GNU Linux-libre 5.10.217-gnu1
[releases.git] / tools / bpf / resolve_btfids / main.c
1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
2
3 /*
4  * resolve_btfids scans Elf object for .BTF_ids section and resolves
5  * its symbols with BTF ID values.
6  *
7  * Each symbol points to 4 bytes data and is expected to have
8  * following name syntax:
9  *
10  * __BTF_ID__<type>__<symbol>[__<id>]
11  *
12  * type is:
13  *
14  *   func    - lookup BTF_KIND_FUNC symbol with <symbol> name
15  *             and store its ID into the data:
16  *
17  *             __BTF_ID__func__vfs_close__1:
18  *             .zero 4
19  *
20  *   struct  - lookup BTF_KIND_STRUCT symbol with <symbol> name
21  *             and store its ID into the data:
22  *
23  *             __BTF_ID__struct__sk_buff__1:
24  *             .zero 4
25  *
26  *   union   - lookup BTF_KIND_UNION symbol with <symbol> name
27  *             and store its ID into the data:
28  *
29  *             __BTF_ID__union__thread_union__1:
30  *             .zero 4
31  *
32  *   typedef - lookup BTF_KIND_TYPEDEF symbol with <symbol> name
33  *             and store its ID into the data:
34  *
35  *             __BTF_ID__typedef__pid_t__1:
36  *             .zero 4
37  *
38  *   set     - store symbol size into first 4 bytes and sort following
39  *             ID list
40  *
41  *             __BTF_ID__set__list:
42  *             .zero 4
43  *             list:
44  *             __BTF_ID__func__vfs_getattr__3:
45  *             .zero 4
46  *             __BTF_ID__func__vfs_fallocate__4:
47  *             .zero 4
48  */
49
50 #define  _GNU_SOURCE
51 #include <stdio.h>
52 #include <string.h>
53 #include <unistd.h>
54 #include <stdlib.h>
55 #include <libelf.h>
56 #include <gelf.h>
57 #include <sys/stat.h>
58 #include <fcntl.h>
59 #include <errno.h>
60 #include <linux/rbtree.h>
61 #include <linux/zalloc.h>
62 #include <linux/err.h>
63 #include <btf.h>
64 #include <libbpf.h>
65 #include <parse-options.h>
66
67 #define BTF_IDS_SECTION ".BTF_ids"
68 #define BTF_ID          "__BTF_ID__"
69
70 #define BTF_STRUCT      "struct"
71 #define BTF_UNION       "union"
72 #define BTF_TYPEDEF     "typedef"
73 #define BTF_FUNC        "func"
74 #define BTF_SET         "set"
75
76 #define ADDR_CNT        100
77
78 struct btf_id {
79         struct rb_node   rb_node;
80         char            *name;
81         union {
82                 int      id;
83                 int      cnt;
84         };
85         int              addr_cnt;
86         Elf64_Addr       addr[ADDR_CNT];
87 };
88
89 struct object {
90         const char *path;
91         const char *btf;
92
93         struct {
94                 int              fd;
95                 Elf             *elf;
96                 Elf_Data        *symbols;
97                 Elf_Data        *idlist;
98                 int              symbols_shndx;
99                 int              idlist_shndx;
100                 size_t           strtabidx;
101                 unsigned long    idlist_addr;
102         } efile;
103
104         struct rb_root  sets;
105         struct rb_root  structs;
106         struct rb_root  unions;
107         struct rb_root  typedefs;
108         struct rb_root  funcs;
109
110         int nr_funcs;
111         int nr_structs;
112         int nr_unions;
113         int nr_typedefs;
114 };
115
116 static int verbose;
117
118 int eprintf(int level, int var, const char *fmt, ...)
