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TOMOYO Linux Cross Reference
Linux/tools/perf/util/symbol-elf.c

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  1 #include <fcntl.h>
  2 #include <stdio.h>
  3 #include <errno.h>
  4 #include <string.h>
  5 #include <unistd.h>
  6 #include <inttypes.h>
  7 
  8 #include "symbol.h"
  9 #include "demangle-java.h"
 10 #include "demangle-rust.h"
 11 #include "machine.h"
 12 #include "vdso.h"
 13 #include <symbol/kallsyms.h>
 14 #include "debug.h"
 15 
 16 #ifndef EM_AARCH64
 17 #define EM_AARCH64      183  /* ARM 64 bit */
 18 #endif
 19 
 20 typedef Elf64_Nhdr GElf_Nhdr;
 21 
 22 #ifdef HAVE_CPLUS_DEMANGLE_SUPPORT
 23 extern char *cplus_demangle(const char *, int);
 24 
 25 static inline char *bfd_demangle(void __maybe_unused *v, const char *c, int i)
 26 {
 27         return cplus_demangle(c, i);
 28 }
 29 #else
 30 #ifdef NO_DEMANGLE
 31 static inline char *bfd_demangle(void __maybe_unused *v,
 32                                  const char __maybe_unused *c,
 33                                  int __maybe_unused i)
 34 {
 35         return NULL;
 36 }
 37 #else
 38 #define PACKAGE 'perf'
 39 #include <bfd.h>
 40 #endif
 41 #endif
 42 
 43 #ifndef HAVE_ELF_GETPHDRNUM_SUPPORT
 44 static int elf_getphdrnum(Elf *elf, size_t *dst)
 45 {
 46         GElf_Ehdr gehdr;
 47         GElf_Ehdr *ehdr;
 48 
 49         ehdr = gelf_getehdr(elf, &gehdr);
 50         if (!ehdr)
 51                 return -1;
 52 
 53         *dst = ehdr->e_phnum;
 54 
 55         return 0;
 56 }
 57 #endif
 58 
 59 #ifndef HAVE_ELF_GETSHDRSTRNDX_SUPPORT
 60 static int elf_getshdrstrndx(Elf *elf __maybe_unused, size_t *dst __maybe_unused)
 61 {
 62         pr_err("%s: update your libelf to > 0.140, this one lacks elf_getshdrstrndx().\n", __func__);
 63         return -1;
 64 }
 65 #endif
 66 
 67 #ifndef NT_GNU_BUILD_ID
 68 #define NT_GNU_BUILD_ID 3
 69 #endif
 70 
 71 /**
 72  * elf_symtab__for_each_symbol - iterate thru all the symbols
 73  *
 74  * @syms: struct elf_symtab instance to iterate
 75  * @idx: uint32_t idx
 76  * @sym: GElf_Sym iterator
 77  */
 78 #define elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) \
 79         for (idx = 0, gelf_getsym(syms, idx, &sym);\
 80              idx < nr_syms; \
 81              idx++, gelf_getsym(syms, idx, &sym))
 82 
 83 static inline uint8_t elf_sym__type(const GElf_Sym *sym)
 84 {
 85         return GELF_ST_TYPE(sym->st_info);
 86 }
 87 
 88 #ifndef STT_GNU_IFUNC
 89 #define STT_GNU_IFUNC 10
 90 #endif
 91 
 92 static inline int elf_sym__is_function(const GElf_Sym *sym)
 93 {
 94         return (elf_sym__type(sym) == STT_FUNC ||
 95                 elf_sym__type(sym) == STT_GNU_IFUNC) &&
 96                sym->st_name != 0 &&
 97                sym->st_shndx != SHN_UNDEF;
 98 }
 99 
100 static inline bool elf_sym__is_object(const GElf_Sym *sym)
101 {
102         return elf_sym__type(sym) == STT_OBJECT &&
103                 sym->st_name != 0 &&
104                 sym->st_shndx != SHN_UNDEF;
105 }
106 
107 static inline int elf_sym__is_label(const GElf_Sym *sym)
108 {
109         return elf_sym__type(sym) == STT_NOTYPE &&
110                 sym->st_name != 0 &&
111                 sym->st_shndx != SHN_UNDEF &&
112                 sym->st_shndx != SHN_ABS;
113 }
114 
115 static bool elf_sym__is_a(GElf_Sym *sym, enum map_type type)
116 {
117         switch (type) {
118         case MAP__FUNCTION:
119                 return elf_sym__is_function(sym);
120         case MAP__VARIABLE:
121                 return elf_sym__is_object(sym);
122         default:
123                 return false;
124         }
125 }
126 
127 static inline const char *elf_sym__name(const GElf_Sym *sym,
128                                         const Elf_Data *symstrs)
129 {
130         return symstrs->d_buf + sym->st_name;
131 }
132 
133 static inline const char *elf_sec__name(const GElf_Shdr *shdr,
134                                         const Elf_Data *secstrs)
135 {
136         return secstrs->d_buf + shdr->sh_name;
137 }
138 
139 static inline int elf_sec__is_text(const GElf_Shdr *shdr,
140                                         const Elf_Data *secstrs)
141 {
142         return strstr(elf_sec__name(shdr, secstrs), "text") != NULL;
143 }
144 
145 static inline bool elf_sec__is_data(const GElf_Shdr *shdr,
146                                     const Elf_Data *secstrs)
147 {
148         return strstr(elf_sec__name(shdr, secstrs), "data") != NULL;
149 }
150 
151 static bool elf_sec__is_a(GElf_Shdr *shdr, Elf_Data *secstrs,
152                           enum map_type type)
153 {
154         switch (type) {
155         case MAP__FUNCTION:
156                 return elf_sec__is_text(shdr, secstrs);
157         case MAP__VARIABLE:
158                 return elf_sec__is_data(shdr, secstrs);
159         default:
160                 return false;
161         }
162 }
163 
164 static size_t elf_addr_to_index(Elf *elf, GElf_Addr addr)
165 {
166         Elf_Scn *sec = NULL;
167         GElf_Shdr shdr;
168         size_t cnt = 1;
169 
170         while ((sec = elf_nextscn(elf, sec)) != NULL) {
171                 gelf_getshdr(sec, &shdr);
172 
173                 if ((addr >= shdr.sh_addr) &&
174                     (addr < (shdr.sh_addr + shdr.sh_size)))
175                         return cnt;
176 
177                 ++cnt;
178         }
179 
180         return -1;
181 }
182 
183 Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
184                              GElf_Shdr *shp, const char *name, size_t *idx)
185 {
186         Elf_Scn *sec = NULL;
187         size_t cnt = 1;
188 
189         /* Elf is corrupted/truncated, avoid calling elf_strptr. */
190         if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL))
191                 return NULL;
192 
193         while ((sec = elf_nextscn(elf, sec)) != NULL) {
194                 char *str;
195 
196                 gelf_getshdr(sec, shp);
197                 str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
198                 if (str && !strcmp(name, str)) {
199                         if (idx)
200                                 *idx = cnt;
201                         return sec;
202                 }
203                 ++cnt;
204         }
205 
206         return NULL;
207 }
208 
209 static bool want_demangle(bool is_kernel_sym)
210 {
211         return is_kernel_sym ? symbol_conf.demangle_kernel : symbol_conf.demangle;
212 }
213 
214 static char *demangle_sym(struct dso *dso, int kmodule, const char *elf_name)
215 {
216         int demangle_flags = verbose ? (DMGL_PARAMS | DMGL_ANSI) : DMGL_NO_OPTS;
217         char *demangled = NULL;
218 
219         /*
220          * We need to figure out if the object was created from C++ sources
221          * DWARF DW_compile_unit has this, but we don't always have access
222          * to it...
223          */
224         if (!want_demangle(dso->kernel || kmodule))
225             return demangled;
226 
227         demangled = bfd_demangle(NULL, elf_name, demangle_flags);
228         if (demangled == NULL)
229                 demangled = java_demangle_sym(elf_name, JAVA_DEMANGLE_NORET);
230         else if (rust_is_mangled(demangled))
231                 /*
232                     * Input to Rust demangling is the BFD-demangled
233                     * name which it Rust-demangles in place.
234                     */
235                 rust_demangle_sym(demangled);
236 
237         return demangled;
238 }
239 
240 #define elf_section__for_each_rel(reldata, pos, pos_mem, idx, nr_entries) \
241         for (idx = 0, pos = gelf_getrel(reldata, 0, &pos_mem); \
242              idx < nr_entries; \
243              ++idx, pos = gelf_getrel(reldata, idx, &pos_mem))
244 
245 #define elf_section__for_each_rela(reldata, pos, pos_mem, idx, nr_entries) \
246         for (idx = 0, pos = gelf_getrela(reldata, 0, &pos_mem); \
247              idx < nr_entries; \
248              ++idx, pos = gelf_getrela(reldata, idx, &pos_mem))
249 
250 /*
251  * We need to check if we have a .dynsym, so that we can handle the
252  * .plt, synthesizing its symbols, that aren't on the symtabs (be it
253  * .dynsym or .symtab).
254  * And always look at the original dso, not at debuginfo packages, that
255  * have the PLT data stripped out (shdr_rel_plt.sh_type == SHT_NOBITS).
