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 <libgen.h>
11 #include <linux/err.h>
12 #include <stdbool.h>
13 #include <stdio.h>
14 #include <string.h>
15 #include <unistd.h>
16 #include <bpf/bpf.h>
17 #include <bpf/libbpf.h>
18 #include <bpf/libbpf_internal.h>
19 #include <sys/types.h>
20 #include <sys/stat.h>
21 #include <sys/mman.h>
22 #include <bpf/btf.h>
23
24 #include "json_writer.h"
25 #include "main.h"
26
27 #define MAX_OBJ_NAME_LEN 64
28
sanitize_identifier(char * name)29 static void sanitize_identifier(char *name)
30 {
31 int i;
32
33 for (i = 0; name[i]; i++)
34 if (!isalnum(name[i]) && name[i] != '_')
35 name[i] = '_';
36 }
37
str_has_prefix(const char * str,const char * prefix)38 static bool str_has_prefix(const char *str, const char *prefix)
39 {
40 return strncmp(str, prefix, strlen(prefix)) == 0;
41 }
42
str_has_suffix(const char * str,const char * suffix)43 static bool str_has_suffix(const char *str, const char *suffix)
44 {
45 size_t i, n1 = strlen(str), n2 = strlen(suffix);
46
47 if (n1 < n2)
48 return false;
49
50 for (i = 0; i < n2; i++) {
51 if (str[n1 - i - 1] != suffix[n2 - i - 1])
52 return false;
53 }
54
55 return true;
56 }
57
58 static const struct btf_type *
resolve_func_ptr(const struct btf * btf,__u32 id,__u32 * res_id)59 resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
60 {
61 const struct btf_type *t;
62
63 t = skip_mods_and_typedefs(btf, id, NULL);
64 if (!btf_is_ptr(t))
65 return NULL;
66
67 t = skip_mods_and_typedefs(btf, t->type, res_id);
68
69 return btf_is_func_proto(t) ? t : NULL;
70 }
71
get_obj_name(char * name,const char * file)72 static void get_obj_name(char *name, const char *file)
73 {
74 char file_copy[PATH_MAX];
75
76 /* Using basename() POSIX version to be more portable. */
77 strncpy(file_copy, file, PATH_MAX - 1)[PATH_MAX - 1] = '\0';
78 strncpy(name, basename(file_copy), MAX_OBJ_NAME_LEN - 1)[MAX_OBJ_NAME_LEN - 1] = '\0';
79 if (str_has_suffix(name, ".o"))
80 name[strlen(name) - 2] = '\0';
81 sanitize_identifier(name);
82 }
83
get_header_guard(char * guard,const char * obj_name,const char * suffix)84 static void get_header_guard(char *guard, const char *obj_name, const char *suffix)
85 {
86 int i;
87
88 sprintf(guard, "__%s_%s__", obj_name, suffix);
89 for (i = 0; guard[i]; i++)
90 guard[i] = toupper(guard[i]);
91 }
92
get_map_ident(const struct bpf_map * map,char * buf,size_t buf_sz)93 static bool get_map_ident(const struct bpf_map *map, char *buf, size_t buf_sz)
94 {
95 static const char *sfxs[] = { ".data", ".rodata", ".bss", ".kconfig" };
96 const char *name = bpf_map__name(map);
97 int i, n;
98
99 if (!bpf_map__is_internal(map)) {
100 snprintf(buf, buf_sz, "%s", name);
101 return true;
102 }
103
104 for (i = 0, n = ARRAY_SIZE(sfxs); i < n; i++) {
105 const char *sfx = sfxs[i], *p;
106
107 p = strstr(name, sfx);
108 if (p) {
109 snprintf(buf, buf_sz, "%s", p + 1);
110 sanitize_identifier(buf);
111 return true;
112 }
113 }
114
115 return false;
116 }
117
get_datasec_ident(const char * sec_name,char * buf,size_t buf_sz)118 static bool get_datasec_ident(const char *sec_name, char *buf, size_t buf_sz)
119 {
120 static const char *pfxs[] = { ".data", ".rodata", ".bss", ".kconfig" };
121 int i, n;
122
123 /* recognize hard coded LLVM section name */
124 if (strcmp(sec_name, ".addr_space.1") == 0) {
125 /* this is the name to use in skeleton */
126 snprintf(buf, buf_sz, "arena");
127 return true;
128 }
129 for (i = 0, n = ARRAY_SIZE(pfxs); i < n; i++) {
130 const char *pfx = pfxs[i];
131
132 if (str_has_prefix(sec_name, pfx)) {
133 snprintf(buf, buf_sz, "%s", sec_name + 1);
134 sanitize_identifier(buf);
135 return true;
136 }
137 }
138
139 return false;
140 }
141
codegen_btf_dump_printf(void * ctx,const char * fmt,va_list args)142 static void codegen_btf_dump_printf(void *ctx, const char *fmt, va_list args)
143 {
144 vprintf(fmt, args);
145 }
146
codegen_datasec_def(struct bpf_object * obj,struct btf * btf,struct btf_dump * d,const struct btf_type * sec,const char * obj_name)147 static int codegen_datasec_def(struct bpf_object *obj,
148 struct btf *btf,
149 struct btf_dump *d,
150 const struct btf_type *sec,
151 const char *obj_name)
152 {
153 const char *sec_name = btf__name_by_offset(btf, sec->name_off);
154 const struct btf_var_secinfo *sec_var = btf_var_secinfos(sec);
155 int i, err, off = 0, pad_cnt = 0, vlen = btf_vlen(sec);
156 char var_ident[256], sec_ident[256];
157 bool strip_mods = false;
158
159 if (!get_datasec_ident(sec_name, sec_ident, sizeof(sec_ident)))
160 return 0;
161
162 if (strcmp(sec_name, ".kconfig") != 0)
163 strip_mods = true;
164
165 printf(" struct %s__%s {\n", obj_name, sec_ident);
166 for (i = 0; i < vlen; i++, sec_var++) {
167 const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
168 const char *var_name = btf__name_by_offset(btf, var->name_off);
169 DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
170 .field_name = var_ident,
171 .indent_level = 2,
172 .strip_mods = strip_mods,
173 );
174 int need_off = sec_var->offset, align_off, align;
175 __u32 var_type_id = var->type;
176
177 /* static variables are not exposed through BPF skeleton */
178 if (btf_var(var)->linkage == BTF_VAR_STATIC)
179 continue;
180
181 if (off > need_off) {
182 p_err("Something is wrong for %s's variable #%d: need offset %d, already at %d.\n",
183 sec_name, i, need_off, off);
184 return -EINVAL;
185 }
186
187 align = btf__align_of(btf, var->type);
188 if (align <= 0) {
189 p_err("Failed to determine alignment of variable '%s': %d",
190 var_name, align);
191 return -EINVAL;
192 }
193 /* Assume 32-bit architectures when generating data section
194 * struct memory layout. Given bpftool can't know which target
195 * host architecture it's emitting skeleton for, we need to be
196 * conservative and assume 32-bit one to ensure enough padding
197 * bytes are generated for pointer and long types. This will
198 * still work correctly for 64-bit architectures, because in
199 * the worst case we'll generate unnecessary padding field,
200 * which on 64-bit architectures is not strictly necessary and
201 * would be handled by natural 8-byte alignment. But it still
202 * will be a correct memory layout, based on recorded offsets
203 * in BTF.
204 */
205 if (align > 4)
206 align = 4;
207
208 align_off = (off + align - 1) / align * align;
209 if (align_off != need_off) {
210 printf("\t\tchar __pad%d[%d];\n",
211 pad_cnt, need_off - off);
212 pad_cnt++;
213 }
214
215 /* sanitize variable name, e.g., for static vars inside
216 * a function, it's name is '<function name>.<variable name>',
217 * which we'll turn into a '<function name>_<variable name>'
218 */
219 var_ident[0] = '\0';
220 strncat(var_ident, var_name, sizeof(var_ident) - 1);
221 sanitize_identifier(var_ident);
222
223 printf("\t\t");
224 err = btf_dump__emit_type_decl(d, var_type_id, &opts);
225 if (err)
226 return err;
227 printf(";\n");
228
229 off = sec_var->offset + sec_var->size;
230 }
231 printf(" } *%s;\n", sec_ident);
232 return 0;
233 }
234
find_type_for_map(struct btf * btf,const char * map_ident)235 static const struct btf_type *find_type_for_map(struct btf *btf, const char *map_ident)
236 {
237 int n = btf__type_cnt(btf), i;
238 char sec_ident[256];
239
240 for (i = 1; i < n; i++) {
241 const struct btf_type *t = btf__type_by_id(btf, i);
242 const char *name;
243
244 if (!btf_is_datasec(t))
245 continue;
246
247 name = btf__str_by_offset(btf, t->name_off);
248 if (!get_datasec_ident(name, sec_ident, sizeof(sec_ident)))
249 continue;
250
251 if (strcmp(sec_ident, map_ident) == 0)
252 return t;
253 }
254 return NULL;
255 }
256
is_mmapable_map(const struct bpf_map * map,char * buf,size_t sz)257 static bool is_mmapable_map(const struct bpf_map *map, char *buf, size_t sz)
258 {
259 size_t tmp_sz;
260
261 if (bpf_map__type(map) == BPF_MAP_TYPE_ARENA && bpf_map__initial_value(map, &tmp_sz)) {
262 snprintf(buf, sz, "arena");
263 return true;
264 }
265
266 if (!bpf_map__is_internal(map) || !(bpf_map__map_flags(map) & BPF_F_MMAPABLE))
267 return false;
268
269 if (!get_map_ident(map, buf, sz))
270 return false;
271
272 return true;
273 }
274
codegen_datasecs(struct bpf_object * obj,const char * obj_name)275 static int codegen_datasecs(struct bpf_object *obj, const char *obj_name)
276 {
277 struct btf *btf = bpf_object__btf(obj);
278 struct btf_dump *d;
279 struct bpf_map *map;
280 const struct btf_type *sec;
281 char map_ident[256];
282 int err = 0;
283
284 d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
285 if (!d)
286 return -errno;
287
288 bpf_object__for_each_map(map, obj) {
289 /* only generate definitions for memory-mapped internal maps */
290 if (!is_mmapable_map(map, map_ident, sizeof(map_ident)))
291 continue;
292
293 sec = find_type_for_map(btf, map_ident);
294
295 /* In some cases (e.g., sections like .rodata.cst16 containing
296 * compiler allocated string constants only) there will be
297 * special internal maps with no corresponding DATASEC BTF
298 * type. In such case, generate empty structs for each such
299 * map. It will still be memory-mapped and its contents
300 * accessible from user-space through BPF skeleton.
