1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) 2 3 /* 4 * BTF-to-C type converter. 5 * 6 * Copyright (c) 2019 Facebook 7 */ 8 9 #include <stdbool.h> 10 #include <stddef.h> 11 #include <stdlib.h> 12 #include <string.h> 13 #include <ctype.h> 14 #include <endian.h> 15 #include <errno.h> 16 #include <limits.h> 17 #include <linux/err.h> 18 #include <linux/btf.h> 19 #include <linux/kernel.h> 20 #include "btf.h" 21 #include "hashmap.h" 22 #include "libbpf.h" 23 #include "libbpf_internal.h" 24 25 static const char PREFIXES[] = "\t\t\t\t\t\t\t\t\t\t\t\t\t"; 26 static const size_t PREFIX_CNT = sizeof(PREFIXES) - 1; 27 28 static const char *pfx(int lvl) 29 { 30 return lvl >= PREFIX_CNT ? PREFIXES : &PREFIXES[PREFIX_CNT - lvl]; 31 } 32 33 enum btf_dump_type_order_state { 34 NOT_ORDERED, 35 ORDERING, 36 ORDERED, 37 }; 38 39 enum btf_dump_type_emit_state { 40 NOT_EMITTED, 41 EMITTING, 42 EMITTED, 43 }; 44 45 /* per-type auxiliary state */ 46 struct btf_dump_type_aux_state { 47 /* topological sorting state */ 48 enum btf_dump_type_order_state order_state: 2; 49 /* emitting state used to determine the need for forward declaration */ 50 enum btf_dump_type_emit_state emit_state: 2; 51 /* whether forward declaration was already emitted */ 52 __u8 fwd_emitted: 1; 53 /* whether unique non-duplicate name was already assigned */ 54 __u8 name_resolved: 1; 55 /* whether type is referenced from any other type */ 56 __u8 referenced: 1; 57 }; 58 59 /* indent string length; one indent string is added for each indent level */ 60 #define BTF_DATA_INDENT_STR_LEN 32 61 62 /* 63 * Common internal data for BTF type data dump operations. 64 */ 65 struct btf_dump_data { 66 const void *data_end; /* end of valid data to show */ 67 bool compact; 68 bool skip_names; 69 bool emit_zeroes; 70 __u8 indent_lvl; /* base indent level */ 71 char indent_str[BTF_DATA_INDENT_STR_LEN]; 72 /* below are used during iteration */ 73 int depth; 74 bool is_array_member; 75 bool is_array_terminated; 76 bool is_array_char; 77 }; 78 79 struct btf_dump { 80 const struct btf *btf; 81 btf_dump_printf_fn_t printf_fn; 82 void *cb_ctx; 83 int ptr_sz; 84 bool strip_mods; 85 bool skip_anon_defs; 86 int last_id; 87 88 /* per-type auxiliary state */ 89 struct btf_dump_type_aux_state *type_states; 90 size_t type_states_cap; 91 /* per-type optional cached unique name, must be freed, if present */ 92 const char **cached_names; 93 size_t cached_names_cap; 94 95 /* topo-sorted list of dependent type definitions */ 96 __u32 *emit_queue; 97 int emit_queue_cap; 98 int emit_queue_cnt; 99 100 /* 101 * stack of type declarations (e.g., chain of modifiers, arrays, 102 * funcs, etc) 103 */ 104 __u32 *decl_stack; 105 int decl_stack_cap; 106 int decl_stack_cnt; 107 108 /* maps struct/union/enum name to a number of name occurrences */ 109 struct hashmap *type_names; 110 /* 111 * maps typedef identifiers and enum value names to a number of such 112 * name occurrences 113 */ 114 struct hashmap *ident_names; 115 /* 116 * data for typed display; allocated if needed. 117 */ 118 struct btf_dump_data *typed_dump; 119 }; 120 121 static size_t str_hash_fn(long key, void *ctx) 122 { 123 return str_hash((void *)key); 124 } 125 126 static bool str_equal_fn(long a, long b, void *ctx) 127 { 128 return strcmp((void *)a, (void *)b) == 0; 129 } 130 131 static const char *btf_name_of(const struct btf_dump *d, __u32 name_off) 132 { 133 return btf__name_by_offset(d->btf, name_off); 134 } 135 136 static void btf_dump_printf(const struct btf_dump *d, const char *fmt, ...) 137 { 138 va_list args; 139 140 va_start(args, fmt); 141 d->printf_fn(d->cb_ctx, fmt, args); 142 va_end(args); 143 } 144 145 static int btf_dump_mark_referenced(struct btf_dump *d); 146 static int btf_dump_resize(struct btf_dump *d); 147 148 struct btf_dump *btf_dump__new(const struct btf *btf, 149 btf_dump_printf_fn_t printf_fn, 150 void *ctx, 151 const struct btf_dump_opts *opts) 152 { 153 struct btf_dump *d; 154 int err; 155 156 if (!OPTS_VALID(opts, btf_dump_opts)) 157 return libbpf_err_ptr(-EINVAL); 158 159 if (!printf_fn) 160 return libbpf_err_ptr(-EINVAL); 161 162 d = calloc(1, sizeof(struct btf_dump)); 163 if (!d) 164 return libbpf_err_ptr(-ENOMEM); 165 166 d->btf = btf; 167 d->printf_fn = printf_fn; 168 d->cb_ctx = ctx; 169 d->ptr_sz = btf__pointer_size(btf) ? : sizeof(void *); 170 171 d->type_names = hashmap__new(str_hash_fn, str_equal_fn, NULL); 172 if (IS_ERR(d->type_names)) { 173 err = PTR_ERR(d->type_names); 174 d->type_names = NULL; 175 goto err; 176 } 177 d->ident_names = hashmap__new(str_hash_fn, str_equal_fn, NULL); 178 if (IS_ERR(d->ident_names)) { 179 err = PTR_ERR(d->ident_names); 180 d->ident_names = NULL; 181 goto err; 182 } 183 184 err = btf_dump_resize(d); 185 if (err) 186 goto err; 187 188 return d; 189 err: 190 btf_dump__free(d); 191 return libbpf_err_ptr(err); 192 } 193 194 static int btf_dump_resize(struct btf_dump *d) 195 { 196 int err, last_id = btf__type_cnt(d->btf) - 1; 197 198 if (last_id <= d->last_id) 199 return 0; 200 201 if (libbpf_ensure_mem((void **)&d->type_states, &d->type_states_cap, 202 sizeof(*d->type_states), last_id + 1)) 203 return -ENOMEM; 204 if (libbpf_ensure_mem((void **)&d->cached_names, &d->cached_names_cap, 205 sizeof(*d->cached_names), last_id + 1)) 206 return -ENOMEM; 207 208 if (d->last_id == 0) { 209 /* VOID is special */ 210 d->type_states[0].order_state = ORDERED; 211 d->type_states[0].emit_state = EMITTED; 212 } 213 214 /* eagerly determine referenced types for anon enums */ 215 err = btf_dump_mark_referenced(d); 216 if (err) 217 return err; 218 219 d->last_id = last_id; 220 return 0; 221 } 222 223 static void btf_dump_free_names(struct hashmap *map) 224 { 225 size_t bkt; 226 struct hashmap_entry *cur; 227 228 hashmap__for_each_entry(map, cur, bkt) 229 free((void *)cur->pkey); 230 231 hashmap__free(map); 232 } 233 234 void btf_dump__free(struct btf_dump *d) 235 { 236 int i; 237 238 if (IS_ERR_OR_NULL(d)) 239 return; 240 241 free(d->type_states); 242 if (d->cached_names) { 243 /* any set cached name is owned by us and should be freed */ 244 for (i = 0; i <= d->last_id; i++) { 245 if (d->cached_names[i]) 246 free((void *)d->cached_names[i]); 247 } 248 } 249 free(d->cached_names); 250 free(d->emit_queue); 251 free(d->decl_stack); 252 btf_dump_free_names(d->type_names); 253 btf_dump_free_names(d->ident_names); 254 255 free(d); 256 } 257 258 static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr); 259 static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id); 260 261 /* 262 * Dump BTF type in a compilable C syntax, including all the necessary 263 * dependent types, necessary for compilation. If some of the dependent types 264 * were already emitted as part of previous btf_dump__dump_type() invocation 265 * for another type, they won't be emitted again. This API allows callers to 266 * filter out BTF types according to user-defined criterias and emitted only 267 * minimal subset of types, necessary to compile everything. Full struct/union 268 * definitions will still be emitted, even if the only usage is through 269 * pointer and could be satisfied with just a forward declaration. 270 * 271 * Dumping is done in two high-level passes: 272 * 1. Topologically sort type definitions to satisfy C rules of compilation. 273 * 2. Emit type definitions in C syntax. 274 * 275 * Returns 0 on success; <0, otherwise. 276 */ 277 int btf_dump__dump_type(struct btf_dump *d, __u32 id) 278 { 279 int err, i; 280 281 if (id >= btf__type_cnt(d->btf)) 282 return libbpf_err(-EINVAL); 283 284 err = btf_dump_resize(d); 285 if (err) 286 return libbpf_err(err); 287 288 d->emit_queue_cnt = 0; 289 err = btf_dump_order_type(d, id, false); 290 if (err < 0) 291 return libbpf_err(err); 292 293 for (i = 0; i < d->emit_queue_cnt; i++) 294 btf_dump_emit_type(d, d->emit_queue[i], 0 /*top-level*/); 295 296 return 0; 297 } 298 299 /* 300 * Mark all types that are referenced from any other type. This is used to 301 * determine top-level anonymous enums that need to be emitted as an 302 * independent type declarations. 303 * Anonymous enums come in two flavors: either embedded in a struct's field 304 * definition, in which case they have to be declared inline as part of field 305 * type declaration; or as a top-level anonymous enum, typically used for 306 * declaring global constants. It's impossible to distinguish between two 307 * without knowing whether given enum type was referenced from other type: 308 * top-level anonymous enum won't be referenced by anything, while embedded 309 * one will. 310 */ 311 static int btf_dump_mark_referenced(struct btf_dump *d) 312 { 313 int i, j, n = btf__type_cnt(d->btf); 314 const struct btf_type *t; 315 __u16 vlen; 316 317 for (i = d->last_id + 1; i < n; i++) { 318 t = btf__type_by_id(d->btf, i); 319 vlen = btf_vlen(t); 320 321 switch (btf_kind(t)) { 322 case BTF_KIND_INT: 323 case BTF_KIND_ENUM: 324 case BTF_KIND_ENUM64: 325 case BTF_KIND_FWD: 326 case BTF_KIND_FLOAT: 327 break; 328 329 case BTF_KIND_VOLATILE: 330 case BTF_KIND_CONST: 331 case BTF_KIND_RESTRICT: 332 case BTF_KIND_PTR: 333 case BTF_KIND_TYPEDEF: 334 case BTF_KIND_FUNC: 335 case BTF_KIND_VAR: 336 case BTF_KIND_DECL_TAG: 337 case BTF_KIND_TYPE_TAG: 338 d->type_states[t->type].referenced = 1; 339 break; 340 341 case BTF_KIND_ARRAY: { 342 const struct btf_array *a = btf_array(t); 343 344 d->type_states[a->index_type].referenced = 1; 345 d->type_states[a->type].referenced = 1; 346 break; 347 } 348 case BTF_KIND_STRUCT: 349 case BTF_KIND_UNION: { 350 const struct btf_member *m = btf_members(t); 351 352 for (j = 0; j < vlen; j++, m++) 353 d->type_states[m->type].referenced = 1; 354 break; 355 } 