256  */
257 int dso__synthesize_plt_symbols(struct dso *dso, struct symsrc *ss, struct map *map)
258 {
259         uint32_t nr_rel_entries, idx;
260         GElf_Sym sym;
261         u64 plt_offset;
262         GElf_Shdr shdr_plt;
263         struct symbol *f;
264         GElf_Shdr shdr_rel_plt, shdr_dynsym;
265         Elf_Data *reldata, *syms, *symstrs;
266         Elf_Scn *scn_plt_rel, *scn_symstrs, *scn_dynsym;
267         size_t dynsym_idx;
268         GElf_Ehdr ehdr;
269         char sympltname[1024];
270         Elf *elf;
271         int nr = 0, symidx, err = 0;
272 
273         if (!ss->dynsym)
274                 return 0;
275 
276         elf = ss->elf;
277         ehdr = ss->ehdr;
278 
279         scn_dynsym = ss->dynsym;
280         shdr_dynsym = ss->dynshdr;
281         dynsym_idx = ss->dynsym_idx;
282 
283         if (scn_dynsym == NULL)
284                 goto out_elf_end;
285 
286         scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
287                                           ".rela.plt", NULL);
288         if (scn_plt_rel == NULL) {
289                 scn_plt_rel = elf_section_by_name(elf, &ehdr, &shdr_rel_plt,
290                                                   ".rel.plt", NULL);
291                 if (scn_plt_rel == NULL)
292                         goto out_elf_end;
293         }
294 
295         err = -1;
296 
297         if (shdr_rel_plt.sh_link != dynsym_idx)
298                 goto out_elf_end;
299 
300         if (elf_section_by_name(elf, &ehdr, &shdr_plt, ".plt", NULL) == NULL)
301                 goto out_elf_end;
302 
303         /*
304          * Fetch the relocation section to find the idxes to the GOT
305          * and the symbols in the .dynsym they refer to.
306          */
307         reldata = elf_getdata(scn_plt_rel, NULL);
308         if (reldata == NULL)
309                 goto out_elf_end;
310 
311         syms = elf_getdata(scn_dynsym, NULL);
312         if (syms == NULL)
313                 goto out_elf_end;
314 
315         scn_symstrs = elf_getscn(elf, shdr_dynsym.sh_link);
316         if (scn_symstrs == NULL)
317                 goto out_elf_end;
318 
319         symstrs = elf_getdata(scn_symstrs, NULL);
320         if (symstrs == NULL)
321                 goto out_elf_end;
322 
323         if (symstrs->d_size == 0)
324                 goto out_elf_end;
325 
326         nr_rel_entries = shdr_rel_plt.sh_size / shdr_rel_plt.sh_entsize;
327         plt_offset = shdr_plt.sh_offset;
328 
329         if (shdr_rel_plt.sh_type == SHT_RELA) {
330                 GElf_Rela pos_mem, *pos;
331 
332                 elf_section__for_each_rela(reldata, pos, pos_mem, idx,
333                                            nr_rel_entries) {
334                         const char *elf_name = NULL;
335                         char *demangled = NULL;
336                         symidx = GELF_R_SYM(pos->r_info);
337                         plt_offset += shdr_plt.sh_entsize;
338                         gelf_getsym(syms, symidx, &sym);
339 
340                         elf_name = elf_sym__name(&sym, symstrs);
341                         demangled = demangle_sym(dso, 0, elf_name);
342                         if (demangled != NULL)
343                                 elf_name = demangled;
344                         snprintf(sympltname, sizeof(sympltname),
345                                  "%s@plt", elf_name);
346                         free(demangled);
347 
348                         f = symbol__new(plt_offset, shdr_plt.sh_entsize,
349                                         STB_GLOBAL, sympltname);
350                         if (!f)
351                                 goto out_elf_end;
352 
353                         symbols__insert(&dso->symbols[map->type], f);
354                         ++nr;
355                 }
356         } else if (shdr_rel_plt.sh_type == SHT_REL) {
357                 GElf_Rel pos_mem, *pos;
358                 elf_section__for_each_rel(reldata, pos, pos_mem, idx,
359                                           nr_rel_entries) {
360                         const char *elf_name = NULL;
361                         char *demangled = NULL;
362                         symidx = GELF_R_SYM(pos->r_info);
363                         plt_offset += shdr_plt.sh_entsize;
364                         gelf_getsym(syms, symidx, &sym);
365 
366                         elf_name = elf_sym__name(&sym, symstrs);
367                         demangled = demangle_sym(dso, 0, elf_name);
368                         if (demangled != NULL)
369                                 elf_name = demangled;
370                         snprintf(sympltname, sizeof(sympltname),
371                                  "%s@plt", elf_name);
372                         free(demangled);
373 
374                         f = symbol__new(plt_offset, shdr_plt.sh_entsize,
375                                         STB_GLOBAL, sympltname);
376                         if (!f)
377                                 goto out_elf_end;
378 
379                         symbols__insert(&dso->symbols[map->type], f);
380                         ++nr;
381                 }
382         }
383 
384         err = 0;
385 out_elf_end:
386         if (err == 0)
387                 return nr;
388         pr_debug("%s: problems reading %s PLT info.\n",
389                  __func__, dso->long_name);
390         return 0;
391 }
392 
393 /*
394  * Align offset to 4 bytes as needed for note name and descriptor data.
395  */
396 #define NOTE_ALIGN(n) (((n) + 3) & -4U)
397 
398 static int elf_read_build_id(Elf *elf, void *bf, size_t size)
399 {
400         int err = -1;
401         GElf_Ehdr ehdr;
402         GElf_Shdr shdr;
403         Elf_Data *data;
404         Elf_Scn *sec;
405         Elf_Kind ek;
406         void *ptr;
407 
408         if (size < BUILD_ID_SIZE)
409                 goto out;
410 
411         ek = elf_kind(elf);
412         if (ek != ELF_K_ELF)
413                 goto out;
414 
415         if (gelf_getehdr(elf, &ehdr) == NULL) {
416                 pr_err("%s: cannot get elf header.\n", __func__);
417                 goto out;
418         }
419 
420         /*
421          * Check following sections for notes:
422          *   '.note.gnu.build-id'
423          *   '.notes'
424          *   '.note' (VDSO specific)
425          */
426         do {
427                 sec = elf_section_by_name(elf, &ehdr, &shdr,
428                                           ".note.gnu.build-id", NULL);
429                 if (sec)
430                         break;
431 
432                 sec = elf_section_by_name(elf, &ehdr, &shdr,
433                                           ".notes", NULL);
434                 if (sec)
435                         break;
436 
437                 sec = elf_section_by_name(elf, &ehdr, &shdr,
438                                           ".note", NULL);
439                 if (sec)
440                         break;
441 
442                 return err;
443 
444         } while (0);
445 
446         data = elf_getdata(sec, NULL);
447         if (data == NULL)
448                 goto out;
449 
450         ptr = data->d_buf;
451         while (ptr < (data->d_buf + data->d_size)) {
452                 GElf_Nhdr *nhdr = ptr;
453                 size_t namesz = NOTE_ALIGN(nhdr->n_namesz),
454                        descsz = NOTE_ALIGN(nhdr->n_descsz);
455                 const char *name;
456 
457                 ptr += sizeof(*nhdr);
458                 name = ptr;
459                 ptr += namesz;
460                 if (nhdr->n_type == NT_GNU_BUILD_ID &&
461                     nhdr->n_namesz == sizeof("GNU")) {
462                         if (memcmp(name, "GNU", sizeof("GNU")) == 0) {
463                                 size_t sz = min(size, descsz);
464                                 memcpy(bf, ptr, sz);
465                                 memset(bf + sz, 0, size - sz);
466                                 err = descsz;
467                                 break;
468                         }
469                 }
470                 ptr += descsz;
471         }
472 
473 out:
474         return err;
475 }
476 
477 int filename__read_build_id(const char *filename, void *bf, size_t size)
478 {
479         int fd, err = -1;
480         Elf *elf;
481 
482         if (size < BUILD_ID_SIZE)
483                 goto out;
484 
485         fd = open(filename, O_RDONLY);
486         if (fd < 0)
487                 goto out;
488 
489         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
490         if (elf == NULL) {
491                 pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
492                 goto out_close;
493         }
494 
495         err = elf_read_build_id(elf, bf, size);
496 
497         elf_end(elf);
498 out_close:
499         close(fd);
500 out:
501         return err;
502 }
503 
504 int sysfs__read_build_id(const char *filename, void *build_id, size_t size)
505 {
506         int fd, err = -1;
507 
508         if (size < BUILD_ID_SIZE)
509                 goto out;
510 
511         fd = open(filename, O_RDONLY);
512         if (fd < 0)
513                 goto out;
514 
515         while (1) {
516                 char bf[BUFSIZ];
517                 GElf_Nhdr nhdr;
518                 size_t namesz, descsz;
519 
520                 if (read(fd, &nhdr, sizeof(nhdr)) != sizeof(nhdr))
521                         break;
522 
523                 namesz = NOTE_ALIGN(nhdr.n_namesz);
524                 descsz = NOTE_ALIGN(nhdr.n_descsz);
525                 if (nhdr.n_type == NT_GNU_BUILD_ID &&