301 */
302 if (!sec) {
303 printf(" struct %s__%s {\n", obj_name, map_ident);
304 printf(" } *%s;\n", map_ident);
305 } else {
306 err = codegen_datasec_def(obj, btf, d, sec, obj_name);
307 if (err)
308 goto out;
309 }
310 }
311
312
313 out:
314 btf_dump__free(d);
315 return err;
316 }
317
btf_is_ptr_to_func_proto(const struct btf * btf,const struct btf_type * v)318 static bool btf_is_ptr_to_func_proto(const struct btf *btf,
319 const struct btf_type *v)
320 {
321 return btf_is_ptr(v) && btf_is_func_proto(btf__type_by_id(btf, v->type));
322 }
323
codegen_subskel_datasecs(struct bpf_object * obj,const char * obj_name)324 static int codegen_subskel_datasecs(struct bpf_object *obj, const char *obj_name)
325 {
326 struct btf *btf = bpf_object__btf(obj);
327 struct btf_dump *d;
328 struct bpf_map *map;
329 const struct btf_type *sec, *var;
330 const struct btf_var_secinfo *sec_var;
331 int i, err = 0, vlen;
332 char map_ident[256], sec_ident[256];
333 bool strip_mods = false, needs_typeof = false;
334 const char *sec_name, *var_name;
335 __u32 var_type_id;
336
337 d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
338 if (!d)
339 return -errno;
340
341 bpf_object__for_each_map(map, obj) {
342 /* only generate definitions for memory-mapped internal maps */
343 if (!is_mmapable_map(map, map_ident, sizeof(map_ident)))
344 continue;
345
346 sec = find_type_for_map(btf, map_ident);
347 if (!sec)
348 continue;
349
350 sec_name = btf__name_by_offset(btf, sec->name_off);
351 if (!get_datasec_ident(sec_name, sec_ident, sizeof(sec_ident)))
352 continue;
353
354 strip_mods = strcmp(sec_name, ".kconfig") != 0;
355 printf(" struct %s__%s {\n", obj_name, sec_ident);
356
357 sec_var = btf_var_secinfos(sec);
358 vlen = btf_vlen(sec);
359 for (i = 0; i < vlen; i++, sec_var++) {
360 DECLARE_LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts,
361 .indent_level = 2,
362 .strip_mods = strip_mods,
363 /* we'll print the name separately */
364 .field_name = "",
365 );
366
367 var = btf__type_by_id(btf, sec_var->type);
368 var_name = btf__name_by_offset(btf, var->name_off);
369 var_type_id = var->type;
370
371 /* static variables are not exposed through BPF skeleton */
372 if (btf_var(var)->linkage == BTF_VAR_STATIC)
373 continue;
374
375 /* The datasec member has KIND_VAR but we want the
376 * underlying type of the variable (e.g. KIND_INT).
377 */
378 var = skip_mods_and_typedefs(btf, var->type, NULL);
379
380 printf("\t\t");
381 /* Func and array members require special handling.
382 * Instead of producing `typename *var`, they produce
383 * `typeof(typename) *var`. This allows us to keep a
384 * similar syntax where the identifier is just prefixed
385 * by *, allowing us to ignore C declaration minutiae.
386 */
387 needs_typeof = btf_is_array(var) || btf_is_ptr_to_func_proto(btf, var);
388 if (needs_typeof)
389 printf("typeof(");
390
391 err = btf_dump__emit_type_decl(d, var_type_id, &opts);
392 if (err)
393 goto out;
394
395 if (needs_typeof)
396 printf(")");
397
398 printf(" *%s;\n", var_name);
399 }
400 printf(" } %s;\n", sec_ident);
401 }
402
403 out:
404 btf_dump__free(d);
405 return err;
406 }
407
codegen(const char * template,...)408 static void codegen(const char *template, ...)
409 {
410 const char *src, *end;
411 int skip_tabs = 0, n;
412 char *s, *dst;
413 va_list args;
414 char c;
415
416 n = strlen(template);
417 s = malloc(n + 1);
418 if (!s)
419 exit(-1);
420 src = template;
421 dst = s;
422
423 /* find out "baseline" indentation to skip */
424 while ((c = *src++)) {
425 if (c == '\t') {
426 skip_tabs++;
427 } else if (c == '\n') {
428 break;
429 } else {
430 p_err("unrecognized character at pos %td in template '%s': '%c'",
431 src - template - 1, template, c);
432 free(s);
433 exit(-1);
434 }
435 }
436
437 while (*src) {
438 /* skip baseline indentation tabs */
439 for (n = skip_tabs; n > 0; n--, src++) {
440 if (*src != '\t') {
441 p_err("not enough tabs at pos %td in template '%s'",
442 src - template - 1, template);
443 free(s);
444 exit(-1);
445 }
446 }
447 /* trim trailing whitespace */
448 end = strchrnul(src, '\n');
449 for (n = end - src; n > 0 && isspace(src[n - 1]); n--)
450 ;
451 memcpy(dst, src, n);
452 dst += n;
453 if (*end)
454 *dst++ = '\n';
455 src = *end ? end + 1 : end;
456 }
457 *dst++ = '\0';
458
459 /* print out using adjusted template */
460 va_start(args, template);
461 n = vprintf(s, args);
462 va_end(args);
463
464 free(s);
465 }
466
print_hex(const char * data,int data_sz)467 static void print_hex(const char *data, int data_sz)
468 {
469 int i, len;
470
471 for (i = 0, len = 0; i < data_sz; i++) {
472 int w = data[i] ? 4 : 2;
473
474 len += w;
475 if (len > 78) {
476 printf("\\\n");
477 len = w;
478 }
479 if (!data[i])
480 printf("\\0");
481 else
482 printf("\\x%02x", (unsigned char)data[i]);
483 }
484 }
485
bpf_map_mmap_sz(const struct bpf_map * map)486 static size_t bpf_map_mmap_sz(const struct bpf_map *map)
487 {
488 long page_sz = sysconf(_SC_PAGE_SIZE);
489 size_t map_sz;
490
491 map_sz = (size_t)roundup(bpf_map__value_size(map), 8) * bpf_map__max_entries(map);
492 map_sz = roundup(map_sz, page_sz);
493 return map_sz;
494 }
495
496 /* Emit type size asserts for all top-level fields in memory-mapped internal maps. */
codegen_asserts(struct bpf_object * obj,const char * obj_name)497 static void codegen_asserts(struct bpf_object *obj, const char *obj_name)
498 {
499 struct btf *btf = bpf_object__btf(obj);
500 struct bpf_map *map;
501 struct btf_var_secinfo *sec_var;
502 int i, vlen;
503 const struct btf_type *sec;
504 char map_ident[256], var_ident[256];
505
506 if (!btf)
507 return;
508
509 codegen("\
510 \n\
511 __attribute__((unused)) static void \n\
512 %1$s__assert(struct %1$s *s __attribute__((unused))) \n\
513 { \n\
514 #ifdef __cplusplus \n\
515 #define _Static_assert static_assert \n\
516 #endif \n\
517 ", obj_name);
518
519 bpf_object__for_each_map(map, obj) {
520 if (!is_mmapable_map(map, map_ident, sizeof(map_ident)))
521 continue;
522
523 sec = find_type_for_map(btf, map_ident);
524 if (!sec) {
525 /* best effort, couldn't find the type for this map */
526 continue;
527 }
528
529 sec_var = btf_var_secinfos(sec);
530 vlen = btf_vlen(sec);
531
532 for (i = 0; i < vlen; i++, sec_var++) {
533 const struct btf_type *var = btf__type_by_id(btf, sec_var->type);
534 const char *var_name = btf__name_by_offset(btf, var->name_off);
535 long var_size;
536
537 /* static variables are not exposed through BPF skeleton */
538 if (btf_var(var)->linkage == BTF_VAR_STATIC)
539 continue;
540
541 var_size = btf__resolve_size(btf, var->type);
542 if (var_size < 0)
543 continue;
544
545 var_ident[0] = '\0';
546 strncat(var_ident, var_name, sizeof(var_ident) - 1);
547 sanitize_identifier(var_ident);
548
549 printf("\t_Static_assert(sizeof(s->%s->%s) == %ld, \"unexpected size of '%s'\");\n",
550 map_ident, var_ident, var_size, var_ident);
551 }
552 }
553 codegen("\
554 \n\
555 #ifdef __cplusplus \n\
556 #undef _Static_assert \n\
557 #endif \n\
558 } \n\
559 ");
560 }
561
codegen_attach_detach(struct bpf_object * obj,const char * obj_name)562 static void codegen_attach_detach(struct bpf_object *obj, const char *obj_name)
563 {
564 struct bpf_program *prog;
565
566 bpf_object__for_each_program(prog, obj) {
567 const char *tp_name;
568
569 codegen("\
570 \n\
571 \n\
572 static inline int \n\
573 %1$s__%2$s__attach(struct %1$s *skel) \n\
574 { \n\
575 int prog_fd = skel->progs.%2$s.prog_fd; \n\
576 ", obj_name, bpf_program__name(prog));
577
578 switch (bpf_program__type(prog)) {
579 case BPF_PROG_TYPE_RAW_TRACEPOINT:
580 tp_name = strchr(bpf_program__section_name(prog), '/') + 1;
581 printf("\tint fd = skel_raw_tracepoint_open(\"%s\", prog_fd);\n", tp_name);
582 break;
583 case BPF_PROG_TYPE_TRACING:
584 case BPF_PROG_TYPE_LSM:
585 if (bpf_program__expected_attach_type(prog) == BPF_TRACE_ITER)
586 printf("\tint fd = skel_link_create(prog_fd, 0, BPF_TRACE_ITER);\n");
587 else
588 printf("\tint fd = skel_raw_tracepoint_open(NULL, prog_fd);\n");
589 break;
590 default:
591 printf("\tint fd = ((void)prog_fd, 0); /* auto-attach not supported */\n");
592 break;
593 }
594 codegen("\
595 \n\
596 \n\
597 if (fd > 0) \n\
598 skel->links.%1$s_fd = fd; \n\
599 return fd; \n\
600 } \n\
601 ", bpf_program__name(prog));
602 }
603
604 codegen("\
605 \n\
606 \n\
607 static inline int \n\
608 %1$s__attach(struct %1$s *skel) \n\
609 { \n\
610 int ret = 0; \n\
611 \n\
612 ", obj_name);
613
614 bpf_object__for_each_program(prog, obj) {
615 codegen("\
616 \n\
617 ret = ret < 0 ? ret : %1$s__%2$s__attach(skel); \n\
618 ", obj_name, bpf_program__name(prog));
619 }
620
621 codegen("\
622 \n\
623 return ret < 0 ? ret : 0; \n\
624 } \n\
625 \n\
626 static inline void \n\
627 %1$s__detach(struct %1$s *skel) \n\
628 { \n\
629 ", obj_name);
630
631 bpf_object__for_each_program(prog, obj) {
632 codegen("\
633 \n\
634 skel_closenz(skel->links.%1$s_fd); \n\
635 ", bpf_program__name(prog));
636 }
637
638 codegen("\
639 \n\
640 } \n\
641 ");
642 }
643
codegen_destroy(struct bpf_object * obj,const char * obj_name)644 static void codegen_destroy(struct bpf_object *obj, const char *obj_name)
645 {
646 struct bpf_program *prog;
647 struct bpf_map *map;
648 char ident[256];
649
650 codegen("\
651 \n\
652 static void \n\
653 %1$s__destroy(struct %1$s *skel) \n\
654 { \n\
655 if (!skel) \n\
656 return; \n\
657 %1$s__detach(skel); \n\
658 ",
659 obj_name);
660
661 bpf_object__for_each_program(prog, obj) {
662 codegen("\
663 \n\
664 skel_closenz(skel->progs.%1$s.prog_fd); \n\
665 ", bpf_program__name(prog));
666 }
667
668 bpf_object__for_each_map(map, obj) {
669 if (!get_map_ident(map, ident, sizeof(ident)))
670 continue;
671 if (bpf_map__is_internal(map) &&
672 (bpf_map__map_flags(map) & BPF_F_MMAPABLE))
673 printf("\tskel_free_map_data(skel->%1$s, skel->maps.%1$s.initial_value, %2$zd);\n",
674 ident, bpf_map_mmap_sz(map));
675 codegen("\
676 \n\
677 skel_closenz(skel->maps.%1$s.map_fd); \n\
678 ", ident);
679 }
680 codegen("\
681 \n\
682 skel_free(skel); \n\
683 } \n\
684 ",
685 obj_name);
686 }
687
gen_trace(struct bpf_object * obj,const char * obj_name,const char * header_guard)688 static int gen_trace(struct bpf_object *obj, const char *obj_name, const char *header_guard)
689 {
690 DECLARE_LIBBPF_OPTS(gen_loader_opts, opts);
691 struct bpf_map *map;
692 char ident[256];
693 int err = 0;
694
695 err = bpf_object__gen_loader(obj, &opts);
696 if (err)
697 return err;
698
699 err = bpf_object__load(obj);
700 if (err) {
701 p_err("failed to load object file");
702 goto out;
703 }
704 /* If there was no error during load then gen_loader_opts
705 * are populated with the loader program.
