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	bool emit_strings;
71	__u8 indent_lvl; /* base indent level */
72	char indent_str[BTF_DATA_INDENT_STR_LEN];
73	/* below are used during iteration */
74	int depth;
75	bool is_array_member;
76	bool is_array_terminated;
77	bool is_array_char;
78	};
79
80	struct btf_dump {
81	const struct btf *btf;
82	btf_dump_printf_fn_t printf_fn;
83	void *cb_ctx;
84	int ptr_sz;
85	bool strip_mods;
86	bool skip_anon_defs;
87	int last_id;
88
89	/* per-type auxiliary state */
90	struct btf_dump_type_aux_state *type_states;
91	size_t type_states_cap;
92	/* per-type optional cached unique name, must be freed, if present */
93	const char **cached_names;
94	size_t cached_names_cap;
95
96	/* topo-sorted list of dependent type definitions */
97	__u32 *emit_queue;
98	int emit_queue_cap;
99	int emit_queue_cnt;
100
101	/*
102	* stack of type declarations (e.g., chain of modifiers, arrays,
103	* funcs, etc)
104	*/
105	__u32 *decl_stack;
106	int decl_stack_cap;
107	int decl_stack_cnt;
108
109	/* maps struct/union/enum name to a number of name occurrences */
110	struct hashmap *type_names;
111	/*
112	* maps typedef identifiers and enum value names to a number of such
113	* name occurrences
114	*/
115	struct hashmap *ident_names;
116	/*
117	* data for typed display; allocated if needed.
118	*/
119	struct btf_dump_data *typed_dump;
120	};
121
122	static size_t str_hash_fn(long key, void *ctx)
123	{
124	return str_hash(s: (void *)key);
125	}
126
127	static bool str_equal_fn(long a, long b, void *ctx)
128	{
129	return strcmp((void *)a, (void *)b) == 0;
130	}
131
132	static const char *btf_name_of(const struct btf_dump *d, __u32 name_off)
133	{
134	return btf__name_by_offset(btf: d->btf, offset: name_off);
135	}
136
137	static void btf_dump_printf(const struct btf_dump *d, const char *fmt, ...)
138	{
139	va_list args;
140
141	va_start(args, fmt);
142	d->printf_fn(d->cb_ctx, fmt, args);
143	va_end(args);
144	}
145
146	static int btf_dump_mark_referenced(struct btf_dump *d);
147	static int btf_dump_resize(struct btf_dump *d);
148
149	struct btf_dump *btf_dump__new(const struct btf *btf,
150	btf_dump_printf_fn_t printf_fn,
151	void *ctx,
152	const struct btf_dump_opts *opts)
153	{
154	struct btf_dump *d;
155	int err;
156
157	if (!OPTS_VALID(opts, btf_dump_opts))
158	return libbpf_err_ptr(err: -EINVAL);
159
160	if (!printf_fn)
161	return libbpf_err_ptr(err: -EINVAL);
162
163	d = calloc(1, sizeof(struct btf_dump));
164	if (!d)
165	return libbpf_err_ptr(err: -ENOMEM);
166
167	d->btf = btf;
168	d->printf_fn = printf_fn;
169	d->cb_ctx = ctx;
170	d->ptr_sz = btf__pointer_size(btf) ? : sizeof(void *);
171
172	d->type_names = hashmap__new(hash_fn: str_hash_fn, equal_fn: str_equal_fn, NULL);
173	if (IS_ERR(ptr: d->type_names)) {
174	err = PTR_ERR(ptr: d->type_names);
175	d->type_names = NULL;
176	goto err;
177	}
178	d->ident_names = hashmap__new(hash_fn: str_hash_fn, equal_fn: str_equal_fn, NULL);
179	if (IS_ERR(ptr: d->ident_names)) {
180	err = PTR_ERR(ptr: d->ident_names);
181	d->ident_names = NULL;
182	goto err;
183	}
184
185	err = btf_dump_resize(d);
186	if (err)
187	goto err;
188
189	return d;
190	err:
191	btf_dump__free(d);
192	return libbpf_err_ptr(err);
193	}
194
195	static int btf_dump_resize(struct btf_dump *d)
196	{
197	int err, last_id = btf__type_cnt(btf: d->btf) - 1;
198
199	if (last_id <= d->last_id)
200	return 0;
201
202	if (libbpf_ensure_mem(data: (void **)&d->type_states, cap_cnt: &d->type_states_cap,
203	elem_sz: sizeof(*d->type_states), need_cnt: last_id + 1))
204	return -ENOMEM;
205	if (libbpf_ensure_mem(data: (void **)&d->cached_names, cap_cnt: &d->cached_names_cap,
206	elem_sz: sizeof(*d->cached_names), need_cnt: last_id + 1))
207	return -ENOMEM;
208
209	if (d->last_id == 0) {
210	/* VOID is special */
211	d->type_states[0].order_state = ORDERED;
212	d->type_states[0].emit_state = EMITTED;
213	}
214
215	/* eagerly determine referenced types for anon enums */
216	err = btf_dump_mark_referenced(d);
217	if (err)
218	return err;
219
220	d->last_id = last_id;
221	return 0;
222	}
223
224	static void btf_dump_free_names(struct hashmap *map)
225	{
226	size_t bkt;
227	struct hashmap_entry *cur;
228
229	if (!map)
230	return;
231
232	hashmap__for_each_entry(map, cur, bkt)
233	free((void *)cur->pkey);
234
235	hashmap__free(map);
236	}
237
238	void btf_dump__free(struct btf_dump *d)
239	{
240	int i;
241
242	if (IS_ERR_OR_NULL(ptr: d))
243	return;
244
245	free(d->type_states);
246	if (d->cached_names) {
247	/* any set cached name is owned by us and should be freed */
248	for (i = 0; i <= d->last_id; i++) {
249	if (d->cached_names[i])
250	free((void *)d->cached_names[i]);
251	}
252	}
253	free(d->cached_names);
254	free(d->emit_queue);
255	free(d->decl_stack);
256	btf_dump_free_names(map: d->type_names);
257	btf_dump_free_names(map: d->ident_names);
258
259	free(d);
260	}
261
262	static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr);
263	static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id);
264
265	/*
266	* Dump BTF type in a compilable C syntax, including all the necessary
267	* dependent types, necessary for compilation. If some of the dependent types
268	* were already emitted as part of previous btf_dump__dump_type() invocation
269	* for another type, they won't be emitted again. This API allows callers to
270	* filter out BTF types according to user-defined criterias and emitted only
271	* minimal subset of types, necessary to compile everything. Full struct/union
272	* definitions will still be emitted, even if the only usage is through
273	* pointer and could be satisfied with just a forward declaration.
274	*
275	* Dumping is done in two high-level passes:
276	* 1. Topologically sort type definitions to satisfy C rules of compilation.
277	* 2. Emit type definitions in C syntax.
278	*
279	* Returns 0 on success; <0, otherwise.
280	*/
281	int btf_dump__dump_type(struct btf_dump *d, __u32 id)
282	{
283	int err, i;
284
285	if (id >= btf__type_cnt(btf: d->btf))
286	return libbpf_err(ret: -EINVAL);
287
288	err = btf_dump_resize(d);
289	if (err)
290	return libbpf_err(ret: err);
291
292	d->emit_queue_cnt = 0;
293	err = btf_dump_order_type(d, id, through_ptr: false);
294	if (err < 0)
295	return libbpf_err(ret: err);
296
297	for (i = 0; i < d->emit_queue_cnt; i++)
298	btf_dump_emit_type(d, id: d->emit_queue[i], cont_id: 0 /*top-level*/);
299
300	return 0;
301	}
302
303	/*
304	* Mark all types that are referenced from any other type. This is used to
305	* determine top-level anonymous enums that need to be emitted as an
306	* independent type declarations.
307	* Anonymous enums come in two flavors: either embedded in a struct's field
308	* definition, in which case they have to be declared inline as part of field
309	* type declaration; or as a top-level anonymous enum, typically used for
310	* declaring global constants. It's impossible to distinguish between two
311	* without knowing whether given enum type was referenced from other type:
312	* top-level anonymous enum won't be referenced by anything, while embedded
313	* one will.
314	*/
315	static int btf_dump_mark_referenced(struct btf_dump *d)
316	{
317	int i, j, n = btf__type_cnt(btf: d->btf);
318	const struct btf_type *t;
319	__u16 vlen;
320
321	for (i = d->last_id + 1; i < n; i++) {
322	t = btf__type_by_id(btf: d->btf, id: i);
323	vlen = btf_vlen(t);
324
325	switch (btf_kind(t)) {
326	case BTF_KIND_INT:
327	case BTF_KIND_ENUM:
328	case BTF_KIND_ENUM64:
329	case BTF_KIND_FWD:
330	case BTF_KIND_FLOAT:
331	break;
332
333	case BTF_KIND_VOLATILE:
334	case BTF_KIND_CONST:
335	case BTF_KIND_RESTRICT:
336	case BTF_KIND_PTR:
337	case BTF_KIND_TYPEDEF:
338	case BTF_KIND_FUNC:
339	case BTF_KIND_VAR:
340	case BTF_KIND_DECL_TAG:
341	case BTF_KIND_TYPE_TAG:
342	d->type_states[t->type].referenced = 1;
343	break;
344
345	case BTF_KIND_ARRAY: {
346	const struct btf_array *a = btf_array(t);
347
348	d->type_states[a->index_type].referenced = 1;
349	d->type_states[a->type].referenced = 1;
350	break;
351	}
352	case BTF_KIND_STRUCT:
353	case BTF_KIND_UNION: {
354	const struct btf_member *m = btf_members(t);
355
356	for (j = 0; j < vlen; j++, m++)
357	d->type_states[m->type].referenced = 1;
358	break;
359	}
360	case BTF_KIND_FUNC_PROTO: {
361	const struct btf_param *p = btf_params(t);
362
363	for (j = 0; j < vlen; j++, p++)
364	d->type_states[p->type].referenced = 1;
365	break;
366	}
367	case BTF_KIND_DATASEC: {
368	const struct btf_var_secinfo *v = btf_var_secinfos(t);
369
370	for (j = 0; j < vlen; j++, v++)
371	d->type_states[v->type].referenced = 1;
372	break;
373	}
374	default:
375	return -EINVAL;
376	}
377	}
378	return 0;
379	}
380
381	static int btf_dump_add_emit_queue_id(struct btf_dump *d, __u32 id)
382	{
383	__u32 *new_queue;
384	size_t new_cap;
385
386	if (d->emit_queue_cnt >= d->emit_queue_cap) {
387	new_cap = max(16, d->emit_queue_cap * 3 / 2);
388	new_queue = libbpf_reallocarray(ptr: d->emit_queue, nmemb: new_cap, size: sizeof(new_queue[0]));
389	if (!new_queue)
390	return -ENOMEM;
391	d->emit_queue = new_queue;
392	d->emit_queue_cap = new_cap;
393	}
394
395	d->emit_queue[d->emit_queue_cnt++] = id;
396	return 0;
397	}
398
399	/*
400	* Determine order of emitting dependent types and specified type to satisfy
401	* C compilation rules. This is done through topological sorting with an
402	* additional complication which comes from C rules. The main idea for C is
403	* that if some type is "embedded" into a struct/union, it's size needs to be
404	* known at the time of definition of containing type. E.g., for:
405	*
406	* struct A {};
407	* struct B { struct A x; }
408	*
409	* struct A *HAS* to be defined before struct B, because it's "embedded",
410	* i.e., it is part of struct B layout. But in the following case:
411	*
412	* struct A;
413	* struct B { struct A *x; }
414	* struct A {};
415	*
416	* it's enough to just have a forward declaration of struct A at the time of
417	* struct B definition, as struct B has a pointer to struct A, so the size of
418	* field x is known without knowing struct A size: it's sizeof(void *).