526                     nhdr.n_namesz == sizeof("GNU")) {
527                         if (read(fd, bf, namesz) != (ssize_t)namesz)
528                                 break;
529                         if (memcmp(bf, "GNU", sizeof("GNU")) == 0) {
530                                 size_t sz = min(descsz, size);
531                                 if (read(fd, build_id, sz) == (ssize_t)sz) {
532                                         memset(build_id + sz, 0, size - sz);
533                                         err = 0;
534                                         break;
535                                 }
536                         } else if (read(fd, bf, descsz) != (ssize_t)descsz)
537                                 break;
538                 } else {
539                         int n = namesz + descsz;
540 
541                         if (n > (int)sizeof(bf)) {
542                                 n = sizeof(bf);
543                                 pr_debug("%s: truncating reading of build id in sysfs file %s: n_namesz=%u, n_descsz=%u.\n",
544                                          __func__, filename, nhdr.n_namesz, nhdr.n_descsz);
545                         }
546                         if (read(fd, bf, n) != n)
547                                 break;
548                 }
549         }
550         close(fd);
551 out:
552         return err;
553 }
554 
555 int filename__read_debuglink(const char *filename, char *debuglink,
556                              size_t size)
557 {
558         int fd, err = -1;
559         Elf *elf;
560         GElf_Ehdr ehdr;
561         GElf_Shdr shdr;
562         Elf_Data *data;
563         Elf_Scn *sec;
564         Elf_Kind ek;
565 
566         fd = open(filename, O_RDONLY);
567         if (fd < 0)
568                 goto out;
569 
570         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
571         if (elf == NULL) {
572                 pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);
573                 goto out_close;
574         }
575 
576         ek = elf_kind(elf);
577         if (ek != ELF_K_ELF)
578                 goto out_elf_end;
579 
580         if (gelf_getehdr(elf, &ehdr) == NULL) {
581                 pr_err("%s: cannot get elf header.\n", __func__);
582                 goto out_elf_end;
583         }
584 
585         sec = elf_section_by_name(elf, &ehdr, &shdr,
586                                   ".gnu_debuglink", NULL);
587         if (sec == NULL)
588                 goto out_elf_end;
589 
590         data = elf_getdata(sec, NULL);
591         if (data == NULL)
592                 goto out_elf_end;
593 
594         /* the start of this section is a zero-terminated string */
595         strncpy(debuglink, data->d_buf, size);
596 
597         err = 0;
598 
599 out_elf_end:
600         elf_end(elf);
601 out_close:
602         close(fd);
603 out:
604         return err;
605 }
606 
607 static int dso__swap_init(struct dso *dso, unsigned char eidata)
608 {
609         static unsigned int const endian = 1;
610 
611         dso->needs_swap = DSO_SWAP__NO;
612 
613         switch (eidata) {
614         case ELFDATA2LSB:
615                 /* We are big endian, DSO is little endian. */
616                 if (*(unsigned char const *)&endian != 1)
617                         dso->needs_swap = DSO_SWAP__YES;
618                 break;
619 
620         case ELFDATA2MSB:
621                 /* We are little endian, DSO is big endian. */
622                 if (*(unsigned char const *)&endian != 0)
623                         dso->needs_swap = DSO_SWAP__YES;
624                 break;
625 
626         default:
627                 pr_err("unrecognized DSO data encoding %d\n", eidata);
628                 return -EINVAL;
629         }
630 
631         return 0;
632 }
633 
634 static int decompress_kmodule(struct dso *dso, const char *name,
635                               enum dso_binary_type type)
636 {
637         int fd = -1;
638         char tmpbuf[] = "/tmp/perf-kmod-XXXXXX";
639         struct kmod_path m;
640 
641         if (type != DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP &&
642             type != DSO_BINARY_TYPE__GUEST_KMODULE_COMP &&
643             type != DSO_BINARY_TYPE__BUILD_ID_CACHE)
644                 return -1;
645 
646         if (type == DSO_BINARY_TYPE__BUILD_ID_CACHE)
647                 name = dso->long_name;
648 
649         if (kmod_path__parse_ext(&m, name) || !m.comp)
650                 return -1;
651 
652         fd = mkstemp(tmpbuf);
653         if (fd < 0) {
654                 dso->load_errno = errno;
655                 goto out;
656         }
657 
658         if (!decompress_to_file(m.ext, name, fd)) {
659                 dso->load_errno = DSO_LOAD_ERRNO__DECOMPRESSION_FAILURE;
660                 close(fd);
661                 fd = -1;
662         }
663 
664         unlink(tmpbuf);
665 
666 out:
667         free(m.ext);
668         return fd;
669 }
670 
671 bool symsrc__possibly_runtime(struct symsrc *ss)
672 {
673         return ss->dynsym || ss->opdsec;
674 }
675 
676 bool symsrc__has_symtab(struct symsrc *ss)
677 {
678         return ss->symtab != NULL;
679 }
680 
681 void symsrc__destroy(struct symsrc *ss)
682 {
683         zfree(&ss->name);
684         elf_end(ss->elf);
685         close(ss->fd);
686 }
687 
688 bool __weak elf__needs_adjust_symbols(GElf_Ehdr ehdr)
689 {
690         return ehdr.e_type == ET_EXEC || ehdr.e_type == ET_REL;
691 }
692 
693 int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
694                  enum dso_binary_type type)
695 {
696         int err = -1;
697         GElf_Ehdr ehdr;
698         Elf *elf;
699         int fd;
700 
701         if (dso__needs_decompress(dso)) {
702                 fd = decompress_kmodule(dso, name, type);
703                 if (fd < 0)
704                         return -1;
705         } else {
706                 fd = open(name, O_RDONLY);
707                 if (fd < 0) {
708                         dso->load_errno = errno;
709                         return -1;
710                 }
711         }
712 
713         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
714         if (elf == NULL) {
715                 pr_debug("%s: cannot read %s ELF file.\n", __func__, name);
716                 dso->load_errno = DSO_LOAD_ERRNO__INVALID_ELF;
717                 goto out_close;
718         }
719 
720         if (gelf_getehdr(elf, &ehdr) == NULL) {
721                 dso->load_errno = DSO_LOAD_ERRNO__INVALID_ELF;
722                 pr_debug("%s: cannot get elf header.\n", __func__);
723                 goto out_elf_end;
724         }
725 
726         if (dso__swap_init(dso, ehdr.e_ident[EI_DATA])) {
727                 dso->load_errno = DSO_LOAD_ERRNO__INTERNAL_ERROR;
728                 goto out_elf_end;
729         }
730 
731         /* Always reject images with a mismatched build-id: */
732         if (dso->has_build_id && !symbol_conf.ignore_vmlinux_buildid) {
733                 u8 build_id[BUILD_ID_SIZE];
734 
735                 if (elf_read_build_id(elf, build_id, BUILD_ID_SIZE) < 0) {
736                         dso->load_errno = DSO_LOAD_ERRNO__CANNOT_READ_BUILDID;
737                         goto out_elf_end;
738                 }
739 
740                 if (!dso__build_id_equal(dso, build_id)) {
741                         pr_debug("%s: build id mismatch for %s.\n", __func__, name);
742                         dso->load_errno = DSO_LOAD_ERRNO__MISMATCHING_BUILDID;
743                         goto out_elf_end;
744                 }
745         }
746 
747         ss->is_64_bit = (gelf_getclass(elf) == ELFCLASS64);
748 
749         ss->symtab = elf_section_by_name(elf, &ehdr, &ss->symshdr, ".symtab",
750                         NULL);
751         if (ss->symshdr.sh_type != SHT_SYMTAB)
752                 ss->symtab = NULL;
753 
754         ss->dynsym_idx = 0;
755         ss->dynsym = elf_section_by_name(elf, &ehdr, &ss->dynshdr, ".dynsym",
756                         &ss->dynsym_idx);
757         if (ss->dynshdr.sh_type != SHT_DYNSYM)
758                 ss->dynsym = NULL;
759 
760         ss->opdidx = 0;
761         ss->opdsec = elf_section_by_name(elf, &ehdr, &ss->opdshdr, ".opd",
762                         &ss->opdidx);
763         if (ss->opdshdr.sh_type != SHT_PROGBITS)
764                 ss->opdsec = NULL;
765 
766         if (dso->kernel == DSO_TYPE_USER)
767                 ss->adjust_symbols = true;
768         else
769                 ss->adjust_symbols = elf__needs_adjust_symbols(ehdr);
770 
771         ss->name   = strdup(name);
772         if (!ss->name) {
773                 dso->load_errno = errno;
774                 goto out_elf_end;
775         }
776 
777         ss->elf    = elf;
778         ss->fd     = fd;
779         ss->ehdr   = ehdr;
780         ss->type   = type;
781 
782         return 0;
783 
784 out_elf_end:
785         elf_end(elf);
786 out_close:
787         close(fd);
788         return err;
789 }
790 
791 /**
792  * ref_reloc_sym_not_found - has kernel relocation symbol been found.
793  * @kmap: kernel maps and relocation reference symbol
794  *
795  * This function returns %true if we are dealing with the kernel maps and the
796  * relocation reference symbol has not yet been found.  Otherwise %false is
797  * returned.
798  */
799 static bool ref_reloc_sym_not_found(struct kmap *kmap)
800 {
801         return kmap && kmap->ref_reloc_sym && kmap->ref_reloc_sym->name &&
802                !kmap->ref_reloc_sym->unrelocated_addr;
803 }
804 
805 /**
806  * ref_reloc - kernel relocation offset.
