20 #include "pthread_impl.h"
24 static char errbuf[128];
28 #if ULONG_MAX == 0xffffffff
29 typedef Elf32_Ehdr Ehdr;
30 typedef Elf32_Phdr Phdr;
31 typedef Elf32_Sym Sym;
32 #define R_TYPE(x) ((x)&255)
33 #define R_SYM(x) ((x)>>8)
35 typedef Elf64_Ehdr Ehdr;
36 typedef Elf64_Phdr Phdr;
37 typedef Elf64_Sym Sym;
38 #define R_TYPE(x) ((x)&0xffffffff)
39 #define R_SYM(x) ((x)>>32)
42 #define MAXP2(a,b) (-(-(a)&-(b)))
43 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
55 struct td_index *next;
62 struct dso *next, *prev;
81 struct dso **deps, *needed_by;
82 char *rpath_orig, *rpath;
84 size_t tls_len, tls_size, tls_align, tls_id, tls_offset;
85 size_t relro_start, relro_end;
87 unsigned char *new_tls;
88 volatile int new_dtv_idx, new_tls_idx;
89 struct td_index *td_index;
90 struct dso *fini_next;
110 REL_TLS, /* everything past here is TLS */
120 int __init_tp(void *);
121 void __init_libc(char **, char *);
123 const char *__libc_get_version(void);
125 static struct builtin_tls {
130 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
132 static struct dso *head, *tail, *ldso, *fini_head;
133 static char *env_path, *sys_path;
134 static unsigned long long gencnt;
137 static int ldso_fail;
139 static jmp_buf *rtld_fail;
140 static pthread_rwlock_t lock;
141 static struct debug debug;
142 static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
143 static size_t static_tls_cnt;
144 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
146 struct debug *_dl_debug_addr = &debug;
151 static void decode_vec(size_t *v, size_t *a, size_t cnt)
153 memset(a, 0, cnt*sizeof(size_t));
154 for (; v[0]; v+=2) if (v[0]<cnt) {
160 static int search_vec(size_t *v, size_t *r, size_t key)
162 for (; v[0]!=key; v+=2)
168 static void error(const char *fmt, ...)
172 vsnprintf(errbuf, sizeof errbuf, fmt, ap);
174 if (runtime) longjmp(*rtld_fail, 1);
175 dprintf(2, "%s\n", errbuf);
179 static uint32_t sysv_hash(const char *s0)
181 const unsigned char *s = (void *)s0;
187 return h & 0xfffffff;
190 static uint32_t gnu_hash(const char *s0)
192 const unsigned char *s = (void *)s0;
193 uint_fast32_t h = 5381;
199 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
202 Sym *syms = dso->syms;
203 uint32_t *hashtab = dso->hashtab;
204 char *strings = dso->strings;
205 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
206 if ((!dso->versym || dso->versym[i] >= 0)
207 && (!strcmp(s, strings+syms[i].st_name)))
213 static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
215 Sym *syms = dso->syms;
216 char *strings = dso->strings;
217 uint32_t *hashtab = dso->ghashtab;
218 uint32_t nbuckets = hashtab[0];
219 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
222 uint32_t i = buckets[h1 % nbuckets];
226 hashval = buckets + nbuckets + (i - hashtab[1]);
228 for (h1 |= 1; ; i++) {
230 if ((!dso->versym || dso->versym[i] >= 0)
231 && (h1 == (h2|1)) && !strcmp(s, strings + syms[i].st_name))
239 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
240 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
242 #ifndef ARCH_SYM_REJECT_UND
243 #define ARCH_SYM_REJECT_UND(s) 0
246 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
248 uint32_t h = 0, gh = 0;
249 struct symdef def = {0};
250 for (; dso; dso=dso->next) {
252 if (!dso->global) continue;
254 if (!gh) gh = gnu_hash(s);
255 sym = gnu_lookup(s, gh, dso);
257 if (!h) h = sysv_hash(s);
258 sym = sysv_lookup(s, h, dso);
262 if (need_def || (sym->st_info&0xf) == STT_TLS
263 || ARCH_SYM_REJECT_UND(sym))
266 if ((sym->st_info&0xf) != STT_TLS)
268 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
269 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
271 if (def.sym && sym->st_info>>4 == STB_WEAK) continue;
274 if (sym->st_info>>4 == STB_GLOBAL) break;
279 #define NO_INLINE_ADDEND (1<<REL_COPY | 1<<REL_GOT | 1<<REL_PLT)
281 ptrdiff_t __tlsdesc_static(), __tlsdesc_dynamic();
283 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
285 unsigned char *base = dso->base;
286 Sym *syms = dso->syms;
287 char *strings = dso->strings;
299 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
300 astype = R_TYPE(rel[1]);
301 if (!astype) continue;
302 type = remap_rel(astype);
304 error("Error relocating %s: unsupported relocation type %d",
308 sym_index = R_SYM(rel[1]);
309 reloc_addr = (void *)(base + rel[0]);
311 sym = syms + sym_index;
312 name = strings + sym->st_name;
313 ctx = type==REL_COPY ? head->next : head;
314 def = find_sym(ctx, name, type==REL_PLT);
315 if (!def.sym && (sym->st_shndx != SHN_UNDEF
