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1// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2/* Copyright (c) 2018 Facebook */
3
4#include <byteswap.h>
5#include <endian.h>
6#include <stdio.h>
7#include <stdlib.h>
8#include <string.h>
9#include <fcntl.h>
10#include <unistd.h>
11#include <errno.h>
12#include <sys/utsname.h>
13#include <sys/param.h>
14#include <sys/stat.h>
15#include <linux/kernel.h>
16#include <linux/err.h>
17#include <linux/btf.h>
18#include <gelf.h>
19#include "btf.h"
20#include "bpf.h"
21#include "libbpf.h"
22#include "libbpf_internal.h"
23#include "hashmap.h"
24#include "strset.h"
25
26#define BTF_MAX_NR_TYPES 0x7fffffffU
27#define BTF_MAX_STR_OFFSET 0x7fffffffU
28
29static struct btf_type btf_void;
30
31struct btf {
32 /* raw BTF data in native endianness */
33 void *raw_data;
34 /* raw BTF data in non-native endianness */
35 void *raw_data_swapped;
36 __u32 raw_size;
37 /* whether target endianness differs from the native one */
38 bool swapped_endian;
39
40 /*
41 * When BTF is loaded from an ELF or raw memory it is stored
42 * in a contiguous memory block. The hdr, type_data, and, strs_data
43 * point inside that memory region to their respective parts of BTF
44 * representation:
45 *
46 * +--------------------------------+
47 * | Header | Types | Strings |
48 * +--------------------------------+
49 * ^ ^ ^
50 * | | |
51 * hdr | |
52 * types_data-+ |
53 * strs_data------------+
54 *
55 * If BTF data is later modified, e.g., due to types added or
56 * removed, BTF deduplication performed, etc, this contiguous
57 * representation is broken up into three independently allocated
58 * memory regions to be able to modify them independently.
59 * raw_data is nulled out at that point, but can be later allocated
60 * and cached again if user calls btf__raw_data(), at which point
61 * raw_data will contain a contiguous copy of header, types, and
62 * strings:
63 *
64 * +----------+ +---------+ +-----------+
65 * | Header | | Types | | Strings |
66 * +----------+ +---------+ +-----------+
67 * ^ ^ ^
68 * | | |
69 * hdr | |
70 * types_data----+ |
71 * strset__data(strs_set)-----+
72 *
73 * +----------+---------+-----------+
74 * | Header | Types | Strings |
75 * raw_data----->+----------+---------+-----------+
76 */
77 struct btf_header *hdr;
78
79 void *types_data;
80 size_t types_data_cap; /* used size stored in hdr->type_len */
81
82 /* type ID to `struct btf_type *` lookup index
83 * type_offs[0] corresponds to the first non-VOID type:
84 * - for base BTF it's type [1];
85 * - for split BTF it's the first non-base BTF type.
86 */
87 __u32 *type_offs;
88 size_t type_offs_cap;
89 /* number of types in this BTF instance:
90 * - doesn't include special [0] void type;
91 * - for split BTF counts number of types added on top of base BTF.
92 */
93 __u32 nr_types;
94 /* if not NULL, points to the base BTF on top of which the current
95 * split BTF is based
96 */
97 struct btf *base_btf;
98 /* BTF type ID of the first type in this BTF instance:
99 * - for base BTF it's equal to 1;
100 * - for split BTF it's equal to biggest type ID of base BTF plus 1.
101 */
102 int start_id;
103 /* logical string offset of this BTF instance:
104 * - for base BTF it's equal to 0;
105 * - for split BTF it's equal to total size of base BTF's string section size.
106 */
107 int start_str_off;
108
109 /* only one of strs_data or strs_set can be non-NULL, depending on
110 * whether BTF is in a modifiable state (strs_set is used) or not
111 * (strs_data points inside raw_data)
112 */
113 void *strs_data;
114 /* a set of unique strings */
115 struct strset *strs_set;
116 /* whether strings are already deduplicated */
117 bool strs_deduped;
118
119 /* BTF object FD, if loaded into kernel */
120 int fd;
121
122 /* Pointer size (in bytes) for a target architecture of this BTF */
123 int ptr_sz;
124};
125
126static inline __u64 ptr_to_u64(const void *ptr)
127{
128 return (__u64) (unsigned long) ptr;
129}
130
131/* Ensure given dynamically allocated memory region pointed to by *data* with
132 * capacity of *cap_cnt* elements each taking *elem_sz* bytes has enough
133 * memory to accommodate *add_cnt* new elements, assuming *cur_cnt* elements
134 * are already used. At most *max_cnt* elements can be ever allocated.
135 * If necessary, memory is reallocated and all existing data is copied over,
136 * new pointer to the memory region is stored at *data, new memory region
137 * capacity (in number of elements) is stored in *cap.
138 * On success, memory pointer to the beginning of unused memory is returned.
139 * On error, NULL is returned.
140 */
141void *libbpf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
142 size_t cur_cnt, size_t max_cnt, size_t add_cnt)
143{
144 size_t new_cnt;
145 void *new_data;
146
147 if (cur_cnt + add_cnt <= *cap_cnt)
148 return *data + cur_cnt * elem_sz;
149
150 /* requested more than the set limit */
151 if (cur_cnt + add_cnt > max_cnt)
152 return NULL;
153
154 new_cnt = *cap_cnt;
155 new_cnt += new_cnt / 4; /* expand by 25% */
156 if (new_cnt < 16) /* but at least 16 elements */
157 new_cnt = 16;
158 if (new_cnt > max_cnt) /* but not exceeding a set limit */
159 new_cnt = max_cnt;
160 if (new_cnt < cur_cnt + add_cnt) /* also ensure we have enough memory */
161 new_cnt = cur_cnt + add_cnt;
162
163 new_data = libbpf_reallocarray(*data, new_cnt, elem_sz);
164 if (!new_data)
165 return NULL;
166
167 /* zero out newly allocated portion of memory */
168 memset(new_data + (*cap_cnt) * elem_sz, 0, (new_cnt - *cap_cnt) * elem_sz);
169
170 *data = new_data;
171 *cap_cnt = new_cnt;
172 return new_data + cur_cnt * elem_sz;
173}
174
175/* Ensure given dynamically allocated memory region has enough allocated space
176 * to accommodate *need_cnt* elements of size *elem_sz* bytes each
177 */
178int libbpf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt)
179{
180 void *p;
181
182 if (need_cnt <= *cap_cnt)
183 return 0;
184
185 p = libbpf_add_mem(data, cap_cnt, elem_sz, *cap_cnt, SIZE_MAX, need_cnt - *cap_cnt);
186 if (!p)
187 return -ENOMEM;
188
189 return 0;
190}
191
192static void *btf_add_type_offs_mem(struct btf *btf, size_t add_cnt)
193{
194 return libbpf_add_mem((void **)&btf->type_offs, &btf->type_offs_cap, sizeof(__u32),
195 btf->nr_types, BTF_MAX_NR_TYPES, add_cnt);
196}
197
198static int btf_add_type_idx_entry(struct btf *btf, __u32 type_off)
199{
200 __u32 *p;
201
202 p = btf_add_type_offs_mem(btf, 1);
203 if (!p)
204 return -ENOMEM;
205
206 *p = type_off;
207 return 0;
208}
209
210static void btf_bswap_hdr(struct btf_header *h)
211{
212 h->magic = bswap_16(h->magic);
213 h->hdr_len = bswap_32(h->hdr_len);
214 h->type_off = bswap_32(h->type_off);
215 h->type_len = bswap_32(h->type_len);
216 h->str_off = bswap_32(h->str_off);
217 h->str_len = bswap_32(h->str_len);
218}
219
220static int btf_parse_hdr(struct btf *btf)
221{
222 struct btf_header *hdr = btf->hdr;
223 __u32 meta_left;
224
225 if (btf->raw_size < sizeof(struct btf_header)) {
226 pr_debug("BTF header not found\n");
227 return -EINVAL;
228 }
229
230 if (hdr->magic == bswap_16(BTF_MAGIC)) {
231 btf->swapped_endian = true;
232 if (bswap_32(hdr->hdr_len) != sizeof(struct btf_header)) {
233 pr_warn("Can't load BTF with non-native endianness due to unsupported header length %u\n",
234 bswap_32(hdr->hdr_len));
235 return -ENOTSUP;
236 }
237 btf_bswap_hdr(hdr);
238 } else if (hdr->magic != BTF_MAGIC) {
239 pr_debug("Invalid BTF magic: %x\n", hdr->magic);
240 return -EINVAL;
241 }
242
243 if (btf->raw_size < hdr->hdr_len) {
244 pr_debug("BTF header len %u larger than data size %u\n",
245 hdr->hdr_len, btf->raw_size);
246 return -EINVAL;
247 }
248
249 meta_left = btf->raw_size - hdr->hdr_len;
250 if (meta_left < (long long)hdr->str_off + hdr->str_len) {
251 pr_debug("Invalid BTF total size: %u\n", btf->raw_size);
252 return -EINVAL;
253 }
254
255 if ((long long)hdr->type_off + hdr->type_len > hdr->str_off) {
256 pr_debug("Invalid BTF data sections layout: type data at %u + %u, strings data at %u + %u\n",
257 hdr->type_off, hdr->type_len, hdr->str_off, hdr->str_len);
258 return -EINVAL;
259 }
260
261 if (hdr->type_off % 4) {
262 pr_debug("BTF type section is not aligned to 4 bytes\n");
263 return -EINVAL;
264 }
265
266 return 0;
267}
268
269static int btf_parse_str_sec(struct btf *btf)
270{
271 const struct btf_header *hdr = btf->hdr;
272 const char *start = btf->strs_data;
273 const char *end = start + btf->hdr->str_len;
274
275 if (btf->base_btf && hdr->str_len == 0)
276 return 0;
277 if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_STR_OFFSET || end[-1]) {
278 pr_debug("Invalid BTF string section\n");
279 return -EINVAL;
280 }
281 if (!btf->base_btf && start[0]) {
282 pr_debug("Invalid BTF string section\n");
283 return -EINVAL;
284 }
285 return 0;
286}
287
288static int btf_type_size(const struct btf_type *t)
289{
290 const int base_size = sizeof(struct btf_type);
291 __u16 vlen = btf_vlen(t);
292
293 switch (btf_kind(t)) {
294 case BTF_KIND_FWD:
295 case BTF_KIND_CONST:
296 case BTF_KIND_VOLATILE:
297 case BTF_KIND_RESTRICT:
298 case BTF_KIND_PTR:
299 case BTF_KIND_TYPEDEF:
300 case BTF_KIND_FUNC:
301 case BTF_KIND_FLOAT:
302 case BTF_KIND_TYPE_TAG:
303 return base_size;
304 case BTF_KIND_INT:
305 return base_size + sizeof(__u32);
306 case BTF_KIND_ENUM:
307 return base_size + vlen * sizeof(struct btf_enum);
308 case BTF_KIND_ENUM64:
309 return base_size + vlen * sizeof(struct btf_enum64);
310 case BTF_KIND_ARRAY:
311 return base_size + sizeof(struct btf_array);
312 case BTF_KIND_STRUCT:
313 case BTF_KIND_UNION:
314 return base_size + vlen * sizeof(struct btf_member);
315 case BTF_KIND_FUNC_PROTO:
316 return base_size + vlen * sizeof(struct btf_param);
317 case BTF_KIND_VAR:
318 return base_size + sizeof(struct btf_var);
319 case BTF_KIND_DATASEC:
320 return base_size + vlen * sizeof(struct btf_var_secinfo);
321 case BTF_KIND_DECL_TAG:
322 return base_size + sizeof(struct btf_decl_tag);
323 default:
324 pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
325 return -EINVAL;
326 }
327}
328
329static void btf_bswap_type_base(struct btf_type *t)
330{
331 t->name_off = bswap_32(t->name_off);
332 t->info = bswap_32(t->info);
333 t->type = bswap_32(t->type);
334}
335
336static int btf_bswap_type_rest(struct btf_type *t)
337{
338 struct btf_var_secinfo *v;
339 struct btf_enum64 *e64;
340 struct btf_member *m;
341 struct btf_array *a;
342 struct btf_param *p;
343 struct btf_enum *e;
344 __u16 vlen = btf_vlen(t);
345 int i;
346
347 switch (btf_kind(t)) {
348 case BTF_KIND_FWD:
349 case BTF_KIND_CONST:
350 case BTF_KIND_VOLATILE:
351 case BTF_KIND_RESTRICT:
352 case BTF_KIND_PTR:
353 case BTF_KIND_TYPEDEF:
354 case BTF_KIND_FUNC:
355 case BTF_KIND_FLOAT:
356 case BTF_KIND_TYPE_TAG:
357 return 0;
358 case BTF_KIND_INT:
359 *(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
360 return 0;
361 case BTF_KIND_ENUM:
362 for (i = 0, e = btf_enum(t); i < vlen; i++, e++) {
363 e->name_off = bswap_32(e->name_off);
364 e->val = bswap_32(e->val);
365 }
366 return 0;
367 case BTF_KIND_ENUM64:
368 for (i = 0, e64 = btf_enum64(t); i < vlen; i++, e64++) {
369 e64->name_off = bswap_32(e64->name_off);
370 e64->val_lo32 = bswap_32(e64->val_lo32);
371 e64->val_hi32 = bswap_32(e64->val_hi32);
372 }
373 return 0;
374 case BTF_KIND_ARRAY:
375 a = btf_array(t);
376 a->type = bswap_32(a->type);
377 a->index_type = bswap_32(a->index_type);
378 a->nelems = bswap_32(a->nelems);
379 return 0;
380 case BTF_KIND_STRUCT:
381 case BTF_KIND_UNION:
382 for (i = 0, m = btf_members(t); i < vlen; i++, m++) {
383 m->name_off = bswap_32(m->name_off);
384 m->type = bswap_32(m->type);
385 m->offset = bswap_32(m->offset);
386 }
387 return 0;
388 case BTF_KIND_FUNC_PROTO:
389 for (i = 0, p = btf_params(t); i < vlen; i++, p++) {
390 p->name_off = bswap_32(p->name_off);
391 p->type = bswap_32(p->type);
392 }
393 return 0;
394 case BTF_KIND_VAR:
395 btf_var(t)->linkage = bswap_32(btf_var(t)->linkage);
396 return 0;
397 case BTF_KIND_DATASEC:
398 for (i = 0, v = btf_var_secinfos(t); i < vlen; i++, v++) {
399 v->type = bswap_32(v->type);
400 v->offset = bswap_32(v->offset);
401 v->size = bswap_32(v->size);
402 }
403 return 0;
404 case BTF_KIND_DECL_TAG:
405 btf_decl_tag(t)->component_idx = bswap_32(btf_decl_tag(t)->component_idx);
406 return 0;
407 default:
408 pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
409 return -EINVAL;
410 }
411}
412
413static int btf_parse_type_sec(struct btf *btf)
414{
415 struct btf_header *hdr = btf->hdr;
416 void *next_type = btf->types_data;
417 void *end_type = next_type + hdr->type_len;
418 int err, type_size;
419
420 while (next_type + sizeof(struct btf_type) <= end_type) {
421 if (btf->swapped_endian)
422 btf_bswap_type_base(next_type);
423
424 type_size = btf_type_size(next_type);
425 if (type_size < 0)
426 return type_size;
427 if (next_type + type_size > end_type) {
428 pr_warn("BTF type [%d] is malformed\n", btf->start_id + btf->nr_types);
429 return -EINVAL;
430 }
431
432 if (btf->swapped_endian && btf_bswap_type_rest(next_type))
433 return -EINVAL;
434
435 err = btf_add_type_idx_entry(btf, next_type - btf->types_data);
436 if (err)
437 return err;
438
439 next_type += type_size;
440 btf->nr_types++;
441 }
442
443 if (next_type != end_type) {
444 pr_warn("BTF types data is malformed\n");
445 return -EINVAL;
446 }
447
448 return 0;
449}
450
451static int btf_validate_str(const struct btf *btf, __u32 str_off, const char *what, __u32 type_id)
452{
453 const char *s;
454
455 s = btf__str_by_offset(btf, str_off);
456 if (!s) {
457 pr_warn("btf: type [%u]: invalid %s (string offset %u)\n", type_id, what, str_off);
458 return -EINVAL;
459 }
460
461 return 0;
462}
463
464static int btf_validate_id(const struct btf *btf, __u32 id, __u32 ctx_id)
465{
466 const struct btf_type *t;
467
468 t = btf__type_by_id(btf, id);
469 if (!t) {
470 pr_warn("btf: type [%u]: invalid referenced type ID %u\n", ctx_id, id);
471 return -EINVAL;
472 }
473
474 return 0;
475}
476
477static int btf_validate_type(const struct btf *btf, const struct btf_type *t, __u32 id)
478{
479 __u32 kind = btf_kind(t);
480 int err, i, n;
481
482 err = btf_validate_str(btf, t->name_off, "type name", id);
483 if (err)
484 return err;
485
486 switch (kind) {
487 case BTF_KIND_UNKN:
488 case BTF_KIND_INT:
489 case BTF_KIND_FWD:
490 case BTF_KIND_FLOAT:
491 break;
492 case BTF_KIND_PTR:
493 case BTF_KIND_TYPEDEF:
494 case BTF_KIND_VOLATILE:
495 case BTF_KIND_CONST:
496 case BTF_KIND_RESTRICT:
497 case BTF_KIND_VAR:
498 case BTF_KIND_DECL_TAG:
499 case BTF_KIND_TYPE_TAG:
500 err = btf_validate_id(btf, t->type, id);
501 if (err)
502 return err;
503 break;
504 case BTF_KIND_ARRAY: {
505 const struct btf_array *a = btf_array(t);
506
507 err = btf_validate_id(btf, a->type, id);
508 err = err ?: btf_validate_id(btf, a->index_type, id);
509 if (err)
510 return err;
511 break;
512 }
513 case BTF_KIND_STRUCT:
514 case BTF_KIND_UNION: {
515 const struct btf_member *m = btf_members(t);
516
517 n = btf_vlen(t);
518 for (i = 0; i < n; i++, m++) {
519 err = btf_validate_str(btf, m->name_off, "field name", id);
520 err = err ?: btf_validate_id(btf, m->type, id);
521 if (err)
522 return err;
523 }
524 break;
525 }
526 case BTF_KIND_ENUM: {
527 const struct btf_enum *m = btf_enum(t);
528
529 n = btf_vlen(t);
530 for (i = 0; i < n; i++, m++) {
531 err = btf_validate_str(btf, m->name_off, "enum name", id);
532 if (err)
533 return err;
534 }
535 break;
536 }
537 case BTF_KIND_ENUM64: {
538 const struct btf_enum64 *m = btf_enum64(t);
539
540 n = btf_vlen(t);
541 for (i = 0; i < n; i++, m++) {
542 err = btf_validate_str(btf, m->name_off, "enum name", id);
543 if (err)
544 return err;
545 }
546 break;
547 }
548 case BTF_KIND_FUNC: {
549 const struct btf_type *ft;
550
551 err = btf_validate_id(btf, t->type, id);
552 if (err)
553 return err;
554 ft = btf__type_by_id(btf, t->type);
555 if (btf_kind(ft) != BTF_KIND_FUNC_PROTO) {
556 pr_warn("btf: type [%u]: referenced type [%u] is not FUNC_PROTO\n", id, t->type);
557 return -EINVAL;
558 }
559 break;
560 }
561 case BTF_KIND_FUNC_PROTO: {
562 const struct btf_param *m = btf_params(t);
563
564 n = btf_vlen(t);
565 for (i = 0; i < n; i++, m++) {
566 err = btf_validate_str(btf, m->name_off, "param name", id);
567 err = err ?: btf_validate_id(btf, m->type, id);
568 if (err)
569 return err;
570 }
571 break;
572 }
573 case BTF_KIND_DATASEC: {
574 const struct btf_var_secinfo *m = btf_var_secinfos(t);
575
576 n = btf_vlen(t);
577 for (i = 0; i < n; i++, m++) {
578 err = btf_validate_id(btf, m->type, id);
579 if (err)
580 return err;
581 }
582 break;
583 }
584 default:
585 pr_warn("btf: type [%u]: unrecognized kind %u\n", id, kind);
586 return -EINVAL;
587 }
588 return 0;
589}
590
591/* Validate basic sanity of BTF. It's intentionally less thorough than
592 * kernel's validation and validates only properties of BTF that libbpf relies
593 * on to be correct (e.g., valid type IDs, valid string offsets, etc)
594 */
595static int btf_sanity_check(const struct btf *btf)
596{
597 const struct btf_type *t;
598 __u32 i, n = btf__type_cnt(btf);
599 int err;
600
601 for (i = 1; i < n; i++) {
602 t = btf_type_by_id(btf, i);
603 err = btf_validate_type(btf, t, i);
604 if (err)
605 return err;
606 }
607 return 0;
608}
609
610__u32 btf__type_cnt(const struct btf *btf)
611{
612 return btf->start_id + btf->nr_types;
613}
614
615const struct btf *btf__base_btf(const struct btf *btf)
616{
617 return btf->base_btf;
618}
619
620/* internal helper returning non-const pointer to a type */
621struct btf_type *btf_type_by_id(const struct btf *btf, __u32 type_id)
622{
623 if (type_id == 0)
624 return &btf_void;
625 if (type_id < btf->start_id)
626 return btf_type_by_id(btf->base_btf, type_id);
627 return btf->types_data + btf->type_offs[type_id - btf->start_id];
628}
629
630const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
631{
632 if (type_id >= btf->start_id + btf->nr_types)
633 return errno = EINVAL, NULL;
634 return btf_type_by_id((struct btf *)btf, type_id);
635}
636
637static int determine_ptr_size(const struct btf *btf)
638{
639 static const char * const long_aliases[] = {
640 "long",
641 "long int",
642 "int long",
643 "unsigned long",
644 "long unsigned",
645 "unsigned long int",
646 "unsigned int long",
647 "long unsigned int",
648 "long int unsigned",
649 "int unsigned long",
650 "int long unsigned",
651 };
652 const struct btf_type *t;
653 const char *name;
654 int i, j, n;
655
656 if (btf->base_btf && btf->base_btf->ptr_sz > 0)
657 return btf->base_btf->ptr_sz;
658
659 n = btf__type_cnt(btf);
660 for (i = 1; i < n; i++) {
661 t = btf__type_by_id(btf, i);
662 if (!btf_is_int(t))
663 continue;
664
665 if (t->size != 4 && t->size != 8)
666 continue;
667
668 name = btf__name_by_offset(btf, t->name_off);
669 if (!name)
670 continue;
671
672 for (j = 0; j < ARRAY_SIZE(long_aliases); j++) {
673 if (strcmp(name, long_aliases[j]) == 0)
674 return t->size;
675 }
676 }
677
678 return -1;
679}
680
681static size_t btf_ptr_sz(const struct btf *btf)
682{
683 if (!btf->ptr_sz)
684 ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
685 return btf->ptr_sz < 0 ? sizeof(void *) : btf->ptr_sz;
686}
687
688/* Return pointer size this BTF instance assumes. The size is heuristically
689 * determined by looking for 'long' or 'unsigned long' integer type and
690 * recording its size in bytes. If BTF type information doesn't have any such
691 * type, this function returns 0. In the latter case, native architecture's
692 * pointer size is assumed, so will be either 4 or 8, depending on
693 * architecture that libbpf was compiled for. It's possible to override
694 * guessed value by using btf__set_pointer_size() API.
695 */
696size_t btf__pointer_size(const struct btf *btf)
697{
698 if (!btf->ptr_sz)
699 ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
700
701 if (btf->ptr_sz < 0)
702 /* not enough BTF type info to guess */
703 return 0;
704
705 return btf->ptr_sz;
706}
707
708/* Override or set pointer size in bytes. Only values of 4 and 8 are
709 * supported.
710 */
711int btf__set_pointer_size(struct btf *btf, size_t ptr_sz)
712{
713 if (ptr_sz != 4 && ptr_sz != 8)
714 return libbpf_err(-EINVAL);
715 btf->ptr_sz = ptr_sz;
716 return 0;
717}
718
719static bool is_host_big_endian(void)
720{
721#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
722 return false;
723#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
724 return true;
725#else
726# error "Unrecognized __BYTE_ORDER__"
727#endif
728}
729
730enum btf_endianness btf__endianness(const struct btf *btf)
731{
732 if (is_host_big_endian())
733 return btf->swapped_endian ? BTF_LITTLE_ENDIAN : BTF_BIG_ENDIAN;
734 else
735 return btf->swapped_endian ? BTF_BIG_ENDIAN : BTF_LITTLE_ENDIAN;
736}
737
738int btf__set_endianness(struct btf *btf, enum btf_endianness endian)
739{
740 if (endian != BTF_LITTLE_ENDIAN && endian != BTF_BIG_ENDIAN)
741 return libbpf_err(-EINVAL);
742
743 btf->swapped_endian = is_host_big_endian() != (endian == BTF_BIG_ENDIAN);
744 if (!btf->swapped_endian) {
745 free(btf->raw_data_swapped);
746 btf->raw_data_swapped = NULL;
747 }
748 return 0;
749}
750
751static bool btf_type_is_void(const struct btf_type *t)
752{
753 return t == &btf_void || btf_is_fwd(t);
754}
755
756static bool btf_type_is_void_or_null(const struct btf_type *t)
757{
758 return !t || btf_type_is_void(t);
759}
760
761#define MAX_RESOLVE_DEPTH 32
762
763__s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
764{
765 const struct btf_array *array;
766 const struct btf_type *t;
767 __u32 nelems = 1;
768 __s64 size = -1;
769 int i;
770
771 t = btf__type_by_id(btf, type_id);
772 for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t); i++) {
773 switch (btf_kind(t)) {
774 case BTF_KIND_INT:
775 case BTF_KIND_STRUCT:
776 case BTF_KIND_UNION:
777 case BTF_KIND_ENUM:
778 case BTF_KIND_ENUM64:
779 case BTF_KIND_DATASEC:
780 case BTF_KIND_FLOAT:
781 size = t->size;
782 goto done;
783 case BTF_KIND_PTR:
784 size = btf_ptr_sz(btf);
785 goto done;
786 case BTF_KIND_TYPEDEF:
787 case BTF_KIND_VOLATILE:
788 case BTF_KIND_CONST:
789 case BTF_KIND_RESTRICT:
790 case BTF_KIND_VAR:
791 case BTF_KIND_DECL_TAG:
792 case BTF_KIND_TYPE_TAG:
793 type_id = t->type;
794 break;
795 case BTF_KIND_ARRAY:
796 array = btf_array(t);
797 if (nelems && array->nelems > UINT32_MAX / nelems)
798 return libbpf_err(-E2BIG);
799 nelems *= array->nelems;
800 type_id = array->type;
801 break;
802 default:
803 return libbpf_err(-EINVAL);
804 }
805
806 t = btf__type_by_id(btf, type_id);
807 }
808
809done:
810 if (size < 0)
811 return libbpf_err(-EINVAL);
812 if (nelems && size > UINT32_MAX / nelems)
813 return libbpf_err(-E2BIG);
814
815 return nelems * size;
816}
817
818int btf__align_of(const struct btf *btf, __u32 id)
819{
820 const struct btf_type *t = btf__type_by_id(btf, id);
821 __u16 kind = btf_kind(t);
822
823 switch (kind) {
824 case BTF_KIND_INT:
825 case BTF_KIND_ENUM:
826 case BTF_KIND_ENUM64:
827 case BTF_KIND_FLOAT:
828 return min(btf_ptr_sz(btf), (size_t)t->size);
829 case BTF_KIND_PTR:
830 return btf_ptr_sz(btf);
831 case BTF_KIND_TYPEDEF:
832 case BTF_KIND_VOLATILE:
833 case BTF_KIND_CONST:
834 case BTF_KIND_RESTRICT:
835 case BTF_KIND_TYPE_TAG:
836 return btf__align_of(btf, t->type);
837 case BTF_KIND_ARRAY:
838 return btf__align_of(btf, btf_array(t)->type);
839 case BTF_KIND_STRUCT:
840 case BTF_KIND_UNION: {
841 const struct btf_member *m = btf_members(t);
842 __u16 vlen = btf_vlen(t);
843 int i, max_align = 1, align;
844
845 for (i = 0; i < vlen; i++, m++) {
846 align = btf__align_of(btf, m->type);
847 if (align <= 0)
848 return libbpf_err(align);
849 max_align = max(max_align, align);
850
851 /* if field offset isn't aligned according to field
852 * type's alignment, then struct must be packed
853 */
854 if (btf_member_bitfield_size(t, i) == 0 &&
855 (m->offset % (8 * align)) != 0)
856 return 1;
857 }
858
859 /* if struct/union size isn't a multiple of its alignment,
860 * then struct must be packed
861 */
862 if ((t->size % max_align) != 0)
863 return 1;
864
865 return max_align;
866 }
867 default:
868 pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
869 return errno = EINVAL, 0;
870 }
871}
872
873int btf__resolve_type(const struct btf *btf, __u32 type_id)
874{
875 const struct btf_type *t;
876 int depth = 0;
877
878 t = btf__type_by_id(btf, type_id);
879 while (depth < MAX_RESOLVE_DEPTH &&
880 !btf_type_is_void_or_null(t) &&
881 (btf_is_mod(t) || btf_is_typedef(t) || btf_is_var(t))) {
882 type_id = t->type;
883 t = btf__type_by_id(btf, type_id);
884 depth++;
885 }
886
887 if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
888 return libbpf_err(-EINVAL);
889
890 return type_id;
891}
892
893__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
894{
895 __u32 i, nr_types = btf__type_cnt(btf);
896
897 if (!strcmp(type_name, "void"))
898 return 0;
899
900 for (i = 1; i < nr_types; i++) {
901 const struct btf_type *t = btf__type_by_id(btf, i);
902 const char *name = btf__name_by_offset(btf, t->name_off);
903
904 if (name && !strcmp(type_name, name))
905 return i;
906 }
907
908 return libbpf_err(-ENOENT);
909}
910
911static __s32 btf_find_by_name_kind(const struct btf *btf, int start_id,
912 const char *type_name, __u32 kind)
913{
914 __u32 i, nr_types = btf__type_cnt(btf);
915
916 if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void"))
917 return 0;
918
919 for (i = start_id; i < nr_types; i++) {
920 const struct btf_type *t = btf__type_by_id(btf, i);
921 const char *name;
922
923 if (btf_kind(t) != kind)
924 continue;
925 name = btf__name_by_offset(btf, t->name_off);
926 if (name && !strcmp(type_name, name))
927 return i;
928 }
929
930 return libbpf_err(-ENOENT);
931}
932
933__s32 btf__find_by_name_kind_own(const struct btf *btf, const char *type_name,
934 __u32 kind)
935{
936 return btf_find_by_name_kind(btf, btf->start_id, type_name, kind);
937}
938
939__s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
940 __u32 kind)
941{
942 return btf_find_by_name_kind(btf, 1, type_name, kind);
943}
944
945static bool btf_is_modifiable(const struct btf *btf)
946{
947 return (void *)btf->hdr != btf->raw_data;
948}
949
950void btf__free(struct btf *btf)
951{
952 if (IS_ERR_OR_NULL(btf))
953 return;
954
955 if (btf->fd >= 0)
956 close(btf->fd);
957
958 if (btf_is_modifiable(btf)) {
959 /* if BTF was modified after loading, it will have a split
960 * in-memory representation for header, types, and strings
961 * sections, so we need to free all of them individually. It
962 * might still have a cached contiguous raw data present,
963 * which will be unconditionally freed below.