356 case BTF_KIND_FUNC_PROTO: { 357 const struct btf_param *p = btf_params(t); 358 359 for (j = 0; j < vlen; j++, p++) 360 d->type_states[p->type].referenced = 1; 361 break; 362 } 363 case BTF_KIND_DATASEC: { 364 const struct btf_var_secinfo *v = btf_var_secinfos(t); 365 366 for (j = 0; j < vlen; j++, v++) 367 d->type_states[v->type].referenced = 1; 368 break; 369 } 370 default: 371 return -EINVAL; 372 } 373 } 374 return 0; 375 } 376 377 static int btf_dump_add_emit_queue_id(struct btf_dump *d, __u32 id) 378 { 379 __u32 *new_queue; 380 size_t new_cap; 381 382 if (d->emit_queue_cnt >= d->emit_queue_cap) { 383 new_cap = max(16, d->emit_queue_cap * 3 / 2); 384 new_queue = libbpf_reallocarray(d->emit_queue, new_cap, sizeof(new_queue[0])); 385 if (!new_queue) 386 return -ENOMEM; 387 d->emit_queue = new_queue; 388 d->emit_queue_cap = new_cap; 389 } 390 391 d->emit_queue[d->emit_queue_cnt++] = id; 392 return 0; 393 } 394 395 /* 396 * Determine order of emitting dependent types and specified type to satisfy 397 * C compilation rules. This is done through topological sorting with an 398 * additional complication which comes from C rules. The main idea for C is 399 * that if some type is "embedded" into a struct/union, it's size needs to be 400 * known at the time of definition of containing type. E.g., for: 401 * 402 * struct A {}; 403 * struct B { struct A x; } 404 * 405 * struct A *HAS* to be defined before struct B, because it's "embedded", 406 * i.e., it is part of struct B layout. But in the following case: 407 * 408 * struct A; 409 * struct B { struct A *x; } 410 * struct A {}; 411 * 412 * it's enough to just have a forward declaration of struct A at the time of 413 * struct B definition, as struct B has a pointer to struct A, so the size of 414 * field x is known without knowing struct A size: it's sizeof(void *). 415 * 416 * Unfortunately, there are some trickier cases we need to handle, e.g.: 417 * 418 * struct A {}; // if this was forward-declaration: compilation error 419 * struct B { 420 * struct { // anonymous struct 421 * struct A y; 422 * } *x; 423 * }; 424 * 425 * In this case, struct B's field x is a pointer, so it's size is known 426 * regardless of the size of (anonymous) struct it points to. But because this 427 * struct is anonymous and thus defined inline inside struct B, *and* it 428 * embeds struct A, compiler requires full definition of struct A to be known 429 * before struct B can be defined. This creates a transitive dependency 430 * between struct A and struct B. If struct A was forward-declared before 431 * struct B definition and fully defined after struct B definition, that would 432 * trigger compilation error. 433 * 434 * All this means that while we are doing topological sorting on BTF type 435 * graph, we need to determine relationships between different types (graph 436 * nodes): 437 * - weak link (relationship) between X and Y, if Y *CAN* be 438 * forward-declared at the point of X definition; 439 * - strong link, if Y *HAS* to be fully-defined before X can be defined. 440 * 441 * The rule is as follows. Given a chain of BTF types from X to Y, if there is 442 * BTF_KIND_PTR type in the chain and at least one non-anonymous type 443 * Z (excluding X, including Y), then link is weak. Otherwise, it's strong. 444 * Weak/strong relationship is determined recursively during DFS traversal and 445 * is returned as a result from btf_dump_order_type(). 446 * 447 * btf_dump_order_type() is trying to avoid unnecessary forward declarations, 448 * but it is not guaranteeing that no extraneous forward declarations will be 449 * emitted. 450 * 451 * To avoid extra work, algorithm marks some of BTF types as ORDERED, when 452 * it's done with them, but not for all (e.g., VOLATILE, CONST, RESTRICT, 453 * ARRAY, FUNC_PROTO), as weak/strong semantics for those depends on the 454 * entire graph path, so depending where from one came to that BTF type, it 455 * might cause weak or strong ordering. For types like STRUCT/UNION/INT/ENUM, 456 * once they are processed, there is no need to do it again, so they are 457 * marked as ORDERED. We can mark PTR as ORDERED as well, as it semi-forces 458 * weak link, unless subsequent referenced STRUCT/UNION/ENUM is anonymous. But 459 * in any case, once those are processed, no need to do it again, as the 460 * result won't change. 461 * 462 * Returns: 463 * - 1, if type is part of strong link (so there is strong topological 464 * ordering requirements); 465 * - 0, if type is part of weak link (so can be satisfied through forward 466 * declaration); 467 * - <0, on error (e.g., unsatisfiable type loop detected). 468 */ 469 static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr) 470 { 471 /* 472 * Order state is used to detect strong link cycles, but only for BTF 473 * kinds that are or could be an independent definition (i.e., 474 * stand-alone fwd decl, enum, typedef, struct, union). Ptrs, arrays, 475 * func_protos, modifiers are just means to get to these definitions. 476 * Int/void don't need definitions, they are assumed to be always 477 * properly defined. We also ignore datasec, var, and funcs for now. 478 * So for all non-defining kinds, we never even set ordering state, 479 * for defining kinds we set ORDERING and subsequently ORDERED if it 480 * forms a strong link. 481 */ 482 struct btf_dump_type_aux_state *tstate = &d->type_states[id]; 483 const struct btf_type *t; 484 __u16 vlen; 485 int err, i; 486 487 /* return true, letting typedefs know that it's ok to be emitted */ 488 if (tstate->order_state == ORDERED) 489 return 1; 490 491 t = btf__type_by_id(d->btf, id); 492 493 if (tstate->order_state == ORDERING) { 494 /* type loop, but resolvable through fwd declaration */ 495 if (btf_is_composite(t) && through_ptr && t->name_off != 0) 496 return 0; 497 pr_warn("unsatisfiable type cycle, id:[%u]\n", id); 498 return -ELOOP; 499 } 500 501 switch (btf_kind(t)) { 502 case BTF_KIND_INT: 503 case BTF_KIND_FLOAT: 504 tstate->order_state = ORDERED; 505 return 0; 506 507 case BTF_KIND_PTR: 508 err = btf_dump_order_type(d, t->type, true); 509 tstate->order_state = ORDERED; 510 return err; 511 512 case BTF_KIND_ARRAY: 513 return btf_dump_order_type(d, btf_array(t)->type, false); 514 515 case BTF_KIND_STRUCT: 516 case BTF_KIND_UNION: { 517 const struct btf_member *m = btf_members(t); 518 /* 519 * struct/union is part of strong link, only if it's embedded 520 * (so no ptr in a path) or it's anonymous (so has to be 521 * defined inline, even if declared through ptr) 522 */ 523 if (through_ptr && t->name_off != 0) 524 return 0; 525 526 tstate->order_state = ORDERING; 527 528 vlen = btf_vlen(t); 529 for (i = 0; i < vlen; i++, m++) { 530 err = btf_dump_order_type(d, m->type, false); 531 if (err < 0) 532 return err; 533 } 534 535 if (t->name_off != 0) { 536 err = btf_dump_add_emit_queue_id(d, id); 537 if (err < 0) 538 return err; 539 } 540 541 tstate->order_state = ORDERED; 542 return 1; 543 } 544 case BTF_KIND_ENUM: 545 case BTF_KIND_ENUM64: 546 case BTF_KIND_FWD: 547 /* 548 * non-anonymous or non-referenced enums are top-level 549 * declarations and should be emitted. Same logic can be 550 * applied to FWDs, it won't hurt anyways. 551 */ 552 if (t->name_off != 0 || !tstate->referenced) { 553 err = btf_dump_add_emit_queue_id(d, id); 554 if (err) 555 return err; 556 } 557 tstate->order_state = ORDERED; 558 return 1; 559 560 case BTF_KIND_TYPEDEF: { 561 int is_strong; 562 563 is_strong = btf_dump_order_type(d, t->type, through_ptr); 564 if (is_strong < 0) 565 return is_strong; 566 567 /* typedef is similar to struct/union w.r.t. fwd-decls */ 568 if (through_ptr && !is_strong) 569 return 0; 570 571 /* typedef is always a named definition */ 572 err = btf_dump_add_emit_queue_id(d, id); 573 if (err) 574 return err; 575 576 d->type_states[id].order_state = ORDERED; 577 return 1; 578 } 579 case BTF_KIND_VOLATILE: 580 case BTF_KIND_CONST: 581 case BTF_KIND_RESTRICT: 582 case BTF_KIND_TYPE_TAG: 583 return btf_dump_order_type(d, t->type, through_ptr); 584 585 case BTF_KIND_FUNC_PROTO: { 586 const struct btf_param *p = btf_params(t); 587 bool is_strong; 588 589 err = btf_dump_order_type(d, t->type, through_ptr); 590 if (err < 0) 591 return err; 592 is_strong = err > 0; 593 594 vlen = btf_vlen(t); 595 for (i = 0; i < vlen; i++, p++) { 596 err = btf_dump_order_type(d, p->type, through_ptr); 597 if (err < 0) 598 return err; 599 if (err > 0) 600 is_strong = true; 601 } 602 return is_strong; 603 } 604 case BTF_KIND_FUNC: 605 case BTF_KIND_VAR: 606 case BTF_KIND_DATASEC: 607 case BTF_KIND_DECL_TAG: 608 d->type_states[id].order_state = ORDERED; 609 return 0; 610 611 default: 612 return -EINVAL; 613 } 614 } 615 616 static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id, 617 const struct btf_type *t); 618 619 static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id, 620 const struct btf_type *t); 621 static void btf_dump_emit_struct_def(struct btf_dump *d, __u32 id, 622 const struct btf_type *t, int lvl); 623 624 static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id, 625 const struct btf_type *t); 626 static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id, 627 const struct btf_type *t, int lvl); 628 629 static void btf_dump_emit_fwd_def(struct btf_dump *d, __u32 id, 630 const struct btf_type *t); 631 632 static void btf_dump_emit_typedef_def(struct btf_dump *d, __u32 id, 633 const struct btf_type *t, int lvl); 634 635 /* a local view into a shared stack */ 636 struct id_stack { 637 const __u32 *ids; 638 int cnt; 639 }; 640 641 static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id, 642 const char *fname, int lvl); 643 static void btf_dump_emit_type_chain(struct btf_dump *d, 644 struct id_stack *decl_stack, 645 const char *fname, int lvl); 646 647 static const char *btf_dump_type_name(struct btf_dump *d, __u32 id); 648 static const char *btf_dump_ident_name(struct btf_dump *d, __u32 id); 649 static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_map, 650 const char *orig_name); 651 652 static bool btf_dump_is_blacklisted(struct btf_dump *d, __u32 id) 653 { 654 const struct btf_type *t = btf__type_by_id(d->btf, id); 655 656 /* __builtin_va_list is a compiler built-in, which causes compilation 657 * errors, when compiling w/ different compiler, then used to compile 658 * original code (e.g., GCC to compile kernel, Clang to use generated 659 * C header from BTF). As it is built-in, it should be already defined 660 * properly internally in compiler. 