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
sanitize_identifier(char * name)28 static 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
str_has_prefix(const char * str,const char * prefix)37 static bool str_has_prefix(const char *str, const char *prefix)
38 {
39 return strncmp(str, prefix, strlen(prefix)) == 0;
40 }
41
str_has_suffix(const char * str,const char * suffix)42 static 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
get_obj_name(char * name,const char * file)57 static 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
get_header_guard(char * guard,const char * obj_name,const char * suffix)67 static 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
get_map_ident(const struct bpf_map * map,char * buf,size_t buf_sz)76 static 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
get_datasec_ident(const char * sec_name,char * buf,size_t buf_sz)101 static 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
codegen_btf_dump_printf(void * ctx,const char * fmt,va_list args)119 static void codegen_btf_dump_printf(void *ctx, const char *fmt, va_list args)
120 {
121 vprintf(fmt, args);
122 }
123
codegen_datasec_def(struct bpf_object * obj,struct btf * btf,struct btf_dump * d,const struct btf_type * sec,const char * obj_name)124 static 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
find_type_for_map(struct btf * btf,const char * map_ident)212 static 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
is_internal_mmapable_map(const struct bpf_map * map,char * buf,size_t sz)234 static 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
codegen_datasecs(struct bpf_object * obj,const char * obj_name)245 static 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
283 out:
284 btf_dump__free(d);
285 return err;
286 }
287
btf_is_ptr_to_func_proto(const struct btf * btf,const struct btf_type * v)288 static 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
codegen_subskel_datasecs(struct bpf_object * obj,const char * obj_name)294 static 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
373 out:
374 btf_dump__free(d);
375 return err;
376 }
377
codegen(const char * template,...)378 static 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
print_hex(const char * data,int data_sz)437 static 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
bpf_map_mmap_sz(const struct bpf_map * map)456 static 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. */
codegen_asserts(struct bpf_object * obj,const char * obj_name)467 static 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
codegen_attach_detach(struct bpf_object * obj,const char * obj_name)532 static 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
codegen_destroy(struct bpf_object * obj,const char * obj_name)614 static 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
gen_trace(struct bpf_object * obj,const char * obj_name,const char * header_guard)658 static 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;
813 out:
814 return err;
815 }
816
817 static void
codegen_maps_skeleton(struct bpf_object * obj,size_t map_cnt,bool mmaped)818 codegen_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
862 static void
codegen_progs_skeleton(struct bpf_object * obj,size_t prog_cnt,bool populate_links)863 codegen_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
do_skeleton(int argc,char ** argv)906 static 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 = %1$s__elf_bytes(&s->data_sz); \n\
1213 \n\
1214 obj->skeleton = s; \n\
1215 return 0; \n\
1216 err: \n\
1217 bpf_object__destroy_skeleton(s); \n\
1218 return err; \n\
1219 } \n\
1220 \n\
1221 static inline const void *%1$s__elf_bytes(size_t *sz) \n\
1222 { \n\
1223 static const char data[] __attribute__((__aligned__(8))) = \"\\\n\
1224 ",
1225 obj_name
1226 );
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 *sz = sizeof(data) - 1; \n\
1236 return (const void *)data; \n\
1237 } \n\
1238 \n\
1239 #ifdef __cplusplus \n\
1240 struct %1$s *%1$s::open(const struct bpf_object_open_opts *opts) { return %1$s__open_opts(opts); }\n\
1241 struct %1$s *%1$s::open_and_load() { return %1$s__open_and_load(); } \n\
1242 int %1$s::load(struct %1$s *skel) { return %1$s__load(skel); } \n\
1243 int %1$s::attach(struct %1$s *skel) { return %1$s__attach(skel); } \n\
1244 void %1$s::detach(struct %1$s *skel) { %1$s__detach(skel); } \n\
1245 void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); } \n\
1246 const void *%1$s::elf_bytes(size_t *sz) { return %1$s__elf_bytes(sz); } \n\
1247 #endif /* __cplusplus */ \n\
1248 \n\
1249 ",
1250 obj_name);
1251
1252 codegen_asserts(obj, obj_name);
1253
1254 codegen("\
1255 \n\
1256 \n\
1257 #endif /* %1$s */ \n\
1258 ",
1259 header_guard);
1260 err = 0;
1261 out:
1262 bpf_object__close(obj);
1263 if (obj_data)
1264 munmap(obj_data, mmap_sz);
1265 close(fd);
1266 return err;
1267 }
1268
1269 /* Subskeletons are like skeletons, except they don't own the bpf_object,
1270 * associated maps, links, etc. Instead, they know about the existence of
1271 * variables, maps, programs and are able to find their locations
1272 * _at runtime_ from an already loaded bpf_object.
1273 *
1274 * This allows for library-like BPF objects to have userspace counterparts
1275 * with access to their own items without having to know anything about the
1276 * final BPF object that the library was linked into.
