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