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. */
481 static void reclaim(struct dso *dso, size_t start, size_t end)
483 void __malloc_donate(char *, char *);
484 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
485 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
486 if (start >= end) return;
487 __malloc_donate(laddr(dso, start), laddr(dso, end));
490 static void reclaim_gaps(struct dso *dso)
492 Phdr *ph = dso->phdr;
493 size_t phcnt = dso->phnum;
495 if (DL_FDPIC) return; // FIXME
496 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
497 if (ph->p_type!=PT_LOAD) continue;
498 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
499 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
500 reclaim(dso, ph->p_vaddr+ph->p_memsz,
501 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
505 static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t off)
507 static int no_map_fixed;
510 q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
511 if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
515 /* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
516 if (flags & MAP_ANONYMOUS) {
521 if (lseek(fd, off, SEEK_SET) < 0) return MAP_FAILED;
522 for (q=p; n; q+=r, off+=r, n-=r) {
524 if (r < 0 && errno != EINTR) return MAP_FAILED;
533 static void unmap_library(struct dso *dso)
537 for (i=0; i<dso->loadmap->nsegs; i++) {
538 if (!dso->loadmap->segs[i].p_memsz)
540 munmap((void *)dso->loadmap->segs[i].addr,
541 dso->loadmap->segs[i].p_memsz);
544 } else if (dso->map && dso->map_len) {
545 munmap(dso->map, dso->map_len);
549 static void *map_library(int fd, struct dso *dso)
551 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
552 void *allocated_buf=0;
554 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
555 size_t this_min, this_max;
561 unsigned char *map=MAP_FAILED, *base;
566 ssize_t l = read(fd, buf, sizeof buf);
569 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
571 phsize = eh->e_phentsize * eh->e_phnum;
572 if (phsize > sizeof buf - sizeof *eh) {
573 allocated_buf = malloc(phsize);
574 if (!allocated_buf) return 0;
575 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
576 if (l < 0) goto error;
577 if (l != phsize) goto noexec;
578 ph = ph0 = allocated_buf;
579 } else if (eh->e_phoff + phsize > l) {
580 l = pread(fd, buf+1, phsize, eh->e_phoff);
581 if (l < 0) goto error;
582 if (l != phsize) goto noexec;
583 ph = ph0 = (void *)(buf + 1);
585 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
587 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
588 if (ph->p_type == PT_DYNAMIC) {
590 } else if (ph->p_type == PT_TLS) {
591 tls_image = ph->p_vaddr;
592 dso->tls.align = ph->p_align;
593 dso->tls.len = ph->p_filesz;
594 dso->tls.size = ph->p_memsz;
595 } else if (ph->p_type == PT_GNU_RELRO) {
596 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
597 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
599 if (ph->p_type != PT_LOAD) continue;
601 if (ph->p_vaddr < addr_min) {
602 addr_min = ph->p_vaddr;
603 off_start = ph->p_offset;
604 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
605 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
606 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
608 if (ph->p_vaddr+ph->p_memsz > addr_max) {
609 addr_max = ph->p_vaddr+ph->p_memsz;
612 if (!dyn) goto noexec;
613 if (DL_FDPIC && !(eh->e_flags & FDPIC_CONSTDISP_FLAG)) {
614 dso->loadmap = calloc(1, sizeof *dso->loadmap
615 + nsegs * sizeof *dso->loadmap->segs);
616 if (!dso->loadmap) goto error;
617 dso->loadmap->nsegs = nsegs;
618 for (ph=ph0, i=0; i<nsegs; ph=(void *)((char *)ph+eh->e_phentsize)) {
619 if (ph->p_type != PT_LOAD) continue;
620 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
621 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
622 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
623 map = mmap(0, ph->p_memsz + (ph->p_vaddr & PAGE_SIZE-1),
625 fd, ph->p_offset & -PAGE_SIZE);
626 if (map == MAP_FAILED) {
630 dso->loadmap->segs[i].addr = (size_t)map +
631 (ph->p_vaddr & PAGE_SIZE-1);
632 dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
633 dso->loadmap->segs[i].p_memsz = ph->p_memsz;
635 if (prot & PROT_WRITE) {
636 size_t brk = (ph->p_vaddr & PAGE_SIZE-1)
638 size_t pgbrk = brk + PAGE_SIZE-1 & -PAGE_SIZE;
639 size_t pgend = brk + ph->p_memsz - ph->p_filesz
640 + PAGE_SIZE-1 & -PAGE_SIZE;
641 if (pgend > pgbrk && mmap_fixed(map+pgbrk,
643 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
644 -1, off_start) == MAP_FAILED)
646 memset(map + brk, 0, pgbrk-brk);
649 map = (void *)dso->loadmap->segs[0].addr;
653 addr_max += PAGE_SIZE-1;
654 addr_max &= -PAGE_SIZE;
655 addr_min &= -PAGE_SIZE;
656 off_start &= -PAGE_SIZE;
657 map_len = addr_max - addr_min + off_start;
658 /* The first time, we map too much, possibly even more than
659 * the length of the file. This is okay because we will not