1277 */
do_subskeleton(int argc,char ** argv)1278 static int do_subskeleton(int argc, char **argv)
1279 {
1280 char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SUBSKEL_H__")];
1281 size_t i, len, file_sz, map_cnt = 0, prog_cnt = 0, mmap_sz, var_cnt = 0, var_idx = 0;
1282 DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
1283 char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
1284 struct bpf_object *obj = NULL;
1285 const char *file, *var_name;
1286 char ident[256];
1287 int fd, err = -1, map_type_id;
1288 const struct bpf_map *map;
1289 struct bpf_program *prog;
1290 struct btf *btf;
1291 const struct btf_type *map_type, *var_type;
1292 const struct btf_var_secinfo *var;
1293 struct stat st;
1294
1295 if (!REQ_ARGS(1)) {
1296 usage();
1297 return -1;
1298 }
1299 file = GET_ARG();
1300
1301 while (argc) {
1302 if (!REQ_ARGS(2))
1303 return -1;
1304
1305 if (is_prefix(*argv, "name")) {
1306 NEXT_ARG();
1307
1308 if (obj_name[0] != '\0') {
1309 p_err("object name already specified");
1310 return -1;
1311 }
1312
1313 strncpy(obj_name, *argv, MAX_OBJ_NAME_LEN - 1);
1314 obj_name[MAX_OBJ_NAME_LEN - 1] = '\0';
1315 } else {
1316 p_err("unknown arg %s", *argv);
1317 return -1;
1318 }
1319
1320 NEXT_ARG();
1321 }
1322
1323 if (argc) {
1324 p_err("extra unknown arguments");
1325 return -1;
1326 }
1327
1328 if (use_loader) {
1329 p_err("cannot use loader for subskeletons");
1330 return -1;
1331 }
1332
1333 if (stat(file, &st)) {
1334 p_err("failed to stat() %s: %s", file, strerror(errno));
1335 return -1;
1336 }
1337 file_sz = st.st_size;
1338 mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
1339 fd = open(file, O_RDONLY);
1340 if (fd < 0) {
1341 p_err("failed to open() %s: %s", file, strerror(errno));
1342 return -1;
1343 }
1344 obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
1345 if (obj_data == MAP_FAILED) {
1346 obj_data = NULL;
1347 p_err("failed to mmap() %s: %s", file, strerror(errno));
1348 goto out;
1349 }
1350 if (obj_name[0] == '\0')
1351 get_obj_name(obj_name, file);
1352
1353 /* The empty object name allows us to use bpf_map__name and produce
1354 * ELF section names out of it. (".data" instead of "obj.data")
1355 */
1356 opts.object_name = "";
1357 obj = bpf_object__open_mem(obj_data, file_sz, &opts);
1358 if (!obj) {
1359 char err_buf[256];
1360
1361 libbpf_strerror(errno, err_buf, sizeof(err_buf));
1362 p_err("failed to open BPF object file: %s", err_buf);
1363 obj = NULL;
1364 goto out;
1365 }
1366
1367 btf = bpf_object__btf(obj);
1368 if (!btf) {
1369 err = -1;
1370 p_err("need btf type information for %s", obj_name);
1371 goto out;
1372 }
1373
1374 bpf_object__for_each_program(prog, obj) {
1375 prog_cnt++;
1376 }
1377
1378 /* First, count how many variables we have to find.
1379 * We need this in advance so the subskel can allocate the right
1380 * amount of storage.
1381 */
1382 bpf_object__for_each_map(map, obj) {
1383 if (!get_map_ident(map, ident, sizeof(ident)))
1384 continue;
1385
1386 /* Also count all maps that have a name */
1387 map_cnt++;
1388
1389 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
1390 continue;
1391
1392 map_type_id = bpf_map__btf_value_type_id(map);
1393 if (map_type_id <= 0) {
1394 err = map_type_id;
1395 goto out;
1396 }
1397 map_type = btf__type_by_id(btf, map_type_id);
1398
1399 var = btf_var_secinfos(map_type);
1400 len = btf_vlen(map_type);
1401 for (i = 0; i < len; i++, var++) {
1402 var_type = btf__type_by_id(btf, var->type);
1403
1404 if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
1405 continue;
1406
1407 var_cnt++;
1408 }
1409 }
1410
1411 get_header_guard(header_guard, obj_name, "SUBSKEL_H");
1412 codegen("\
1413 \n\
1414 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
1415 \n\
1416 /* THIS FILE IS AUTOGENERATED! */ \n\
1417 #ifndef %2$s \n\
1418 #define %2$s \n\
1419 \n\
1420 #include <errno.h> \n\
1421 #include <stdlib.h> \n\
1422 #include <bpf/libbpf.h> \n\
1423 \n\
1424 struct %1$s { \n\
1425 struct bpf_object *obj; \n\