419	*
420	* Unfortunately, there are some trickier cases we need to handle, e.g.:
421	*
422	* struct A {}; // if this was forward-declaration: compilation error
423	* struct B {
424	* struct { // anonymous struct
425	* struct A y;
426	* } *x;
427	* };
428	*
429	* In this case, struct B's field x is a pointer, so it's size is known
430	* regardless of the size of (anonymous) struct it points to. But because this
431	* struct is anonymous and thus defined inline inside struct B, *and* it
432	* embeds struct A, compiler requires full definition of struct A to be known
433	* before struct B can be defined. This creates a transitive dependency
434	* between struct A and struct B. If struct A was forward-declared before
435	* struct B definition and fully defined after struct B definition, that would
436	* trigger compilation error.
437	*
438	* All this means that while we are doing topological sorting on BTF type
439	* graph, we need to determine relationships between different types (graph
440	* nodes):
441	* - weak link (relationship) between X and Y, if Y *CAN* be
442	* forward-declared at the point of X definition;
443	* - strong link, if Y *HAS* to be fully-defined before X can be defined.
444	*
445	* The rule is as follows. Given a chain of BTF types from X to Y, if there is
446	* BTF_KIND_PTR type in the chain and at least one non-anonymous type
447	* Z (excluding X, including Y), then link is weak. Otherwise, it's strong.
448	* Weak/strong relationship is determined recursively during DFS traversal and
449	* is returned as a result from btf_dump_order_type().
450	*
451	* btf_dump_order_type() is trying to avoid unnecessary forward declarations,
452	* but it is not guaranteeing that no extraneous forward declarations will be
453	* emitted.
454	*
455	* To avoid extra work, algorithm marks some of BTF types as ORDERED, when
456	* it's done with them, but not for all (e.g., VOLATILE, CONST, RESTRICT,
457	* ARRAY, FUNC_PROTO), as weak/strong semantics for those depends on the
458	* entire graph path, so depending where from one came to that BTF type, it
459	* might cause weak or strong ordering. For types like STRUCT/UNION/INT/ENUM,
460	* once they are processed, there is no need to do it again, so they are
461	* marked as ORDERED. We can mark PTR as ORDERED as well, as it semi-forces
462	* weak link, unless subsequent referenced STRUCT/UNION/ENUM is anonymous. But
463	* in any case, once those are processed, no need to do it again, as the
464	* result won't change.
465	*
466	* Returns:
467	* - 1, if type is part of strong link (so there is strong topological
468	* ordering requirements);
469	* - 0, if type is part of weak link (so can be satisfied through forward
470	* declaration);
471	* - <0, on error (e.g., unsatisfiable type loop detected).
472	*/
473	static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
474	{
475	/*
476	* Order state is used to detect strong link cycles, but only for BTF
477	* kinds that are or could be an independent definition (i.e.,
478	* stand-alone fwd decl, enum, typedef, struct, union). Ptrs, arrays,
479	* func_protos, modifiers are just means to get to these definitions.
480	* Int/void don't need definitions, they are assumed to be always
481	* properly defined. We also ignore datasec, var, and funcs for now.
482	* So for all non-defining kinds, we never even set ordering state,
483	* for defining kinds we set ORDERING and subsequently ORDERED if it
484	* forms a strong link.
485	*/
486	struct btf_dump_type_aux_state *tstate = &d->type_states[id];
487	const struct btf_type *t;
488	__u16 vlen;
489	int err, i;
490
491	/* return true, letting typedefs know that it's ok to be emitted */
492	if (tstate->order_state == ORDERED)
493	return 1;
494
495	t = btf__type_by_id(btf: d->btf, id);
496
497	if (tstate->order_state == ORDERING) {
498	/* type loop, but resolvable through fwd declaration */
499	if (btf_is_composite(t) && through_ptr && t->name_off != 0)
500	return 0;
501	pr_warn("unsatisfiable type cycle, id:[%u]\n", id);
502	return -ELOOP;
503	}
504
505	switch (btf_kind(t)) {
506	case BTF_KIND_INT:
507	case BTF_KIND_FLOAT:
508	tstate->order_state = ORDERED;
509	return 0;
510
511	case BTF_KIND_PTR:
512	err = btf_dump_order_type(d, id: t->type, through_ptr: true);
513	tstate->order_state = ORDERED;
514	return err;
515
516	case BTF_KIND_ARRAY:
517	return btf_dump_order_type(d, id: btf_array(t)->type, through_ptr: false);
518
519	case BTF_KIND_STRUCT:
520	case BTF_KIND_UNION: {
521	const struct btf_member *m = btf_members(t);
522	/*
523	* struct/union is part of strong link, only if it's embedded
524	* (so no ptr in a path) or it's anonymous (so has to be
525	* defined inline, even if declared through ptr)
526	*/
527	if (through_ptr && t->name_off != 0)
528	return 0;
529
530	tstate->order_state = ORDERING;
531
532	vlen = btf_vlen(t);
533	for (i = 0; i < vlen; i++, m++) {
534	err = btf_dump_order_type(d, id: m->type, through_ptr: false);
535	if (err < 0)
536	return err;
537	}
538
539	if (t->name_off != 0) {
540	err = btf_dump_add_emit_queue_id(d, id);
541	if (err < 0)
542	return err;
543	}
544
545	tstate->order_state = ORDERED;
546	return 1;
547	}
548	case BTF_KIND_ENUM:
549	case BTF_KIND_ENUM64:
550	case BTF_KIND_FWD:
551	/*
552	* non-anonymous or non-referenced enums are top-level
553	* declarations and should be emitted. Same logic can be
554	* applied to FWDs, it won't hurt anyways.
555	*/
556	if (t->name_off != 0 || !tstate->referenced) {
557	err = btf_dump_add_emit_queue_id(d, id);
558	if (err)
559	return err;
560	}
561	tstate->order_state = ORDERED;
562	return 1;
563
564	case BTF_KIND_TYPEDEF: {
565	int is_strong;
566
567	is_strong = btf_dump_order_type(d, id: t->type, through_ptr);
568	if (is_strong < 0)
569	return is_strong;
570
571	/* typedef is similar to struct/union w.r.t. fwd-decls */
572	if (through_ptr && !is_strong)
573	return 0;
574
575	/* typedef is always a named definition */
576	err = btf_dump_add_emit_queue_id(d, id);
577	if (err)
578	return err;
579
580	d->type_states[id].order_state = ORDERED;
581	return 1;
582	}
583	case BTF_KIND_VOLATILE:
584	case BTF_KIND_CONST:
585	case BTF_KIND_RESTRICT:
586	case BTF_KIND_TYPE_TAG:
587	return btf_dump_order_type(d, id: t->type, through_ptr);
588
589	case BTF_KIND_FUNC_PROTO: {
590	const struct btf_param *p = btf_params(t);
591	bool is_strong;
592
593	err = btf_dump_order_type(d, id: t->type, through_ptr);
594	if (err < 0)
595	return err;
596	is_strong = err > 0;
597
598	vlen = btf_vlen(t);
599	for (i = 0; i < vlen; i++, p++) {
600	err = btf_dump_order_type(d, id: p->type, through_ptr);
601	if (err < 0)
602	return err;
603	if (err > 0)
604	is_strong = true;
605	}
606	return is_strong;
607	}
608	case BTF_KIND_FUNC:
609	case BTF_KIND_VAR:
610	case BTF_KIND_DATASEC:
611	case BTF_KIND_DECL_TAG:
612	d->type_states[id].order_state = ORDERED;
613	return 0;
614
615	default:
616	return -EINVAL;
617	}
618	}
619
620	static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id,
621	const struct btf_type *t);
622
623	static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id,
624	const struct btf_type *t);
625	static void btf_dump_emit_struct_def(struct btf_dump *d, __u32 id,
626	const struct btf_type *t, int lvl);
627
628	static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id,
629	const struct btf_type *t);
630	static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id,
631	const struct btf_type *t, int lvl);
632
633	static void btf_dump_emit_fwd_def(struct btf_dump *d, __u32 id,
634	const struct btf_type *t);
635
636	static void btf_dump_emit_typedef_def(struct btf_dump *d, __u32 id,
637	const struct btf_type *t, int lvl);
638
639	/* a local view into a shared stack */
640	struct id_stack {
641	const __u32 *ids;
642	int cnt;
643	};
644
645	static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
646	const char *fname, int lvl);
647	static void btf_dump_emit_type_chain(struct btf_dump *d,
648	struct id_stack *decl_stack,
649	const char *fname, int lvl);
650
651	static const char *btf_dump_type_name(struct btf_dump *d, __u32 id);
652	static const char *btf_dump_ident_name(struct btf_dump *d, __u32 id);
653	static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_map,
654	const char *orig_name);
655
656	static bool btf_dump_is_blacklisted(struct btf_dump *d, __u32 id)
657	{
658	const struct btf_type *t = btf__type_by_id(btf: d->btf, id);
659
660	/* __builtin_va_list is a compiler built-in, which causes compilation
661	* errors, when compiling w/ different compiler, then used to compile
662	* original code (e.g., GCC to compile kernel, Clang to use generated
663	* C header from BTF). As it is built-in, it should be already defined
664	* properly internally in compiler.
665	*/
666	if (t->name_off == 0)
667	return false;
668	return strcmp(btf_name_of(d, name_off: t->name_off), "__builtin_va_list") == 0;
669	}
670
671	/*
672	* Emit C-syntax definitions of types from chains of BTF types.
673	*
674	* High-level handling of determining necessary forward declarations are handled
675	* by btf_dump_emit_type() itself, but all nitty-gritty details of emitting type
676	* declarations/definitions in C syntax are handled by a combo of
677	* btf_dump_emit_type_decl()/btf_dump_emit_type_chain() w/ delegation to
678	* corresponding btf_dump_emit_*_{def,fwd}() functions.
679	*
680	* We also keep track of "containing struct/union type ID" to determine when
681	* we reference it from inside and thus can avoid emitting unnecessary forward
682	* declaration.
683	*
684	* This algorithm is designed in such a way, that even if some error occurs
685	* (either technical, e.g., out of memory, or logical, i.e., malformed BTF
686	* that doesn't comply to C rules completely), algorithm will try to proceed
687	* and produce as much meaningful output as possible.
