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tools lib bpf: Use official ELF e_machine value
[deliverable/linux.git] / tools / lib / bpf / libbpf.c
1 /*
2 * Common eBPF ELF object loading operations.
3 *
4 * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
5 * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
6 * Copyright (C) 2015 Huawei Inc.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation;
11 * version 2.1 of the License (not later!)
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this program; if not, see <http://www.gnu.org/licenses>
20 */
21
22 #include <stdlib.h>
23 #include <stdio.h>
24 #include <stdarg.h>
25 #include <inttypes.h>
26 #include <string.h>
27 #include <unistd.h>
28 #include <fcntl.h>
29 #include <errno.h>
30 #include <asm/unistd.h>
31 #include <linux/kernel.h>
32 #include <linux/bpf.h>
33 #include <linux/list.h>
34 #include <libelf.h>
35 #include <gelf.h>
36
37 #include "libbpf.h"
38 #include "bpf.h"
39
40 #ifndef EM_BPF
41 #define EM_BPF 247
42 #endif
43
44 #define __printf(a, b) __attribute__((format(printf, a, b)))
45
46 __printf(1, 2)
47 static int __base_pr(const char *format, ...)
48 {
49 va_list args;
50 int err;
51
52 va_start(args, format);
53 err = vfprintf(stderr, format, args);
54 va_end(args);
55 return err;
56 }
57
58 static __printf(1, 2) libbpf_print_fn_t __pr_warning = __base_pr;
59 static __printf(1, 2) libbpf_print_fn_t __pr_info = __base_pr;
60 static __printf(1, 2) libbpf_print_fn_t __pr_debug;
61
62 #define __pr(func, fmt, ...) \
63 do { \
64 if ((func)) \
65 (func)("libbpf: " fmt, ##__VA_ARGS__); \
66 } while (0)
67
68 #define pr_warning(fmt, ...) __pr(__pr_warning, fmt, ##__VA_ARGS__)
69 #define pr_info(fmt, ...) __pr(__pr_info, fmt, ##__VA_ARGS__)
70 #define pr_debug(fmt, ...) __pr(__pr_debug, fmt, ##__VA_ARGS__)
71
72 void libbpf_set_print(libbpf_print_fn_t warn,
73 libbpf_print_fn_t info,
74 libbpf_print_fn_t debug)
75 {
76 __pr_warning = warn;
77 __pr_info = info;
78 __pr_debug = debug;
79 }
80
81 #define STRERR_BUFSIZE 128
82
83 #define ERRNO_OFFSET(e) ((e) - __LIBBPF_ERRNO__START)
84 #define ERRCODE_OFFSET(c) ERRNO_OFFSET(LIBBPF_ERRNO__##c)
85 #define NR_ERRNO (__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START)
86
87 static const char *libbpf_strerror_table[NR_ERRNO] = {
88 [ERRCODE_OFFSET(LIBELF)] = "Something wrong in libelf",
89 [ERRCODE_OFFSET(FORMAT)] = "BPF object format invalid",
90 [ERRCODE_OFFSET(KVERSION)] = "'version' section incorrect or lost",
91 [ERRCODE_OFFSET(ENDIAN)] = "Endian mismatch",
92 [ERRCODE_OFFSET(INTERNAL)] = "Internal error in libbpf",
93 [ERRCODE_OFFSET(RELOC)] = "Relocation failed",
94 [ERRCODE_OFFSET(VERIFY)] = "Kernel verifier blocks program loading",
95 [ERRCODE_OFFSET(PROG2BIG)] = "Program too big",
96 [ERRCODE_OFFSET(KVER)] = "Incorrect kernel version",
97 [ERRCODE_OFFSET(PROGTYPE)] = "Kernel doesn't support this program type",
98 };
99
100 int libbpf_strerror(int err, char *buf, size_t size)
101 {
102 if (!buf || !size)
103 return -1;
104
105 err = err > 0 ? err : -err;
106
107 if (err < __LIBBPF_ERRNO__START) {
108 int ret;
109
110 ret = strerror_r(err, buf, size);
111 buf[size - 1] = '\0';
112 return ret;
113 }
114
115 if (err < __LIBBPF_ERRNO__END) {
116 const char *msg;
117
118 msg = libbpf_strerror_table[ERRNO_OFFSET(err)];
119 snprintf(buf, size, "%s", msg);
120 buf[size - 1] = '\0';
121 return 0;
122 }
123
124 snprintf(buf, size, "Unknown libbpf error %d", err);
125 buf[size - 1] = '\0';
126 return -1;
127 }
128
129 #define CHECK_ERR(action, err, out) do { \
130 err = action; \
131 if (err) \
132 goto out; \
133 } while(0)
134
135
136 /* Copied from tools/perf/util/util.h */
137 #ifndef zfree
138 # define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
139 #endif
140
141 #ifndef zclose
142 # define zclose(fd) ({ \
143 int ___err = 0; \
144 if ((fd) >= 0) \
145 ___err = close((fd)); \
146 fd = -1; \
147 ___err; })
148 #endif
149
150 #ifdef HAVE_LIBELF_MMAP_SUPPORT
151 # define LIBBPF_ELF_C_READ_MMAP ELF_C_READ_MMAP
152 #else
153 # define LIBBPF_ELF_C_READ_MMAP ELF_C_READ
154 #endif
155
156 /*
157 * bpf_prog should be a better name but it has been used in
158 * linux/filter.h.
