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