq <= 0)
2309                         return eq;
2310                 return btf_dedup_is_equiv(d, cand_arr->type, canon_arr->type);
2311         }
2312 
2313         case BTF_KIND_STRUCT:
2314         case BTF_KIND_UNION: {
2315                 const struct btf_member *cand_m, *canon_m;
2316                 __u16 vlen;
2317 
2318                 if (!btf_shallow_equal_struct(cand_type, canon_type))
2319                         return 0;
2320                 vlen = btf_vlen(cand_type);
2321                 cand_m = btf_members(cand_type);
2322                 canon_m = btf_members(canon_type);
2323                 for (i = 0; i < vlen; i++) {
2324                         eq = btf_dedup_is_equiv(d, cand_m->type, canon_m->type);
2325                         if (eq <= 0)
2326                                 return eq;
2327                         cand_m++;
2328                         canon_m++;
2329                 }
2330 
2331                 return 1;
2332         }
2333 
2334         case BTF_KIND_FUNC_PROTO: {
2335                 const struct btf_param *cand_p, *canon_p;
2336                 __u16 vlen;
2337 
2338                 if (!btf_compat_fnproto(cand_type, canon_type))
2339                         return 0;
2340                 eq = btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
2341                 if (eq <= 0)
2342                         return eq;
2343                 vlen = btf_vlen(cand_type);
2344                 cand_p = btf_params(cand_type);
2345                 canon_p = btf_params(canon_type);
2346                 for (i = 0; i < vlen; i++) {
2347                         eq = btf_dedup_is_equiv(d, cand_p->type, canon_p->type);
2348                         if (eq <= 0)
2349                                 return eq;
2350                         cand_p++;
2351                         canon_p++;
2352                 }
2353                 return 1;
2354         }
2355 
2356         default:
2357                 return -EINVAL;
2358         }
2359         return 0;
2360 }
2361 
2362 /*
2363  * Use hypothetical mapping, produced by successful type graph equivalence
2364  * check, to augment existing struct/union canonical mapping, where possible.
2365  *
2366  * If BTF_KIND_FWD resolution is allowed, this mapping is also used to record
2367  * FWD -> STRUCT/UNION correspondence as well. FWD resolution is bidirectional:
2368  * it doesn't matter if FWD type was part of canonical graph or candidate one,
2369  * we are recording the mapping anyway. As opposed to carefulness required
2370  * for struct/union correspondence mapping (described below), for FWD resolution
2371  * it's not important, as by the time that FWD type (reference type) will be
2372  * deduplicated all structs/unions will be deduped already anyway.
2373  *
2374  * Recording STRUCT/UNION mapping is purely a performance optimization and is
2375  * not required for correctness. It needs to be done carefully to ensure that
2376  * struct/union from candidate's type graph is not mapped into corresponding
2377  * struct/union from canonical type graph that itself hasn't been resolved into
2378  * canonical representative. The only guarantee we have is that canonical
2379  * struct/union was determined as canonical and that won't change. But any
2380  * types referenced through that struct/union fields could have been not yet
2381  * resolved, so in case like that it's too early to establish any kind of
2382  * correspondence between structs/unions.
2383  *
2384  * No canonical correspondence is derived for primitive types (they are already
2385  * deduplicated completely already anyway) or reference types (they rely on
2386  * stability of struct/union canonical relationship for equivalence checks).
2387  */
2388 static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
2389 {
2390         __u32 cand_type_id, targ_type_id;
2391         __u16 t_kind, c_kind;
2392         __u32 t_id, c_id;
2393         int i;
2394 
2395         for (i = 0; i < d->hypot_cnt; i++) {
2396                 cand_type_id = d->hypot_list[i];
2397                 targ_type_id = d->hypot_map[cand_type_id];
2398                 t_id = resolve_type_id(d, targ_type_id);
2399                 c_id = resolve_type_id(d, cand_type_id);
2400                 t_kind = btf_kind(d->btf->types[t_id]);
2401                 c_kind = btf_kind(d->btf->types[c_id]);
2402                 /*
2403                  * Resolve FWD into STRUCT/UNION.
2404                  * It's ok to resolve FWD into STRUCT/UNION that's not yet
2405                  * mapped to canonical representative (as opposed to
2406                  * STRUCT/UNION <--> STRUCT/UNION mapping logic below), because
2407                  * eventually that struct is going to be mapped and all resolved
2408                  * FWDs will automatically resolve to correct canonical
2409                  * representative. This will happen before ref type deduping,
2410                  * which critically depends on stability of these mapping. This
2411                  * stability is not a requirement for STRUCT/UNION equivalence
2412                  * checks, though.