316 || sym->st_info>>4 != STB_WEAK)) {
317 error("Error relocating %s: %s: symbol not found",
327 addend = stride>2 ? rel[2]
328 : (1<<type & NO_INLINE_ADDEND) ? 0
331 sym_val = def.sym ? (size_t)def.dso->base+def.sym->st_value : 0;
332 tls_val = def.sym ? def.sym->st_value : 0;
336 addend -= (size_t)reloc_addr;
340 *reloc_addr = sym_val + addend;
343 *reloc_addr = (size_t)base + addend;
346 if (sym) *reloc_addr = sym_val + addend;
347 else *reloc_addr = (size_t)base + addend;
350 memcpy(reloc_addr, (void *)sym_val, sym->st_size);
353 *(uint32_t *)reloc_addr = sym_val + addend
354 - (size_t)reloc_addr;
357 *reloc_addr = def.dso->tls_id;
360 *reloc_addr = tls_val + addend;
364 *reloc_addr = tls_val + def.dso->tls_offset + TPOFF_K + addend;
368 *reloc_addr = tls_val - def.dso->tls_offset + addend;
371 *reloc_addr = def.dso->tls_offset - tls_val + addend;
375 if (stride<3) addend = reloc_addr[1];
376 if (runtime && def.dso->tls_id >= static_tls_cnt) {
377 struct td_index *new = malloc(sizeof *new);
379 "Error relocating %s: cannot allocate TLSDESC for %s",
380 dso->name, sym ? name : "(local)" );
381 new->next = dso->td_index;
383 new->args[0] = def.dso->tls_id;
384 new->args[1] = tls_val + addend;
385 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
386 reloc_addr[1] = (size_t)new;
388 reloc_addr[0] = (size_t)__tlsdesc_static;
390 reloc_addr[1] = tls_val + def.dso->tls_offset
393 reloc_addr[1] = tls_val - def.dso->tls_offset
402 /* A huge hack: to make up for the wastefulness of shared libraries
403 * needing at least a page of dirty memory even if they have no global
404 * data, we reclaim the gaps at the beginning and end of writable maps
405 * and "donate" them to the heap by setting up minimal malloc
406 * structures and then freeing them. */
408 static void reclaim(struct dso *dso, size_t start, size_t end)
411 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
412 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
413 start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
414 end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
415 if (start>end || end-start < 4*sizeof(size_t)) return;
416 a = (size_t *)(dso->base + start);
417 z = (size_t *)(dso->base + end);
419 a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
424 static void reclaim_gaps(struct dso *dso)
426 Phdr *ph = dso->phdr;
427 size_t phcnt = dso->phnum;
429 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
430 if (ph->p_type!=PT_LOAD) continue;
431 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
432 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
433 reclaim(dso, ph->p_vaddr+ph->p_memsz,
434 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
438 static void *map_library(int fd, struct dso *dso)
440 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
441 void *allocated_buf=0;
443 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
444 size_t this_min, this_max;
449 unsigned char *map=MAP_FAILED, *base;
454 ssize_t l = read(fd, buf, sizeof buf);
457 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
459 phsize = eh->e_phentsize * eh->e_phnum;
460 if (phsize > sizeof buf - sizeof *eh) {
461 allocated_buf = malloc(phsize);
462 if (!allocated_buf) return 0;
463 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
464 if (l < 0) goto error;
465 if (l != phsize) goto noexec;
466 ph = ph0 = allocated_buf;
467 } else if (eh->e_phoff + phsize > l) {
468 l = pread(fd, buf+1, phsize, eh->e_phoff);
469 if (l < 0) goto error;
470 if (l != phsize) goto noexec;
471 ph = ph0 = (void *)(buf + 1);
473 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
475 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
476 if (ph->p_type == PT_DYNAMIC) {
478 } else if (ph->p_type == PT_TLS) {
479 tls_image = ph->p_vaddr;
480 dso->tls_align = ph->p_align;
481 dso->tls_len = ph->p_filesz;
482 dso->tls_size = ph->p_memsz;
483 } else if (ph->p_type == PT_GNU_RELRO) {
484 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
485 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
487 if (ph->p_type != PT_LOAD) continue;
488 if (ph->p_vaddr < addr_min) {
489 addr_min = ph->p_vaddr;
490 off_start = ph->p_offset;
491 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
492 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
493 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
495 if (ph->p_vaddr+ph->p_memsz > addr_max) {
496 addr_max = ph->p_vaddr+ph->p_memsz;
499 if (!dyn) goto noexec;