688	*/
689	static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id)
690	{
691	struct btf_dump_type_aux_state *tstate = &d->type_states[id];
692	bool top_level_def = cont_id == 0;
693	const struct btf_type *t;
694	__u16 kind;
695
696	if (tstate->emit_state == EMITTED)
697	return;
698
699	t = btf__type_by_id(btf: d->btf, id);
700	kind = btf_kind(t);
701
702	if (tstate->emit_state == EMITTING) {
703	if (tstate->fwd_emitted)
704	return;
705
706	switch (kind) {
707	case BTF_KIND_STRUCT:
708	case BTF_KIND_UNION:
709	/*
710	* if we are referencing a struct/union that we are
711	* part of - then no need for fwd declaration
712	*/
713	if (id == cont_id)
714	return;
715	if (t->name_off == 0) {
716	pr_warn("anonymous struct/union loop, id:[%u]\n",
717	id);
718	return;
719	}
720	btf_dump_emit_struct_fwd(d, id, t);
721	btf_dump_printf(d, fmt: ";\n\n");
722	tstate->fwd_emitted = 1;
723	break;
724	case BTF_KIND_TYPEDEF:
725	/*
726	* for typedef fwd_emitted means typedef definition
727	* was emitted, but it can be used only for "weak"
728	* references through pointer only, not for embedding
729	*/
730	if (!btf_dump_is_blacklisted(d, id)) {
731	btf_dump_emit_typedef_def(d, id, t, lvl: 0);
732	btf_dump_printf(d, fmt: ";\n\n");
733	}
734	tstate->fwd_emitted = 1;
735	break;
736	default:
737	break;
738	}
739
740	return;
741	}
742
743	switch (kind) {
744	case BTF_KIND_INT:
745	/* Emit type alias definitions if necessary */
746	btf_dump_emit_missing_aliases(d, id, t);
747
748	tstate->emit_state = EMITTED;
749	break;
750	case BTF_KIND_ENUM:
751	case BTF_KIND_ENUM64:
752	if (top_level_def) {
753	btf_dump_emit_enum_def(d, id, t, lvl: 0);
754	btf_dump_printf(d, fmt: ";\n\n");
755	}
756	tstate->emit_state = EMITTED;
757	break;
758	case BTF_KIND_PTR:
759	case BTF_KIND_VOLATILE:
760	case BTF_KIND_CONST:
761	case BTF_KIND_RESTRICT:
762	case BTF_KIND_TYPE_TAG:
763	btf_dump_emit_type(d, id: t->type, cont_id);
764	break;
765	case BTF_KIND_ARRAY:
766	btf_dump_emit_type(d, id: btf_array(t)->type, cont_id);
767	break;
768	case BTF_KIND_FWD:
769	btf_dump_emit_fwd_def(d, id, t);
770	btf_dump_printf(d, fmt: ";\n\n");
771	tstate->emit_state = EMITTED;
772	break;
773	case BTF_KIND_TYPEDEF:
774	tstate->emit_state = EMITTING;
775	btf_dump_emit_type(d, id: t->type, cont_id: id);
776	/*
777	* typedef can server as both definition and forward
778	* declaration; at this stage someone depends on
779	* typedef as a forward declaration (refers to it
780	* through pointer), so unless we already did it,
781	* emit typedef as a forward declaration
782	*/
783	if (!tstate->fwd_emitted && !btf_dump_is_blacklisted(d, id)) {
784	btf_dump_emit_typedef_def(d, id, t, lvl: 0);
785	btf_dump_printf(d, fmt: ";\n\n");
786	}
787	tstate->emit_state = EMITTED;
788	break;
789	case BTF_KIND_STRUCT:
790	case BTF_KIND_UNION:
791	tstate->emit_state = EMITTING;
792	/* if it's a top-level struct/union definition or struct/union
793	* is anonymous, then in C we'll be emitting all fields and
794	* their types (as opposed to just `struct X`), so we need to
795	* make sure that all types, referenced from struct/union
796	* members have necessary forward-declarations, where
797	* applicable
798	*/
799	if (top_level_def || t->name_off == 0) {
800	const struct btf_member *m = btf_members(t);
801	__u16 vlen = btf_vlen(t);
802	int i, new_cont_id;
803
804	new_cont_id = t->name_off == 0 ? cont_id : id;
805	for (i = 0; i < vlen; i++, m++)
806	btf_dump_emit_type(d, id: m->type, cont_id: new_cont_id);
807	} else if (!tstate->fwd_emitted && id != cont_id) {
808	btf_dump_emit_struct_fwd(d, id, t);
809	btf_dump_printf(d, fmt: ";\n\n");
810	tstate->fwd_emitted = 1;
811	}
812
813	if (top_level_def) {
814	btf_dump_emit_struct_def(d, id, t, lvl: 0);
815	btf_dump_printf(d, fmt: ";\n\n");
816	tstate->emit_state = EMITTED;
817	} else {
818	tstate->emit_state = NOT_EMITTED;
819	}
820	break;
821	case BTF_KIND_FUNC_PROTO: {
822	const struct btf_param *p = btf_params(t);
823	__u16 n = btf_vlen(t);
824	int i;
825
826	btf_dump_emit_type(d, id: t->type, cont_id);
827	for (i = 0; i < n; i++, p++)
828	btf_dump_emit_type(d, id: p->type, cont_id);
829
830	break;
831	}
832	default:
833	break;
834	}
835	}
836
837	static bool btf_is_struct_packed(const struct btf *btf, __u32 id,
838	const struct btf_type *t)
839	{
840	const struct btf_member *m;
841	int max_align = 1, align, i, bit_sz;
842	__u16 vlen;
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, id: 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	max_align = max(align, max_align);
853	}
854	/* size of a non-packed struct has to be a multiple of its alignment */
855	if (t->size % max_align != 0)
856	return true;
857	/*
858	* if original struct was marked as packed, but its layout is
859	* naturally aligned, we'll detect that it's not packed
860	*/
861	return false;
862	}
863
864	static void btf_dump_emit_bit_padding(const struct btf_dump *d,
865	int cur_off, int next_off, int next_align,
866	bool in_bitfield, int lvl)
867	{
868	const struct {
869	const char *name;
870	int bits;
871	} pads[] = {
872	{"long", d->ptr_sz * 8}, {"int", 32}, {"short", 16}, {"char", 8}
873	};
874	int new_off = 0, pad_bits = 0, bits, i;
875	const char *pad_type = NULL;
876
877	if (cur_off >= next_off)
878	return; /* no gap */
879
880	/* For filling out padding we want to take advantage of
881	* natural alignment rules to minimize unnecessary explicit
882	* padding. First, we find the largest type (among long, int,
883	* short, or char) that can be used to force naturally aligned
884	* boundary. Once determined, we'll use such type to fill in
885	* the remaining padding gap. In some cases we can rely on
886	* compiler filling some gaps, but sometimes we need to force
887	* alignment to close natural alignment with markers like
888	* `long: 0` (this is always the case for bitfields). Note
889	* that even if struct itself has, let's say 4-byte alignment
890	* (i.e., it only uses up to int-aligned types), using `long:
891	* X;` explicit padding doesn't actually change struct's
892	* overall alignment requirements, but compiler does take into
893	* account that type's (long, in this example) natural
894	* alignment requirements when adding implicit padding. We use
895	* this fact heavily and don't worry about ruining correct
896	* struct alignment requirement.
897	*/
898	for (i = 0; i < ARRAY_SIZE(pads); i++) {
899	pad_bits = pads[i].bits;
900	pad_type = pads[i].name;
901
902	new_off = roundup(cur_off, pad_bits);
903	if (new_off <= next_off)
904	break;
905	}
906
907	if (new_off > cur_off && new_off <= next_off) {
908	/* We need explicit `<type>: 0` aligning mark if next
909	* field is right on alignment offset and its
910	* alignment requirement is less strict than <type>'s
911	* alignment (so compiler won't naturally align to the
912	* offset we expect), or if subsequent `<type>: X`,
913	* will actually completely fit in the remaining hole,
914	* making compiler basically ignore `<type>: X`
915	* completely.
916	*/
917	if (in_bitfield ||
918	(new_off == next_off && roundup(cur_off, next_align * 8) != new_off) ||
919	(new_off != next_off && next_off - new_off <= new_off - cur_off))
920	/* but for bitfields we'll emit explicit bit count */
921	btf_dump_printf(d, fmt: "\n%s%s: %d;", pfx(lvl), pad_type,
922	in_bitfield ? new_off - cur_off : 0);
923	cur_off = new_off;
924	}
925
926	/* Now we know we start at naturally aligned offset for a chosen
927	* padding type (long, int, short, or char), and so the rest is just
928	* a straightforward filling of remaining padding gap with full
929	* `<type>: sizeof(<type>);` markers, except for the last one, which
930	* might need smaller than sizeof(<type>) padding.
931	*/
932	while (cur_off != next_off) {
933	bits = min(next_off - cur_off, pad_bits);
934	if (bits == pad_bits) {
935	btf_dump_printf(d, fmt: "\n%s%s: %d;", pfx(lvl), pad_type, pad_bits);
936	cur_off += bits;
937	continue;
938	}
939	/* For the remainder padding that doesn't cover entire
940	* pad_type bit length, we pick the smallest necessary type.
941	* This is pure aesthetics, we could have just used `long`,
942	* but having smallest necessary one communicates better the
943	* scale of the padding gap.
944	*/
945	for (i = ARRAY_SIZE(pads) - 1; i >= 0; i--) {
946	pad_type = pads[i].name;
947	pad_bits = pads[i].bits;
948	if (pad_bits < bits)
949	continue;
950
951	btf_dump_printf(d, fmt: "\n%s%s: %d;", pfx(lvl), pad_type, bits);
952	cur_off += bits;
953	break;
954	}
955	}
956	}
957
958	static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id,
959	const struct btf_type *t)
960	{
961	btf_dump_printf(d, fmt: "%s%s%s",
962	btf_is_struct(t) ? "struct" : "union",
963	t->name_off ? " " : "",
964	btf_dump_type_name(d, id));
965	}
966
967	static void btf_dump_emit_struct_def(struct btf_dump *d,
968	__u32 id,
969	const struct btf_type *t,
970	int lvl)
971	{
972	const struct btf_member *m = btf_members(t);
973	bool is_struct = btf_is_struct(t);
974	bool packed, prev_bitfield = false;
975	int align, i, off = 0;
976	__u16 vlen = btf_vlen(t);
977
978	align = btf__align_of(btf: d->btf, id);
979	packed = is_struct ? btf_is_struct_packed(btf: d->btf, id, t) : 0;
980
981	btf_dump_printf(d, fmt: "%s%s%s {",
982	is_struct ? "struct" : "union",
983	t->name_off ? " " : "",
984	btf_dump_type_name(d, id));
985
986	for (i = 0; i < vlen; i++, m++) {
987	const char *fname;
988	int m_off, m_sz, m_align;
989	bool in_bitfield;
990
991	fname = btf_name_of(d, name_off: m->name_off);
992	m_sz = btf_member_bitfield_size(t, i);
993	m_off = btf_member_bit_offset(t, i);
994	m_align = packed ? 1 : btf__align_of(btf: d->btf, id: m->type);
995
996	in_bitfield = prev_bitfield && m_sz != 0;
997
998	btf_dump_emit_bit_padding(d, cur_off: off, next_off: m_off, next_align: m_align, in_bitfield, lvl: lvl + 1);
999	btf_dump_printf(d, fmt: "\n%s", pfx(lvl: lvl + 1));
1000	btf_dump_emit_type_decl(d, id: m->type, fname, lvl: lvl + 1);
1001
1002	if (m_sz) {
1003	btf_dump_printf(d, fmt: ": %d", m_sz);
1004	off = m_off + m_sz;
1005	prev_bitfield = true;
1006	} else {
1007	m_sz = max((__s64)0, btf__resolve_size(d->btf, m->type));
1008	off = m_off + m_sz * 8;
1009	prev_bitfield = false;
1010	}
1011
1012	btf_dump_printf(d, fmt: ";");
1013	}
1014
1015	/* pad at the end, if necessary */
1016	if (is_struct)
1017	btf_dump_emit_bit_padding(d, cur_off: off, next_off: t->size * 8, next_align: align, in_bitfield: false, lvl: lvl + 1);
1018
1019	/*
1020	* Keep `struct empty {}` on a single line,
1021	* only print newline when there are regular or padding fields.
1022	*/
1023	if (vlen || t->size) {
1024	btf_dump_printf(d, fmt: "\n");
1025	btf_dump_printf(d, fmt: "%s}", pfx(lvl));
1026	} else {
1027	btf_dump_printf(d, fmt: "}");
1028	}
1029	if (packed)
1030	btf_dump_printf(d, fmt: " __attribute__((packed))");
1031	}
1032
1033	static const char *missing_base_types[][2] = {
1034	/*
1035	* GCC emits typedefs to its internal __PolyX_t types when compiling Arm
1036	* SIMD intrinsics. Alias them to standard base types.