2413                  */
2414                 if (t_kind != BTF_KIND_FWD && c_kind == BTF_KIND_FWD)
2415                         d->map[c_id] = t_id;
2416                 else if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD)
2417                         d->map[t_id] = c_id;
2418 
2419                 if ((t_kind == BTF_KIND_STRUCT || t_kind == BTF_KIND_UNION) &&
2420                     c_kind != BTF_KIND_FWD &&
2421                     is_type_mapped(d, c_id) &&
2422                     !is_type_mapped(d, t_id)) {
2423                         /*
2424                          * as a perf optimization, we can map struct/union
2425                          * that's part of type graph we just verified for
2426                          * equivalence. We can do that for struct/union that has
2427                          * canonical representative only, though.
2428                          */
2429                         d->map[t_id] = c_id;
2430                 }
2431         }
2432 }
2433 
2434 /*
2435  * Deduplicate struct/union types.
2436  *
2437  * For each struct/union type its type signature hash is calculated, taking
2438  * into account type's name, size, number, order and names of fields, but
2439  * ignoring type ID's referenced from fields, because they might not be deduped
2440  * completely until after reference types deduplication phase. This type hash
2441  * is used to iterate over all potential canonical types, sharing same hash.
2442  * For each canonical candidate we check whether type graphs that they form
2443  * (through referenced types in fields and so on) are equivalent using algorithm
2444  * implemented in `btf_dedup_is_equiv`. If such equivalence is found and
2445  * BTF_KIND_FWD resolution is allowed, then hypothetical mapping
2446  * (btf_dedup->hypot_map) produced by aforementioned type graph equivalence
2447  * algorithm is used to record FWD -> STRUCT/UNION mapping. It's also used to
2448  * potentially map other structs/unions to their canonical representatives,
2449  * if such relationship hasn't yet been established. This speeds up algorithm
2450  * by eliminating some of the duplicate work.
2451  *
2452  * If no matching canonical representative was found, struct/union is marked
2453  * as canonical for itself and is added into btf_dedup->dedup_table hash map
2454  * for further look ups.
2455  */
2456 static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
2457 {
2458         struct btf_type *cand_type, *t;
2459         struct hashmap_entry *hash_entry;
2460         /* if we don't find equivalent type, then we are canonical */
2461         __u32 new_id = type_id;
2462         __u16 kind;
2463         long h;
2464 
2465         /* already deduped or is in process of deduping (loop detected) */
2466         if (d->map[type_id] <= BTF_MAX_NR_TYPES)
2467                 return 0;
2468 
2469         t = d->btf->types[type_id];
2470         kind = btf_kind(t);
2471 
2472         if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
2473                 return 0;
2474 
2475         h = btf_hash_struct(t);
2476         for_each_dedup_cand(d, hash_entry, h) {
2477                 __u32 cand_id = (__u32)(long)hash_entry->value;
2478                 int eq;
2479 
2480                 /*
2481                  * Even though btf_dedup_is_equiv() checks for
2482                  * btf_shallow_equal_struct() internally when checking two
2483                  * structs (unions) for equivalence, we need to guard here
2484                  * from picking matching FWD type as a dedup candidate.
2485                  * This can happen due to hash collision. In such case just
2486                  * relying on btf_dedup_is_equiv() would lead to potentially
2487                  * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because
2488                  * FWD and compatible STRUCT/UNION are considered equivalent.
2489                  */
2490                 cand_type = d->btf->types[cand_id];
2491                 if (!btf_shallow_equal_struct(t, cand_type))
2492                         continue;
2493 
2494                 btf_dedup_clear_hypot_map(d);
2495                 eq = btf_dedup_is_equiv(d, type_id, cand_id);
2496                 if (eq < 0)
2497                         return eq;
2498                 if (!eq)
2499                         continue;
2500                 new_id = cand_id;
2501                 btf_dedup_merge_hypot_map(d);
2502                 break;
2503         }
2504 
2505         d->map[type_id] = new_id;
2506         if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
2507                 return -ENOMEM;
2508 
2509         return 0;
2510 }
2511 
2512 static int btf_dedup_struct_types(struct btf_dedup *d)
2513 {
2514         int i, err;
2515 
2516         for (i = 1; i <= d->btf->nr_types; i++) {
2517                 err = btf_dedup_struct_type(d, i);
2518                 if (err)
2519                         return err;
2520         }
2521         return 0;
2522 }
2523 
2524 /*
2525  * Deduplicate reference type.