706 */
707
708 /* finish generating 'struct skel' */
709 codegen("\
710 \n\
711 }; \n\
712 ", obj_name);
713
714
715 codegen_attach_detach(obj, obj_name);
716
717 codegen_destroy(obj, obj_name);
718
719 codegen("\
720 \n\
721 static inline struct %1$s * \n\
722 %1$s__open(void) \n\
723 { \n\
724 struct %1$s *skel; \n\
725 \n\
726 skel = skel_alloc(sizeof(*skel)); \n\
727 if (!skel) \n\
728 goto cleanup; \n\
729 skel->ctx.sz = (void *)&skel->links - (void *)skel; \n\
730 ",
731 obj_name, opts.data_sz);
732 bpf_object__for_each_map(map, obj) {
733 const void *mmap_data = NULL;
734 size_t mmap_size = 0;
735
736 if (!is_mmapable_map(map, ident, sizeof(ident)))
737 continue;
738
739 codegen("\
740 \n\
741 { \n\
742 static const char data[] __attribute__((__aligned__(8))) = \"\\\n\
743 ");
744 mmap_data = bpf_map__initial_value(map, &mmap_size);
745 print_hex(mmap_data, mmap_size);
746 codegen("\
747 \n\
748 \"; \n\
749 \n\
750 skel->%1$s = skel_prep_map_data((void *)data, %2$zd,\n\
751 sizeof(data) - 1);\n\
752 if (!skel->%1$s) \n\
753 goto cleanup; \n\
754 skel->maps.%1$s.initial_value = (__u64) (long) skel->%1$s;\n\
755 } \n\
756 ", ident, bpf_map_mmap_sz(map));
757 }
758 codegen("\
759 \n\
760 return skel; \n\
761 cleanup: \n\
762 %1$s__destroy(skel); \n\
763 return NULL; \n\
764 } \n\
765 \n\
766 static inline int \n\
767 %1$s__load(struct %1$s *skel) \n\
768 { \n\
769 struct bpf_load_and_run_opts opts = {}; \n\
770 int err; \n\
771 static const char opts_data[] __attribute__((__aligned__(8))) = \"\\\n\
772 ",
773 obj_name);
774 print_hex(opts.data, opts.data_sz);
775 codegen("\
776 \n\
777 \"; \n\
778 static const char opts_insn[] __attribute__((__aligned__(8))) = \"\\\n\
779 ");
780 print_hex(opts.insns, opts.insns_sz);
781 codegen("\
782 \n\
783 \"; \n\
784 \n\
785 opts.ctx = (struct bpf_loader_ctx *)skel; \n\
786 opts.data_sz = sizeof(opts_data) - 1; \n\
787 opts.data = (void *)opts_data; \n\
788 opts.insns_sz = sizeof(opts_insn) - 1; \n\
789 opts.insns = (void *)opts_insn; \n\
790 \n\
791 err = bpf_load_and_run(&opts); \n\
792 if (err < 0) \n\
793 return err; \n\
794 ");
795 bpf_object__for_each_map(map, obj) {
796 const char *mmap_flags;
797
798 if (!is_mmapable_map(map, ident, sizeof(ident)))
799 continue;
800
801 if (bpf_map__map_flags(map) & BPF_F_RDONLY_PROG)
802 mmap_flags = "PROT_READ";
803 else
804 mmap_flags = "PROT_READ | PROT_WRITE";
805
806 codegen("\
807 \n\
808 skel->%1$s = skel_finalize_map_data(&skel->maps.%1$s.initial_value, \n\
809 %2$zd, %3$s, skel->maps.%1$s.map_fd);\n\
810 if (!skel->%1$s) \n\
811 return -ENOMEM; \n\
812 ",
813 ident, bpf_map_mmap_sz(map), mmap_flags);
814 }
815 codegen("\
816 \n\
817 return 0; \n\
818 } \n\
819 \n\
820 static inline struct %1$s * \n\
821 %1$s__open_and_load(void) \n\
822 { \n\
823 struct %1$s *skel; \n\
824 \n\
825 skel = %1$s__open(); \n\
826 if (!skel) \n\
827 return NULL; \n\
828 if (%1$s__load(skel)) { \n\
829 %1$s__destroy(skel); \n\
830 return NULL; \n\
831 } \n\
832 return skel; \n\
833 } \n\
834 \n\
835 ", obj_name);
836
837 codegen_asserts(obj, obj_name);
838
839 codegen("\
840 \n\
841 \n\
842 #endif /* %s */ \n\
843 ",
844 header_guard);
845 err = 0;
846 out:
847 return err;
848 }
849
850 static void
codegen_maps_skeleton(struct bpf_object * obj,size_t map_cnt,bool mmaped)851 codegen_maps_skeleton(struct bpf_object *obj, size_t map_cnt, bool mmaped)
852 {
853 struct bpf_map *map;
854 char ident[256];
855 size_t i;
856
857 if (!map_cnt)
858 return;
859
860 codegen("\
861 \n\
862 \n\
863 /* maps */ \n\
864 s->map_cnt = %zu; \n\
865 s->map_skel_sz = sizeof(*s->maps); \n\
866 s->maps = (struct bpf_map_skeleton *)calloc(s->map_cnt, s->map_skel_sz);\n\
867 if (!s->maps) { \n\
868 err = -ENOMEM; \n\
869 goto err; \n\
870 } \n\
871 ",
872 map_cnt
873 );
874 i = 0;
875 bpf_object__for_each_map(map, obj) {
876 if (!get_map_ident(map, ident, sizeof(ident)))
877 continue;
878
879 codegen("\
880 \n\
881 \n\
882 s->maps[%zu].name = \"%s\"; \n\
883 s->maps[%zu].map = &obj->maps.%s; \n\
884 ",
885 i, bpf_map__name(map), i, ident);
886 /* memory-mapped internal maps */
887 if (mmaped && is_mmapable_map(map, ident, sizeof(ident))) {
888 printf("\ts->maps[%zu].mmaped = (void **)&obj->%s;\n",
889 i, ident);
890 }
891 i++;
892 }
893 }
894
895 static void
codegen_progs_skeleton(struct bpf_object * obj,size_t prog_cnt,bool populate_links)896 codegen_progs_skeleton(struct bpf_object *obj, size_t prog_cnt, bool populate_links)
897 {
898 struct bpf_program *prog;
899 int i;
900
901 if (!prog_cnt)
902 return;
903
904 codegen("\
905 \n\
906 \n\
907 /* programs */ \n\
908 s->prog_cnt = %zu; \n\
909 s->prog_skel_sz = sizeof(*s->progs); \n\
910 s->progs = (struct bpf_prog_skeleton *)calloc(s->prog_cnt, s->prog_skel_sz);\n\
911 if (!s->progs) { \n\
912 err = -ENOMEM; \n\
913 goto err; \n\
914 } \n\
915 ",
916 prog_cnt
917 );
918 i = 0;
919 bpf_object__for_each_program(prog, obj) {
920 codegen("\
921 \n\
922 \n\
923 s->progs[%1$zu].name = \"%2$s\"; \n\
924 s->progs[%1$zu].prog = &obj->progs.%2$s;\n\
925 ",
926 i, bpf_program__name(prog));
927
928 if (populate_links) {
929 codegen("\
930 \n\
931 s->progs[%1$zu].link = &obj->links.%2$s;\n\
932 ",
933 i, bpf_program__name(prog));
934 }
935 i++;
936 }
937 }
938
walk_st_ops_shadow_vars(struct btf * btf,const char * ident,const struct btf_type * map_type,__u32 map_type_id)939 static int walk_st_ops_shadow_vars(struct btf *btf, const char *ident,
940 const struct btf_type *map_type, __u32 map_type_id)
941 {
942 LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts, .indent_level = 3);
943 const struct btf_type *member_type;
944 __u32 offset, next_offset = 0;
945 const struct btf_member *m;
946 struct btf_dump *d = NULL;
947 const char *member_name;
948 __u32 member_type_id;
949 int i, err = 0, n;
950 int size;
951
952 d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
953 if (!d)
954 return -errno;
955
956 n = btf_vlen(map_type);
957 for (i = 0, m = btf_members(map_type); i < n; i++, m++) {
958 member_type = skip_mods_and_typedefs(btf, m->type, &member_type_id);
959 member_name = btf__name_by_offset(btf, m->name_off);
960
961 offset = m->offset / 8;
962 if (next_offset < offset)
963 printf("\t\t\tchar __padding_%d[%d];\n", i, offset - next_offset);
964
965 switch (btf_kind(member_type)) {
966 case BTF_KIND_INT:
967 case BTF_KIND_FLOAT:
968 case BTF_KIND_ENUM:
969 case BTF_KIND_ENUM64:
970 /* scalar type */
971 printf("\t\t\t");
972 opts.field_name = member_name;
973 err = btf_dump__emit_type_decl(d, member_type_id, &opts);
974 if (err) {
975 p_err("Failed to emit type declaration for %s: %d", member_name, err);
976 goto out;
977 }
978 printf(";\n");
979
980 size = btf__resolve_size(btf, member_type_id);
981 if (size < 0) {
982 p_err("Failed to resolve size of %s: %d\n", member_name, size);
983 err = size;
984 goto out;
985 }
986
987 next_offset = offset + size;
988 break;
989
990 case BTF_KIND_PTR:
991 if (resolve_func_ptr(btf, m->type, NULL)) {
992 /* Function pointer */
993 printf("\t\t\tstruct bpf_program *%s;\n", member_name);
994
995 next_offset = offset + sizeof(void *);
996 break;
997 }
998 /* All pointer types are unsupported except for
999 * function pointers.
1000 */
1001 fallthrough;
1002
1003 default:
1004 /* Unsupported types
1005 *
1006 * Types other than scalar types and function
1007 * pointers are currently not supported in order to
1008 * prevent conflicts in the generated code caused
1009 * by multiple definitions. For instance, if the
1010 * struct type FOO is used in a struct_ops map,
1011 * bpftool has to generate definitions for FOO,
1012 * which may result in conflicts if FOO is defined
1013 * in different skeleton files.
