20 #include "pthread_impl.h"
24 static void error(const char *, ...);
26 #define MAXP2(a,b) (-(-(a)&-(b)))
27 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
39 struct td_index *next;
44 struct fdpic_loadmap *loadmap;
50 struct dso *next, *prev;
60 struct dso *syms_next, *lazy_next;
61 size_t *lazy, lazy_cnt;
69 struct dso **deps, *needed_by;
70 char *rpath_orig, *rpath;
71 struct tls_module tls;
73 size_t relro_start, relro_end;
75 unsigned char *new_tls;
76 volatile int new_dtv_idx, new_tls_idx;
77 struct td_index *td_index;
78 struct dso *fini_next;
83 struct fdpic_loadmap *loadmap;
98 int __init_tp(void *);
99 void __init_libc(char **, char *);
100 void *__copy_tls(unsigned char *);
102 __attribute__((__visibility__("hidden")))
103 const char *__libc_get_version(void);
105 static struct builtin_tls {
110 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
112 #define ADDEND_LIMIT 4096
113 static size_t *saved_addends, *apply_addends_to;
115 static struct dso ldso;
116 static struct dso *head, *tail, *fini_head, *syms_tail, *lazy_head;
117 static char *env_path, *sys_path;
118 static unsigned long long gencnt;
121 static int ldso_fail;
123 static jmp_buf *rtld_fail;
124 static pthread_rwlock_t lock;
125 static struct debug debug;
126 static struct tls_module *tls_tail;
127 static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
128 static size_t static_tls_cnt;
129 static pthread_mutex_t init_fini_lock = { ._m_type = PTHREAD_MUTEX_RECURSIVE };
130 static struct fdpic_loadmap *app_loadmap;
131 static struct fdpic_dummy_loadmap app_dummy_loadmap;
132 static struct dso *const nodeps_dummy;
134 struct debug *_dl_debug_addr = &debug;
136 __attribute__((__visibility__("hidden")))
137 void (*const __init_array_start)(void)=0, (*const __fini_array_start)(void)=0;
139 __attribute__((__visibility__("hidden")))
140 extern void (*const __init_array_end)(void), (*const __fini_array_end)(void);
142 weak_alias(__init_array_start, __init_array_end);
143 weak_alias(__fini_array_start, __fini_array_end);
145 static int dl_strcmp(const char *l, const char *r)
147 for (; *l==*r && *l; l++, r++);
148 return *(unsigned char *)l - *(unsigned char *)r;
150 #define strcmp(l,r) dl_strcmp(l,r)
152 /* Compute load address for a virtual address in a given dso. */
154 static void *laddr(const struct dso *p, size_t v)
157 if (!p->loadmap) return p->base + v;
158 for (j=0; v-p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz; j++);
159 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
161 #define fpaddr(p, v) ((void (*)())&(struct funcdesc){ \
162 laddr(p, v), (p)->got })
164 #define laddr(p, v) (void *)((p)->base + (v))
165 #define fpaddr(p, v) ((void (*)())laddr(p, v))
168 static void decode_vec(size_t *v, size_t *a, size_t cnt)
171 for (i=0; i<cnt; i++) a[i] = 0;
172 for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
178 static int search_vec(size_t *v, size_t *r, size_t key)
180 for (; v[0]!=key; v+=2)
186 static uint32_t sysv_hash(const char *s0)
188 const unsigned char *s = (void *)s0;
194 return h & 0xfffffff;
197 static uint32_t gnu_hash(const char *s0)
199 const unsigned char *s = (void *)s0;
200 uint_fast32_t h = 5381;
206 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
209 Sym *syms = dso->syms;
210 Elf_Symndx *hashtab = dso->hashtab;
211 char *strings = dso->strings;
212 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
213 if ((!dso->versym || dso->versym[i] >= 0)
214 && (!strcmp(s, strings+syms[i].st_name)))
220 static Sym *gnu_lookup(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s)
222 uint32_t nbuckets = hashtab[0];
223 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
224 uint32_t i = buckets[h1 % nbuckets];
228 uint32_t *hashval = buckets + nbuckets + (i - hashtab[1]);
230 for (h1 |= 1; ; i++) {
231 uint32_t h2 = *hashval++;
232 if ((h1 == (h2|1)) && (!dso->versym || dso->versym[i] >= 0)
233 && !strcmp(s, dso->strings + dso->syms[i].st_name))
241 static Sym *gnu_lookup_filtered(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s, uint32_t fofs, size_t fmask)
243 const size_t *bloomwords = (const void *)(hashtab+4);
244 size_t f = bloomwords[fofs & (hashtab[2]-1)];
245 if (!(f & fmask)) return 0;
247 f >>= (h1 >> hashtab[3]) % (8 * sizeof f);
248 if (!(f & 1)) return 0;
250 return gnu_lookup(h1, hashtab, dso, s);
253 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
254 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
256 #ifndef ARCH_SYM_REJECT_UND
257 #define ARCH_SYM_REJECT_UND(s) 0
260 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
262 uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
263 size_t ghm = 1ul << gh % (8*sizeof(size_t));
264 struct symdef def = {0};
265 for (; dso; dso=dso->syms_next) {
267 if ((ght = dso->ghashtab)) {
268 sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
270 if (!h) h = sysv_hash(s);
271 sym = sysv_lookup(s, h, dso);
275 if (need_def || (sym->st_info&0xf) == STT_TLS
276 || ARCH_SYM_REJECT_UND(sym))
279 if ((sym->st_info&0xf) != STT_TLS)
281 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
282 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
290 __attribute__((__visibility__("hidden")))
291 ptrdiff_t __tlsdesc_static(), __tlsdesc_dynamic();
293 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
295 unsigned char *base = dso->base;
296 Sym *syms = dso->syms;
297 char *strings = dso->strings;
308 int skip_relative = 0, reuse_addends = 0, save_slot = 0;
311 /* Only ldso's REL table needs addend saving/reuse. */
312 if (rel == apply_addends_to)
317 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
318 if (skip_relative && IS_RELATIVE(rel[1], dso->syms)) continue;
319 type = R_TYPE(rel[1]);
320 if (type == REL_NONE) continue;