661 */ 662 if (t->name_off == 0) 663 return false; 664 return strcmp(btf_name_of(d, t->name_off), "__builtin_va_list") == 0; 665 } 666 667 /* 668 * Emit C-syntax definitions of types from chains of BTF types. 669 * 670 * High-level handling of determining necessary forward declarations are handled 671 * by btf_dump_emit_type() itself, but all nitty-gritty details of emitting type 672 * declarations/definitions in C syntax are handled by a combo of 673 * btf_dump_emit_type_decl()/btf_dump_emit_type_chain() w/ delegation to 674 * corresponding btf_dump_emit_*_{def,fwd}() functions. 675 * 676 * We also keep track of "containing struct/union type ID" to determine when 677 * we reference it from inside and thus can avoid emitting unnecessary forward 678 * declaration. 679 * 680 * This algorithm is designed in such a way, that even if some error occurs 681 * (either technical, e.g., out of memory, or logical, i.e., malformed BTF 682 * that doesn't comply to C rules completely), algorithm will try to proceed 683 * and produce as much meaningful output as possible. 684 */ 685 static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id) 686 { 687 struct btf_dump_type_aux_state *tstate = &d->type_states[id]; 688 bool top_level_def = cont_id == 0; 689 const struct btf_type *t; 690 __u16 kind; 691 692 if (tstate->emit_state == EMITTED) 693 return; 694 695 t = btf__type_by_id(d->btf, id); 696 kind = btf_kind(t); 697 698 if (tstate->emit_state == EMITTING) { 699 if (tstate->fwd_emitted) 700 return; 701 702 switch (kind) { 703 case BTF_KIND_STRUCT: 704 case BTF_KIND_UNION: 705 /* 706 * if we are referencing a struct/union that we are 707 * part of - then no need for fwd declaration 708 */ 709 if (id == cont_id) 710 return; 711 if (t->name_off == 0) { 712 pr_warn("anonymous struct/union loop, id:[%u]\n", 713 id); 714 return; 715 } 716 btf_dump_emit_struct_fwd(d, id, t); 717 btf_dump_printf(d, ";\n\n"); 718 tstate->fwd_emitted = 1; 719 break; 720 case BTF_KIND_TYPEDEF: 721 /* 722 * for typedef fwd_emitted means typedef definition 723 * was emitted, but it can be used only for "weak" 724 * references through pointer only, not for embedding 725 */ 726 if (!btf_dump_is_blacklisted(d, id)) { 727 btf_dump_emit_typedef_def(d, id, t, 0); 728 btf_dump_printf(d, ";\n\n"); 729 } 730 tstate->fwd_emitted = 1; 731 break; 732 default: 733 break; 734 } 735 736 return; 737 } 738 739 switch (kind) { 740 case BTF_KIND_INT: 741 /* Emit type alias definitions if necessary */ 742 btf_dump_emit_missing_aliases(d, id, t); 743 744 tstate->emit_state = EMITTED; 745 break; 746 case BTF_KIND_ENUM: 747 case BTF_KIND_ENUM64: 748 if (top_level_def) { 749 btf_dump_emit_enum_def(d, id, t, 0); 750 btf_dump_printf(d, ";\n\n"); 751 } 752 tstate->emit_state = EMITTED; 753 break; 754 case BTF_KIND_PTR: 755 case BTF_KIND_VOLATILE: 756 case BTF_KIND_CONST: 757 case BTF_KIND_RESTRICT: 758 case BTF_KIND_TYPE_TAG: 759 btf_dump_emit_type(d, t->type, cont_id); 760 break; 761 case BTF_KIND_ARRAY: 762 btf_dump_emit_type(d, btf_array(t)->type, cont_id); 763 break; 764 case BTF_KIND_FWD: 765 btf_dump_emit_fwd_def(d, id, t); 766 btf_dump_printf(d, ";\n\n"); 767 tstate->emit_state = EMITTED; 768 break; 769 case BTF_KIND_TYPEDEF: 770 tstate->emit_state = EMITTING; 771 btf_dump_emit_type(d, t->type, id); 772 /* 773 * typedef can server as both definition and forward 774 * declaration; at this stage someone depends on 775 * typedef as a forward declaration (refers to it 776 * through pointer), so unless we already did it, 777 * emit typedef as a forward declaration 778 */ 779 if (!tstate->fwd_emitted && !btf_dump_is_blacklisted(d, id)) { 780 btf_dump_emit_typedef_def(d, id, t, 0); 781 btf_dump_printf(d, ";\n\n"); 782 } 783 tstate->emit_state = EMITTED; 784 break; 785 case BTF_KIND_STRUCT: 786 case BTF_KIND_UNION: 787 tstate->emit_state = EMITTING; 788 /* if it's a top-level struct/union definition or struct/union 789 * is anonymous, then in C we'll be emitting all fields and 790 * their types (as opposed to just `struct X`), so we need to 791 * make sure that all types, referenced from struct/union 792 * members have necessary forward-declarations, where 793 * applicable 794 */ 795 if (top_level_def || t->name_off == 0) { 796 const struct btf_member *m = btf_members(t); 797 __u16 vlen = btf_vlen(t); 798 int i, new_cont_id; 799 800 new_cont_id = t->name_off == 0 ? cont_id : id; 801 for (i = 0; i < vlen; i++, m++) 802 btf_dump_emit_type(d, m->type, new_cont_id); 803 } else if (!tstate->fwd_emitted && id != cont_id) { 804 btf_dump_emit_struct_fwd(d, id, t); 805 btf_dump_printf(d, ";\n\n"); 806 tstate->fwd_emitted = 1; 807 } 808 809 if (top_level_def) { 810 btf_dump_emit_struct_def(d, id, t, 0); 811 btf_dump_printf(d, ";\n\n"); 812 tstate->emit_state = EMITTED; 813 } else { 814 tstate->emit_state = NOT_EMITTED; 815 } 816 break; 817 case BTF_KIND_FUNC_PROTO: { 818 const struct btf_param *p = btf_params(t); 819 __u16 n = btf_vlen(t); 820 int i; 821 822 btf_dump_emit_type(d, t->type, cont_id); 823 for (i = 0; i < n; i++, p++) 824 btf_dump_emit_type(d, p->type, cont_id); 825 826 break; 827 } 828 default: 829 break; 830 } 831 } 832 833 static bool btf_is_struct_packed(const struct btf *btf, __u32 id, 834 const struct btf_type *t) 835 { 836 const struct btf_member *m; 837 int max_align = 1, align, i, bit_sz; 838 __u16 vlen; 839 840 m = btf_members(t); 841 vlen = btf_vlen(t); 842 /* all non-bitfield fields have to be naturally aligned */ 843 for (i = 0; i < vlen; i++, m++) { 844 align = btf__align_of(btf, m->type); 845 bit_sz = btf_member_bitfield_size(t, i); 846 if (align && bit_sz == 0 && m->offset % (8 * align) != 0) 847 return true; 848 max_align = max(align, max_align); 849 } 850 /* size of a non-packed struct has to be a multiple of its alignment */ 851 if (t->size % max_align != 0) 852 return true; 853 /* 854 * if original struct was marked as packed, but its layout is 855 * naturally aligned, we'll detect that it's not packed 856 */ 857 return false; 858 } 859 860 static void btf_dump_emit_bit_padding(const struct btf_dump *d, 861 int cur_off, int next_off, int next_align, 862 bool in_bitfield, int lvl) 863 { 864 const struct { 865 const char *name; 866 int bits; 867 } pads[] = { 868 {"long", d->ptr_sz * 8}, {"int", 32}, {"short", 16}, {"char", 8} 869 }; 870 int new_off, pad_bits, bits, i; 871 const char *pad_type; 872 873 if (cur_off >= next_off) 874 return; /* no gap */ 875 876 /* For filling out padding we want to take advantage of 877 * natural alignment rules to minimize unnecessary explicit 878 * padding. First, we find the largest type (among long, int, 879 * short, or char) that can be used to force naturally aligned 880 * boundary. Once determined, we'll use such type to fill in 881 * the remaining padding gap. In some cases we can rely on 882 * compiler filling some gaps, but sometimes we need to force 883 * alignment to close natural alignment with markers like 884 * `long: 0` (this is always the case for bitfields). Note 885 * that even if struct itself has, let's say 4-byte alignment 886 * (i.e., it only uses up to int-aligned types), using `long: 887 * X;` explicit padding doesn't actually change struct's 888 * overall alignment requirements, but compiler does take into 889 * account that type's (long, in this example) natural 890 * alignment requirements when adding implicit padding. We use 891 * this fact heavily and don't worry about ruining correct 892 * struct alignment requirement. 893 */ 894 for (i = 0; i < ARRAY_SIZE(pads); i++) { 895 pad_bits = pads[i].bits; 896 pad_type = pads[i].name; 897 898 new_off = roundup(cur_off, pad_bits); 899 if (new_off <= next_off) 900 break; 901 } 902 903 if (new_off > cur_off && new_off <= next_off) { 904 /* We need explicit `<type>: 0` aligning mark if next 905 * field is right on alignment offset and its 906 * alignment requirement is less strict than <type>'s 907 * alignment (so compiler won't naturally align to the 908 * offset we expect), or if subsequent `<type>: X`, 909 * will actually completely fit in the remaining hole, 910 * making compiler basically ignore `<type>: X` 911 * completely. 912 */ 913 if (in_bitfield || 914 (new_off == next_off && roundup(cur_off, next_align * 8) != new_off) || 915 (new_off != next_off && next_off - new_off <= new_off - cur_off)) 916 /* but for bitfields we'll emit explicit bit count */ 917 btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type, 918 in_bitfield ? new_off - cur_off : 0); 919 cur_off = new_off; 920 } 921 922 /* Now we know we start at naturally aligned offset for a chosen 923 * padding type (long, int, short, or char), and so the rest is just 924 * a straightforward filling of remaining padding gap with full 925 * `<type>: sizeof(<type>);` markers, except for the last one, which 926 * might need smaller than sizeof(<type>) padding. 