964 */
965 free(btf->hdr);
966 free(btf->types_data);
967 strset__free(btf->strs_set);
968 }
969 free(btf->raw_data);
970 free(btf->raw_data_swapped);
971 free(btf->type_offs);
972 free(btf);
973}
974
975static struct btf *btf_new_empty(struct btf *base_btf)
976{
977 struct btf *btf;
978
979 btf = calloc(1, sizeof(*btf));
980 if (!btf)
981 return ERR_PTR(-ENOMEM);
982
983 btf->nr_types = 0;
984 btf->start_id = 1;
985 btf->start_str_off = 0;
986 btf->fd = -1;
987 btf->ptr_sz = sizeof(void *);
988 btf->swapped_endian = false;
989
990 if (base_btf) {
991 btf->base_btf = base_btf;
992 btf->start_id = btf__type_cnt(base_btf);
993 btf->start_str_off = base_btf->hdr->str_len;
994 }
995
996 /* +1 for empty string at offset 0 */
997 btf->raw_size = sizeof(struct btf_header) + (base_btf ? 0 : 1);
998 btf->raw_data = calloc(1, btf->raw_size);
999 if (!btf->raw_data) {
1000 free(btf);
1001 return ERR_PTR(-ENOMEM);
1002 }
1003
1004 btf->hdr = btf->raw_data;
1005 btf->hdr->hdr_len = sizeof(struct btf_header);
1006 btf->hdr->magic = BTF_MAGIC;
1007 btf->hdr->version = BTF_VERSION;
1008
1009 btf->types_data = btf->raw_data + btf->hdr->hdr_len;
1010 btf->strs_data = btf->raw_data + btf->hdr->hdr_len;
1011 btf->hdr->str_len = base_btf ? 0 : 1; /* empty string at offset 0 */
1012
1013 return btf;
1014}
1015
1016struct btf *btf__new_empty(void)
1017{
1018 return libbpf_ptr(btf_new_empty(NULL));
1019}
1020
1021struct btf *btf__new_empty_split(struct btf *base_btf)
1022{
1023 return libbpf_ptr(btf_new_empty(base_btf));
1024}
1025
1026static struct btf *btf_new(const void *data, __u32 size, struct btf *base_btf)
1027{
1028 struct btf *btf;
1029 int err;
1030
1031 btf = calloc(1, sizeof(struct btf));
1032 if (!btf)
1033 return ERR_PTR(-ENOMEM);
1034
1035 btf->nr_types = 0;
1036 btf->start_id = 1;
1037 btf->start_str_off = 0;
1038 btf->fd = -1;
1039
1040 if (base_btf) {
1041 btf->base_btf = base_btf;
1042 btf->start_id = btf__type_cnt(base_btf);
1043 btf->start_str_off = base_btf->hdr->str_len;
1044 }
1045
1046 btf->raw_data = malloc(size);
1047 if (!btf->raw_data) {
1048 err = -ENOMEM;
1049 goto done;
1050 }
1051 memcpy(btf->raw_data, data, size);
1052 btf->raw_size = size;
1053
1054 btf->hdr = btf->raw_data;
1055 err = btf_parse_hdr(btf);
1056 if (err)
1057 goto done;
1058
1059 btf->strs_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->str_off;
1060 btf->types_data = btf->raw_data + btf->hdr->hdr_len + btf->hdr->type_off;
1061
1062 err = btf_parse_str_sec(btf);
1063 err = err ?: btf_parse_type_sec(btf);
1064 err = err ?: btf_sanity_check(btf);
1065 if (err)
1066 goto done;
1067
1068done:
1069 if (err) {
1070 btf__free(btf);
1071 return ERR_PTR(err);
1072 }
1073
1074 return btf;
1075}
1076
1077struct btf *btf__new(const void *data, __u32 size)
1078{
1079 return libbpf_ptr(btf_new(data, size, NULL));
1080}
1081
1082static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
1083 struct btf_ext **btf_ext)
1084{
1085 Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
1086 int err = 0, fd = -1, idx = 0;
1087 struct btf *btf = NULL;
1088 Elf_Scn *scn = NULL;
1089 Elf *elf = NULL;
1090 GElf_Ehdr ehdr;
1091 size_t shstrndx;
1092
1093 if (elf_version(EV_CURRENT) == EV_NONE) {
1094 pr_warn("failed to init libelf for %s\n", path);
1095 return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
1096 }
1097
1098 fd = open(path, O_RDONLY | O_CLOEXEC);
1099 if (fd < 0) {
1100 err = -errno;
1101 pr_warn("failed to open %s: %s\n", path, strerror(errno));
1102 return ERR_PTR(err);
1103 }
1104
1105 err = -LIBBPF_ERRNO__FORMAT;
1106
1107 elf = elf_begin(fd, ELF_C_READ, NULL);
1108 if (!elf) {
1109 pr_warn("failed to open %s as ELF file\n", path);
1110 goto done;
1111 }
1112 if (!gelf_getehdr(elf, &ehdr)) {
1113 pr_warn("failed to get EHDR from %s\n", path);
1114 goto done;
1115 }
1116
1117 if (elf_getshdrstrndx(elf, &shstrndx)) {
1118 pr_warn("failed to get section names section index for %s\n",
1119 path);
1120 goto done;
1121 }
1122
1123 if (!elf_rawdata(elf_getscn(elf, shstrndx), NULL)) {
1124 pr_warn("failed to get e_shstrndx from %s\n", path);
1125 goto done;
1126 }
1127
1128 while ((scn = elf_nextscn(elf, scn)) != NULL) {
1129 GElf_Shdr sh;
1130 char *name;
1131
1132 idx++;
1133 if (gelf_getshdr(scn, &sh) != &sh) {
1134 pr_warn("failed to get section(%d) header from %s\n",
1135 idx, path);
1136 goto done;
1137 }
1138 name = elf_strptr(elf, shstrndx, sh.sh_name);
1139 if (!name) {
1140 pr_warn("failed to get section(%d) name from %s\n",
1141 idx, path);
1142 goto done;
1143 }
1144 if (strcmp(name, BTF_ELF_SEC) == 0) {
1145 btf_data = elf_getdata(scn, 0);
1146 if (!btf_data) {
1147 pr_warn("failed to get section(%d, %s) data from %s\n",
1148 idx, name, path);
1149 goto done;
1150 }
1151 continue;
1152 } else if (btf_ext && strcmp(name, BTF_EXT_ELF_SEC) == 0) {
1153 btf_ext_data = elf_getdata(scn, 0);
1154 if (!btf_ext_data) {
1155 pr_warn("failed to get section(%d, %s) data from %s\n",
1156 idx, name, path);
1157 goto done;
1158 }
1159 continue;
1160 }
1161 }
1162
1163 if (!btf_data) {
1164 pr_warn("failed to find '%s' ELF section in %s\n", BTF_ELF_SEC, path);
1165 err = -ENODATA;
1166 goto done;
1167 }
1168 btf = btf_new(btf_data->d_buf, btf_data->d_size, base_btf);
1169 err = libbpf_get_error(btf);
1170 if (err)
1171 goto done;
1172
1173 switch (gelf_getclass(elf)) {
1174 case ELFCLASS32:
1175 btf__set_pointer_size(btf, 4);
1176 break;
1177 case ELFCLASS64:
1178 btf__set_pointer_size(btf, 8);
1179 break;
1180 default:
1181 pr_warn("failed to get ELF class (bitness) for %s\n", path);
1182 break;
1183 }
1184
1185 if (btf_ext && btf_ext_data) {
1186 *btf_ext = btf_ext__new(btf_ext_data->d_buf, btf_ext_data->d_size);
1187 err = libbpf_get_error(*btf_ext);
1188 if (err)
1189 goto done;
1190 } else if (btf_ext) {
1191 *btf_ext = NULL;
1192 }
1193done:
1194 if (elf)
1195 elf_end(elf);
1196 close(fd);
1197
1198 if (!err)
1199 return btf;
1200
1201 if (btf_ext)
1202 btf_ext__free(*btf_ext);
1203 btf__free(btf);
1204
1205 return ERR_PTR(err);
1206}
1207
1208struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
1209{
1210 return libbpf_ptr(btf_parse_elf(path, NULL, btf_ext));
1211}
1212
1213struct btf *btf__parse_elf_split(const char *path, struct btf *base_btf)
1214{
1215 return libbpf_ptr(btf_parse_elf(path, base_btf, NULL));
1216}
1217
1218static struct btf *btf_parse_raw(const char *path, struct btf *base_btf)
1219{
1220 struct btf *btf = NULL;
1221 void *data = NULL;
1222 FILE *f = NULL;
1223 __u16 magic;
1224 int err = 0;
1225 long sz;
1226
1227 f = fopen(path, "rbe");
1228 if (!f) {
1229 err = -errno;
1230 goto err_out;
1231 }
1232
1233 /* check BTF magic */
1234 if (fread(&magic, 1, sizeof(magic), f) < sizeof(magic)) {
1235 err = -EIO;
1236 goto err_out;
1237 }
1238 if (magic != BTF_MAGIC && magic != bswap_16(BTF_MAGIC)) {
1239 /* definitely not a raw BTF */
1240 err = -EPROTO;
1241 goto err_out;
1242 }
1243
1244 /* get file size */
1245 if (fseek(f, 0, SEEK_END)) {
1246 err = -errno;
1247 goto err_out;
1248 }
1249 sz = ftell(f);
1250 if (sz < 0) {
1251 err = -errno;
1252 goto err_out;
1253 }
1254 /* rewind to the start */
1255 if (fseek(f, 0, SEEK_SET)) {
1256 err = -errno;
1257 goto err_out;
1258 }
1259
1260 /* pre-alloc memory and read all of BTF data */
1261 data = malloc(sz);
1262 if (!data) {
1263 err = -ENOMEM;
1264 goto err_out;
1265 }
1266 if (fread(data, 1, sz, f) < sz) {
1267 err = -EIO;
1268 goto err_out;
1269 }
1270
1271 /* finally parse BTF data */
1272 btf = btf_new(data, sz, base_btf);
1273
1274err_out:
1275 free(data);
1276 if (f)
1277 fclose(f);
1278 return err ? ERR_PTR(err) : btf;
1279}
1280
1281struct btf *btf__parse_raw(const char *path)
1282{
1283 return libbpf_ptr(btf_parse_raw(path, NULL));
1284}
1285
1286struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf)
1287{
1288 return libbpf_ptr(btf_parse_raw(path, base_btf));
1289}
1290
1291static struct btf *btf_parse(const char *path, struct btf *base_btf, struct btf_ext **btf_ext)
1292{
1293 struct btf *btf;
1294 int err;
1295
1296 if (btf_ext)
1297 *btf_ext = NULL;
1298
1299 btf = btf_parse_raw(path, base_btf);
1300 err = libbpf_get_error(btf);
1301 if (!err)
1302 return btf;
1303 if (err != -EPROTO)
1304 return ERR_PTR(err);
1305 return btf_parse_elf(path, base_btf, btf_ext);
1306}
1307
1308struct btf *btf__parse(const char *path, struct btf_ext **btf_ext)
1309{
1310 return libbpf_ptr(btf_parse(path, NULL, btf_ext));
1311}
1312
1313struct btf *btf__parse_split(const char *path, struct btf *base_btf)
1314{
1315 return libbpf_ptr(btf_parse(path, base_btf, NULL));
1316}
1317
1318static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian);
1319
1320int btf_load_into_kernel(struct btf *btf, char *log_buf, size_t log_sz, __u32 log_level)
1321{
1322 LIBBPF_OPTS(bpf_btf_load_opts, opts);
1323 __u32 buf_sz = 0, raw_size;
1324 char *buf = NULL, *tmp;
1325 void *raw_data;
1326 int err = 0;
1327
1328 if (btf->fd >= 0)
1329 return libbpf_err(-EEXIST);
1330 if (log_sz && !log_buf)
1331 return libbpf_err(-EINVAL);
1332
1333 /* cache native raw data representation */
1334 raw_data = btf_get_raw_data(btf, &raw_size, false);
1335 if (!raw_data) {
1336 err = -ENOMEM;
1337 goto done;
1338 }
1339 btf->raw_size = raw_size;
1340 btf->raw_data = raw_data;
1341
1342retry_load:
1343 /* if log_level is 0, we won't provide log_buf/log_size to the kernel,
1344 * initially. Only if BTF loading fails, we bump log_level to 1 and
1345 * retry, using either auto-allocated or custom log_buf. This way
1346 * non-NULL custom log_buf provides a buffer just in case, but hopes
1347 * for successful load and no need for log_buf.
1348 */
1349 if (log_level) {
1350 /* if caller didn't provide custom log_buf, we'll keep
1351 * allocating our own progressively bigger buffers for BTF
1352 * verification log
1353 */
1354 if (!log_buf) {
1355 buf_sz = max((__u32)BPF_LOG_BUF_SIZE, buf_sz * 2);
1356 tmp = realloc(buf, buf_sz);
1357 if (!tmp) {
1358 err = -ENOMEM;
1359 goto done;
1360 }
1361 buf = tmp;
1362 buf[0] = '\0';
1363 }
1364
1365 opts.log_buf = log_buf ? log_buf : buf;
1366 opts.log_size = log_buf ? log_sz : buf_sz;
1367 opts.log_level = log_level;
1368 }
1369
1370 btf->fd = bpf_btf_load(raw_data, raw_size, &opts);
1371 if (btf->fd < 0) {
1372 /* time to turn on verbose mode and try again */
1373 if (log_level == 0) {
1374 log_level = 1;
1375 goto retry_load;
1376 }
1377 /* only retry if caller didn't provide custom log_buf, but
1378 * make sure we can never overflow buf_sz
1379 */
1380 if (!log_buf && errno == ENOSPC && buf_sz <= UINT_MAX / 2)
1381 goto retry_load;
1382
1383 err = -errno;
1384 pr_warn("BTF loading error: %d\n", err);
1385 /* don't print out contents of custom log_buf */
1386 if (!log_buf && buf[0])
1387 pr_warn("-- BEGIN BTF LOAD LOG ---\n%s\n-- END BTF LOAD LOG --\n", buf);
1388 }
1389
1390done:
1391 free(buf);
1392 return libbpf_err(err);
1393}
1394
1395int btf__load_into_kernel(struct btf *btf)
1396{
1397 return btf_load_into_kernel(btf, NULL, 0, 0);
1398}
1399
1400int btf__fd(const struct btf *btf)
1401{
1402 return btf->fd;
1403}
1404
1405void btf__set_fd(struct btf *btf, int fd)
1406{
1407 btf->fd = fd;
1408}
1409
1410static const void *btf_strs_data(const struct btf *btf)
1411{
1412 return btf->strs_data ? btf->strs_data : strset__data(btf->strs_set);
1413}
1414
1415static void *btf_get_raw_data(const struct btf *btf, __u32 *size, bool swap_endian)
1416{
1417 struct btf_header *hdr = btf->hdr;
1418 struct btf_type *t;
1419 void *data, *p;
1420 __u32 data_sz;
1421 int i;
1422
1423 data = swap_endian ? btf->raw_data_swapped : btf->raw_data;
1424 if (data) {
1425 *size = btf->raw_size;
1426 return data;
1427 }
1428
1429 data_sz = hdr->hdr_len + hdr->type_len + hdr->str_len;
1430 data = calloc(1, data_sz);
1431 if (!data)
1432 return NULL;
1433 p = data;
1434
1435 memcpy(p, hdr, hdr->hdr_len);
1436 if (swap_endian)
1437 btf_bswap_hdr(p);
1438 p += hdr->hdr_len;
1439
1440 memcpy(p, btf->types_data, hdr->type_len);
1441 if (swap_endian) {
1442 for (i = 0; i < btf->nr_types; i++) {
1443 t = p + btf->type_offs[i];
1444 /* btf_bswap_type_rest() relies on native t->info, so
1445 * we swap base type info after we swapped all the
1446 * additional information
1447 */
1448 if (btf_bswap_type_rest(t))
1449 goto err_out;
1450 btf_bswap_type_base(t);
1451 }
1452 }
1453 p += hdr->type_len;
1454
1455 memcpy(p, btf_strs_data(btf), hdr->str_len);
1456 p += hdr->str_len;
1457
1458 *size = data_sz;
1459 return data;
1460err_out:
1461 free(data);
1462 return NULL;
1463}
1464
1465const void *btf__raw_data(const struct btf *btf_ro, __u32 *size)
1466{
1467 struct btf *btf = (struct btf *)btf_ro;
1468 __u32 data_sz;
1469 void *data;
1470
1471 data = btf_get_raw_data(btf, &data_sz, btf->swapped_endian);
1472 if (!data)
1473 return errno = ENOMEM, NULL;
1474
1475 btf->raw_size = data_sz;
1476 if (btf->swapped_endian)
1477 btf->raw_data_swapped = data;
1478 else
1479 btf->raw_data = data;
1480 *size = data_sz;
1481 return data;
1482}
1483
1484__attribute__((alias("btf__raw_data")))
1485const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
1486
1487const char *btf__str_by_offset(const struct btf *btf, __u32 offset)
1488{
1489 if (offset < btf->start_str_off)
1490 return btf__str_by_offset(btf->base_btf, offset);
1491 else if (offset - btf->start_str_off < btf->hdr->str_len)
1492 return btf_strs_data(btf) + (offset - btf->start_str_off);
1493 else
1494 return errno = EINVAL, NULL;
1495}
1496
1497const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
1498{
1499 return btf__str_by_offset(btf, offset);
1500}
1501
1502struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf)
1503{
1504 struct bpf_btf_info btf_info;
1505 __u32 len = sizeof(btf_info);
1506 __u32 last_size;
1507 struct btf *btf;
1508 void *ptr;
1509 int err;
1510
1511 /* we won't know btf_size until we call bpf_btf_get_info_by_fd(). so
1512 * let's start with a sane default - 4KiB here - and resize it only if
1513 * bpf_btf_get_info_by_fd() needs a bigger buffer.
1514 */
1515 last_size = 4096;
1516 ptr = malloc(last_size);
1517 if (!ptr)
1518 return ERR_PTR(-ENOMEM);
1519
1520 memset(&btf_info, 0, sizeof(btf_info));
1521 btf_info.btf = ptr_to_u64(ptr);
1522 btf_info.btf_size = last_size;
1523 err = bpf_btf_get_info_by_fd(btf_fd, &btf_info, &len);
1524
1525 if (!err && btf_info.btf_size > last_size) {
1526 void *temp_ptr;
1527
1528 last_size = btf_info.btf_size;
1529 temp_ptr = realloc(ptr, last_size);
1530 if (!temp_ptr) {
1531 btf = ERR_PTR(-ENOMEM);
1532 goto exit_free;
1533 }
1534 ptr = temp_ptr;
1535
1536 len = sizeof(btf_info);
1537 memset(&btf_info, 0, sizeof(btf_info));
1538 btf_info.btf = ptr_to_u64(ptr);
1539 btf_info.btf_size = last_size;
1540
1541 err = bpf_btf_get_info_by_fd(btf_fd, &btf_info, &len);
1542 }
1543
1544 if (err || btf_info.btf_size > last_size) {
1545 btf = err ? ERR_PTR(-errno) : ERR_PTR(-E2BIG);
1546 goto exit_free;
1547 }
1548
1549 btf = btf_new(ptr, btf_info.btf_size, base_btf);
1550
1551exit_free:
1552 free(ptr);
1553 return btf;
1554}
1555
1556struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf)
1557{
1558 struct btf *btf;
1559 int btf_fd;
1560
1561 btf_fd = bpf_btf_get_fd_by_id(id);
1562 if (btf_fd < 0)
1563 return libbpf_err_ptr(-errno);
1564
1565 btf = btf_get_from_fd(btf_fd, base_btf);
1566 close(btf_fd);
1567
1568 return libbpf_ptr(btf);
1569}
1570
1571struct btf *btf__load_from_kernel_by_id(__u32 id)
1572{
1573 return btf__load_from_kernel_by_id_split(id, NULL);
1574}
1575
1576static void btf_invalidate_raw_data(struct btf *btf)
1577{
1578 if (btf->raw_data) {
1579 free(btf->raw_data);
1580 btf->raw_data = NULL;
1581 }
1582 if (btf->raw_data_swapped) {
1583 free(btf->raw_data_swapped);
1584 btf->raw_data_swapped = NULL;
1585 }
1586}
1587
1588/* Ensure BTF is ready to be modified (by splitting into a three memory
1589 * regions for header, types, and strings). Also invalidate cached
1590 * raw_data, if any.
1591 */
1592static int btf_ensure_modifiable(struct btf *btf)
1593{
1594 void *hdr, *types;
1595 struct strset *set = NULL;
1596 int err = -ENOMEM;
1597
1598 if (btf_is_modifiable(btf)) {
1599 /* any BTF modification invalidates raw_data */
1600 btf_invalidate_raw_data(btf);
1601 return 0;
1602 }
1603
1604 /* split raw data into three memory regions */
1605 hdr = malloc(btf->hdr->hdr_len);
1606 types = malloc(btf->hdr->type_len);
1607 if (!hdr || !types)
1608 goto err_out;
1609
1610 memcpy(hdr, btf->hdr, btf->hdr->hdr_len);
1611 memcpy(types, btf->types_data, btf->hdr->type_len);
1612
1613 /* build lookup index for all strings */
1614 set = strset__new(BTF_MAX_STR_OFFSET, btf->strs_data, btf->hdr->str_len);
1615 if (IS_ERR(set)) {
1616 err = PTR_ERR(set);
1617 goto err_out;
1618 }
1619
1620 /* only when everything was successful, update internal state */
1621 btf->hdr = hdr;
1622 btf->types_data = types;
1623 btf->types_data_cap = btf->hdr->type_len;
1624 btf->strs_data = NULL;
1625 btf->strs_set = set;
1626 /* if BTF was created from scratch, all strings are guaranteed to be
1627 * unique and deduplicated
1628 */
1629 if (btf->hdr->str_len == 0)
1630 btf->strs_deduped = true;
1631 if (!btf->base_btf && btf->hdr->str_len == 1)
1632 btf->strs_deduped = true;
1633
1634 /* invalidate raw_data representation */
1635 btf_invalidate_raw_data(btf);
1636
1637 return 0;
1638
1639err_out:
1640 strset__free(set);
1641 free(hdr);
1642 free(types);
1643 return err;
1644}
1645
1646/* Find an offset in BTF string section that corresponds to a given string *s*.
1647 * Returns:
1648 * - >0 offset into string section, if string is found;
1649 * - -ENOENT, if string is not in the string section;
1650 * - <0, on any other error.
1651 */
1652int btf__find_str(struct btf *btf, const char *s)
1653{
1654 int off;
1655
1656 if (btf->base_btf) {
1657 off = btf__find_str(btf->base_btf, s);
1658 if (off != -ENOENT)
1659 return off;
1660 }
1661
1662 /* BTF needs to be in a modifiable state to build string lookup index */
1663 if (btf_ensure_modifiable(btf))
1664 return libbpf_err(-ENOMEM);
1665
1666 off = strset__find_str(btf->strs_set, s);
1667 if (off < 0)
1668 return libbpf_err(off);
1669
1670 return btf->start_str_off + off;
1671}
1672
1673/* Add a string s to the BTF string section.
1674 * Returns:
1675 * - > 0 offset into string section, on success;
1676 * - < 0, on error.
1677 */
1678int btf__add_str(struct btf *btf, const char *s)
1679{
1680 int off;
1681
1682 if (btf->base_btf) {
1683 off = btf__find_str(btf->base_btf, s);
1684 if (off != -ENOENT)
1685 return off;
1686 }
1687
1688 if (btf_ensure_modifiable(btf))
1689 return libbpf_err(-ENOMEM);
1690
1691 off = strset__add_str(btf->strs_set, s);
1692 if (off < 0)
1693 return libbpf_err(off);
1694
1695 btf->hdr->str_len = strset__data_size(btf->strs_set);
1696
1697 return btf->start_str_off + off;
1698}
1699
1700static void *btf_add_type_mem(struct btf *btf, size_t add_sz)
1701{
1702 return libbpf_add_mem(&btf->types_data, &btf->types_data_cap, 1,
1703 btf->hdr->type_len, UINT_MAX, add_sz);
1704}
1705
1706static void btf_type_inc_vlen(struct btf_type *t)
1707{
1708 t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, btf_kflag(t));
1709}
1710
1711static int btf_commit_type(struct btf *btf, int data_sz)
1712{
1713 int err;
1714
1715 err = btf_add_type_idx_entry(btf, btf->hdr->type_len);
1716 if (err)
1717 return libbpf_err(err);
1718
1719 btf->hdr->type_len += data_sz;
1720 btf->hdr->str_off += data_sz;
1721 btf->nr_types++;
1722 return btf->start_id + btf->nr_types - 1;
1723}
1724
1725struct btf_pipe {
1726 const struct btf *src;
1727 struct btf *dst;
1728 struct hashmap *str_off_map; /* map string offsets from src to dst */
1729};
1730
1731static int btf_rewrite_str(__u32 *str_off, void *ctx)
1732{
1733 struct btf_pipe *p = ctx;
1734 long mapped_off;
1735 int off, err;
1736
1737 if (!*str_off) /* nothing to do for empty strings */
1738 return 0;
1739
1740 if (p->str_off_map &&
1741 hashmap__find(p->str_off_map, *str_off, &mapped_off)) {
1742 *str_off = mapped_off;
1743 return 0;
1744 }
1745
1746 off = btf__add_str(p->dst, btf__str_by_offset(p->src, *str_off));
1747 if (off < 0)
1748 return off;
1749
1750 /* Remember string mapping from src to dst. It avoids
1751 * performing expensive string comparisons.
1752 */
1753 if (p->str_off_map) {
1754 err = hashmap__append(p->str_off_map, *str_off, off);
1755 if (err)
1756 return err;
1757 }
1758
1759 *str_off = off;
1760 return 0;
1761}
1762
1763int btf__add_type(struct btf *btf, const struct btf *src_btf, const struct btf_type *src_type)
1764{
1765 struct btf_pipe p = { .src = src_btf, .dst = btf };
1766 struct btf_type *t;
1767 int sz, err;
1768
1769 sz = btf_type_size(src_type);
1770 if (sz < 0)
1771 return libbpf_err(sz);
1772
1773 /* deconstruct BTF, if necessary, and invalidate raw_data */
1774 if (btf_ensure_modifiable(btf))
1775 return libbpf_err(-ENOMEM);
1776
1777 t = btf_add_type_mem(btf, sz);
1778 if (!t)
1779 return libbpf_err(-ENOMEM);
1780
1781 memcpy(t, src_type, sz);
1782
1783 err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
1784 if (err)
1785 return libbpf_err(err);
1786
1787 return btf_commit_type(btf, sz);
1788}
1789
1790static int btf_rewrite_type_ids(__u32 *type_id, void *ctx)
1791{
1792 struct btf *btf = ctx;
1793
1794 if (!*type_id) /* nothing to do for VOID references */
1795 return 0;
1796
1797 /* we haven't updated btf's type count yet, so
1798 * btf->start_id + btf->nr_types - 1 is the type ID offset we should
1799 * add to all newly added BTF types
1800 */
1801 *type_id += btf->start_id + btf->nr_types - 1;
1802 return 0;
1803}
1804
1805static size_t btf_dedup_identity_hash_fn(long key, void *ctx);
1806static bool btf_dedup_equal_fn(long k1, long k2, void *ctx);
1807
1808int btf__add_btf(struct btf *btf, const struct btf *src_btf)
1809{
1810 struct btf_pipe p = { .src = src_btf, .dst = btf };
1811 int data_sz, sz, cnt, i, err, old_strs_len;
1812 __u32 *off;
1813 void *t;
1814
1815 /* appending split BTF isn't supported yet */
1816 if (src_btf->base_btf)
1817 return libbpf_err(-ENOTSUP);
1818
1819 /* deconstruct BTF, if necessary, and invalidate raw_data */
1820 if (btf_ensure_modifiable(btf))
1821 return libbpf_err(-ENOMEM);
1822
1823 /* remember original strings section size if we have to roll back
1824 * partial strings section changes
1825 */
1826 old_strs_len = btf->hdr->str_len;
1827
1828 data_sz = src_btf->hdr->type_len;
1829 cnt = btf__type_cnt(src_btf) - 1;
1830
1831 /* pre-allocate enough memory for new types */
1832 t = btf_add_type_mem(btf, data_sz);
1833 if (!t)
1834 return libbpf_err(-ENOMEM);
1835
1836 /* pre-allocate enough memory for type offset index for new types */
1837 off = btf_add_type_offs_mem(btf, cnt);
1838 if (!off)
1839 return libbpf_err(-ENOMEM);
1840
1841 /* Map the string offsets from src_btf to the offsets from btf to improve performance */
1842 p.str_off_map = hashmap__new(btf_dedup_identity_hash_fn, btf_dedup_equal_fn, NULL);
1843 if (IS_ERR(p.str_off_map))
1844 return libbpf_err(-ENOMEM);
1845
1846 /* bulk copy types data for all types from src_btf */
1847 memcpy(t, src_btf->types_data, data_sz);
1848
1849 for (i = 0; i < cnt; i++) {
1850 sz = btf_type_size(t);
1851 if (sz < 0) {
1852 /* unlikely, has to be corrupted src_btf */
1853 err = sz;
1854 goto err_out;
1855 }
1856
1857 /* fill out type ID to type offset mapping for lookups by type ID */
1858 *off = t - btf->types_data;
1859
1860 /* add, dedup, and remap strings referenced by this BTF type */
1861 err = btf_type_visit_str_offs(t, btf_rewrite_str, &p);
1862 if (err)
1863 goto err_out;
1864
1865 /* remap all type IDs referenced from this BTF type */
1866 err = btf_type_visit_type_ids(t, btf_rewrite_type_ids, btf);
1867 if (err)
1868 goto err_out;
1869
1870 /* go to next type data and type offset index entry */
1871 t += sz;
1872 off++;
1873 }
1874
1875 /* Up until now any of the copied type data was effectively invisible,
1876 * so if we exited early before this point due to error, BTF would be
1877 * effectively unmodified. There would be extra internal memory
1878 * pre-allocated, but it would not be available for querying. But now
1879 * that we've copied and rewritten all the data successfully, we can
1880 * update type count and various internal offsets and sizes to
1881 * "commit" the changes and made them visible to the outside world.
1882 */
1883 btf->hdr->type_len += data_sz;
1884 btf->hdr->str_off += data_sz;
1885 btf->nr_types += cnt;
1886
1887 hashmap__free(p.str_off_map);
1888
1889 /* return type ID of the first added BTF type */
1890 return btf->start_id + btf->nr_types - cnt;
1891err_out:
1892 /* zero out preallocated memory as if it was just allocated with
1893 * libbpf_add_mem()
1894 */
1895 memset(btf->types_data + btf->hdr->type_len, 0, data_sz);
1896 memset(btf->strs_data + old_strs_len, 0, btf->hdr->str_len - old_strs_len);
1897
1898 /* and now restore original strings section size; types data size
1899 * wasn't modified, so doesn't need restoring, see big comment above
1900 */
1901 btf->hdr->str_len = old_strs_len;
1902
1903 hashmap__free(p.str_off_map);
1904
1905 return libbpf_err(err);
1906}
1907
1908/*
1909 * Append new BTF_KIND_INT type with:
1910 * - *name* - non-empty, non-NULL type name;
1911 * - *sz* - power-of-2 (1, 2, 4, ..) size of the type, in bytes;
1912 * - encoding is a combination of BTF_INT_SIGNED, BTF_INT_CHAR, BTF_INT_BOOL.
1913 * Returns:
1914 * - >0, type ID of newly added BTF type;
1915 * - <0, on error.
1916 */
1917int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding)
1918{
1919 struct btf_type *t;
1920 int sz, name_off;
1921
1922 /* non-empty name */
1923 if (!name || !name[0])
1924 return libbpf_err(-EINVAL);
1925 /* byte_sz must be power of 2 */
1926 if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 16)
1927 return libbpf_err(-EINVAL);
1928 if (encoding & ~(BTF_INT_SIGNED | BTF_INT_CHAR | BTF_INT_BOOL))
1929 return libbpf_err(-EINVAL);
1930
1931 /* deconstruct BTF, if necessary, and invalidate raw_data */
1932 if (btf_ensure_modifiable(btf))
1933 return libbpf_err(-ENOMEM);
1934
1935 sz = sizeof(struct btf_type) + sizeof(int);
1936 t = btf_add_type_mem(btf, sz);
1937 if (!t)
1938 return libbpf_err(-ENOMEM);
1939
1940 /* if something goes wrong later, we might end up with an extra string,
1941 * but that shouldn't be a problem, because BTF can't be constructed
1942 * completely anyway and will most probably be just discarded
1943 */
1944 name_off = btf__add_str(btf, name);
1945 if (name_off < 0)
1946 return name_off;
1947
1948 t->name_off = name_off;
1949 t->info = btf_type_info(BTF_KIND_INT, 0, 0);
1950 t->size = byte_sz;
1951 /* set INT info, we don't allow setting legacy bit offset/size */
1952 *(__u32 *)(t + 1) = (encoding << 24) | (byte_sz * 8);
1953
1954 return btf_commit_type(btf, sz);
1955}
1956
1957/*
1958 * Append new BTF_KIND_FLOAT type with:
1959 * - *name* - non-empty, non-NULL type name;
1960 * - *sz* - size of the type, in bytes;
1961 * Returns:
1962 * - >0, type ID of newly added BTF type;
1963 * - <0, on error.
1964 */
1965int btf__add_float(struct btf *btf, const char *name, size_t byte_sz)
1966{
1967 struct btf_type *t;
1968 int sz, name_off;
1969
1970 /* non-empty name */
1971 if (!name || !name[0])
1972 return libbpf_err(-EINVAL);
1973
1974 /* byte_sz must be one of the explicitly allowed values */
1975 if (byte_sz != 2 && byte_sz != 4 && byte_sz != 8 && byte_sz != 12 &&
1976 byte_sz != 16)
1977 return libbpf_err(-EINVAL);
1978
1979 if (btf_ensure_modifiable(btf))
1980 return libbpf_err(-ENOMEM);
1981
1982 sz = sizeof(struct btf_type);
1983 t = btf_add_type_mem(btf, sz);
1984 if (!t)
1985 return libbpf_err(-ENOMEM);
1986
1987 name_off = btf__add_str(btf, name);
1988 if (name_off < 0)
1989 return name_off;
1990
1991 t->name_off = name_off;
1992 t->info = btf_type_info(BTF_KIND_FLOAT, 0, 0);
1993 t->size = byte_sz;
1994
1995 return btf_commit_type(btf, sz);
1996}
1997
1998/* it's completely legal to append BTF types with type IDs pointing forward to
1999 * types that haven't been appended yet, so we only make sure that id looks
2000 * sane, we can't guarantee that ID will always be valid
2001 */
2002static int validate_type_id(int id)
2003{
2004 if (id < 0 || id > BTF_MAX_NR_TYPES)
2005 return -EINVAL;
2006 return 0;
2007}
2008
2009/* generic append function for PTR, TYPEDEF, CONST/VOLATILE/RESTRICT */
2010static int btf_add_ref_kind(struct btf *btf, int kind, const char *name, int ref_type_id)
2011{
2012 struct btf_type *t;
2013 int sz, name_off = 0;
2014
2015 if (validate_type_id(ref_type_id))
2016 return libbpf_err(-EINVAL);
2017
2018 if (btf_ensure_modifiable(btf))
2019 return libbpf_err(-ENOMEM);
2020
2021 sz = sizeof(struct btf_type);
2022 t = btf_add_type_mem(btf, sz);
2023 if (!t)
2024 return libbpf_err(-ENOMEM);
2025
2026 if (name && name[0]) {
2027 name_off = btf__add_str(btf, name);
2028 if (name_off < 0)
2029 return name_off;
2030 }
2031
2032 t->name_off = name_off;
2033 t->info = btf_type_info(kind, 0, 0);
2034 t->type = ref_type_id;
2035
2036 return btf_commit_type(btf, sz);
2037}
2038
2039/*
2040 * Append new BTF_KIND_PTR type with:
2041 * - *ref_type_id* - referenced type ID, it might not exist yet;
2042 * Returns:
2043 * - >0, type ID of newly added BTF type;
2044 * - <0, on error.
2045 */
2046int btf__add_ptr(struct btf *btf, int ref_type_id)
2047{
2048 return btf_add_ref_kind(btf, BTF_KIND_PTR, NULL, ref_type_id);
2049}
2050
2051/*
2052 * Append new BTF_KIND_ARRAY type with:
2053 * - *index_type_id* - type ID of the type describing array index;
2054 * - *elem_type_id* - type ID of the type describing array element;
2055 * - *nr_elems* - the size of the array;
2056 * Returns:
2057 * - >0, type ID of newly added BTF type;
2058 * - <0, on error.
2059 */
2060int btf__add_array(struct btf *btf, int index_type_id, int elem_type_id, __u32 nr_elems)
2061{
2062 struct btf_type *t;
2063 struct btf_array *a;
2064 int sz;
2065
2066 if (validate_type_id(index_type_id) || validate_type_id(elem_type_id))
2067 return libbpf_err(-EINVAL);
2068
2069 if (btf_ensure_modifiable(btf))
2070 return libbpf_err(-ENOMEM);
2071
2072 sz = sizeof(struct btf_type) + sizeof(struct btf_array);
2073 t = btf_add_type_mem(btf, sz);
2074 if (!t)
2075 return libbpf_err(-ENOMEM);
2076
2077 t->name_off = 0;
2078 t->info = btf_type_info(BTF_KIND_ARRAY, 0, 0);
2079 t->size = 0;
2080
2081 a = btf_array(t);
2082 a->type = elem_type_id;
2083 a->index_type = index_type_id;
2084 a->nelems = nr_elems;
2085
2086 return btf_commit_type(btf, sz);
2087}
2088
2089/* generic STRUCT/UNION append function */
2090static int btf_add_composite(struct btf *btf, int kind, const char *name, __u32 bytes_sz)
2091{
2092 struct btf_type *t;
2093 int sz, name_off = 0;
2094
2095 if (btf_ensure_modifiable(btf))
2096 return libbpf_err(-ENOMEM);
2097
2098 sz = sizeof(struct btf_type);
2099 t = btf_add_type_mem(btf, sz);
2100 if (!t)
2101 return libbpf_err(-ENOMEM);
2102
2103 if (name && name[0]) {
2104 name_off = btf__add_str(btf, name);
2105 if (name_off < 0)
2106 return name_off;
2107 }
2108
2109 /* start out with vlen=0 and no kflag; this will be adjusted when
2110 * adding each member
2111 */
2112 t->name_off = name_off;
2113 t->info = btf_type_info(kind, 0, 0);
2114 t->size = bytes_sz;
2115
2116 return btf_commit_type(btf, sz);
2117}
2118
2119/*
2120 * Append new BTF_KIND_STRUCT type with:
2121 * - *name* - name of the struct, can be NULL or empty for anonymous structs;
2122 * - *byte_sz* - size of the struct, in bytes;
2123 *
2124 * Struct initially has no fields in it. Fields can be added by
2125 * btf__add_field() right after btf__add_struct() succeeds.
2126 *
2127 * Returns:
2128 * - >0, type ID of newly added BTF type;
2129 * - <0, on error.
2130 */
2131int btf__add_struct(struct btf *btf, const char *name, __u32 byte_sz)
2132{
2133 return btf_add_composite(btf, BTF_KIND_STRUCT, name, byte_sz);
2134}
2135
2136/*
2137 * Append new BTF_KIND_UNION type with:
2138 * - *name* - name of the union, can be NULL or empty for anonymous union;
2139 * - *byte_sz* - size of the union, in bytes;
2140 *
2141 * Union initially has no fields in it. Fields can be added by
2142 * btf__add_field() right after btf__add_union() succeeds. All fields
2143 * should have *bit_offset* of 0.
2144 *
2145 * Returns:
2146 * - >0, type ID of newly added BTF type;
2147 * - <0, on error.