321 reloc_addr = laddr(dso, rel[0]);
325 } else if (type==REL_GOT || type==REL_PLT|| type==REL_COPY) {
327 } else if (reuse_addends) {
328 /* Save original addend in stage 2 where the dso
329 * chain consists of just ldso; otherwise read back
330 * saved addend since the inline one was clobbered. */
332 saved_addends[save_slot] = *reloc_addr;
333 addend = saved_addends[save_slot++];
335 addend = *reloc_addr;
338 sym_index = R_SYM(rel[1]);
340 sym = syms + sym_index;
341 name = strings + sym->st_name;
342 ctx = type==REL_COPY ? head->syms_next : head;
343 def = (sym->st_info&0xf) == STT_SECTION
344 ? (struct symdef){ .dso = dso, .sym = sym }
345 : find_sym(ctx, name, type==REL_PLT);
346 if (!def.sym && (sym->st_shndx != SHN_UNDEF
347 || sym->st_info>>4 != STB_WEAK)) {
348 if (dso->lazy && (type==REL_PLT || type==REL_GOT)) {
349 dso->lazy[3*dso->lazy_cnt+0] = rel[0];
350 dso->lazy[3*dso->lazy_cnt+1] = rel[1];
351 dso->lazy[3*dso->lazy_cnt+2] = addend;
355 error("Error relocating %s: %s: symbol not found",
357 if (runtime) longjmp(*rtld_fail, 1);
366 sym_val = def.sym ? (size_t)laddr(def.dso, def.sym->st_value) : 0;
367 tls_val = def.sym ? def.sym->st_value : 0;
373 addend -= (size_t)reloc_addr;
377 *reloc_addr = sym_val + addend;
380 *reloc_addr = (size_t)base + addend;
383 if (sym) *reloc_addr = sym_val + addend;
384 else *reloc_addr = (size_t)base + addend;
387 memcpy(reloc_addr, (void *)sym_val, sym->st_size);
390 *(uint32_t *)reloc_addr = sym_val + addend
391 - (size_t)reloc_addr;
394 *reloc_addr = def.sym ? (size_t)(def.dso->funcdescs
395 + (def.sym - def.dso->syms)) : 0;
397 case REL_FUNCDESC_VAL:
398 if ((sym->st_info&0xf) == STT_SECTION) *reloc_addr += sym_val;
399 else *reloc_addr = sym_val;
400 reloc_addr[1] = def.sym ? (size_t)def.dso->got : 0;
403 *reloc_addr = def.dso->tls_id;
406 *reloc_addr = tls_val + addend - DTP_OFFSET;
410 *reloc_addr = tls_val + def.dso->tls.offset + TPOFF_K + addend;
414 *reloc_addr = tls_val - def.dso->tls.offset + addend;
417 *reloc_addr = def.dso->tls.offset - tls_val + addend;
421 if (stride<3) addend = reloc_addr[1];
422 if (runtime && def.dso->tls_id >= static_tls_cnt) {
423 struct td_index *new = malloc(sizeof *new);
426 "Error relocating %s: cannot allocate TLSDESC for %s",
427 dso->name, sym ? name : "(local)" );
428 longjmp(*rtld_fail, 1);
430 new->next = dso->td_index;
432 new->args[0] = def.dso->tls_id;
433 new->args[1] = tls_val + addend;
434 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
435 reloc_addr[1] = (size_t)new;
437 reloc_addr[0] = (size_t)__tlsdesc_static;
439 reloc_addr[1] = tls_val + def.dso->tls.offset
442 reloc_addr[1] = tls_val - def.dso->tls.offset
448 error("Error relocating %s: unsupported relocation type %d",
450 if (runtime) longjmp(*rtld_fail, 1);
456 static void redo_lazy_relocs()
458 struct dso *p = lazy_head, *next;
462 size_t size = p->lazy_cnt*3*sizeof(size_t);
464 do_relocs(p, p->lazy, size, 3);
466 p->lazy_next = lazy_head;
476 /* A huge hack: to make up for the wastefulness of shared libraries
477 * needing at least a page of dirty memory even if they have no global
478 * data, we reclaim the gaps at the beginning and end of writable maps
479 * and "donate" them to the heap by setting up minimal malloc
480 * structures and then freeing them. */
482 static void reclaim(struct dso *dso, size_t start, size_t end)
485 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
486 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
487 start = start + 6*sizeof(size_t)-1 & -4*sizeof(size_t);
488 end = (end & -4*sizeof(size_t)) - 2*sizeof(size_t);
489 if (start>end || end-start < 4*sizeof(size_t)) return;
490 a = laddr(dso, start);
493 a[-1] = z[0] = end-start + 2*sizeof(size_t) | 1;
498 static void reclaim_gaps(struct dso *dso)
500 Phdr *ph = dso->phdr;
501 size_t phcnt = dso->phnum;
503 if (DL_FDPIC) return; // FIXME
504 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
505 if (ph->p_type!=PT_LOAD) continue;
506 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
507 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
508 reclaim(dso, ph->p_vaddr+ph->p_memsz,
509 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
513 static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t off)
515 static int no_map_fixed;
518 q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
519 if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
523 /* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
524 if (flags & MAP_ANONYMOUS) {
529 if (lseek(fd, off, SEEK_SET) < 0) return MAP_FAILED;
530 for (q=p; n; q+=r, off+=r, n-=r) {
532 if (r < 0 && errno != EINTR) return MAP_FAILED;
541 static void unmap_library(struct dso *dso)
545 for (i=0; i<dso->loadmap->nsegs; i++) {
546 if (!dso->loadmap->segs[i].p_memsz)
548 munmap((void *)dso->loadmap->segs[i].addr,
549 dso->loadmap->segs[i].p_memsz);
552 } else if (dso->map && dso->map_len) {
553 munmap(dso->map, dso->map_len);
557 static void *map_library(int fd, struct dso *dso)
559 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
560 void *allocated_buf=0;
562 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
563 size_t this_min, this_max;
569 unsigned char *map=MAP_FAILED, *base;
574 ssize_t l = read(fd, buf, sizeof buf);
577 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
579 phsize = eh->e_phentsize * eh->e_phnum;
580 if (phsize > sizeof buf - sizeof *eh) {
581 allocated_buf = malloc(phsize);
582 if (!allocated_buf) return 0;
583 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
584 if (l < 0) goto error;
585 if (l != phsize) goto noexec;
586 ph = ph0 = allocated_buf;
587 } else if (eh->e_phoff + phsize > l) {
588 l = pread(fd, buf+1, phsize, eh->e_phoff);
589 if (l < 0) goto error;