660 * use the invalid part; we just need to reserve the right
661 * amount of virtual address space to map over later. */
662 map = DL_NOMMU_SUPPORT
663 ? mmap((void *)addr_min, map_len, PROT_READ|PROT_WRITE|PROT_EXEC,
664 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
665 : mmap((void *)addr_min, map_len, prot,
666 MAP_PRIVATE, fd, off_start);
667 if (map==MAP_FAILED) goto error;
669 dso->map_len = map_len;
670 /* If the loaded file is not relocatable and the requested address is
671 * not available, then the load operation must fail. */
672 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
676 base = map - addr_min;
679 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
680 if (ph->p_type != PT_LOAD) continue;
681 /* Check if the programs headers are in this load segment, and
682 * if so, record the address for use by dl_iterate_phdr. */
683 if (!dso->phdr && eh->e_phoff >= ph->p_offset
684 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
685 dso->phdr = (void *)(base + ph->p_vaddr
686 + (eh->e_phoff-ph->p_offset));
687 dso->phnum = eh->e_phnum;
688 dso->phentsize = eh->e_phentsize;
690 /* Reuse the existing mapping for the lowest-address LOAD */
691 if ((ph->p_vaddr & -PAGE_SIZE) == addr_min && !DL_NOMMU_SUPPORT)
693 this_min = ph->p_vaddr & -PAGE_SIZE;
694 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
695 off_start = ph->p_offset & -PAGE_SIZE;
696 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
697 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
698 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
699 if (mmap_fixed(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
701 if (ph->p_memsz > ph->p_filesz) {
702 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
703 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
704 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
705 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)
709 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
710 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
711 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
718 dso->dynv = laddr(dso, dyn);
719 if (dso->tls.size) dso->tls.image = laddr(dso, tls_image);
725 if (map!=MAP_FAILED) unmap_library(dso);
730 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
735 s += strspn(s, ":\n");
736 l = strcspn(s, ":\n");
737 if (l-1 >= INT_MAX) return -1;
738 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
739 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
747 /* Any negative value but -1 will inhibit
748 * futher path search. */
756 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
759 const char *s, *t, *origin;
761 if (p->rpath || !p->rpath_orig) return 0;
762 if (!strchr(p->rpath_orig, '$')) {
763 p->rpath = p->rpath_orig;
768 while ((t=strchr(s, '$'))) {
769 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
774 if (n > SSIZE_MAX/PATH_MAX) return 0;
776 if (p->kernel_mapped) {
777 /* $ORIGIN searches cannot be performed for the main program
778 * when it is suid/sgid/AT_SECURE. This is because the
779 * pathname is under the control of the caller of execve.
780 * For libraries, however, $ORIGIN can be processed safely
781 * since the library's pathname came from a trusted source
782 * (either system paths or a call to dlopen). */
785 l = readlink("/proc/self/exe", buf, buf_size);
786 if (l == -1) switch (errno) {
801 t = strrchr(origin, '/');
805 /* Normally p->name will always be an absolute or relative
806 * pathname containing at least one '/' character, but in the
807 * case where ldso was invoked as a command to execute a
808 * program in the working directory, app.name may not. Fix. */
812 /* Disallow non-absolute origins for suid/sgid/AT_SECURE. */
813 if (libc.secure && *origin != '/')
815 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
816 if (!p->rpath) return -1;
820 while ((t=strchr(s, '$'))) {
823 memcpy(d, origin, l);
825 /* It was determined previously that the '$' is followed
826 * either by "ORIGIN" or "{ORIGIN}". */
827 s = t + 7 + 2*(t[1]=='{');
833 static void decode_dyn(struct dso *p)
836 decode_vec(p->dynv, dyn, DYN_CNT);
837 p->syms = laddr(p, dyn[DT_SYMTAB]);
838 p->strings = laddr(p, dyn[DT_STRTAB]);
839 if (dyn[0]&(1<<DT_HASH))
840 p->hashtab = laddr(p, dyn[DT_HASH]);
841 if (dyn[0]&(1<<DT_RPATH))
842 p->rpath_orig = p->strings + dyn[DT_RPATH];
843 if (dyn[0]&(1<<DT_RUNPATH))
844 p->rpath_orig = p->strings + dyn[DT_RUNPATH];
845 if (dyn[0]&(1<<DT_PLTGOT))
846 p->got = laddr(p, dyn[DT_PLTGOT]);
847 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
848 p->ghashtab = laddr(p, *dyn);
849 if (search_vec(p->dynv, dyn, DT_VERSYM))
850 p->versym = laddr(p, *dyn);
853 static size_t count_syms(struct dso *p)
855 if (p->hashtab) return p->hashtab[1];
858 uint32_t *buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
860 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