1426 struct bpf_object_subskeleton *subskel; \n\
1427 ", obj_name, header_guard);
1428
1429 if (map_cnt) {
1430 printf("\tstruct {\n");
1431 bpf_object__for_each_map(map, obj) {
1432 if (!get_map_ident(map, ident, sizeof(ident)))
1433 continue;
1434 printf("\t\tstruct bpf_map *%s;\n", ident);
1435 }
1436 printf("\t} maps;\n");
1437 }
1438
1439 if (prog_cnt) {
1440 printf("\tstruct {\n");
1441 bpf_object__for_each_program(prog, obj) {
1442 printf("\t\tstruct bpf_program *%s;\n",
1443 bpf_program__name(prog));
1444 }
1445 printf("\t} progs;\n");
1446 }
1447
1448 err = codegen_subskel_datasecs(obj, obj_name);
1449 if (err)
1450 goto out;
1451
1452 /* emit code that will allocate enough storage for all symbols */
1453 codegen("\
1454 \n\
1455 \n\
1456 #ifdef __cplusplus \n\
1457 static inline struct %1$s *open(const struct bpf_object *src);\n\
1458 static inline void destroy(struct %1$s *skel); \n\
1459 #endif /* __cplusplus */ \n\
1460 }; \n\
1461 \n\
1462 static inline void \n\
1463 %1$s__destroy(struct %1$s *skel) \n\
1464 { \n\
1465 if (!skel) \n\
1466 return; \n\
1467 if (skel->subskel) \n\
1468 bpf_object__destroy_subskeleton(skel->subskel);\n\
1469 free(skel); \n\
1470 } \n\
1471 \n\
1472 static inline struct %1$s * \n\
1473 %1$s__open(const struct bpf_object *src) \n\
1474 { \n\
1475 struct %1$s *obj; \n\
1476 struct bpf_object_subskeleton *s; \n\
1477 int err; \n\
1478 \n\
1479 obj = (struct %1$s *)calloc(1, sizeof(*obj)); \n\
1480 if (!obj) { \n\
1481 err = -ENOMEM; \n\
1482 goto err; \n\
1483 } \n\
1484 s = (struct bpf_object_subskeleton *)calloc(1, sizeof(*s));\n\
1485 if (!s) { \n\
1486 err = -ENOMEM; \n\
1487 goto err; \n\
1488 } \n\
1489 s->sz = sizeof(*s); \n\
1490 s->obj = src; \n\
1491 s->var_skel_sz = sizeof(*s->vars); \n\
1492 obj->subskel = s; \n\
1493 \n\
1494 /* vars */ \n\
1495 s->var_cnt = %2$d; \n\
1496 s->vars = (struct bpf_var_skeleton *)calloc(%2$d, sizeof(*s->vars));\n\
1497 if (!s->vars) { \n\
1498 err = -ENOMEM; \n\
1499 goto err; \n\
1500 } \n\
1501 ",
1502 obj_name, var_cnt
1503 );
1504
1505 /* walk through each symbol and emit the runtime representation */
1506 bpf_object__for_each_map(map, obj) {
1507 if (!is_internal_mmapable_map(map, ident, sizeof(ident)))
1508 continue;
1509
1510 map_type_id = bpf_map__btf_value_type_id(map);
1511 if (map_type_id <= 0)
1512 /* skip over internal maps with no type*/
1513 continue;
1514
1515 map_type = btf__type_by_id(btf, map_type_id);
1516 var = btf_var_secinfos(map_type);
1517 len = btf_vlen(map_type);
1518 for (i = 0; i < len; i++, var++) {
1519 var_type = btf__type_by_id(btf, var->type);
1520 var_name = btf__name_by_offset(btf, var_type->name_off);
1521
1522 if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
1523 continue;
1524
1525 /* Note that we use the dot prefix in .data as the
1526 * field access operator i.e. maps%s becomes maps.data
1527 */
1528 codegen("\
1529 \n\
1530 \n\
1531 s->vars[%3$d].name = \"%1$s\"; \n\
1532 s->vars[%3$d].map = &obj->maps.%2$s; \n\
1533 s->vars[%3$d].addr = (void **) &obj->%2$s.%1$s;\n\
1534 ", var_name, ident, var_idx);
1535
1536 var_idx++;
1537 }
1538 }
1539
1540 codegen_maps_skeleton(obj, map_cnt, false /*mmaped*/);
1541 codegen_progs_skeleton(obj, prog_cnt, false /*links*/);
1542
1543 codegen("\
1544 \n\
1545 \n\
1546 err = bpf_object__open_subskeleton(s); \n\
1547 if (err) \n\
1548 goto err; \n\
1549 \n\
1550 return obj; \n\
1551 err: \n\
1552 %1$s__destroy(obj); \n\
1553 errno = -err; \n\
1554 return NULL; \n\
1555 } \n\
1556 \n\
1557 #ifdef __cplusplus \n\
1558 struct %1$s *%1$s::open(const struct bpf_object *src) { return %1$s__open(src); }\n\
1559 void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); }\n\
1560 #endif /* __cplusplus */ \n\
1561 \n\
1562 #endif /* %2$s */ \n\
1563 ",
1564 obj_name, header_guard);
1565 err = 0;
1566 out:
1567 bpf_object__close(obj);
1568 if (obj_data)
1569 munmap(obj_data, mmap_sz);
1570 close(fd);
1571 return err;
1572 }
1573