500 addr_max += PAGE_SIZE-1;
501 addr_max &= -PAGE_SIZE;
502 addr_min &= -PAGE_SIZE;
503 off_start &= -PAGE_SIZE;
504 map_len = addr_max - addr_min + off_start;
505 /* The first time, we map too much, possibly even more than
506 * the length of the file. This is okay because we will not
507 * use the invalid part; we just need to reserve the right
508 * amount of virtual address space to map over later. */
509 map = mmap((void *)addr_min, map_len, prot, MAP_PRIVATE, fd, off_start);
510 if (map==MAP_FAILED) goto error;
511 /* If the loaded file is not relocatable and the requested address is
512 * not available, then the load operation must fail. */
513 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
517 base = map - addr_min;
520 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
521 if (ph->p_type != PT_LOAD) continue;
522 /* Check if the programs headers are in this load segment, and
523 * if so, record the address for use by dl_iterate_phdr. */
524 if (!dso->phdr && eh->e_phoff >= ph->p_offset
525 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
526 dso->phdr = (void *)(base + ph->p_vaddr
527 + (eh->e_phoff-ph->p_offset));
528 dso->phnum = eh->e_phnum;
529 dso->phentsize = eh->e_phentsize;
531 /* Reuse the existing mapping for the lowest-address LOAD */
532 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min) continue;
533 this_min = ph->p_vaddr & -PAGE_SIZE;
534 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
535 off_start = ph->p_offset & -PAGE_SIZE;
536 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
537 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
538 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
539 if (mmap(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
541 if (ph->p_memsz > ph->p_filesz) {
542 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
543 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
544 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
545 if (pgbrk-(size_t)base < this_max && mmap((void *)pgbrk, (size_t)base+this_max-pgbrk, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED)
549 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
550 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
551 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC) < 0)
556 dso->map_len = map_len;
558 dso->dynv = (void *)(base+dyn);
559 if (dso->tls_size) dso->tls_image = (void *)(base+tls_image);
560 if (!runtime) reclaim_gaps(dso);
566 if (map!=MAP_FAILED) munmap(map, map_len);
571 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
576 s += strspn(s, ":\n");
577 l = strcspn(s, ":\n");
578 if (l-1 >= INT_MAX) return -1;
579 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
580 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
588 /* Any negative value but -1 will inhibit
589 * futher path search. */
597 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
600 const char *s, *t, *origin;
602 if (p->rpath) return 0;
603 if (!p->rpath_orig) return -1;
604 if (!strchr(p->rpath_orig, '$')) {
605 p->rpath = p->rpath_orig;
610 while ((t=strchr(s, '$'))) {
611 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
616 if (n > SSIZE_MAX/PATH_MAX) return -1;
618 if (p->kernel_mapped) {
619 /* $ORIGIN searches cannot be performed for the main program
620 * when it is suid/sgid/AT_SECURE. This is because the
621 * pathname is under the control of the caller of execve.
622 * For libraries, however, $ORIGIN can be processed safely
623 * since the library's pathname came from a trusted source
624 * (either system paths or a call to dlopen). */
627 l = readlink("/proc/self/exe", buf, buf_size);
635 t = strrchr(origin, '/');
636 l = t ? t-origin : 0;
637 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
638 if (!p->rpath) return -1;
642 while ((t=strchr(s, '$'))) {
645 memcpy(d, origin, l);
647 /* It was determined previously that the '$' is followed
648 * either by "ORIGIN" or "{ORIGIN}". */
649 s = t + 7 + 2*(t[1]=='{');
655 static void decode_dyn(struct dso *p)
657 size_t dyn[DYN_CNT] = {0};
658 decode_vec(p->dynv, dyn, DYN_CNT);
659 p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
660 p->strings = (void *)(p->base + dyn[DT_STRTAB]);
661 if (dyn[0]&(1<<DT_HASH))
662 p->hashtab = (void *)(p->base + dyn[DT_HASH]);
663 if (dyn[0]&(1<<DT_RPATH))
664 p->rpath_orig = (void *)(p->strings + dyn[DT_RPATH]);
665 if (dyn[0]&(1<<DT_RUNPATH))
666 p->rpath_orig = (void *)(p->strings + dyn[DT_RUNPATH]);
667 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
