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1// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2/* Copyright (c) 2018 Facebook */
3
4#include <byteswap.h>
5#include <endian.h>
6#include <stdio.h>
7#include <stdlib.h>
8#include <string.h>
9#include <fcntl.h>
10#include <unistd.h>
11#include <errno.h>
12#include <sys/utsname.h>
13#include <sys/param.h>
14#include <sys/stat.h>
15#include <linux/kernel.h>
16#include <linux/err.h>
17#include <linux/btf.h>
18#include <gelf.h>
19#include "btf.h"
20#include "bpf.h"
21#include "libbpf.h"
22#include "libbpf_internal.h"
23#include "hashmap.h"
24#include "strset.h"
25
26#define BTF_MAX_NR_TYPES 0x7fffffffU
27#define BTF_MAX_STR_OFFSET 0x7fffffffU
28
29static struct btf_type btf_void;
30
31struct btf {
32 /* raw BTF data in native endianness */
33 void *raw_data;
34 /* raw BTF data in non-native endianness */
35 void *raw_data_swapped;
36 __u32 raw_size;
37 /* whether target endianness differs from the native one */
38 bool swapped_endian;
39
40 /*
41 * When BTF is loaded from an ELF or raw memory it is stored
42 * in a contiguous memory block. The hdr, type_data, and, strs_data
43 * point inside that memory region to their respective parts of BTF
44 * representation:
45 *
46 * +--------------------------------+
47 * | Header | Types | Strings |
48 * +--------------------------------+
49 * ^ ^ ^
50 * | | |
51 * hdr | |
52 * types_data-+ |
53 * strs_data------------+
54 *
55 * If BTF data is later modified, e.g., due to types added or
56 * removed, BTF deduplication performed, etc, this contiguous
57 * representation is broken up into three independently allocated
58 * memory regions to be able to modify them independently.
59 * raw_data is nulled out at that point, but can be later allocated
60 * and cached again if user calls btf__raw_data(), at which point
61 * raw_data will contain a contiguous copy of header, types, and
62 * strings:
63 *
64 * +----------+ +---------+ +-----------+
65 * | Header | | Types | | Strings |
66 * +----------+ +---------+ +-----------+
67 * ^ ^ ^
68 * | | |
69 * hdr | |
70 * types_data----+ |
71 * strset__data(strs_set)-----+
72 *
73 * +----------+---------+-----------+
74 * | Header | Types | Strings |
75 * raw_data----->+----------+---------+-----------+
76 */
77 struct btf_header *hdr;
78
79 void *types_data;
80 size_t types_data_cap; /* used size stored in hdr->type_len */
81
82 /* type ID to `struct btf_type *` lookup index
83 * type_offs[0] corresponds to the first non-VOID type:
84 * - for base BTF it's type [1];
85 * - for split BTF it's the first non-base BTF type.
86 */
87 __u32 *type_offs;
88 size_t type_offs_cap;
89 /* number of types in this BTF instance:
90 * - doesn't include special [0] void type;
91 * - for split BTF counts number of types added on top of base BTF.
92 */
93 __u32 nr_types;
94 /* if not NULL, points to the base BTF on top of which the current
95 * split BTF is based
96 */
97 struct btf *base_btf;
98 /* BTF type ID of the first type in this BTF instance:
99 * - for base BTF it's equal to 1;
100 * - for split BTF it's equal to biggest type ID of base BTF plus 1.
101 */
102 int start_id;
103 /* logical string offset of this BTF instance:
104 * - for base BTF it's equal to 0;
105 * - for split BTF it's equal to total size of base BTF's string section size.
106 */
107 int start_str_off;
108
109 /* only one of strs_data or strs_set can be non-NULL, depending on
110 * whether BTF is in a modifiable state (strs_set is used) or not
111 * (strs_data points inside raw_data)
112 */
113 void *strs_data;
114 /* a set of unique strings */
115 struct strset *strs_set;
116 /* whether strings are already deduplicated */
117 bool strs_deduped;
118
119 /* BTF object FD, if loaded into kernel */
120 int fd;
121
122 /* Pointer size (in bytes) for a target architecture of this BTF */
123 int ptr_sz;
124};
125
126static inline __u64 ptr_to_u64(const void *ptr)
127{
128 return (__u64) (unsigned long) ptr;
129}
130
131/* Ensure given dynamically allocated memory region pointed to by *data* with
132 * capacity of *cap_cnt* elements each taking *elem_sz* bytes has enough
133 * memory to accommodate *add_cnt* new elements, assuming *cur_cnt* elements
134 * are already used. At most *max_cnt* elements can be ever allocated.
135 * If necessary, memory is reallocated and all existing data is copied over,
136 * new pointer to the memory region is stored at *data, new memory region
137 * capacity (in number of elements) is stored in *cap.
138 * On success, memory pointer to the beginning of unused memory is returned.
139 * On error, NULL is returned.
140 */
141void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
142 size_t cur_cnt, size_t max_cnt, size_t add_cnt)
143{
144 size_t new_cnt;
145 void *new_data;
146
147 if (cur_cnt + add_cnt <= *cap_cnt)
148 return *data + cur_cnt * elem_sz;
149
150 /* requested more than the set limit */
151 if (cur_cnt + add_cnt > max_cnt)
152 return NULL;
153
154 new_cnt = *cap_cnt;
155 new_cnt += new_cnt / 4; /* expand by 25% */
156 if (new_cnt < 16) /* but at least 16 elements */
157 new_cnt = 16;
158 if (new_cnt > max_cnt) /* but not exceeding a set limit */
159 new_cnt = max_cnt;
160 if (new_cnt < cur_cnt + add_cnt) /* also ensure we have enough memory */
161 new_cnt = cur_cnt + add_cnt;
162
163 new_data = libbpf_reallocarray(*data, new_cnt, elem_sz);
164 if (!new_data)
165 return NULL;
166
167 /* zero out newly allocated portion of memory */
168 memset(new_data + (*cap_cnt) * elem_sz, 0, (new_cnt - *cap_cnt) * elem_sz);
169
170 *data = new_data;
171 *cap_cnt = new_cnt;
172 return new_data + cur_cnt * elem_sz;
173}
174
175/* Ensure given dynamically allocated memory region has enough allocated space
176 * to accommodate *need_cnt* elements of size *elem_sz* bytes each
177 */
178int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt)
179{
180 void *p;
181
182 if (need_cnt <= *cap_cnt)
183 return 0;
184
185 p = libbpf_add_mem(data, cap_cnt, elem_sz, *cap_cnt, SIZE_MAX, need_cnt - *cap_cnt);
186 if (!p)
187 return -ENOMEM;
188
189 return 0;
190}
191
192static void *btf_add_type_offs_mem(struct btf *btf, size_t add_cnt)
193{
194 return libbpf_add_mem((void **)&btf->type_offs, &btf->type_offs_cap, sizeof(__u32),
195 btf->nr_types, BTF_MAX_NR_TYPES, add_cnt);
196}
197
198static int btf_add_type_idx_entry(struct btf *btf, __u32 type_off)
199{
200 __u32 *p;
201
202 p = btf_add_type_offs_mem(btf, 1);
203 if (!p)
204 return -ENOMEM;
205
206 *p = type_off;
207 return 0;
208}
209
210static void btf_bswap_hdr(struct btf_header *h)
211{
212 h->magic = bswap_16(h->magic);
213 h->hdr_len = bswap_32(h->hdr_len);
214 h->type_off = bswap_32(h->type_off);
215 h->type_len = bswap_32(h->type_len);
216 h->str_off = bswap_32(h->str_off);
217 h->str_len = bswap_32(h->str_len);
218}
219
220static int btf_parse_hdr(struct btf *btf)
221{
222 struct btf_header *hdr = btf->hdr;
223 __u32 meta_left;
224
225 if (btf->raw_size < sizeof(struct btf_header)) {
226 pr_debug("BTF header not found\n");
227 return -EINVAL;
228 }
229
230 if (hdr->magic == bswap_16(BTF_MAGIC)) {
231 btf->swapped_endian = true;
232 if (bswap_32(hdr->hdr_len) != sizeof(struct btf_header)) {
233 pr_warn("Can't load BTF with non-native endianness due to unsupported header length %u\n",
234 bswap_32(hdr->hdr_len));
235 return -ENOTSUP;
236 }
237 btf_bswap_hdr(hdr);
238 } else if (hdr->magic != BTF_MAGIC) {
239 pr_debug("Invalid BTF magic: %x\n", hdr->magic);
240 return -EINVAL;
241 }
242
243 if (btf->raw_size < hdr->hdr_len) {
244 pr_debug("BTF header len %u larger than data size %u\n",
245 hdr->hdr_len, btf->raw_size);
246 return -EINVAL;
247 }
248
249 meta_left = btf->raw_size - hdr->hdr_len;
250 if (meta_left < (long long)hdr->str_off + hdr->str_len) {
251 pr_debug("Invalid BTF total size: %u\n", btf->raw_size);
252 return -EINVAL;
253 }
254
255 if ((long long)hdr->type_off + hdr->type_len > hdr->str_off) {
256 pr_debug("Invalid BTF data sections layout: type data at %u + %u, strings data at %u + %u\n",
257 hdr->type_off, hdr->type_len, hdr->str_off, hdr->str_len);
258 return -EINVAL;
259 }
260
261 if (hdr->type_off % 4) {
262 pr_debug("BTF type section is not aligned to 4 bytes\n");
263 return -EINVAL;
264 }
265
266 return 0;
267}
268
269static int btf_parse_str_sec(struct btf *btf)
270{
271 const struct btf_header *hdr = btf->hdr;
272 const char *start = btf->strs_data;
273 const char *end = start + btf->hdr->str_len;
274
275 if (btf->base_btf && hdr->str_len == 0)
276 return 0;
277 if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_STR_OFFSET || end[-1]) {
278 pr_debug("Invalid BTF string section\n");
279 return -EINVAL;
280 }
281 if (!btf->base_btf && start[0]) {
282 pr_debug("Invalid BTF string section\n");
283 return -EINVAL;
284 }
285 return 0;
286}
287
288static int btf_type_size(const struct btf_type *t)
289{
290 const int base_size = sizeof(struct btf_type);
291 __u16 vlen = btf_vlen(t);
292
293 switch (btf_kind(t)) {
294 case BTF_KIND_FWD:
295 case BTF_KIND_CONST:
296 case BTF_KIND_VOLATILE:
297 case BTF_KIND_RESTRICT:
298 case BTF_KIND_PTR:
299 case BTF_KIND_TYPEDEF:
300 case BTF_KIND_FUNC:
301 case BTF_KIND_FLOAT:
302 case BTF_KIND_TYPE_TAG:
303 return base_size;
304 case BTF_KIND_INT:
305 return base_size + sizeof(__u32);
306 case BTF_KIND_ENUM:
307 return base_size + vlen * sizeof(struct btf_enum);
308 case BTF_KIND_ENUM64:
309 return base_size + vlen * sizeof(struct btf_enum64);
310 case BTF_KIND_ARRAY:
311 return base_size + sizeof(struct btf_array);
312 case BTF_KIND_STRUCT:
313 case BTF_KIND_UNION:
314 return base_size + vlen * sizeof(struct btf_member);
315 case BTF_KIND_FUNC_PROTO:
316 return base_size + vlen * sizeof(struct btf_param);
317 case BTF_KIND_VAR:
318 return base_size + sizeof(struct btf_var);
319 case BTF_KIND_DATASEC:
320 return base_size + vlen * sizeof(struct btf_var_secinfo);
321 case BTF_KIND_DECL_TAG:
322 return base_size + sizeof(struct btf_decl_tag);
323 default:
324 pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
325 return -EINVAL;
326 }
327}
328
329static void btf_bswap_type_base(struct btf_type *t)
330{
331 t->name_off = bswap_32(t->name_off);
332 t->info = bswap_32(t->info);
333 t->type = bswap_32(t->type);
334}
335
336static int btf_bswap_type_rest(struct btf_type *t)
337{
338 struct btf_var_secinfo *v;
339 struct btf_enum64 *e64;
340 struct btf_member *m;
341 struct btf_array *a;
342 struct btf_param *p;
343 struct btf_enum *e;
344 __u16 vlen = btf_vlen(t);
345 int i;
346
347 switch (btf_kind(t)) {
348 case BTF_KIND_FWD:
349 case BTF_KIND_CONST:
350 case BTF_KIND_VOLATILE:
351 case BTF_KIND_RESTRICT:
352 case BTF_KIND_PTR:
353 case BTF_KIND_TYPEDEF:
354 case BTF_KIND_FUNC:
355 case BTF_KIND_FLOAT:
356 case BTF_KIND_TYPE_TAG:
357 return 0;
358 case BTF_KIND_INT:
359 *(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
360 return 0;
361 case BTF_KIND_ENUM:
362 for (i = 0, e = btf_enum(t); i < vlen; i++, e++) {
363 e->name_off = bswap_32(e->name_off);
364 e->val = bswap_32(e->val);
365 }
366 return 0;
367 case BTF_KIND_ENUM64:
368 for (i = 0, e64 = btf_enum64(t); i < vlen; i++, e64++) {
369 e64->name_off = bswap_32(e64->name_off);
370 e64->val_lo32 = bswap_32(e64->val_lo32);
371 e64->val_hi32 = bswap_32(e64->val_hi32);
372 }
373 return 0;
374 case BTF_KIND_ARRAY:
375 a = btf_array(t);
376 a->type = bswap_32(a->type);
377 a->index_type = bswap_32(a->index_type);
378 a->nelems = bswap_32(a->nelems);
379 return 0;
380 case BTF_KIND_STRUCT:
381 case BTF_KIND_UNION:
382 for (i = 0, m = btf_members(t); i < vlen; i++, m++) {
383 m->name_off = bswap_32(m->name_off);
384 m->type = bswap_32(m->type);
385 m->offset = bswap_32(m->offset);
386 }
387 return 0;
388 case BTF_KIND_FUNC_PROTO:
389 for (i = 0, p = btf_params(t); i < vlen; i++, p++) {
390 p->name_off = bswap_32(p->name_off);
391 p->type = bswap_32(p->type);
392 }
393 return 0;
394 case BTF_KIND_VAR:
395 btf_var(t)->linkage = bswap_32(btf_var(t)->linkage);
396 return 0;
397 case BTF_KIND_DATASEC:
398 for (i = 0, v = btf_var_secinfos(t); i < vlen; i++, v++) {
399 v->type = bswap_32(v->type);
400 v->offset = bswap_32(v->offset);
401 v->size = bswap_32(v->size);
402 }
403 return 0;
404 case BTF_KIND_DECL_TAG:
405 btf_decl_tag(t)->component_idx = bswap_32(btf_decl_tag(t)->component_idx);
406 return 0;
407 default:
408 pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
409 return -EINVAL;
410 }
411}
412
413static int btf_parse_type_sec(struct btf *btf)
414{
415 struct btf_header *hdr = btf->hdr;
416 void *next_type = btf->types_data;
417 void *end_type = next_type + hdr->type_len;
418 int err, type_size;
419
420 while (next_type + sizeof(struct btf_type) <= end_type) {
421 if (btf->swapped_endian)
422 btf_bswap_type_base(next_type);
423
424 type_size = btf_type_size(next_type);
425 if (type_size < 0)
426 return type_size;
427 if (next_type + type_size > end_type) {
428 pr_warn("BTF type [%d] is malformed\n", btf->start_id + btf->nr_types);
429 return -EINVAL;
430 }
431
432 if (btf->swapped_endian && btf_bswap_type_rest(next_type))
433 return -EINVAL;
434
435 err = btf_add_type_idx_entry(btf, next_type - btf->types_data);
436 if (err)
437 return err;
438
439 next_type += type_size;
440 btf->nr_types++;
441 }
442
443 if (next_type != end_type) {
444 pr_warn("BTF types data is malformed\n");
445 return -EINVAL;
446 }
447
448 return 0;
449}
450
451static int btf_validate_str(const struct btf *btf, __u32 str_off, const char *what, __u32 type_id)
452{
453 const char *s;
454
455 s = btf__str_by_offset(btf, str_off);
456 if (!s) {
457 pr_warn("btf: type [%u]: invalid %s (string offset %u)\n", type_id, what, str_off);
458 return -EINVAL;
459 }
460
461 return 0;
462}
463
464static int btf_validate_id(const struct btf *btf, __u32 id, __u32 ctx_id)
465{
466 const struct btf_type *t;
467
468 t = btf__type_by_id(btf, id);
469 if (!t) {
470 pr_warn("btf: type [%u]: invalid referenced type ID %u\n", ctx_id, id);
471 return -EINVAL;
472 }
473
474 return 0;
475}
476
477static int btf_validate_type(const struct btf *btf, const struct btf_type *t, __u32 id)
478{
479 __u32 kind = btf_kind(t);
480 int err, i, n;
481
482 err = btf_validate_str(btf, t->name_off, "type name", id);
483 if (err)
484 return err;
485
486 switch (kind) {
487 case BTF_KIND_UNKN:
488 case BTF_KIND_INT:
489 case BTF_KIND_FWD:
490 case BTF_KIND_FLOAT:
491 break;
492 case BTF_KIND_PTR:
493 case BTF_KIND_TYPEDEF:
494 case BTF_KIND_VOLATILE:
495 case BTF_KIND_CONST:
496 case BTF_KIND_RESTRICT:
497 case BTF_KIND_VAR:
498 case BTF_KIND_DECL_TAG:
499 case BTF_KIND_TYPE_TAG:
500 err = btf_validate_id(btf, t->type, id);
501 if (err)
502 return err;
503 break;
504 case BTF_KIND_ARRAY: {
505 const struct btf_array *a = btf_array(t);
506
507 err = btf_validate_id(btf, a->type, id);
508 err = err ?: btf_validate_id(btf, a->index_type, id);
509 if (err)
510 return err;
511 break;
512 }
513 case BTF_KIND_STRUCT:
514 case BTF_KIND_UNION: {
515 const struct btf_member *m = btf_members(t);
516
517 n = btf_vlen(t);
518 for (i = 0; i < n; i++, m++) {
519 err = btf_validate_str(btf, m->name_off, "field name", id);
520 err = err ?: btf_validate_id(btf, m->type, id);
521 if (err)
522 return err;
523 }
524 break;
525 }
526 case BTF_KIND_ENUM: {
527 const struct btf_enum *m = btf_enum(t);
528
529 n = btf_vlen(t);
530 for (i = 0; i < n; i++, m++) {
531 err = btf_validate_str(btf, m->name_off, "enum name", id);
532 if (err)
533 return err;
534 }
535 break;
536 }
537 case BTF_KIND_ENUM64: {
538 const struct btf_enum64 *m = btf_enum64(t);
539
540 n = btf_vlen(t);
541 for (i = 0; i < n; i++, m++) {
542 err = btf_validate_str(btf, m->name_off, "enum name", id);
543 if (err)
544 return err;
545 }
546 break;
547 }
548 case BTF_KIND_FUNC: {
549 const struct btf_type *ft;
550
551 err = btf_validate_id(btf, t->type, id);
552 if (err)
553 return err;
554 ft = btf__type_by_id(btf, t->type);
555 if (btf_kind(ft) != BTF_KIND_FUNC_PROTO) {
556 pr_warn("btf: type [%u]: referenced type [%u] is not FUNC_PROTO\n", id, t->type);
557 return -EINVAL;
558 }
559 break;
560 }
561 case BTF_KIND_FUNC_PROTO: {
562 const struct btf_param *m = btf_params(t);
563
564 n = btf_vlen(t);
565 for (i = 0; i < n; i++, m++) {
566 err = btf_validate_str(btf, m->name_off, "param name", id);
567 err = err ?: btf_validate_id(btf, m->type, id);
568 if (err)
569 return err;
570 }
571 break;
572 }
573 case BTF_KIND_DATASEC: {
574 const struct btf_var_secinfo *m = btf_var_secinfos(t);
575
576 n = btf_vlen(t);
577 for (i = 0; i < n; i++, m++) {
578 err = btf_validate_id(btf, m->type, id);
579 if (err)
580 return err;
581 }
582 break;
583 }
584 default:
585 pr_warn("btf: type [%u]: unrecognized kind %u\n", id, kind);
586 return -EINVAL;
587 }
588 return 0;
589}
590
591/* Validate basic sanity of BTF. It's intentionally less thorough than
592 * kernel's validation and validates only properties of BTF that libbpf relies
593 * on to be correct (e.g., valid type IDs, valid string offsets, etc)
594 */
595static int btf_sanity_check(const struct btf *btf)
596{
597 const struct btf_type *t;
598 __u32 i, n = btf__type_cnt(btf);
599 int err;
600
601 for (i = 1; i < n; i++) {
602 t = btf_type_by_id(btf, i);
603 err = btf_validate_type(btf, t, i);
604 if (err)
605 return err;
606 }
607 return 0;
608}
609
610__u32 btf__type_cnt(const struct btf *btf)
611{
612 return btf->start_id + btf->nr_types;
613}
614
615const struct btf *btf__base_btf(const struct btf *btf)
616{
617 return btf->base_btf;
618}
619
620/* internal helper returning non-const pointer to a type */
621struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id)
622{
623 if (type_id == 0)
624 return &btf_void;
625 if (type_id < btf->start_id)
626 return btf_type_by_id(btf->base_btf, type_id);
627 return btf->types_data + btf->type_offs[type_id - btf->start_id];
628}
629
630const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
631{
632 if (type_id >= btf->start_id + btf->nr_types)
633 return errno = EINVAL, NULL;
634 return btf_type_by_id((struct btf *)btf, type_id);
635}
636
637static int determine_ptr_size(const struct btf *btf)
638{
639 static const char * const long_aliases[] = {
640 "long",
641 "long int",
642 "int long",
643 "unsigned long",
644 "long unsigned",
645 "unsigned long int",
646 "unsigned int long",
647 "long unsigned int",
648 "long int unsigned",
649 "int unsigned long",
650 "int long unsigned",
651 };
652 const struct btf_type *t;
653 const char *name;
654 int i, j, n;
655
656 if (btf->base_btf && btf->base_btf->ptr_sz > 0)
657 return btf->base_btf->ptr_sz;
658
659 n = btf__type_cnt(btf);
660 for (i = 1; i < n; i++) {
661 t = btf__type_by_id(btf, i);
662 if (!btf_is_int(t))
663 continue;
664
665 if (t->size != 4 && t->size != 8)
666 continue;
667
668 name = btf__name_by_offset(btf, t->name_off);
669 if (!name)
670 continue;
671
672 for (j = 0; j < ARRAY_SIZE(long_aliases); j++) {
673 if (strcmp(name, long_aliases[j]) == 0)
674 return t->size;
675 }
676 }
677
678 return -1;
679}
680
681static size_t btf_ptr_sz(const struct btf *btf)
682{
683 if (!btf->ptr_sz)
684 ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
685 return btf->ptr_sz < 0 ? sizeof(void *) : btf->ptr_sz;
686}
687
688/* Return pointer size this BTF instance assumes. The size is heuristically
689 * determined by looking for 'long' or 'unsigned long' integer type and
690 * recording its size in bytes. If BTF type information doesn't have any such
691 * type, this function returns 0. In the latter case, native architecture's
692 * pointer size is assumed, so will be either 4 or 8, depending on
693 * architecture that libbpf was compiled for. It's possible to override
694 * guessed value by using btf__set_pointer_size() API.
695 */
696size_t btf__pointer_size(const struct btf *btf)
697{
698 if (!btf->ptr_sz)
699 ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
700
701 if (btf->ptr_sz < 0)
702 /* not enough BTF type info to guess */
703 return 0;
704
705 return btf->ptr_sz;
706}
707
708/* Override or set pointer size in bytes. Only values of 4 and 8 are
709 * supported.
710 */
711int btf__set_pointer_size(struct btf *btf, size_t ptr_sz)
712{
713 if (ptr_sz != 4 && ptr_sz != 8)
714 return libbpf_err(-EINVAL);
715 btf->ptr_sz = ptr_sz;
716 return 0;
717}
718
719static bool is_host_big_endian(void)
720{
721#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
722 return false;
723#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
724 return true;
725#else
726# error "Unrecognized __BYTE_ORDER__"
727#endif
728}
729
730enum btf_endianness btf__endianness(const struct btf *btf)
731{
732 if (is_host_big_endian())
733 return btf->swapped_endian ? BTF_LITTLE_ENDIAN : BTF_BIG_ENDIAN;
734 else
735 return btf->swapped_endian ? BTF_BIG_ENDIAN : BTF_LITTLE_ENDIAN;
736}
737
738int btf__set_endianness(struct btf *btf, enum btf_endianness endian)
739{
740 if (endian != BTF_LITTLE_ENDIAN && endian != BTF_BIG_ENDIAN)
741 return libbpf_err(-EINVAL);
742
743 btf->swapped_endian = is_host_big_endian() != (endian == BTF_BIG_ENDIAN);
744 if (!btf->swapped_endian) {
745 free(btf->raw_data_swapped);
746 btf->raw_data_swapped = NULL;
747 }
748 return 0;
749}
750
751static bool btf_type_is_void(const struct btf_type *t)
752{
753 return t == &btf_void || btf_is_fwd(t);
754}
755
756static bool btf_type_is_void_or_null(const struct btf_type *t)
757{
758 return !t || btf_type_is_void(t);
759}
760
761#define MAX_RESOLVE_DEPTH 32
762
763__s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
764{
765 const struct btf_array *array;
766 const struct btf_type *t;
767 __u32 nelems = 1;
768 __s64 size = -1;
769 int i;
770
771 t = btf__type_by_id(btf, type_id);
772 for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t); i++) {
773 switch (btf_kind(t)) {
774 case BTF_KIND_INT:
775 case BTF_KIND_STRUCT:
776 case BTF_KIND_UNION:
777 case BTF_KIND_ENUM:
778 case BTF_KIND_ENUM64:
779 case BTF_KIND_DATASEC:
780 case BTF_KIND_FLOAT:
781 size = t->size;
782 goto done;
783 case BTF_KIND_PTR:
784 size = btf_ptr_sz(btf);
785 goto done;
786 case BTF_KIND_TYPEDEF:
787 case BTF_KIND_VOLATILE:
788 case BTF_KIND_CONST:
789 case BTF_KIND_RESTRICT:
790 case BTF_KIND_VAR:
791 case BTF_KIND_DECL_TAG:
792 case BTF_KIND_TYPE_TAG:
793 type_id = t->type;
794 break;
795 case BTF_KIND_ARRAY:
796 array = btf_array(t);
797 if (nelems && array->nelems > UINT32_MAX / nelems)
798 return libbpf_err(-E2BIG);
799 nelems *= array->nelems;
800 type_id = array->type;
801 break;
802 default:
803 return libbpf_err(-EINVAL);
804 }
805
806 t = btf__type_by_id(btf, type_id);
807 }
808
809done:
810 if (size < 0)
811 return libbpf_err(-EINVAL);
812 if (nelems && size > UINT32_MAX / nelems)
813 return libbpf_err(-E2BIG);
814
815 return nelems * size;
816}
817
818int btf__align_of(const struct btf *btf, __u32 id)
819{
820 const struct btf_type *t = btf__type_by_id(btf, id);
821 __u16 kind = btf_kind(t);
822
823 switch (kind) {
824 case BTF_KIND_INT:
825 case BTF_KIND_ENUM:
826 case BTF_KIND_ENUM64:
827 case BTF_KIND_FLOAT:
828 return min(btf_ptr_sz(btf), (size_t)t->size);
829 case BTF_KIND_PTR:
830 return btf_ptr_sz(btf);
831 case BTF_KIND_TYPEDEF:
832 case BTF_KIND_VOLATILE:
833 case BTF_KIND_CONST:
834 case BTF_KIND_RESTRICT:
835 case BTF_KIND_TYPE_TAG:
836 return btf__align_of(btf, t->type);
837 case BTF_KIND_ARRAY:
838 return btf__align_of(btf, btf_array(t)->type);
839 case BTF_KIND_STRUCT:
840 case BTF_KIND_UNION: {
841 const struct btf_member *m = btf_members(t);
842 __u16 vlen = btf_vlen(t);
843 int i, max_align = 1, align;
844
845 for (i = 0; i < vlen; i++, m++) {
846 align = btf__align_of(btf, m->type);
847 if (align <= 0)
848 return libbpf_err(align);
849 max_align = max(max_align, align);
850
851 /* if field offset isn't aligned according to field
852 * type's alignment, then struct must be packed
853 */
854 if (btf_member_bitfield_size(t, i) == 0 &&
855 (m->offset % (8 * align)) != 0)
856 return 1;
857 }
858
859 /* if struct/union size isn't a multiple of its alignment,
860 * then struct must be packed
861 */
862 if ((t->size % max_align) != 0)
863 return 1;
864
865 return max_align;
866 }
867 default:
868 pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
869 return errno = EINVAL, 0;
870 }
871}
872
873int btf__resolve_type(const struct btf *btf, __u32 type_id)
874{
875 const struct btf_type *t;
876 int depth = 0;
877
878 t = btf__type_by_id(btf, type_id);
879 while (depth < MAX_RESOLVE_DEPTH &&
880 !btf_type_is_void_or_null(t) &&
881 (btf_is_mod(t) || btf_is_typedef(t) || btf_is_var(t))) {
882 type_id = t->type;
883 t = btf__type_by_id(btf, type_id);
884 depth++;
885 }
886
887 if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
888 return libbpf_err(-EINVAL);
889
890 return type_id;
891}
892
893__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
894{
895 __u32 i, nr_types = btf__type_cnt(btf);
896
897 if (!strcmp(type_name, "void"))
898 return 0;
899
900 for (i = 1; i < nr_types; i++) {
901 const struct btf_type *t = btf__type_by_id(btf, i);
902 const char *name = btf__name_by_offset(btf, t->name_off);
903
904 if (name && !strcmp(type_name, name))
905 return i;
906 }
907
908 return libbpf_err(-ENOENT);
909}
910
911static __s32 btf_find_by_name_kind(const struct btf *btf, int start_id,
912 const char *type_name, __u32 kind)
913{
914 __u32 i, nr_types = btf__type_cnt(btf);
915
916 if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void"))
917 return 0;
918
919 for (i = start_id; i < nr_types; i++) {
920 const struct btf_type *t = btf__type_by_id(btf, i);
921 const char *name;
922
923 if (btf_kind(t) != kind)
924 continue;
925 name = btf__name_by_offset(btf, t->name_off);
926 if (name && !strcmp(type_name, name))
927 return i;
928 }
929
930 return libbpf_err(-ENOENT);
931}
932
933__s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name,
934 __u32 kind)
935{
936 return btf_find_by_name_kind(btf, btf->start_id, type_name, kind);
937}
938
939__s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
940 __u32 kind)
941{
942 return btf_find_by_name_kind(btf, 1, type_name, kind);
943}
944
945static bool btf_is_modifiable(const struct btf *btf)
946{
947 return (void *)btf->hdr != btf->raw_data;
948}
949
950void btf__free(struct btf *btf)
951{
952 if (IS_ERR_OR_NULL(btf))
953 return;
954
955 if (btf->fd >= 0)
956 close(btf->fd);
957
958 if (btf_is_modifiable(btf)) {
959 /* if BTF was modified after loading, it will have a split
960 * in-memory representation for header, types, and strings
961 * sections, so we need to free all of them individually. It
962 * might still have a cached contiguous raw data present,
963 * which will be unconditionally freed below.
964 */
965 free(btf->hdr);
966 free(btf->types_data);
967 strset__free(btf->strs_set);
968 }
969 free(btf->raw_data);
970 free(btf->raw_data_swapped);
971 free(btf->type_offs);
972 free(btf);
973}
974
975static struct btf *btf_new_empty(struct btf *base_btf)
976{
977 struct btf *btf;
978
979 btf = calloc(1, sizeof(*btf));
980 if (!btf)
981 return ERR_PTR(-ENOMEM);
982
983 btf->nr_types = 0;
984 btf->start_id = 1;
985 btf->start_str_off = 0;
986 btf->fd = -1;
987 btf->ptr_sz = sizeof(void *);
988 btf->swapped_endian = false;
989
990 if (base_btf) {
991 btf->base_btf = base_btf;
992 btf->start_id = btf__type_cnt(base_btf);
993 btf->start_str_off = base_btf->hdr->str_len;
994 }
995
996 /* +1 for empty string at offset 0 */
997 btf->raw_size = sizeof(struct btf_header) + (base_btf ? 0 : 1);
998 btf->raw_data = calloc(1, btf->raw_size);
999 if (!btf->raw_data) {
1000 free(btf);
1001 return ERR_PTR(-ENOMEM);
1002 }
1003
1004 btf->hdr = btf->raw_data;
1005 btf->hdr->hdr_len = sizeof(struct btf_header);
1006 btf->hdr->magic = BTF_MAGIC;
1007 btf->hdr->version = BTF_VERSION;
1008
1009 btf->types_data = btf->raw_data + btf->hdr->hdr_len;
1010 btf->strs_data = btf->raw_data + btf->hdr->hdr_len;
1011 btf->hdr->str_len = base_btf ? 0 : 1; /* empty string at offset 0 */
1012
1013 return btf;
1014}
1015
1016struct btf *btf__new_empty(void)
1017{
1018 return libbpf_ptr(btf_new_empty(NULL));
1019}
1020
1021struct btf *btf__new_empty_split(struct btf *base_btf)
1022{
1023 return libbpf_ptr(btf_new_empty(base_btf));
1024}
1025
1026static struct btf *btf_new(const void *data, __u32 size, struct btf *base_btf)
1027{
1028 struct btf *btf;
1029 int err;
1030
1031 btf = calloc(1, sizeof(struct btf));
1032 if (!btf)
1033 return ERR_PTR(-ENOMEM);
1034
1035 btf->nr_types = 0;
1036 btf->start_id = 1;
1037 btf->start_str_off = 0;
1038 btf->fd = -1;
1039
1040 if (base_btf) {
1041 btf->base_btf = base_btf;
1042 btf->start_id = btf__type_cnt(base_btf);
1043 btf->start_str_off = base_btf->hdr->str_len;
1044 }
1045
1046 btf->raw_data = malloc(size);
1047 if (!btf->raw_data) {
1048 err = -ENOMEM;
1049 goto done;
1050 }
1051 memcpy(btf->raw_data, data, size);
1052 btf->raw_size = size;
1053
1054 btf->hdr = btf->raw_data;
1055 err = btf_parse_hdr(btf);
1056 if (err)
1057 goto done;
1058
1059 btf->strs_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->str_off;
1060 btf->types_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->type_off;
1061
1062 err = btf_parse_str_sec(btf);
1063 err = err ?: btf_parse_type_sec(btf);
1064 err = err ?: btf_sanity_check(btf);
1065 if (err)
1066 goto done;
1067
1068done:
1069 if (err) {
1070 btf__free(btf);
1071 return ERR_PTR(err);
1072 }
1073
1074 return btf;
1075}
1076
1077struct btf *btf__new(const void *data, __u32 size)
1078{
1079 return libbpf_ptr(btf_new(data, size, NULL));
1080}
1081
1082static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
1083 struct btf_ext **btf_ext)
1084{
1085 Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
1086 int err = 0, fd = -1, idx = 0;
1087 struct btf *btf = NULL;
1088 Elf_Scn *scn = NULL;
1089 Elf *elf = NULL;
1090 GElf_Ehdr ehdr;
1091 size_t shstrndx;
1092
1093 if (elf_version(EV_CURRENT) == EV_NONE) {
1094 pr_warn("failed to init libelf for %s\n", path);
1095 return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
1096 }
1097
1098 fd = open(path, O_RDONLY | O_CLOEXEC);
1099 if (fd < 0) {
1100 err = -errno;
1101 pr_warn("failed to open %s: %s\n", path, strerror(errno));
1102 return ERR_PTR(err);
1103 }
1104
1105 err = -LIBBPF_ERRNO__FORMAT;
1106
1107 elf = elf_begin(fd, ELF_C_READ, NULL);
1108 if (!elf) {
1109 pr_warn("failed to open %s as ELF file\n", path);
1110 goto done;
1111 }
1112 if (!gelf_getehdr(elf, &ehdr)) {
1113 pr_warn("failed to get EHDR from %s\n", path);
1114 goto done;
1115 }
1116
1117 if (elf_getshdrstrndx(elf, &shstrndx)) {
1118 pr_warn("failed to get section names section index for %s\n",
1119 path);
1120 goto done;
1121 }
1122
1123 if (!elf_rawdata(elf_getscn(elf, shstrndx), NULL)) {
1124 pr_warn("failed to get e_shstrndx from %s\n", path);
1125 goto done;
1126 }
1127
1128 while ((scn = elf_nextscn(elf, scn)) != NULL) {
1129 GElf_Shdr sh;
1130 char *name;
1131
1132 idx++;
1133 if (gelf_getshdr(scn, &sh) != &sh) {
1134 pr_warn("failed to get section(%d) header from %s\n",
1135 idx, path);
1136 goto done;
1137 }
1138 name = elf_strptr(elf, shstrndx, sh.sh_name);
1139 if (!name) {
1140 pr_warn("failed to get section(%d) name from %s\n",
1141 idx, path);
1142 goto done;
1143 }
1144 if (strcmp(name, BTF_ELF_SEC) == 0) {
1145 btf_data = elf_getdata(scn, 0);
1146 if (!btf_data) {
1147 pr_warn("failed to get section(%d, %s) data from %s\n",
1148 idx, name, path);
1149 goto done;
1150 }
1151 continue;
1152 } else if (btf_ext && strcmp(name, BTF_EXT_ELF_SEC) == 0) {
1153 btf_ext_data = elf_getdata(scn, 0);
1154 if (!btf_ext_data) {
1155 pr_warn("failed to get section(%d, %s) data from %s\n",
1156 idx, name, path);
1157 goto done;
1158 }
1159 continue;
1160 }
1161 }
1162
1163 if (!btf_data) {
1164 pr_warn("failed to find '%s' ELF section in %s\n", BTF_ELF_SEC, path);
1165 err = -ENODATA;
1166 goto done;
1167 }
1168 btf = btf_new(btf_data->d_buf, btf_data->d_size, base_btf);
1169 err = libbpf_get_error(btf);
1170 if (err)
1171 goto done;
1172
1173 switch (gelf_getclass(elf)) {
1174 case ELFCLASS32:
1175 btf__set_pointer_size(btf, 4);
1176 break;
1177 case ELFCLASS64:
1178 btf__set_pointer_size(btf, 8);
1179 break;
1180 default:
1181 pr_warn("failed to get ELF class (bitness) for %s\n", path);
1182 break;
1183 }
1184
1185 if (btf_ext && btf_ext_data) {
1186 *btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
1187 err = libbpf_get_error(*btf_ext);
1188 if (err)
1189 goto done;
1190 } else if (btf_ext) {
1191 *btf_ext = NULL;
1192 }
1193done:
1194 if (elf)
1195 elf_end(elf);
1196 close(fd);
1197
1198 if (!err)
1199 return btf;
1200
1201 if (btf_ext)
1202 btf_ext__free(*btf_ext);
1203 btf__free(btf);
1204
1205 return ERR_PTR(err);
1206}
1207
1208struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
1209{
1210 return libbpf_ptr(btf_parse_elf(path, NULL, btf_ext));
1211}
1212
1213struct btf *btf__parse_elf_split(const char *path, struct btf *base_btf)
1214{
1215 return libbpf_ptr(btf_parse_elf(path, base_btf, NULL));
1216}
1217
1218static struct btf *btf_parse_raw(const char *path, struct btf *base_btf)
1219{
1220 struct btf *btf = NULL;
1221 void *data = NULL;
1222 FILE *f = NULL;
1223 __u16 magic;
1224 int err = 0;
1225 long sz;
1226
1227 f = fopen(path, "rbe");
1228 if (!f) {
1229 err = -errno;
1230 goto err_out;
1231 }
1232
1233 /* check BTF magic */
1234 if (fread(&magic, 1, sizeof(magic), f) < sizeof(magic)) {
1235 err = -EIO;
1236 goto err_out;
1237 }
1238 if (magic != BTF_MAGIC && magic != bswap_16(BTF_MAGIC)) {
1239 /* definitely not a raw BTF */
1240 err = -EPROTO;
1241 goto err_out;
1242 }
1243
1244 /* get file size */
1245 if (fseek(f, 0, SEEK_END)) {
1246 err = -errno;
1247 goto err_out;
1248 }
1249 sz = ftell(f);
1250 if (sz < 0) {
1251 err = -errno;
1252 goto err_out;
1253 }
1254 /* rewind to the start */
1255 if (fseek(f, 0, SEEK_SET)) {
1256 err = -errno;
1257 goto err_out;
1258 }
1259
1260 /* pre-alloc memory and read all of BTF data */
1261 data = malloc(sz);
1262 if (!data) {
1263 err = -ENOMEM;
1264 goto err_out;
1265 }
1266 if (fread(data, 1, sz, f) < sz) {
1267 err = -EIO;
1268 goto err_out;
1269 }
1270
1271 /* finally parse BTF data */
1272 btf = btf_new(data, sz, base_btf);
1273
1274err_out:
1275 free(data);
1276 if (f)
1277 fclose(f);
1278 return err ? ERR_PTR(err) : btf;
1279}
1280
1281struct btf *btf__parse_raw(const char *path)
1282{
1283 return libbpf_ptr(btf_parse_raw(path, NULL));
1284}
1285
1286struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf)
1287{
1288 return libbpf_ptr(btf_parse_raw(path, base_btf));
1289}
1290
1291static struct btf *btf_parse(const char *path, struct btf *base_btf, struct btf_ext **btf_ext)
1292{
1293 struct btf *btf;
1294 int err;
1295
1296 if (btf_ext)
1297 *btf_ext = NULL;
1298
1299 btf = btf_parse_raw(path, base_btf);
1300 err = libbpf_get_error(btf);
1301 if (!err)
1302 return btf;
1303 if (err != -EPROTO)
1304 return ERR_PTR(err);
1305 return btf_parse_elf(path, base_btf, btf_ext);
1306}
1307
1308struct btf *btf__parse(const char *path, struct btf_ext **btf_ext)
1309{
1310 return libbpf_ptr(btf_parse(path, NULL, btf_ext));
1311}
1312
1313struct btf *btf__parse_split(const char *path, struct btf *base_btf)
1314{
1315 return libbpf_ptr(btf_parse(path, base_btf, NULL));
1316}
1317
1318static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian);
1319
1320int btf_load_into_kernel(struct btf *btf, char *log_buf, size_t log_sz, __u32 log_level)
1321{
1322 LIBBPF_OPTS(bpf_btf_load_opts, opts);
1323 __u32 buf_sz = 0, raw_size;
1324 char *buf = NULL, *tmp;
1325 void *raw_data;
1326 int err = 0;
1327
1328 if (btf->fd >= 0)
1329 return libbpf_err(-EEXIST);
1330 if (log_sz && !log_buf)
1331 return libbpf_err(-EINVAL);
1332
1333 /* cache native raw data representation */
1334 raw_data = btf_get_raw_data(btf, &raw_size, false);
1335 if (!raw_data) {
1336 err = -ENOMEM;
1337 goto done;
1338 }
1339 btf->raw_size = raw_size;
1340 btf->raw_data = raw_data;
1341
1342retry_load:
1343 /* if log_level is 0, we won't provide log_buf/log_size to the kernel,
1344 * initially. Only if BTF loading fails, we bump log_level to 1 and
1345 * retry, using either auto-allocated or custom log_buf. This way
1346 * non-NULL custom log_buf provides a buffer just in case, but hopes
1347 * for successful load and no need for log_buf.