119 {
120         va_list args;
121         int ret;
122
123         if (var >= level) {
124                 va_start(args, fmt);
125                 ret = vfprintf(stderr, fmt, args);
126                 va_end(args);
127         }
128         return ret;
129 }
130
131 #ifndef pr_fmt
132 #define pr_fmt(fmt) fmt
133 #endif
134
135 #define pr_debug(fmt, ...) \
136         eprintf(1, verbose, pr_fmt(fmt), ##__VA_ARGS__)
137 #define pr_debugN(n, fmt, ...) \
138         eprintf(n, verbose, pr_fmt(fmt), ##__VA_ARGS__)
139 #define pr_debug2(fmt, ...) pr_debugN(2, pr_fmt(fmt), ##__VA_ARGS__)
140 #define pr_err(fmt, ...) \
141         eprintf(0, verbose, pr_fmt(fmt), ##__VA_ARGS__)
142
143 static bool is_btf_id(const char *name)
144 {
145         return name && !strncmp(name, BTF_ID, sizeof(BTF_ID) - 1);
146 }
147
148 static struct btf_id *btf_id__find(struct rb_root *root, const char *name)
149 {
150         struct rb_node *p = root->rb_node;
151         struct btf_id *id;
152         int cmp;
153
154         while (p) {
155                 id = rb_entry(p, struct btf_id, rb_node);
156                 cmp = strcmp(id->name, name);
157                 if (cmp < 0)
158                         p = p->rb_left;
159                 else if (cmp > 0)
160                         p = p->rb_right;
161                 else
162                         return id;
163         }
164         return NULL;
165 }
166
167 static struct btf_id*
168 btf_id__add(struct rb_root *root, char *name, bool unique)
169 {
170         struct rb_node **p = &root->rb_node;
171         struct rb_node *parent = NULL;
172         struct btf_id *id;
173         int cmp;
174
175         while (*p != NULL) {
176                 parent = *p;
177                 id = rb_entry(parent, struct btf_id, rb_node);
178                 cmp = strcmp(id->name, name);
179                 if (cmp < 0)
180                         p = &(*p)->rb_left;
181                 else if (cmp > 0)
182                         p = &(*p)->rb_right;
183                 else
184                         return unique ? NULL : id;
185         }
186
187         id = zalloc(sizeof(*id));
188         if (id) {
189                 pr_debug("adding symbol %s\n", name);
190                 id->name = name;
191                 rb_link_node(&id->rb_node, parent, p);
192                 rb_insert_color(&id->rb_node, root);
193         }
194         return id;
195 }
196
197 static char *get_id(const char *prefix_end)
198 {
199         /*
200          * __BTF_ID__func__vfs_truncate__0
201          * prefix_end =  ^
202          * pos        =    ^
203          */
204         int len = strlen(prefix_end);
205         int pos = sizeof("__") - 1;
206         char *p, *id;
207
208         if (pos >= len)
209                 return NULL;
210
211         id = strdup(prefix_end + pos);
212         if (id) {
213                 /*
214                  * __BTF_ID__func__vfs_truncate__0
215                  * id =            ^
216                  *
217                  * cut the unique id part
218                  */
219                 p = strrchr(id, '_');
220                 p--;
221                 if (*p != '_') {
222                         free(id);
223                         return NULL;
224                 }
225                 *p = '\0';
226         }
227         return id;
228 }
229
230 static struct btf_id *add_set(struct object *obj, char *name)
231 {
232         /*
233          * __BTF_ID__set__name
234          * name =    ^
235          * id   =         ^
236          */
237         char *id = name + sizeof(BTF_SET "__") - 1;
238         int len = strlen(name);
239
240         if (id >= name + len) {
241                 pr_err("FAILED to parse set name: %s\n", name);
242                 return NULL;
243         }
244
245         return btf_id__add(&obj->sets, id, true);
246 }
247
248 static struct btf_id *add_symbol(struct rb_root *root, char *name, size_t size)
249 {
250         char *id;
251
252         id = get_id(name + size);
253         if (!id) {
254                 pr_err("FAILED to parse symbol name: %s\n", name);
255                 return NULL;
256         }
257
258         return btf_id__add(root, id, false);
259 }
260
261 /* Older libelf.h and glibc elf.h might not yet define the ELF compression types. */
262 #ifndef SHF_COMPRESSED
263 #define SHF_COMPRESSED (1 << 11) /* Section with compressed data. */
264 #endif
265
266 /*
267  * The data of compressed section should be aligned to 4
268  * (for 32bit) or 8 (for 64 bit) bytes. The binutils ld
269  * sets sh_addralign to 1, which makes libelf fail with
270  * misaligned section error during the update:
271  *    FAILED elf_update(WRITE): invalid section alignment
272  *
273  * While waiting for ld fix, we fix the compressed sections
274  * sh_addralign value manualy.
