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1// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2/* Copyright (C) 2019 Facebook */
3
4#ifndef _GNU_SOURCE
5#define _GNU_SOURCE
6#endif
7#include <ctype.h>
8#include <errno.h>
9#include <fcntl.h>
10#include <linux/err.h>
11#include <stdbool.h>
12#include <stdio.h>
13#include <string.h>
14#include <unistd.h>
15#include <bpf/bpf.h>
16#include <bpf/libbpf.h>
17#include <bpf/libbpf_internal.h>
18#include <sys/types.h>
19#include <sys/stat.h>
20#include <sys/mman.h>
21#include <bpf/btf.h>
22
23#include "json_writer.h"
24#include "main.h"
25
26#define MAX_OBJ_NAME_LEN 64
27
28static void sanitize_identifier(char *name)
29{
30 int i;
31
32 for (i = 0; name[i]; i++)
33 if (!isalnum(name[i]) && name[i] != '_')
34 name[i] = '_';
35}
36
37static bool str_has_prefix(const char *str, const char *prefix)
38{
39 return strncmp(str, prefix, strlen(prefix)) == 0;
40}
41
42static bool str_has_suffix(const char *str, const char *suffix)
43{
44 size_t i, n1 = strlen(str), n2 = strlen(suffix);
45
46 if (n1 < n2)
47 return false;
48
49 for (i = 0; i < n2; i++) {
50 if (str[n1 - i - 1] != suffix[n2 - i - 1])
51 return false;
52 }
53
54 return true;
55}
56
57static void get_obj_name(char *name, const char *file)
58{
59 /* Using basename() GNU version which doesn't modify arg. */
60 strncpy(name, basename(file), MAX_OBJ_NAME_LEN - 1);
61 name[MAX_OBJ_NAME_LEN - 1] = '\0';
62 if (str_has_suffix(name, ".o"))
63 name[strlen(name) - 2] = '\0';
64 sanitize_identifier(name);
65}
66
67static void get_header_guard(char *guard, const char *obj_name, const char *suffix)
68{
69 int i;
70
71 sprintf(guard, "__%s_%s__", obj_name, suffix);
72 for (i = 0; guard[i]; i++)
73 guard[i] = toupper(guard[i]);
74}
75
76static bool get_map_ident(const struct bpf_map *map, char *buf, size_t buf_sz)
77{
78 static const char *sfxs[] = { ".data", ".rodata", ".bss", ".kconfig" };
79 const char *name = bpf_map__name(map);
80 int i, n;
81
82 if (!bpf_map__is_internal(map)) {
83 snprintf(buf, buf_sz, "%s", name);
84 return true;
85 }
86
87 for (i = 0, n = ARRAY_SIZE(sfxs); i < n; i++) {
88 const char *sfx = sfxs[i], *p;
89
90 p = strstr(name, sfx);
91 if (p) {
92 snprintf(buf, buf_sz, "%s", p + 1);
93 sanitize_identifier(buf);
94 return true;
95 }
96 }
97
98 return false;
99}
100
101static bool get_datasec_ident(const char *sec_name, char *buf, size_t buf_sz)
102{
103 static const char *pfxs[] = { ".data", ".rodata", ".bss", ".kconfig" };
104 int i, n;
105
106 for (i = 0, n = ARRAY_SIZE(pfxs); i < n; i++) {
107 const char *pfx = pfxs[i];
108
109 if (str_has_prefix(sec_name, pfx)) {
110 snprintf(buf, buf_sz, "%s", sec_name + 1);
111 sanitize_identifier(buf);
112 return true;
113 }
114 }
115
116 return false;
117}
118
119static void codegen_btf_dump_printf(void *ctx, const char *fmt, va_list args)
120{
121 vprintf(fmt, args);
122}
123
124static int codegen_datasec_def(struct bpf_object *obj,
125 struct btf *btf,
126 struct btf_dump *d,
127 const struct btf_type *sec,
128 const char *obj_name)
129{
130 const char *sec_name = btf__name_by_offset(btf, sec->name_off);
131 const struct btf_var_secinfo *sec_var = btf_var_secinfos(sec);
132 int i, err, off = 0, pad_cnt = 0, vlen = btf_vlen(sec);
133 char var_ident[256], sec_ident[256];
134 bool strip_mods = false;
135
136 if (!get_datasec_ident(sec_name, sec_ident, sizeof(sec_ident)))
137 return 0;
138
139 if (strcmp(sec_name, ".kconfig") != 0)
140 strip_mods = true;
141
142 printf(" struct %s__%s {\n", obj_name, sec_ident);
143 for (i = 0; i < vlen; i++, sec_var++) {
144 const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
145 const char *var_name = btf__name_by_offset(btf, var->name_off);
146 DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
147 .field_name = var_ident,
148 .indent_level = 2,
149 .strip_mods = strip_mods,
150 );
151 int need_off = sec_var->offset, align_off, align;
152 __u32 var_type_id = var->type;
153
154 /* static variables are not exposed through BPF skeleton */
155 if (btf_var(var)->linkage == BTF_VAR_STATIC)
156 continue;
157
158 if (off > need_off) {
159 p_err("Something is wrong for %s's variable #%d: need offset %d, already at %d.\n",
160 sec_name, i, need_off, off);
161 return -EINVAL;
162 }
163
164 align = btf__align_of(btf, var->type);
165 if (align <= 0) {
166 p_err("Failed to determine alignment of variable '%s': %d",
167 var_name, align);
168 return -EINVAL;
169 }
170 /* Assume 32-bit architectures when generating data section
171 * struct memory layout. Given bpftool can't know which target
172 * host architecture it's emitting skeleton for, we need to be
173 * conservative and assume 32-bit one to ensure enough padding
174 * bytes are generated for pointer and long types. This will
175 * still work correctly for 64-bit architectures, because in
176 * the worst case we'll generate unnecessary padding field,
177 * which on 64-bit architectures is not strictly necessary and
178 * would be handled by natural 8-byte alignment. But it still
179 * will be a correct memory layout, based on recorded offsets
180 * in BTF.
181 */
182 if (align > 4)
183 align = 4;
184
185 align_off = (off + align - 1) / align * align;
186 if (align_off != need_off) {
187 printf("\t\tchar __pad%d[%d];\n",
188 pad_cnt, need_off - off);
189 pad_cnt++;
190 }
191
192 /* sanitize variable name, e.g., for static vars inside
193 * a function, it's name is '<function name>.<variable name>',
194 * which we'll turn into a '<function name>_<variable name>'
195 */
196 var_ident[0] = '\0';
197 strncat(var_ident, var_name, sizeof(var_ident) - 1);
198 sanitize_identifier(var_ident);
199
200 printf("\t\t");
201 err = btf_dump__emit_type_decl(d, var_type_id, &opts);
202 if (err)
203 return err;
204 printf(";\n");
205
206 off = sec_var->offset + sec_var->size;
207 }
208 printf(" } *%s;\n", sec_ident);
209 return 0;
210}
211
212static const struct btf_type *find_type_for_map(struct btf *btf, const char *map_ident)
213{
214 int n = btf__type_cnt(btf), i;
215 char sec_ident[256];
216
217 for (i = 1; i < n; i++) {
218 const struct btf_type *t = btf__type_by_id(btf, i);
219 const char *name;
220
221 if (!btf_is_datasec(t))
222 continue;
223
224 name = btf__str_by_offset(btf, t->name_off);
225 if (!get_datasec_ident(name, sec_ident, sizeof(sec_ident)))
226 continue;
227
228 if (strcmp(sec_ident, map_ident) == 0)
229 return t;
230 }
231 return NULL;
232}
233
234static bool is_internal_mmapable_map(const struct bpf_map *map, char *buf, size_t sz)
235{
236 if (!bpf_map__is_internal(map) || !(bpf_map__map_flags(map) & BPF_F_MMAPABLE))
237 return false;
238
239 if (!get_map_ident(map, buf, sz))
240 return false;
241
242 return true;
243}
244
245static int codegen_datasecs(struct bpf_object *obj, const char *obj_name)
246{
247 struct btf *btf = bpf_object__btf(obj);
248 struct btf_dump *d;
249 struct bpf_map *map;
250 const struct btf_type *sec;
251 char map_ident[256];
252 int err = 0;
253
254 d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
255 if (!d)
256 return -errno;
257
258 bpf_object__for_each_map(map, obj) {
259 /* only generate definitions for memory-mapped internal maps */
260 if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
261 continue;
262
263 sec = find_type_for_map(btf, map_ident);
264
265 /* In some cases (e.g., sections like .rodata.cst16 containing
266 * compiler allocated string constants only) there will be
267 * special internal maps with no corresponding DATASEC BTF
268 * type. In such case, generate empty structs for each such
269 * map. It will still be memory-mapped and its contents
270 * accessible from user-space through BPF skeleton.