1348 */
1349 if (log_level) {
1350 /* if caller didn't provide custom log_buf, we'll keep
1351 * allocating our own progressively bigger buffers for BTF
1352 * verification log
1353 */
1354 if (!log_buf) {
1355 buf_sz = max((__u32)BPF_LOG_BUF_SIZE, buf_sz * 2);
1356 tmp = realloc(buf, buf_sz);
1357 if (!tmp) {
1358 err = -ENOMEM;
1359 goto done;
1360 }
1361 buf = tmp;
1362 buf[0] = '\0';
1363 }
1364
1365 opts.log_buf = log_buf ? log_buf : buf;
1366 opts.log_size = log_buf ? log_sz : buf_sz;
1367 opts.log_level = log_level;
1368 }
1369
1370 btf->fd = bpf_btf_load(raw_data, raw_size, &opts);
1371 if (btf->fd < 0) {
1372 /* time to turn on verbose mode and try again */
1373 if (log_level == 0) {
1374 log_level = 1;
1375 goto retry_load;
1376 }
1377 /* only retry if caller didn't provide custom log_buf, but
1378 * make sure we can never overflow buf_sz
1379 */
1380 if (!log_buf && errno == ENOSPC && buf_sz <= UINT_MAX / 2)
1381 goto retry_load;
1382
1383 err = -errno;
1384 pr_warn("BTF loading error: %d\n", err);
1385 /* don't print out contents of custom log_buf */
1386 if (!log_buf && buf[0])
1387 pr_warn("-- BEGIN BTF LOAD LOG ---\n%s\n-- END BTF LOAD LOG --\n", buf);
1388 }
1389
1390done:
1391 free(buf);
1392 return libbpf_err(err);
1393}
1394
1395int btf__load_into_kernel(struct btf *btf)
1396{
1397 return btf_load_into_kernel(btf, NULL, 0, 0);
1398}
1399
1400int btf__fd(const struct btf *btf)
1401{
1402 return btf->fd;
1403}
1404
1405void btf__set_fd(struct btf *btf, int fd)
1406{
1407 btf->fd = fd;
1408}
1409
1410static const void *btf_strs_data(const struct btf *btf)
1411{
1412 return btf->strs_data ? btf->strs_data : strset__data(btf->strs_set);
1413}
1414
1415static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian)
1416{
1417 struct btf_header *hdr = btf->hdr;
1418 struct btf_type *t;
1419 void *data, *p;
1420 __u32 data_sz;
1421 int i;
1422
1423 data = swap_endian ? btf->raw_data_swapped : btf->raw_data;
1424 if (data) {
1425 *size = btf->raw_size;
1426 return data;
1427 }
1428
1429 data_sz = hdr->hdr_len + hdr->type_len + hdr->str_len;
1430 data = calloc(1, data_sz);
1431 if (!data)
1432 return NULL;
1433 p = data;
1434
1435 memcpy(p, hdr, hdr->hdr_len);
1436 if (swap_endian)
1437 btf_bswap_hdr(p);
1438 p += hdr->hdr_len;
1439
1440 memcpy(p, btf->types_data, hdr->type_len);
1441 if (swap_endian) {
1442 for (i = 0; i < btf->nr_types; i++) {
1443 t = p + btf->type_offs[i];
1444 /* btf_bswap_type_rest() relies on native t->info, so
1445 * we swap base type info after we swapped all the
1446 * additional information
1447 */
1448 if (btf_bswap_type_rest(t))
1449 goto err_out;
1450 btf_bswap_type_base(t);
1451 }
1452 }
1453 p += hdr->type_len;
1454
1455 memcpy(p, btf_strs_data(btf), hdr->str_len);
1456 p += hdr->str_len;
1457
1458 *size = data_sz;
1459 return data;
1460err_out:
1461 free(data);
1462 return NULL;
1463}
1464
1465const void *btf__raw_data(const struct btf *btf_ro, __u32 *size)
1466{
1467 struct btf *btf = (struct btf *)btf_ro;
1468 __u32 data_sz;
1469 void *data;
1470
1471 data = btf_get_raw_data(btf, &data_sz, btf->swapped_endian);
1472 if (!data)
1473 return errno = ENOMEM, NULL;
1474
1475 btf->raw_size = data_sz;
1476 if (btf->swapped_endian)
1477 btf->raw_data_swapped = data;
1478 else
1479 btf->raw_data = data;
1480 *size = data_sz;
1481 return data;
1482}
1483
1484__attribute__((alias("btf__raw_data")))
1485const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
1486
1487const char *btf__str_by_offset(const struct btf *btf, __u32 offset)
1488{
1489 if (offset < btf->start_str_off)
1490 return btf__str_by_offset(btf->base_btf, offset);
1491 else if (offset - btf->start_str_off < btf->hdr->str_len)
1492 return btf_strs_data(btf) + (offset - btf->start_str_off);
1493 else
1494 return errno = EINVAL, NULL;
1495}
1496
1497const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
1498{
1499 return btf__str_by_offset(btf, offset);
1500}
1501
1502struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf)
1503{
1504 struct bpf_btf_info btf_info;
1505 __u32 len = sizeof(btf_info);
1506 __u32 last_size;
1507 struct btf *btf;
1508 void *ptr;
1509 int err;
1510
1511 /* we won't know btf_size until we call bpf_btf_get_info_by_fd(). so
1512 * let's start with a sane default - 4KiB here - and resize it only if
1513 * bpf_btf_get_info_by_fd() needs a bigger buffer.
1514 */
1515 last_size = 4096;
1516 ptr = malloc(last_size);
1517 if (!ptr)
1518 return ERR_PTR(-ENOMEM);
1519
1520 memset(&btf_info, 0, sizeof(btf_info));
1521 btf_info.btf = ptr_to_u64(ptr);
1522 btf_info.btf_size = last_size;
1523 err = bpf_btf_get_info_by_fd(btf_fd, &btf_info, &len);
1524
1525 if (!err && btf_info.btf_size > last_size) {
1526 void *temp_ptr;
1527
1528 last_size = btf_info.btf_size;
1529 temp_ptr = realloc(ptr, last_size);
1530 if (!temp_ptr) {
1531 btf = ERR_PTR(-ENOMEM);
1532 goto exit_free;
1533 }
1534 ptr = temp_ptr;
1535
1536 len = sizeof(btf_info);
1537 memset(&btf_info, 0, sizeof(btf_info));
1538 btf_info.btf = ptr_to_u64(ptr);
1539 btf_info.btf_size = last_size;
1540
1541 err = bpf_btf_get_info_by_fd(btf_fd, &btf_info, &len);
1542 }
1543
1544 if (err || btf_info.btf_size > last_size) {
1545 btf = err ? ERR_PTR(-errno) : ERR_PTR(-E2BIG);
1546 goto exit_free;
1547 }
1548
1549 btf = btf_new(ptr, btf_info.btf_size, base_btf);
1550
1551exit_free:
1552 free(ptr);
1553 return btf;
1554}
1555
1556struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf)
1557{
1558 struct btf *btf;
1559 int btf_fd;
1560
1561 btf_fd = bpf_btf_get_fd_by_id(id);
1562 if (btf_fd < 0)
1563 return libbpf_err_ptr(-errno);
1564
1565 btf = btf_get_from_fd(btf_fd, base_btf);
1566 close(btf_fd);
1567
1568 return libbpf_ptr(btf);
1569}
1570
1571struct btf *btf__load_from_kernel_by_id(__u32 id)
1572{
1573 return btf__load_from_kernel_by_id_split(id, NULL);
1574}
1575
1576static void btf_invalidate_raw_data(struct btf *btf)
1577{
1578 if (btf->raw_data) {
1579 free(btf->raw_data);
1580 btf->raw_data = NULL;
1581 }
1582 if (btf->raw_data_swapped) {
1583 free(btf->raw_data_swapped);
1584 btf->raw_data_swapped = NULL;
1585 }
1586}
1587
1588/* Ensure BTF is ready to be modified (by splitting into a three memory
1589 * regions for header, types, and strings). Also invalidate cached
1590 * raw_data, if any.
1591 */
1592static int btf_ensure_modifiable(struct btf *btf)
1593{
1594 void *hdr, *types;
1595 struct strset *set = NULL;
1596 int err = -ENOMEM;
1597
1598 if (btf_is_modifiable(btf)) {
1599 /* any BTF modification invalidates raw_data */
1600 btf_invalidate_raw_data(btf);
1601 return 0;
1602 }
1603
1604 /* split raw data into three memory regions */
1605 hdr = malloc(btf->hdr->hdr_len);
1606 types = malloc(btf->hdr->type_len);
1607 if (!hdr || !types)
1608 goto err_out;
1609
1610 memcpy(hdr, btf->hdr, btf->hdr->hdr_len);
1611 memcpy(types, btf->types_data, btf->hdr->type_len);
1612
1613 /* build lookup index for all strings */
1614 set = strset__new(BTF_MAX_STR_OFFSET, btf->strs_data, btf->hdr->str_len);
1615 if (IS_ERR(set)) {
1616 err = PTR_ERR(set);
1617 goto err_out;
1618 }
1619
1620 /* only when everything was successful, update internal state */
1621 btf->hdr = hdr;
1622 btf->types_data = types;
1623 btf->types_data_cap = btf->hdr->type_len;
1624 btf->strs_data = NULL;
1625 btf->strs_set = set;
1626 /* if BTF was created from scratch, all strings are guaranteed to be
1627 * unique and deduplicated
1628 */
1629 if (btf->hdr->str_len == 0)
1630 btf->strs_deduped = true;
1631 if (!btf->base_btf && btf->hdr->str_len == 1)
1632 btf->strs_deduped = true;
1633
1634 /* invalidate raw_data representation */
1635 btf_invalidate_raw_data(btf);
1636
1637 return 0;
1638
1639err_out:
1640 strset__free(set);
1641 free(hdr);
1642 free(types);
1643 return err;
1644}
1645
1646/* Find an offset in BTF string section that corresponds to a given string *s*.
1647 * Returns:
1648 * - >0 offset into string section, if string is found;
1649 * - -ENOENT, if string is not in the string section;
1650 * - <0, on any other error.
1651 */
1652int btf__find_str(struct btf *btf, const char *s)
1653{
1654 int off;
1655
1656 if (btf->base_btf) {
1657 off = btf__find_str(btf->base_btf, s);
1658 if (off != -ENOENT)
1659 return off;
1660 }
1661
1662 /* BTF needs to be in a modifiable state to build string lookup index */
1663 if (btf_ensure_modifiable(btf))
1664 return libbpf_err(-ENOMEM);
1665
1666 off = strset__find_str(btf->strs_set, s);
1667 if (off < 0)
1668 return libbpf_err(off);
1669
1670 return btf->start_str_off + off;
1671}
1672
1673/* Add a string s to the BTF string section.
1674 * Returns:
1675 * - > 0 offset into string section, on success;
1676 * - < 0, on error.
1677 */
1678int btf__add_str(struct btf *btf, const char *s)
1679{
1680 int off;
1681
1682 if (btf->base_btf) {
1683 off = btf__find_str(btf->base_btf, s);
1684 if (off != -ENOENT)
1685 return off;
1686 }
1687
1688 if (btf_ensure_modifiable(btf))
1689 return libbpf_err(-ENOMEM);
1690
1691 off = strset__add_str(btf->strs_set, s);
1692 if (off < 0)
1693 return libbpf_err(off);
1694
1695 btf->hdr->str_len = strset__data_size(btf->strs_set);
1696
1697 return btf->start_str_off + off;
1698}
1699
1700static void *btf_add_type_mem(struct btf *btf, size_t add_sz)
1701{
1702 return libbpf_add_mem(&btf->types_data, &btf->types_data_cap, 1,
1703 btf->hdr->type_len, UINT_MAX, add_sz);
1704}
1705
1706static void btf_type_inc_vlen(struct btf_type *t)
1707{
1708 t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, btf_kflag(t));
1709}
1710
1711static int btf_commit_type(struct btf *btf, int data_sz)
1712{
1713 int err;
1714
1715 err = btf_add_type_idx_entry(btf, btf->hdr->type_len);
1716 if (err)
1717 return libbpf_err(err);
1718
1719 btf->hdr->type_len += data_sz;
1720 btf->hdr->str_off += data_sz;
1721 btf->nr_types++;
1722 return btf->start_id + btf->nr_types - 1;
1723}
1724
1725struct btf_pipe {
1726 const struct btf *src;
1727 struct btf *dst;
1728 struct hashmap *str_off_map; /* map string offsets from src to dst */
1729};
1730
1731static int btf_rewrite_str(__u32 *str_off, void *ctx)
1732{
1733 struct btf_pipe *p = ctx;
1734 long mapped_off;
1735 int off, err;
1736
1737 if (!*str_off) /* nothing to do for empty strings */
1738 return 0;
1739
1740 if (p->str_off_map &&
1741 hashmap__find(p->str_off_map, *str_off, &mapped_off)) {
1742 *str_off = mapped_off;
1743 return 0;
1744 }
1745
1746 off = btf__add_str(p->dst, btf__str_by_offset(p->src, *str_off));
1747 if (off < 0)
1748 return off;
1749
1750 /* Remember string mapping from src to dst. It avoids
1751 * performing expensive string comparisons.
1752 */
1753 if (p->str_off_map) {
1754 err = hashmap__append(p->str_off_map, *str_off, off);
1755 if (err)
1756 return err;
1757 }
1758
1759 *str_off = off;
1760 return 0;
1761}
1762
1763int btf__add_type(struct btf *btf, const struct btf *src_btf, const struct btf_type *src_type)
1764{
1765 struct btf_pipe p = { .src = src_btf, .dst = btf };
1766 struct btf_type *t;
1767 int sz, err;
1768
1769 sz = btf_type_size(src_type);
1770 if (sz < 0)
1771 return libbpf_err(sz);
1772
1773 /* deconstruct BTF, if necessary, and invalidate raw_data */
1774 if (btf_ensure_modifiable(btf))
1775 return libbpf_err(-ENOMEM);
1776
1777 t = btf_add_type_mem(btf, sz);
1778 if (!t)
1779 return libbpf_err(-ENOMEM);
1780
1781 memcpy(t, src_type, sz);
1782
1783 err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
1784 if (err)
1785 return libbpf_err(err);
1786
1787 return btf_commit_type(btf, sz);
1788}
1789
1790static int btf_rewrite_type_ids(__u32 *type_id, void *ctx)
1791{
1792 struct btf *btf = ctx;
1793
1794 if (!*type_id) /* nothing to do for VOID references */
1795 return 0;
1796
1797 /* we haven't updated btf's type count yet, so
1798 * btf->start_id + btf->nr_types - 1 is the type ID offset we should
1799 * add to all newly added BTF types
1800 */
1801 *type_id += btf->start_id + btf->nr_types - 1;
1802 return 0;
1803}
1804
1805static size_t btf_dedup_identity_hash_fn(long key, void *ctx);
1806static bool btf_dedup_equal_fn(long k1, long k2, void *ctx);
1807
1808int btf__add_btf(struct btf *btf, const struct btf *src_btf)
1809{
1810 struct btf_pipe p = { .src = src_btf, .dst = btf };
1811 int data_sz, sz, cnt, i, err, old_strs_len;
1812 __u32 *off;
1813 void *t;
1814
1815 /* appending split BTF isn't supported yet */
1816 if (src_btf->base_btf)
1817 return libbpf_err(-ENOTSUP);
1818
1819 /* deconstruct BTF, if necessary, and invalidate raw_data */
1820 if (btf_ensure_modifiable(btf))
1821 return libbpf_err(-ENOMEM);
1822
1823 /* remember original strings section size if we have to roll back
1824 * partial strings section changes
1825 */
1826 old_strs_len = btf->hdr->str_len;
1827
1828 data_sz = src_btf->hdr->type_len;
1829 cnt = btf__type_cnt(src_btf) - 1;
1830
1831 /* pre-allocate enough memory for new types */
1832 t = btf_add_type_mem(btf, data_sz);
1833 if (!t)
1834 return libbpf_err(-ENOMEM);
1835
1836 /* pre-allocate enough memory for type offset index for new types */
1837 off = btf_add_type_offs_mem(btf, cnt);
1838 if (!off)
1839 return libbpf_err(-ENOMEM);
1840
1841 /* Map the string offsets from src_btf to the offsets from btf to improve performance */
1842 p.str_off_map = hashmap__new(btf_dedup_identity_hash_fn, btf_dedup_equal_fn, NULL);
1843 if (IS_ERR(p.str_off_map))
1844 return libbpf_err(-ENOMEM);
1845
1846 /* bulk copy types data for all types from src_btf */
1847 memcpy(t, src_btf->types_data, data_sz);
1848
1849 for (i = 0; i < cnt; i++) {
1850 sz = btf_type_size(t);
1851 if (sz < 0) {
1852 /* unlikely, has to be corrupted src_btf */
1853 err = sz;
1854 goto err_out;
1855 }
1856
1857 /* fill out type ID to type offset mapping for lookups by type ID */
1858 *off = t - btf->types_data;
1859
1860 /* add, dedup, and remap strings referenced by this BTF type */
1861 err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
1862 if (err)
1863 goto err_out;
1864
1865 /* remap all type IDs referenced from this BTF type */
1866 err = btf_type_visit_type_ids(t, btf_rewrite_type_ids, btf);
1867 if (err)
1868 goto err_out;
1869
1870 /* go to next type data and type offset index entry */
1871 t += sz;
1872 off++;
1873 }
1874
1875 /* Up until now any of the copied type data was effectively invisible,
1876 * so if we exited early before this point due to error, BTF would be
1877 * effectively unmodified. There would be extra internal memory
1878 * pre-allocated, but it would not be available for querying. But now
1879 * that we've copied and rewritten all the data successfully, we can
1880 * update type count and various internal offsets and sizes to
1881 * "commit" the changes and made them visible to the outside world.
1882 */
1883 btf->hdr->type_len += data_sz;
1884 btf->hdr->str_off += data_sz;
1885 btf->nr_types += cnt;
1886
1887 hashmap__free(p.str_off_map);
1888
1889 /* return type ID of the first added BTF type */
1890 return btf->start_id + btf->nr_types - cnt;
1891err_out:
1892 /* zero out preallocated memory as if it was just allocated with
1893 * libbpf_add_mem()
1894 */
1895 memset(btf->types_data + btf->hdr->type_len, 0, data_sz);
1896 memset(btf->strs_data + old_strs_len, 0, btf->hdr->str_len - old_strs_len);
1897
1898 /* and now restore original strings section size; types data size
1899 * wasn't modified, so doesn't need restoring, see big comment above
1900 */
1901 btf->hdr->str_len = old_strs_len;
1902
1903 hashmap__free(p.str_off_map);
1904
1905 return libbpf_err(err);
1906}
1907
1908/*
1909 * Append new BTF_KIND_INT type with:
1910 * - *name* - non-empty, non-NULL type name;
1911 * - *sz* - power-of-2 (1, 2, 4, ..) size of the type, in bytes;
1912 * - encoding is a combination of BTF_INT_SIGNED, BTF_INT_CHAR, BTF_INT_BOOL.
1913 * Returns:
1914 * - >0, type ID of newly added BTF type;
1915 * - <0, on error.
1916 */
1917int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding)
1918{
1919 struct btf_type *t;
1920 int sz, name_off;
1921
1922 /* non-empty name */
1923 if (!name || !name[0])
1924 return libbpf_err(-EINVAL);
1925 /* byte_sz must be power of 2 */
1926 if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 16)
1927 return libbpf_err(-EINVAL);
1928 if (encoding & ~(BTF_INT_SIGNED | BTF_INT_CHAR | BTF_INT_BOOL))
1929 return libbpf_err(-EINVAL);
1930
1931 /* deconstruct BTF, if necessary, and invalidate raw_data */
1932 if (btf_ensure_modifiable(btf))
1933 return libbpf_err(-ENOMEM);
1934
1935 sz = sizeof(struct btf_type) + sizeof(int);
1936 t = btf_add_type_mem(btf, sz);
1937 if (!t)
1938 return libbpf_err(-ENOMEM);
1939
1940 /* if something goes wrong later, we might end up with an extra string,
1941 * but that shouldn't be a problem, because BTF can't be constructed
1942 * completely anyway and will most probably be just discarded
1943 */
1944 name_off = btf__add_str(btf, name);
1945 if (name_off < 0)
1946 return name_off;
1947
1948 t->name_off = name_off;
1949 t->info = btf_type_info(BTF_KIND_INT, 0, 0);
1950 t->size = byte_sz;
1951 /* set INT info, we don't allow setting legacy bit offset/size */
1952 *(__u32 *)(t + 1) = (encoding << 24) | (byte_sz * 8);
1953
1954 return btf_commit_type(btf, sz);
1955}
1956
1957/*
1958 * Append new BTF_KIND_FLOAT type with:
1959 * - *name* - non-empty, non-NULL type name;
1960 * - *sz* - size of the type, in bytes;
1961 * Returns:
1962 * - >0, type ID of newly added BTF type;
1963 * - <0, on error.
1964 */
1965int btf__add_float(struct btf *btf, const char *name, size_t byte_sz)
1966{
1967 struct btf_type *t;
1968 int sz, name_off;
1969
1970 /* non-empty name */
1971 if (!name || !name[0])
1972 return libbpf_err(-EINVAL);
1973
1974 /* byte_sz must be one of the explicitly allowed values */
1975 if (byte_sz != 2 && byte_sz != 4 && byte_sz != 8 && byte_sz != 12 &&
1976 byte_sz != 16)
1977 return libbpf_err(-EINVAL);
1978
1979 if (btf_ensure_modifiable(btf))
1980 return libbpf_err(-ENOMEM);
1981
1982 sz = sizeof(struct btf_type);
1983 t = btf_add_type_mem(btf, sz);
1984 if (!t)
1985 return libbpf_err(-ENOMEM);
1986
1987 name_off = btf__add_str(btf, name);
1988 if (name_off < 0)
1989 return name_off;
1990
1991 t->name_off = name_off;
1992 t->info = btf_type_info(BTF_KIND_FLOAT, 0, 0);
1993 t->size = byte_sz;
1994
1995 return btf_commit_type(btf, sz);
1996}
1997
1998/* it's completely legal to append BTF types with type IDs pointing forward to
1999 * types that haven't been appended yet, so we only make sure that id looks
2000 * sane, we can't guarantee that ID will always be valid
2001 */
2002static int validate_type_id(int id)
2003{
2004 if (id < 0 || id > BTF_MAX_NR_TYPES)
2005 return -EINVAL;
2006 return 0;
2007}
2008
2009/* generic append function for PTR, TYPEDEF, CONST/VOLATILE/RESTRICT */
2010static int btf_add_ref_kind(struct btf *btf, int kind, const char *name, int ref_type_id)
2011{
2012 struct btf_type *t;
2013 int sz, name_off = 0;
2014
2015 if (validate_type_id(ref_type_id))
2016 return libbpf_err(-EINVAL);
2017
2018 if (btf_ensure_modifiable(btf))
2019 return libbpf_err(-ENOMEM);
2020
2021 sz = sizeof(struct btf_type);
2022 t = btf_add_type_mem(btf, sz);
2023 if (!t)
2024 return libbpf_err(-ENOMEM);
2025
2026 if (name && name[0]) {
2027 name_off = btf__add_str(btf, name);
2028 if (name_off < 0)
2029 return name_off;
2030 }
2031
2032 t->name_off = name_off;
2033 t->info = btf_type_info(kind, 0, 0);
2034 t->type = ref_type_id;
2035
2036 return btf_commit_type(btf, sz);
2037}
2038
2039/*
2040 * Append new BTF_KIND_PTR type with:
2041 * - *ref_type_id* - referenced type ID, it might not exist yet;
2042 * Returns:
2043 * - >0, type ID of newly added BTF type;
2044 * - <0, on error.
2045 */
2046int btf__add_ptr(struct btf *btf, int ref_type_id)
2047{
2048 return btf_add_ref_kind(btf, BTF_KIND_PTR, NULL, ref_type_id);
2049}
2050
2051/*
2052 * Append new BTF_KIND_ARRAY type with:
2053 * - *index_type_id* - type ID of the type describing array index;
2054 * - *elem_type_id* - type ID of the type describing array element;
2055 * - *nr_elems* - the size of the array;
2056 * Returns:
2057 * - >0, type ID of newly added BTF type;
2058 * - <0, on error.
2059 */
2060int btf__add_array(struct btf *btf, int index_type_id, int elem_type_id, __u32 nr_elems)
2061{
2062 struct btf_type *t;
2063 struct btf_array *a;
2064 int sz;
2065
2066 if (validate_type_id(index_type_id) || validate_type_id(elem_type_id))
2067 return libbpf_err(-EINVAL);
2068
2069 if (btf_ensure_modifiable(btf))
2070 return libbpf_err(-ENOMEM);
2071
2072 sz = sizeof(struct btf_type) + sizeof(struct btf_array);
2073 t = btf_add_type_mem(btf, sz);
2074 if (!t)
2075 return libbpf_err(-ENOMEM);
2076
2077 t->name_off = 0;
2078 t->info = btf_type_info(BTF_KIND_ARRAY, 0, 0);
2079 t->size = 0;
2080
2081 a = btf_array(t);
2082 a->type = elem_type_id;
2083 a->index_type = index_type_id;
2084 a->nelems = nr_elems;
2085
2086 return btf_commit_type(btf, sz);
2087}
2088
2089/* generic STRUCT/UNION append function */
2090static int btf_add_composite(struct btf *btf, int kind, const char *name, __u32 bytes_sz)
2091{
2092 struct btf_type *t;
2093 int sz, name_off = 0;
2094
2095 if (btf_ensure_modifiable(btf))
2096 return libbpf_err(-ENOMEM);
2097
2098 sz = sizeof(struct btf_type);
2099 t = btf_add_type_mem(btf, sz);
2100 if (!t)
2101 return libbpf_err(-ENOMEM);
2102
2103 if (name && name[0]) {
2104 name_off = btf__add_str(btf, name);
2105 if (name_off < 0)
2106 return name_off;
2107 }
2108
2109 /* start out with vlen=0 and no kflag; this will be adjusted when
2110 * adding each member
2111 */
2112 t->name_off = name_off;
2113 t->info = btf_type_info(kind, 0, 0);
2114 t->size = bytes_sz;
2115
2116 return btf_commit_type(btf, sz);
2117}
2118
2119/*
2120 * Append new BTF_KIND_STRUCT type with:
2121 * - *name* - name of the struct, can be NULL or empty for anonymous structs;
2122 * - *byte_sz* - size of the struct, in bytes;
2123 *
2124 * Struct initially has no fields in it. Fields can be added by
2125 * btf__add_field() right after btf__add_struct() succeeds.
2126 *
2127 * Returns:
2128 * - >0, type ID of newly added BTF type;
2129 * - <0, on error.
2130 */
2131int btf__add_struct(struct btf *btf, const char *name, __u32 byte_sz)
2132{
2133 return btf_add_composite(btf, BTF_KIND_STRUCT, name, byte_sz);
2134}
2135
2136/*
2137 * Append new BTF_KIND_UNION type with:
2138 * - *name* - name of the union, can be NULL or empty for anonymous union;
2139 * - *byte_sz* - size of the union, in bytes;
2140 *
2141 * Union initially has no fields in it. Fields can be added by
2142 * btf__add_field() right after btf__add_union() succeeds. All fields
2143 * should have *bit_offset* of 0.
2144 *
2145 * Returns:
2146 * - >0, type ID of newly added BTF type;
2147 * - <0, on error.
2148 */
2149int btf__add_union(struct btf *btf, const char *name, __u32 byte_sz)
2150{
2151 return btf_add_composite(btf, BTF_KIND_UNION, name, byte_sz);
2152}
2153
2154static struct btf_type *btf_last_type(struct btf *btf)
2155{
2156 return btf_type_by_id(btf, btf__type_cnt(btf) - 1);
2157}
2158
2159/*
2160 * Append new field for the current STRUCT/UNION type with:
2161 * - *name* - name of the field, can be NULL or empty for anonymous field;
2162 * - *type_id* - type ID for the type describing field type;
2163 * - *bit_offset* - bit offset of the start of the field within struct/union;
2164 * - *bit_size* - bit size of a bitfield, 0 for non-bitfield fields;
2165 * Returns:
2166 * - 0, on success;
2167 * - <0, on error.
2168 */
2169int btf__add_field(struct btf *btf, const char *name, int type_id,
2170 __u32 bit_offset, __u32 bit_size)
2171{
2172 struct btf_type *t;
2173 struct btf_member *m;
2174 bool is_bitfield;
2175 int sz, name_off = 0;
2176
2177 /* last type should be union/struct */
2178 if (btf->nr_types == 0)
2179 return libbpf_err(-EINVAL);
2180 t = btf_last_type(btf);
2181 if (!btf_is_composite(t))
2182 return libbpf_err(-EINVAL);
2183
2184 if (validate_type_id(type_id))
2185 return libbpf_err(-EINVAL);
2186 /* best-effort bit field offset/size enforcement */
2187 is_bitfield = bit_size || (bit_offset % 8 != 0);
2188 if (is_bitfield && (bit_size == 0 || bit_size > 255 || bit_offset > 0xffffff))
2189 return libbpf_err(-EINVAL);
2190
2191 /* only offset 0 is allowed for unions */
2192 if (btf_is_union(t) && bit_offset)
2193 return libbpf_err(-EINVAL);
2194
2195 /* decompose and invalidate raw data */
2196 if (btf_ensure_modifiable(btf))
2197 return libbpf_err(-ENOMEM);
2198
2199 sz = sizeof(struct btf_member);
2200 m = btf_add_type_mem(btf, sz);
2201 if (!m)
2202 return libbpf_err(-ENOMEM);
2203
2204 if (name && name[0]) {
2205 name_off = btf__add_str(btf, name);
2206 if (name_off < 0)
2207 return name_off;
2208 }
2209
2210 m->name_off = name_off;
2211 m->type = type_id;
2212 m->offset = bit_offset | (bit_size << 24);
2213
2214 /* btf_add_type_mem can invalidate t pointer */
2215 t = btf_last_type(btf);
2216 /* update parent type's vlen and kflag */
2217 t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, is_bitfield || btf_kflag(t));
2218
2219 btf->hdr->type_len += sz;
2220 btf->hdr->str_off += sz;
2221 return 0;
2222}
2223
2224static int btf_add_enum_common(struct btf *btf, const char *name, __u32 byte_sz,
2225 bool is_signed, __u8 kind)
2226{
2227 struct btf_type *t;
2228 int sz, name_off = 0;
2229
2230 /* byte_sz must be power of 2 */
2231 if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 8)
2232 return libbpf_err(-EINVAL);
2233
2234 if (btf_ensure_modifiable(btf))
2235 return libbpf_err(-ENOMEM);
2236
2237 sz = sizeof(struct btf_type);
2238 t = btf_add_type_mem(btf, sz);
2239 if (!t)
2240 return libbpf_err(-ENOMEM);
2241
2242 if (name && name[0]) {
2243 name_off = btf__add_str(btf, name);
2244 if (name_off < 0)
2245 return name_off;
2246 }
2247
2248 /* start out with vlen=0; it will be adjusted when adding enum values */
2249 t->name_off = name_off;
2250 t->info = btf_type_info(kind, 0, is_signed);
2251 t->size = byte_sz;
2252
2253 return btf_commit_type(btf, sz);
2254}
2255
2256/*
2257 * Append new BTF_KIND_ENUM type with:
2258 * - *name* - name of the enum, can be NULL or empty for anonymous enums;
2259 * - *byte_sz* - size of the enum, in bytes.
2260 *
2261 * Enum initially has no enum values in it (and corresponds to enum forward
2262 * declaration). Enumerator values can be added by btf__add_enum_value()
2263 * immediately after btf__add_enum() succeeds.
2264 *
2265 * Returns:
2266 * - >0, type ID of newly added BTF type;
2267 * - <0, on error.
2268 */
2269int btf__add_enum(struct btf *btf, const char *name, __u32 byte_sz)
2270{
2271 /*
2272 * set the signedness to be unsigned, it will change to signed
2273 * if any later enumerator is negative.
2274 */
2275 return btf_add_enum_common(btf, name, byte_sz, false, BTF_KIND_ENUM);
2276}
2277
2278/*
2279 * Append new enum value for the current ENUM type with:
2280 * - *name* - name of the enumerator value, can't be NULL or empty;
2281 * - *value* - integer value corresponding to enum value *name*;
2282 * Returns:
2283 * - 0, on success;
2284 * - <0, on error.
2285 */
2286int btf__add_enum_value(struct btf *btf, const char *name, __s64 value)
2287{
2288 struct btf_type *t;
2289 struct btf_enum *v;
2290 int sz, name_off;
2291
2292 /* last type should be BTF_KIND_ENUM */
2293 if (btf->nr_types == 0)
2294 return libbpf_err(-EINVAL);
2295 t = btf_last_type(btf);
2296 if (!btf_is_enum(t))
2297 return libbpf_err(-EINVAL);
2298
2299 /* non-empty name */
2300 if (!name || !name[0])
2301 return libbpf_err(-EINVAL);
2302 if (value < INT_MIN || value > UINT_MAX)
2303 return libbpf_err(-E2BIG);
2304
2305 /* decompose and invalidate raw data */
2306 if (btf_ensure_modifiable(btf))
2307 return libbpf_err(-ENOMEM);
2308
2309 sz = sizeof(struct btf_enum);
2310 v = btf_add_type_mem(btf, sz);
2311 if (!v)
2312 return libbpf_err(-ENOMEM);
2313
2314 name_off = btf__add_str(btf, name);
2315 if (name_off < 0)
2316 return name_off;
2317
2318 v->name_off = name_off;
2319 v->val = value;
2320
2321 /* update parent type's vlen */
2322 t = btf_last_type(btf);
2323 btf_type_inc_vlen(t);
2324
2325 /* if negative value, set signedness to signed */
2326 if (value < 0)
2327 t->info = btf_type_info(btf_kind(t), btf_vlen(t), true);
2328
2329 btf->hdr->type_len += sz;
2330 btf->hdr->str_off += sz;
2331 return 0;
2332}
2333
2334/*
2335 * Append new BTF_KIND_ENUM64 type with:
2336 * - *name* - name of the enum, can be NULL or empty for anonymous enums;
2337 * - *byte_sz* - size of the enum, in bytes.
2338 * - *is_signed* - whether the enum values are signed or not;
2339 *
2340 * Enum initially has no enum values in it (and corresponds to enum forward
2341 * declaration). Enumerator values can be added by btf__add_enum64_value()
2342 * immediately after btf__add_enum64() succeeds.
2343 *
2344 * Returns:
2345 * - >0, type ID of newly added BTF type;
2346 * - <0, on error.
2347 */
2348int btf__add_enum64(struct btf *btf, const char *name, __u32 byte_sz,
2349 bool is_signed)
2350{
2351 return btf_add_enum_common(btf, name, byte_sz, is_signed,
2352 BTF_KIND_ENUM64);
2353}
2354
2355/*
2356 * Append new enum value for the current ENUM64 type with:
2357 * - *name* - name of the enumerator value, can't be NULL or empty;
2358 * - *value* - integer value corresponding to enum value *name*;
2359 * Returns:
2360 * - 0, on success;
2361 * - <0, on error.
2362 */
2363int btf__add_enum64_value(struct btf *btf, const char *name, __u64 value)
2364{
2365 struct btf_enum64 *v;
2366 struct btf_type *t;
2367 int sz, name_off;
2368
2369 /* last type should be BTF_KIND_ENUM64 */
2370 if (btf->nr_types == 0)
2371 return libbpf_err(-EINVAL);
2372 t = btf_last_type(btf);
2373 if (!btf_is_enum64(t))
2374 return libbpf_err(-EINVAL);
2375
2376 /* non-empty name */
2377 if (!name || !name[0])
2378 return libbpf_err(-EINVAL);
2379
2380 /* decompose and invalidate raw data */
2381 if (btf_ensure_modifiable(btf))
2382 return libbpf_err(-ENOMEM);
2383
2384 sz = sizeof(struct btf_enum64);
2385 v = btf_add_type_mem(btf, sz);
2386 if (!v)
2387 return libbpf_err(-ENOMEM);
2388
2389 name_off = btf__add_str(btf, name);
2390 if (name_off < 0)
2391 return name_off;
2392
2393 v->name_off = name_off;
2394 v->val_lo32 = (__u32)value;
2395 v->val_hi32 = value >> 32;
2396
2397 /* update parent type's vlen */
2398 t = btf_last_type(btf);
2399 btf_type_inc_vlen(t);
2400
2401 btf->hdr->type_len += sz;
2402 btf->hdr->str_off += sz;
2403 return 0;
2404}
2405
2406/*
2407 * Append new BTF_KIND_FWD type with:
2408 * - *name*, non-empty/non-NULL name;
2409 * - *fwd_kind*, kind of forward declaration, one of BTF_FWD_STRUCT,
2410 * BTF_FWD_UNION, or BTF_FWD_ENUM;
2411 * Returns:
2412 * - >0, type ID of newly added BTF type;
2413 * - <0, on error.
2414 */
2415int btf__add_fwd(struct btf *btf, const char *name, enum btf_fwd_kind fwd_kind)
2416{
2417 if (!name || !name[0])
2418 return libbpf_err(-EINVAL);
2419
2420 switch (fwd_kind) {
2421 case BTF_FWD_STRUCT:
2422 case BTF_FWD_UNION: {
2423 struct btf_type *t;
2424 int id;
2425
2426 id = btf_add_ref_kind(btf, BTF_KIND_FWD, name, 0);
2427 if (id <= 0)
2428 return id;
2429 t = btf_type_by_id(btf, id);
2430 t->info = btf_type_info(BTF_KIND_FWD, 0, fwd_kind == BTF_FWD_UNION);
2431 return id;
2432 }
2433 case BTF_FWD_ENUM:
2434 /* enum forward in BTF currently is just an enum with no enum
2435 * values; we also assume a standard 4-byte size for it
2436 */
2437 return btf__add_enum(btf, name, sizeof(int));
2438 default:
2439 return libbpf_err(-EINVAL);
2440 }
2441}
2442
2443/*
2444 * Append new BTF_KING_TYPEDEF type with:
2445 * - *name*, non-empty/non-NULL name;
2446 * - *ref_type_id* - referenced type ID, it might not exist yet;
2447 * Returns:
2448 * - >0, type ID of newly added BTF type;
2449 * - <0, on error.
2450 */
2451int btf__add_typedef(struct btf *btf, const char *name, int ref_type_id)
2452{
2453 if (!name || !name[0])
2454 return libbpf_err(-EINVAL);
2455
2456 return btf_add_ref_kind(btf, BTF_KIND_TYPEDEF, name, ref_type_id);
2457}
2458
2459/*
2460 * Append new BTF_KIND_VOLATILE type with:
2461 * - *ref_type_id* - referenced type ID, it might not exist yet;
2462 * Returns:
2463 * - >0, type ID of newly added BTF type;
2464 * - <0, on error.
2465 */
2466int btf__add_volatile(struct btf *btf, int ref_type_id)
2467{
2468 return btf_add_ref_kind(btf, BTF_KIND_VOLATILE, NULL, ref_type_id);
2469}
2470
2471/*
2472 * Append new BTF_KIND_CONST type with:
2473 * - *ref_type_id* - referenced type ID, it might not exist yet;
2474 * Returns:
2475 * - >0, type ID of newly added BTF type;
2476 * - <0, on error.
2477 */
2478int btf__add_const(struct btf *btf, int ref_type_id)
2479{
2480 return btf_add_ref_kind(btf, BTF_KIND_CONST, NULL, ref_type_id);
2481}
2482
2483/*
2484 * Append new BTF_KIND_RESTRICT type with:
2485 * - *ref_type_id* - referenced type ID, it might not exist yet;
2486 * Returns:
2487 * - >0, type ID of newly added BTF type;
2488 * - <0, on error.
2489 */
2490int btf__add_restrict(struct btf *btf, int ref_type_id)
2491{
2492 return btf_add_ref_kind(btf, BTF_KIND_RESTRICT, NULL, ref_type_id);
2493}
2494
2495/*
2496 * Append new BTF_KIND_TYPE_TAG type with:
2497 * - *value*, non-empty/non-NULL tag value;
2498 * - *ref_type_id* - referenced type ID, it might not exist yet;
2499 * Returns:
2500 * - >0, type ID of newly added BTF type;
2501 * - <0, on error.
2502 */
2503int btf__add_type_tag(struct btf *btf, const char *value, int ref_type_id)
2504{
2505 if (!value || !value[0])
2506 return libbpf_err(-EINVAL);
2507
2508 return btf_add_ref_kind(btf, BTF_KIND_TYPE_TAG, value, ref_type_id);
2509}
2510
2511/*
2512 * Append new BTF_KIND_FUNC type with:
2513 * - *name*, non-empty/non-NULL name;
2514 * - *proto_type_id* - FUNC_PROTO's type ID, it might not exist yet;
2515 * Returns:
2516 * - >0, type ID of newly added BTF type;
2517 * - <0, on error.
2518 */
2519int btf__add_func(struct btf *btf, const char *name,
2520 enum btf_func_linkage linkage, int proto_type_id)
2521{
2522 int id;
2523
2524 if (!name || !name[0])
2525 return libbpf_err(-EINVAL);
2526 if (linkage != BTF_FUNC_STATIC && linkage != BTF_FUNC_GLOBAL &&
2527 linkage != BTF_FUNC_EXTERN)
2528 return libbpf_err(-EINVAL);
2529
2530 id = btf_add_ref_kind(btf, BTF_KIND_FUNC, name, proto_type_id);
2531 if (id > 0) {
2532 struct btf_type *t = btf_type_by_id(btf, id);
2533
2534 t->info = btf_type_info(BTF_KIND_FUNC, linkage, 0);
2535 }
2536 return libbpf_err(id);
2537}
2538
2539/*
2540 * Append new BTF_KIND_FUNC_PROTO with:
2541 * - *ret_type_id* - type ID for return result of a function.
2542 *
2543 * Function prototype initially has no arguments, but they can be added by
2544 * btf__add_func_param() one by one, immediately after
2545 * btf__add_func_proto() succeeded.
2546 *
2547 * Returns:
2548 * - >0, type ID of newly added BTF type;
2549 * - <0, on error.
2550 */
2551int btf__add_func_proto(struct btf *btf, int ret_type_id)
2552{
2553 struct btf_type *t;
2554 int sz;
2555
2556 if (validate_type_id(ret_type_id))
2557 return libbpf_err(-EINVAL);
2558
2559 if (btf_ensure_modifiable(btf))
2560 return libbpf_err(-ENOMEM);
2561
2562 sz = sizeof(struct btf_type);
2563 t = btf_add_type_mem(btf, sz);
2564 if (!t)
2565 return libbpf_err(-ENOMEM);
2566
2567 /* start out with vlen=0; this will be adjusted when adding enum
2568 * values, if necessary
2569 */
2570 t->name_off = 0;
2571 t->info = btf_type_info(BTF_KIND_FUNC_PROTO, 0, 0);
2572 t->type = ret_type_id;
2573
2574 return btf_commit_type(btf, sz);
2575}
2576
2577/*
2578 * Append new function parameter for current FUNC_PROTO type with:
2579 * - *name* - parameter name, can be NULL or empty;
2580 * - *type_id* - type ID describing the type of the parameter.
2581 * Returns:
2582 * - 0, on success;
2583 * - <0, on error.
2584 */
2585int btf__add_func_param(struct btf *btf, const char *name, int type_id)
2586{
2587 struct btf_type *t;
2588 struct btf_param *p;
2589 int sz, name_off = 0;
2590
2591 if (validate_type_id(type_id))
2592 return libbpf_err(-EINVAL);
2593
2594 /* last type should be BTF_KIND_FUNC_PROTO */
2595 if (btf->nr_types == 0)
2596 return libbpf_err(-EINVAL);
2597 t = btf_last_type(btf);
2598 if (!btf_is_func_proto(t))
2599 return libbpf_err(-EINVAL);
2600
2601 /* decompose and invalidate raw data */
2602 if (btf_ensure_modifiable(btf))
2603 return libbpf_err(-ENOMEM);
2604
2605 sz = sizeof(struct btf_param);
2606 p = btf_add_type_mem(btf, sz);
2607 if (!p)
2608 return libbpf_err(-ENOMEM);
2609
2610 if (name && name[0]) {
2611 name_off = btf__add_str(btf, name);
2612 if (name_off < 0)
2613 return name_off;
2614 }
2615
2616 p->name_off = name_off;
2617 p->type = type_id;
2618
2619 /* update parent type's vlen */
2620 t = btf_last_type(btf);
2621 btf_type_inc_vlen(t);
2622
2623 btf->hdr->type_len += sz;
2624 btf->hdr->str_off += sz;
2625 return 0;
2626}
2627
2628/*
2629 * Append new BTF_KIND_VAR type with:
2630 * - *name* - non-empty/non-NULL name;
2631 * - *linkage* - variable linkage, one of BTF_VAR_STATIC,
2632 * BTF_VAR_GLOBAL_ALLOCATED, or BTF_VAR_GLOBAL_EXTERN;
2633 * - *type_id* - type ID of the type describing the type of the variable.
2634 * Returns:
2635 * - >0, type ID of newly added BTF type;
2636 * - <0, on error.
2637 */
2638int btf__add_var(struct btf *btf, const char *name, int linkage, int type_id)
2639{
2640 struct btf_type *t;
2641 struct btf_var *v;
2642 int sz, name_off;
2643
2644 /* non-empty name */
2645 if (!name || !name[0])
2646 return libbpf_err(-EINVAL);
2647 if (linkage != BTF_VAR_STATIC && linkage != BTF_VAR_GLOBAL_ALLOCATED &&
2648 linkage != BTF_VAR_GLOBAL_EXTERN)
2649 return libbpf_err(-EINVAL);
2650 if (validate_type_id(type_id))
2651 return libbpf_err(-EINVAL);
2652
2653 /* deconstruct BTF, if necessary, and invalidate raw_data */
2654 if (btf_ensure_modifiable(btf))
2655 return libbpf_err(-ENOMEM);
2656
2657 sz = sizeof(struct btf_type) + sizeof(struct btf_var);
2658 t = btf_add_type_mem(btf, sz);
2659 if (!t)
2660 return libbpf_err(-ENOMEM);
2661
2662 name_off = btf__add_str(btf, name);
2663 if (name_off < 0)
2664 return name_off;
2665
2666 t->name_off = name_off;
2667 t->info = btf_type_info(BTF_KIND_VAR, 0, 0);
2668 t->type = type_id;
2669
2670 v = btf_var(t);
2671 v->linkage = linkage;
2672
2673 return btf_commit_type(btf, sz);
2674}
2675
2676/*
2677 * Append new BTF_KIND_DATASEC type with:
2678 * - *name* - non-empty/non-NULL name;
2679 * - *byte_sz* - data section size, in bytes.