2148 */
2149int btf__add_union(struct btf *btf, const char *name, __u32 byte_sz)
2150{
2151 return btf_add_composite(btf, BTF_KIND_UNION, name, byte_sz);
2152}
2153
2154static struct btf_type *btf_last_type(struct btf *btf)
2155{
2156 return btf_type_by_id(btf, btf__type_cnt(btf) - 1);
2157}
2158
2159/*
2160 * Append new field for the current STRUCT/UNION type with:
2161 * - *name* - name of the field, can be NULL or empty for anonymous field;
2162 * - *type_id* - type ID for the type describing field type;
2163 * - *bit_offset* - bit offset of the start of the field within struct/union;
2164 * - *bit_size* - bit size of a bitfield, 0 for non-bitfield fields;
2165 * Returns:
2166 * - 0, on success;
2167 * - <0, on error.
2168 */
2169int btf__add_field(struct btf *btf, const char *name, int type_id,
2170 __u32 bit_offset, __u32 bit_size)
2171{
2172 struct btf_type *t;
2173 struct btf_member *m;
2174 bool is_bitfield;
2175 int sz, name_off = 0;
2176
2177 /* last type should be union/struct */
2178 if (btf->nr_types == 0)
2179 return libbpf_err(-EINVAL);
2180 t = btf_last_type(btf);
2181 if (!btf_is_composite(t))
2182 return libbpf_err(-EINVAL);
2183
2184 if (validate_type_id(type_id))
2185 return libbpf_err(-EINVAL);
2186 /* best-effort bit field offset/size enforcement */
2187 is_bitfield = bit_size || (bit_offset % 8 != 0);
2188 if (is_bitfield && (bit_size == 0 || bit_size > 255 || bit_offset > 0xffffff))
2189 return libbpf_err(-EINVAL);
2190
2191 /* only offset 0 is allowed for unions */
2192 if (btf_is_union(t) && bit_offset)
2193 return libbpf_err(-EINVAL);
2194
2195 /* decompose and invalidate raw data */
2196 if (btf_ensure_modifiable(btf))
2197 return libbpf_err(-ENOMEM);
2198
2199 sz = sizeof(struct btf_member);
2200 m = btf_add_type_mem(btf, sz);
2201 if (!m)
2202 return libbpf_err(-ENOMEM);
2203
2204 if (name && name[0]) {
2205 name_off = btf__add_str(btf, name);
2206 if (name_off < 0)
2207 return name_off;
2208 }
2209
2210 m->name_off = name_off;
2211 m->type = type_id;
2212 m->offset = bit_offset | (bit_size << 24);
2213
2214 /* btf_add_type_mem can invalidate t pointer */
2215 t = btf_last_type(btf);
2216 /* update parent type's vlen and kflag */
2217 t->info = btf_type_info(btf_kind(t), btf_vlen(t) + 1, is_bitfield || btf_kflag(t));
2218
2219 btf->hdr->type_len += sz;
2220 btf->hdr->str_off += sz;
2221 return 0;
2222}
2223
2224static int btf_add_enum_common(struct btf *btf, const char *name, __u32 byte_sz,
2225 bool is_signed, __u8 kind)
2226{
2227 struct btf_type *t;
2228 int sz, name_off = 0;
2229
2230 /* byte_sz must be power of 2 */
2231 if (!byte_sz || (byte_sz & (byte_sz - 1)) || byte_sz > 8)
2232 return libbpf_err(-EINVAL);
2233
2234 if (btf_ensure_modifiable(btf))
2235 return libbpf_err(-ENOMEM);
2236
2237 sz = sizeof(struct btf_type);
2238 t = btf_add_type_mem(btf, sz);
2239 if (!t)
2240 return libbpf_err(-ENOMEM);
2241
2242 if (name && name[0]) {
2243 name_off = btf__add_str(btf, name);
2244 if (name_off < 0)
2245 return name_off;
2246 }
2247
2248 /* start out with vlen=0; it will be adjusted when adding enum values */
2249 t->name_off = name_off;
2250 t->info = btf_type_info(kind, 0, is_signed);
2251 t->size = byte_sz;
2252
2253 return btf_commit_type(btf, sz);
2254}
2255
2256/*
2257 * Append new BTF_KIND_ENUM type with:
2258 * - *name* - name of the enum, can be NULL or empty for anonymous enums;
2259 * - *byte_sz* - size of the enum, in bytes.
2260 *
2261 * Enum initially has no enum values in it (and corresponds to enum forward
2262 * declaration). Enumerator values can be added by btf__add_enum_value()
2263 * immediately after btf__add_enum() succeeds.
2264 *
2265 * Returns:
2266 * - >0, type ID of newly added BTF type;
2267 * - <0, on error.
2268 */
2269int btf__add_enum(struct btf *btf, const char *name, __u32 byte_sz)
2270{
2271 /*
2272 * set the signedness to be unsigned, it will change to signed
2273 * if any later enumerator is negative.
2274 */
2275 return btf_add_enum_common(btf, name, byte_sz, false, BTF_KIND_ENUM);
2276}
2277
2278/*
2279 * Append new enum value for the current ENUM type with:
2280 * - *name* - name of the enumerator value, can't be NULL or empty;
2281 * - *value* - integer value corresponding to enum value *name*;
2282 * Returns:
2283 * - 0, on success;
2284 * - <0, on error.
2285 */
2286int btf__add_enum_value(struct btf *btf, const char *name, __s64 value)
2287{
2288 struct btf_type *t;
2289 struct btf_enum *v;
2290 int sz, name_off;
2291
2292 /* last type should be BTF_KIND_ENUM */
2293 if (btf->nr_types == 0)
2294 return libbpf_err(-EINVAL);
2295 t = btf_last_type(btf);
2296 if (!btf_is_enum(t))
2297 return libbpf_err(-EINVAL);
2298
2299 /* non-empty name */
2300 if (!name || !name[0])
2301 return libbpf_err(-EINVAL);
2302 if (value < INT_MIN || value > UINT_MAX)
2303 return libbpf_err(-E2BIG);
2304
2305 /* decompose and invalidate raw data */
2306 if (btf_ensure_modifiable(btf))
2307 return libbpf_err(-ENOMEM);
2308
2309 sz = sizeof(struct btf_enum);
2310 v = btf_add_type_mem(btf, sz);
2311 if (!v)
2312 return libbpf_err(-ENOMEM);
2313
2314 name_off = btf__add_str(btf, name);
2315 if (name_off < 0)
2316 return name_off;
2317
2318 v->name_off = name_off;
2319 v->val = value;
2320
2321 /* update parent type's vlen */
2322 t = btf_last_type(btf);
2323 btf_type_inc_vlen(t);
2324
2325 /* if negative value, set signedness to signed */
2326 if (value < 0)
2327 t->info = btf_type_info(btf_kind(t), btf_vlen(t), true);
2328
2329 btf->hdr->type_len += sz;
2330 btf->hdr->str_off += sz;
2331 return 0;
2332}
2333
2334/*
2335 * Append new BTF_KIND_ENUM64 type with:
2336 * - *name* - name of the enum, can be NULL or empty for anonymous enums;
2337 * - *byte_sz* - size of the enum, in bytes.
2338 * - *is_signed* - whether the enum values are signed or not;
2339 *
2340 * Enum initially has no enum values in it (and corresponds to enum forward
2341 * declaration). Enumerator values can be added by btf__add_enum64_value()
2342 * immediately after btf__add_enum64() succeeds.
2343 *
2344 * Returns:
2345 * - >0, type ID of newly added BTF type;
2346 * - <0, on error.
2347 */
2348int btf__add_enum64(struct btf *btf, const char *name, __u32 byte_sz,
2349 bool is_signed)
2350{
2351 return btf_add_enum_common(btf, name, byte_sz, is_signed,
2352 BTF_KIND_ENUM64);
2353}
2354
2355/*
2356 * Append new enum value for the current ENUM64 type with:
2357 * - *name* - name of the enumerator value, can't be NULL or empty;
2358 * - *value* - integer value corresponding to enum value *name*;
2359 * Returns:
2360 * - 0, on success;
2361 * - <0, on error.
2362 */
2363int btf__add_enum64_value(struct btf *btf, const char *name, __u64 value)
2364{
2365 struct btf_enum64 *v;
2366 struct btf_type *t;
2367 int sz, name_off;
2368
2369 /* last type should be BTF_KIND_ENUM64 */
2370 if (btf->nr_types == 0)
2371 return libbpf_err(-EINVAL);
2372 t = btf_last_type(btf);
2373 if (!btf_is_enum64(t))
2374 return libbpf_err(-EINVAL);
2375
2376 /* non-empty name */
2377 if (!name || !name[0])
2378 return libbpf_err(-EINVAL);
2379
2380 /* decompose and invalidate raw data */
2381 if (btf_ensure_modifiable(btf))
2382 return libbpf_err(-ENOMEM);
2383
2384 sz = sizeof(struct btf_enum64);
2385 v = btf_add_type_mem(btf, sz);
2386 if (!v)
2387 return libbpf_err(-ENOMEM);
2388
2389 name_off = btf__add_str(btf, name);
2390 if (name_off < 0)
2391 return name_off;
2392
2393 v->name_off = name_off;
2394 v->val_lo32 = (__u32)value;
2395 v->val_hi32 = value >> 32;
2396
2397 /* update parent type's vlen */
2398 t = btf_last_type(btf);
2399 btf_type_inc_vlen(t);
2400
2401 btf->hdr->type_len += sz;
2402 btf->hdr->str_off += sz;
2403 return 0;
2404}
2405
2406/*
2407 * Append new BTF_KIND_FWD type with:
2408 * - *name*, non-empty/non-NULL name;
2409 * - *fwd_kind*, kind of forward declaration, one of BTF_FWD_STRUCT,
2410 * BTF_FWD_UNION, or BTF_FWD_ENUM;
2411 * Returns:
2412 * - >0, type ID of newly added BTF type;
2413 * - <0, on error.
2414 */
2415int btf__add_fwd(struct btf *btf, const char *name, enum btf_fwd_kind fwd_kind)
2416{
2417 if (!name || !name[0])
2418 return libbpf_err(-EINVAL);
2419
2420 switch (fwd_kind) {
2421 case BTF_FWD_STRUCT:
2422 case BTF_FWD_UNION: {
2423 struct btf_type *t;
2424 int id;
2425
2426 id = btf_add_ref_kind(btf, BTF_KIND_FWD, name, 0);
2427 if (id <= 0)
2428 return id;
2429 t = btf_type_by_id(btf, id);
2430 t->info = btf_type_info(BTF_KIND_FWD, 0, fwd_kind == BTF_FWD_UNION);
2431 return id;
2432 }
2433 case BTF_FWD_ENUM:
2434 /* enum forward in BTF currently is just an enum with no enum
2435 * values; we also assume a standard 4-byte size for it
2436 */
2437 return btf__add_enum(btf, name, sizeof(int));
2438 default:
2439 return libbpf_err(-EINVAL);
2440 }
2441}
2442
2443/*
2444 * Append new BTF_KING_TYPEDEF type with:
2445 * - *name*, non-empty/non-NULL name;
2446 * - *ref_type_id* - referenced type ID, it might not exist yet;
2447 * Returns:
2448 * - >0, type ID of newly added BTF type;
2449 * - <0, on error.
2450 */
2451int btf__add_typedef(struct btf *btf, const char *name, int ref_type_id)
2452{
2453 if (!name || !name[0])
2454 return libbpf_err(-EINVAL);
2455
2456 return btf_add_ref_kind(btf, BTF_KIND_TYPEDEF, name, ref_type_id);
2457}
2458
2459/*
2460 * Append new BTF_KIND_VOLATILE type with:
2461 * - *ref_type_id* - referenced type ID, it might not exist yet;
2462 * Returns:
2463 * - >0, type ID of newly added BTF type;
2464 * - <0, on error.
2465 */
2466int btf__add_volatile(struct btf *btf, int ref_type_id)
2467{
2468 return btf_add_ref_kind(btf, BTF_KIND_VOLATILE, NULL, ref_type_id);
2469}
2470
2471/*
2472 * Append new BTF_KIND_CONST type with:
2473 * - *ref_type_id* - referenced type ID, it might not exist yet;
2474 * Returns:
2475 * - >0, type ID of newly added BTF type;
2476 * - <0, on error.
2477 */
2478int btf__add_const(struct btf *btf, int ref_type_id)
2479{
2480 return btf_add_ref_kind(btf, BTF_KIND_CONST, NULL, ref_type_id);
2481}
2482
2483/*
2484 * Append new BTF_KIND_RESTRICT type with:
2485 * - *ref_type_id* - referenced type ID, it might not exist yet;
2486 * Returns:
2487 * - >0, type ID of newly added BTF type;
2488 * - <0, on error.
2489 */
2490int btf__add_restrict(struct btf *btf, int ref_type_id)
2491{
2492 return btf_add_ref_kind(btf, BTF_KIND_RESTRICT, NULL, ref_type_id);
2493}
2494
2495/*
2496 * Append new BTF_KIND_TYPE_TAG type with:
2497 * - *value*, non-empty/non-NULL tag value;
2498 * - *ref_type_id* - referenced type ID, it might not exist yet;
2499 * Returns:
2500 * - >0, type ID of newly added BTF type;
2501 * - <0, on error.
2502 */
2503int btf__add_type_tag(struct btf *btf, const char *value, int ref_type_id)
2504{
2505 if (!value || !value[0])
2506 return libbpf_err(-EINVAL);
2507
2508 return btf_add_ref_kind(btf, BTF_KIND_TYPE_TAG, value, ref_type_id);
2509}
2510
2511/*
2512 * Append new BTF_KIND_FUNC type with:
2513 * - *name*, non-empty/non-NULL name;
2514 * - *proto_type_id* - FUNC_PROTO's type ID, it might not exist yet;
2515 * Returns:
2516 * - >0, type ID of newly added BTF type;
2517 * - <0, on error.
2518 */
2519int btf__add_func(struct btf *btf, const char *name,
2520 enum btf_func_linkage linkage, int proto_type_id)
2521{
2522 int id;
2523
2524 if (!name || !name[0])
2525 return libbpf_err(-EINVAL);
2526 if (linkage != BTF_FUNC_STATIC && linkage != BTF_FUNC_GLOBAL &&
2527 linkage != BTF_FUNC_EXTERN)
2528 return libbpf_err(-EINVAL);
2529
2530 id = btf_add_ref_kind(btf, BTF_KIND_FUNC, name, proto_type_id);
2531 if (id > 0) {
2532 struct btf_type *t = btf_type_by_id(btf, id);
2533
2534 t->info = btf_type_info(BTF_KIND_FUNC, linkage, 0);
2535 }
2536 return libbpf_err(id);
2537}
2538
2539/*
2540 * Append new BTF_KIND_FUNC_PROTO with:
2541 * - *ret_type_id* - type ID for return result of a function.
2542 *
2543 * Function prototype initially has no arguments, but they can be added by
2544 * btf__add_func_param() one by one, immediately after
2545 * btf__add_func_proto() succeeded.
2546 *
2547 * Returns:
2548 * - >0, type ID of newly added BTF type;
2549 * - <0, on error.
2550 */
2551int btf__add_func_proto(struct btf *btf, int ret_type_id)
2552{
2553 struct btf_type *t;
2554 int sz;
2555
2556 if (validate_type_id(ret_type_id))
2557 return libbpf_err(-EINVAL);
2558
2559 if (btf_ensure_modifiable(btf))
2560 return libbpf_err(-ENOMEM);
2561
2562 sz = sizeof(struct btf_type);
2563 t = btf_add_type_mem(btf, sz);
2564 if (!t)
2565 return libbpf_err(-ENOMEM);
2566
2567 /* start out with vlen=0; this will be adjusted when adding enum
2568 * values, if necessary
2569 */
2570 t->name_off = 0;
2571 t->info = btf_type_info(BTF_KIND_FUNC_PROTO, 0, 0);
2572 t->type = ret_type_id;
2573
2574 return btf_commit_type(btf, sz);
2575}
2576
2577/*
2578 * Append new function parameter for current FUNC_PROTO type with:
2579 * - *name* - parameter name, can be NULL or empty;
2580 * - *type_id* - type ID describing the type of the parameter.
2581 * Returns:
2582 * - 0, on success;
2583 * - <0, on error.
2584 */
2585int btf__add_func_param(struct btf *btf, const char *name, int type_id)
2586{
2587 struct btf_type *t;
2588 struct btf_param *p;
2589 int sz, name_off = 0;
2590
2591 if (validate_type_id(type_id))
2592 return libbpf_err(-EINVAL);
2593
2594 /* last type should be BTF_KIND_FUNC_PROTO */
2595 if (btf->nr_types == 0)
2596 return libbpf_err(-EINVAL);
2597 t = btf_last_type(btf);
2598 if (!btf_is_func_proto(t))
2599 return libbpf_err(-EINVAL);
2600
2601 /* decompose and invalidate raw data */
2602 if (btf_ensure_modifiable(btf))
2603 return libbpf_err(-ENOMEM);
2604
2605 sz = sizeof(struct btf_param);
2606 p = btf_add_type_mem(btf, sz);
2607 if (!p)
2608 return libbpf_err(-ENOMEM);
2609
2610 if (name && name[0]) {
2611 name_off = btf__add_str(btf, name);
2612 if (name_off < 0)
2613 return name_off;
2614 }
2615
2616 p->name_off = name_off;
2617 p->type = type_id;
2618
2619 /* update parent type's vlen */
2620 t = btf_last_type(btf);
2621 btf_type_inc_vlen(t);
2622
2623 btf->hdr->type_len += sz;
2624 btf->hdr->str_off += sz;
2625 return 0;
2626}
2627
2628/*
2629 * Append new BTF_KIND_VAR type with:
2630 * - *name* - non-empty/non-NULL name;
2631 * - *linkage* - variable linkage, one of BTF_VAR_STATIC,
2632 * BTF_VAR_GLOBAL_ALLOCATED, or BTF_VAR_GLOBAL_EXTERN;
2633 * - *type_id* - type ID of the type describing the type of the variable.
2634 * Returns:
2635 * - >0, type ID of newly added BTF type;
2636 * - <0, on error.
2637 */
2638int btf__add_var(struct btf *btf, const char *name, int linkage, int type_id)
2639{
2640 struct btf_type *t;
2641 struct btf_var *v;
2642 int sz, name_off;
2643
2644 /* non-empty name */
2645 if (!name || !name[0])
2646 return libbpf_err(-EINVAL);
2647 if (linkage != BTF_VAR_STATIC && linkage != BTF_VAR_GLOBAL_ALLOCATED &&
2648 linkage != BTF_VAR_GLOBAL_EXTERN)
2649 return libbpf_err(-EINVAL);
2650 if (validate_type_id(type_id))
2651 return libbpf_err(-EINVAL);
2652
2653 /* deconstruct BTF, if necessary, and invalidate raw_data */
2654 if (btf_ensure_modifiable(btf))
2655 return libbpf_err(-ENOMEM);
2656
2657 sz = sizeof(struct btf_type) + sizeof(struct btf_var);
2658 t = btf_add_type_mem(btf, sz);
2659 if (!t)
2660 return libbpf_err(-ENOMEM);
2661
2662 name_off = btf__add_str(btf, name);
2663 if (name_off < 0)
2664 return name_off;
2665
2666 t->name_off = name_off;
2667 t->info = btf_type_info(BTF_KIND_VAR, 0, 0);
2668 t->type = type_id;
2669
2670 v = btf_var(t);
2671 v->linkage = linkage;
2672
2673 return btf_commit_type(btf, sz);
2674}
2675
2676/*
2677 * Append new BTF_KIND_DATASEC type with:
2678 * - *name* - non-empty/non-NULL name;
2679 * - *byte_sz* - data section size, in bytes.
2680 *
2681 * Data section is initially empty. Variables info can be added with
2682 * btf__add_datasec_var_info() calls, after btf__add_datasec() succeeds.
2683 *
2684 * Returns:
2685 * - >0, type ID of newly added BTF type;
2686 * - <0, on error.
2687 */
2688int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz)
2689{
2690 struct btf_type *t;
2691 int sz, name_off;
2692
2693 /* non-empty name */
2694 if (!name || !name[0])
2695 return libbpf_err(-EINVAL);
2696
2697 if (btf_ensure_modifiable(btf))
2698 return libbpf_err(-ENOMEM);
2699
2700 sz = sizeof(struct btf_type);
2701 t = btf_add_type_mem(btf, sz);
2702 if (!t)
2703 return libbpf_err(-ENOMEM);
2704
2705 name_off = btf__add_str(btf, name);
2706 if (name_off < 0)
2707 return name_off;
2708
2709 /* start with vlen=0, which will be update as var_secinfos are added */
2710 t->name_off = name_off;
2711 t->info = btf_type_info(BTF_KIND_DATASEC, 0, 0);
2712 t->size = byte_sz;
2713
2714 return btf_commit_type(btf, sz);
2715}
2716
2717/*
2718 * Append new data section variable information entry for current DATASEC type:
2719 * - *var_type_id* - type ID, describing type of the variable;
2720 * - *offset* - variable offset within data section, in bytes;
2721 * - *byte_sz* - variable size, in bytes.
2722 *
2723 * Returns:
2724 * - 0, on success;
2725 * - <0, on error.
2726 */
2727int btf__add_datasec_var_info(struct btf *btf, int var_type_id, __u32 offset, __u32 byte_sz)
2728{
2729 struct btf_type *t;
2730 struct btf_var_secinfo *v;
2731 int sz;
2732
2733 /* last type should be BTF_KIND_DATASEC */
2734 if (btf->nr_types == 0)
2735 return libbpf_err(-EINVAL);
2736 t = btf_last_type(btf);
2737 if (!btf_is_datasec(t))
2738 return libbpf_err(-EINVAL);
2739
2740 if (validate_type_id(var_type_id))
2741 return libbpf_err(-EINVAL);
2742
2743 /* decompose and invalidate raw data */
2744 if (btf_ensure_modifiable(btf))
2745 return libbpf_err(-ENOMEM);
2746
2747 sz = sizeof(struct btf_var_secinfo);
2748 v = btf_add_type_mem(btf, sz);
2749 if (!v)
2750 return libbpf_err(-ENOMEM);
2751
2752 v->type = var_type_id;
2753 v->offset = offset;
2754 v->size = byte_sz;
2755
2756 /* update parent type's vlen */
2757 t = btf_last_type(btf);
2758 btf_type_inc_vlen(t);
2759
2760 btf->hdr->type_len += sz;
2761 btf->hdr->str_off += sz;
2762 return 0;
2763}
2764
2765/*
2766 * Append new BTF_KIND_DECL_TAG type with:
2767 * - *value* - non-empty/non-NULL string;
2768 * - *ref_type_id* - referenced type ID, it might not exist yet;
2769 * - *component_idx* - -1 for tagging reference type, otherwise struct/union
2770 * member or function argument index;
2771 * Returns:
2772 * - >0, type ID of newly added BTF type;
2773 * - <0, on error.
2774 */
2775int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
2776 int component_idx)
2777{
2778 struct btf_type *t;
2779 int sz, value_off;
2780
2781 if (!value || !value[0] || component_idx < -1)
2782 return libbpf_err(-EINVAL);
2783
2784 if (validate_type_id(ref_type_id))
2785 return libbpf_err(-EINVAL);
2786
2787 if (btf_ensure_modifiable(btf))
2788 return libbpf_err(-ENOMEM);
2789
2790 sz = sizeof(struct btf_type) + sizeof(struct btf_decl_tag);
2791 t = btf_add_type_mem(btf, sz);
2792 if (!t)
2793 return libbpf_err(-ENOMEM);
2794
2795 value_off = btf__add_str(btf, value);
2796 if (value_off < 0)
2797 return value_off;
2798
2799 t->name_off = value_off;
2800 t->info = btf_type_info(BTF_KIND_DECL_TAG, 0, false);
2801 t->type = ref_type_id;
2802 btf_decl_tag(t)->component_idx = component_idx;
2803
2804 return btf_commit_type(btf, sz);
2805}
2806
2807struct btf_ext_sec_setup_param {
2808 __u32 off;
2809 __u32 len;
2810 __u32 min_rec_size;
2811 struct btf_ext_info *ext_info;
2812 const char *desc;
2813};
2814
2815static int btf_ext_setup_info(struct btf_ext *btf_ext,
2816 struct btf_ext_sec_setup_param *ext_sec)
2817{
2818 const struct btf_ext_info_sec *sinfo;
2819 struct btf_ext_info *ext_info;
2820 __u32 info_left, record_size;
2821 size_t sec_cnt = 0;
2822 /* The start of the info sec (including the __u32 record_size). */
2823 void *info;
2824
2825 if (ext_sec->len == 0)
2826 return 0;
2827
2828 if (ext_sec->off & 0x03) {
2829 pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
2830 ext_sec->desc);
2831 return -EINVAL;
2832 }
2833
2834 info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;
2835 info_left = ext_sec->len;
2836
2837 if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {
2838 pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
2839 ext_sec->desc, ext_sec->off, ext_sec->len);
2840 return -EINVAL;
2841 }
2842
2843 /* At least a record size */
2844 if (info_left < sizeof(__u32)) {
2845 pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
2846 return -EINVAL;
2847 }
2848
2849 /* The record size needs to meet the minimum standard */
2850 record_size = *(__u32 *)info;
2851 if (record_size < ext_sec->min_rec_size ||
2852 record_size & 0x03) {
2853 pr_debug("%s section in .BTF.ext has invalid record size %u\n",
2854 ext_sec->desc, record_size);
2855 return -EINVAL;
2856 }
2857
2858 sinfo = info + sizeof(__u32);
2859 info_left -= sizeof(__u32);
2860
2861 /* If no records, return failure now so .BTF.ext won't be used. */
2862 if (!info_left) {
2863 pr_debug("%s section in .BTF.ext has no records", ext_sec->desc);
2864 return -EINVAL;
2865 }
2866
2867 while (info_left) {
2868 unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
2869 __u64 total_record_size;
2870 __u32 num_records;
2871
2872 if (info_left < sec_hdrlen) {
2873 pr_debug("%s section header is not found in .BTF.ext\n",
2874 ext_sec->desc);
2875 return -EINVAL;
2876 }
2877
2878 num_records = sinfo->num_info;
2879 if (num_records == 0) {
2880 pr_debug("%s section has incorrect num_records in .BTF.ext\n",
2881 ext_sec->desc);
2882 return -EINVAL;
2883 }
2884
2885 total_record_size = sec_hdrlen + (__u64)num_records * record_size;
2886 if (info_left < total_record_size) {
2887 pr_debug("%s section has incorrect num_records in .BTF.ext\n",
2888 ext_sec->desc);
2889 return -EINVAL;
2890 }
2891
2892 info_left -= total_record_size;
2893 sinfo = (void *)sinfo + total_record_size;
2894 sec_cnt++;
2895 }
2896
2897 ext_info = ext_sec->ext_info;
2898 ext_info->len = ext_sec->len - sizeof(__u32);
2899 ext_info->rec_size = record_size;
2900 ext_info->info = info + sizeof(__u32);
2901 ext_info->sec_cnt = sec_cnt;
2902
2903 return 0;
2904}
2905
2906static int btf_ext_setup_func_info(struct btf_ext *btf_ext)
2907{
2908 struct btf_ext_sec_setup_param param = {
2909 .off = btf_ext->hdr->func_info_off,
2910 .len = btf_ext->hdr->func_info_len,
2911 .min_rec_size = sizeof(struct bpf_func_info_min),
2912 .ext_info = &btf_ext->func_info,
2913 .desc = "func_info"
2914 };
2915
2916 return btf_ext_setup_info(btf_ext, ¶m);
2917}
2918
2919static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
2920{
2921 struct btf_ext_sec_setup_param param = {
2922 .off = btf_ext->hdr->line_info_off,
2923 .len = btf_ext->hdr->line_info_len,
2924 .min_rec_size = sizeof(struct bpf_line_info_min),
2925 .ext_info = &btf_ext->line_info,
2926 .desc = "line_info",
2927 };
2928
2929 return btf_ext_setup_info(btf_ext, ¶m);
2930}
2931
2932static int btf_ext_setup_core_relos(struct btf_ext *btf_ext)
2933{
2934 struct btf_ext_sec_setup_param param = {
2935 .off = btf_ext->hdr->core_relo_off,
2936 .len = btf_ext->hdr->core_relo_len,
2937 .min_rec_size = sizeof(struct bpf_core_relo),
2938 .ext_info = &btf_ext->core_relo_info,
2939 .desc = "core_relo",
2940 };
2941
2942 return btf_ext_setup_info(btf_ext, ¶m);
2943}
2944
2945static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
2946{
2947 const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
2948
2949 if (data_size < offsetofend(struct btf_ext_header, hdr_len) ||
2950 data_size < hdr->hdr_len) {
2951 pr_debug("BTF.ext header not found");
2952 return -EINVAL;
2953 }
2954
2955 if (hdr->magic == bswap_16(BTF_MAGIC)) {
2956 pr_warn("BTF.ext in non-native endianness is not supported\n");
2957 return -ENOTSUP;
2958 } else if (hdr->magic != BTF_MAGIC) {
2959 pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic);
2960 return -EINVAL;
2961 }
2962
2963 if (hdr->version != BTF_VERSION) {
2964 pr_debug("Unsupported BTF.ext version:%u\n", hdr->version);
2965 return -ENOTSUP;
2966 }
2967
2968 if (hdr->flags) {
2969 pr_debug("Unsupported BTF.ext flags:%x\n", hdr->flags);
2970 return -ENOTSUP;
2971 }
2972
2973 if (data_size == hdr->hdr_len) {
2974 pr_debug("BTF.ext has no data\n");
2975 return -EINVAL;
2976 }
2977
2978 return 0;
2979}
2980
2981void btf_ext__free(struct btf_ext *btf_ext)
2982{
2983 if (IS_ERR_OR_NULL(btf_ext))
2984 return;
2985 free(btf_ext->func_info.sec_idxs);
2986 free(btf_ext->line_info.sec_idxs);
2987 free(btf_ext->core_relo_info.sec_idxs);
2988 free(btf_ext->data);
2989 free(btf_ext);
2990}
2991
2992struct btf_ext *btf_ext__new(const __u8 *data, __u32 size)
2993{
2994 struct btf_ext *btf_ext;
2995 int err;
2996
2997 btf_ext = calloc(1, sizeof(struct btf_ext));
2998 if (!btf_ext)
2999 return libbpf_err_ptr(-ENOMEM);
3000
3001 btf_ext->data_size = size;
3002 btf_ext->data = malloc(size);
3003 if (!btf_ext->data) {
3004 err = -ENOMEM;
3005 goto done;
3006 }
3007 memcpy(btf_ext->data, data, size);
3008
3009 err = btf_ext_parse_hdr(btf_ext->data, size);
3010 if (err)
3011 goto done;
3012
3013 if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, line_info_len)) {
3014 err = -EINVAL;
3015 goto done;
3016 }
3017
3018 err = btf_ext_setup_func_info(btf_ext);
3019 if (err)
3020 goto done;
3021
3022 err = btf_ext_setup_line_info(btf_ext);
3023 if (err)
3024 goto done;
3025
3026 if (btf_ext->hdr->hdr_len < offsetofend(struct btf_ext_header, core_relo_len))
3027 goto done; /* skip core relos parsing */
3028
3029 err = btf_ext_setup_core_relos(btf_ext);
3030 if (err)
3031 goto done;
3032
3033done:
3034 if (err) {
3035 btf_ext__free(btf_ext);
3036 return libbpf_err_ptr(err);
3037 }
3038
3039 return btf_ext;
3040}
3041
3042const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size)
3043{
3044 *size = btf_ext->data_size;
3045 return btf_ext->data;
3046}
3047
3048struct btf_dedup;
3049
3050static struct btf_dedup *btf_dedup_new(struct btf *btf, const struct btf_dedup_opts *opts);
3051static void btf_dedup_free(struct btf_dedup *d);
3052static int btf_dedup_prep(struct btf_dedup *d);
3053static int btf_dedup_strings(struct btf_dedup *d);
3054static int btf_dedup_prim_types(struct btf_dedup *d);
3055static int btf_dedup_struct_types(struct btf_dedup *d);
3056static int btf_dedup_ref_types(struct btf_dedup *d);
3057static int btf_dedup_resolve_fwds(struct btf_dedup *d);
3058static int btf_dedup_compact_types(struct btf_dedup *d);
3059static int btf_dedup_remap_types(struct btf_dedup *d);
3060
3061/*
3062 * Deduplicate BTF types and strings.
3063 *
3064 * BTF dedup algorithm takes as an input `struct btf` representing `.BTF` ELF
3065 * section with all BTF type descriptors and string data. It overwrites that
3066 * memory in-place with deduplicated types and strings without any loss of
3067 * information. If optional `struct btf_ext` representing '.BTF.ext' ELF section
3068 * is provided, all the strings referenced from .BTF.ext section are honored
3069 * and updated to point to the right offsets after deduplication.
3070 *
3071 * If function returns with error, type/string data might be garbled and should
3072 * be discarded.
3073 *
3074 * More verbose and detailed description of both problem btf_dedup is solving,
3075 * as well as solution could be found at:
3076 * https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
3077 *
3078 * Problem description and justification
3079 * =====================================
3080 *
3081 * BTF type information is typically emitted either as a result of conversion
3082 * from DWARF to BTF or directly by compiler. In both cases, each compilation
3083 * unit contains information about a subset of all the types that are used
3084 * in an application. These subsets are frequently overlapping and contain a lot
3085 * of duplicated information when later concatenated together into a single
3086 * binary. This algorithm ensures that each unique type is represented by single
3087 * BTF type descriptor, greatly reducing resulting size of BTF data.
3088 *
3089 * Compilation unit isolation and subsequent duplication of data is not the only
3090 * problem. The same type hierarchy (e.g., struct and all the type that struct
3091 * references) in different compilation units can be represented in BTF to
3092 * various degrees of completeness (or, rather, incompleteness) due to
3093 * struct/union forward declarations.
3094 *
3095 * Let's take a look at an example, that we'll use to better understand the
3096 * problem (and solution). Suppose we have two compilation units, each using
3097 * same `struct S`, but each of them having incomplete type information about
3098 * struct's fields:
3099 *
3100 * // CU #1:
3101 * struct S;
3102 * struct A {
3103 * int a;
3104 * struct A* self;
3105 * struct S* parent;
3106 * };
3107 * struct B;
3108 * struct S {
3109 * struct A* a_ptr;
3110 * struct B* b_ptr;
3111 * };
3112 *
3113 * // CU #2:
3114 * struct S;
3115 * struct A;
3116 * struct B {
3117 * int b;
3118 * struct B* self;
3119 * struct S* parent;
3120 * };
3121 * struct S {
3122 * struct A* a_ptr;
3123 * struct B* b_ptr;
3124 * };
3125 *
3126 * In case of CU #1, BTF data will know only that `struct B` exist (but no
3127 * more), but will know the complete type information about `struct A`. While
3128 * for CU #2, it will know full type information about `struct B`, but will
3129 * only know about forward declaration of `struct A` (in BTF terms, it will
3130 * have `BTF_KIND_FWD` type descriptor with name `B`).
3131 *
3132 * This compilation unit isolation means that it's possible that there is no
3133 * single CU with complete type information describing structs `S`, `A`, and
3134 * `B`. Also, we might get tons of duplicated and redundant type information.
3135 *
3136 * Additional complication we need to keep in mind comes from the fact that
3137 * types, in general, can form graphs containing cycles, not just DAGs.
3138 *
3139 * While algorithm does deduplication, it also merges and resolves type
3140 * information (unless disabled throught `struct btf_opts`), whenever possible.