271 */
272 if (!sec) {
273 printf(" struct %s__%s {\n", obj_name, map_ident);
274 printf(" } *%s;\n", map_ident);
275 } else {
276 err = codegen_datasec_def(obj, btf, d, sec, obj_name);
277 if (err)
278 goto out;
279 }
280 }
281
282
283out:
284 btf_dump__free(d);
285 return err;
286}
287
288static bool btf_is_ptr_to_func_proto(const struct btf *btf,
289 const struct btf_type *v)
290{
291 return btf_is_ptr(v) && btf_is_func_proto(btf__type_by_id(btf, v->type));
292}
293
294static int codegen_subskel_datasecs(struct bpf_object *obj, const char *obj_name)
295{
296 struct btf *btf = bpf_object__btf(obj);
297 struct btf_dump *d;
298 struct bpf_map *map;
299 const struct btf_type *sec, *var;
300 const struct btf_var_secinfo *sec_var;
301 int i, err = 0, vlen;
302 char map_ident[256], sec_ident[256];
303 bool strip_mods = false, needs_typeof = false;
304 const char *sec_name, *var_name;
305 __u32 var_type_id;
306
307 d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
308 if (!d)
309 return -errno;
310
311 bpf_object__for_each_map(map, obj) {
312 /* only generate definitions for memory-mapped internal maps */
313 if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
314 continue;
315
316 sec = find_type_for_map(btf, map_ident);
317 if (!sec)
318 continue;
319
320 sec_name = btf__name_by_offset(btf, sec->name_off);
321 if (!get_datasec_ident(sec_name, sec_ident, sizeof(sec_ident)))
322 continue;
323
324 strip_mods = strcmp(sec_name, ".kconfig") != 0;
325 printf(" struct %s__%s {\n", obj_name, sec_ident);
326
327 sec_var = btf_var_secinfos(sec);
328 vlen = btf_vlen(sec);
329 for (i = 0; i < vlen; i++, sec_var++) {
330 DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
331 .indent_level = 2,
332 .strip_mods = strip_mods,
333 /* we'll print the name separately */
334 .field_name = "",
335 );
336
337 var = btf__type_by_id(btf, sec_var->type);
338 var_name = btf__name_by_offset(btf, var->name_off);
339 var_type_id = var->type;
340
341 /* static variables are not exposed through BPF skeleton */
342 if (btf_var(var)->linkage == BTF_VAR_STATIC)
343 continue;
344
345 /* The datasec member has KIND_VAR but we want the
346 * underlying type of the variable (e.g. KIND_INT).
347 */
348 var = skip_mods_and_typedefs(btf, var->type, NULL);
349
350 printf("\t\t");
351 /* Func and array members require special handling.
352 * Instead of producing `typename *var`, they produce
353 * `typeof(typename) *var`. This allows us to keep a
354 * similar syntax where the identifier is just prefixed
355 * by *, allowing us to ignore C declaration minutiae.
356 */
357 needs_typeof = btf_is_array(var) || btf_is_ptr_to_func_proto(btf, var);
358 if (needs_typeof)
359 printf("typeof(");
360
361 err = btf_dump__emit_type_decl(d, var_type_id, &opts);
362 if (err)
363 goto out;
364
365 if (needs_typeof)
366 printf(")");
367
368 printf(" *%s;\n", var_name);
369 }
370 printf(" } %s;\n", sec_ident);
371 }
372
373out:
374 btf_dump__free(d);
375 return err;
376}
377
378static void codegen(const char *template, ...)
379{
380 const char *src, *end;
381 int skip_tabs = 0, n;
382 char *s, *dst;
383 va_list args;
384 char c;
385
386 n = strlen(template);
387 s = malloc(n + 1);
388 if (!s)
389 exit(-1);
390 src = template;
391 dst = s;
392
393 /* find out "baseline" indentation to skip */
394 while ((c = *src++)) {
395 if (c == '\t') {
396 skip_tabs++;
397 } else if (c == '\n') {
398 break;
399 } else {
400 p_err("unrecognized character at pos %td in template '%s': '%c'",
401 src - template - 1, template, c);
402 free(s);
403 exit(-1);
404 }
405 }
406
407 while (*src) {
408 /* skip baseline indentation tabs */
409 for (n = skip_tabs; n > 0; n--, src++) {
410 if (*src != '\t') {
411 p_err("not enough tabs at pos %td in template '%s'",
412 src - template - 1, template);
413 free(s);
414 exit(-1);
415 }
416 }
417 /* trim trailing whitespace */
418 end = strchrnul(src, '\n');
419 for (n = end - src; n > 0 && isspace(src[n - 1]); n--)
420 ;
421 memcpy(dst, src, n);
422 dst += n;
423 if (*end)
424 *dst++ = '\n';
425 src = *end ? end + 1 : end;
426 }
427 *dst++ = '\0';
428
429 /* print out using adjusted template */
430 va_start(args, template);
431 n = vprintf(s, args);
432 va_end(args);
433
434 free(s);
435}
436
437static void print_hex(const char *data, int data_sz)
438{
439 int i, len;
440
441 for (i = 0, len = 0; i < data_sz; i++) {
442 int w = data[i] ? 4 : 2;
443
444 len += w;
445 if (len > 78) {
446 printf("\\\n");
447 len = w;
448 }
449 if (!data[i])
450 printf("\\0");
451 else
452 printf("\\x%02x", (unsigned char)data[i]);
453 }
454}
455
456static size_t bpf_map_mmap_sz(const struct bpf_map *map)
457{
458 long page_sz = sysconf(_SC_PAGE_SIZE);
459 size_t map_sz;
460
461 map_sz = (size_t)roundup(bpf_map__value_size(map), 8) * bpf_map__max_entries(map);
462 map_sz = roundup(map_sz, page_sz);
463 return map_sz;
464}
465
466/* Emit type size asserts for all top-level fields in memory-mapped internal maps. */
467static void codegen_asserts(struct bpf_object *obj, const char *obj_name)
468{
469 struct btf *btf = bpf_object__btf(obj);
470 struct bpf_map *map;
471 struct btf_var_secinfo *sec_var;
472 int i, vlen;
473 const struct btf_type *sec;
474 char map_ident[256], var_ident[256];
475
476 if (!btf)
477 return;
478
479 codegen("\
480 \n\
481 __attribute__((unused)) static void \n\
482 %1$s__assert(struct %1$s *s __attribute__((unused))) \n\
483 { \n\
484 #ifdef __cplusplus \n\
485 #define _Static_assert static_assert \n\
486 #endif \n\
487 ", obj_name);
488
489 bpf_object__for_each_map(map, obj) {
490 if (!is_internal_mmapable_map(map, map_ident, sizeof(map_ident)))
491 continue;
492
493 sec = find_type_for_map(btf, map_ident);
494 if (!sec) {
495 /* best effort, couldn't find the type for this map */
496 continue;
497 }
498
499 sec_var = btf_var_secinfos(sec);
500 vlen = btf_vlen(sec);
501
502 for (i = 0; i < vlen; i++, sec_var++) {
503 const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
504 const char *var_name = btf__name_by_offset(btf, var->name_off);
505 long var_size;
506
507 /* static variables are not exposed through BPF skeleton */
508 if (btf_var(var)->linkage == BTF_VAR_STATIC)
509 continue;
510
511 var_size = btf__resolve_size(btf, var->type);
512 if (var_size < 0)
513 continue;
514
515 var_ident[0] = '\0';
516 strncat(var_ident, var_name, sizeof(var_ident) - 1);
517 sanitize_identifier(var_ident);
518
519 printf("\t_Static_assert(sizeof(s->%s->%s) == %ld, \"unexpected size of '%s'\");\n",
520 map_ident, var_ident, var_size, var_ident);
521 }
522 }
523 codegen("\
524 \n\
525 #ifdef __cplusplus \n\
526 #undef _Static_assert \n\
527 #endif \n\
528 } \n\
529 ");
530}
531
532static void codegen_attach_detach(struct bpf_object *obj, const char *obj_name)
533{
534 struct bpf_program *prog;
535
536 bpf_object__for_each_program(prog, obj) {
537 const char *tp_name;
538
539 codegen("\
540 \n\
541 \n\
542 static inline int \n\
543 %1$s__%2$s__attach(struct %1$s *skel) \n\
544 { \n\
545 int prog_fd = skel->progs.%2$s.prog_fd; \n\
546 ", obj_name, bpf_program__name(prog));
547
548 switch (bpf_program__type(prog)) {
549 case BPF_PROG_TYPE_RAW_TRACEPOINT:
550 tp_name = strchr(bpf_program__section_name(prog), '/') + 1;
551 printf("\tint fd = skel_raw_tracepoint_open(\"%s\", prog_fd);\n", tp_name);
552 break;
553 case BPF_PROG_TYPE_TRACING:
554 case BPF_PROG_TYPE_LSM:
555 if (bpf_program__expected_attach_type(prog) == BPF_TRACE_ITER)
556 printf("\tint fd = skel_link_create(prog_fd, 0, BPF_TRACE_ITER);\n");
557 else
558 printf("\tint fd = skel_raw_tracepoint_open(NULL, prog_fd);\n");
559 break;
560 default:
561 printf("\tint fd = ((void)prog_fd, 0); /* auto-attach not supported */\n");
562 break;
563 }
564 codegen("\
565 \n\
566 \n\
567 if (fd > 0) \n\
568 skel->links.%1$s_fd = fd; \n\
569 return fd; \n\
570 } \n\
571 ", bpf_program__name(prog));
572 }
573
574 codegen("\
575 \n\
576 \n\
577 static inline int \n\
578 %1$s__attach(struct %1$s *skel) \n\
579 { \n\
580 int ret = 0; \n\
581 \n\
582 ", obj_name);
583
584 bpf_object__for_each_program(prog, obj) {
585 codegen("\
586 \n\
587 ret = ret < 0 ? ret : %1$s__%2$s__attach(skel); \n\
588 ", obj_name, bpf_program__name(prog));
589 }
590
591 codegen("\
592 \n\
593 return ret < 0 ? ret : 0; \n\
594 } \n\
595 \n\
596 static inline void \n\
597 %1$s__detach(struct %1$s *skel) \n\
598 { \n\
599 ", obj_name);
600
601 bpf_object__for_each_program(prog, obj) {
602 codegen("\
603 \n\
604 skel_closenz(skel->links.%1$s_fd); \n\
605 ", bpf_program__name(prog));
606 }
607
608 codegen("\
609 \n\
610 } \n\
611 ");
612}
613
614static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
615{
616 struct bpf_program *prog;
617 struct bpf_map *map;
618 char ident[256];
619
620 codegen("\
621 \n\
622 static void \n\
623 %1$s__destroy(struct %1$s *skel) \n\
624 { \n\
625 if (!skel) \n\
626 return; \n\
627 %1$s__detach(skel); \n\
628 ",
629 obj_name);
630
631 bpf_object__for_each_program(prog, obj) {
632 codegen("\
633 \n\
634 skel_closenz(skel->progs.%1$s.prog_fd); \n\
635 ", bpf_program__name(prog));
636 }
637
638 bpf_object__for_each_map(map, obj) {
639 if (!get_map_ident(map, ident, sizeof(ident)))
640 continue;
641 if (bpf_map__is_internal(map) &&
642 (bpf_map__map_flags(map) & BPF_F_MMAPABLE))
643 printf("\tskel_free_map_data(skel->%1$s, skel->maps.%1$s.initial_value, %2$zd);\n",
644 ident, bpf_map_mmap_sz(map));
645 codegen("\
646 \n\
647 skel_closenz(skel->maps.%1$s.map_fd); \n\
648 ", ident);
649 }
650 codegen("\
651 \n\
652 skel_free(skel); \n\
653 } \n\
654 ",
655 obj_name);
656}
657
658static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *header_guard)
659{
660 DECLARE_LIBBPF_OPTS(gen_loader_opts, opts);
661 struct bpf_map *map;
662 char ident[256];
663 int err = 0;
664
665 err = bpf_object__gen_loader(obj, &opts);
666 if (err)
667 return err;
668
669 err = bpf_object__load(obj);
670 if (err) {
671 p_err("failed to load object file");
672 goto out;
673 }
674 /* If there was no error during load then gen_loader_opts
675 * are populated with the loader program.