590 if (l != phsize) goto noexec;
591 ph = ph0 = (void *)(buf + 1);
593 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
595 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
596 if (ph->p_type == PT_DYNAMIC) {
598 } else if (ph->p_type == PT_TLS) {
599 tls_image = ph->p_vaddr;
600 dso->tls.align = ph->p_align;
601 dso->tls.len = ph->p_filesz;
602 dso->tls.size = ph->p_memsz;
603 } else if (ph->p_type == PT_GNU_RELRO) {
604 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
605 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
607 if (ph->p_type != PT_LOAD) continue;
609 if (ph->p_vaddr < addr_min) {
610 addr_min = ph->p_vaddr;
611 off_start = ph->p_offset;
612 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
613 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
614 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
616 if (ph->p_vaddr+ph->p_memsz > addr_max) {
617 addr_max = ph->p_vaddr+ph->p_memsz;
620 if (!dyn) goto noexec;
621 if (DL_FDPIC && !(eh->e_flags & FDPIC_CONSTDISP_FLAG)) {
622 dso->loadmap = calloc(1, sizeof *dso->loadmap
623 + nsegs * sizeof *dso->loadmap->segs);
624 if (!dso->loadmap) goto error;
625 dso->loadmap->nsegs = nsegs;
626 for (ph=ph0, i=0; i<nsegs; ph=(void *)((char *)ph+eh->e_phentsize)) {
627 if (ph->p_type != PT_LOAD) continue;
628 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
629 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
630 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
631 map = mmap(0, ph->p_memsz + (ph->p_vaddr & PAGE_SIZE-1),
633 fd, ph->p_offset & -PAGE_SIZE);
634 if (map == MAP_FAILED) {
638 dso->loadmap->segs[i].addr = (size_t)map +
639 (ph->p_vaddr & PAGE_SIZE-1);
640 dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
641 dso->loadmap->segs[i].p_memsz = ph->p_memsz;
643 if (prot & PROT_WRITE) {
644 size_t brk = (ph->p_vaddr & PAGE_SIZE-1)
646 size_t pgbrk = brk + PAGE_SIZE-1 & -PAGE_SIZE;
647 size_t pgend = brk + ph->p_memsz - ph->p_filesz
648 + PAGE_SIZE-1 & -PAGE_SIZE;
649 if (pgend > pgbrk && mmap_fixed(map+pgbrk,
651 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
652 -1, off_start) == MAP_FAILED)
654 memset(map + brk, 0, pgbrk-brk);
657 map = (void *)dso->loadmap->segs[0].addr;
661 addr_max += PAGE_SIZE-1;
662 addr_max &= -PAGE_SIZE;
663 addr_min &= -PAGE_SIZE;
664 off_start &= -PAGE_SIZE;
665 map_len = addr_max - addr_min + off_start;
666 /* The first time, we map too much, possibly even more than
667 * the length of the file. This is okay because we will not
668 * use the invalid part; we just need to reserve the right
669 * amount of virtual address space to map over later. */
670 map = DL_NOMMU_SUPPORT
671 ? mmap((void *)addr_min, map_len, PROT_READ|PROT_WRITE|PROT_EXEC,
672 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
673 : mmap((void *)addr_min, map_len, prot,
674 MAP_PRIVATE, fd, off_start);
675 if (map==MAP_FAILED) goto error;
677 dso->map_len = map_len;
678 /* If the loaded file is not relocatable and the requested address is
679 * not available, then the load operation must fail. */
680 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
684 base = map - addr_min;
687 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
688 if (ph->p_type != PT_LOAD) continue;
689 /* Check if the programs headers are in this load segment, and
690 * if so, record the address for use by dl_iterate_phdr. */
691 if (!dso->phdr && eh->e_phoff >= ph->p_offset
692 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
693 dso->phdr = (void *)(base + ph->p_vaddr
694 + (eh->e_phoff-ph->p_offset));
695 dso->phnum = eh->e_phnum;
696 dso->phentsize = eh->e_phentsize;
698 /* Reuse the existing mapping for the lowest-address LOAD */
699 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min && !DL_NOMMU_SUPPORT)
701 this_min = ph->p_vaddr & -PAGE_SIZE;
702 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
703 off_start = ph->p_offset & -PAGE_SIZE;
704 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
705 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
706 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
707 if (mmap_fixed(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
709 if (ph->p_memsz > ph->p_filesz) {
710 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
711 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
712 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
713 if (pgbrk-(size_t)base < this_max && mmap_fixed((void *)pgbrk, (size_t)base+this_max-pgbrk, prot, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED)
717 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
718 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
719 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
726 dso->dynv = laddr(dso, dyn);
727 if (dso->tls.size) dso->tls.image = laddr(dso, tls_image);
733 if (map!=MAP_FAILED) unmap_library(dso);
738 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
743 s += strspn(s, ":\n");
744 l = strcspn(s, ":\n");
745 if (l-1 >= INT_MAX) return -1;
746 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
747 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
755 /* Any negative value but -1 will inhibit
756 * futher path search. */
764 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
767 const char *s, *t, *origin;
769 if (p->rpath || !p->rpath_orig) return 0;
770 if (!strchr(p->rpath_orig, '$')) {
771 p->rpath = p->rpath_orig;
776 while ((t=strchr(s, '$'))) {
777 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
782 if (n > SSIZE_MAX/PATH_MAX) return 0;
784 if (p->kernel_mapped) {
785 /* $ORIGIN searches cannot be performed for the main program
786 * when it is suid/sgid/AT_SECURE. This is because the
787 * pathname is under the control of the caller of execve.