159 */
160 struct bpf_program {
161 /* Index in elf obj file, for relocation use. */
162 int idx;
163 char *section_name;
164 struct bpf_insn *insns;
165 size_t insns_cnt;
166 enum bpf_prog_type type;
167
168 struct {
169 int insn_idx;
170 int map_idx;
171 } *reloc_desc;
172 int nr_reloc;
173
174 struct {
175 int nr;
176 int *fds;
177 } instances;
178 bpf_program_prep_t preprocessor;
179
180 struct bpf_object *obj;
181 void *priv;
182 bpf_program_clear_priv_t clear_priv;
183 };
184
185 struct bpf_map {
186 int fd;
187 char *name;
188 struct bpf_map_def def;
189 void *priv;
190 bpf_map_clear_priv_t clear_priv;
191 };
192
193 static LIST_HEAD(bpf_objects_list);
194
195 struct bpf_object {
196 char license[64];
197 u32 kern_version;
198
199 struct bpf_program *programs;
200 size_t nr_programs;
201 struct bpf_map *maps;
202 size_t nr_maps;
203
204 bool loaded;
205
206 /*
207 * Information when doing elf related work. Only valid if fd
208 * is valid.
209 */
210 struct {
211 int fd;
212 void *obj_buf;
213 size_t obj_buf_sz;
214 Elf *elf;
215 GElf_Ehdr ehdr;
216 Elf_Data *symbols;
217 size_t strtabidx;
218 struct {
219 GElf_Shdr shdr;
220 Elf_Data *data;
221 } *reloc;
222 int nr_reloc;
223 int maps_shndx;
224 } efile;
225 /*
226 * All loaded bpf_object is linked in a list, which is
227 * hidden to caller. bpf_objects__<func> handlers deal with
228 * all objects.
229 */
230 struct list_head list;
231 char path[];
232 };
233 #define obj_elf_valid(o) ((o)->efile.elf)
234
235 static void bpf_program__unload(struct bpf_program *prog)
236 {
237 int i;
238
239 if (!prog)
240 return;
241
242 /*
243 * If the object is opened but the program was never loaded,
244 * it is possible that prog->instances.nr == -1.
245 */
246 if (prog->instances.nr > 0) {
247 for (i = 0; i < prog->instances.nr; i++)
248 zclose(prog->instances.fds[i]);
249 } else if (prog->instances.nr != -1) {
250 pr_warning("Internal error: instances.nr is %d\n",
251 prog->instances.nr);
252 }
253
254 prog->instances.nr = -1;
255 zfree(&prog->instances.fds);
256 }
257
258 static void bpf_program__exit(struct bpf_program *prog)
259 {
260 if (!prog)
261 return;
262
263 if (prog->clear_priv)
264 prog->clear_priv(prog, prog->priv);
265
266 prog->priv = NULL;
267 prog->clear_priv = NULL;
268
269 bpf_program__unload(prog);
270 zfree(&prog->section_name);
271 zfree(&prog->insns);
272 zfree(&prog->reloc_desc);
273
274 prog->nr_reloc = 0;
275 prog->insns_cnt = 0;
276 prog->idx = -1;
277 }
278
279 static int
280 bpf_program__init(void *data, size_t size, char *name, int idx,
281 struct bpf_program *prog)
282 {
283 if (size < sizeof(struct bpf_insn)) {
284 pr_warning("corrupted section '%s'\n", name);
285 return -EINVAL;
286 }
287
288 bzero(prog, sizeof(*prog));
289
290 prog->section_name = strdup(name);
291 if (!prog->section_name) {
292 pr_warning("failed to alloc name for prog %s\n",
293 name);
294 goto errout;
295 }
296
297 prog->insns = malloc(size);
298 if (!prog->insns) {
299 pr_warning("failed to alloc insns for %s\n", name);
300 goto errout;
301 }
302 prog->insns_cnt = size / sizeof(struct bpf_insn);
303 memcpy(prog->insns, data,
304 prog->insns_cnt * sizeof(struct bpf_insn));
305 prog->idx = idx;
306 prog->instances.fds = NULL;
307 prog->instances.nr = -1;
308 prog->type = BPF_PROG_TYPE_KPROBE;
309
310 return 0;
311 errout:
312 bpf_program__exit(prog);
313 return -ENOMEM;
314 }
315
316 static int
317 bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
318 char *name, int idx)
319 {
320 struct bpf_program prog, *progs;
321 int nr_progs, err;
322
323 err = bpf_program__init(data, size, name, idx, &prog);
324 if (err)
325 return err;
326
327 progs = obj->programs;
328 nr_progs = obj->nr_programs;
329
330 progs = realloc(progs, sizeof(progs[0]) * (nr_progs + 1));
331 if (!progs) {
332 /*
333 * In this case the original obj->programs
334 * is still valid, so don't need special treat for
335 * bpf_close_object().
336 */
337 pr_warning("failed to alloc a new program '%s'\n",
338 name);
339 bpf_program__exit(&prog);
340 return -ENOMEM;
341 }
342
343 pr_debug("found program %s\n", prog.section_name);
344 obj->programs = progs;
345 obj->nr_programs = nr_progs + 1;
346 prog.obj = obj;
347 progs[nr_progs] = prog;
348 return 0;
349 }
350
351 static struct bpf_object *bpf_object__new(const char *path,
352 void *obj_buf,
353 size_t obj_buf_sz)
354 {
355 struct bpf_object *obj;
356
357 obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
358 if (!obj) {
359 pr_warning("alloc memory failed for %s\n", path);
360 return ERR_PTR(-ENOMEM);
361 }
362
363 strcpy(obj->path, path);
364 obj->efile.fd = -1;
365
366 /*
367 * Caller of this function should also calls
368 * bpf_object__elf_finish() after data collection to return
369 * obj_buf to user. If not, we should duplicate the buffer to
370 * avoid user freeing them before elf finish.