3141 * E.g., in the example above with two compilation units having partial type
3142 * information for structs `A` and `B`, the output of algorithm will emit
3143 * a single copy of each BTF type that describes structs `A`, `B`, and `S`
3144 * (as well as type information for `int` and pointers), as if they were defined
3145 * in a single compilation unit as:
3146 *
3147 * struct A {
3148 * int a;
3149 * struct A* self;
3150 * struct S* parent;
3151 * };
3152 * struct B {
3153 * int b;
3154 * struct B* self;
3155 * struct S* parent;
3156 * };
3157 * struct S {
3158 * struct A* a_ptr;
3159 * struct B* b_ptr;
3160 * };
3161 *
3162 * Algorithm summary
3163 * =================
3164 *
3165 * Algorithm completes its work in 7 separate passes:
3166 *
3167 * 1. Strings deduplication.
3168 * 2. Primitive types deduplication (int, enum, fwd).
3169 * 3. Struct/union types deduplication.
3170 * 4. Resolve unambiguous forward declarations.
3171 * 5. Reference types deduplication (pointers, typedefs, arrays, funcs, func
3172 * protos, and const/volatile/restrict modifiers).
3173 * 6. Types compaction.
3174 * 7. Types remapping.
3175 *
3176 * Algorithm determines canonical type descriptor, which is a single
3177 * representative type for each truly unique type. This canonical type is the
3178 * one that will go into final deduplicated BTF type information. For
3179 * struct/unions, it is also the type that algorithm will merge additional type
3180 * information into (while resolving FWDs), as it discovers it from data in
3181 * other CUs. Each input BTF type eventually gets either mapped to itself, if
3182 * that type is canonical, or to some other type, if that type is equivalent
3183 * and was chosen as canonical representative. This mapping is stored in
3184 * `btf_dedup->map` array. This map is also used to record STRUCT/UNION that
3185 * FWD type got resolved to.
3186 *
3187 * To facilitate fast discovery of canonical types, we also maintain canonical
3188 * index (`btf_dedup->dedup_table`), which maps type descriptor's signature hash
3189 * (i.e., hashed kind, name, size, fields, etc) into a list of canonical types
3190 * that match that signature. With sufficiently good choice of type signature
3191 * hashing function, we can limit number of canonical types for each unique type
3192 * signature to a very small number, allowing to find canonical type for any
3193 * duplicated type very quickly.
3194 *
3195 * Struct/union deduplication is the most critical part and algorithm for
3196 * deduplicating structs/unions is described in greater details in comments for
3197 * `btf_dedup_is_equiv` function.
3198 */
3199int btf__dedup(struct btf *btf, const struct btf_dedup_opts *opts)
3200{
3201 struct btf_dedup *d;
3202 int err;
3203
3204 if (!OPTS_VALID(opts, btf_dedup_opts))
3205 return libbpf_err(-EINVAL);
3206
3207 d = btf_dedup_new(btf, opts);
3208 if (IS_ERR(d)) {
3209 pr_debug("btf_dedup_new failed: %ld", PTR_ERR(d));
3210 return libbpf_err(-EINVAL);
3211 }
3212
3213 if (btf_ensure_modifiable(btf)) {
3214 err = -ENOMEM;
3215 goto done;
3216 }
3217
3218 err = btf_dedup_prep(d);
3219 if (err) {
3220 pr_debug("btf_dedup_prep failed:%d\n", err);
3221 goto done;
3222 }
3223 err = btf_dedup_strings(d);
3224 if (err < 0) {
3225 pr_debug("btf_dedup_strings failed:%d\n", err);
3226 goto done;
3227 }
3228 err = btf_dedup_prim_types(d);
3229 if (err < 0) {
3230 pr_debug("btf_dedup_prim_types failed:%d\n", err);
3231 goto done;
3232 }
3233 err = btf_dedup_struct_types(d);
3234 if (err < 0) {
3235 pr_debug("btf_dedup_struct_types failed:%d\n", err);
3236 goto done;
3237 }
3238 err = btf_dedup_resolve_fwds(d);
3239 if (err < 0) {
3240 pr_debug("btf_dedup_resolve_fwds failed:%d\n", err);
3241 goto done;
3242 }
3243 err = btf_dedup_ref_types(d);
3244 if (err < 0) {
3245 pr_debug("btf_dedup_ref_types failed:%d\n", err);
3246 goto done;
3247 }
3248 err = btf_dedup_compact_types(d);
3249 if (err < 0) {
3250 pr_debug("btf_dedup_compact_types failed:%d\n", err);
3251 goto done;
3252 }
3253 err = btf_dedup_remap_types(d);
3254 if (err < 0) {
3255 pr_debug("btf_dedup_remap_types failed:%d\n", err);
3256 goto done;
3257 }
3258
3259done:
3260 btf_dedup_free(d);
3261 return libbpf_err(err);
3262}
3263
3264#define BTF_UNPROCESSED_ID ((__u32)-1)
3265#define BTF_IN_PROGRESS_ID ((__u32)-2)
3266
3267struct btf_dedup {
3268 /* .BTF section to be deduped in-place */
3269 struct btf *btf;
3270 /*
3271 * Optional .BTF.ext section. When provided, any strings referenced
3272 * from it will be taken into account when deduping strings
3273 */
3274 struct btf_ext *btf_ext;
3275 /*
3276 * This is a map from any type's signature hash to a list of possible
3277 * canonical representative type candidates. Hash collisions are
3278 * ignored, so even types of various kinds can share same list of
3279 * candidates, which is fine because we rely on subsequent
3280 * btf_xxx_equal() checks to authoritatively verify type equality.
3281 */
3282 struct hashmap *dedup_table;
3283 /* Canonical types map */
3284 __u32 *map;
3285 /* Hypothetical mapping, used during type graph equivalence checks */
3286 __u32 *hypot_map;
3287 __u32 *hypot_list;
3288 size_t hypot_cnt;
3289 size_t hypot_cap;
3290 /* Whether hypothetical mapping, if successful, would need to adjust
3291 * already canonicalized types (due to a new forward declaration to
3292 * concrete type resolution). In such case, during split BTF dedup
3293 * candidate type would still be considered as different, because base
3294 * BTF is considered to be immutable.
3295 */
3296 bool hypot_adjust_canon;
3297 /* Various option modifying behavior of algorithm */
3298 struct btf_dedup_opts opts;
3299 /* temporary strings deduplication state */
3300 struct strset *strs_set;
3301};
3302
3303static long hash_combine(long h, long value)
3304{
3305 return h * 31 + value;
3306}
3307
3308#define for_each_dedup_cand(d, node, hash) \
3309 hashmap__for_each_key_entry(d->dedup_table, node, hash)
3310
3311static int btf_dedup_table_add(struct btf_dedup *d, long hash, __u32 type_id)
3312{
3313 return hashmap__append(d->dedup_table, hash, type_id);
3314}
3315
3316static int btf_dedup_hypot_map_add(struct btf_dedup *d,
3317 __u32 from_id, __u32 to_id)
3318{
3319 if (d->hypot_cnt == d->hypot_cap) {
3320 __u32 *new_list;
3321
3322 d->hypot_cap += max((size_t)16, d->hypot_cap / 2);
3323 new_list = libbpf_reallocarray(d->hypot_list, d->hypot_cap, sizeof(__u32));
3324 if (!new_list)
3325 return -ENOMEM;
3326 d->hypot_list = new_list;
3327 }
3328 d->hypot_list[d->hypot_cnt++] = from_id;
3329 d->hypot_map[from_id] = to_id;
3330 return 0;
3331}
3332
3333static void btf_dedup_clear_hypot_map(struct btf_dedup *d)
3334{
3335 int i;
3336
3337 for (i = 0; i < d->hypot_cnt; i++)
3338 d->hypot_map[d->hypot_list[i]] = BTF_UNPROCESSED_ID;
3339 d->hypot_cnt = 0;
3340 d->hypot_adjust_canon = false;
3341}
3342
3343static void btf_dedup_free(struct btf_dedup *d)
3344{
3345 hashmap__free(d->dedup_table);
3346 d->dedup_table = NULL;
3347
3348 free(d->map);
3349 d->map = NULL;
3350
3351 free(d->hypot_map);
3352 d->hypot_map = NULL;
3353
3354 free(d->hypot_list);
3355 d->hypot_list = NULL;
3356
3357 free(d);
3358}
3359
3360static size_t btf_dedup_identity_hash_fn(long key, void *ctx)
3361{
3362 return key;
3363}
3364
3365static size_t btf_dedup_collision_hash_fn(long key, void *ctx)
3366{
3367 return 0;
3368}
3369
3370static bool btf_dedup_equal_fn(long k1, long k2, void *ctx)
3371{
3372 return k1 == k2;
3373}
3374
3375static struct btf_dedup *btf_dedup_new(struct btf *btf, const struct btf_dedup_opts *opts)
3376{
3377 struct btf_dedup *d = calloc(1, sizeof(struct btf_dedup));
3378 hashmap_hash_fn hash_fn = btf_dedup_identity_hash_fn;
3379 int i, err = 0, type_cnt;
3380
3381 if (!d)
3382 return ERR_PTR(-ENOMEM);
3383
3384 if (OPTS_GET(opts, force_collisions, false))
3385 hash_fn = btf_dedup_collision_hash_fn;
3386
3387 d->btf = btf;
3388 d->btf_ext = OPTS_GET(opts, btf_ext, NULL);
3389
3390 d->dedup_table = hashmap__new(hash_fn, btf_dedup_equal_fn, NULL);
3391 if (IS_ERR(d->dedup_table)) {
3392 err = PTR_ERR(d->dedup_table);
3393 d->dedup_table = NULL;
3394 goto done;
3395 }
3396
3397 type_cnt = btf__type_cnt(btf);
3398 d->map = malloc(sizeof(__u32) * type_cnt);
3399 if (!d->map) {
3400 err = -ENOMEM;
3401 goto done;
3402 }
3403 /* special BTF "void" type is made canonical immediately */
3404 d->map[0] = 0;
3405 for (i = 1; i < type_cnt; i++) {
3406 struct btf_type *t = btf_type_by_id(d->btf, i);
3407
3408 /* VAR and DATASEC are never deduped and are self-canonical */
3409 if (btf_is_var(t) || btf_is_datasec(t))
3410 d->map[i] = i;
3411 else
3412 d->map[i] = BTF_UNPROCESSED_ID;
3413 }
3414
3415 d->hypot_map = malloc(sizeof(__u32) * type_cnt);
3416 if (!d->hypot_map) {
3417 err = -ENOMEM;
3418 goto done;
3419 }
3420 for (i = 0; i < type_cnt; i++)
3421 d->hypot_map[i] = BTF_UNPROCESSED_ID;
3422
3423done:
3424 if (err) {
3425 btf_dedup_free(d);
3426 return ERR_PTR(err);
3427 }
3428
3429 return d;
3430}
3431
3432/*
3433 * Iterate over all possible places in .BTF and .BTF.ext that can reference
3434 * string and pass pointer to it to a provided callback `fn`.
3435 */
3436static int btf_for_each_str_off(struct btf_dedup *d, str_off_visit_fn fn, void *ctx)
3437{
3438 int i, r;
3439
3440 for (i = 0; i < d->btf->nr_types; i++) {
3441 struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
3442
3443 r = btf_type_visit_str_offs(t, fn, ctx);
3444 if (r)
3445 return r;
3446 }
3447
3448 if (!d->btf_ext)
3449 return 0;
3450
3451 r = btf_ext_visit_str_offs(d->btf_ext, fn, ctx);
3452 if (r)
3453 return r;
3454
3455 return 0;
3456}
3457
3458static int strs_dedup_remap_str_off(__u32 *str_off_ptr, void *ctx)
3459{
3460 struct btf_dedup *d = ctx;
3461 __u32 str_off = *str_off_ptr;
3462 const char *s;
3463 int off, err;
3464
3465 /* don't touch empty string or string in main BTF */
3466 if (str_off == 0 || str_off < d->btf->start_str_off)
3467 return 0;
3468
3469 s = btf__str_by_offset(d->btf, str_off);
3470 if (d->btf->base_btf) {
3471 err = btf__find_str(d->btf->base_btf, s);
3472 if (err >= 0) {
3473 *str_off_ptr = err;
3474 return 0;
3475 }
3476 if (err != -ENOENT)
3477 return err;
3478 }
3479
3480 off = strset__add_str(d->strs_set, s);
3481 if (off < 0)
3482 return off;
3483
3484 *str_off_ptr = d->btf->start_str_off + off;
3485 return 0;
3486}
3487
3488/*
3489 * Dedup string and filter out those that are not referenced from either .BTF
3490 * or .BTF.ext (if provided) sections.
3491 *
3492 * This is done by building index of all strings in BTF's string section,
3493 * then iterating over all entities that can reference strings (e.g., type
3494 * names, struct field names, .BTF.ext line info, etc) and marking corresponding
3495 * strings as used. After that all used strings are deduped and compacted into
3496 * sequential blob of memory and new offsets are calculated. Then all the string
3497 * references are iterated again and rewritten using new offsets.
3498 */
3499static int btf_dedup_strings(struct btf_dedup *d)
3500{
3501 int err;
3502
3503 if (d->btf->strs_deduped)
3504 return 0;
3505
3506 d->strs_set = strset__new(BTF_MAX_STR_OFFSET, NULL, 0);
3507 if (IS_ERR(d->strs_set)) {
3508 err = PTR_ERR(d->strs_set);
3509 goto err_out;
3510 }
3511
3512 if (!d->btf->base_btf) {
3513 /* insert empty string; we won't be looking it up during strings
3514 * dedup, but it's good to have it for generic BTF string lookups
3515 */
3516 err = strset__add_str(d->strs_set, "");
3517 if (err < 0)
3518 goto err_out;
3519 }
3520
3521 /* remap string offsets */
3522 err = btf_for_each_str_off(d, strs_dedup_remap_str_off, d);
3523 if (err)
3524 goto err_out;
3525
3526 /* replace BTF string data and hash with deduped ones */
3527 strset__free(d->btf->strs_set);
3528 d->btf->hdr->str_len = strset__data_size(d->strs_set);
3529 d->btf->strs_set = d->strs_set;
3530 d->strs_set = NULL;
3531 d->btf->strs_deduped = true;
3532 return 0;
3533
3534err_out:
3535 strset__free(d->strs_set);
3536 d->strs_set = NULL;
3537
3538 return err;
3539}
3540
3541static long btf_hash_common(struct btf_type *t)
3542{
3543 long h;
3544
3545 h = hash_combine(0, t->name_off);
3546 h = hash_combine(h, t->info);
3547 h = hash_combine(h, t->size);
3548 return h;
3549}
3550
3551static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
3552{
3553 return t1->name_off == t2->name_off &&
3554 t1->info == t2->info &&
3555 t1->size == t2->size;
3556}
3557
3558/* Calculate type signature hash of INT or TAG. */
3559static long btf_hash_int_decl_tag(struct btf_type *t)
3560{
3561 __u32 info = *(__u32 *)(t + 1);
3562 long h;
3563
3564 h = btf_hash_common(t);
3565 h = hash_combine(h, info);
3566 return h;
3567}
3568
3569/* Check structural equality of two INTs or TAGs. */
3570static bool btf_equal_int_tag(struct btf_type *t1, struct btf_type *t2)
3571{
3572 __u32 info1, info2;
3573
3574 if (!btf_equal_common(t1, t2))
3575 return false;
3576 info1 = *(__u32 *)(t1 + 1);
3577 info2 = *(__u32 *)(t2 + 1);
3578 return info1 == info2;
3579}
3580
3581/* Calculate type signature hash of ENUM/ENUM64. */
3582static long btf_hash_enum(struct btf_type *t)
3583{
3584 long h;
3585
3586 /* don't hash vlen, enum members and size to support enum fwd resolving */
3587 h = hash_combine(0, t->name_off);
3588 return h;
3589}
3590
3591static bool btf_equal_enum_members(struct btf_type *t1, struct btf_type *t2)
3592{
3593 const struct btf_enum *m1, *m2;
3594 __u16 vlen;
3595 int i;
3596
3597 vlen = btf_vlen(t1);
3598 m1 = btf_enum(t1);
3599 m2 = btf_enum(t2);
3600 for (i = 0; i < vlen; i++) {
3601 if (m1->name_off != m2->name_off || m1->val != m2->val)
3602 return false;
3603 m1++;
3604 m2++;
3605 }
3606 return true;
3607}
3608
3609static bool btf_equal_enum64_members(struct btf_type *t1, struct btf_type *t2)
3610{
3611 const struct btf_enum64 *m1, *m2;
3612 __u16 vlen;
3613 int i;
3614
3615 vlen = btf_vlen(t1);
3616 m1 = btf_enum64(t1);
3617 m2 = btf_enum64(t2);
3618 for (i = 0; i < vlen; i++) {
3619 if (m1->name_off != m2->name_off || m1->val_lo32 != m2->val_lo32 ||
3620 m1->val_hi32 != m2->val_hi32)
3621 return false;
3622 m1++;
3623 m2++;
3624 }
3625 return true;
3626}
3627
3628/* Check structural equality of two ENUMs or ENUM64s. */
3629static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
3630{
3631 if (!btf_equal_common(t1, t2))
3632 return false;
3633
3634 /* t1 & t2 kinds are identical because of btf_equal_common */
3635 if (btf_kind(t1) == BTF_KIND_ENUM)
3636 return btf_equal_enum_members(t1, t2);
3637 else
3638 return btf_equal_enum64_members(t1, t2);
3639}
3640
3641static inline bool btf_is_enum_fwd(struct btf_type *t)
3642{
3643 return btf_is_any_enum(t) && btf_vlen(t) == 0;
3644}
3645
3646static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
3647{
3648 if (!btf_is_enum_fwd(t1) && !btf_is_enum_fwd(t2))
3649 return btf_equal_enum(t1, t2);
3650 /* At this point either t1 or t2 or both are forward declarations, thus:
3651 * - skip comparing vlen because it is zero for forward declarations;
3652 * - skip comparing size to allow enum forward declarations
3653 * to be compatible with enum64 full declarations;
3654 * - skip comparing kind for the same reason.
3655 */
3656 return t1->name_off == t2->name_off &&
3657 btf_is_any_enum(t1) && btf_is_any_enum(t2);
3658}
3659
3660/*
3661 * Calculate type signature hash of STRUCT/UNION, ignoring referenced type IDs,
3662 * as referenced type IDs equivalence is established separately during type
3663 * graph equivalence check algorithm.
3664 */
3665static long btf_hash_struct(struct btf_type *t)
3666{
3667 const struct btf_member *member = btf_members(t);
3668 __u32 vlen = btf_vlen(t);
3669 long h = btf_hash_common(t);
3670 int i;
3671
3672 for (i = 0; i < vlen; i++) {
3673 h = hash_combine(h, member->name_off);
3674 h = hash_combine(h, member->offset);
3675 /* no hashing of referenced type ID, it can be unresolved yet */
3676 member++;
3677 }
3678 return h;
3679}
3680
3681/*
3682 * Check structural compatibility of two STRUCTs/UNIONs, ignoring referenced
3683 * type IDs. This check is performed during type graph equivalence check and
3684 * referenced types equivalence is checked separately.
3685 */
3686static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
3687{
3688 const struct btf_member *m1, *m2;
3689 __u16 vlen;
3690 int i;
3691
3692 if (!btf_equal_common(t1, t2))
3693 return false;
3694
3695 vlen = btf_vlen(t1);
3696 m1 = btf_members(t1);
3697 m2 = btf_members(t2);
3698 for (i = 0; i < vlen; i++) {
3699 if (m1->name_off != m2->name_off || m1->offset != m2->offset)
3700 return false;
3701 m1++;
3702 m2++;
3703 }
3704 return true;
3705}
3706
3707/*
3708 * Calculate type signature hash of ARRAY, including referenced type IDs,
3709 * under assumption that they were already resolved to canonical type IDs and
3710 * are not going to change.
3711 */
3712static long btf_hash_array(struct btf_type *t)
3713{
3714 const struct btf_array *info = btf_array(t);
3715 long h = btf_hash_common(t);
3716
3717 h = hash_combine(h, info->type);
3718 h = hash_combine(h, info->index_type);
3719 h = hash_combine(h, info->nelems);
3720 return h;
3721}
3722
3723/*
3724 * Check exact equality of two ARRAYs, taking into account referenced
3725 * type IDs, under assumption that they were already resolved to canonical
3726 * type IDs and are not going to change.
3727 * This function is called during reference types deduplication to compare
3728 * ARRAY to potential canonical representative.
3729 */
3730static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
3731{
3732 const struct btf_array *info1, *info2;
3733
3734 if (!btf_equal_common(t1, t2))
3735 return false;
3736
3737 info1 = btf_array(t1);
3738 info2 = btf_array(t2);
3739 return info1->type == info2->type &&
3740 info1->index_type == info2->index_type &&
3741 info1->nelems == info2->nelems;
3742}
3743
3744/*
3745 * Check structural compatibility of two ARRAYs, ignoring referenced type
3746 * IDs. This check is performed during type graph equivalence check and
3747 * referenced types equivalence is checked separately.
3748 */
3749static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
3750{
3751 if (!btf_equal_common(t1, t2))
3752 return false;
3753
3754 return btf_array(t1)->nelems == btf_array(t2)->nelems;
3755}
3756
3757/*
3758 * Calculate type signature hash of FUNC_PROTO, including referenced type IDs,
3759 * under assumption that they were already resolved to canonical type IDs and
3760 * are not going to change.
3761 */
3762static long btf_hash_fnproto(struct btf_type *t)
3763{
3764 const struct btf_param *member = btf_params(t);
3765 __u16 vlen = btf_vlen(t);
3766 long h = btf_hash_common(t);
3767 int i;
3768
3769 for (i = 0; i < vlen; i++) {
3770 h = hash_combine(h, member->name_off);
3771 h = hash_combine(h, member->type);
3772 member++;
3773 }
3774 return h;
3775}
3776
3777/*
3778 * Check exact equality of two FUNC_PROTOs, taking into account referenced
3779 * type IDs, under assumption that they were already resolved to canonical
3780 * type IDs and are not going to change.
3781 * This function is called during reference types deduplication to compare
3782 * FUNC_PROTO to potential canonical representative.
3783 */
3784static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
3785{
3786 const struct btf_param *m1, *m2;
3787 __u16 vlen;
3788 int i;
3789
3790 if (!btf_equal_common(t1, t2))
3791 return false;
3792
3793 vlen = btf_vlen(t1);
3794 m1 = btf_params(t1);
3795 m2 = btf_params(t2);
3796 for (i = 0; i < vlen; i++) {
3797 if (m1->name_off != m2->name_off || m1->type != m2->type)
3798 return false;
3799 m1++;
3800 m2++;
3801 }
3802 return true;
3803}
3804
3805/*
3806 * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
3807 * IDs. This check is performed during type graph equivalence check and
3808 * referenced types equivalence is checked separately.
3809 */
3810static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
3811{
3812 const struct btf_param *m1, *m2;
3813 __u16 vlen;
3814 int i;
3815
3816 /* skip return type ID */
3817 if (t1->name_off != t2->name_off || t1->info != t2->info)
3818 return false;
3819
3820 vlen = btf_vlen(t1);
3821 m1 = btf_params(t1);
3822 m2 = btf_params(t2);
3823 for (i = 0; i < vlen; i++) {
3824 if (m1->name_off != m2->name_off)
3825 return false;
3826 m1++;
3827 m2++;
3828 }
3829 return true;
3830}
3831
3832/* Prepare split BTF for deduplication by calculating hashes of base BTF's
3833 * types and initializing the rest of the state (canonical type mapping) for
3834 * the fixed base BTF part.
3835 */
3836static int btf_dedup_prep(struct btf_dedup *d)
3837{
3838 struct btf_type *t;
3839 int type_id;
3840 long h;
3841
3842 if (!d->btf->base_btf)
3843 return 0;
3844
3845 for (type_id = 1; type_id < d->btf->start_id; type_id++) {
3846 t = btf_type_by_id(d->btf, type_id);
3847
3848 /* all base BTF types are self-canonical by definition */
3849 d->map[type_id] = type_id;
3850
3851 switch (btf_kind(t)) {
3852 case BTF_KIND_VAR:
3853 case BTF_KIND_DATASEC:
3854 /* VAR and DATASEC are never hash/deduplicated */
3855 continue;
3856 case BTF_KIND_CONST:
3857 case BTF_KIND_VOLATILE:
3858 case BTF_KIND_RESTRICT:
3859 case BTF_KIND_PTR:
3860 case BTF_KIND_FWD:
3861 case BTF_KIND_TYPEDEF:
3862 case BTF_KIND_FUNC:
3863 case BTF_KIND_FLOAT:
3864 case BTF_KIND_TYPE_TAG:
3865 h = btf_hash_common(t);
3866 break;
3867 case BTF_KIND_INT:
3868 case BTF_KIND_DECL_TAG:
3869 h = btf_hash_int_decl_tag(t);
3870 break;
3871 case BTF_KIND_ENUM:
3872 case BTF_KIND_ENUM64:
3873 h = btf_hash_enum(t);
3874 break;
3875 case BTF_KIND_STRUCT:
3876 case BTF_KIND_UNION:
3877 h = btf_hash_struct(t);
3878 break;
3879 case BTF_KIND_ARRAY:
3880 h = btf_hash_array(t);
3881 break;
3882 case BTF_KIND_FUNC_PROTO:
3883 h = btf_hash_fnproto(t);
3884 break;
3885 default:
3886 pr_debug("unknown kind %d for type [%d]\n", btf_kind(t), type_id);
3887 return -EINVAL;
3888 }
3889 if (btf_dedup_table_add(d, h, type_id))
3890 return -ENOMEM;
3891 }
3892
3893 return 0;
3894}
3895
3896/*
3897 * Deduplicate primitive types, that can't reference other types, by calculating
3898 * their type signature hash and comparing them with any possible canonical
3899 * candidate. If no canonical candidate matches, type itself is marked as
3900 * canonical and is added into `btf_dedup->dedup_table` as another candidate.
3901 */
3902static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
3903{
3904 struct btf_type *t = btf_type_by_id(d->btf, type_id);
3905 struct hashmap_entry *hash_entry;
3906 struct btf_type *cand;
3907 /* if we don't find equivalent type, then we are canonical */
3908 __u32 new_id = type_id;
3909 __u32 cand_id;
3910 long h;
3911
3912 switch (btf_kind(t)) {
3913 case BTF_KIND_CONST:
3914 case BTF_KIND_VOLATILE:
3915 case BTF_KIND_RESTRICT:
3916 case BTF_KIND_PTR:
3917 case BTF_KIND_TYPEDEF:
3918 case BTF_KIND_ARRAY:
3919 case BTF_KIND_STRUCT:
3920 case BTF_KIND_UNION:
3921 case BTF_KIND_FUNC:
3922 case BTF_KIND_FUNC_PROTO:
3923 case BTF_KIND_VAR:
3924 case BTF_KIND_DATASEC:
3925 case BTF_KIND_DECL_TAG:
3926 case BTF_KIND_TYPE_TAG:
3927 return 0;
3928
3929 case BTF_KIND_INT:
3930 h = btf_hash_int_decl_tag(t);
3931 for_each_dedup_cand(d, hash_entry, h) {
3932 cand_id = hash_entry->value;
3933 cand = btf_type_by_id(d->btf, cand_id);
3934 if (btf_equal_int_tag(t, cand)) {
3935 new_id = cand_id;
3936 break;
3937 }
3938 }
3939 break;
3940
3941 case BTF_KIND_ENUM:
3942 case BTF_KIND_ENUM64:
3943 h = btf_hash_enum(t);
3944 for_each_dedup_cand(d, hash_entry, h) {
3945 cand_id = hash_entry->value;
3946 cand = btf_type_by_id(d->btf, cand_id);
3947 if (btf_equal_enum(t, cand)) {
3948 new_id = cand_id;
3949 break;
3950 }
3951 if (btf_compat_enum(t, cand)) {
3952 if (btf_is_enum_fwd(t)) {
3953 /* resolve fwd to full enum */
3954 new_id = cand_id;
3955 break;
3956 }
3957 /* resolve canonical enum fwd to full enum */
3958 d->map[cand_id] = type_id;
3959 }
3960 }
3961 break;
3962
3963 case BTF_KIND_FWD:
3964 case BTF_KIND_FLOAT:
3965 h = btf_hash_common(t);
3966 for_each_dedup_cand(d, hash_entry, h) {
3967 cand_id = hash_entry->value;
3968 cand = btf_type_by_id(d->btf, cand_id);
3969 if (btf_equal_common(t, cand)) {
3970 new_id = cand_id;
3971 break;
3972 }
3973 }
3974 break;
3975
3976 default:
3977 return -EINVAL;
3978 }
3979
3980 d->map[type_id] = new_id;
3981 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
3982 return -ENOMEM;
3983
3984 return 0;
3985}
3986
3987static int btf_dedup_prim_types(struct btf_dedup *d)
3988{
3989 int i, err;
3990
3991 for (i = 0; i < d->btf->nr_types; i++) {
3992 err = btf_dedup_prim_type(d, d->btf->start_id + i);
3993 if (err)
3994 return err;
3995 }
3996 return 0;
3997}
3998
3999/*
4000 * Check whether type is already mapped into canonical one (could be to itself).
4001 */
4002static inline bool is_type_mapped(struct btf_dedup *d, uint32_t type_id)
4003{
4004 return d->map[type_id] <= BTF_MAX_NR_TYPES;
4005}
4006
4007/*
4008 * Resolve type ID into its canonical type ID, if any; otherwise return original
4009 * type ID. If type is FWD and is resolved into STRUCT/UNION already, follow
4010 * STRUCT/UNION link and resolve it into canonical type ID as well.
4011 */
4012static inline __u32 resolve_type_id(struct btf_dedup *d, __u32 type_id)
4013{
4014 while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
4015 type_id = d->map[type_id];
4016 return type_id;
4017}
4018
4019/*
4020 * Resolve FWD to underlying STRUCT/UNION, if any; otherwise return original
4021 * type ID.
4022 */
4023static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
4024{
4025 __u32 orig_type_id = type_id;
4026
4027 if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
4028 return type_id;
4029
4030 while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
4031 type_id = d->map[type_id];
4032
4033 if (!btf_is_fwd(btf__type_by_id(d->btf, type_id)))
4034 return type_id;
4035
4036 return orig_type_id;
4037}
4038
4039
4040static inline __u16 btf_fwd_kind(struct btf_type *t)
4041{
4042 return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
4043}
4044
4045/* Check if given two types are identical ARRAY definitions */
4046static bool btf_dedup_identical_arrays(struct btf_dedup *d, __u32 id1, __u32 id2)
4047{
4048 struct btf_type *t1, *t2;
4049
4050 t1 = btf_type_by_id(d->btf, id1);
4051 t2 = btf_type_by_id(d->btf, id2);
4052 if (!btf_is_array(t1) || !btf_is_array(t2))
4053 return false;
4054
4055 return btf_equal_array(t1, t2);
4056}
4057
4058/* Check if given two types are identical STRUCT/UNION definitions */
4059static bool btf_dedup_identical_structs(struct btf_dedup *d, __u32 id1, __u32 id2)
4060{
4061 const struct btf_member *m1, *m2;
4062 struct btf_type *t1, *t2;
4063 int n, i;
4064
4065 t1 = btf_type_by_id(d->btf, id1);
4066 t2 = btf_type_by_id(d->btf, id2);
4067
4068 if (!btf_is_composite(t1) || btf_kind(t1) != btf_kind(t2))
4069 return false;
4070
4071 if (!btf_shallow_equal_struct(t1, t2))
4072 return false;
4073
4074 m1 = btf_members(t1);
4075 m2 = btf_members(t2);
4076 for (i = 0, n = btf_vlen(t1); i < n; i++, m1++, m2++) {
4077 if (m1->type != m2->type &&
4078 !btf_dedup_identical_arrays(d, m1->type, m2->type) &&
4079 !btf_dedup_identical_structs(d, m1->type, m2->type))
4080 return false;
4081 }
4082 return true;
4083}
4084
4085/*
4086 * Check equivalence of BTF type graph formed by candidate struct/union (we'll
4087 * call it "candidate graph" in this description for brevity) to a type graph
4088 * formed by (potential) canonical struct/union ("canonical graph" for brevity
4089 * here, though keep in mind that not all types in canonical graph are
4090 * necessarily canonical representatives themselves, some of them might be
4091 * duplicates or its uniqueness might not have been established yet).
4092 * Returns:
4093 * - >0, if type graphs are equivalent;
4094 * - 0, if not equivalent;
4095 * - <0, on error.
4096 *
4097 * Algorithm performs side-by-side DFS traversal of both type graphs and checks
4098 * equivalence of BTF types at each step. If at any point BTF types in candidate
4099 * and canonical graphs are not compatible structurally, whole graphs are
4100 * incompatible. If types are structurally equivalent (i.e., all information
4101 * except referenced type IDs is exactly the same), a mapping from `canon_id` to
4102 * a `cand_id` is recored in hypothetical mapping (`btf_dedup->hypot_map`).
4103 * If a type references other types, then those referenced types are checked
4104 * for equivalence recursively.
4105 *
4106 * During DFS traversal, if we find that for current `canon_id` type we
4107 * already have some mapping in hypothetical map, we check for two possible
4108 * situations:
4109 * - `canon_id` is mapped to exactly the same type as `cand_id`. This will
4110 * happen when type graphs have cycles. In this case we assume those two
4111 * types are equivalent.
4112 * - `canon_id` is mapped to different type. This is contradiction in our
4113 * hypothetical mapping, because same graph in canonical graph corresponds
4114 * to two different types in candidate graph, which for equivalent type
4115 * graphs shouldn't happen. This condition terminates equivalence check
4116 * with negative result.
4117 *
4118 * If type graphs traversal exhausts types to check and find no contradiction,
4119 * then type graphs are equivalent.
4120 *
4121 * When checking types for equivalence, there is one special case: FWD types.
4122 * If FWD type resolution is allowed and one of the types (either from canonical
4123 * or candidate graph) is FWD and other is STRUCT/UNION (depending on FWD's kind
4124 * flag) and their names match, hypothetical mapping is updated to point from
4125 * FWD to STRUCT/UNION. If graphs will be determined as equivalent successfully,
4126 * this mapping will be used to record FWD -> STRUCT/UNION mapping permanently.
4127 *
4128 * Technically, this could lead to incorrect FWD to STRUCT/UNION resolution,
4129 * if there are two exactly named (or anonymous) structs/unions that are
4130 * compatible structurally, one of which has FWD field, while other is concrete
4131 * STRUCT/UNION, but according to C sources they are different structs/unions
4132 * that are referencing different types with the same name. This is extremely
4133 * unlikely to happen, but btf_dedup API allows to disable FWD resolution if
4134 * this logic is causing problems.
4135 *
4136 * Doing FWD resolution means that both candidate and/or canonical graphs can
4137 * consists of portions of the graph that come from multiple compilation units.
4138 * This is due to the fact that types within single compilation unit are always
4139 * deduplicated and FWDs are already resolved, if referenced struct/union
4140 * definiton is available. So, if we had unresolved FWD and found corresponding
4141 * STRUCT/UNION, they will be from different compilation units. This
4142 * consequently means that when we "link" FWD to corresponding STRUCT/UNION,
4143 * type graph will likely have at least two different BTF types that describe
4144 * same type (e.g., most probably there will be two different BTF types for the
4145 * same 'int' primitive type) and could even have "overlapping" parts of type
4146 * graph that describe same subset of types.
4147 *
4148 * This in turn means that our assumption that each type in canonical graph
4149 * must correspond to exactly one type in candidate graph might not hold
4150 * anymore and will make it harder to detect contradictions using hypothetical
4151 * map. To handle this problem, we allow to follow FWD -> STRUCT/UNION
4152 * resolution only in canonical graph. FWDs in candidate graphs are never
4153 * resolved. To see why it's OK, let's check all possible situations w.r.t. FWDs
4154 * that can occur:
4155 * - Both types in canonical and candidate graphs are FWDs. If they are
4156 * structurally equivalent, then they can either be both resolved to the
4157 * same STRUCT/UNION or not resolved at all. In both cases they are
4158 * equivalent and there is no need to resolve FWD on candidate side.