807  * @kmap: kernel maps and relocation reference symbol
808  *
809  * This function returns the offset of kernel addresses as determined by using
810  * the relocation reference symbol i.e. if the kernel has not been relocated
811  * then the return value is zero.
812  */
813 static u64 ref_reloc(struct kmap *kmap)
814 {
815         if (kmap && kmap->ref_reloc_sym &&
816             kmap->ref_reloc_sym->unrelocated_addr)
817                 return kmap->ref_reloc_sym->addr -
818                        kmap->ref_reloc_sym->unrelocated_addr;
819         return 0;
820 }
821 
822 void __weak arch__sym_update(struct symbol *s __maybe_unused,
823                 GElf_Sym *sym __maybe_unused) { }
824 
825 int dso__load_sym(struct dso *dso, struct map *map, struct symsrc *syms_ss,
826                   struct symsrc *runtime_ss, int kmodule)
827 {
828         struct kmap *kmap = dso->kernel ? map__kmap(map) : NULL;
829         struct map_groups *kmaps = kmap ? map__kmaps(map) : NULL;
830         struct map *curr_map = map;
831         struct dso *curr_dso = dso;
832         Elf_Data *symstrs, *secstrs;
833         uint32_t nr_syms;
834         int err = -1;
835         uint32_t idx;
836         GElf_Ehdr ehdr;
837         GElf_Shdr shdr;
838         GElf_Shdr tshdr;
839         Elf_Data *syms, *opddata = NULL;
840         GElf_Sym sym;
841         Elf_Scn *sec, *sec_strndx;
842         Elf *elf;
843         int nr = 0;
844         bool remap_kernel = false, adjust_kernel_syms = false;
845 
846         if (kmap && !kmaps)
847                 return -1;
848 
849         dso->symtab_type = syms_ss->type;
850         dso->is_64_bit = syms_ss->is_64_bit;
851         dso->rel = syms_ss->ehdr.e_type == ET_REL;
852 
853         /*
854          * Modules may already have symbols from kallsyms, but those symbols
855          * have the wrong values for the dso maps, so remove them.
856          */
857         if (kmodule && syms_ss->symtab)
858                 symbols__delete(&dso->symbols[map->type]);
859 
860         if (!syms_ss->symtab) {
861                 /*
862                  * If the vmlinux is stripped, fail so we will fall back
863                  * to using kallsyms. The vmlinux runtime symbols aren't
864                  * of much use.
865                  */
866                 if (dso->kernel)
867                         goto out_elf_end;
868 
869                 syms_ss->symtab  = syms_ss->dynsym;
870                 syms_ss->symshdr = syms_ss->dynshdr;
871         }
872 
873         elf = syms_ss->elf;
874         ehdr = syms_ss->ehdr;
875         sec = syms_ss->symtab;
876         shdr = syms_ss->symshdr;
877 
878         if (elf_section_by_name(runtime_ss->elf, &runtime_ss->ehdr, &tshdr,
879                                 ".text", NULL))
880                 dso->text_offset = tshdr.sh_addr - tshdr.sh_offset;
881 
882         if (runtime_ss->opdsec)
883                 opddata = elf_rawdata(runtime_ss->opdsec, NULL);
884 
885         syms = elf_getdata(sec, NULL);
886         if (syms == NULL)
887                 goto out_elf_end;
888 
889         sec = elf_getscn(elf, shdr.sh_link);
890         if (sec == NULL)
891                 goto out_elf_end;
892 
893         symstrs = elf_getdata(sec, NULL);
894         if (symstrs == NULL)
895                 goto out_elf_end;
896 
897         sec_strndx = elf_getscn(runtime_ss->elf, runtime_ss->ehdr.e_shstrndx);
898         if (sec_strndx == NULL)
899                 goto out_elf_end;
900 
901         secstrs = elf_getdata(sec_strndx, NULL);
902         if (secstrs == NULL)
903                 goto out_elf_end;
904 
905         nr_syms = shdr.sh_size / shdr.sh_entsize;
906 
907         memset(&sym, 0, sizeof(sym));
908 
909         /*
910          * The kernel relocation symbol is needed in advance in order to adjust
911          * kernel maps correctly.
912          */
913         if (ref_reloc_sym_not_found(kmap)) {
914                 elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
915                         const char *elf_name = elf_sym__name(&sym, symstrs);
916 
917                         if (strcmp(elf_name, kmap->ref_reloc_sym->name))
918                                 continue;
919                         kmap->ref_reloc_sym->unrelocated_addr = sym.st_value;
920                         map->reloc = kmap->ref_reloc_sym->addr -
921                                      kmap->ref_reloc_sym->unrelocated_addr;
922                         break;
923                 }
924         }
925 
926         /*
927          * Handle any relocation of vdso necessary because older kernels
928          * attempted to prelink vdso to its virtual address.
929          */
930         if (dso__is_vdso(dso))
931                 map->reloc = map->start - dso->text_offset;
932 
933         dso->adjust_symbols = runtime_ss->adjust_symbols || ref_reloc(kmap);
934         /*
935          * Initial kernel and module mappings do not map to the dso.  For
936          * function mappings, flag the fixups.
937          */
938         if (map->type == MAP__FUNCTION && (dso->kernel || kmodule)) {
939                 remap_kernel = true;
940                 adjust_kernel_syms = dso->adjust_symbols;
941         }
942         elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
943                 struct symbol *f;
944                 const char *elf_name = elf_sym__name(&sym, symstrs);
945                 char *demangled = NULL;
946                 int is_label = elf_sym__is_label(&sym);
947                 const char *section_name;
948                 bool used_opd = false;
949 
950                 if (!is_label && !elf_sym__is_a(&sym, map->type))
951                         continue;
952 
953                 /* Reject ARM ELF "mapping symbols": these aren't unique and
954                  * don't identify functions, so will confuse the profile
955                  * output: */
956                 if (ehdr.e_machine == EM_ARM || ehdr.e_machine == EM_AARCH64) {
957                         if (elf_name[0] == '$' && strchr("adtx", elf_name[1])
958                             && (elf_name[2] == '\0' || elf_name[2] == '.'))
959                                 continue;
960                 }
961 
962                 if (runtime_ss->opdsec && sym.st_shndx == runtime_ss->opdidx) {
963                         u32 offset = sym.st_value - syms_ss->opdshdr.sh_addr;
964                         u64 *opd = opddata->d_buf + offset;
965                         sym.st_value = DSO__SWAP(dso, u64, *opd);
966                         sym.st_shndx = elf_addr_to_index(runtime_ss->elf,
967                                         sym.st_value);
968                         used_opd = true;
969                 }
970                 /*
971                  * When loading symbols in a data mapping, ABS symbols (which
972                  * has a value of SHN_ABS in its st_shndx) failed at
973                  * elf_getscn().  And it marks the loading as a failure so
974                  * already loaded symbols cannot be fixed up.
975                  *
976                  * I'm not sure what should be done. Just ignore them for now.
977                  * - Namhyung Kim
978                  */
979                 if (sym.st_shndx == SHN_ABS)
980                         continue;
981 
982                 sec = elf_getscn(runtime_ss->elf, sym.st_shndx);
983                 if (!sec)
984                         goto out_elf_end;
985 
986                 gelf_getshdr(sec, &shdr);
987 
988                 if (is_label && !elf_sec__is_a(&shdr, secstrs, map->type))
989                         continue;
990 
991                 section_name = elf_sec__name(&shdr, secstrs);
992 
993                 /* On ARM, symbols for thumb functions have 1 added to
994                  * the symbol address as a flag - remove it */
995                 if ((ehdr.e_machine == EM_ARM) &&
996                     (map->type == MAP__FUNCTION) &&
997                     (sym.st_value & 1))
998                         --sym.st_value;
999 
1000                 if (dso->kernel || kmodule) {
1001                         char dso_name[PATH_MAX];
1002 
1003                         /* Adjust symbol to map to file offset */
1004                         if (adjust_kernel_syms)
1005                                 sym.st_value -= shdr.sh_addr - shdr.sh_offset;
1006 
1007                         if (strcmp(section_name,
1008                                    (curr_dso->short_name +
1009                                     dso->short_name_len)) == 0)
1010                                 goto new_symbol;
1011 
1012                         if (strcmp(section_name, ".text") == 0) {
1013                                 /*
1014                                  * The initial kernel mapping is based on
1015                                  * kallsyms and identity maps.  Overwrite it to
1016                                  * map to the kernel dso.
1017                                  */
1018                                 if (remap_kernel && dso->kernel) {
1019                                         remap_kernel = false;
1020                                         map->start = shdr.sh_addr +
1021                                                      ref_reloc(kmap);
1022                                         map->end = map->start + shdr.sh_size;
1023                                         map->pgoff = shdr.sh_offset;
1024                                         map->map_ip = map__map_ip;
1025                                         map->unmap_ip = map__unmap_ip;
1026                                         /* Ensure maps are correctly ordered */
1027                                         if (kmaps) {
1028                                                 map__get(map);
1029                                                 map_groups__remove(kmaps, map);
1030                                                 map_groups__insert(kmaps, map);
1031                                                 map__put(map);
1032                                         }
1033                                 }
1034 
1035                                 /*
1036                                  * The initial module mapping is based on
1037                                  * /proc/modules mapped to offset zero.
