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