do_object(int argc,char ** argv)1574 static int do_object(int argc, char **argv)
1575 {
1576 struct bpf_linker *linker;
1577 const char *output_file, *file;
1578 int err = 0;
1579
1580 if (!REQ_ARGS(2)) {
1581 usage();
1582 return -1;
1583 }
1584
1585 output_file = GET_ARG();
1586
1587 linker = bpf_linker__new(output_file, NULL);
1588 if (!linker) {
1589 p_err("failed to create BPF linker instance");
1590 return -1;
1591 }
1592
1593 while (argc) {
1594 file = GET_ARG();
1595
1596 err = bpf_linker__add_file(linker, file, NULL);
1597 if (err) {
1598 p_err("failed to link '%s': %s (%d)", file, strerror(errno), errno);
1599 goto out;
1600 }
1601 }
1602
1603 err = bpf_linker__finalize(linker);
1604 if (err) {
1605 p_err("failed to finalize ELF file: %s (%d)", strerror(errno), errno);
1606 goto out;
1607 }
1608
1609 err = 0;
1610 out:
1611 bpf_linker__free(linker);
1612 return err;
1613 }
1614
do_help(int argc,char ** argv)1615 static int do_help(int argc, char **argv)
1616 {
1617 if (json_output) {
1618 jsonw_null(json_wtr);
1619 return 0;
1620 }
1621
1622 fprintf(stderr,
1623 "Usage: %1$s %2$s object OUTPUT_FILE INPUT_FILE [INPUT_FILE...]\n"
1624 " %1$s %2$s skeleton FILE [name OBJECT_NAME]\n"
1625 " %1$s %2$s subskeleton FILE [name OBJECT_NAME]\n"
1626 " %1$s %2$s min_core_btf INPUT OUTPUT OBJECT [OBJECT...]\n"
1627 " %1$s %2$s help\n"
1628 "\n"
1629 " " HELP_SPEC_OPTIONS " |\n"
1630 " {-L|--use-loader} }\n"
1631 "",
1632 bin_name, "gen");
1633
1634 return 0;
1635 }
1636
btf_save_raw(const struct btf * btf,const char * path)1637 static int btf_save_raw(const struct btf *btf, const char *path)
1638 {
1639 const void *data;
1640 FILE *f = NULL;
1641 __u32 data_sz;
1642 int err = 0;
1643
1644 data = btf__raw_data(btf, &data_sz);
1645 if (!data)
1646 return -ENOMEM;
1647
1648 f = fopen(path, "wb");
1649 if (!f)
1650 return -errno;
1651
1652 if (fwrite(data, 1, data_sz, f) != data_sz)
1653 err = -errno;
1654
1655 fclose(f);
1656 return err;
1657 }
1658
1659 struct btfgen_info {
1660 struct btf *src_btf;
1661 struct btf *marked_btf; /* btf structure used to mark used types */
1662 };
1663
btfgen_hash_fn(long key,void * ctx)1664 static size_t btfgen_hash_fn(long key, void *ctx)
1665 {
1666 return key;
1667 }
1668
btfgen_equal_fn(long k1,long k2,void * ctx)1669 static bool btfgen_equal_fn(long k1, long k2, void *ctx)
1670 {
1671 return k1 == k2;
1672 }
1673
btfgen_free_info(struct btfgen_info * info)1674 static void btfgen_free_info(struct btfgen_info *info)
1675 {
1676 if (!info)
1677 return;
1678
1679 btf__free(info->src_btf);
1680 btf__free(info->marked_btf);
1681
1682 free(info);
1683 }
1684
1685 static struct btfgen_info *
btfgen_new_info(const char * targ_btf_path)1686 btfgen_new_info(const char *targ_btf_path)
1687 {
1688 struct btfgen_info *info;
1689 int err;
1690
1691 info = calloc(1, sizeof(*info));
1692 if (!info)
1693 return NULL;
1694
1695 info->src_btf = btf__parse(targ_btf_path, NULL);
1696 if (!info->src_btf) {
1697 err = -errno;
1698 p_err("failed parsing '%s' BTF file: %s", targ_btf_path, strerror(errno));
1699 goto err_out;
1700 }
1701
1702 info->marked_btf = btf__parse(targ_btf_path, NULL);
1703 if (!info->marked_btf) {
1704 err = -errno;
1705 p_err("failed parsing '%s' BTF file: %s", targ_btf_path, strerror(errno));
1706 goto err_out;
1707 }
1708
1709 return info;
1710
1711 err_out:
1712 btfgen_free_info(info);
1713 errno = -err;
1714 return NULL;
1715 }
1716
1717 #define MARKED UINT32_MAX
1718
btfgen_mark_member(struct btfgen_info * info,int type_id,int idx)1719 static void btfgen_mark_member(struct btfgen_info *info, int type_id, int idx)
1720 {
1721 const struct btf_type *t = btf__type_by_id(info->marked_btf, type_id);
1722 struct btf_member *m = btf_members(t) + idx;
1723
1724 m->name_off = MARKED;
1725 }
1726
1727 static int
btfgen_mark_type(struct btfgen_info * info,unsigned int type_id,bool follow_pointers)1728 btfgen_mark_type(struct btfgen_info *info, unsigned int type_id, bool follow_pointers)
1729 {