1038                                  * Overwrite it to map to the module dso.
1039                                  */
1040                                 if (remap_kernel && kmodule) {
1041                                         remap_kernel = false;
1042                                         map->pgoff = shdr.sh_offset;
1043                                 }
1044 
1045                                 curr_map = map;
1046                                 curr_dso = dso;
1047                                 goto new_symbol;
1048                         }
1049 
1050                         if (!kmap)
1051                                 goto new_symbol;
1052 
1053                         snprintf(dso_name, sizeof(dso_name),
1054                                  "%s%s", dso->short_name, section_name);
1055 
1056                         curr_map = map_groups__find_by_name(kmaps, map->type, dso_name);
1057                         if (curr_map == NULL) {
1058                                 u64 start = sym.st_value;
1059 
1060                                 if (kmodule)
1061                                         start += map->start + shdr.sh_offset;
1062 
1063                                 curr_dso = dso__new(dso_name);
1064                                 if (curr_dso == NULL)
1065                                         goto out_elf_end;
1066                                 curr_dso->kernel = dso->kernel;
1067                                 curr_dso->long_name = dso->long_name;
1068                                 curr_dso->long_name_len = dso->long_name_len;
1069                                 curr_map = map__new2(start, curr_dso,
1070                                                      map->type);
1071                                 dso__put(curr_dso);
1072                                 if (curr_map == NULL) {
1073                                         goto out_elf_end;
1074                                 }
1075                                 if (adjust_kernel_syms) {
1076                                         curr_map->start = shdr.sh_addr +
1077                                                           ref_reloc(kmap);
1078                                         curr_map->end = curr_map->start +
1079                                                         shdr.sh_size;
1080                                         curr_map->pgoff = shdr.sh_offset;
1081                                 } else {
1082                                         curr_map->map_ip = identity__map_ip;
1083                                         curr_map->unmap_ip = identity__map_ip;
1084                                 }
1085                                 curr_dso->symtab_type = dso->symtab_type;
1086                                 map_groups__insert(kmaps, curr_map);
1087                                 /*
1088                                  * Add it before we drop the referece to curr_map,
1089                                  * i.e. while we still are sure to have a reference
1090                                  * to this DSO via curr_map->dso.
1091                                  */
1092                                 dsos__add(&map->groups->machine->dsos, curr_dso);
1093                                 /* kmaps already got it */
1094                                 map__put(curr_map);
1095                                 dso__set_loaded(curr_dso, map->type);
1096                         } else
1097                                 curr_dso = curr_map->dso;
1098 
1099                         goto new_symbol;
1100                 }
1101 
1102                 if ((used_opd && runtime_ss->adjust_symbols)
1103                                 || (!used_opd && syms_ss->adjust_symbols)) {
1104                         pr_debug4("%s: adjusting symbol: st_value: %#" PRIx64 " "
1105                                   "sh_addr: %#" PRIx64 " sh_offset: %#" PRIx64 "\n", __func__,
1106                                   (u64)sym.st_value, (u64)shdr.sh_addr,
1107                                   (u64)shdr.sh_offset);
1108                         sym.st_value -= shdr.sh_addr - shdr.sh_offset;
1109                 }
1110 new_symbol:
1111                 demangled = demangle_sym(dso, kmodule, elf_name);
1112                 if (demangled != NULL)
1113                         elf_name = demangled;
1114 
1115                 f = symbol__new(sym.st_value, sym.st_size,
1116                                 GELF_ST_BIND(sym.st_info), elf_name);
1117                 free(demangled);
1118                 if (!f)
1119                         goto out_elf_end;
1120 
1121                 arch__sym_update(f, &sym);
1122 
1123                 __symbols__insert(&curr_dso->symbols[curr_map->type], f, dso->kernel);
1124                 nr++;
1125         }
1126 
1127         /*
1128          * For misannotated, zeroed, ASM function sizes.
1129          */
1130         if (nr > 0) {
1131                 symbols__fixup_end(&dso->symbols[map->type]);
1132                 symbols__fixup_duplicate(&dso->symbols[map->type]);
1133                 if (kmap) {
1134                         /*
1135                          * We need to fixup this here too because we create new
1136                          * maps here, for things like vsyscall sections.
1137                          */
1138                         __map_groups__fixup_end(kmaps, map->type);
1139                 }
1140         }
1141         err = nr;
1142 out_elf_end:
1143         return err;
1144 }
1145 
1146 static int elf_read_maps(Elf *elf, bool exe, mapfn_t mapfn, void *data)
1147 {
1148         GElf_Phdr phdr;
1149         size_t i, phdrnum;
1150         int err;
1151         u64 sz;
1152 
1153         if (elf_getphdrnum(elf, &phdrnum))
1154                 return -1;
1155 
1156         for (i = 0; i < phdrnum; i++) {
1157                 if (gelf_getphdr(elf, i, &phdr) == NULL)
1158                         return -1;
1159                 if (phdr.p_type != PT_LOAD)
1160                         continue;
1161                 if (exe) {
1162                         if (!(phdr.p_flags & PF_X))
1163                                 continue;
1164                 } else {
1165                         if (!(phdr.p_flags & PF_R))
1166                                 continue;
1167                 }
1168                 sz = min(phdr.p_memsz, phdr.p_filesz);
1169                 if (!sz)
1170                         continue;
1171                 err = mapfn(phdr.p_vaddr, sz, phdr.p_offset, data);
1172                 if (err)
1173                         return err;
1174         }
1175         return 0;
1176 }
1177 
1178 int file__read_maps(int fd, bool exe, mapfn_t mapfn, void *data,
1179                     bool *is_64_bit)
1180 {
1181         int err;
1182         Elf *elf;
1183 
1184         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
1185         if (elf == NULL)
1186                 return -1;
1187 
1188         if (is_64_bit)
1189                 *is_64_bit = (gelf_getclass(elf) == ELFCLASS64);
1190 
1191         err = elf_read_maps(elf, exe, mapfn, data);
1192 
1193         elf_end(elf);
1194         return err;
1195 }
1196 
1197 enum dso_type dso__type_fd(int fd)
1198 {
1199         enum dso_type dso_type = DSO__TYPE_UNKNOWN;
1200         GElf_Ehdr ehdr;
1201         Elf_Kind ek;
1202         Elf *elf;
1203 
1204         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
1205         if (elf == NULL)
1206                 goto out;
1207 
1208         ek = elf_kind(elf);
1209         if (ek != ELF_K_ELF)
1210                 goto out_end;
1211 
1212         if (gelf_getclass(elf) == ELFCLASS64) {
1213                 dso_type = DSO__TYPE_64BIT;
1214                 goto out_end;
1215         }
1216 
1217         if (gelf_getehdr(elf, &ehdr) == NULL)
1218                 goto out_end;
1219 
1220         if (ehdr.e_machine == EM_X86_64)
1221                 dso_type = DSO__TYPE_X32BIT;
1222         else
1223                 dso_type = DSO__TYPE_32BIT;
1224 out_end:
1225         elf_end(elf);
1226 out:
1227         return dso_type;
1228 }
1229 
1230 static int copy_bytes(int from, off_t from_offs, int to, off_t to_offs, u64 len)
1231 {
1232         ssize_t r;
1233         size_t n;
1234         int err = -1;
1235         char *buf = malloc(page_size);
1236 
1237         if (buf == NULL)
1238                 return -1;
1239 
1240         if (lseek(to, to_offs, SEEK_SET) != to_offs)
1241                 goto out;
1242 
1243         if (lseek(from, from_offs, SEEK_SET) != from_offs)
1244                 goto out;
1245 
1246         while (len) {
1247                 n = page_size;
1248                 if (len < n)
1249                         n = len;
1250                 /* Use read because mmap won't work on proc files */
1251                 r = read(from, buf, n);
1252                 if (r < 0)
1253                         goto out;
1254                 if (!r)
1255                         break;
1256                 n = r;
1257                 r = write(to, buf, n);
1258                 if (r < 0)
1259                         goto out;
1260                 if ((size_t)r != n)
1261                         goto out;
1262                 len -= n;
1263         }
1264 
1265         err = 0;
1266 out:
1267         free(buf);
1268         return err;
1269 }
1270 
1271 struct kcore {
1272         int fd;
1273         int elfclass;
1274         Elf *elf;
1275         GElf_Ehdr ehdr;
1276 };
1277 