861 if (buckets[i] > nsym)
865 hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
867 while (!(*hashval++ & 1));
872 static void *dl_mmap(size_t n)
875 int prot = PROT_READ|PROT_WRITE, flags = MAP_ANONYMOUS|MAP_PRIVATE;
877 p = (void *)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
879 p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
881 return p == MAP_FAILED ? 0 : p;
884 static void makefuncdescs(struct dso *p)
886 static int self_done;
887 size_t nsym = count_syms(p);
888 size_t i, size = nsym * sizeof(*p->funcdescs);
891 p->funcdescs = dl_mmap(size);
894 p->funcdescs = malloc(size);
897 if (!runtime) a_crash();
898 error("Error allocating function descriptors for %s", p->name);
899 longjmp(*rtld_fail, 1);
901 for (i=0; i<nsym; i++) {
902 if ((p->syms[i].st_info&0xf)==STT_FUNC && p->syms[i].st_shndx) {
903 p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
904 p->funcdescs[i].got = p->got;
906 p->funcdescs[i].addr = 0;
907 p->funcdescs[i].got = 0;
912 static struct dso *load_library(const char *name, struct dso *needed_by)
914 char buf[2*NAME_MAX+2];
915 const char *pathname;
917 struct dso *p, temp_dso = {0};
929 /* Catch and block attempts to reload the implementation itself */
930 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
931 static const char reserved[] =
932 "c.pthread.rt.m.dl.util.xnet.";
933 const char *rp, *next;
934 for (rp=reserved; *rp; rp=next) {
935 next = strchr(rp, '.') + 1;
936 if (strncmp(name+3, rp, next-rp) == 0)
941 /* Track which names have been resolved
942 * and only report each one once. */
943 static unsigned reported;
944 unsigned mask = 1U<<(rp-reserved);
945 if (!(reported & mask)) {
947 dprintf(1, "\t%s => %s (%p)\n",
955 if (!strcmp(name, ldso.name)) is_self = 1;
964 if (strchr(name, '/')) {
966 fd = open(name, O_RDONLY|O_CLOEXEC);
968 /* Search for the name to see if it's already loaded */
969 for (p=head->next; p; p=p->next) {
970 if (p->shortname && !strcmp(p->shortname, name)) {
974 if (strlen(name) > NAME_MAX) return 0;
976 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
977 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
978 if (fixup_rpath(p, buf, sizeof buf) < 0)
979 fd = -2; /* Inhibit further search. */
981 fd = path_open(name, p->rpath, buf, sizeof buf);
987 if (ldso.name[0]=='/') {
989 for (s=t=z=ldso.name; *s; s++)
990 if (*s=='/') z=t, t=s;
991 prefix_len = z-ldso.name;
992 if (prefix_len < PATH_MAX)
999 char etc_ldso_path[prefix_len + 1
1000 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
1001 snprintf(etc_ldso_path, sizeof etc_ldso_path,
1002 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
1003 (int)prefix_len, prefix);
1004 FILE *f = fopen(etc_ldso_path, "rbe");
1006 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
1011 } else if (errno != ENOENT) {
1015 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
1016 fd = path_open(name, sys_path, buf, sizeof buf);
1020 if (fd < 0) return 0;
1021 if (fstat(fd, &st) < 0) {
1025 for (p=head->next; p; p=p->next) {
1026 if (p->dev == st.st_dev && p->ino == st.st_ino) {
1027 /* If this library was previously loaded with a
1028 * pathname but a search found the same inode,
1029 * setup its shortname so it can be found by name. */
1030 if (!p->shortname && pathname != name)
1031 p->shortname = strrchr(p->name, '/')+1;
1036 map = noload ? 0 : map_library(fd, &temp_dso);
1040 /* Avoid the danger of getting two versions of libc mapped into the
1041 * same process when an absolute pathname was used. The symbols
1042 * checked are chosen to catch both musl and glibc, and to avoid
1043 * false positives from interposition-hack libraries. */
1044 decode_dyn(&temp_dso);
1045 if (find_sym(&temp_dso, "__libc_start_main", 1).sym &&
1046 find_sym(&temp_dso, "stdin", 1).sym) {
1047 unmap_library(&temp_dso);
1048 return load_library("libc.so", needed_by);
1050 /* Past this point, if we haven't reached runtime yet, ldso has
1051 * committed either to use the mapped library or to abort execution.
1052 * Unmapping is not possible, so we can safely reclaim gaps. */
1053 if (!runtime) reclaim_gaps(&temp_dso);
1055 /* Allocate storage for the new DSO. When there is TLS, this
1056 * storage must include a reservation for all pre-existing
1057 * threads to obtain copies of both the new TLS, and an
1058 * extended DTV capable of storing an additional slot for
1059 * the newly-loaded DSO. */
1060 alloc_size = sizeof *p + strlen(pathname) + 1;
1061 if (runtime && temp_dso.tls.image) {
1062 size_t per_th = temp_dso.tls.size + temp_dso.tls.align
1063 + sizeof(void *) * (tls_cnt+3);
1064 n_th = libc.threads_minus_1 + 1;
1065 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
1066 else alloc_size += n_th * per_th;
1068 p = calloc(1, alloc_size);
1070 unmap_library(&temp_dso);
1073 memcpy(p, &temp_dso, sizeof temp_dso);
1076 p->needed_by = needed_by;
1078 strcpy(p->name, pathname);