371 */
372 obj->efile.obj_buf = obj_buf;
373 obj->efile.obj_buf_sz = obj_buf_sz;
374 obj->efile.maps_shndx = -1;
375
376 obj->loaded = false;
377
378 INIT_LIST_HEAD(&obj->list);
379 list_add(&obj->list, &bpf_objects_list);
380 return obj;
381 }
382
383 static void bpf_object__elf_finish(struct bpf_object *obj)
384 {
385 if (!obj_elf_valid(obj))
386 return;
387
388 if (obj->efile.elf) {
389 elf_end(obj->efile.elf);
390 obj->efile.elf = NULL;
391 }
392 obj->efile.symbols = NULL;
393
394 zfree(&obj->efile.reloc);
395 obj->efile.nr_reloc = 0;
396 zclose(obj->efile.fd);
397 obj->efile.obj_buf = NULL;
398 obj->efile.obj_buf_sz = 0;
399 }
400
401 static int bpf_object__elf_init(struct bpf_object *obj)
402 {
403 int err = 0;
404 GElf_Ehdr *ep;
405
406 if (obj_elf_valid(obj)) {
407 pr_warning("elf init: internal error\n");
408 return -LIBBPF_ERRNO__LIBELF;
409 }
410
411 if (obj->efile.obj_buf_sz > 0) {
412 /*
413 * obj_buf should have been validated by
414 * bpf_object__open_buffer().
415 */
416 obj->efile.elf = elf_memory(obj->efile.obj_buf,
417 obj->efile.obj_buf_sz);
418 } else {
419 obj->efile.fd = open(obj->path, O_RDONLY);
420 if (obj->efile.fd < 0) {
421 pr_warning("failed to open %s: %s\n", obj->path,
422 strerror(errno));
423 return -errno;
424 }
425
426 obj->efile.elf = elf_begin(obj->efile.fd,
427 LIBBPF_ELF_C_READ_MMAP,
428 NULL);
429 }
430
431 if (!obj->efile.elf) {
432 pr_warning("failed to open %s as ELF file\n",
433 obj->path);
434 err = -LIBBPF_ERRNO__LIBELF;
435 goto errout;
436 }
437
438 if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) {
439 pr_warning("failed to get EHDR from %s\n",
440 obj->path);
441 err = -LIBBPF_ERRNO__FORMAT;
442 goto errout;
443 }
444 ep = &obj->efile.ehdr;
445
446 /* Old LLVM set e_machine to EM_NONE */
447 if ((ep->e_type != ET_REL) || (ep->e_machine && (ep->e_machine != EM_BPF))) {
448 pr_warning("%s is not an eBPF object file\n",
449 obj->path);
450 err = -LIBBPF_ERRNO__FORMAT;
451 goto errout;
452 }
453
454 return 0;
455 errout:
456 bpf_object__elf_finish(obj);
457 return err;
458 }
459
460 static int
461 bpf_object__check_endianness(struct bpf_object *obj)
462 {
463 static unsigned int const endian = 1;
464
465 switch (obj->efile.ehdr.e_ident[EI_DATA]) {
466 case ELFDATA2LSB:
467 /* We are big endian, BPF obj is little endian. */
468 if (*(unsigned char const *)&endian != 1)
469 goto mismatch;
470 break;
471
472 case ELFDATA2MSB:
473 /* We are little endian, BPF obj is big endian. */
474 if (*(unsigned char const *)&endian != 0)
475 goto mismatch;
476 break;
477 default:
478 return -LIBBPF_ERRNO__ENDIAN;
479 }
480
481 return 0;
482
483 mismatch:
484 pr_warning("Error: endianness mismatch.\n");
485 return -LIBBPF_ERRNO__ENDIAN;
486 }
487
488 static int
489 bpf_object__init_license(struct bpf_object *obj,
490 void *data, size_t size)
491 {
492 memcpy(obj->license, data,
493 min(size, sizeof(obj->license) - 1));
494 pr_debug("license of %s is %s\n", obj->path, obj->license);
495 return 0;
496 }
497
498 static int
499 bpf_object__init_kversion(struct bpf_object *obj,
500 void *data, size_t size)
501 {
502 u32 kver;
503
504 if (size != sizeof(kver)) {
505 pr_warning("invalid kver section in %s\n", obj->path);
506 return -LIBBPF_ERRNO__FORMAT;
507 }
508 memcpy(&kver, data, sizeof(kver));
509 obj->kern_version = kver;
510 pr_debug("kernel version of %s is %x\n", obj->path,
511 obj->kern_version);
512 return 0;
513 }
514
515 static int
516 bpf_object__init_maps(struct bpf_object *obj, void *data,
517 size_t size)
518 {
519 size_t nr_maps;
520 int i;
521
522 nr_maps = size / sizeof(struct bpf_map_def);
523 if (!data || !nr_maps) {
524 pr_debug("%s doesn't need map definition\n",
525 obj->path);
526 return 0;
527 }
528
529 pr_debug("maps in %s: %zd bytes\n", obj->path, size);
530
531 obj->maps = calloc(nr_maps, sizeof(obj->maps[0]));
532 if (!obj->maps) {
533 pr_warning("alloc maps for object failed\n");
534 return -ENOMEM;
535 }
536 obj->nr_maps = nr_maps;
537
538 for (i = 0; i < nr_maps; i++) {
539 struct bpf_map_def *def = &obj->maps[i].def;
540
541 /*
542 * fill all fd with -1 so won't close incorrect
543 * fd (fd=0 is stdin) when failure (zclose won't close
544 * negative fd)).