788 * For libraries, however, $ORIGIN can be processed safely
789 * since the library's pathname came from a trusted source
790 * (either system paths or a call to dlopen). */
793 l = readlink("/proc/self/exe", buf, buf_size);
794 if (l == -1) switch (errno) {
809 t = strrchr(origin, '/');
810 l = t ? t-origin : 0;
811 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
812 if (!p->rpath) return -1;
816 while ((t=strchr(s, '$'))) {
819 memcpy(d, origin, l);
821 /* It was determined previously that the '$' is followed
822 * either by "ORIGIN" or "{ORIGIN}". */
823 s = t + 7 + 2*(t[1]=='{');
829 static void decode_dyn(struct dso *p)
832 decode_vec(p->dynv, dyn, DYN_CNT);
833 p->syms = laddr(p, dyn[DT_SYMTAB]);
834 p->strings = laddr(p, dyn[DT_STRTAB]);
835 if (dyn[0]&(1<<DT_HASH))
836 p->hashtab = laddr(p, dyn[DT_HASH]);
837 if (dyn[0]&(1<<DT_RPATH))
838 p->rpath_orig = p->strings + dyn[DT_RPATH];
839 if (dyn[0]&(1<<DT_RUNPATH))
840 p->rpath_orig = p->strings + dyn[DT_RUNPATH];
841 if (dyn[0]&(1<<DT_PLTGOT))
842 p->got = laddr(p, dyn[DT_PLTGOT]);
843 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
844 p->ghashtab = laddr(p, *dyn);
845 if (search_vec(p->dynv, dyn, DT_VERSYM))
846 p->versym = laddr(p, *dyn);
849 static size_t count_syms(struct dso *p)
851 if (p->hashtab) return p->hashtab[1];
854 uint32_t *buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
856 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
857 if (buckets[i] > nsym)
861 hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
863 while (!(*hashval++ & 1));
868 static void *dl_mmap(size_t n)
871 int prot = PROT_READ|PROT_WRITE, flags = MAP_ANONYMOUS|MAP_PRIVATE;
873 p = (void *)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
875 p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
877 return p == MAP_FAILED ? 0 : p;
880 static void makefuncdescs(struct dso *p)
882 static int self_done;
883 size_t nsym = count_syms(p);
884 size_t i, size = nsym * sizeof(*p->funcdescs);
887 p->funcdescs = dl_mmap(size);
890 p->funcdescs = malloc(size);
893 if (!runtime) a_crash();
894 error("Error allocating function descriptors for %s", p->name);
895 longjmp(*rtld_fail, 1);
897 for (i=0; i<nsym; i++) {
898 if ((p->syms[i].st_info&0xf)==STT_FUNC && p->syms[i].st_shndx) {
899 p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
900 p->funcdescs[i].got = p->got;
902 p->funcdescs[i].addr = 0;
903 p->funcdescs[i].got = 0;
908 static struct dso *load_library(const char *name, struct dso *needed_by)
910 char buf[2*NAME_MAX+2];
911 const char *pathname;
913 struct dso *p, temp_dso = {0};
925 /* Catch and block attempts to reload the implementation itself */
926 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
927 static const char reserved[] =
928 "c.pthread.rt.m.dl.util.xnet.";
929 const char *rp, *next;
930 for (rp=reserved; *rp; rp=next) {
931 next = strchr(rp, '.') + 1;
932 if (strncmp(name+3, rp, next-rp) == 0)
937 /* Track which names have been resolved
938 * and only report each one once. */
939 static unsigned reported;
940 unsigned mask = 1U<<(rp-reserved);
941 if (!(reported & mask)) {
943 dprintf(1, "\t%s => %s (%p)\n",
951 if (!strcmp(name, ldso.name)) is_self = 1;
960 if (strchr(name, '/')) {
962 fd = open(name, O_RDONLY|O_CLOEXEC);
964 /* Search for the name to see if it's already loaded */
965 for (p=head->next; p; p=p->next) {
966 if (p->shortname && !strcmp(p->shortname, name)) {
970 if (strlen(name) > NAME_MAX) return 0;
972 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
973 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
974 if (fixup_rpath(p, buf, sizeof buf) < 0)
975 fd = -2; /* Inhibit further search. */
977 fd = path_open(name, p->rpath, buf, sizeof buf);
983 if (ldso.name[0]=='/') {
985 for (s=t=z=ldso.name; *s; s++)
986 if (*s=='/') z=t, t=s;
987 prefix_len = z-ldso.name;
988 if (prefix_len < PATH_MAX)
995 char etc_ldso_path[prefix_len + 1
996 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
997 snprintf(etc_ldso_path, sizeof etc_ldso_path,
998 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
999 (int)prefix_len, prefix);
1000 FILE *f = fopen(etc_ldso_path, "rbe");
1002 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
1007 } else if (errno != ENOENT) {
1011 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
1012 fd = path_open(name, sys_path, buf, sizeof buf);
1016 if (fd < 0) return 0;
1017 if (fstat(fd, &st) < 0) {
1021 for (p=head->next; p; p=p->next) {
1022 if (p->dev == st.st_dev && p->ino == st.st_ino) {
1023 /* If this library was previously loaded with a
1024 * pathname but a search found the same inode,
1025 * setup its shortname so it can be found by name. */
1026 if (!p->shortname && pathname != name)
1027 p->shortname = strrchr(p->name, '/')+1;
1032 map = noload ? 0 : map_library(fd, &temp_dso);
1036 /* Avoid the danger of getting two versions of libc mapped into the
1037 * same process when an absolute pathname was used. The symbols
1038 * checked are chosen to catch both musl and glibc, and to avoid
1039 * false positives from interposition-hack libraries. */
1040 decode_dyn(&temp_dso);
1041 if (find_sym(&temp_dso, "__libc_start_main", 1).sym &&
1042 find_sym(&temp_dso, "stdin", 1).sym) {
1043 unmap_library(&temp_dso);
1044 return load_library("libc.so", needed_by);
1046 /* Past this point, if we haven't reached runtime yet, ldso has
1047 * committed either to use the mapped library or to abort execution.
1048 * Unmapping is not possible, so we can safely reclaim gaps. */
1049 if (!runtime) reclaim_gaps(&temp_dso);
1051 /* Allocate storage for the new DSO. When there is TLS, this
1052 * storage must include a reservation for all pre-existing
1053 * threads to obtain copies of both the new TLS, and an
1054 * extended DTV capable of storing an additional slot for
1055 * the newly-loaded DSO. */
1056 alloc_size = sizeof *p + strlen(pathname) + 1;
1057 if (runtime && temp_dso.tls.image) {
1058 size_t per_th = temp_dso.tls.size + temp_dso.tls.align
1059 + sizeof(void *) * (tls_cnt+3);
1060 n_th = libc.threads_minus_1 + 1;
1061 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
1062 else alloc_size += n_th * per_th;