1079 /* Add a shortname only if name arg was not an explicit pathname. */
1080 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
1082 p->tls_id = ++tls_cnt;
1083 tls_align = MAXP2(tls_align, p->tls.align);
1085 p->tls.offset = tls_offset + ( (tls_align-1) &
1086 -(tls_offset + (uintptr_t)p->tls.image) );
1087 tls_offset += p->tls.size;
1089 tls_offset += p->tls.size + p->tls.align - 1;
1090 tls_offset -= (tls_offset + (uintptr_t)p->tls.image)
1092 p->tls.offset = tls_offset;
1094 p->new_dtv = (void *)(-sizeof(size_t) &
1095 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
1096 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
1097 if (tls_tail) tls_tail->next = &p->tls;
1098 else libc.tls_head = &p->tls;
1106 if (DL_FDPIC) makefuncdescs(p);
1108 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
1113 static void load_deps(struct dso *p)
1116 struct dso ***deps = &p->deps, **tmp, *dep;
1117 for (; p; p=p->next) {
1118 for (i=0; p->dynv[i]; i+=2) {
1119 if (p->dynv[i] != DT_NEEDED) continue;
1120 dep = load_library(p->strings + p->dynv[i+1], p);
1122 error("Error loading shared library %s: %m (needed by %s)",
1123 p->strings + p->dynv[i+1], p->name);
1124 if (runtime) longjmp(*rtld_fail, 1);
1128 tmp = realloc(*deps, sizeof(*tmp)*(ndeps+2));
1129 if (!tmp) longjmp(*rtld_fail, 1);
1136 if (!*deps) *deps = (struct dso **)&nodeps_dummy;
1139 static void load_preload(char *s)
1143 for (z=s; *z; s=z) {
1144 for ( ; *s && (isspace(*s) || *s==':'); s++);
1145 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
1153 static void add_syms(struct dso *p)
1155 if (!p->syms_next && syms_tail != p) {
1156 syms_tail->syms_next = p;
1161 static void revert_syms(struct dso *old_tail)
1163 struct dso *p, *next;
1164 /* Chop off the tail of the list of dsos that participate in
1165 * the global symbol table, reverting them to RTLD_LOCAL. */
1166 for (p=old_tail; p; p=next) {
1167 next = p->syms_next;
1170 syms_tail = old_tail;
1173 static void do_mips_relocs(struct dso *p, size_t *got)
1175 size_t i, j, rel[2];
1176 unsigned char *base = p->base;
1177 i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
1181 while (i--) *got++ += (size_t)base;
1183 j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1184 i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1185 Sym *sym = p->syms + j;
1186 rel[0] = (unsigned char *)got - base;
1187 for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
1188 rel[1] = R_INFO(sym-p->syms, R_MIPS_JUMP_SLOT);
1189 do_relocs(p, rel, sizeof rel, 2);
1193 static void reloc_all(struct dso *p)
1195 size_t dyn[DYN_CNT];
1196 for (; p; p=p->next) {
1197 if (p->relocated) continue;
1198 decode_vec(p->dynv, dyn, DYN_CNT);
1199 if (NEED_MIPS_GOT_RELOCS)
1200 do_mips_relocs(p, laddr(p, dyn[DT_PLTGOT]));
1201 do_relocs(p, laddr(p, dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
1202 2+(dyn[DT_PLTREL]==DT_RELA));
1203 do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
1204 do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);
1206 if (head != &ldso && p->relro_start != p->relro_end &&
1207 mprotect(laddr(p, p->relro_start), p->relro_end-p->relro_start, PROT_READ)
1208 && errno != ENOSYS) {
1209 error("Error relocating %s: RELRO protection failed: %m",
1211 if (runtime) longjmp(*rtld_fail, 1);
1218 static void kernel_mapped_dso(struct dso *p)
1220 size_t min_addr = -1, max_addr = 0, cnt;
1222 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
1223 if (ph->p_type == PT_DYNAMIC) {
1224 p->dynv = laddr(p, ph->p_vaddr);
1225 } else if (ph->p_type == PT_GNU_RELRO) {
1226 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
1227 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
1229 if (ph->p_type != PT_LOAD) continue;
1230 if (ph->p_vaddr < min_addr)
1231 min_addr = ph->p_vaddr;
1232 if (ph->p_vaddr+ph->p_memsz > max_addr)
1233 max_addr = ph->p_vaddr+ph->p_memsz;
1235 min_addr &= -PAGE_SIZE;
1236 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
1237 p->map = p->base + min_addr;
1238 p->map_len = max_addr - min_addr;
1239 p->kernel_mapped = 1;
1242 void __libc_exit_fini()
1245 size_t dyn[DYN_CNT];
1246 for (p=fini_head; p; p=p->fini_next) {
1247 if (!p->constructed) continue;
1248 decode_vec(p->dynv, dyn, DYN_CNT);
1249 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
1250 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
1251 size_t *fn = (size_t *)laddr(p, dyn[DT_FINI_ARRAY])+n;
1252 while (n--) ((void (*)(void))*--fn)();
1254 #ifndef NO_LEGACY_INITFINI
1255 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
1256 fpaddr(p, dyn[DT_FINI])();
1261 static void do_init_fini(struct dso *p)
1263 size_t dyn[DYN_CNT];
1264 int need_locking = libc.threads_minus_1;
1265 /* Allow recursive calls that arise when a library calls
1266 * dlopen from one of its constructors, but block any
1267 * other threads until all ctors have finished. */