1278 static int kcore__open(struct kcore *kcore, const char *filename)
1279 {
1280         GElf_Ehdr *ehdr;
1281 
1282         kcore->fd = open(filename, O_RDONLY);
1283         if (kcore->fd == -1)
1284                 return -1;
1285 
1286         kcore->elf = elf_begin(kcore->fd, ELF_C_READ, NULL);
1287         if (!kcore->elf)
1288                 goto out_close;
1289 
1290         kcore->elfclass = gelf_getclass(kcore->elf);
1291         if (kcore->elfclass == ELFCLASSNONE)
1292                 goto out_end;
1293 
1294         ehdr = gelf_getehdr(kcore->elf, &kcore->ehdr);
1295         if (!ehdr)
1296                 goto out_end;
1297 
1298         return 0;
1299 
1300 out_end:
1301         elf_end(kcore->elf);
1302 out_close:
1303         close(kcore->fd);
1304         return -1;
1305 }
1306 
1307 static int kcore__init(struct kcore *kcore, char *filename, int elfclass,
1308                        bool temp)
1309 {
1310         kcore->elfclass = elfclass;
1311 
1312         if (temp)
1313                 kcore->fd = mkstemp(filename);
1314         else
1315                 kcore->fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0400);
1316         if (kcore->fd == -1)
1317                 return -1;
1318 
1319         kcore->elf = elf_begin(kcore->fd, ELF_C_WRITE, NULL);
1320         if (!kcore->elf)
1321                 goto out_close;
1322 
1323         if (!gelf_newehdr(kcore->elf, elfclass))
1324                 goto out_end;
1325 
1326         memset(&kcore->ehdr, 0, sizeof(GElf_Ehdr));
1327 
1328         return 0;
1329 
1330 out_end:
1331         elf_end(kcore->elf);
1332 out_close:
1333         close(kcore->fd);
1334         unlink(filename);
1335         return -1;
1336 }
1337 
1338 static void kcore__close(struct kcore *kcore)
1339 {
1340         elf_end(kcore->elf);
1341         close(kcore->fd);
1342 }
1343 
1344 static int kcore__copy_hdr(struct kcore *from, struct kcore *to, size_t count)
1345 {
1346         GElf_Ehdr *ehdr = &to->ehdr;
1347         GElf_Ehdr *kehdr = &from->ehdr;
1348 
1349         memcpy(ehdr->e_ident, kehdr->e_ident, EI_NIDENT);
1350         ehdr->e_type      = kehdr->e_type;
1351         ehdr->e_machine   = kehdr->e_machine;
1352         ehdr->e_version   = kehdr->e_version;
1353         ehdr->e_entry     = 0;
1354         ehdr->e_shoff     = 0;
1355         ehdr->e_flags     = kehdr->e_flags;
1356         ehdr->e_phnum     = count;
1357         ehdr->e_shentsize = 0;
1358         ehdr->e_shnum     = 0;
1359         ehdr->e_shstrndx  = 0;
1360 
1361         if (from->elfclass == ELFCLASS32) {
1362                 ehdr->e_phoff     = sizeof(Elf32_Ehdr);
1363                 ehdr->e_ehsize    = sizeof(Elf32_Ehdr);
1364                 ehdr->e_phentsize = sizeof(Elf32_Phdr);
1365         } else {
1366                 ehdr->e_phoff     = sizeof(Elf64_Ehdr);
1367                 ehdr->e_ehsize    = sizeof(Elf64_Ehdr);
1368                 ehdr->e_phentsize = sizeof(Elf64_Phdr);
1369         }
1370 
1371         if (!gelf_update_ehdr(to->elf, ehdr))
1372                 return -1;
1373 
1374         if (!gelf_newphdr(to->elf, count))
1375                 return -1;
1376 
1377         return 0;
1378 }
1379 
1380 static int kcore__add_phdr(struct kcore *kcore, int idx, off_t offset,
1381                            u64 addr, u64 len)
1382 {
1383         GElf_Phdr phdr = {
1384                 .p_type         = PT_LOAD,
1385                 .p_flags        = PF_R | PF_W | PF_X,
1386                 .p_offset       = offset,
1387                 .p_vaddr        = addr,
1388                 .p_paddr        = 0,
1389                 .p_filesz       = len,
1390                 .p_memsz        = len,
1391                 .p_align        = page_size,
1392         };
1393 
1394         if (!gelf_update_phdr(kcore->elf, idx, &phdr))
1395                 return -1;
1396 
1397         return 0;
1398 }
1399 
1400 static off_t kcore__write(struct kcore *kcore)
1401 {
1402         return elf_update(kcore->elf, ELF_C_WRITE);
1403 }
1404 
1405 struct phdr_data {
1406         off_t offset;
1407         u64 addr;
1408         u64 len;
1409 };
1410 
1411 struct kcore_copy_info {
1412         u64 stext;
1413         u64 etext;
1414         u64 first_symbol;
1415         u64 last_symbol;
1416         u64 first_module;
1417         u64 last_module_symbol;
1418         struct phdr_data kernel_map;
1419         struct phdr_data modules_map;
1420 };
1421 
1422 static int kcore_copy__process_kallsyms(void *arg, const char *name, char type,
1423                                         u64 start)
1424 {
1425         struct kcore_copy_info *kci = arg;
1426 
1427         if (!symbol_type__is_a(type, MAP__FUNCTION))
1428                 return 0;
1429 
1430         if (strchr(name, '[')) {
1431                 if (start > kci->last_module_symbol)
1432                         kci->last_module_symbol = start;
1433                 return 0;
1434         }
1435 
1436         if (!kci->first_symbol || start < kci->first_symbol)
1437                 kci->first_symbol = start;
1438 
1439         if (!kci->last_symbol || start > kci->last_symbol)
1440                 kci->last_symbol = start;
1441 
1442         if (!strcmp(name, "_stext")) {
1443                 kci->stext = start;
1444                 return 0;
1445         }
1446 
1447         if (!strcmp(name, "_etext")) {
1448                 kci->etext = start;
1449                 return 0;
1450         }
1451 
1452         return 0;
1453 }
1454 
1455 static int kcore_copy__parse_kallsyms(struct kcore_copy_info *kci,
1456                                       const char *dir)
1457 {
1458         char kallsyms_filename[PATH_MAX];
1459 
1460         scnprintf(kallsyms_filename, PATH_MAX, "%s/kallsyms", dir);
1461 
1462         if (symbol__restricted_filename(kallsyms_filename, "/proc/kallsyms"))
1463                 return -1;
1464 
1465         if (kallsyms__parse(kallsyms_filename, kci,
1466                             kcore_copy__process_kallsyms) < 0)
1467                 return -1;
1468 
1469         return 0;
1470 }
1471 
1472 static int kcore_copy__process_modules(void *arg,
1473                                        const char *name __maybe_unused,
1474                                        u64 start)
1475 {
1476         struct kcore_copy_info *kci = arg;
1477 
1478         if (!kci->first_module || start < kci->first_module)
1479                 kci->first_module = start;
1480 
1481         return 0;
1482 }
1483 
1484 static int kcore_copy__parse_modules(struct kcore_copy_info *kci,
1485                                      const char *dir)
1486 {
1487         char modules_filename[PATH_MAX];
1488 
1489         scnprintf(modules_filename, PATH_MAX, "%s/modules", dir);
1490 
1491         if (symbol__restricted_filename(modules_filename, "/proc/modules"))
1492                 return -1;
1493 
1494         if (modules__parse(modules_filename, kci,
1495                            kcore_copy__process_modules) < 0)
1496                 return -1;
1497 
1498         return 0;
1499 }
1500 
1501 static void kcore_copy__map(struct phdr_data *p, u64 start, u64 end, u64 pgoff,
1502                             u64 s, u64 e)
1503 {
1504         if (p->addr || s < start || s >= end)
1505                 return;
1506 
1507         p->addr = s;
1508         p->offset = (s - start) + pgoff;
1509         p->len = e < end ? e - s : end - s;
1510 }
1511 
1512 static int kcore_copy__read_map(u64 start, u64 len, u64 pgoff, void *data)
1513 {
1514         struct kcore_copy_info *kci = data;
1515         u64 end = start + len;
1516 
1517         kcore_copy__map(&kci->kernel_map, start, end, pgoff, kci->stext,
1518                         kci->etext);
1519 
1520         kcore_copy__map(&kci->modules_map, start, end, pgoff, kci->first_module,
1521                         kci->last_module_symbol);
1522 
1523         return 0;
1524 }
1525 
1526 static int kcore_copy__read_maps(struct kcore_copy_info *kci, Elf *elf)
1527 {
1528         if (elf_read_maps(elf, true, kcore_copy__read_map, kci) < 0)
1529                 return -1;
1530 
1531         return 0;
1532 }
1533 
1534 static int kcore_copy__calc_maps(struct kcore_copy_info *kci, const char *dir,
1535                                  Elf *elf)
1536 {
1537         if (kcore_copy__parse_kallsyms(kci, dir))
1538                 return -1;
1539 
1540         if (kcore_copy__parse_modules(kci, dir))
1541                 return -1;
1542 
1543         if (kci->stext)
1544                 kci->stext = round_down(kci->stext, page_size);
1545         else
1546                 kci->stext = round_down(kci->first_symbol, page_size);
1547 
1548         if (kci->etext) {
1549                 kci->etext = round_up(kci->etext, page_size);
1550         } else if (kci->last_symbol) {
1551                 kci->etext = round_up(kci->last_symbol, page_size);
1552                 kci->etext += page_size;
1553         }
1554 
1555         kci->first_module = round_down(kci->first_module, page_size);
1556 
1557         if (kci->last_module_symbol) {
1558                 kci->last_module_symbol = round_up(kci->last_module_symbol,
1559                                                    page_size);
1560                 kci->last_module_symbol += page_size;
1561         }
1562 
1563         if (!kci->stext || !kci->etext)
1564                 return -1;
1565 
1566         if (kci->first_module && !kci->last_module_symbol)
1567                 return -1;
1568 
1569         return kcore_copy__read_maps(kci, elf);