545 */
546 obj->maps[i].fd = -1;
547
548 /* Save map definition into obj->maps */
549 *def = ((struct bpf_map_def *)data)[i];
550 }
551 return 0;
552 }
553
554 static int
555 bpf_object__init_maps_name(struct bpf_object *obj)
556 {
557 int i;
558 Elf_Data *symbols = obj->efile.symbols;
559
560 if (!symbols || obj->efile.maps_shndx < 0)
561 return -EINVAL;
562
563 for (i = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) {
564 GElf_Sym sym;
565 size_t map_idx;
566 const char *map_name;
567
568 if (!gelf_getsym(symbols, i, &sym))
569 continue;
570 if (sym.st_shndx != obj->efile.maps_shndx)
571 continue;
572
573 map_name = elf_strptr(obj->efile.elf,
574 obj->efile.strtabidx,
575 sym.st_name);
576 map_idx = sym.st_value / sizeof(struct bpf_map_def);
577 if (map_idx >= obj->nr_maps) {
578 pr_warning("index of map \"%s\" is buggy: %zu > %zu\n",
579 map_name, map_idx, obj->nr_maps);
580 continue;
581 }
582 obj->maps[map_idx].name = strdup(map_name);
583 if (!obj->maps[map_idx].name) {
584 pr_warning("failed to alloc map name\n");
585 return -ENOMEM;
586 }
587 pr_debug("map %zu is \"%s\"\n", map_idx,
588 obj->maps[map_idx].name);
589 }
590 return 0;
591 }
592
593 static int bpf_object__elf_collect(struct bpf_object *obj)
594 {
595 Elf *elf = obj->efile.elf;
596 GElf_Ehdr *ep = &obj->efile.ehdr;
597 Elf_Scn *scn = NULL;
598 int idx = 0, err = 0;
599
600 /* Elf is corrupted/truncated, avoid calling elf_strptr. */
601 if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) {
602 pr_warning("failed to get e_shstrndx from %s\n",
603 obj->path);
604 return -LIBBPF_ERRNO__FORMAT;
605 }
606
607 while ((scn = elf_nextscn(elf, scn)) != NULL) {
608 char *name;
609 GElf_Shdr sh;
610 Elf_Data *data;
611
612 idx++;
613 if (gelf_getshdr(scn, &sh) != &sh) {
614 pr_warning("failed to get section header from %s\n",
615 obj->path);
616 err = -LIBBPF_ERRNO__FORMAT;
617 goto out;
618 }
619
620 name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
621 if (!name) {
622 pr_warning("failed to get section name from %s\n",
623 obj->path);
624 err = -LIBBPF_ERRNO__FORMAT;
625 goto out;
626 }
627
628 data = elf_getdata(scn, 0);
629 if (!data) {
630 pr_warning("failed to get section data from %s(%s)\n",
631 name, obj->path);
632 err = -LIBBPF_ERRNO__FORMAT;
633 goto out;
634 }
635 pr_debug("section %s, size %ld, link %d, flags %lx, type=%d\n",
636 name, (unsigned long)data->d_size,
637 (int)sh.sh_link, (unsigned long)sh.sh_flags,
638 (int)sh.sh_type);
639
640 if (strcmp(name, "license") == 0)
641 err = bpf_object__init_license(obj,
642 data->d_buf,
643 data->d_size);
644 else if (strcmp(name, "version") == 0)
645 err = bpf_object__init_kversion(obj,
646 data->d_buf,
647 data->d_size);
648 else if (strcmp(name, "maps") == 0) {
649 err = bpf_object__init_maps(obj, data->d_buf,
650 data->d_size);
651 obj->efile.maps_shndx = idx;
652 } else if (sh.sh_type == SHT_SYMTAB) {
653 if (obj->efile.symbols) {
654 pr_warning("bpf: multiple SYMTAB in %s\n",
655 obj->path);
656 err = -LIBBPF_ERRNO__FORMAT;
657 } else {
658 obj->efile.symbols = data;
659 obj->efile.strtabidx = sh.sh_link;
660 }
661 } else if ((sh.sh_type == SHT_PROGBITS) &&
662 (sh.sh_flags & SHF_EXECINSTR) &&
663 (data->d_size > 0)) {
664 err = bpf_object__add_program(obj, data->d_buf,
665 data->d_size, name, idx);
666 if (err) {
667 char errmsg[STRERR_BUFSIZE];
668
669 strerror_r(-err, errmsg, sizeof(errmsg));
670 pr_warning("failed to alloc program %s (%s): %s",
671 name, obj->path, errmsg);
672 }
673 } else if (sh.sh_type == SHT_REL) {
674 void *reloc = obj->efile.reloc;
675 int nr_reloc = obj->efile.nr_reloc + 1;
676
677 reloc = realloc(reloc,
678 sizeof(*obj->efile.reloc) * nr_reloc);
679 if (!reloc) {
680 pr_warning("realloc failed\n");
681 err = -ENOMEM;
682 } else {
683 int n = nr_reloc - 1;
684
685 obj->efile.reloc = reloc;
686 obj->efile.nr_reloc = nr_reloc;
687
688 obj->efile.reloc[n].shdr = sh;
689 obj->efile.reloc[n].data = data;
690 }
691 }
692 if (err)
693 goto out;
694 }
695
696 if (!obj->efile.strtabidx || obj->efile.strtabidx >= idx) {
697 pr_warning("Corrupted ELF file: index of strtab invalid\n");
698 return LIBBPF_ERRNO__FORMAT;
699 }
700 if (obj->efile.maps_shndx >= 0)
701 err = bpf_object__init_maps_name(obj);
702 out:
703 return err;
704 }
705
706 static struct bpf_program *
707 bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
708 {
709 struct bpf_program *prog;
710 size_t i;
711
712 for (i = 0; i < obj->nr_programs; i++) {
713 prog = &obj->programs[i];
714 if (prog->idx == idx)