1268 if (need_locking) pthread_mutex_lock(&init_fini_lock);
1269 for (; p; p=p->prev) {
1270 if (p->constructed) continue;
1272 decode_vec(p->dynv, dyn, DYN_CNT);
1273 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
1274 p->fini_next = fini_head;
1277 #ifndef NO_LEGACY_INITFINI
1278 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
1279 fpaddr(p, dyn[DT_INIT])();
1281 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
1282 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
1283 size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
1284 while (n--) ((void (*)(void))*fn++)();
1286 if (!need_locking && libc.threads_minus_1) {
1288 pthread_mutex_lock(&init_fini_lock);
1291 if (need_locking) pthread_mutex_unlock(&init_fini_lock);
1294 void __libc_start_init(void)
1299 static void dl_debug_state(void)
1303 weak_alias(dl_debug_state, _dl_debug_state);
1305 void __init_tls(size_t *auxv)
1309 __attribute__((__visibility__("hidden")))
1310 void *__tls_get_new(tls_mod_off_t *v)
1312 pthread_t self = __pthread_self();
1314 /* Block signals to make accessing new TLS async-signal-safe */
1316 __block_all_sigs(&set);
1317 if (v[0]<=(size_t)self->dtv[0]) {
1318 __restore_sigs(&set);
1319 return (char *)self->dtv[v[0]]+v[1]+DTP_OFFSET;
1322 /* This is safe without any locks held because, if the caller
1323 * is able to request the Nth entry of the DTV, the DSO list
1324 * must be valid at least that far out and it was synchronized
1325 * at program startup or by an already-completed call to dlopen. */
1327 for (p=head; p->tls_id != v[0]; p=p->next);
1329 /* Get new DTV space from new DSO if needed */
1330 if (v[0] > (size_t)self->dtv[0]) {
1331 void **newdtv = p->new_dtv +
1332 (v[0]+1)*a_fetch_add(&p->new_dtv_idx,1);
1333 memcpy(newdtv, self->dtv,
1334 ((size_t)self->dtv[0]+1) * sizeof(void *));
1335 newdtv[0] = (void *)v[0];
1336 self->dtv = self->dtv_copy = newdtv;
1339 /* Get new TLS memory from all new DSOs up to the requested one */
1341 for (p=head; ; p=p->next) {
1342 if (!p->tls_id || self->dtv[p->tls_id]) continue;
1343 mem = p->new_tls + (p->tls.size + p->tls.align)
1344 * a_fetch_add(&p->new_tls_idx,1);
1345 mem += ((uintptr_t)p->tls.image - (uintptr_t)mem)
1347 self->dtv[p->tls_id] = mem;
1348 memcpy(mem, p->tls.image, p->tls.len);
1349 if (p->tls_id == v[0]) break;
1351 __restore_sigs(&set);
1352 return mem + v[1] + DTP_OFFSET;
1355 static void update_tls_size()
1357 libc.tls_cnt = tls_cnt;
1358 libc.tls_align = tls_align;
1359 libc.tls_size = ALIGN(
1360 (1+tls_cnt) * sizeof(void *) +
1362 sizeof(struct pthread) +
1367 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1368 * following stage 2 and stage 3 functions via primitive symbolic lookup
1369 * since it does not have access to their addresses to begin with. */
1371 /* Stage 2 of the dynamic linker is called after relative relocations
1372 * have been processed. It can make function calls to static functions
1373 * and access string literals and static data, but cannot use extern
1374 * symbols. Its job is to perform symbolic relocations on the dynamic
1375 * linker itself, but some of the relocations performed may need to be
1376 * replaced later due to copy relocations in the main program. */
1378 __attribute__((__visibility__("hidden")))
1379 void __dls2(unsigned char *base, size_t *sp)
1382 void *p1 = (void *)sp[-2];
1383 void *p2 = (void *)sp[-1];
1385 size_t *auxv, aux[AUX_CNT];
1386 for (auxv=sp+1+*sp+1; *auxv; auxv++); auxv++;
1387 decode_vec(auxv, aux, AUX_CNT);
1388 if (aux[AT_BASE]) ldso.base = (void *)aux[AT_BASE];
1389 else ldso.base = (void *)(aux[AT_PHDR] & -4096);
1391 app_loadmap = p2 ? p1 : 0;
1392 ldso.loadmap = p2 ? p2 : p1;
1393 ldso.base = laddr(&ldso, 0);
1397 Ehdr *ehdr = (void *)ldso.base;
1398 ldso.name = ldso.shortname = "libc.so";
1399 ldso.phnum = ehdr->e_phnum;
1400 ldso.phdr = laddr(&ldso, ehdr->e_phoff);
1401 ldso.phentsize = ehdr->e_phentsize;
1402 kernel_mapped_dso(&ldso);
1405 if (DL_FDPIC) makefuncdescs(&ldso);
1407 /* Prepare storage for to save clobbered REL addends so they
1408 * can be reused in stage 3. There should be very few. If
1409 * something goes wrong and there are a huge number, abort
1410 * instead of risking stack overflow. */
1411 size_t dyn[DYN_CNT];
1412 decode_vec(ldso.dynv, dyn, DYN_CNT);
1413 size_t *rel = laddr(&ldso, dyn[DT_REL]);
1414 size_t rel_size = dyn[DT_RELSZ];
1415 size_t symbolic_rel_cnt = 0;
1416 apply_addends_to = rel;
1417 for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
1418 if (!IS_RELATIVE(rel[1], ldso.syms)) symbolic_rel_cnt++;
1419 if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
1420 size_t addends[symbolic_rel_cnt+1];
1421 saved_addends = addends;
1428 /* Call dynamic linker stage-3, __dls3, looking it up
1429 * symbolically as a barrier against moving the address
1430 * load across the above relocation processing. */