1730 const struct btf_type *btf_type = btf__type_by_id(info->src_btf, type_id);
1731 struct btf_type *cloned_type;
1732 struct btf_param *param;
1733 struct btf_array *array;
1734 int err, i;
1735
1736 if (type_id == 0)
1737 return 0;
1738
1739 /* mark type on cloned BTF as used */
1740 cloned_type = (struct btf_type *) btf__type_by_id(info->marked_btf, type_id);
1741 cloned_type->name_off = MARKED;
1742
1743 /* recursively mark other types needed by it */
1744 switch (btf_kind(btf_type)) {
1745 case BTF_KIND_UNKN:
1746 case BTF_KIND_INT:
1747 case BTF_KIND_FLOAT:
1748 case BTF_KIND_ENUM:
1749 case BTF_KIND_ENUM64:
1750 case BTF_KIND_STRUCT:
1751 case BTF_KIND_UNION:
1752 break;
1753 case BTF_KIND_PTR:
1754 if (follow_pointers) {
1755 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1756 if (err)
1757 return err;
1758 }
1759 break;
1760 case BTF_KIND_CONST:
1761 case BTF_KIND_RESTRICT:
1762 case BTF_KIND_VOLATILE:
1763 case BTF_KIND_TYPEDEF:
1764 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1765 if (err)
1766 return err;
1767 break;
1768 case BTF_KIND_ARRAY:
1769 array = btf_array(btf_type);
1770
1771 /* mark array type */
1772 err = btfgen_mark_type(info, array->type, follow_pointers);
1773 /* mark array's index type */
1774 err = err ? : btfgen_mark_type(info, array->index_type, follow_pointers);
1775 if (err)
1776 return err;
1777 break;
1778 case BTF_KIND_FUNC_PROTO:
1779 /* mark ret type */
1780 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
1781 if (err)
1782 return err;
1783
1784 /* mark parameters types */
1785 param = btf_params(btf_type);
1786 for (i = 0; i < btf_vlen(btf_type); i++) {
1787 err = btfgen_mark_type(info, param->type, follow_pointers);
1788 if (err)
1789 return err;
1790 param++;
1791 }
1792 break;
1793 /* tells if some other type needs to be handled */
1794 default:
1795 p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
1796 return -EINVAL;
1797 }
1798
1799 return 0;
1800 }
1801
btfgen_record_field_relo(struct btfgen_info * info,struct bpf_core_spec * targ_spec)1802 static int btfgen_record_field_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1803 {
1804 struct btf *btf = info->src_btf;
1805 const struct btf_type *btf_type;
1806 struct btf_member *btf_member;
1807 struct btf_array *array;
1808 unsigned int type_id = targ_spec->root_type_id;
1809 int idx, err;
1810
1811 /* mark root type */
1812 btf_type = btf__type_by_id(btf, type_id);
1813 err = btfgen_mark_type(info, type_id, false);
1814 if (err)
1815 return err;
1816
1817 /* mark types for complex types (arrays, unions, structures) */
1818 for (int i = 1; i < targ_spec->raw_len; i++) {
1819 /* skip typedefs and mods */
1820 while (btf_is_mod(btf_type) || btf_is_typedef(btf_type)) {
1821 type_id = btf_type->type;
1822 btf_type = btf__type_by_id(btf, type_id);
1823 }
1824
1825 switch (btf_kind(btf_type)) {
1826 case BTF_KIND_STRUCT:
1827 case BTF_KIND_UNION:
1828 idx = targ_spec->raw_spec[i];
1829 btf_member = btf_members(btf_type) + idx;
1830
1831 /* mark member */
1832 btfgen_mark_member(info, type_id, idx);
1833
1834 /* mark member's type */
1835 type_id = btf_member->type;
1836 btf_type = btf__type_by_id(btf, type_id);
1837 err = btfgen_mark_type(info, type_id, false);
1838 if (err)
1839 return err;
1840 break;
1841 case BTF_KIND_ARRAY:
1842 array = btf_array(btf_type);
1843 type_id = array->type;
1844 btf_type = btf__type_by_id(btf, type_id);
1845 break;
1846 default:
1847 p_err("unsupported kind: %s (%d)",
1848 btf_kind_str(btf_type), btf_type->type);
1849 return -EINVAL;
1850 }
1851 }
1852
1853 return 0;
1854 }
1855
1856 /* Mark types, members, and member types. Compared to btfgen_record_field_relo,
1857 * this function does not rely on the target spec for inferring members, but
1858 * uses the associated BTF.
1859 *
1860 * The `behind_ptr` argument is used to stop marking of composite types reached
1861 * through a pointer. This way, we can keep BTF size in check while providing
1862 * reasonable match semantics.