715 return prog;
716 }
717 return NULL;
718 }
719
720 static int
721 bpf_program__collect_reloc(struct bpf_program *prog,
722 size_t nr_maps, GElf_Shdr *shdr,
723 Elf_Data *data, Elf_Data *symbols,
724 int maps_shndx)
725 {
726 int i, nrels;
727
728 pr_debug("collecting relocating info for: '%s'\n",
729 prog->section_name);
730 nrels = shdr->sh_size / shdr->sh_entsize;
731
732 prog->reloc_desc = malloc(sizeof(*prog->reloc_desc) * nrels);
733 if (!prog->reloc_desc) {
734 pr_warning("failed to alloc memory in relocation\n");
735 return -ENOMEM;
736 }
737 prog->nr_reloc = nrels;
738
739 for (i = 0; i < nrels; i++) {
740 GElf_Sym sym;
741 GElf_Rel rel;
742 unsigned int insn_idx;
743 struct bpf_insn *insns = prog->insns;
744 size_t map_idx;
745
746 if (!gelf_getrel(data, i, &rel)) {
747 pr_warning("relocation: failed to get %d reloc\n", i);
748 return -LIBBPF_ERRNO__FORMAT;
749 }
750
751 if (!gelf_getsym(symbols,
752 GELF_R_SYM(rel.r_info),
753 &sym)) {
754 pr_warning("relocation: symbol %"PRIx64" not found\n",
755 GELF_R_SYM(rel.r_info));
756 return -LIBBPF_ERRNO__FORMAT;
757 }
758
759 if (sym.st_shndx != maps_shndx) {
760 pr_warning("Program '%s' contains non-map related relo data pointing to section %u\n",
761 prog->section_name, sym.st_shndx);
762 return -LIBBPF_ERRNO__RELOC;
763 }
764
765 insn_idx = rel.r_offset / sizeof(struct bpf_insn);
766 pr_debug("relocation: insn_idx=%u\n", insn_idx);
767
768 if (insns[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) {
769 pr_warning("bpf: relocation: invalid relo for insns[%d].code 0x%x\n",
770 insn_idx, insns[insn_idx].code);
771 return -LIBBPF_ERRNO__RELOC;
772 }
773
774 map_idx = sym.st_value / sizeof(struct bpf_map_def);
775 if (map_idx >= nr_maps) {
776 pr_warning("bpf relocation: map_idx %d large than %d\n",
777 (int)map_idx, (int)nr_maps - 1);
778 return -LIBBPF_ERRNO__RELOC;
779 }
780
781 prog->reloc_desc[i].insn_idx = insn_idx;
782 prog->reloc_desc[i].map_idx = map_idx;
783 }
784 return 0;
785 }
786
787 static int
788 bpf_object__create_maps(struct bpf_object *obj)
789 {
790 unsigned int i;
791
792 for (i = 0; i < obj->nr_maps; i++) {
793 struct bpf_map_def *def = &obj->maps[i].def;
794 int *pfd = &obj->maps[i].fd;
795
796 *pfd = bpf_create_map(def->type,
797 def->key_size,
798 def->value_size,
799 def->max_entries);
800 if (*pfd < 0) {
801 size_t j;
802 int err = *pfd;
803
804 pr_warning("failed to create map: %s\n",
805 strerror(errno));
806 for (j = 0; j < i; j++)
807 zclose(obj->maps[j].fd);
808 return err;
809 }
810 pr_debug("create map: fd=%d\n", *pfd);
811 }
812
813 return 0;
814 }
815
816 static int
817 bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
818 {
819 int i;
820
821 if (!prog || !prog->reloc_desc)
822 return 0;
823
824 for (i = 0; i < prog->nr_reloc; i++) {
825 int insn_idx, map_idx;
826 struct bpf_insn *insns = prog->insns;
827
828 insn_idx = prog->reloc_desc[i].insn_idx;
829 map_idx = prog->reloc_desc[i].map_idx;
830
831 if (insn_idx >= (int)prog->insns_cnt) {
832 pr_warning("relocation out of range: '%s'\n",
833 prog->section_name);
834 return -LIBBPF_ERRNO__RELOC;
835 }
836 insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
837 insns[insn_idx].imm = obj->maps[map_idx].fd;
838 }
839
840 zfree(&prog->reloc_desc);
841 prog->nr_reloc = 0;
842 return 0;
843 }
844
845
846 static int
847 bpf_object__relocate(struct bpf_object *obj)
848 {
849 struct bpf_program *prog;
850 size_t i;
851 int err;
852
853 for (i = 0; i < obj->nr_programs; i++) {
854 prog = &obj->programs[i];
855
856 err = bpf_program__relocate(prog, obj);
857 if (err) {
858 pr_warning("failed to relocate '%s'\n",
859 prog->section_name);
860 return err;
861 }
862 }
863 return 0;
864 }
865
866 static int bpf_object__collect_reloc(struct bpf_object *obj)
867 {
868 int i, err;
869
870 if (!obj_elf_valid(obj)) {
871 pr_warning("Internal error: elf object is closed\n");
872 return -LIBBPF_ERRNO__INTERNAL;
873 }
874
875 for (i = 0; i < obj->efile.nr_reloc; i++) {
876 GElf_Shdr *shdr = &obj->efile.reloc[i].shdr;
877 Elf_Data *data = obj->efile.reloc[i].data;
878 int idx = shdr->sh_info;
879 struct bpf_program *prog;
880 size_t nr_maps = obj->nr_maps;
881
882 if (shdr->sh_type != SHT_REL) {
883 pr_warning("internal error at %d\n", __LINE__);
884 return -LIBBPF_ERRNO__INTERNAL;
885 }
886
887 prog = bpf_object__find_prog_by_idx(obj, idx);
888 if (!prog) {
889 pr_warning("relocation failed: no %d section\n",
890 idx);
891 return -LIBBPF_ERRNO__RELOC;
892 }
893
894 err = bpf_program__collect_reloc(prog, nr_maps,