1037	*/
1038	{ "__Poly8_t", "unsigned char" },
1039	{ "__Poly16_t", "unsigned short" },
1040	{ "__Poly64_t", "unsigned long long" },
1041	{ "__Poly128_t", "unsigned __int128" },
1042	};
1043
1044	static void btf_dump_emit_missing_aliases(struct btf_dump *d, __u32 id,
1045	const struct btf_type *t)
1046	{
1047	const char *name = btf_dump_type_name(d, id);
1048	int i;
1049
1050	for (i = 0; i < ARRAY_SIZE(missing_base_types); i++) {
1051	if (strcmp(name, missing_base_types[i][0]) == 0) {
1052	btf_dump_printf(d, fmt: "typedef %s %s;\n\n",
1053	missing_base_types[i][1], name);
1054	break;
1055	}
1056	}
1057	}
1058
1059	static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id,
1060	const struct btf_type *t)
1061	{
1062	btf_dump_printf(d, fmt: "enum %s", btf_dump_type_name(d, id));
1063	}
1064
1065	static void btf_dump_emit_enum32_val(struct btf_dump *d,
1066	const struct btf_type *t,
1067	int lvl, __u16 vlen)
1068	{
1069	const struct btf_enum *v = btf_enum(t);
1070	bool is_signed = btf_kflag(t);
1071	const char *fmt_str;
1072	const char *name;
1073	size_t dup_cnt;
1074	int i;
1075
1076	for (i = 0; i < vlen; i++, v++) {
1077	name = btf_name_of(d, name_off: v->name_off);
1078	/* enumerators share namespace with typedef idents */
1079	dup_cnt = btf_dump_name_dups(d, name_map: d->ident_names, orig_name: name);
1080	if (dup_cnt > 1) {
1081	fmt_str = is_signed ? "\n%s%s___%zd = %d," : "\n%s%s___%zd = %u,";
1082	btf_dump_printf(d, fmt: fmt_str, pfx(lvl: lvl + 1), name, dup_cnt, v->val);
1083	} else {
1084	fmt_str = is_signed ? "\n%s%s = %d," : "\n%s%s = %u,";
1085	btf_dump_printf(d, fmt: fmt_str, pfx(lvl: lvl + 1), name, v->val);
1086	}
1087	}
1088	}
1089
1090	static void btf_dump_emit_enum64_val(struct btf_dump *d,
1091	const struct btf_type *t,
1092	int lvl, __u16 vlen)
1093	{
1094	const struct btf_enum64 *v = btf_enum64(t);
1095	bool is_signed = btf_kflag(t);
1096	const char *fmt_str;
1097	const char *name;
1098	size_t dup_cnt;
1099	__u64 val;
1100	int i;
1101
1102	for (i = 0; i < vlen; i++, v++) {
1103	name = btf_name_of(d, name_off: v->name_off);
1104	dup_cnt = btf_dump_name_dups(d, name_map: d->ident_names, orig_name: name);
1105	val = btf_enum64_value(v);
1106	if (dup_cnt > 1) {
1107	fmt_str = is_signed ? "\n%s%s___%zd = %lldLL,"
1108	: "\n%s%s___%zd = %lluULL,";
1109	btf_dump_printf(d, fmt: fmt_str,
1110	pfx(lvl: lvl + 1), name, dup_cnt,
1111	(unsigned long long)val);
1112	} else {
1113	fmt_str = is_signed ? "\n%s%s = %lldLL,"
1114	: "\n%s%s = %lluULL,";
1115	btf_dump_printf(d, fmt: fmt_str,
1116	pfx(lvl: lvl + 1), name,
1117	(unsigned long long)val);
1118	}
1119	}
1120	}
1121	static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id,
1122	const struct btf_type *t,
1123	int lvl)
1124	{
1125	__u16 vlen = btf_vlen(t);
1126
1127	btf_dump_printf(d, fmt: "enum%s%s",
1128	t->name_off ? " " : "",
1129	btf_dump_type_name(d, id));
1130
1131	if (!vlen)
1132	return;
1133
1134	btf_dump_printf(d, fmt: " {");
1135	if (btf_is_enum(t))
1136	btf_dump_emit_enum32_val(d, t, lvl, vlen);
1137	else
1138	btf_dump_emit_enum64_val(d, t, lvl, vlen);
1139	btf_dump_printf(d, fmt: "\n%s}", pfx(lvl));
1140
1141	/* special case enums with special sizes */
1142	if (t->size == 1) {
1143	/* one-byte enums can be forced with mode(byte) attribute */
1144	btf_dump_printf(d, fmt: " __attribute__((mode(byte)))");
1145	} else if (t->size == 8 && d->ptr_sz == 8) {
1146	/* enum can be 8-byte sized if one of the enumerator values
1147	* doesn't fit in 32-bit integer, or by adding mode(word)
1148	* attribute (but probably only on 64-bit architectures); do
1149	* our best here to try to satisfy the contract without adding
1150	* unnecessary attributes
1151	*/
1152	bool needs_word_mode;
1153
1154	if (btf_is_enum(t)) {
1155	/* enum can't represent 64-bit values, so we need word mode */
1156	needs_word_mode = true;
1157	} else {
1158	/* enum64 needs mode(word) if none of its values has
1159	* non-zero upper 32-bits (which means that all values
1160	* fit in 32-bit integers and won't cause compiler to
1161	* bump enum to be 64-bit naturally
1162	*/
1163	int i;
1164
1165	needs_word_mode = true;
1166	for (i = 0; i < vlen; i++) {
1167	if (btf_enum64(t)[i].val_hi32 != 0) {
1168	needs_word_mode = false;
1169	break;
1170	}
1171	}
1172	}
1173	if (needs_word_mode)
1174	btf_dump_printf(d, fmt: " __attribute__((mode(word)))");
1175	}
1176
1177	}
1178
1179	static void btf_dump_emit_fwd_def(struct btf_dump *d, __u32 id,
1180	const struct btf_type *t)
1181	{
1182	const char *name = btf_dump_type_name(d, id);
1183
1184	if (btf_kflag(t))
1185	btf_dump_printf(d, fmt: "union %s", name);
1186	else
1187	btf_dump_printf(d, fmt: "struct %s", name);
1188	}
1189
1190	static void btf_dump_emit_typedef_def(struct btf_dump *d, __u32 id,
1191	const struct btf_type *t, int lvl)
1192	{
1193	const char *name = btf_dump_ident_name(d, id);
1194
1195	/*
1196	* Old GCC versions are emitting invalid typedef for __gnuc_va_list
1197	* pointing to VOID. This generates warnings from btf_dump() and
1198	* results in uncompilable header file, so we are fixing it up here
1199	* with valid typedef into __builtin_va_list.
1200	*/
1201	if (t->type == 0 && strcmp(name, "__gnuc_va_list") == 0) {
1202	btf_dump_printf(d, fmt: "typedef __builtin_va_list __gnuc_va_list");
1203	return;
1204	}
1205
1206	btf_dump_printf(d, fmt: "typedef ");
1207	btf_dump_emit_type_decl(d, id: t->type, fname: name, lvl);
1208	}
1209
1210	static int btf_dump_push_decl_stack_id(struct btf_dump *d, __u32 id)
1211	{
1212	__u32 *new_stack;
1213	size_t new_cap;
1214
1215	if (d->decl_stack_cnt >= d->decl_stack_cap) {
1216	new_cap = max(16, d->decl_stack_cap * 3 / 2);
1217	new_stack = libbpf_reallocarray(ptr: d->decl_stack, nmemb: new_cap, size: sizeof(new_stack[0]));
1218	if (!new_stack)
1219	return -ENOMEM;
1220	d->decl_stack = new_stack;
1221	d->decl_stack_cap = new_cap;
1222	}
1223
1224	d->decl_stack[d->decl_stack_cnt++] = id;
1225
1226	return 0;
1227	}
1228
1229	/*
1230	* Emit type declaration (e.g., field type declaration in a struct or argument
1231	* declaration in function prototype) in correct C syntax.
1232	*
1233	* For most types it's trivial, but there are few quirky type declaration
1234	* cases worth mentioning:
1235	* - function prototypes (especially nesting of function prototypes);
1236	* - arrays;
1237	* - const/volatile/restrict for pointers vs other types.
1238	*
1239	* For a good discussion of *PARSING* C syntax (as a human), see
1240	* Peter van der Linden's "Expert C Programming: Deep C Secrets",
1241	* Ch.3 "Unscrambling Declarations in C".
1242	*
1243	* It won't help with BTF to C conversion much, though, as it's an opposite
1244	* problem. So we came up with this algorithm in reverse to van der Linden's
1245	* parsing algorithm. It goes from structured BTF representation of type
1246	* declaration to a valid compilable C syntax.
1247	*
1248	* For instance, consider this C typedef:
1249	* typedef const int * const * arr[10] arr_t;
1250	* It will be represented in BTF with this chain of BTF types:
1251	* [typedef] -> [array] -> [ptr] -> [const] -> [ptr] -> [const] -> [int]
1252	*
1253	* Notice how [const] modifier always goes before type it modifies in BTF type
1254	* graph, but in C syntax, const/volatile/restrict modifiers are written to
1255	* the right of pointers, but to the left of other types. There are also other
1256	* quirks, like function pointers, arrays of them, functions returning other
1257	* functions, etc.
1258	*
1259	* We handle that by pushing all the types to a stack, until we hit "terminal"
1260	* type (int/enum/struct/union/fwd). Then depending on the kind of a type on
1261	* top of a stack, modifiers are handled differently. Array/function pointers
1262	* have also wildly different syntax and how nesting of them are done. See
1263	* code for authoritative definition.
1264	*
1265	* To avoid allocating new stack for each independent chain of BTF types, we
1266	* share one bigger stack, with each chain working only on its own local view
1267	* of a stack frame. Some care is required to "pop" stack frames after
1268	* processing type declaration chain.
1269	*/
1270	int btf_dump__emit_type_decl(struct btf_dump *d, __u32 id,
1271	const struct btf_dump_emit_type_decl_opts *opts)
1272	{
1273	const char *fname;
1274	int lvl, err;
1275
1276	if (!OPTS_VALID(opts, btf_dump_emit_type_decl_opts))
1277	return libbpf_err(ret: -EINVAL);
1278
1279	err = btf_dump_resize(d);
1280	if (err)
1281	return libbpf_err(ret: err);
1282
1283	fname = OPTS_GET(opts, field_name, "");
1284	lvl = OPTS_GET(opts, indent_level, 0);
1285	d->strip_mods = OPTS_GET(opts, strip_mods, false);
1286	btf_dump_emit_type_decl(d, id, fname, lvl);
1287	d->strip_mods = false;
1288	return 0;
1289	}
1290
1291	static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
1292	const char *fname, int lvl)
1293	{
1294	struct id_stack decl_stack;
1295	const struct btf_type *t;
1296	int err, stack_start;
1297
1298	stack_start = d->decl_stack_cnt;
1299	for (;;) {
1300	t = btf__type_by_id(btf: d->btf, id);
1301	if (d->strip_mods && btf_is_mod(t))
1302	goto skip_mod;
1303
1304	err = btf_dump_push_decl_stack_id(d, id);
1305	if (err < 0) {
1306	/*
1307	* if we don't have enough memory for entire type decl
1308	* chain, restore stack, emit warning, and try to
1309	* proceed nevertheless
1310	*/
1311	pr_warn("not enough memory for decl stack: %s\n", errstr(err));
1312	d->decl_stack_cnt = stack_start;
1313	return;
1314	}
1315	skip_mod:
1316	/* VOID */
1317	if (id == 0)
1318	break;
1319
1320	switch (btf_kind(t)) {
1321	case BTF_KIND_PTR:
1322	case BTF_KIND_VOLATILE:
1323	case BTF_KIND_CONST:
1324	case BTF_KIND_RESTRICT:
1325	case BTF_KIND_FUNC_PROTO:
1326	case BTF_KIND_TYPE_TAG:
1327	id = t->type;
1328	break;
1329	case BTF_KIND_ARRAY:
1330	id = btf_array(t)->type;
1331	break;
1332	case BTF_KIND_INT:
1333	case BTF_KIND_ENUM:
1334	case BTF_KIND_ENUM64:
1335	case BTF_KIND_FWD:
1336	case BTF_KIND_STRUCT:
1337	case BTF_KIND_UNION:
1338	case BTF_KIND_TYPEDEF:
1339	case BTF_KIND_FLOAT:
1340	goto done;
1341	default:
1342	pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
1343	btf_kind(t), id);
1344	goto done;
1345	}
1346	}
1347	done:
1348	/*
1349	* We might be inside a chain of declarations (e.g., array of function
1350	* pointers returning anonymous (so inlined) structs, having another
1351	* array field). Each of those needs its own "stack frame" to handle
1352	* emitting of declarations. Those stack frames are non-overlapping
1353	* portions of shared btf_dump->decl_stack. To make it a bit nicer to
1354	* handle this set of nested stacks, we create a view corresponding to
1355	* our own "stack frame" and work with it as an independent stack.