1014 */
1015 size = btf__resolve_size(btf, member_type_id);
1016 if (size < 0) {
1017 p_err("Failed to resolve size of %s: %d\n", member_name, size);
1018 err = size;
1019 goto out;
1020 }
1021 printf("\t\t\tchar __unsupported_%d[%d];\n", i, size);
1022
1023 next_offset = offset + size;
1024 break;
1025 }
1026 }
1027
1028 /* Cannot fail since it must be a struct type */
1029 size = btf__resolve_size(btf, map_type_id);
1030 if (next_offset < (__u32)size)
1031 printf("\t\t\tchar __padding_end[%d];\n", size - next_offset);
1032
1033 out:
1034 btf_dump__free(d);
1035
1036 return err;
1037 }
1038
1039 /* Generate the pointer of the shadow type for a struct_ops map.
1040 *
1041 * This function adds a pointer of the shadow type for a struct_ops map.
1042 * The members of a struct_ops map can be exported through a pointer to a
1043 * shadow type. The user can access these members through the pointer.
1044 *
1045 * A shadow type includes not all members, only members of some types.
1046 * They are scalar types and function pointers. The function pointers are
1047 * translated to the pointer of the struct bpf_program. The scalar types
1048 * are translated to the original type without any modifiers.
1049 *
1050 * Unsupported types will be translated to a char array to occupy the same
1051 * space as the original field, being renamed as __unsupported_*. The user
1052 * should treat these fields as opaque data.
1053 */
gen_st_ops_shadow_type(const char * obj_name,struct btf * btf,const char * ident,const struct bpf_map * map)1054 static int gen_st_ops_shadow_type(const char *obj_name, struct btf *btf, const char *ident,
1055 const struct bpf_map *map)
1056 {
1057 const struct btf_type *map_type;
1058 const char *type_name;
1059 __u32 map_type_id;
1060 int err;
1061
1062 map_type_id = bpf_map__btf_value_type_id(map);
1063 if (map_type_id == 0)
1064 return -EINVAL;
1065 map_type = btf__type_by_id(btf, map_type_id);
1066 if (!map_type)
1067 return -EINVAL;
1068
1069 type_name = btf__name_by_offset(btf, map_type->name_off);
1070
1071 printf("\t\tstruct %s__%s__%s {\n", obj_name, ident, type_name);
1072
1073 err = walk_st_ops_shadow_vars(btf, ident, map_type, map_type_id);
1074 if (err)
1075 return err;
1076
1077 printf("\t\t} *%s;\n", ident);
1078
1079 return 0;
1080 }
1081
gen_st_ops_shadow(const char * obj_name,struct btf * btf,struct bpf_object * obj)1082 static int gen_st_ops_shadow(const char *obj_name, struct btf *btf, struct bpf_object *obj)
1083 {
1084 int err, st_ops_cnt = 0;
1085 struct bpf_map *map;
1086 char ident[256];
1087
1088 if (!btf)
1089 return 0;
1090
1091 /* Generate the pointers to shadow types of
1092 * struct_ops maps.
1093 */
1094 bpf_object__for_each_map(map, obj) {
1095 if (bpf_map__type(map) != BPF_MAP_TYPE_STRUCT_OPS)
1096 continue;
1097 if (!get_map_ident(map, ident, sizeof(ident)))
1098 continue;
1099
1100 if (st_ops_cnt == 0) /* first struct_ops map */
1101 printf("\tstruct {\n");
1102 st_ops_cnt++;
1103
1104 err = gen_st_ops_shadow_type(obj_name, btf, ident, map);
1105 if (err)
1106 return err;
1107 }
1108
1109 if (st_ops_cnt)
1110 printf("\t} struct_ops;\n");
1111
1112 return 0;
1113 }
1114
1115 /* Generate the code to initialize the pointers of shadow types. */
gen_st_ops_shadow_init(struct btf * btf,struct bpf_object * obj)1116 static void gen_st_ops_shadow_init(struct btf *btf, struct bpf_object *obj)
1117 {
1118 struct bpf_map *map;
1119 char ident[256];
1120
1121 if (!btf)
1122 return;
1123
1124 /* Initialize the pointers to_ops shadow types of
1125 * struct_ops maps.
1126 */
1127 bpf_object__for_each_map(map, obj) {
1128 if (bpf_map__type(map) != BPF_MAP_TYPE_STRUCT_OPS)
1129 continue;
1130 if (!get_map_ident(map, ident, sizeof(ident)))
1131 continue;
1132 codegen("\
1133 \n\
1134 obj->struct_ops.%1$s = (typeof(obj->struct_ops.%1$s))\n\
1135 bpf_map__initial_value(obj->maps.%1$s, NULL);\n\
1136 \n\
1137 ", ident);
1138 }
1139 }
1140
do_skeleton(int argc,char ** argv)1141 static int do_skeleton(int argc, char **argv)
1142 {
1143 char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")];
1144 size_t map_cnt = 0, prog_cnt = 0, file_sz, mmap_sz;
1145 DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
1146 char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
1147 struct bpf_object *obj = NULL;
1148 const char *file;
1149 char ident[256];
1150 struct bpf_program *prog;
1151 int fd, err = -1;
1152 struct bpf_map *map;
1153 struct btf *btf;
1154 struct stat st;
1155
1156 if (!REQ_ARGS(1)) {
1157 usage();
1158 return -1;
1159 }
1160 file = GET_ARG();
1161
1162 while (argc) {
1163 if (!REQ_ARGS(2))
1164 return -1;
1165
1166 if (is_prefix(*argv, "name")) {
1167 NEXT_ARG();
1168
1169 if (obj_name[0] != '\0') {
1170 p_err("object name already specified");
1171 return -1;
1172 }
1173
1174 strncpy(obj_name, *argv, MAX_OBJ_NAME_LEN - 1);
1175 obj_name[MAX_OBJ_NAME_LEN - 1] = '\0';
1176 } else {
1177 p_err("unknown arg %s", *argv);
1178 return -1;
1179 }
1180
1181 NEXT_ARG();
1182 }
1183
1184 if (argc) {
1185 p_err("extra unknown arguments");
1186 return -1;
1187 }
1188
1189 if (stat(file, &st)) {
1190 p_err("failed to stat() %s: %s", file, strerror(errno));
1191 return -1;
1192 }
1193 file_sz = st.st_size;
1194 mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
1195 fd = open(file, O_RDONLY);
1196 if (fd < 0) {
1197 p_err("failed to open() %s: %s", file, strerror(errno));
1198 return -1;
1199 }
1200 obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
1201 if (obj_data == MAP_FAILED) {
1202 obj_data = NULL;
1203 p_err("failed to mmap() %s: %s", file, strerror(errno));
1204 goto out;
1205 }
1206 if (obj_name[0] == '\0')
1207 get_obj_name(obj_name, file);
1208 opts.object_name = obj_name;
1209 if (verifier_logs)
1210 /* log_level1 + log_level2 + stats, but not stable UAPI */
1211 opts.kernel_log_level = 1 + 2 + 4;
1212 obj = bpf_object__open_mem(obj_data, file_sz, &opts);
1213 if (!obj) {
1214 char err_buf[256];
1215
1216 err = -errno;
1217 libbpf_strerror(err, err_buf, sizeof(err_buf));
1218 p_err("failed to open BPF object file: %s", err_buf);
1219 goto out;
1220 }
1221
1222 bpf_object__for_each_map(map, obj) {
1223 if (!get_map_ident(map, ident, sizeof(ident))) {
1224 p_err("ignoring unrecognized internal map '%s'...",
1225 bpf_map__name(map));
1226 continue;
1227 }
1228 map_cnt++;
1229 }
1230 bpf_object__for_each_program(prog, obj) {
1231 prog_cnt++;
1232 }
1233
1234 get_header_guard(header_guard, obj_name, "SKEL_H");
1235 if (use_loader) {
1236 codegen("\
1237 \n\
1238 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
1239 /* THIS FILE IS AUTOGENERATED BY BPFTOOL! */ \n\
1240 #ifndef %2$s \n\
1241 #define %2$s \n\
1242 \n\
1243 #include <bpf/skel_internal.h> \n\
1244 \n\
1245 struct %1$s { \n\
1246 struct bpf_loader_ctx ctx; \n\
1247 ",
1248 obj_name, header_guard
1249 );
1250 } else {
1251 codegen("\
1252 \n\
1253 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
1254 \n\
1255 /* THIS FILE IS AUTOGENERATED BY BPFTOOL! */ \n\
1256 #ifndef %2$s \n\
1257 #define %2$s \n\
1258 \n\
1259 #include <errno.h> \n\
1260 #include <stdlib.h> \n\
1261 #include <bpf/libbpf.h> \n\
1262 \n\
1263 struct %1$s { \n\
1264 struct bpf_object_skeleton *skeleton; \n\
1265 struct bpf_object *obj; \n\
1266 ",
1267 obj_name, header_guard
1268 );
1269 }
1270
1271 if (map_cnt) {
1272 printf("\tstruct {\n");
1273 bpf_object__for_each_map(map, obj) {
1274 if (!get_map_ident(map, ident, sizeof(ident)))
1275 continue;
1276 if (use_loader)
1277 printf("\t\tstruct bpf_map_desc %s;\n", ident);
1278 else
1279 printf("\t\tstruct bpf_map *%s;\n", ident);
1280 }
1281 printf("\t} maps;\n");
1282 }
1283
1284 btf = bpf_object__btf(obj);
1285 err = gen_st_ops_shadow(obj_name, btf, obj);
1286 if (err)
1287 goto out;
1288
1289 if (prog_cnt) {
1290 printf("\tstruct {\n");
1291 bpf_object__for_each_program(prog, obj) {
1292 if (use_loader)
1293 printf("\t\tstruct bpf_prog_desc %s;\n",
1294 bpf_program__name(prog));
1295 else
1296 printf("\t\tstruct bpf_program *%s;\n",
1297 bpf_program__name(prog));
1298 }
1299 printf("\t} progs;\n");
1300 printf("\tstruct {\n");
1301 bpf_object__for_each_program(prog, obj) {
1302 if (use_loader)
1303 printf("\t\tint %s_fd;\n",
1304 bpf_program__name(prog));
1305 else
1306 printf("\t\tstruct bpf_link *%s;\n",
1307 bpf_program__name(prog));
1308 }
1309 printf("\t} links;\n");
1310 }
1311
1312 if (btf) {
