2 #define SYSCALL_NO_TLS 1
21 #include <semaphore.h>
22 #include <sys/membarrier.h>
23 #include "pthread_impl.h"
26 #include "malloc_impl.h"
28 static void error(const char *, ...);
30 #define MAXP2(a,b) (-(-(a)&-(b)))
31 #define ALIGN(x,y) ((x)+(y)-1 & -(y))
33 #define container_of(p,t,m) ((t*)((char *)(p)-offsetof(t,m)))
34 #define countof(a) ((sizeof (a))/(sizeof (a)[0]))
46 struct td_index *next;
51 struct fdpic_loadmap *loadmap;
57 struct dso *next, *prev;
67 struct dso *syms_next, *lazy_next;
68 size_t *lazy, lazy_cnt;
79 struct dso **deps, *needed_by;
83 char *rpath_orig, *rpath;
84 struct tls_module tls;
86 size_t relro_start, relro_end;
88 unsigned char *new_tls;
89 struct td_index *td_index;
90 struct dso *fini_next;
95 struct fdpic_loadmap *loadmap;
110 typedef void (*stage3_func)(size_t *, size_t *);
112 static struct builtin_tls {
117 #define MIN_TLS_ALIGN offsetof(struct builtin_tls, pt)
119 #define ADDEND_LIMIT 4096
120 static size_t *saved_addends, *apply_addends_to;
122 static struct dso ldso;
123 static struct dso *head, *tail, *fini_head, *syms_tail, *lazy_head;
124 static char *env_path, *sys_path;
125 static unsigned long long gencnt;
128 static int ldso_fail;
130 static int shutting_down;
131 static jmp_buf *rtld_fail;
132 static pthread_rwlock_t lock;
133 static struct debug debug;
134 static struct tls_module *tls_tail;
135 static size_t tls_cnt, tls_offset, tls_align = MIN_TLS_ALIGN;
136 static size_t static_tls_cnt;
137 static pthread_mutex_t init_fini_lock;
138 static pthread_cond_t ctor_cond;
139 static struct dso *builtin_deps[2];
140 static struct dso *const no_deps[1];
141 static struct dso *builtin_ctor_queue[4];
142 static struct dso **main_ctor_queue;
143 static struct fdpic_loadmap *app_loadmap;
144 static struct fdpic_dummy_loadmap app_dummy_loadmap;
146 struct debug *_dl_debug_addr = &debug;
148 extern hidden int __malloc_replaced;
150 hidden void (*const __init_array_start)(void)=0, (*const __fini_array_start)(void)=0;
152 extern hidden void (*const __init_array_end)(void), (*const __fini_array_end)(void);
154 weak_alias(__init_array_start, __init_array_end);
155 weak_alias(__fini_array_start, __fini_array_end);
157 static int dl_strcmp(const char *l, const char *r)
159 for (; *l==*r && *l; l++, r++);
160 return *(unsigned char *)l - *(unsigned char *)r;
162 #define strcmp(l,r) dl_strcmp(l,r)
164 /* Compute load address for a virtual address in a given dso. */
166 static void *laddr(const struct dso *p, size_t v)
169 if (!p->loadmap) return p->base + v;
170 for (j=0; v-p->loadmap->segs[j].p_vaddr >= p->loadmap->segs[j].p_memsz; j++);
171 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
173 static void *laddr_pg(const struct dso *p, size_t v)
176 size_t pgsz = PAGE_SIZE;
177 if (!p->loadmap) return p->base + v;
179 size_t a = p->loadmap->segs[j].p_vaddr;
180 size_t b = a + p->loadmap->segs[j].p_memsz;
186 return (void *)(v - p->loadmap->segs[j].p_vaddr + p->loadmap->segs[j].addr);
188 #define fpaddr(p, v) ((void (*)())&(struct funcdesc){ \
189 laddr(p, v), (p)->got })
191 #define laddr(p, v) (void *)((p)->base + (v))
192 #define laddr_pg(p, v) laddr(p, v)
193 #define fpaddr(p, v) ((void (*)())laddr(p, v))
196 static void decode_vec(size_t *v, size_t *a, size_t cnt)
199 for (i=0; i<cnt; i++) a[i] = 0;
200 for (; v[0]; v+=2) if (v[0]-1<cnt-1) {
206 static int search_vec(size_t *v, size_t *r, size_t key)
208 for (; v[0]!=key; v+=2)
214 static uint32_t sysv_hash(const char *s0)