4159 * - Both types in canonical and candidate graphs are concrete STRUCT/UNION,
4160 * so nothing to resolve as well, algorithm will check equivalence anyway.
4161 * - Type in canonical graph is FWD, while type in candidate is concrete
4162 * STRUCT/UNION. In this case candidate graph comes from single compilation
4163 * unit, so there is exactly one BTF type for each unique C type. After
4164 * resolving FWD into STRUCT/UNION, there might be more than one BTF type
4165 * in canonical graph mapping to single BTF type in candidate graph, but
4166 * because hypothetical mapping maps from canonical to candidate types, it's
4167 * alright, and we still maintain the property of having single `canon_id`
4168 * mapping to single `cand_id` (there could be two different `canon_id`
4169 * mapped to the same `cand_id`, but it's not contradictory).
4170 * - Type in canonical graph is concrete STRUCT/UNION, while type in candidate
4171 * graph is FWD. In this case we are just going to check compatibility of
4172 * STRUCT/UNION and corresponding FWD, and if they are compatible, we'll
4173 * assume that whatever STRUCT/UNION FWD resolves to must be equivalent to
4174 * a concrete STRUCT/UNION from canonical graph. If the rest of type graphs
4175 * turn out equivalent, we'll re-resolve FWD to concrete STRUCT/UNION from
4176 * canonical graph.
4177 */
4178static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
4179 __u32 canon_id)
4180{
4181 struct btf_type *cand_type;
4182 struct btf_type *canon_type;
4183 __u32 hypot_type_id;
4184 __u16 cand_kind;
4185 __u16 canon_kind;
4186 int i, eq;
4187
4188 /* if both resolve to the same canonical, they must be equivalent */
4189 if (resolve_type_id(d, cand_id) == resolve_type_id(d, canon_id))
4190 return 1;
4191
4192 canon_id = resolve_fwd_id(d, canon_id);
4193
4194 hypot_type_id = d->hypot_map[canon_id];
4195 if (hypot_type_id <= BTF_MAX_NR_TYPES) {
4196 if (hypot_type_id == cand_id)
4197 return 1;
4198 /* In some cases compiler will generate different DWARF types
4199 * for *identical* array type definitions and use them for
4200 * different fields within the *same* struct. This breaks type
4201 * equivalence check, which makes an assumption that candidate
4202 * types sub-graph has a consistent and deduped-by-compiler
4203 * types within a single CU. So work around that by explicitly
4204 * allowing identical array types here.
4205 */
4206 if (btf_dedup_identical_arrays(d, hypot_type_id, cand_id))
4207 return 1;
4208 /* It turns out that similar situation can happen with
4209 * struct/union sometimes, sigh... Handle the case where
4210 * structs/unions are exactly the same, down to the referenced
4211 * type IDs. Anything more complicated (e.g., if referenced
4212 * types are different, but equivalent) is *way more*
4213 * complicated and requires a many-to-many equivalence mapping.
4214 */
4215 if (btf_dedup_identical_structs(d, hypot_type_id, cand_id))
4216 return 1;
4217 return 0;
4218 }
4219
4220 if (btf_dedup_hypot_map_add(d, canon_id, cand_id))
4221 return -ENOMEM;
4222
4223 cand_type = btf_type_by_id(d->btf, cand_id);
4224 canon_type = btf_type_by_id(d->btf, canon_id);
4225 cand_kind = btf_kind(cand_type);
4226 canon_kind = btf_kind(canon_type);
4227
4228 if (cand_type->name_off != canon_type->name_off)
4229 return 0;
4230
4231 /* FWD <--> STRUCT/UNION equivalence check, if enabled */
4232 if ((cand_kind == BTF_KIND_FWD || canon_kind == BTF_KIND_FWD)
4233 && cand_kind != canon_kind) {
4234 __u16 real_kind;
4235 __u16 fwd_kind;
4236
4237 if (cand_kind == BTF_KIND_FWD) {
4238 real_kind = canon_kind;
4239 fwd_kind = btf_fwd_kind(cand_type);
4240 } else {
4241 real_kind = cand_kind;
4242 fwd_kind = btf_fwd_kind(canon_type);
4243 /* we'd need to resolve base FWD to STRUCT/UNION */
4244 if (fwd_kind == real_kind && canon_id < d->btf->start_id)
4245 d->hypot_adjust_canon = true;
4246 }
4247 return fwd_kind == real_kind;
4248 }
4249
4250 if (cand_kind != canon_kind)
4251 return 0;
4252
4253 switch (cand_kind) {
4254 case BTF_KIND_INT:
4255 return btf_equal_int_tag(cand_type, canon_type);
4256
4257 case BTF_KIND_ENUM:
4258 case BTF_KIND_ENUM64:
4259 return btf_compat_enum(cand_type, canon_type);
4260
4261 case BTF_KIND_FWD:
4262 case BTF_KIND_FLOAT:
4263 return btf_equal_common(cand_type, canon_type);
4264
4265 case BTF_KIND_CONST:
4266 case BTF_KIND_VOLATILE:
4267 case BTF_KIND_RESTRICT:
4268 case BTF_KIND_PTR:
4269 case BTF_KIND_TYPEDEF:
4270 case BTF_KIND_FUNC:
4271 case BTF_KIND_TYPE_TAG:
4272 if (cand_type->info != canon_type->info)
4273 return 0;
4274 return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
4275
4276 case BTF_KIND_ARRAY: {
4277 const struct btf_array *cand_arr, *canon_arr;
4278
4279 if (!btf_compat_array(cand_type, canon_type))
4280 return 0;
4281 cand_arr = btf_array(cand_type);
4282 canon_arr = btf_array(canon_type);
4283 eq = btf_dedup_is_equiv(d, cand_arr->index_type, canon_arr->index_type);
4284 if (eq <= 0)
4285 return eq;
4286 return btf_dedup_is_equiv(d, cand_arr->type, canon_arr->type);
4287 }
4288
4289 case BTF_KIND_STRUCT:
4290 case BTF_KIND_UNION: {
4291 const struct btf_member *cand_m, *canon_m;
4292 __u16 vlen;
4293
4294 if (!btf_shallow_equal_struct(cand_type, canon_type))
4295 return 0;
4296 vlen = btf_vlen(cand_type);
4297 cand_m = btf_members(cand_type);
4298 canon_m = btf_members(canon_type);
4299 for (i = 0; i < vlen; i++) {
4300 eq = btf_dedup_is_equiv(d, cand_m->type, canon_m->type);
4301 if (eq <= 0)
4302 return eq;
4303 cand_m++;
4304 canon_m++;
4305 }
4306
4307 return 1;
4308 }
4309
4310 case BTF_KIND_FUNC_PROTO: {
4311 const struct btf_param *cand_p, *canon_p;
4312 __u16 vlen;
4313
4314 if (!btf_compat_fnproto(cand_type, canon_type))
4315 return 0;
4316 eq = btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
4317 if (eq <= 0)
4318 return eq;
4319 vlen = btf_vlen(cand_type);
4320 cand_p = btf_params(cand_type);
4321 canon_p = btf_params(canon_type);
4322 for (i = 0; i < vlen; i++) {
4323 eq = btf_dedup_is_equiv(d, cand_p->type, canon_p->type);
4324 if (eq <= 0)
4325 return eq;
4326 cand_p++;
4327 canon_p++;
4328 }
4329 return 1;
4330 }
4331
4332 default:
4333 return -EINVAL;
4334 }
4335 return 0;
4336}
4337
4338/*
4339 * Use hypothetical mapping, produced by successful type graph equivalence
4340 * check, to augment existing struct/union canonical mapping, where possible.
4341 *
4342 * If BTF_KIND_FWD resolution is allowed, this mapping is also used to record
4343 * FWD -> STRUCT/UNION correspondence as well. FWD resolution is bidirectional:
4344 * it doesn't matter if FWD type was part of canonical graph or candidate one,
4345 * we are recording the mapping anyway. As opposed to carefulness required
4346 * for struct/union correspondence mapping (described below), for FWD resolution
4347 * it's not important, as by the time that FWD type (reference type) will be
4348 * deduplicated all structs/unions will be deduped already anyway.
4349 *
4350 * Recording STRUCT/UNION mapping is purely a performance optimization and is
4351 * not required for correctness. It needs to be done carefully to ensure that
4352 * struct/union from candidate's type graph is not mapped into corresponding
4353 * struct/union from canonical type graph that itself hasn't been resolved into
4354 * canonical representative. The only guarantee we have is that canonical
4355 * struct/union was determined as canonical and that won't change. But any
4356 * types referenced through that struct/union fields could have been not yet
4357 * resolved, so in case like that it's too early to establish any kind of
4358 * correspondence between structs/unions.
4359 *
4360 * No canonical correspondence is derived for primitive types (they are already
4361 * deduplicated completely already anyway) or reference types (they rely on
4362 * stability of struct/union canonical relationship for equivalence checks).
4363 */
4364static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
4365{
4366 __u32 canon_type_id, targ_type_id;
4367 __u16 t_kind, c_kind;
4368 __u32 t_id, c_id;
4369 int i;
4370
4371 for (i = 0; i < d->hypot_cnt; i++) {
4372 canon_type_id = d->hypot_list[i];
4373 targ_type_id = d->hypot_map[canon_type_id];
4374 t_id = resolve_type_id(d, targ_type_id);
4375 c_id = resolve_type_id(d, canon_type_id);
4376 t_kind = btf_kind(btf__type_by_id(d->btf, t_id));
4377 c_kind = btf_kind(btf__type_by_id(d->btf, c_id));
4378 /*
4379 * Resolve FWD into STRUCT/UNION.
4380 * It's ok to resolve FWD into STRUCT/UNION that's not yet
4381 * mapped to canonical representative (as opposed to
4382 * STRUCT/UNION <--> STRUCT/UNION mapping logic below), because
4383 * eventually that struct is going to be mapped and all resolved
4384 * FWDs will automatically resolve to correct canonical
4385 * representative. This will happen before ref type deduping,
4386 * which critically depends on stability of these mapping. This
4387 * stability is not a requirement for STRUCT/UNION equivalence
4388 * checks, though.
4389 */
4390
4391 /* if it's the split BTF case, we still need to point base FWD
4392 * to STRUCT/UNION in a split BTF, because FWDs from split BTF
4393 * will be resolved against base FWD. If we don't point base
4394 * canonical FWD to the resolved STRUCT/UNION, then all the
4395 * FWDs in split BTF won't be correctly resolved to a proper
4396 * STRUCT/UNION.
4397 */
4398 if (t_kind != BTF_KIND_FWD && c_kind == BTF_KIND_FWD)
4399 d->map[c_id] = t_id;
4400
4401 /* if graph equivalence determined that we'd need to adjust
4402 * base canonical types, then we need to only point base FWDs
4403 * to STRUCTs/UNIONs and do no more modifications. For all
4404 * other purposes the type graphs were not equivalent.
4405 */
4406 if (d->hypot_adjust_canon)
4407 continue;
4408
4409 if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD)
4410 d->map[t_id] = c_id;
4411
4412 if ((t_kind == BTF_KIND_STRUCT || t_kind == BTF_KIND_UNION) &&
4413 c_kind != BTF_KIND_FWD &&
4414 is_type_mapped(d, c_id) &&
4415 !is_type_mapped(d, t_id)) {
4416 /*
4417 * as a perf optimization, we can map struct/union
4418 * that's part of type graph we just verified for
4419 * equivalence. We can do that for struct/union that has
4420 * canonical representative only, though.
4421 */
4422 d->map[t_id] = c_id;
4423 }
4424 }
4425}
4426
4427/*
4428 * Deduplicate struct/union types.
4429 *
4430 * For each struct/union type its type signature hash is calculated, taking
4431 * into account type's name, size, number, order and names of fields, but
4432 * ignoring type ID's referenced from fields, because they might not be deduped
4433 * completely until after reference types deduplication phase. This type hash
4434 * is used to iterate over all potential canonical types, sharing same hash.
4435 * For each canonical candidate we check whether type graphs that they form
4436 * (through referenced types in fields and so on) are equivalent using algorithm
4437 * implemented in `btf_dedup_is_equiv`. If such equivalence is found and
4438 * BTF_KIND_FWD resolution is allowed, then hypothetical mapping
4439 * (btf_dedup->hypot_map) produced by aforementioned type graph equivalence
4440 * algorithm is used to record FWD -> STRUCT/UNION mapping. It's also used to
4441 * potentially map other structs/unions to their canonical representatives,
4442 * if such relationship hasn't yet been established. This speeds up algorithm
4443 * by eliminating some of the duplicate work.
4444 *
4445 * If no matching canonical representative was found, struct/union is marked
4446 * as canonical for itself and is added into btf_dedup->dedup_table hash map
4447 * for further look ups.
4448 */
4449static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
4450{
4451 struct btf_type *cand_type, *t;
4452 struct hashmap_entry *hash_entry;
4453 /* if we don't find equivalent type, then we are canonical */
4454 __u32 new_id = type_id;
4455 __u16 kind;
4456 long h;
4457
4458 /* already deduped or is in process of deduping (loop detected) */
4459 if (d->map[type_id] <= BTF_MAX_NR_TYPES)
4460 return 0;
4461
4462 t = btf_type_by_id(d->btf, type_id);
4463 kind = btf_kind(t);
4464
4465 if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
4466 return 0;
4467
4468 h = btf_hash_struct(t);
4469 for_each_dedup_cand(d, hash_entry, h) {
4470 __u32 cand_id = hash_entry->value;
4471 int eq;
4472
4473 /*
4474 * Even though btf_dedup_is_equiv() checks for
4475 * btf_shallow_equal_struct() internally when checking two
4476 * structs (unions) for equivalence, we need to guard here
4477 * from picking matching FWD type as a dedup candidate.
4478 * This can happen due to hash collision. In such case just
4479 * relying on btf_dedup_is_equiv() would lead to potentially
4480 * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because
4481 * FWD and compatible STRUCT/UNION are considered equivalent.
4482 */
4483 cand_type = btf_type_by_id(d->btf, cand_id);
4484 if (!btf_shallow_equal_struct(t, cand_type))
4485 continue;
4486
4487 btf_dedup_clear_hypot_map(d);
4488 eq = btf_dedup_is_equiv(d, type_id, cand_id);
4489 if (eq < 0)
4490 return eq;
4491 if (!eq)
4492 continue;
4493 btf_dedup_merge_hypot_map(d);
4494 if (d->hypot_adjust_canon) /* not really equivalent */
4495 continue;
4496 new_id = cand_id;
4497 break;
4498 }
4499
4500 d->map[type_id] = new_id;
4501 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
4502 return -ENOMEM;
4503
4504 return 0;
4505}
4506
4507static int btf_dedup_struct_types(struct btf_dedup *d)
4508{
4509 int i, err;
4510
4511 for (i = 0; i < d->btf->nr_types; i++) {
4512 err = btf_dedup_struct_type(d, d->btf->start_id + i);
4513 if (err)
4514 return err;
4515 }
4516 return 0;
4517}
4518
4519/*
4520 * Deduplicate reference type.
4521 *
4522 * Once all primitive and struct/union types got deduplicated, we can easily
4523 * deduplicate all other (reference) BTF types. This is done in two steps:
4524 *
4525 * 1. Resolve all referenced type IDs into their canonical type IDs. This
4526 * resolution can be done either immediately for primitive or struct/union types
4527 * (because they were deduped in previous two phases) or recursively for
4528 * reference types. Recursion will always terminate at either primitive or
4529 * struct/union type, at which point we can "unwind" chain of reference types
4530 * one by one. There is no danger of encountering cycles because in C type
4531 * system the only way to form type cycle is through struct/union, so any chain
4532 * of reference types, even those taking part in a type cycle, will inevitably
4533 * reach struct/union at some point.
4534 *
4535 * 2. Once all referenced type IDs are resolved into canonical ones, BTF type
4536 * becomes "stable", in the sense that no further deduplication will cause
4537 * any changes to it. With that, it's now possible to calculate type's signature
4538 * hash (this time taking into account referenced type IDs) and loop over all
4539 * potential canonical representatives. If no match was found, current type
4540 * will become canonical representative of itself and will be added into
4541 * btf_dedup->dedup_table as another possible canonical representative.
4542 */
4543static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
4544{
4545 struct hashmap_entry *hash_entry;
4546 __u32 new_id = type_id, cand_id;
4547 struct btf_type *t, *cand;
4548 /* if we don't find equivalent type, then we are representative type */
4549 int ref_type_id;
4550 long h;
4551
4552 if (d->map[type_id] == BTF_IN_PROGRESS_ID)
4553 return -ELOOP;
4554 if (d->map[type_id] <= BTF_MAX_NR_TYPES)
4555 return resolve_type_id(d, type_id);
4556
4557 t = btf_type_by_id(d->btf, type_id);
4558 d->map[type_id] = BTF_IN_PROGRESS_ID;
4559
4560 switch (btf_kind(t)) {
4561 case BTF_KIND_CONST:
4562 case BTF_KIND_VOLATILE:
4563 case BTF_KIND_RESTRICT:
4564 case BTF_KIND_PTR:
4565 case BTF_KIND_TYPEDEF:
4566 case BTF_KIND_FUNC:
4567 case BTF_KIND_TYPE_TAG:
4568 ref_type_id = btf_dedup_ref_type(d, t->type);
4569 if (ref_type_id < 0)
4570 return ref_type_id;
4571 t->type = ref_type_id;
4572
4573 h = btf_hash_common(t);
4574 for_each_dedup_cand(d, hash_entry, h) {
4575 cand_id = hash_entry->value;
4576 cand = btf_type_by_id(d->btf, cand_id);
4577 if (btf_equal_common(t, cand)) {
4578 new_id = cand_id;
4579 break;
4580 }
4581 }
4582 break;
4583
4584 case BTF_KIND_DECL_TAG:
4585 ref_type_id = btf_dedup_ref_type(d, t->type);
4586 if (ref_type_id < 0)
4587 return ref_type_id;
4588 t->type = ref_type_id;
4589
4590 h = btf_hash_int_decl_tag(t);
4591 for_each_dedup_cand(d, hash_entry, h) {
4592 cand_id = hash_entry->value;
4593 cand = btf_type_by_id(d->btf, cand_id);
4594 if (btf_equal_int_tag(t, cand)) {
4595 new_id = cand_id;
4596 break;
4597 }
4598 }
4599 break;
4600
4601 case BTF_KIND_ARRAY: {
4602 struct btf_array *info = btf_array(t);
4603
4604 ref_type_id = btf_dedup_ref_type(d, info->type);
4605 if (ref_type_id < 0)
4606 return ref_type_id;
4607 info->type = ref_type_id;
4608
4609 ref_type_id = btf_dedup_ref_type(d, info->index_type);
4610 if (ref_type_id < 0)
4611 return ref_type_id;
4612 info->index_type = ref_type_id;
4613
4614 h = btf_hash_array(t);
4615 for_each_dedup_cand(d, hash_entry, h) {
4616 cand_id = hash_entry->value;
4617 cand = btf_type_by_id(d->btf, cand_id);
4618 if (btf_equal_array(t, cand)) {
4619 new_id = cand_id;
4620 break;
4621 }
4622 }
4623 break;
4624 }
4625
4626 case BTF_KIND_FUNC_PROTO: {
4627 struct btf_param *param;
4628 __u16 vlen;
4629 int i;
4630
4631 ref_type_id = btf_dedup_ref_type(d, t->type);
4632 if (ref_type_id < 0)
4633 return ref_type_id;
4634 t->type = ref_type_id;
4635
4636 vlen = btf_vlen(t);
4637 param = btf_params(t);
4638 for (i = 0; i < vlen; i++) {
4639 ref_type_id = btf_dedup_ref_type(d, param->type);
4640 if (ref_type_id < 0)
4641 return ref_type_id;
4642 param->type = ref_type_id;
4643 param++;
4644 }
4645
4646 h = btf_hash_fnproto(t);
4647 for_each_dedup_cand(d, hash_entry, h) {
4648 cand_id = hash_entry->value;
4649 cand = btf_type_by_id(d->btf, cand_id);
4650 if (btf_equal_fnproto(t, cand)) {
4651 new_id = cand_id;
4652 break;
4653 }
4654 }
4655 break;
4656 }
4657
4658 default:
4659 return -EINVAL;
4660 }
4661
4662 d->map[type_id] = new_id;
4663 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
4664 return -ENOMEM;
4665
4666 return new_id;
4667}
4668
4669static int btf_dedup_ref_types(struct btf_dedup *d)
4670{
4671 int i, err;
4672
4673 for (i = 0; i < d->btf->nr_types; i++) {
4674 err = btf_dedup_ref_type(d, d->btf->start_id + i);
4675 if (err < 0)
4676 return err;
4677 }
4678 /* we won't need d->dedup_table anymore */
4679 hashmap__free(d->dedup_table);
4680 d->dedup_table = NULL;
4681 return 0;
4682}
4683
4684/*
4685 * Collect a map from type names to type ids for all canonical structs
4686 * and unions. If the same name is shared by several canonical types
4687 * use a special value 0 to indicate this fact.
4688 */
4689static int btf_dedup_fill_unique_names_map(struct btf_dedup *d, struct hashmap *names_map)
4690{
4691 __u32 nr_types = btf__type_cnt(d->btf);
4692 struct btf_type *t;
4693 __u32 type_id;
4694 __u16 kind;
4695 int err;
4696
4697 /*
4698 * Iterate over base and split module ids in order to get all
4699 * available structs in the map.
4700 */
4701 for (type_id = 1; type_id < nr_types; ++type_id) {
4702 t = btf_type_by_id(d->btf, type_id);
4703 kind = btf_kind(t);
4704
4705 if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
4706 continue;
4707
4708 /* Skip non-canonical types */
4709 if (type_id != d->map[type_id])
4710 continue;
4711
4712 err = hashmap__add(names_map, t->name_off, type_id);
4713 if (err == -EEXIST)
4714 err = hashmap__set(names_map, t->name_off, 0, NULL, NULL);
4715
4716 if (err)
4717 return err;
4718 }
4719
4720 return 0;
4721}
4722
4723static int btf_dedup_resolve_fwd(struct btf_dedup *d, struct hashmap *names_map, __u32 type_id)
4724{
4725 struct btf_type *t = btf_type_by_id(d->btf, type_id);
4726 enum btf_fwd_kind fwd_kind = btf_kflag(t);
4727 __u16 cand_kind, kind = btf_kind(t);
4728 struct btf_type *cand_t;
4729 uintptr_t cand_id;
4730
4731 if (kind != BTF_KIND_FWD)
4732 return 0;
4733
4734 /* Skip if this FWD already has a mapping */
4735 if (type_id != d->map[type_id])
4736 return 0;
4737
4738 if (!hashmap__find(names_map, t->name_off, &cand_id))
4739 return 0;
4740
4741 /* Zero is a special value indicating that name is not unique */
4742 if (!cand_id)
4743 return 0;
4744
4745 cand_t = btf_type_by_id(d->btf, cand_id);
4746 cand_kind = btf_kind(cand_t);
4747 if ((cand_kind == BTF_KIND_STRUCT && fwd_kind != BTF_FWD_STRUCT) ||
4748 (cand_kind == BTF_KIND_UNION && fwd_kind != BTF_FWD_UNION))
4749 return 0;
4750
4751 d->map[type_id] = cand_id;
4752
4753 return 0;
4754}
4755
4756/*
4757 * Resolve unambiguous forward declarations.
4758 *
4759 * The lion's share of all FWD declarations is resolved during
4760 * `btf_dedup_struct_types` phase when different type graphs are
4761 * compared against each other. However, if in some compilation unit a
4762 * FWD declaration is not a part of a type graph compared against
4763 * another type graph that declaration's canonical type would not be
4764 * changed. Example:
4765 *
4766 * CU #1:
4767 *
4768 * struct foo;
4769 * struct foo *some_global;
4770 *
4771 * CU #2:
4772 *
4773 * struct foo { int u; };
4774 * struct foo *another_global;
4775 *
4776 * After `btf_dedup_struct_types` the BTF looks as follows:
4777 *
4778 * [1] STRUCT 'foo' size=4 vlen=1 ...
4779 * [2] INT 'int' size=4 ...
4780 * [3] PTR '(anon)' type_id=1
4781 * [4] FWD 'foo' fwd_kind=struct
4782 * [5] PTR '(anon)' type_id=4
4783 *
4784 * This pass assumes that such FWD declarations should be mapped to
4785 * structs or unions with identical name in case if the name is not
4786 * ambiguous.
4787 */
4788static int btf_dedup_resolve_fwds(struct btf_dedup *d)
4789{
4790 int i, err;
4791 struct hashmap *names_map;
4792
4793 names_map = hashmap__new(btf_dedup_identity_hash_fn, btf_dedup_equal_fn, NULL);
4794 if (IS_ERR(names_map))
4795 return PTR_ERR(names_map);
4796
4797 err = btf_dedup_fill_unique_names_map(d, names_map);
4798 if (err < 0)
4799 goto exit;
4800
4801 for (i = 0; i < d->btf->nr_types; i++) {
4802 err = btf_dedup_resolve_fwd(d, names_map, d->btf->start_id + i);
4803 if (err < 0)
4804 break;
4805 }
4806
4807exit:
4808 hashmap__free(names_map);
4809 return err;
4810}
4811
4812/*
4813 * Compact types.
4814 *
4815 * After we established for each type its corresponding canonical representative
4816 * type, we now can eliminate types that are not canonical and leave only
4817 * canonical ones layed out sequentially in memory by copying them over
4818 * duplicates. During compaction btf_dedup->hypot_map array is reused to store
4819 * a map from original type ID to a new compacted type ID, which will be used
4820 * during next phase to "fix up" type IDs, referenced from struct/union and
4821 * reference types.
4822 */
4823static int btf_dedup_compact_types(struct btf_dedup *d)
4824{
4825 __u32 *new_offs;
4826 __u32 next_type_id = d->btf->start_id;
4827 const struct btf_type *t;
4828 void *p;
4829 int i, id, len;
4830
4831 /* we are going to reuse hypot_map to store compaction remapping */
4832 d->hypot_map[0] = 0;
4833 /* base BTF types are not renumbered */
4834 for (id = 1; id < d->btf->start_id; id++)
4835 d->hypot_map[id] = id;
4836 for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++)
4837 d->hypot_map[id] = BTF_UNPROCESSED_ID;
4838
4839 p = d->btf->types_data;
4840
4841 for (i = 0, id = d->btf->start_id; i < d->btf->nr_types; i++, id++) {
4842 if (d->map[id] != id)
4843 continue;
4844
4845 t = btf__type_by_id(d->btf, id);
4846 len = btf_type_size(t);
4847 if (len < 0)
4848 return len;
4849
4850 memmove(p, t, len);
4851 d->hypot_map[id] = next_type_id;
4852 d->btf->type_offs[next_type_id - d->btf->start_id] = p - d->btf->types_data;
4853 p += len;
4854 next_type_id++;
4855 }
4856
4857 /* shrink struct btf's internal types index and update btf_header */
4858 d->btf->nr_types = next_type_id - d->btf->start_id;
4859 d->btf->type_offs_cap = d->btf->nr_types;
4860 d->btf->hdr->type_len = p - d->btf->types_data;
4861 new_offs = libbpf_reallocarray(d->btf->type_offs, d->btf->type_offs_cap,
4862 sizeof(*new_offs));
4863 if (d->btf->type_offs_cap && !new_offs)
4864 return -ENOMEM;
4865 d->btf->type_offs = new_offs;
4866 d->btf->hdr->str_off = d->btf->hdr->type_len;
4867 d->btf->raw_size = d->btf->hdr->hdr_len + d->btf->hdr->type_len + d->btf->hdr->str_len;
4868 return 0;
4869}
4870
4871/*
4872 * Figure out final (deduplicated and compacted) type ID for provided original
4873 * `type_id` by first resolving it into corresponding canonical type ID and
4874 * then mapping it to a deduplicated type ID, stored in btf_dedup->hypot_map,
4875 * which is populated during compaction phase.
4876 */
4877static int btf_dedup_remap_type_id(__u32 *type_id, void *ctx)
4878{
4879 struct btf_dedup *d = ctx;
4880 __u32 resolved_type_id, new_type_id;
4881
4882 resolved_type_id = resolve_type_id(d, *type_id);
4883 new_type_id = d->hypot_map[resolved_type_id];
4884 if (new_type_id > BTF_MAX_NR_TYPES)
4885 return -EINVAL;
4886
4887 *type_id = new_type_id;
4888 return 0;
4889}
4890
4891/*
4892 * Remap referenced type IDs into deduped type IDs.
4893 *
4894 * After BTF types are deduplicated and compacted, their final type IDs may
4895 * differ from original ones. The map from original to a corresponding
4896 * deduped type ID is stored in btf_dedup->hypot_map and is populated during
4897 * compaction phase. During remapping phase we are rewriting all type IDs
4898 * referenced from any BTF type (e.g., struct fields, func proto args, etc) to
4899 * their final deduped type IDs.
4900 */
4901static int btf_dedup_remap_types(struct btf_dedup *d)
4902{
4903 int i, r;
4904
4905 for (i = 0; i < d->btf->nr_types; i++) {
4906 struct btf_type *t = btf_type_by_id(d->btf, d->btf->start_id + i);
4907
4908 r = btf_type_visit_type_ids(t, btf_dedup_remap_type_id, d);
4909 if (r)
4910 return r;
4911 }
4912
4913 if (!d->btf_ext)
4914 return 0;
4915
4916 r = btf_ext_visit_type_ids(d->btf_ext, btf_dedup_remap_type_id, d);
4917 if (r)
4918 return r;
4919
4920 return 0;
4921}
4922
4923/*
4924 * Probe few well-known locations for vmlinux kernel image and try to load BTF
4925 * data out of it to use for target BTF.