1064 p = calloc(1, alloc_size);
1066 unmap_library(&temp_dso);
1069 memcpy(p, &temp_dso, sizeof temp_dso);
1072 p->needed_by = needed_by;
1074 strcpy(p->name, pathname);
1075 /* Add a shortname only if name arg was not an explicit pathname. */
1076 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
1078 p->tls_id = ++tls_cnt;
1079 tls_align = MAXP2(tls_align, p->tls.align);
1081 p->tls.offset = tls_offset + ( (tls_align-1) &
1082 -(tls_offset + (uintptr_t)p->tls.image) );
1083 tls_offset += p->tls.size;
1085 tls_offset += p->tls.size + p->tls.align - 1;
1086 tls_offset -= (tls_offset + (uintptr_t)p->tls.image)
1088 p->tls.offset = tls_offset;
1090 p->new_dtv = (void *)(-sizeof(size_t) &
1091 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
1092 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
1093 if (tls_tail) tls_tail->next = &p->tls;
1094 else libc.tls_head = &p->tls;
1102 if (DL_FDPIC) makefuncdescs(p);
1104 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
1109 static void load_deps(struct dso *p)
1112 struct dso ***deps = &p->deps, **tmp, *dep;
1113 for (; p; p=p->next) {
1114 for (i=0; p->dynv[i]; i+=2) {
1115 if (p->dynv[i] != DT_NEEDED) continue;
1116 dep = load_library(p->strings + p->dynv[i+1], p);
1118 error("Error loading shared library %s: %m (needed by %s)",
1119 p->strings + p->dynv[i+1], p->name);
1120 if (runtime) longjmp(*rtld_fail, 1);
1124 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
1125 if (!tmp) longjmp(*rtld_fail, 1);
1132 if (!*deps) *deps = (struct dso **)&nodeps_dummy;
1135 static void load_preload(char *s)
1139 for (z=s; *z; s=z) {
1140 for ( ; *s && (isspace(*s) || *s==':'); s++);
1141 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
1149 static void add_syms(struct dso *p)
1151 if (!p->syms_next && syms_tail != p) {
1152 syms_tail->syms_next = p;
1157 static void revert_syms(struct dso *old_tail)
1159 struct dso *p, *next;
1160 /* Chop off the tail of the list of dsos that participate in
1161 * the global symbol table, reverting them to RTLD_LOCAL. */
1162 for (p=old_tail; p; p=next) {
1163 next = p->syms_next;
1166 syms_tail = old_tail;
1169 static void do_mips_relocs(struct dso *p, size_t *got)
1171 size_t i, j, rel[2];
1172 unsigned char *base = p->base;
1173 i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
1177 while (i--) *got++ += (size_t)base;
1179 j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1180 i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1181 Sym *sym = p->syms + j;
1182 rel[0] = (unsigned char *)got - base;
1183 for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
1184 rel[1] = R_INFO(sym-p->syms, R_MIPS_JUMP_SLOT);
1185 do_relocs(p, rel, sizeof rel, 2);
1189 static void reloc_all(struct dso *p)
1191 size_t dyn[DYN_CNT];
1192 for (; p; p=p->next) {
1193 if (p->relocated) continue;
1194 decode_vec(p->dynv, dyn, DYN_CNT);
1195 if (NEED_MIPS_GOT_RELOCS)
1196 do_mips_relocs(p, laddr(p, dyn[DT_PLTGOT]));
1197 do_relocs(p, laddr(p, dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
1198 2+(dyn[DT_PLTREL]==DT_RELA));
1199 do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
1200 do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);
1202 if (head != &ldso && p->relro_start != p->relro_end &&
1203 mprotect(laddr(p, p->relro_start), p->relro_end-p->relro_start, PROT_READ)
1204 && errno != ENOSYS) {
1205 error("Error relocating %s: RELRO protection failed: %m",
1207 if (runtime) longjmp(*rtld_fail, 1);
1214 static void kernel_mapped_dso(struct dso *p)
1216 size_t min_addr = -1, max_addr = 0, cnt;
1218 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
1219 if (ph->p_type == PT_DYNAMIC) {
1220 p->dynv = laddr(p, ph->p_vaddr);
1221 } else if (ph->p_type == PT_GNU_RELRO) {
1222 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
1223 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
1225 if (ph->p_type != PT_LOAD) continue;
1226 if (ph->p_vaddr < min_addr)
1227 min_addr = ph->p_vaddr;
1228 if (ph->p_vaddr+ph->p_memsz > max_addr)
1229 max_addr = ph->p_vaddr+ph->p_memsz;
1231 min_addr &= -PAGE_SIZE;
1232 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
1233 p->map = p->base + min_addr;
1234 p->map_len = max_addr - min_addr;
1235 p->kernel_mapped = 1;
1238 void __libc_exit_fini()
1241 size_t dyn[DYN_CNT];
1242 for (p=fini_head; p; p=p->fini_next) {
1243 if (!p->constructed) continue;
1244 decode_vec(p->dynv, dyn, DYN_CNT);
1245 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
1246 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
1247 size_t *fn = (size_t *)laddr(p, dyn[DT_FINI_ARRAY])+n;
1248 while (n--) ((void (*)(void))*--fn)();
1250 #ifndef NO_LEGACY_INITFINI
1251 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
1252 fpaddr(p, dyn[DT_FINI])();
1257 static void do_init_fini(struct dso *p)
1259 size_t dyn[DYN_CNT];
1260 int need_locking = libc.threads_minus_1;
1261 /* Allow recursive calls that arise when a library calls
1262 * dlopen from one of its constructors, but block any
1263 * other threads until all ctors have finished. */
1264 if (need_locking) pthread_mutex_lock(&init_fini_lock);
1265 for (; p; p=p->prev) {
1266 if (p->constructed) continue;
1268 decode_vec(p->dynv, dyn, DYN_CNT);
1269 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
1270 p->fini_next = fini_head;
1273 #ifndef NO_LEGACY_INITFINI
1274 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
1275 fpaddr(p, dyn[DT_INIT])();
1277 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
1278 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
1279 size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
1280 while (n--) ((void (*)(void))*fn++)();
1282 if (!need_locking && libc.threads_minus_1) {
1284 pthread_mutex_lock(&init_fini_lock);
1287 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
1290 void __libc_start_init(void)
1295 static void dl_debug_state(void)
1299 weak_alias(dl_debug_state, _dl_debug_state);
1301 void __init_tls(size_t *auxv)
1305 __attribute__((__visibility__("hidden")))
1306 void *__tls_get_new(tls_mod_off_t *v)
1308 pthread_t self = __pthread_self();
1310 /* Block signals to make accessing new TLS async-signal-safe */