1356	* We'll need to clean up after emit_type_chain() returns, though.
1357	*/
1358	decl_stack.ids = d->decl_stack + stack_start;
1359	decl_stack.cnt = d->decl_stack_cnt - stack_start;
1360	btf_dump_emit_type_chain(d, decl_stack: &decl_stack, fname, lvl);
1361	/*
1362	* emit_type_chain() guarantees that it will pop its entire decl_stack
1363	* frame before returning. But it works with a read-only view into
1364	* decl_stack, so it doesn't actually pop anything from the
1365	* perspective of shared btf_dump->decl_stack, per se. We need to
1366	* reset decl_stack state to how it was before us to avoid it growing
1367	* all the time.
1368	*/
1369	d->decl_stack_cnt = stack_start;
1370	}
1371
1372	static void btf_dump_emit_mods(struct btf_dump *d, struct id_stack *decl_stack)
1373	{
1374	const struct btf_type *t;
1375	__u32 id;
1376
1377	while (decl_stack->cnt) {
1378	id = decl_stack->ids[decl_stack->cnt - 1];
1379	t = btf__type_by_id(btf: d->btf, id);
1380
1381	switch (btf_kind(t)) {
1382	case BTF_KIND_VOLATILE:
1383	btf_dump_printf(d, fmt: "volatile ");
1384	break;
1385	case BTF_KIND_CONST:
1386	btf_dump_printf(d, fmt: "const ");
1387	break;
1388	case BTF_KIND_RESTRICT:
1389	btf_dump_printf(d, fmt: "restrict ");
1390	break;
1391	default:
1392	return;
1393	}
1394	decl_stack->cnt--;
1395	}
1396	}
1397
1398	static void btf_dump_drop_mods(struct btf_dump *d, struct id_stack *decl_stack)
1399	{
1400	const struct btf_type *t;
1401	__u32 id;
1402
1403	while (decl_stack->cnt) {
1404	id = decl_stack->ids[decl_stack->cnt - 1];
1405	t = btf__type_by_id(btf: d->btf, id);
1406	if (!btf_is_mod(t))
1407	return;
1408	decl_stack->cnt--;
1409	}
1410	}
1411
1412	static void btf_dump_emit_name(const struct btf_dump *d,
1413	const char *name, bool last_was_ptr)
1414	{
1415	bool separate = name[0] && !last_was_ptr;
1416
1417	btf_dump_printf(d, fmt: "%s%s", separate ? " " : "", name);
1418	}
1419
1420	static void btf_dump_emit_type_chain(struct btf_dump *d,
1421	struct id_stack *decls,
1422	const char *fname, int lvl)
1423	{
1424	/*
1425	* last_was_ptr is used to determine if we need to separate pointer
1426	* asterisk (*) from previous part of type signature with space, so
1427	* that we get `int ***`, instead of `int * * *`. We default to true
1428	* for cases where we have single pointer in a chain. E.g., in ptr ->
1429	* func_proto case. func_proto will start a new emit_type_chain call
1430	* with just ptr, which should be emitted as (*) or (*<fname>), so we
1431	* don't want to prepend space for that last pointer.
1432	*/
1433	bool last_was_ptr = true;
1434	const struct btf_type *t;
1435	const char *name;
1436	__u16 kind;
1437	__u32 id;
1438
1439	while (decls->cnt) {
1440	id = decls->ids[--decls->cnt];
1441	if (id == 0) {
1442	/* VOID is a special snowflake */
1443	btf_dump_emit_mods(d, decl_stack: decls);
1444	btf_dump_printf(d, fmt: "void");
1445	last_was_ptr = false;
1446	continue;
1447	}
1448
1449	t = btf__type_by_id(btf: d->btf, id);
1450	kind = btf_kind(t);
1451
1452	switch (kind) {
1453	case BTF_KIND_INT:
1454	case BTF_KIND_FLOAT:
1455	btf_dump_emit_mods(d, decl_stack: decls);
1456	name = btf_name_of(d, name_off: t->name_off);
1457	btf_dump_printf(d, fmt: "%s", name);
1458	break;
1459	case BTF_KIND_STRUCT:
1460	case BTF_KIND_UNION:
1461	btf_dump_emit_mods(d, decl_stack: decls);
1462	/* inline anonymous struct/union */
1463	if (t->name_off == 0 && !d->skip_anon_defs)
1464	btf_dump_emit_struct_def(d, id, t, lvl);
1465	else
1466	btf_dump_emit_struct_fwd(d, id, t);
1467	break;
1468	case BTF_KIND_ENUM:
1469	case BTF_KIND_ENUM64:
1470	btf_dump_emit_mods(d, decl_stack: decls);
1471	/* inline anonymous enum */
1472	if (t->name_off == 0 && !d->skip_anon_defs)
1473	btf_dump_emit_enum_def(d, id, t, lvl);
1474	else
1475	btf_dump_emit_enum_fwd(d, id, t);
1476	break;
1477	case BTF_KIND_FWD:
1478	btf_dump_emit_mods(d, decl_stack: decls);
1479	btf_dump_emit_fwd_def(d, id, t);
1480	break;
1481	case BTF_KIND_TYPEDEF:
1482	btf_dump_emit_mods(d, decl_stack: decls);
1483	btf_dump_printf(d, fmt: "%s", btf_dump_ident_name(d, id));
1484	break;
1485	case BTF_KIND_PTR:
1486	btf_dump_printf(d, fmt: "%s", last_was_ptr ? "*" : " *");
1487	break;
1488	case BTF_KIND_VOLATILE:
1489	btf_dump_printf(d, fmt: " volatile");
1490	break;
1491	case BTF_KIND_CONST:
1492	btf_dump_printf(d, fmt: " const");
1493	break;
1494	case BTF_KIND_RESTRICT:
1495	btf_dump_printf(d, fmt: " restrict");
1496	break;
1497	case BTF_KIND_TYPE_TAG:
1498	btf_dump_emit_mods(d, decl_stack: decls);
1499	name = btf_name_of(d, name_off: t->name_off);
1500	if (btf_kflag(t))
1501	btf_dump_printf(d, fmt: " __attribute__((%s))", name);
1502	else
1503	btf_dump_printf(d, fmt: " __attribute__((btf_type_tag(\"%s\")))", name);
1504	break;
1505	case BTF_KIND_ARRAY: {
1506	const struct btf_array *a = btf_array(t);
1507	const struct btf_type *next_t;
1508	__u32 next_id;
1509	bool multidim;
1510	/*
1511	* GCC has a bug
1512	* (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=8354)
1513	* which causes it to emit extra const/volatile
1514	* modifiers for an array, if array's element type has
1515	* const/volatile modifiers. Clang doesn't do that.
1516	* In general, it doesn't seem very meaningful to have
1517	* a const/volatile modifier for array, so we are
1518	* going to silently skip them here.
1519	*/
1520	btf_dump_drop_mods(d, decl_stack: decls);
1521
1522	if (decls->cnt == 0) {
1523	btf_dump_emit_name(d, name: fname, last_was_ptr);
1524	btf_dump_printf(d, fmt: "[%u]", a->nelems);
1525	return;
1526	}
1527
1528	next_id = decls->ids[decls->cnt - 1];
1529	next_t = btf__type_by_id(btf: d->btf, id: next_id);
1530	multidim = btf_is_array(next_t);
1531	/* we need space if we have named non-pointer */
1532	if (fname[0] && !last_was_ptr)
1533	btf_dump_printf(d, fmt: " ");
1534	/* no parentheses for multi-dimensional array */
1535	if (!multidim)
1536	btf_dump_printf(d, fmt: "(");
1537	btf_dump_emit_type_chain(d, decls, fname, lvl);
1538	if (!multidim)
1539	btf_dump_printf(d, fmt: ")");
1540	btf_dump_printf(d, fmt: "[%u]", a->nelems);
1541	return;
1542	}
1543	case BTF_KIND_FUNC_PROTO: {
1544	const struct btf_param *p = btf_params(t);
1545	__u16 vlen = btf_vlen(t);
1546	int i;
1547
1548	/*
1549	* GCC emits extra volatile qualifier for
1550	* __attribute__((noreturn)) function pointers. Clang
1551	* doesn't do it. It's a GCC quirk for backwards
1552	* compatibility with code written for GCC <2.5. So,
1553	* similarly to extra qualifiers for array, just drop
1554	* them, instead of handling them.
1555	*/
1556	btf_dump_drop_mods(d, decl_stack: decls);
1557	if (decls->cnt) {
1558	btf_dump_printf(d, fmt: " (");
1559	btf_dump_emit_type_chain(d, decls, fname, lvl);
1560	btf_dump_printf(d, fmt: ")");
1561	} else {
1562	btf_dump_emit_name(d, name: fname, last_was_ptr);
1563	}
1564	btf_dump_printf(d, fmt: "(");
1565	/*
1566	* Clang for BPF target generates func_proto with no
1567	* args as a func_proto with a single void arg (e.g.,
1568	* `int (*f)(void)` vs just `int (*f)()`). We are
1569	* going to emit valid empty args (void) syntax for
1570	* such case. Similarly and conveniently, valid
1571	* no args case can be special-cased here as well.
1572	*/
1573	if (vlen == 0 || (vlen == 1 && p->type == 0)) {
1574	btf_dump_printf(d, fmt: "void)");
1575	return;
1576	}
1577
1578	for (i = 0; i < vlen; i++, p++) {
1579	if (i > 0)
1580	btf_dump_printf(d, fmt: ", ");
1581
1582	/* last arg of type void is vararg */
1583	if (i == vlen - 1 && p->type == 0) {
1584	btf_dump_printf(d, fmt: "...");
1585	break;
1586	}
1587
1588	name = btf_name_of(d, name_off: p->name_off);
1589	btf_dump_emit_type_decl(d, id: p->type, fname: name, lvl);
1590	}
1591
1592	btf_dump_printf(d, fmt: ")");
1593	return;
1594	}
1595	default:
1596	pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
1597	kind, id);
1598	return;
1599	}
1600
1601	last_was_ptr = kind == BTF_KIND_PTR;
1602	}
1603
1604	btf_dump_emit_name(d, name: fname, last_was_ptr);
1605	}
1606
1607	/* show type name as (type_name) */
1608	static void btf_dump_emit_type_cast(struct btf_dump *d, __u32 id,
1609	bool top_level)
1610	{
1611	const struct btf_type *t;
1612
1613	/* for array members, we don't bother emitting type name for each
1614	* member to avoid the redundancy of
1615	* .name = (char[4])[(char)'f',(char)'o',(char)'o',]
1616	*/
1617	if (d->typed_dump->is_array_member)
1618	return;
1619
1620	/* avoid type name specification for variable/section; it will be done
1621	* for the associated variable value(s).