4926 */
4927struct btf *btf__load_vmlinux_btf(void)
4928{
4929 const char *locations[] = {
4930 /* try canonical vmlinux BTF through sysfs first */
4931 "/sys/kernel/btf/vmlinux",
4932 /* fall back to trying to find vmlinux on disk otherwise */
4933 "/boot/vmlinux-%1$s",
4934 "/lib/modules/%1$s/vmlinux-%1$s",
4935 "/lib/modules/%1$s/build/vmlinux",
4936 "/usr/lib/modules/%1$s/kernel/vmlinux",
4937 "/usr/lib/debug/boot/vmlinux-%1$s",
4938 "/usr/lib/debug/boot/vmlinux-%1$s.debug",
4939 "/usr/lib/debug/lib/modules/%1$s/vmlinux",
4940 };
4941 char path[PATH_MAX + 1];
4942 struct utsname buf;
4943 struct btf *btf;
4944 int i, err;
4945
4946 uname(&buf);
4947
4948 for (i = 0; i < ARRAY_SIZE(locations); i++) {
4949 snprintf(path, PATH_MAX, locations[i], buf.release);
4950
4951 if (faccessat(AT_FDCWD, path, R_OK, AT_EACCESS))
4952 continue;
4953
4954 btf = btf__parse(path, NULL);
4955 err = libbpf_get_error(btf);
4956 pr_debug("loading kernel BTF '%s': %d\n", path, err);
4957 if (err)
4958 continue;
4959
4960 return btf;
4961 }
4962
4963 pr_warn("failed to find valid kernel BTF\n");
4964 return libbpf_err_ptr(-ESRCH);
4965}
4966
4967struct btf *libbpf_find_kernel_btf(void) __attribute__((alias("btf__load_vmlinux_btf")));
4968
4969struct btf *btf__load_module_btf(const char *module_name, struct btf *vmlinux_btf)
4970{
4971 char path[80];
4972
4973 snprintf(path, sizeof(path), "/sys/kernel/btf/%s", module_name);
4974 return btf__parse_split(path, vmlinux_btf);
4975}
4976
4977int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ctx)
4978{
4979 int i, n, err;
4980
4981 switch (btf_kind(t)) {
4982 case BTF_KIND_INT:
4983 case BTF_KIND_FLOAT:
4984 case BTF_KIND_ENUM:
4985 case BTF_KIND_ENUM64:
4986 return 0;
4987
4988 case BTF_KIND_FWD:
4989 case BTF_KIND_CONST:
4990 case BTF_KIND_VOLATILE:
4991 case BTF_KIND_RESTRICT:
4992 case BTF_KIND_PTR:
4993 case BTF_KIND_TYPEDEF:
4994 case BTF_KIND_FUNC:
4995 case BTF_KIND_VAR:
4996 case BTF_KIND_DECL_TAG:
4997 case BTF_KIND_TYPE_TAG:
4998 return visit(&t->type, ctx);
4999
5000 case BTF_KIND_ARRAY: {
5001 struct btf_array *a = btf_array(t);
5002
5003 err = visit(&a->type, ctx);
5004 err = err ?: visit(&a->index_type, ctx);
5005 return err;
5006 }
5007
5008 case BTF_KIND_STRUCT:
5009 case BTF_KIND_UNION: {
5010 struct btf_member *m = btf_members(t);
5011
5012 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5013 err = visit(&m->type, ctx);
5014 if (err)
5015 return err;
5016 }
5017 return 0;
5018 }
5019
5020 case BTF_KIND_FUNC_PROTO: {
5021 struct btf_param *m = btf_params(t);
5022
5023 err = visit(&t->type, ctx);
5024 if (err)
5025 return err;
5026 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5027 err = visit(&m->type, ctx);
5028 if (err)
5029 return err;
5030 }
5031 return 0;
5032 }
5033
5034 case BTF_KIND_DATASEC: {
5035 struct btf_var_secinfo *m = btf_var_secinfos(t);
5036
5037 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5038 err = visit(&m->type, ctx);
5039 if (err)
5040 return err;
5041 }
5042 return 0;
5043 }
5044
5045 default:
5046 return -EINVAL;
5047 }
5048}
5049
5050int btf_type_visit_str_offs(struct btf_type *t, str_off_visit_fn visit, void *ctx)
5051{
5052 int i, n, err;
5053
5054 err = visit(&t->name_off, ctx);
5055 if (err)
5056 return err;
5057
5058 switch (btf_kind(t)) {
5059 case BTF_KIND_STRUCT:
5060 case BTF_KIND_UNION: {
5061 struct btf_member *m = btf_members(t);
5062
5063 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5064 err = visit(&m->name_off, ctx);
5065 if (err)
5066 return err;
5067 }
5068 break;
5069 }
5070 case BTF_KIND_ENUM: {
5071 struct btf_enum *m = btf_enum(t);
5072
5073 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5074 err = visit(&m->name_off, ctx);
5075 if (err)
5076 return err;
5077 }
5078 break;
5079 }
5080 case BTF_KIND_ENUM64: {
5081 struct btf_enum64 *m = btf_enum64(t);
5082
5083 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5084 err = visit(&m->name_off, ctx);
5085 if (err)
5086 return err;
5087 }
5088 break;
5089 }
5090 case BTF_KIND_FUNC_PROTO: {
5091 struct btf_param *m = btf_params(t);
5092
5093 for (i = 0, n = btf_vlen(t); i < n; i++, m++) {
5094 err = visit(&m->name_off, ctx);
5095 if (err)
5096 return err;
5097 }
5098 break;
5099 }
5100 default:
5101 break;
5102 }
5103
5104 return 0;
5105}
5106
5107int btf_ext_visit_type_ids(struct btf_ext *btf_ext, type_id_visit_fn visit, void *ctx)
5108{
5109 const struct btf_ext_info *seg;
5110 struct btf_ext_info_sec *sec;
5111 int i, err;
5112
5113 seg = &btf_ext->func_info;
5114 for_each_btf_ext_sec(seg, sec) {
5115 struct bpf_func_info_min *rec;
5116
5117 for_each_btf_ext_rec(seg, sec, i, rec) {
5118 err = visit(&rec->type_id, ctx);
5119 if (err < 0)
5120 return err;
5121 }
5122 }
5123
5124 seg = &btf_ext->core_relo_info;
5125 for_each_btf_ext_sec(seg, sec) {
5126 struct bpf_core_relo *rec;
5127
5128 for_each_btf_ext_rec(seg, sec, i, rec) {
5129 err = visit(&rec->type_id, ctx);
5130 if (err < 0)
5131 return err;
5132 }
5133 }
5134
5135 return 0;
5136}
5137
5138int btf_ext_visit_str_offs(struct btf_ext *btf_ext, str_off_visit_fn visit, void *ctx)
5139{
5140 const struct btf_ext_info *seg;
5141 struct btf_ext_info_sec *sec;
5142 int i, err;
5143
5144 seg = &btf_ext->func_info;
5145 for_each_btf_ext_sec(seg, sec) {
5146 err = visit(&sec->sec_name_off, ctx);
5147 if (err)
5148 return err;
5149 }
5150
5151 seg = &btf_ext->line_info;
5152 for_each_btf_ext_sec(seg, sec) {
5153 struct bpf_line_info_min *rec;
5154
5155 err = visit(&sec->sec_name_off, ctx);
5156 if (err)
5157 return err;
5158
5159 for_each_btf_ext_rec(seg, sec, i, rec) {
5160 err = visit(&rec->file_name_off, ctx);
5161 if (err)
5162 return err;
5163 err = visit(&rec->line_off, ctx);
5164 if (err)
5165 return err;
5166 }
5167 }
5168
5169 seg = &btf_ext->core_relo_info;
5170 for_each_btf_ext_sec(seg, sec) {
5171 struct bpf_core_relo *rec;
5172
5173 err = visit(&sec->sec_name_off, ctx);
5174 if (err)
5175 return err;
5176
5177 for_each_btf_ext_rec(seg, sec, i, rec) {
5178 err = visit(&rec->access_str_off, ctx);
5179 if (err)
5180 return err;
5181 }
5182 }
5183
5184 return 0;
5185}
1// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2/* Copyright (c) 2018 Facebook */
3
4#include <endian.h>
5#include <stdio.h>
6#include <stdlib.h>
7#include <string.h>
8#include <fcntl.h>
9#include <unistd.h>
10#include <errno.h>
11#include <sys/utsname.h>
12#include <sys/param.h>
13#include <sys/stat.h>
14#include <linux/kernel.h>
15#include <linux/err.h>
16#include <linux/btf.h>
17#include <gelf.h>
18#include "btf.h"
19#include "bpf.h"
20#include "libbpf.h"
21#include "libbpf_internal.h"
22#include "hashmap.h"
23
24/* make sure libbpf doesn't use kernel-only integer typedefs */
25#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
26
27#define BTF_MAX_NR_TYPES 0x7fffffffU
28#define BTF_MAX_STR_OFFSET 0x7fffffffU
29
30static struct btf_type btf_void;
31
32struct btf {
33 union {
34 struct btf_header *hdr;
35 void *data;
36 };
37 struct btf_type **types;
38 const char *strings;
39 void *nohdr_data;
40 __u32 nr_types;
41 __u32 types_size;
42 __u32 data_size;
43 int fd;
44 int ptr_sz;
45};
46
47static inline __u64 ptr_to_u64(const void *ptr)
48{
49 return (__u64) (unsigned long) ptr;
50}
51
52static int btf_add_type(struct btf *btf, struct btf_type *t)
53{
54 if (btf->types_size - btf->nr_types < 2) {
55 struct btf_type **new_types;
56 __u32 expand_by, new_size;
57
58 if (btf->types_size == BTF_MAX_NR_TYPES)
59 return -E2BIG;
60
61 expand_by = max(btf->types_size >> 2, 16U);
62 new_size = min(BTF_MAX_NR_TYPES, btf->types_size + expand_by);
63
64 new_types = realloc(btf->types, sizeof(*new_types) * new_size);
65 if (!new_types)
66 return -ENOMEM;
67
68 if (btf->nr_types == 0)
69 new_types[0] = &btf_void;
70
71 btf->types = new_types;
72 btf->types_size = new_size;
73 }
74
75 btf->types[++(btf->nr_types)] = t;
76
77 return 0;
78}
79
80static int btf_parse_hdr(struct btf *btf)
81{
82 const struct btf_header *hdr = btf->hdr;
83 __u32 meta_left;
84
85 if (btf->data_size < sizeof(struct btf_header)) {
86 pr_debug("BTF header not found\n");
87 return -EINVAL;
88 }
89
90 if (hdr->magic != BTF_MAGIC) {
91 pr_debug("Invalid BTF magic:%x\n", hdr->magic);
92 return -EINVAL;
93 }
94
95 if (hdr->version != BTF_VERSION) {
96 pr_debug("Unsupported BTF version:%u\n", hdr->version);
97 return -ENOTSUP;
98 }
99
100 if (hdr->flags) {
101 pr_debug("Unsupported BTF flags:%x\n", hdr->flags);
102 return -ENOTSUP;
103 }
104
105 meta_left = btf->data_size - sizeof(*hdr);
106 if (!meta_left) {
107 pr_debug("BTF has no data\n");
108 return -EINVAL;
109 }
110
111 if (meta_left < hdr->type_off) {
112 pr_debug("Invalid BTF type section offset:%u\n", hdr->type_off);
113 return -EINVAL;
114 }
115
116 if (meta_left < hdr->str_off) {
117 pr_debug("Invalid BTF string section offset:%u\n", hdr->str_off);
118 return -EINVAL;
119 }
120
121 if (hdr->type_off >= hdr->str_off) {
122 pr_debug("BTF type section offset >= string section offset. No type?\n");
123 return -EINVAL;
124 }
125
126 if (hdr->type_off & 0x02) {
127 pr_debug("BTF type section is not aligned to 4 bytes\n");
128 return -EINVAL;
129 }
130
131 btf->nohdr_data = btf->hdr + 1;
132
133 return 0;
134}
135
136static int btf_parse_str_sec(struct btf *btf)
137{
138 const struct btf_header *hdr = btf->hdr;
139 const char *start = btf->nohdr_data + hdr->str_off;
140 const char *end = start + btf->hdr->str_len;
141
142 if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_STR_OFFSET ||
143 start[0] || end[-1]) {
144 pr_debug("Invalid BTF string section\n");
145 return -EINVAL;
146 }
147
148 btf->strings = start;
149
150 return 0;
151}
152
153static int btf_type_size(struct btf_type *t)
154{
155 int base_size = sizeof(struct btf_type);
156 __u16 vlen = btf_vlen(t);
157
158 switch (btf_kind(t)) {
159 case BTF_KIND_FWD:
160 case BTF_KIND_CONST:
161 case BTF_KIND_VOLATILE:
162 case BTF_KIND_RESTRICT:
163 case BTF_KIND_PTR:
164 case BTF_KIND_TYPEDEF:
165 case BTF_KIND_FUNC:
166 return base_size;
167 case BTF_KIND_INT:
168 return base_size + sizeof(__u32);
169 case BTF_KIND_ENUM:
170 return base_size + vlen * sizeof(struct btf_enum);
171 case BTF_KIND_ARRAY:
172 return base_size + sizeof(struct btf_array);
173 case BTF_KIND_STRUCT:
174 case BTF_KIND_UNION:
175 return base_size + vlen * sizeof(struct btf_member);
176 case BTF_KIND_FUNC_PROTO:
177 return base_size + vlen * sizeof(struct btf_param);
178 case BTF_KIND_VAR:
179 return base_size + sizeof(struct btf_var);
180 case BTF_KIND_DATASEC:
181 return base_size + vlen * sizeof(struct btf_var_secinfo);
182 default:
183 pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
184 return -EINVAL;
185 }
186}
187
188static int btf_parse_type_sec(struct btf *btf)
189{
190 struct btf_header *hdr = btf->hdr;
191 void *nohdr_data = btf->nohdr_data;
192 void *next_type = nohdr_data + hdr->type_off;
193 void *end_type = nohdr_data + hdr->str_off;
194
195 while (next_type < end_type) {
196 struct btf_type *t = next_type;
197 int type_size;
198 int err;
199
200 type_size = btf_type_size(t);
201 if (type_size < 0)
202 return type_size;
203 next_type += type_size;
204 err = btf_add_type(btf, t);
205 if (err)
206 return err;
207 }
208
209 return 0;
210}
211
212__u32 btf__get_nr_types(const struct btf *btf)
213{
214 return btf->nr_types;
215}
216
217const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
218{
219 if (type_id > btf->nr_types)
220 return NULL;
221
222 return btf->types[type_id];
223}
224
225static int determine_ptr_size(const struct btf *btf)
226{
227 const struct btf_type *t;
228 const char *name;
229 int i;
230
231 for (i = 1; i <= btf->nr_types; i++) {
232 t = btf__type_by_id(btf, i);
233 if (!btf_is_int(t))
234 continue;
235
236 name = btf__name_by_offset(btf, t->name_off);
237 if (!name)
238 continue;
239
240 if (strcmp(name, "long int") == 0 ||
241 strcmp(name, "long unsigned int") == 0) {
242 if (t->size != 4 && t->size != 8)
243 continue;
244 return t->size;
245 }
246 }
247
248 return -1;
249}
250
251static size_t btf_ptr_sz(const struct btf *btf)
252{
253 if (!btf->ptr_sz)
254 ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
255 return btf->ptr_sz < 0 ? sizeof(void *) : btf->ptr_sz;
256}
257
258/* Return pointer size this BTF instance assumes. The size is heuristically
259 * determined by looking for 'long' or 'unsigned long' integer type and
260 * recording its size in bytes. If BTF type information doesn't have any such
261 * type, this function returns 0. In the latter case, native architecture's
262 * pointer size is assumed, so will be either 4 or 8, depending on
263 * architecture that libbpf was compiled for. It's possible to override
264 * guessed value by using btf__set_pointer_size() API.
265 */
266size_t btf__pointer_size(const struct btf *btf)
267{
268 if (!btf->ptr_sz)
269 ((struct btf *)btf)->ptr_sz = determine_ptr_size(btf);
270
271 if (btf->ptr_sz < 0)
272 /* not enough BTF type info to guess */
273 return 0;
274
275 return btf->ptr_sz;
276}
277
278/* Override or set pointer size in bytes. Only values of 4 and 8 are
279 * supported.
280 */
281int btf__set_pointer_size(struct btf *btf, size_t ptr_sz)
282{
283 if (ptr_sz != 4 && ptr_sz != 8)
284 return -EINVAL;
285 btf->ptr_sz = ptr_sz;
286 return 0;
287}
288
289static bool btf_type_is_void(const struct btf_type *t)
290{
291 return t == &btf_void || btf_is_fwd(t);
292}
293
294static bool btf_type_is_void_or_null(const struct btf_type *t)
295{
296 return !t || btf_type_is_void(t);
297}
298
299#define MAX_RESOLVE_DEPTH 32
300
301__s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
302{
303 const struct btf_array *array;
304 const struct btf_type *t;
305 __u32 nelems = 1;
306 __s64 size = -1;
307 int i;
308
309 t = btf__type_by_id(btf, type_id);
310 for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t);
311 i++) {
312 switch (btf_kind(t)) {
313 case BTF_KIND_INT:
314 case BTF_KIND_STRUCT:
315 case BTF_KIND_UNION:
316 case BTF_KIND_ENUM:
317 case BTF_KIND_DATASEC:
318 size = t->size;
319 goto done;
320 case BTF_KIND_PTR:
321 size = btf_ptr_sz(btf);
322 goto done;
323 case BTF_KIND_TYPEDEF:
324 case BTF_KIND_VOLATILE:
325 case BTF_KIND_CONST:
326 case BTF_KIND_RESTRICT:
327 case BTF_KIND_VAR:
328 type_id = t->type;
329 break;
330 case BTF_KIND_ARRAY:
331 array = btf_array(t);
332 if (nelems && array->nelems > UINT32_MAX / nelems)
333 return -E2BIG;
334 nelems *= array->nelems;
335 type_id = array->type;
336 break;
337 default:
338 return -EINVAL;
339 }
340
341 t = btf__type_by_id(btf, type_id);
342 }
343
344done:
345 if (size < 0)
346 return -EINVAL;
347 if (nelems && size > UINT32_MAX / nelems)
348 return -E2BIG;
349
350 return nelems * size;
351}
352
353int btf__align_of(const struct btf *btf, __u32 id)
354{
355 const struct btf_type *t = btf__type_by_id(btf, id);
356 __u16 kind = btf_kind(t);
357
358 switch (kind) {
359 case BTF_KIND_INT:
360 case BTF_KIND_ENUM:
361 return min(btf_ptr_sz(btf), (size_t)t->size);
362 case BTF_KIND_PTR:
363 return btf_ptr_sz(btf);
364 case BTF_KIND_TYPEDEF:
365 case BTF_KIND_VOLATILE:
366 case BTF_KIND_CONST:
367 case BTF_KIND_RESTRICT:
368 return btf__align_of(btf, t->type);
369 case BTF_KIND_ARRAY:
370 return btf__align_of(btf, btf_array(t)->type);
371 case BTF_KIND_STRUCT:
372 case BTF_KIND_UNION: {
373 const struct btf_member *m = btf_members(t);
374 __u16 vlen = btf_vlen(t);
375 int i, max_align = 1, align;
376
377 for (i = 0; i < vlen; i++, m++) {
378 align = btf__align_of(btf, m->type);
379 if (align <= 0)
380 return align;
381 max_align = max(max_align, align);
382 }
383
384 return max_align;
385 }
386 default:
387 pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
388 return 0;
389 }
390}
391
392int btf__resolve_type(const struct btf *btf, __u32 type_id)
393{
394 const struct btf_type *t;
395 int depth = 0;
396
397 t = btf__type_by_id(btf, type_id);
398 while (depth < MAX_RESOLVE_DEPTH &&
399 !btf_type_is_void_or_null(t) &&
400 (btf_is_mod(t) || btf_is_typedef(t) || btf_is_var(t))) {
401 type_id = t->type;
402 t = btf__type_by_id(btf, type_id);
403 depth++;
404 }
405
406 if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
407 return -EINVAL;
408
409 return type_id;
410}
411
412__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
413{
414 __u32 i;
415
416 if (!strcmp(type_name, "void"))
417 return 0;
418
419 for (i = 1; i <= btf->nr_types; i++) {
420 const struct btf_type *t = btf->types[i];
421 const char *name = btf__name_by_offset(btf, t->name_off);
422
423 if (name && !strcmp(type_name, name))
424 return i;
425 }
426
427 return -ENOENT;
428}
429
430__s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
431 __u32 kind)
432{
433 __u32 i;
434
435 if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void"))
436 return 0;
437
438 for (i = 1; i <= btf->nr_types; i++) {
439 const struct btf_type *t = btf->types[i];
440 const char *name;
441
442 if (btf_kind(t) != kind)
443 continue;
444 name = btf__name_by_offset(btf, t->name_off);
445 if (name && !strcmp(type_name, name))
446 return i;
447 }
448
449 return -ENOENT;
450}
451
452void btf__free(struct btf *btf)
453{
454 if (IS_ERR_OR_NULL(btf))
455 return;
456
457 if (btf->fd >= 0)
458 close(btf->fd);
459
460 free(btf->data);
461 free(btf->types);
462 free(btf);
463}
464
465struct btf *btf__new(const void *data, __u32 size)
466{
467 struct btf *btf;
468 int err;
469
470 btf = calloc(1, sizeof(struct btf));
471 if (!btf)
472 return ERR_PTR(-ENOMEM);
473
474 btf->fd = -1;
475
476 btf->data = malloc(size);
477 if (!btf->data) {
478 err = -ENOMEM;
479 goto done;
480 }
481
482 memcpy(btf->data, data, size);
483 btf->data_size = size;
484
485 err = btf_parse_hdr(btf);
486 if (err)
487 goto done;
488
489 err = btf_parse_str_sec(btf);
490 if (err)
491 goto done;
492
493 err = btf_parse_type_sec(btf);
494
495done:
496 if (err) {
497 btf__free(btf);
498 return ERR_PTR(err);
499 }
500
501 return btf;
502}
503
504static bool btf_check_endianness(const GElf_Ehdr *ehdr)
505{
506#if __BYTE_ORDER == __LITTLE_ENDIAN
507 return ehdr->e_ident[EI_DATA] == ELFDATA2LSB;
508#elif __BYTE_ORDER == __BIG_ENDIAN
509 return ehdr->e_ident[EI_DATA] == ELFDATA2MSB;
510#else
511# error "Unrecognized __BYTE_ORDER__"
512#endif
513}
514
515struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
516{
517 Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
518 int err = 0, fd = -1, idx = 0;
519 struct btf *btf = NULL;
520 Elf_Scn *scn = NULL;
521 Elf *elf = NULL;
522 GElf_Ehdr ehdr;
523
524 if (elf_version(EV_CURRENT) == EV_NONE) {
525 pr_warn("failed to init libelf for %s\n", path);
526 return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
527 }
528
529 fd = open(path, O_RDONLY);
530 if (fd < 0) {
531 err = -errno;
532 pr_warn("failed to open %s: %s\n", path, strerror(errno));
533 return ERR_PTR(err);
534 }
535
536 err = -LIBBPF_ERRNO__FORMAT;
537
538 elf = elf_begin(fd, ELF_C_READ, NULL);
539 if (!elf) {
540 pr_warn("failed to open %s as ELF file\n", path);
541 goto done;
542 }
543 if (!gelf_getehdr(elf, &ehdr)) {
544 pr_warn("failed to get EHDR from %s\n", path);
545 goto done;
546 }
547 if (!btf_check_endianness(&ehdr)) {
548 pr_warn("non-native ELF endianness is not supported\n");
549 goto done;
550 }
551 if (!elf_rawdata(elf_getscn(elf, ehdr.e_shstrndx), NULL)) {
552 pr_warn("failed to get e_shstrndx from %s\n", path);
553 goto done;
554 }
555
556 while ((scn = elf_nextscn(elf, scn)) != NULL) {
557 GElf_Shdr sh;
558 char *name;
559
560 idx++;
561 if (gelf_getshdr(scn, &sh) != &sh) {
562 pr_warn("failed to get section(%d) header from %s\n",
563 idx, path);
564 goto done;
565 }
566 name = elf_strptr(elf, ehdr.e_shstrndx, sh.sh_name);
567 if (!name) {
568 pr_warn("failed to get section(%d) name from %s\n",
569 idx, path);
570 goto done;
571 }
572 if (strcmp(name, BTF_ELF_SEC) == 0) {
573 btf_data = elf_getdata(scn, 0);
574 if (!btf_data) {
575 pr_warn("failed to get section(%d, %s) data from %s\n",
576 idx, name, path);
577 goto done;
578 }
579 continue;
580 } else if (btf_ext && strcmp(name, BTF_EXT_ELF_SEC) == 0) {
581 btf_ext_data = elf_getdata(scn, 0);
582 if (!btf_ext_data) {
583 pr_warn("failed to get section(%d, %s) data from %s\n",
584 idx, name, path);
585 goto done;
586 }
587 continue;
588 }
589 }
590
591 err = 0;
592
593 if (!btf_data) {
594 err = -ENOENT;
595 goto done;
596 }
597 btf = btf__new(btf_data->d_buf, btf_data->d_size);
598 if (IS_ERR(btf))
599 goto done;
600
601 switch (gelf_getclass(elf)) {
602 case ELFCLASS32:
603 btf__set_pointer_size(btf, 4);
604 break;
605 case ELFCLASS64:
606 btf__set_pointer_size(btf, 8);
607 break;
608 default:
609 pr_warn("failed to get ELF class (bitness) for %s\n", path);
610 break;
611 }
612
613 if (btf_ext && btf_ext_data) {
614 *btf_ext = btf_ext__new(btf_ext_data->d_buf,
615 btf_ext_data->d_size);
616 if (IS_ERR(*btf_ext))
617 goto done;
618 } else if (btf_ext) {
619 *btf_ext = NULL;
620 }
621done:
622 if (elf)
623 elf_end(elf);
624 close(fd);
625
626 if (err)
627 return ERR_PTR(err);
628 /*
629 * btf is always parsed before btf_ext, so no need to clean up
630 * btf_ext, if btf loading failed
631 */
632 if (IS_ERR(btf))
633 return btf;
634 if (btf_ext && IS_ERR(*btf_ext)) {
635 btf__free(btf);
636 err = PTR_ERR(*btf_ext);
637 return ERR_PTR(err);
638 }
639 return btf;
640}
641
642struct btf *btf__parse_raw(const char *path)
643{
644 struct btf *btf = NULL;
645 void *data = NULL;
646 FILE *f = NULL;
647 __u16 magic;
648 int err = 0;
649 long sz;
650
651 f = fopen(path, "rb");
652 if (!f) {
653 err = -errno;
654 goto err_out;
655 }
656
657 /* check BTF magic */
658 if (fread(&magic, 1, sizeof(magic), f) < sizeof(magic)) {
659 err = -EIO;
660 goto err_out;
661 }
662 if (magic == __bswap_16(BTF_MAGIC)) {
663 /* non-native endian raw BTF */
664 pr_warn("non-native BTF endianness is not supported\n");
665 err = -LIBBPF_ERRNO__ENDIAN;
666 goto err_out;
667 }
668 if (magic != BTF_MAGIC) {
669 /* definitely not a raw BTF */
670 err = -EPROTO;
671 goto err_out;
672 }
673
674 /* get file size */
675 if (fseek(f, 0, SEEK_END)) {
676 err = -errno;
677 goto err_out;
678 }
679 sz = ftell(f);
680 if (sz < 0) {
681 err = -errno;
682 goto err_out;
683 }
684 /* rewind to the start */
685 if (fseek(f, 0, SEEK_SET)) {
686 err = -errno;
687 goto err_out;
688 }
689
690 /* pre-alloc memory and read all of BTF data */
691 data = malloc(sz);
692 if (!data) {
693 err = -ENOMEM;
694 goto err_out;
695 }
696 if (fread(data, 1, sz, f) < sz) {
697 err = -EIO;
698 goto err_out;
699 }
700
701 /* finally parse BTF data */
702 btf = btf__new(data, sz);
703
704err_out:
705 free(data);
706 if (f)
707 fclose(f);
708 return err ? ERR_PTR(err) : btf;
709}
710
711struct btf *btf__parse(const char *path, struct btf_ext **btf_ext)
712{
713 struct btf *btf;
714
715 if (btf_ext)
716 *btf_ext = NULL;
717
718 btf = btf__parse_raw(path);
719 if (!IS_ERR(btf) || PTR_ERR(btf) != -EPROTO)
720 return btf;
721
722 return btf__parse_elf(path, btf_ext);
723}
724
725static int compare_vsi_off(const void *_a, const void *_b)
726{
727 const struct btf_var_secinfo *a = _a;
728 const struct btf_var_secinfo *b = _b;
729
730 return a->offset - b->offset;
731}
732
733static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
734 struct btf_type *t)
735{
736 __u32 size = 0, off = 0, i, vars = btf_vlen(t);
737 const char *name = btf__name_by_offset(btf, t->name_off);
738 const struct btf_type *t_var;
739 struct btf_var_secinfo *vsi;
740 const struct btf_var *var;
741 int ret;
742
743 if (!name) {
744 pr_debug("No name found in string section for DATASEC kind.\n");
745 return -ENOENT;
746 }
747
748 /* .extern datasec size and var offsets were set correctly during
749 * extern collection step, so just skip straight to sorting variables
750 */
751 if (t->size)
752 goto sort_vars;
753
754 ret = bpf_object__section_size(obj, name, &size);
755 if (ret || !size || (t->size && t->size != size)) {
756 pr_debug("Invalid size for section %s: %u bytes\n", name, size);
757 return -ENOENT;
758 }
759
760 t->size = size;
761
762 for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
763 t_var = btf__type_by_id(btf, vsi->type);
764 var = btf_var(t_var);
765
766 if (!btf_is_var(t_var)) {
767 pr_debug("Non-VAR type seen in section %s\n", name);
768 return -EINVAL;
769 }
770
771 if (var->linkage == BTF_VAR_STATIC)
772 continue;
773
774 name = btf__name_by_offset(btf, t_var->name_off);
775 if (!name) {
776 pr_debug("No name found in string section for VAR kind\n");
777 return -ENOENT;
778 }
779
780 ret = bpf_object__variable_offset(obj, name, &off);
781 if (ret) {
782 pr_debug("No offset found in symbol table for VAR %s\n",
783 name);
784 return -ENOENT;
785 }
786
787 vsi->offset = off;
788 }
789
790sort_vars:
791 qsort(btf_var_secinfos(t), vars, sizeof(*vsi), compare_vsi_off);
792 return 0;
793}
794
795int btf__finalize_data(struct bpf_object *obj, struct btf *btf)
796{
797 int err = 0;
798 __u32 i;
799
800 for (i = 1; i <= btf->nr_types; i++) {
801 struct btf_type *t = btf->types[i];
802
803 /* Loader needs to fix up some of the things compiler
804 * couldn't get its hands on while emitting BTF. This
805 * is section size and global variable offset. We use
806 * the info from the ELF itself for this purpose.
807 */
808 if (btf_is_datasec(t)) {
809 err = btf_fixup_datasec(obj, btf, t);
810 if (err)
811 break;
812 }
813 }
814
815 return err;
816}
817
818int btf__load(struct btf *btf)
819{
820 __u32 log_buf_size = 0;
821 char *log_buf = NULL;
822 int err = 0;
823
824 if (btf->fd >= 0)
825 return -EEXIST;
826
827retry_load:
828 if (log_buf_size) {
829 log_buf = malloc(log_buf_size);
830 if (!log_buf)
831 return -ENOMEM;
832
833 *log_buf = 0;
834 }
835
836 btf->fd = bpf_load_btf(btf->data, btf->data_size,
837 log_buf, log_buf_size, false);
838 if (btf->fd < 0) {
839 if (!log_buf || errno == ENOSPC) {
840 log_buf_size = max((__u32)BPF_LOG_BUF_SIZE,
841 log_buf_size << 1);
842 free(log_buf);
843 goto retry_load;
844 }
845
846 err = -errno;
847 pr_warn("Error loading BTF: %s(%d)\n", strerror(errno), errno);
848 if (*log_buf)
849 pr_warn("%s\n", log_buf);
850 goto done;
851 }
852
853done:
854 free(log_buf);
855 return err;
856}
857
858int btf__fd(const struct btf *btf)
859{
860 return btf->fd;
861}
862
863void btf__set_fd(struct btf *btf, int fd)
864{
865 btf->fd = fd;
866}
867
868const void *btf__get_raw_data(const struct btf *btf, __u32 *size)
869{
870 *size = btf->data_size;
871 return btf->data;
872}
873
874const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
875{
876 if (offset < btf->hdr->str_len)
877 return &btf->strings[offset];
878 else
879 return NULL;
880}
881
882int btf__get_from_id(__u32 id, struct btf **btf)
883{
884 struct bpf_btf_info btf_info = { 0 };
885 __u32 len = sizeof(btf_info);
886 __u32 last_size;
887 int btf_fd;
888 void *ptr;
889 int err;
890
891 err = 0;
892 *btf = NULL;
893 btf_fd = bpf_btf_get_fd_by_id(id);
894 if (btf_fd < 0)
895 return 0;
896
897 /* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so
898 * let's start with a sane default - 4KiB here - and resize it only if
899 * bpf_obj_get_info_by_fd() needs a bigger buffer.
900 */
901 btf_info.btf_size = 4096;
902 last_size = btf_info.btf_size;
903 ptr = malloc(last_size);
904 if (!ptr) {
905 err = -ENOMEM;
906 goto exit_free;
907 }
908
909 memset(ptr, 0, last_size);
910 btf_info.btf = ptr_to_u64(ptr);
911 err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
912
913 if (!err && btf_info.btf_size > last_size) {
914 void *temp_ptr;
915
916 last_size = btf_info.btf_size;
917 temp_ptr = realloc(ptr, last_size);
918 if (!temp_ptr) {
919 err = -ENOMEM;
920 goto exit_free;
921 }
922 ptr = temp_ptr;
923 memset(ptr, 0, last_size);
924 btf_info.btf = ptr_to_u64(ptr);
925 err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
926 }
927
928 if (err || btf_info.btf_size > last_size) {
929 err = errno;
930 goto exit_free;
931 }
932
933 *btf = btf__new((__u8 *)(long)btf_info.btf, btf_info.btf_size);
934 if (IS_ERR(*btf)) {
935 err = PTR_ERR(*btf);
936 *btf = NULL;
937 }
938
939exit_free:
940 close(btf_fd);
941 free(ptr);
942
943 return err;
944}
945
946int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
947 __u32 expected_key_size, __u32 expected_value_size,
948 __u32 *key_type_id, __u32 *value_type_id)
949{
950 const struct btf_type *container_type;
951 const struct btf_member *key, *value;
952 const size_t max_name = 256;
953 char container_name[max_name];
954 __s64 key_size, value_size;
955 __s32 container_id;
956
957 if (snprintf(container_name, max_name, "____btf_map_%s", map_name) ==
958 max_name) {
959 pr_warn("map:%s length of '____btf_map_%s' is too long\n",
960 map_name, map_name);
961 return -EINVAL;
962 }
963
964 container_id = btf__find_by_name(btf, container_name);
965 if (container_id < 0) {
966 pr_debug("map:%s container_name:%s cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?\n",
967 map_name, container_name);
968 return container_id;
969 }
970
971 container_type = btf__type_by_id(btf, container_id);
972 if (!container_type) {
973 pr_warn("map:%s cannot find BTF type for container_id:%u\n",
974 map_name, container_id);
975 return -EINVAL;
976 }
977
978 if (!btf_is_struct(container_type) || btf_vlen(container_type) < 2) {
979 pr_warn("map:%s container_name:%s is an invalid container struct\n",
980 map_name, container_name);
981 return -EINVAL;
982 }
983
984 key = btf_members(container_type);
985 value = key + 1;
986
987 key_size = btf__resolve_size(btf, key->type);
988 if (key_size < 0) {
989 pr_warn("map:%s invalid BTF key_type_size\n", map_name);
990 return key_size;
991 }
992
993 if (expected_key_size != key_size) {
994 pr_warn("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
995 map_name, (__u32)key_size, expected_key_size);
996 return -EINVAL;
997 }
998
999 value_size = btf__resolve_size(btf, value->type);
1000 if (value_size < 0) {
1001 pr_warn("map:%s invalid BTF value_type_size\n", map_name);
1002 return value_size;
1003 }
1004
1005 if (expected_value_size != value_size) {
1006 pr_warn("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
1007 map_name, (__u32)value_size, expected_value_size);
1008 return -EINVAL;
1009 }
1010
1011 *key_type_id = key->type;
1012 *value_type_id = value->type;
1013
1014 return 0;
1015}
1016
1017struct btf_ext_sec_setup_param {
1018 __u32 off;
1019 __u32 len;
1020 __u32 min_rec_size;
1021 struct btf_ext_info *ext_info;
1022 const char *desc;
1023};
1024
1025static int btf_ext_setup_info(struct btf_ext *btf_ext,
1026 struct btf_ext_sec_setup_param *ext_sec)
1027{
1028 const struct btf_ext_info_sec *sinfo;
1029 struct btf_ext_info *ext_info;
1030 __u32 info_left, record_size;
1031 /* The start of the info sec (including the __u32 record_size). */
1032 void *info;
1033
1034 if (ext_sec->len == 0)
1035 return 0;
1036
1037 if (ext_sec->off & 0x03) {
1038 pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
1039 ext_sec->desc);
1040 return -EINVAL;
1041 }
1042
1043 info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;
1044 info_left = ext_sec->len;
1045
1046 if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {
1047 pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
1048 ext_sec->desc, ext_sec->off, ext_sec->len);
1049 return -EINVAL;
1050 }
1051
1052 /* At least a record size */
1053 if (info_left < sizeof(__u32)) {
1054 pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
1055 return -EINVAL;
1056 }
1057
1058 /* The record size needs to meet the minimum standard */
1059 record_size = *(__u32 *)info;
1060 if (record_size < ext_sec->min_rec_size ||
1061 record_size & 0x03) {
1062 pr_debug("%s section in .BTF.ext has invalid record size %u\n",
1063 ext_sec->desc, record_size);
1064 return -EINVAL;
1065 }
1066
1067 sinfo = info + sizeof(__u32);
1068 info_left -= sizeof(__u32);
1069
1070 /* If no records, return failure now so .BTF.ext won't be used. */
1071 if (!info_left) {
1072 pr_debug("%s section in .BTF.ext has no records", ext_sec->desc);
1073 return -EINVAL;
1074 }
1075
1076 while (info_left) {
1077 unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
1078 __u64 total_record_size;
1079 __u32 num_records;
1080
1081 if (info_left < sec_hdrlen) {
1082 pr_debug("%s section header is not found in .BTF.ext\n",
1083 ext_sec->desc);
1084 return -EINVAL;
1085 }
1086
1087 num_records = sinfo->num_info;
1088 if (num_records == 0) {
1089 pr_debug("%s section has incorrect num_records in .BTF.ext\n",
1090 ext_sec->desc);
1091 return -EINVAL;
1092 }
1093
1094 total_record_size = sec_hdrlen +
1095 (__u64)num_records * record_size;
1096 if (info_left < total_record_size) {
1097 pr_debug("%s section has incorrect num_records in .BTF.ext\n",
1098 ext_sec->desc);
1099 return -EINVAL;
1100 }
1101
1102 info_left -= total_record_size;
1103 sinfo = (void *)sinfo + total_record_size;
1104 }
1105
1106 ext_info = ext_sec->ext_info;
1107 ext_info->len = ext_sec->len - sizeof(__u32);
1108 ext_info->rec_size = record_size;
1109 ext_info->info = info + sizeof(__u32);
1110
1111 return 0;
1112}
1113
1114static int btf_ext_setup_func_info(struct btf_ext *btf_ext)
1115{
1116 struct btf_ext_sec_setup_param param = {
1117 .off = btf_ext->hdr->func_info_off,
1118 .len = btf_ext->hdr->func_info_len,
1119 .min_rec_size = sizeof(struct bpf_func_info_min),
1120 .ext_info = &btf_ext->func_info,
1121 .desc = "func_info"
1122 };
1123
1124 return btf_ext_setup_info(btf_ext, ¶m);
1125}
1126
1127static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
1128{
1129 struct btf_ext_sec_setup_param param = {
1130 .off = btf_ext->hdr->line_info_off,
1131 .len = btf_ext->hdr->line_info_len,
1132 .min_rec_size = sizeof(struct bpf_line_info_min),
1133 .ext_info = &btf_ext->line_info,
1134 .desc = "line_info",
1135 };
1136
1137 return btf_ext_setup_info(btf_ext, ¶m);
1138}
1139
1140static int btf_ext_setup_field_reloc(struct btf_ext *btf_ext)
1141{
1142 struct btf_ext_sec_setup_param param = {
1143 .off = btf_ext->hdr->field_reloc_off,
1144 .len = btf_ext->hdr->field_reloc_len,
1145 .min_rec_size = sizeof(struct bpf_field_reloc),
1146 .ext_info = &btf_ext->field_reloc_info,
1147 .desc = "field_reloc",
1148 };
1149
1150 return btf_ext_setup_info(btf_ext, ¶m);
1151}
1152
1153static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
1154{
1155 const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
1156
1157 if (data_size < offsetofend(struct btf_ext_header, hdr_len) ||
1158 data_size < hdr->hdr_len) {
1159 pr_debug("BTF.ext header not found");
1160 return -EINVAL;
1161 }
1162
1163 if (hdr->magic != BTF_MAGIC) {
1164 pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic);
1165 return -EINVAL;
1166 }
1167
1168 if (hdr->version != BTF_VERSION) {
1169 pr_debug("Unsupported BTF.ext version:%u\n", hdr->version);
1170 return -ENOTSUP;
1171 }
1172
1173 if (hdr->flags) {
1174 pr_debug("Unsupported BTF.ext flags:%x\n", hdr->flags);
1175 return -ENOTSUP;
1176 }
1177
1178 if (data_size == hdr->hdr_len) {
1179 pr_debug("BTF.ext has no data\n");
1180 return -EINVAL;
1181 }
1182
1183 return 0;
1184}
1185
1186void btf_ext__free(struct btf_ext *btf_ext)
1187{
1188 if (IS_ERR_OR_NULL(btf_ext))
1189 return;
1190 free(btf_ext->data);
1191 free(btf_ext);
1192}
1193
1194struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
1195{
1196 struct btf_ext *btf_ext;
1197 int err;
1198
1199 err = btf_ext_parse_hdr(data, size);
1200 if (err)
1201 return ERR_PTR(err);
1202
1203 btf_ext = calloc(1, sizeof(struct btf_ext));
1204 if (!btf_ext)
1205 return ERR_PTR(-ENOMEM);
1206
1207 btf_ext->data_size = size;
1208 btf_ext->data = malloc(size);
1209 if (!btf_ext->data) {
1210 err = -ENOMEM;
1211 goto done;
1212 }
1213 memcpy(btf_ext->data, data, size);
1214
1215 if (btf_ext->hdr->hdr_len <
1216 offsetofend(struct btf_ext_header, line_info_len))
1217 goto done;
1218 err = btf_ext_setup_func_info(btf_ext);
1219 if (err)
1220 goto done;
1221
1222 err = btf_ext_setup_line_info(btf_ext);
1223 if (err)
1224 goto done;
1225
1226 if (btf_ext->hdr->hdr_len <
1227 offsetofend(struct btf_ext_header, field_reloc_len))
1228 goto done;
1229 err = btf_ext_setup_field_reloc(btf_ext);
1230 if (err)
1231 goto done;
1232
1233done:
1234 if (err) {
1235 btf_ext__free(btf_ext);
1236 return ERR_PTR(err);
1237 }
1238
1239 return btf_ext;
1240}
1241
1242const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size)
1243{
1244 *size = btf_ext->data_size;
1245 return btf_ext->data;
1246}
1247
1248static int btf_ext_reloc_info(const struct btf *btf,
1249 const struct btf_ext_info *ext_info,
1250 const char *sec_name, __u32 insns_cnt,
1251 void **info, __u32 *cnt)
1252{
1253 __u32 sec_hdrlen = sizeof(struct btf_ext_info_sec);
1254 __u32 i, record_size, existing_len, records_len;
1255 struct btf_ext_info_sec *sinfo;
1256 const char *info_sec_name;
1257 __u64 remain_len;
1258 void *data;
1259
1260 record_size = ext_info->rec_size;
1261 sinfo = ext_info->info;
1262 remain_len = ext_info->len;
1263 while (remain_len > 0) {
1264 records_len = sinfo->num_info * record_size;
1265 info_sec_name = btf__name_by_offset(btf, sinfo->sec_name_off);
1266 if (strcmp(info_sec_name, sec_name)) {
1267 remain_len -= sec_hdrlen + records_len;
1268 sinfo = (void *)sinfo + sec_hdrlen + records_len;
1269 continue;
1270 }
1271
1272 existing_len = (*cnt) * record_size;
1273 data = realloc(*info, existing_len + records_len);
1274 if (!data)
1275 return -ENOMEM;
1276
1277 memcpy(data + existing_len, sinfo->data, records_len);
1278 /* adjust insn_off only, the rest data will be passed
1279 * to the kernel.