927 */ 928 while (cur_off != next_off) { 929 bits = min(next_off - cur_off, pad_bits); 930 if (bits == pad_bits) { 931 btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type, pad_bits); 932 cur_off += bits; 933 continue; 934 } 935 /* For the remainder padding that doesn't cover entire 936 * pad_type bit length, we pick the smallest necessary type. 937 * This is pure aesthetics, we could have just used `long`, 938 * but having smallest necessary one communicates better the 939 * scale of the padding gap. 940 */ 941 for (i = ARRAY_SIZE(pads) - 1; i >= 0; i--) { 942 pad_type = pads[i].name; 943 pad_bits = pads[i].bits; 944 if (pad_bits < bits) 945 continue; 946 947 btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type, bits); 948 cur_off += bits; 949 break; 950 } 951 } 952 } 953 954 static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id, 955 const struct btf_type *t) 956 { 957 btf_dump_printf(d, "%s%s%s", 958 btf_is_struct(t) ? "struct" : "union", 959 t->name_off ? " " : "", 960 btf_dump_type_name(d, id)); 961 } 962 963 static void btf_dump_emit_struct_def(struct btf_dump *d, 964 __u32 id, 965 const struct btf_type *t, 966 int lvl) 967 { 968 const struct btf_member *m = btf_members(t); 969 bool is_struct = btf_is_struct(t); 970 bool packed, prev_bitfield = false; 971 int align, i, off = 0; 972 __u16 vlen = btf_vlen(t); 973 974 align = btf__align_of(d->btf, id); 975 packed = is_struct ? btf_is_struct_packed(d->btf, id, t) : 0; 976 977 btf_dump_printf(d, "%s%s%s {", 978 is_struct ? "struct" : "union", 979 t->name_off ? " " : "", 980 btf_dump_type_name(d, id)); 981 982 for (i = 0; i < vlen; i++, m++) { 983 const char *fname; 984 int m_off, m_sz, m_align; 985 bool in_bitfield; 986 987 fname = btf_name_of(d, m->name_off); 988 m_sz = btf_member_bitfield_size(t, i); 989 m_off = btf_member_bit_offset(t, i); 990 m_align = packed ? 1 : btf__align_of(d->btf, m->type); 991 992 in_bitfield = prev_bitfield && m_sz != 0; 993 994 btf_dump_emit_bit_padding(d, off, m_off, m_align, in_bitfield, lvl + 1); 995 btf_dump_printf(d, "\n%s", pfx(lvl + 1)); 996 btf_dump_emit_type_decl(d, m->type, fname, lvl + 1); 997 998 if (m_sz) { 999 btf_dump_printf(d, ": %d", m_sz); 1000 off = m_off + m_sz; 1001 prev_bitfield = true; 1002 } else { 1003 m_sz = max((__s64)0, btf__resolve_size(d->btf, m->type)); 1004 off = m_off + m_sz * 8; 1005 prev_bitfield = false; 1006 } 1007 1008 btf_dump_printf(d, ";"); 1009 } 1010 1011 /* pad at the end, if necessary */ 1012 if (is_struct) 1013 btf_dump_emit_bit_padding(d, off, t->size * 8, align, false, lvl + 1); 1014 1015 /* 1016 * Keep `struct empty {}` on a single line, 1017 * only print newline when there are regular or padding fields. 1018 */ 1019 if (vlen || t->size) { 1020 btf_dump_printf(d, "\n"); 1021 btf_dump_printf(d, "%s}", pfx(lvl)); 1022 } else { 1023 btf_dump_printf(d, "}"); 1024 } 1025 if (packed) 1026 btf_dump_printf(d, " __attribute__((packed))"); 1027 } 1028 1029 static const char *missing_base_types[][2] = { 1030 /* 1031 * GCC emits typedefs to its internal __PolyX_t types when compiling Arm 1032 * SIMD intrinsics. Alias them to standard base types. 1033 */ 1034 { "__Poly8_t", "unsigned char" }, 1035 { "__Poly16_t", "unsigned short" }, 1036 { "__Poly64_t", "unsigned long long" }, 1037 { "__Poly128_t", "unsigned __int128" }, 1038 }; 1039 1040 static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id, 1041 const struct btf_type *t) 1042 { 1043 const char *name = btf_dump_type_name(d, id); 1044 int i; 1045 1046 for (i = 0; i < ARRAY_SIZE(missing_base_types); i++) { 1047 if (strcmp(name, missing_base_types[i][0]) == 0) { 1048 btf_dump_printf(d, "typedef %s %s;\n\n", 1049 missing_base_types[i][1], name); 1050 break; 1051 } 1052 } 1053 } 1054 1055 static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id, 1056 const struct btf_type *t) 1057 { 1058 btf_dump_printf(d, "enum %s", btf_dump_type_name(d, id)); 1059 } 1060 1061 static void btf_dump_emit_enum32_val(struct btf_dump *d, 1062 const struct btf_type *t, 1063 int lvl, __u16 vlen) 1064 { 1065 const struct btf_enum *v = btf_enum(t); 1066 bool is_signed = btf_kflag(t); 1067 const char *fmt_str; 1068 const char *name; 1069 size_t dup_cnt; 1070 int i; 1071 1072 for (i = 0; i < vlen; i++, v++) { 1073 name = btf_name_of(d, v->name_off); 1074 /* enumerators share namespace with typedef idents */ 1075 dup_cnt = btf_dump_name_dups(d, d->ident_names, name); 1076 if (dup_cnt > 1) { 1077 fmt_str = is_signed ? "\n%s%s___%zd = %d," : "\n%s%s___%zd = %u,"; 1078 btf_dump_printf(d, fmt_str, pfx(lvl + 1), name, dup_cnt, v->val); 1079 } else { 1080 fmt_str = is_signed ? "\n%s%s = %d," : "\n%s%s = %u,"; 1081 btf_dump_printf(d, fmt_str, pfx(lvl + 1), name, v->val); 1082 } 1083 } 1084 } 1085 1086 static void btf_dump_emit_enum64_val(struct btf_dump *d, 1087 const struct btf_type *t, 1088 int lvl, __u16 vlen) 1089 { 1090 const struct btf_enum64 *v = btf_enum64(t); 1091 bool is_signed = btf_kflag(t); 1092 const char *fmt_str; 1093 const char *name; 1094 size_t dup_cnt; 1095 __u64 val; 1096 int i; 1097 1098 for (i = 0; i < vlen; i++, v++) { 1099 name = btf_name_of(d, v->name_off); 1100 dup_cnt = btf_dump_name_dups(d, d->ident_names, name); 1101 val = btf_enum64_value(v); 1102 if (dup_cnt > 1) { 1103 fmt_str = is_signed ? "\n%s%s___%zd = %lldLL," 1104 : "\n%s%s___%zd = %lluULL,"; 1105 btf_dump_printf(d, fmt_str, 1106 pfx(lvl + 1), name, dup_cnt, 1107 (unsigned long long)val); 1108 } else { 1109 fmt_str = is_signed ? "\n%s%s = %lldLL," 1110 : "\n%s%s = %lluULL,"; 1111 btf_dump_printf(d, fmt_str, 1112 pfx(lvl + 1), name, 1113 (unsigned long long)val); 1114 } 1115 } 1116 } 1117 static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id, 1118 const struct btf_type *t, 1119 int lvl) 1120 { 1121 __u16 vlen = btf_vlen(t); 1122 1123 btf_dump_printf(d, "enum%s%s", 1124 t->name_off ? " " : "", 1125 btf_dump_type_name(d, id)); 1126 1127 if (!vlen) 1128 return; 1129 1130 btf_dump_printf(d, " {"); 1131 if (btf_is_enum(t)) 1132 btf_dump_emit_enum32_val(d, t, lvl, vlen); 1133 else 1134 btf_dump_emit_enum64_val(d, t, lvl, vlen); 1135 btf_dump_printf(d, "\n%s}", pfx(lvl)); 1136 1137 /* special case enums with special sizes */ 1138 if (t->size == 1) { 1139 /* one-byte enums can be forced with mode(byte) attribute */ 1140 btf_dump_printf(d, " __attribute__((mode(byte)))"); 1141 } else if (t->size == 8 && d->ptr_sz == 8) { 1142 /* enum can be 8-byte sized if one of the enumerator values 1143 * doesn't fit in 32-bit integer, or by adding mode(word) 1144 * attribute (but probably only on 64-bit architectures); do 1145 * our best here to try to satisfy the contract without adding 1146 * unnecessary attributes 1147 */ 1148 bool needs_word_mode; 1149 1150 if (btf_is_enum(t)) { 1151 /* enum can't represent 64-bit values, so we need word mode */ 1152 needs_word_mode = true; 1153 } else { 1154 /* enum64 needs mode(word) if none of its values has 1155 * non-zero upper 32-bits (which means that all values 1156 * fit in 32-bit integers and won't cause compiler to 1157 * bump enum to be 64-bit naturally 1158 */ 1159 int i; 1160 1161 needs_word_mode = true; 1162 for (i = 0; i < vlen; i++) { 1163 if (btf_enum64(t)[i].val_hi32 != 0) { 1164 needs_word_mode = false; 1165 break; 1166 } 1167 } 1168 } 1169 if (needs_word_mode) 1170 btf_dump_printf(d, " __attribute__((mode(word)))"); 1171 } 1172 1173 } 1174 1175 static void btf_dump_emit_fwd_def(struct btf_dump *d, __u32 id, 1176 const struct btf_type *t) 1177 { 1178 const char *name = btf_dump_type_name(d, id); 1179 1180 if (btf_kflag(t)) 1181 btf_dump_printf(d, "union %s", name); 1182 else 1183 btf_dump_printf(d, "struct %s", name); 1184 } 1185 1186 static void btf_dump_emit_typedef_def(struct btf_dump *d, __u32 id, 1187 const struct btf_type *t, int lvl) 1188 { 1189 const char *name = btf_dump_ident_name(d, id); 1190 1191 /* 1192 * Old GCC versions are emitting invalid typedef for __gnuc_va_list 1193 * pointing to VOID. This generates warnings from btf_dump() and 1194 * results in uncompilable header file, so we are fixing it up here 1195 * with valid typedef into __builtin_va_list. 1196 */ 1197 if (t->type == 0 && strcmp(name, "__gnuc_va_list") == 0) { 1198 btf_dump_printf(d, "typedef __builtin_va_list __gnuc_va_list"); 1199 return; 1200 } 1201 1202 btf_dump_printf(d, "typedef "); 1203 btf_dump_emit_type_decl(d, t->type, name, lvl); 1204 } 1205 1206 static int btf_dump_push_decl_stack_id(struct btf_dump *d, __u32 id) 1207 { 1208 __u32 *new_stack; 1209 size_t new_cap; 1210 1211 if (d->decl_stack_cnt >= d->decl_stack_cap) { 1212 new_cap = max(16, d->decl_stack_cap * 3 / 2); 1213 new_stack = libbpf_reallocarray(d->decl_stack, new_cap, sizeof(new_stack[0])); 1214 if (!new_stack) 1215 return -ENOMEM; 1216 d->decl_stack = new_stack; 1217 d->decl_stack_cap = new_cap; 1218 } 1219 1220 d->decl_stack[d->decl_stack_cnt++] = id; 1221 1222 return 0; 1223 } 1224 1225 /* 1226 * Emit type declaration (e.g., field type declaration in a struct or argument 1227 * declaration in function prototype) in correct C syntax. 1228 * 1229 * For most types it's trivial, but there are few quirky type declaration 1230 * cases worth mentioning: 1231 * - function prototypes (especially nesting of function prototypes); 1232 * - arrays; 1233 * - const/volatile/restrict for pointers vs other types. 1234 * 1235 * For a good discussion of *PARSING* C syntax (as a human), see 1236 * Peter van der Linden's "Expert C Programming: Deep C Secrets", 1237 * Ch.3 "Unscrambling Declarations in C". 1238 * 1239 * It won't help with BTF to C conversion much, though, as it's an opposite 1240 * problem. So we came up with this algorithm in reverse to van der Linden's 1241 * parsing algorithm. It goes from structured BTF representation of type 1242 * declaration to a valid compilable C syntax. 