1622	*/
1623	t = btf__type_by_id(btf: d->btf, id);
1624	if (btf_is_var(t) || btf_is_datasec(t))
1625	return;
1626
1627	if (top_level)
1628	btf_dump_printf(d, fmt: "(");
1629
1630	d->skip_anon_defs = true;
1631	d->strip_mods = true;
1632	btf_dump_emit_type_decl(d, id, fname: "", lvl: 0);
1633	d->strip_mods = false;
1634	d->skip_anon_defs = false;
1635
1636	if (top_level)
1637	btf_dump_printf(d, fmt: ")");
1638	}
1639
1640	/* return number of duplicates (occurrences) of a given name */
1641	static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_map,
1642	const char *orig_name)
1643	{
1644	char *old_name, *new_name;
1645	size_t dup_cnt = 0;
1646	int err;
1647
1648	new_name = strdup(orig_name);
1649	if (!new_name)
1650	return 1;
1651
1652	(void)hashmap__find(name_map, orig_name, &dup_cnt);
1653	dup_cnt++;
1654
1655	err = hashmap__set(name_map, new_name, dup_cnt, &old_name, NULL);
1656	if (err)
1657	free(new_name);
1658
1659	free(old_name);
1660
1661	return dup_cnt;
1662	}
1663
1664	static const char *btf_dump_resolve_name(struct btf_dump *d, __u32 id,
1665	struct hashmap *name_map)
1666	{
1667	struct btf_dump_type_aux_state *s = &d->type_states[id];
1668	const struct btf_type *t = btf__type_by_id(btf: d->btf, id);
1669	const char *orig_name = btf_name_of(d, name_off: t->name_off);
1670	const char **cached_name = &d->cached_names[id];
1671	size_t dup_cnt;
1672
1673	if (t->name_off == 0)
1674	return "";
1675
1676	if (s->name_resolved)
1677	return *cached_name ? *cached_name : orig_name;
1678
1679	if (btf_is_fwd(t) || (btf_is_enum(t) && btf_vlen(t) == 0)) {
1680	s->name_resolved = 1;
1681	return orig_name;
1682	}
1683
1684	dup_cnt = btf_dump_name_dups(d, name_map, orig_name);
1685	if (dup_cnt > 1) {
1686	const size_t max_len = 256;
1687	char new_name[max_len];
1688
1689	snprintf(buf: new_name, size: max_len, fmt: "%s___%zu", orig_name, dup_cnt);
1690	*cached_name = strdup(new_name);
1691	}
1692
1693	s->name_resolved = 1;
1694	return *cached_name ? *cached_name : orig_name;
1695	}
1696
1697	static const char *btf_dump_type_name(struct btf_dump *d, __u32 id)
1698	{
1699	return btf_dump_resolve_name(d, id, name_map: d->type_names);
1700	}
1701
1702	static const char *btf_dump_ident_name(struct btf_dump *d, __u32 id)
1703	{
1704	return btf_dump_resolve_name(d, id, name_map: d->ident_names);
1705	}
1706
1707	static int btf_dump_dump_type_data(struct btf_dump *d,
1708	const char *fname,
1709	const struct btf_type *t,
1710	__u32 id,
1711	const void *data,
1712	__u8 bits_offset,
1713	__u8 bit_sz);
1714
1715	static const char *btf_dump_data_newline(struct btf_dump *d)
1716	{
1717	return d->typed_dump->compact || d->typed_dump->depth == 0 ? "" : "\n";
1718	}
1719
1720	static const char *btf_dump_data_delim(struct btf_dump *d)
1721	{
1722	return d->typed_dump->depth == 0 ? "" : ",";
1723	}
1724
1725	static void btf_dump_data_pfx(struct btf_dump *d)
1726	{
1727	int i, lvl = d->typed_dump->indent_lvl + d->typed_dump->depth;
1728
1729	if (d->typed_dump->compact)
1730	return;
1731
1732	for (i = 0; i < lvl; i++)
1733	btf_dump_printf(d, fmt: "%s", d->typed_dump->indent_str);
1734	}
1735
1736	/* A macro is used here as btf_type_value[s]() appends format specifiers
1737	* to the format specifier passed in; these do the work of appending
1738	* delimiters etc while the caller simply has to specify the type values
1739	* in the format specifier + value(s).
1740	*/
1741	#define btf_dump_type_values(d, fmt, ...) \
1742	btf_dump_printf(d, fmt "%s%s", \
1743	##__VA_ARGS__, \
1744	btf_dump_data_delim(d), \
1745	btf_dump_data_newline(d))
1746
1747	static int btf_dump_unsupported_data(struct btf_dump *d,
1748	const struct btf_type *t,
1749	__u32 id)
1750	{
1751	btf_dump_printf(d, fmt: "<unsupported kind:%u>", btf_kind(t));
1752	return -ENOTSUP;
1753	}
1754
1755	static int btf_dump_get_bitfield_value(struct btf_dump *d,
1756	const struct btf_type *t,
1757	const void *data,
1758	__u8 bits_offset,
1759	__u8 bit_sz,
1760	__u64 *value)
1761	{
1762	__u16 left_shift_bits, right_shift_bits;
1763	const __u8 *bytes = data;
1764	__u8 nr_copy_bits;
1765	__u64 num = 0;
1766	int i;
1767
1768	/* Maximum supported bitfield size is 64 bits */
1769	if (t->size > 8) {
1770	pr_warn("unexpected bitfield size %d\n", t->size);
1771	return -EINVAL;
1772	}
1773
1774	/* Bitfield value retrieval is done in two steps; first relevant bytes are
1775	* stored in num, then we left/right shift num to eliminate irrelevant bits.
1776	*/
1777	#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
1778	for (i = t->size - 1; i >= 0; i--)
1779	num = num * 256 + bytes[i];
1780	nr_copy_bits = bit_sz + bits_offset;
1781	#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
1782	for (i = 0; i < t->size; i++)
1783	num = num * 256 + bytes[i];
1784	nr_copy_bits = t->size * 8 - bits_offset;
1785	#else
1786	# error "Unrecognized __BYTE_ORDER__"
1787	#endif
1788	left_shift_bits = 64 - nr_copy_bits;
1789	right_shift_bits = 64 - bit_sz;
1790
1791	*value = (num << left_shift_bits) >> right_shift_bits;
1792
1793	return 0;
1794	}
1795
1796	static int btf_dump_bitfield_check_zero(struct btf_dump *d,
1797	const struct btf_type *t,
1798	const void *data,
1799	__u8 bits_offset,
1800	__u8 bit_sz)
1801	{
1802	__u64 check_num;
1803	int err;
1804
1805	err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, value: &check_num);
1806	if (err)
1807	return err;
1808	if (check_num == 0)
1809	return -ENODATA;
1810	return 0;
1811	}
1812
1813	static int btf_dump_bitfield_data(struct btf_dump *d,
1814	const struct btf_type *t,
1815	const void *data,
1816	__u8 bits_offset,
1817	__u8 bit_sz)
1818	{
1819	__u64 print_num;
1820	int err;
1821
1822	err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz, value: &print_num);
1823	if (err)
1824	return err;
1825
1826	btf_dump_type_values(d, "0x%llx", (unsigned long long)print_num);
1827
1828	return 0;
1829	}
1830
1831	/* ints, floats and ptrs */
1832	static int btf_dump_base_type_check_zero(struct btf_dump *d,
1833	const struct btf_type *t,
1834	__u32 id,
1835	const void *data)
1836	{
1837	static __u8 bytecmp[16] = {};
1838	int nr_bytes;
1839
1840	/* For pointer types, pointer size is not defined on a per-type basis.
1841	* On dump creation however, we store the pointer size.
1842	*/
1843	if (btf_kind(t) == BTF_KIND_PTR)
1844	nr_bytes = d->ptr_sz;
1845	else
1846	nr_bytes = t->size;
1847
1848	if (nr_bytes < 1 || nr_bytes > 16) {
1849	pr_warn("unexpected size %d for id [%u]\n", nr_bytes, id);
1850	return -EINVAL;
1851	}
1852
1853	if (memcmp(p: data, q: bytecmp, size: nr_bytes) == 0)
1854	return -ENODATA;
1855	return 0;
1856	}
1857
1858	static bool ptr_is_aligned(const struct btf *btf, __u32 type_id,
1859	const void *data)
1860	{
1861	int alignment = btf__align_of(btf, id: type_id);
1862
1863	if (alignment == 0)
1864	return false;
1865
1866	return ((uintptr_t)data) % alignment == 0;
1867	}
1868
1869	static int btf_dump_int_data(struct btf_dump *d,
1870	const struct btf_type *t,
1871	__u32 type_id,
1872	const void *data,
1873	__u8 bits_offset)
1874	{
1875	__u8 encoding = btf_int_encoding(t);
1876	bool sign = encoding & BTF_INT_SIGNED;
1877	char buf[16] __attribute__((aligned(16)));
1878	int sz = t->size;
1879
1880	if (sz == 0 || sz > sizeof(buf)) {
1881	pr_warn("unexpected size %d for id [%u]\n", sz, type_id);
1882	return -EINVAL;
1883	}
1884
1885	/* handle packed int data - accesses of integers not aligned on
1886	* int boundaries can cause problems on some platforms.
1887	*/
1888	if (!ptr_is_aligned(btf: d->btf, type_id, data)) {
1889	memcpy(buf, data, sz);
1890	data = buf;
1891	}
1892
1893	switch (sz) {
1894	case 16: {
1895	const __u64 *ints = data;
1896	__u64 lsi, msi;
1897
1898	/* avoid use of __int128 as some 32-bit platforms do not
1899	* support it.