668 p->ghashtab = (void *)(p->base + *dyn);
669 if (search_vec(p->dynv, dyn, DT_VERSYM))
670 p->versym = (void *)(p->base + *dyn);
673 static struct dso *load_library(const char *name, struct dso *needed_by)
675 char buf[2*NAME_MAX+2];
676 const char *pathname;
678 struct dso *p, temp_dso = {0};
690 /* Catch and block attempts to reload the implementation itself */
691 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
692 static const char *rp, reserved[] =
693 "c\0pthread\0rt\0m\0dl\0util\0xnet\0";
694 char *z = strchr(name, '.');
697 for (rp=reserved; *rp && strncmp(name+3, rp, l-3); rp+=strlen(rp)+1);
700 /* Track which names have been resolved
701 * and only report each one once. */
702 static unsigned reported;
703 unsigned mask = 1U<<(rp-reserved);
704 if (!(reported & mask)) {
706 dprintf(1, "\t%s => %s (%p)\n",
715 if (!strcmp(name, ldso->name)) is_self = 1;
720 tail = ldso->next ? ldso->next : ldso;
724 if (strchr(name, '/')) {
726 fd = open(name, O_RDONLY|O_CLOEXEC);
728 /* Search for the name to see if it's already loaded */
729 for (p=head->next; p; p=p->next) {
730 if (p->shortname && !strcmp(p->shortname, name)) {
735 if (strlen(name) > NAME_MAX) return 0;
737 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
738 for (p=needed_by; fd == -1 && p; p=p->needed_by)
739 if (!fixup_rpath(p, buf, sizeof buf))
740 fd = path_open(name, p->rpath, buf, sizeof buf);
745 if (ldso->name[0]=='/') {
747 for (s=t=z=ldso->name; *s; s++)
748 if (*s=='/') z=t, t=s;
749 prefix_len = z-ldso->name;
750 if (prefix_len < PATH_MAX)
757 char etc_ldso_path[prefix_len + 1
758 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
759 snprintf(etc_ldso_path, sizeof etc_ldso_path,
760 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
761 (int)prefix_len, prefix);
762 FILE *f = fopen(etc_ldso_path, "rbe");
764 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
769 } else if (errno != ENOENT) {
773 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
774 fd = path_open(name, sys_path, buf, sizeof buf);
778 if (fd < 0) return 0;
779 if (fstat(fd, &st) < 0) {
783 for (p=head->next; p; p=p->next) {
784 if (p->dev == st.st_dev && p->ino == st.st_ino) {
785 /* If this library was previously loaded with a
786 * pathname but a search found the same inode,
787 * setup its shortname so it can be found by name. */
788 if (!p->shortname && pathname != name)
789 p->shortname = strrchr(p->name, '/')+1;
795 map = noload ? 0 : map_library(fd, &temp_dso);
799 /* Allocate storage for the new DSO. When there is TLS, this
800 * storage must include a reservation for all pre-existing
801 * threads to obtain copies of both the new TLS, and an
802 * extended DTV capable of storing an additional slot for
803 * the newly-loaded DSO. */
804 alloc_size = sizeof *p + strlen(pathname) + 1;
805 if (runtime && temp_dso.tls_image) {
806 size_t per_th = temp_dso.tls_size + temp_dso.tls_align
807 + sizeof(void *) * (tls_cnt+3);
808 n_th = libc.threads_minus_1 + 1;
809 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
810 else alloc_size += n_th * per_th;
812 p = calloc(1, alloc_size);
814 munmap(map, temp_dso.map_len);
817 memcpy(p, &temp_dso, sizeof temp_dso);
822 p->needed_by = needed_by;
824 strcpy(p->name, pathname);
825 /* Add a shortname only if name arg was not an explicit pathname. */
826 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
828 if (runtime && !libc.has_thread_pointer) {
829 munmap(map, p->map_len);
834 p->tls_id = ++tls_cnt;
835 tls_align = MAXP2(tls_align, p->tls_align);
837 p->tls_offset = tls_offset + ( (tls_align-1) &
838 -(tls_offset + (uintptr_t)p->tls_image) );
839 tls_offset += p->tls_size;
841 tls_offset += p->tls_size + p->tls_align - 1;
842 tls_offset -= (tls_offset + (uintptr_t)p->tls_image)
844 p->tls_offset = tls_offset;
846 p->new_dtv = (void *)(-sizeof(size_t) &
847 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
848 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
855 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
860 static void load_deps(struct dso *p)
863 struct dso ***deps = &p->deps, **tmp, *dep;
864 for (; p; p=p->next) {
865 for (i=0; p->dynv[i]; i+=2) {
866 if (p->dynv[i] != DT_NEEDED) continue;
867 dep = load_library(p->strings + p->dynv[i+1], p);
869 error("Error loading shared library %s: %m (needed by %s)",
870 p->strings + p->dynv[i+1], p->name);
874 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
875 if (!tmp) longjmp(*rtld_fail, 1);
884 static void load_preload(char *s)