1313 err = codegen_datasecs(obj, obj_name);
1314 if (err)
1315 goto out;
1316 }
1317 if (use_loader) {
1318 err = gen_trace(obj, obj_name, header_guard);
1319 goto out;
1320 }
1321
1322 codegen("\
1323 \n\
1324 \n\
1325 #ifdef __cplusplus \n\
1326 static inline struct %1$s *open(const struct bpf_object_open_opts *opts = nullptr);\n\
1327 static inline struct %1$s *open_and_load(); \n\
1328 static inline int load(struct %1$s *skel); \n\
1329 static inline int attach(struct %1$s *skel); \n\
1330 static inline void detach(struct %1$s *skel); \n\
1331 static inline void destroy(struct %1$s *skel); \n\
1332 static inline const void *elf_bytes(size_t *sz); \n\
1333 #endif /* __cplusplus */ \n\
1334 }; \n\
1335 \n\
1336 static void \n\
1337 %1$s__destroy(struct %1$s *obj) \n\
1338 { \n\
1339 if (!obj) \n\
1340 return; \n\
1341 if (obj->skeleton) \n\
1342 bpf_object__destroy_skeleton(obj->skeleton);\n\
1343 free(obj); \n\
1344 } \n\
1345 \n\
1346 static inline int \n\
1347 %1$s__create_skeleton(struct %1$s *obj); \n\
1348 \n\
1349 static inline struct %1$s * \n\
1350 %1$s__open_opts(const struct bpf_object_open_opts *opts) \n\
1351 { \n\
1352 struct %1$s *obj; \n\
1353 int err; \n\
1354 \n\
1355 obj = (struct %1$s *)calloc(1, sizeof(*obj)); \n\
1356 if (!obj) { \n\
1357 errno = ENOMEM; \n\
1358 return NULL; \n\
1359 } \n\
1360 \n\
1361 err = %1$s__create_skeleton(obj); \n\
1362 if (err) \n\
1363 goto err_out; \n\
1364 \n\
1365 err = bpf_object__open_skeleton(obj->skeleton, opts);\n\
1366 if (err) \n\
1367 goto err_out; \n\
1368 \n\
1369 ", obj_name);
1370
1371 gen_st_ops_shadow_init(btf, obj);
1372
1373 codegen("\
1374 \n\
1375 return obj; \n\
1376 err_out: \n\
1377 %1$s__destroy(obj); \n\
1378 errno = -err; \n\
1379 return NULL; \n\
1380 } \n\
1381 \n\
1382 static inline struct %1$s * \n\
1383 %1$s__open(void) \n\
1384 { \n\
1385 return %1$s__open_opts(NULL); \n\
1386 } \n\
1387 \n\
1388 static inline int \n\
1389 %1$s__load(struct %1$s *obj) \n\
1390 { \n\
1391 return bpf_object__load_skeleton(obj->skeleton); \n\
1392 } \n\
1393 \n\
1394 static inline struct %1$s * \n\
1395 %1$s__open_and_load(void) \n\
1396 { \n\
1397 struct %1$s *obj; \n\
1398 int err; \n\
1399 \n\
1400 obj = %1$s__open(); \n\
1401 if (!obj) \n\
1402 return NULL; \n\
1403 err = %1$s__load(obj); \n\
1404 if (err) { \n\
1405 %1$s__destroy(obj); \n\
1406 errno = -err; \n\
1407 return NULL; \n\
1408 } \n\
1409 return obj; \n\
1410 } \n\
1411 \n\
1412 static inline int \n\
1413 %1$s__attach(struct %1$s *obj) \n\
1414 { \n\
1415 return bpf_object__attach_skeleton(obj->skeleton); \n\
1416 } \n\
1417 \n\
1418 static inline void \n\
1419 %1$s__detach(struct %1$s *obj) \n\
1420 { \n\
1421 bpf_object__detach_skeleton(obj->skeleton); \n\
1422 } \n\
1423 ",
1424 obj_name
1425 );
1426
1427 codegen("\
1428 \n\
1429 \n\
1430 static inline const void *%1$s__elf_bytes(size_t *sz); \n\
1431 \n\
1432 static inline int \n\
1433 %1$s__create_skeleton(struct %1$s *obj) \n\
1434 { \n\
1435 struct bpf_object_skeleton *s; \n\
1436 int err; \n\
1437 \n\
1438 s = (struct bpf_object_skeleton *)calloc(1, sizeof(*s));\n\
1439 if (!s) { \n\
1440 err = -ENOMEM; \n\
1441 goto err; \n\
1442 } \n\
1443 \n\
1444 s->sz = sizeof(*s); \n\
1445 s->name = \"%1$s\"; \n\
1446 s->obj = &obj->obj; \n\
1447 ",
1448 obj_name
1449 );
1450
1451 codegen_maps_skeleton(obj, map_cnt, true /*mmaped*/);
1452 codegen_progs_skeleton(obj, prog_cnt, true /*populate_links*/);
1453
1454 codegen("\
1455 \n\
1456 \n\
1457 s->data = %1$s__elf_bytes(&s->data_sz); \n\
1458 \n\
1459 obj->skeleton = s; \n\
1460 return 0; \n\
1461 err: \n\
1462 bpf_object__destroy_skeleton(s); \n\
1463 return err; \n\
1464 } \n\
1465 \n\
1466 static inline const void *%1$s__elf_bytes(size_t *sz) \n\
1467 { \n\
1468 static const char data[] __attribute__((__aligned__(8))) = \"\\\n\
1469 ",
1470 obj_name
1471 );
1472
1473 /* embed contents of BPF object file */
1474 print_hex(obj_data, file_sz);
1475
1476 codegen("\
1477 \n\
1478 \"; \n\
1479 \n\
1480 *sz = sizeof(data) - 1; \n\
1481 return (const void *)data; \n\
1482 } \n\
1483 \n\
1484 #ifdef __cplusplus \n\
1485 struct %1$s *%1$s::open(const struct bpf_object_open_opts *opts) { return %1$s__open_opts(opts); }\n\
1486 struct %1$s *%1$s::open_and_load() { return %1$s__open_and_load(); } \n\
1487 int %1$s::load(struct %1$s *skel) { return %1$s__load(skel); } \n\
1488 int %1$s::attach(struct %1$s *skel) { return %1$s__attach(skel); } \n\
1489 void %1$s::detach(struct %1$s *skel) { %1$s__detach(skel); } \n\
1490 void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); } \n\
1491 const void *%1$s::elf_bytes(size_t *sz) { return %1$s__elf_bytes(sz); } \n\
1492 #endif /* __cplusplus */ \n\
1493 \n\
1494 ",
1495 obj_name);
1496
1497 codegen_asserts(obj, obj_name);
1498
1499 codegen("\
1500 \n\
1501 \n\
1502 #endif /* %1$s */ \n\
1503 ",
1504 header_guard);
1505 err = 0;
1506 out:
1507 bpf_object__close(obj);
1508 if (obj_data)
1509 munmap(obj_data, mmap_sz);
1510 close(fd);
1511 return err;
1512 }
1513
1514 /* Subskeletons are like skeletons, except they don't own the bpf_object,
1515 * associated maps, links, etc. Instead, they know about the existence of
1516 * variables, maps, programs and are able to find their locations
1517 * _at runtime_ from an already loaded bpf_object.
1518 *
1519 * This allows for library-like BPF objects to have userspace counterparts
1520 * with access to their own items without having to know anything about the
1521 * final BPF object that the library was linked into.
1522 */
do_subskeleton(int argc,char ** argv)1523 static int do_subskeleton(int argc, char **argv)
1524 {
1525 char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SUBSKEL_H__")];
1526 size_t i, len, file_sz, map_cnt = 0, prog_cnt = 0, mmap_sz, var_cnt = 0, var_idx = 0;
1527 DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
1528 char obj_name[MAX_OBJ_NAME_LEN] = "", *obj_data;
1529 struct bpf_object *obj = NULL;
1530 const char *file, *var_name;
1531 char ident[256];
1532 int fd, err = -1, map_type_id;
1533 const struct bpf_map *map;
1534 struct bpf_program *prog;
1535 struct btf *btf;
1536 const struct btf_type *map_type, *var_type;
1537 const struct btf_var_secinfo *var;
1538 struct stat st;
1539
1540 if (!REQ_ARGS(1)) {
1541 usage();
1542 return -1;
1543 }
1544 file = GET_ARG();
1545
1546 while (argc) {
1547 if (!REQ_ARGS(2))
1548 return -1;
1549
1550 if (is_prefix(*argv, "name")) {
1551 NEXT_ARG();
1552
1553 if (obj_name[0] != '\0') {
1554 p_err("object name already specified");
1555 return -1;
1556 }
1557
1558 strncpy(obj_name, *argv, MAX_OBJ_NAME_LEN - 1);
1559 obj_name[MAX_OBJ_NAME_LEN - 1] = '\0';
1560 } else {
1561 p_err("unknown arg %s", *argv);
1562 return -1;
1563 }
1564
1565 NEXT_ARG();
1566 }
1567
1568 if (argc) {
1569 p_err("extra unknown arguments");
1570 return -1;
1571 }
1572
1573 if (use_loader) {
1574 p_err("cannot use loader for subskeletons");
1575 return -1;
1576 }
1577
1578 if (stat(file, &st)) {
1579 p_err("failed to stat() %s: %s", file, strerror(errno));
1580 return -1;
1581 }
1582 file_sz = st.st_size;
1583 mmap_sz = roundup(file_sz, sysconf(_SC_PAGE_SIZE));
1584 fd = open(file, O_RDONLY);
1585 if (fd < 0) {
1586 p_err("failed to open() %s: %s", file, strerror(errno));
1587 return -1;
1588 }
1589 obj_data = mmap(NULL, mmap_sz, PROT_READ, MAP_PRIVATE, fd, 0);
1590 if (obj_data == MAP_FAILED) {
1591 obj_data = NULL;
1592 p_err("failed to mmap() %s: %s", file, strerror(errno));
1593 goto out;
1594 }
1595 if (obj_name[0] == '\0')
1596 get_obj_name(obj_name, file);
1597
1598 /* The empty object name allows us to use bpf_map__name and produce
1599 * ELF section names out of it. (".data" instead of "obj.data")
1600 */
1601 opts.object_name = "";
1602 obj = bpf_object__open_mem(obj_data, file_sz, &opts);
1603 if (!obj) {
1604 char err_buf[256];
1605
1606 libbpf_strerror(errno, err_buf, sizeof(err_buf));
1607 p_err("failed to open BPF object file: %s", err_buf);
1608 obj = NULL;
1609 goto out;
1610 }
1611
1612 btf = bpf_object__btf(obj);
1613 if (!btf) {
1614 err = -1;
1615 p_err("need btf type information for %s", obj_name);
1616 goto out;
1617 }
1618
1619 bpf_object__for_each_program(prog, obj) {
1620 prog_cnt++;
1621 }
1622
1623 /* First, count how many variables we have to find.
1624 * We need this in advance so the subskel can allocate the right
1625 * amount of storage.