1431 struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1432 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp);
1433 else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp);
1436 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1437 * fully functional. Its job is to load (if not already loaded) and
1438 * process dependencies and relocations for the main application and
1439 * transfer control to its entry point. */
1441 _Noreturn void __dls3(size_t *sp)
1443 static struct dso app, vdso;
1444 size_t aux[AUX_CNT], *auxv;
1446 char *env_preload=0;
1447 char *replace_argv0=0;
1450 char **argv = (void *)(sp+1);
1451 char **argv_orig = argv;
1452 char **envp = argv+argc+1;
1454 /* Find aux vector just past environ[] and use it to initialize
1455 * global data that may be needed before we can make syscalls. */
1457 for (i=argc+1; argv[i]; i++);
1458 libc.auxv = auxv = (void *)(argv+i+1);
1459 decode_vec(auxv, aux, AUX_CNT);
1460 __hwcap = aux[AT_HWCAP];
1461 libc.page_size = aux[AT_PAGESZ];
1462 libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1463 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
1465 /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1466 * use during dynamic linking. If possible it will also serve as the
1467 * thread pointer at runtime. */
1468 libc.tls_size = sizeof builtin_tls;
1469 libc.tls_align = tls_align;
1470 if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1474 /* Only trust user/env if kernel says we're not suid/sgid */
1476 env_path = getenv("LD_LIBRARY_PATH");
1477 env_preload = getenv("LD_PRELOAD");
1480 /* If the main program was already loaded by the kernel,
1481 * AT_PHDR will point to some location other than the dynamic
1482 * linker's program headers. */
1483 if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1484 size_t interp_off = 0;
1485 size_t tls_image = 0;
1486 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1487 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1488 app.phnum = aux[AT_PHNUM];
1489 app.phentsize = aux[AT_PHENT];
1490 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1491 if (phdr->p_type == PT_PHDR)
1492 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1493 else if (phdr->p_type == PT_INTERP)
1494 interp_off = (size_t)phdr->p_vaddr;
1495 else if (phdr->p_type == PT_TLS) {
1496 tls_image = phdr->p_vaddr;
1497 app.tls.len = phdr->p_filesz;
1498 app.tls.size = phdr->p_memsz;
1499 app.tls.align = phdr->p_align;
1502 if (DL_FDPIC) app.loadmap = app_loadmap;
1503 if (app.tls.size) app.tls.image = laddr(&app, tls_image);
1504 if (interp_off) ldso.name = laddr(&app, interp_off);
1505 if ((aux[0] & (1UL<<AT_EXECFN))
1506 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1507 app.name = (char *)aux[AT_EXECFN];
1510 kernel_mapped_dso(&app);
1513 char *ldname = argv[0];
1514 size_t l = strlen(ldname);
1515 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1517 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1518 char *opt = argv[0]+2;
1519 *argv++ = (void *)-1;
1522 } else if (!memcmp(opt, "list", 5)) {
1524 } else if (!memcmp(opt, "library-path", 12)) {
1525 if (opt[12]=='=') env_path = opt+13;
1526 else if (opt[12]) *argv = 0;
1527 else if (*argv) env_path = *argv++;
1528 } else if (!memcmp(opt, "preload", 7)) {
1529 if (opt[7]=='=') env_preload = opt+8;
1530 else if (opt[7]) *argv = 0;
1531 else if (*argv) env_preload = *argv++;
1532 } else if (!memcmp(opt, "argv0", 5)) {
1533 if (opt[5]=='=') replace_argv0 = opt+6;
1534 else if (opt[5]) *argv = 0;
1535 else if (*argv) replace_argv0 = *argv++;
1540 argv[-1] = (void *)(argc - (argv-argv_orig));
1542 dprintf(2, "musl libc (" LDSO_ARCH ")\n"
1544 "Dynamic Program Loader\n"
1545 "Usage: %s [options] [--] pathname%s\n",
1546 __libc_get_version(), ldname,
1547 ldd_mode ? "" : " [args]");
1550 fd = open(argv[0], O_RDONLY);
1552 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1555 Ehdr *ehdr = (void *)map_library(fd, &app);
1557 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1563 aux[AT_ENTRY] = (size_t)laddr(&app, ehdr->e_entry);
1564 /* Find the name that would have been used for the dynamic
1565 * linker had ldd not taken its place. */
1567 for (i=0; i<app.phnum; i++) {
1568 if (app.phdr[i].p_type == PT_INTERP)
1569 ldso.name = laddr(&app, app.phdr[i].p_vaddr);
1571 dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1575 libc.tls_head = tls_tail = &app.tls;
1576 app.tls_id = tls_cnt = 1;
1579 tls_offset = app.tls.size
1580 + ( -((uintptr_t)app.tls.image + app.tls.size)
1581 & (app.tls.align-1) );
1583 tls_offset = app.tls.offset = app.tls.size
1584 + ( -((uintptr_t)app.tls.image + app.tls.size)
1585 & (app.tls.align-1) );
1587 tls_align = MAXP2(tls_align, app.tls.align);
1591 makefuncdescs(&app);
1593 app.loadmap = (void *)&app_dummy_loadmap;
1594 app.loadmap->nsegs = 1;
1595 app.loadmap->segs[0].addr = (size_t)app.map;
1596 app.loadmap->segs[0].p_vaddr = (size_t)app.map
