2550 lines · c
1// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)2 3/*4 * BTF-to-C type converter.5 *6 * Copyright (c) 2019 Facebook7 */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 25static const char PREFIXES[] = "\t\t\t\t\t\t\t\t\t\t\t\t\t";26static const size_t PREFIX_CNT = sizeof(PREFIXES) - 1;27 28static const char *pfx(int lvl)29{30 return lvl >= PREFIX_CNT ? PREFIXES : &PREFIXES[PREFIX_CNT - lvl];31}32 33enum btf_dump_type_order_state {34 NOT_ORDERED,35 ORDERING,36 ORDERED,37};38 39enum btf_dump_type_emit_state {40 NOT_EMITTED,41 EMITTING,42 EMITTED,43};44 45/* per-type auxiliary state */46struct 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 3261 62/*63 * Common internal data for BTF type data dump operations.64 */65struct 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 79struct 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 such112 * name occurrences113 */114 struct hashmap *ident_names;115 /*116 * data for typed display; allocated if needed.117 */118 struct btf_dump_data *typed_dump;119};120 121static size_t str_hash_fn(long key, void *ctx)122{123 return str_hash((void *)key);124}125 126static bool str_equal_fn(long a, long b, void *ctx)127{128 return strcmp((void *)a, (void *)b) == 0;129}130 131static 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 136static 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 145static int btf_dump_mark_referenced(struct btf_dump *d);146static int btf_dump_resize(struct btf_dump *d);147 148struct 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;189err:190 btf_dump__free(d);191 return libbpf_err_ptr(err);192}193 194static 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 223static 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 234void 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 258static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr);259static 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 necessary263 * dependent types, necessary for compilation. If some of the dependent types264 * were already emitted as part of previous btf_dump__dump_type() invocation265 * for another type, they won't be emitted again. This API allows callers to266 * filter out BTF types according to user-defined criterias and emitted only267 * minimal subset of types, necessary to compile everything. Full struct/union268 * definitions will still be emitted, even if the only usage is through269 * 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 */277int 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 to301 * determine top-level anonymous enums that need to be emitted as an302 * independent type declarations.303 * Anonymous enums come in two flavors: either embedded in a struct's field304 * definition, in which case they have to be declared inline as part of field305 * type declaration; or as a top-level anonymous enum, typically used for306 * declaring global constants. It's impossible to distinguish between two307 * without knowing whether given enum type was referenced from other type:308 * top-level anonymous enum won't be referenced by anything, while embedded309 * one will.310 */311static 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 377static 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 satisfy397 * C compilation rules. This is done through topological sorting with an398 * additional complication which comes from C rules. The main idea for C is399 * that if some type is "embedded" into a struct/union, it's size needs to be400 * 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 of413 * struct B definition, as struct B has a pointer to struct A, so the size of414 * 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 error419 * struct B {420 * struct { // anonymous struct421 * struct A y;422 * } *x;423 * };424 *425 * In this case, struct B's field x is a pointer, so it's size is known426 * regardless of the size of (anonymous) struct it points to. But because this427 * struct is anonymous and thus defined inline inside struct B, *and* it428 * embeds struct A, compiler requires full definition of struct A to be known429 * before struct B can be defined. This creates a transitive dependency430 * between struct A and struct B. If struct A was forward-declared before431 * struct B definition and fully defined after struct B definition, that would432 * trigger compilation error.433 *434 * All this means that while we are doing topological sorting on BTF type435 * graph, we need to determine relationships between different types (graph436 * nodes):437 * - weak link (relationship) between X and Y, if Y *CAN* be438 * 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 is442 * BTF_KIND_PTR type in the chain and at least one non-anonymous type443 * Z (excluding X, including Y), then link is weak. Otherwise, it's strong.444 * Weak/strong relationship is determined recursively during DFS traversal and445 * 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 be449 * emitted.450 *451 * To avoid extra work, algorithm marks some of BTF types as ORDERED, when452 * 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 the454 * entire graph path, so depending where from one came to that BTF type, it455 * 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 are457 * marked as ORDERED. We can mark PTR as ORDERED as well, as it semi-forces458 * weak link, unless subsequent referenced STRUCT/UNION/ENUM is anonymous. But459 * in any case, once those are processed, no need to do it again, as the460 * result won't change.461 *462 * Returns:463 * - 1, if type is part of strong link (so there is strong topological464 * ordering requirements);465 * - 0, if type is part of weak link (so can be satisfied through forward466 * declaration);467 * - <0, on error (e.g., unsatisfiable type loop detected).468 */469static 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 BTF473 * 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 always477 * 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 it480 * 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 embedded520 * (so no ptr in a path) or it's anonymous (so has to be521 * 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-level549 * declarations and should be emitted. Same logic can be550 * 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 616static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id,617 const struct btf_type *t);618 619static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id,620 const struct btf_type *t);621static void btf_dump_emit_struct_def(struct btf_dump *d, __u32 id,622 const struct btf_type *t, int lvl);623 624static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id,625 const struct btf_type *t);626static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id,627 const struct btf_type *t, int lvl);628 629static void btf_dump_emit_fwd_def(struct btf_dump *d, __u32 id,630 const struct btf_type *t);631 632static 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 */636struct id_stack {637 const __u32 *ids;638 int cnt;639};640 641static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,642 const char *fname, int lvl);643static void btf_dump_emit_type_chain(struct btf_dump *d,644 struct id_stack *decl_stack,645 const char *fname, int lvl);646 647static const char *btf_dump_type_name(struct btf_dump *d, __u32 id);648static const char *btf_dump_ident_name(struct btf_dump *d, __u32 id);649static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_map,650 const char *orig_name);651 652static 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 compilation657 * errors, when compiling w/ different