216 const unsigned char *s = (void *)s0;
222 return h & 0xfffffff;
225 static uint32_t gnu_hash(const char *s0)
227 const unsigned char *s = (void *)s0;
228 uint_fast32_t h = 5381;
234 static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
237 Sym *syms = dso->syms;
238 Elf_Symndx *hashtab = dso->hashtab;
239 char *strings = dso->strings;
240 for (i=hashtab[2+h%hashtab[0]]; i; i=hashtab[2+hashtab[0]+i]) {
241 if ((!dso->versym || dso->versym[i] >= 0)
242 && (!strcmp(s, strings+syms[i].st_name)))
248 static Sym *gnu_lookup(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s)
250 uint32_t nbuckets = hashtab[0];
251 uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
252 uint32_t i = buckets[h1 % nbuckets];
256 uint32_t *hashval = buckets + nbuckets + (i - hashtab[1]);
258 for (h1 |= 1; ; i++) {
259 uint32_t h2 = *hashval++;
260 if ((h1 == (h2|1)) && (!dso->versym || dso->versym[i] >= 0)
261 && !strcmp(s, dso->strings + dso->syms[i].st_name))
269 static Sym *gnu_lookup_filtered(uint32_t h1, uint32_t *hashtab, struct dso *dso, const char *s, uint32_t fofs, size_t fmask)
271 const size_t *bloomwords = (const void *)(hashtab+4);
272 size_t f = bloomwords[fofs & (hashtab[2]-1)];
273 if (!(f & fmask)) return 0;
275 f >>= (h1 >> hashtab[3]) % (8 * sizeof f);
276 if (!(f & 1)) return 0;
278 return gnu_lookup(h1, hashtab, dso, s);
281 #define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON | 1<<STT_TLS)
282 #define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK | 1<<STB_GNU_UNIQUE)
284 #ifndef ARCH_SYM_REJECT_UND
285 #define ARCH_SYM_REJECT_UND(s) 0
288 #if defined(__GNUC__)
289 __attribute__((always_inline))
291 static inline struct symdef find_sym2(struct dso *dso, const char *s, int need_def, int use_deps)
293 uint32_t h = 0, gh = gnu_hash(s), gho = gh / (8*sizeof(size_t)), *ght;
294 size_t ghm = 1ul << gh % (8*sizeof(size_t));
295 struct symdef def = {0};
296 struct dso **deps = use_deps ? dso->deps : 0;
297 for (; dso; dso=use_deps ? *deps++ : dso->syms_next) {
299 if ((ght = dso->ghashtab)) {
300 sym = gnu_lookup_filtered(gh, ght, dso, s, gho, ghm);
302 if (!h) h = sysv_hash(s);
303 sym = sysv_lookup(s, h, dso);
307 if (need_def || (sym->st_info&0xf) == STT_TLS
308 || ARCH_SYM_REJECT_UND(sym))
311 if ((sym->st_info&0xf) != STT_TLS)
313 if (!(1<<(sym->st_info&0xf) & OK_TYPES)) continue;
314 if (!(1<<(sym->st_info>>4) & OK_BINDS)) continue;
322 static struct symdef find_sym(struct dso *dso, const char *s, int need_def)
324 return find_sym2(dso, s, need_def, 0);
327 static void do_relocs(struct dso *dso, size_t *rel, size_t rel_size, size_t stride)
329 unsigned char *base = dso->base;
330 Sym *syms = dso->syms;
331 char *strings = dso->strings;
342 int skip_relative = 0, reuse_addends = 0, save_slot = 0;
345 /* Only ldso's REL table needs addend saving/reuse. */
346 if (rel == apply_addends_to)
351 for (; rel_size; rel+=stride, rel_size-=stride*sizeof(size_t)) {
352 if (skip_relative && IS_RELATIVE(rel[1], dso->syms)) continue;
353 type = R_TYPE(rel[1]);
354 if (type == REL_NONE) continue;
355 reloc_addr = laddr(dso, rel[0]);
359 } else if (type==REL_GOT || type==REL_PLT|| type==REL_COPY) {
361 } else if (reuse_addends) {
362 /* Save original addend in stage 2 where the dso
363 * chain consists of just ldso; otherwise read back
364 * saved addend since the inline one was clobbered. */
366 saved_addends[save_slot] = *reloc_addr;
367 addend = saved_addends[save_slot++];
369 addend = *reloc_addr;