889 for ( ; *s && (isspace(*s) || *s==':'); s++);
890 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
898 static void make_global(struct dso *p)
900 for (; p; p=p->next) p->global = 1;
903 static void reloc_all(struct dso *p)
905 size_t dyn[DYN_CNT] = {0};
906 for (; p; p=p->next) {
907 if (p->relocated) continue;
908 decode_vec(p->dynv, dyn, DYN_CNT);
909 #ifdef NEED_ARCH_RELOCS
910 do_arch_relocs(p, head);
912 do_relocs(p, (void *)(p->base+dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
913 2+(dyn[DT_PLTREL]==DT_RELA));
914 do_relocs(p, (void *)(p->base+dyn[DT_REL]), dyn[DT_RELSZ], 2);
915 do_relocs(p, (void *)(p->base+dyn[DT_RELA]), dyn[DT_RELASZ], 3);
917 if (p->relro_start != p->relro_end &&
918 mprotect(p->base+p->relro_start, p->relro_end-p->relro_start, PROT_READ) < 0) {
919 error("Error relocating %s: RELRO protection failed: %m",
927 static void kernel_mapped_dso(struct dso *p)
929 size_t min_addr = -1, max_addr = 0, cnt;
931 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
932 if (ph->p_type == PT_DYNAMIC) {
933 p->dynv = (void *)(p->base + ph->p_vaddr);
934 } else if (ph->p_type == PT_GNU_RELRO) {
935 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
936 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
938 if (ph->p_type != PT_LOAD) continue;
939 if (ph->p_vaddr < min_addr)
940 min_addr = ph->p_vaddr;
941 if (ph->p_vaddr+ph->p_memsz > max_addr)
942 max_addr = ph->p_vaddr+ph->p_memsz;
944 min_addr &= -PAGE_SIZE;
945 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
946 p->map = p->base + min_addr;
947 p->map_len = max_addr - min_addr;
948 p->kernel_mapped = 1;
951 static void do_fini()
954 size_t dyn[DYN_CNT] = {0};
955 for (p=fini_head; p; p=p->fini_next) {
956 if (!p->constructed) continue;
957 decode_vec(p->dynv, dyn, DYN_CNT);
958 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
959 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
960 size_t *fn = (size_t *)(p->base + dyn[DT_FINI_ARRAY])+n;
961 while (n--) ((void (*)(void))*--fn)();
963 #ifndef NO_LEGACY_INITFINI
964 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
965 ((void (*)(void))(p->base + dyn[DT_FINI]))();
970 static void do_init_fini(struct dso *p)
972 size_t dyn[DYN_CNT] = {0};
973 int need_locking = libc.threads_minus_1;
974 /* Allow recursive calls that arise when a library calls
975 * dlopen from one of its constructors, but block any
976 * other threads until all ctors have finished. */
977 if (need_locking) pthread_mutex_lock(&init_fini_lock);
978 for (; p; p=p->prev) {
979 if (p->constructed) continue;
981 decode_vec(p->dynv, dyn, DYN_CNT);
982 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
983 p->fini_next = fini_head;
986 #ifndef NO_LEGACY_INITFINI
987 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
988 ((void (*)(void))(p->base + dyn[DT_INIT]))();
990 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
991 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
992 size_t *fn = (void *)(p->base + dyn[DT_INIT_ARRAY]);
993 while (n--) ((void (*)(void))*fn++)();
995 if (!need_locking && libc.threads_minus_1) {
997 pthread_mutex_lock(&init_fini_lock);
1000 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
1003 void _dl_debug_state(void)
1009 pthread_t self = __pthread_self();
1011 for (p=head; p; p=p->next) {
1012 if (!p->tls_id || !self->dtv[p->tls_id]) continue;
1013 memcpy(self->dtv[p->tls_id], p->tls_image, p->tls_len);
1014 memset((char *)self->dtv[p->tls_id]+p->tls_len, 0,
1015 p->tls_size - p->tls_len);
1016 if (p->tls_id == (size_t)self->dtv[0]) break;
1020 void *__copy_tls(unsigned char *mem)
1025 void **dtv = (void *)mem;
1026 dtv[0] = (void *)tls_cnt;
1028 td = (void *)(dtv+1);
1029 td->dtv = td->dtv_copy = dtv;
1034 mem += sizeof(void *) * (tls_cnt+1);
1035 mem += -((uintptr_t)mem + sizeof(struct pthread)) & (tls_align-1);
1036 td = (pthread_t)mem;
1037 mem += sizeof(struct pthread);
1039 for (p=head; p; p=p->next) {
1040 if (!p->tls_id) continue;
1041 dtv[p->tls_id] = mem + p->tls_offset;
1042 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
1045 mem += libc.tls_size - sizeof(struct pthread);
1046 mem -= (uintptr_t)mem & (tls_align-1);
1047 td = (pthread_t)mem;
1049 for (p=head; p; p=p->next) {
1050 if (!p->tls_id) continue;
1051 dtv[p->tls_id] = mem - p->tls_offset;
1052 memcpy(dtv[p->tls_id], p->tls_image, p->tls_len);
1055 td->dtv = td->dtv_copy = dtv;
1059 void *__tls_get_new(size_t *v)
1061 pthread_t self = __pthread_self();
