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