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