compiler, then used to compile658 * original code (e.g., GCC to compile kernel, Clang to use generated659 * C header from BTF). As it is built-in, it should be already defined660 * 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 handled671 * by btf_dump_emit_type() itself, but all nitty-gritty details of emitting type672 * declarations/definitions in C syntax are handled by a combo of673 * btf_dump_emit_type_decl()/btf_dump_emit_type_chain() w/ delegation to674 * corresponding btf_dump_emit_*_{def,fwd}() functions.675 *676 * We also keep track of "containing struct/union type ID" to determine when677 * we reference it from inside and thus can avoid emitting unnecessary forward678 * declaration.679 *680 * This algorithm is designed in such a way, that even if some error occurs681 * (either technical, e.g., out of memory, or logical, i.e., malformed BTF682 * that doesn't comply to C rules completely), algorithm will try to proceed683 * and produce as much meaningful output as possible.684 */685static 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 are707 * part of - then no need for fwd declaration708 */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 definition723 * was emitted, but it can be used only for "weak"724 * references through pointer only, not for embedding725 */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 forward774 * declaration; at this stage someone depends on775 * typedef as a forward declaration (refers to it776 * through pointer), so unless we already did it,777 * emit typedef as a forward declaration778 */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/union789 * is anonymous, then in C we'll be emitting all fields and790 * their types (as opposed to just `struct X`), so we need to791 * make sure that all types, referenced from struct/union792 * members have necessary forward-declarations, where793 * applicable794 */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 833static 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 is855 * naturally aligned, we'll detect that it's not packed856 */857 return false;858}859 860static 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 of877 * natural alignment rules to minimize unnecessary explicit878 * padding. First, we find the largest type (among long, int,879 * short, or char) that can be used to force naturally aligned880 * boundary. Once determined, we'll use such type to fill in881 * the remaining padding gap. In some cases we can rely on882 * compiler filling some gaps, but sometimes we need to force883 * alignment to close natural alignment with markers like884 * `long: 0` (this is always the case for bitfields). Note885 * that even if struct itself has, let's say 4-byte alignment886 * (i.e., it only uses up to int-aligned types), using `long:887 * X;` explicit padding doesn't actually change struct's888 * overall alignment requirements, but compiler does take into889 * account that type's (long, in this example) natural890 * alignment requirements when adding implicit padding. We use891 * this fact heavily and don't worry about ruining correct892 * 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 next905 * field is right on alignment offset and its906 * alignment requirement is less strict than <type>'s907 * alignment (so compiler won't naturally align to the908 * 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 chosen923 * padding type (long, int, short, or char), and so the rest is just924 * a straightforward filling of remaining padding gap with full925 * `<type>: sizeof(<type>);` markers, except for the last one, which926 * 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 entire936 * 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 the939 * 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 954static 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 963static 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 1029static const char *missing_base_types[][2] = {1030 /*1031 * GCC emits typedefs to its internal __PolyX_t types when compiling Arm1032 * 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 1040static 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 1055static 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 1061static 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 1086static 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}1117static 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 else1134 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 values1143 * doesn't fit in 32-bit integer, or by adding mode(word)1144 * attribute (but probably only on 64-bit architectures); do1145 * our best here to try to satisfy the contract without adding1146 * unnecessary attributes1147 */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 has1155 * non-zero upper 32-bits (which means that all values1156 * fit in 32-bit integers and won't cause compiler to1157 * bump enum to be 64-bit naturally1158 */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 1175static 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 else1183 btf_dump_printf(d, "struct %s", name);1184}1185 1186static 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_list1193 * pointing to VOID. This generates warnings from btf_dump() and1194 * results in uncompilable header file, so we are fixing it up here1195 * 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 1206static 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 argument1227 * declaration in function prototype) in correct C syntax.1228 *1229 * For most types it's trivial, but there are few quirky type declaration1230 * 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), see1236 * 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 opposite1240 * problem. So we came up with this algorithm in reverse to van der Linden's1241 * parsing algorithm. It goes from structured BTF representation of type1242 * 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 type1250 * graph, but in C syntax, const/volatile/restrict modifiers are written to1251 * the right of pointers, but to the left of other types. There are also other1252 * quirks, like function pointers, arrays of them, functions returning other1253 * 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 on1257 * top of a stack, modifiers are handled differently. Array/function pointers1258 * have also wildly different syntax and how nesting of them are done. See1259 * code for authoritative definition.1260 *1261 * To avoid allocating new stack for each independent chain of BTF types, we1262 * share one bigger stack, with each chain working only on its own local view1263 * of a stack frame. Some care is required to "pop" stack frames after1264 * processing type declaration chain.1265 */1266int 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 1287static 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 decl1304 * chain, restore stack, emit warning, and try to1305 * proceed nevertheless1306 */1307 pr_warn("not enough memory for decl stack:%d", err);1308 d->decl_stack_cnt = stack_start;1309 return;1310 }1311skip_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 }1343done:1344 /*1345 * We might be inside a chain of declarations (e.g., array of function1346 * pointers returning anonymous (so inlined) structs, having another1347 * array field). Each of those needs its own "stack frame" to handle1348 * emitting of declarations. Those stack frames are non-overlapping1349 * portions of shared btf_dump->decl_stack. To make it a bit nicer to1350 * handle this set of nested stacks, we create a view corresponding to1351 * 