1280 */
1281 for (i = 0; i < sinfo->num_info; i++) {
1282 __u32 *insn_off;
1283
1284 insn_off = data + existing_len + (i * record_size);
1285 *insn_off = *insn_off / sizeof(struct bpf_insn) +
1286 insns_cnt;
1287 }
1288 *info = data;
1289 *cnt += sinfo->num_info;
1290 return 0;
1291 }
1292
1293 return -ENOENT;
1294}
1295
1296int btf_ext__reloc_func_info(const struct btf *btf,
1297 const struct btf_ext *btf_ext,
1298 const char *sec_name, __u32 insns_cnt,
1299 void **func_info, __u32 *cnt)
1300{
1301 return btf_ext_reloc_info(btf, &btf_ext->func_info, sec_name,
1302 insns_cnt, func_info, cnt);
1303}
1304
1305int btf_ext__reloc_line_info(const struct btf *btf,
1306 const struct btf_ext *btf_ext,
1307 const char *sec_name, __u32 insns_cnt,
1308 void **line_info, __u32 *cnt)
1309{
1310 return btf_ext_reloc_info(btf, &btf_ext->line_info, sec_name,
1311 insns_cnt, line_info, cnt);
1312}
1313
1314__u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext)
1315{
1316 return btf_ext->func_info.rec_size;
1317}
1318
1319__u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext)
1320{
1321 return btf_ext->line_info.rec_size;
1322}
1323
1324struct btf_dedup;
1325
1326static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
1327 const struct btf_dedup_opts *opts);
1328static void btf_dedup_free(struct btf_dedup *d);
1329static int btf_dedup_strings(struct btf_dedup *d);
1330static int btf_dedup_prim_types(struct btf_dedup *d);
1331static int btf_dedup_struct_types(struct btf_dedup *d);
1332static int btf_dedup_ref_types(struct btf_dedup *d);
1333static int btf_dedup_compact_types(struct btf_dedup *d);
1334static int btf_dedup_remap_types(struct btf_dedup *d);
1335
1336/*
1337 * Deduplicate BTF types and strings.
1338 *
1339 * BTF dedup algorithm takes as an input `struct btf` representing `.BTF` ELF
1340 * section with all BTF type descriptors and string data. It overwrites that
1341 * memory in-place with deduplicated types and strings without any loss of
1342 * information. If optional `struct btf_ext` representing '.BTF.ext' ELF section
1343 * is provided, all the strings referenced from .BTF.ext section are honored
1344 * and updated to point to the right offsets after deduplication.
1345 *
1346 * If function returns with error, type/string data might be garbled and should
1347 * be discarded.
1348 *
1349 * More verbose and detailed description of both problem btf_dedup is solving,
1350 * as well as solution could be found at:
1351 * https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
1352 *
1353 * Problem description and justification
1354 * =====================================
1355 *
1356 * BTF type information is typically emitted either as a result of conversion
1357 * from DWARF to BTF or directly by compiler. In both cases, each compilation
1358 * unit contains information about a subset of all the types that are used
1359 * in an application. These subsets are frequently overlapping and contain a lot
1360 * of duplicated information when later concatenated together into a single
1361 * binary. This algorithm ensures that each unique type is represented by single
1362 * BTF type descriptor, greatly reducing resulting size of BTF data.
1363 *
1364 * Compilation unit isolation and subsequent duplication of data is not the only
1365 * problem. The same type hierarchy (e.g., struct and all the type that struct
1366 * references) in different compilation units can be represented in BTF to
1367 * various degrees of completeness (or, rather, incompleteness) due to
1368 * struct/union forward declarations.
1369 *
1370 * Let's take a look at an example, that we'll use to better understand the
1371 * problem (and solution). Suppose we have two compilation units, each using
1372 * same `struct S`, but each of them having incomplete type information about
1373 * struct's fields:
1374 *
1375 * // CU #1:
1376 * struct S;
1377 * struct A {
1378 * int a;
1379 * struct A* self;
1380 * struct S* parent;
1381 * };
1382 * struct B;
1383 * struct S {
1384 * struct A* a_ptr;
1385 * struct B* b_ptr;
1386 * };
1387 *
1388 * // CU #2:
1389 * struct S;
1390 * struct A;
1391 * struct B {
1392 * int b;
1393 * struct B* self;
1394 * struct S* parent;
1395 * };
1396 * struct S {
1397 * struct A* a_ptr;
1398 * struct B* b_ptr;
1399 * };
1400 *
1401 * In case of CU #1, BTF data will know only that `struct B` exist (but no
1402 * more), but will know the complete type information about `struct A`. While
1403 * for CU #2, it will know full type information about `struct B`, but will
1404 * only know about forward declaration of `struct A` (in BTF terms, it will
1405 * have `BTF_KIND_FWD` type descriptor with name `B`).
1406 *
1407 * This compilation unit isolation means that it's possible that there is no
1408 * single CU with complete type information describing structs `S`, `A`, and
1409 * `B`. Also, we might get tons of duplicated and redundant type information.
1410 *
1411 * Additional complication we need to keep in mind comes from the fact that
1412 * types, in general, can form graphs containing cycles, not just DAGs.
1413 *
1414 * While algorithm does deduplication, it also merges and resolves type
1415 * information (unless disabled throught `struct btf_opts`), whenever possible.
1416 * E.g., in the example above with two compilation units having partial type
1417 * information for structs `A` and `B`, the output of algorithm will emit
1418 * a single copy of each BTF type that describes structs `A`, `B`, and `S`
1419 * (as well as type information for `int` and pointers), as if they were defined
1420 * in a single compilation unit as:
1421 *
1422 * struct A {
1423 * int a;
1424 * struct A* self;
1425 * struct S* parent;
1426 * };
1427 * struct B {
1428 * int b;
1429 * struct B* self;
1430 * struct S* parent;
1431 * };
1432 * struct S {
1433 * struct A* a_ptr;
1434 * struct B* b_ptr;
1435 * };
1436 *
1437 * Algorithm summary
1438 * =================
1439 *
1440 * Algorithm completes its work in 6 separate passes:
1441 *
1442 * 1. Strings deduplication.
1443 * 2. Primitive types deduplication (int, enum, fwd).
1444 * 3. Struct/union types deduplication.
1445 * 4. Reference types deduplication (pointers, typedefs, arrays, funcs, func
1446 * protos, and const/volatile/restrict modifiers).
1447 * 5. Types compaction.
1448 * 6. Types remapping.
1449 *
1450 * Algorithm determines canonical type descriptor, which is a single
1451 * representative type for each truly unique type. This canonical type is the
1452 * one that will go into final deduplicated BTF type information. For
1453 * struct/unions, it is also the type that algorithm will merge additional type
1454 * information into (while resolving FWDs), as it discovers it from data in
1455 * other CUs. Each input BTF type eventually gets either mapped to itself, if
1456 * that type is canonical, or to some other type, if that type is equivalent
1457 * and was chosen as canonical representative. This mapping is stored in
1458 * `btf_dedup->map` array. This map is also used to record STRUCT/UNION that
1459 * FWD type got resolved to.
1460 *
1461 * To facilitate fast discovery of canonical types, we also maintain canonical
1462 * index (`btf_dedup->dedup_table`), which maps type descriptor's signature hash
1463 * (i.e., hashed kind, name, size, fields, etc) into a list of canonical types
1464 * that match that signature. With sufficiently good choice of type signature
1465 * hashing function, we can limit number of canonical types for each unique type
1466 * signature to a very small number, allowing to find canonical type for any
1467 * duplicated type very quickly.
1468 *
1469 * Struct/union deduplication is the most critical part and algorithm for
1470 * deduplicating structs/unions is described in greater details in comments for
1471 * `btf_dedup_is_equiv` function.
1472 */
1473int btf__dedup(struct btf *btf, struct btf_ext *btf_ext,
1474 const struct btf_dedup_opts *opts)
1475{
1476 struct btf_dedup *d = btf_dedup_new(btf, btf_ext, opts);
1477 int err;
1478
1479 if (IS_ERR(d)) {
1480 pr_debug("btf_dedup_new failed: %ld", PTR_ERR(d));
1481 return -EINVAL;
1482 }
1483
1484 err = btf_dedup_strings(d);
1485 if (err < 0) {
1486 pr_debug("btf_dedup_strings failed:%d\n", err);
1487 goto done;
1488 }
1489 err = btf_dedup_prim_types(d);
1490 if (err < 0) {
1491 pr_debug("btf_dedup_prim_types failed:%d\n", err);
1492 goto done;
1493 }
1494 err = btf_dedup_struct_types(d);
1495 if (err < 0) {
1496 pr_debug("btf_dedup_struct_types failed:%d\n", err);
1497 goto done;
1498 }
1499 err = btf_dedup_ref_types(d);
1500 if (err < 0) {
1501 pr_debug("btf_dedup_ref_types failed:%d\n", err);
1502 goto done;
1503 }
1504 err = btf_dedup_compact_types(d);
1505 if (err < 0) {
1506 pr_debug("btf_dedup_compact_types failed:%d\n", err);
1507 goto done;
1508 }
1509 err = btf_dedup_remap_types(d);
1510 if (err < 0) {
1511 pr_debug("btf_dedup_remap_types failed:%d\n", err);
1512 goto done;
1513 }
1514
1515done:
1516 btf_dedup_free(d);
1517 return err;
1518}
1519
1520#define BTF_UNPROCESSED_ID ((__u32)-1)
1521#define BTF_IN_PROGRESS_ID ((__u32)-2)
1522
1523struct btf_dedup {
1524 /* .BTF section to be deduped in-place */
1525 struct btf *btf;
1526 /*
1527 * Optional .BTF.ext section. When provided, any strings referenced
1528 * from it will be taken into account when deduping strings
1529 */
1530 struct btf_ext *btf_ext;
1531 /*
1532 * This is a map from any type's signature hash to a list of possible
1533 * canonical representative type candidates. Hash collisions are
1534 * ignored, so even types of various kinds can share same list of
1535 * candidates, which is fine because we rely on subsequent
1536 * btf_xxx_equal() checks to authoritatively verify type equality.
1537 */
1538 struct hashmap *dedup_table;
1539 /* Canonical types map */
1540 __u32 *map;
1541 /* Hypothetical mapping, used during type graph equivalence checks */
1542 __u32 *hypot_map;
1543 __u32 *hypot_list;
1544 size_t hypot_cnt;
1545 size_t hypot_cap;
1546 /* Various option modifying behavior of algorithm */
1547 struct btf_dedup_opts opts;
1548};
1549
1550struct btf_str_ptr {
1551 const char *str;
1552 __u32 new_off;
1553 bool used;
1554};
1555
1556struct btf_str_ptrs {
1557 struct btf_str_ptr *ptrs;
1558 const char *data;
1559 __u32 cnt;
1560 __u32 cap;
1561};
1562
1563static long hash_combine(long h, long value)
1564{
1565 return h * 31 + value;
1566}
1567
1568#define for_each_dedup_cand(d, node, hash) \
1569 hashmap__for_each_key_entry(d->dedup_table, node, (void *)hash)
1570
1571static int btf_dedup_table_add(struct btf_dedup *d, long hash, __u32 type_id)
1572{
1573 return hashmap__append(d->dedup_table,
1574 (void *)hash, (void *)(long)type_id);
1575}
1576
1577static int btf_dedup_hypot_map_add(struct btf_dedup *d,
1578 __u32 from_id, __u32 to_id)
1579{
1580 if (d->hypot_cnt == d->hypot_cap) {
1581 __u32 *new_list;
1582
1583 d->hypot_cap += max((size_t)16, d->hypot_cap / 2);
1584 new_list = realloc(d->hypot_list, sizeof(__u32) * d->hypot_cap);
1585 if (!new_list)
1586 return -ENOMEM;
1587 d->hypot_list = new_list;
1588 }
1589 d->hypot_list[d->hypot_cnt++] = from_id;
1590 d->hypot_map[from_id] = to_id;
1591 return 0;
1592}
1593
1594static void btf_dedup_clear_hypot_map(struct btf_dedup *d)
1595{
1596 int i;
1597
1598 for (i = 0; i < d->hypot_cnt; i++)
1599 d->hypot_map[d->hypot_list[i]] = BTF_UNPROCESSED_ID;
1600 d->hypot_cnt = 0;
1601}
1602
1603static void btf_dedup_free(struct btf_dedup *d)
1604{
1605 hashmap__free(d->dedup_table);
1606 d->dedup_table = NULL;
1607
1608 free(d->map);
1609 d->map = NULL;
1610
1611 free(d->hypot_map);
1612 d->hypot_map = NULL;
1613
1614 free(d->hypot_list);
1615 d->hypot_list = NULL;
1616
1617 free(d);
1618}
1619
1620static size_t btf_dedup_identity_hash_fn(const void *key, void *ctx)
1621{
1622 return (size_t)key;
1623}
1624
1625static size_t btf_dedup_collision_hash_fn(const void *key, void *ctx)
1626{
1627 return 0;
1628}
1629
1630static bool btf_dedup_equal_fn(const void *k1, const void *k2, void *ctx)
1631{
1632 return k1 == k2;
1633}
1634
1635static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
1636 const struct btf_dedup_opts *opts)
1637{
1638 struct btf_dedup *d = calloc(1, sizeof(struct btf_dedup));
1639 hashmap_hash_fn hash_fn = btf_dedup_identity_hash_fn;
1640 int i, err = 0;
1641
1642 if (!d)
1643 return ERR_PTR(-ENOMEM);
1644
1645 d->opts.dont_resolve_fwds = opts && opts->dont_resolve_fwds;
1646 /* dedup_table_size is now used only to force collisions in tests */
1647 if (opts && opts->dedup_table_size == 1)
1648 hash_fn = btf_dedup_collision_hash_fn;
1649
1650 d->btf = btf;
1651 d->btf_ext = btf_ext;
1652
1653 d->dedup_table = hashmap__new(hash_fn, btf_dedup_equal_fn, NULL);
1654 if (IS_ERR(d->dedup_table)) {
1655 err = PTR_ERR(d->dedup_table);
1656 d->dedup_table = NULL;
1657 goto done;
1658 }
1659
1660 d->map = malloc(sizeof(__u32) * (1 + btf->nr_types));
1661 if (!d->map) {
1662 err = -ENOMEM;
1663 goto done;
1664 }
1665 /* special BTF "void" type is made canonical immediately */
1666 d->map[0] = 0;
1667 for (i = 1; i <= btf->nr_types; i++) {
1668 struct btf_type *t = d->btf->types[i];
1669
1670 /* VAR and DATASEC are never deduped and are self-canonical */
1671 if (btf_is_var(t) || btf_is_datasec(t))
1672 d->map[i] = i;
1673 else
1674 d->map[i] = BTF_UNPROCESSED_ID;
1675 }
1676
1677 d->hypot_map = malloc(sizeof(__u32) * (1 + btf->nr_types));
1678 if (!d->hypot_map) {
1679 err = -ENOMEM;
1680 goto done;
1681 }
1682 for (i = 0; i <= btf->nr_types; i++)
1683 d->hypot_map[i] = BTF_UNPROCESSED_ID;
1684
1685done:
1686 if (err) {
1687 btf_dedup_free(d);
1688 return ERR_PTR(err);
1689 }
1690
1691 return d;
1692}
1693
1694typedef int (*str_off_fn_t)(__u32 *str_off_ptr, void *ctx);
1695
1696/*
1697 * Iterate over all possible places in .BTF and .BTF.ext that can reference
1698 * string and pass pointer to it to a provided callback `fn`.
1699 */
1700static int btf_for_each_str_off(struct btf_dedup *d, str_off_fn_t fn, void *ctx)
1701{
1702 void *line_data_cur, *line_data_end;
1703 int i, j, r, rec_size;
1704 struct btf_type *t;
1705
1706 for (i = 1; i <= d->btf->nr_types; i++) {
1707 t = d->btf->types[i];
1708 r = fn(&t->name_off, ctx);
1709 if (r)
1710 return r;
1711
1712 switch (btf_kind(t)) {
1713 case BTF_KIND_STRUCT:
1714 case BTF_KIND_UNION: {
1715 struct btf_member *m = btf_members(t);
1716 __u16 vlen = btf_vlen(t);
1717
1718 for (j = 0; j < vlen; j++) {
1719 r = fn(&m->name_off, ctx);
1720 if (r)
1721 return r;
1722 m++;
1723 }
1724 break;
1725 }
1726 case BTF_KIND_ENUM: {
1727 struct btf_enum *m = btf_enum(t);
1728 __u16 vlen = btf_vlen(t);
1729
1730 for (j = 0; j < vlen; j++) {
1731 r = fn(&m->name_off, ctx);
1732 if (r)
1733 return r;
1734 m++;
1735 }
1736 break;
1737 }
1738 case BTF_KIND_FUNC_PROTO: {
1739 struct btf_param *m = btf_params(t);
1740 __u16 vlen = btf_vlen(t);
1741
1742 for (j = 0; j < vlen; j++) {
1743 r = fn(&m->name_off, ctx);
1744 if (r)
1745 return r;
1746 m++;
1747 }
1748 break;
1749 }
1750 default:
1751 break;
1752 }
1753 }
1754
1755 if (!d->btf_ext)
1756 return 0;
1757
1758 line_data_cur = d->btf_ext->line_info.info;
1759 line_data_end = d->btf_ext->line_info.info + d->btf_ext->line_info.len;
1760 rec_size = d->btf_ext->line_info.rec_size;
1761
1762 while (line_data_cur < line_data_end) {
1763 struct btf_ext_info_sec *sec = line_data_cur;
1764 struct bpf_line_info_min *line_info;
1765 __u32 num_info = sec->num_info;
1766
1767 r = fn(&sec->sec_name_off, ctx);
1768 if (r)
1769 return r;
1770
1771 line_data_cur += sizeof(struct btf_ext_info_sec);
1772 for (i = 0; i < num_info; i++) {
1773 line_info = line_data_cur;
1774 r = fn(&line_info->file_name_off, ctx);
1775 if (r)
1776 return r;
1777 r = fn(&line_info->line_off, ctx);
1778 if (r)
1779 return r;
1780 line_data_cur += rec_size;
1781 }
1782 }
1783
1784 return 0;
1785}
1786
1787static int str_sort_by_content(const void *a1, const void *a2)
1788{
1789 const struct btf_str_ptr *p1 = a1;
1790 const struct btf_str_ptr *p2 = a2;
1791
1792 return strcmp(p1->str, p2->str);
1793}
1794
1795static int str_sort_by_offset(const void *a1, const void *a2)
1796{
1797 const struct btf_str_ptr *p1 = a1;
1798 const struct btf_str_ptr *p2 = a2;
1799
1800 if (p1->str != p2->str)
1801 return p1->str < p2->str ? -1 : 1;
1802 return 0;
1803}
1804
1805static int btf_dedup_str_ptr_cmp(const void *str_ptr, const void *pelem)
1806{
1807 const struct btf_str_ptr *p = pelem;
1808
1809 if (str_ptr != p->str)
1810 return (const char *)str_ptr < p->str ? -1 : 1;
1811 return 0;
1812}
1813
1814static int btf_str_mark_as_used(__u32 *str_off_ptr, void *ctx)
1815{
1816 struct btf_str_ptrs *strs;
1817 struct btf_str_ptr *s;
1818
1819 if (*str_off_ptr == 0)
1820 return 0;
1821
1822 strs = ctx;
1823 s = bsearch(strs->data + *str_off_ptr, strs->ptrs, strs->cnt,
1824 sizeof(struct btf_str_ptr), btf_dedup_str_ptr_cmp);
1825 if (!s)
1826 return -EINVAL;
1827 s->used = true;
1828 return 0;
1829}
1830
1831static int btf_str_remap_offset(__u32 *str_off_ptr, void *ctx)
1832{
1833 struct btf_str_ptrs *strs;
1834 struct btf_str_ptr *s;
1835
1836 if (*str_off_ptr == 0)
1837 return 0;
1838
1839 strs = ctx;
1840 s = bsearch(strs->data + *str_off_ptr, strs->ptrs, strs->cnt,
1841 sizeof(struct btf_str_ptr), btf_dedup_str_ptr_cmp);
1842 if (!s)
1843 return -EINVAL;
1844 *str_off_ptr = s->new_off;
1845 return 0;
1846}
1847
1848/*
1849 * Dedup string and filter out those that are not referenced from either .BTF
1850 * or .BTF.ext (if provided) sections.
1851 *
1852 * This is done by building index of all strings in BTF's string section,
1853 * then iterating over all entities that can reference strings (e.g., type
1854 * names, struct field names, .BTF.ext line info, etc) and marking corresponding
1855 * strings as used. After that all used strings are deduped and compacted into
1856 * sequential blob of memory and new offsets are calculated. Then all the string
1857 * references are iterated again and rewritten using new offsets.
1858 */
1859static int btf_dedup_strings(struct btf_dedup *d)
1860{
1861 const struct btf_header *hdr = d->btf->hdr;
1862 char *start = (char *)d->btf->nohdr_data + hdr->str_off;
1863 char *end = start + d->btf->hdr->str_len;
1864 char *p = start, *tmp_strs = NULL;
1865 struct btf_str_ptrs strs = {
1866 .cnt = 0,
1867 .cap = 0,
1868 .ptrs = NULL,
1869 .data = start,
1870 };
1871 int i, j, err = 0, grp_idx;
1872 bool grp_used;
1873
1874 /* build index of all strings */
1875 while (p < end) {
1876 if (strs.cnt + 1 > strs.cap) {
1877 struct btf_str_ptr *new_ptrs;
1878
1879 strs.cap += max(strs.cnt / 2, 16U);
1880 new_ptrs = realloc(strs.ptrs,
1881 sizeof(strs.ptrs[0]) * strs.cap);
1882 if (!new_ptrs) {
1883 err = -ENOMEM;
1884 goto done;
1885 }
1886 strs.ptrs = new_ptrs;
1887 }
1888
1889 strs.ptrs[strs.cnt].str = p;
1890 strs.ptrs[strs.cnt].used = false;
1891
1892 p += strlen(p) + 1;
1893 strs.cnt++;
1894 }
1895
1896 /* temporary storage for deduplicated strings */
1897 tmp_strs = malloc(d->btf->hdr->str_len);
1898 if (!tmp_strs) {
1899 err = -ENOMEM;
1900 goto done;
1901 }
1902
1903 /* mark all used strings */
1904 strs.ptrs[0].used = true;
1905 err = btf_for_each_str_off(d, btf_str_mark_as_used, &strs);
1906 if (err)
1907 goto done;
1908
1909 /* sort strings by context, so that we can identify duplicates */
1910 qsort(strs.ptrs, strs.cnt, sizeof(strs.ptrs[0]), str_sort_by_content);
1911
1912 /*
1913 * iterate groups of equal strings and if any instance in a group was
1914 * referenced, emit single instance and remember new offset
1915 */
1916 p = tmp_strs;
1917 grp_idx = 0;
1918 grp_used = strs.ptrs[0].used;
1919 /* iterate past end to avoid code duplication after loop */
1920 for (i = 1; i <= strs.cnt; i++) {
1921 /*
1922 * when i == strs.cnt, we want to skip string comparison and go
1923 * straight to handling last group of strings (otherwise we'd
1924 * need to handle last group after the loop w/ duplicated code)
1925 */
1926 if (i < strs.cnt &&
1927 !strcmp(strs.ptrs[i].str, strs.ptrs[grp_idx].str)) {
1928 grp_used = grp_used || strs.ptrs[i].used;
1929 continue;
1930 }
1931
1932 /*
1933 * this check would have been required after the loop to handle
1934 * last group of strings, but due to <= condition in a loop
1935 * we avoid that duplication
1936 */
1937 if (grp_used) {
1938 int new_off = p - tmp_strs;
1939 __u32 len = strlen(strs.ptrs[grp_idx].str);
1940
1941 memmove(p, strs.ptrs[grp_idx].str, len + 1);
1942 for (j = grp_idx; j < i; j++)
1943 strs.ptrs[j].new_off = new_off;
1944 p += len + 1;
1945 }
1946
1947 if (i < strs.cnt) {
1948 grp_idx = i;
1949 grp_used = strs.ptrs[i].used;
1950 }
1951 }
1952
1953 /* replace original strings with deduped ones */
1954 d->btf->hdr->str_len = p - tmp_strs;
1955 memmove(start, tmp_strs, d->btf->hdr->str_len);
1956 end = start + d->btf->hdr->str_len;
1957
1958 /* restore original order for further binary search lookups */
1959 qsort(strs.ptrs, strs.cnt, sizeof(strs.ptrs[0]), str_sort_by_offset);
1960
1961 /* remap string offsets */
1962 err = btf_for_each_str_off(d, btf_str_remap_offset, &strs);
1963 if (err)
1964 goto done;
1965
1966 d->btf->hdr->str_len = end - start;
1967
1968done:
1969 free(tmp_strs);
1970 free(strs.ptrs);
1971 return err;
1972}
1973
1974static long btf_hash_common(struct btf_type *t)
1975{
1976 long h;
1977
1978 h = hash_combine(0, t->name_off);
1979 h = hash_combine(h, t->info);
1980 h = hash_combine(h, t->size);
1981 return h;
1982}
1983
1984static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
1985{
1986 return t1->name_off == t2->name_off &&
1987 t1->info == t2->info &&
1988 t1->size == t2->size;
1989}
1990
1991/* Calculate type signature hash of INT. */
1992static long btf_hash_int(struct btf_type *t)
1993{
1994 __u32 info = *(__u32 *)(t + 1);
1995 long h;
1996
1997 h = btf_hash_common(t);
1998 h = hash_combine(h, info);
1999 return h;
2000}
2001
2002/* Check structural equality of two INTs. */
2003static bool btf_equal_int(struct btf_type *t1, struct btf_type *t2)
2004{
2005 __u32 info1, info2;
2006
2007 if (!btf_equal_common(t1, t2))
2008 return false;
2009 info1 = *(__u32 *)(t1 + 1);
2010 info2 = *(__u32 *)(t2 + 1);
2011 return info1 == info2;
2012}
2013
2014/* Calculate type signature hash of ENUM. */
2015static long btf_hash_enum(struct btf_type *t)
2016{
2017 long h;
2018
2019 /* don't hash vlen and enum members to support enum fwd resolving */
2020 h = hash_combine(0, t->name_off);
2021 h = hash_combine(h, t->info & ~0xffff);
2022 h = hash_combine(h, t->size);
2023 return h;
2024}
2025
2026/* Check structural equality of two ENUMs. */
2027static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
2028{
2029 const struct btf_enum *m1, *m2;
2030 __u16 vlen;
2031 int i;
2032
2033 if (!btf_equal_common(t1, t2))
2034 return false;
2035
2036 vlen = btf_vlen(t1);
2037 m1 = btf_enum(t1);
2038 m2 = btf_enum(t2);
2039 for (i = 0; i < vlen; i++) {
2040 if (m1->name_off != m2->name_off || m1->val != m2->val)
2041 return false;
2042 m1++;
2043 m2++;
2044 }
2045 return true;
2046}
2047
2048static inline bool btf_is_enum_fwd(struct btf_type *t)
2049{
2050 return btf_is_enum(t) && btf_vlen(t) == 0;
2051}
2052
2053static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
2054{
2055 if (!btf_is_enum_fwd(t1) && !btf_is_enum_fwd(t2))
2056 return btf_equal_enum(t1, t2);
2057 /* ignore vlen when comparing */
2058 return t1->name_off == t2->name_off &&
2059 (t1->info & ~0xffff) == (t2->info & ~0xffff) &&
2060 t1->size == t2->size;
2061}
2062
2063/*
2064 * Calculate type signature hash of STRUCT/UNION, ignoring referenced type IDs,
2065 * as referenced type IDs equivalence is established separately during type
2066 * graph equivalence check algorithm.
2067 */
2068static long btf_hash_struct(struct btf_type *t)
2069{
2070 const struct btf_member *member = btf_members(t);
2071 __u32 vlen = btf_vlen(t);
2072 long h = btf_hash_common(t);
2073 int i;
2074
2075 for (i = 0; i < vlen; i++) {
2076 h = hash_combine(h, member->name_off);
2077 h = hash_combine(h, member->offset);
2078 /* no hashing of referenced type ID, it can be unresolved yet */
2079 member++;
2080 }
2081 return h;
2082}
2083
2084/*
2085 * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
2086 * IDs. This check is performed during type graph equivalence check and
2087 * referenced types equivalence is checked separately.
2088 */
2089static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
2090{
2091 const struct btf_member *m1, *m2;
2092 __u16 vlen;
2093 int i;
2094
2095 if (!btf_equal_common(t1, t2))
2096 return false;
2097
2098 vlen = btf_vlen(t1);
2099 m1 = btf_members(t1);
2100 m2 = btf_members(t2);
2101 for (i = 0; i < vlen; i++) {
2102 if (m1->name_off != m2->name_off || m1->offset != m2->offset)
2103 return false;
2104 m1++;
2105 m2++;
2106 }
2107 return true;
2108}
2109
2110/*
2111 * Calculate type signature hash of ARRAY, including referenced type IDs,
2112 * under assumption that they were already resolved to canonical type IDs and
2113 * are not going to change.
2114 */
2115static long btf_hash_array(struct btf_type *t)
2116{
2117 const struct btf_array *info = btf_array(t);
2118 long h = btf_hash_common(t);
2119
2120 h = hash_combine(h, info->type);
2121 h = hash_combine(h, info->index_type);
2122 h = hash_combine(h, info->nelems);
2123 return h;
2124}
2125
2126/*
2127 * Check exact equality of two ARRAYs, taking into account referenced
2128 * type IDs, under assumption that they were already resolved to canonical
2129 * type IDs and are not going to change.
2130 * This function is called during reference types deduplication to compare
2131 * ARRAY to potential canonical representative.
2132 */
2133static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
2134{
2135 const struct btf_array *info1, *info2;
2136
2137 if (!btf_equal_common(t1, t2))
2138 return false;
2139
2140 info1 = btf_array(t1);
2141 info2 = btf_array(t2);
2142 return info1->type == info2->type &&
2143 info1->index_type == info2->index_type &&
2144 info1->nelems == info2->nelems;
2145}
2146
2147/*
2148 * Check structural compatibility of two ARRAYs, ignoring referenced type
2149 * IDs. This check is performed during type graph equivalence check and
2150 * referenced types equivalence is checked separately.
2151 */
2152static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
2153{
2154 if (!btf_equal_common(t1, t2))
2155 return false;
2156
2157 return btf_array(t1)->nelems == btf_array(t2)->nelems;
2158}
2159
2160/*
2161 * Calculate type signature hash of FUNC_PROTO, including referenced type IDs,
2162 * under assumption that they were already resolved to canonical type IDs and
2163 * are not going to change.
2164 */
2165static long btf_hash_fnproto(struct btf_type *t)
2166{
2167 const struct btf_param *member = btf_params(t);
2168 __u16 vlen = btf_vlen(t);
2169 long h = btf_hash_common(t);
2170 int i;
2171
2172 for (i = 0; i < vlen; i++) {
2173 h = hash_combine(h, member->name_off);
2174 h = hash_combine(h, member->type);
2175 member++;
2176 }
2177 return h;
2178}
2179
2180/*
2181 * Check exact equality of two FUNC_PROTOs, taking into account referenced
2182 * type IDs, under assumption that they were already resolved to canonical
2183 * type IDs and are not going to change.
2184 * This function is called during reference types deduplication to compare
2185 * FUNC_PROTO to potential canonical representative.
2186 */
2187static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
2188{
2189 const struct btf_param *m1, *m2;
2190 __u16 vlen;
2191 int i;
2192
2193 if (!btf_equal_common(t1, t2))
2194 return false;
2195
2196 vlen = btf_vlen(t1);
2197 m1 = btf_params(t1);
2198 m2 = btf_params(t2);
2199 for (i = 0; i < vlen; i++) {
2200 if (m1->name_off != m2->name_off || m1->type != m2->type)
2201 return false;
2202 m1++;
2203 m2++;
2204 }
2205 return true;
2206}
2207
2208/*
2209 * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
2210 * IDs. This check is performed during type graph equivalence check and
2211 * referenced types equivalence is checked separately.