2526  *
2527  * Once all primitive and struct/union types got deduplicated, we can easily
2528  * deduplicate all other (reference) BTF types. This is done in two steps:
2529  *
2530  * 1. Resolve all referenced type IDs into their canonical type IDs. This
2531  * resolution can be done either immediately for primitive or struct/union types
2532  * (because they were deduped in previous two phases) or recursively for
2533  * reference types. Recursion will always terminate at either primitive or
2534  * struct/union type, at which point we can "unwind" chain of reference types
2535  * one by one. There is no danger of encountering cycles because in C type
2536  * system the only way to form type cycle is through struct/union, so any chain
2537  * of reference types, even those taking part in a type cycle, will inevitably
2538  * reach struct/union at some point.
2539  *
2540  * 2. Once all referenced type IDs are resolved into canonical ones, BTF type
2541  * becomes "stable", in the sense that no further deduplication will cause
2542  * any changes to it. With that, it's now possible to calculate type's signature
2543  * hash (this time taking into account referenced type IDs) and loop over all
2544  * potential canonical representatives. If no match was found, current type
2545  * will become canonical representative of itself and will be added into
2546  * btf_dedup->dedup_table as another possible canonical representative.
2547  */
2548 static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
2549 {
2550         struct hashmap_entry *hash_entry;
2551         __u32 new_id = type_id, cand_id;
2552         struct btf_type *t, *cand;
2553         /* if we don't find equivalent type, then we are representative type */
2554         int ref_type_id;
2555         long h;
2556 
2557         if (d->map[type_id] == BTF_IN_PROGRESS_ID)
2558                 return -ELOOP;
2559         if (d->map[type_id] <= BTF_MAX_NR_TYPES)
2560                 return resolve_type_id(d, type_id);
2561 
2562         t = d->btf->types[type_id];
2563         d->map[type_id] = BTF_IN_PROGRESS_ID;
2564 
2565         switch (btf_kind(t)) {
2566         case BTF_KIND_CONST:
2567         case BTF_KIND_VOLATILE:
2568         case BTF_KIND_RESTRICT:
2569         case BTF_KIND_PTR:
2570         case BTF_KIND_TYPEDEF:
2571         case BTF_KIND_FUNC:
2572                 ref_type_id = btf_dedup_ref_type(d, t->type);
2573                 if (ref_type_id < 0)
2574                         return ref_type_id;
2575                 t->type = ref_type_id;
2576 
2577                 h = btf_hash_common(t);
2578                 for_each_dedup_cand(d, hash_entry, h) {
2579                         cand_id = (__u32)(long)hash_entry->value;
2580                         cand = d->btf->types[cand_id];
2581                         if (btf_equal_common(t, cand)) {
2582                                 new_id = cand_id;
2583                                 break;
2584                         }
2585                 }
2586                 break;
2587 
2588         case BTF_KIND_ARRAY: {
2589                 struct btf_array *info = btf_array(t);
2590 
2591                 ref_type_id = btf_dedup_ref_type(d, info->type);
2592                 if (ref_type_id < 0)
2593                         return ref_type_id;
2594                 info->type = ref_type_id;
2595 
2596                 ref_type_id = btf_dedup_ref_type(d, info->index_type);
2597                 if (ref_type_id < 0)
2598                         return ref_type_id;
2599                 info->index_type = ref_type_id;
2600 
2601                 h = btf_hash_array(t);
2602                 for_each_dedup_cand(d, hash_entry, h) {
2603                         cand_id = (__u32)(long)hash_entry->value;
2604                         cand = d->btf->types[cand_id];
2605                         if (btf_equal_array(t, cand)) {
2606                                 new_id = cand_id;
2607                                 break;
2608                         }
2609                 }
2610                 break;
2611         }
2612 
2613         case BTF_KIND_FUNC_PROTO: {
2614                 struct btf_param *param;
2615                 __u16 vlen;
2616                 int i;
2617 
2618                 ref_type_id = btf_dedup_ref_type(d, t->type);
2619                 if (ref_type_id < 0)
2620                         return ref_type_id;
2621                 t->type = ref_type_id;
2622 
2623                 vlen = btf_vlen(t);