1312 __block_all_sigs(&set);
1313 if (v[0]<=(size_t)self->dtv[0]) {
1314 __restore_sigs(&set);
1315 return (char *)self->dtv[v[0]]+v[1]+DTP_OFFSET;
1318 /* This is safe without any locks held because, if the caller
1319 * is able to request the Nth entry of the DTV, the DSO list
1320 * must be valid at least that far out and it was synchronized
1321 * at program startup or by an already-completed call to dlopen. */
1323 for (p=head; p->tls_id != v[0]; p=p->next);
1325 /* Get new DTV space from new DSO if needed */
1326 if (v[0] > (size_t)self->dtv[0]) {
1327 void **newdtv = p->new_dtv +
1328 (v[0]+1)*a_fetch_add(&p->new_dtv_idx,1);
1329 memcpy(newdtv, self->dtv,
1330 ((size_t)self->dtv[0]+1) * sizeof(void *));
1331 newdtv[0] = (void *)v[0];
1332 self->dtv = self->dtv_copy = newdtv;
1335 /* Get new TLS memory from all new DSOs up to the requested one */
1337 for (p=head; ; p=p->next) {
1338 if (!p->tls_id || self->dtv[p->tls_id]) continue;
1339 mem = p->new_tls + (p->tls.size + p->tls.align)
1340 * a_fetch_add(&p->new_tls_idx,1);
1341 mem += ((uintptr_t)p->tls.image - (uintptr_t)mem)
1343 self->dtv[p->tls_id] = mem;
1344 memcpy(mem, p->tls.image, p->tls.len);
1345 if (p->tls_id == v[0]) break;
1347 __restore_sigs(&set);
1348 return mem + v[1] + DTP_OFFSET;
1351 static void update_tls_size()
1353 libc.tls_cnt = tls_cnt;
1354 libc.tls_align = tls_align;
1355 libc.tls_size = ALIGN(
1356 (1+tls_cnt) * sizeof(void *) +
1358 sizeof(struct pthread) +
1363 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1364 * following stage 2 and stage 3 functions via primitive symbolic lookup
1365 * since it does not have access to their addresses to begin with. */
1367 /* Stage 2 of the dynamic linker is called after relative relocations
1368 * have been processed. It can make function calls to static functions
1369 * and access string literals and static data, but cannot use extern
1370 * symbols. Its job is to perform symbolic relocations on the dynamic
1371 * linker itself, but some of the relocations performed may need to be
1372 * replaced later due to copy relocations in the main program. */
1374 __attribute__((__visibility__("hidden")))
1375 void __dls2(unsigned char *base, size_t *sp)
1378 void *p1 = (void *)sp[-2];
1379 void *p2 = (void *)sp[-1];
1381 size_t *auxv, aux[AUX_CNT];
1382 for (auxv=sp+1+*sp+1; *auxv; auxv++); auxv++;
1383 decode_vec(auxv, aux, AUX_CNT);
1384 if (aux[AT_BASE]) ldso.base = (void *)aux[AT_BASE];
1385 else ldso.base = (void *)(aux[AT_PHDR] & -4096);
1387 app_loadmap = p2 ? p1 : 0;
1388 ldso.loadmap = p2 ? p2 : p1;
1389 ldso.base = laddr(&ldso, 0);
1393 Ehdr *ehdr = (void *)ldso.base;
1394 ldso.name = ldso.shortname = "libc.so";
1395 ldso.phnum = ehdr->e_phnum;
1396 ldso.phdr = laddr(&ldso, ehdr->e_phoff);
1397 ldso.phentsize = ehdr->e_phentsize;
1398 kernel_mapped_dso(&ldso);
1401 if (DL_FDPIC) makefuncdescs(&ldso);
1403 /* Prepare storage for to save clobbered REL addends so they
1404 * can be reused in stage 3. There should be very few. If
1405 * something goes wrong and there are a huge number, abort
1406 * instead of risking stack overflow. */
1407 size_t dyn[DYN_CNT];
1408 decode_vec(ldso.dynv, dyn, DYN_CNT);
1409 size_t *rel = laddr(&ldso, dyn[DT_REL]);
1410 size_t rel_size = dyn[DT_RELSZ];
1411 size_t symbolic_rel_cnt = 0;
1412 apply_addends_to = rel;
1413 for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
1414 if (!IS_RELATIVE(rel[1], ldso.syms)) symbolic_rel_cnt++;
1415 if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
1416 size_t addends[symbolic_rel_cnt+1];
1417 saved_addends = addends;
1424 /* Call dynamic linker stage-3, __dls3, looking it up
1425 * symbolically as a barrier against moving the address
1426 * load across the above relocation processing. */
1427 struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1428 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp);
1429 else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp);
1432 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1433 * fully functional. Its job is to load (if not already loaded) and
1434 * process dependencies and relocations for the main application and
1435 * transfer control to its entry point. */
1437 _Noreturn void __dls3(size_t *sp)
1439 static struct dso app, vdso;
1440 size_t aux[AUX_CNT], *auxv;
1442 char *env_preload=0;
1443 char *replace_argv0=0;
1446 char **argv = (void *)(sp+1);
1447 char **argv_orig = argv;
1448 char **envp = argv+argc+1;
1450 /* Find aux vector just past environ[] and use it to initialize
1451 * global data that may be needed before we can make syscalls. */
1453 for (i=argc+1; argv[i]; i++);
1454 libc.auxv = auxv = (void *)(argv+i+1);
1455 decode_vec(auxv, aux, AUX_CNT);
1456 __hwcap = aux[AT_HWCAP];
1457 libc.page_size = aux[AT_PAGESZ];
1458 libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1459 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
1461 /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1462 * use during dynamic linking. If possible it will also serve as the
1463 * thread pointer at runtime. */
1464 libc.tls_size = sizeof builtin_tls;
1465 libc.tls_align = tls_align;
1466 if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1470 /* Only trust user/env if kernel says we're not suid/sgid */
1472 env_path = getenv("LD_LIBRARY_PATH");
1473 env_preload = getenv("LD_PRELOAD");
1476 /* If the main program was already loaded by the kernel,
1477 * AT_PHDR will point to some location other than the dynamic
1478 * linker's program headers. */
1479 if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1480 size_t interp_off = 0;
1481 size_t tls_image = 0;
1482 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1483 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1484 app.phnum = aux[AT_PHNUM];
1485 app.phentsize = aux[AT_PHENT];
1486 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1487 if (phdr->p_type == PT_PHDR)
1488 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1489 else if (phdr->p_type == PT_INTERP)
1490 interp_off = (size_t)phdr->p_vaddr;
1491 else if (phdr->p_type == PT_TLS) {
1492 tls_image = phdr->p_vaddr;