1570 }
1571 
1572 static int kcore_copy__copy_file(const char *from_dir, const char *to_dir,
1573                                  const char *name)
1574 {
1575         char from_filename[PATH_MAX];
1576         char to_filename[PATH_MAX];
1577 
1578         scnprintf(from_filename, PATH_MAX, "%s/%s", from_dir, name);
1579         scnprintf(to_filename, PATH_MAX, "%s/%s", to_dir, name);
1580 
1581         return copyfile_mode(from_filename, to_filename, 0400);
1582 }
1583 
1584 static int kcore_copy__unlink(const char *dir, const char *name)
1585 {
1586         char filename[PATH_MAX];
1587 
1588         scnprintf(filename, PATH_MAX, "%s/%s", dir, name);
1589 
1590         return unlink(filename);
1591 }
1592 
1593 static int kcore_copy__compare_fds(int from, int to)
1594 {
1595         char *buf_from;
1596         char *buf_to;
1597         ssize_t ret;
1598         size_t len;
1599         int err = -1;
1600 
1601         buf_from = malloc(page_size);
1602         buf_to = malloc(page_size);
1603         if (!buf_from || !buf_to)
1604                 goto out;
1605 
1606         while (1) {
1607                 /* Use read because mmap won't work on proc files */
1608                 ret = read(from, buf_from, page_size);
1609                 if (ret < 0)
1610                         goto out;
1611 
1612                 if (!ret)
1613                         break;
1614 
1615                 len = ret;
1616 
1617                 if (readn(to, buf_to, len) != (int)len)
1618                         goto out;
1619 
1620                 if (memcmp(buf_from, buf_to, len))
1621                         goto out;
1622         }
1623 
1624         err = 0;
1625 out:
1626         free(buf_to);
1627         free(buf_from);
1628         return err;
1629 }
1630 
1631 static int kcore_copy__compare_files(const char *from_filename,
1632                                      const char *to_filename)
1633 {
1634         int from, to, err = -1;
1635 
1636         from = open(from_filename, O_RDONLY);
1637         if (from < 0)
1638                 return -1;
1639 
1640         to = open(to_filename, O_RDONLY);
1641         if (to < 0)
1642                 goto out_close_from;
1643 
1644         err = kcore_copy__compare_fds(from, to);
1645 
1646         close(to);
1647 out_close_from:
1648         close(from);
1649         return err;
1650 }
1651 
1652 static int kcore_copy__compare_file(const char *from_dir, const char *to_dir,
1653                                     const char *name)
1654 {
1655         char from_filename[PATH_MAX];
1656         char to_filename[PATH_MAX];
1657 
1658         scnprintf(from_filename, PATH_MAX, "%s/%s", from_dir, name);
1659         scnprintf(to_filename, PATH_MAX, "%s/%s", to_dir, name);
1660 
1661         return kcore_copy__compare_files(from_filename, to_filename);
1662 }
1663 
1664 /**
1665  * kcore_copy - copy kallsyms, modules and kcore from one directory to another.
1666  * @from_dir: from directory
1667  * @to_dir: to directory
1668  *
1669  * This function copies kallsyms, modules and kcore files from one directory to
1670  * another.  kallsyms and modules are copied entirely.  Only code segments are
1671  * copied from kcore.  It is assumed that two segments suffice: one for the
1672  * kernel proper and one for all the modules.  The code segments are determined
1673  * from kallsyms and modules files.  The kernel map starts at _stext or the
1674  * lowest function symbol, and ends at _etext or the highest function symbol.
1675  * The module map starts at the lowest module address and ends at the highest
1676  * module symbol.  Start addresses are rounded down to the nearest page.  End
1677  * addresses are rounded up to the nearest page.  An extra page is added to the
1678  * highest kernel symbol and highest module symbol to, hopefully, encompass that
1679  * symbol too.  Because it contains only code sections, the resulting kcore is
1680  * unusual.  One significant peculiarity is that the mapping (start -> pgoff)
1681  * is not the same for the kernel map and the modules map.  That happens because
1682  * the data is copied adjacently whereas the original kcore has gaps.  Finally,
1683  * kallsyms and modules files are compared with their copies to check that
1684  * modules have not been loaded or unloaded while the copies were taking place.
1685  *
1686  * Return: %0 on success, %-1 on failure.
1687  */
1688 int kcore_copy(const char *from_dir, const char *to_dir)
1689 {
1690         struct kcore kcore;
1691         struct kcore extract;
1692         size_t count = 2;
1693         int idx = 0, err = -1;
1694         off_t offset = page_size, sz, modules_offset = 0;
1695         struct kcore_copy_info kci = { .stext = 0, };
1696         char kcore_filename[PATH_MAX];
1697         char extract_filename[PATH_MAX];
1698 
1699         if (kcore_copy__copy_file(from_dir, to_dir, "kallsyms"))
1700                 return -1;
1701 
1702         if (kcore_copy__copy_file(from_dir, to_dir, "modules"))
1703                 goto out_unlink_kallsyms;
1704 
1705         scnprintf(kcore_filename, PATH_MAX, "%s/kcore", from_dir);
1706         scnprintf(extract_filename, PATH_MAX, "%s/kcore", to_dir);
1707 
1708         if (kcore__open(&kcore, kcore_filename))
1709                 goto out_unlink_modules;
1710 
1711         if (kcore_copy__calc_maps(&kci, from_dir, kcore.elf))
1712                 goto out_kcore_close;
1713 
1714         if (kcore__init(&extract, extract_filename, kcore.elfclass, false))
1715                 goto out_kcore_close;
1716 
1717         if (!kci.modules_map.addr)
1718                 count -= 1;
1719 
1720         if (kcore__copy_hdr(&kcore, &extract, count))
1721                 goto out_extract_close;
1722 
1723         if (kcore__add_phdr(&extract, idx++, offset, kci.kernel_map.addr,
1724                             kci.kernel_map.len))
1725                 goto out_extract_close;
1726 
1727         if (kci.modules_map.addr) {
1728                 modules_offset = offset + kci.kernel_map.len;
1729                 if (kcore__add_phdr(&extract, idx, modules_offset,
1730                                     kci.modules_map.addr, kci.modules_map.len))
1731                         goto out_extract_close;
1732         }
1733 
1734         sz = kcore__write(&extract);
1735         if (sz < 0 || sz > offset)
1736                 goto out_extract_close;
1737 
1738         if (copy_bytes(kcore.fd, kci.kernel_map.offset, extract.fd, offset,
1739                        kci.kernel_map.len))
1740                 goto out_extract_close;
1741 
1742         if (modules_offset && copy_bytes(kcore.fd, kci.modules_map.offset,
1743                                          extract.fd, modules_offset,
1744                                          kci.modules_map.len))
1745                 goto out_extract_close;
1746 
1747         if (kcore_copy__compare_file(from_dir, to_dir, "modules"))
1748                 goto out_extract_close;
1749 
1750         if (kcore_copy__compare_file(from_dir, to_dir, "kallsyms"))
1751                 goto out_extract_close;
1752 
1753         err = 0;
1754 
1755 out_extract_close:
1756         kcore__close(&extract);
1757         if (err)
1758                 unlink(extract_filename);
1759 out_kcore_close:
1760         kcore__close(&kcore);
1761 out_unlink_modules:
1762         if (err)
1763                 kcore_copy__unlink(to_dir, "modules");
1764 out_unlink_kallsyms:
1765         if (err)
1766                 kcore_copy__unlink(to_dir, "kallsyms");
1767 
1768         return err;
1769 }
1770 
1771 int kcore_extract__create(struct kcore_extract *kce)
1772 {
1773         struct kcore kcore;
1774         struct kcore extract;
1775         size_t count = 1;
1776         int idx = 0, err = -1;
1777         off_t offset = page_size, sz;
1778 
1779         if (kcore__open(&kcore, kce->kcore_filename))
1780                 return -1;
1781 
1782         strcpy(kce->extract_filename, PERF_KCORE_EXTRACT);
1783         if (kcore__init(&extract, kce->extract_filename, kcore.elfclass, true))
1784                 goto out_kcore_close;
1785 
1786         if (kcore__copy_hdr(&kcore, &extract, count))
1787                 goto out_extract_close;
1788 
1789         if (kcore__add_phdr(&extract, idx, offset, kce->addr, kce->len))
1790                 goto out_extract_close;
1791 
1792         sz = kcore__write(&extract);
1793         if (sz < 0 || sz > offset)
1794                 goto out_extract_close;
1795 
1796         if (copy_bytes(kcore.fd, kce->offs, extract.fd, offset, kce->len))
1797                 goto out_extract_close;
1798 
1799         err = 0;
1800 
1801 out_extract_close:
1802         kcore__close(&extract);
1803         if (err)
1804                 unlink(kce->extract_filename);
1805 out_kcore_close:
1806         kcore__close(&kcore);
1807 
1808         return err;
1809 }
1810 
1811 void kcore_extract__delete(struct kcore_extract *kce)
1812 {
1813         unlink(kce->extract_filename);
1814 }
1815 
1816 #ifdef HAVE_GELF_GETNOTE_SUPPORT
1817 /**
1818  * populate_sdt_note : Parse raw data and identify SDT note
1819  * @elf: elf of the opened file
1820  * @data: raw data of a section with description offset applied
1821  * @len: note description size
1822  * @type: type of the note
1823  * @sdt_notes: List to add the SDT note
1824  *
1825  * Responsible for parsing the @data in section .note.stapsdt in @elf and
1826  * if its an SDT note, it appends to @sdt_notes list.