1063 /* Block signals to make accessing new TLS async-signal-safe */
1065 __block_all_sigs(&set);
1066 if (v[0]<=(size_t)self->dtv[0]) {
1067 __restore_sigs(&set);
1068 return (char *)self->dtv[v[0]]+v[1];
1071 /* This is safe without any locks held because, if the caller
1072 * is able to request the Nth entry of the DTV, the DSO list
1073 * must be valid at least that far out and it was synchronized
1074 * at program startup or by an already-completed call to dlopen. */
1076 for (p=head; p->tls_id != v[0]; p=p->next);
1078 /* Get new DTV space from new DSO if needed */
1079 if (v[0] > (size_t)self->dtv[0]) {
1080 void **newdtv = p->new_dtv +
1081 (v[0]+1)*sizeof(void *)*a_fetch_add(&p->new_dtv_idx,1);
1082 memcpy(newdtv, self->dtv,
1083 ((size_t)self->dtv[0]+1) * sizeof(void *));
1084 newdtv[0] = (void *)v[0];
1085 self->dtv = self->dtv_copy = newdtv;
1088 /* Get new TLS memory from all new DSOs up to the requested one */
1090 for (p=head; ; p=p->next) {
1091 if (!p->tls_id || self->dtv[p->tls_id]) continue;
1092 mem = p->new_tls + (p->tls_size + p->tls_align)
1093 * a_fetch_add(&p->new_tls_idx,1);
1094 mem += ((uintptr_t)p->tls_image - (uintptr_t)mem)
1096 self->dtv[p->tls_id] = mem;
1097 memcpy(mem, p->tls_image, p->tls_len);
1098 if (p->tls_id == v[0]) break;
1100 __restore_sigs(&set);
1104 static void update_tls_size()
1106 libc.tls_size = ALIGN(
1107 (1+tls_cnt) * sizeof(void *) +
1109 sizeof(struct pthread) +
1114 void *__dynlink(int argc, char **argv)
1116 size_t aux[AUX_CNT] = {0};
1120 static struct dso builtin_dsos[3];
1121 struct dso *const app = builtin_dsos+0;
1122 struct dso *const lib = builtin_dsos+1;
1123 struct dso *const vdso = builtin_dsos+2;
1124 char *env_preload=0;
1127 char **envp = argv+argc+1;
1130 /* Find aux vector just past environ[] */
1131 for (i=argc+1; argv[i]; i++)
1132 if (!memcmp(argv[i], "LD_LIBRARY_PATH=", 16))
1133 env_path = argv[i]+16;
1134 else if (!memcmp(argv[i], "LD_PRELOAD=", 11))
1135 env_preload = argv[i]+11;
1136 auxv = (void *)(argv+i+1);
1138 decode_vec(auxv, aux, AUX_CNT);
1140 /* Only trust user/env if kernel says we're not suid/sgid */
1141 if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1142 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]) {
1147 libc.page_size = aux[AT_PAGESZ];
1150 /* If the dynamic linker was invoked as a program itself, AT_BASE
1151 * will not be set. In that case, we assume the base address is
1152 * the start of the page containing the PHDRs; I don't know any
1153 * better approach... */
1154 if (!aux[AT_BASE]) {
1155 aux[AT_BASE] = aux[AT_PHDR] & -PAGE_SIZE;
1156 aux[AT_PHDR] = aux[AT_PHENT] = aux[AT_PHNUM] = 0;
1159 /* The dynamic linker load address is passed by the kernel
1160 * in the AUX vector, so this is easy. */
1161 lib->base = (void *)aux[AT_BASE];
1162 lib->name = lib->shortname = "libc.so";
1164 ehdr = (void *)lib->base;
1165 lib->phnum = ehdr->e_phnum;
1166 lib->phdr = (void *)(aux[AT_BASE]+ehdr->e_phoff);
1167 lib->phentsize = ehdr->e_phentsize;
1168 kernel_mapped_dso(lib);
1172 size_t interp_off = 0;
1173 size_t tls_image = 0;
1174 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1175 app->phdr = phdr = (void *)aux[AT_PHDR];
1176 app->phnum = aux[AT_PHNUM];
1177 app->phentsize = aux[AT_PHENT];
1178 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1179 if (phdr->p_type == PT_PHDR)
1180 app->base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1181 else if (phdr->p_type == PT_INTERP)
1182 interp_off = (size_t)phdr->p_vaddr;
1183 else if (phdr->p_type == PT_TLS) {
1184 tls_image = phdr->p_vaddr;
1185 app->tls_len = phdr->p_filesz;
1186 app->tls_size = phdr->p_memsz;
1187 app->tls_align = phdr->p_align;
1190 if (app->tls_size) app->tls_image = (char *)app->base + tls_image;
1191 if (interp_off) lib->name = (char *)app->base + interp_off;
1192 if ((aux[0] & (1UL<<AT_EXECFN))
1193 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1194 app->name = (char *)aux[AT_EXECFN];
1196 app->name = argv[0];
1197 kernel_mapped_dso(app);
1200 char *ldname = argv[0];
1201 size_t l = strlen(ldname);
1202 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1203 *argv++ = (void *)-1;
1204 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1205 char *opt = argv[0]+2;
1206 *argv++ = (void *)-1;
1209 } else if (!memcmp(opt, "list", 5)) {
1211 } else if (!memcmp(opt, "library-path", 12)) {
1212 if (opt[12]=='=') env_path = opt+13;
1213 else if (opt[12]) *argv = 0;
1214 else if (*argv) env_path = *argv++;
1215 } else if (!memcmp(opt, "preload", 7)) {