1863 */
btfgen_mark_type_match(struct btfgen_info * info,__u32 type_id,bool behind_ptr)1864 static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool behind_ptr)
1865 {
1866 const struct btf_type *btf_type;
1867 struct btf *btf = info->src_btf;
1868 struct btf_type *cloned_type;
1869 int i, err;
1870
1871 if (type_id == 0)
1872 return 0;
1873
1874 btf_type = btf__type_by_id(btf, type_id);
1875 /* mark type on cloned BTF as used */
1876 cloned_type = (struct btf_type *)btf__type_by_id(info->marked_btf, type_id);
1877 cloned_type->name_off = MARKED;
1878
1879 switch (btf_kind(btf_type)) {
1880 case BTF_KIND_UNKN:
1881 case BTF_KIND_INT:
1882 case BTF_KIND_FLOAT:
1883 case BTF_KIND_ENUM:
1884 case BTF_KIND_ENUM64:
1885 break;
1886 case BTF_KIND_STRUCT:
1887 case BTF_KIND_UNION: {
1888 struct btf_member *m = btf_members(btf_type);
1889 __u16 vlen = btf_vlen(btf_type);
1890
1891 if (behind_ptr)
1892 break;
1893
1894 for (i = 0; i < vlen; i++, m++) {
1895 /* mark member */
1896 btfgen_mark_member(info, type_id, i);
1897
1898 /* mark member's type */
1899 err = btfgen_mark_type_match(info, m->type, false);
1900 if (err)
1901 return err;
1902 }
1903 break;
1904 }
1905 case BTF_KIND_CONST:
1906 case BTF_KIND_FWD:
1907 case BTF_KIND_RESTRICT:
1908 case BTF_KIND_TYPEDEF:
1909 case BTF_KIND_VOLATILE:
1910 return btfgen_mark_type_match(info, btf_type->type, behind_ptr);
1911 case BTF_KIND_PTR:
1912 return btfgen_mark_type_match(info, btf_type->type, true);
1913 case BTF_KIND_ARRAY: {
1914 struct btf_array *array;
1915
1916 array = btf_array(btf_type);
1917 /* mark array type */
1918 err = btfgen_mark_type_match(info, array->type, false);
1919 /* mark array's index type */
1920 err = err ? : btfgen_mark_type_match(info, array->index_type, false);
1921 if (err)
1922 return err;
1923 break;
1924 }
1925 case BTF_KIND_FUNC_PROTO: {
1926 __u16 vlen = btf_vlen(btf_type);
1927 struct btf_param *param;
1928
1929 /* mark ret type */
1930 err = btfgen_mark_type_match(info, btf_type->type, false);
1931 if (err)
1932 return err;
1933
1934 /* mark parameters types */
1935 param = btf_params(btf_type);
1936 for (i = 0; i < vlen; i++) {
1937 err = btfgen_mark_type_match(info, param->type, false);
1938 if (err)
1939 return err;
1940 param++;
1941 }
1942 break;
1943 }
1944 /* tells if some other type needs to be handled */
1945 default:
1946 p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
1947 return -EINVAL;
1948 }
1949
1950 return 0;
1951 }
1952
1953 /* Mark types, members, and member types. Compared to btfgen_record_field_relo,
1954 * this function does not rely on the target spec for inferring members, but
1955 * uses the associated BTF.
1956 */
btfgen_record_type_match_relo(struct btfgen_info * info,struct bpf_core_spec * targ_spec)1957 static int btfgen_record_type_match_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1958 {
1959 return btfgen_mark_type_match(info, targ_spec->root_type_id, false);
1960 }
1961
btfgen_record_type_relo(struct btfgen_info * info,struct bpf_core_spec * targ_spec)1962 static int btfgen_record_type_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1963 {
1964 return btfgen_mark_type(info, targ_spec->root_type_id, true);
1965 }
1966
btfgen_record_enumval_relo(struct btfgen_info * info,struct bpf_core_spec * targ_spec)1967 static int btfgen_record_enumval_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
1968 {
1969 return btfgen_mark_type(info, targ_spec->root_type_id, false);
1970 }
1971
btfgen_record_reloc(struct btfgen_info * info,struct bpf_core_spec * res)1972 static int btfgen_record_reloc(struct btfgen_info *info, struct bpf_core_spec *res)
1973 {
1974 switch (res->relo_kind) {
1975 case BPF_CORE_FIELD_BYTE_OFFSET:
1976 case BPF_CORE_FIELD_BYTE_SIZE:
1977 case BPF_CORE_FIELD_EXISTS:
1978 case BPF_CORE_FIELD_SIGNED:
1979 case BPF_CORE_FIELD_LSHIFT_U64:
1980 case BPF_CORE_FIELD_RSHIFT_U64:
1981 return btfgen_record_field_relo(info, res);
1982 case BPF_CORE_TYPE_ID_LOCAL: /* BPF_CORE_TYPE_ID_LOCAL doesn't require kernel BTF */
1983 return 0;
1984 case BPF_CORE_TYPE_ID_TARGET:
1985 case BPF_CORE_TYPE_EXISTS:
1986 case BPF_CORE_TYPE_SIZE:
1987 return btfgen_record_type_relo(info, res);
1988 case BPF_CORE_TYPE_MATCHES:
1989 return btfgen_record_type_match_relo(info, res);
1990 case BPF_CORE_ENUMVAL_EXISTS:
1991 case BPF_CORE_ENUMVAL_VALUE:
1992 return btfgen_record_enumval_relo(info, res);
1993 default:
1994 return -EINVAL;
1995 }
1996 }
1997
1998 static struct bpf_core_cand_list *
btfgen_find_cands(const struct btf * local_btf,const struct btf * targ_btf,__u32 local_id)1999 btfgen_find_cands(const struct btf *local_btf, const struct btf *targ_btf, __u32 local_id)
2000 {
2001 const struct btf_type *local_type;