1493 app.tls.len = phdr->p_filesz;
1494 app.tls.size = phdr->p_memsz;
1495 app.tls.align = phdr->p_align;
1498 if (DL_FDPIC) app.loadmap = app_loadmap;
1499 if (app.tls.size) app.tls.image = laddr(&app, tls_image);
1500 if (interp_off) ldso.name = laddr(&app, interp_off);
1501 if ((aux[0] & (1UL<<AT_EXECFN))
1502 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1503 app.name = (char *)aux[AT_EXECFN];
1506 kernel_mapped_dso(&app);
1509 char *ldname = argv[0];
1510 size_t l = strlen(ldname);
1511 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1513 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1514 char *opt = argv[0]+2;
1515 *argv++ = (void *)-1;
1518 } else if (!memcmp(opt, "list", 5)) {
1520 } else if (!memcmp(opt, "library-path", 12)) {
1521 if (opt[12]=='=') env_path = opt+13;
1522 else if (opt[12]) *argv = 0;
1523 else if (*argv) env_path = *argv++;
1524 } else if (!memcmp(opt, "preload", 7)) {
1525 if (opt[7]=='=') env_preload = opt+8;
1526 else if (opt[7]) *argv = 0;
1527 else if (*argv) env_preload = *argv++;
1528 } else if (!memcmp(opt, "argv0", 5)) {
1529 if (opt[5]=='=') replace_argv0 = opt+6;
1530 else if (opt[5]) *argv = 0;
1531 else if (*argv) replace_argv0 = *argv++;
1536 argv[-1] = (void *)(argc - (argv-argv_orig));
1538 dprintf(2, "musl libc (" LDSO_ARCH ")\n"
1540 "Dynamic Program Loader\n"
1541 "Usage: %s [options] [--] pathname%s\n",
1542 __libc_get_version(), ldname,
1543 ldd_mode ? "" : " [args]");
1546 fd = open(argv[0], O_RDONLY);
1548 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1551 Ehdr *ehdr = (void *)map_library(fd, &app);
1553 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1559 aux[AT_ENTRY] = (size_t)laddr(&app, ehdr->e_entry);
1560 /* Find the name that would have been used for the dynamic
1561 * linker had ldd not taken its place. */
1563 for (i=0; i<app.phnum; i++) {
1564 if (app.phdr[i].p_type == PT_INTERP)
1565 ldso.name = laddr(&app, app.phdr[i].p_vaddr);
1567 dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1571 libc.tls_head = tls_tail = &app.tls;
1572 app.tls_id = tls_cnt = 1;
1575 tls_offset = app.tls.size
1576 + ( -((uintptr_t)app.tls.image + app.tls.size)
1577 & (app.tls.align-1) );
1579 tls_offset = app.tls.offset = app.tls.size
1580 + ( -((uintptr_t)app.tls.image + app.tls.size)
1581 & (app.tls.align-1) );
1583 tls_align = MAXP2(tls_align, app.tls.align);
1587 makefuncdescs(&app);
1589 app.loadmap = (void *)&app_dummy_loadmap;
1590 app.loadmap->nsegs = 1;
1591 app.loadmap->segs[0].addr = (size_t)app.map;
1592 app.loadmap->segs[0].p_vaddr = (size_t)app.map
1594 app.loadmap->segs[0].p_memsz = app.map_len;
1596 argv[-3] = (void *)app.loadmap;
1599 /* Initial dso chain consists only of the app. */
1600 head = tail = syms_tail = &app;
1602 /* Donate unused parts of app and library mapping to malloc */
1604 reclaim_gaps(&ldso);
1606 /* Load preload/needed libraries, add symbols to global namespace. */
1607 if (env_preload) load_preload(env_preload);
1609 for (struct dso *p=head; p; p=p->next)
1612 /* Attach to vdso, if provided by the kernel, last so that it does
1613 * not become part of the global namespace. */
1614 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR) && vdso_base) {
1615 Ehdr *ehdr = (void *)vdso_base;
1616 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
1617 vdso.phnum = ehdr->e_phnum;
1618 vdso.phentsize = ehdr->e_phentsize;
1619 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1620 if (phdr->p_type == PT_DYNAMIC)
1621 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
1622 if (phdr->p_type == PT_LOAD)
1623 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1626 vdso.shortname = "linux-gate.so.1";
1634 for (i=0; app.dynv[i]; i+=2) {
1635 if (!DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG)
1636 app.dynv[i+1] = (size_t)&debug;
1637 if (DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG_INDIRECT) {
1638 size_t *ptr = (size_t *) app.dynv[i+1];
1639 *ptr = (size_t)&debug;
1643 /* The main program must be relocated LAST since it may contin
1644 * copy relocations which depend on libraries' relocations. */
1645 reloc_all(app.next);
1649 if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
1650 void *initial_tls = calloc(libc.tls_size, 1);
1652 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1653 argv[0], libc.tls_size);
1656 if (__init_tp(__copy_tls(initial_tls)) < 0) {
1660 size_t tmp_tls_size = libc.tls_size;
1661 pthread_t self = __pthread_self();
1662 /* Temporarily set the tls size to the full size of
1663 * builtin_tls so that __copy_tls will use the same layout
1664 * as it did for before. Then check, just to be safe. */
1665 libc.tls_size = sizeof builtin_tls;
1666 if (__copy_tls((void*)builtin_tls) != self) a_crash();
1667 libc.tls_size = tmp_tls_size;
1669 static_tls_cnt = tls_cnt;
1671 if (ldso_fail) _exit(127);
1672 if (ldd_mode) _exit(0);
1674 /* Switch to runtime mode: any further failures in the dynamic
1675 * linker are a reportable failure rather than a fatal startup
1680 debug.bp = dl_debug_state;
1682 debug.base = ldso.base;
1686 if (replace_argv0) argv[0] = replace_argv0;
1690 CRTJMP((void *)aux[AT_ENTRY], argv-1);
1694 static void prepare_lazy(struct dso *p)
1696 size_t dyn[DYN_CNT], n, flags1=0;
1697 decode_vec(p->dynv, dyn, DYN_CNT);
1698 search_vec(p->dynv, &flags1, DT_FLAGS_1);
1699 if (dyn[DT_BIND_NOW] || (dyn[DT_FLAGS] & DF_BIND_NOW) || (flags1 & DF_1_NOW))
1701 n = dyn[DT_RELSZ]/2 + dyn[DT_RELASZ]/3 + dyn[DT_PLTRELSZ]/2 + 1;
1702 if (NEED_MIPS_GOT_RELOCS) {
1703 size_t j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1704 size_t i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1707 p->lazy = calloc(n, 3*sizeof(size_t));
1709 error("Error preparing lazy relocation for %s: %m", p->name);
1710 longjmp(*rtld_fail, 1);
1712 p->lazy_next = lazy_head;
1716 void *dlopen(const char *file, int mode)
1718 struct dso *volatile p, *orig_tail, *orig_syms_tail, *orig_lazy_head, *next;
1719 struct tls_module *orig_tls_tail;
1720 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1725 if (!file) return head;
1727 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1728 pthread_rwlock_wrlock(&lock);