1216 if (opt[7]=='=') env_preload = opt+8;
1217 else if (opt[7]) *argv = 0;
1218 else if (*argv) env_preload = *argv++;
1222 argv[-1] = (void *)-1;
1225 dprintf(2, "musl libc\n"
1227 "Dynamic Program Loader\n"
1228 "Usage: %s [options] [--] pathname%s\n",
1229 __libc_get_version(), ldname,
1230 ldd_mode ? "" : " [args]");
1233 fd = open(argv[0], O_RDONLY);
1235 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1239 ehdr = (void *)map_library(fd, app);
1241 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1247 app->name = argv[0];
1248 aux[AT_ENTRY] = (size_t)app->base + ehdr->e_entry;
1249 /* Find the name that would have been used for the dynamic
1250 * linker had ldd not taken its place. */
1252 for (i=0; i<app->phnum; i++) {
1253 if (app->phdr[i].p_type == PT_INTERP)
1254 lib->name = (void *)(app->base
1255 + app->phdr[i].p_vaddr);
1257 dprintf(1, "\t%s (%p)\n", lib->name, lib->base);
1260 if (app->tls_size) {
1261 app->tls_id = tls_cnt = 1;
1263 app->tls_offset = 0;
1264 tls_offset = app->tls_size
1265 + ( -((uintptr_t)app->tls_image + app->tls_size)
1266 & (app->tls_align-1) );
1268 tls_offset = app->tls_offset = app->tls_size
1269 + ( -((uintptr_t)app->tls_image + app->tls_size)
1270 & (app->tls_align-1) );
1272 tls_align = MAXP2(tls_align, app->tls_align);
1277 /* Attach to vdso, if provided by the kernel */
1278 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR)) {
1279 ehdr = (void *)vdso_base;
1280 vdso->phdr = phdr = (void *)(vdso_base + ehdr->e_phoff);
1281 vdso->phnum = ehdr->e_phnum;
1282 vdso->phentsize = ehdr->e_phentsize;
1283 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1284 if (phdr->p_type == PT_DYNAMIC)
1285 vdso->dynv = (void *)(vdso_base + phdr->p_offset);
1286 if (phdr->p_type == PT_LOAD)
1287 vdso->base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1290 vdso->shortname = "linux-gate.so.1";
1297 /* Initial dso chain consists only of the app. We temporarily
1298 * append the dynamic linker/libc so we can relocate it, then
1299 * restore the initial chain in preparation for loading third
1300 * party libraries (preload/needed). */
1307 /* PAST THIS POINT, ALL LIBC INTERFACES ARE FULLY USABLE. */
1309 /* Donate unused parts of app and library mapping to malloc */
1313 /* Load preload/needed libraries, add their symbols to the global
1314 * namespace, and perform all remaining relocations. The main
1315 * program must be relocated LAST since it may contain copy
1316 * relocations which depend on libraries' relocations. */
1317 if (env_preload) load_preload(env_preload);
1321 #ifndef DYNAMIC_IS_RO
1322 for (i=0; app->dynv[i]; i+=2)
1323 if (app->dynv[i]==DT_DEBUG)
1324 app->dynv[i+1] = (size_t)&debug;
1327 reloc_all(app->next);
1331 if (libc.tls_size > sizeof builtin_tls) {
1332 initial_tls = calloc(libc.tls_size, 1);
1334 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1335 argv[0], libc.tls_size);
1339 initial_tls = builtin_tls;
1341 if (__init_tp(__copy_tls(initial_tls)) < 0 && tls_cnt) {
1342 dprintf(2, "%s: Thread-local storage not supported by kernel.\n", argv[0]);
1345 static_tls_cnt = tls_cnt;
1347 if (ldso_fail) _exit(127);
1348 if (ldd_mode) _exit(0);
1350 /* Switch to runtime mode: any further failures in the dynamic
1351 * linker are a reportable failure rather than a fatal startup
1352 * error. If the dynamic loader (dlopen) will not be used, free
1353 * all memory used by the dynamic linker. */
1357 debug.bp = _dl_debug_state;
1359 debug.base = lib->base;
1363 __init_libc(envp, argv[0]);
1368 return (void *)aux[AT_ENTRY];
1371 void *dlopen(const char *file, int mode)
1373 struct dso *volatile p, *orig_tail, *next;
1374 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1379 if (!file) return head;
1381 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1382 pthread_rwlock_wrlock(&lock);
1386 orig_tls_cnt = tls_cnt;
1387 orig_tls_offset = tls_offset;
1388 orig_tls_align = tls_align;
1390 noload = mode & RTLD_NOLOAD;
1393 if (setjmp(*rtld_fail)) {
1394 /* Clean up anything new that was (partially) loaded */
1395 if (p && p->deps) for (i=0; p->deps[i]; i++)
1396 if (p->deps[i]->global < 0)
1397 p->deps[i]->global = 0;
1398 for (p=orig_tail->next; p; p=next) {
1400 munmap(p->map, p->map_len);
1401 while (p->td_index) {
1402 void *tmp = p->td_index->next;
1409 tls_cnt = orig_tls_cnt;
1410 tls_offset = orig_tls_offset;
1411 tls_align = orig_tls_align;
1417 } else p = load_library(file, head);
1420 snprintf(errbuf, sizeof errbuf, noload ?