2002 struct bpf_core_cand_list *cands = NULL;
2003 struct bpf_core_cand local_cand = {};
2004 size_t local_essent_len;
2005 const char *local_name;
2006 int err;
2007
2008 local_cand.btf = local_btf;
2009 local_cand.id = local_id;
2010
2011 local_type = btf__type_by_id(local_btf, local_id);
2012 if (!local_type) {
2013 err = -EINVAL;
2014 goto err_out;
2015 }
2016
2017 local_name = btf__name_by_offset(local_btf, local_type->name_off);
2018 if (!local_name) {
2019 err = -EINVAL;
2020 goto err_out;
2021 }
2022 local_essent_len = bpf_core_essential_name_len(local_name);
2023
2024 cands = calloc(1, sizeof(*cands));
2025 if (!cands)
2026 return NULL;
2027
2028 err = bpf_core_add_cands(&local_cand, local_essent_len, targ_btf, "vmlinux", 1, cands);
2029 if (err)
2030 goto err_out;
2031
2032 return cands;
2033
2034 err_out:
2035 bpf_core_free_cands(cands);
2036 errno = -err;
2037 return NULL;
2038 }
2039
2040 /* Record relocation information for a single BPF object */
btfgen_record_obj(struct btfgen_info * info,const char * obj_path)2041 static int btfgen_record_obj(struct btfgen_info *info, const char *obj_path)
2042 {
2043 const struct btf_ext_info_sec *sec;
2044 const struct bpf_core_relo *relo;
2045 const struct btf_ext_info *seg;
2046 struct hashmap_entry *entry;
2047 struct hashmap *cand_cache = NULL;
2048 struct btf_ext *btf_ext = NULL;
2049 unsigned int relo_idx;
2050 struct btf *btf = NULL;
2051 size_t i;
2052 int err;
2053
2054 btf = btf__parse(obj_path, &btf_ext);
2055 if (!btf) {
2056 err = -errno;
2057 p_err("failed to parse BPF object '%s': %s", obj_path, strerror(errno));
2058 return err;
2059 }
2060
2061 if (!btf_ext) {
2062 p_err("failed to parse BPF object '%s': section %s not found",
2063 obj_path, BTF_EXT_ELF_SEC);
2064 err = -EINVAL;
2065 goto out;
2066 }
2067
2068 if (btf_ext->core_relo_info.len == 0) {
2069 err = 0;
2070 goto out;
2071 }
2072
2073 cand_cache = hashmap__new(btfgen_hash_fn, btfgen_equal_fn, NULL);
2074 if (IS_ERR(cand_cache)) {
2075 err = PTR_ERR(cand_cache);
2076 goto out;
2077 }
2078
2079 seg = &btf_ext->core_relo_info;
2080 for_each_btf_ext_sec(seg, sec) {
2081 for_each_btf_ext_rec(seg, sec, relo_idx, relo) {
2082 struct bpf_core_spec specs_scratch[3] = {};
2083 struct bpf_core_relo_res targ_res = {};
2084 struct bpf_core_cand_list *cands = NULL;
2085 const char *sec_name = btf__name_by_offset(btf, sec->sec_name_off);
2086
2087 if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
2088 !hashmap__find(cand_cache, relo->type_id, &cands)) {
2089 cands = btfgen_find_cands(btf, info->src_btf, relo->type_id);
2090 if (!cands) {
2091 err = -errno;
2092 goto out;
2093 }
2094
2095 err = hashmap__set(cand_cache, relo->type_id, cands,
2096 NULL, NULL);
2097 if (err)
2098 goto out;
2099 }
2100
2101 err = bpf_core_calc_relo_insn(sec_name, relo, relo_idx, btf, cands,
2102 specs_scratch, &targ_res);
2103 if (err)
2104 goto out;
2105
2106 /* specs_scratch[2] is the target spec */
2107 err = btfgen_record_reloc(info, &specs_scratch[2]);
2108 if (err)
2109 goto out;
2110 }
2111 }
2112
2113 out:
2114 btf__free(btf);
2115 btf_ext__free(btf_ext);
2116
2117 if (!IS_ERR_OR_NULL(cand_cache)) {
2118 hashmap__for_each_entry(cand_cache, entry, i) {
2119 bpf_core_free_cands(entry->pvalue);
2120 }
2121 hashmap__free(cand_cache);
2122 }
2123
2124 return err;
2125 }
2126
btfgen_remap_id(__u32 * type_id,void * ctx)2127 static int btfgen_remap_id(__u32 *type_id, void *ctx)
2128 {
2129 unsigned int *ids = ctx;
2130
2131 *type_id = ids[*type_id];
2132
2133 return 0;
2134 }
2135
2136 /* Generate BTF from relocation information previously recorded */
btfgen_get_btf(struct btfgen_info * info)2137 static struct btf *btfgen_get_btf(struct btfgen_info *info)
2138 {
2139 struct btf *btf_new = NULL;
2140 unsigned int *ids = NULL;
2141 unsigned int i, n = btf__type_cnt(info->marked_btf);
2142 int err = 0;
2143
2144 btf_new = btf__new_empty();
2145 if (!btf_new) {
2146 err = -errno;
2147 goto err_out;
2148 }
2149
2150 ids = calloc(n, sizeof(*ids));
2151 if (!ids) {
2152 err = -errno;
2153 goto err_out;
2154 }
2155
2156 /* first pass: add all marked types to btf_new and add their new ids to the ids map */
2157 for (i = 1; i < n; i++) {
2158 const struct btf_type *cloned_type, *type;
2159 const char *name;
2160 int new_id;
2161
2162 cloned_type = btf__type_by_id(info->marked_btf, i);
2163
2164 if (cloned_type->name_off != MARKED)
2165 continue;
2166
2167 type = btf__type_by_id(info->src_btf, i);
2168
2169 /* add members for struct and union */
2170 if (btf_is_composite(type)) {
2171 struct btf_member *cloned_m, *m;
2172 unsigned short vlen;
2173 int idx_src;
2174
2175 name = btf__str_by_offset(info->src_btf, type->name_off);
2176