676 */
677
678 /* finish generating 'struct skel' */
679 codegen("\
680 \n\
681 }; \n\
682 ", obj_name);
683
684
685 codegen_attach_detach(obj, obj_name);
686
687 codegen_destroy(obj, obj_name);
688
689 codegen("\
690 \n\
691 static inline struct %1$s * \n\
692 %1$s__open(void) \n\
693 { \n\
694 struct %1$s *skel; \n\
695 \n\
696 skel = skel_alloc(sizeof(*skel)); \n\
697 if (!skel) \n\
698 goto cleanup; \n\
699 skel->ctx.sz = (void *)&skel->links - (void *)skel; \n\
700 ",
701 obj_name, opts.data_sz);
702 bpf_object__for_each_map(map, obj) {
703 const void *mmap_data = NULL;
704 size_t mmap_size = 0;
705
706 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
707 continue;
708
709 codegen("\
710 \n\
711 skel->%1$s = skel_prep_map_data((void *)\"\\ \n\
712 ", ident);
713 mmap_data = bpf_map__initial_value(map, &mmap_size);
714 print_hex(mmap_data, mmap_size);
715 codegen("\
716 \n\
717 \", %1$zd, %2$zd); \n\
718 if (!skel->%3$s) \n\
719 goto cleanup; \n\
720 skel->maps.%3$s.initial_value = (__u64) (long) skel->%3$s;\n\
721 ", bpf_map_mmap_sz(map), mmap_size, ident);
722 }
723 codegen("\
724 \n\
725 return skel; \n\
726 cleanup: \n\
727 %1$s__destroy(skel); \n\
728 return NULL; \n\
729 } \n\
730 \n\
731 static inline int \n\
732 %1$s__load(struct %1$s *skel) \n\
733 { \n\
734 struct bpf_load_and_run_opts opts = {}; \n\
735 int err; \n\
736 \n\
737 opts.ctx = (struct bpf_loader_ctx *)skel; \n\
738 opts.data_sz = %2$d; \n\
739 opts.data = (void *)\"\\ \n\
740 ",
741 obj_name, opts.data_sz);
742 print_hex(opts.data, opts.data_sz);
743 codegen("\
744 \n\
745 \"; \n\
746 ");
747
748 codegen("\
749 \n\
750 opts.insns_sz = %d; \n\
751 opts.insns = (void *)\"\\ \n\
752 ",
753 opts.insns_sz);
754 print_hex(opts.insns, opts.insns_sz);
755 codegen("\
756 \n\
757 \"; \n\
758 err = bpf_load_and_run(&opts); \n\
759 if (err < 0) \n\
760 return err; \n\
761 ", obj_name);
762 bpf_object__for_each_map(map, obj) {
763 const char *mmap_flags;
764
765 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
766 continue;
767
768 if (bpf_map__map_flags(map) & BPF_F_RDONLY_PROG)
769 mmap_flags = "PROT_READ";
770 else
771 mmap_flags = "PROT_READ | PROT_WRITE";
772
773 codegen("\
774 \n\
775 skel->%1$s = skel_finalize_map_data(&skel->maps.%1$s.initial_value, \n\
776 %2$zd, %3$s, skel->maps.%1$s.map_fd);\n\
777 if (!skel->%1$s) \n\
778 return -ENOMEM; \n\
779 ",
780 ident, bpf_map_mmap_sz(map), mmap_flags);
781 }
782 codegen("\
783 \n\
784 return 0; \n\
785 } \n\
786 \n\
787 static inline struct %1$s * \n\
788 %1$s__open_and_load(void) \n\
789 { \n\
790 struct %1$s *skel; \n\
791 \n\
792 skel = %1$s__open(); \n\
793 if (!skel) \n\
794 return NULL; \n\
795 if (%1$s__load(skel)) { \n\
796 %1$s__destroy(skel); \n\
797 return NULL; \n\
798 } \n\
799 return skel; \n\
800 } \n\
801 \n\
802 ", obj_name);
803
804 codegen_asserts(obj, obj_name);
805
806 codegen("\
807 \n\
808 \n\
809 #endif /* %s */ \n\
810 ",
811 header_guard);
812 err = 0;
813out:
814 return err;
815}
816
817static void
818codegen_maps_skeleton(struct bpf_object *obj, size_t map_cnt, bool mmaped)
819{
820 struct bpf_map *map;
821 char ident[256];
822 size_t i;
823
824 if (!map_cnt)
825 return;
826
827 codegen("\
828 \n\
829 \n\
830 /* maps */ \n\
831 s->map_cnt = %zu; \n\
832 s->map_skel_sz = sizeof(*s->maps); \n\
833 s->maps = (struct bpf_map_skeleton *)calloc(s->map_cnt, s->map_skel_sz);\n\
834 if (!s->maps) { \n\
835 err = -ENOMEM; \n\
836 goto err; \n\
837 } \n\
838 ",
839 map_cnt
840 );
841 i = 0;
842 bpf_object__for_each_map(map, obj) {
843 if (!get_map_ident(map, ident, sizeof(ident)))
844 continue;
845
846 codegen("\
847 \n\
848 \n\
849 s->maps[%zu].name = \"%s\"; \n\
850 s->maps[%zu].map = &obj->maps.%s; \n\
851 ",
852 i, bpf_map__name(map), i, ident);
853 /* memory-mapped internal maps */
854 if (mmaped && is_internal_mmapable_map(map, ident, sizeof(ident))) {
855 printf("\ts->maps[%zu].mmaped = (void **)&obj->%s;\n",
856 i, ident);
857 }
858 i++;
859 }
860}
861
862static void
863codegen_progs_skeleton(struct bpf_object *obj, size_t prog_cnt, bool populate_links)
864{
865 struct bpf_program *prog;
866 int i;
867
868 if (!prog_cnt)
869 return;
870
871 codegen("\
872 \n\
873 \n\
874 /* programs */ \n\
875 s->prog_cnt = %zu; \n\
876 s->prog_skel_sz = sizeof(*s->progs); \n\
877 s->progs = (struct bpf_prog_skeleton *)calloc(s->prog_cnt, s->prog_skel_sz);\n\
878 if (!s->progs) { \n\
879 err = -ENOMEM; \n\
880 goto err; \n\
881 } \n\
882 ",
883 prog_cnt
884 );
885 i = 0;
886 bpf_object__for_each_program(prog, obj) {
887 codegen("\
888 \n\
889 \n\
890 s->progs[%1$zu].name = \"%2$s\"; \n\
891 s->progs[%1$zu].prog = &obj->progs.%2$s;\n\
892 ",
893 i, bpf_program__name(prog));
894
895 if (populate_links) {
896 codegen("\
897 \n\
898 s->progs[%1$zu].link = &obj->links.%2$s;\n\
899 ",
900 i, bpf_program__name(prog));
901 }
902 i++;
903 }
904}
905
906static int do_skeleton(int argc, char **argv)
907{
908 char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")];
909 size_t map_cnt = 0, prog_cnt = 0, file_sz, mmap_sz;
910 DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
911 char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
912 struct bpf_object *obj = NULL;
913 const char *file;
914 char ident[256];
915 struct bpf_program *prog;
916 int fd, err = -1;
917 struct bpf_map *map;
918 struct btf *btf;
919 struct stat st;
920
921 if (!REQ_ARGS(1)) {
922 usage();
923 return -1;
924 }
925 file = GET_ARG();
926
927 while (argc) {
928 if (!REQ_ARGS(2))
929 return -1;
930
931 if (is_prefix(*argv, "name")) {
932 NEXT_ARG();
933
934 if (obj_name[0] != '\0') {
935 p_err("object name already specified");
936 return -1;
937 }
938
939 strncpy(obj_name, *argv, MAX_OBJ_NAME_LEN - 1);
940 obj_name[MAX_OBJ_NAME_LEN - 1] = '\0';
941 } else {
942 p_err("unknown arg %s", *argv);
943 return -1;
944 }
945
946 NEXT_ARG();
947 }
948
949 if (argc) {
950 p_err("extra unknown arguments");
951 return -1;
952 }
953
954 if (stat(file, &st)) {
955 p_err("failed to stat() %s: %s", file, strerror(errno));
956 return -1;
957 }
958 file_sz = st.st_size;
959 mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
960 fd = open(file, O_RDONLY);
961 if (fd < 0) {
962 p_err("failed to open() %s: %s", file, strerror(errno));
963 return -1;
964 }
965 obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
966 if (obj_data == MAP_FAILED) {
967 obj_data = NULL;
968 p_err("failed to mmap() %s: %s", file, strerror(errno));
969 goto out;
970 }
971 if (obj_name[0] == '\0')
972 get_obj_name(obj_name, file);
973 opts.object_name = obj_name;
974 if (verifier_logs)
975 /* log_level1 + log_level2 + stats, but not stable UAPI */
976 opts.kernel_log_level = 1 + 2 + 4;
977 obj = bpf_object__open_mem(obj_data, file_sz, &opts);
978 if (!obj) {
979 char err_buf[256];
980
981 err = -errno;
982 libbpf_strerror(err, err_buf, sizeof(err_buf));
983 p_err("failed to open BPF object file: %s", err_buf);
984 goto out;
985 }
986
987 bpf_object__for_each_map(map, obj) {
988 if (!get_map_ident(map, ident, sizeof(ident))) {
989 p_err("ignoring unrecognized internal map '%s'...",
990 bpf_map__name(map));
991 continue;