2624                 param = btf_params(t);
2625                 for (i = 0; i < vlen; i++) {
2626                         ref_type_id = btf_dedup_ref_type(d, param->type);
2627                         if (ref_type_id < 0)
2628                                 return ref_type_id;
2629                         param->type = ref_type_id;
2630                         param++;
2631                 }
2632 
2633                 h = btf_hash_fnproto(t);
2634                 for_each_dedup_cand(d, hash_entry, h) {
2635                         cand_id = (__u32)(long)hash_entry->value;
2636                         cand = d->btf->types[cand_id];
2637                         if (btf_equal_fnproto(t, cand)) {
2638                                 new_id = cand_id;
2639                                 break;
2640                         }
2641                 }
2642                 break;
2643         }
2644 
2645         default:
2646                 return -EINVAL;
2647         }
2648 
2649         d->map[type_id] = new_id;
2650         if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
2651                 return -ENOMEM;
2652 
2653         return new_id;
2654 }
2655 
2656 static int btf_dedup_ref_types(struct btf_dedup *d)
2657 {
2658         int i, err;
2659 
2660         for (i = 1; i <= d->btf->nr_types; i++) {
2661                 err = btf_dedup_ref_type(d, i);
2662                 if (err < 0)
2663                         return err;
2664         }
2665         /* we won't need d->dedup_table anymore */
2666         hashmap__free(d->dedup_table);
2667         d->dedup_table = NULL;
2668         return 0;
2669 }
2670 
2671 /*
2672  * Compact types.
2673  *
2674  * After we established for each type its corresponding canonical representative
2675  * type, we now can eliminate types that are not canonical and leave only
2676  * canonical ones layed out sequentially in memory by copying them over
2677  * duplicates. During compaction btf_dedup->hypot_map array is reused to store
2678  * a map from original type ID to a new compacted type ID, which will be used
2679  * during next phase to "fix up" type IDs, referenced from struct/union and
2680  * reference types.
2681  */
2682 static int btf_dedup_compact_types(struct btf_dedup *d)
2683 {
2684         struct btf_type **new_types;
2685         __u32 next_type_id = 1;
2686         char *types_start, *p;
2687         int i, len;
2688 
2689         /* we are going to reuse hypot_map to store compaction remapping */
2690         d->hypot_map[0] = 0;
2691         for (i = 1; i <= d->btf->nr_types; i++)
2692                 d->hypot_map[i] = BTF_UNPROCESSED_ID;
2693 
2694         types_start = d->btf->nohdr_data + d->btf->hdr->type_off;
2695         p = types_start;
2696 
2697         for (i = 1; i <= d->btf->nr_types; i++) {
2698                 if (d->map[i] != i)
2699                         continue;
2700 
2701                 len = btf_type_size(d->btf->types[i]);
2702                 if (len < 0)
2703                         return len;
2704 
2705                 memmove(p, d->btf->types[i], len);
2706                 d->hypot_map[i] = next_type_id;
2707                 d->btf->types[next_type_id] = (struct btf_type *)p;
2708                 p += len;
2709                 next_type_id++;
2710         }
2711 
2712         /* shrink struct btf's internal types index and update btf_header */
2713         d->btf->nr_types = next_type_id - 1;
2714         d->btf->types_size = d->btf->nr_types;
2715         d->btf->hdr->type_len = p - types_start;
2716         new_types = realloc(d->btf->types,
2717                             (1 + d->btf->nr_types) * sizeof(struct btf_type *));
2718         if (!new_types)
2719                 return -ENOMEM;
2720         d->btf->types = new_types;
2721 
2722         /* make sure string section follows type information without gaps */
2723         d->btf->hdr->str_off = p - (char *)d->btf->nohdr_data;
2724         memmove(p, d->btf->strings, d->btf->hdr->str_len);
2725         d->btf->strings = p;
2726         p += d->btf->hdr->str_len;
2727 
2728         d->btf->data_size = p - (char *)d->btf->data;
2729         return 0;
2730 }
2731 
2732 /*
2733  * Figure out final (deduplicated and compacted) type ID for provided original
2734  * `type_id` by first resolving it into corresponding canonical type ID and
2735  * then mapping it to a deduplicated type ID, stored in btf_dedup->hypot_map,
2736  * which is populated during compaction phase.