2680 *
2681 * Data section is initially empty. Variables info can be added with
2682 * btf__add_datasec_var_info() calls, after btf__add_datasec() succeeds.
2683 *
2684 * Returns:
2685 * - >0, type ID of newly added BTF type;
2686 * - <0, on error.
2687 */
2688int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz)
2689{
2690 struct btf_type *t;
2691 int sz, name_off;
2692
2693 /* non-empty name */
2694 if (!name || !name[0])
2695 return libbpf_err(-EINVAL);
2696
2697 if (btf_ensure_modifiable(btf))
2698 return libbpf_err(-ENOMEM);
2699
2700 sz = sizeof(struct btf_type);
2701 t = btf_add_type_mem(btf, sz);
2702 if (!t)
2703 return libbpf_err(-ENOMEM);
2704
2705 name_off = btf__add_str(btf, name);
2706 if (name_off < 0)
2707 return name_off;
2708
2709 /* start with vlen=0, which will be update as var_secinfos are added */
2710 t->name_off = name_off;
2711 t->info = btf_type_info(BTF_KIND_DATASEC, 0, 0);
2712 t->size = byte_sz;
2713
2714 return btf_commit_type(btf, sz);
2715}
2716
2717/*
2718 * Append new data section variable information entry for current DATASEC type:
2719 * - *var_type_id* - type ID, describing type of the variable;
2720 * - *offset* - variable offset within data section, in bytes;
2721 * - *byte_sz* - variable size, in bytes.
2722 *
2723 * Returns:
2724 * - 0, on success;
2725 * - <0, on error.
2726 */
2727int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __u32 byte_sz)
2728{
2729 struct btf_type *t;
2730 struct btf_var_secinfo *v;
2731 int sz;
2732
2733 /* last type should be BTF_KIND_DATASEC */
2734 if (btf->nr_types == 0)
2735 return libbpf_err(-EINVAL);
2736 t = btf_last_type(btf);
2737 if (!btf_is_datasec(t))
2738 return libbpf_err(-EINVAL);
2739
2740 if (validate_type_id(var_type_id))
2741 return libbpf_err(-EINVAL);
2742
2743 /* decompose and invalidate raw data */
2744 if (btf_ensure_modifiable(btf))
2745 return libbpf_err(-ENOMEM);
2746
2747 sz = sizeof(struct btf_var_secinfo);
2748 v = btf_add_type_mem(btf, sz);
2749 if (!v)
2750 return libbpf_err(-ENOMEM);
2751
2752 v->type = var_type_id;
2753 v->offset = offset;
2754 v->size = byte_sz;
2755
2756 /* update parent type's vlen */
2757 t = btf_last_type(btf);
2758 btf_type_inc_vlen(t);
2759
2760 btf->hdr->type_len += sz;
2761 btf->hdr->str_off += sz;
2762 return 0;
2763}
2764
2765/*
2766 * Append new BTF_KIND_DECL_TAG type with:
2767 * - *value* - non-empty/non-NULL string;
2768 * - *ref_type_id* - referenced type ID, it might not exist yet;
2769 * - *component_idx* - -1 for tagging reference type, otherwise struct/union
2770 * member or function argument index;
2771 * Returns:
2772 * - >0, type ID of newly added BTF type;
2773 * - <0, on error.
2774 */
2775int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
2776 int component_idx)
2777{
2778 struct btf_type *t;
2779 int sz, value_off;
2780
2781 if (!value || !value[0] || component_idx < -1)
2782 return libbpf_err(-EINVAL);
2783
2784 if (validate_type_id(ref_type_id))
2785 return libbpf_err(-EINVAL);
2786
2787 if (btf_ensure_modifiable(btf))
2788 return libbpf_err(-ENOMEM);
2789
2790 sz = sizeof(struct btf_type) + sizeof(struct btf_decl_tag);
2791 t = btf_add_type_mem(btf, sz);
2792 if (!t)
2793 return libbpf_err(-ENOMEM);
2794
2795 value_off = btf__add_str(btf, value);
2796 if (value_off < 0)
2797 return value_off;
2798
2799 t->name_off = value_off;
2800 t->info = btf_type_info(BTF_KIND_DECL_TAG, 0, false);
2801 t->type = ref_type_id;
2802 btf_decl_tag(t)->component_idx = component_idx;
2803
2804 return btf_commit_type(btf, sz);
2805}
2806
2807struct btf_ext_sec_setup_param {
2808 __u32 off;
2809 __u32 len;
2810 __u32 min_rec_size;
2811 struct btf_ext_info *ext_info;
2812 const char *desc;
2813};
2814
2815static int btf_ext_setup_info(struct btf_ext *btf_ext,
2816 struct btf_ext_sec_setup_param *ext_sec)
2817{
2818 const struct btf_ext_info_sec *sinfo;
2819 struct btf_ext_info *ext_info;
2820 __u32 info_left, record_size;
2821 size_t sec_cnt = 0;
2822 /* The start of the info sec (including the __u32 record_size). */
2823 void *info;
2824
2825 if (ext_sec->len == 0)
2826 return 0;
2827
2828 if (ext_sec->off & 0x03) {
2829 pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
2830 ext_sec->desc);
2831 return -EINVAL;
2832 }
2833
2834 info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;
2835 info_left = ext_sec->len;
2836
2837 if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {
2838 pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
2839 ext_sec->desc, ext_sec->off, ext_sec->len);
2840 return -EINVAL;
2841 }
2842
2843 /* At least a record size */
2844 if (info_left < sizeof(__u32)) {
2845 pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
2846 return -EINVAL;
2847 }
2848
2849 /* The record size needs to meet the minimum standard */
2850 record_size = *(__u32 *)info;
2851 if (record_size < ext_sec->min_rec_size ||
2852 record_size & 0x03) {
2853 pr_debug("%s section in .BTF.ext has invalid record size %u\n",
2854 ext_sec->desc, record_size);
2855 return -EINVAL;
2856 }
2857
2858 sinfo = info + sizeof(__u32);
2859 info_left -= sizeof(__u32);
2860
2861 /* If no records, return failure now so .BTF.ext won't be used. */
2862 if (!info_left) {
2863 pr_debug("%s section in .BTF.ext has no records", ext_sec->desc);
2864 return -EINVAL;
2865 }
2866
2867 while (info_left) {
2868 unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
2869 __u64 total_record_size;
2870 __u32 num_records;
2871
2872 if (info_left < sec_hdrlen) {
2873 pr_debug("%s section header is not found in .BTF.ext\n",
2874 ext_sec->desc);
2875 return -EINVAL;
2876 }
2877
2878 num_records = sinfo->num_info;
2879 if (num_records == 0) {
2880 pr_debug("%s section has incorrect num_records in .BTF.ext\n",
2881 ext_sec->desc);
2882 return -EINVAL;
2883 }
2884
2885 total_record_size = sec_hdrlen + (__u64)num_records * record_size;
2886 if (info_left < total_record_size) {
2887 pr_debug("%s section has incorrect num_records in .BTF.ext\n",
2888 ext_sec->desc);
2889 return -EINVAL;
2890 }
2891
2892 info_left -= total_record_size;
2893 sinfo = (void *)sinfo + total_record_size;
2894 sec_cnt++;
2895 }
2896
2897 ext_info = ext_sec->ext_info;
2898 ext_info->len = ext_sec->len - sizeof(__u32);
2899 ext_info->rec_size = record_size;
2900 ext_info->info = info + sizeof(__u32);
2901 ext_info->sec_cnt = sec_cnt;
2902
2903 return 0;
2904}
2905
2906static int btf_ext_setup_func_info(struct btf_ext *btf_ext)
2907{
2908 struct btf_ext_sec_setup_param param = {
2909 .off = btf_ext->hdr->func_info_off,
2910 .len = btf_ext->hdr->func_info_len,
2911 .min_rec_size = sizeof(struct bpf_func_info_min),
2912 .ext_info = &btf_ext->func_info,
2913 .desc = "func_info"
2914 };
2915
2916 return btf_ext_setup_info(btf_ext, ¶m);
2917}
2918
2919static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
2920{
2921 struct btf_ext_sec_setup_param param = {
2922 .off = btf_ext->hdr->line_info_off,
2923 .len = btf_ext->hdr->line_info_len,
2924 .min_rec_size = sizeof(struct bpf_line_info_min),
2925 .ext_info = &btf_ext->line_info,
2926 .desc = "line_info",
2927 };
2928
2929 return btf_ext_setup_info(btf_ext, ¶m);
2930}
2931
2932static int btf_ext_setup_core_relos(struct btf_ext *btf_ext)
2933{
2934 struct btf_ext_sec_setup_param param = {
2935 .off = btf_ext->hdr->core_relo_off,
2936 .len = btf_ext->hdr->core_relo_len,
2937 .min_rec_size = sizeof(struct bpf_core_relo),
2938 .ext_info = &btf_ext->core_relo_info,
2939 .desc = "core_relo",
2940 };
2941
2942 return btf_ext_setup_info(btf_ext, ¶m);
2943}
2944
2945static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
2946{
2947 const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
2948
2949 if (data_size < offsetofend(struct btf_ext_header, hdr_len) ||
2950 data_size < hdr->hdr_len) {
2951 pr_debug("BTF.ext header not found");
2952 return -EINVAL;
2953 }
2954
2955 if (hdr->magic == bswap_16(BTF_MAGIC)) {
2956 pr_warn("BTF.ext in non-native endianness is not supported\n");
2957 return -ENOTSUP;
2958 } else if (hdr->magic != BTF_MAGIC) {
2959 pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic);
2960 return -EINVAL;
2961 }
2962
2963 if (hdr->version != BTF_VERSION) {
2964 pr_debug("Unsupported BTF.ext version:%u\n", hdr->version);
2965 return -ENOTSUP;
2966 }
2967
2968 if (hdr->flags) {
2969 pr_debug("Unsupported BTF.ext flags:%x\n", hdr->flags);
2970 return -ENOTSUP;
2971 }
2972
2973 if (data_size == hdr->hdr_len) {
2974 pr_debug("BTF.ext has no data\n");
2975 return -EINVAL;
2976 }
2977
2978 return 0;
2979}
2980
2981void btf_ext__free(struct btf_ext *btf_ext)
2982{
2983 if (IS_ERR_OR_NULL(btf_ext))
2984 return;
2985 free(btf_ext->func_info.sec_idxs);
2986 free(btf_ext->line_info.sec_idxs);
2987 free(btf_ext->core_relo_info.sec_idxs);
2988 free(btf_ext->data);
2989 free(btf_ext);
2990}
2991
2992struct btf_ext *btf_ext__new(const __u8 *data, __u32 size)
2993{
2994 struct btf_ext *btf_ext;
2995 int err;
2996
2997 btf_ext = calloc(1, sizeof(struct btf_ext));
2998 if (!btf_ext)
2999 return libbpf_err_ptr(-ENOMEM);
3000
3001 btf_ext->data_size = size;
3002 btf_ext->data = malloc(size);
3003 if (!btf_ext->data) {
3004 err = -ENOMEM;
3005 goto done;
3006 }
3007 memcpy(btf_ext->data, data, size);
3008
3009 err = btf_ext_parse_hdr(btf_ext->data, size);
3010 if (err)
3011 goto done;
3012
3013 if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, line_info_len)) {
3014 err = -EINVAL;
3015 goto done;
3016 }
3017
3018 err = btf_ext_setup_func_info(btf_ext);
3019 if (err)
3020 goto done;
3021
3022 err = btf_ext_setup_line_info(btf_ext);
3023 if (err)
3024 goto done;
3025
3026 if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len))
3027 goto done; /* skip core relos parsing */
3028
3029 err = btf_ext_setup_core_relos(btf_ext);
3030 if (err)
3031 goto done;
3032
3033done:
3034 if (err) {
3035 btf_ext__free(btf_ext);
3036 return libbpf_err_ptr(err);
3037 }
3038
3039 return btf_ext;
3040}
3041
3042const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size)
3043{
3044 *size = btf_ext->data_size;
3045 return btf_ext->data;
3046}
3047
3048struct btf_dedup;
3049
3050static struct btf_dedup *btf_dedup_new(struct btf *btf, const struct btf_dedup_opts *opts);
3051static void btf_dedup_free(struct btf_dedup *d);
3052static int btf_dedup_prep(struct btf_dedup *d);
3053static int btf_dedup_strings(struct btf_dedup *d);
3054static int btf_dedup_prim_types(struct btf_dedup *d);
3055static int btf_dedup_struct_types(struct btf_dedup *d);
3056static int btf_dedup_ref_types(struct btf_dedup *d);
3057static int btf_dedup_resolve_fwds(struct btf_dedup *d);
3058static int btf_dedup_compact_types(struct btf_dedup *d);
3059static int btf_dedup_remap_types(struct btf_dedup *d);
3060
3061/*
3062 * Deduplicate BTF types and strings.
3063 *
3064 * BTF dedup algorithm takes as an input `struct btf` representing `.BTF` ELF
3065 * section with all BTF type descriptors and string data. It overwrites that
3066 * memory in-place with deduplicated types and strings without any loss of
3067 * information. If optional `struct btf_ext` representing '.BTF.ext' ELF section
3068 * is provided, all the strings referenced from .BTF.ext section are honored
3069 * and updated to point to the right offsets after deduplication.
3070 *
3071 * If function returns with error, type/string data might be garbled and should
3072 * be discarded.
3073 *
3074 * More verbose and detailed description of both problem btf_dedup is solving,
3075 * as well as solution could be found at:
3076 * https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
3077 *
3078 * Problem description and justification
3079 * =====================================
3080 *
3081 * BTF type information is typically emitted either as a result of conversion
3082 * from DWARF to BTF or directly by compiler. In both cases, each compilation
3083 * unit contains information about a subset of all the types that are used
3084 * in an application. These subsets are frequently overlapping and contain a lot
3085 * of duplicated information when later concatenated together into a single
3086 * binary. This algorithm ensures that each unique type is represented by single
3087 * BTF type descriptor, greatly reducing resulting size of BTF data.
3088 *
3089 * Compilation unit isolation and subsequent duplication of data is not the only
3090 * problem. The same type hierarchy (e.g., struct and all the type that struct
3091 * references) in different compilation units can be represented in BTF to
3092 * various degrees of completeness (or, rather, incompleteness) due to
3093 * struct/union forward declarations.
3094 *
3095 * Let's take a look at an example, that we'll use to better understand the
3096 * problem (and solution). Suppose we have two compilation units, each using
3097 * same `struct S`, but each of them having incomplete type information about
3098 * struct's fields:
3099 *
3100 * // CU #1:
3101 * struct S;
3102 * struct A {
3103 * int a;
3104 * struct A* self;
3105 * struct S* parent;
3106 * };
3107 * struct B;
3108 * struct S {
3109 * struct A* a_ptr;
3110 * struct B* b_ptr;
3111 * };
3112 *
3113 * // CU #2:
3114 * struct S;
3115 * struct A;
3116 * struct B {
3117 * int b;
3118 * struct B* self;
3119 * struct S* parent;
3120 * };
3121 * struct S {
3122 * struct A* a_ptr;
3123 * struct B* b_ptr;
3124 * };
3125 *
3126 * In case of CU #1, BTF data will know only that `struct B` exist (but no
3127 * more), but will know the complete type information about `struct A`. While
3128 * for CU #2, it will know full type information about `struct B`, but will
3129 * only know about forward declaration of `struct A` (in BTF terms, it will
3130 * have `BTF_KIND_FWD` type descriptor with name `B`).
3131 *
3132 * This compilation unit isolation means that it's possible that there is no
3133 * single CU with complete type information describing structs `S`, `A`, and
3134 * `B`. Also, we might get tons of duplicated and redundant type information.
3135 *
3136 * Additional complication we need to keep in mind comes from the fact that
3137 * types, in general, can form graphs containing cycles, not just DAGs.
3138 *
3139 * While algorithm does deduplication, it also merges and resolves type
3140 * information (unless disabled throught `struct btf_opts`), whenever possible.
3141 * E.g., in the example above with two compilation units having partial type
3142 * information for structs `A` and `B`, the output of algorithm will emit
3143 * a single copy of each BTF type that describes structs `A`, `B`, and `S`
3144 * (as well as type information for `int` and pointers), as if they were defined
3145 * in a single compilation unit as:
3146 *
3147 * struct A {
3148 * int a;
3149 * struct A* self;
3150 * struct S* parent;
3151 * };
3152 * struct B {
3153 * int b;
3154 * struct B* self;
3155 * struct S* parent;
3156 * };
3157 * struct S {
3158 * struct A* a_ptr;
3159 * struct B* b_ptr;
3160 * };
3161 *
3162 * Algorithm summary
3163 * =================
3164 *
3165 * Algorithm completes its work in 7 separate passes:
3166 *
3167 * 1. Strings deduplication.
3168 * 2. Primitive types deduplication (int, enum, fwd).
3169 * 3. Struct/union types deduplication.
3170 * 4. Resolve unambiguous forward declarations.
3171 * 5. Reference types deduplication (pointers, typedefs, arrays, funcs, func
3172 * protos, and const/volatile/restrict modifiers).
3173 * 6. Types compaction.
3174 * 7. Types remapping.
3175 *
3176 * Algorithm determines canonical type descriptor, which is a single
3177 * representative type for each truly unique type. This canonical type is the
3178 * one that will go into final deduplicated BTF type information. For
3179 * struct/unions, it is also the type that algorithm will merge additional type
3180 * information into (while resolving FWDs), as it discovers it from data in
3181 * other CUs. Each input BTF type eventually gets either mapped to itself, if
3182 * that type is canonical, or to some other type, if that type is equivalent
3183 * and was chosen as canonical representative. This mapping is stored in
3184 * `btf_dedup->map` array. This map is also used to record STRUCT/UNION that
3185 * FWD type got resolved to.
3186 *
3187 * To facilitate fast discovery of canonical types, we also maintain canonical
3188 * index (`btf_dedup->dedup_table`), which maps type descriptor's signature hash
3189 * (i.e., hashed kind, name, size, fields, etc) into a list of canonical types
3190 * that match that signature. With sufficiently good choice of type signature
3191 * hashing function, we can limit number of canonical types for each unique type
3192 * signature to a very small number, allowing to find canonical type for any
3193 * duplicated type very quickly.
3194 *
3195 * Struct/union deduplication is the most critical part and algorithm for
3196 * deduplicating structs/unions is described in greater details in comments for
3197 * `btf_dedup_is_equiv` function.
3198 */
3199int btf__dedup(struct btf *btf, const struct btf_dedup_opts *opts)
3200{
3201 struct btf_dedup *d;
3202 int err;
3203
3204 if (!OPTS_VALID(opts, btf_dedup_opts))
3205 return libbpf_err(-EINVAL);
3206
3207 d = btf_dedup_new(btf, opts);
3208 if (IS_ERR(d)) {
3209 pr_debug("btf_dedup_new failed: %ld", PTR_ERR(d));
3210 return libbpf_err(-EINVAL);
3211 }
3212
3213 if (btf_ensure_modifiable(btf)) {
3214 err = -ENOMEM;
3215 goto done;
3216 }
3217
3218 err = btf_dedup_prep(d);
3219 if (err) {
3220 pr_debug("btf_dedup_prep failed:%d\n", err);
3221 goto done;
3222 }
3223 err = btf_dedup_strings(d);
3224 if (err < 0) {
3225 pr_debug("btf_dedup_strings failed:%d\n", err);
3226 goto done;
3227 }
3228 err = btf_dedup_prim_types(d);
3229 if (err < 0) {
3230 pr_debug("btf_dedup_prim_types failed:%d\n", err);
3231 goto done;
3232 }
3233 err = btf_dedup_struct_types(d);
3234 if (err < 0) {
3235 pr_debug("btf_dedup_struct_types failed:%d\n", err);
3236 goto done;
3237 }
3238 err = btf_dedup_resolve_fwds(d);
3239 if (err < 0) {
3240 pr_debug("btf_dedup_resolve_fwds failed:%d\n", err);
3241 goto done;
3242 }
3243 err = btf_dedup_ref_types(d);
3244 if (err < 0) {
3245 pr_debug("btf_dedup_ref_types failed:%d\n", err);
3246 goto done;
3247 }
3248 err = btf_dedup_compact_types(d);
3249 if (err < 0) {
3250 pr_debug("btf_dedup_compact_types failed:%d\n", err);
3251 goto done;
3252 }
3253 err = btf_dedup_remap_types(d);
3254 if (err < 0) {
3255 pr_debug("btf_dedup_remap_types failed:%d\n", err);
3256 goto done;
3257 }
3258
3259done:
3260 btf_dedup_free(d);
3261 return libbpf_err(err);
3262}
3263
3264#define BTF_UNPROCESSED_ID ((__u32)-1)
3265#define BTF_IN_PROGRESS_ID ((__u32)-2)
3266
3267struct btf_dedup {
3268 /* .BTF section to be deduped in-place */
3269 struct btf *btf;
3270 /*
3271 * Optional .BTF.ext section. When provided, any strings referenced
3272 * from it will be taken into account when deduping strings
3273 */
3274 struct btf_ext *btf_ext;
3275 /*
3276 * This is a map from any type's signature hash to a list of possible
3277 * canonical representative type candidates. Hash collisions are
3278 * ignored, so even types of various kinds can share same list of
3279 * candidates, which is fine because we rely on subsequent
3280 * btf_xxx_equal() checks to authoritatively verify type equality.
3281 */
3282 struct hashmap *dedup_table;
3283 /* Canonical types map */
3284 __u32 *map;
3285 /* Hypothetical mapping, used during type graph equivalence checks */
3286 __u32 *hypot_map;
3287 __u32 *hypot_list;
3288 size_t hypot_cnt;
3289 size_t hypot_cap;
3290 /* Whether hypothetical mapping, if successful, would need to adjust
3291 * already canonicalized types (due to a new forward declaration to
3292 * concrete type resolution). In such case, during split BTF dedup
3293 * candidate type would still be considered as different, because base
3294 * BTF is considered to be immutable.
3295 */
3296 bool hypot_adjust_canon;
3297 /* Various option modifying behavior of algorithm */
3298 struct btf_dedup_opts opts;
3299 /* temporary strings deduplication state */
3300 struct strset *strs_set;
3301};
3302
3303static long hash_combine(long h, long value)
3304{
3305 return h * 31 + value;
3306}
3307
3308#define for_each_dedup_cand(d, node, hash) \
3309 hashmap__for_each_key_entry(d->dedup_table, node, hash)
3310
3311static int btf_dedup_table_add(struct btf_dedup *d, long hash, __u32 type_id)
3312{
3313 return hashmap__append(d->dedup_table, hash, type_id);
3314}
3315
3316static int btf_dedup_hypot_map_add(struct btf_dedup *d,
3317 __u32 from_id, __u32 to_id)
3318{
3319 if (d->hypot_cnt == d->hypot_cap) {
3320 __u32 *new_list;
3321
3322 d->hypot_cap += max((size_t)16, d->hypot_cap / 2);
3323 new_list = libbpf_reallocarray(d->hypot_list, d->hypot_cap, sizeof(__u32));
3324 if (!new_list)
3325 return -ENOMEM;
3326 d->hypot_list = new_list;
3327 }
3328 d->hypot_list[d->hypot_cnt++] = from_id;
3329 d->hypot_map[from_id] = to_id;
3330 return 0;
3331}
3332
3333static void btf_dedup_clear_hypot_map(struct btf_dedup *d)
3334{
3335 int i;
3336
3337 for (i = 0; i < d->hypot_cnt; i++)
3338 d->hypot_map[d->hypot_list[i]] = BTF_UNPROCESSED_ID;
3339 d->hypot_cnt = 0;
3340 d->hypot_adjust_canon = false;
3341}
3342
3343static void btf_dedup_free(struct btf_dedup *d)
3344{
3345 hashmap__free(d->dedup_table);
3346 d->dedup_table = NULL;
3347
3348 free(d->map);
3349 d->map = NULL;
3350
3351 free(d->hypot_map);
3352 d->hypot_map = NULL;
3353
3354 free(d->hypot_list);
3355 d->hypot_list = NULL;
3356
3357 free(d);
3358}
3359
3360static size_t btf_dedup_identity_hash_fn(long key, void *ctx)
3361{
3362 return key;
3363}
3364
3365static size_t btf_dedup_collision_hash_fn(long key, void *ctx)
3366{
3367 return 0;
3368}
3369
3370static bool btf_dedup_equal_fn(long k1, long k2, void *ctx)
3371{
3372 return k1 == k2;
3373}
3374
3375static struct btf_dedup *btf_dedup_new(struct btf *btf, const struct btf_dedup_opts *opts)
3376{
3377 struct btf_dedup *d = calloc(1, sizeof(struct btf_dedup));
3378 hashmap_hash_fn hash_fn = btf_dedup_identity_hash_fn;
3379 int i, err = 0, type_cnt;
3380
3381 if (!d)
3382 return ERR_PTR(-ENOMEM);
3383
3384 if (OPTS_GET(opts, force_collisions, false))
3385 hash_fn = btf_dedup_collision_hash_fn;
3386
3387 d->btf = btf;
3388 d->btf_ext = OPTS_GET(opts, btf_ext, NULL);
3389
3390 d->dedup_table = hashmap__new(hash_fn, btf_dedup_equal_fn, NULL);
3391 if (IS_ERR(d->dedup_table)) {
3392 err = PTR_ERR(d->dedup_table);
3393 d->dedup_table = NULL;
3394 goto done;
3395 }
3396
3397 type_cnt = btf__type_cnt(btf);
3398 d->map = malloc(sizeof(__u32) * type_cnt);
3399 if (!d->map) {
3400 err = -ENOMEM;
3401 goto done;
3402 }
3403 /* special BTF "void" type is made canonical immediately */
3404 d->map[0] = 0;
3405 for (i = 1; i < type_cnt; i++) {
3406 struct btf_type *t = btf_type_by_id(d->btf, i);
3407
3408 /* VAR and DATASEC are never deduped and are self-canonical */
3409 if (btf_is_var(t) || btf_is_datasec(t))
3410 d->map[i] = i;
3411 else
3412 d->map[i] = BTF_UNPROCESSED_ID;
3413 }
3414
3415 d->hypot_map = malloc(sizeof(__u32) * type_cnt);
3416 if (!d->hypot_map) {
3417 err = -ENOMEM;
3418 goto done;
3419 }
3420 for (i = 0; i < type_cnt; i++)
3421 d->hypot_map[i] = BTF_UNPROCESSED_ID;
3422
3423done:
3424 if (err) {
3425 btf_dedup_free(d);
3426 return ERR_PTR(err);
3427 }
3428
3429 return d;
3430}
3431
3432/*
3433 * Iterate over all possible places in .BTF and .BTF.ext that can reference
3434 * string and pass pointer to it to a provided callback `fn`.
3435 */
3436static int btf_for_each_str_off(struct btf_dedup *d, str_off_visit_fn fn, void *ctx)
3437{
3438 int i, r;
3439
3440 for (i = 0; i < d->btf->nr_types; i++) {
3441 struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
3442
3443 r = btf_type_visit_str_offs(t, fn, ctx);
3444 if (r)
3445 return r;
3446 }
3447
3448 if (!d->btf_ext)
3449 return 0;
3450
3451 r = btf_ext_visit_str_offs(d->btf_ext, fn, ctx);
3452 if (r)
3453 return r;
3454
3455 return 0;
3456}
3457
3458static int strs_dedup_remap_str_off(__u32 *str_off_ptr, void *ctx)
3459{
3460 struct btf_dedup *d = ctx;
3461 __u32 str_off = *str_off_ptr;
3462 const char *s;
3463 int off, err;
3464
3465 /* don't touch empty string or string in main BTF */
3466 if (str_off == 0 || str_off < d->btf->start_str_off)
3467 return 0;
3468
3469 s = btf__str_by_offset(d->btf, str_off);
3470 if (d->btf->base_btf) {
3471 err = btf__find_str(d->btf->base_btf, s);
3472 if (err >= 0) {
3473 *str_off_ptr = err;
3474 return 0;
3475 }
3476 if (err != -ENOENT)
3477 return err;
3478 }
3479
3480 off = strset__add_str(d->strs_set, s);
3481 if (off < 0)
3482 return off;
3483
3484 *str_off_ptr = d->btf->start_str_off + off;
3485 return 0;
3486}
3487
3488/*
3489 * Dedup string and filter out those that are not referenced from either .BTF
3490 * or .BTF.ext (if provided) sections.
3491 *
3492 * This is done by building index of all strings in BTF's string section,
3493 * then iterating over all entities that can reference strings (e.g., type
3494 * names, struct field names, .BTF.ext line info, etc) and marking corresponding
3495 * strings as used. After that all used strings are deduped and compacted into
3496 * sequential blob of memory and new offsets are calculated. Then all the string
3497 * references are iterated again and rewritten using new offsets.
3498 */
3499static int btf_dedup_strings(struct btf_dedup *d)
3500{
3501 int err;
3502
3503 if (d->btf->strs_deduped)
3504 return 0;
3505
3506 d->strs_set = strset__new(BTF_MAX_STR_OFFSET, NULL, 0);
3507 if (IS_ERR(d->strs_set)) {
3508 err = PTR_ERR(d->strs_set);
3509 goto err_out;
3510 }
3511
3512 if (!d->btf->base_btf) {
3513 /* insert empty string; we won't be looking it up during strings
3514 * dedup, but it's good to have it for generic BTF string lookups
3515 */
3516 err = strset__add_str(d->strs_set, "");
3517 if (err < 0)
3518 goto err_out;
3519 }
3520
3521 /* remap string offsets */
3522 err = btf_for_each_str_off(d, strs_dedup_remap_str_off, d);
3523 if (err)
3524 goto err_out;
3525
3526 /* replace BTF string data and hash with deduped ones */
3527 strset__free(d->btf->strs_set);
3528 d->btf->hdr->str_len = strset__data_size(d->strs_set);
3529 d->btf->strs_set = d->strs_set;
3530 d->strs_set = NULL;
3531 d->btf->strs_deduped = true;
3532 return 0;
3533
3534err_out:
3535 strset__free(d->strs_set);
3536 d->strs_set = NULL;
3537
3538 return err;
3539}
3540
3541static long btf_hash_common(struct btf_type *t)
3542{
3543 long h;
3544
3545 h = hash_combine(0, t->name_off);
3546 h = hash_combine(h, t->info);
3547 h = hash_combine(h, t->size);
3548 return h;
3549}
3550
3551static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
3552{
3553 return t1->name_off == t2->name_off &&
3554 t1->info == t2->info &&
3555 t1->size == t2->size;
3556}
3557
3558/* Calculate type signature hash of INT or TAG. */
3559static long btf_hash_int_decl_tag(struct btf_type *t)
3560{
3561 __u32 info = *(__u32 *)(t + 1);
3562 long h;
3563
3564 h = btf_hash_common(t);
3565 h = hash_combine(h, info);
3566 return h;
3567}
3568
3569/* Check structural equality of two INTs or TAGs. */
3570static bool btf_equal_int_tag(struct btf_type *t1, struct btf_type *t2)
3571{
3572 __u32 info1, info2;
3573
3574 if (!btf_equal_common(t1, t2))
3575 return false;
3576 info1 = *(__u32 *)(t1 + 1);
3577 info2 = *(__u32 *)(t2 + 1);
3578 return info1 == info2;
3579}
3580
3581/* Calculate type signature hash of ENUM/ENUM64. */
3582static long btf_hash_enum(struct btf_type *t)
3583{
3584 long h;
3585
3586 /* don't hash vlen, enum members and size to support enum fwd resolving */
3587 h = hash_combine(0, t->name_off);
3588 return h;
3589}
3590
3591static bool btf_equal_enum_members(struct btf_type *t1, struct btf_type *t2)
3592{
3593 const struct btf_enum *m1, *m2;
3594 __u16 vlen;
3595 int i;
3596
3597 vlen = btf_vlen(t1);
3598 m1 = btf_enum(t1);
3599 m2 = btf_enum(t2);
3600 for (i = 0; i < vlen; i++) {
3601 if (m1->name_off != m2->name_off || m1->val != m2->val)
3602 return false;
3603 m1++;
3604 m2++;
3605 }
3606 return true;
3607}
3608
3609static bool btf_equal_enum64_members(struct btf_type *t1, struct btf_type *t2)
3610{
3611 const struct btf_enum64 *m1, *m2;
3612 __u16 vlen;
3613 int i;
3614
3615 vlen = btf_vlen(t1);
3616 m1 = btf_enum64(t1);
3617 m2 = btf_enum64(t2);
3618 for (i = 0; i < vlen; i++) {
3619 if (m1->name_off != m2->name_off || m1->val_lo32 != m2->val_lo32 ||
3620 m1->val_hi32 != m2->val_hi32)
3621 return false;
3622 m1++;
3623 m2++;
3624 }
3625 return true;
3626}
3627
3628/* Check structural equality of two ENUMs or ENUM64s. */
3629static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
3630{
3631 if (!btf_equal_common(t1, t2))
3632 return false;
3633
3634 /* t1 & t2 kinds are identical because of btf_equal_common */
3635 if (btf_kind(t1) == BTF_KIND_ENUM)
3636 return btf_equal_enum_members(t1, t2);
3637 else
3638 return btf_equal_enum64_members(t1, t2);
3639}
3640
3641static inline bool btf_is_enum_fwd(struct btf_type *t)
3642{
3643 return btf_is_any_enum(t) && btf_vlen(t) == 0;
3644}
3645
3646static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
3647{
3648 if (!btf_is_enum_fwd(t1) && !btf_is_enum_fwd(t2))
3649 return btf_equal_enum(t1, t2);
3650 /* At this point either t1 or t2 or both are forward declarations, thus:
3651 * - skip comparing vlen because it is zero for forward declarations;
3652 * - skip comparing size to allow enum forward declarations
3653 * to be compatible with enum64 full declarations;
3654 * - skip comparing kind for the same reason.
3655 */
3656 return t1->name_off == t2->name_off &&
3657 btf_is_any_enum(t1) && btf_is_any_enum(t2);
3658}
3659
3660/*
3661 * Calculate type signature hash of STRUCT/UNION, ignoring referenced type IDs,
3662 * as referenced type IDs equivalence is established separately during type
3663 * graph equivalence check algorithm.
3664 */
3665static long btf_hash_struct(struct btf_type *t)
3666{
3667 const struct btf_member *member = btf_members(t);
3668 __u32 vlen = btf_vlen(t);
3669 long h = btf_hash_common(t);
3670 int i;
3671
3672 for (i = 0; i < vlen; i++) {
3673 h = hash_combine(h, member->name_off);
3674 h = hash_combine(h, member->offset);
3675 /* no hashing of referenced type ID, it can be unresolved yet */
3676 member++;
3677 }
3678 return h;
3679}
3680
3681/*
3682 * Check structural compatibility of two STRUCTs/UNIONs, ignoring referenced
3683 * type IDs. This check is performed during type graph equivalence check and
3684 * referenced types equivalence is checked separately.
3685 */
3686static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
3687{
3688 const struct btf_member *m1, *m2;
3689 __u16 vlen;
3690 int i;
3691
3692 if (!btf_equal_common(t1, t2))
3693 return false;
3694
3695 vlen = btf_vlen(t1);
3696 m1 = btf_members(t1);
3697 m2 = btf_members(t2);
3698 for (i = 0; i < vlen; i++) {
3699 if (m1->name_off != m2->name_off || m1->offset != m2->offset)
3700 return false;
3701 m1++;
3702 m2++;
3703 }
3704 return true;
3705}
3706
3707/*
3708 * Calculate type signature hash of ARRAY, including referenced type IDs,
3709 * under assumption that they were already resolved to canonical type IDs and
3710 * are not going to change.
3711 */
3712static long btf_hash_array(struct btf_type *t)
3713{
3714 const struct btf_array *info = btf_array(t);
3715 long h = btf_hash_common(t);
3716
3717 h = hash_combine(h, info->type);
3718 h = hash_combine(h, info->index_type);
3719 h = hash_combine(h, info->nelems);
3720 return h;
3721}
3722
3723/*
3724 * Check exact equality of two ARRAYs, taking into account referenced
3725 * type IDs, under assumption that they were already resolved to canonical
3726 * type IDs and are not going to change.
3727 * This function is called during reference types deduplication to compare
3728 * ARRAY to potential canonical representative.
3729 */
3730static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
3731{
3732 const struct btf_array *info1, *info2;
3733
3734 if (!btf_equal_common(t1, t2))
3735 return false;
3736
3737 info1 = btf_array(t1);
3738 info2 = btf_array(t2);
3739 return info1->type == info2->type &&
3740 info1->index_type == info2->index_type &&
3741 info1->nelems == info2->nelems;
3742}
3743
3744/*
3745 * Check structural compatibility of two ARRAYs, ignoring referenced type
3746 * IDs. This check is performed during type graph equivalence check and
3747 * referenced types equivalence is checked separately.
3748 */
3749static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
3750{
3751 if (!btf_equal_common(t1, t2))
3752 return false;
3753
3754 return btf_array(t1)->nelems == btf_array(t2)->nelems;
3755}
3756
3757/*
3758 * Calculate type signature hash of FUNC_PROTO, including referenced type IDs,
3759 * under assumption that they were already resolved to canonical type IDs and
3760 * are not going to change.
3761 */
3762static long btf_hash_fnproto(struct btf_type *t)
3763{
3764 const struct btf_param *member = btf_params(t);
3765 __u16 vlen = btf_vlen(t);
3766 long h = btf_hash_common(t);
3767 int i;
3768
3769 for (i = 0; i < vlen; i++) {
3770 h = hash_combine(h, member->name_off);
3771 h = hash_combine(h, member->type);
3772 member++;
3773 }
3774 return h;
3775}
3776
3777/*
3778 * Check exact equality of two FUNC_PROTOs, taking into account referenced
3779 * type IDs, under assumption that they were already resolved to canonical
3780 * type IDs and are not going to change.
3781 * This function is called during reference types deduplication to compare
3782 * FUNC_PROTO to potential canonical representative.
3783 */
3784static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
3785{
3786 const struct btf_param *m1, *m2;
3787 __u16 vlen;
3788 int i;
3789
3790 if (!btf_equal_common(t1, t2))
3791 return false;
3792
3793 vlen = btf_vlen(t1);
3794 m1 = btf_params(t1);
3795 m2 = btf_params(t2);
3796 for (i = 0; i < vlen; i++) {
3797 if (m1->name_off != m2->name_off || m1->type != m2->type)
3798 return false;
3799 m1++;
3800 m2++;
3801 }
3802 return true;
3803}
3804
3805/*
3806 * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
3807 * IDs. This check is performed during type graph equivalence check and
3808 * referenced types equivalence is checked separately.
3809 */
3810static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
3811{
3812 const struct btf_param *m1, *m2;
3813 __u16 vlen;
3814 int i;
3815
3816 /* skip return type ID */
3817 if (t1->name_off != t2->name_off || t1->info != t2->info)
3818 return false;
3819
3820 vlen = btf_vlen(t1);
3821 m1 = btf_params(t1);
3822 m2 = btf_params(t2);
3823 for (i = 0; i < vlen; i++) {
3824 if (m1->name_off != m2->name_off)
3825 return false;
3826 m1++;
3827 m2++;
3828 }
3829 return true;
3830}
3831
3832/* Prepare split BTF for deduplication by calculating hashes of base BTF's
3833 * types and initializing the rest of the state (canonical type mapping) for
3834 * the fixed base BTF part.
3835 */
3836static int btf_dedup_prep(struct btf_dedup *d)
3837{
3838 struct btf_type *t;
3839 int type_id;
3840 long h;
3841
3842 if (!d->btf->base_btf)
3843 return 0;
3844
3845 for (type_id = 1; type_id < d->btf->start_id; type_id++) {
3846 t = btf_type_by_id(d->btf, type_id);
3847
3848 /* all base BTF types are self-canonical by definition */
3849 d->map[type_id] = type_id;
3850
3851 switch (btf_kind(t)) {
3852 case BTF_KIND_VAR:
3853 case BTF_KIND_DATASEC:
3854 /* VAR and DATASEC are never hash/deduplicated */
3855 continue;
3856 case BTF_KIND_CONST:
3857 case BTF_KIND_VOLATILE:
3858 case BTF_KIND_RESTRICT:
3859 case BTF_KIND_PTR:
3860 case BTF_KIND_FWD:
3861 case BTF_KIND_TYPEDEF:
3862 case BTF_KIND_FUNC:
3863 case BTF_KIND_FLOAT:
3864 case BTF_KIND_TYPE_TAG:
3865 h = btf_hash_common(t);
3866 break;
3867 case BTF_KIND_INT:
3868 case BTF_KIND_DECL_TAG:
3869 h = btf_hash_int_decl_tag(t);
3870 break;
3871 case BTF_KIND_ENUM:
3872 case BTF_KIND_ENUM64:
3873 h = btf_hash_enum(t);
3874 break;
3875 case BTF_KIND_STRUCT:
3876 case BTF_KIND_UNION:
3877 h = btf_hash_struct(t);
3878 break;
3879 case BTF_KIND_ARRAY:
3880 h = btf_hash_array(t);
3881 break;
3882 case BTF_KIND_FUNC_PROTO:
3883 h = btf_hash_fnproto(t);
3884 break;
3885 default:
3886 pr_debug("unknown kind %d for type [%d]\n", btf_kind(t), type_id);
3887 return -EINVAL;
3888 }
3889 if (btf_dedup_table_add(d, h, type_id))
3890 return -ENOMEM;
3891 }
3892
3893 return 0;
3894}
3895
3896/*
3897 * Deduplicate primitive types, that can't reference other types, by calculating
3898 * their type signature hash and comparing them with any possible canonical
3899 * candidate. If no canonical candidate matches, type itself is marked as
3900 * canonical and is added into `btf_dedup->dedup_table` as another candidate.
3901 */
3902static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
3903{
3904 struct btf_type *t = btf_type_by_id(d->btf, type_id);
3905 struct hashmap_entry *hash_entry;
3906 struct btf_type *cand;
3907 /* if we don't find equivalent type, then we are canonical */
3908 __u32 new_id = type_id;
3909 __u32 cand_id;
3910 long h;
3911
3912 switch (btf_kind(t)) {
3913 case BTF_KIND_CONST:
3914 case BTF_KIND_VOLATILE:
3915 case BTF_KIND_RESTRICT:
3916 case BTF_KIND_PTR:
3917 case BTF_KIND_TYPEDEF:
3918 case BTF_KIND_ARRAY:
3919 case BTF_KIND_STRUCT:
3920 case BTF_KIND_UNION:
3921 case BTF_KIND_FUNC:
3922 case BTF_KIND_FUNC_PROTO:
3923 case BTF_KIND_VAR:
3924 case BTF_KIND_DATASEC:
3925 case BTF_KIND_DECL_TAG:
3926 case BTF_KIND_TYPE_TAG:
3927 return 0;
3928
3929 case BTF_KIND_INT:
3930 h = btf_hash_int_decl_tag(t);
3931 for_each_dedup_cand(d, hash_entry, h) {
3932 cand_id = hash_entry->value;
3933 cand = btf_type_by_id(d->btf, cand_id);
3934 if (btf_equal_int_tag(t, cand)) {
3935 new_id = cand_id;
3936 break;
3937 }
3938 }
3939 break;
3940
3941 case BTF_KIND_ENUM:
3942 case BTF_KIND_ENUM64:
3943 h = btf_hash_enum(t);
3944 for_each_dedup_cand(d, hash_entry, h) {
3945 cand_id = hash_entry->value;
3946 cand = btf_type_by_id(d->btf, cand_id);
3947 if (btf_equal_enum(t, cand)) {
3948 new_id = cand_id;
3949 break;
3950 }
3951 if (btf_compat_enum(t, cand)) {
3952 if (btf_is_enum_fwd(t)) {
3953 /* resolve fwd to full enum */
3954 new_id = cand_id;
3955 break;
3956 }
3957 /* resolve canonical enum fwd to full enum */
3958 d->map[cand_id] = type_id;
3959 }
3960 }
3961 break;
3962
3963 case BTF_KIND_FWD:
3964 case BTF_KIND_FLOAT:
3965 h = btf_hash_common(t);
3966 for_each_dedup_cand(d, hash_entry, h) {
3967 cand_id = hash_entry->value;
3968 cand = btf_type_by_id(d->btf, cand_id);
3969 if (btf_equal_common(t, cand)) {
3970 new_id = cand_id;
3971 break;
3972 }
3973 }
3974 break;
3975
3976 default:
3977 return -EINVAL;
3978 }
3979
3980 d->map[type_id] = new_id;
3981 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
3982 return -ENOMEM;
3983
3984 return 0;
3985}
3986
3987static int btf_dedup_prim_types(struct btf_dedup *d)
3988{
3989 int i, err;
3990
3991 for (i = 0; i < d->btf->nr_types; i++) {
3992 err = btf_dedup_prim_type(d, d->btf->start_id + i);
3993 if (err)
3994 return err;
3995 }
3996 return 0;
3997}
3998
3999/*
4000 * Check whether type is already mapped into canonical one (could be to itself).