895 shdr, data,
896 obj->efile.symbols,
897 obj->efile.maps_shndx);
898 if (err)
899 return err;
900 }
901 return 0;
902 }
903
904 static int
905 load_program(enum bpf_prog_type type, struct bpf_insn *insns,
906 int insns_cnt, char *license, u32 kern_version, int *pfd)
907 {
908 int ret;
909 char *log_buf;
910
911 if (!insns || !insns_cnt)
912 return -EINVAL;
913
914 log_buf = malloc(BPF_LOG_BUF_SIZE);
915 if (!log_buf)
916 pr_warning("Alloc log buffer for bpf loader error, continue without log\n");
917
918 ret = bpf_load_program(type, insns, insns_cnt, license,
919 kern_version, log_buf, BPF_LOG_BUF_SIZE);
920
921 if (ret >= 0) {
922 *pfd = ret;
923 ret = 0;
924 goto out;
925 }
926
927 ret = -LIBBPF_ERRNO__LOAD;
928 pr_warning("load bpf program failed: %s\n", strerror(errno));
929
930 if (log_buf && log_buf[0] != '\0') {
931 ret = -LIBBPF_ERRNO__VERIFY;
932 pr_warning("-- BEGIN DUMP LOG ---\n");
933 pr_warning("\n%s\n", log_buf);
934 pr_warning("-- END LOG --\n");
935 } else if (insns_cnt >= BPF_MAXINSNS) {
936 pr_warning("Program too large (%d insns), at most %d insns\n",
937 insns_cnt, BPF_MAXINSNS);
938 ret = -LIBBPF_ERRNO__PROG2BIG;
939 } else {
940 /* Wrong program type? */
941 if (type != BPF_PROG_TYPE_KPROBE) {
942 int fd;
943
944 fd = bpf_load_program(BPF_PROG_TYPE_KPROBE, insns,
945 insns_cnt, license, kern_version,
946 NULL, 0);
947 if (fd >= 0) {
948 close(fd);
949 ret = -LIBBPF_ERRNO__PROGTYPE;
950 goto out;
951 }
952 }
953
954 if (log_buf)
955 ret = -LIBBPF_ERRNO__KVER;
956 }
957
958 out:
959 free(log_buf);
960 return ret;
961 }
962
963 static int
964 bpf_program__load(struct bpf_program *prog,
965 char *license, u32 kern_version)
966 {
967 int err = 0, fd, i;
968
969 if (prog->instances.nr < 0 || !prog->instances.fds) {
970 if (prog->preprocessor) {
971 pr_warning("Internal error: can't load program '%s'\n",
972 prog->section_name);
973 return -LIBBPF_ERRNO__INTERNAL;
974 }
975
976 prog->instances.fds = malloc(sizeof(int));
977 if (!prog->instances.fds) {
978 pr_warning("Not enough memory for BPF fds\n");
979 return -ENOMEM;
980 }
981 prog->instances.nr = 1;
982 prog->instances.fds[0] = -1;
983 }
984
985 if (!prog->preprocessor) {
986 if (prog->instances.nr != 1) {
987 pr_warning("Program '%s' is inconsistent: nr(%d) != 1\n",
988 prog->section_name, prog->instances.nr);
989 }
990 err = load_program(prog->type, prog->insns, prog->insns_cnt,
991 license, kern_version, &fd);
992 if (!err)
993 prog->instances.fds[0] = fd;
994 goto out;
995 }
996
997 for (i = 0; i < prog->instances.nr; i++) {
998 struct bpf_prog_prep_result result;
999 bpf_program_prep_t preprocessor = prog->preprocessor;
1000
1001 bzero(&result, sizeof(result));
1002 err = preprocessor(prog, i, prog->insns,
1003 prog->insns_cnt, &result);
1004 if (err) {
1005 pr_warning("Preprocessing the %dth instance of program '%s' failed\n",
1006 i, prog->section_name);
1007 goto out;
1008 }
1009
1010 if (!result.new_insn_ptr || !result.new_insn_cnt) {
1011 pr_debug("Skip loading the %dth instance of program '%s'\n",
1012 i, prog->section_name);
1013 prog->instances.fds[i] = -1;
1014 if (result.pfd)
1015 *result.pfd = -1;
1016 continue;
1017 }
1018
1019 err = load_program(prog->type, result.new_insn_ptr,
1020 result.new_insn_cnt,
1021 license, kern_version, &fd);
1022
1023 if (err) {
1024 pr_warning("Loading the %dth instance of program '%s' failed\n",
1025 i, prog->section_name);
1026 goto out;
1027 }
1028
1029 if (result.pfd)
1030 *result.pfd = fd;
1031 prog->instances.fds[i] = fd;
1032 }
1033 out:
1034 if (err)
1035 pr_warning("failed to load program '%s'\n",
1036 prog->section_name);
1037 zfree(&prog->insns);
1038 prog->insns_cnt = 0;
1039 return err;
1040 }
1041
1042 static int
1043 bpf_object__load_progs(struct bpf_object *obj)
1044 {
1045 size_t i;
1046 int err;
1047
1048 for (i = 0; i < obj->nr_programs; i++) {
1049 err = bpf_program__load(&obj->programs[i],
1050 obj->license,
1051 obj->kern_version);
1052 if (err)
1053 return err;
1054 }
1055 return 0;
1056 }
1057
1058 static int bpf_object__validate(struct bpf_object *obj)
1059 {
1060 if (obj->kern_version == 0) {
1061 pr_warning("%s doesn't provide kernel version\n",
1062 obj->path);
1063 return -LIBBPF_ERRNO__KVERSION;
1064 }
1065 return 0;
1066 }
1067
1068 static struct bpf_object *
1069 __bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz)
1070 {
1071 struct bpf_object *obj;
1072 int err;
1073
1074 if (elf_version(EV_CURRENT) == EV_NONE) {
1075 pr_warning("failed to init libelf for %s\n", path);