1900	*/
1901	#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
1902	lsi = ints[0];
1903	msi = ints[1];
1904	#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
1905	lsi = ints[1];
1906	msi = ints[0];
1907	#else
1908	# error "Unrecognized __BYTE_ORDER__"
1909	#endif
1910	if (msi == 0)
1911	btf_dump_type_values(d, "0x%llx", (unsigned long long)lsi);
1912	else
1913	btf_dump_type_values(d, "0x%llx%016llx", (unsigned long long)msi,
1914	(unsigned long long)lsi);
1915	break;
1916	}
1917	case 8:
1918	if (sign)
1919	btf_dump_type_values(d, "%lld", *(long long *)data);
1920	else
1921	btf_dump_type_values(d, "%llu", *(unsigned long long *)data);
1922	break;
1923	case 4:
1924	if (sign)
1925	btf_dump_type_values(d, "%d", *(__s32 *)data);
1926	else
1927	btf_dump_type_values(d, "%u", *(__u32 *)data);
1928	break;
1929	case 2:
1930	if (sign)
1931	btf_dump_type_values(d, "%d", *(__s16 *)data);
1932	else
1933	btf_dump_type_values(d, "%u", *(__u16 *)data);
1934	break;
1935	case 1:
1936	if (d->typed_dump->is_array_char) {
1937	/* check for null terminator */
1938	if (d->typed_dump->is_array_terminated)
1939	break;
1940	if (*(char *)data == '\0') {
1941	btf_dump_type_values(d, "'\\0'");
1942	d->typed_dump->is_array_terminated = true;
1943	break;
1944	}
1945	if (isprint(*(char *)data)) {
1946	btf_dump_type_values(d, "'%c'", *(char *)data);
1947	break;
1948	}
1949	}
1950	if (sign)
1951	btf_dump_type_values(d, "%d", *(__s8 *)data);
1952	else
1953	btf_dump_type_values(d, "%u", *(__u8 *)data);
1954	break;
1955	default:
1956	pr_warn("unexpected sz %d for id [%u]\n", sz, type_id);
1957	return -EINVAL;
1958	}
1959	return 0;
1960	}
1961
1962	union float_data {
1963	long double ld;
1964	double d;
1965	float f;
1966	};
1967
1968	static int btf_dump_float_data(struct btf_dump *d,
1969	const struct btf_type *t,
1970	__u32 type_id,
1971	const void *data)
1972	{
1973	const union float_data *flp = data;
1974	union float_data fl;
1975	int sz = t->size;
1976
1977	/* handle unaligned data; copy to local union */
1978	if (!ptr_is_aligned(btf: d->btf, type_id, data)) {
1979	memcpy(&fl, data, sz);
1980	flp = &fl;
1981	}
1982
1983	switch (sz) {
1984	case 16:
1985	btf_dump_type_values(d, "%Lf", flp->ld);
1986	break;
1987	case 8:
1988	btf_dump_type_values(d, "%lf", flp->d);
1989	break;
1990	case 4:
1991	btf_dump_type_values(d, "%f", flp->f);
1992	break;
1993	default:
1994	pr_warn("unexpected size %d for id [%u]\n", sz, type_id);
1995	return -EINVAL;
1996	}
1997	return 0;
1998	}
1999
2000	static int btf_dump_var_data(struct btf_dump *d,
2001	const struct btf_type *v,
2002	__u32 id,
2003	const void *data)
2004	{
2005	enum btf_func_linkage linkage = btf_var(t: v)->linkage;
2006	const struct btf_type *t;
2007	const char *l;
2008	__u32 type_id;
2009
2010	switch (linkage) {
2011	case BTF_FUNC_STATIC:
2012	l = "static ";
2013	break;
2014	case BTF_FUNC_EXTERN:
2015	l = "extern ";
2016	break;
2017	case BTF_FUNC_GLOBAL:
2018	default:
2019	l = "";
2020	break;
2021	}
2022
2023	/* format of output here is [linkage] [type] [varname] = (type)value,
2024	* for example "static int cpu_profile_flip = (int)1"
2025	*/
2026	btf_dump_printf(d, fmt: "%s", l);
2027	type_id = v->type;
2028	t = btf__type_by_id(btf: d->btf, id: type_id);
2029	btf_dump_emit_type_cast(d, id: type_id, top_level: false);
2030	btf_dump_printf(d, fmt: " %s = ", btf_name_of(d, name_off: v->name_off));
2031	return btf_dump_dump_type_data(d, NULL, t, id: type_id, data, bits_offset: 0, bit_sz: 0);
2032	}
2033
2034	static int btf_dump_string_data(struct btf_dump *d,
2035	const struct btf_type *t,
2036	__u32 id,
2037	const void *data)
2038	{
2039	const struct btf_array *array = btf_array(t);
2040	const char *chars = data;
2041	__u32 i;
2042
2043	/* Make sure it is a NUL-terminated string. */
2044	for (i = 0; i < array->nelems; i++) {
2045	if ((void *)(chars + i) >= d->typed_dump->data_end)
2046	return -E2BIG;
2047	if (chars[i] == '\0')
2048	break;
2049	}
2050	if (i == array->nelems) {
2051	/* The caller will print this as a regular array. */
2052	return -EINVAL;
2053	}
2054
2055	btf_dump_data_pfx(d);
2056	btf_dump_printf(d, fmt: "\"");
2057
2058	for (i = 0; i < array->nelems; i++) {
2059	char c = chars[i];
2060
2061	if (c == '\0') {
2062	/*
2063	* When printing character arrays as strings, NUL bytes
2064	* are always treated as string terminators; they are
2065	* never printed.
2066	*/
2067	break;
2068	}
2069	if (isprint(c))
2070	btf_dump_printf(d, fmt: "%c", c);
2071	else
2072	btf_dump_printf(d, fmt: "\\x%02x", (__u8)c);
2073	}
2074
2075	btf_dump_printf(d, fmt: "\"");
2076
2077	return 0;
2078	}
2079
2080	static int btf_dump_array_data(struct btf_dump *d,
2081	const struct btf_type *t,
2082	__u32 id,
2083	const void *data)
2084	{
2085	const struct btf_array *array = btf_array(t);
2086	const struct btf_type *elem_type;
2087	__u32 i, elem_type_id;
2088	__s64 elem_size;
2089	bool is_array_member;
2090	bool is_array_terminated;
2091
2092	elem_type_id = array->type;
2093	elem_type = skip_mods_and_typedefs(btf: d->btf, id: elem_type_id, NULL);
2094	elem_size = btf__resolve_size(btf: d->btf, type_id: elem_type_id);
2095	if (elem_size <= 0) {
2096	pr_warn("unexpected elem size %zd for array type [%u]\n",
2097	(ssize_t)elem_size, id);
2098	return -EINVAL;
2099	}
2100
2101	if (btf_is_int(elem_type)) {
2102	/*
2103	* BTF_INT_CHAR encoding never seems to be set for
2104	* char arrays, so if size is 1 and element is
2105	* printable as a char, we'll do that.
2106	*/
2107	if (elem_size == 1) {
2108	if (d->typed_dump->emit_strings &&
2109	btf_dump_string_data(d, t, id, data) == 0) {
2110	return 0;
2111	}
2112	d->typed_dump->is_array_char = true;
2113	}
2114	}
2115
2116	/* note that we increment depth before calling btf_dump_print() below;
2117	* this is intentional. btf_dump_data_newline() will not print a
2118	* newline for depth 0 (since this leaves us with trailing newlines
2119	* at the end of typed display), so depth is incremented first.
2120	* For similar reasons, we decrement depth before showing the closing
2121	* parenthesis.
2122	*/
2123	d->typed_dump->depth++;
2124	btf_dump_printf(d, fmt: "[%s", btf_dump_data_newline(d));
2125
2126	/* may be a multidimensional array, so store current "is array member"
2127	* status so we can restore it correctly later.
2128	*/
2129	is_array_member = d->typed_dump->is_array_member;
2130	d->typed_dump->is_array_member = true;
2131	is_array_terminated = d->typed_dump->is_array_terminated;
2132	d->typed_dump->is_array_terminated = false;
2133	for (i = 0; i < array->nelems; i++, data += elem_size) {
2134	if (d->typed_dump->is_array_terminated)
2135	break;
2136	btf_dump_dump_type_data(d, NULL, t: elem_type, id: elem_type_id, data, bits_offset: 0, bit_sz: 0);
2137	}
2138	d->typed_dump->is_array_member = is_array_member;
2139	d->typed_dump->is_array_terminated = is_array_terminated;
2140	d->typed_dump->depth--;
2141	btf_dump_data_pfx(d);
2142	btf_dump_type_values(d, "]");
2143
2144	return 0;
2145	}
2146
2147	static int btf_dump_struct_data(struct btf_dump *d,
2148	const struct btf_type *t,
2149	__u32 id,
2150	const void *data)
2151	{
2152	const struct btf_member *m = btf_members(t);
2153	__u16 n = btf_vlen(t);
2154	int i, err = 0;
2155
2156	/* note that we increment depth before calling btf_dump_print() below;
2157	* this is intentional. btf_dump_data_newline() will not print a
2158	* newline for depth 0 (since this leaves us with trailing newlines
2159	* at the end of typed display), so depth is incremented first.
2160	* For similar reasons, we decrement depth before showing the closing
2161	* parenthesis.
2162	*/
2163	d->typed_dump->depth++;
2164	btf_dump_printf(d, fmt: "{%s", btf_dump_data_newline(d));
2165
2166	for (i = 0; i < n; i++, m++) {
2167	const struct btf_type *mtype;
2168	const char *mname;
2169	__u32 moffset;
2170	__u8 bit_sz;
2171
2172	mtype = btf__type_by_id(btf: d->btf, id: m->type);
2173	mname = btf_name_of(d, name_off: m->name_off);
2174	moffset = btf_member_bit_offset(t, i);
2175
2176	bit_sz = btf_member_bitfield_size(t, i);
2177	err = btf_dump_dump_type_data(d, fname: mname, t: mtype, id: m->type, data: data + moffset / 8,
2178	bits_offset: moffset % 8, bit_sz);
2179	if (err < 0)
2180	return err;
2181	}
2182	d->typed_dump->depth--;
2183	btf_dump_data_pfx(d);
2184	btf_dump_type_values(d, "}");
2185	return err;
2186	}
2187
2188	union ptr_data {
2189	unsigned int p;
2190	unsigned long long lp;
2191	};
2192
2193	static int btf_dump_ptr_data(struct btf_dump *d,
2194	const struct btf_type *t,
2195	__u32 id,
2196	const void *data)
2197	{
2198	if (ptr_is_aligned(btf: d->btf, type_id: id, data) && d->ptr_sz == sizeof(void *)) {
2199	btf_dump_type_values(d, "%p", *(void **)data);
2200	} else {
2201	union ptr_data pt;
2202
2203	memcpy(&pt, data, d->ptr_sz);
2204	if (d->ptr_sz == 4)
2205	btf_dump_type_values(d, "0x%x", pt.p);
2206	else
2207	btf_dump_type_values(d, "0x%llx", pt.lp);
2208	}
2209	return 0;
2210	}
2211
2212	static int btf_dump_get_enum_value(struct btf_dump *d,
2213	const struct btf_type *t,
2214	const void *data,
2215	__u32 id,
2216	__s64 *value)
2217	{
2218	bool is_signed = btf_kflag(t);
2219
2220	if (!ptr_is_aligned(btf: d->btf, type_id: id, data)) {
2221	__u64 val;
2222	int err;
2223
2224	err = btf_dump_get_bitfield_value(d, t, data, bits_offset: 0, bit_sz: 0, value: &val);
2225	if (err)
2226	return err;
2227	*value = (__s64)val;
2228	return 0;
2229	}
2230
2231	switch (t->size) {
2232	case 8:
2233	*value = *(__s64 *)data;
2234	return 0;
2235	case 4:
2236	*value = is_signed ? (__s64)*(__s32 *)data : *(__u32 *)data;
2237	return 0;
2238	case 2:
2239	*value = is_signed ? *(__s16 *)data : *(__u16 *)data;
2240	return 0;
2241	case 1:
2242	*value = is_signed ? *(__s8 *)data : *(__u8 *)data;
2243	return 0;
2244	default:
2245	pr_warn("unexpected size %d for enum, id:[%u]\n", t->size, id);
2246	return -EINVAL;
2247	}
2248	}
2249
2250	static int btf_dump_enum_data(struct btf_dump *d,
2251	const struct btf_type *t,
2252	__u32 id,
2253	const void *data)
2254	{
2255	bool is_signed;
2256	__s64 value;
2257	int i, err;
2258
2259	err = btf_dump_get_enum_value(d, t, data, id, value: &value);
2260	if (err)
2261	return err;
2262
2263	is_signed = btf_kflag(t);
2264	if (btf_is_enum(t)) {
2265	const struct btf_enum *e;
2266
2267	for (i = 0, e = btf_enum(t); i < btf_vlen(t); i++, e++) {
2268	if (value != e->val)
2269	continue;
2270	btf_dump_type_values(d, "%s", btf_name_of(d, e->name_off));
2271	return 0;
2272	}
2273
2274	btf_dump_type_values(d, is_signed ? "%d" : "%u", value);
2275	} else {
2276	const struct btf_enum64 *e;
2277
2278	for (i = 0, e = btf_enum64(t); i < btf_vlen(t); i++, e++) {
2279	if (value != btf_enum64_value(e))
2280	continue;
2281	btf_dump_type_values(d, "%s", btf_name_of(d, e->name_off));
2282	return 0;
2283	}
2284
2285	btf_dump_type_values(d, is_signed ? "%lldLL" : "%lluULL",
2286	(unsigned long long)value);
2287	}
2288	return 0;
2289	}
2290
2291	static int btf_dump_datasec_data(struct btf_dump *d,
2292	const struct btf_type *t,
2293	__u32 id,
2294	const void *data)
2295	{
2296	const struct btf_var_secinfo *vsi;
2297	const struct btf_type *var;
2298	__u32 i;
2299	int err;
2300
2301	btf_dump_type_values(d, "SEC(\"%s\") ", btf_name_of(d, t->name_off));
2302
2303	for (i = 0, vsi = btf_var_secinfos(t); i < btf_vlen(t); i++, vsi++) {
2304	var = btf__type_by_id(btf: d->btf, id: vsi->type);
2305	err = btf_dump_dump_type_data(d, NULL, t: var, id: vsi->type, data: data + vsi->offset, bits_offset: 0, bit_sz: 0);
2306	if (err < 0)
2307	return err;
2308	btf_dump_printf(d, fmt: ";");
2309	}
2310	return 0;
2311	}
2312
2313	/* return size of type, or if base type overflows, return -E2BIG. */
2314	static int btf_dump_type_data_check_overflow(struct btf_dump *d,
2315	const struct btf_type *t,
2316	__u32 id,
2317	const void *data,
2318	__u8 bits_offset,
2319	__u8 bit_sz)
2320	{
2321	__s64 size;
2322
2323	if (bit_sz) {
2324	/* bits_offset is at most 7. bit_sz is at most 128. */
2325	__u8 nr_bytes = (bits_offset + bit_sz + 7) / 8;
2326
2327	/* When bit_sz is non zero, it is called from
2328	* btf_dump_struct_data() where it only cares about
2329	* negative error value.