992 }
993 map_cnt++;
994 }
995 bpf_object__for_each_program(prog, obj) {
996 prog_cnt++;
997 }
998
999 get_header_guard(header_guard, obj_name, "SKEL_H");
1000 if (use_loader) {
1001 codegen("\
1002 \n\
1003 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
1004 /* THIS FILE IS AUTOGENERATED BY BPFTOOL! */ \n\
1005 #ifndef %2$s \n\
1006 #define %2$s \n\
1007 \n\
1008 #include <bpf/skel_internal.h> \n\
1009 \n\
1010 struct %1$s { \n\
1011 struct bpf_loader_ctx ctx; \n\
1012 ",
1013 obj_name, header_guard
1014 );
1015 } else {
1016 codegen("\
1017 \n\
1018 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
1019 \n\
1020 /* THIS FILE IS AUTOGENERATED BY BPFTOOL! */ \n\
1021 #ifndef %2$s \n\
1022 #define %2$s \n\
1023 \n\
1024 #include <errno.h> \n\
1025 #include <stdlib.h> \n\
1026 #include <bpf/libbpf.h> \n\
1027 \n\
1028 struct %1$s { \n\
1029 struct bpf_object_skeleton *skeleton; \n\
1030 struct bpf_object *obj; \n\
1031 ",
1032 obj_name, header_guard
1033 );
1034 }
1035
1036 if (map_cnt) {
1037 printf("\tstruct {\n");
1038 bpf_object__for_each_map(map, obj) {
1039 if (!get_map_ident(map, ident, sizeof(ident)))
1040 continue;
1041 if (use_loader)
1042 printf("\t\tstruct bpf_map_desc %s;\n", ident);
1043 else
1044 printf("\t\tstruct bpf_map *%s;\n", ident);
1045 }
1046 printf("\t} maps;\n");
1047 }
1048
1049 if (prog_cnt) {
1050 printf("\tstruct {\n");
1051 bpf_object__for_each_program(prog, obj) {
1052 if (use_loader)
1053 printf("\t\tstruct bpf_prog_desc %s;\n",
1054 bpf_program__name(prog));
1055 else
1056 printf("\t\tstruct bpf_program *%s;\n",
1057 bpf_program__name(prog));
1058 }
1059 printf("\t} progs;\n");
1060 printf("\tstruct {\n");
1061 bpf_object__for_each_program(prog, obj) {
1062 if (use_loader)
1063 printf("\t\tint %s_fd;\n",
1064 bpf_program__name(prog));
1065 else
1066 printf("\t\tstruct bpf_link *%s;\n",
1067 bpf_program__name(prog));
1068 }
1069 printf("\t} links;\n");
1070 }
1071
1072 btf = bpf_object__btf(obj);
1073 if (btf) {
1074 err = codegen_datasecs(obj, obj_name);
1075 if (err)
1076 goto out;
1077 }
1078 if (use_loader) {
1079 err = gen_trace(obj, obj_name, header_guard);
1080 goto out;
1081 }
1082
1083 codegen("\
1084 \n\
1085 \n\
1086 #ifdef __cplusplus \n\
1087 static inline struct %1$s *open(const struct bpf_object_open_opts *opts = nullptr);\n\
1088 static inline struct %1$s *open_and_load(); \n\
1089 static inline int load(struct %1$s *skel); \n\
1090 static inline int attach(struct %1$s *skel); \n\
1091 static inline void detach(struct %1$s *skel); \n\
1092 static inline void destroy(struct %1$s *skel); \n\
1093 static inline const void *elf_bytes(size_t *sz); \n\
1094 #endif /* __cplusplus */ \n\
1095 }; \n\
1096 \n\
1097 static void \n\
1098 %1$s__destroy(struct %1$s *obj) \n\
1099 { \n\
1100 if (!obj) \n\
1101 return; \n\
1102 if (obj->skeleton) \n\
1103 bpf_object__destroy_skeleton(obj->skeleton);\n\
1104 free(obj); \n\
1105 } \n\
1106 \n\
1107 static inline int \n\
1108 %1$s__create_skeleton(struct %1$s *obj); \n\
1109 \n\
1110 static inline struct %1$s * \n\
1111 %1$s__open_opts(const struct bpf_object_open_opts *opts) \n\
1112 { \n\
1113 struct %1$s *obj; \n\
1114 int err; \n\
1115 \n\
1116 obj = (struct %1$s *)calloc(1, sizeof(*obj)); \n\
1117 if (!obj) { \n\
1118 errno = ENOMEM; \n\
1119 return NULL; \n\
1120 } \n\
1121 \n\
1122 err = %1$s__create_skeleton(obj); \n\
1123 if (err) \n\
1124 goto err_out; \n\
1125 \n\
1126 err = bpf_object__open_skeleton(obj->skeleton, opts);\n\
1127 if (err) \n\
1128 goto err_out; \n\
1129 \n\
1130 return obj; \n\
1131 err_out: \n\
1132 %1$s__destroy(obj); \n\
1133 errno = -err; \n\
1134 return NULL; \n\
1135 } \n\
1136 \n\
1137 static inline struct %1$s * \n\
1138 %1$s__open(void) \n\
1139 { \n\
1140 return %1$s__open_opts(NULL); \n\
1141 } \n\
1142 \n\
1143 static inline int \n\
1144 %1$s__load(struct %1$s *obj) \n\
1145 { \n\
1146 return bpf_object__load_skeleton(obj->skeleton); \n\
1147 } \n\
1148 \n\
1149 static inline struct %1$s * \n\
1150 %1$s__open_and_load(void) \n\
1151 { \n\
1152 struct %1$s *obj; \n\
1153 int err; \n\
1154 \n\
1155 obj = %1$s__open(); \n\
1156 if (!obj) \n\
1157 return NULL; \n\
1158 err = %1$s__load(obj); \n\
1159 if (err) { \n\
1160 %1$s__destroy(obj); \n\
1161 errno = -err; \n\
1162 return NULL; \n\
1163 } \n\
1164 return obj; \n\
1165 } \n\
1166 \n\
1167 static inline int \n\
1168 %1$s__attach(struct %1$s *obj) \n\
1169 { \n\
1170 return bpf_object__attach_skeleton(obj->skeleton); \n\
1171 } \n\
1172 \n\
1173 static inline void \n\
1174 %1$s__detach(struct %1$s *obj) \n\
1175 { \n\
1176 bpf_object__detach_skeleton(obj->skeleton); \n\
1177 } \n\
1178 ",
1179 obj_name
1180 );
1181
1182 codegen("\
1183 \n\
1184 \n\
1185 static inline const void *%1$s__elf_bytes(size_t *sz); \n\
1186 \n\
1187 static inline int \n\
1188 %1$s__create_skeleton(struct %1$s *obj) \n\
1189 { \n\
1190 struct bpf_object_skeleton *s; \n\
1191 int err; \n\
1192 \n\
1193 s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\
1194 if (!s) { \n\
1195 err = -ENOMEM; \n\
1196 goto err; \n\
1197 } \n\
1198 \n\
1199 s->sz = sizeof(*s); \n\
1200 s->name = \"%1$s\"; \n\
1201 s->obj = &obj->obj; \n\
1202 ",
1203 obj_name
1204 );
1205
1206 codegen_maps_skeleton(obj, map_cnt, true /*mmaped*/);
1207 codegen_progs_skeleton(obj, prog_cnt, true /*populate_links*/);
1208
1209 codegen("\
1210 \n\
1211 \n\
1212 s->data = (void *)%2$s__elf_bytes(&s->data_sz); \n\
1213 \n\
1214 obj->skeleton = s; \n\
1215 return 0; \n\
1216 err: \n\
1217 bpf_object__destroy_skeleton(s); \n\
1218 return err; \n\
1219 } \n\
1220 \n\
1221 static inline const void *%2$s__elf_bytes(size_t *sz) \n\
1222 { \n\
1223 *sz = %1$d; \n\
1224 return (const void *)\"\\ \n\
1225 "
1226 , file_sz, obj_name);
1227
1228 /* embed contents of BPF object file */
1229 print_hex(obj_data, file_sz);
1230
1231 codegen("\
1232 \n\
1233 \"; \n\
1234 } \n\
1235 \n\
1236 #ifdef __cplusplus \n\
1237 struct %1$s *%1$s::open(const struct bpf_object_open_opts *opts) { return %1$s__open_opts(opts); }\n\
1238 struct %1$s *%1$s::open_and_load() { return %1$s__open_and_load(); } \n\
1239 int %1$s::load(struct %1$s *skel) { return %1$s__load(skel); } \n\
1240 int %1$s::attach(struct %1$s *skel) { return %1$s__attach(skel); } \n\
1241 void %1$s::detach(struct %1$s *skel) { %1$s__detach(skel); } \n\
1242 void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); } \n\
1243 const void *%1$s::elf_bytes(size_t *sz) { return %1$s__elf_bytes(sz); } \n\
1244 #endif /* __cplusplus */ \n\
1245 \n\
1246 ",
1247 obj_name);
1248
1249 codegen_asserts(obj, obj_name);
1250
1251 codegen("\
1252 \n\
1253 \n\
1254 #endif /* %1$s */ \n\
1255 ",
1256 header_guard);
1257 err = 0;
1258out:
1259 bpf_object__close(obj);
1260 if (obj_data)
1261 munmap(obj_data, mmap_sz);
1262 close(fd);
1263 return err;
1264}
1265
1266/* Subskeletons are like skeletons, except they don't own the bpf_object,
1267 * associated maps, links, etc. Instead, they know about the existence of
1268 * variables, maps, programs and are able to find their locations
1269 * _at runtime_ from an already loaded bpf_object.