1598 app.loadmap->segs[0].p_memsz = app.map_len;
1600 argv[-3] = (void *)app.loadmap;
1603 /* Initial dso chain consists only of the app. */
1604 head = tail = syms_tail = &app;
1606 /* Donate unused parts of app and library mapping to malloc */
1608 reclaim_gaps(&ldso);
1610 /* Load preload/needed libraries, add symbols to global namespace. */
1611 if (env_preload) load_preload(env_preload);
1613 for (struct dso *p=head; p; p=p->next)
1616 /* Attach to vdso, if provided by the kernel, last so that it does
1617 * not become part of the global namespace. */
1618 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR) && vdso_base) {
1619 Ehdr *ehdr = (void *)vdso_base;
1620 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
1621 vdso.phnum = ehdr->e_phnum;
1622 vdso.phentsize = ehdr->e_phentsize;
1623 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1624 if (phdr->p_type == PT_DYNAMIC)
1625 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
1626 if (phdr->p_type == PT_LOAD)
1627 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1630 vdso.shortname = "linux-gate.so.1";
1638 for (i=0; app.dynv[i]; i+=2) {
1639 if (!DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG)
1640 app.dynv[i+1] = (size_t)&debug;
1641 if (DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG_INDIRECT) {
1642 size_t *ptr = (size_t *) app.dynv[i+1];
1643 *ptr = (size_t)&debug;
1647 /* The main program must be relocated LAST since it may contin
1648 * copy relocations which depend on libraries' relocations. */
1649 reloc_all(app.next);
1653 if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
1654 void *initial_tls = calloc(libc.tls_size, 1);
1656 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1657 argv[0], libc.tls_size);
1660 if (__init_tp(__copy_tls(initial_tls)) < 0) {
1664 size_t tmp_tls_size = libc.tls_size;
1665 pthread_t self = __pthread_self();
1666 /* Temporarily set the tls size to the full size of
1667 * builtin_tls so that __copy_tls will use the same layout
1668 * as it did for before. Then check, just to be safe. */
1669 libc.tls_size = sizeof builtin_tls;
1670 if (__copy_tls((void*)builtin_tls) != self) a_crash();
1671 libc.tls_size = tmp_tls_size;
1673 static_tls_cnt = tls_cnt;
1675 if (ldso_fail) _exit(127);
1676 if (ldd_mode) _exit(0);
1678 /* Switch to runtime mode: any further failures in the dynamic
1679 * linker are a reportable failure rather than a fatal startup
1684 debug.bp = dl_debug_state;
1686 debug.base = ldso.base;
1690 if (replace_argv0) argv[0] = replace_argv0;
1694 CRTJMP((void *)aux[AT_ENTRY], argv-1);
1698 static void prepare_lazy(struct dso *p)
1700 size_t dyn[DYN_CNT], n, flags1=0;
1701 decode_vec(p->dynv, dyn, DYN_CNT);
1702 search_vec(p->dynv, &flags1, DT_FLAGS_1);
1703 if (dyn[DT_BIND_NOW] || (dyn[DT_FLAGS] & DF_BIND_NOW) || (flags1 & DF_1_NOW))
1705 n = dyn[DT_RELSZ]/2 + dyn[DT_RELASZ]/3 + dyn[DT_PLTRELSZ]/2 + 1;
1706 if (NEED_MIPS_GOT_RELOCS) {
1707 size_t j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1708 size_t i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1711 p->lazy = calloc(n, 3*sizeof(size_t));
1713 error("Error preparing lazy relocation for %s: %m", p->name);
1714 longjmp(*rtld_fail, 1);
1716 p->lazy_next = lazy_head;
1720 void *dlopen(const char *file, int mode)
1722 struct dso *volatile p, *orig_tail, *orig_syms_tail, *orig_lazy_head, *next;
1723 struct tls_module *orig_tls_tail;
1724 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1729 if (!file) return head;
1731 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1732 pthread_rwlock_wrlock(&lock);
1736 orig_tls_tail = tls_tail;
1737 orig_tls_cnt = tls_cnt;
1738 orig_tls_offset = tls_offset;
1739 orig_tls_align = tls_align;
1740 orig_lazy_head = lazy_head;
1741 orig_syms_tail = syms_tail;
1743 noload = mode & RTLD_NOLOAD;
1746 if (setjmp(*rtld_fail)) {
1747 /* Clean up anything new that was (partially) loaded */
1748 revert_syms(orig_syms_tail);
1749 for (p=orig_tail->next; p; p=next) {
1751 while (p->td_index) {
1752 void *tmp = p->td_index->next;
1757 if (p->rpath != p->rpath_orig)
1759 if (p->deps != &nodeps_dummy)
1764 if (!orig_tls_tail) libc.tls_head = 0;
1765 tls_tail = orig_tls_tail;
1766 if (tls_tail) tls_tail->next = 0;
1767 tls_cnt = orig_tls_cnt;
1768 tls_offset = orig_tls_offset;
1769 tls_align = orig_tls_align;
1770 lazy_head = orig_lazy_head;
1775 } else p = load_library(file, head);
1779 "Library %s is not already loaded" :
1780 "Error loading shared library %s: %m",
1785 /* First load handling */
1786 int first_load = !p->deps;
1789 if (!p->relocated && (mode & RTLD_LAZY)) {
1791 for (i=0; p->deps[i]; i++)
1792 if (!p->deps[i]->relocated)
1793 prepare_lazy(p->deps[i]);
1796 if (first_load || (mode & RTLD_GLOBAL)) {
1797 /* Make new symbols global, at least temporarily, so we can do
1798 * relocations. If not RTLD_GLOBAL, this is reverted below. */