1827  */
1828 static int populate_sdt_note(Elf **elf, const char *data, size_t len,
1829                              struct list_head *sdt_notes)
1830 {
1831         const char *provider, *name;
1832         struct sdt_note *tmp = NULL;
1833         GElf_Ehdr ehdr;
1834         GElf_Addr base_off = 0;
1835         GElf_Shdr shdr;
1836         int ret = -EINVAL;
1837 
1838         union {
1839                 Elf64_Addr a64[NR_ADDR];
1840                 Elf32_Addr a32[NR_ADDR];
1841         } buf;
1842 
1843         Elf_Data dst = {
1844                 .d_buf = &buf, .d_type = ELF_T_ADDR, .d_version = EV_CURRENT,
1845                 .d_size = gelf_fsize((*elf), ELF_T_ADDR, NR_ADDR, EV_CURRENT),
1846                 .d_off = 0, .d_align = 0
1847         };
1848         Elf_Data src = {
1849                 .d_buf = (void *) data, .d_type = ELF_T_ADDR,
1850                 .d_version = EV_CURRENT, .d_size = dst.d_size, .d_off = 0,
1851                 .d_align = 0
1852         };
1853 
1854         tmp = (struct sdt_note *)calloc(1, sizeof(struct sdt_note));
1855         if (!tmp) {
1856                 ret = -ENOMEM;
1857                 goto out_err;
1858         }
1859 
1860         INIT_LIST_HEAD(&tmp->note_list);
1861 
1862         if (len < dst.d_size + 3)
1863                 goto out_free_note;
1864 
1865         /* Translation from file representation to memory representation */
1866         if (gelf_xlatetom(*elf, &dst, &src,
1867                           elf_getident(*elf, NULL)[EI_DATA]) == NULL) {
1868                 pr_err("gelf_xlatetom : %s\n", elf_errmsg(-1));
1869                 goto out_free_note;
1870         }
1871 
1872         /* Populate the fields of sdt_note */
1873         provider = data + dst.d_size;
1874 
1875         name = (const char *)memchr(provider, '\0', data + len - provider);
1876         if (name++ == NULL)
1877                 goto out_free_note;
1878 
1879         tmp->provider = strdup(provider);
1880         if (!tmp->provider) {
1881                 ret = -ENOMEM;
1882                 goto out_free_note;
1883         }
1884         tmp->name = strdup(name);
1885         if (!tmp->name) {
1886                 ret = -ENOMEM;
1887                 goto out_free_prov;
1888         }
1889 
1890         if (gelf_getclass(*elf) == ELFCLASS32) {
1891                 memcpy(&tmp->addr, &buf, 3 * sizeof(Elf32_Addr));
1892                 tmp->bit32 = true;
1893         } else {
1894                 memcpy(&tmp->addr, &buf, 3 * sizeof(Elf64_Addr));
1895                 tmp->bit32 = false;
1896         }
1897 
1898         if (!gelf_getehdr(*elf, &ehdr)) {
1899                 pr_debug("%s : cannot get elf header.\n", __func__);
1900                 ret = -EBADF;
1901                 goto out_free_name;
1902         }
1903 
1904         /* Adjust the prelink effect :
1905          * Find out the .stapsdt.base section.
1906          * This scn will help us to handle prelinking (if present).
1907          * Compare the retrieved file offset of the base section with the
1908          * base address in the description of the SDT note. If its different,
1909          * then accordingly, adjust the note location.
1910          */
1911         if (elf_section_by_name(*elf, &ehdr, &shdr, SDT_BASE_SCN, NULL)) {
1912                 base_off = shdr.sh_offset;
1913                 if (base_off) {
1914                         if (tmp->bit32)
1915                                 tmp->addr.a32[0] = tmp->addr.a32[0] + base_off -
1916                                         tmp->addr.a32[1];
1917                         else
1918                                 tmp->addr.a64[0] = tmp->addr.a64[0] + base_off -
1919                                         tmp->addr.a64[1];
1920                 }
1921         }
1922 
1923         list_add_tail(&tmp->note_list, sdt_notes);
1924         return 0;
1925 
1926 out_free_name:
1927         free(tmp->name);
1928 out_free_prov:
1929         free(tmp->provider);
1930 out_free_note:
1931         free(tmp);
1932 out_err:
1933         return ret;
1934 }
1935 
1936 /**
1937  * construct_sdt_notes_list : constructs a list of SDT notes
1938  * @elf : elf to look into
1939  * @sdt_notes : empty list_head
1940  *
1941  * Scans the sections in 'elf' for the section
1942  * .note.stapsdt. It, then calls populate_sdt_note to find
1943  * out the SDT events and populates the 'sdt_notes'.
1944  */
1945 static int construct_sdt_notes_list(Elf *elf, struct list_head *sdt_notes)
1946 {
1947         GElf_Ehdr ehdr;
1948         Elf_Scn *scn = NULL;
1949         Elf_Data *data;
1950         GElf_Shdr shdr;
1951         size_t shstrndx, next;
1952         GElf_Nhdr nhdr;
1953         size_t name_off, desc_off, offset;
1954         int ret = 0;
1955 
1956         if (gelf_getehdr(elf, &ehdr) == NULL) {
1957                 ret = -EBADF;
1958                 goto out_ret;
1959         }
1960         if (elf_getshdrstrndx(elf, &shstrndx) != 0) {
1961                 ret = -EBADF;
1962                 goto out_ret;
1963         }
1964 
1965         /* Look for the required section */
1966         scn = elf_section_by_name(elf, &ehdr, &shdr, SDT_NOTE_SCN, NULL);
1967         if (!scn) {
1968                 ret = -ENOENT;
1969                 goto out_ret;
1970         }
1971 
1972         if ((shdr.sh_type != SHT_NOTE) || (shdr.sh_flags & SHF_ALLOC)) {
1973                 ret = -ENOENT;
1974                 goto out_ret;
1975         }
1976 
1977         data = elf_getdata(scn, NULL);
1978 
1979         /* Get the SDT notes */
1980         for (offset = 0; (next = gelf_getnote(data, offset, &nhdr, &name_off,
1981                                               &desc_off)) > 0; offset = next) {
1982                 if (nhdr.n_namesz == sizeof(SDT_NOTE_NAME) &&
1983                     !memcmp(data->d_buf + name_off, SDT_NOTE_NAME,
1984                             sizeof(SDT_NOTE_NAME))) {
1985                         /* Check the type of the note */
1986                         if (nhdr.n_type != SDT_NOTE_TYPE)
1987                                 goto out_ret;
1988 
1989                         ret = populate_sdt_note(&elf, ((data->d_buf) + desc_off),
1990                                                 nhdr.n_descsz, sdt_notes);
1991                         if (ret < 0)
1992                                 goto out_ret;
1993                 }
1994         }
1995         if (list_empty(sdt_notes))
1996                 ret = -ENOENT;
1997 
1998 out_ret:
1999         return ret;
2000 }
2001 
2002 /**
2003  * get_sdt_note_list : Wrapper to construct a list of sdt notes
2004  * @head : empty list_head
2005  * @target : file to find SDT notes from
2006  *
2007  * This opens the file, initializes
2008  * the ELF and then calls construct_sdt_notes_list.
2009  */
2010 int get_sdt_note_list(struct list_head *head, const char *target)
2011 {
2012         Elf *elf;
2013         int fd, ret;
2014 
2015         fd = open(target, O_RDONLY);
2016         if (fd < 0)
2017                 return -EBADF;
2018 
2019         elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
2020         if (!elf) {
2021                 ret = -EBADF;
2022                 goto out_close;
2023         }
2024         ret = construct_sdt_notes_list(elf, head);
2025         elf_end(elf);
2026 out_close:
2027         close(fd);
2028         return ret;
2029 }
2030 
2031 /**
2032  * cleanup_sdt_note_list : free the sdt notes' list
2033  * @sdt_notes: sdt notes' list
2034  *
2035  * Free up the SDT notes in @sdt_notes.
2036  * Returns the number of SDT notes free'd.
2037  */
2038 int cleanup_sdt_note_list(struct list_head *sdt_notes)
2039 {
2040         struct sdt_note *tmp, *pos;
2041         int nr_free = 0;
2042 
2043         list_for_each_entry_safe(pos, tmp, sdt_notes, note_list) {
2044                 list_del(&pos->note_list);
2045                 free(pos->name);
2046                 free(pos->provider);
2047                 free(pos);
2048                 nr_free++;
2049         }
2050         return nr_free;
2051 }
2052 
2053 /**
2054  * sdt_notes__get_count: Counts the number of sdt events
2055  * @start: list_head to sdt_notes list
2056  *
2057  * Returns the number of SDT notes in a list
2058  */
2059 int sdt_notes__get_count(struct list_head *start)
2060 {
2061         struct sdt_note *sdt_ptr;
2062         int count = 0;
2063 
2064         list_for_each_entry(sdt_ptr, start, note_list)
2065                 count++;
2066         return count;
2067 }
2068 #endif
2069 
2070 void symbol__elf_init(void)
2071 {
2072         elf_version(EV_CURRENT);
2073 }
2074 

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