4001 */
4002static inline bool is_type_mapped(struct btf_dedup *d, uint32_t type_id)
4003{
4004 return d->map[type_id] <= BTF_MAX_NR_TYPES;
4005}
4006
4007/*
4008 * Resolve type ID into its canonical type ID, if any; otherwise return original
4009 * type ID. If type is FWD and is resolved into STRUCT/UNION already, follow
4010 * STRUCT/UNION link and resolve it into canonical type ID as well.
4011 */
4012static inline __u32 resolve_type_id(struct btf_dedup *d, __u32 type_id)
4013{
4014 while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
4015 type_id = d->map[type_id];
4016 return type_id;
4017}
4018
4019/*
4020 * Resolve FWD to underlying STRUCT/UNION, if any; otherwise return original
4021 * type ID.
4022 */
4023static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
4024{
4025 __u32 orig_type_id = type_id;
4026
4027 if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
4028 return type_id;
4029
4030 while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
4031 type_id = d->map[type_id];
4032
4033 if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
4034 return type_id;
4035
4036 return orig_type_id;
4037}
4038
4039
4040static inline __u16 btf_fwd_kind(struct btf_type *t)
4041{
4042 return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
4043}
4044
4045/* Check if given two types are identical ARRAY definitions */
4046static bool btf_dedup_identical_arrays(struct btf_dedup *d, __u32 id1, __u32 id2)
4047{
4048 struct btf_type *t1, *t2;
4049
4050 t1 = btf_type_by_id(d->btf, id1);
4051 t2 = btf_type_by_id(d->btf, id2);
4052 if (!btf_is_array(t1) || !btf_is_array(t2))
4053 return false;
4054
4055 return btf_equal_array(t1, t2);
4056}
4057
4058/* Check if given two types are identical STRUCT/UNION definitions */
4059static bool btf_dedup_identical_structs(struct btf_dedup *d, __u32 id1, __u32 id2)
4060{
4061 const struct btf_member *m1, *m2;
4062 struct btf_type *t1, *t2;
4063 int n, i;
4064
4065 t1 = btf_type_by_id(d->btf, id1);
4066 t2 = btf_type_by_id(d->btf, id2);
4067
4068 if (!btf_is_composite(t1) || btf_kind(t1) != btf_kind(t2))
4069 return false;
4070
4071 if (!btf_shallow_equal_struct(t1, t2))
4072 return false;
4073
4074 m1 = btf_members(t1);
4075 m2 = btf_members(t2);
4076 for (i = 0, n = btf_vlen(t1); i < n; i++, m1++, m2++) {
4077 if (m1->type != m2->type &&
4078 !btf_dedup_identical_arrays(d, m1->type, m2->type) &&
4079 !btf_dedup_identical_structs(d, m1->type, m2->type))
4080 return false;
4081 }
4082 return true;
4083}
4084
4085/*
4086 * Check equivalence of BTF type graph formed by candidate struct/union (we'll
4087 * call it "candidate graph" in this description for brevity) to a type graph
4088 * formed by (potential) canonical struct/union ("canonical graph" for brevity
4089 * here, though keep in mind that not all types in canonical graph are
4090 * necessarily canonical representatives themselves, some of them might be
4091 * duplicates or its uniqueness might not have been established yet).
4092 * Returns:
4093 * - >0, if type graphs are equivalent;
4094 * - 0, if not equivalent;
4095 * - <0, on error.
4096 *
4097 * Algorithm performs side-by-side DFS traversal of both type graphs and checks
4098 * equivalence of BTF types at each step. If at any point BTF types in candidate
4099 * and canonical graphs are not compatible structurally, whole graphs are
4100 * incompatible. If types are structurally equivalent (i.e., all information
4101 * except referenced type IDs is exactly the same), a mapping from `canon_id` to
4102 * a `cand_id` is recored in hypothetical mapping (`btf_dedup->hypot_map`).
4103 * If a type references other types, then those referenced types are checked
4104 * for equivalence recursively.
4105 *
4106 * During DFS traversal, if we find that for current `canon_id` type we
4107 * already have some mapping in hypothetical map, we check for two possible
4108 * situations:
4109 * - `canon_id` is mapped to exactly the same type as `cand_id`. This will
4110 * happen when type graphs have cycles. In this case we assume those two
4111 * types are equivalent.
4112 * - `canon_id` is mapped to different type. This is contradiction in our
4113 * hypothetical mapping, because same graph in canonical graph corresponds
4114 * to two different types in candidate graph, which for equivalent type
4115 * graphs shouldn't happen. This condition terminates equivalence check
4116 * with negative result.
4117 *
4118 * If type graphs traversal exhausts types to check and find no contradiction,
4119 * then type graphs are equivalent.
4120 *
4121 * When checking types for equivalence, there is one special case: FWD types.
4122 * If FWD type resolution is allowed and one of the types (either from canonical
4123 * or candidate graph) is FWD and other is STRUCT/UNION (depending on FWD's kind
4124 * flag) and their names match, hypothetical mapping is updated to point from
4125 * FWD to STRUCT/UNION. If graphs will be determined as equivalent successfully,
4126 * this mapping will be used to record FWD -> STRUCT/UNION mapping permanently.
4127 *
4128 * Technically, this could lead to incorrect FWD to STRUCT/UNION resolution,
4129 * if there are two exactly named (or anonymous) structs/unions that are
4130 * compatible structurally, one of which has FWD field, while other is concrete
4131 * STRUCT/UNION, but according to C sources they are different structs/unions
4132 * that are referencing different types with the same name. This is extremely
4133 * unlikely to happen, but btf_dedup API allows to disable FWD resolution if
4134 * this logic is causing problems.
4135 *
4136 * Doing FWD resolution means that both candidate and/or canonical graphs can
4137 * consists of portions of the graph that come from multiple compilation units.
4138 * This is due to the fact that types within single compilation unit are always
4139 * deduplicated and FWDs are already resolved, if referenced struct/union
4140 * definiton is available. So, if we had unresolved FWD and found corresponding
4141 * STRUCT/UNION, they will be from different compilation units. This
4142 * consequently means that when we "link" FWD to corresponding STRUCT/UNION,
4143 * type graph will likely have at least two different BTF types that describe
4144 * same type (e.g., most probably there will be two different BTF types for the
4145 * same 'int' primitive type) and could even have "overlapping" parts of type
4146 * graph that describe same subset of types.
4147 *
4148 * This in turn means that our assumption that each type in canonical graph
4149 * must correspond to exactly one type in candidate graph might not hold
4150 * anymore and will make it harder to detect contradictions using hypothetical
4151 * map. To handle this problem, we allow to follow FWD -> STRUCT/UNION
4152 * resolution only in canonical graph. FWDs in candidate graphs are never
4153 * resolved. To see why it's OK, let's check all possible situations w.r.t. FWDs
4154 * that can occur:
4155 * - Both types in canonical and candidate graphs are FWDs. If they are
4156 * structurally equivalent, then they can either be both resolved to the
4157 * same STRUCT/UNION or not resolved at all. In both cases they are
4158 * equivalent and there is no need to resolve FWD on candidate side.
4159 * - Both types in canonical and candidate graphs are concrete STRUCT/UNION,
4160 * so nothing to resolve as well, algorithm will check equivalence anyway.
4161 * - Type in canonical graph is FWD, while type in candidate is concrete
4162 * STRUCT/UNION. In this case candidate graph comes from single compilation
4163 * unit, so there is exactly one BTF type for each unique C type. After
4164 * resolving FWD into STRUCT/UNION, there might be more than one BTF type
4165 * in canonical graph mapping to single BTF type in candidate graph, but
4166 * because hypothetical mapping maps from canonical to candidate types, it's
4167 * alright, and we still maintain the property of having single `canon_id`
4168 * mapping to single `cand_id` (there could be two different `canon_id`
4169 * mapped to the same `cand_id`, but it's not contradictory).
4170 * - Type in canonical graph is concrete STRUCT/UNION, while type in candidate
4171 * graph is FWD. In this case we are just going to check compatibility of
4172 * STRUCT/UNION and corresponding FWD, and if they are compatible, we'll
4173 * assume that whatever STRUCT/UNION FWD resolves to must be equivalent to
4174 * a concrete STRUCT/UNION from canonical graph. If the rest of type graphs
4175 * turn out equivalent, we'll re-resolve FWD to concrete STRUCT/UNION from
4176 * canonical graph.
4177 */
4178static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
4179 __u32 canon_id)
4180{
4181 struct btf_type *cand_type;
4182 struct btf_type *canon_type;
4183 __u32 hypot_type_id;
4184 __u16 cand_kind;
4185 __u16 canon_kind;
4186 int i, eq;
4187
4188 /* if both resolve to the same canonical, they must be equivalent */
4189 if (resolve_type_id(d, cand_id) == resolve_type_id(d, canon_id))
4190 return 1;
4191
4192 canon_id = resolve_fwd_id(d, canon_id);
4193
4194 hypot_type_id = d->hypot_map[canon_id];
4195 if (hypot_type_id <= BTF_MAX_NR_TYPES) {
4196 if (hypot_type_id == cand_id)
4197 return 1;
4198 /* In some cases compiler will generate different DWARF types
4199 * for *identical* array type definitions and use them for
4200 * different fields within the *same* struct. This breaks type
4201 * equivalence check, which makes an assumption that candidate
4202 * types sub-graph has a consistent and deduped-by-compiler
4203 * types within a single CU. So work around that by explicitly
4204 * allowing identical array types here.
4205 */
4206 if (btf_dedup_identical_arrays(d, hypot_type_id, cand_id))
4207 return 1;
4208 /* It turns out that similar situation can happen with
4209 * struct/union sometimes, sigh... Handle the case where
4210 * structs/unions are exactly the same, down to the referenced
4211 * type IDs. Anything more complicated (e.g., if referenced
4212 * types are different, but equivalent) is *way more*
4213 * complicated and requires a many-to-many equivalence mapping.
4214 */
4215 if (btf_dedup_identical_structs(d, hypot_type_id, cand_id))
4216 return 1;
4217 return 0;
4218 }
4219
4220 if (btf_dedup_hypot_map_add(d, canon_id, cand_id))
4221 return -ENOMEM;
4222
4223 cand_type = btf_type_by_id(d->btf, cand_id);
4224 canon_type = btf_type_by_id(d->btf, canon_id);
4225 cand_kind = btf_kind(cand_type);
4226 canon_kind = btf_kind(canon_type);
4227
4228 if (cand_type->name_off != canon_type->name_off)
4229 return 0;
4230
4231 /* FWD <--> STRUCT/UNION equivalence check, if enabled */
4232 if ((cand_kind == BTF_KIND_FWD || canon_kind == BTF_KIND_FWD)
4233 && cand_kind != canon_kind) {
4234 __u16 real_kind;
4235 __u16 fwd_kind;
4236
4237 if (cand_kind == BTF_KIND_FWD) {
4238 real_kind = canon_kind;
4239 fwd_kind = btf_fwd_kind(cand_type);
4240 } else {
4241 real_kind = cand_kind;
4242 fwd_kind = btf_fwd_kind(canon_type);
4243 /* we'd need to resolve base FWD to STRUCT/UNION */
4244 if (fwd_kind == real_kind && canon_id < d->btf->start_id)
4245 d->hypot_adjust_canon = true;
4246 }
4247 return fwd_kind == real_kind;
4248 }
4249
4250 if (cand_kind != canon_kind)
4251 return 0;
4252
4253 switch (cand_kind) {
4254 case BTF_KIND_INT:
4255 return btf_equal_int_tag(cand_type, canon_type);
4256
4257 case BTF_KIND_ENUM:
4258 case BTF_KIND_ENUM64:
4259 return btf_compat_enum(cand_type, canon_type);
4260
4261 case BTF_KIND_FWD:
4262 case BTF_KIND_FLOAT:
4263 return btf_equal_common(cand_type, canon_type);
4264
4265 case BTF_KIND_CONST:
4266 case BTF_KIND_VOLATILE:
4267 case BTF_KIND_RESTRICT:
4268 case BTF_KIND_PTR:
4269 case BTF_KIND_TYPEDEF:
4270 case BTF_KIND_FUNC:
4271 case BTF_KIND_TYPE_TAG:
4272 if (cand_type->info != canon_type->info)
4273 return 0;
4274 return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
4275
4276 case BTF_KIND_ARRAY: {
4277 const struct btf_array *cand_arr, *canon_arr;
4278
4279 if (!btf_compat_array(cand_type, canon_type))
4280 return 0;
4281 cand_arr = btf_array(cand_type);
4282 canon_arr = btf_array(canon_type);
4283 eq = btf_dedup_is_equiv(d, cand_arr->index_type, canon_arr->index_type);
4284 if (eq <= 0)
4285 return eq;
4286 return btf_dedup_is_equiv(d, cand_arr->type, canon_arr->type);
4287 }
4288
4289 case BTF_KIND_STRUCT:
4290 case BTF_KIND_UNION: {
4291 const struct btf_member *cand_m, *canon_m;
4292 __u16 vlen;
4293
4294 if (!btf_shallow_equal_struct(cand_type, canon_type))
4295 return 0;
4296 vlen = btf_vlen(cand_type);
4297 cand_m = btf_members(cand_type);
4298 canon_m = btf_members(canon_type);
4299 for (i = 0; i < vlen; i++) {
4300 eq = btf_dedup_is_equiv(d, cand_m->type, canon_m->type);
4301 if (eq <= 0)
4302 return eq;
4303 cand_m++;
4304 canon_m++;
4305 }
4306
4307 return 1;
4308 }
4309
4310 case BTF_KIND_FUNC_PROTO: {
4311 const struct btf_param *cand_p, *canon_p;
4312 __u16 vlen;
4313
4314 if (!btf_compat_fnproto(cand_type, canon_type))
4315 return 0;
4316 eq = btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
4317 if (eq <= 0)
4318 return eq;
4319 vlen = btf_vlen(cand_type);
4320 cand_p = btf_params(cand_type);
4321 canon_p = btf_params(canon_type);
4322 for (i = 0; i < vlen; i++) {
4323 eq = btf_dedup_is_equiv(d, cand_p->type, canon_p->type);
4324 if (eq <= 0)
4325 return eq;
4326 cand_p++;
4327 canon_p++;
4328 }
4329 return 1;
4330 }
4331
4332 default:
4333 return -EINVAL;
4334 }
4335 return 0;
4336}
4337
4338/*
4339 * Use hypothetical mapping, produced by successful type graph equivalence
4340 * check, to augment existing struct/union canonical mapping, where possible.
4341 *
4342 * If BTF_KIND_FWD resolution is allowed, this mapping is also used to record
4343 * FWD -> STRUCT/UNION correspondence as well. FWD resolution is bidirectional:
4344 * it doesn't matter if FWD type was part of canonical graph or candidate one,
4345 * we are recording the mapping anyway. As opposed to carefulness required
4346 * for struct/union correspondence mapping (described below), for FWD resolution
4347 * it's not important, as by the time that FWD type (reference type) will be
4348 * deduplicated all structs/unions will be deduped already anyway.
4349 *
4350 * Recording STRUCT/UNION mapping is purely a performance optimization and is
4351 * not required for correctness. It needs to be done carefully to ensure that
4352 * struct/union from candidate's type graph is not mapped into corresponding
4353 * struct/union from canonical type graph that itself hasn't been resolved into
4354 * canonical representative. The only guarantee we have is that canonical
4355 * struct/union was determined as canonical and that won't change. But any
4356 * types referenced through that struct/union fields could have been not yet
4357 * resolved, so in case like that it's too early to establish any kind of
4358 * correspondence between structs/unions.
4359 *
4360 * No canonical correspondence is derived for primitive types (they are already
4361 * deduplicated completely already anyway) or reference types (they rely on
4362 * stability of struct/union canonical relationship for equivalence checks).
4363 */
4364static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
4365{
4366 __u32 canon_type_id, targ_type_id;
4367 __u16 t_kind, c_kind;
4368 __u32 t_id, c_id;
4369 int i;
4370
4371 for (i = 0; i < d->hypot_cnt; i++) {
4372 canon_type_id = d->hypot_list[i];
4373 targ_type_id = d->hypot_map[canon_type_id];
4374 t_id = resolve_type_id(d, targ_type_id);
4375 c_id = resolve_type_id(d, canon_type_id);
4376 t_kind = btf_kind(btf__type_by_id(d->btf, t_id));
4377 c_kind = btf_kind(btf__type_by_id(d->btf, c_id));
4378 /*
4379 * Resolve FWD into STRUCT/UNION.
4380 * It's ok to resolve FWD into STRUCT/UNION that's not yet
4381 * mapped to canonical representative (as opposed to
4382 * STRUCT/UNION <--> STRUCT/UNION mapping logic below), because
4383 * eventually that struct is going to be mapped and all resolved
4384 * FWDs will automatically resolve to correct canonical
4385 * representative. This will happen before ref type deduping,
4386 * which critically depends on stability of these mapping. This
4387 * stability is not a requirement for STRUCT/UNION equivalence
4388 * checks, though.
4389 */
4390
4391 /* if it's the split BTF case, we still need to point base FWD
4392 * to STRUCT/UNION in a split BTF, because FWDs from split BTF
4393 * will be resolved against base FWD. If we don't point base
4394 * canonical FWD to the resolved STRUCT/UNION, then all the
4395 * FWDs in split BTF won't be correctly resolved to a proper
4396 * STRUCT/UNION.
4397 */
4398 if (t_kind != BTF_KIND_FWD && c_kind == BTF_KIND_FWD)
4399 d->map[c_id] = t_id;
4400
4401 /* if graph equivalence determined that we'd need to adjust
4402 * base canonical types, then we need to only point base FWDs
4403 * to STRUCTs/UNIONs and do no more modifications. For all
4404 * other purposes the type graphs were not equivalent.
4405 */
4406 if (d->hypot_adjust_canon)
4407 continue;
4408
4409 if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD)
4410 d->map[t_id] = c_id;
4411
4412 if ((t_kind == BTF_KIND_STRUCT || t_kind == BTF_KIND_UNION) &&
4413 c_kind != BTF_KIND_FWD &&
4414 is_type_mapped(d, c_id) &&
4415 !is_type_mapped(d, t_id)) {
4416 /*
4417 * as a perf optimization, we can map struct/union
4418 * that's part of type graph we just verified for
4419 * equivalence. We can do that for struct/union that has
4420 * canonical representative only, though.
4421 */
4422 d->map[t_id] = c_id;
4423 }
4424 }
4425}
4426
4427/*
4428 * Deduplicate struct/union types.
4429 *
4430 * For each struct/union type its type signature hash is calculated, taking
4431 * into account type's name, size, number, order and names of fields, but
4432 * ignoring type ID's referenced from fields, because they might not be deduped
4433 * completely until after reference types deduplication phase. This type hash
4434 * is used to iterate over all potential canonical types, sharing same hash.
4435 * For each canonical candidate we check whether type graphs that they form
4436 * (through referenced types in fields and so on) are equivalent using algorithm
4437 * implemented in `btf_dedup_is_equiv`. If such equivalence is found and
4438 * BTF_KIND_FWD resolution is allowed, then hypothetical mapping
4439 * (btf_dedup->hypot_map) produced by aforementioned type graph equivalence
4440 * algorithm is used to record FWD -> STRUCT/UNION mapping. It's also used to
4441 * potentially map other structs/unions to their canonical representatives,
4442 * if such relationship hasn't yet been established. This speeds up algorithm
4443 * by eliminating some of the duplicate work.
4444 *
4445 * If no matching canonical representative was found, struct/union is marked
4446 * as canonical for itself and is added into btf_dedup->dedup_table hash map
4447 * for further look ups.
4448 */
4449static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
4450{
4451 struct btf_type *cand_type, *t;
4452 struct hashmap_entry *hash_entry;
4453 /* if we don't find equivalent type, then we are canonical */
4454 __u32 new_id = type_id;
4455 __u16 kind;
4456 long h;
4457
4458 /* already deduped or is in process of deduping (loop detected) */
4459 if (d->map[type_id] <= BTF_MAX_NR_TYPES)
4460 return 0;
4461
4462 t = btf_type_by_id(d->btf, type_id);
4463 kind = btf_kind(t);
4464
4465 if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
4466 return 0;
4467
4468 h = btf_hash_struct(t);
4469 for_each_dedup_cand(d, hash_entry, h) {
4470 __u32 cand_id = hash_entry->value;
4471 int eq;
4472
4473 /*
4474 * Even though btf_dedup_is_equiv() checks for
4475 * btf_shallow_equal_struct() internally when checking two
4476 * structs (unions) for equivalence, we need to guard here
4477 * from picking matching FWD type as a dedup candidate.
4478 * This can happen due to hash collision. In such case just
4479 * relying on btf_dedup_is_equiv() would lead to potentially
4480 * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because
4481 * FWD and compatible STRUCT/UNION are considered equivalent.
4482 */
4483 cand_type = btf_type_by_id(d->btf, cand_id);
4484 if (!btf_shallow_equal_struct(t, cand_type))
4485 continue;
4486
4487 btf_dedup_clear_hypot_map(d);
4488 eq = btf_dedup_is_equiv(d, type_id, cand_id);
4489 if (eq < 0)
4490 return eq;
4491 if (!eq)
4492 continue;
4493 btf_dedup_merge_hypot_map(d);
4494 if (d->hypot_adjust_canon) /* not really equivalent */
4495 continue;
4496 new_id = cand_id;
4497 break;
4498 }
4499
4500 d->map[type_id] = new_id;
4501 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
4502 return -ENOMEM;
4503
4504 return 0;
4505}
4506
4507static int btf_dedup_struct_types(struct btf_dedup *d)
4508{
4509 int i, err;
4510
4511 for (i = 0; i < d->btf->nr_types; i++) {
4512 err = btf_dedup_struct_type(d, d->btf->start_id + i);
4513 if (err)
4514 return err;
4515 }
4516 return 0;
4517}
4518
4519/*
4520 * Deduplicate reference type.
4521 *
4522 * Once all primitive and struct/union types got deduplicated, we can easily
4523 * deduplicate all other (reference) BTF types. This is done in two steps:
4524 *
4525 * 1. Resolve all referenced type IDs into their canonical type IDs. This
4526 * resolution can be done either immediately for primitive or struct/union types
4527 * (because they were deduped in previous two phases) or recursively for
4528 * reference types. Recursion will always terminate at either primitive or
4529 * struct/union type, at which point we can "unwind" chain of reference types
4530 * one by one. There is no danger of encountering cycles because in C type
4531 * system the only way to form type cycle is through struct/union, so any chain
4532 * of reference types, even those taking part in a type cycle, will inevitably
4533 * reach struct/union at some point.
4534 *
4535 * 2. Once all referenced type IDs are resolved into canonical ones, BTF type
4536 * becomes "stable", in the sense that no further deduplication will cause
4537 * any changes to it. With that, it's now possible to calculate type's signature
4538 * hash (this time taking into account referenced type IDs) and loop over all
4539 * potential canonical representatives. If no match was found, current type
4540 * will become canonical representative of itself and will be added into
4541 * btf_dedup->dedup_table as another possible canonical representative.
4542 */
4543static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
4544{
4545 struct hashmap_entry *hash_entry;
4546 __u32 new_id = type_id, cand_id;
4547 struct btf_type *t, *cand;
4548 /* if we don't find equivalent type, then we are representative type */
4549 int ref_type_id;
4550 long h;
4551
4552 if (d->map[type_id] == BTF_IN_PROGRESS_ID)
4553 return -ELOOP;
4554 if (d->map[type_id] <= BTF_MAX_NR_TYPES)
4555 return resolve_type_id(d, type_id);
4556
4557 t = btf_type_by_id(d->btf, type_id);
4558 d->map[type_id] = BTF_IN_PROGRESS_ID;
4559
4560 switch (btf_kind(t)) {
4561 case BTF_KIND_CONST:
4562 case BTF_KIND_VOLATILE:
4563 case BTF_KIND_RESTRICT:
4564 case BTF_KIND_PTR:
4565 case BTF_KIND_TYPEDEF:
4566 case BTF_KIND_FUNC:
4567 case BTF_KIND_TYPE_TAG:
4568 ref_type_id = btf_dedup_ref_type(d, t->type);
4569 if (ref_type_id < 0)
4570 return ref_type_id;
4571 t->type = ref_type_id;
4572
4573 h = btf_hash_common(t);
4574 for_each_dedup_cand(d, hash_entry, h) {
4575 cand_id = hash_entry->value;
4576 cand = btf_type_by_id(d->btf, cand_id);
4577 if (btf_equal_common(t, cand)) {
4578 new_id = cand_id;
4579 break;
4580 }
4581 }
4582 break;
4583
4584 case BTF_KIND_DECL_TAG:
4585 ref_type_id = btf_dedup_ref_type(d, t->type);
4586 if (ref_type_id < 0)
4587 return ref_type_id;
4588 t->type = ref_type_id;
4589
4590 h = btf_hash_int_decl_tag(t);
4591 for_each_dedup_cand(d, hash_entry, h) {
4592 cand_id = hash_entry->value;
4593 cand = btf_type_by_id(d->btf, cand_id);
4594 if (btf_equal_int_tag(t, cand)) {
4595 new_id = cand_id;
4596 break;
4597 }
4598 }
4599 break;
4600
4601 case BTF_KIND_ARRAY: {
4602 struct btf_array *info = btf_array(t);
4603
4604 ref_type_id = btf_dedup_ref_type(d, info->type);
4605 if (ref_type_id < 0)
4606 return ref_type_id;
4607 info->type = ref_type_id;
4608
4609 ref_type_id = btf_dedup_ref_type(d, info->index_type);
4610 if (ref_type_id < 0)
4611 return ref_type_id;
4612 info->index_type = ref_type_id;
4613
4614 h = btf_hash_array(t);
4615 for_each_dedup_cand(d, hash_entry, h) {
4616 cand_id = hash_entry->value;
4617 cand = btf_type_by_id(d->btf, cand_id);
4618 if (btf_equal_array(t, cand)) {
4619 new_id = cand_id;
4620 break;
4621 }
4622 }
4623 break;
4624 }
4625
4626 case BTF_KIND_FUNC_PROTO: {
4627 struct btf_param *param;
4628 __u16 vlen;
4629 int i;
4630
4631 ref_type_id = btf_dedup_ref_type(d, t->type);
4632 if (ref_type_id < 0)
4633 return ref_type_id;
4634 t->type = ref_type_id;
4635
4636 vlen = btf_vlen(t);
4637 param = btf_params(t);
4638 for (i = 0; i < vlen; i++) {
4639 ref_type_id = btf_dedup_ref_type(d, param->type);
4640 if (ref_type_id < 0)
4641 return ref_type_id;
4642 param->type = ref_type_id;
4643 param++;
4644 }
4645
4646 h = btf_hash_fnproto(t);
4647 for_each_dedup_cand(d, hash_entry, h) {
4648 cand_id = hash_entry->value;
4649 cand = btf_type_by_id(d->btf, cand_id);
4650 if (btf_equal_fnproto(t, cand)) {
4651 new_id = cand_id;
4652 break;
4653 }
4654 }
4655 break;
4656 }
4657
4658 default:
4659 return -EINVAL;
4660 }
4661
4662 d->map[type_id] = new_id;
4663 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
4664 return -ENOMEM;
4665
4666 return new_id;
4667}
4668
4669static int btf_dedup_ref_types(struct btf_dedup *d)
4670{
4671 int i, err;
4672
4673 for (i = 0; i < d->btf->nr_types; i++) {
4674 err = btf_dedup_ref_type(d, d->btf->start_id + i);
4675 if (err < 0)
4676 return err;
4677 }
4678 /* we won't need d->dedup_table anymore */
4679 hashmap__free(d->dedup_table);
4680 d->dedup_table = NULL;
4681 return 0;
4682}
4683
4684/*
4685 * Collect a map from type names to type ids for all canonical structs
4686 * and unions. If the same name is shared by several canonical types
4687 * use a special value 0 to indicate this fact.
4688 */
4689static int btf_dedup_fill_unique_names_map(struct btf_dedup *d, struct hashmap *names_map)
4690{
4691 __u32 nr_types = btf__type_cnt(d->btf);
4692 struct btf_type *t;
4693 __u32 type_id;
4694 __u16 kind;
4695 int err;
4696
4697 /*
4698 * Iterate over base and split module ids in order to get all
4699 * available structs in the map.
4700 */
4701 for (type_id = 1; type_id < nr_types; ++type_id) {
4702 t = btf_type_by_id(d->btf, type_id);
4703 kind = btf_kind(t);
4704
4705 if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
4706 continue;
4707
4708 /* Skip non-canonical types */
4709 if (type_id != d->map[type_id])
4710 continue;
4711
4712 err = hashmap__add(names_map, t->name_off, type_id);
4713 if (err == -EEXIST)
4714 err = hashmap__set(names_map, t->name_off, 0, NULL, NULL);
4715
4716 if (err)
4717 return err;
4718 }
4719
4720 return 0;
4721}
4722
4723static int btf_dedup_resolve_fwd(struct btf_dedup *d, struct hashmap *names_map, __u32 type_id)
4724{
4725 struct btf_type *t = btf_type_by_id(d->btf, type_id);
4726 enum btf_fwd_kind fwd_kind = btf_kflag(t);
4727 __u16 cand_kind, kind = btf_kind(t);
4728 struct btf_type *cand_t;
4729 uintptr_t cand_id;
4730
4731 if (kind != BTF_KIND_FWD)
4732 return 0;
4733
4734 /* Skip if this FWD already has a mapping */
4735 if (type_id != d->map[type_id])
4736 return 0;
4737
4738 if (!hashmap__find(names_map, t->name_off, &cand_id))
4739 return 0;
4740
4741 /* Zero is a special value indicating that name is not unique */
4742 if (!cand_id)
4743 return 0;
4744
4745 cand_t = btf_type_by_id(d->btf, cand_id);
4746 cand_kind = btf_kind(cand_t);
4747 if ((cand_kind == BTF_KIND_STRUCT && fwd_kind != BTF_FWD_STRUCT) ||
4748 (cand_kind == BTF_KIND_UNION && fwd_kind != BTF_FWD_UNION))
4749 return 0;
4750
4751 d->map[type_id] = cand_id;
4752
4753 return 0;
4754}
4755
4756/*
4757 * Resolve unambiguous forward declarations.
4758 *
4759 * The lion's share of all FWD declarations is resolved during
4760 * `btf_dedup_struct_types` phase when different type graphs are
4761 * compared against each other. However, if in some compilation unit a
4762 * FWD declaration is not a part of a type graph compared against
4763 * another type graph that declaration's canonical type would not be
4764 * changed. Example:
4765 *
4766 * CU #1:
4767 *
4768 * struct foo;
4769 * struct foo *some_global;
4770 *
4771 * CU #2:
4772 *
4773 * struct foo { int u; };
4774 * struct foo *another_global;
4775 *
4776 * After `btf_dedup_struct_types` the BTF looks as follows:
4777 *
4778 * [1] STRUCT 'foo' size=4 vlen=1 ...
4779 * [2] INT 'int' size=4 ...
4780 * [3] PTR '(anon)' type_id=1
4781 * [4] FWD 'foo' fwd_kind=struct
4782 * [5] PTR '(anon)' type_id=4
4783 *
4784 * This pass assumes that such FWD declarations should be mapped to
4785 * structs or unions with identical name in case if the name is not
4786 * ambiguous.
4787 */
4788static int btf_dedup_resolve_fwds(struct btf_dedup *d)
4789{
4790 int i, err;
4791 struct hashmap *names_map;
4792
4793 names_map = hashmap__new(btf_dedup_identity_hash_fn, btf_dedup_equal_fn, NULL);
4794 if (IS_ERR(names_map))
4795 return PTR_ERR(names_map);
4796
4797 err = btf_dedup_fill_unique_names_map(d, names_map);
4798 if (err < 0)
4799 goto exit;
4800
4801 for (i = 0; i < d->btf->nr_types; i++) {
4802 err = btf_dedup_resolve_fwd(d, names_map, d->btf->start_id + i);
4803 if (err < 0)
4804 break;
4805 }
4806
4807exit:
4808 hashmap__free(names_map);
4809 return err;
4810}
4811
4812/*
4813 * Compact types.
4814 *
4815 * After we established for each type its corresponding canonical representative
4816 * type, we now can eliminate types that are not canonical and leave only
4817 * canonical ones layed out sequentially in memory by copying them over
4818 * duplicates. During compaction btf_dedup->hypot_map array is reused to store
4819 * a map from original type ID to a new compacted type ID, which will be used
4820 * during next phase to "fix up" type IDs, referenced from struct/union and
4821 * reference types.
4822 */
4823static int btf_dedup_compact_types(struct btf_dedup *d)
4824{
4825 __u32 *new_offs;
4826 __u32 next_type_id = d->btf->start_id;
4827 const struct btf_type *t;
4828 void *p;
4829 int i, id, len;
4830
4831 /* we are going to reuse hypot_map to store compaction remapping */
4832 d->hypot_map[0] = 0;
4833 /* base BTF types are not renumbered */
4834 for (id = 1; id < d->btf->start_id; id++)
4835 d->hypot_map[id] = id;
4836 for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++)
4837 d->hypot_map[id] = BTF_UNPROCESSED_ID;
4838
4839 p = d->btf->types_data;
4840
4841 for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++) {
4842 if (d->map[id] != id)
4843 continue;
4844
4845 t = btf__type_by_id(d->btf, id);
4846 len = btf_type_size(t);
4847 if (len < 0)
4848 return len;
4849
4850 memmove(p, t, len);
4851 d->hypot_map[id] = next_type_id;
4852 d->btf->type_offs[next_type_id - d->btf->start_id] = p - d->btf->types_data;
4853 p += len;
4854 next_type_id++;
4855 }
4856
4857 /* shrink struct btf's internal types index and update btf_header */
4858 d->btf->nr_types = next_type_id - d->btf->start_id;
4859 d->btf->type_offs_cap = d->btf->nr_types;
4860 d->btf->hdr->type_len = p - d->btf->types_data;
4861 new_offs = libbpf_reallocarray(d->btf->type_offs, d->btf->type_offs_cap,
4862 sizeof(*new_offs));
4863 if (d->btf->type_offs_cap && !new_offs)
4864 return -ENOMEM;
4865 d->btf->type_offs = new_offs;
4866 d->btf->hdr->str_off = d->btf->hdr->type_len;
4867 d->btf->raw_size = d->btf->hdr->hdr_len + d->btf->hdr->type_len + d->btf->hdr->str_len;
4868 return 0;
4869}
4870
4871/*
4872 * Figure out final (deduplicated and compacted) type ID for provided original
4873 * `type_id` by first resolving it into corresponding canonical type ID and
4874 * then mapping it to a deduplicated type ID, stored in btf_dedup->hypot_map,
4875 * which is populated during compaction phase.
4876 */
4877static int btf_dedup_remap_type_id(__u32 *type_id, void *ctx)
4878{
4879 struct btf_dedup *d = ctx;
4880 __u32 resolved_type_id, new_type_id;
4881
4882 resolved_type_id = resolve_type_id(d, *type_id);
4883 new_type_id = d->hypot_map[resolved_type_id];
4884 if (new_type_id > BTF_MAX_NR_TYPES)
4885 return -EINVAL;
4886
4887 *type_id = new_type_id;
4888 return 0;
4889}
4890
4891/*
4892 * Remap referenced type IDs into deduped type IDs.
4893 *
4894 * After BTF types are deduplicated and compacted, their final type IDs may
4895 * differ from original ones. The map from original to a corresponding
4896 * deduped type ID is stored in btf_dedup->hypot_map and is populated during
4897 * compaction phase. During remapping phase we are rewriting all type IDs
4898 * referenced from any BTF type (e.g., struct fields, func proto args, etc) to
4899 * their final deduped type IDs.
4900 */
4901static int btf_dedup_remap_types(struct btf_dedup *d)
4902{
4903 int i, r;
4904
4905 for (i = 0; i < d->btf->nr_types; i++) {
4906 struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
4907
4908 r = btf_type_visit_type_ids(t, btf_dedup_remap_type_id, d);
4909 if (r)
4910 return r;
4911 }
4912
4913 if (!d->btf_ext)
4914 return 0;
4915
4916 r = btf_ext_visit_type_ids(d->btf_ext, btf_dedup_remap_type_id, d);
4917 if (r)
4918 return r;
4919
4920 return 0;
4921}
4922
4923/*
4924 * Probe few well-known locations for vmlinux kernel image and try to load BTF
4925 * data out of it to use for target BTF.
4926 */
4927struct btf *btf__load_vmlinux_btf(void)
4928{
4929 const char *locations[] = {
4930 /* try canonical vmlinux BTF through sysfs first */
4931 "/sys/kernel/btf/vmlinux",
4932 /* fall back to trying to find vmlinux on disk otherwise */
4933 "/boot/vmlinux-%1$s",
4934 "/lib/modules/%1$s/vmlinux-%1$s",
4935 "/lib/modules/%1$s/build/vmlinux",
4936 "/usr/lib/modules/%1$s/kernel/vmlinux",
4937 "/usr/lib/debug/boot/vmlinux-%1$s",
4938 "/usr/lib/debug/boot/vmlinux-%1$s.debug",
4939 "/usr/lib/debug/lib/modules/%1$s/vmlinux",
4940 };
4941 char path[PATH_MAX + 1];
4942 struct utsname buf;
4943 struct btf *btf;
4944 int i, err;
4945
4946 uname(&buf);
4947
4948 for (i = 0; i < ARRAY_SIZE(locations); i++) {
4949 snprintf(path, PATH_MAX, locations[i], buf.release);
4950
4951 if (faccessat(AT_FDCWD, path, R_OK, AT_EACCESS))
4952 continue;
4953
4954 btf = btf__parse(path, NULL);
4955 err = libbpf_get_error(btf);
4956 pr_debug("loading kernel BTF '%s': %d\n", path, err);
4957 if (err)
4958 continue;
4959
4960 return btf;
4961 }
4962
4963 pr_warn("failed to find valid kernel BTF\n");
4964 return libbpf_err_ptr(-ESRCH);
4965}
4966
4967struct btf *libbpf_find_kernel_btf(void) __attribute__((alias("btf__load_vmlinux_btf")));
4968
4969struct btf *btf__load_module_btf(const char *module_name, struct btf *vmlinux_btf)
4970{
4971 char path[80];
4972
4973 snprintf(path, sizeof(path), "/sys/kernel/btf/%s", module_name);
4974 return btf__parse_split(path, vmlinux_btf);
4975}
4976
4977int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx)
4978{
4979 int i, n, err;
4980
4981 switch (btf_kind(t)) {
4982 case BTF_KIND_INT:
4983 case BTF_KIND_FLOAT:
4984 case BTF_KIND_ENUM:
4985 case BTF_KIND_ENUM64:
4986 return 0;
4987
4988 case BTF_KIND_FWD:
4989 case BTF_KIND_CONST:
4990 case BTF_KIND_VOLATILE:
4991 case BTF_KIND_RESTRICT:
4992 case BTF_KIND_PTR:
4993 case BTF_KIND_TYPEDEF:
4994 case BTF_KIND_FUNC:
4995 case BTF_KIND_VAR:
4996 case BTF_KIND_DECL_TAG:
4997 case BTF_KIND_TYPE_TAG:
4998 return visit(&t->type, ctx);
4999
5000 case BTF_KIND_ARRAY: {
5001 struct btf_array *a = btf_array(t);
5002
5003 err = visit(&a->type, ctx);
5004 err = err ?: visit(&a->index_type, ctx);
5005 return err;
5006 }
5007
5008 case BTF_KIND_STRUCT:
5009 case BTF_KIND_UNION: {
5010 struct btf_member *m = btf_members(t);
5011
5012 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5013 err = visit(&m->type, ctx);
5014 if (err)
5015 return err;
5016 }
5017 return 0;
5018 }
5019
5020 case BTF_KIND_FUNC_PROTO: {
5021 struct btf_param *m = btf_params(t);
5022
5023 err = visit(&t->type, ctx);
5024 if (err)
5025 return err;
5026 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5027 err = visit(&m->type, ctx);
5028 if (err)
5029 return err;
5030 }
5031 return 0;
5032 }
5033
5034 case BTF_KIND_DATASEC: {
5035 struct btf_var_secinfo *m = btf_var_secinfos(t);
5036
5037 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5038 err = visit(&m->type, ctx);
5039 if (err)
5040 return err;
5041 }
5042 return 0;
5043 }
5044
5045 default:
5046 return -EINVAL;
5047 }
5048}
5049
5050int btf_type_visit_str_offs(struct btf_type *t, str_off_visit_fn visit, void *ctx)
5051{
5052 int i, n, err;
5053
5054 err = visit(&t->name_off, ctx);
5055 if (err)
5056 return err;
5057
5058 switch (btf_kind(t)) {
5059 case BTF_KIND_STRUCT:
5060 case BTF_KIND_UNION: {
5061 struct btf_member *m = btf_members(t);
5062
5063 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5064 err = visit(&m->name_off, ctx);
5065 if (err)
5066 return err;
5067 }
5068 break;
5069 }
5070 case BTF_KIND_ENUM: {
5071 struct btf_enum *m = btf_enum(t);
5072
5073 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5074 err = visit(&m->name_off, ctx);
5075 if (err)
5076 return err;
5077 }
5078 break;
5079 }
5080 case BTF_KIND_ENUM64: {
5081 struct btf_enum64 *m = btf_enum64(t);
5082
5083 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5084 err = visit(&m->name_off, ctx);
5085 if (err)
5086 return err;
5087 }
5088 break;
5089 }
5090 case BTF_KIND_FUNC_PROTO: {
5091 struct btf_param *m = btf_params(t);
5092
5093 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5094 err = visit(&m->name_off, ctx);
5095 if (err)
5096 return err;
5097 }
5098 break;
5099 }
5100 default:
5101 break;
5102 }
5103
5104 return 0;
5105}
5106
5107int btf_ext_visit_type_ids(struct btf_ext *btf_ext, type_id_visit_fn visit, void *ctx)
5108{
5109 const struct btf_ext_info *seg;
5110 struct btf_ext_info_sec *sec;
5111 int i, err;
5112
5113 seg = &btf_ext->func_info;
5114 for_each_btf_ext_sec(seg, sec) {
5115 struct bpf_func_info_min *rec;
5116
5117 for_each_btf_ext_rec(seg, sec, i, rec) {
5118 err = visit(&rec->type_id, ctx);
5119 if (err < 0)
5120 return err;
5121 }
5122 }
5123
5124 seg = &btf_ext->core_relo_info;
5125 for_each_btf_ext_sec(seg, sec) {
5126 struct bpf_core_relo *rec;
5127
5128 for_each_btf_ext_rec(seg, sec, i, rec) {
5129 err = visit(&rec->type_id, ctx);
5130 if (err < 0)
5131 return err;
5132 }
5133 }
5134
5135 return 0;
5136}
5137
5138int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void *ctx)
5139{
5140 const struct btf_ext_info *seg;
5141 struct btf_ext_info_sec *sec;
5142 int i, err;
5143
5144 seg = &btf_ext->func_info;
5145 for_each_btf_ext_sec(seg, sec) {
5146 err = visit(&sec->sec_name_off, ctx);
5147 if (err)
5148 return err;
5149 }
5150
5151 seg = &btf_ext->line_info;
5152 for_each_btf_ext_sec(seg, sec) {
5153 struct bpf_line_info_min *rec;
5154
5155 err = visit(&sec->sec_name_off, ctx);
5156 if (err)
5157 return err;
5158
5159 for_each_btf_ext_rec(seg, sec, i, rec) {
5160 err = visit(&rec->file_name_off, ctx);
5161 if (err)
5162 return err;
5163 err = visit(&rec->line_off, ctx);
5164 if (err)
5165 return err;
5166 }
5167 }
5168
5169 seg = &btf_ext->core_relo_info;
5170 for_each_btf_ext_sec(seg, sec) {
5171 struct bpf_core_relo *rec;
5172
5173 err = visit(&sec->sec_name_off, ctx);
5174 if (err)
5175 return err;
5176
5177 for_each_btf_ext_rec(seg, sec, i, rec) {
5178 err = visit(&rec->access_str_off, ctx);
5179 if (err)
5180 return err;
5181 }
5182 }
5183
5184 return 0;
5185}
1// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2/* Copyright (c) 2018 Facebook */
3
4#include <byteswap.h>
5#include <endian.h>
6#include <stdio.h>
7#include <stdlib.h>
8#include <string.h>
9#include <fcntl.h>
10#include <unistd.h>
11#include <errno.h>
12#include <sys/utsname.h>
13#include <sys/param.h>
14#include <sys/stat.h>
15#include <linux/kernel.h>
16#include <linux/err.h>
17#include <linux/btf.h>
18#include <gelf.h>
19#include "btf.h"
20#include "bpf.h"
21#include "libbpf.h"
22#include "libbpf_internal.h"
23#include "hashmap.h"
24#include "strset.h"
25
26#define BTF_MAX_NR_TYPES 0x7fffffffU
27#define BTF_MAX_STR_OFFSET 0x7fffffffU
28
29static struct btf_type btf_void;
30
31struct btf {
32 /* raw BTF data in native endianness */
33 void *raw_data;
34 /* raw BTF data in non-native endianness */
35 void *raw_data_swapped;
36 __u32 raw_size;
37 /* whether target endianness differs from the native one */
38 bool swapped_endian;
39
40 /*
41 * When BTF is loaded from an ELF or raw memory it is stored
42 * in a contiguous memory block. The hdr, type_data, and, strs_data
43 * point inside that memory region to their respective parts of BTF
44 * representation:
45 *
46 * +--------------------------------+
47 * | Header | Types | Strings |
48 * +--------------------------------+
49 * ^ ^ ^
50 * | | |
51 * hdr | |
52 * types_data-+ |
53 * strs_data------------+
54 *
55 * If BTF data is later modified, e.g., due to types added or
56 * removed, BTF deduplication performed, etc, this contiguous
57 * representation is broken up into three independently allocated
58 * memory regions to be able to modify them independently.