372 sym_index = R_SYM(rel[1]);
374 sym = syms + sym_index;
375 name = strings + sym->st_name;
376 ctx = type==REL_COPY ? head->syms_next : head;
377 def = (sym->st_info>>4) == STB_LOCAL
378 ? (struct symdef){ .dso = dso, .sym = sym }
379 : find_sym(ctx, name, type==REL_PLT);
380 if (!def.sym && (sym->st_shndx != SHN_UNDEF
381 || sym->st_info>>4 != STB_WEAK)) {
382 if (dso->lazy && (type==REL_PLT || type==REL_GOT)) {
383 dso->lazy[3*dso->lazy_cnt+0] = rel[0];
384 dso->lazy[3*dso->lazy_cnt+1] = rel[1];
385 dso->lazy[3*dso->lazy_cnt+2] = addend;
389 error("Error relocating %s: %s: symbol not found",
391 if (runtime) longjmp(*rtld_fail, 1);
400 sym_val = def.sym ? (size_t)laddr(def.dso, def.sym->st_value) : 0;
401 tls_val = def.sym ? def.sym->st_value : 0;
403 if ((type == REL_TPOFF || type == REL_TPOFF_NEG)
404 && def.dso->tls_id > static_tls_cnt) {
405 error("Error relocating %s: %s: initial-exec TLS "
406 "resolves to dynamic definition in %s",
407 dso->name, name, def.dso->name);
408 longjmp(*rtld_fail, 1);
415 addend -= (size_t)reloc_addr;
419 *reloc_addr = sym_val + addend;
422 memcpy(reloc_addr, &(size_t){sym_val + addend}, sizeof(size_t));
425 *reloc_addr = (size_t)base + addend;
428 if (sym) *reloc_addr = sym_val + addend;
429 else *reloc_addr = (size_t)base + addend;
432 memcpy(reloc_addr, (void *)sym_val, sym->st_size);
435 *(uint32_t *)reloc_addr = sym_val + addend
436 - (size_t)reloc_addr;
439 *reloc_addr = def.sym ? (size_t)(def.dso->funcdescs
440 + (def.sym - def.dso->syms)) : 0;
442 case REL_FUNCDESC_VAL:
443 if ((sym->st_info&0xf) == STT_SECTION) *reloc_addr += sym_val;
444 else *reloc_addr = sym_val;
445 reloc_addr[1] = def.sym ? (size_t)def.dso->got : 0;
448 *reloc_addr = def.dso->tls_id;
451 *reloc_addr = tls_val + addend - DTP_OFFSET;
455 *reloc_addr = tls_val + def.dso->tls.offset + TPOFF_K + addend;
459 *reloc_addr = tls_val - def.dso->tls.offset + addend;
462 *reloc_addr = def.dso->tls.offset - tls_val + addend;
466 if (stride<3) addend = reloc_addr[1];
467 if (def.dso->tls_id > static_tls_cnt) {
468 struct td_index *new = malloc(sizeof *new);
471 "Error relocating %s: cannot allocate TLSDESC for %s",
472 dso->name, sym ? name : "(local)" );
473 longjmp(*rtld_fail, 1);
475 new->next = dso->td_index;
477 new->args[0] = def.dso->tls_id;
478 new->args[1] = tls_val + addend - DTP_OFFSET;
479 reloc_addr[0] = (size_t)__tlsdesc_dynamic;
480 reloc_addr[1] = (size_t)new;
482 reloc_addr[0] = (size_t)__tlsdesc_static;
484 reloc_addr[1] = tls_val + def.dso->tls.offset
487 reloc_addr[1] = tls_val - def.dso->tls.offset
491 #ifdef TLSDESC_BACKWARDS
492 /* Some archs (32-bit ARM at least) invert the order of
493 * the descriptor members. Fix them up here. */
494 size_t tmp = reloc_addr[0];
495 reloc_addr[0] = reloc_addr[1];
500 error("Error relocating %s: unsupported relocation type %d",
502 if (runtime) longjmp(*rtld_fail, 1);
508 static void redo_lazy_relocs()
510 struct dso *p = lazy_head, *next;
514 size_t size = p->lazy_cnt*3*sizeof(size_t);
516 do_relocs(p, p->lazy, size, 3);
518 p->lazy_next = lazy_head;
528 /* A huge hack: to make up for the wastefulness of shared libraries
529 * needing at least a page of dirty memory even if they have no global
530 * data, we reclaim the gaps at the beginning and end of writable maps
531 * and "donate" them to the heap. */
533 static void reclaim(struct dso *dso, size_t start, size_t end)
535 if (start >= dso->relro_start && start < dso->relro_end) start = dso->relro_end;