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_stack1359 * frame before returning. But it works with a read-only view into1360 * decl_stack, so it doesn't actually pop anything from the1361 * perspective of shared btf_dump->decl_stack, per se. We need to1362 * reset decl_stack state to how it was before us to avoid it growing1363 * all the time.1364 */1365 d->decl_stack_cnt = stack_start;1366}1367 1368static 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 1394static 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 1408static 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 1416static 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 pointer1422 * asterisk (*) from previous part of type signature with space, so1423 * that we get `int ***`, instead of `int * * *`. We default to true1424 * 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 call1426 * with just ptr, which should be emitted as (*) or (*<fname>), so we1427 * 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 else1462 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 else1471 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 bug1505 * (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=8354)1506 * which causes it to emit extra const/volatile1507 * modifiers for an array, if array's element type has1508 * const/volatile modifiers. Clang doesn't do that.1509 * In general, it doesn't seem very meaningful to have1510 * a const/volatile modifier for array, so we are1511 * 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 for1543 * __attribute__((noreturn)) function pointers. Clang1544 * doesn't do it. It's a GCC quirk for backwards1545 * compatibility with code written for GCC <2.5. So,1546 * similarly to extra qualifiers for array, just drop1547 * 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 no1560 * args as a func_proto with a single void arg (e.g.,1561 * `int (*f)(void)` vs just `int (*f)()`). We are1562 * going to emit valid empty args (void) syntax for1563 * such case. Similarly and conveniently, valid1564 * 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) */1601static 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 each1607 * member to avoid the redundancy of1608 * .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 done1614 * 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 */1634static 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 1657static 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 1690static 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 1695static 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 1700static 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 1708static 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 1713static const char *btf_dump_data_delim(struct btf_dump *d)1714{1715 return d->typed_dump->depth == 0 ? "" : ",";1716}1717 1718static 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 specifiers1730 * to the format specifier passed in; these do the work of appending1731 * delimiters etc while the caller simply has to specify the type values1732 * 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 1740static 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 1748static 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 are1768 * 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#else1779# error "Unrecognized __BYTE_ORDER__"1780#endif1781 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 1789static 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 1806static 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 */1825static 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 else1839 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 1851static 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 1862static 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 on1879 * 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 not1892 * 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#else1901# error "Unrecognized __BYTE_ORDER__"1902#endif1903 if (msi == 0)1904 btf_dump_type_values(d, "0x%llx", (unsigned long long)lsi);1905 else1906 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 else1914 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 else1920 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 else1926 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 else1946 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 1955union float_data {1956 long double ld;1957 double d;1958 float f;1959};1960 1961static 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 1993static 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 2027static 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 for2051 * char arrays, so if size is 1 and element is2052 * 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 a2060 * newline for depth 0 (since this leaves us with trailing newlines2061 * at the end of typed display), so depth is incremented first.2062 * For similar reasons, we decrement depth before showing the closing2063 * 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 2089static 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 a2100 * newline for depth 0 (since this leaves us with trailing newlines2101 * at the end of typed display), so depth is incremented first.2102 * For similar reasons, we decrement depth before showing the closing2103 * 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 2130union ptr_data {2131 unsigned int p;2132 unsigned long long lp;2133};2134 2135static 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 else2149 btf_dump_type_values(d, "0x%llx", pt.lp);2150 }2151 return 0;2152}2153 2154static 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 2192static 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 2233static 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. */2256static 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 from2270 * btf_dump_struct_data() where it only cares about2271 * negative error value.2272 * Return nr_bytes in success case to make it2273 * 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 to2287 * avoid showing part of a struct, union or array, even if we2288 * do not have enough data to show the full object. By2289 * restricting overflow checking to base types we can ensure2290 * that partial display succeeds, while avoiding overflowing2291 * 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 2315static 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 if2326 * - 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 and2329 * not a char array; we don't want to be in a situation where we2330 * 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 starting2332 * with a '\0', the array-level check_zero() will prevent showing it;2333 * we are concerned with determining zero value at the array member2334 * 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, all2364 * of array is displayed. We make an exception however2365 * for char arrays where the first element is 0; these2366 * are considered zeroed also, even if later elements are2367 * 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/union2388 * 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 display2399 * 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. */2423static 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 skip2439 * 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 else2467 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 } else2496 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 2514int 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 else2537 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