59 * raw_data is nulled out at that point, but can be later allocated
60 * and cached again if user calls btf__raw_data(), at which point
61 * raw_data will contain a contiguous copy of header, types, and
62 * strings:
63 *
64 * +----------+ +---------+ +-----------+
65 * | Header | | Types | | Strings |
66 * +----------+ +---------+ +-----------+
67 * ^ ^ ^
68 * | | |
69 * hdr | |
70 * types_data----+ |
71 * strset__data(strs_set)-----+
72 *
73 * +----------+---------+-----------+
74 * | Header | Types | Strings |
75 * raw_data----->+----------+---------+-----------+
76 */
77 struct btf_header *hdr;
78
79 void *types_data;
80 size_t types_data_cap; /* used size stored in hdr->type_len */
81
82 /* type ID to `struct btf_type *` lookup index
83 * type_offs[0] corresponds to the first non-VOID type:
84 * - for base BTF it's type [1];
85 * - for split BTF it's the first non-base BTF type.
86 */
87 __u32 *type_offs;
88 size_t type_offs_cap;
89 /* number of types in this BTF instance:
90 * - doesn't include special [0] void type;
91 * - for split BTF counts number of types added on top of base BTF.
92 */
93 __u32 nr_types;
94 /* if not NULL, points to the base BTF on top of which the current
95 * split BTF is based
96 */
97 struct btf *base_btf;
98 /* BTF type ID of the first type in this BTF instance:
99 * - for base BTF it's equal to 1;
100 * - for split BTF it's equal to biggest type ID of base BTF plus 1.
101 */
102 int start_id;
103 /* logical string offset of this BTF instance:
104 * - for base BTF it's equal to 0;
105 * - for split BTF it's equal to total size of base BTF's string section size.
106 */
107 int start_str_off;
108
109 /* only one of strs_data or strs_set can be non-NULL, depending on
110 * whether BTF is in a modifiable state (strs_set is used) or not
111 * (strs_data points inside raw_data)
112 */
113 void *strs_data;
114 /* a set of unique strings */
115 struct strset *strs_set;
116 /* whether strings are already deduplicated */
117 bool strs_deduped;
118
119 /* BTF object FD, if loaded into kernel */
120 int fd;
121
122 /* Pointer size (in bytes) for a target architecture of this BTF */
123 int ptr_sz;
124};
125
126static inline __u64 ptr_to_u64(const void *ptr)
127{
128 return (__u64) (unsigned long) ptr;
129}
130
131/* Ensure given dynamically allocated memory region pointed to by *data* with
132 * capacity of *cap_cnt* elements each taking *elem_sz* bytes has enough
133 * memory to accommodate *add_cnt* new elements, assuming *cur_cnt* elements
134 * are already used. At most *max_cnt* elements can be ever allocated.
135 * If necessary, memory is reallocated and all existing data is copied over,
136 * new pointer to the memory region is stored at *data, new memory region
137 * capacity (in number of elements) is stored in *cap.
138 * On success, memory pointer to the beginning of unused memory is returned.
139 * On error, NULL is returned.
140 */
141void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
142 size_t cur_cnt, size_t max_cnt, size_t add_cnt)
143{
144 size_t new_cnt;
145 void *new_data;
146
147 if (cur_cnt + add_cnt <= *cap_cnt)
148 return *data + cur_cnt * elem_sz;
149
150 /* requested more than the set limit */
151 if (cur_cnt + add_cnt > max_cnt)
152 return NULL;
153
154 new_cnt = *cap_cnt;
155 new_cnt += new_cnt / 4; /* expand by 25% */
156 if (new_cnt < 16) /* but at least 16 elements */
157 new_cnt = 16;
158 if (new_cnt > max_cnt) /* but not exceeding a set limit */
159 new_cnt = max_cnt;
160 if (new_cnt < cur_cnt + add_cnt) /* also ensure we have enough memory */
161 new_cnt = cur_cnt + add_cnt;
162
163 new_data = libbpf_reallocarray(*data, new_cnt, elem_sz);
164 if (!new_data)
165 return NULL;
166
167 /* zero out newly allocated portion of memory */
168 memset(new_data + (*cap_cnt) * elem_sz, 0, (new_cnt - *cap_cnt) * elem_sz);
169
170 *data = new_data;
171 *cap_cnt = new_cnt;
172 return new_data + cur_cnt * elem_sz;
173}
174
175/* Ensure given dynamically allocated memory region has enough allocated space
176 * to accommodate *need_cnt* elements of size *elem_sz* bytes each
177 */
178int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt)
179{
180 void *p;
181
182 if (need_cnt <= *cap_cnt)
183 return 0;
184
185 p = libbpf_add_mem(data, cap_cnt, elem_sz, *cap_cnt, SIZE_MAX, need_cnt - *cap_cnt);
186 if (!p)
187 return -ENOMEM;
188
189 return 0;
190}
191
192static void *btf_add_type_offs_mem(struct btf *btf, size_t add_cnt)
193{
194 return libbpf_add_mem((void **)&btf->type_offs, &btf->type_offs_cap, sizeof(__u32),
195 btf->nr_types, BTF_MAX_NR_TYPES, add_cnt);
196}
197
198static int btf_add_type_idx_entry(struct btf *btf, __u32 type_off)
199{
200 __u32 *p;
201
202 p = btf_add_type_offs_mem(btf, 1);
203 if (!p)
204 return -ENOMEM;
205
206 *p = type_off;
207 return 0;
208}
209
210static void btf_bswap_hdr(struct btf_header *h)
211{
212 h->magic = bswap_16(h->magic);
213 h->hdr_len = bswap_32(h->hdr_len);
214 h->type_off = bswap_32(h->type_off);
215 h->type_len = bswap_32(h->type_len);
216 h->str_off = bswap_32(h->str_off);
217 h->str_len = bswap_32(h->str_len);
218}
219
220static int btf_parse_hdr(struct btf *btf)
221{
222 struct btf_header *hdr = btf->hdr;
223 __u32 meta_left;
224
225 if (btf->raw_size < sizeof(struct btf_header)) {
226 pr_debug("BTF header not found\n");
227 return -EINVAL;
228 }
229
230 if (hdr->magic == bswap_16(BTF_MAGIC)) {
231 btf->swapped_endian = true;
232 if (bswap_32(hdr->hdr_len) != sizeof(struct btf_header)) {
233 pr_warn("Can't load BTF with non-native endianness due to unsupported header length %u\n",
234 bswap_32(hdr->hdr_len));
235 return -ENOTSUP;
236 }
237 btf_bswap_hdr(hdr);
238 } else if (hdr->magic != BTF_MAGIC) {
239 pr_debug("Invalid BTF magic: %x\n", hdr->magic);
240 return -EINVAL;
241 }
242
243 if (btf->raw_size < hdr->hdr_len) {
244 pr_debug("BTF header len %u larger than data size %u\n",
245 hdr->hdr_len, btf->raw_size);
246 return -EINVAL;
247 }
248
249 meta_left = btf->raw_size - hdr->hdr_len;
250 if (meta_left < (long long)hdr->str_off + hdr->str_len) {
251 pr_debug("Invalid BTF total size: %u\n", btf->raw_size);
252 return -EINVAL;
253 }
254
255 if ((long long)hdr->type_off + hdr->type_len > hdr->str_off) {
256 pr_debug("Invalid BTF data sections layout: type data at %u + %u, strings data at %u + %u\n",
257 hdr->type_off, hdr->type_len, hdr->str_off, hdr->str_len);
258 return -EINVAL;
259 }
260
261 if (hdr->type_off % 4) {
262 pr_debug("BTF type section is not aligned to 4 bytes\n");
263 return -EINVAL;
264 }
265
266 return 0;
267}
268
269static int btf_parse_str_sec(struct btf *btf)
270{
271 const struct btf_header *hdr = btf->hdr;
272 const char *start = btf->strs_data;
273 const char *end = start + btf->hdr->str_len;
274
275 if (btf->base_btf && hdr->str_len == 0)
276 return 0;
277 if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_STR_OFFSET || end[-1]) {
278 pr_debug("Invalid BTF string section\n");
279 return -EINVAL;
280 }
281 if (!btf->base_btf && start[0]) {
282 pr_debug("Invalid BTF string section\n");
283 return -EINVAL;
284 }
285 return 0;
286}
287
288static int btf_type_size(const struct btf_type *t)
289{
290 const int base_size = sizeof(struct btf_type);
291 __u16 vlen = btf_vlen(t);
292
293 switch (btf_kind(t)) {
294 case BTF_KIND_FWD:
295 case BTF_KIND_CONST:
296 case BTF_KIND_VOLATILE:
297 case BTF_KIND_RESTRICT:
298 case BTF_KIND_PTR:
299 case BTF_KIND_TYPEDEF:
300 case BTF_KIND_FUNC:
301 case BTF_KIND_FLOAT:
302 case BTF_KIND_TYPE_TAG:
303 return base_size;
304 case BTF_KIND_INT:
305 return base_size + sizeof(__u32);
306 case BTF_KIND_ENUM:
307 return base_size + vlen * sizeof(struct btf_enum);
308 case BTF_KIND_ENUM64:
309 return base_size + vlen * sizeof(struct btf_enum64);
310 case BTF_KIND_ARRAY:
311 return base_size + sizeof(struct btf_array);
312 case BTF_KIND_STRUCT:
313 case BTF_KIND_UNION:
314 return base_size + vlen * sizeof(struct btf_member);
315 case BTF_KIND_FUNC_PROTO:
316 return base_size + vlen * sizeof(struct btf_param);
317 case BTF_KIND_VAR:
318 return base_size + sizeof(struct btf_var);
319 case BTF_KIND_DATASEC:
320 return base_size + vlen * sizeof(struct btf_var_secinfo);
321 case BTF_KIND_DECL_TAG:
322 return base_size + sizeof(struct btf_decl_tag);
323 default:
324 pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
325 return -EINVAL;
326 }
327}
328
329static void btf_bswap_type_base(struct btf_type *t)
330{
331 t->name_off = bswap_32(t->name_off);
332 t->info = bswap_32(t->info);
333 t->type = bswap_32(t->type);
334}
335
336static int btf_bswap_type_rest(struct btf_type *t)
337{
338 struct btf_var_secinfo *v;
339 struct btf_enum64 *e64;
340 struct btf_member *m;
341 struct btf_array *a;
342 struct btf_param *p;
343 struct btf_enum *e;
344 __u16 vlen = btf_vlen(t);
345 int i;
346
347 switch (btf_kind(t)) {
348 case BTF_KIND_FWD:
349 case BTF_KIND_CONST:
350 case BTF_KIND_VOLATILE:
351 case BTF_KIND_RESTRICT:
352 case BTF_KIND_PTR:
353 case BTF_KIND_TYPEDEF:
354 case BTF_KIND_FUNC:
355 case BTF_KIND_FLOAT:
356 case BTF_KIND_TYPE_TAG:
357 return 0;
358 case BTF_KIND_INT:
359 *(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
360 return 0;
361 case BTF_KIND_ENUM:
362 for (i = 0, e = btf_enum(t); i < vlen; i++, e++) {
363 e->name_off = bswap_32(e->name_off);
364 e->val = bswap_32(e->val);
365 }
366 return 0;
367 case BTF_KIND_ENUM64:
368 for (i = 0, e64 = btf_enum64(t); i < vlen; i++, e64++) {
369 e64->name_off = bswap_32(e64->name_off);
370 e64->val_lo32 = bswap_32(e64->val_lo32);
371 e64->val_hi32 = bswap_32(e64->val_hi32);
372 }
373 return 0;
374 case BTF_KIND_ARRAY:
375 a = btf_array(t);
376 a->type = bswap_32(a->type);
377 a->index_type = bswap_32(a->index_type);
378 a->nelems = bswap_32(a->nelems);
379 return 0;
380 case BTF_KIND_STRUCT:
381 case BTF_KIND_UNION:
382 for (i = 0, m = btf_members(t); i < vlen; i++, m++) {
383 m->name_off = bswap_32(m->name_off);
384 m->type = bswap_32(m->type);
385 m->offset = bswap_32(m->offset);
386 }
387 return 0;
388 case BTF_KIND_FUNC_PROTO:
389 for (i = 0, p = btf_params(t); i < vlen; i++, p++) {
390 p->name_off = bswap_32(p->name_off);
391 p->type = bswap_32(p->type);
392 }
393 return 0;
394 case BTF_KIND_VAR:
395 btf_var(t)->linkage = bswap_32(btf_var(t)->linkage);
396 return 0;
397 case BTF_KIND_DATASEC:
398 for (i = 0, v = btf_var_secinfos(t); i < vlen; i++, v++) {
399 v->type = bswap_32(v->type);
400 v->offset = bswap_32(v->offset);
401 v->size = bswap_32(v->size);
402 }
403 return 0;
404 case BTF_KIND_DECL_TAG:
405 btf_decl_tag(t)->component_idx = bswap_32(btf_decl_tag(t)->component_idx);
406 return 0;
407 default:
408 pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
409 return -EINVAL;
410 }
411}
412
413static int btf_parse_type_sec(struct btf *btf)
414{
415 struct btf_header *hdr = btf->hdr;
416 void *next_type = btf->types_data;
417 void *end_type = next_type + hdr->type_len;
418 int err, type_size;
419
420 while (next_type + sizeof(struct btf_type) <= end_type) {
421 if (btf->swapped_endian)
422 btf_bswap_type_base(next_type);
423
424 type_size = btf_type_size(next_type);
425 if (type_size < 0)
426 return type_size;
427 if (next_type + type_size > end_type) {
428 pr_warn("BTF type [%d] is malformed\n", btf->start_id + btf->nr_types);
429 return -EINVAL;
430 }
431
432 if (btf->swapped_endian && btf_bswap_type_rest(next_type))
433 return -EINVAL;
434
435 err = btf_add_type_idx_entry(btf, next_type - btf->types_data);
436 if (err)
437 return err;
438
439 next_type += type_size;
440 btf->nr_types++;
441 }
442
443 if (next_type != end_type) {
444 pr_warn("BTF types data is malformed\n");
445 return -EINVAL;
446 }
447
448 return 0;
449}
450
451static int btf_validate_str(const struct btf *btf, __u32 str_off, const char *what, __u32 type_id)
452{
453 const char *s;
454
455 s = btf__str_by_offset(btf, str_off);
456 if (!s) {
457 pr_warn("btf: type [%u]: invalid %s (string offset %u)\n", type_id, what, str_off);
458 return -EINVAL;
459 }
460
461 return 0;
462}
463
464static int btf_validate_id(const struct btf *btf, __u32 id, __u32 ctx_id)
465{
466 const struct btf_type *t;
467
468 t = btf__type_by_id(btf, id);
469 if (!t) {
470 pr_warn("btf: type [%u]: invalid referenced type ID %u\n", ctx_id, id);
471 return -EINVAL;
472 }
473
474 return 0;
475}
476
477static int btf_validate_type(const struct btf *btf, const struct btf_type *t, __u32 id)
478{
479 __u32 kind = btf_kind(t);
480 int err, i, n;
481
482 err = btf_validate_str(btf, t->name_off, "type name", id);
483 if (err)
484 return err;
485
486 switch (kind) {
487 case BTF_KIND_UNKN:
488 case BTF_KIND_INT:
489 case BTF_KIND_FWD:
490 case BTF_KIND_FLOAT:
491 break;
492 case BTF_KIND_PTR:
493 case BTF_KIND_TYPEDEF:
494 case BTF_KIND_VOLATILE:
495 case BTF_KIND_CONST:
496 case BTF_KIND_RESTRICT:
497 case BTF_KIND_VAR:
498 case BTF_KIND_DECL_TAG:
499 case BTF_KIND_TYPE_TAG:
500 err = btf_validate_id(btf, t->type, id);
501 if (err)
502 return err;
503 break;
504 case BTF_KIND_ARRAY: {
505 const struct btf_array *a = btf_array(t);
506
507 err = btf_validate_id(btf, a->type, id);
508 err = err ?: btf_validate_id(btf, a->index_type, id);
509 if (err)
510 return err;
511 break;
512 }
513 case BTF_KIND_STRUCT:
514 case BTF_KIND_UNION: {
515 const struct btf_member *m = btf_members(t);
516
517 n = btf_vlen(t);
518 for (i = 0; i < n; i++, m++) {
519 err = btf_validate_str(btf, m->name_off, "field name", id);
520 err = err ?: btf_validate_id(btf, m->type, id);
521 if (err)
522 return err;
523 }
524 break;
525 }
526 case BTF_KIND_ENUM: {
527 const struct btf_enum *m = btf_enum(t);
528
529 n = btf_vlen(t);
530 for (i = 0; i < n; i++, m++) {
531 err = btf_validate_str(btf, m->name_off, "enum name", id);
532 if (err)
533 return err;
534 }
535 break;
536 }
537 case BTF_KIND_ENUM64: {
538 const struct btf_enum64 *m = btf_enum64(t);
539
540 n = btf_vlen(t);
541 for (i = 0; i < n; i++, m++) {
542 err = btf_validate_str(btf, m->name_off, "enum name", id);
543 if (err)
544 return err;
545 }
546 break;
547 }
548 case BTF_KIND_FUNC: {
549 const struct btf_type *ft;
550
551 err = btf_validate_id(btf, t->type, id);
552 if (err)
553 return err;
554 ft = btf__type_by_id(btf, t->type);
555 if (btf_kind(ft) != BTF_KIND_FUNC_PROTO) {
556 pr_warn("btf: type [%u]: referenced type [%u] is not FUNC_PROTO\n", id, t->type);
557 return -EINVAL;
558 }
559 break;
560 }
561 case BTF_KIND_FUNC_PROTO: {
562 const struct btf_param *m = btf_params(t);
563
564 n = btf_vlen(t);
565 for (i = 0; i < n; i++, m++) {
566 err = btf_validate_str(btf, m->name_off, "param name", id);
567 err = err ?: btf_validate_id(btf, m->type, id);
568 if (err)
569 return err;
570 }
571 break;
572 }
573 case BTF_KIND_DATASEC: {
574 const struct btf_var_secinfo *m = btf_var_secinfos(t);
575
576 n = btf_vlen(t);
577 for (i = 0; i < n; i++, m++) {
578 err = btf_validate_id(btf, m->type, id);
579 if (err)
580 return err;
581 }
582 break;
583 }
584 default:
585 pr_warn("btf: type [%u]: unrecognized kind %u\n", id, kind);
586 return -EINVAL;
587 }
588 return 0;
589}
590
591/* Validate basic sanity of BTF. It's intentionally less thorough than
592 * kernel's validation and validates only properties of BTF that libbpf relies
593 * on to be correct (e.g., valid type IDs, valid string offsets, etc)
594 */
595static int btf_sanity_check(const struct btf *btf)
596{
597 const struct btf_type *t;
598 __u32 i, n = btf__type_cnt(btf);
599 int err;
600
601 for (i = 1; i < n; i++) {
602 t = btf_type_by_id(btf, i);
603 err = btf_validate_type(btf, t, i);
604 if (err)
605 return err;
606 }
607 return 0;
608}
609
610__u32 btf__type_cnt(const struct btf *btf)
611{
612 return btf->start_id + btf->nr_types;
613}
614
615const struct btf *btf__base_btf(const struct btf *btf)
616{
617 return btf->base_btf;
618}
619
620/* internal helper returning non-const pointer to a type */
621struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id)
622{
623 if (type_id == 0)
624 return &btf_void;
625 if (type_id < btf->start_id)
626 return btf_type_by_id(btf->base_btf, type_id);
627 return btf->types_data + btf->type_offs[type_id - btf->start_id];
628}
629
630const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
631{
632 if (type_id >= btf->start_id + btf->nr_types)
633 return errno = EINVAL, NULL;
634 return btf_type_by_id((struct btf *)btf, type_id);
635}
636
637static int determine_ptr_size(const struct btf *btf)
638{
639 static const char * const long_aliases[] = {
640 "long",
641 "long int",
642 "int long",
643 "unsigned long",
644 "long unsigned",
645 "unsigned long int",
646 "unsigned int long",
647 "long unsigned int",
648 "long int unsigned",
649 "int unsigned long",
650 "int long unsigned",
651 };
652 const struct btf_type *t;
653 const char *name;
654 int i, j, n;
655
656 if (btf->base_btf && btf->base_btf->ptr_sz > 0)
657 return btf->base_btf->ptr_sz;
658
659 n = btf__type_cnt(btf);
660 for (i = 1; i < n; i++) {
661 t = btf__type_by_id(btf, i);
662 if (!btf_is_int(t))
663 continue;
664
665 if (t->size != 4 && t->size != 8)
666 continue;
667
668 name = btf__name_by_offset(btf, t->name_off);
669 if (!name)
670 continue;
671
672 for (j = 0; j < ARRAY_SIZE(long_aliases); j++) {
673 if (strcmp(name, long_aliases[j]) == 0)
674 return t->size;
675 }
676 }
677
678 return -1;
679}
680
681static size_t btf_ptr_sz(const struct btf *btf)
682{
683 if (!btf->ptr_sz)
684 ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
685 return btf->ptr_sz < 0 ? sizeof(void *) : btf->ptr_sz;
686}
687
688/* Return pointer size this BTF instance assumes. The size is heuristically
689 * determined by looking for 'long' or 'unsigned long' integer type and
690 * recording its size in bytes. If BTF type information doesn't have any such
691 * type, this function returns 0. In the latter case, native architecture's
692 * pointer size is assumed, so will be either 4 or 8, depending on
693 * architecture that libbpf was compiled for. It's possible to override
694 * guessed value by using btf__set_pointer_size() API.
695 */
696size_t btf__pointer_size(const struct btf *btf)
697{
698 if (!btf->ptr_sz)
699 ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
700
701 if (btf->ptr_sz < 0)
702 /* not enough BTF type info to guess */
703 return 0;
704
705 return btf->ptr_sz;
706}
707
708/* Override or set pointer size in bytes. Only values of 4 and 8 are
709 * supported.
710 */
711int btf__set_pointer_size(struct btf *btf, size_t ptr_sz)
712{
713 if (ptr_sz != 4 && ptr_sz != 8)
714 return libbpf_err(-EINVAL);
715 btf->ptr_sz = ptr_sz;
716 return 0;
717}
718
719static bool is_host_big_endian(void)
720{
721#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
722 return false;
723#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
724 return true;
725#else
726# error "Unrecognized __BYTE_ORDER__"
727#endif
728}
729
730enum btf_endianness btf__endianness(const struct btf *btf)
731{
732 if (is_host_big_endian())
733 return btf->swapped_endian ? BTF_LITTLE_ENDIAN : BTF_BIG_ENDIAN;
734 else
735 return btf->swapped_endian ? BTF_BIG_ENDIAN : BTF_LITTLE_ENDIAN;
736}
737
738int btf__set_endianness(struct btf *btf, enum btf_endianness endian)
739{
740 if (endian != BTF_LITTLE_ENDIAN && endian != BTF_BIG_ENDIAN)
741 return libbpf_err(-EINVAL);
742
743 btf->swapped_endian = is_host_big_endian() != (endian == BTF_BIG_ENDIAN);
744 if (!btf->swapped_endian) {
745 free(btf->raw_data_swapped);
746 btf->raw_data_swapped = NULL;
747 }
748 return 0;
749}
750
751static bool btf_type_is_void(const struct btf_type *t)
752{
753 return t == &btf_void || btf_is_fwd(t);
754}
755
756static bool btf_type_is_void_or_null(const struct btf_type *t)
757{
758 return !t || btf_type_is_void(t);
759}
760
761#define MAX_RESOLVE_DEPTH 32
762
763__s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
764{
765 const struct btf_array *array;
766 const struct btf_type *t;
767 __u32 nelems = 1;
768 __s64 size = -1;
769 int i;
770
771 t = btf__type_by_id(btf, type_id);
772 for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t); i++) {
773 switch (btf_kind(t)) {
774 case BTF_KIND_INT:
775 case BTF_KIND_STRUCT:
776 case BTF_KIND_UNION:
777 case BTF_KIND_ENUM:
778 case BTF_KIND_ENUM64:
779 case BTF_KIND_DATASEC:
780 case BTF_KIND_FLOAT:
781 size = t->size;
782 goto done;
783 case BTF_KIND_PTR:
784 size = btf_ptr_sz(btf);
785 goto done;
786 case BTF_KIND_TYPEDEF:
787 case BTF_KIND_VOLATILE:
788 case BTF_KIND_CONST:
789 case BTF_KIND_RESTRICT:
790 case BTF_KIND_VAR:
791 case BTF_KIND_DECL_TAG:
792 case BTF_KIND_TYPE_TAG:
793 type_id = t->type;
794 break;
795 case BTF_KIND_ARRAY:
796 array = btf_array(t);
797 if (nelems && array->nelems > UINT32_MAX / nelems)
798 return libbpf_err(-E2BIG);
799 nelems *= array->nelems;
800 type_id = array->type;
801 break;
802 default:
803 return libbpf_err(-EINVAL);
804 }
805
806 t = btf__type_by_id(btf, type_id);
807 }
808
809done:
810 if (size < 0)
811 return libbpf_err(-EINVAL);
812 if (nelems && size > UINT32_MAX / nelems)
813 return libbpf_err(-E2BIG);
814
815 return nelems * size;
816}
817
818int btf__align_of(const struct btf *btf, __u32 id)
819{
820 const struct btf_type *t = btf__type_by_id(btf, id);
821 __u16 kind = btf_kind(t);
822
823 switch (kind) {
824 case BTF_KIND_INT:
825 case BTF_KIND_ENUM:
826 case BTF_KIND_ENUM64:
827 case BTF_KIND_FLOAT:
828 return min(btf_ptr_sz(btf), (size_t)t->size);
829 case BTF_KIND_PTR:
830 return btf_ptr_sz(btf);
831 case BTF_KIND_TYPEDEF:
832 case BTF_KIND_VOLATILE:
833 case BTF_KIND_CONST:
834 case BTF_KIND_RESTRICT:
835 case BTF_KIND_TYPE_TAG:
836 return btf__align_of(btf, t->type);
837 case BTF_KIND_ARRAY:
838 return btf__align_of(btf, btf_array(t)->type);
839 case BTF_KIND_STRUCT:
840 case BTF_KIND_UNION: {
841 const struct btf_member *m = btf_members(t);
842 __u16 vlen = btf_vlen(t);
843 int i, max_align = 1, align;
844
845 for (i = 0; i < vlen; i++, m++) {
846 align = btf__align_of(btf, m->type);
847 if (align <= 0)
848 return libbpf_err(align);
849 max_align = max(max_align, align);
850
851 /* if field offset isn't aligned according to field
852 * type's alignment, then struct must be packed
853 */
854 if (btf_member_bitfield_size(t, i) == 0 &&
855 (m->offset % (8 * align)) != 0)
856 return 1;
857 }
858
859 /* if struct/union size isn't a multiple of its alignment,
860 * then struct must be packed
861 */
862 if ((t->size % max_align) != 0)
863 return 1;
864
865 return max_align;
866 }
867 default:
868 pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
869 return errno = EINVAL, 0;
870 }
871}
872
873int btf__resolve_type(const struct btf *btf, __u32 type_id)
874{
875 const struct btf_type *t;
876 int depth = 0;
877
878 t = btf__type_by_id(btf, type_id);
879 while (depth < MAX_RESOLVE_DEPTH &&
880 !btf_type_is_void_or_null(t) &&
881 (btf_is_mod(t) || btf_is_typedef(t) || btf_is_var(t))) {
882 type_id = t->type;
883 t = btf__type_by_id(btf, type_id);
884 depth++;
885 }
886
887 if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
888 return libbpf_err(-EINVAL);
889
890 return type_id;
891}
892
893__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
894{
895 __u32 i, nr_types = btf__type_cnt(btf);
896
897 if (!strcmp(type_name, "void"))
898 return 0;
899
900 for (i = 1; i < nr_types; i++) {
901 const struct btf_type *t = btf__type_by_id(btf, i);
902 const char *name = btf__name_by_offset(btf, t->name_off);
903
904 if (name && !strcmp(type_name, name))
905 return i;
906 }
907
908 return libbpf_err(-ENOENT);
909}
910
911static __s32 btf_find_by_name_kind(const struct btf *btf, int start_id,
912 const char *type_name, __u32 kind)
913{
914 __u32 i, nr_types = btf__type_cnt(btf);
915
916 if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void"))
917 return 0;
918
919 for (i = start_id; i < nr_types; i++) {
920 const struct btf_type *t = btf__type_by_id(btf, i);
921 const char *name;
922
923 if (btf_kind(t) != kind)
924 continue;
925 name = btf__name_by_offset(btf, t->name_off);
926 if (name && !strcmp(type_name, name))
927 return i;
928 }
929
930 return libbpf_err(-ENOENT);
931}
932
933__s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name,
934 __u32 kind)
935{
936 return btf_find_by_name_kind(btf, btf->start_id, type_name, kind);
937}
938
939__s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
940 __u32 kind)
941{
942 return btf_find_by_name_kind(btf, 1, type_name, kind);
943}
944
945static bool btf_is_modifiable(const struct btf *btf)
946{
947 return (void *)btf->hdr != btf->raw_data;
948}
949
950void btf__free(struct btf *btf)
951{
952 if (IS_ERR_OR_NULL(btf))
953 return;
954
955 if (btf->fd >= 0)
956 close(btf->fd);
957
958 if (btf_is_modifiable(btf)) {
959 /* if BTF was modified after loading, it will have a split
960 * in-memory representation for header, types, and strings
961 * sections, so we need to free all of them individually. It
962 * might still have a cached contiguous raw data present,
963 * which will be unconditionally freed below.
964 */
965 free(btf->hdr);
966 free(btf->types_data);
967 strset__free(btf->strs_set);
968 }
969 free(btf->raw_data);
970 free(btf->raw_data_swapped);
971 free(btf->type_offs);
972 free(btf);
973}
974
975static struct btf *btf_new_empty(struct btf *base_btf)
976{
977 struct btf *btf;
978
979 btf = calloc(1, sizeof(*btf));
980 if (!btf)
981 return ERR_PTR(-ENOMEM);
982
983 btf->nr_types = 0;
984 btf->start_id = 1;
985 btf->start_str_off = 0;
986 btf->fd = -1;
987 btf->ptr_sz = sizeof(void *);
988 btf->swapped_endian = false;
989
990 if (base_btf) {
991 btf->base_btf = base_btf;
992 btf->start_id = btf__type_cnt(base_btf);
993 btf->start_str_off = base_btf->hdr->str_len;
994 }
995
996 /* +1 for empty string at offset 0 */
997 btf->raw_size = sizeof(struct btf_header) + (base_btf ? 0 : 1);
998 btf->raw_data = calloc(1, btf->raw_size);
999 if (!btf->raw_data) {
1000 free(btf);
1001 return ERR_PTR(-ENOMEM);
1002 }
1003
1004 btf->hdr = btf->raw_data;
1005 btf->hdr->hdr_len = sizeof(struct btf_header);
1006 btf->hdr->magic = BTF_MAGIC;
1007 btf->hdr->version = BTF_VERSION;
1008
1009 btf->types_data = btf->raw_data + btf->hdr->hdr_len;
1010 btf->strs_data = btf->raw_data + btf->hdr->hdr_len;
1011 btf->hdr->str_len = base_btf ? 0 : 1; /* empty string at offset 0 */
1012
1013 return btf;
1014}
1015
1016struct btf *btf__new_empty(void)
1017{
1018 return libbpf_ptr(btf_new_empty(NULL));
1019}
1020
1021struct btf *btf__new_empty_split(struct btf *base_btf)
1022{
1023 return libbpf_ptr(btf_new_empty(base_btf));
1024}
1025
1026static struct btf *btf_new(const void *data, __u32 size, struct btf *base_btf)
1027{
1028 struct btf *btf;
1029 int err;
1030
1031 btf = calloc(1, sizeof(struct btf));
1032 if (!btf)
1033 return ERR_PTR(-ENOMEM);
1034
1035 btf->nr_types = 0;
1036 btf->start_id = 1;
1037 btf->start_str_off = 0;
1038 btf->fd = -1;
1039
1040 if (base_btf) {
1041 btf->base_btf = base_btf;
1042 btf->start_id = btf__type_cnt(base_btf);
1043 btf->start_str_off = base_btf->hdr->str_len;
1044 }
1045
1046 btf->raw_data = malloc(size);
1047 if (!btf->raw_data) {
1048 err = -ENOMEM;
1049 goto done;
1050 }
1051 memcpy(btf->raw_data, data, size);
1052 btf->raw_size = size;
1053
1054 btf->hdr = btf->raw_data;
1055 err = btf_parse_hdr(btf);
1056 if (err)
1057 goto done;
1058
1059 btf->strs_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->str_off;
1060 btf->types_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->type_off;
1061
1062 err = btf_parse_str_sec(btf);
1063 err = err ?: btf_parse_type_sec(btf);
1064 err = err ?: btf_sanity_check(btf);
1065 if (err)
1066 goto done;
1067
1068done:
1069 if (err) {
1070 btf__free(btf);
1071 return ERR_PTR(err);
1072 }
1073
1074 return btf;
1075}
1076
1077struct btf *btf__new(const void *data, __u32 size)
1078{
1079 return libbpf_ptr(btf_new(data, size, NULL));
1080}
1081
1082struct btf *btf__new_split(const void *data, __u32 size, struct btf *base_btf)
1083{
1084 return libbpf_ptr(btf_new(data, size, base_btf));
1085}
1086
1087static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
1088 struct btf_ext **btf_ext)
1089{
1090 Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
1091 int err = 0, fd = -1, idx = 0;
1092 struct btf *btf = NULL;
1093 Elf_Scn *scn = NULL;
1094 Elf *elf = NULL;
1095 GElf_Ehdr ehdr;
1096 size_t shstrndx;
1097
1098 if (elf_version(EV_CURRENT) == EV_NONE) {
1099 pr_warn("failed to init libelf for %s\n", path);
1100 return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
1101 }
1102
1103 fd = open(path, O_RDONLY | O_CLOEXEC);
1104 if (fd < 0) {
1105 err = -errno;
1106 pr_warn("failed to open %s: %s\n", path, strerror(errno));
1107 return ERR_PTR(err);
1108 }
1109
1110 err = -LIBBPF_ERRNO__FORMAT;
1111
1112 elf = elf_begin(fd, ELF_C_READ, NULL);
1113 if (!elf) {
1114 pr_warn("failed to open %s as ELF file\n", path);
1115 goto done;
1116 }
1117 if (!gelf_getehdr(elf, &ehdr)) {
1118 pr_warn("failed to get EHDR from %s\n", path);
1119 goto done;
1120 }
1121
1122 if (elf_getshdrstrndx(elf, &shstrndx)) {
1123 pr_warn("failed to get section names section index for %s\n",
1124 path);
1125 goto done;
1126 }
1127
1128 if (!elf_rawdata(elf_getscn(elf, shstrndx), NULL)) {
1129 pr_warn("failed to get e_shstrndx from %s\n", path);
1130 goto done;
1131 }
1132
1133 while ((scn = elf_nextscn(elf, scn)) != NULL) {
1134 GElf_Shdr sh;
1135 char *name;
1136
1137 idx++;
1138 if (gelf_getshdr(scn, &sh) != &sh) {
1139 pr_warn("failed to get section(%d) header from %s\n",
1140 idx, path);
1141 goto done;
1142 }
1143 name = elf_strptr(elf, shstrndx, sh.sh_name);
1144 if (!name) {
1145 pr_warn("failed to get section(%d) name from %s\n",
1146 idx, path);
1147 goto done;
1148 }
1149 if (strcmp(name, BTF_ELF_SEC) == 0) {
1150 btf_data = elf_getdata(scn, 0);
1151 if (!btf_data) {
1152 pr_warn("failed to get section(%d, %s) data from %s\n",
1153 idx, name, path);
1154 goto done;
1155 }
1156 continue;
1157 } else if (btf_ext && strcmp(name, BTF_EXT_ELF_SEC) == 0) {
1158 btf_ext_data = elf_getdata(scn, 0);
1159 if (!btf_ext_data) {
1160 pr_warn("failed to get section(%d, %s) data from %s\n",
1161 idx, name, path);
1162 goto done;
1163 }
1164 continue;
1165 }
1166 }
1167
1168 if (!btf_data) {
1169 pr_warn("failed to find '%s' ELF section in %s\n", BTF_ELF_SEC, path);
1170 err = -ENODATA;
1171 goto done;
1172 }
1173 btf = btf_new(btf_data->d_buf, btf_data->d_size, base_btf);
1174 err = libbpf_get_error(btf);
1175 if (err)
1176 goto done;
1177
1178 switch (gelf_getclass(elf)) {
1179 case ELFCLASS32:
1180 btf__set_pointer_size(btf, 4);
1181 break;
1182 case ELFCLASS64:
1183 btf__set_pointer_size(btf, 8);
1184 break;
1185 default:
1186 pr_warn("failed to get ELF class (bitness) for %s\n", path);
1187 break;
1188 }
1189
1190 if (btf_ext && btf_ext_data) {
1191 *btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
1192 err = libbpf_get_error(*btf_ext);
1193 if (err)
1194 goto done;
1195 } else if (btf_ext) {
1196 *btf_ext = NULL;
1197 }
1198done:
1199 if (elf)
1200 elf_end(elf);
1201 close(fd);
1202
1203 if (!err)
1204 return btf;
1205
1206 if (btf_ext)
1207 btf_ext__free(*btf_ext);
1208 btf__free(btf);
1209
1210 return ERR_PTR(err);
1211}
1212
1213struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
1214{
1215 return libbpf_ptr(btf_parse_elf(path, NULL, btf_ext));
1216}
1217
1218struct btf *btf__parse_elf_split(const char *path, struct btf *base_btf)
1219{
1220 return libbpf_ptr(btf_parse_elf(path, base_btf, NULL));
1221}
1222
1223static struct btf *btf_parse_raw(const char *path, struct btf *base_btf)
1224{
1225 struct btf *btf = NULL;
1226 void *data = NULL;
1227 FILE *f = NULL;
1228 __u16 magic;
1229 int err = 0;
1230 long sz;
1231
1232 f = fopen(path, "rbe");
1233 if (!f) {
1234 err = -errno;
1235 goto err_out;
1236 }
1237
1238 /* check BTF magic */
1239 if (fread(&magic, 1, sizeof(magic), f) < sizeof(magic)) {
1240 err = -EIO;
1241 goto err_out;
1242 }
1243 if (magic != BTF_MAGIC && magic != bswap_16(BTF_MAGIC)) {
1244 /* definitely not a raw BTF */
1245 err = -EPROTO;
1246 goto err_out;
1247 }
1248
1249 /* get file size */
1250 if (fseek(f, 0, SEEK_END)) {
1251 err = -errno;
1252 goto err_out;
1253 }
1254 sz = ftell(f);
1255 if (sz < 0) {
1256 err = -errno;
1257 goto err_out;
1258 }
1259 /* rewind to the start */
1260 if (fseek(f, 0, SEEK_SET)) {
1261 err = -errno;
1262 goto err_out;
1263 }
1264
1265 /* pre-alloc memory and read all of BTF data */
1266 data = malloc(sz);
1267 if (!data) {
1268 err = -ENOMEM;
1269 goto err_out;
1270 }
1271 if (fread(data, 1, sz, f) < sz) {
1272 err = -EIO;
1273 goto err_out;
1274 }
1275
1276 /* finally parse BTF data */
1277 btf = btf_new(data, sz, base_btf);
1278
1279err_out:
1280 free(data);
1281 if (f)
1282 fclose(f);
1283 return err ? ERR_PTR(err) : btf;
1284}
1285
1286struct btf *btf__parse_raw(const char *path)
1287{
1288 return libbpf_ptr(btf_parse_raw(path, NULL));
1289}
1290
1291struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf)
1292{
1293 return libbpf_ptr(btf_parse_raw(path, base_btf));
1294}
1295
1296static struct btf *btf_parse(const char *path, struct btf *base_btf, struct btf_ext **btf_ext)
1297{
1298 struct btf *btf;
1299 int err;
1300
1301 if (btf_ext)
1302 *btf_ext = NULL;
1303
1304 btf = btf_parse_raw(path, base_btf);
1305 err = libbpf_get_error(btf);
1306 if (!err)
1307 return btf;
1308 if (err != -EPROTO)
1309 return ERR_PTR(err);
1310 return btf_parse_elf(path, base_btf, btf_ext);
1311}
1312
1313struct btf *btf__parse(const char *path, struct btf_ext **btf_ext)
1314{
1315 return libbpf_ptr(btf_parse(path, NULL, btf_ext));
1316}
1317
1318struct btf *btf__parse_split(const char *path, struct btf *base_btf)
1319{
1320 return libbpf_ptr(btf_parse(path, base_btf, NULL));
1321}
1322
1323static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian);
1324
1325int btf_load_into_kernel(struct btf *btf,
1326 char *log_buf, size_t log_sz, __u32 log_level,
1327 int token_fd)
1328{
1329 LIBBPF_OPTS(bpf_btf_load_opts, opts);
1330 __u32 buf_sz = 0, raw_size;
1331 char *buf = NULL, *tmp;
1332 void *raw_data;
1333 int err = 0;
1334
1335 if (btf->fd >= 0)
1336 return libbpf_err(-EEXIST);
1337 if (log_sz && !log_buf)
1338 return libbpf_err(-EINVAL);
1339
1340 /* cache native raw data representation */
1341 raw_data = btf_get_raw_data(btf, &raw_size, false);
1342 if (!raw_data) {
1343 err = -ENOMEM;
1344 goto done;
1345 }
1346 btf->raw_size = raw_size;
1347 btf->raw_data = raw_data;
1348
1349retry_load:
1350 /* if log_level is 0, we won't provide log_buf/log_size to the kernel,
1351 * initially. Only if BTF loading fails, we bump log_level to 1 and
1352 * retry, using either auto-allocated or custom log_buf. This way
1353 * non-NULL custom log_buf provides a buffer just in case, but hopes
1354 * for successful load and no need for log_buf.