1243 * 1244 * For instance, consider this C typedef: 1245 * typedef const int * const * arr[10] arr_t; 1246 * It will be represented in BTF with this chain of BTF types: 1247 * [typedef] -> [array] -> [ptr] -> [const] -> [ptr] -> [const] -> [int] 1248 * 1249 * Notice how [const] modifier always goes before type it modifies in BTF type 1250 * graph, but in C syntax, const/volatile/restrict modifiers are written to 1251 * the right of pointers, but to the left of other types. There are also other 1252 * quirks, like function pointers, arrays of them, functions returning other 1253 * functions, etc. 1254 * 1255 * We handle that by pushing all the types to a stack, until we hit "terminal" 1256 * type (int/enum/struct/union/fwd). Then depending on the kind of a type on 1257 * top of a stack, modifiers are handled differently. Array/function pointers 1258 * have also wildly different syntax and how nesting of them are done. See 1259 * code for authoritative definition. 1260 * 1261 * To avoid allocating new stack for each independent chain of BTF types, we 1262 * share one bigger stack, with each chain working only on its own local view 1263 * of a stack frame. Some care is required to "pop" stack frames after 1264 * processing type declaration chain. 1265 */ 1266 int btf_dump__emit_type_decl(struct btf_dump *d, __u32 id, 1267 const struct btf_dump_emit_type_decl_opts *opts) 1268 { 1269 const char *fname; 1270 int lvl, err; 1271 1272 if (!OPTS_VALID(opts, btf_dump_emit_type_decl_opts)) 1273 return libbpf_err(-EINVAL); 1274 1275 err = btf_dump_resize(d); 1276 if (err) 1277 return libbpf_err(err); 1278 1279 fname = OPTS_GET(opts, field_name, ""); 1280 lvl = OPTS_GET(opts, indent_level, 0); 1281 d->strip_mods = OPTS_GET(opts, strip_mods, false); 1282 btf_dump_emit_type_decl(d, id, fname, lvl); 1283 d->strip_mods = false; 1284 return 0; 1285 } 1286 1287 static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id, 1288 const char *fname, int lvl) 1289 { 1290 struct id_stack decl_stack; 1291 const struct btf_type *t; 1292 int err, stack_start; 1293 1294 stack_start = d->decl_stack_cnt; 1295 for (;;) { 1296 t = btf__type_by_id(d->btf, id); 1297 if (d->strip_mods && btf_is_mod(t)) 1298 goto skip_mod; 1299 1300 err = btf_dump_push_decl_stack_id(d, id); 1301 if (err < 0) { 1302 /* 1303 * if we don't have enough memory for entire type decl 1304 * chain, restore stack, emit warning, and try to 1305 * proceed nevertheless 1306 */ 1307 pr_warn("not enough memory for decl stack:%d", err); 1308 d->decl_stack_cnt = stack_start; 1309 return; 1310 } 1311 skip_mod: 1312 /* VOID */ 1313 if (id == 0) 1314 break; 1315 1316 switch (btf_kind(t)) { 1317 case BTF_KIND_PTR: 1318 case BTF_KIND_VOLATILE: 1319 case BTF_KIND_CONST: 1320 case BTF_KIND_RESTRICT: 1321 case BTF_KIND_FUNC_PROTO: 1322 case BTF_KIND_TYPE_TAG: 1323 id = t->type; 1324 break; 1325 case BTF_KIND_ARRAY: 1326 id = btf_array(t)->type; 1327 break; 1328 case BTF_KIND_INT: 1329 case BTF_KIND_ENUM: 1330 case BTF_KIND_ENUM64: 1331 case BTF_KIND_FWD: 1332 case BTF_KIND_STRUCT: 1333 case BTF_KIND_UNION: 1334 case BTF_KIND_TYPEDEF: 1335 case BTF_KIND_FLOAT: 1336 goto done; 1337 default: 1338 pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n", 1339 btf_kind(t), id); 1340 goto done; 1341 } 1342 } 1343 done: 1344 /* 1345 * We might be inside a chain of declarations (e.g., array of function 1346 * pointers returning anonymous (so inlined) structs, having another 1347 * array field). Each of those needs its own "stack frame" to handle 1348 * emitting of declarations. Those stack frames are non-overlapping 1349 * portions of shared btf_dump->decl_stack. To make it a bit nicer to 1350 * handle this set of nested stacks, we create a view corresponding to 1351 * our own "stack frame" and work with it as an independent stack. 1352 * We'll need to clean up after emit_type_chain() returns, though. 1353 */ 1354 decl_stack.ids = d->decl_stack + stack_start; 1355 decl_stack.cnt = d->decl_stack_cnt - stack_start; 1356 btf_dump_emit_type_chain(d, &decl_stack, fname, lvl); 1357 /* 1358 * emit_type_chain() guarantees that it will pop its entire decl_stack 1359 * frame before returning. But it works with a read-only view into 1360 * decl_stack, so it doesn't actually pop anything from the 1361 * perspective of shared btf_dump->decl_stack, per se. We need to 1362 * reset decl_stack state to how it was before us to avoid it growing 1363 * all the time. 1364 */ 1365 d->decl_stack_cnt = stack_start; 1366 } 1367 1368 static void btf_dump_emit_mods(struct btf_dump *d, struct id_stack *decl_stack) 1369 { 1370 const struct btf_type *t; 1371 __u32 id; 1372 1373 while (decl_stack->cnt) { 1374 id = decl_stack->ids[decl_stack->cnt - 1]; 1375 t = btf__type_by_id(d->btf, id); 1376 1377 switch (btf_kind(t)) { 1378 case BTF_KIND_VOLATILE: 1379 btf_dump_printf(d, "volatile "); 1380 break; 1381 case BTF_KIND_CONST: 1382 btf_dump_printf(d, "const "); 1383 break; 1384 case BTF_KIND_RESTRICT: 1385 btf_dump_printf(d, "restrict "); 1386 break; 1387 default: 1388 return; 1389 } 1390 decl_stack->cnt--; 1391 } 1392 } 1393 1394 static void btf_dump_drop_mods(struct btf_dump *d, struct id_stack *decl_stack) 1395 { 1396 const struct btf_type *t; 1397 __u32 id; 1398 1399 while (decl_stack->cnt) { 1400 id = decl_stack->ids[decl_stack->cnt - 1]; 1401 t = btf__type_by_id(d->btf, id); 1402 if (!btf_is_mod(t)) 1403 return; 1404 decl_stack->cnt--; 1405 } 1406 } 1407 1408 static void btf_dump_emit_name(const struct btf_dump *d, 1409 const char *name, bool last_was_ptr) 1410 { 1411 bool separate = name[0] && !last_was_ptr; 1412 1413 btf_dump_printf(d, "%s%s", separate ? " " : "", name); 1414 } 1415 1416 static void btf_dump_emit_type_chain(struct btf_dump *d, 1417 struct id_stack *decls, 1418 const char *fname, int lvl) 1419 { 1420 /* 1421 * last_was_ptr is used to determine if we need to separate pointer 1422 * asterisk (*) from previous part of type signature with space, so 1423 * that we get `int ***`, instead of `int * * *`. We default to true 1424 * for cases where we have single pointer in a chain. E.g., in ptr -> 1425 * func_proto case. func_proto will start a new emit_type_chain call 1426 * with just ptr, which should be emitted as (*) or (*<fname>), so we 1427 * don't want to prepend space for that last pointer. 1428 */ 1429 bool last_was_ptr = true; 1430 const struct btf_type *t; 1431 const char *name; 1432 __u16 kind; 1433 __u32 id; 1434 1435 while (decls->cnt) { 1436 id = decls->ids[--decls->cnt]; 1437 if (id == 0) { 1438 /* VOID is a special snowflake */ 1439 btf_dump_emit_mods(d, decls); 1440 btf_dump_printf(d, "void"); 1441 last_was_ptr = false; 1442 continue; 1443 } 1444 1445 t = btf__type_by_id(d->btf, id); 1446 kind = btf_kind(t); 1447 1448 switch (kind) { 1449 case BTF_KIND_INT: 1450 case BTF_KIND_FLOAT: 1451 btf_dump_emit_mods(d, decls); 1452 name = btf_name_of(d, t->name_off); 1453 btf_dump_printf(d, "%s", name); 1454 break; 1455 case BTF_KIND_STRUCT: 1456 case BTF_KIND_UNION: 1457 btf_dump_emit_mods(d, decls); 1458 /* inline anonymous struct/union */ 1459 if (t->name_off == 0 && !d->skip_anon_defs) 1460 btf_dump_emit_struct_def(d, id, t, lvl); 1461 else 1462 btf_dump_emit_struct_fwd(d, id, t); 1463 break; 1464 case BTF_KIND_ENUM: 1465 case BTF_KIND_ENUM64: 1466 btf_dump_emit_mods(d, decls); 1467 /* inline anonymous enum */ 1468 if (t->name_off == 0 && !d->skip_anon_defs) 1469 btf_dump_emit_enum_def(d, id, t, lvl); 1470 else 1471 btf_dump_emit_enum_fwd(d, id, t); 1472 break; 1473 case BTF_KIND_FWD: 1474 btf_dump_emit_mods(d, decls); 1475 btf_dump_emit_fwd_def(d, id, t); 1476 break; 1477 case BTF_KIND_TYPEDEF: 1478 btf_dump_emit_mods(d, decls); 1479 btf_dump_printf(d, "%s", btf_dump_ident_name(d, id)); 1480 break; 1481 case BTF_KIND_PTR: 1482 btf_dump_printf(d, "%s", last_was_ptr ? "*" : " *"); 1483 break; 1484 case BTF_KIND_VOLATILE: 1485 btf_dump_printf(d, " volatile"); 1486 break; 1487 case BTF_KIND_CONST: 1488 btf_dump_printf(d, " const"); 1489 break; 1490 case BTF_KIND_RESTRICT: 1491 btf_dump_printf(d, " restrict"); 1492 break; 1493 case BTF_KIND_TYPE_TAG: 1494 btf_dump_emit_mods(d, decls); 1495 name = btf_name_of(d, t->name_off); 1496 btf_dump_printf(d, " __attribute__((btf_type_tag(\"%s\")))", name); 1497 break; 1498 case BTF_KIND_ARRAY: { 1499 const struct btf_array *a = btf_array(t); 1500 const struct btf_type *next_t; 1501 __u32 next_id; 1502 bool multidim; 1503 /* 1504 * GCC has a bug 1505 * (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=8354) 1506 * which causes it to emit extra const/volatile 1507 * modifiers for an array, if array's element type has 1508 * const/volatile modifiers. Clang doesn't do that. 1509 * In general, it doesn't seem very meaningful to have 1510 * a const/volatile modifier for array, so we are 1511 * going to silently skip them here. 1512 */ 1513 btf_dump_drop_mods(d, decls); 1514 1515 if (decls->cnt == 0) { 1516 btf_dump_emit_name(d, fname, last_was_ptr); 1517 btf_dump_printf(d, "[%u]", a->nelems); 1518 return; 1519 } 1520 1521 next_id = decls->ids[decls->cnt - 1]; 1522 next_t = btf__type_by_id(d->btf, next_id); 1523 multidim = btf_is_array(next_t); 1524 /* we need space if we have named non-pointer */ 1525 if (fname[0] && !last_was_ptr) 1526 btf_dump_printf(d, " "); 1527 /* no parentheses for multi-dimensional array */ 1528 if (!multidim) 1529 btf_dump_printf(d, "("); 1530 btf_dump_emit_type_chain(d, decls, fname, lvl); 1531 if (!multidim) 1532 btf_dump_printf(d, ")"); 1533 btf_dump_printf(d, "[%u]", a->nelems); 1534 