1270 *
1271 * This allows for library-like BPF objects to have userspace counterparts
1272 * with access to their own items without having to know anything about the
1273 * final BPF object that the library was linked into.
1274 */
1275static int do_subskeleton(int argc, char **argv)
1276{
1277 char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SUBSKEL_H__")];
1278 size_t i, len, file_sz, map_cnt = 0, prog_cnt = 0, mmap_sz, var_cnt = 0, var_idx = 0;
1279 DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
1280 char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
1281 struct bpf_object *obj = NULL;
1282 const char *file, *var_name;
1283 char ident[256];
1284 int fd, err = -1, map_type_id;
1285 const struct bpf_map *map;
1286 struct bpf_program *prog;
1287 struct btf *btf;
1288 const struct btf_type *map_type, *var_type;
1289 const struct btf_var_secinfo *var;
1290 struct stat st;
1291
1292 if (!REQ_ARGS(1)) {
1293 usage();
1294 return -1;
1295 }
1296 file = GET_ARG();
1297
1298 while (argc) {
1299 if (!REQ_ARGS(2))
1300 return -1;
1301
1302 if (is_prefix(*argv, "name")) {
1303 NEXT_ARG();
1304
1305 if (obj_name[0] != '\0') {
1306 p_err("object name already specified");
1307 return -1;
1308 }
1309
1310 strncpy(obj_name, *argv, MAX_OBJ_NAME_LEN - 1);
1311 obj_name[MAX_OBJ_NAME_LEN - 1] = '\0';
1312 } else {
1313 p_err("unknown arg %s", *argv);
1314 return -1;
1315 }
1316
1317 NEXT_ARG();
1318 }
1319
1320 if (argc) {
1321 p_err("extra unknown arguments");
1322 return -1;
1323 }
1324
1325 if (use_loader) {
1326 p_err("cannot use loader for subskeletons");
1327 return -1;
1328 }
1329
1330 if (stat(file, &st)) {
1331 p_err("failed to stat() %s: %s", file, strerror(errno));
1332 return -1;
1333 }
1334 file_sz = st.st_size;
1335 mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
1336 fd = open(file, O_RDONLY);
1337 if (fd < 0) {
1338 p_err("failed to open() %s: %s", file, strerror(errno));
1339 return -1;
1340 }
1341 obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
1342 if (obj_data == MAP_FAILED) {
1343 obj_data = NULL;
1344 p_err("failed to mmap() %s: %s", file, strerror(errno));
1345 goto out;
1346 }
1347 if (obj_name[0] == '\0')
1348 get_obj_name(obj_name, file);
1349
1350 /* The empty object name allows us to use bpf_map__name and produce
1351 * ELF section names out of it. (".data" instead of "obj.data")
1352 */
1353 opts.object_name = "";
1354 obj = bpf_object__open_mem(obj_data, file_sz, &opts);
1355 if (!obj) {
1356 char err_buf[256];
1357
1358 libbpf_strerror(errno, err_buf, sizeof(err_buf));
1359 p_err("failed to open BPF object file: %s", err_buf);
1360 obj = NULL;
1361 goto out;
1362 }
1363
1364 btf = bpf_object__btf(obj);
1365 if (!btf) {
1366 err = -1;
1367 p_err("need btf type information for %s", obj_name);
1368 goto out;
1369 }
1370
1371 bpf_object__for_each_program(prog, obj) {
1372 prog_cnt++;
1373 }
1374
1375 /* First, count how many variables we have to find.
1376 * We need this in advance so the subskel can allocate the right
1377 * amount of storage.
1378 */
1379 bpf_object__for_each_map(map, obj) {
1380 if (!get_map_ident(map, ident, sizeof(ident)))
1381 continue;
1382
1383 /* Also count all maps that have a name */
1384 map_cnt++;
1385
1386 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
1387 continue;
1388
1389 map_type_id = bpf_map__btf_value_type_id(map);
1390 if (map_type_id <= 0) {
1391 err = map_type_id;
1392 goto out;
1393 }
1394 map_type = btf__type_by_id(btf, map_type_id);
1395
1396 var = btf_var_secinfos(map_type);
1397 len = btf_vlen(map_type);
1398 for (i = 0; i < len; i++, var++) {
1399 var_type = btf__type_by_id(btf, var->type);
1400
1401 if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
1402 continue;
1403
1404 var_cnt++;
1405 }
1406 }
1407
1408 get_header_guard(header_guard, obj_name, "SUBSKEL_H");
1409 codegen("\
1410 \n\
1411 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
1412 \n\
1413 /* THIS FILE IS AUTOGENERATED! */ \n\
1414 #ifndef %2$s \n\
1415 #define %2$s \n\
1416 \n\
1417 #include <errno.h> \n\
1418 #include <stdlib.h> \n\
1419 #include <bpf/libbpf.h> \n\
1420 \n\
1421 struct %1$s { \n\
1422 struct bpf_object *obj; \n\
1423 struct bpf_object_subskeleton *subskel; \n\
1424 ", obj_name, header_guard);
1425
1426 if (map_cnt) {
1427 printf("\tstruct {\n");
1428 bpf_object__for_each_map(map, obj) {
1429 if (!get_map_ident(map, ident, sizeof(ident)))
1430 continue;
1431 printf("\t\tstruct bpf_map *%s;\n", ident);
1432 }
1433 printf("\t} maps;\n");
1434 }
1435
1436 if (prog_cnt) {
1437 printf("\tstruct {\n");
1438 bpf_object__for_each_program(prog, obj) {
1439 printf("\t\tstruct bpf_program *%s;\n",
1440 bpf_program__name(prog));
1441 }
1442 printf("\t} progs;\n");
1443 }
1444
1445 err = codegen_subskel_datasecs(obj, obj_name);
1446 if (err)
1447 goto out;
1448
1449 /* emit code that will allocate enough storage for all symbols */
1450 codegen("\
1451 \n\
1452 \n\
1453 #ifdef __cplusplus \n\
1454 static inline struct %1$s *open(const struct bpf_object *src);\n\
1455 static inline void destroy(struct %1$s *skel); \n\
1456 #endif /* __cplusplus */ \n\
1457 }; \n\
1458 \n\
1459 static inline void \n\
1460 %1$s__destroy(struct %1$s *skel) \n\
1461 { \n\
1462 if (!skel) \n\
1463 return; \n\
1464 if (skel->subskel) \n\
1465 bpf_object__destroy_subskeleton(skel->subskel);\n\
1466 free(skel); \n\
1467 } \n\
1468 \n\
1469 static inline struct %1$s * \n\
1470 %1$s__open(const struct bpf_object *src) \n\
1471 { \n\
1472 struct %1$s *obj; \n\
1473 struct bpf_object_subskeleton *s; \n\
1474 int err; \n\
1475 \n\
1476 obj = (struct %1$s *)calloc(1, sizeof(*obj)); \n\
1477 if (!obj) { \n\
1478 err = -ENOMEM; \n\
1479 goto err; \n\
1480 } \n\
1481 s = (struct bpf_object_subskeleton *)calloc(1, sizeof(*s));\n\
1482 if (!s) { \n\
1483 err = -ENOMEM; \n\
1484 goto err; \n\
1485 } \n\
1486 s->sz = sizeof(*s); \n\
1487 s->obj = src; \n\
1488 s->var_skel_sz = sizeof(*s->vars); \n\
1489 obj->subskel = s; \n\
1490 \n\
1491 /* vars */ \n\
1492 s->var_cnt = %2$d; \n\
1493 s->vars = (struct bpf_var_skeleton *)calloc(%2$d, sizeof(*s->vars));\n\
1494 if (!s->vars) { \n\
1495 err = -ENOMEM; \n\
1496 goto err; \n\
1497 } \n\
1498 ",
1499 obj_name, var_cnt
1500 );
1501
1502 /* walk through each symbol and emit the runtime representation */
1503 bpf_object__for_each_map(map, obj) {
1504 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
1505 continue;
1506
1507 map_type_id = bpf_map__btf_value_type_id(map);
1508 if (map_type_id <= 0)
1509 /* skip over internal maps with no type*/
1510 continue;
1511
1512 map_type = btf__type_by_id(btf, map_type_id);
1513 var = btf_var_secinfos(map_type);
1514 len = btf_vlen(map_type);
1515 for (i = 0; i < len; i++, var++) {
1516 var_type = btf__type_by_id(btf, var->type);
1517 var_name = btf__name_by_offset(btf, var_type->name_off);
1518
1519 if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
1520 continue;
1521
1522 /* Note that we use the dot prefix in .data as the
1523 * field access operator i.e. maps%s becomes maps.data
1524 */
1525 codegen("\
1526 \n\
1527 \n\
1528 s->vars[%3$d].name = \"%1$s\"; \n\
1529 s->vars[%3$d].map = &obj->maps.%2$s; \n\
1530 s->vars[%3$d].addr = (void **) &obj->%2$s.%1$s;\n\
1531 ", var_name, ident, var_idx);
1532
1533 var_idx++;
1534 }
1535 }
1536
1537 codegen_maps_skeleton(obj, map_cnt, false /*mmaped*/);
1538 codegen_progs_skeleton(obj, prog_cnt, false /*links*/);
1539
1540 codegen("\
1541 \n\
1542 \n\
1543 err = bpf_object__open_subskeleton(s); \n\
1544 if (err) \n\
1545 goto err; \n\
1546 \n\
1547 return obj; \n\
1548 err: \n\
1549 %1$s__destroy(obj); \n\
1550 errno = -err; \n\
1551 return NULL; \n\
1552 } \n\