1355 */
1356 if (log_level) {
1357 /* if caller didn't provide custom log_buf, we'll keep
1358 * allocating our own progressively bigger buffers for BTF
1359 * verification log
1360 */
1361 if (!log_buf) {
1362 buf_sz = max((__u32)BPF_LOG_BUF_SIZE, buf_sz * 2);
1363 tmp = realloc(buf, buf_sz);
1364 if (!tmp) {
1365 err = -ENOMEM;
1366 goto done;
1367 }
1368 buf = tmp;
1369 buf[0] = '\0';
1370 }
1371
1372 opts.log_buf = log_buf ? log_buf : buf;
1373 opts.log_size = log_buf ? log_sz : buf_sz;
1374 opts.log_level = log_level;
1375 }
1376
1377 opts.token_fd = token_fd;
1378 if (token_fd)
1379 opts.btf_flags |= BPF_F_TOKEN_FD;
1380
1381 btf->fd = bpf_btf_load(raw_data, raw_size, &opts);
1382 if (btf->fd < 0) {
1383 /* time to turn on verbose mode and try again */
1384 if (log_level == 0) {
1385 log_level = 1;
1386 goto retry_load;
1387 }
1388 /* only retry if caller didn't provide custom log_buf, but
1389 * make sure we can never overflow buf_sz
1390 */
1391 if (!log_buf && errno == ENOSPC && buf_sz <= UINT_MAX / 2)
1392 goto retry_load;
1393
1394 err = -errno;
1395 pr_warn("BTF loading error: %d\n", err);
1396 /* don't print out contents of custom log_buf */
1397 if (!log_buf && buf[0])
1398 pr_warn("-- BEGIN BTF LOAD LOG ---\n%s\n-- END BTF LOAD LOG --\n", buf);
1399 }
1400
1401done:
1402 free(buf);
1403 return libbpf_err(err);
1404}
1405
1406int btf__load_into_kernel(struct btf *btf)
1407{
1408 return btf_load_into_kernel(btf, NULL, 0, 0, 0);
1409}
1410
1411int btf__fd(const struct btf *btf)
1412{
1413 return btf->fd;
1414}
1415
1416void btf__set_fd(struct btf *btf, int fd)
1417{
1418 btf->fd = fd;
1419}
1420
1421static const void *btf_strs_data(const struct btf *btf)
1422{
1423 return btf->strs_data ? btf->strs_data : strset__data(btf->strs_set);
1424}
1425
1426static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian)
1427{
1428 struct btf_header *hdr = btf->hdr;
1429 struct btf_type *t;
1430 void *data, *p;
1431 __u32 data_sz;
1432 int i;
1433
1434 data = swap_endian ? btf->raw_data_swapped : btf->raw_data;
1435 if (data) {
1436 *size = btf->raw_size;
1437 return data;
1438 }
1439
1440 data_sz = hdr->hdr_len + hdr->type_len + hdr->str_len;
1441 data = calloc(1, data_sz);
1442 if (!data)
1443 return NULL;
1444 p = data;
1445
1446 memcpy(p, hdr, hdr->hdr_len);
1447 if (swap_endian)
1448 btf_bswap_hdr(p);
1449 p += hdr->hdr_len;
1450
1451 memcpy(p, btf->types_data, hdr->type_len);
1452 if (swap_endian) {
1453 for (i = 0; i < btf->nr_types; i++) {
1454 t = p + btf->type_offs[i];
1455 /* btf_bswap_type_rest() relies on native t->info, so
1456 * we swap base type info after we swapped all the
1457 * additional information
1458 */
1459 if (btf_bswap_type_rest(t))
1460 goto err_out;
1461 btf_bswap_type_base(t);
1462 }
1463 }
1464 p += hdr->type_len;
1465
1466 memcpy(p, btf_strs_data(btf), hdr->str_len);
1467 p += hdr->str_len;
1468
1469 *size = data_sz;
1470 return data;
1471err_out:
1472 free(data);
1473 return NULL;
1474}
1475
1476const void *btf__raw_data(const struct btf *btf_ro, __u32 *size)
1477{
1478 struct btf *btf = (struct btf *)btf_ro;
1479 __u32 data_sz;
1480 void *data;
1481
1482 data = btf_get_raw_data(btf, &data_sz, btf->swapped_endian);
1483 if (!data)
1484 return errno = ENOMEM, NULL;
1485
1486 btf->raw_size = data_sz;
1487 if (btf->swapped_endian)
1488 btf->raw_data_swapped = data;
1489 else
1490 btf->raw_data = data;
1491 *size = data_sz;
1492 return data;
1493}
1494
1495__attribute__((alias("btf__raw_data")))
1496const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
1497
1498const char *btf__str_by_offset(const struct btf *btf, __u32 offset)
1499{
1500 if (offset < btf->start_str_off)
1501 return btf__str_by_offset(btf->base_btf, offset);
1502 else if (offset - btf->start_str_off < btf->hdr->str_len)
1503 return btf_strs_data(btf) + (offset - btf->start_str_off);
1504 else
1505 return errno = EINVAL, NULL;
1506}
1507
1508const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
1509{
1510 return btf__str_by_offset(btf, offset);
1511}
1512
1513struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf)
1514{
1515 struct bpf_btf_info btf_info;
1516 __u32 len = sizeof(btf_info);
1517 __u32 last_size;
1518 struct btf *btf;
1519 void *ptr;
1520 int err;
1521
1522 /* we won't know btf_size until we call bpf_btf_get_info_by_fd(). so
1523 * let's start with a sane default - 4KiB here - and resize it only if
1524 * bpf_btf_get_info_by_fd() needs a bigger buffer.
1525 */
1526 last_size = 4096;
1527 ptr = malloc(last_size);
1528 if (!ptr)
1529 return ERR_PTR(-ENOMEM);
1530
1531 memset(&btf_info, 0, sizeof(btf_info));
1532 btf_info.btf = ptr_to_u64(ptr);
1533 btf_info.btf_size = last_size;
1534 err = bpf_btf_get_info_by_fd(btf_fd, &btf_info, &len);
1535
1536 if (!err && btf_info.btf_size > last_size) {
1537 void *temp_ptr;
1538
1539 last_size = btf_info.btf_size;
1540 temp_ptr = realloc(ptr, last_size);
1541 if (!temp_ptr) {
1542 btf = ERR_PTR(-ENOMEM);
1543 goto exit_free;
1544 }
1545 ptr = temp_ptr;
1546
1547 len = sizeof(btf_info);
1548 memset(&btf_info, 0, sizeof(btf_info));
1549 btf_info.btf = ptr_to_u64(ptr);
1550 btf_info.btf_size = last_size;
1551
1552 err = bpf_btf_get_info_by_fd(btf_fd, &btf_info, &len);
1553 }
1554
1555 if (err || btf_info.btf_size > last_size) {
1556 btf = err ? ERR_PTR(-errno) : ERR_PTR(-E2BIG);
1557 goto exit_free;
1558 }
1559
1560 btf = btf_new(ptr, btf_info.btf_size, base_btf);
1561
1562exit_free:
1563 free(ptr);
1564 return btf;
1565}
1566
1567struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf)
1568{
1569 struct btf *btf;
1570 int btf_fd;
1571
1572 btf_fd = bpf_btf_get_fd_by_id(id);
1573 if (btf_fd < 0)
1574 return libbpf_err_ptr(-errno);
1575
1576 btf = btf_get_from_fd(btf_fd, base_btf);
1577 close(btf_fd);
1578
1579 return libbpf_ptr(btf);
1580}
1581
1582struct btf *btf__load_from_kernel_by_id(__u32 id)
1583{
1584 return btf__load_from_kernel_by_id_split(id, NULL);
1585}
1586
1587static void btf_invalidate_raw_data(struct btf *btf)
1588{
1589 if (btf->raw_data) {
1590 free(btf->raw_data);
1591 btf->raw_data = NULL;
1592 }
1593 if (btf->raw_data_swapped) {
1594 free(btf->raw_data_swapped);
1595 btf->raw_data_swapped = NULL;
1596 }
1597}
1598
1599/* Ensure BTF is ready to be modified (by splitting into a three memory
1600 * regions for header, types, and strings). Also invalidate cached
1601 * raw_data, if any.
1602 */
1603static int btf_ensure_modifiable(struct btf *btf)
1604{
1605 void *hdr, *types;
1606 struct strset *set = NULL;
1607 int err = -ENOMEM;
1608
1609 if (btf_is_modifiable(btf)) {
1610 /* any BTF modification invalidates raw_data */
1611 btf_invalidate_raw_data(btf);
1612 return 0;
1613 }
1614
1615 /* split raw data into three memory regions */
1616 hdr = malloc(btf->hdr->hdr_len);
1617 types = malloc(btf->hdr->type_len);
1618 if (!hdr || !types)
1619 goto err_out;
1620
1621 memcpy(hdr, btf->hdr, btf->hdr->hdr_len);
1622 memcpy(types, btf->types_data, btf->hdr->type_len);
1623
1624 /* build lookup index for all strings */
1625 set = strset__new(BTF_MAX_STR_OFFSET, btf->strs_data, btf->hdr->str_len);
1626 if (IS_ERR(set)) {
1627 err = PTR_ERR(set);
1628 goto err_out;
1629 }
1630
1631 /* only when everything was successful, update internal state */
1632 btf->hdr = hdr;
1633 btf->types_data = types;
1634 btf->types_data_cap = btf->hdr->type_len;
1635 btf->strs_data = NULL;
1636 btf->strs_set = set;
1637 /* if BTF was created from scratch, all strings are guaranteed to be
1638 * unique and deduplicated
1639 */
1640 if (btf->hdr->str_len == 0)
1641 btf->strs_deduped = true;
1642 if (!btf->base_btf && btf->hdr->str_len == 1)
1643 btf->strs_deduped = true;
1644
1645 /* invalidate raw_data representation */
1646 btf_invalidate_raw_data(btf);
1647
1648 return 0;
1649
1650err_out:
1651 strset__free(set);
1652 free(hdr);
1653 free(types);
1654 return err;
1655}
1656
1657/* Find an offset in BTF string section that corresponds to a given string *s*.
1658 * Returns:
1659 * - >0 offset into string section, if string is found;
1660 * - -ENOENT, if string is not in the string section;
1661 * - <0, on any other error.
1662 */
1663int btf__find_str(struct btf *btf, const char *s)
1664{
1665 int off;
1666
1667 if (btf->base_btf) {
1668 off = btf__find_str(btf->base_btf, s);
1669 if (off != -ENOENT)
1670 return off;
1671 }
1672
1673 /* BTF needs to be in a modifiable state to build string lookup index */
1674 if (btf_ensure_modifiable(btf))
1675 return libbpf_err(-ENOMEM);
1676
1677 off = strset__find_str(btf->strs_set, s);
1678 if (off < 0)
1679 return libbpf_err(off);
1680
1681 return btf->start_str_off + off;
1682}
1683
1684/* Add a string s to the BTF string section.
1685 * Returns:
1686 * - > 0 offset into string section, on success;
1687 * - < 0, on error.
1688 */
1689int btf__add_str(struct btf *btf, const char *s)
1690{
1691 int off;
1692
1693 if (btf->base_btf) {
1694 off = btf__find_str(btf->base_btf, s);
1695 if (off != -ENOENT)
1696 return off;
1697 }
1698
1699 if (btf_ensure_modifiable(btf))
1700 return libbpf_err(-ENOMEM);
1701
1702 off = strset__add_str(btf->strs_set, s);
1703 if (off < 0)
1704 return libbpf_err(off);
1705
1706 btf->hdr->str_len = strset__data_size(btf->strs_set);
1707
1708 return btf->start_str_off + off;
1709}
1710
1711static void *btf_add_type_mem(struct btf *btf, size_t add_sz)
1712{
1713 return libbpf_add_mem(&btf->types_data, &btf->types_data_cap, 1,
1714 btf->hdr->type_len, UINT_MAX, add_sz);
1715}
1716
1717static void btf_type_inc_vlen(struct btf_type *t)
1718{
1719 t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, btf_kflag(t));
1720}
1721
1722static int btf_commit_type(struct btf *btf, int data_sz)
1723{
1724 int err;
1725
1726 err = btf_add_type_idx_entry(btf, btf->hdr->type_len);
1727 if (err)
1728 return libbpf_err(err);
1729
1730 btf->hdr->type_len += data_sz;
1731 btf->hdr->str_off += data_sz;
1732 btf->nr_types++;
1733 return btf->start_id + btf->nr_types - 1;
1734}
1735
1736struct btf_pipe {
1737 const struct btf *src;
1738 struct btf *dst;
1739 struct hashmap *str_off_map; /* map string offsets from src to dst */
1740};
1741
1742static int btf_rewrite_str(__u32 *str_off, void *ctx)
1743{
1744 struct btf_pipe *p = ctx;
1745 long mapped_off;
1746 int off, err;
1747
1748 if (!*str_off) /* nothing to do for empty strings */
1749 return 0;
1750
1751 if (p->str_off_map &&
1752 hashmap__find(p->str_off_map, *str_off, &mapped_off)) {
1753 *str_off = mapped_off;
1754 return 0;
1755 }
1756
1757 off = btf__add_str(p->dst, btf__str_by_offset(p->src, *str_off));
1758 if (off < 0)
1759 return off;
1760
1761 /* Remember string mapping from src to dst. It avoids
1762 * performing expensive string comparisons.
1763 */
1764 if (p->str_off_map) {
1765 err = hashmap__append(p->str_off_map, *str_off, off);
1766 if (err)
1767 return err;
1768 }
1769
1770 *str_off = off;
1771 return 0;
1772}
1773
1774int btf__add_type(struct btf *btf, const struct btf *src_btf, const struct btf_type *src_type)
1775{
1776 struct btf_pipe p = { .src = src_btf, .dst = btf };
1777 struct btf_type *t;
1778 int sz, err;
1779
1780 sz = btf_type_size(src_type);
1781 if (sz < 0)
1782 return libbpf_err(sz);
1783
1784 /* deconstruct BTF, if necessary, and invalidate raw_data */
1785 if (btf_ensure_modifiable(btf))
1786 return libbpf_err(-ENOMEM);
1787
1788 t = btf_add_type_mem(btf, sz);
1789 if (!t)
1790 return libbpf_err(-ENOMEM);
1791
1792 memcpy(t, src_type, sz);
1793
1794 err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
1795 if (err)
1796 return libbpf_err(err);
1797
1798 return btf_commit_type(btf, sz);
1799}
1800
1801static int btf_rewrite_type_ids(__u32 *type_id, void *ctx)
1802{
1803 struct btf *btf = ctx;
1804
1805 if (!*type_id) /* nothing to do for VOID references */
1806 return 0;
1807
1808 /* we haven't updated btf's type count yet, so
1809 * btf->start_id + btf->nr_types - 1 is the type ID offset we should
1810 * add to all newly added BTF types
1811 */
1812 *type_id += btf->start_id + btf->nr_types - 1;
1813 return 0;
1814}
1815
1816static size_t btf_dedup_identity_hash_fn(long key, void *ctx);
1817static bool btf_dedup_equal_fn(long k1, long k2, void *ctx);
1818
1819int btf__add_btf(struct btf *btf, const struct btf *src_btf)
1820{
1821 struct btf_pipe p = { .src = src_btf, .dst = btf };
1822 int data_sz, sz, cnt, i, err, old_strs_len;
1823 __u32 *off;
1824 void *t;
1825
1826 /* appending split BTF isn't supported yet */
1827 if (src_btf->base_btf)
1828 return libbpf_err(-ENOTSUP);
1829
1830 /* deconstruct BTF, if necessary, and invalidate raw_data */
1831 if (btf_ensure_modifiable(btf))
1832 return libbpf_err(-ENOMEM);
1833
1834 /* remember original strings section size if we have to roll back
1835 * partial strings section changes
1836 */
1837 old_strs_len = btf->hdr->str_len;
1838
1839 data_sz = src_btf->hdr->type_len;
1840 cnt = btf__type_cnt(src_btf) - 1;
1841
1842 /* pre-allocate enough memory for new types */
1843 t = btf_add_type_mem(btf, data_sz);
1844 if (!t)
1845 return libbpf_err(-ENOMEM);
1846
1847 /* pre-allocate enough memory for type offset index for new types */
1848 off = btf_add_type_offs_mem(btf, cnt);
1849 if (!off)
1850 return libbpf_err(-ENOMEM);
1851
1852 /* Map the string offsets from src_btf to the offsets from btf to improve performance */
1853 p.str_off_map = hashmap__new(btf_dedup_identity_hash_fn, btf_dedup_equal_fn, NULL);
1854 if (IS_ERR(p.str_off_map))
1855 return libbpf_err(-ENOMEM);
1856
1857 /* bulk copy types data for all types from src_btf */
1858 memcpy(t, src_btf->types_data, data_sz);
1859
1860 for (i = 0; i < cnt; i++) {
1861 sz = btf_type_size(t);
1862 if (sz < 0) {
1863 /* unlikely, has to be corrupted src_btf */
1864 err = sz;
1865 goto err_out;
1866 }
1867
1868 /* fill out type ID to type offset mapping for lookups by type ID */
1869 *off = t - btf->types_data;
1870
1871 /* add, dedup, and remap strings referenced by this BTF type */
1872 err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
1873 if (err)
1874 goto err_out;
1875
1876 /* remap all type IDs referenced from this BTF type */
1877 err = btf_type_visit_type_ids(t, btf_rewrite_type_ids, btf);
1878 if (err)
1879 goto err_out;
1880
1881 /* go to next type data and type offset index entry */
1882 t += sz;
1883 off++;
1884 }
1885
1886 /* Up until now any of the copied type data was effectively invisible,
1887 * so if we exited early before this point due to error, BTF would be
1888 * effectively unmodified. There would be extra internal memory
1889 * pre-allocated, but it would not be available for querying. But now
1890 * that we've copied and rewritten all the data successfully, we can
1891 * update type count and various internal offsets and sizes to
1892 * "commit" the changes and made them visible to the outside world.
1893 */
1894 btf->hdr->type_len += data_sz;
1895 btf->hdr->str_off += data_sz;
1896 btf->nr_types += cnt;
1897
1898 hashmap__free(p.str_off_map);
1899
1900 /* return type ID of the first added BTF type */
1901 return btf->start_id + btf->nr_types - cnt;
1902err_out:
1903 /* zero out preallocated memory as if it was just allocated with
1904 * libbpf_add_mem()
1905 */
1906 memset(btf->types_data + btf->hdr->type_len, 0, data_sz);
1907 memset(btf->strs_data + old_strs_len, 0, btf->hdr->str_len - old_strs_len);
1908
1909 /* and now restore original strings section size; types data size
1910 * wasn't modified, so doesn't need restoring, see big comment above
1911 */
1912 btf->hdr->str_len = old_strs_len;
1913
1914 hashmap__free(p.str_off_map);
1915
1916 return libbpf_err(err);
1917}
1918
1919/*
1920 * Append new BTF_KIND_INT type with:
1921 * - *name* - non-empty, non-NULL type name;
1922 * - *sz* - power-of-2 (1, 2, 4, ..) size of the type, in bytes;
1923 * - encoding is a combination of BTF_INT_SIGNED, BTF_INT_CHAR, BTF_INT_BOOL.
1924 * Returns:
1925 * - >0, type ID of newly added BTF type;
1926 * - <0, on error.
1927 */
1928int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding)
1929{
1930 struct btf_type *t;
1931 int sz, name_off;
1932
1933 /* non-empty name */
1934 if (!name || !name[0])
1935 return libbpf_err(-EINVAL);
1936 /* byte_sz must be power of 2 */
1937 if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 16)
1938 return libbpf_err(-EINVAL);
1939 if (encoding & ~(BTF_INT_SIGNED | BTF_INT_CHAR | BTF_INT_BOOL))
1940 return libbpf_err(-EINVAL);
1941
1942 /* deconstruct BTF, if necessary, and invalidate raw_data */
1943 if (btf_ensure_modifiable(btf))
1944 return libbpf_err(-ENOMEM);
1945
1946 sz = sizeof(struct btf_type) + sizeof(int);
1947 t = btf_add_type_mem(btf, sz);
1948 if (!t)
1949 return libbpf_err(-ENOMEM);
1950
1951 /* if something goes wrong later, we might end up with an extra string,
1952 * but that shouldn't be a problem, because BTF can't be constructed
1953 * completely anyway and will most probably be just discarded
1954 */
1955 name_off = btf__add_str(btf, name);
1956 if (name_off < 0)
1957 return name_off;
1958
1959 t->name_off = name_off;
1960 t->info = btf_type_info(BTF_KIND_INT, 0, 0);
1961 t->size = byte_sz;
1962 /* set INT info, we don't allow setting legacy bit offset/size */
1963 *(__u32 *)(t + 1) = (encoding << 24) | (byte_sz * 8);
1964
1965 return btf_commit_type(btf, sz);
1966}
1967
1968/*
1969 * Append new BTF_KIND_FLOAT type with:
1970 * - *name* - non-empty, non-NULL type name;
1971 * - *sz* - size of the type, in bytes;
1972 * Returns:
1973 * - >0, type ID of newly added BTF type;
1974 * - <0, on error.
1975 */
1976int btf__add_float(struct btf *btf, const char *name, size_t byte_sz)
1977{
1978 struct btf_type *t;
1979 int sz, name_off;
1980
1981 /* non-empty name */
1982 if (!name || !name[0])
1983 return libbpf_err(-EINVAL);
1984
1985 /* byte_sz must be one of the explicitly allowed values */
1986 if (byte_sz != 2 && byte_sz != 4 && byte_sz != 8 && byte_sz != 12 &&
1987 byte_sz != 16)
1988 return libbpf_err(-EINVAL);
1989
1990 if (btf_ensure_modifiable(btf))
1991 return libbpf_err(-ENOMEM);
1992
1993 sz = sizeof(struct btf_type);
1994 t = btf_add_type_mem(btf, sz);
1995 if (!t)
1996 return libbpf_err(-ENOMEM);
1997
1998 name_off = btf__add_str(btf, name);
1999 if (name_off < 0)
2000 return name_off;
2001
2002 t->name_off = name_off;
2003 t->info = btf_type_info(BTF_KIND_FLOAT, 0, 0);
2004 t->size = byte_sz;
2005
2006 return btf_commit_type(btf, sz);
2007}
2008
2009/* it's completely legal to append BTF types with type IDs pointing forward to
2010 * types that haven't been appended yet, so we only make sure that id looks
2011 * sane, we can't guarantee that ID will always be valid
2012 */
2013static int validate_type_id(int id)
2014{
2015 if (id < 0 || id > BTF_MAX_NR_TYPES)
2016 return -EINVAL;
2017 return 0;
2018}
2019
2020/* generic append function for PTR, TYPEDEF, CONST/VOLATILE/RESTRICT */
2021static int btf_add_ref_kind(struct btf *btf, int kind, const char *name, int ref_type_id)
2022{
2023 struct btf_type *t;
2024 int sz, name_off = 0;
2025
2026 if (validate_type_id(ref_type_id))
2027 return libbpf_err(-EINVAL);
2028
2029 if (btf_ensure_modifiable(btf))
2030 return libbpf_err(-ENOMEM);
2031
2032 sz = sizeof(struct btf_type);
2033 t = btf_add_type_mem(btf, sz);
2034 if (!t)
2035 return libbpf_err(-ENOMEM);
2036
2037 if (name && name[0]) {
2038 name_off = btf__add_str(btf, name);
2039 if (name_off < 0)
2040 return name_off;
2041 }
2042
2043 t->name_off = name_off;
2044 t->info = btf_type_info(kind, 0, 0);
2045 t->type = ref_type_id;
2046
2047 return btf_commit_type(btf, sz);
2048}
2049
2050/*
2051 * Append new BTF_KIND_PTR type with:
2052 * - *ref_type_id* - referenced type ID, it might not exist yet;
2053 * Returns:
2054 * - >0, type ID of newly added BTF type;
2055 * - <0, on error.
2056 */
2057int btf__add_ptr(struct btf *btf, int ref_type_id)
2058{
2059 return btf_add_ref_kind(btf, BTF_KIND_PTR, NULL, ref_type_id);
2060}
2061
2062/*
2063 * Append new BTF_KIND_ARRAY type with:
2064 * - *index_type_id* - type ID of the type describing array index;
2065 * - *elem_type_id* - type ID of the type describing array element;
2066 * - *nr_elems* - the size of the array;
2067 * Returns:
2068 * - >0, type ID of newly added BTF type;
2069 * - <0, on error.
2070 */
2071int btf__add_array(struct btf *btf, int index_type_id, int elem_type_id, __u32 nr_elems)
2072{
2073 struct btf_type *t;
2074 struct btf_array *a;
2075 int sz;
2076
2077 if (validate_type_id(index_type_id) || validate_type_id(elem_type_id))
2078 return libbpf_err(-EINVAL);
2079
2080 if (btf_ensure_modifiable(btf))
2081 return libbpf_err(-ENOMEM);
2082
2083 sz = sizeof(struct btf_type) + sizeof(struct btf_array);
2084 t = btf_add_type_mem(btf, sz);
2085 if (!t)
2086 return libbpf_err(-ENOMEM);
2087
2088 t->name_off = 0;
2089 t->info = btf_type_info(BTF_KIND_ARRAY, 0, 0);
2090 t->size = 0;
2091
2092 a = btf_array(t);
2093 a->type = elem_type_id;
2094 a->index_type = index_type_id;
2095 a->nelems = nr_elems;
2096
2097 return btf_commit_type(btf, sz);
2098}
2099
2100/* generic STRUCT/UNION append function */
2101static int btf_add_composite(struct btf *btf, int kind, const char *name, __u32 bytes_sz)
2102{
2103 struct btf_type *t;
2104 int sz, name_off = 0;
2105
2106 if (btf_ensure_modifiable(btf))
2107 return libbpf_err(-ENOMEM);
2108
2109 sz = sizeof(struct btf_type);
2110 t = btf_add_type_mem(btf, sz);
2111 if (!t)
2112 return libbpf_err(-ENOMEM);
2113
2114 if (name && name[0]) {
2115 name_off = btf__add_str(btf, name);
2116 if (name_off < 0)
2117 return name_off;
2118 }
2119
2120 /* start out with vlen=0 and no kflag; this will be adjusted when
2121 * adding each member
2122 */
2123 t->name_off = name_off;
2124 t->info = btf_type_info(kind, 0, 0);
2125 t->size = bytes_sz;
2126
2127 return btf_commit_type(btf, sz);
2128}
2129
2130/*
2131 * Append new BTF_KIND_STRUCT type with:
2132 * - *name* - name of the struct, can be NULL or empty for anonymous structs;
2133 * - *byte_sz* - size of the struct, in bytes;
2134 *
2135 * Struct initially has no fields in it. Fields can be added by
2136 * btf__add_field() right after btf__add_struct() succeeds.
2137 *
2138 * Returns:
2139 * - >0, type ID of newly added BTF type;
2140 * - <0, on error.
2141 */
2142int btf__add_struct(struct btf *btf, const char *name, __u32 byte_sz)
2143{
2144 return btf_add_composite(btf, BTF_KIND_STRUCT, name, byte_sz);
2145}
2146
2147/*
2148 * Append new BTF_KIND_UNION type with:
2149 * - *name* - name of the union, can be NULL or empty for anonymous union;
2150 * - *byte_sz* - size of the union, in bytes;
2151 *
2152 * Union initially has no fields in it. Fields can be added by
2153 * btf__add_field() right after btf__add_union() succeeds. All fields
2154 * should have *bit_offset* of 0.
2155 *
2156 * Returns:
2157 * - >0, type ID of newly added BTF type;
2158 * - <0, on error.
2159 */
2160int btf__add_union(struct btf *btf, const char *name, __u32 byte_sz)
2161{
2162 return btf_add_composite(btf, BTF_KIND_UNION, name, byte_sz);
2163}
2164
2165static struct btf_type *btf_last_type(struct btf *btf)
2166{
2167 return btf_type_by_id(btf, btf__type_cnt(btf) - 1);
2168}
2169
2170/*
2171 * Append new field for the current STRUCT/UNION type with:
2172 * - *name* - name of the field, can be NULL or empty for anonymous field;
2173 * - *type_id* - type ID for the type describing field type;
2174 * - *bit_offset* - bit offset of the start of the field within struct/union;
2175 * - *bit_size* - bit size of a bitfield, 0 for non-bitfield fields;
2176 * Returns:
2177 * - 0, on success;
2178 * - <0, on error.
2179 */
2180int btf__add_field(struct btf *btf, const char *name, int type_id,
2181 __u32 bit_offset, __u32 bit_size)
2182{
2183 struct btf_type *t;
2184 struct btf_member *m;
2185 bool is_bitfield;
2186 int sz, name_off = 0;
2187
2188 /* last type should be union/struct */
2189 if (btf->nr_types == 0)
2190 return libbpf_err(-EINVAL);
2191 t = btf_last_type(btf);
2192 if (!btf_is_composite(t))
2193 return libbpf_err(-EINVAL);
2194
2195 if (validate_type_id(type_id))
2196 return libbpf_err(-EINVAL);
2197 /* best-effort bit field offset/size enforcement */
2198 is_bitfield = bit_size || (bit_offset % 8 != 0);
2199 if (is_bitfield && (bit_size == 0 || bit_size > 255 || bit_offset > 0xffffff))
2200 return libbpf_err(-EINVAL);
2201
2202 /* only offset 0 is allowed for unions */
2203 if (btf_is_union(t) && bit_offset)
2204 return libbpf_err(-EINVAL);
2205
2206 /* decompose and invalidate raw data */
2207 if (btf_ensure_modifiable(btf))
2208 return libbpf_err(-ENOMEM);
2209
2210 sz = sizeof(struct btf_member);
2211 m = btf_add_type_mem(btf, sz);
2212 if (!m)
2213 return libbpf_err(-ENOMEM);
2214
2215 if (name && name[0]) {
2216 name_off = btf__add_str(btf, name);
2217 if (name_off < 0)
2218 return name_off;
2219 }
2220
2221 m->name_off = name_off;
2222 m->type = type_id;
2223 m->offset = bit_offset | (bit_size << 24);
2224
2225 /* btf_add_type_mem can invalidate t pointer */
2226 t = btf_last_type(btf);
2227 /* update parent type's vlen and kflag */
2228 t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, is_bitfield || btf_kflag(t));
2229
2230 btf->hdr->type_len += sz;
2231 btf->hdr->str_off += sz;
2232 return 0;
2233}
2234
2235static int btf_add_enum_common(struct btf *btf, const char *name, __u32 byte_sz,
2236 bool is_signed, __u8 kind)
2237{
2238 struct btf_type *t;
2239 int sz, name_off = 0;
2240
2241 /* byte_sz must be power of 2 */
2242 if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 8)
2243 return libbpf_err(-EINVAL);
2244
2245 if (btf_ensure_modifiable(btf))
2246 return libbpf_err(-ENOMEM);
2247
2248 sz = sizeof(struct btf_type);
2249 t = btf_add_type_mem(btf, sz);
2250 if (!t)
2251 return libbpf_err(-ENOMEM);
2252
2253 if (name && name[0]) {
2254 name_off = btf__add_str(btf, name);
2255 if (name_off < 0)
2256 return name_off;
2257 }
2258
2259 /* start out with vlen=0; it will be adjusted when adding enum values */
2260 t->name_off = name_off;
2261 t->info = btf_type_info(kind, 0, is_signed);
2262 t->size = byte_sz;
2263
2264 return btf_commit_type(btf, sz);
2265}
2266
2267/*
2268 * Append new BTF_KIND_ENUM type with:
2269 * - *name* - name of the enum, can be NULL or empty for anonymous enums;
2270 * - *byte_sz* - size of the enum, in bytes.
2271 *
2272 * Enum initially has no enum values in it (and corresponds to enum forward
2273 * declaration). Enumerator values can be added by btf__add_enum_value()
2274 * immediately after btf__add_enum() succeeds.
2275 *
2276 * Returns:
2277 * - >0, type ID of newly added BTF type;
2278 * - <0, on error.
2279 */
2280int btf__add_enum(struct btf *btf, const char *name, __u32 byte_sz)
2281{
2282 /*
2283 * set the signedness to be unsigned, it will change to signed
2284 * if any later enumerator is negative.
2285 */
2286 return btf_add_enum_common(btf, name, byte_sz, false, BTF_KIND_ENUM);
2287}
2288
2289/*
2290 * Append new enum value for the current ENUM type with:
2291 * - *name* - name of the enumerator value, can't be NULL or empty;
2292 * - *value* - integer value corresponding to enum value *name*;
2293 * Returns:
2294 * - 0, on success;
2295 * - <0, on error.
2296 */
2297int btf__add_enum_value(struct btf *btf, const char *name, __s64 value)
2298{
2299 struct btf_type *t;
2300 struct btf_enum *v;
2301 int sz, name_off;
2302
2303 /* last type should be BTF_KIND_ENUM */
2304 if (btf->nr_types == 0)
2305 return libbpf_err(-EINVAL);
2306 t = btf_last_type(btf);
2307 if (!btf_is_enum(t))
2308 return libbpf_err(-EINVAL);
2309
2310 /* non-empty name */
2311 if (!name || !name[0])
2312 return libbpf_err(-EINVAL);
2313 if (value < INT_MIN || value > UINT_MAX)
2314 return libbpf_err(-E2BIG);
2315
2316 /* decompose and invalidate raw data */
2317 if (btf_ensure_modifiable(btf))
2318 return libbpf_err(-ENOMEM);
2319
2320 sz = sizeof(struct btf_enum);
2321 v = btf_add_type_mem(btf, sz);
2322 if (!v)
2323 return libbpf_err(-ENOMEM);
2324
2325 name_off = btf__add_str(btf, name);
2326 if (name_off < 0)
2327 return name_off;
2328
2329 v->name_off = name_off;
2330 v->val = value;
2331
2332 /* update parent type's vlen */
2333 t = btf_last_type(btf);
2334 btf_type_inc_vlen(t);
2335
2336 /* if negative value, set signedness to signed */
2337 if (value < 0)
2338 t->info = btf_type_info(btf_kind(t), btf_vlen(t), true);
2339
2340 btf->hdr->type_len += sz;
2341 btf->hdr->str_off += sz;
2342 return 0;
2343}
2344
2345/*
2346 * Append new BTF_KIND_ENUM64 type with:
2347 * - *name* - name of the enum, can be NULL or empty for anonymous enums;
2348 * - *byte_sz* - size of the enum, in bytes.
2349 * - *is_signed* - whether the enum values are signed or not;
2350 *
2351 * Enum initially has no enum values in it (and corresponds to enum forward
2352 * declaration). Enumerator values can be added by btf__add_enum64_value()
2353 * immediately after btf__add_enum64() succeeds.
2354 *
2355 * Returns:
2356 * - >0, type ID of newly added BTF type;
2357 * - <0, on error.
2358 */
2359int btf__add_enum64(struct btf *btf, const char *name, __u32 byte_sz,
2360 bool is_signed)
2361{
2362 return btf_add_enum_common(btf, name, byte_sz, is_signed,
2363 BTF_KIND_ENUM64);
2364}
2365
2366/*
2367 * Append new enum value for the current ENUM64 type with:
2368 * - *name* - name of the enumerator value, can't be NULL or empty;
2369 * - *value* - integer value corresponding to enum value *name*;
2370 * Returns:
2371 * - 0, on success;
2372 * - <0, on error.
2373 */
2374int btf__add_enum64_value(struct btf *btf, const char *name, __u64 value)
2375{
2376 struct btf_enum64 *v;
2377 struct btf_type *t;
2378 int sz, name_off;
2379
2380 /* last type should be BTF_KIND_ENUM64 */
2381 if (btf->nr_types == 0)
2382 return libbpf_err(-EINVAL);
2383 t = btf_last_type(btf);
2384 if (!btf_is_enum64(t))
2385 return libbpf_err(-EINVAL);
2386
2387 /* non-empty name */
2388 if (!name || !name[0])
2389 return libbpf_err(-EINVAL);
2390
2391 /* decompose and invalidate raw data */
2392 if (btf_ensure_modifiable(btf))
2393 return libbpf_err(-ENOMEM);
2394
2395 sz = sizeof(struct btf_enum64);
2396 v = btf_add_type_mem(btf, sz);
2397 if (!v)
2398 return libbpf_err(-ENOMEM);
2399
2400 name_off = btf__add_str(btf, name);
2401 if (name_off < 0)
2402 return name_off;
2403
2404 v->name_off = name_off;
2405 v->val_lo32 = (__u32)value;
2406 v->val_hi32 = value >> 32;
2407
2408 /* update parent type's vlen */
2409 t = btf_last_type(btf);
2410 btf_type_inc_vlen(t);
2411
2412 btf->hdr->type_len += sz;
2413 btf->hdr->str_off += sz;
2414 return 0;
2415}
2416
2417/*
2418 * Append new BTF_KIND_FWD type with:
2419 * - *name*, non-empty/non-NULL name;
2420 * - *fwd_kind*, kind of forward declaration, one of BTF_FWD_STRUCT,
2421 * BTF_FWD_UNION, or BTF_FWD_ENUM;
2422 * Returns:
2423 * - >0, type ID of newly added BTF type;
2424 * - <0, on error.
2425 */
2426int btf__add_fwd(struct btf *btf, const char *name, enum btf_fwd_kind fwd_kind)
2427{
2428 if (!name || !name[0])
2429 return libbpf_err(-EINVAL);
2430
2431 switch (fwd_kind) {
2432 case BTF_FWD_STRUCT:
2433 case BTF_FWD_UNION: {
2434 struct btf_type *t;
2435 int id;
2436
2437 id = btf_add_ref_kind(btf, BTF_KIND_FWD, name, 0);
2438 if (id <= 0)
2439 return id;
2440 t = btf_type_by_id(btf, id);
2441 t->info = btf_type_info(BTF_KIND_FWD, 0, fwd_kind == BTF_FWD_UNION);
2442 return id;
2443 }
2444 case BTF_FWD_ENUM:
2445 /* enum forward in BTF currently is just an enum with no enum
2446 * values; we also assume a standard 4-byte size for it
2447 */
2448 return btf__add_enum(btf, name, sizeof(int));
2449 default:
2450 return libbpf_err(-EINVAL);
2451 }
2452}
2453
2454/*
2455 * Append new BTF_KING_TYPEDEF type with:
2456 * - *name*, non-empty/non-NULL name;
2457 * - *ref_type_id* - referenced type ID, it might not exist yet;
2458 * Returns:
2459 * - >0, type ID of newly added BTF type;
2460 * - <0, on error.
2461 */
2462int btf__add_typedef(struct btf *btf, const char *name, int ref_type_id)
2463{
2464 if (!name || !name[0])
2465 return libbpf_err(-EINVAL);
2466
2467 return btf_add_ref_kind(btf, BTF_KIND_TYPEDEF, name, ref_type_id);
2468}
2469
2470/*
2471 * Append new BTF_KIND_VOLATILE type with:
2472 * - *ref_type_id* - referenced type ID, it might not exist yet;
2473 * Returns:
2474 * - >0, type ID of newly added BTF type;
2475 * - <0, on error.
2476 */
2477int btf__add_volatile(struct btf *btf, int ref_type_id)
2478{
2479 return btf_add_ref_kind(btf, BTF_KIND_VOLATILE, NULL, ref_type_id);
2480}
2481
2482/*
2483 * Append new BTF_KIND_CONST type with:
2484 * - *ref_type_id* - referenced type ID, it might not exist yet;
2485 * Returns:
2486 * - >0, type ID of newly added BTF type;
2487 * - <0, on error.
2488 */
2489int btf__add_const(struct btf *btf, int ref_type_id)
2490{
2491 return btf_add_ref_kind(btf, BTF_KIND_CONST, NULL, ref_type_id);
2492}
2493
2494/*
2495 * Append new BTF_KIND_RESTRICT type with:
2496 * - *ref_type_id* - referenced type ID, it might not exist yet;
2497 * Returns:
2498 * - >0, type ID of newly added BTF type;
2499 * - <0, on error.
2500 */
2501int btf__add_restrict(struct btf *btf, int ref_type_id)
2502{
2503 return btf_add_ref_kind(btf, BTF_KIND_RESTRICT, NULL, ref_type_id);
2504}
2505
2506/*
2507 * Append new BTF_KIND_TYPE_TAG type with:
2508 * - *value*, non-empty/non-NULL tag value;
2509 * - *ref_type_id* - referenced type ID, it might not exist yet;
2510 * Returns:
2511 * - >0, type ID of newly added BTF type;
2512 * - <0, on error.
2513 */
2514int btf__add_type_tag(struct btf *btf, const char *value, int ref_type_id)
2515{
2516 if (!value || !value[0])
2517 return libbpf_err(-EINVAL);
2518
2519 return btf_add_ref_kind(btf, BTF_KIND_TYPE_TAG, value, ref_type_id);
2520}
2521
2522/*
2523 * Append new BTF_KIND_FUNC type with:
2524 * - *name*, non-empty/non-NULL name;
2525 * - *proto_type_id* - FUNC_PROTO's type ID, it might not exist yet;
2526 * Returns:
2527 * - >0, type ID of newly added BTF type;
2528 * - <0, on error.
2529 */
2530int btf__add_func(struct btf *btf, const char *name,
2531 enum btf_func_linkage linkage, int proto_type_id)
2532{
2533 int id;
2534
2535 if (!name || !name[0])
2536 return libbpf_err(-EINVAL);
2537 if (linkage != BTF_FUNC_STATIC && linkage != BTF_FUNC_GLOBAL &&
2538 linkage != BTF_FUNC_EXTERN)
2539 return libbpf_err(-EINVAL);
2540
2541 id = btf_add_ref_kind(btf, BTF_KIND_FUNC, name, proto_type_id);
2542 if (id > 0) {
2543 struct btf_type *t = btf_type_by_id(btf, id);
2544
2545 t->info = btf_type_info(BTF_KIND_FUNC, linkage, 0);
2546 }
2547 return libbpf_err(id);
2548}
2549
2550/*
2551 * Append new BTF_KIND_FUNC_PROTO with:
2552 * - *ret_type_id* - type ID for return result of a function.
2553 *
2554 * Function prototype initially has no arguments, but they can be added by
2555 * btf__add_func_param() one by one, immediately after
2556 * btf__add_func_proto() succeeded.
2557 *
2558 * Returns:
2559 * - >0, type ID of newly added BTF type;
2560 * - <0, on error.
2561 */
2562int btf__add_func_proto(struct btf *btf, int ret_type_id)
2563{
2564 struct btf_type *t;
2565 int sz;
2566
2567 if (validate_type_id(ret_type_id))
2568 return libbpf_err(-EINVAL);
2569
2570 if (btf_ensure_modifiable(btf))
2571 return libbpf_err(-ENOMEM);
2572
2573 sz = sizeof(struct btf_type);
2574 t = btf_add_type_mem(btf, sz);
2575 if (!t)
2576 return libbpf_err(-ENOMEM);
2577
2578 /* start out with vlen=0; this will be adjusted when adding enum
2579 * values, if necessary
2580 */
2581 t->name_off = 0;
2582 t->info = btf_type_info(BTF_KIND_FUNC_PROTO, 0, 0);
2583 t->type = ret_type_id;
2584
2585 return btf_commit_type(btf, sz);
2586}
2587
2588/*
2589 * Append new function parameter for current FUNC_PROTO type with:
2590 * - *name* - parameter name, can be NULL or empty;
2591 * - *type_id* - type ID describing the type of the parameter.
2592 * Returns:
2593 * - 0, on success;
2594 * - <0, on error.
2595 */
2596int btf__add_func_param(struct btf *btf, const char *name, int type_id)
2597{
2598 struct btf_type *t;
2599 struct btf_param *p;
2600 int sz, name_off = 0;
2601
2602 if (validate_type_id(type_id))
2603 return libbpf_err(-EINVAL);
2604
2605 /* last type should be BTF_KIND_FUNC_PROTO */
2606 if (btf->nr_types == 0)
2607 return libbpf_err(-EINVAL);
2608 t = btf_last_type(btf);
2609 if (!btf_is_func_proto(t))
2610 return libbpf_err(-EINVAL);
2611
2612 /* decompose and invalidate raw data */
2613 if (btf_ensure_modifiable(btf))
2614 return libbpf_err(-ENOMEM);
2615
2616 sz = sizeof(struct btf_param);
2617 p = btf_add_type_mem(btf, sz);
2618 if (!p)
2619 return libbpf_err(-ENOMEM);
2620
2621 if (name && name[0]) {
2622 name_off = btf__add_str(btf, name);
2623 if (name_off < 0)
2624 return name_off;
2625 }
2626
2627 p->name_off = name_off;
2628 p->type = type_id;
2629
2630 /* update parent type's vlen */
2631 t = btf_last_type(btf);
2632 btf_type_inc_vlen(t);
2633
2634 btf->hdr->type_len += sz;
2635 btf->hdr->str_off += sz;
2636 return 0;
2637}
2638
2639/*
2640 * Append new BTF_KIND_VAR type with:
2641 * - *name* - non-empty/non-NULL name;
2642 * - *linkage* - variable linkage, one of BTF_VAR_STATIC,
2643 * BTF_VAR_GLOBAL_ALLOCATED, or BTF_VAR_GLOBAL_EXTERN;
2644 * - *type_id* - type ID of the type describing the type of the variable.
2645 * Returns:
2646 * - >0, type ID of newly added BTF type;
2647 * - <0, on error.
2648 */
2649int btf__add_var(struct btf *btf, const char *name, int linkage, int type_id)
2650{
2651 struct btf_type *t;
2652 struct btf_var *v;
2653 int sz, name_off;
2654
2655 /* non-empty name */
2656 if (!name || !name[0])
2657 return libbpf_err(-EINVAL);
2658 if (linkage != BTF_VAR_STATIC && linkage != BTF_VAR_GLOBAL_ALLOCATED &&
2659 linkage != BTF_VAR_GLOBAL_EXTERN)
2660 return libbpf_err(-EINVAL);
2661 if (validate_type_id(type_id))
2662 return libbpf_err(-EINVAL);
2663
2664 /* deconstruct BTF, if necessary, and invalidate raw_data */
2665 if (btf_ensure_modifiable(btf))
2666 return libbpf_err(-ENOMEM);
2667
2668 sz = sizeof(struct btf_type) + sizeof(struct btf_var);
2669 t = btf_add_type_mem(btf, sz);
2670 if (!t)
2671 return libbpf_err(-ENOMEM);
2672
2673 name_off = btf__add_str(btf, name);
2674 if (name_off < 0)
2675 return name_off;
2676
2677 t->name_off = name_off;
2678 t->info = btf_type_info(BTF_KIND_VAR, 0, 0);
2679 t->type = type_id;
2680
2681 v = btf_var(t);
2682 v->linkage = linkage;
2683
2684 return btf_commit_type(btf, sz);
2685}
2686
2687/*
2688 * Append new BTF_KIND_DATASEC type with:
2689 * - *name* - non-empty/non-NULL name;
2690 * - *byte_sz* - data section size, in bytes.