2212 */
2213static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
2214{
2215 const struct btf_param *m1, *m2;
2216 __u16 vlen;
2217 int i;
2218
2219 /* skip return type ID */
2220 if (t1->name_off != t2->name_off || t1->info != t2->info)
2221 return false;
2222
2223 vlen = btf_vlen(t1);
2224 m1 = btf_params(t1);
2225 m2 = btf_params(t2);
2226 for (i = 0; i < vlen; i++) {
2227 if (m1->name_off != m2->name_off)
2228 return false;
2229 m1++;
2230 m2++;
2231 }
2232 return true;
2233}
2234
2235/*
2236 * Deduplicate primitive types, that can't reference other types, by calculating
2237 * their type signature hash and comparing them with any possible canonical
2238 * candidate. If no canonical candidate matches, type itself is marked as
2239 * canonical and is added into `btf_dedup->dedup_table` as another candidate.
2240 */
2241static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
2242{
2243 struct btf_type *t = d->btf->types[type_id];
2244 struct hashmap_entry *hash_entry;
2245 struct btf_type *cand;
2246 /* if we don't find equivalent type, then we are canonical */
2247 __u32 new_id = type_id;
2248 __u32 cand_id;
2249 long h;
2250
2251 switch (btf_kind(t)) {
2252 case BTF_KIND_CONST:
2253 case BTF_KIND_VOLATILE:
2254 case BTF_KIND_RESTRICT:
2255 case BTF_KIND_PTR:
2256 case BTF_KIND_TYPEDEF:
2257 case BTF_KIND_ARRAY:
2258 case BTF_KIND_STRUCT:
2259 case BTF_KIND_UNION:
2260 case BTF_KIND_FUNC:
2261 case BTF_KIND_FUNC_PROTO:
2262 case BTF_KIND_VAR:
2263 case BTF_KIND_DATASEC:
2264 return 0;
2265
2266 case BTF_KIND_INT:
2267 h = btf_hash_int(t);
2268 for_each_dedup_cand(d, hash_entry, h) {
2269 cand_id = (__u32)(long)hash_entry->value;
2270 cand = d->btf->types[cand_id];
2271 if (btf_equal_int(t, cand)) {
2272 new_id = cand_id;
2273 break;
2274 }
2275 }
2276 break;
2277
2278 case BTF_KIND_ENUM:
2279 h = btf_hash_enum(t);
2280 for_each_dedup_cand(d, hash_entry, h) {
2281 cand_id = (__u32)(long)hash_entry->value;
2282 cand = d->btf->types[cand_id];
2283 if (btf_equal_enum(t, cand)) {
2284 new_id = cand_id;
2285 break;
2286 }
2287 if (d->opts.dont_resolve_fwds)
2288 continue;
2289 if (btf_compat_enum(t, cand)) {
2290 if (btf_is_enum_fwd(t)) {
2291 /* resolve fwd to full enum */
2292 new_id = cand_id;
2293 break;
2294 }
2295 /* resolve canonical enum fwd to full enum */
2296 d->map[cand_id] = type_id;
2297 }
2298 }
2299 break;
2300
2301 case BTF_KIND_FWD:
2302 h = btf_hash_common(t);
2303 for_each_dedup_cand(d, hash_entry, h) {
2304 cand_id = (__u32)(long)hash_entry->value;
2305 cand = d->btf->types[cand_id];
2306 if (btf_equal_common(t, cand)) {
2307 new_id = cand_id;
2308 break;
2309 }
2310 }
2311 break;
2312
2313 default:
2314 return -EINVAL;
2315 }
2316
2317 d->map[type_id] = new_id;
2318 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
2319 return -ENOMEM;
2320
2321 return 0;
2322}
2323
2324static int btf_dedup_prim_types(struct btf_dedup *d)
2325{
2326 int i, err;
2327
2328 for (i = 1; i <= d->btf->nr_types; i++) {
2329 err = btf_dedup_prim_type(d, i);
2330 if (err)
2331 return err;
2332 }
2333 return 0;
2334}
2335
2336/*
2337 * Check whether type is already mapped into canonical one (could be to itself).
2338 */
2339static inline bool is_type_mapped(struct btf_dedup *d, uint32_t type_id)
2340{
2341 return d->map[type_id] <= BTF_MAX_NR_TYPES;
2342}
2343
2344/*
2345 * Resolve type ID into its canonical type ID, if any; otherwise return original
2346 * type ID. If type is FWD and is resolved into STRUCT/UNION already, follow
2347 * STRUCT/UNION link and resolve it into canonical type ID as well.
2348 */
2349static inline __u32 resolve_type_id(struct btf_dedup *d, __u32 type_id)
2350{
2351 while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
2352 type_id = d->map[type_id];
2353 return type_id;
2354}
2355
2356/*
2357 * Resolve FWD to underlying STRUCT/UNION, if any; otherwise return original
2358 * type ID.
2359 */
2360static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
2361{
2362 __u32 orig_type_id = type_id;
2363
2364 if (!btf_is_fwd(d->btf->types[type_id]))
2365 return type_id;
2366
2367 while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
2368 type_id = d->map[type_id];
2369
2370 if (!btf_is_fwd(d->btf->types[type_id]))
2371 return type_id;
2372
2373 return orig_type_id;
2374}
2375
2376
2377static inline __u16 btf_fwd_kind(struct btf_type *t)
2378{
2379 return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
2380}
2381
2382/*
2383 * Check equivalence of BTF type graph formed by candidate struct/union (we'll
2384 * call it "candidate graph" in this description for brevity) to a type graph
2385 * formed by (potential) canonical struct/union ("canonical graph" for brevity
2386 * here, though keep in mind that not all types in canonical graph are
2387 * necessarily canonical representatives themselves, some of them might be
2388 * duplicates or its uniqueness might not have been established yet).
2389 * Returns:
2390 * - >0, if type graphs are equivalent;
2391 * - 0, if not equivalent;
2392 * - <0, on error.
2393 *
2394 * Algorithm performs side-by-side DFS traversal of both type graphs and checks
2395 * equivalence of BTF types at each step. If at any point BTF types in candidate
2396 * and canonical graphs are not compatible structurally, whole graphs are
2397 * incompatible. If types are structurally equivalent (i.e., all information
2398 * except referenced type IDs is exactly the same), a mapping from `canon_id` to
2399 * a `cand_id` is recored in hypothetical mapping (`btf_dedup->hypot_map`).
2400 * If a type references other types, then those referenced types are checked
2401 * for equivalence recursively.
2402 *
2403 * During DFS traversal, if we find that for current `canon_id` type we
2404 * already have some mapping in hypothetical map, we check for two possible
2405 * situations:
2406 * - `canon_id` is mapped to exactly the same type as `cand_id`. This will
2407 * happen when type graphs have cycles. In this case we assume those two
2408 * types are equivalent.
2409 * - `canon_id` is mapped to different type. This is contradiction in our
2410 * hypothetical mapping, because same graph in canonical graph corresponds
2411 * to two different types in candidate graph, which for equivalent type
2412 * graphs shouldn't happen. This condition terminates equivalence check
2413 * with negative result.
2414 *
2415 * If type graphs traversal exhausts types to check and find no contradiction,
2416 * then type graphs are equivalent.
2417 *
2418 * When checking types for equivalence, there is one special case: FWD types.
2419 * If FWD type resolution is allowed and one of the types (either from canonical
2420 * or candidate graph) is FWD and other is STRUCT/UNION (depending on FWD's kind
2421 * flag) and their names match, hypothetical mapping is updated to point from
2422 * FWD to STRUCT/UNION. If graphs will be determined as equivalent successfully,
2423 * this mapping will be used to record FWD -> STRUCT/UNION mapping permanently.
2424 *
2425 * Technically, this could lead to incorrect FWD to STRUCT/UNION resolution,
2426 * if there are two exactly named (or anonymous) structs/unions that are
2427 * compatible structurally, one of which has FWD field, while other is concrete
2428 * STRUCT/UNION, but according to C sources they are different structs/unions
2429 * that are referencing different types with the same name. This is extremely
2430 * unlikely to happen, but btf_dedup API allows to disable FWD resolution if
2431 * this logic is causing problems.
2432 *
2433 * Doing FWD resolution means that both candidate and/or canonical graphs can
2434 * consists of portions of the graph that come from multiple compilation units.
2435 * This is due to the fact that types within single compilation unit are always
2436 * deduplicated and FWDs are already resolved, if referenced struct/union
2437 * definiton is available. So, if we had unresolved FWD and found corresponding
2438 * STRUCT/UNION, they will be from different compilation units. This
2439 * consequently means that when we "link" FWD to corresponding STRUCT/UNION,
2440 * type graph will likely have at least two different BTF types that describe
2441 * same type (e.g., most probably there will be two different BTF types for the
2442 * same 'int' primitive type) and could even have "overlapping" parts of type
2443 * graph that describe same subset of types.
2444 *
2445 * This in turn means that our assumption that each type in canonical graph
2446 * must correspond to exactly one type in candidate graph might not hold
2447 * anymore and will make it harder to detect contradictions using hypothetical
2448 * map. To handle this problem, we allow to follow FWD -> STRUCT/UNION
2449 * resolution only in canonical graph. FWDs in candidate graphs are never
2450 * resolved. To see why it's OK, let's check all possible situations w.r.t. FWDs
2451 * that can occur:
2452 * - Both types in canonical and candidate graphs are FWDs. If they are
2453 * structurally equivalent, then they can either be both resolved to the
2454 * same STRUCT/UNION or not resolved at all. In both cases they are
2455 * equivalent and there is no need to resolve FWD on candidate side.
2456 * - Both types in canonical and candidate graphs are concrete STRUCT/UNION,
2457 * so nothing to resolve as well, algorithm will check equivalence anyway.
2458 * - Type in canonical graph is FWD, while type in candidate is concrete
2459 * STRUCT/UNION. In this case candidate graph comes from single compilation
2460 * unit, so there is exactly one BTF type for each unique C type. After
2461 * resolving FWD into STRUCT/UNION, there might be more than one BTF type
2462 * in canonical graph mapping to single BTF type in candidate graph, but
2463 * because hypothetical mapping maps from canonical to candidate types, it's
2464 * alright, and we still maintain the property of having single `canon_id`
2465 * mapping to single `cand_id` (there could be two different `canon_id`
2466 * mapped to the same `cand_id`, but it's not contradictory).
2467 * - Type in canonical graph is concrete STRUCT/UNION, while type in candidate
2468 * graph is FWD. In this case we are just going to check compatibility of
2469 * STRUCT/UNION and corresponding FWD, and if they are compatible, we'll
2470 * assume that whatever STRUCT/UNION FWD resolves to must be equivalent to
2471 * a concrete STRUCT/UNION from canonical graph. If the rest of type graphs
2472 * turn out equivalent, we'll re-resolve FWD to concrete STRUCT/UNION from
2473 * canonical graph.
2474 */
2475static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
2476 __u32 canon_id)
2477{
2478 struct btf_type *cand_type;
2479 struct btf_type *canon_type;
2480 __u32 hypot_type_id;
2481 __u16 cand_kind;
2482 __u16 canon_kind;
2483 int i, eq;
2484
2485 /* if both resolve to the same canonical, they must be equivalent */
2486 if (resolve_type_id(d, cand_id) == resolve_type_id(d, canon_id))
2487 return 1;
2488
2489 canon_id = resolve_fwd_id(d, canon_id);
2490
2491 hypot_type_id = d->hypot_map[canon_id];
2492 if (hypot_type_id <= BTF_MAX_NR_TYPES)
2493 return hypot_type_id == cand_id;
2494
2495 if (btf_dedup_hypot_map_add(d, canon_id, cand_id))
2496 return -ENOMEM;
2497
2498 cand_type = d->btf->types[cand_id];
2499 canon_type = d->btf->types[canon_id];
2500 cand_kind = btf_kind(cand_type);
2501 canon_kind = btf_kind(canon_type);
2502
2503 if (cand_type->name_off != canon_type->name_off)
2504 return 0;
2505
2506 /* FWD <--> STRUCT/UNION equivalence check, if enabled */
2507 if (!d->opts.dont_resolve_fwds
2508 && (cand_kind == BTF_KIND_FWD || canon_kind == BTF_KIND_FWD)
2509 && cand_kind != canon_kind) {
2510 __u16 real_kind;
2511 __u16 fwd_kind;
2512
2513 if (cand_kind == BTF_KIND_FWD) {
2514 real_kind = canon_kind;
2515 fwd_kind = btf_fwd_kind(cand_type);
2516 } else {
2517 real_kind = cand_kind;
2518 fwd_kind = btf_fwd_kind(canon_type);
2519 }
2520 return fwd_kind == real_kind;
2521 }
2522
2523 if (cand_kind != canon_kind)
2524 return 0;
2525
2526 switch (cand_kind) {
2527 case BTF_KIND_INT:
2528 return btf_equal_int(cand_type, canon_type);
2529
2530 case BTF_KIND_ENUM:
2531 if (d->opts.dont_resolve_fwds)
2532 return btf_equal_enum(cand_type, canon_type);
2533 else
2534 return btf_compat_enum(cand_type, canon_type);
2535
2536 case BTF_KIND_FWD:
2537 return btf_equal_common(cand_type, canon_type);
2538
2539 case BTF_KIND_CONST:
2540 case BTF_KIND_VOLATILE:
2541 case BTF_KIND_RESTRICT:
2542 case BTF_KIND_PTR:
2543 case BTF_KIND_TYPEDEF:
2544 case BTF_KIND_FUNC:
2545 if (cand_type->info != canon_type->info)
2546 return 0;
2547 return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
2548
2549 case BTF_KIND_ARRAY: {
2550 const struct btf_array *cand_arr, *canon_arr;
2551
2552 if (!btf_compat_array(cand_type, canon_type))
2553 return 0;
2554 cand_arr = btf_array(cand_type);
2555 canon_arr = btf_array(canon_type);
2556 eq = btf_dedup_is_equiv(d,
2557 cand_arr->index_type, canon_arr->index_type);
2558 if (eq <= 0)
2559 return eq;
2560 return btf_dedup_is_equiv(d, cand_arr->type, canon_arr->type);
2561 }
2562
2563 case BTF_KIND_STRUCT:
2564 case BTF_KIND_UNION: {
2565 const struct btf_member *cand_m, *canon_m;
2566 __u16 vlen;
2567
2568 if (!btf_shallow_equal_struct(cand_type, canon_type))
2569 return 0;
2570 vlen = btf_vlen(cand_type);
2571 cand_m = btf_members(cand_type);
2572 canon_m = btf_members(canon_type);
2573 for (i = 0; i < vlen; i++) {
2574 eq = btf_dedup_is_equiv(d, cand_m->type, canon_m->type);
2575 if (eq <= 0)
2576 return eq;
2577 cand_m++;
2578 canon_m++;
2579 }
2580
2581 return 1;
2582 }
2583
2584 case BTF_KIND_FUNC_PROTO: {
2585 const struct btf_param *cand_p, *canon_p;
2586 __u16 vlen;
2587
2588 if (!btf_compat_fnproto(cand_type, canon_type))
2589 return 0;
2590 eq = btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
2591 if (eq <= 0)
2592 return eq;
2593 vlen = btf_vlen(cand_type);
2594 cand_p = btf_params(cand_type);
2595 canon_p = btf_params(canon_type);
2596 for (i = 0; i < vlen; i++) {
2597 eq = btf_dedup_is_equiv(d, cand_p->type, canon_p->type);
2598 if (eq <= 0)
2599 return eq;
2600 cand_p++;
2601 canon_p++;
2602 }
2603 return 1;
2604 }
2605
2606 default:
2607 return -EINVAL;
2608 }
2609 return 0;
2610}
2611
2612/*
2613 * Use hypothetical mapping, produced by successful type graph equivalence
2614 * check, to augment existing struct/union canonical mapping, where possible.
2615 *
2616 * If BTF_KIND_FWD resolution is allowed, this mapping is also used to record
2617 * FWD -> STRUCT/UNION correspondence as well. FWD resolution is bidirectional:
2618 * it doesn't matter if FWD type was part of canonical graph or candidate one,
2619 * we are recording the mapping anyway. As opposed to carefulness required
2620 * for struct/union correspondence mapping (described below), for FWD resolution
2621 * it's not important, as by the time that FWD type (reference type) will be
2622 * deduplicated all structs/unions will be deduped already anyway.
2623 *
2624 * Recording STRUCT/UNION mapping is purely a performance optimization and is
2625 * not required for correctness. It needs to be done carefully to ensure that
2626 * struct/union from candidate's type graph is not mapped into corresponding
2627 * struct/union from canonical type graph that itself hasn't been resolved into
2628 * canonical representative. The only guarantee we have is that canonical
2629 * struct/union was determined as canonical and that won't change. But any
2630 * types referenced through that struct/union fields could have been not yet
2631 * resolved, so in case like that it's too early to establish any kind of
2632 * correspondence between structs/unions.
2633 *
2634 * No canonical correspondence is derived for primitive types (they are already
2635 * deduplicated completely already anyway) or reference types (they rely on
2636 * stability of struct/union canonical relationship for equivalence checks).
2637 */
2638static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
2639{
2640 __u32 cand_type_id, targ_type_id;
2641 __u16 t_kind, c_kind;
2642 __u32 t_id, c_id;
2643 int i;
2644
2645 for (i = 0; i < d->hypot_cnt; i++) {
2646 cand_type_id = d->hypot_list[i];
2647 targ_type_id = d->hypot_map[cand_type_id];
2648 t_id = resolve_type_id(d, targ_type_id);
2649 c_id = resolve_type_id(d, cand_type_id);
2650 t_kind = btf_kind(d->btf->types[t_id]);
2651 c_kind = btf_kind(d->btf->types[c_id]);
2652 /*
2653 * Resolve FWD into STRUCT/UNION.
2654 * It's ok to resolve FWD into STRUCT/UNION that's not yet
2655 * mapped to canonical representative (as opposed to
2656 * STRUCT/UNION <--> STRUCT/UNION mapping logic below), because
2657 * eventually that struct is going to be mapped and all resolved
2658 * FWDs will automatically resolve to correct canonical
2659 * representative. This will happen before ref type deduping,
2660 * which critically depends on stability of these mapping. This
2661 * stability is not a requirement for STRUCT/UNION equivalence
2662 * checks, though.
2663 */
2664 if (t_kind != BTF_KIND_FWD && c_kind == BTF_KIND_FWD)
2665 d->map[c_id] = t_id;
2666 else if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD)
2667 d->map[t_id] = c_id;
2668
2669 if ((t_kind == BTF_KIND_STRUCT || t_kind == BTF_KIND_UNION) &&
2670 c_kind != BTF_KIND_FWD &&
2671 is_type_mapped(d, c_id) &&
2672 !is_type_mapped(d, t_id)) {
2673 /*
2674 * as a perf optimization, we can map struct/union
2675 * that's part of type graph we just verified for
2676 * equivalence. We can do that for struct/union that has
2677 * canonical representative only, though.
2678 */
2679 d->map[t_id] = c_id;
2680 }
2681 }
2682}
2683
2684/*
2685 * Deduplicate struct/union types.
2686 *
2687 * For each struct/union type its type signature hash is calculated, taking
2688 * into account type's name, size, number, order and names of fields, but
2689 * ignoring type ID's referenced from fields, because they might not be deduped
2690 * completely until after reference types deduplication phase. This type hash
2691 * is used to iterate over all potential canonical types, sharing same hash.
2692 * For each canonical candidate we check whether type graphs that they form
2693 * (through referenced types in fields and so on) are equivalent using algorithm
2694 * implemented in `btf_dedup_is_equiv`. If such equivalence is found and
2695 * BTF_KIND_FWD resolution is allowed, then hypothetical mapping
2696 * (btf_dedup->hypot_map) produced by aforementioned type graph equivalence
2697 * algorithm is used to record FWD -> STRUCT/UNION mapping. It's also used to
2698 * potentially map other structs/unions to their canonical representatives,
2699 * if such relationship hasn't yet been established. This speeds up algorithm
2700 * by eliminating some of the duplicate work.
2701 *
2702 * If no matching canonical representative was found, struct/union is marked
2703 * as canonical for itself and is added into btf_dedup->dedup_table hash map
2704 * for further look ups.
2705 */
2706static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
2707{
2708 struct btf_type *cand_type, *t;
2709 struct hashmap_entry *hash_entry;
2710 /* if we don't find equivalent type, then we are canonical */
2711 __u32 new_id = type_id;
2712 __u16 kind;
2713 long h;
2714
2715 /* already deduped or is in process of deduping (loop detected) */
2716 if (d->map[type_id] <= BTF_MAX_NR_TYPES)
2717 return 0;
2718
2719 t = d->btf->types[type_id];
2720 kind = btf_kind(t);
2721
2722 if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
2723 return 0;
2724
2725 h = btf_hash_struct(t);
2726 for_each_dedup_cand(d, hash_entry, h) {
2727 __u32 cand_id = (__u32)(long)hash_entry->value;
2728 int eq;
2729
2730 /*
2731 * Even though btf_dedup_is_equiv() checks for
2732 * btf_shallow_equal_struct() internally when checking two
2733 * structs (unions) for equivalence, we need to guard here
2734 * from picking matching FWD type as a dedup candidate.
2735 * This can happen due to hash collision. In such case just
2736 * relying on btf_dedup_is_equiv() would lead to potentially
2737 * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because
2738 * FWD and compatible STRUCT/UNION are considered equivalent.
2739 */
2740 cand_type = d->btf->types[cand_id];
2741 if (!btf_shallow_equal_struct(t, cand_type))
2742 continue;
2743
2744 btf_dedup_clear_hypot_map(d);
2745 eq = btf_dedup_is_equiv(d, type_id, cand_id);
2746 if (eq < 0)
2747 return eq;
2748 if (!eq)
2749 continue;
2750 new_id = cand_id;
2751 btf_dedup_merge_hypot_map(d);
2752 break;
2753 }
2754
2755 d->map[type_id] = new_id;
2756 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
2757 return -ENOMEM;
2758
2759 return 0;
2760}
2761
2762static int btf_dedup_struct_types(struct btf_dedup *d)
2763{
2764 int i, err;
2765
2766 for (i = 1; i <= d->btf->nr_types; i++) {
2767 err = btf_dedup_struct_type(d, i);
2768 if (err)
2769 return err;
2770 }
2771 return 0;
2772}
2773
2774/*
2775 * Deduplicate reference type.
2776 *
2777 * Once all primitive and struct/union types got deduplicated, we can easily
2778 * deduplicate all other (reference) BTF types. This is done in two steps:
2779 *
2780 * 1. Resolve all referenced type IDs into their canonical type IDs. This
2781 * resolution can be done either immediately for primitive or struct/union types
2782 * (because they were deduped in previous two phases) or recursively for
2783 * reference types. Recursion will always terminate at either primitive or
2784 * struct/union type, at which point we can "unwind" chain of reference types
2785 * one by one. There is no danger of encountering cycles because in C type
2786 * system the only way to form type cycle is through struct/union, so any chain
2787 * of reference types, even those taking part in a type cycle, will inevitably
2788 * reach struct/union at some point.
2789 *
2790 * 2. Once all referenced type IDs are resolved into canonical ones, BTF type
2791 * becomes "stable", in the sense that no further deduplication will cause
2792 * any changes to it. With that, it's now possible to calculate type's signature
2793 * hash (this time taking into account referenced type IDs) and loop over all
2794 * potential canonical representatives. If no match was found, current type
2795 * will become canonical representative of itself and will be added into
2796 * btf_dedup->dedup_table as another possible canonical representative.
2797 */
2798static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
2799{
2800 struct hashmap_entry *hash_entry;
2801 __u32 new_id = type_id, cand_id;
2802 struct btf_type *t, *cand;
2803 /* if we don't find equivalent type, then we are representative type */
2804 int ref_type_id;
2805 long h;
2806
2807 if (d->map[type_id] == BTF_IN_PROGRESS_ID)
2808 return -ELOOP;
2809 if (d->map[type_id] <= BTF_MAX_NR_TYPES)
2810 return resolve_type_id(d, type_id);
2811
2812 t = d->btf->types[type_id];
2813 d->map[type_id] = BTF_IN_PROGRESS_ID;
2814
2815 switch (btf_kind(t)) {
2816 case BTF_KIND_CONST:
2817 case BTF_KIND_VOLATILE:
2818 case BTF_KIND_RESTRICT:
2819 case BTF_KIND_PTR:
2820 case BTF_KIND_TYPEDEF:
2821 case BTF_KIND_FUNC:
2822 ref_type_id = btf_dedup_ref_type(d, t->type);
2823 if (ref_type_id < 0)
2824 return ref_type_id;
2825 t->type = ref_type_id;
2826
2827 h = btf_hash_common(t);
2828 for_each_dedup_cand(d, hash_entry, h) {
2829 cand_id = (__u32)(long)hash_entry->value;
2830 cand = d->btf->types[cand_id];
2831 if (btf_equal_common(t, cand)) {
2832 new_id = cand_id;
2833 break;
2834 }
2835 }
2836 break;
2837
2838 case BTF_KIND_ARRAY: {
2839 struct btf_array *info = btf_array(t);
2840
2841 ref_type_id = btf_dedup_ref_type(d, info->type);
2842 if (ref_type_id < 0)
2843 return ref_type_id;
2844 info->type = ref_type_id;
2845
2846 ref_type_id = btf_dedup_ref_type(d, info->index_type);
2847 if (ref_type_id < 0)
2848 return ref_type_id;
2849 info->index_type = ref_type_id;
2850
2851 h = btf_hash_array(t);
2852 for_each_dedup_cand(d, hash_entry, h) {
2853 cand_id = (__u32)(long)hash_entry->value;
2854 cand = d->btf->types[cand_id];
2855 if (btf_equal_array(t, cand)) {
2856 new_id = cand_id;
2857 break;
2858 }
2859 }
2860 break;
2861 }
2862
2863 case BTF_KIND_FUNC_PROTO: {
2864 struct btf_param *param;
2865 __u16 vlen;
2866 int i;
2867
2868 ref_type_id = btf_dedup_ref_type(d, t->type);
2869 if (ref_type_id < 0)
2870 return ref_type_id;
2871 t->type = ref_type_id;
2872
2873 vlen = btf_vlen(t);
2874 param = btf_params(t);
2875 for (i = 0; i < vlen; i++) {
2876 ref_type_id = btf_dedup_ref_type(d, param->type);
2877 if (ref_type_id < 0)
2878 return ref_type_id;
2879 param->type = ref_type_id;
2880 param++;
2881 }
2882
2883 h = btf_hash_fnproto(t);
2884 for_each_dedup_cand(d, hash_entry, h) {
2885 cand_id = (__u32)(long)hash_entry->value;
2886 cand = d->btf->types[cand_id];
2887 if (btf_equal_fnproto(t, cand)) {
2888 new_id = cand_id;
2889 break;
2890 }
2891 }
2892 break;
2893 }
2894
2895 default:
2896 return -EINVAL;
2897 }
2898
2899 d->map[type_id] = new_id;
2900 if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
2901 return -ENOMEM;
2902
2903 return new_id;
2904}
2905
2906static int btf_dedup_ref_types(struct btf_dedup *d)
2907{
2908 int i, err;
2909
2910 for (i = 1; i <= d->btf->nr_types; i++) {
2911 err = btf_dedup_ref_type(d, i);
2912 if (err < 0)
2913 return err;
2914 }
2915 /* we won't need d->dedup_table anymore */
2916 hashmap__free(d->dedup_table);
2917 d->dedup_table = NULL;
2918 return 0;
2919}
2920
2921/*
2922 * Compact types.
2923 *
2924 * After we established for each type its corresponding canonical representative
2925 * type, we now can eliminate types that are not canonical and leave only
2926 * canonical ones layed out sequentially in memory by copying them over
2927 * duplicates. During compaction btf_dedup->hypot_map array is reused to store
2928 * a map from original type ID to a new compacted type ID, which will be used
2929 * during next phase to "fix up" type IDs, referenced from struct/union and
2930 * reference types.
2931 */
2932static int btf_dedup_compact_types(struct btf_dedup *d)
2933{
2934 struct btf_type **new_types;
2935 __u32 next_type_id = 1;
2936 char *types_start, *p;
2937 int i, len;
2938
2939 /* we are going to reuse hypot_map to store compaction remapping */
2940 d->hypot_map[0] = 0;
2941 for (i = 1; i <= d->btf->nr_types; i++)
2942 d->hypot_map[i] = BTF_UNPROCESSED_ID;
2943
2944 types_start = d->btf->nohdr_data + d->btf->hdr->type_off;
2945 p = types_start;
2946
2947 for (i = 1; i <= d->btf->nr_types; i++) {
2948 if (d->map[i] != i)
2949 continue;
2950
2951 len = btf_type_size(d->btf->types[i]);
2952 if (len < 0)
2953 return len;
2954
2955 memmove(p, d->btf->types[i], len);
2956 d->hypot_map[i] = next_type_id;
2957 d->btf->types[next_type_id] = (struct btf_type *)p;
2958 p += len;
2959 next_type_id++;
2960 }
2961
2962 /* shrink struct btf's internal types index and update btf_header */
2963 d->btf->nr_types = next_type_id - 1;
2964 d->btf->types_size = d->btf->nr_types;
2965 d->btf->hdr->type_len = p - types_start;
2966 new_types = realloc(d->btf->types,
2967 (1 + d->btf->nr_types) * sizeof(struct btf_type *));
2968 if (!new_types)
2969 return -ENOMEM;
2970 d->btf->types = new_types;
2971
2972 /* make sure string section follows type information without gaps */
2973 d->btf->hdr->str_off = p - (char *)d->btf->nohdr_data;
2974 memmove(p, d->btf->strings, d->btf->hdr->str_len);
2975 d->btf->strings = p;
2976 p += d->btf->hdr->str_len;
2977
2978 d->btf->data_size = p - (char *)d->btf->data;
2979 return 0;
2980}
2981
2982/*
2983 * Figure out final (deduplicated and compacted) type ID for provided original
2984 * `type_id` by first resolving it into corresponding canonical type ID and
2985 * then mapping it to a deduplicated type ID, stored in btf_dedup->hypot_map,
2986 * which is populated during compaction phase.
2987 */
2988static int btf_dedup_remap_type_id(struct btf_dedup *d, __u32 type_id)
2989{
2990 __u32 resolved_type_id, new_type_id;
2991
2992 resolved_type_id = resolve_type_id(d, type_id);
2993 new_type_id = d->hypot_map[resolved_type_id];
2994 if (new_type_id > BTF_MAX_NR_TYPES)
2995 return -EINVAL;
2996 return new_type_id;
2997}
2998
2999/*
3000 * Remap referenced type IDs into deduped type IDs.
3001 *
3002 * After BTF types are deduplicated and compacted, their final type IDs may
3003 * differ from original ones. The map from original to a corresponding
3004 * deduped type ID is stored in btf_dedup->hypot_map and is populated during
3005 * compaction phase. During remapping phase we are rewriting all type IDs
3006 * referenced from any BTF type (e.g., struct fields, func proto args, etc) to
3007 * their final deduped type IDs.
3008 */
3009static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
3010{
3011 struct btf_type *t = d->btf->types[type_id];
3012 int i, r;
3013
3014 switch (btf_kind(t)) {
3015 case BTF_KIND_INT:
3016 case BTF_KIND_ENUM:
3017 break;
3018
3019 case BTF_KIND_FWD:
3020 case BTF_KIND_CONST:
3021 case BTF_KIND_VOLATILE:
3022 case BTF_KIND_RESTRICT:
3023 case BTF_KIND_PTR:
3024 case BTF_KIND_TYPEDEF:
3025 case BTF_KIND_FUNC:
3026 case BTF_KIND_VAR:
3027 r = btf_dedup_remap_type_id(d, t->type);
3028 if (r < 0)
3029 return r;
3030 t->type = r;
3031 break;
3032
3033 case BTF_KIND_ARRAY: {
3034 struct btf_array *arr_info = btf_array(t);
3035
3036 r = btf_dedup_remap_type_id(d, arr_info->type);
3037 if (r < 0)
3038 return r;
3039 arr_info->type = r;
3040 r = btf_dedup_remap_type_id(d, arr_info->index_type);
3041 if (r < 0)
3042 return r;
3043 arr_info->index_type = r;
3044 break;
3045 }
3046
3047 case BTF_KIND_STRUCT:
3048 case BTF_KIND_UNION: {
3049 struct btf_member *member = btf_members(t);
3050 __u16 vlen = btf_vlen(t);
3051
3052 for (i = 0; i < vlen; i++) {
3053 r = btf_dedup_remap_type_id(d, member->type);
3054 if (r < 0)
3055 return r;
3056 member->type = r;
3057 member++;
3058 }
3059 break;
3060 }
3061
3062 case BTF_KIND_FUNC_PROTO: {
3063 struct btf_param *param = btf_params(t);
3064 __u16 vlen = btf_vlen(t);
3065
3066 r = btf_dedup_remap_type_id(d, t->type);
3067 if (r < 0)
3068 return r;
3069 t->type = r;
3070
3071 for (i = 0; i < vlen; i++) {
3072 r = btf_dedup_remap_type_id(d, param->type);
3073 if (r < 0)
3074 return r;
3075 param->type = r;
3076 param++;
3077 }
3078 break;
3079 }
3080
3081 case BTF_KIND_DATASEC: {
3082 struct btf_var_secinfo *var = btf_var_secinfos(t);
3083 __u16 vlen = btf_vlen(t);
3084
3085 for (i = 0; i < vlen; i++) {
3086 r = btf_dedup_remap_type_id(d, var->type);
3087 if (r < 0)
3088 return r;
3089 var->type = r;
3090 var++;
3091 }
3092 break;
3093 }
3094
3095 default:
3096 return -EINVAL;
3097 }
3098
3099 return 0;
3100}
3101
3102static int btf_dedup_remap_types(struct btf_dedup *d)
3103{
3104 int i, r;
3105
3106 for (i = 1; i <= d->btf->nr_types; i++) {
3107 r = btf_dedup_remap_type(d, i);
3108 if (r < 0)
3109 return r;
3110 }
3111 return 0;
3112}
3113
3114/*
3115 * Probe few well-known locations for vmlinux kernel image and try to load BTF
3116 * data out of it to use for target BTF.
3117 */
3118struct btf *libbpf_find_kernel_btf(void)
3119{
3120 struct {
3121 const char *path_fmt;
3122 bool raw_btf;
3123 } locations[] = {
3124 /* try canonical vmlinux BTF through sysfs first */
3125 { "/sys/kernel/btf/vmlinux", true /* raw BTF */ },
3126 /* fall back to trying to find vmlinux ELF on disk otherwise */
3127 { "/boot/vmlinux-%1$s" },
3128 { "/lib/modules/%1$s/vmlinux-%1$s" },
3129 { "/lib/modules/%1$s/build/vmlinux" },
3130 { "/usr/lib/modules/%1$s/kernel/vmlinux" },
3131 { "/usr/lib/debug/boot/vmlinux-%1$s" },
3132 { "/usr/lib/debug/boot/vmlinux-%1$s.debug" },
3133 { "/usr/lib/debug/lib/modules/%1$s/vmlinux" },
3134 };
3135 char path[PATH_MAX + 1];
3136 struct utsname buf;
3137 struct btf *btf;
3138 int i;
3139
3140 uname(&buf);
3141
3142 for (i = 0; i < ARRAY_SIZE(locations); i++) {
3143 snprintf(path, PATH_MAX, locations[i].path_fmt, buf.release);
3144
3145 if (access(path, R_OK))
3146 continue;
3147
3148 if (locations[i].raw_btf)
3149 btf = btf__parse_raw(path);
3150 else
3151 btf = btf__parse_elf(path, NULL);
3152
3153 pr_debug("loading kernel BTF '%s': %ld\n",
3154 path, IS_ERR(btf) ? PTR_ERR(btf) : 0);
3155 if (IS_ERR(btf))
3156 continue;
3157
3158 return btf;
3159 }
3160
3161 pr_warn("failed to find valid kernel BTF\n");
3162 return ERR_PTR(-ESRCH);
3163}