1626 */
1627 bpf_object__for_each_map(map, obj) {
1628 if (!get_map_ident(map, ident, sizeof(ident)))
1629 continue;
1630
1631 /* Also count all maps that have a name */
1632 map_cnt++;
1633
1634 if (!is_mmapable_map(map, ident, sizeof(ident)))
1635 continue;
1636
1637 map_type_id = bpf_map__btf_value_type_id(map);
1638 if (map_type_id <= 0) {
1639 err = map_type_id;
1640 goto out;
1641 }
1642 map_type = btf__type_by_id(btf, map_type_id);
1643
1644 var = btf_var_secinfos(map_type);
1645 len = btf_vlen(map_type);
1646 for (i = 0; i < len; i++, var++) {
1647 var_type = btf__type_by_id(btf, var->type);
1648
1649 if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
1650 continue;
1651
1652 var_cnt++;
1653 }
1654 }
1655
1656 get_header_guard(header_guard, obj_name, "SUBSKEL_H");
1657 codegen("\
1658 \n\
1659 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ \n\
1660 \n\
1661 /* THIS FILE IS AUTOGENERATED! */ \n\
1662 #ifndef %2$s \n\
1663 #define %2$s \n\
1664 \n\
1665 #include <errno.h> \n\
1666 #include <stdlib.h> \n\
1667 #include <bpf/libbpf.h> \n\
1668 \n\
1669 struct %1$s { \n\
1670 struct bpf_object *obj; \n\
1671 struct bpf_object_subskeleton *subskel; \n\
1672 ", obj_name, header_guard);
1673
1674 if (map_cnt) {
1675 printf("\tstruct {\n");
1676 bpf_object__for_each_map(map, obj) {
1677 if (!get_map_ident(map, ident, sizeof(ident)))
1678 continue;
1679 printf("\t\tstruct bpf_map *%s;\n", ident);
1680 }
1681 printf("\t} maps;\n");
1682 }
1683
1684 err = gen_st_ops_shadow(obj_name, btf, obj);
1685 if (err)
1686 goto out;
1687
1688 if (prog_cnt) {
1689 printf("\tstruct {\n");
1690 bpf_object__for_each_program(prog, obj) {
1691 printf("\t\tstruct bpf_program *%s;\n",
1692 bpf_program__name(prog));
1693 }
1694 printf("\t} progs;\n");
1695 }
1696
1697 err = codegen_subskel_datasecs(obj, obj_name);
1698 if (err)
1699 goto out;
1700
1701 /* emit code that will allocate enough storage for all symbols */
1702 codegen("\
1703 \n\
1704 \n\
1705 #ifdef __cplusplus \n\
1706 static inline struct %1$s *open(const struct bpf_object *src);\n\
1707 static inline void destroy(struct %1$s *skel); \n\
1708 #endif /* __cplusplus */ \n\
1709 }; \n\
1710 \n\
1711 static inline void \n\
1712 %1$s__destroy(struct %1$s *skel) \n\
1713 { \n\
1714 if (!skel) \n\
1715 return; \n\
1716 if (skel->subskel) \n\
1717 bpf_object__destroy_subskeleton(skel->subskel);\n\
1718 free(skel); \n\
1719 } \n\
1720 \n\
1721 static inline struct %1$s * \n\
1722 %1$s__open(const struct bpf_object *src) \n\
1723 { \n\
1724 struct %1$s *obj; \n\
1725 struct bpf_object_subskeleton *s; \n\
1726 int err; \n\
1727 \n\
1728 obj = (struct %1$s *)calloc(1, sizeof(*obj)); \n\
1729 if (!obj) { \n\
1730 err = -ENOMEM; \n\
1731 goto err; \n\
1732 } \n\
1733 s = (struct bpf_object_subskeleton *)calloc(1, sizeof(*s));\n\
1734 if (!s) { \n\
1735 err = -ENOMEM; \n\
1736 goto err; \n\
1737 } \n\
1738 s->sz = sizeof(*s); \n\
1739 s->obj = src; \n\
1740 s->var_skel_sz = sizeof(*s->vars); \n\
1741 obj->subskel = s; \n\
1742 \n\
1743 /* vars */ \n\
1744 s->var_cnt = %2$d; \n\
1745 s->vars = (struct bpf_var_skeleton *)calloc(%2$d, sizeof(*s->vars));\n\
1746 if (!s->vars) { \n\
1747 err = -ENOMEM; \n\
1748 goto err; \n\
1749 } \n\
1750 ",
1751 obj_name, var_cnt
1752 );
1753
1754 /* walk through each symbol and emit the runtime representation */
1755 bpf_object__for_each_map(map, obj) {
1756 if (!is_mmapable_map(map, ident, sizeof(ident)))
1757 continue;
1758
1759 map_type_id = bpf_map__btf_value_type_id(map);
1760 if (map_type_id <= 0)
1761 /* skip over internal maps with no type*/
1762 continue;
1763
1764 map_type = btf__type_by_id(btf, map_type_id);
1765 var = btf_var_secinfos(map_type);
1766 len = btf_vlen(map_type);
1767 for (i = 0; i < len; i++, var++) {
1768 var_type = btf__type_by_id(btf, var->type);
1769 var_name = btf__name_by_offset(btf, var_type->name_off);
1770
1771 if (btf_var(var_type)->linkage == BTF_VAR_STATIC)
1772 continue;
1773
1774 /* Note that we use the dot prefix in .data as the
1775 * field access operator i.e. maps%s becomes maps.data
1776 */
1777 codegen("\
1778 \n\
1779 \n\
1780 s->vars[%3$d].name = \"%1$s\"; \n\
1781 s->vars[%3$d].map = &obj->maps.%2$s; \n\
1782 s->vars[%3$d].addr = (void **) &obj->%2$s.%1$s;\n\
1783 ", var_name, ident, var_idx);
1784
1785 var_idx++;
1786 }
1787 }
1788
1789 codegen_maps_skeleton(obj, map_cnt, false /*mmaped*/);
1790 codegen_progs_skeleton(obj, prog_cnt, false /*links*/);
1791
1792 codegen("\
1793 \n\
1794 \n\
1795 err = bpf_object__open_subskeleton(s); \n\
1796 if (err) \n\
1797 goto err; \n\
1798 \n\
1799 ");
1800
1801 gen_st_ops_shadow_init(btf, obj);
1802
1803 codegen("\
1804 \n\
1805 return obj; \n\
1806 err: \n\
1807 %1$s__destroy(obj); \n\
1808 errno = -err; \n\
1809 return NULL; \n\
1810 } \n\
1811 \n\
1812 #ifdef __cplusplus \n\
1813 struct %1$s *%1$s::open(const struct bpf_object *src) { return %1$s__open(src); }\n\
1814 void %1$s::destroy(struct %1$s *skel) { %1$s__destroy(skel); }\n\
1815 #endif /* __cplusplus */ \n\
1816 \n\
1817 #endif /* %2$s */ \n\
1818 ",
1819 obj_name, header_guard);
1820 err = 0;
1821 out:
1822 bpf_object__close(obj);
1823 if (obj_data)
1824 munmap(obj_data, mmap_sz);
1825 close(fd);
1826 return err;
1827 }
1828
do_object(int argc,char ** argv)1829 static int do_object(int argc, char **argv)
1830 {
1831 struct bpf_linker *linker;
1832 const char *output_file, *file;
1833 int err = 0;
1834
1835 if (!REQ_ARGS(2)) {
1836 usage();
1837 return -1;
1838 }
1839
1840 output_file = GET_ARG();
1841
1842 linker = bpf_linker__new(output_file, NULL);
1843 if (!linker) {
1844 p_err("failed to create BPF linker instance");
1845 return -1;
1846 }
1847
1848 while (argc) {
1849 file = GET_ARG();
1850
1851 err = bpf_linker__add_file(linker, file, NULL);
1852 if (err) {
1853 p_err("failed to link '%s': %s (%d)", file, strerror(errno), errno);
1854 goto out;
1855 }
1856 }
1857
1858 err = bpf_linker__finalize(linker);
1859 if (err) {
1860 p_err("failed to finalize ELF file: %s (%d)", strerror(errno), errno);
1861 goto out;
1862 }
1863
1864 err = 0;
1865 out:
1866 bpf_linker__free(linker);
1867 return err;
1868 }
1869
do_help(int argc,char ** argv)1870 static int do_help(int argc, char **argv)
1871 {
1872 if (json_output) {
1873 jsonw_null(json_wtr);
1874 return 0;
1875 }
1876
1877 fprintf(stderr,
1878 "Usage: %1$s %2$s object OUTPUT_FILE INPUT_FILE [INPUT_FILE...]\n"
1879 " %1$s %2$s skeleton FILE [name OBJECT_NAME]\n"
1880 " %1$s %2$s subskeleton FILE [name OBJECT_NAME]\n"
1881 " %1$s %2$s min_core_btf INPUT OUTPUT OBJECT [OBJECT...]\n"
1882 " %1$s %2$s help\n"
1883 "\n"
1884 " " HELP_SPEC_OPTIONS " |\n"
1885 " {-L|--use-loader} }\n"
1886 "",
1887 bin_name, "gen");
1888
1889 return 0;
1890 }
1891
btf_save_raw(const struct btf * btf,const char * path)1892 static int btf_save_raw(const struct btf *btf, const char *path)
1893 {
1894 const void *data;
1895 FILE *f = NULL;
1896 __u32 data_sz;
1897 int err = 0;
1898
1899 data = btf__raw_data(btf, &data_sz);
1900 if (!data)
1901 return -ENOMEM;
1902
1903 f = fopen(path, "wb");
1904 if (!f)
1905 return -errno;
1906
1907 if (fwrite(data, 1, data_sz, f) != data_sz)
1908 err = -errno;
1909
1910 fclose(f);
1911 return err;
1912 }
1913
1914 struct btfgen_info {
1915 struct btf *src_btf;
1916 struct btf *marked_btf; /* btf structure used to mark used types */
1917 };
1918
btfgen_hash_fn(long key,void * ctx)1919 static size_t btfgen_hash_fn(long key, void *ctx)
1920 {
1921 return key;
1922 }
1923
btfgen_equal_fn(long k1,long k2,void * ctx)1924 static bool btfgen_equal_fn(long k1, long k2, void *ctx)
1925 {
1926 return k1 == k2;
1927 }
1928
btfgen_free_info(struct btfgen_info * info)1929 static void btfgen_free_info(struct btfgen_info *info)
1930 {
1931 if (!info)
1932 return;
1933
1934 btf__free(info->src_btf);
1935 btf__free(info->marked_btf);
1936
1937 free(info);
1938 }
1939
1940 static struct btfgen_info *
btfgen_new_info(const char * targ_btf_path)1941 btfgen_new_info(const char *targ_btf_path)