2691 *
2692 * Data section is initially empty. Variables info can be added with
2693 * btf__add_datasec_var_info() calls, after btf__add_datasec() succeeds.
2694 *
2695 * Returns:
2696 * - >0, type ID of newly added BTF type;
2697 * - <0, on error.
2698 */
2699int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz)
2700{
2701 struct btf_type *t;
2702 int sz, name_off;
2703
2704 /* non-empty name */
2705 if (!name || !name[0])
2706 return libbpf_err(-EINVAL);
2707
2708 if (btf_ensure_modifiable(btf))
2709 return libbpf_err(-ENOMEM);
2710
2711 sz = sizeof(struct btf_type);
2712 t = btf_add_type_mem(btf, sz);
2713 if (!t)
2714 return libbpf_err(-ENOMEM);
2715
2716 name_off = btf__add_str(btf, name);
2717 if (name_off < 0)
2718 return name_off;
2719
2720 /* start with vlen=0, which will be update as var_secinfos are added */
2721 t->name_off = name_off;
2722 t->info = btf_type_info(BTF_KIND_DATASEC, 0, 0);
2723 t->size = byte_sz;
2724
2725 return btf_commit_type(btf, sz);
2726}
2727
2728/*
2729 * Append new data section variable information entry for current DATASEC type:
2730 * - *var_type_id* - type ID, describing type of the variable;
2731 * - *offset* - variable offset within data section, in bytes;
2732 * - *byte_sz* - variable size, in bytes.
2733 *
2734 * Returns:
2735 * - 0, on success;
2736 * - <0, on error.
2737 */
2738int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __u32 byte_sz)
2739{
2740 struct btf_type *t;
2741 struct btf_var_secinfo *v;
2742 int sz;
2743
2744 /* last type should be BTF_KIND_DATASEC */
2745 if (btf->nr_types == 0)
2746 return libbpf_err(-EINVAL);
2747 t = btf_last_type(btf);
2748 if (!btf_is_datasec(t))
2749 return libbpf_err(-EINVAL);
2750
2751 if (validate_type_id(var_type_id))
2752 return libbpf_err(-EINVAL);
2753
2754 /* decompose and invalidate raw data */
2755 if (btf_ensure_modifiable(btf))
2756 return libbpf_err(-ENOMEM);
2757
2758 sz = sizeof(struct btf_var_secinfo);
2759 v = btf_add_type_mem(btf, sz);
2760 if (!v)
2761 return libbpf_err(-ENOMEM);
2762
2763 v->type = var_type_id;
2764 v->offset = offset;
2765 v->size = byte_sz;
2766
2767 /* update parent type's vlen */
2768 t = btf_last_type(btf);
2769 btf_type_inc_vlen(t);
2770
2771 btf->hdr->type_len += sz;
2772 btf->hdr->str_off += sz;
2773 return 0;
2774}
2775
2776/*
2777 * Append new BTF_KIND_DECL_TAG type with:
2778 * - *value* - non-empty/non-NULL string;
2779 * - *ref_type_id* - referenced type ID, it might not exist yet;
2780 * - *component_idx* - -1 for tagging reference type, otherwise struct/union
2781 * member or function argument index;
2782 * Returns:
2783 * - >0, type ID of newly added BTF type;
2784 * - <0, on error.
2785 */
2786int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
2787 int component_idx)
2788{
2789 struct btf_type *t;
2790 int sz, value_off;
2791
2792 if (!value || !value[0] || component_idx < -1)
2793 return libbpf_err(-EINVAL);
2794
2795 if (validate_type_id(ref_type_id))
2796 return libbpf_err(-EINVAL);
2797
2798 if (btf_ensure_modifiable(btf))
2799 return libbpf_err(-ENOMEM);
2800
2801 sz = sizeof(struct btf_type) + sizeof(struct btf_decl_tag);
2802 t = btf_add_type_mem(btf, sz);
2803 if (!t)
2804 return libbpf_err(-ENOMEM);
2805
2806 value_off = btf__add_str(btf, value);
2807 if (value_off < 0)
2808 return value_off;
2809
2810 t->name_off = value_off;
2811 t->info = btf_type_info(BTF_KIND_DECL_TAG, 0, false);
2812 t->type = ref_type_id;
2813 btf_decl_tag(t)->component_idx = component_idx;
2814
2815 return btf_commit_type(btf, sz);
2816}
2817
2818struct btf_ext_sec_setup_param {
2819 __u32 off;
2820 __u32 len;
2821 __u32 min_rec_size;
2822 struct btf_ext_info *ext_info;
2823 const char *desc;
2824};
2825
2826static int btf_ext_setup_info(struct btf_ext *btf_ext,
2827 struct btf_ext_sec_setup_param *ext_sec)
2828{
2829 const struct btf_ext_info_sec *sinfo;
2830 struct btf_ext_info *ext_info;
2831 __u32 info_left, record_size;
2832 size_t sec_cnt = 0;
2833 /* The start of the info sec (including the __u32 record_size). */
2834 void *info;
2835
2836 if (ext_sec->len == 0)
2837 return 0;
2838
2839 if (ext_sec->off & 0x03) {
2840 pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
2841 ext_sec->desc);
2842 return -EINVAL;
2843 }
2844
2845 info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;
2846 info_left = ext_sec->len;
2847
2848 if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {
2849 pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
2850 ext_sec->desc, ext_sec->off, ext_sec->len);
2851 return -EINVAL;
2852 }
2853
2854 /* At least a record size */
2855 if (info_left < sizeof(__u32)) {
2856 pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
2857 return -EINVAL;
2858 }
2859
2860 /* The record size needs to meet the minimum standard */
2861 record_size = *(__u32 *)info;
2862 if (record_size < ext_sec->min_rec_size ||
2863 record_size & 0x03) {
2864 pr_debug("%s section in .BTF.ext has invalid record size %u\n",
2865 ext_sec->desc, record_size);
2866 return -EINVAL;
2867 }
2868
2869 sinfo = info + sizeof(__u32);
2870 info_left -= sizeof(__u32);
2871
2872 /* If no records, return failure now so .BTF.ext won't be used. */
2873 if (!info_left) {
2874 pr_debug("%s section in .BTF.ext has no records", ext_sec->desc);
2875 return -EINVAL;
2876 }
2877
2878 while (info_left) {
2879 unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
2880 __u64 total_record_size;
2881 __u32 num_records;
2882
2883 if (info_left < sec_hdrlen) {
2884 pr_debug("%s section header is not found in .BTF.ext\n",
2885 ext_sec->desc);
2886 return -EINVAL;
2887 }
2888
2889 num_records = sinfo->num_info;
2890 if (num_records == 0) {
2891 pr_debug("%s section has incorrect num_records in .BTF.ext\n",
2892 ext_sec->desc);
2893 return -EINVAL;
2894 }
2895
2896 total_record_size = sec_hdrlen + (__u64)num_records * record_size;
2897 if (info_left < total_record_size) {
2898 pr_debug("%s section has incorrect num_records in .BTF.ext\n",
2899 ext_sec->desc);
2900 return -EINVAL;
2901 }
2902
2903 info_left -= total_record_size;
2904 sinfo = (void *)sinfo + total_record_size;
2905 sec_cnt++;
2906 }
2907
2908 ext_info = ext_sec->ext_info;
2909 ext_info->len = ext_sec->len - sizeof(__u32);
2910 ext_info->rec_size = record_size;
2911 ext_info->info = info + sizeof(__u32);
2912 ext_info->sec_cnt = sec_cnt;
2913
2914 return 0;
2915}
2916
2917static int btf_ext_setup_func_info(struct btf_ext *btf_ext)
2918{
2919 struct btf_ext_sec_setup_param param = {
2920 .off = btf_ext->hdr->func_info_off,
2921 .len = btf_ext->hdr->func_info_len,
2922 .min_rec_size = sizeof(struct bpf_func_info_min),
2923 .ext_info = &btf_ext->func_info,
2924 .desc = "func_info"
2925 };
2926
2927 return btf_ext_setup_info(btf_ext, ¶m);
2928}
2929
2930static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
2931{
2932 struct btf_ext_sec_setup_param param = {
2933 .off = btf_ext->hdr->line_info_off,
2934 .len = btf_ext->hdr->line_info_len,
2935 .min_rec_size = sizeof(struct bpf_line_info_min),
2936 .ext_info = &btf_ext->line_info,
2937 .desc = "line_info",
2938 };
2939
2940 return btf_ext_setup_info(btf_ext, ¶m);
2941}
2942
2943static int btf_ext_setup_core_relos(struct btf_ext *btf_ext)
2944{
2945 struct btf_ext_sec_setup_param param = {
2946 .off = btf_ext->hdr->core_relo_off,
2947 .len = btf_ext->hdr->core_relo_len,
2948 .min_rec_size = sizeof(struct bpf_core_relo),
2949 .ext_info = &btf_ext->core_relo_info,
2950 .desc = "core_relo",
2951 };
2952
2953 return btf_ext_setup_info(btf_ext, ¶m);
2954}
2955
2956static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
2957{
2958 const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
2959
2960 if (data_size < offsetofend(struct btf_ext_header, hdr_len) ||
2961 data_size < hdr->hdr_len) {
2962 pr_debug("BTF.ext header not found");
2963 return -EINVAL;
2964 }
2965
2966 if (hdr->magic == bswap_16(BTF_MAGIC)) {
2967 pr_warn("BTF.ext in non-native endianness is not supported\n");
2968 return -ENOTSUP;
2969 } else if (hdr->magic != BTF_MAGIC) {
2970 pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic);
2971 return -EINVAL;
2972 }
2973
2974 if (hdr->version != BTF_VERSION) {
2975 pr_debug("Unsupported BTF.ext version:%u\n", hdr->version);
2976 return -ENOTSUP;
2977 }
2978
2979 if (hdr->flags) {
2980 pr_debug("Unsupported BTF.ext flags:%x\n", hdr->flags);
2981 return -ENOTSUP;
2982 }
2983
2984 if (data_size == hdr->hdr_len) {
2985 pr_debug("BTF.ext has no data\n");
2986 return -EINVAL;
2987 }
2988
2989 return 0;
2990}
2991
2992void btf_ext__free(struct btf_ext *btf_ext)
2993{
2994 if (IS_ERR_OR_NULL(btf_ext))
2995 return;
2996 free(btf_ext->func_info.sec_idxs);
2997 free(btf_ext->line_info.sec_idxs);
2998 free(btf_ext->core_relo_info.sec_idxs);
2999 free(btf_ext->data);
3000 free(btf_ext);
3001}
3002
3003struct btf_ext *btf_ext__new(const __u8 *data, __u32 size)
3004{
3005 struct btf_ext *btf_ext;
3006 int err;
3007
3008 btf_ext = calloc(1, sizeof(struct btf_ext));
3009 if (!btf_ext)
3010 return libbpf_err_ptr(-ENOMEM);
3011
3012 btf_ext->data_size = size;
3013 btf_ext->data = malloc(size);
3014 if (!btf_ext->data) {
3015 err = -ENOMEM;
3016 goto done;
3017 }
3018 memcpy(btf_ext->data, data, size);
3019
3020 err = btf_ext_parse_hdr(btf_ext->data, size);
3021 if (err)
3022 goto done;
3023
3024 if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, line_info_len)) {
3025 err = -EINVAL;
3026 goto done;
3027 }
3028
3029 err = btf_ext_setup_func_info(btf_ext);
3030 if (err)
3031 goto done;
3032
3033 err = btf_ext_setup_line_info(btf_ext);
3034 if (err)
3035 goto done;
3036
3037 if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len))
3038 goto done; /* skip core relos parsing */
3039
3040 err = btf_ext_setup_core_relos(btf_ext);
3041 if (err)
3042 goto done;
3043
3044done:
3045 if (err) {
3046 btf_ext__free(btf_ext);
3047 return libbpf_err_ptr(err);
3048 }
3049
3050 return btf_ext;
3051}
3052
3053const void *btf_ext__raw_data(const struct btf_ext *btf_ext, __u32 *size)
3054{
3055 *size = btf_ext->data_size;
3056 return btf_ext->data;
3057}
3058
3059__attribute__((alias("btf_ext__raw_data")))
3060const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size);
3061
3062
3063struct btf_dedup;
3064
3065static struct btf_dedup *btf_dedup_new(struct btf *btf, const struct btf_dedup_opts *opts);
3066static void btf_dedup_free(struct btf_dedup *d);
3067static int btf_dedup_prep(struct btf_dedup *d);
3068static int btf_dedup_strings(struct btf_dedup *d);
3069static int btf_dedup_prim_types(struct btf_dedup *d);
3070static int btf_dedup_struct_types(struct btf_dedup *d);
3071static int btf_dedup_ref_types(struct btf_dedup *d);
3072static int btf_dedup_resolve_fwds(struct btf_dedup *d);
3073static int btf_dedup_compact_types(struct btf_dedup *d);
3074static int btf_dedup_remap_types(struct btf_dedup *d);
3075
3076/*
3077 * Deduplicate BTF types and strings.
3078 *
3079 * BTF dedup algorithm takes as an input `struct btf` representing `.BTF` ELF
3080 * section with all BTF type descriptors and string data. It overwrites that
3081 * memory in-place with deduplicated types and strings without any loss of
3082 * information. If optional `struct btf_ext` representing '.BTF.ext' ELF section
3083 * is provided, all the strings referenced from .BTF.ext section are honored
3084 * and updated to point to the right offsets after deduplication.
3085 *
3086 * If function returns with error, type/string data might be garbled and should
3087 * be discarded.
3088 *
3089 * More verbose and detailed description of both problem btf_dedup is solving,
3090 * as well as solution could be found at:
3091 * https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
3092 *
3093 * Problem description and justification
3094 * =====================================
3095 *
3096 * BTF type information is typically emitted either as a result of conversion
3097 * from DWARF to BTF or directly by compiler. In both cases, each compilation
3098 * unit contains information about a subset of all the types that are used
3099 * in an application. These subsets are frequently overlapping and contain a lot
3100 * of duplicated information when later concatenated together into a single
3101 * binary. This algorithm ensures that each unique type is represented by single
3102 * BTF type descriptor, greatly reducing resulting size of BTF data.
3103 *
3104 * Compilation unit isolation and subsequent duplication of data is not the only
3105 * problem. The same type hierarchy (e.g., struct and all the type that struct
3106 * references) in different compilation units can be represented in BTF to
3107 * various degrees of completeness (or, rather, incompleteness) due to
3108 * struct/union forward declarations.
3109 *
3110 * Let's take a look at an example, that we'll use to better understand the
3111 * problem (and solution). Suppose we have two compilation units, each using
3112 * same `struct S`, but each of them having incomplete type information about
3113 * struct's fields:
3114 *
3115 * // CU #1:
3116 * struct S;
3117 * struct A {
3118 * int a;
3119 * struct A* self;
3120 * struct S* parent;
3121 * };
3122 * struct B;
3123 * struct S {
3124 * struct A* a_ptr;
3125 * struct B* b_ptr;
3126 * };
3127 *
3128 * // CU #2:
3129 * struct S;
3130 * struct A;
3131 * struct B {
3132 * int b;
3133 * struct B* self;
3134 * struct S* parent;
3135 * };
3136 * struct S {
3137 * struct A* a_ptr;
3138 * struct B* b_ptr;
3139 * };
3140 *
3141 * In case of CU #1, BTF data will know only that `struct B` exist (but no
3142 * more), but will know the complete type information about `struct A`. While
3143 * for CU #2, it will know full type information about `struct B`, but will
3144 * only know about forward declaration of `struct A` (in BTF terms, it will
3145 * have `BTF_KIND_FWD` type descriptor with name `B`).
3146 *
3147 * This compilation unit isolation means that it's possible that there is no
3148 * single CU with complete type information describing structs `S`, `A`, and
3149 * `B`. Also, we might get tons of duplicated and redundant type information.
3150 *
3151 * Additional complication we need to keep in mind comes from the fact that
3152 * types, in general, can form graphs containing cycles, not just DAGs.
3153 *
3154 * While algorithm does deduplication, it also merges and resolves type
3155 * information (unless disabled throught `struct btf_opts`), whenever possible.
3156 * E.g., in the example above with two compilation units having partial type
3157 * information for structs `A` and `B`, the output of algorithm will emit
3158 * a single copy of each BTF type that describes structs `A`, `B`, and `S`
3159 * (as well as type information for `int` and pointers), as if they were defined
3160 * in a single compilation unit as:
3161 *
3162 * struct A {
3163 * int a;
3164 * struct A* self;
3165 * struct S* parent;
3166 * };
3167 * struct B {
3168 * int b;
3169 * struct B* self;
3170 * struct S* parent;
3171 * };
3172 * struct S {
3173 * struct A* a_ptr;
3174 * struct B* b_ptr;
3175 * };
3176 *
3177 * Algorithm summary
3178 * =================
3179 *
3180 * Algorithm completes its work in 7 separate passes:
3181 *
3182 * 1. Strings deduplication.
3183 * 2. Primitive types deduplication (int, enum, fwd).
3184 * 3. Struct/union types deduplication.
3185 * 4. Resolve unambiguous forward declarations.
3186 * 5. Reference types deduplication (pointers, typedefs, arrays, funcs, func
3187 * protos, and const/volatile/restrict modifiers).
3188 * 6. Types compaction.
3189 * 7. Types remapping.
3190 *
3191 * Algorithm determines canonical type descriptor, which is a single
3192 * representative type for each truly unique type. This canonical type is the
3193 * one that will go into final deduplicated BTF type information. For
3194 * struct/unions, it is also the type that algorithm will merge additional type
3195 * information into (while resolving FWDs), as it discovers it from data in
3196 * other CUs. Each input BTF type eventually gets either mapped to itself, if
3197 * that type is canonical, or to some other type, if that type is equivalent
3198 * and was chosen as canonical representative. This mapping is stored in
3199 * `btf_dedup->map` array. This map is also used to record STRUCT/UNION that
3200 * FWD type got resolved to.
3201 *
3202 * To facilitate fast discovery of canonical types, we also maintain canonical
3203 * index (`btf_dedup->dedup_table`), which maps type descriptor's signature hash
3204 * (i.e., hashed kind, name, size, fields, etc) into a list of canonical types
3205 * that match that signature. With sufficiently good choice of type signature
3206 * hashing function, we can limit number of canonical types for each unique type
3207 * signature to a very small number, allowing to find canonical type for any
3208 * duplicated type very quickly.
3209 *
3210 * Struct/union deduplication is the most critical part and algorithm for
3211 * deduplicating structs/unions is described in greater details in comments for
3212 * `btf_dedup_is_equiv` function.
3213 */
3214int btf__dedup(struct btf *btf, const struct btf_dedup_opts *opts)
3215{
3216 struct btf_dedup *d;
3217 int err;
3218
3219 if (!OPTS_VALID(opts, btf_dedup_opts))
3220 return libbpf_err(-EINVAL);
3221
3222 d = btf_dedup_new(btf, opts);
3223 if (IS_ERR(d)) {
3224 pr_debug("btf_dedup_new failed: %ld", PTR_ERR(d));
3225 return libbpf_err(-EINVAL);
3226 }
3227
3228 if (btf_ensure_modifiable(btf)) {
3229 err = -ENOMEM;
3230 goto done;
3231 }
3232
3233 err = btf_dedup_prep(d);
3234 if (err) {
3235 pr_debug("btf_dedup_prep failed:%d\n", err);
3236 goto done;
3237 }
3238 err = btf_dedup_strings(d);
3239 if (err < 0) {
3240 pr_debug("btf_dedup_strings failed:%d\n", err);
3241 goto done;
3242 }
3243 err = btf_dedup_prim_types(d);
3244 if (err < 0) {
3245 pr_debug("btf_dedup_prim_types failed:%d\n", err);
3246 goto done;
3247 }
3248 err = btf_dedup_struct_types(d);
3249 if (err < 0) {
3250 pr_debug("btf_dedup_struct_types failed:%d\n", err);
3251 goto done;
3252 }
3253 err = btf_dedup_resolve_fwds(d);
3254 if (err < 0) {
3255 pr_debug("btf_dedup_resolve_fwds failed:%d\n", err);
3256 goto done;
3257 }
3258 err = btf_dedup_ref_types(d);
3259 if (err < 0) {
3260 pr_debug("btf_dedup_ref_types failed:%d\n", err);
3261 goto done;
3262 }
3263 err = btf_dedup_compact_types(d);
3264 if (err < 0) {
3265 pr_debug("btf_dedup_compact_types failed:%d\n", err);
3266 goto done;
3267 }
3268 err = btf_dedup_remap_types(d);
3269 if (err < 0) {
3270 pr_debug("btf_dedup_remap_types failed:%d\n", err);
3271 goto done;
3272 }
3273
3274done:
3275 btf_dedup_free(d);
3276 return libbpf_err(err);
3277}
3278
3279#define BTF_UNPROCESSED_ID ((__u32)-1)
3280#define BTF_IN_PROGRESS_ID ((__u32)-2)
3281
3282struct btf_dedup {
3283 /* .BTF section to be deduped in-place */
3284 struct btf *btf;
3285 /*
3286 * Optional .BTF.ext section. When provided, any strings referenced
3287 * from it will be taken into account when deduping strings
3288 */
3289 struct btf_ext *btf_ext;
3290 /*
3291 * This is a map from any type's signature hash to a list of possible
3292 * canonical representative type candidates. Hash collisions are
3293 * ignored, so even types of various kinds can share same list of
3294 * candidates, which is fine because we rely on subsequent
3295 * btf_xxx_equal() checks to authoritatively verify type equality.
3296 */
3297 struct hashmap *dedup_table;
3298 /* Canonical types map */
3299 __u32 *map;
3300 /* Hypothetical mapping, used during type graph equivalence checks */
3301 __u32 *hypot_map;
3302 __u32 *hypot_list;
3303 size_t hypot_cnt;
3304 size_t hypot_cap;
3305 /* Whether hypothetical mapping, if successful, would need to adjust
3306 * already canonicalized types (due to a new forward declaration to
3307 * concrete type resolution). In such case, during split BTF dedup
3308 * candidate type would still be considered as different, because base
3309 * BTF is considered to be immutable.
3310 */
3311 bool hypot_adjust_canon;
3312 /* Various option modifying behavior of algorithm */
3313 struct btf_dedup_opts opts;
3314 /* temporary strings deduplication state */
3315 struct strset *strs_set;
3316};
3317
3318static long hash_combine(long h, long value)
3319{
3320 return h * 31 + value;
3321}
3322
3323#define for_each_dedup_cand(d, node, hash) \
3324 hashmap__for_each_key_entry(d->dedup_table, node, hash)
3325
3326static int btf_dedup_table_add(struct btf_dedup *d, long hash, __u32 type_id)
3327{
3328 return hashmap__append(d->dedup_table, hash, type_id);
3329}
3330
3331static int btf_dedup_hypot_map_add(struct btf_dedup *d,
3332 __u32 from_id, __u32 to_id)
3333{
3334 if (d->hypot_cnt == d->hypot_cap) {
3335 __u32 *new_list;
3336
3337 d->hypot_cap += max((size_t)16, d->hypot_cap / 2);
3338 new_list = libbpf_reallocarray(d->hypot_list, d->hypot_cap, sizeof(__u32));
3339 if (!new_list)
3340 return -ENOMEM;
3341 d->hypot_list = new_list;
3342 }
3343 d->hypot_list[d->hypot_cnt++] = from_id;
3344 d->hypot_map[from_id] = to_id;
3345 return 0;
3346}
3347
3348static void btf_dedup_clear_hypot_map(struct btf_dedup *d)
3349{
3350 int i;
3351
3352 for (i = 0; i < d->hypot_cnt; i++)
3353 d->hypot_map[d->hypot_list[i]] = BTF_UNPROCESSED_ID;
3354 d->hypot_cnt = 0;
3355 d->hypot_adjust_canon = false;
3356}
3357
3358static void btf_dedup_free(struct btf_dedup *d)
3359{
3360 hashmap__free(d->dedup_table);
3361 d->dedup_table = NULL;
3362
3363 free(d->map);
3364 d->map = NULL;
3365
3366 free(d->hypot_map);
3367 d->hypot_map = NULL;
3368
3369 free(d->hypot_list);
3370 d->hypot_list = NULL;
3371
3372 free(d);
3373}
3374
3375static size_t btf_dedup_identity_hash_fn(long key, void *ctx)
3376{
3377 return key;
3378}
3379
3380static size_t btf_dedup_collision_hash_fn(long key, void *ctx)
3381{
3382 return 0;
3383}
3384
3385static bool btf_dedup_equal_fn(long k1, long k2, void *ctx)
3386{
3387 return k1 == k2;
3388}
3389
3390static struct btf_dedup *btf_dedup_new(struct btf *btf, const struct btf_dedup_opts *opts)
3391{
3392 struct btf_dedup *d = calloc(1, sizeof(struct btf_dedup));
3393 hashmap_hash_fn hash_fn = btf_dedup_identity_hash_fn;
3394 int i, err = 0, type_cnt;
3395
3396 if (!d)
3397 return ERR_PTR(-ENOMEM);
3398
3399 if (OPTS_GET(opts, force_collisions, false))
3400 hash_fn = btf_dedup_collision_hash_fn;
3401
3402 d->btf = btf;
3403 d->btf_ext = OPTS_GET(opts, btf_ext, NULL);
3404
3405 d->dedup_table = hashmap__new(hash_fn, btf_dedup_equal_fn, NULL);
3406 if (IS_ERR(d->dedup_table)) {
3407 err = PTR_ERR(d->dedup_table);
3408 d->dedup_table = NULL;
3409 goto done;
3410 }
3411
3412 type_cnt = btf__type_cnt(btf);
3413 d->map = malloc(sizeof(__u32) * type_cnt);
3414 if (!d->map) {
3415 err = -ENOMEM;
3416 goto done;
3417 }
3418 /* special BTF "void" type is made canonical immediately */
3419 d->map[0] = 0;
3420 for (i = 1; i < type_cnt; i++) {
3421 struct btf_type *t = btf_type_by_id(d->btf, i);
3422
3423 /* VAR and DATASEC are never deduped and are self-canonical */
3424 if (btf_is_var(t) || btf_is_datasec(t))
3425 d->map[i] = i;
3426 else
3427 d->map[i] = BTF_UNPROCESSED_ID;
3428 }
3429
3430 d->hypot_map = malloc(sizeof(__u32) * type_cnt);
3431 if (!d->hypot_map) {
3432 err = -ENOMEM;
3433 goto done;
3434 }
3435 for (i = 0; i < type_cnt; i++)
3436 d->hypot_map[i] = BTF_UNPROCESSED_ID;
3437
3438done:
3439 if (err) {
3440 btf_dedup_free(d);
3441 return ERR_PTR(err);
3442 }
3443
3444 return d;
3445}
3446
3447/*
3448 * Iterate over all possible places in .BTF and .BTF.ext that can reference
3449 * string and pass pointer to it to a provided callback `fn`.
3450 */
3451static int btf_for_each_str_off(struct btf_dedup *d, str_off_visit_fn fn, void *ctx)
3452{
3453 int i, r;
3454
3455 for (i = 0; i < d->btf->nr_types; i++) {
3456 struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
3457
3458 r = btf_type_visit_str_offs(t, fn, ctx);
3459 if (r)
3460 return r;
3461 }
3462
3463 if (!d->btf_ext)
3464 return 0;
3465
3466 r = btf_ext_visit_str_offs(d->btf_ext, fn, ctx);
3467 if (r)
3468 return r;
3469
3470 return 0;
3471}
3472
3473static int strs_dedup_remap_str_off(__u32 *str_off_ptr, void *ctx)
3474{
3475 struct btf_dedup *d = ctx;
3476 __u32 str_off = *str_off_ptr;
3477 const char *s;
3478 int off, err;
3479
3480 /* don't touch empty string or string in main BTF */
3481 if (str_off == 0 || str_off < d->btf->start_str_off)
3482 return 0;
3483
3484 s = btf__str_by_offset(d->btf, str_off);
3485 if (d->btf->base_btf) {
3486 err = btf__find_str(d->btf->base_btf, s);
3487 if (err >= 0) {
3488 *str_off_ptr = err;
3489 return 0;
3490 }
3491 if (err != -ENOENT)
3492 return err;
3493 }
3494
3495 off = strset__add_str(d->strs_set, s);
3496 if (off < 0)
3497 return off;
3498
3499 *str_off_ptr = d->btf->start_str_off + off;
3500 return 0;
3501}
3502
3503/*
3504 * Dedup string and filter out those that are not referenced from either .BTF
3505 * or .BTF.ext (if provided) sections.
3506 *
3507 * This is done by building index of all strings in BTF's string section,
3508 * then iterating over all entities that can reference strings (e.g., type
3509 * names, struct field names, .BTF.ext line info, etc) and marking corresponding
3510 * strings as used. After that all used strings are deduped and compacted into
3511 * sequential blob of memory and new offsets are calculated. Then all the string
3512 * references are iterated again and rewritten using new offsets.
3513 */
3514static int btf_dedup_strings(struct btf_dedup *d)
3515{
3516 int err;
3517
3518 if (d->btf->strs_deduped)
3519 return 0;
3520
3521 d->strs_set = strset__new(BTF_MAX_STR_OFFSET, NULL, 0);
3522 if (IS_ERR(d->strs_set)) {
3523 err = PTR_ERR(d->strs_set);
3524 goto err_out;
3525 }
3526
3527 if (!d->btf->base_btf) {
3528 /* insert empty string; we won't be looking it up during strings
3529 * dedup, but it's good to have it for generic BTF string lookups
3530 */
3531 err = strset__add_str(d->strs_set, "");
3532 if (err < 0)
3533 goto err_out;
3534 }
3535
3536 /* remap string offsets */
3537 err = btf_for_each_str_off(d, strs_dedup_remap_str_off, d);
3538 if (err)
3539 goto err_out;
3540
3541 /* replace BTF string data and hash with deduped ones */
3542 strset__free(d->btf->strs_set);
3543 d->btf->hdr->str_len = strset__data_size(d->strs_set);
3544 d->btf->strs_set = d->strs_set;
3545 d->strs_set = NULL;
3546 d->btf->strs_deduped = true;
3547 return 0;
3548
3549err_out:
3550 strset__free(d->strs_set);
3551 d->strs_set = NULL;
3552
3553 return err;
3554}
3555
3556static long btf_hash_common(struct btf_type *t)
3557{
3558 long h;
3559
3560 h = hash_combine(0, t->name_off);
3561 h = hash_combine(h, t->info);
3562 h = hash_combine(h, t->size);
3563 return h;
3564}
3565
3566static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
3567{
3568 return t1->name_off == t2->name_off &&
3569 t1->info == t2->info &&
3570 t1->size == t2->size;
3571}
3572
3573/* Calculate type signature hash of INT or TAG. */
3574static long btf_hash_int_decl_tag(struct btf_type *t)
3575{
3576 __u32 info = *(__u32 *)(t + 1);
3577 long h;
3578
3579 h = btf_hash_common(t);
3580 h = hash_combine(h, info);
3581 return h;
3582}
3583
3584/* Check structural equality of two INTs or TAGs. */
3585static bool btf_equal_int_tag(struct btf_type *t1, struct btf_type *t2)
3586{
3587 __u32 info1, info2;
3588
3589 if (!btf_equal_common(t1, t2))
3590 return false;
3591 info1 = *(__u32 *)(t1 + 1);
3592 info2 = *(__u32 *)(t2 + 1);
3593 return info1 == info2;
3594}
3595
3596/* Calculate type signature hash of ENUM/ENUM64. */
3597static long btf_hash_enum(struct btf_type *t)
3598{
3599 long h;
3600
3601 /* don't hash vlen, enum members and size to support enum fwd resolving */
3602 h = hash_combine(0, t->name_off);
3603 return h;
3604}
3605
3606static bool btf_equal_enum_members(struct btf_type *t1, struct btf_type *t2)
3607{
3608 const struct btf_enum *m1, *m2;
3609 __u16 vlen;
3610 int i;
3611
3612 vlen = btf_vlen(t1);
3613 m1 = btf_enum(t1);
3614 m2 = btf_enum(t2);
3615 for (i = 0; i < vlen; i++) {
3616 if (m1->name_off != m2->name_off || m1->val != m2->val)
3617 return false;
3618 m1++;
3619 m2++;
3620 }
3621 return true;
3622}
3623
3624static bool btf_equal_enum64_members(struct btf_type *t1, struct btf_type *t2)
3625{
3626 const struct btf_enum64 *m1, *m2;
3627 __u16 vlen;
3628 int i;
3629
3630 vlen = btf_vlen(t1);
3631 m1 = btf_enum64(t1);
3632 m2 = btf_enum64(t2);
3633 for (i = 0; i < vlen; i++) {
3634 if (m1->name_off != m2->name_off || m1->val_lo32 != m2->val_lo32 ||
3635 m1->val_hi32 != m2->val_hi32)
3636 return false;
3637 m1++;
3638 m2++;
3639 }
3640 return true;
3641}
3642
3643/* Check structural equality of two ENUMs or ENUM64s. */
3644static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
3645{
3646 if (!btf_equal_common(t1, t2))
3647 return false;
3648
3649 /* t1 & t2 kinds are identical because of btf_equal_common */
3650 if (btf_kind(t1) == BTF_KIND_ENUM)
3651 return btf_equal_enum_members(t1, t2);
3652 else
3653 return btf_equal_enum64_members(t1, t2);
3654}
3655
3656static inline bool btf_is_enum_fwd(struct btf_type *t)
3657{
3658 return btf_is_any_enum(t) && btf_vlen(t) == 0;
3659}
3660
3661static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
3662{
3663 if (!btf_is_enum_fwd(t1) && !btf_is_enum_fwd(t2))
3664 return btf_equal_enum(t1, t2);
3665 /* At this point either t1 or t2 or both are forward declarations, thus:
3666 * - skip comparing vlen because it is zero for forward declarations;
3667 * - skip comparing size to allow enum forward declarations
3668 * to be compatible with enum64 full declarations;
3669 * - skip comparing kind for the same reason.
3670 */
3671 return t1->name_off == t2->name_off &&
3672 btf_is_any_enum(t1) && btf_is_any_enum(t2);
3673}
3674
3675/*
3676 * Calculate type signature hash of STRUCT/UNION, ignoring referenced type IDs,
3677 * as referenced type IDs equivalence is established separately during type
3678 * graph equivalence check algorithm.
3679 */
3680static long btf_hash_struct(struct btf_type *t)
3681{
3682 const struct btf_member *member = btf_members(t);
3683 __u32 vlen = btf_vlen(t);
3684 long h = btf_hash_common(t);
3685 int i;
3686
3687 for (i = 0; i < vlen; i++) {
3688 h = hash_combine(h, member->name_off);
3689 h = hash_combine(h, member->offset);
3690 /* no hashing of referenced type ID, it can be unresolved yet */
3691 member++;
3692 }
3693 return h;
3694}
3695
3696/*
3697 * Check structural compatibility of two STRUCTs/UNIONs, ignoring referenced
3698 * type IDs. This check is performed during type graph equivalence check and
3699 * referenced types equivalence is checked separately.
3700 */
3701static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
3702{
3703 const struct btf_member *m1, *m2;
3704 __u16 vlen;
3705 int i;
3706
3707 if (!btf_equal_common(t1, t2))
3708 return false;
3709
3710 vlen = btf_vlen(t1);
3711 m1 = btf_members(t1);
3712 m2 = btf_members(t2);
3713 for (i = 0; i < vlen; i++) {
3714 if (m1->name_off != m2->name_off || m1->offset != m2->offset)
3715 return false;
3716 m1++;
3717 m2++;
3718 }
3719 return true;
3720}
3721
3722/*
3723 * Calculate type signature hash of ARRAY, including referenced type IDs,
3724 * under assumption that they were already resolved to canonical type IDs and
3725 * are not going to change.
3726 */
3727static long btf_hash_array(struct btf_type *t)
3728{
3729 const struct btf_array *info = btf_array(t);
3730 long h = btf_hash_common(t);
3731
3732 h = hash_combine(h, info->type);
3733 h = hash_combine(h, info->index_type);
3734 h = hash_combine(h, info->nelems);
3735 return h;
3736}
3737
3738/*
3739 * Check exact equality of two ARRAYs, taking into account referenced
3740 * type IDs, under assumption that they were already resolved to canonical
3741 * type IDs and are not going to change.
3742 * This function is called during reference types deduplication to compare
3743 * ARRAY to potential canonical representative.
3744 */
3745static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
3746{
3747 const struct btf_array *info1, *info2;
3748
3749 if (!btf_equal_common(t1, t2))
3750 return false;
3751
3752 info1 = btf_array(t1);
3753 info2 = btf_array(t2);
3754 return info1->type == info2->type &&
3755 info1->index_type == info2->index_type &&
3756 info1->nelems == info2->nelems;
3757}
3758
3759/*
3760 * Check structural compatibility of two ARRAYs, ignoring referenced type
3761 * IDs. This check is performed during type graph equivalence check and
3762 * referenced types equivalence is checked separately.
3763 */
3764static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
3765{
3766 if (!btf_equal_common(t1, t2))
3767 return false;
3768
3769 return btf_array(t1)->nelems == btf_array(t2)->nelems;
3770}
3771
3772/*
3773 * Calculate type signature hash of FUNC_PROTO, including referenced type IDs,
3774 * under assumption that they were already resolved to canonical type IDs and
3775 * are not going to change.
3776 */
3777static long btf_hash_fnproto(struct btf_type *t)
3778{
3779 const struct btf_param *member = btf_params(t);
3780 __u16 vlen = btf_vlen(t);
3781 long h = btf_hash_common(t);
3782 int i;
3783
3784 for (i = 0; i < vlen; i++) {
3785 h = hash_combine(h, member->name_off);
3786 h = hash_combine(h, member->type);
3787 member++;
3788 }
3789 return h;
3790}
3791
3792/*
3793 * Check exact equality of two FUNC_PROTOs, taking into account referenced
3794 * type IDs, under assumption that they were already resolved to canonical
3795 * type IDs and are not going to change.
3796 * This function is called during reference types deduplication to compare
3797 * FUNC_PROTO to potential canonical representative.
3798 */
3799static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
3800{
3801 const struct btf_param *m1, *m2;
3802 __u16 vlen;
3803 int i;
3804
3805 if (!btf_equal_common(t1, t2))
3806 return false;
3807
3808 vlen = btf_vlen(t1);
3809 m1 = btf_params(t1);
3810 m2 = btf_params(t2);
3811 for (i = 0; i < vlen; i++) {
3812 if (m1->name_off != m2->name_off || m1->type != m2->type)
3813 return false;
3814 m1++;
3815 m2++;
3816 }
3817 return true;
3818}
3819
3820/*
3821 * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
3822 * IDs. This check is performed during type graph equivalence check and
3823 * referenced types equivalence is checked separately.
3824 */
3825static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
3826{
3827 const struct btf_param *m1, *m2;
3828 __u16 vlen;
3829 int i;
3830
3831 /* skip return type ID */
3832 if (t1->name_off != t2->name_off || t1->info != t2->info)
3833 return false;
3834
3835 vlen = btf_vlen(t1);
3836 m1 = btf_params(t1);
3837 m2 = btf_params(t2);
3838 for (i = 0; i < vlen; i++) {
3839 if (m1->name_off != m2->name_off)
3840 return false;
3841 m1++;
3842 m2++;
3843 }
3844 return true;
3845}
3846
3847/* Prepare split BTF for deduplication by calculating hashes of base BTF's
3848 * types and initializing the rest of the state (canonical type mapping) for
3849 * the fixed base BTF part.
3850 */
3851static int btf_dedup_prep(struct btf_dedup *d)
3852{
3853 struct btf_type *t;
3854 int type_id;
3855 long h;
3856
3857 if (!d->btf->base_btf)
3858 return 0;
3859
3860 for (type_id = 1; type_id < d->btf->start_id; type_id++) {
3861 t = btf_type_by_id(d->btf, type_id);
3862
3863 /* all base BTF types are self-canonical by definition */
3864 d->map[type_id] = type_id;
3865
3866 switch (btf_kind(t)) {
3867 case BTF_KIND_VAR:
3868 case BTF_KIND_DATASEC:
3869 /* VAR and DATASEC are never hash/deduplicated */
3870 continue;
3871 case BTF_KIND_CONST:
3872 case BTF_KIND_VOLATILE:
3873 case BTF_KIND_RESTRICT:
3874 case BTF_KIND_PTR:
3875 case BTF_KIND_FWD:
3876 case BTF_KIND_TYPEDEF:
3877 case BTF_KIND_FUNC:
3878 case BTF_KIND_FLOAT:
3879 case BTF_KIND_TYPE_TAG:
3880 h = btf_hash_common(t);
3881 break;
3882 case BTF_KIND_INT:
3883 case BTF_KIND_DECL_TAG:
3884 h = btf_hash_int_decl_tag(t);
3885 break;
3886 case BTF_KIND_ENUM:
3887 case BTF_KIND_ENUM64:
3888 h = btf_hash_enum(t);
3889 break;
3890 case BTF_KIND_STRUCT:
3891 case BTF_KIND_UNION:
3892 h = btf_hash_struct(t);
3893 break;
3894 case BTF_KIND_ARRAY:
3895 h = btf_hash_array(t);
3896 break;
3897 case BTF_KIND_FUNC_PROTO:
3898 h = btf_hash_fnproto(t);
3899 break;
3900 default:
3901 pr_debug("unknown kind %d for type [%d]\n", btf_kind(t), type_id);
3902 return -EINVAL;
3903 }
3904 if (btf_dedup_table_add(d, h, type_id))
3905 return -ENOMEM;
3906 }
3907
3908 return 0;
3909}
3910
3911/*
3912 * Deduplicate primitive types, that can't reference other types, by calculating
3913 * their type signature hash and comparing them with any possible canonical
3914 * candidate. If no canonical candidate matches, type itself is marked as
3915 * canonical and is added into `btf_dedup->dedup_table` as another candidate.
3916 */
3917static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
3918{
3919 struct btf_type *t = btf_type_by_id(d->btf, type_id);
3920 struct hashmap_entry *hash_entry;
3921 struct btf_type *cand;
3922 /* if we don't find equivalent type, then we are canonical */
3923 __u32 new_id = type_id;
3924 __u32 cand_id;
3925 long h;
3926
3927 switch (btf_kind(t)) {
3928 case BTF_KIND_CONST:
3929 case BTF_KIND_VOLATILE:
3930 case BTF_KIND_RESTRICT:
3931 case BTF_KIND_PTR:
3932 case BTF_KIND_TYPEDEF:
3933 case BTF_KIND_ARRAY:
3934 case BTF_KIND_STRUCT:
3935 case BTF_KIND_UNION:
3936 case BTF_KIND_FUNC:
3937 case BTF_KIND_FUNC_PROTO:
3938 case BTF_KIND_VAR:
3939 case BTF_KIND_DATASEC:
3940 case BTF_KIND_DECL_TAG:
3941 case BTF_KIND_TYPE_TAG:
3942 return 0;
3943
3944 case BTF_KIND_INT:
3945 h = btf_hash_int_decl_tag(t);
3946 for_each_dedup_cand(d, hash_entry, h) {
3947 cand_id = hash_entry->value;
3948 cand = btf_type_by_id(d->btf, cand_id);
3949 if (btf_equal_int_tag(t, cand)) {
3950 new_id = cand_id;
3951 break;
3952 }
3953 }
3954 break;
3955
3956 case BTF_KIND_ENUM:
3957 case BTF_KIND_ENUM64:
3958 h = btf_hash_enum(t);
3959 for_each_dedup_cand(d, hash_entry, h) {
3960 cand_id = hash_entry->value;
3961 cand = btf_type_by_id(d->btf, cand_id);
3962 if (btf_equal_enum(t, cand)) {
3963 new_id = cand_id;
3964 break;
3965 }
3966 if (btf_compat_enum(t, cand)) {
3967 if (btf_is_enum_fwd(t)) {
3968 /* resolve fwd to full enum */
3969 new_id = cand_id;
3970 break;
3971 }
3972 /* resolve canonical enum fwd to full enum */
3973 d->map[cand_id] = type_id;
3974 }
3975 }
3976 break;
3977
3978 case BTF_KIND_FWD:
3979 case BTF_KIND_FLOAT:
3980 h = btf_hash_common(t);
3981 for_each_dedup_cand(d, hash_entry, h) {
3982 cand_id = hash_entry->value;
3983 cand = btf_type_by_id(d->btf, cand_id);
3984 if (btf_equal_common(t, cand)) {
3985 new_id = cand_id;
3986 break;
3987 }
3988 }
3989 break;
3990
3991 default:
3992 return -EINVAL;
3993 }
3994
3995 d->map[type_id] = new_id;
3996 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
3997 return -ENOMEM;
3998
3999 return 0;
4000}
4001
4002static int btf_dedup_prim_types(struct btf_dedup *d)
4003{
4004 int i, err;
4005
4006 for (i = 0; i < d->btf->nr_types; i++) {
4007 err = btf_dedup_prim_type(d, d->btf->start_id + i);
4008 if (err)
4009 return err;
4010 }
4011 return 0;
4012}
4013
4014/*
4015 * Check whether type is already mapped into canonical one (could be to itself).