2177 if (btf_is_struct(type))
2178 err = btf__add_struct(btf_new, name, type->size);
2179 else
2180 err = btf__add_union(btf_new, name, type->size);
2181
2182 if (err < 0)
2183 goto err_out;
2184 new_id = err;
2185
2186 cloned_m = btf_members(cloned_type);
2187 m = btf_members(type);
2188 vlen = btf_vlen(cloned_type);
2189 for (idx_src = 0; idx_src < vlen; idx_src++, cloned_m++, m++) {
2190 /* add only members that are marked as used */
2191 if (cloned_m->name_off != MARKED)
2192 continue;
2193
2194 name = btf__str_by_offset(info->src_btf, m->name_off);
2195 err = btf__add_field(btf_new, name, m->type,
2196 btf_member_bit_offset(cloned_type, idx_src),
2197 btf_member_bitfield_size(cloned_type, idx_src));
2198 if (err < 0)
2199 goto err_out;
2200 }
2201 } else {
2202 err = btf__add_type(btf_new, info->src_btf, type);
2203 if (err < 0)
2204 goto err_out;
2205 new_id = err;
2206 }
2207
2208 /* add ID mapping */
2209 ids[i] = new_id;
2210 }
2211
2212 /* second pass: fix up type ids */
2213 for (i = 1; i < btf__type_cnt(btf_new); i++) {
2214 struct btf_type *btf_type = (struct btf_type *) btf__type_by_id(btf_new, i);
2215
2216 err = btf_type_visit_type_ids(btf_type, btfgen_remap_id, ids);
2217 if (err)
2218 goto err_out;
2219 }
2220
2221 free(ids);
2222 return btf_new;
2223
2224 err_out:
2225 btf__free(btf_new);
2226 free(ids);
2227 errno = -err;
2228 return NULL;
2229 }
2230
2231 /* Create minimized BTF file for a set of BPF objects.
2232 *
2233 * The BTFGen algorithm is divided in two main parts: (1) collect the
2234 * BTF types that are involved in relocations and (2) generate the BTF
2235 * object using the collected types.
2236 *
2237 * In order to collect the types involved in the relocations, we parse
2238 * the BTF and BTF.ext sections of the BPF objects and use
2239 * bpf_core_calc_relo_insn() to get the target specification, this
2240 * indicates how the types and fields are used in a relocation.
2241 *
2242 * Types are recorded in different ways according to the kind of the
2243 * relocation. For field-based relocations only the members that are
2244 * actually used are saved in order to reduce the size of the generated
2245 * BTF file. For type-based relocations empty struct / unions are
2246 * generated and for enum-based relocations the whole type is saved.
2247 *
2248 * The second part of the algorithm generates the BTF object. It creates
2249 * an empty BTF object and fills it with the types recorded in the
2250 * previous step. This function takes care of only adding the structure
2251 * and union members that were marked as used and it also fixes up the
2252 * type IDs on the generated BTF object.
2253 */
minimize_btf(const char * src_btf,const char * dst_btf,const char * objspaths[])2254 static int minimize_btf(const char *src_btf, const char *dst_btf, const char *objspaths[])
2255 {
2256 struct btfgen_info *info;
2257 struct btf *btf_new = NULL;
2258 int err, i;
2259
2260 info = btfgen_new_info(src_btf);
2261 if (!info) {
2262 err = -errno;
2263 p_err("failed to allocate info structure: %s", strerror(errno));
2264 goto out;
2265 }
2266
2267 for (i = 0; objspaths[i] != NULL; i++) {
2268 err = btfgen_record_obj(info, objspaths[i]);
2269 if (err) {
2270 p_err("error recording relocations for %s: %s", objspaths[i],
2271 strerror(errno));
2272 goto out;
2273 }
2274 }
2275
2276 btf_new = btfgen_get_btf(info);
2277 if (!btf_new) {
2278 err = -errno;
2279 p_err("error generating BTF: %s", strerror(errno));
2280 goto out;
2281 }
2282
2283 err = btf_save_raw(btf_new, dst_btf);
2284 if (err) {
2285 p_err("error saving btf file: %s", strerror(errno));
2286 goto out;
2287 }
2288
2289 out:
2290 btf__free(btf_new);
2291 btfgen_free_info(info);
2292
2293 return err;
2294 }
2295
do_min_core_btf(int argc,char ** argv)2296 static int do_min_core_btf(int argc, char **argv)
2297 {
2298 const char *input, *output, **objs;
2299 int i, err;
2300
2301 if (!REQ_ARGS(3)) {
2302 usage();
2303 return -1;
2304 }
2305
2306 input = GET_ARG();
2307 output = GET_ARG();
2308
2309 objs = (const char **) calloc(argc + 1, sizeof(*objs));
2310 if (!objs) {
2311 p_err("failed to allocate array for object names");
2312 return -ENOMEM;
2313 }
2314
2315 i = 0;
2316 while (argc)
2317 objs[i++] = GET_ARG();
2318
2319 err = minimize_btf(input, output, objs);
2320 free(objs);
2321 return err;
2322 }
2323
2324 static const struct cmd cmds[] = {
2325 { "object", do_object },
2326 { "skeleton", do_skeleton },
2327 { "subskeleton", do_subskeleton },
2328 { "min_core_btf", do_min_core_btf},
2329 { "help", do_help },
2330 { 0 }
2331 };
2332
do_gen(int argc,char ** argv)2333 int do_gen(int argc, char **argv)
2334 {
2335 return cmd_select(cmds, argc, argv, do_help);
2336 }
2337