1942 {
1943 struct btfgen_info *info;
1944 int err;
1945
1946 info = calloc(1, sizeof(*info));
1947 if (!info)
1948 return NULL;
1949
1950 info->src_btf = btf__parse(targ_btf_path, NULL);
1951 if (!info->src_btf) {
1952 err = -errno;
1953 p_err("failed parsing '%s' BTF file: %s", targ_btf_path, strerror(errno));
1954 goto err_out;
1955 }
1956
1957 info->marked_btf = btf__parse(targ_btf_path, NULL);
1958 if (!info->marked_btf) {
1959 err = -errno;
1960 p_err("failed parsing '%s' BTF file: %s", targ_btf_path, strerror(errno));
1961 goto err_out;
1962 }
1963
1964 return info;
1965
1966 err_out:
1967 btfgen_free_info(info);
1968 errno = -err;
1969 return NULL;
1970 }
1971
1972 #define MARKED UINT32_MAX
1973
btfgen_mark_member(struct btfgen_info * info,int type_id,int idx)1974 static void btfgen_mark_member(struct btfgen_info *info, int type_id, int idx)
1975 {
1976 const struct btf_type *t = btf__type_by_id(info->marked_btf, type_id);
1977 struct btf_member *m = btf_members(t) + idx;
1978
1979 m->name_off = MARKED;
1980 }
1981
1982 static int
btfgen_mark_type(struct btfgen_info * info,unsigned int type_id,bool follow_pointers)1983 btfgen_mark_type(struct btfgen_info *info, unsigned int type_id, bool follow_pointers)
1984 {
1985 const struct btf_type *btf_type = btf__type_by_id(info->src_btf, type_id);
1986 struct btf_type *cloned_type;
1987 struct btf_param *param;
1988 struct btf_array *array;
1989 int err, i;
1990
1991 if (type_id == 0)
1992 return 0;
1993
1994 /* mark type on cloned BTF as used */
1995 cloned_type = (struct btf_type *) btf__type_by_id(info->marked_btf, type_id);
1996 cloned_type->name_off = MARKED;
1997
1998 /* recursively mark other types needed by it */
1999 switch (btf_kind(btf_type)) {
2000 case BTF_KIND_UNKN:
2001 case BTF_KIND_INT:
2002 case BTF_KIND_FLOAT:
2003 case BTF_KIND_ENUM:
2004 case BTF_KIND_ENUM64:
2005 case BTF_KIND_STRUCT:
2006 case BTF_KIND_UNION:
2007 break;
2008 case BTF_KIND_PTR:
2009 if (follow_pointers) {
2010 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
2011 if (err)
2012 return err;
2013 }
2014 break;
2015 case BTF_KIND_CONST:
2016 case BTF_KIND_RESTRICT:
2017 case BTF_KIND_VOLATILE:
2018 case BTF_KIND_TYPEDEF:
2019 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
2020 if (err)
2021 return err;
2022 break;
2023 case BTF_KIND_ARRAY:
2024 array = btf_array(btf_type);
2025
2026 /* mark array type */
2027 err = btfgen_mark_type(info, array->type, follow_pointers);
2028 /* mark array's index type */
2029 err = err ? : btfgen_mark_type(info, array->index_type, follow_pointers);
2030 if (err)
2031 return err;
2032 break;
2033 case BTF_KIND_FUNC_PROTO:
2034 /* mark ret type */
2035 err = btfgen_mark_type(info, btf_type->type, follow_pointers);
2036 if (err)
2037 return err;
2038
2039 /* mark parameters types */
2040 param = btf_params(btf_type);
2041 for (i = 0; i < btf_vlen(btf_type); i++) {
2042 err = btfgen_mark_type(info, param->type, follow_pointers);
2043 if (err)
2044 return err;
2045 param++;
2046 }
2047 break;
2048 /* tells if some other type needs to be handled */
2049 default:
2050 p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
2051 return -EINVAL;
2052 }
2053
2054 return 0;
2055 }
2056
btfgen_record_field_relo(struct btfgen_info * info,struct bpf_core_spec * targ_spec)2057 static int btfgen_record_field_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
2058 {
2059 struct btf *btf = info->src_btf;
2060 const struct btf_type *btf_type;
2061 struct btf_member *btf_member;
2062 struct btf_array *array;
2063 unsigned int type_id = targ_spec->root_type_id;
2064 int idx, err;
2065
2066 /* mark root type */
2067 btf_type = btf__type_by_id(btf, type_id);
2068 err = btfgen_mark_type(info, type_id, false);
2069 if (err)
2070 return err;
2071
2072 /* mark types for complex types (arrays, unions, structures) */
2073 for (int i = 1; i < targ_spec->raw_len; i++) {
2074 /* skip typedefs and mods */
2075 while (btf_is_mod(btf_type) || btf_is_typedef(btf_type)) {
2076 type_id = btf_type->type;
2077 btf_type = btf__type_by_id(btf, type_id);
2078 }
2079
2080 switch (btf_kind(btf_type)) {
2081 case BTF_KIND_STRUCT:
2082 case BTF_KIND_UNION:
2083 idx = targ_spec->raw_spec[i];
2084 btf_member = btf_members(btf_type) + idx;
2085
2086 /* mark member */
2087 btfgen_mark_member(info, type_id, idx);
2088
2089 /* mark member's type */
2090 type_id = btf_member->type;
2091 btf_type = btf__type_by_id(btf, type_id);
2092 err = btfgen_mark_type(info, type_id, false);
2093 if (err)
2094 return err;
2095 break;
2096 case BTF_KIND_ARRAY:
2097 array = btf_array(btf_type);
2098 type_id = array->type;
2099 btf_type = btf__type_by_id(btf, type_id);
2100 break;
2101 default:
2102 p_err("unsupported kind: %s (%d)",
2103 btf_kind_str(btf_type), btf_type->type);
2104 return -EINVAL;
2105 }
2106 }
2107
2108 return 0;
2109 }
2110
2111 /* Mark types, members, and member types. Compared to btfgen_record_field_relo,
2112 * this function does not rely on the target spec for inferring members, but
2113 * uses the associated BTF.
2114 *
2115 * The `behind_ptr` argument is used to stop marking of composite types reached
2116 * through a pointer. This way, we can keep BTF size in check while providing
2117 * reasonable match semantics.
2118 */
btfgen_mark_type_match(struct btfgen_info * info,__u32 type_id,bool behind_ptr)2119 static int btfgen_mark_type_match(struct btfgen_info *info, __u32 type_id, bool behind_ptr)
2120 {
2121 const struct btf_type *btf_type;
2122 struct btf *btf = info->src_btf;
2123 struct btf_type *cloned_type;
2124 int i, err;
2125
2126 if (type_id == 0)
2127 return 0;
2128
2129 btf_type = btf__type_by_id(btf, type_id);
2130 /* mark type on cloned BTF as used */
2131 cloned_type = (struct btf_type *)btf__type_by_id(info->marked_btf, type_id);
2132 cloned_type->name_off = MARKED;
2133
2134 switch (btf_kind(btf_type)) {
2135 case BTF_KIND_UNKN:
2136 case BTF_KIND_INT:
2137 case BTF_KIND_FLOAT:
2138 case BTF_KIND_ENUM:
2139 case BTF_KIND_ENUM64:
2140 break;
2141 case BTF_KIND_STRUCT:
2142 case BTF_KIND_UNION: {
2143 struct btf_member *m = btf_members(btf_type);
2144 __u16 vlen = btf_vlen(btf_type);
2145
2146 if (behind_ptr)
2147 break;
2148
2149 for (i = 0; i < vlen; i++, m++) {
2150 /* mark member */
2151 btfgen_mark_member(info, type_id, i);
2152
2153 /* mark member's type */
2154 err = btfgen_mark_type_match(info, m->type, false);
2155 if (err)
2156 return err;
2157 }
2158 break;
2159 }
2160 case BTF_KIND_CONST:
2161 case BTF_KIND_FWD:
2162 case BTF_KIND_RESTRICT:
2163 case BTF_KIND_TYPEDEF:
2164 case BTF_KIND_VOLATILE:
2165 return btfgen_mark_type_match(info, btf_type->type, behind_ptr);
2166 case BTF_KIND_PTR:
2167 return btfgen_mark_type_match(info, btf_type->type, true);
2168 case BTF_KIND_ARRAY: {
2169 struct btf_array *array;
2170
2171 array = btf_array(btf_type);
2172 /* mark array type */
2173 err = btfgen_mark_type_match(info, array->type, false);
2174 /* mark array's index type */
2175 err = err ? : btfgen_mark_type_match(info, array->index_type, false);
2176 if (err)
2177 return err;
2178 break;
2179 }
2180 case BTF_KIND_FUNC_PROTO: {
2181 __u16 vlen = btf_vlen(btf_type);
2182 struct btf_param *param;
2183
2184 /* mark ret type */
2185 err = btfgen_mark_type_match(info, btf_type->type, false);
2186 if (err)
2187 return err;
2188
2189 /* mark parameters types */
2190 param = btf_params(btf_type);
2191 for (i = 0; i < vlen; i++) {
2192 err = btfgen_mark_type_match(info, param->type, false);
2193 if (err)
2194 return err;
2195 param++;
2196 }
2197 break;
2198 }
2199 /* tells if some other type needs to be handled */
2200 default:
2201 p_err("unsupported kind: %s (%d)", btf_kind_str(btf_type), type_id);
2202 return -EINVAL;
2203 }
2204
2205 return 0;
2206 }
2207
2208 /* Mark types, members, and member types. Compared to btfgen_record_field_relo,
2209 * this function does not rely on the target spec for inferring members, but
2210 * uses the associated BTF.