275  */
276 static int compressed_section_fix(Elf *elf, Elf_Scn *scn, GElf_Shdr *sh)
277 {
278         int expected = gelf_getclass(elf) == ELFCLASS32 ? 4 : 8;
279
280         if (!(sh->sh_flags & SHF_COMPRESSED))
281                 return 0;
282
283         if (sh->sh_addralign == expected)
284                 return 0;
285
286         pr_debug2(" - fixing wrong alignment sh_addralign %u, expected %u\n",
287                   sh->sh_addralign, expected);
288
289         sh->sh_addralign = expected;
290
291         if (gelf_update_shdr(scn, sh) == 0) {
292                 printf("FAILED cannot update section header: %s\n",
293                         elf_errmsg(-1));
294                 return -1;
295         }
296         return 0;
297 }
298
299 static int elf_collect(struct object *obj)
300 {
301         Elf_Scn *scn = NULL;
302         size_t shdrstrndx;
303         int idx = 0;
304         Elf *elf;
305         int fd;
306
307         fd = open(obj->path, O_RDWR, 0666);
308         if (fd == -1) {
309                 pr_err("FAILED cannot open %s: %s\n",
310                         obj->path, strerror(errno));
311                 return -1;
312         }
313
314         elf_version(EV_CURRENT);
315
316         elf = elf_begin(fd, ELF_C_RDWR_MMAP, NULL);
317         if (!elf) {
318                 pr_err("FAILED cannot create ELF descriptor: %s\n",
319                         elf_errmsg(-1));
320                 return -1;
321         }
322
323         obj->efile.fd  = fd;
324         obj->efile.elf = elf;
325
326         elf_flagelf(elf, ELF_C_SET, ELF_F_LAYOUT);
327
328         if (elf_getshdrstrndx(elf, &shdrstrndx) != 0) {
329                 pr_err("FAILED cannot get shdr str ndx\n");
330                 return -1;
331         }
332
333         /*
334          * Scan all the elf sections and look for save data
335          * from .BTF_ids section and symbols.
336          */
337         while ((scn = elf_nextscn(elf, scn)) != NULL) {
338                 Elf_Data *data;
339                 GElf_Shdr sh;
340                 char *name;
341
342                 idx++;
343                 if (gelf_getshdr(scn, &sh) != &sh) {
344                         pr_err("FAILED get section(%d) header\n", idx);
345                         return -1;
346                 }
347
348                 name = elf_strptr(elf, shdrstrndx, sh.sh_name);
349                 if (!name) {
350                         pr_err("FAILED get section(%d) name\n", idx);
351                         return -1;
352                 }
353
354                 data = elf_getdata(scn, 0);
355                 if (!data) {
356                         pr_err("FAILED to get section(%d) data from %s\n",
357                                 idx, name);
358                         return -1;
359                 }
360
361                 pr_debug2("section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
362                           idx, name, (unsigned long) data->d_size,
363                           (int) sh.sh_link, (unsigned long) sh.sh_flags,
364                           (int) sh.sh_type);
365
366                 if (sh.sh_type == SHT_SYMTAB) {
367                         obj->efile.symbols       = data;
368                         obj->efile.symbols_shndx = idx;
369                         obj->efile.strtabidx     = sh.sh_link;
370                 } else if (!strcmp(name, BTF_IDS_SECTION)) {
371                         obj->efile.idlist       = data;
372                         obj->efile.idlist_shndx = idx;
373                         obj->efile.idlist_addr  = sh.sh_addr;
374                 }
375
376                 if (compressed_section_fix(elf, scn, &sh))
377                         return -1;
378         }
379
380         return 0;
381 }
382
383 static int symbols_collect(struct object *obj)
384 {
385         Elf_Scn *scn = NULL;
386         int n, i, err = 0;
387         GElf_Shdr sh;
388         char *name;
389
390         scn = elf_getscn(obj->efile.elf, obj->efile.symbols_shndx);
391         if (!scn)
392                 return -1;
393
394         if (gelf_getshdr(scn, &sh) != &sh)
395                 return -1;
396
397         n = sh.sh_size / sh.sh_entsize;
398
399         /*
400          * Scan symbols and look for the ones starting with
401          * __BTF_ID__* over .BTF_ids section.