4016 */
4017static inline bool is_type_mapped(struct btf_dedup *d, uint32_t type_id)
4018{
4019 return d->map[type_id] <= BTF_MAX_NR_TYPES;
4020}
4021
4022/*
4023 * Resolve type ID into its canonical type ID, if any; otherwise return original
4024 * type ID. If type is FWD and is resolved into STRUCT/UNION already, follow
4025 * STRUCT/UNION link and resolve it into canonical type ID as well.
4026 */
4027static inline __u32 resolve_type_id(struct btf_dedup *d, __u32 type_id)
4028{
4029 while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
4030 type_id = d->map[type_id];
4031 return type_id;
4032}
4033
4034/*
4035 * Resolve FWD to underlying STRUCT/UNION, if any; otherwise return original
4036 * type ID.
4037 */
4038static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
4039{
4040 __u32 orig_type_id = type_id;
4041
4042 if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
4043 return type_id;
4044
4045 while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
4046 type_id = d->map[type_id];
4047
4048 if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
4049 return type_id;
4050
4051 return orig_type_id;
4052}
4053
4054
4055static inline __u16 btf_fwd_kind(struct btf_type *t)
4056{
4057 return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
4058}
4059
4060/* Check if given two types are identical ARRAY definitions */
4061static bool btf_dedup_identical_arrays(struct btf_dedup *d, __u32 id1, __u32 id2)
4062{
4063 struct btf_type *t1, *t2;
4064
4065 t1 = btf_type_by_id(d->btf, id1);
4066 t2 = btf_type_by_id(d->btf, id2);
4067 if (!btf_is_array(t1) || !btf_is_array(t2))
4068 return false;
4069
4070 return btf_equal_array(t1, t2);
4071}
4072
4073/* Check if given two types are identical STRUCT/UNION definitions */
4074static bool btf_dedup_identical_structs(struct btf_dedup *d, __u32 id1, __u32 id2)
4075{
4076 const struct btf_member *m1, *m2;
4077 struct btf_type *t1, *t2;
4078 int n, i;
4079
4080 t1 = btf_type_by_id(d->btf, id1);
4081 t2 = btf_type_by_id(d->btf, id2);
4082
4083 if (!btf_is_composite(t1) || btf_kind(t1) != btf_kind(t2))
4084 return false;
4085
4086 if (!btf_shallow_equal_struct(t1, t2))
4087 return false;
4088
4089 m1 = btf_members(t1);
4090 m2 = btf_members(t2);
4091 for (i = 0, n = btf_vlen(t1); i < n; i++, m1++, m2++) {
4092 if (m1->type != m2->type &&
4093 !btf_dedup_identical_arrays(d, m1->type, m2->type) &&
4094 !btf_dedup_identical_structs(d, m1->type, m2->type))
4095 return false;
4096 }
4097 return true;
4098}
4099
4100/*
4101 * Check equivalence of BTF type graph formed by candidate struct/union (we'll
4102 * call it "candidate graph" in this description for brevity) to a type graph
4103 * formed by (potential) canonical struct/union ("canonical graph" for brevity
4104 * here, though keep in mind that not all types in canonical graph are
4105 * necessarily canonical representatives themselves, some of them might be
4106 * duplicates or its uniqueness might not have been established yet).
4107 * Returns:
4108 * - >0, if type graphs are equivalent;
4109 * - 0, if not equivalent;
4110 * - <0, on error.
4111 *
4112 * Algorithm performs side-by-side DFS traversal of both type graphs and checks
4113 * equivalence of BTF types at each step. If at any point BTF types in candidate
4114 * and canonical graphs are not compatible structurally, whole graphs are
4115 * incompatible. If types are structurally equivalent (i.e., all information
4116 * except referenced type IDs is exactly the same), a mapping from `canon_id` to
4117 * a `cand_id` is recored in hypothetical mapping (`btf_dedup->hypot_map`).
4118 * If a type references other types, then those referenced types are checked
4119 * for equivalence recursively.
4120 *
4121 * During DFS traversal, if we find that for current `canon_id` type we
4122 * already have some mapping in hypothetical map, we check for two possible
4123 * situations:
4124 * - `canon_id` is mapped to exactly the same type as `cand_id`. This will
4125 * happen when type graphs have cycles. In this case we assume those two
4126 * types are equivalent.
4127 * - `canon_id` is mapped to different type. This is contradiction in our
4128 * hypothetical mapping, because same graph in canonical graph corresponds
4129 * to two different types in candidate graph, which for equivalent type
4130 * graphs shouldn't happen. This condition terminates equivalence check
4131 * with negative result.
4132 *
4133 * If type graphs traversal exhausts types to check and find no contradiction,
4134 * then type graphs are equivalent.
4135 *
4136 * When checking types for equivalence, there is one special case: FWD types.
4137 * If FWD type resolution is allowed and one of the types (either from canonical
4138 * or candidate graph) is FWD and other is STRUCT/UNION (depending on FWD's kind
4139 * flag) and their names match, hypothetical mapping is updated to point from
4140 * FWD to STRUCT/UNION. If graphs will be determined as equivalent successfully,
4141 * this mapping will be used to record FWD -> STRUCT/UNION mapping permanently.
4142 *
4143 * Technically, this could lead to incorrect FWD to STRUCT/UNION resolution,
4144 * if there are two exactly named (or anonymous) structs/unions that are
4145 * compatible structurally, one of which has FWD field, while other is concrete
4146 * STRUCT/UNION, but according to C sources they are different structs/unions
4147 * that are referencing different types with the same name. This is extremely
4148 * unlikely to happen, but btf_dedup API allows to disable FWD resolution if
4149 * this logic is causing problems.
4150 *
4151 * Doing FWD resolution means that both candidate and/or canonical graphs can
4152 * consists of portions of the graph that come from multiple compilation units.
4153 * This is due to the fact that types within single compilation unit are always
4154 * deduplicated and FWDs are already resolved, if referenced struct/union
4155 * definiton is available. So, if we had unresolved FWD and found corresponding
4156 * STRUCT/UNION, they will be from different compilation units. This
4157 * consequently means that when we "link" FWD to corresponding STRUCT/UNION,
4158 * type graph will likely have at least two different BTF types that describe
4159 * same type (e.g., most probably there will be two different BTF types for the
4160 * same 'int' primitive type) and could even have "overlapping" parts of type
4161 * graph that describe same subset of types.
4162 *
4163 * This in turn means that our assumption that each type in canonical graph
4164 * must correspond to exactly one type in candidate graph might not hold
4165 * anymore and will make it harder to detect contradictions using hypothetical
4166 * map. To handle this problem, we allow to follow FWD -> STRUCT/UNION
4167 * resolution only in canonical graph. FWDs in candidate graphs are never
4168 * resolved. To see why it's OK, let's check all possible situations w.r.t. FWDs
4169 * that can occur:
4170 * - Both types in canonical and candidate graphs are FWDs. If they are
4171 * structurally equivalent, then they can either be both resolved to the
4172 * same STRUCT/UNION or not resolved at all. In both cases they are
4173 * equivalent and there is no need to resolve FWD on candidate side.
4174 * - Both types in canonical and candidate graphs are concrete STRUCT/UNION,
4175 * so nothing to resolve as well, algorithm will check equivalence anyway.
4176 * - Type in canonical graph is FWD, while type in candidate is concrete
4177 * STRUCT/UNION. In this case candidate graph comes from single compilation
4178 * unit, so there is exactly one BTF type for each unique C type. After
4179 * resolving FWD into STRUCT/UNION, there might be more than one BTF type
4180 * in canonical graph mapping to single BTF type in candidate graph, but
4181 * because hypothetical mapping maps from canonical to candidate types, it's
4182 * alright, and we still maintain the property of having single `canon_id`
4183 * mapping to single `cand_id` (there could be two different `canon_id`
4184 * mapped to the same `cand_id`, but it's not contradictory).
4185 * - Type in canonical graph is concrete STRUCT/UNION, while type in candidate
4186 * graph is FWD. In this case we are just going to check compatibility of
4187 * STRUCT/UNION and corresponding FWD, and if they are compatible, we'll
4188 * assume that whatever STRUCT/UNION FWD resolves to must be equivalent to
4189 * a concrete STRUCT/UNION from canonical graph. If the rest of type graphs
4190 * turn out equivalent, we'll re-resolve FWD to concrete STRUCT/UNION from
4191 * canonical graph.
4192 */
4193static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
4194 __u32 canon_id)
4195{
4196 struct btf_type *cand_type;
4197 struct btf_type *canon_type;
4198 __u32 hypot_type_id;
4199 __u16 cand_kind;
4200 __u16 canon_kind;
4201 int i, eq;
4202
4203 /* if both resolve to the same canonical, they must be equivalent */
4204 if (resolve_type_id(d, cand_id) == resolve_type_id(d, canon_id))
4205 return 1;
4206
4207 canon_id = resolve_fwd_id(d, canon_id);
4208
4209 hypot_type_id = d->hypot_map[canon_id];
4210 if (hypot_type_id <= BTF_MAX_NR_TYPES) {
4211 if (hypot_type_id == cand_id)
4212 return 1;
4213 /* In some cases compiler will generate different DWARF types
4214 * for *identical* array type definitions and use them for
4215 * different fields within the *same* struct. This breaks type
4216 * equivalence check, which makes an assumption that candidate
4217 * types sub-graph has a consistent and deduped-by-compiler
4218 * types within a single CU. So work around that by explicitly
4219 * allowing identical array types here.
4220 */
4221 if (btf_dedup_identical_arrays(d, hypot_type_id, cand_id))
4222 return 1;
4223 /* It turns out that similar situation can happen with
4224 * struct/union sometimes, sigh... Handle the case where
4225 * structs/unions are exactly the same, down to the referenced
4226 * type IDs. Anything more complicated (e.g., if referenced
4227 * types are different, but equivalent) is *way more*
4228 * complicated and requires a many-to-many equivalence mapping.
4229 */
4230 if (btf_dedup_identical_structs(d, hypot_type_id, cand_id))
4231 return 1;
4232 return 0;
4233 }
4234
4235 if (btf_dedup_hypot_map_add(d, canon_id, cand_id))
4236 return -ENOMEM;
4237
4238 cand_type = btf_type_by_id(d->btf, cand_id);
4239 canon_type = btf_type_by_id(d->btf, canon_id);
4240 cand_kind = btf_kind(cand_type);
4241 canon_kind = btf_kind(canon_type);
4242
4243 if (cand_type->name_off != canon_type->name_off)
4244 return 0;
4245
4246 /* FWD <--> STRUCT/UNION equivalence check, if enabled */
4247 if ((cand_kind == BTF_KIND_FWD || canon_kind == BTF_KIND_FWD)
4248 && cand_kind != canon_kind) {
4249 __u16 real_kind;
4250 __u16 fwd_kind;
4251
4252 if (cand_kind == BTF_KIND_FWD) {
4253 real_kind = canon_kind;
4254 fwd_kind = btf_fwd_kind(cand_type);
4255 } else {
4256 real_kind = cand_kind;
4257 fwd_kind = btf_fwd_kind(canon_type);
4258 /* we'd need to resolve base FWD to STRUCT/UNION */
4259 if (fwd_kind == real_kind && canon_id < d->btf->start_id)
4260 d->hypot_adjust_canon = true;
4261 }
4262 return fwd_kind == real_kind;
4263 }
4264
4265 if (cand_kind != canon_kind)
4266 return 0;
4267
4268 switch (cand_kind) {
4269 case BTF_KIND_INT:
4270 return btf_equal_int_tag(cand_type, canon_type);
4271
4272 case BTF_KIND_ENUM:
4273 case BTF_KIND_ENUM64:
4274 return btf_compat_enum(cand_type, canon_type);
4275
4276 case BTF_KIND_FWD:
4277 case BTF_KIND_FLOAT:
4278 return btf_equal_common(cand_type, canon_type);
4279
4280 case BTF_KIND_CONST:
4281 case BTF_KIND_VOLATILE:
4282 case BTF_KIND_RESTRICT:
4283 case BTF_KIND_PTR:
4284 case BTF_KIND_TYPEDEF:
4285 case BTF_KIND_FUNC:
4286 case BTF_KIND_TYPE_TAG:
4287 if (cand_type->info != canon_type->info)
4288 return 0;
4289 return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
4290
4291 case BTF_KIND_ARRAY: {
4292 const struct btf_array *cand_arr, *canon_arr;
4293
4294 if (!btf_compat_array(cand_type, canon_type))
4295 return 0;
4296 cand_arr = btf_array(cand_type);
4297 canon_arr = btf_array(canon_type);
4298 eq = btf_dedup_is_equiv(d, cand_arr->index_type, canon_arr->index_type);
4299 if (eq <= 0)
4300 return eq;
4301 return btf_dedup_is_equiv(d, cand_arr->type, canon_arr->type);
4302 }
4303
4304 case BTF_KIND_STRUCT:
4305 case BTF_KIND_UNION: {
4306 const struct btf_member *cand_m, *canon_m;
4307 __u16 vlen;
4308
4309 if (!btf_shallow_equal_struct(cand_type, canon_type))
4310 return 0;
4311 vlen = btf_vlen(cand_type);
4312 cand_m = btf_members(cand_type);
4313 canon_m = btf_members(canon_type);
4314 for (i = 0; i < vlen; i++) {
4315 eq = btf_dedup_is_equiv(d, cand_m->type, canon_m->type);
4316 if (eq <= 0)
4317 return eq;
4318 cand_m++;
4319 canon_m++;
4320 }
4321
4322 return 1;
4323 }
4324
4325 case BTF_KIND_FUNC_PROTO: {
4326 const struct btf_param *cand_p, *canon_p;
4327 __u16 vlen;
4328
4329 if (!btf_compat_fnproto(cand_type, canon_type))
4330 return 0;
4331 eq = btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
4332 if (eq <= 0)
4333 return eq;
4334 vlen = btf_vlen(cand_type);
4335 cand_p = btf_params(cand_type);
4336 canon_p = btf_params(canon_type);
4337 for (i = 0; i < vlen; i++) {
4338 eq = btf_dedup_is_equiv(d, cand_p->type, canon_p->type);
4339 if (eq <= 0)
4340 return eq;
4341 cand_p++;
4342 canon_p++;
4343 }
4344 return 1;
4345 }
4346
4347 default:
4348 return -EINVAL;
4349 }
4350 return 0;
4351}
4352
4353/*
4354 * Use hypothetical mapping, produced by successful type graph equivalence
4355 * check, to augment existing struct/union canonical mapping, where possible.
4356 *
4357 * If BTF_KIND_FWD resolution is allowed, this mapping is also used to record
4358 * FWD -> STRUCT/UNION correspondence as well. FWD resolution is bidirectional:
4359 * it doesn't matter if FWD type was part of canonical graph or candidate one,
4360 * we are recording the mapping anyway. As opposed to carefulness required
4361 * for struct/union correspondence mapping (described below), for FWD resolution
4362 * it's not important, as by the time that FWD type (reference type) will be
4363 * deduplicated all structs/unions will be deduped already anyway.
4364 *
4365 * Recording STRUCT/UNION mapping is purely a performance optimization and is
4366 * not required for correctness. It needs to be done carefully to ensure that
4367 * struct/union from candidate's type graph is not mapped into corresponding
4368 * struct/union from canonical type graph that itself hasn't been resolved into
4369 * canonical representative. The only guarantee we have is that canonical
4370 * struct/union was determined as canonical and that won't change. But any
4371 * types referenced through that struct/union fields could have been not yet
4372 * resolved, so in case like that it's too early to establish any kind of
4373 * correspondence between structs/unions.
4374 *
4375 * No canonical correspondence is derived for primitive types (they are already
4376 * deduplicated completely already anyway) or reference types (they rely on
4377 * stability of struct/union canonical relationship for equivalence checks).
4378 */
4379static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
4380{
4381 __u32 canon_type_id, targ_type_id;
4382 __u16 t_kind, c_kind;
4383 __u32 t_id, c_id;
4384 int i;
4385
4386 for (i = 0; i < d->hypot_cnt; i++) {
4387 canon_type_id = d->hypot_list[i];
4388 targ_type_id = d->hypot_map[canon_type_id];
4389 t_id = resolve_type_id(d, targ_type_id);
4390 c_id = resolve_type_id(d, canon_type_id);
4391 t_kind = btf_kind(btf__type_by_id(d->btf, t_id));
4392 c_kind = btf_kind(btf__type_by_id(d->btf, c_id));
4393 /*
4394 * Resolve FWD into STRUCT/UNION.
4395 * It's ok to resolve FWD into STRUCT/UNION that's not yet
4396 * mapped to canonical representative (as opposed to
4397 * STRUCT/UNION <--> STRUCT/UNION mapping logic below), because
4398 * eventually that struct is going to be mapped and all resolved
4399 * FWDs will automatically resolve to correct canonical
4400 * representative. This will happen before ref type deduping,
4401 * which critically depends on stability of these mapping. This
4402 * stability is not a requirement for STRUCT/UNION equivalence
4403 * checks, though.
4404 */
4405
4406 /* if it's the split BTF case, we still need to point base FWD
4407 * to STRUCT/UNION in a split BTF, because FWDs from split BTF
4408 * will be resolved against base FWD. If we don't point base
4409 * canonical FWD to the resolved STRUCT/UNION, then all the
4410 * FWDs in split BTF won't be correctly resolved to a proper
4411 * STRUCT/UNION.
4412 */
4413 if (t_kind != BTF_KIND_FWD && c_kind == BTF_KIND_FWD)
4414 d->map[c_id] = t_id;
4415
4416 /* if graph equivalence determined that we'd need to adjust
4417 * base canonical types, then we need to only point base FWDs
4418 * to STRUCTs/UNIONs and do no more modifications. For all
4419 * other purposes the type graphs were not equivalent.
4420 */
4421 if (d->hypot_adjust_canon)
4422 continue;
4423
4424 if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD)
4425 d->map[t_id] = c_id;
4426
4427 if ((t_kind == BTF_KIND_STRUCT || t_kind == BTF_KIND_UNION) &&
4428 c_kind != BTF_KIND_FWD &&
4429 is_type_mapped(d, c_id) &&
4430 !is_type_mapped(d, t_id)) {
4431 /*
4432 * as a perf optimization, we can map struct/union
4433 * that's part of type graph we just verified for
4434 * equivalence. We can do that for struct/union that has
4435 * canonical representative only, though.
4436 */
4437 d->map[t_id] = c_id;
4438 }
4439 }
4440}
4441
4442/*
4443 * Deduplicate struct/union types.
4444 *
4445 * For each struct/union type its type signature hash is calculated, taking
4446 * into account type's name, size, number, order and names of fields, but
4447 * ignoring type ID's referenced from fields, because they might not be deduped
4448 * completely until after reference types deduplication phase. This type hash
4449 * is used to iterate over all potential canonical types, sharing same hash.
4450 * For each canonical candidate we check whether type graphs that they form
4451 * (through referenced types in fields and so on) are equivalent using algorithm
4452 * implemented in `btf_dedup_is_equiv`. If such equivalence is found and
4453 * BTF_KIND_FWD resolution is allowed, then hypothetical mapping
4454 * (btf_dedup->hypot_map) produced by aforementioned type graph equivalence
4455 * algorithm is used to record FWD -> STRUCT/UNION mapping. It's also used to
4456 * potentially map other structs/unions to their canonical representatives,
4457 * if such relationship hasn't yet been established. This speeds up algorithm
4458 * by eliminating some of the duplicate work.
4459 *
4460 * If no matching canonical representative was found, struct/union is marked
4461 * as canonical for itself and is added into btf_dedup->dedup_table hash map
4462 * for further look ups.
4463 */
4464static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
4465{
4466 struct btf_type *cand_type, *t;
4467 struct hashmap_entry *hash_entry;
4468 /* if we don't find equivalent type, then we are canonical */
4469 __u32 new_id = type_id;
4470 __u16 kind;
4471 long h;
4472
4473 /* already deduped or is in process of deduping (loop detected) */
4474 if (d->map[type_id] <= BTF_MAX_NR_TYPES)
4475 return 0;
4476
4477 t = btf_type_by_id(d->btf, type_id);
4478 kind = btf_kind(t);
4479
4480 if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
4481 return 0;
4482
4483 h = btf_hash_struct(t);
4484 for_each_dedup_cand(d, hash_entry, h) {
4485 __u32 cand_id = hash_entry->value;
4486 int eq;
4487
4488 /*
4489 * Even though btf_dedup_is_equiv() checks for
4490 * btf_shallow_equal_struct() internally when checking two
4491 * structs (unions) for equivalence, we need to guard here
4492 * from picking matching FWD type as a dedup candidate.
4493 * This can happen due to hash collision. In such case just
4494 * relying on btf_dedup_is_equiv() would lead to potentially
4495 * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because
4496 * FWD and compatible STRUCT/UNION are considered equivalent.
4497 */
4498 cand_type = btf_type_by_id(d->btf, cand_id);
4499 if (!btf_shallow_equal_struct(t, cand_type))
4500 continue;
4501
4502 btf_dedup_clear_hypot_map(d);
4503 eq = btf_dedup_is_equiv(d, type_id, cand_id);
4504 if (eq < 0)
4505 return eq;
4506 if (!eq)
4507 continue;
4508 btf_dedup_merge_hypot_map(d);
4509 if (d->hypot_adjust_canon) /* not really equivalent */
4510 continue;
4511 new_id = cand_id;
4512 break;
4513 }
4514
4515 d->map[type_id] = new_id;
4516 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
4517 return -ENOMEM;
4518
4519 return 0;
4520}
4521
4522static int btf_dedup_struct_types(struct btf_dedup *d)
4523{
4524 int i, err;
4525
4526 for (i = 0; i < d->btf->nr_types; i++) {
4527 err = btf_dedup_struct_type(d, d->btf->start_id + i);
4528 if (err)
4529 return err;
4530 }
4531 return 0;
4532}
4533
4534/*
4535 * Deduplicate reference type.
4536 *
4537 * Once all primitive and struct/union types got deduplicated, we can easily
4538 * deduplicate all other (reference) BTF types. This is done in two steps:
4539 *
4540 * 1. Resolve all referenced type IDs into their canonical type IDs. This
4541 * resolution can be done either immediately for primitive or struct/union types
4542 * (because they were deduped in previous two phases) or recursively for
4543 * reference types. Recursion will always terminate at either primitive or
4544 * struct/union type, at which point we can "unwind" chain of reference types
4545 * one by one. There is no danger of encountering cycles because in C type
4546 * system the only way to form type cycle is through struct/union, so any chain
4547 * of reference types, even those taking part in a type cycle, will inevitably
4548 * reach struct/union at some point.
4549 *
4550 * 2. Once all referenced type IDs are resolved into canonical ones, BTF type
4551 * becomes "stable", in the sense that no further deduplication will cause
4552 * any changes to it. With that, it's now possible to calculate type's signature
4553 * hash (this time taking into account referenced type IDs) and loop over all
4554 * potential canonical representatives. If no match was found, current type
4555 * will become canonical representative of itself and will be added into
4556 * btf_dedup->dedup_table as another possible canonical representative.
4557 */
4558static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
4559{
4560 struct hashmap_entry *hash_entry;
4561 __u32 new_id = type_id, cand_id;
4562 struct btf_type *t, *cand;
4563 /* if we don't find equivalent type, then we are representative type */
4564 int ref_type_id;
4565 long h;
4566
4567 if (d->map[type_id] == BTF_IN_PROGRESS_ID)
4568 return -ELOOP;
4569 if (d->map[type_id] <= BTF_MAX_NR_TYPES)
4570 return resolve_type_id(d, type_id);
4571
4572 t = btf_type_by_id(d->btf, type_id);
4573 d->map[type_id] = BTF_IN_PROGRESS_ID;
4574
4575 switch (btf_kind(t)) {
4576 case BTF_KIND_CONST:
4577 case BTF_KIND_VOLATILE:
4578 case BTF_KIND_RESTRICT:
4579 case BTF_KIND_PTR:
4580 case BTF_KIND_TYPEDEF:
4581 case BTF_KIND_FUNC:
4582 case BTF_KIND_TYPE_TAG:
4583 ref_type_id = btf_dedup_ref_type(d, t->type);
4584 if (ref_type_id < 0)
4585 return ref_type_id;
4586 t->type = ref_type_id;
4587
4588 h = btf_hash_common(t);
4589 for_each_dedup_cand(d, hash_entry, h) {
4590 cand_id = hash_entry->value;
4591 cand = btf_type_by_id(d->btf, cand_id);
4592 if (btf_equal_common(t, cand)) {
4593 new_id = cand_id;
4594 break;
4595 }
4596 }
4597 break;
4598
4599 case BTF_KIND_DECL_TAG:
4600 ref_type_id = btf_dedup_ref_type(d, t->type);
4601 if (ref_type_id < 0)
4602 return ref_type_id;
4603 t->type = ref_type_id;
4604
4605 h = btf_hash_int_decl_tag(t);
4606 for_each_dedup_cand(d, hash_entry, h) {
4607 cand_id = hash_entry->value;
4608 cand = btf_type_by_id(d->btf, cand_id);
4609 if (btf_equal_int_tag(t, cand)) {
4610 new_id = cand_id;
4611 break;
4612 }
4613 }
4614 break;
4615
4616 case BTF_KIND_ARRAY: {
4617 struct btf_array *info = btf_array(t);
4618
4619 ref_type_id = btf_dedup_ref_type(d, info->type);
4620 if (ref_type_id < 0)
4621 return ref_type_id;
4622 info->type = ref_type_id;
4623
4624 ref_type_id = btf_dedup_ref_type(d, info->index_type);
4625 if (ref_type_id < 0)
4626 return ref_type_id;
4627 info->index_type = ref_type_id;
4628
4629 h = btf_hash_array(t);
4630 for_each_dedup_cand(d, hash_entry, h) {
4631 cand_id = hash_entry->value;
4632 cand = btf_type_by_id(d->btf, cand_id);
4633 if (btf_equal_array(t, cand)) {
4634 new_id = cand_id;
4635 break;
4636 }
4637 }
4638 break;
4639 }
4640
4641 case BTF_KIND_FUNC_PROTO: {
4642 struct btf_param *param;
4643 __u16 vlen;
4644 int i;
4645
4646 ref_type_id = btf_dedup_ref_type(d, t->type);
4647 if (ref_type_id < 0)
4648 return ref_type_id;
4649 t->type = ref_type_id;
4650
4651 vlen = btf_vlen(t);
4652 param = btf_params(t);
4653 for (i = 0; i < vlen; i++) {
4654 ref_type_id = btf_dedup_ref_type(d, param->type);
4655 if (ref_type_id < 0)
4656 return ref_type_id;
4657 param->type = ref_type_id;
4658 param++;
4659 }
4660
4661 h = btf_hash_fnproto(t);
4662 for_each_dedup_cand(d, hash_entry, h) {
4663 cand_id = hash_entry->value;
4664 cand = btf_type_by_id(d->btf, cand_id);
4665 if (btf_equal_fnproto(t, cand)) {
4666 new_id = cand_id;
4667 break;
4668 }
4669 }
4670 break;
4671 }
4672
4673 default:
4674 return -EINVAL;
4675 }
4676
4677 d->map[type_id] = new_id;
4678 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
4679 return -ENOMEM;
4680
4681 return new_id;
4682}
4683
4684static int btf_dedup_ref_types(struct btf_dedup *d)
4685{
4686 int i, err;
4687
4688 for (i = 0; i < d->btf->nr_types; i++) {
4689 err = btf_dedup_ref_type(d, d->btf->start_id + i);
4690 if (err < 0)
4691 return err;
4692 }
4693 /* we won't need d->dedup_table anymore */
4694 hashmap__free(d->dedup_table);
4695 d->dedup_table = NULL;
4696 return 0;
4697}
4698
4699/*
4700 * Collect a map from type names to type ids for all canonical structs
4701 * and unions. If the same name is shared by several canonical types
4702 * use a special value 0 to indicate this fact.
4703 */
4704static int btf_dedup_fill_unique_names_map(struct btf_dedup *d, struct hashmap *names_map)
4705{
4706 __u32 nr_types = btf__type_cnt(d->btf);
4707 struct btf_type *t;
4708 __u32 type_id;
4709 __u16 kind;
4710 int err;
4711
4712 /*
4713 * Iterate over base and split module ids in order to get all
4714 * available structs in the map.
4715 */
4716 for (type_id = 1; type_id < nr_types; ++type_id) {
4717 t = btf_type_by_id(d->btf, type_id);
4718 kind = btf_kind(t);
4719
4720 if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
4721 continue;
4722
4723 /* Skip non-canonical types */
4724 if (type_id != d->map[type_id])
4725 continue;
4726
4727 err = hashmap__add(names_map, t->name_off, type_id);
4728 if (err == -EEXIST)
4729 err = hashmap__set(names_map, t->name_off, 0, NULL, NULL);
4730
4731 if (err)
4732 return err;
4733 }
4734
4735 return 0;
4736}
4737
4738static int btf_dedup_resolve_fwd(struct btf_dedup *d, struct hashmap *names_map, __u32 type_id)
4739{
4740 struct btf_type *t = btf_type_by_id(d->btf, type_id);
4741 enum btf_fwd_kind fwd_kind = btf_kflag(t);
4742 __u16 cand_kind, kind = btf_kind(t);
4743 struct btf_type *cand_t;
4744 uintptr_t cand_id;
4745
4746 if (kind != BTF_KIND_FWD)
4747 return 0;
4748
4749 /* Skip if this FWD already has a mapping */
4750 if (type_id != d->map[type_id])
4751 return 0;
4752
4753 if (!hashmap__find(names_map, t->name_off, &cand_id))
4754 return 0;
4755
4756 /* Zero is a special value indicating that name is not unique */
4757 if (!cand_id)
4758 return 0;
4759
4760 cand_t = btf_type_by_id(d->btf, cand_id);
4761 cand_kind = btf_kind(cand_t);
4762 if ((cand_kind == BTF_KIND_STRUCT && fwd_kind != BTF_FWD_STRUCT) ||
4763 (cand_kind == BTF_KIND_UNION && fwd_kind != BTF_FWD_UNION))
4764 return 0;
4765
4766 d->map[type_id] = cand_id;
4767
4768 return 0;
4769}
4770
4771/*
4772 * Resolve unambiguous forward declarations.
4773 *
4774 * The lion's share of all FWD declarations is resolved during
4775 * `btf_dedup_struct_types` phase when different type graphs are
4776 * compared against each other. However, if in some compilation unit a
4777 * FWD declaration is not a part of a type graph compared against
4778 * another type graph that declaration's canonical type would not be
4779 * changed. Example:
4780 *
4781 * CU #1:
4782 *
4783 * struct foo;
4784 * struct foo *some_global;
4785 *
4786 * CU #2:
4787 *
4788 * struct foo { int u; };
4789 * struct foo *another_global;
4790 *
4791 * After `btf_dedup_struct_types` the BTF looks as follows:
4792 *
4793 * [1] STRUCT 'foo' size=4 vlen=1 ...
4794 * [2] INT 'int' size=4 ...
4795 * [3] PTR '(anon)' type_id=1
4796 * [4] FWD 'foo' fwd_kind=struct
4797 * [5] PTR '(anon)' type_id=4
4798 *
4799 * This pass assumes that such FWD declarations should be mapped to
4800 * structs or unions with identical name in case if the name is not
4801 * ambiguous.
4802 */
4803static int btf_dedup_resolve_fwds(struct btf_dedup *d)
4804{
4805 int i, err;
4806 struct hashmap *names_map;
4807
4808 names_map = hashmap__new(btf_dedup_identity_hash_fn, btf_dedup_equal_fn, NULL);
4809 if (IS_ERR(names_map))
4810 return PTR_ERR(names_map);
4811
4812 err = btf_dedup_fill_unique_names_map(d, names_map);
4813 if (err < 0)
4814 goto exit;
4815
4816 for (i = 0; i < d->btf->nr_types; i++) {
4817 err = btf_dedup_resolve_fwd(d, names_map, d->btf->start_id + i);
4818 if (err < 0)
4819 break;
4820 }
4821
4822exit:
4823 hashmap__free(names_map);
4824 return err;
4825}
4826
4827/*
4828 * Compact types.
4829 *
4830 * After we established for each type its corresponding canonical representative
4831 * type, we now can eliminate types that are not canonical and leave only
4832 * canonical ones layed out sequentially in memory by copying them over
4833 * duplicates. During compaction btf_dedup->hypot_map array is reused to store
4834 * a map from original type ID to a new compacted type ID, which will be used
4835 * during next phase to "fix up" type IDs, referenced from struct/union and
4836 * reference types.
4837 */
4838static int btf_dedup_compact_types(struct btf_dedup *d)
4839{
4840 __u32 *new_offs;
4841 __u32 next_type_id = d->btf->start_id;
4842 const struct btf_type *t;
4843 void *p;
4844 int i, id, len;
4845
4846 /* we are going to reuse hypot_map to store compaction remapping */
4847 d->hypot_map[0] = 0;
4848 /* base BTF types are not renumbered */
4849 for (id = 1; id < d->btf->start_id; id++)
4850 d->hypot_map[id] = id;
4851 for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++)
4852 d->hypot_map[id] = BTF_UNPROCESSED_ID;
4853
4854 p = d->btf->types_data;
4855
4856 for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++) {
4857 if (d->map[id] != id)
4858 continue;
4859
4860 t = btf__type_by_id(d->btf, id);
4861 len = btf_type_size(t);
4862 if (len < 0)
4863 return len;
4864
4865 memmove(p, t, len);
4866 d->hypot_map[id] = next_type_id;
4867 d->btf->type_offs[next_type_id - d->btf->start_id] = p - d->btf->types_data;
4868 p += len;
4869 next_type_id++;
4870 }
4871
4872 /* shrink struct btf's internal types index and update btf_header */
4873 d->btf->nr_types = next_type_id - d->btf->start_id;
4874 d->btf->type_offs_cap = d->btf->nr_types;
4875 d->btf->hdr->type_len = p - d->btf->types_data;
4876 new_offs = libbpf_reallocarray(d->btf->type_offs, d->btf->type_offs_cap,
4877 sizeof(*new_offs));
4878 if (d->btf->type_offs_cap && !new_offs)
4879 return -ENOMEM;
4880 d->btf->type_offs = new_offs;
4881 d->btf->hdr->str_off = d->btf->hdr->type_len;
4882 d->btf->raw_size = d->btf->hdr->hdr_len + d->btf->hdr->type_len + d->btf->hdr->str_len;
4883 return 0;
4884}
4885
4886/*
4887 * Figure out final (deduplicated and compacted) type ID for provided original
4888 * `type_id` by first resolving it into corresponding canonical type ID and
4889 * then mapping it to a deduplicated type ID, stored in btf_dedup->hypot_map,
4890 * which is populated during compaction phase.
4891 */
4892static int btf_dedup_remap_type_id(__u32 *type_id, void *ctx)
4893{
4894 struct btf_dedup *d = ctx;
4895 __u32 resolved_type_id, new_type_id;
4896
4897 resolved_type_id = resolve_type_id(d, *type_id);
4898 new_type_id = d->hypot_map[resolved_type_id];
4899 if (new_type_id > BTF_MAX_NR_TYPES)
4900 return -EINVAL;
4901
4902 *type_id = new_type_id;
4903 return 0;
4904}
4905
4906/*
4907 * Remap referenced type IDs into deduped type IDs.
4908 *
4909 * After BTF types are deduplicated and compacted, their final type IDs may
4910 * differ from original ones. The map from original to a corresponding
4911 * deduped type ID is stored in btf_dedup->hypot_map and is populated during
4912 * compaction phase. During remapping phase we are rewriting all type IDs
4913 * referenced from any BTF type (e.g., struct fields, func proto args, etc) to
4914 * their final deduped type IDs.
4915 */
4916static int btf_dedup_remap_types(struct btf_dedup *d)
4917{
4918 int i, r;
4919
4920 for (i = 0; i < d->btf->nr_types; i++) {
4921 struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
4922
4923 r = btf_type_visit_type_ids(t, btf_dedup_remap_type_id, d);
4924 if (r)
4925 return r;
4926 }
4927
4928 if (!d->btf_ext)
4929 return 0;
4930
4931 r = btf_ext_visit_type_ids(d->btf_ext, btf_dedup_remap_type_id, d);
4932 if (r)
4933 return r;
4934
4935 return 0;
4936}
4937
4938/*
4939 * Probe few well-known locations for vmlinux kernel image and try to load BTF
4940 * data out of it to use for target BTF.
4941 */
4942struct btf *btf__load_vmlinux_btf(void)
4943{
4944 const char *sysfs_btf_path = "/sys/kernel/btf/vmlinux";
4945 /* fall back locations, trying to find vmlinux on disk */
4946 const char *locations[] = {
4947 "/boot/vmlinux-%1$s",
4948 "/lib/modules/%1$s/vmlinux-%1$s",
4949 "/lib/modules/%1$s/build/vmlinux",
4950 "/usr/lib/modules/%1$s/kernel/vmlinux",
4951 "/usr/lib/debug/boot/vmlinux-%1$s",
4952 "/usr/lib/debug/boot/vmlinux-%1$s.debug",
4953 "/usr/lib/debug/lib/modules/%1$s/vmlinux",
4954 };
4955 char path[PATH_MAX + 1];
4956 struct utsname buf;
4957 struct btf *btf;
4958 int i, err;
4959
4960 /* is canonical sysfs location accessible? */
4961 if (faccessat(AT_FDCWD, sysfs_btf_path, F_OK, AT_EACCESS) < 0) {
4962 pr_warn("kernel BTF is missing at '%s', was CONFIG_DEBUG_INFO_BTF enabled?\n",
4963 sysfs_btf_path);
4964 } else {
4965 btf = btf__parse(sysfs_btf_path, NULL);
4966 if (!btf) {
4967 err = -errno;
4968 pr_warn("failed to read kernel BTF from '%s': %d\n", sysfs_btf_path, err);
4969 return libbpf_err_ptr(err);
4970 }
4971 pr_debug("loaded kernel BTF from '%s'\n", sysfs_btf_path);
4972 return btf;
4973 }
4974
4975 /* try fallback locations */
4976 uname(&buf);
4977 for (i = 0; i < ARRAY_SIZE(locations); i++) {
4978 snprintf(path, PATH_MAX, locations[i], buf.release);
4979
4980 if (faccessat(AT_FDCWD, path, R_OK, AT_EACCESS))
4981 continue;
4982
4983 btf = btf__parse(path, NULL);
4984 err = libbpf_get_error(btf);
4985 pr_debug("loading kernel BTF '%s': %d\n", path, err);
4986 if (err)
4987 continue;
4988
4989 return btf;
4990 }
4991
4992 pr_warn("failed to find valid kernel BTF\n");
4993 return libbpf_err_ptr(-ESRCH);
4994}
4995
4996struct btf *libbpf_find_kernel_btf(void) __attribute__((alias("btf__load_vmlinux_btf")));
4997
4998struct btf *btf__load_module_btf(const char *module_name, struct btf *vmlinux_btf)
4999{
5000 char path[80];
5001
5002 snprintf(path, sizeof(path), "/sys/kernel/btf/%s", module_name);
5003 return btf__parse_split(path, vmlinux_btf);
5004}
5005
5006int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx)
5007{
5008 int i, n, err;
5009
5010 switch (btf_kind(t)) {
5011 case BTF_KIND_INT:
5012 case BTF_KIND_FLOAT:
5013 case BTF_KIND_ENUM:
5014 case BTF_KIND_ENUM64:
5015 return 0;
5016
5017 case BTF_KIND_FWD:
5018 case BTF_KIND_CONST:
5019 case BTF_KIND_VOLATILE:
5020 case BTF_KIND_RESTRICT:
5021 case BTF_KIND_PTR:
5022 case BTF_KIND_TYPEDEF:
5023 case BTF_KIND_FUNC:
5024 case BTF_KIND_VAR:
5025 case BTF_KIND_DECL_TAG:
5026 case BTF_KIND_TYPE_TAG:
5027 return visit(&t->type, ctx);
5028
5029 case BTF_KIND_ARRAY: {
5030 struct btf_array *a = btf_array(t);
5031
5032 err = visit(&a->type, ctx);
5033 err = err ?: visit(&a->index_type, ctx);
5034 return err;
5035 }
5036
5037 case BTF_KIND_STRUCT:
5038 case BTF_KIND_UNION: {
5039 struct btf_member *m = btf_members(t);
5040
5041 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5042 err = visit(&m->type, ctx);
5043 if (err)
5044 return err;
5045 }
5046 return 0;
5047 }
5048
5049 case BTF_KIND_FUNC_PROTO: {
5050 struct btf_param *m = btf_params(t);
5051
5052 err = visit(&t->type, ctx);
5053 if (err)
5054 return err;
5055 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5056 err = visit(&m->type, ctx);
5057 if (err)
5058 return err;
5059 }
5060 return 0;
5061 }
5062
5063 case BTF_KIND_DATASEC: {
5064 struct btf_var_secinfo *m = btf_var_secinfos(t);
5065
5066 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5067 err = visit(&m->type, ctx);
5068 if (err)
5069 return err;
5070 }
5071 return 0;
5072 }
5073
5074 default:
5075 return -EINVAL;
5076 }
5077}
5078
5079int btf_type_visit_str_offs(struct btf_type *t, str_off_visit_fn visit, void *ctx)
5080{
5081 int i, n, err;
5082
5083 err = visit(&t->name_off, ctx);
5084 if (err)
5085 return err;
5086
5087 switch (btf_kind(t)) {
5088 case BTF_KIND_STRUCT:
5089 case BTF_KIND_UNION: {
5090 struct btf_member *m = btf_members(t);
5091
5092 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5093 err = visit(&m->name_off, ctx);
5094 if (err)
5095 return err;
5096 }
5097 break;
5098 }
5099 case BTF_KIND_ENUM: {
5100 struct btf_enum *m = btf_enum(t);
5101
5102 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5103 err = visit(&m->name_off, ctx);
5104 if (err)
5105 return err;
5106 }
5107 break;
5108 }
5109 case BTF_KIND_ENUM64: {
5110 struct btf_enum64 *m = btf_enum64(t);
5111
5112 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5113 err = visit(&m->name_off, ctx);
5114 if (err)
5115 return err;
5116 }
5117 break;
5118 }
5119 case BTF_KIND_FUNC_PROTO: {
5120 struct btf_param *m = btf_params(t);
5121
5122 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5123 err = visit(&m->name_off, ctx);
5124 if (err)
5125 return err;
5126 }
5127 break;
5128 }
5129 default:
5130 break;
5131 }
5132
5133 return 0;
5134}
5135
5136int btf_ext_visit_type_ids(struct btf_ext *btf_ext, type_id_visit_fn visit, void *ctx)
5137{
5138 const struct btf_ext_info *seg;
5139 struct btf_ext_info_sec *sec;
5140 int i, err;
5141
5142 seg = &btf_ext->func_info;
5143 for_each_btf_ext_sec(seg, sec) {
5144 struct bpf_func_info_min *rec;
5145
5146 for_each_btf_ext_rec(seg, sec, i, rec) {
5147 err = visit(&rec->type_id, ctx);
5148 if (err < 0)
5149 return err;
5150 }
5151 }
5152
5153 seg = &btf_ext->core_relo_info;
5154 for_each_btf_ext_sec(seg, sec) {
5155 struct bpf_core_relo *rec;
5156
5157 for_each_btf_ext_rec(seg, sec, i, rec) {
5158 err = visit(&rec->type_id, ctx);
5159 if (err < 0)
5160 return err;
5161 }
5162 }
5163
5164 return 0;
5165}
5166
5167int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void *ctx)
5168{
5169 const struct btf_ext_info *seg;
5170 struct btf_ext_info_sec *sec;
5171 int i, err;
5172
5173 seg = &btf_ext->func_info;
5174 for_each_btf_ext_sec(seg, sec) {
5175 err = visit(&sec->sec_name_off, ctx);
5176 if (err)
5177 return err;
5178 }
5179
5180 seg = &btf_ext->line_info;
5181 for_each_btf_ext_sec(seg, sec) {
5182 struct bpf_line_info_min *rec;
5183
5184 err = visit(&sec->sec_name_off, ctx);
5185 if (err)
5186 return err;
5187
5188 for_each_btf_ext_rec(seg, sec, i, rec) {
5189 err = visit(&rec->file_name_off, ctx);
5190 if (err)
5191 return err;
5192 err = visit(&rec->line_off, ctx);
5193 if (err)
5194 return err;
5195 }
5196 }
5197
5198 seg = &btf_ext->core_relo_info;
5199 for_each_btf_ext_sec(seg, sec) {
5200 struct bpf_core_relo *rec;
5201
5202 err = visit(&sec->sec_name_off, ctx);
5203 if (err)
5204 return err;
5205
5206 for_each_btf_ext_rec(seg, sec, i, rec) {
5207 err = visit(&rec->access_str_off, ctx);
5208 if (err)
5209 return err;
5210 }
5211 }
5212
5213 return 0;
5214}