2211 */
btfgen_record_type_match_relo(struct btfgen_info * info,struct bpf_core_spec * targ_spec)2212 static int btfgen_record_type_match_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
2213 {
2214 return btfgen_mark_type_match(info, targ_spec->root_type_id, false);
2215 }
2216
btfgen_record_type_relo(struct btfgen_info * info,struct bpf_core_spec * targ_spec)2217 static int btfgen_record_type_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
2218 {
2219 return btfgen_mark_type(info, targ_spec->root_type_id, true);
2220 }
2221
btfgen_record_enumval_relo(struct btfgen_info * info,struct bpf_core_spec * targ_spec)2222 static int btfgen_record_enumval_relo(struct btfgen_info *info, struct bpf_core_spec *targ_spec)
2223 {
2224 return btfgen_mark_type(info, targ_spec->root_type_id, false);
2225 }
2226
btfgen_record_reloc(struct btfgen_info * info,struct bpf_core_spec * res)2227 static int btfgen_record_reloc(struct btfgen_info *info, struct bpf_core_spec *res)
2228 {
2229 switch (res->relo_kind) {
2230 case BPF_CORE_FIELD_BYTE_OFFSET:
2231 case BPF_CORE_FIELD_BYTE_SIZE:
2232 case BPF_CORE_FIELD_EXISTS:
2233 case BPF_CORE_FIELD_SIGNED:
2234 case BPF_CORE_FIELD_LSHIFT_U64:
2235 case BPF_CORE_FIELD_RSHIFT_U64:
2236 return btfgen_record_field_relo(info, res);
2237 case BPF_CORE_TYPE_ID_LOCAL: /* BPF_CORE_TYPE_ID_LOCAL doesn't require kernel BTF */
2238 return 0;
2239 case BPF_CORE_TYPE_ID_TARGET:
2240 case BPF_CORE_TYPE_EXISTS:
2241 case BPF_CORE_TYPE_SIZE:
2242 return btfgen_record_type_relo(info, res);
2243 case BPF_CORE_TYPE_MATCHES:
2244 return btfgen_record_type_match_relo(info, res);
2245 case BPF_CORE_ENUMVAL_EXISTS:
2246 case BPF_CORE_ENUMVAL_VALUE:
2247 return btfgen_record_enumval_relo(info, res);
2248 default:
2249 return -EINVAL;
2250 }
2251 }
2252
2253 static struct bpf_core_cand_list *
btfgen_find_cands(const struct btf * local_btf,const struct btf * targ_btf,__u32 local_id)2254 btfgen_find_cands(const struct btf *local_btf, const struct btf *targ_btf, __u32 local_id)
2255 {
2256 const struct btf_type *local_type;
2257 struct bpf_core_cand_list *cands = NULL;
2258 struct bpf_core_cand local_cand = {};
2259 size_t local_essent_len;
2260 const char *local_name;
2261 int err;
2262
2263 local_cand.btf = local_btf;
2264 local_cand.id = local_id;
2265
2266 local_type = btf__type_by_id(local_btf, local_id);
2267 if (!local_type) {
2268 err = -EINVAL;
2269 goto err_out;
2270 }
2271
2272 local_name = btf__name_by_offset(local_btf, local_type->name_off);
2273 if (!local_name) {
2274 err = -EINVAL;
2275 goto err_out;
2276 }
2277 local_essent_len = bpf_core_essential_name_len(local_name);
2278
2279 cands = calloc(1, sizeof(*cands));
2280 if (!cands)
2281 return NULL;
2282
2283 err = bpf_core_add_cands(&local_cand, local_essent_len, targ_btf, "vmlinux", 1, cands);
2284 if (err)
2285 goto err_out;
2286
2287 return cands;
2288
2289 err_out:
2290 bpf_core_free_cands(cands);
2291 errno = -err;
2292 return NULL;
2293 }
2294
2295 /* Record relocation information for a single BPF object */
btfgen_record_obj(struct btfgen_info * info,const char * obj_path)2296 static int btfgen_record_obj(struct btfgen_info *info, const char *obj_path)
2297 {
2298 const struct btf_ext_info_sec *sec;
2299 const struct bpf_core_relo *relo;
2300 const struct btf_ext_info *seg;
2301 struct hashmap_entry *entry;
2302 struct hashmap *cand_cache = NULL;
2303 struct btf_ext *btf_ext = NULL;
2304 unsigned int relo_idx;
2305 struct btf *btf = NULL;
2306 size_t i;
2307 int err;
2308
2309 btf = btf__parse(obj_path, &btf_ext);
2310 if (!btf) {
2311 err = -errno;
2312 p_err("failed to parse BPF object '%s': %s", obj_path, strerror(errno));
2313 return err;
2314 }
2315
2316 if (!btf_ext) {
2317 p_err("failed to parse BPF object '%s': section %s not found",
2318 obj_path, BTF_EXT_ELF_SEC);
2319 err = -EINVAL;
2320 goto out;
2321 }
2322
2323 if (btf_ext->core_relo_info.len == 0) {
2324 err = 0;
2325 goto out;
2326 }
2327
2328 cand_cache = hashmap__new(btfgen_hash_fn, btfgen_equal_fn, NULL);
2329 if (IS_ERR(cand_cache)) {
2330 err = PTR_ERR(cand_cache);
2331 goto out;
2332 }
2333
2334 seg = &btf_ext->core_relo_info;
2335 for_each_btf_ext_sec(seg, sec) {
2336 for_each_btf_ext_rec(seg, sec, relo_idx, relo) {
2337 struct bpf_core_spec specs_scratch[3] = {};
2338 struct bpf_core_relo_res targ_res = {};
2339 struct bpf_core_cand_list *cands = NULL;
2340 const char *sec_name = btf__name_by_offset(btf, sec->sec_name_off);
2341
2342 if (relo->kind != BPF_CORE_TYPE_ID_LOCAL &&
2343 !hashmap__find(cand_cache, relo->type_id, &cands)) {
2344 cands = btfgen_find_cands(btf, info->src_btf, relo->type_id);
2345 if (!cands) {
2346 err = -errno;
2347 goto out;
2348 }
2349
2350 err = hashmap__set(cand_cache, relo->type_id, cands,
2351 NULL, NULL);
2352 if (err)
2353 goto out;
2354 }
2355
2356 err = bpf_core_calc_relo_insn(sec_name, relo, relo_idx, btf, cands,
2357 specs_scratch, &targ_res);
2358 if (err)
2359 goto out;
2360
2361 /* specs_scratch[2] is the target spec */
2362 err = btfgen_record_reloc(info, &specs_scratch[2]);
2363 if (err)
2364 goto out;
2365 }
2366 }
2367
2368 out:
2369 btf__free(btf);
2370 btf_ext__free(btf_ext);
2371
2372 if (!IS_ERR_OR_NULL(cand_cache)) {
2373 hashmap__for_each_entry(cand_cache, entry, i) {
2374 bpf_core_free_cands(entry->pvalue);
2375 }
2376 hashmap__free(cand_cache);
2377 }
2378
2379 return err;
2380 }
2381
btfgen_remap_id(__u32 * type_id,void * ctx)2382 static int btfgen_remap_id(__u32 *type_id, void *ctx)
2383 {
2384 unsigned int *ids = ctx;
2385
2386 *type_id = ids[*type_id];
2387
2388 return 0;
2389 }
2390
2391 /* Generate BTF from relocation information previously recorded */
btfgen_get_btf(struct btfgen_info * info)2392 static struct btf *btfgen_get_btf(struct btfgen_info *info)
2393 {
2394 struct btf *btf_new = NULL;
2395 unsigned int *ids = NULL;
2396 unsigned int i, n = btf__type_cnt(info->marked_btf);
2397 int err = 0;
2398
2399 btf_new = btf__new_empty();
2400 if (!btf_new) {
2401 err = -errno;
2402 goto err_out;
2403 }
2404
2405 ids = calloc(n, sizeof(*ids));
2406 if (!ids) {
2407 err = -errno;
2408 goto err_out;
2409 }
2410
2411 /* first pass: add all marked types to btf_new and add their new ids to the ids map */
2412 for (i = 1; i < n; i++) {
2413 const struct btf_type *cloned_type, *type;
2414 const char *name;
2415 int new_id;
2416
2417 cloned_type = btf__type_by_id(info->marked_btf, i);
2418
2419 if (cloned_type->name_off != MARKED)
2420 continue;
2421
2422 type = btf__type_by_id(info->src_btf, i);
2423
2424 /* add members for struct and union */
2425 if (btf_is_composite(type)) {
2426 struct btf_member *cloned_m, *m;
2427 unsigned short vlen;
2428 int idx_src;
2429
2430 name = btf__str_by_offset(info->src_btf, type->name_off);
2431
2432 if (btf_is_struct(type))
2433 err = btf__add_struct(btf_new, name, type->size);
2434 else
2435 err = btf__add_union(btf_new, name, type->size);
2436
2437 if (err < 0)
2438 goto err_out;
2439 new_id = err;
2440
2441 cloned_m = btf_members(cloned_type);
2442 m = btf_members(type);
2443 vlen = btf_vlen(cloned_type);
2444 for (idx_src = 0; idx_src < vlen; idx_src++, cloned_m++, m++) {
2445 /* add only members that are marked as used */
2446 if (cloned_m->name_off != MARKED)
2447 continue;
2448
2449 name = btf__str_by_offset(info->src_btf, m->name_off);
2450 err = btf__add_field(btf_new, name, m->type,
2451 btf_member_bit_offset(cloned_type, idx_src),
2452 btf_member_bitfield_size(cloned_type, idx_src));
2453 if (err < 0)
2454 goto err_out;
2455 }
2456 } else {
2457 err = btf__add_type(btf_new, info->src_btf, type);
2458 if (err < 0)
2459 goto err_out;
2460 new_id = err;
2461 }
2462
2463 /* add ID mapping */
2464 ids[i] = new_id;
2465 }
2466
2467 /* second pass: fix up type ids */
2468 for (i = 1; i < btf__type_cnt(btf_new); i++) {
2469 struct btf_type *btf_type = (struct btf_type *) btf__type_by_id(btf_new, i);
2470
2471 err = btf_type_visit_type_ids(btf_type, btfgen_remap_id, ids);
2472 if (err)
2473 goto err_out;
2474 }
2475
2476 free(ids);
2477 return btf_new;
2478
2479 err_out:
2480 btf__free(btf_new);
2481 free(ids);
2482 errno = -err;
2483 return NULL;
2484 }
2485
2486 /* Create minimized BTF file for a set of BPF objects.
2487 *
2488 * The BTFGen algorithm is divided in two main parts: (1) collect the
2489 * BTF types that are involved in relocations and (2) generate the BTF
2490 * object using the collected types.
2491 *
2492 * In order to collect the types involved in the relocations, we parse
2493 * the BTF and BTF.ext sections of the BPF objects and use
2494 * bpf_core_calc_relo_insn() to get the target specification, this
2495 * indicates how the types and fields are used in a relocation.
2496 *
2497 * Types are recorded in different ways according to the kind of the
2498 * relocation. For field-based relocations only the members that are
2499 * actually used are saved in order to reduce the size of the generated
2500 * BTF file. For type-based relocations empty struct / unions are
2501 * generated and for enum-based relocations the whole type is saved.
2502 *
2503 * The second part of the algorithm generates the BTF object. It creates
2504 * an empty BTF object and fills it with the types recorded in the
2505 * previous step. This function takes care of only adding the structure
2506 * and union members that were marked as used and it also fixes up the
2507 * type IDs on the generated BTF object.
2508 */
minimize_btf(const char * src_btf,const char * dst_btf,const char * objspaths[])2509 static int minimize_btf(const char *src_btf, const char *dst_btf, const char *objspaths[])
2510 {
2511 struct btfgen_info *info;
2512 struct btf *btf_new = NULL;
2513 int err, i;
2514
2515 info = btfgen_new_info(src_btf);
2516 if (!info) {
2517 err = -errno;
2518 p_err("failed to allocate info structure: %s", strerror(errno));
2519 goto out;
2520 }
2521
2522 for (i = 0; objspaths[i] != NULL; i++) {
2523 err = btfgen_record_obj(info, objspaths[i]);
2524 if (err) {
2525 p_err("error recording relocations for %s: %s", objspaths[i],
2526 strerror(errno));
2527 goto out;
2528 }
2529 }
2530
2531 btf_new = btfgen_get_btf(info);
2532 if (!btf_new) {
2533 err = -errno;
2534 p_err("error generating BTF: %s", strerror(errno));
2535 goto out;
2536 }
2537
2538 err = btf_save_raw(btf_new, dst_btf);
2539 if (err) {
2540 p_err("error saving btf file: %s", strerror(errno));
2541 goto out;
2542 }
2543
2544 out:
2545 btf__free(btf_new);
2546 btfgen_free_info(info);
2547
2548 return err;
2549 }
2550
do_min_core_btf(int argc,char ** argv)2551 static int do_min_core_btf(int argc, char **argv)
2552 {
2553 const char *input, *output, **objs;
2554 int i, err;
2555
2556 if (!REQ_ARGS(3)) {
2557 usage();
2558 return -1;
2559 }
2560
2561 input = GET_ARG();
2562 output = GET_ARG();
2563
2564 objs = (const char **) calloc(argc + 1, sizeof(*objs));
2565 if (!objs) {
2566 p_err("failed to allocate array for object names");
2567 return -ENOMEM;
2568 }
2569
2570 i = 0;
2571 while (argc)
2572 objs[i++] = GET_ARG();
2573
2574 err = minimize_btf(input, output, objs);
2575 free(objs);
2576 return err;
2577 }
2578
2579 static const struct cmd cmds[] = {
2580 { "object", do_object },
2581 { "skeleton", do_skeleton },
2582 { "subskeleton", do_subskeleton },
2583 { "min_core_btf", do_min_core_btf},
2584 { "help", do_help },
2585 { 0 }
2586 };
2587
do_gen(int argc,char ** argv)2588 int do_gen(int argc, char **argv)
2589 {
2590 return cmd_select(cmds, argc, argv, do_help);
2591 }
2592