1076 return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
1077 }
1078
1079 obj = bpf_object__new(path, obj_buf, obj_buf_sz);
1080 if (IS_ERR(obj))
1081 return obj;
1082
1083 CHECK_ERR(bpf_object__elf_init(obj), err, out);
1084 CHECK_ERR(bpf_object__check_endianness(obj), err, out);
1085 CHECK_ERR(bpf_object__elf_collect(obj), err, out);
1086 CHECK_ERR(bpf_object__collect_reloc(obj), err, out);
1087 CHECK_ERR(bpf_object__validate(obj), err, out);
1088
1089 bpf_object__elf_finish(obj);
1090 return obj;
1091 out:
1092 bpf_object__close(obj);
1093 return ERR_PTR(err);
1094 }
1095
1096 struct bpf_object *bpf_object__open(const char *path)
1097 {
1098 /* param validation */
1099 if (!path)
1100 return NULL;
1101
1102 pr_debug("loading %s\n", path);
1103
1104 return __bpf_object__open(path, NULL, 0);
1105 }
1106
1107 struct bpf_object *bpf_object__open_buffer(void *obj_buf,
1108 size_t obj_buf_sz,
1109 const char *name)
1110 {
1111 char tmp_name[64];
1112
1113 /* param validation */
1114 if (!obj_buf || obj_buf_sz <= 0)
1115 return NULL;
1116
1117 if (!name) {
1118 snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
1119 (unsigned long)obj_buf,
1120 (unsigned long)obj_buf_sz);
1121 tmp_name[sizeof(tmp_name) - 1] = '\0';
1122 name = tmp_name;
1123 }
1124 pr_debug("loading object '%s' from buffer\n",
1125 name);
1126
1127 return __bpf_object__open(name, obj_buf, obj_buf_sz);
1128 }
1129
1130 int bpf_object__unload(struct bpf_object *obj)
1131 {
1132 size_t i;
1133
1134 if (!obj)
1135 return -EINVAL;
1136
1137 for (i = 0; i < obj->nr_maps; i++)
1138 zclose(obj->maps[i].fd);
1139
1140 for (i = 0; i < obj->nr_programs; i++)
1141 bpf_program__unload(&obj->programs[i]);
1142
1143 return 0;
1144 }
1145
1146 int bpf_object__load(struct bpf_object *obj)
1147 {
1148 int err;
1149
1150 if (!obj)
1151 return -EINVAL;
1152
1153 if (obj->loaded) {
1154 pr_warning("object should not be loaded twice\n");
1155 return -EINVAL;
1156 }
1157
1158 obj->loaded = true;
1159
1160 CHECK_ERR(bpf_object__create_maps(obj), err, out);
1161 CHECK_ERR(bpf_object__relocate(obj), err, out);
1162 CHECK_ERR(bpf_object__load_progs(obj), err, out);
1163
1164 return 0;
1165 out:
1166 bpf_object__unload(obj);
1167 pr_warning("failed to load object '%s'\n", obj->path);
1168 return err;
1169 }
1170
1171 void bpf_object__close(struct bpf_object *obj)
1172 {
1173 size_t i;
1174
1175 if (!obj)
1176 return;
1177
1178 bpf_object__elf_finish(obj);
1179 bpf_object__unload(obj);
1180
1181 for (i = 0; i < obj->nr_maps; i++) {
1182 zfree(&obj->maps[i].name);
1183 if (obj->maps[i].clear_priv)
1184 obj->maps[i].clear_priv(&obj->maps[i],
1185 obj->maps[i].priv);
1186 obj->maps[i].priv = NULL;
1187 obj->maps[i].clear_priv = NULL;
1188 }
1189 zfree(&obj->maps);
1190 obj->nr_maps = 0;
1191
1192 if (obj->programs && obj->nr_programs) {
1193 for (i = 0; i < obj->nr_programs; i++)
1194 bpf_program__exit(&obj->programs[i]);
1195 }
1196 zfree(&obj->programs);
1197
1198 list_del(&obj->list);
1199 free(obj);
1200 }
1201
1202 struct bpf_object *
1203 bpf_object__next(struct bpf_object *prev)
1204 {
1205 struct bpf_object *next;
1206
1207 if (!prev)
1208 next = list_first_entry(&bpf_objects_list,
1209 struct bpf_object,
1210 list);
1211 else
1212 next = list_next_entry(prev, list);
1213
1214 /* Empty list is noticed here so don't need checking on entry. */
1215 if (&next->list == &bpf_objects_list)
1216 return NULL;
1217
1218 return next;
1219 }
1220
1221 const char *bpf_object__name(struct bpf_object *obj)
1222 {
1223 return obj ? obj->path : ERR_PTR(-EINVAL);
1224 }
1225
1226 unsigned int bpf_object__kversion(struct bpf_object *obj)
1227 {
1228 return obj ? obj->kern_version : 0;
1229 }
1230
1231 struct bpf_program *
1232 bpf_program__next(struct bpf_program *prev, struct bpf_object *obj)
1233 {
1234 size_t idx;
1235
1236 if (!obj->programs)
1237 return NULL;
1238 /* First handler */
1239 if (prev == NULL)
1240 return &obj->programs[0];
1241
1242 if (prev->obj != obj) {
1243 pr_warning("error: program handler doesn't match object\n");
1244 return NULL;
1245 }
1246
1247 idx = (prev - obj->programs) + 1;
1248 if (idx >= obj->nr_programs)
1249 return NULL;
1250 return &obj->programs[idx];
1251 }
1252
1253 int bpf_program__set_priv(struct bpf_program *prog, void *priv,
1254 bpf_program_clear_priv_t clear_priv)
1255 {
1256 if (prog->priv && prog->clear_priv)
1257 prog->clear_priv(prog, prog->priv);
1258
1259 prog->priv = priv;
1260 prog->clear_priv = clear_priv;
1261 return 0;
1262 }
1263