1553 \n\
1554 #ifdef __cplusplus \n\
1555 struct %1$s *%1$s::open(const struct bpf_object *src) { return %1$s__open(src); }\n\
1556 void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); }\n\
1557 #endif /* __cplusplus */ \n\
1558 \n\
1559 #endif /* %2$s */ \n\
1560 ",
1561 obj_name, header_guard);
1562 err = 0;
1563out:
1564 bpf_object__close(obj);
1565 if (obj_data)
1566 munmap(obj_data, mmap_sz);
1567 close(fd);
1568 return err;
1569}
1570
1571static int do_object(int argc, char **argv)
1572{
1573 struct bpf_linker *linker;
1574 const char *output_file, *file;
1575 int err = 0;
1576
1577 if (!REQ_ARGS(2)) {
1578 usage();
1579 return -1;
1580 }
1581
1582 output_file = GET_ARG();
1583
1584 linker = bpf_linker__new(output_file, NULL);
1585 if (!linker) {
1586 p_err("failed to create BPF linker instance");
1587 return -1;
1588 }
1589
1590 while (argc) {
1591 file = GET_ARG();
1592
1593 err = bpf_linker__add_file(linker, file, NULL);
1594 if (err) {
1595 p_err("failed to link '%s': %s (%d)", file, strerror(errno), errno);
1596 goto out;
1597 }
1598 }
1599
1600 err = bpf_linker__finalize(linker);
1601 if (err) {
1602 p_err("failed to finalize ELF file: %s (%d)", strerror(errno), errno);
1603 goto out;
1604 }
1605
1606 err = 0;
1607out:
1608 bpf_linker__free(linker);
1609 return err;
1610}
1611
1612static int do_help(int argc, char **argv)
1613{
1614 if (json_output) {
1615 jsonw_null(json_wtr);
1616 return 0;
1617 }
1618
1619 fprintf(stderr,
1620 "Usage: %1$s %2$s object OUTPUT_FILE INPUT_FILE [INPUT_FILE...]\n"
1621 " %1$s %2$s skeleton FILE [name OBJECT_NAME]\n"
1622 " %1$s %2$s subskeleton FILE [name OBJECT_NAME]\n"
1623 " %1$s %2$s min_core_btf INPUT OUTPUT OBJECT [OBJECT...]\n"
1624 " %1$s %2$s help\n"
1625 "\n"
1626 " " HELP_SPEC_OPTIONS " |\n"
1627 " {-L|--use-loader} }\n"
1628 "",
1629 bin_name, "gen");
1630
1631 return 0;
1632}
1633
1634static int btf_save_raw(const struct btf *btf, const char *path)
1635{
1636 const void *data;
1637 FILE *f = NULL;
1638 __u32 data_sz;
1639 int err = 0;
1640
1641 data = btf__raw_data(btf, &data_sz);
1642 if (!data)
1643 return -ENOMEM;
1644
1645 f = fopen(path, "wb");
1646 if (!f)
1647 return -errno;
1648
1649 if (fwrite(data, 1, data_sz, f) != data_sz)
1650 err = -errno;
1651
1652 fclose(f);
1653 return err;
1654}
1655
1656struct btfgen_info {
1657 struct btf *src_btf;
1658 struct btf *marked_btf; /* btf structure used to mark used types */
1659};
1660
1661static size_t btfgen_hash_fn(long key, void *ctx)
1662{
1663 return key;
1664}
1665
1666static bool btfgen_equal_fn(long k1, long k2, void *ctx)
1667{
1668 return k1 == k2;
1669}
1670
1671static void btfgen_free_info(struct btfgen_info *info)
1672{
1673 if (!info)
1674 return;
1675
1676 btf__free(info->src_btf);
1677 btf__free(info->marked_btf);
1678
1679 free(info);
1680}
1681
1682static struct btfgen_info *
1683btfgen_new_info(const char *targ_btf_path)
1684{
1685 struct btfgen_info *info;
1686 int err;
1687
1688 info = calloc(1, sizeof(*info));
1689 if (!info)
1690 return NULL;
1691
1692 info->src_btf = btf__parse(targ_btf_path, NULL);
1693 if (!info->src_btf) {
1694 err = -errno;
1695 p_err("failed parsing '%s' BTF file: %s", targ_btf_path, strerror(errno));
1696 goto err_out;
1697 }
1698
1699 info->marked_btf = btf__parse(targ_btf_path, NULL);
1700 if (!info->marked_btf) {
1701 err = -errno;
1702 p_err("failed parsing '%s' BTF file: %s", targ_btf_path, strerror(errno));
1703 goto err_out;
1704 }
1705
1706 return info;
1707
1708err_out:
1709 btfgen_free_info(info);
1710 errno = -err;
1711 return NULL;
1712}
1713
1714#define MARKED UINT32_MAX
1715
1716static void btfgen_mark_member(struct btfgen_info *info, int type_id, int idx)
1717{
1718 const struct btf_type *t = btf__type_by_id(info->marked_btf, type_id);
1719 struct btf_member *m = btf_members(t) + idx;
1720
1721 m->name_off = MARKED;
1722}
1723
1724static int
1725btfgen_mark_type(struct btfgen_info *info, unsigned int type_id, bool follow_pointers)
1726{
1727 const struct btf_type *btf_type = btf__type_by_id(info->src_btf, type_id);
1728 struct btf_type *cloned_type;
1729 struct btf_param *param;
1730 struct btf_array *array;
1731 int err, i;
1732
1733 if (type_id == 0)
1734 return 0;
1735
1736 /* mark type on cloned BTF as used */
1737 cloned_type = (struct btf_type *) btf__type_by_id(info->marked_btf, type_id);
1738 cloned_type->name_off = MARKED;
1739
1740 /* recursively mark other types needed by it */
1741 switch (btf_kind(btf_type)) {
1742 case BTF_KIND_UNKN:
1743 case BTF_KIND_INT:
1744 case BTF_KIND_FLOAT:
1745 case BTF_KIND_ENUM:
1746 case BTF_KIND_ENUM64:
1747 case BTF_KIND_STRUCT:
1748 case BTF_KIND_UNION:
1749 break;
1750 case BTF_KIND_PTR:
1751 if (follow_pointers) {
1752 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1753 if (err)
1754 return err;
1755 }
1756 break;
1757 case BTF_KIND_CONST:
1758 case BTF_KIND_RESTRICT:
1759 case BTF_KIND_VOLATILE:
1760 case BTF_KIND_TYPEDEF:
1761 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1762 if (err)
1763 return err;
1764 break;
1765 case BTF_KIND_ARRAY:
1766 array = btf_array(btf_type);
1767
1768 /* mark array type */
1769 err = btfgen_mark_type(info, array->type, follow_pointers);
1770 /* mark array's index type */
1771 err = err ? : btfgen_mark_type(info, array->index_type, follow_pointers);
1772 if (err)
1773 return err;
1774 break;
1775 case BTF_KIND_FUNC_PROTO:
1776 /* mark ret type */
1777 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1778 if (err)
1779 return err;
1780
1781 /* mark parameters types */
1782 param = btf_params(btf_type);
1783 for (i = 0; i < btf_vlen(btf_type); i++) {
1784 err = btfgen_mark_type(info, param->type, follow_pointers);
1785 if (err)
1786 return err;
1787 param++;
1788 }
1789 break;
1790 /* tells if some other type needs to be handled */
1791 default:
1792 p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
1793 return -EINVAL;
1794 }
1795
1796 return 0;
1797}
1798
1799static int btfgen_record_field_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1800{
1801 struct btf *btf = info->src_btf;
1802 const struct btf_type *btf_type;
1803 struct btf_member *btf_member;
1804 struct btf_array *array;
1805 unsigned int type_id = targ_spec->root_type_id;
1806 int idx, err;
1807
1808 /* mark root type */
1809 btf_type = btf__type_by_id(btf, type_id);
1810 err = btfgen_mark_type(info, type_id, false);
1811 if (err)
1812 return err;
1813
1814 /* mark types for complex types (arrays, unions, structures) */
1815 for (int i = 1; i < targ_spec->raw_len; i++) {
1816 /* skip typedefs and mods */
1817 while (btf_is_mod(btf_type) || btf_is_typedef(btf_type)) {
1818 type_id = btf_type->type;
1819 btf_type = btf__type_by_id(btf, type_id);
1820 }
1821
1822 switch (btf_kind(btf_type)) {
1823 case BTF_KIND_STRUCT:
1824 case BTF_KIND_UNION:
1825 idx = targ_spec->raw_spec[i];
1826 btf_member = btf_members(btf_type) + idx;
1827
1828 /* mark member */
1829 btfgen_mark_member(info, type_id, idx);
1830
1831 /* mark member's type */
1832 type_id = btf_member->type;
1833 btf_type = btf__type_by_id(btf, type_id);
1834 err = btfgen_mark_type(info, type_id, false);
1835 if (err)
1836 return err;
1837 break;
1838 case BTF_KIND_ARRAY:
1839 array = btf_array(btf_type);
1840 type_id = array->type;
1841 btf_type = btf__type_by_id(btf, type_id);
1842 break;
1843 default:
1844 p_err("unsupported kind: %s (%d)",
1845 btf_kind_str(btf_type), btf_type->type);
1846 return -EINVAL;
1847 }
1848 }
1849
1850 return 0;
1851}
1852
1853/* Mark types, members, and member types. Compared to btfgen_record_field_relo,
1854 * this function does not rely on the target spec for inferring members, but
1855 * uses the associated BTF.