1800 for (i=0; p->deps[i]; i++)
1801 add_syms(p->deps[i]);
1807 /* If RTLD_GLOBAL was not specified, undo any new additions
1808 * to the global symbol table. This is a nop if the library was
1809 * previously loaded and already global. */
1810 if (!(mode & RTLD_GLOBAL))
1811 revert_syms(orig_syms_tail);
1813 /* Processing of deferred lazy relocations must not happen until
1814 * the new libraries are committed; otherwise we could end up with
1815 * relocations resolved to symbol definitions that get removed. */
1824 pthread_rwlock_unlock(&lock);
1825 if (p) do_init_fini(orig_tail);
1826 pthread_setcancelstate(cs, 0);
1830 __attribute__((__visibility__("hidden")))
1831 int __dl_invalid_handle(void *h)
1834 for (p=head; p; p=p->next) if (h==p) return 0;
1835 error("Invalid library handle %p", (void *)h);
1839 static void *addr2dso(size_t a)
1843 if (DL_FDPIC) for (p=head; p; p=p->next) {
1845 if (a-(size_t)p->funcdescs < i*sizeof(*p->funcdescs))
1848 for (p=head; p; p=p->next) {
1849 if (DL_FDPIC && p->loadmap) {
1850 for (i=0; i<p->loadmap->nsegs; i++) {
1851 if (a-p->loadmap->segs[i].p_vaddr
1852 < p->loadmap->segs[i].p_memsz)
1856 if (a-(size_t)p->map < p->map_len)
1863 void *__tls_get_addr(tls_mod_off_t *);
1865 static void *do_dlsym(struct dso *p, const char *s, void *ra)
1868 uint32_t h = 0, gh = 0, *ght;
1870 if (p == head || p == RTLD_DEFAULT || p == RTLD_NEXT) {
1871 if (p == RTLD_DEFAULT) {
1873 } else if (p == RTLD_NEXT) {
1874 p = addr2dso((size_t)ra);
1878 struct symdef def = find_sym(p, s, 0);
1879 if (!def.sym) goto failed;
1880 if ((def.sym->st_info&0xf) == STT_TLS)
1881 return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value});
1882 if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
1883 return def.dso->funcdescs + (def.sym - def.dso->syms);
1884 return laddr(def.dso, def.sym->st_value);
1886 if (__dl_invalid_handle(p))
1888 if ((ght = p->ghashtab)) {
1890 sym = gnu_lookup(gh, ght, p, s);
1893 sym = sysv_lookup(s, h, p);
1895 if (sym && (sym->st_info&0xf) == STT_TLS)
1896 return __tls_get_addr((tls_mod_off_t []){p->tls_id, sym->st_value});
1897 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
1898 return p->funcdescs + (sym - p->syms);
1899 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1900 return laddr(p, sym->st_value);
1901 for (i=0; p->deps[i]; i++) {
1902 if ((ght = p->deps[i]->ghashtab)) {
1903 if (!gh) gh = gnu_hash(s);
1904 sym = gnu_lookup(gh, ght, p->deps[i], s);
1906 if (!h) h = sysv_hash(s);
1907 sym = sysv_lookup(s, h, p->deps[i]);
1909 if (sym && (sym->st_info&0xf) == STT_TLS)
1910 return __tls_get_addr((tls_mod_off_t []){p->deps[i]->tls_id, sym->st_value});
1911 if (DL_FDPIC && sym && sym->st_shndx && (sym->st_info&0xf) == STT_FUNC)
1912 return p->deps[i]->funcdescs + (sym - p->deps[i]->syms);
1913 if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
1914 return laddr(p->deps[i], sym->st_value);
1917 error("Symbol not found: %s", s);
1921 int dladdr(const void *addr, Dl_info *info)
1929 pthread_rwlock_rdlock(&lock);
1930 p = addr2dso((size_t)addr);
1931 pthread_rwlock_unlock(&lock);
1936 strings = p->strings;
1937 nsym = count_syms(p);
1940 size_t idx = ((size_t)addr-(size_t)p->funcdescs)
1941 / sizeof(*p->funcdescs);
1942 if (idx < nsym && (sym[idx].st_info&0xf) == STT_FUNC) {
1943 best = p->funcdescs + idx;
1944 bestsym = sym + idx;
1948 if (!best) for (; nsym; nsym--, sym++) {
1950 && (1<<(sym->st_info&0xf) & OK_TYPES)
1951 && (1<<(sym->st_info>>4) & OK_BINDS)) {
1952 void *symaddr = laddr(p, sym->st_value);
1953 if (symaddr > addr || symaddr < best)
1957 if (addr == symaddr)
1962 if (!best) return 0;
1964 if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
1965 best = p->funcdescs + (bestsym - p->syms);
1967 info->dli_fname = p->name;
1968 info->dli_fbase = p->map;
1969 info->dli_sname = strings + bestsym->st_name;
1970 info->dli_saddr = best;
1975 __attribute__((__visibility__("hidden")))
1976 void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
1979 pthread_rwlock_rdlock(&lock);
1980 res = do_dlsym(p, s, ra);
1981 pthread_rwlock_unlock(&lock);
1985 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
1987 struct dso *current;
1988 struct dl_phdr_info info;
1990 for(current = head; current;) {
1991 info.dlpi_addr = (uintptr_t)current->base;
1992 info.dlpi_name = current->name;
1993 info.dlpi_phdr = current->phdr;
1994 info.dlpi_phnum = current->phnum;
1995 info.dlpi_adds = gencnt;
1997 info.dlpi_tls_modid = current->tls_id;
1998 info.dlpi_tls_data = current->tls.image;
2000 ret = (callback)(&info, sizeof (info), data);
2002 if (ret != 0) break;
2004 pthread_rwlock_rdlock(&lock);
2005 current = current->next;
2006 pthread_rwlock_unlock(&lock);
2011 __attribute__((__visibility__("hidden")))
2012 void __dl_vseterr(const char *, va_list);
2014 static void error(const char *fmt, ...)
2019 vdprintf(2, fmt, ap);
2025 __dl_vseterr(fmt, ap);