402          */
403         for (i = 0; !err && i < n; i++) {
404                 char *tmp, *prefix;
405                 struct btf_id *id;
406                 GElf_Sym sym;
407                 int err = -1;
408
409                 if (!gelf_getsym(obj->efile.symbols, i, &sym))
410                         return -1;
411
412                 if (sym.st_shndx != obj->efile.idlist_shndx)
413                         continue;
414
415                 name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
416                                   sym.st_name);
417
418                 if (!is_btf_id(name))
419                         continue;
420
421                 /*
422                  * __BTF_ID__TYPE__vfs_truncate__0
423                  * prefix =  ^
424                  */
425                 prefix = name + sizeof(BTF_ID) - 1;
426
427                 /* struct */
428                 if (!strncmp(prefix, BTF_STRUCT, sizeof(BTF_STRUCT) - 1)) {
429                         obj->nr_structs++;
430                         id = add_symbol(&obj->structs, prefix, sizeof(BTF_STRUCT) - 1);
431                 /* union  */
432                 } else if (!strncmp(prefix, BTF_UNION, sizeof(BTF_UNION) - 1)) {
433                         obj->nr_unions++;
434                         id = add_symbol(&obj->unions, prefix, sizeof(BTF_UNION) - 1);
435                 /* typedef */
436                 } else if (!strncmp(prefix, BTF_TYPEDEF, sizeof(BTF_TYPEDEF) - 1)) {
437                         obj->nr_typedefs++;
438                         id = add_symbol(&obj->typedefs, prefix, sizeof(BTF_TYPEDEF) - 1);
439                 /* func */
440                 } else if (!strncmp(prefix, BTF_FUNC, sizeof(BTF_FUNC) - 1)) {
441                         obj->nr_funcs++;
442                         id = add_symbol(&obj->funcs, prefix, sizeof(BTF_FUNC) - 1);
443                 /* set */
444                 } else if (!strncmp(prefix, BTF_SET, sizeof(BTF_SET) - 1)) {
445                         id = add_set(obj, prefix);
446                         /*
447                          * SET objects store list's count, which is encoded
448                          * in symbol's size, together with 'cnt' field hence
449                          * that - 1.
450                          */
451                         if (id)
452                                 id->cnt = sym.st_size / sizeof(int) - 1;
453                 } else {
454                         pr_err("FAILED unsupported prefix %s\n", prefix);
455                         return -1;
456                 }
457
458                 if (!id)
459                         return -ENOMEM;
460
461                 if (id->addr_cnt >= ADDR_CNT) {
462                         pr_err("FAILED symbol %s crossed the number of allowed lists",
463                                 id->name);
464                         return -1;
465                 }
466                 id->addr[id->addr_cnt++] = sym.st_value;
467         }
468
469         return 0;
470 }
471
472 static int symbols_resolve(struct object *obj)
473 {
474         int nr_typedefs = obj->nr_typedefs;
475         int nr_structs  = obj->nr_structs;
476         int nr_unions   = obj->nr_unions;
477         int nr_funcs    = obj->nr_funcs;
478         int err, type_id;
479         struct btf *btf;
480         __u32 nr;
481
482         btf = btf__parse(obj->btf ?: obj->path, NULL);
483         err = libbpf_get_error(btf);
484         if (err) {
485                 pr_err("FAILED: load BTF from %s: %s",
486                         obj->path, strerror(err));
487                 return -1;
488         }
489
490         err = -1;
491         nr  = btf__get_nr_types(btf);
492
493         /*
494          * Iterate all the BTF types and search for collected symbol IDs.