1856 *
1857 * The `behind_ptr` argument is used to stop marking of composite types reached
1858 * through a pointer. This way, we can keep BTF size in check while providing
1859 * reasonable match semantics.
1860 */
1861static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool behind_ptr)
1862{
1863 const struct btf_type *btf_type;
1864 struct btf *btf = info->src_btf;
1865 struct btf_type *cloned_type;
1866 int i, err;
1867
1868 if (type_id == 0)
1869 return 0;
1870
1871 btf_type = btf__type_by_id(btf, type_id);
1872 /* mark type on cloned BTF as used */
1873 cloned_type = (struct btf_type *)btf__type_by_id(info->marked_btf, type_id);
1874 cloned_type->name_off = MARKED;
1875
1876 switch (btf_kind(btf_type)) {
1877 case BTF_KIND_UNKN:
1878 case BTF_KIND_INT:
1879 case BTF_KIND_FLOAT:
1880 case BTF_KIND_ENUM:
1881 case BTF_KIND_ENUM64:
1882 break;
1883 case BTF_KIND_STRUCT:
1884 case BTF_KIND_UNION: {
1885 struct btf_member *m = btf_members(btf_type);
1886 __u16 vlen = btf_vlen(btf_type);
1887
1888 if (behind_ptr)
1889 break;
1890
1891 for (i = 0; i < vlen; i++, m++) {
1892 /* mark member */
1893 btfgen_mark_member(info, type_id, i);
1894
1895 /* mark member's type */
1896 err = btfgen_mark_type_match(info, m->type, false);
1897 if (err)
1898 return err;
1899 }
1900 break;
1901 }
1902 case BTF_KIND_CONST:
1903 case BTF_KIND_FWD:
1904 case BTF_KIND_RESTRICT:
1905 case BTF_KIND_TYPEDEF:
1906 case BTF_KIND_VOLATILE:
1907 return btfgen_mark_type_match(info, btf_type->type, behind_ptr);
1908 case BTF_KIND_PTR:
1909 return btfgen_mark_type_match(info, btf_type->type, true);
1910 case BTF_KIND_ARRAY: {
1911 struct btf_array *array;
1912
1913 array = btf_array(btf_type);
1914 /* mark array type */
1915 err = btfgen_mark_type_match(info, array->type, false);
1916 /* mark array's index type */
1917 err = err ? : btfgen_mark_type_match(info, array->index_type, false);
1918 if (err)
1919 return err;
1920 break;
1921 }
1922 case BTF_KIND_FUNC_PROTO: {
1923 __u16 vlen = btf_vlen(btf_type);
1924 struct btf_param *param;
1925
1926 /* mark ret type */
1927 err = btfgen_mark_type_match(info, btf_type->type, false);
1928 if (err)
1929 return err;
1930
1931 /* mark parameters types */
1932 param = btf_params(btf_type);
1933 for (i = 0; i < vlen; i++) {
1934 err = btfgen_mark_type_match(info, param->type, false);
1935 if (err)
1936 return err;
1937 param++;
1938 }
1939 break;
1940 }
1941 /* tells if some other type needs to be handled */
1942 default:
1943 p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
1944 return -EINVAL;
1945 }
1946
1947 return 0;
1948}
1949
1950/* Mark types, members, and member types. Compared to btfgen_record_field_relo,
1951 * this function does not rely on the target spec for inferring members, but
1952 * uses the associated BTF.
1953 */
1954static int btfgen_record_type_match_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1955{
1956 return btfgen_mark_type_match(info, targ_spec->root_type_id, false);
1957}
1958
1959static int btfgen_record_type_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1960{
1961 return btfgen_mark_type(info, targ_spec->root_type_id, true);
1962}
1963
1964static int btfgen_record_enumval_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1965{
1966 return btfgen_mark_type(info, targ_spec->root_type_id, false);
1967}
1968
1969static int btfgen_record_reloc(struct btfgen_info *info, struct bpf_core_spec *res)
1970{
1971 switch (res->relo_kind) {
1972 case BPF_CORE_FIELD_BYTE_OFFSET:
1973 case BPF_CORE_FIELD_BYTE_SIZE:
1974 case BPF_CORE_FIELD_EXISTS:
1975 case BPF_CORE_FIELD_SIGNED:
1976 case BPF_CORE_FIELD_LSHIFT_U64:
1977 case BPF_CORE_FIELD_RSHIFT_U64:
1978 return btfgen_record_field_relo(info, res);
1979 case BPF_CORE_TYPE_ID_LOCAL: /* BPF_CORE_TYPE_ID_LOCAL doesn't require kernel BTF */
1980 return 0;
1981 case BPF_CORE_TYPE_ID_TARGET:
1982 case BPF_CORE_TYPE_EXISTS:
1983 case BPF_CORE_TYPE_SIZE:
1984 return btfgen_record_type_relo(info, res);
1985 case BPF_CORE_TYPE_MATCHES:
1986 return btfgen_record_type_match_relo(info, res);
1987 case BPF_CORE_ENUMVAL_EXISTS:
1988 case BPF_CORE_ENUMVAL_VALUE:
1989 return btfgen_record_enumval_relo(info, res);
1990 default:
1991 return -EINVAL;
1992 }
1993}
1994
1995static struct bpf_core_cand_list *
1996btfgen_find_cands(const struct btf *local_btf, const struct btf *targ_btf, __u32 local_id)
1997{
1998 const struct btf_type *local_type;
1999 struct bpf_core_cand_list *cands = NULL;
2000 struct bpf_core_cand local_cand = {};
2001 size_t local_essent_len;
2002 const char *local_name;
2003 int err;
2004
2005 local_cand.btf = local_btf;
2006 local_cand.id = local_id;
2007
2008 local_type = btf__type_by_id(local_btf, local_id);
2009 if (!local_type) {
2010 err = -EINVAL;
2011 goto err_out;
2012 }
2013
2014 local_name = btf__name_by_offset(local_btf, local_type->name_off);
2015 if (!local_name) {
2016 err = -EINVAL;
2017 goto err_out;
2018 }
2019 local_essent_len = bpf_core_essential_name_len(local_name);
2020
2021 cands = calloc(1, sizeof(*cands));
2022 if (!cands)
2023 return NULL;
2024
2025 err = bpf_core_add_cands(&local_cand, local_essent_len, targ_btf, "vmlinux", 1, cands);
2026 if (err)
2027 goto err_out;
2028
2029 return cands;
2030
2031err_out:
2032 bpf_core_free_cands(cands);
2033 errno = -err;
2034 return NULL;
2035}
2036
2037/* Record relocation information for a single BPF object */
2038static int btfgen_record_obj(struct btfgen_info *info, const char *obj_path)
2039{
2040 const struct btf_ext_info_sec *sec;
2041 const struct bpf_core_relo *relo;
2042 const struct btf_ext_info *seg;
2043 struct hashmap_entry *entry;
2044 struct hashmap *cand_cache = NULL;
2045 struct btf_ext *btf_ext = NULL;
2046 unsigned int relo_idx;
2047 struct btf *btf = NULL;
2048 size_t i;
2049 int err;
2050
2051 btf = btf__parse(obj_path, &btf_ext);
2052 if (!btf) {
2053 err = -errno;
2054 p_err("failed to parse BPF object '%s': %s", obj_path, strerror(errno));
2055 return err;
2056 }
2057
2058 if (!btf_ext) {
2059 p_err("failed to parse BPF object '%s': section %s not found",
2060 obj_path, BTF_EXT_ELF_SEC);
2061 err = -EINVAL;
2062 goto out;
2063 }
2064
2065 if (btf_ext->core_relo_info.len == 0) {
2066 err = 0;
2067 goto out;
2068 }
2069
2070 cand_cache = hashmap__new(btfgen_hash_fn, btfgen_equal_fn, NULL);
2071 if (IS_ERR(cand_cache)) {
2072 err = PTR_ERR(cand_cache);
2073 goto out;
2074 }
2075
2076 seg = &btf_ext->core_relo_info;
2077 for_each_btf_ext_sec(seg, sec) {
2078 for_each_btf_ext_rec(seg, sec, relo_idx, relo) {
2079 struct bpf_core_spec specs_scratch[3] = {};
2080 struct bpf_core_relo_res targ_res = {};
2081 struct bpf_core_cand_list *cands = NULL;
2082 const char *sec_name = btf__name_by_offset(btf, sec->sec_name_off);
2083