1421 "Library %s is not already loaded" :
1422 "Error loading shared library %s: %m",
1428 /* First load handling */
1431 if (p->deps) for (i=0; p->deps[i]; i++)
1432 if (!p->deps[i]->global)
1433 p->deps[i]->global = -1;
1434 if (!p->global) p->global = -1;
1436 if (p->deps) for (i=0; p->deps[i]; i++)
1437 if (p->deps[i]->global < 0)
1438 p->deps[i]->global = 0;
1439 if (p->global < 0) p->global = 0;
1442 if (mode & RTLD_GLOBAL) {
1443 if (p->deps) for (i=0; p->deps[i]; i++)
1444 p->deps[i]->global = 1;
1454 pthread_rwlock_unlock(&lock);
1455 if (p) do_init_fini(orig_tail);
1456 pthread_setcancelstate(cs, 0);
1460 static int invalid_dso_handle(void *h)
1463 for (p=head; p; p=p->next) if (h==p) return 0;
1464 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1469 void *__tls_get_addr(size_t *);
1471 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1474 uint32_t h = 0, gh = 0;
1476 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1477 if (p == RTLD_DEFAULT) {
1479 } else if (p == RTLD_NEXT) {
1480 for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
1484 struct symdef def = find_sym(p, s, 0);
1485 if (!def.sym) goto failed;
1486 if ((def.sym->st_info&0xf) == STT_TLS)
1487 return __tls_get_addr((size_t []){def.dso->tls_id, def.sym->st_value});
1488 return def.dso->base + def.sym->st_value;
1490 if (p != RTLD_DEFAULT && p != RTLD_NEXT && invalid_dso_handle(p))
1494 sym = gnu_lookup(s, gh, p);
1497 sym = sysv_lookup(s, h, p);
1499 if (sym && (sym->st_info&0xf) == STT_TLS)
1500 return __tls_get_addr((size_t []){p->tls_id, sym->st_value});
1501 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1502 return p->base + sym->st_value;
1503 if (p->deps) for (i=0; p->deps[i]; i++) {
1504 if (p->deps[i]->ghashtab) {
1505 if (!gh) gh = gnu_hash(s);
1506 sym = gnu_lookup(s, gh, p->deps[i]);
1508 if (!h) h = sysv_hash(s);
1509 sym = sysv_lookup(s, h, p->deps[i]);
1511 if (sym && (sym->st_info&0xf) == STT_TLS)
1512 return __tls_get_addr((size_t []){p->deps[i]->tls_id, sym->st_value});
1513 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1514 return p->deps[i]->base + sym->st_value;
1518 snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
1522 int __dladdr(const void *addr, Dl_info *info)
1532 pthread_rwlock_rdlock(&lock);
1533 for (p=head; p && (unsigned char *)addr-p->map>p->map_len; p=p->next);
1534 pthread_rwlock_unlock(&lock);
1539 strings = p->strings;
1541 nsym = p->hashtab[1];
1545 buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
1546 sym += p->ghashtab[1];
1547 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
1548 if (buckets[i] > nsym)
1552 nsym -= p->ghashtab[1];
1553 hashval = buckets + p->ghashtab[0] + nsym;
1555 while (!(*hashval++ & 1));
1559 for (; nsym; nsym--, sym++) {
1561 && (1<<(sym->st_info&0xf) & OK_TYPES)
1562 && (1<<(sym->st_info>>4) & OK_BINDS)) {
1563 void *symaddr = p->base + sym->st_value;
1564 if (symaddr > addr || symaddr < best)
1567 bestname = strings + sym->st_name;
1568 if (addr == symaddr)
1573 if (!best) return 0;
1575 info->dli_fname = p->name;
1576 info->dli_fbase = p->base;
1577 info->dli_sname = bestname;
1578 info->dli_saddr = best;
1583 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1586 pthread_rwlock_rdlock(&lock);
1587 res = do_dlsym(p, s, ra);
1588 pthread_rwlock_unlock(&lock);
1592 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
1594 struct dso *current;
1595 struct dl_phdr_info info;
1597 for(current = head; current;) {
1598 info.dlpi_addr = (uintptr_t)current->base;
1599 info.dlpi_name = current->name;
1600 info.dlpi_phdr = current->phdr;
1601 info.dlpi_phnum = current->phnum;
1602 info.dlpi_adds = gencnt;
1604 info.dlpi_tls_modid = current->tls_id;
1605 info.dlpi_tls_data = current->tls_image;
1607 ret = (callback)(&info, sizeof (info), data);
1609 if (ret != 0) break;
1611 pthread_rwlock_rdlock(&lock);
1612 current = current->next;
1613 pthread_rwlock_unlock(&lock);
1618 static int invalid_dso_handle(void *h)
1620 snprintf(errbuf, sizeof errbuf, "Invalid library handle %p", (void *)h);
1624 void *dlopen(const char *file, int mode)
1626 strcpy(errbuf, "Dynamic loading not supported");
1630 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1633 snprintf(errbuf, sizeof errbuf, "Symbol not found: %s", s);
1636 int __dladdr (const void *addr, Dl_info *info)
1642 int __dlinfo(void *dso, int req, void *res)
1644 if (invalid_dso_handle(dso)) return -1;
1645 if (req != RTLD_DI_LINKMAP) {
1646 snprintf(errbuf, sizeof errbuf, "Unsupported request %d", req);
1650 *(struct link_map **)res = dso;
1656 if (!errflag) return 0;
1661 int dlclose(void *p)
1663 return invalid_dso_handle(p);