1264 void *bpf_program__priv(struct bpf_program *prog)
1265 {
1266 return prog ? prog->priv : ERR_PTR(-EINVAL);
1267 }
1268
1269 const char *bpf_program__title(struct bpf_program *prog, bool needs_copy)
1270 {
1271 const char *title;
1272
1273 title = prog->section_name;
1274 if (needs_copy) {
1275 title = strdup(title);
1276 if (!title) {
1277 pr_warning("failed to strdup program title\n");
1278 return ERR_PTR(-ENOMEM);
1279 }
1280 }
1281
1282 return title;
1283 }
1284
1285 int bpf_program__fd(struct bpf_program *prog)
1286 {
1287 return bpf_program__nth_fd(prog, 0);
1288 }
1289
1290 int bpf_program__set_prep(struct bpf_program *prog, int nr_instances,
1291 bpf_program_prep_t prep)
1292 {
1293 int *instances_fds;
1294
1295 if (nr_instances <= 0 || !prep)
1296 return -EINVAL;
1297
1298 if (prog->instances.nr > 0 || prog->instances.fds) {
1299 pr_warning("Can't set pre-processor after loading\n");
1300 return -EINVAL;
1301 }
1302
1303 instances_fds = malloc(sizeof(int) * nr_instances);
1304 if (!instances_fds) {
1305 pr_warning("alloc memory failed for fds\n");
1306 return -ENOMEM;
1307 }
1308
1309 /* fill all fd with -1 */
1310 memset(instances_fds, -1, sizeof(int) * nr_instances);
1311
1312 prog->instances.nr = nr_instances;
1313 prog->instances.fds = instances_fds;
1314 prog->preprocessor = prep;
1315 return 0;
1316 }
1317
1318 int bpf_program__nth_fd(struct bpf_program *prog, int n)
1319 {
1320 int fd;
1321
1322 if (n >= prog->instances.nr || n < 0) {
1323 pr_warning("Can't get the %dth fd from program %s: only %d instances\n",
1324 n, prog->section_name, prog->instances.nr);
1325 return -EINVAL;
1326 }
1327
1328 fd = prog->instances.fds[n];
1329 if (fd < 0) {
1330 pr_warning("%dth instance of program '%s' is invalid\n",
1331 n, prog->section_name);
1332 return -ENOENT;
1333 }
1334
1335 return fd;
1336 }
1337
1338 static void bpf_program__set_type(struct bpf_program *prog,
1339 enum bpf_prog_type type)
1340 {
1341 prog->type = type;
1342 }
1343
1344 int bpf_program__set_tracepoint(struct bpf_program *prog)
1345 {
1346 if (!prog)
1347 return -EINVAL;
1348 bpf_program__set_type(prog, BPF_PROG_TYPE_TRACEPOINT);
1349 return 0;
1350 }
1351
1352 int bpf_program__set_kprobe(struct bpf_program *prog)
1353 {
1354 if (!prog)
1355 return -EINVAL;
1356 bpf_program__set_type(prog, BPF_PROG_TYPE_KPROBE);
1357 return 0;
1358 }
1359
1360 static bool bpf_program__is_type(struct bpf_program *prog,
1361 enum bpf_prog_type type)
1362 {
1363 return prog ? (prog->type == type) : false;
1364 }
1365
1366 bool bpf_program__is_tracepoint(struct bpf_program *prog)
1367 {
1368 return bpf_program__is_type(prog, BPF_PROG_TYPE_TRACEPOINT);
1369 }
1370
1371 bool bpf_program__is_kprobe(struct bpf_program *prog)
1372 {
1373 return bpf_program__is_type(prog, BPF_PROG_TYPE_KPROBE);
1374 }
1375
1376 int bpf_map__fd(struct bpf_map *map)
1377 {
1378 return map ? map->fd : -EINVAL;
1379 }
1380
1381 const struct bpf_map_def *bpf_map__def(struct bpf_map *map)
1382 {
1383 return map ? &map->def : ERR_PTR(-EINVAL);
1384 }
1385
1386 const char *bpf_map__name(struct bpf_map *map)
1387 {
1388 return map ? map->name : NULL;
1389 }
1390
1391 int bpf_map__set_priv(struct bpf_map *map, void *priv,
1392 bpf_map_clear_priv_t clear_priv)
1393 {
1394 if (!map)
1395 return -EINVAL;
1396
1397 if (map->priv) {
1398 if (map->clear_priv)
1399 map->clear_priv(map, map->priv);
1400 }
1401
1402 map->priv = priv;
1403 map->clear_priv = clear_priv;
1404 return 0;
1405 }
1406
1407 void *bpf_map__priv(struct bpf_map *map)
1408 {
1409 return map ? map->priv : ERR_PTR(-EINVAL);
1410 }
1411
1412 struct bpf_map *
1413 bpf_map__next(struct bpf_map *prev, struct bpf_object *obj)
1414 {
1415 size_t idx;
1416 struct bpf_map *s, *e;
1417
1418 if (!obj || !obj->maps)
1419 return NULL;
1420
1421 s = obj->maps;
1422 e = obj->maps + obj->nr_maps;
1423
1424 if (prev == NULL)
1425 return s;
1426
1427 if ((prev < s) || (prev >= e)) {
1428 pr_warning("error in %s: map handler doesn't belong to object\n",
1429 __func__);
1430 return NULL;
1431 }
1432
1433 idx = (prev - obj->maps) + 1;
1434 if (idx >= obj->nr_maps)
1435 return NULL;
1436 return &obj->maps[idx];
1437 }
1438
1439 struct bpf_map *
1440 bpf_object__find_map_by_name(struct bpf_object *obj, const char *name)
1441 {
1442 struct bpf_map *pos;
1443
1444 bpf_map__for_each(pos, obj) {
1445 if (pos->name && !strcmp(pos->name, name))
1446 return pos;
1447 }
1448 return NULL;
1449 }
Linux kernel - Deliverables
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