return; 1535 } 1536 case BTF_KIND_FUNC_PROTO: { 1537 const struct btf_param *p = btf_params(t); 1538 __u16 vlen = btf_vlen(t); 1539 int i; 1540 1541 /* 1542 * GCC emits extra volatile qualifier for 1543 * __attribute__((noreturn)) function pointers. Clang 1544 * doesn't do it. It's a GCC quirk for backwards 1545 * compatibility with code written for GCC <2.5. So, 1546 * similarly to extra qualifiers for array, just drop 1547 * them, instead of handling them. 1548 */ 1549 btf_dump_drop_mods(d, decls); 1550 if (decls->cnt) { 1551 btf_dump_printf(d, " ("); 1552 btf_dump_emit_type_chain(d, decls, fname, lvl); 1553 btf_dump_printf(d, ")"); 1554 } else { 1555 btf_dump_emit_name(d, fname, last_was_ptr); 1556 } 1557 btf_dump_printf(d, "("); 1558 /* 1559 * Clang for BPF target generates func_proto with no 1560 * args as a func_proto with a single void arg (e.g., 1561 * `int (*f)(void)` vs just `int (*f)()`). We are 1562 * going to emit valid empty args (void) syntax for 1563 * such case. Similarly and conveniently, valid 1564 * no args case can be special-cased here as well. 1565 */ 1566 if (vlen == 0 || (vlen == 1 && p->type == 0)) { 1567 btf_dump_printf(d, "void)"); 1568 return; 1569 } 1570 1571 for (i = 0; i < vlen; i++, p++) { 1572 if (i > 0) 1573 btf_dump_printf(d, ", "); 1574 1575 /* last arg of type void is vararg */ 1576 if (i == vlen - 1 && p->type == 0) { 1577 btf_dump_printf(d, "..."); 1578 break; 1579 } 1580 1581 name = btf_name_of(d, p->name_off); 1582 btf_dump_emit_type_decl(d, p->type, name, lvl); 1583 } 1584 1585 btf_dump_printf(d, ")"); 1586 return; 1587 } 1588 default: 1589 pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n", 1590 kind, id); 1591 return; 1592 } 1593 1594 last_was_ptr = kind == BTF_KIND_PTR; 1595 } 1596 1597 btf_dump_emit_name(d, fname, last_was_ptr); 1598 } 1599 1600 /* show type name as (type_name) */ 1601 static void btf_dump_emit_type_cast(struct btf_dump *d, __u32 id, 1602 bool top_level) 1603 { 1604 const struct btf_type *t; 1605 1606 /* for array members, we don't bother emitting type name for each 1607 * member to avoid the redundancy of 1608 * .name = (char[4])[(char)'f',(char)'o',(char)'o',] 1609 */ 1610 if (d->typed_dump->is_array_member) 1611 return; 1612 1613 /* avoid type name specification for variable/section; it will be done 1614 * for the associated variable value(s). 1615 */ 1616 t = btf__type_by_id(d->btf, id); 1617 if (btf_is_var(t) || btf_is_datasec(t)) 1618 return; 1619 1620 if (top_level) 1621 btf_dump_printf(d, "("); 1622 1623 d->skip_anon_defs = true; 1624 d->strip_mods = true; 1625 btf_dump_emit_type_decl(d, id, "", 0); 1626 d->strip_mods = false; 1627 d->skip_anon_defs = false; 1628 1629 if (top_level) 1630 btf_dump_printf(d, ")"); 1631 } 1632 1633 /* return number of duplicates (occurrences) of a given name */ 1634 static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_map, 1635 const char *orig_name) 1636 { 1637 char *old_name, *new_name; 1638 size_t dup_cnt = 0; 1639 int err; 1640 1641 new_name = strdup(orig_name); 1642 if (!new_name) 1643 return 1; 1644 1645 (void)hashmap__find(name_map, orig_name, &dup_cnt); 1646 dup_cnt++; 1647 1648 err = hashmap__set(name_map, new_name, dup_cnt, &old_name, NULL); 1649 if (err) 1650 free(new_name); 1651 1652 free(old_name); 1653 1654 return dup_cnt; 1655 } 1656 1657 static const char *btf_dump_resolve_name(struct btf_dump *d, __u32 id, 1658 struct hashmap *name_map) 1659 { 1660 struct btf_dump_type_aux_state *s = &d->type_states[id]; 1661 const struct btf_type *t = btf__type_by_id(d->btf, id); 1662 const char *orig_name = btf_name_of(d, t->name_off); 1663 const char **cached_name = &d->cached_names[id]; 1664 size_t dup_cnt; 1665 1666 if (t->name_off == 0) 1667 return ""; 1668 1669 if (s->name_resolved) 1670 return *cached_name ? *cached_name : orig_name; 1671 1672 if (btf_is_fwd(t) || (btf_is_enum(t) && btf_vlen(t) == 0)) { 1673 s->name_resolved = 1; 1674 return orig_name; 1675 } 1676 1677 dup_cnt = btf_dump_name_dups(d, name_map, orig_name); 1678 if (dup_cnt > 1) { 1679 const size_t max_len = 256; 1680 char new_name[max_len]; 1681 1682 snprintf(new_name, max_len, "%s___%zu", orig_name, dup_cnt); 1683 *cached_name = strdup(new_name); 1684 } 1685 1686 s->name_resolved = 1; 1687 return *cached_name ? *cached_name : orig_name; 1688 } 1689 1690 static const char *btf_dump_type_name(struct btf_dump *d, __u32 id) 1691 { 1692 return btf_dump_resolve_name(d, id, d->type_names); 1693 } 1694 1695 static const char *btf_dump_ident_name(struct btf_dump *d, __u32 id) 1696 { 1697 return btf_dump_resolve_name(d, id, d->ident_names); 1698 } 1699 1700 static int btf_dump_dump_type_data(struct btf_dump *d, 1701 const char *fname, 1702 const struct btf_type *t, 1703 __u32 id, 1704 const void *data, 1705 __u8 bits_offset, 1706 __u8 bit_sz); 1707 1708 static const char *btf_dump_data_newline(struct btf_dump *d) 1709 { 1710 return d->typed_dump->compact || d->typed_dump->depth == 0 ? "" : "\n"; 1711 } 1712 1713 static const char *btf_dump_data_delim(struct btf_dump *d) 1714 { 1715 return d->typed_dump->depth == 0 ? "" : ","; 1716 } 1717 1718 static void btf_dump_data_pfx(struct btf_dump *d) 1719 { 1720 int i, lvl = d->typed_dump->indent_lvl + d->typed_dump->depth; 1721 1722 if (d->typed_dump->compact) 1723 return; 1724 1725 for (i = 0; i < lvl; i++) 1726 btf_dump_printf(d, "%s", d->typed_dump->indent_str); 1727 } 1728 1729 /* A macro is used here as btf_type_value[s]() appends format specifiers 1730 * to the format specifier passed in; these do the work of appending 1731 * delimiters etc while the caller simply has to specify the type values 1732 * in the format specifier + value(s). 1733 */ 1734 #define btf_dump_type_values(d, fmt, ...) \ 1735 btf_dump_printf(d, fmt "%s%s", \ 1736 ##__VA_ARGS__, \ 1737 btf_dump_data_delim(d), \ 1738 btf_dump_data_newline(d)) 1739 1740 static int btf_dump_unsupported_data(struct btf_dump *d, 1741 const struct btf_type *t, 1742 __u32 id) 1743 { 1744 btf_dump_printf(d, "<unsupported kind:%u>", btf_kind(t)); 1745 return -ENOTSUP; 1746 } 1747 1748 static int btf_dump_get_bitfield_value(struct btf_dump *d, 1749 const struct btf_type *t, 1750 const void *data, 1751 __u8 bits_offset, 1752 __u8 bit_sz, 1753 __u64 *value) 1754 { 1755 __u16 left_shift_bits, right_shift_bits; 1756 const __u8 *bytes = data; 1757 __u8 nr_copy_bits; 1758 __u64 num = 0; 1759 int i; 1760 1761 /* Maximum supported bitfield size is 64 bits */ 1762 if (t->size > 8) { 1763 pr_warn("unexpected bitfield size %d\n", t->size); 1764 return -EINVAL; 1765 } 1766 1767 /* Bitfield value retrieval is done in two steps; first relevant bytes are 1768 * stored in num, then we left/right shift num to eliminate irrelevant bits. 1769 */ 1770 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ 1771 for (i = t->size - 1; i >= 0; i--) 1772 num = num * 256 + bytes[i]; 1773 nr_copy_bits = bit_sz + bits_offset; 1774 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ 1775 for (i = 0; i < t->size; i++) 1776 num = num * 256 + bytes[i]; 1777 nr_copy_bits = t->size * 8 - bits_offset; 1778 #else 1779 # error "Unrecognized __BYTE_ORDER__" 1780 #endif 1781 left_shift_bits = 64 - nr_copy_bits; 1782 right_shift_bits = 64 - bit_sz; 1783 1784 *value = (num << left_shift_bits) >> right_shift_bits; 1785 1786 return 0; 1787 } 1788 1789 static int btf_dump_bitfield_check_zero(struct btf_dump *d, 1790 const struct btf_type *t, 1791 const void *data, 1792 __u8 bits_offset, 1793 __u8 bit_sz) 1794 { 1795 __u64 check_num; 1796 int err; 1797 1798 err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, &check_num); 1799 if (err) 1800 return err; 1801 if (check_num == 0) 1802 return -ENODATA; 1803 return 0; 1804 } 1805 1806 static int btf_dump_bitfield_data(struct btf_dump *d, 1807 const struct btf_type *t, 1808 const void *data, 1809 __u8 bits_offset, 1810 __u8 bit_sz) 1811 { 1812 __u64 print_num; 1813 int err; 1814 1815 err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, &print_num); 1816 if (err) 1817 return err; 1818 1819 btf_dump_type_values(d, "0x%llx", (unsigned long long)print_num); 1820 1821 return 0; 1822 } 1823 1824 /* ints, floats and ptrs */ 1825 static int btf_dump_base_type_check_zero(struct btf_dump *d, 1826 const struct btf_type *t, 1827 __u32 id, 1828 const void *data) 1829 { 1830 static __u8 bytecmp[16] = {}; 1831 int nr_bytes; 1832 1833 /* For pointer types, pointer size is not defined on a per-type basis. 1834 * On dump creation however, we store the pointer size. 1835 */ 1836 if (btf_kind(t) == BTF_KIND_PTR) 1837 nr_bytes = d->ptr_sz; 1838 else 1839 nr_bytes = t->size; 1840 1841 if (nr_bytes < 1 || nr_bytes > 16) { 1842 pr_warn("unexpected size %d for id [%u]\n", nr_bytes, id); 1843 return -EINVAL; 1844 } 1845 1846 if (memcmp(data, bytecmp, nr_bytes) == 0) 1847 return -ENODATA; 1848 return 0; 1849 } 1850 1851 static bool ptr_is_aligned(const struct btf *btf, __u32 type_id, 1852 const void *data) 1853 { 1854 int alignment = btf__align_of(btf, type_id); 1855 1856 if (alignment == 0) 1857 return false; 1858 1859 return ((uintptr_t)data) % alignment == 0; 1860 } 1861 1862 static int btf_dump_int_data(struct btf_dump *d, 1863 const struct btf_type *t, 1864 __u32 type_id, 1865 const void *data, 1866 __u8 bits_offset) 1867 { 1868 __u8 encoding = btf_int_encoding(t); 1869 bool sign = encoding & BTF_INT_SIGNED; 1870 char buf[16] __attribute__((aligned(16))); 1871 int sz = t->size; 1872 1873 if (sz == 0 || sz > sizeof(buf)) { 1874 pr_warn("unexpected size %d for id [%u]\n", sz, type_id); 1875 return -EINVAL; 1876 } 1877 1878 /* handle packed int data - accesses of integers not aligned on 1879 * int boundaries can cause problems on some platforms. 