1732 orig_tls_tail = tls_tail;
1733 orig_tls_cnt = tls_cnt;
1734 orig_tls_offset = tls_offset;
1735 orig_tls_align = tls_align;
1736 orig_lazy_head = lazy_head;
1737 orig_syms_tail = syms_tail;
1739 noload = mode & RTLD_NOLOAD;
1742 if (setjmp(*rtld_fail)) {
1743 /* Clean up anything new that was (partially) loaded */
1744 revert_syms(orig_syms_tail);
1745 for (p=orig_tail->next; p; p=next) {
1747 while (p->td_index) {
1748 void *tmp = p->td_index->next;
1753 if (p->rpath != p->rpath_orig)
1755 if (p->deps != &nodeps_dummy)
1760 if (!orig_tls_tail) libc.tls_head = 0;
1761 tls_tail = orig_tls_tail;
1762 if (tls_tail) tls_tail->next = 0;
1763 tls_cnt = orig_tls_cnt;
1764 tls_offset = orig_tls_offset;
1765 tls_align = orig_tls_align;
1766 lazy_head = orig_lazy_head;
1771 } else p = load_library(file, head);
1775 "Library %s is not already loaded" :
1776 "Error loading shared library %s: %m",
1781 /* First load handling */
1782 int first_load = !p->deps;
1785 if (!p->relocated && (mode & RTLD_LAZY)) {
1787 for (i=0; p->deps[i]; i++)
1788 if (!p->deps[i]->relocated)
1789 prepare_lazy(p->deps[i]);
1792 if (first_load || (mode & RTLD_GLOBAL)) {
1793 /* Make new symbols global, at least temporarily, so we can do
1794 * relocations. If not RTLD_GLOBAL, this is reverted below. */
1796 for (i=0; p->deps[i]; i++)
1797 add_syms(p->deps[i]);
1803 /* If RTLD_GLOBAL was not specified, undo any new additions
1804 * to the global symbol table. This is a nop if the library was
1805 * previously loaded and already global. */
1806 if (!(mode & RTLD_GLOBAL))
1807 revert_syms(orig_syms_tail);
1809 /* Processing of deferred lazy relocations must not happen until
1810 * the new libraries are committed; otherwise we could end up with
1811 * relocations resolved to symbol definitions that get removed. */
1820 pthread_rwlock_unlock(&lock);
1821 if (p) do_init_fini(orig_tail);
1822 pthread_setcancelstate(cs, 0);
1826 __attribute__((__visibility__("hidden")))
1827 int __dl_invalid_handle(void *h)
1830 for (p=head; p; p=p->next) if (h==p) return 0;
1831 error("Invalid library handle %p", (void *)h);
1835 static void *addr2dso(size_t a)
1839 if (DL_FDPIC) for (p=head; p; p=p->next) {
1841 if (a-(size_t)p->funcdescs < i*sizeof(*p->funcdescs))
1844 for (p=head; p; p=p->next) {
1845 if (DL_FDPIC && p->loadmap) {
1846 for (i=0; i<p->loadmap->nsegs; i++) {
1847 if (a-p->loadmap->segs[i].p_vaddr
1848 < p->loadmap->segs[i].p_memsz)
1852 if (a-(size_t)p->map < p->map_len)
1859 void *__tls_get_addr(tls_mod_off_t *);
1861 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1864 uint32_t h = 0, gh = 0, *ght;
1866 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1867 if (p == RTLD_DEFAULT) {
1869 } else if (p == RTLD_NEXT) {
1870 p = addr2dso((size_t)ra);
1874 struct symdef def = find_sym(p, s, 0);
1875 if (!def.sym) goto failed;
1876 if ((def.sym->st_info&0xf) == STT_TLS)
1877 return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value});
1878 if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
1879 return def.dso->funcdescs + (def.sym - def.dso->syms);
1880 return laddr(def.dso, def.sym->st_value);
1882 if (__dl_invalid_handle(p))
1884 if ((ght = p->ghashtab)) {
1886 sym = gnu_lookup(gh, ght, p, s);
1889 sym = sysv_lookup(s, h, p);
1891 if (sym && (sym->st_info&0xf) == STT_TLS)
1892 return __tls_get_addr((tls_mod_off_t []){p->tls_id, sym->st_value});
1893 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
1894 return p->funcdescs + (sym - p->syms);
1895 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1896 return laddr(p, sym->st_value);
1897 for (i=0; p->deps[i]; i++) {
1898 if ((ght = p->deps[i]->ghashtab)) {
1899 if (!gh) gh = gnu_hash(s);
1900 sym = gnu_lookup(gh, ght, p->deps[i], s);
1902 if (!h) h = sysv_hash(s);
1903 sym = sysv_lookup(s, h, p->deps[i]);
1905 if (sym && (sym->st_info&0xf) == STT_TLS)
1906 return __tls_get_addr((tls_mod_off_t []){p->deps[i]->tls_id, sym->st_value});
1907 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
1908 return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
1909 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1910 return laddr(p->deps[i], sym->st_value);
1913 error("Symbol not found: %s", s);
1917 int dladdr(const void *addr, Dl_info *info)
1925 pthread_rwlock_rdlock(&lock);
1926 p = addr2dso((size_t)addr);
1927 pthread_rwlock_unlock(&lock);
1932 strings = p->strings;
1933 nsym = count_syms(p);
1936 size_t idx = ((size_t)addr-(size_t)p->funcdescs)
1937 / sizeof(*p->funcdescs);
1938 if (idx < nsym && (sym[idx].st_info&0xf) == STT_FUNC) {
1939 best = p->funcdescs + idx;
1940 bestsym = sym + idx;
1944 if (!best) for (; nsym; nsym--, sym++) {
1946 && (1<<(sym->st_info&0xf) & OK_TYPES)
1947 && (1<<(sym->st_info>>4) & OK_BINDS)) {
1948 void *symaddr = laddr(p, sym->st_value);
1949 if (symaddr > addr || symaddr < best)
1953 if (addr == symaddr)
1958 if (!best) return 0;
1960 if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
1961 best = p->funcdescs + (bestsym - p->syms);
1963 info->dli_fname = p->name;
1964 info->dli_fbase = p->base;
1965 info->dli_sname = strings + bestsym->st_name;
1966 info->dli_saddr = best;
1971 __attribute__((__visibility__("hidden")))
1972 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1975 pthread_rwlock_rdlock(&lock);
1976 res = do_dlsym(p, s, ra);
1977 pthread_rwlock_unlock(&lock);
1981 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
1983 struct dso *current;
1984 struct dl_phdr_info info;
1986 for(current = head; current;) {
1987 info.dlpi_addr = (uintptr_t)current->base;
1988 info.dlpi_name = current->name;
1989 info.dlpi_phdr = current->phdr;
1990 info.dlpi_phnum = current->phnum;
1991 info.dlpi_adds = gencnt;
1993 info.dlpi_tls_modid = current->tls_id;
1994 info.dlpi_tls_data = current->tls.image;
1996 ret = (callback)(&info, sizeof (info), data);
1998 if (ret != 0) break;
2000 pthread_rwlock_rdlock(&lock);
2001 current = current->next;
2002 pthread_rwlock_unlock(&lock);
2007 __attribute__((__visibility__("hidden")))
2008 void __dl_vseterr(const char *, va_list);
2010 static void error(const char *fmt, ...)
2015 vdprintf(2, fmt, ap);
2021 __dl_vseterr(fmt, ap);