2737  */
2738 static int btf_dedup_remap_type_id(struct btf_dedup *d, __u32 type_id)
2739 {
2740         __u32 resolved_type_id, new_type_id;
2741 
2742         resolved_type_id = resolve_type_id(d, type_id);
2743         new_type_id = d->hypot_map[resolved_type_id];
2744         if (new_type_id > BTF_MAX_NR_TYPES)
2745                 return -EINVAL;
2746         return new_type_id;
2747 }
2748 
2749 /*
2750  * Remap referenced type IDs into deduped type IDs.
2751  *
2752  * After BTF types are deduplicated and compacted, their final type IDs may
2753  * differ from original ones. The map from original to a corresponding
2754  * deduped type ID is stored in btf_dedup->hypot_map and is populated during
2755  * compaction phase. During remapping phase we are rewriting all type IDs
2756  * referenced from any BTF type (e.g., struct fields, func proto args, etc) to
2757  * their final deduped type IDs.
2758  */
2759 static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
2760 {
2761         struct btf_type *t = d->btf->types[type_id];
2762         int i, r;
2763 
2764         switch (btf_kind(t)) {
2765         case BTF_KIND_INT:
2766         case BTF_KIND_ENUM:
2767                 break;
2768 
2769         case BTF_KIND_FWD:
2770         case BTF_KIND_CONST:
2771         case BTF_KIND_VOLATILE:
2772         case BTF_KIND_RESTRICT:
2773         case BTF_KIND_PTR:
2774         case BTF_KIND_TYPEDEF:
2775         case BTF_KIND_FUNC:
2776         case BTF_KIND_VAR:
2777                 r = btf_dedup_remap_type_id(d, t->type);
2778                 if (r < 0)
2779                         return r;
2780                 t->type = r;
2781                 break;
2782 
2783         case BTF_KIND_ARRAY: {
2784                 struct btf_array *arr_info = btf_array(t);
2785 
2786                 r = btf_dedup_remap_type_id(d, arr_info->type);
2787                 if (r < 0)
2788                         return r;
2789                 arr_info->type = r;
2790                 r = btf_dedup_remap_type_id(d, arr_info->index_type);
2791                 if (r < 0)
2792                         return r;
2793                 arr_info->index_type = r;
2794                 break;
2795         }
2796 
2797         case BTF_KIND_STRUCT:
2798         case BTF_KIND_UNION: {
2799                 struct btf_member *member = btf_members(t);
2800                 __u16 vlen = btf_vlen(t);
2801 
2802                 for (i = 0; i < vlen; i++) {
2803                         r = btf_dedup_remap_type_id(d, member->type);
2804                         if (r < 0)
2805                                 return r;
2806                         member->type = r;
2807                         member++;
2808                 }
2809                 break;
2810         }
2811 
2812         case BTF_KIND_FUNC_PROTO: {
2813                 struct btf_param *param = btf_params(t);
2814                 __u16 vlen = btf_vlen(t);
2815 
2816                 r = btf_dedup_remap_type_id(d, t->type);
2817                 if (r < 0)
2818                         return r;
2819                 t->type = r;
2820 
2821                 for (i = 0; i < vlen; i++) {
2822                         r = btf_dedup_remap_type_id(d, param->type);
2823                         if (r < 0)
2824                                 return r;
2825                         param->type = r;
2826                         param++;
2827                 }
2828                 break;
2829         }
2830 
2831         case BTF_KIND_DATASEC: {
2832                 struct btf_var_secinfo *var = btf_var_secinfos(t);
2833                 __u16 vlen = btf_vlen(t);
2834 
2835                 for (i = 0; i < vlen; i++) {
2836                         r = btf_dedup_remap_type_id(d, var->type);
2837                         if (r < 0)
2838                                 return r;
2839                         var->type = r;
2840                         var++;
2841                 }
2842                 break;
2843         }
2844 
2845         default:
2846                 return -EINVAL;
2847         }
2848 
2849         return 0;
2850 }
2851 
2852 static int btf_dedup_remap_types(struct btf_dedup *d)
2853 {
2854         int i, r;
2855 
2856         for (i = 1; i <= d->btf->nr_types; i++) {
2857                 r = btf_dedup_remap_type(d, i);
2858                 if (r < 0)
2859                         return r;
2860         }
2861         return 0;
2862 }
/* [<][>][^][v][top][bottom][index][help] */
root/tools/lib/bpf/btf.c

DEFINITIONS