1880 */ 1881 if (!ptr_is_aligned(d->btf, type_id, data)) { 1882 memcpy(buf, data, sz); 1883 data = buf; 1884 } 1885 1886 switch (sz) { 1887 case 16: { 1888 const __u64 *ints = data; 1889 __u64 lsi, msi; 1890 1891 /* avoid use of __int128 as some 32-bit platforms do not 1892 * support it. 1893 */ 1894 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ 1895 lsi = ints[0]; 1896 msi = ints[1]; 1897 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ 1898 lsi = ints[1]; 1899 msi = ints[0]; 1900 #else 1901 # error "Unrecognized __BYTE_ORDER__" 1902 #endif 1903 if (msi == 0) 1904 btf_dump_type_values(d, "0x%llx", (unsigned long long)lsi); 1905 else 1906 btf_dump_type_values(d, "0x%llx%016llx", (unsigned long long)msi, 1907 (unsigned long long)lsi); 1908 break; 1909 } 1910 case 8: 1911 if (sign) 1912 btf_dump_type_values(d, "%lld", *(long long *)data); 1913 else 1914 btf_dump_type_values(d, "%llu", *(unsigned long long *)data); 1915 break; 1916 case 4: 1917 if (sign) 1918 btf_dump_type_values(d, "%d", *(__s32 *)data); 1919 else 1920 btf_dump_type_values(d, "%u", *(__u32 *)data); 1921 break; 1922 case 2: 1923 if (sign) 1924 btf_dump_type_values(d, "%d", *(__s16 *)data); 1925 else 1926 btf_dump_type_values(d, "%u", *(__u16 *)data); 1927 break; 1928 case 1: 1929 if (d->typed_dump->is_array_char) { 1930 /* check for null terminator */ 1931 if (d->typed_dump->is_array_terminated) 1932 break; 1933 if (*(char *)data == '\0') { 1934 btf_dump_type_values(d, "'\\0'"); 1935 d->typed_dump->is_array_terminated = true; 1936 break; 1937 } 1938 if (isprint(*(char *)data)) { 1939 btf_dump_type_values(d, "'%c'", *(char *)data); 1940 break; 1941 } 1942 } 1943 if (sign) 1944 btf_dump_type_values(d, "%d", *(__s8 *)data); 1945 else 1946 btf_dump_type_values(d, "%u", *(__u8 *)data); 1947 break; 1948 default: 1949 pr_warn("unexpected sz %d for id [%u]\n", sz, type_id); 1950 return -EINVAL; 1951 } 1952 return 0; 1953 } 1954 1955 union float_data { 1956 long double ld; 1957 double d; 1958 float f; 1959 }; 1960 1961 static int btf_dump_float_data(struct btf_dump *d, 1962 const struct btf_type *t, 1963 __u32 type_id, 1964 const void *data) 1965 { 1966 const union float_data *flp = data; 1967 union float_data fl; 1968 int sz = t->size; 1969 1970 /* handle unaligned data; copy to local union */ 1971 if (!ptr_is_aligned(d->btf, type_id, data)) { 1972 memcpy(&fl, data, sz); 1973 flp = &fl; 1974 } 1975 1976 switch (sz) { 1977 case 16: 1978 btf_dump_type_values(d, "%Lf", flp->ld); 1979 break; 1980 case 8: 1981 btf_dump_type_values(d, "%lf", flp->d); 1982 break; 1983 case 4: 1984 btf_dump_type_values(d, "%f", flp->f); 1985 break; 1986 default: 1987 pr_warn("unexpected size %d for id [%u]\n", sz, type_id); 1988 return -EINVAL; 1989 } 1990 return 0; 1991 } 1992 1993 static int btf_dump_var_data(struct btf_dump *d, 1994 const struct btf_type *v, 1995 __u32 id, 1996 const void *data) 1997 { 1998 enum btf_func_linkage linkage = btf_var(v)->linkage; 1999 const struct btf_type *t; 2000 const char *l; 2001 __u32 type_id; 2002 2003 switch (linkage) { 2004 case BTF_FUNC_STATIC: 2005 l = "static "; 2006 break; 2007 case BTF_FUNC_EXTERN: 2008 l = "extern "; 2009 break; 2010 case BTF_FUNC_GLOBAL: 2011 default: 2012 l = ""; 2013 break; 2014 } 2015 2016 /* format of output here is [linkage] [type] [varname] = (type)value, 2017 * for example "static int cpu_profile_flip = (int)1" 2018 */ 2019 btf_dump_printf(d, "%s", l); 2020 type_id = v->type; 2021 t = btf__type_by_id(d->btf, type_id); 2022 btf_dump_emit_type_cast(d, type_id, false); 2023 btf_dump_printf(d, " %s = ", btf_name_of(d, v->name_off)); 2024 return btf_dump_dump_type_data(d, NULL, t, type_id, data, 0, 0); 2025 } 2026 2027 static int btf_dump_array_data(struct btf_dump *d, 2028 const struct btf_type *t, 2029 __u32 id, 2030 const void *data) 2031 { 2032 const struct btf_array *array = btf_array(t); 2033 const struct btf_type *elem_type; 2034 __u32 i, elem_type_id; 2035 __s64 elem_size; 2036 bool is_array_member; 2037 bool is_array_terminated; 2038 2039 elem_type_id = array->type; 2040 elem_type = skip_mods_and_typedefs(d->btf, elem_type_id, NULL); 2041 elem_size = btf__resolve_size(d->btf, elem_type_id); 2042 if (elem_size <= 0) { 2043 pr_warn("unexpected elem size %zd for array type [%u]\n", 2044 (ssize_t)elem_size, id); 2045 return -EINVAL; 2046 } 2047 2048 if (btf_is_int(elem_type)) { 2049 /* 2050 * BTF_INT_CHAR encoding never seems to be set for 2051 * char arrays, so if size is 1 and element is 2052 * printable as a char, we'll do that. 2053 */ 2054 if (elem_size == 1) 2055 d->typed_dump->is_array_char = true; 2056 } 2057 2058 /* note that we increment depth before calling btf_dump_print() below; 2059 * this is intentional. btf_dump_data_newline() will not print a 2060 * newline for depth 0 (since this leaves us with trailing newlines 2061 * at the end of typed display), so depth is incremented first. 2062 * For similar reasons, we decrement depth before showing the closing 2063 * parenthesis. 2064 */ 2065 d->typed_dump->depth++; 2066 btf_dump_printf(d, "[%s", btf_dump_data_newline(d)); 2067 2068 /* may be a multidimensional array, so store current "is array member" 2069 * status so we can restore it correctly later. 2070 */ 2071 is_array_member = d->typed_dump->is_array_member; 2072 d->typed_dump->is_array_member = true; 2073 is_array_terminated = d->typed_dump->is_array_terminated; 2074 d->typed_dump->is_array_terminated = false; 2075 for (i = 0; i < array->nelems; i++, data += elem_size) { 2076 if (d->typed_dump->is_array_terminated) 2077 break; 2078 btf_dump_dump_type_data(d, NULL, elem_type, elem_type_id, data, 0, 0); 2079 } 2080 d->typed_dump->is_array_member = is_array_member; 2081 d->typed_dump->is_array_terminated = is_array_terminated; 2082 d->typed_dump->depth--; 2083 btf_dump_data_pfx(d); 2084 btf_dump_type_values(d, "]"); 2085 2086 return 0; 2087 } 2088 2089 static int btf_dump_struct_data(struct btf_dump *d, 2090 const struct btf_type *t, 2091 __u32 id, 2092 const void *data) 2093 { 2094 const struct btf_member *m = btf_members(t); 2095 __u16 n = btf_vlen(t); 2096 int i, err = 0; 2097 2098 /* note that we increment depth before calling btf_dump_print() below; 2099 * this is intentional. btf_dump_data_newline() will not print a 2100 * newline for depth 0 (since this leaves us with trailing newlines 2101 * at the end of typed display), so depth is incremented first. 2102 * For similar reasons, we decrement depth before showing the closing 2103 * parenthesis. 2104 */ 2105 d->typed_dump->depth++; 2106 btf_dump_printf(d, "{%s", btf_dump_data_newline(d)); 2107 2108 for (i = 0; i < n; i++, m++) { 2109 const struct btf_type *mtype; 2110 const char *mname; 2111 __u32 moffset; 2112 __u8 bit_sz; 2113 2114 mtype = btf__type_by_id(d->btf, m->type); 2115 mname = btf_name_of(d, m->name_off); 2116 moffset = btf_member_bit_offset(t, i); 2117 2118 bit_sz = btf_member_bitfield_size(t, i); 2119 err = btf_dump_dump_type_data(d, mname, mtype, m->type, data + moffset / 8, 2120 moffset % 8, bit_sz); 2121 if (err < 0) 2122 return err; 2123 } 2124 d->typed_dump->depth--; 2125 btf_dump_data_pfx(d); 2126 btf_dump_type_values(d, "}"); 2127 return err; 2128 } 2129 2130 union ptr_data { 2131 unsigned int p; 2132 unsigned long long lp; 2133 }; 2134 2135 static int btf_dump_ptr_data(struct btf_dump *d, 2136 const struct btf_type *t, 2137 __u32 id, 2138 const void *data) 2139 { 2140 if (ptr_is_aligned(d->btf, id, data) && d->ptr_sz == sizeof(void *)) { 2141 btf_dump_type_values(d, "%p", *(void **)data); 2142 } else { 2143 union ptr_data pt; 2144 2145 memcpy(&pt, data, d->ptr_sz); 2146 if (d->ptr_sz == 4) 2147 btf_dump_type_values(d, "0x%x", pt.p); 2148 else 2149 btf_dump_type_values(d, "0x%llx", pt.lp); 2150 } 2151 return 0; 2152 } 2153 2154 static int btf_dump_get_enum_value(struct btf_dump *d, 2155 const struct btf_type *t, 2156 const void *data, 2157 __u32 id, 2158 __s64 *value) 2159 { 2160 bool is_signed = btf_kflag(t); 2161 2162 if (!ptr_is_aligned(d->btf, id, data)) { 2163 __u64 val; 2164 int err; 2165 2166 err = btf_dump_get_bitfield_value(d, t, data, 0, 0, &val); 2167 if (err) 2168 return err; 2169 *value = (__s64)val; 2170 return 0; 2171 } 2172 2173 switch (t->size) { 2174 case 8: 2175 *value = *(__s64 *)data; 2176 return 0; 2177 case 4: 2178 *value = is_signed ? (__s64)*(__s32 *)data : *(__u32 *)data; 2179 return 0; 2180 case 2: 2181 *value = is_signed ? *(__s16 *)data : *(__u16 *)data; 2182 return 0; 2183 case 1: 2184 *value = is_signed ? *(__s8 *)data : *(__u8 *)data; 2185 return 0; 2186 default: 2187 pr_warn("unexpected size %d for enum, id:[%u]\n", t->size, id); 2188 return -EINVAL; 2189 } 2190 } 2191 2192 static int btf_dump_enum_data(struct btf_dump *d, 2193 const struct btf_type *t, 2194 __u32 id, 2195 const void *data) 2196 { 2197 bool is_signed; 2198 __s64 value; 2199 int i, err; 2200 2201 err = btf_dump_get_enum_value(d, t, data, id, &value); 2202 if (err) 2203 return err; 2204 2205 is_signed = btf_kflag(t); 2206 if (btf_is_enum(t)) { 2207 const struct btf_enum *e; 2208 2209 for (i = 0, e = btf_enum(t); i < btf_vlen(t); i++, e++) { 2210 if (value != e->val) 2211 continue; 2212 btf_dump_type_values(d, "%s", btf_name_of(d, e->name_off)); 2213 return 0; 2214 } 2215 2216 btf_dump_type_values(d, is_signed ? "%d" : "%u", value); 2217 } else { 2218 const struct btf_enum64 *e; 2219 2220 for (i = 0, e = btf_enum64(t); i < btf_vlen(t); i++, e++) { 2221 if (value != btf_enum64_value(e)) 2222 continue; 2223 btf_dump_type_values(d, "%s", btf_name_of(d, e->name_off)); 2224 return 0; 2225 } 2226 2227 btf_dump_type_values(d, is_signed ? "%lldLL" : "%lluULL", 2228 (unsigned long long)value); 2229 } 2230 return 0; 2231 } 2232 2233 static int btf_dump_datasec_data(struct btf_dump *d, 2234 const struct btf_type *t, 2235 __u32 id, 2236 const void *data) 2237 { 2238 const struct btf_var_secinfo *vsi; 2239 const struct btf_type *var; 2240 __u32 i; 2241 int err; 2242 2243 btf_dump_type_values(d, "SEC(\"%s\") ", btf_name_of(d, t->name_off)); 2244 2245 for (i = 0, vsi = btf_var_secinfos(t); i < btf_vlen(t); i++, vsi++) { 2246 var = btf__type_by_id(d->btf, vsi->type); 2247 err = btf_dump_dump_type_data(d, NULL, var, vsi->type, data + vsi->offset, 0, 0); 2248 if (err < 0) 2249 return err; 2250 btf_dump_printf(d, ";"); 2251 } 2252 return 0; 2253 } 2254 2255 /* return size of type, or if base type overflows, return -E2BIG. */ 2256 static int btf_dump_type_data_check_overflow(struct btf_dump *d, 2257 const struct btf_type *t, 2258 __u32 id, 2259 const void *data, 2260 __u8 bits_offset, 2261 __u8 bit_sz) 2262 { 2263 __s64 size; 2264 2265 if (bit_sz) { 2266 /* bits_offset is at most 7. bit_sz is at most 128. */ 2267 __u8 nr_bytes = (bits_offset + bit_sz + 7) / 8; 2268 2269 /* When bit_sz is non zero, it is called from 2270 * btf_dump_struct_data() where it only cares about 2271 * negative error value. 