495          */
496         for (type_id = 1; type_id <= nr; type_id++) {
497                 const struct btf_type *type;
498                 struct rb_root *root;
499                 struct btf_id *id;
500                 const char *str;
501                 int *nr;
502
503                 type = btf__type_by_id(btf, type_id);
504                 if (!type) {
505                         pr_err("FAILED: malformed BTF, can't resolve type for ID %d\n",
506                                 type_id);
507                         goto out;
508                 }
509
510                 if (btf_is_func(type) && nr_funcs) {
511                         nr   = &nr_funcs;
512                         root = &obj->funcs;
513                 } else if (btf_is_struct(type) && nr_structs) {
514                         nr   = &nr_structs;
515                         root = &obj->structs;
516                 } else if (btf_is_union(type) && nr_unions) {
517                         nr   = &nr_unions;
518                         root = &obj->unions;
519                 } else if (btf_is_typedef(type) && nr_typedefs) {
520                         nr   = &nr_typedefs;
521                         root = &obj->typedefs;
522                 } else
523                         continue;
524
525                 str = btf__name_by_offset(btf, type->name_off);
526                 if (!str) {
527                         pr_err("FAILED: malformed BTF, can't resolve name for ID %d\n",
528                                 type_id);
529                         goto out;
530                 }
531
532                 id = btf_id__find(root, str);
533                 if (id) {
534                         id->id = type_id;
535                         (*nr)--;
536                 }
537         }
538
539         err = 0;
540 out:
541         btf__free(btf);
542         return err;
543 }
544
545 static int id_patch(struct object *obj, struct btf_id *id)
546 {
547         Elf_Data *data = obj->efile.idlist;
548         int *ptr = data->d_buf;
549         int i;
550
551         if (!id->id) {
552                 pr_err("FAILED unresolved symbol %s\n", id->name);
553                 return -EINVAL;
554         }
555
556         for (i = 0; i < id->addr_cnt; i++) {
557                 unsigned long addr = id->addr[i];
558                 unsigned long idx = addr - obj->efile.idlist_addr;
559
560                 pr_debug("patching addr %5lu: ID %7d [%s]\n",
561                          idx, id->id, id->name);
562
563                 if (idx >= data->d_size) {
564                         pr_err("FAILED patching index %lu out of bounds %lu\n",
565                                 idx, data->d_size);
566                         return -1;
567                 }
568
569                 idx = idx / sizeof(int);
570                 ptr[idx] = id->id;
571         }
572
573         return 0;
574 }
575
576 static int __symbols_patch(struct object *obj, struct rb_root *root)
577 {
578         struct rb_node *next;
579         struct btf_id *id;
580
581         next = rb_first(root);
582         while (next) {
583                 id = rb_entry(next, struct btf_id, rb_node);
584
585                 if (id_patch(obj, id))
586                         return -1;
587
588                 next = rb_next(next);
589         }
590         return 0;
591 }
592
593 static int cmp_id(const void *pa, const void *pb)
594 {
595         const int *a = pa, *b = pb;
596
597         return *a - *b;
598 }
599
600 static int sets_patch(struct object *obj)
601 {
602         Elf_Data *data = obj->efile.idlist;
603         int *ptr = data->d_buf;
604         struct rb_node *next;
605
606         next = rb_first(&obj->sets);
607         while (next) {
608                 unsigned long addr, idx;
609                 struct btf_id *id;
610                 int *base;
611                 int cnt;
612
613                 id   = rb_entry(next, struct btf_id, rb_node);
614                 addr = id->addr[0];