2084 if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
2085 !hashmap__find(cand_cache, relo->type_id, &cands)) {
2086 cands = btfgen_find_cands(btf, info->src_btf, relo->type_id);
2087 if (!cands) {
2088 err = -errno;
2089 goto out;
2090 }
2091
2092 err = hashmap__set(cand_cache, relo->type_id, cands,
2093 NULL, NULL);
2094 if (err)
2095 goto out;
2096 }
2097
2098 err = bpf_core_calc_relo_insn(sec_name, relo, relo_idx, btf, cands,
2099 specs_scratch, &targ_res);
2100 if (err)
2101 goto out;
2102
2103 /* specs_scratch[2] is the target spec */
2104 err = btfgen_record_reloc(info, &specs_scratch[2]);
2105 if (err)
2106 goto out;
2107 }
2108 }
2109
2110out:
2111 btf__free(btf);
2112 btf_ext__free(btf_ext);
2113
2114 if (!IS_ERR_OR_NULL(cand_cache)) {
2115 hashmap__for_each_entry(cand_cache, entry, i) {
2116 bpf_core_free_cands(entry->pvalue);
2117 }
2118 hashmap__free(cand_cache);
2119 }
2120
2121 return err;
2122}
2123
2124static int btfgen_remap_id(__u32 *type_id, void *ctx)
2125{
2126 unsigned int *ids = ctx;
2127
2128 *type_id = ids[*type_id];
2129
2130 return 0;
2131}
2132
2133/* Generate BTF from relocation information previously recorded */
2134static struct btf *btfgen_get_btf(struct btfgen_info *info)
2135{
2136 struct btf *btf_new = NULL;
2137 unsigned int *ids = NULL;
2138 unsigned int i, n = btf__type_cnt(info->marked_btf);
2139 int err = 0;
2140
2141 btf_new = btf__new_empty();
2142 if (!btf_new) {
2143 err = -errno;
2144 goto err_out;
2145 }
2146
2147 ids = calloc(n, sizeof(*ids));
2148 if (!ids) {
2149 err = -errno;
2150 goto err_out;
2151 }
2152
2153 /* first pass: add all marked types to btf_new and add their new ids to the ids map */
2154 for (i = 1; i < n; i++) {
2155 const struct btf_type *cloned_type, *type;
2156 const char *name;
2157 int new_id;
2158
2159 cloned_type = btf__type_by_id(info->marked_btf, i);
2160
2161 if (cloned_type->name_off != MARKED)
2162 continue;
2163
2164 type = btf__type_by_id(info->src_btf, i);
2165
2166 /* add members for struct and union */
2167 if (btf_is_composite(type)) {
2168 struct btf_member *cloned_m, *m;
2169 unsigned short vlen;
2170 int idx_src;
2171
2172 name = btf__str_by_offset(info->src_btf, type->name_off);
2173
2174 if (btf_is_struct(type))
2175 err = btf__add_struct(btf_new, name, type->size);
2176 else
2177 err = btf__add_union(btf_new, name, type->size);
2178
2179 if (err < 0)
2180 goto err_out;
2181 new_id = err;
2182
2183 cloned_m = btf_members(cloned_type);
2184 m = btf_members(type);
2185 vlen = btf_vlen(cloned_type);
2186 for (idx_src = 0; idx_src < vlen; idx_src++, cloned_m++, m++) {
2187 /* add only members that are marked as used */
2188 if (cloned_m->name_off != MARKED)
2189 continue;
2190
2191 name = btf__str_by_offset(info->src_btf, m->name_off);
2192 err = btf__add_field(btf_new, name, m->type,
2193 btf_member_bit_offset(cloned_type, idx_src),
2194 btf_member_bitfield_size(cloned_type, idx_src));
2195 if (err < 0)
2196 goto err_out;
2197 }
2198 } else {
2199 err = btf__add_type(btf_new, info->src_btf, type);
2200 if (err < 0)
2201 goto err_out;
2202 new_id = err;
2203 }
2204
2205 /* add ID mapping */
2206 ids[i] = new_id;
2207 }
2208
2209 /* second pass: fix up type ids */
2210 for (i = 1; i < btf__type_cnt(btf_new); i++) {
2211 struct btf_type *btf_type = (struct btf_type *) btf__type_by_id(btf_new, i);
2212
2213 err = btf_type_visit_type_ids(btf_type, btfgen_remap_id, ids);
2214 if (err)
2215 goto err_out;
2216 }
2217
2218 free(ids);
2219 return btf_new;
2220
2221err_out:
2222 btf__free(btf_new);
2223 free(ids);
2224 errno = -err;
2225 return NULL;
2226}
2227
2228/* Create minimized BTF file for a set of BPF objects.
2229 *
2230 * The BTFGen algorithm is divided in two main parts: (1) collect the
2231 * BTF types that are involved in relocations and (2) generate the BTF
2232 * object using the collected types.
2233 *
2234 * In order to collect the types involved in the relocations, we parse
2235 * the BTF and BTF.ext sections of the BPF objects and use
2236 * bpf_core_calc_relo_insn() to get the target specification, this
2237 * indicates how the types and fields are used in a relocation.
2238 *
2239 * Types are recorded in different ways according to the kind of the
2240 * relocation. For field-based relocations only the members that are
2241 * actually used are saved in order to reduce the size of the generated
2242 * BTF file. For type-based relocations empty struct / unions are
2243 * generated and for enum-based relocations the whole type is saved.
2244 *
2245 * The second part of the algorithm generates the BTF object. It creates
2246 * an empty BTF object and fills it with the types recorded in the
2247 * previous step. This function takes care of only adding the structure
2248 * and union members that were marked as used and it also fixes up the
2249 * type IDs on the generated BTF object.
2250 */
2251static int minimize_btf(const char *src_btf, const char *dst_btf, const char *objspaths[])
2252{
2253 struct btfgen_info *info;
2254 struct btf *btf_new = NULL;
2255 int err, i;
2256
2257 info = btfgen_new_info(src_btf);
2258 if (!info) {
2259 err = -errno;
2260 p_err("failed to allocate info structure: %s", strerror(errno));
2261 goto out;
2262 }
2263
2264 for (i = 0; objspaths[i] != NULL; i++) {
2265 err = btfgen_record_obj(info, objspaths[i]);
2266 if (err) {
2267 p_err("error recording relocations for %s: %s", objspaths[i],
2268 strerror(errno));
2269 goto out;
2270 }
2271 }
2272
2273 btf_new = btfgen_get_btf(info);
2274 if (!btf_new) {
2275 err = -errno;
2276 p_err("error generating BTF: %s", strerror(errno));
2277 goto out;
2278 }
2279
2280 err = btf_save_raw(btf_new, dst_btf);
2281 if (err) {
2282 p_err("error saving btf file: %s", strerror(errno));
2283 goto out;
2284 }
2285
2286out:
2287 btf__free(btf_new);
2288 btfgen_free_info(info);
2289
2290 return err;
2291}
2292
2293static int do_min_core_btf(int argc, char **argv)
2294{
2295 const char *input, *output, **objs;
2296 int i, err;
2297
2298 if (!REQ_ARGS(3)) {
2299 usage();
2300 return -1;
2301 }
2302
2303 input = GET_ARG();
2304 output = GET_ARG();
2305
2306 objs = (const char **) calloc(argc + 1, sizeof(*objs));
2307 if (!objs) {
2308 p_err("failed to allocate array for object names");
2309 return -ENOMEM;
2310 }
2311
2312 i = 0;
2313 while (argc)
2314 objs[i++] = GET_ARG();
2315
2316 err = minimize_btf(input, output, objs);
2317 free(objs);
2318 return err;
2319}
2320
2321static const struct cmd cmds[] = {
2322 { "object", do_object },
2323 { "skeleton", do_skeleton },
2324 { "subskeleton", do_subskeleton },
2325 { "min_core_btf", do_min_core_btf},
2326 { "help", do_help },
2327 { 0 }
2328};
2329
2330int do_gen(int argc, char **argv)
2331{
2332 return cmd_select(cmds, argc, argv, do_help);
2333}