2272 * Return nr_bytes in success case to make it 2273 * consistent as the regular integer case below. 2274 */ 2275 return data + nr_bytes > d->typed_dump->data_end ? -E2BIG : nr_bytes; 2276 } 2277 2278 size = btf__resolve_size(d->btf, id); 2279 2280 if (size < 0 || size >= INT_MAX) { 2281 pr_warn("unexpected size [%zu] for id [%u]\n", 2282 (size_t)size, id); 2283 return -EINVAL; 2284 } 2285 2286 /* Only do overflow checking for base types; we do not want to 2287 * avoid showing part of a struct, union or array, even if we 2288 * do not have enough data to show the full object. By 2289 * restricting overflow checking to base types we can ensure 2290 * that partial display succeeds, while avoiding overflowing 2291 * and using bogus data for display. 2292 */ 2293 t = skip_mods_and_typedefs(d->btf, id, NULL); 2294 if (!t) { 2295 pr_warn("unexpected error skipping mods/typedefs for id [%u]\n", 2296 id); 2297 return -EINVAL; 2298 } 2299 2300 switch (btf_kind(t)) { 2301 case BTF_KIND_INT: 2302 case BTF_KIND_FLOAT: 2303 case BTF_KIND_PTR: 2304 case BTF_KIND_ENUM: 2305 case BTF_KIND_ENUM64: 2306 if (data + bits_offset / 8 + size > d->typed_dump->data_end) 2307 return -E2BIG; 2308 break; 2309 default: 2310 break; 2311 } 2312 return (int)size; 2313 } 2314 2315 static int btf_dump_type_data_check_zero(struct btf_dump *d, 2316 const struct btf_type *t, 2317 __u32 id, 2318 const void *data, 2319 __u8 bits_offset, 2320 __u8 bit_sz) 2321 { 2322 __s64 value; 2323 int i, err; 2324 2325 /* toplevel exceptions; we show zero values if 2326 * - we ask for them (emit_zeros) 2327 * - if we are at top-level so we see "struct empty { }" 2328 * - or if we are an array member and the array is non-empty and 2329 * not a char array; we don't want to be in a situation where we 2330 * have an integer array 0, 1, 0, 1 and only show non-zero values. 2331 * If the array contains zeroes only, or is a char array starting 2332 * with a '\0', the array-level check_zero() will prevent showing it; 2333 * we are concerned with determining zero value at the array member 2334 * level here. 2335 */ 2336 if (d->typed_dump->emit_zeroes || d->typed_dump->depth == 0 || 2337 (d->typed_dump->is_array_member && 2338 !d->typed_dump->is_array_char)) 2339 return 0; 2340 2341 t = skip_mods_and_typedefs(d->btf, id, NULL); 2342 2343 switch (btf_kind(t)) { 2344 case BTF_KIND_INT: 2345 if (bit_sz) 2346 return btf_dump_bitfield_check_zero(d, t, data, bits_offset, bit_sz); 2347 return btf_dump_base_type_check_zero(d, t, id, data); 2348 case BTF_KIND_FLOAT: 2349 case BTF_KIND_PTR: 2350 return btf_dump_base_type_check_zero(d, t, id, data); 2351 case BTF_KIND_ARRAY: { 2352 const struct btf_array *array = btf_array(t); 2353 const struct btf_type *elem_type; 2354 __u32 elem_type_id, elem_size; 2355 bool ischar; 2356 2357 elem_type_id = array->type; 2358 elem_size = btf__resolve_size(d->btf, elem_type_id); 2359 elem_type = skip_mods_and_typedefs(d->btf, elem_type_id, NULL); 2360 2361 ischar = btf_is_int(elem_type) && elem_size == 1; 2362 2363 /* check all elements; if _any_ element is nonzero, all 2364 * of array is displayed. We make an exception however 2365 * for char arrays where the first element is 0; these 2366 * are considered zeroed also, even if later elements are 2367 * non-zero because the string is terminated. 2368 */ 2369 for (i = 0; i < array->nelems; i++) { 2370 if (i == 0 && ischar && *(char *)data == 0) 2371 return -ENODATA; 2372 err = btf_dump_type_data_check_zero(d, elem_type, 2373 elem_type_id, 2374 data + 2375 (i * elem_size), 2376 bits_offset, 0); 2377 if (err != -ENODATA) 2378 return err; 2379 } 2380 return -ENODATA; 2381 } 2382 case BTF_KIND_STRUCT: 2383 case BTF_KIND_UNION: { 2384 const struct btf_member *m = btf_members(t); 2385 __u16 n = btf_vlen(t); 2386 2387 /* if any struct/union member is non-zero, the struct/union 2388 * is considered non-zero and dumped. 2389 */ 2390 for (i = 0; i < n; i++, m++) { 2391 const struct btf_type *mtype; 2392 __u32 moffset; 2393 2394 mtype = btf__type_by_id(d->btf, m->type); 2395 moffset = btf_member_bit_offset(t, i); 2396 2397 /* btf_int_bits() does not store member bitfield size; 2398 * bitfield size needs to be stored here so int display 2399 * of member can retrieve it. 2400 */ 2401 bit_sz = btf_member_bitfield_size(t, i); 2402 err = btf_dump_type_data_check_zero(d, mtype, m->type, data + moffset / 8, 2403 moffset % 8, bit_sz); 2404 if (err != ENODATA) 2405 return err; 2406 } 2407 return -ENODATA; 2408 } 2409 case BTF_KIND_ENUM: 2410 case BTF_KIND_ENUM64: 2411 err = btf_dump_get_enum_value(d, t, data, id, &value); 2412 if (err) 2413 return err; 2414 if (value == 0) 2415 return -ENODATA; 2416 return 0; 2417 default: 2418 return 0; 2419 } 2420 } 2421 2422 /* returns size of data dumped, or error. */ 2423 static int btf_dump_dump_type_data(struct btf_dump *d, 2424 const char *fname, 2425 const struct btf_type *t, 2426 __u32 id, 2427 const void *data, 2428 __u8 bits_offset, 2429 __u8 bit_sz) 2430 { 2431 int size, err = 0; 2432 2433 size = btf_dump_type_data_check_overflow(d, t, id, data, bits_offset, bit_sz); 2434 if (size < 0) 2435 return size; 2436 err = btf_dump_type_data_check_zero(d, t, id, data, bits_offset, bit_sz); 2437 if (err) { 2438 /* zeroed data is expected and not an error, so simply skip 2439 * dumping such data. Record other errors however. 2440 */ 2441 if (err == -ENODATA) 2442 return size; 2443 return err; 2444 } 2445 btf_dump_data_pfx(d); 2446 2447 if (!d->typed_dump->skip_names) { 2448 if (fname && strlen(fname) > 0) 2449 btf_dump_printf(d, ".%s = ", fname); 2450 btf_dump_emit_type_cast(d, id, true); 2451 } 2452 2453 t = skip_mods_and_typedefs(d->btf, id, NULL); 2454 2455 switch (btf_kind(t)) { 2456 case BTF_KIND_UNKN: 2457 case BTF_KIND_FWD: 2458 case BTF_KIND_FUNC: 2459 case BTF_KIND_FUNC_PROTO: 2460 case BTF_KIND_DECL_TAG: 2461 err = btf_dump_unsupported_data(d, t, id); 2462 break; 2463 case BTF_KIND_INT: 2464 if (bit_sz) 2465 err = btf_dump_bitfield_data(d, t, data, bits_offset, bit_sz); 2466 else 2467 err = btf_dump_int_data(d, t, id, data, bits_offset); 2468 break; 2469 case BTF_KIND_FLOAT: 2470 err = btf_dump_float_data(d, t, id, data); 2471 break; 2472 case BTF_KIND_PTR: 2473 err = btf_dump_ptr_data(d, t, id, data); 2474 break; 2475 case BTF_KIND_ARRAY: 2476 err = btf_dump_array_data(d, t, id, data); 2477 break; 2478 case BTF_KIND_STRUCT: 2479 case BTF_KIND_UNION: 2480 err = btf_dump_struct_data(d, t, id, data); 2481 break; 2482 case BTF_KIND_ENUM: 2483 case BTF_KIND_ENUM64: 2484 /* handle bitfield and int enum values */ 2485 if (bit_sz) { 2486 __u64 print_num; 2487 __s64 enum_val; 2488 2489 err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, 2490 &print_num); 2491 if (err) 2492 break; 2493 enum_val = (__s64)print_num; 2494 err = btf_dump_enum_data(d, t, id, &enum_val); 2495 } else 2496 err = btf_dump_enum_data(d, t, id, data); 2497 break; 2498 case BTF_KIND_VAR: 2499 err = btf_dump_var_data(d, t, id, data); 2500 break; 2501 case BTF_KIND_DATASEC: 2502 err = btf_dump_datasec_data(d, t, id, data); 2503 break; 2504 default: 2505 pr_warn("unexpected kind [%u] for id [%u]\n", 2506 BTF_INFO_KIND(t->info), id); 2507 return -EINVAL; 2508 } 2509 if (err < 0) 2510 return err; 2511 return size; 2512 } 2513 2514 int btf_dump__dump_type_data(struct btf_dump *d, __u32 id, 2515 const void *data, size_t data_sz, 2516 const struct btf_dump_type_data_opts *opts) 2517 { 2518 struct btf_dump_data typed_dump = {}; 2519 const struct btf_type *t; 2520 int ret; 2521 2522 if (!OPTS_VALID(opts, btf_dump_type_data_opts)) 2523 return libbpf_err(-EINVAL); 2524 2525 t = btf__type_by_id(d->btf, id); 2526 if (!t) 2527 return libbpf_err(-ENOENT); 2528 2529 d->typed_dump = &typed_dump; 2530 d->typed_dump->data_end = data + data_sz; 2531 d->typed_dump->indent_lvl = OPTS_GET(opts, indent_level, 0); 2532 2533 /* default indent string is a tab */ 2534 if (!OPTS_GET(opts, indent_str, NULL)) 2535 d->typed_dump->indent_str[0] = '\t'; 2536 else 2537 libbpf_strlcpy(d->typed_dump->indent_str, opts->indent_str, 2538 sizeof(d->typed_dump->indent_str)); 2539 2540 d->typed_dump->compact = OPTS_GET(opts, compact, false); 2541 d->typed_dump->skip_names = OPTS_GET(opts, skip_names, false); 2542 d->typed_dump->emit_zeroes = OPTS_GET(opts, emit_zeroes, false); 2543 2544 ret = btf_dump_dump_type_data(d, NULL, t, id, data, 0, 0); 2545 2546 d->typed_dump = NULL; 2547 2548 return libbpf_err(ret); 2549 } 2550