615                 idx  = addr - obj->efile.idlist_addr;
616
617                 /* sets are unique */
618                 if (id->addr_cnt != 1) {
619                         pr_err("FAILED malformed data for set '%s'\n",
620                                 id->name);
621                         return -1;
622                 }
623
624                 idx = idx / sizeof(int);
625                 base = &ptr[idx] + 1;
626                 cnt = ptr[idx];
627
628                 pr_debug("sorting  addr %5lu: cnt %6d [%s]\n",
629                          (idx + 1) * sizeof(int), cnt, id->name);
630
631                 qsort(base, cnt, sizeof(int), cmp_id);
632
633                 next = rb_next(next);
634         }
635         return 0;
636 }
637
638 static int symbols_patch(struct object *obj)
639 {
640         int err;
641
642         if (__symbols_patch(obj, &obj->structs)  ||
643             __symbols_patch(obj, &obj->unions)   ||
644             __symbols_patch(obj, &obj->typedefs) ||
645             __symbols_patch(obj, &obj->funcs)    ||
646             __symbols_patch(obj, &obj->sets))
647                 return -1;
648
649         if (sets_patch(obj))
650                 return -1;
651
652         /* Set type to ensure endian translation occurs. */
653         obj->efile.idlist->d_type = ELF_T_WORD;
654
655         elf_flagdata(obj->efile.idlist, ELF_C_SET, ELF_F_DIRTY);
656
657         err = elf_update(obj->efile.elf, ELF_C_WRITE);
658         if (err < 0) {
659                 pr_err("FAILED elf_update(WRITE): %s\n",
660                         elf_errmsg(-1));
661         }
662
663         pr_debug("update %s for %s\n",
664                  err >= 0 ? "ok" : "failed", obj->path);
665         return err < 0 ? -1 : 0;
666 }
667
668 static const char * const resolve_btfids_usage[] = {
669         "resolve_btfids [<options>] <ELF object>",
670         NULL
671 };
672
673 int main(int argc, const char **argv)
674 {
675         bool no_fail = false;
676         struct object obj = {
677                 .efile = {
678                         .idlist_shndx  = -1,
679                         .symbols_shndx = -1,
680                 },
681                 .structs  = RB_ROOT,
682                 .unions   = RB_ROOT,
683                 .typedefs = RB_ROOT,
684                 .funcs    = RB_ROOT,
685                 .sets     = RB_ROOT,
686         };
687         struct option btfid_options[] = {
688                 OPT_INCR('v', "verbose", &verbose,
689                          "be more verbose (show errors, etc)"),
690                 OPT_STRING(0, "btf", &obj.btf, "BTF data",
691                            "BTF data"),
692                 OPT_BOOLEAN(0, "no-fail", &no_fail,
693                            "do not fail if " BTF_IDS_SECTION " section is not found"),
694                 OPT_END()
695         };
696         int err = -1;
697
698         argc = parse_options(argc, argv, btfid_options, resolve_btfids_usage,
699                              PARSE_OPT_STOP_AT_NON_OPTION);
700         if (argc != 1)
701                 usage_with_options(resolve_btfids_usage, btfid_options);
702
703         obj.path = argv[0];
704
705         if (elf_collect(&obj))
706                 goto out;
707
708         /*
709          * We did not find .BTF_ids section or symbols section,
710          * nothing to do..
711          */
712         if (obj.efile.idlist_shndx == -1 ||
713             obj.efile.symbols_shndx == -1) {
714                 if (no_fail)
715                         return 0;
716                 pr_err("FAILED to find needed sections\n");
717                 return -1;
718         }
719
720         if (symbols_collect(&obj))
721                 goto out;
722
723         if (symbols_resolve(&obj))
724                 goto out;
725
726         if (symbols_patch(&obj))
727                 goto out;
728
729         err = 0;
730 out:
731         if (obj.efile.elf)
732                 elf_end(obj.efile.elf);
733         close(obj.efile.fd);
734         return err;
735 }