2330	* Return nr_bytes in success case to make it
2331	* consistent as the regular integer case below.
2332	*/
2333	return data + nr_bytes > d->typed_dump->data_end ? -E2BIG : nr_bytes;
2334	}
2335
2336	size = btf__resolve_size(btf: d->btf, type_id: id);
2337
2338	if (size < 0 || size >= INT_MAX) {
2339	pr_warn("unexpected size [%zu] for id [%u]\n",
2340	(size_t)size, id);
2341	return -EINVAL;
2342	}
2343
2344	/* Only do overflow checking for base types; we do not want to
2345	* avoid showing part of a struct, union or array, even if we
2346	* do not have enough data to show the full object. By
2347	* restricting overflow checking to base types we can ensure
2348	* that partial display succeeds, while avoiding overflowing
2349	* and using bogus data for display.
2350	*/
2351	t = skip_mods_and_typedefs(btf: d->btf, id, NULL);
2352	if (!t) {
2353	pr_warn("unexpected error skipping mods/typedefs for id [%u]\n",
2354	id);
2355	return -EINVAL;
2356	}
2357
2358	switch (btf_kind(t)) {
2359	case BTF_KIND_INT:
2360	case BTF_KIND_FLOAT:
2361	case BTF_KIND_PTR:
2362	case BTF_KIND_ENUM:
2363	case BTF_KIND_ENUM64:
2364	if (data + bits_offset / 8 + size > d->typed_dump->data_end)
2365	return -E2BIG;
2366	break;
2367	default:
2368	break;
2369	}
2370	return (int)size;
2371	}
2372
2373	static int btf_dump_type_data_check_zero(struct btf_dump *d,
2374	const struct btf_type *t,
2375	__u32 id,
2376	const void *data,
2377	__u8 bits_offset,
2378	__u8 bit_sz)
2379	{
2380	__s64 value;
2381	int i, err;
2382
2383	/* toplevel exceptions; we show zero values if
2384	* - we ask for them (emit_zeros)
2385	* - if we are at top-level so we see "struct empty { }"
2386	* - or if we are an array member and the array is non-empty and
2387	* not a char array; we don't want to be in a situation where we
2388	* have an integer array 0, 1, 0, 1 and only show non-zero values.
2389	* If the array contains zeroes only, or is a char array starting
2390	* with a '\0', the array-level check_zero() will prevent showing it;
2391	* we are concerned with determining zero value at the array member
2392	* level here.
2393	*/
2394	if (d->typed_dump->emit_zeroes || d->typed_dump->depth == 0 ||
2395	(d->typed_dump->is_array_member &&
2396	!d->typed_dump->is_array_char))
2397	return 0;
2398
2399	t = skip_mods_and_typedefs(btf: d->btf, id, NULL);
2400
2401	switch (btf_kind(t)) {
2402	case BTF_KIND_INT:
2403	if (bit_sz)
2404	return btf_dump_bitfield_check_zero(d, t, data, bits_offset, bit_sz);
2405	return btf_dump_base_type_check_zero(d, t, id, data);
2406	case BTF_KIND_FLOAT:
2407	case BTF_KIND_PTR:
2408	return btf_dump_base_type_check_zero(d, t, id, data);
2409	case BTF_KIND_ARRAY: {
2410	const struct btf_array *array = btf_array(t);
2411	const struct btf_type *elem_type;
2412	__u32 elem_type_id, elem_size;
2413	bool ischar;
2414
2415	elem_type_id = array->type;
2416	elem_size = btf__resolve_size(btf: d->btf, type_id: elem_type_id);
2417	elem_type = skip_mods_and_typedefs(btf: d->btf, id: elem_type_id, NULL);
2418
2419	ischar = btf_is_int(elem_type) && elem_size == 1;
2420
2421	/* check all elements; if _any_ element is nonzero, all
2422	* of array is displayed. We make an exception however
2423	* for char arrays where the first element is 0; these
2424	* are considered zeroed also, even if later elements are
2425	* non-zero because the string is terminated.
2426	*/
2427	for (i = 0; i < array->nelems; i++) {
2428	if (i == 0 && ischar && *(char *)data == 0)
2429	return -ENODATA;
2430	err = btf_dump_type_data_check_zero(d, t: elem_type,
2431	id: elem_type_id,
2432	data: data +
2433	(i * elem_size),
2434	bits_offset, bit_sz: 0);
2435	if (err != -ENODATA)
2436	return err;
2437	}
2438	return -ENODATA;
2439	}
2440	case BTF_KIND_STRUCT:
2441	case BTF_KIND_UNION: {
2442	const struct btf_member *m = btf_members(t);
2443	__u16 n = btf_vlen(t);
2444
2445	/* if any struct/union member is non-zero, the struct/union
2446	* is considered non-zero and dumped.
2447	*/
2448	for (i = 0; i < n; i++, m++) {
2449	const struct btf_type *mtype;
2450	__u32 moffset;
2451
2452	mtype = btf__type_by_id(btf: d->btf, id: m->type);
2453	moffset = btf_member_bit_offset(t, i);
2454
2455	/* btf_int_bits() does not store member bitfield size;
2456	* bitfield size needs to be stored here so int display
2457	* of member can retrieve it.
2458	*/
2459	bit_sz = btf_member_bitfield_size(t, i);
2460	err = btf_dump_type_data_check_zero(d, t: mtype, id: m->type, data: data + moffset / 8,
2461	bits_offset: moffset % 8, bit_sz);
2462	if (err != ENODATA)
2463	return err;
2464	}
2465	return -ENODATA;
2466	}
2467	case BTF_KIND_ENUM:
2468	case BTF_KIND_ENUM64:
2469	err = btf_dump_get_enum_value(d, t, data, id, value: &value);
2470	if (err)
2471	return err;
2472	if (value == 0)
2473	return -ENODATA;
2474	return 0;
2475	default:
2476	return 0;
2477	}
2478	}
2479
2480	/* returns size of data dumped, or error. */
2481	static int btf_dump_dump_type_data(struct btf_dump *d,
2482	const char *fname,
2483	const struct btf_type *t,
2484	__u32 id,
2485	const void *data,
2486	__u8 bits_offset,
2487	__u8 bit_sz)
2488	{
2489	int size, err = 0;
2490
2491	size = btf_dump_type_data_check_overflow(d, t, id, data, bits_offset, bit_sz);
2492	if (size < 0)
2493	return size;
2494	err = btf_dump_type_data_check_zero(d, t, id, data, bits_offset, bit_sz);
2495	if (err) {
2496	/* zeroed data is expected and not an error, so simply skip
2497	* dumping such data. Record other errors however.
2498	*/
2499	if (err == -ENODATA)
2500	return size;
2501	return err;
2502	}
2503	btf_dump_data_pfx(d);
2504
2505	if (!d->typed_dump->skip_names) {
2506	if (fname && strlen(fname) > 0)
2507	btf_dump_printf(d, fmt: ".%s = ", fname);
2508	btf_dump_emit_type_cast(d, id, top_level: true);
2509	}
2510
2511	t = skip_mods_and_typedefs(btf: d->btf, id, NULL);
2512
2513	switch (btf_kind(t)) {
2514	case BTF_KIND_UNKN:
2515	case BTF_KIND_FWD:
2516	case BTF_KIND_FUNC:
2517	case BTF_KIND_FUNC_PROTO:
2518	case BTF_KIND_DECL_TAG:
2519	err = btf_dump_unsupported_data(d, t, id);
2520	break;
2521	case BTF_KIND_INT:
2522	if (bit_sz)
2523	err = btf_dump_bitfield_data(d, t, data, bits_offset, bit_sz);
2524	else
2525	err = btf_dump_int_data(d, t, type_id: id, data, bits_offset);
2526	break;
2527	case BTF_KIND_FLOAT:
2528	err = btf_dump_float_data(d, t, type_id: id, data);
2529	break;
2530	case BTF_KIND_PTR:
2531	err = btf_dump_ptr_data(d, t, id, data);
2532	break;
2533	case BTF_KIND_ARRAY:
2534	err = btf_dump_array_data(d, t, id, data);
2535	break;
2536	case BTF_KIND_STRUCT:
2537	case BTF_KIND_UNION:
2538	err = btf_dump_struct_data(d, t, id, data);
2539	break;
2540	case BTF_KIND_ENUM:
2541	case BTF_KIND_ENUM64:
2542	/* handle bitfield and int enum values */
2543	if (bit_sz) {
2544	__u64 print_num;
2545	__s64 enum_val;
2546
2547	err = btf_dump_get_bitfield_value(d, t, data, bits_offset, bit_sz,
2548	value: &print_num);
2549	if (err)
2550	break;
2551	enum_val = (__s64)print_num;
2552	err = btf_dump_enum_data(d, t, id, data: &enum_val);
2553	} else
2554	err = btf_dump_enum_data(d, t, id, data);
2555	break;
2556	case BTF_KIND_VAR:
2557	err = btf_dump_var_data(d, v: t, id, data);
2558	break;
2559	case BTF_KIND_DATASEC:
2560	err = btf_dump_datasec_data(d, t, id, data);
2561	break;
2562	default:
2563	pr_warn("unexpected kind [%u] for id [%u]\n",
2564	BTF_INFO_KIND(t->info), id);
2565	return -EINVAL;
2566	}
2567	if (err < 0)
2568	return err;
2569	return size;
2570	}
2571
2572	int btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
2573	const void *data, size_t data_sz,
2574	const struct btf_dump_type_data_opts *opts)
2575	{
2576	struct btf_dump_data typed_dump = {};
2577	const struct btf_type *t;
2578	int ret;
2579
2580	if (!OPTS_VALID(opts, btf_dump_type_data_opts))
2581	return libbpf_err(ret: -EINVAL);
2582
2583	t = btf__type_by_id(btf: d->btf, id);
2584	if (!t)
2585	return libbpf_err(ret: -ENOENT);
2586
2587	d->typed_dump = &typed_dump;
2588	d->typed_dump->data_end = data + data_sz;
2589	d->typed_dump->indent_lvl = OPTS_GET(opts, indent_level, 0);
2590
2591	/* default indent string is a tab */
2592	if (!OPTS_GET(opts, indent_str, NULL))
2593	d->typed_dump->indent_str[0] = '\t';
2594	else
2595	libbpf_strlcpy(dst: d->typed_dump->indent_str, src: opts->indent_str,
2596	sz: sizeof(d->typed_dump->indent_str));
2597
2598	d->typed_dump->compact = OPTS_GET(opts, compact, false);
2599	d->typed_dump->skip_names = OPTS_GET(opts, skip_names, false);
2600	d->typed_dump->emit_zeroes = OPTS_GET(opts, emit_zeroes, false);
2601	d->typed_dump->emit_strings = OPTS_GET(opts, emit_strings, false);
2602
2603	ret = btf_dump_dump_type_data(d, NULL, t, id, data, bits_offset: 0, bit_sz: 0);
2604
2605	d->typed_dump = NULL;
2606
2607	return libbpf_err(ret);
2608	}
2609