536 if (end >= dso->relro_start && end < dso->relro_end) end = dso->relro_start;
537 if (start >= end) return;
538 char *base = laddr_pg(dso, start);
539 __malloc_donate(base, base+(end-start));
542 static void reclaim_gaps(struct dso *dso)
544 Phdr *ph = dso->phdr;
545 size_t phcnt = dso->phnum;
547 for (; phcnt--; ph=(void *)((char *)ph+dso->phentsize)) {
548 if (ph->p_type!=PT_LOAD) continue;
549 if ((ph->p_flags&(PF_R|PF_W))!=(PF_R|PF_W)) continue;
550 reclaim(dso, ph->p_vaddr & -PAGE_SIZE, ph->p_vaddr);
551 reclaim(dso, ph->p_vaddr+ph->p_memsz,
552 ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE);
556 static void *mmap_fixed(void *p, size_t n, int prot, int flags, int fd, off_t off)
558 static int no_map_fixed;
561 q = mmap(p, n, prot, flags|MAP_FIXED, fd, off);
562 if (!DL_NOMMU_SUPPORT || q != MAP_FAILED || errno != EINVAL)
566 /* Fallbacks for MAP_FIXED failure on NOMMU kernels. */
567 if (flags & MAP_ANONYMOUS) {
572 if (lseek(fd, off, SEEK_SET) < 0) return MAP_FAILED;
573 for (q=p; n; q+=r, off+=r, n-=r) {
575 if (r < 0 && errno != EINTR) return MAP_FAILED;
584 static void unmap_library(struct dso *dso)
588 for (i=0; i<dso->loadmap->nsegs; i++) {
589 if (!dso->loadmap->segs[i].p_memsz)
591 munmap((void *)dso->loadmap->segs[i].addr,
592 dso->loadmap->segs[i].p_memsz);
595 } else if (dso->map && dso->map_len) {
596 munmap(dso->map, dso->map_len);
600 static void *map_library(int fd, struct dso *dso)
602 Ehdr buf[(896+sizeof(Ehdr))/sizeof(Ehdr)];
603 void *allocated_buf=0;
605 size_t addr_min=SIZE_MAX, addr_max=0, map_len;
606 size_t this_min, this_max;
612 unsigned char *map=MAP_FAILED, *base;
617 ssize_t l = read(fd, buf, sizeof buf);
620 if (l<sizeof *eh || (eh->e_type != ET_DYN && eh->e_type != ET_EXEC))
622 phsize = eh->e_phentsize * eh->e_phnum;
623 if (phsize > sizeof buf - sizeof *eh) {
624 allocated_buf = malloc(phsize);
625 if (!allocated_buf) return 0;
626 l = pread(fd, allocated_buf, phsize, eh->e_phoff);
627 if (l < 0) goto error;
628 if (l != phsize) goto noexec;
629 ph = ph0 = allocated_buf;
630 } else if (eh->e_phoff + phsize > l) {
631 l = pread(fd, buf+1, phsize, eh->e_phoff);
632 if (l < 0) goto error;
633 if (l != phsize) goto noexec;
634 ph = ph0 = (void *)(buf + 1);
636 ph = ph0 = (void *)((char *)buf + eh->e_phoff);
638 for (i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
639 if (ph->p_type == PT_DYNAMIC) {
641 } else if (ph->p_type == PT_TLS) {
642 tls_image = ph->p_vaddr;
643 dso->tls.align = ph->p_align;
644 dso->tls.len = ph->p_filesz;
645 dso->tls.size = ph->p_memsz;
646 } else if (ph->p_type == PT_GNU_RELRO) {
647 dso->relro_start = ph->p_vaddr & -PAGE_SIZE;
648 dso->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
649 } else if (ph->p_type == PT_GNU_STACK) {
650 if (!runtime && ph->p_memsz > __default_stacksize) {
651 __default_stacksize =
652 ph->p_memsz < DEFAULT_STACK_MAX ?
653 ph->p_memsz : DEFAULT_STACK_MAX;
656 if (ph->p_type != PT_LOAD) continue;
658 if (ph->p_vaddr < addr_min) {
659 addr_min = ph->p_vaddr;
660 off_start = ph->p_offset;
661 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
662 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
663 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
665 if (ph->p_vaddr+ph->p_memsz > addr_max) {
666 addr_max = ph->p_vaddr+ph->p_memsz;
669 if (!dyn) goto noexec;
670 if (DL_FDPIC && !(eh->e_flags & FDPIC_CONSTDISP_FLAG)) {
671 dso->loadmap = calloc(1, sizeof *dso->loadmap
672 + nsegs * sizeof *dso->loadmap->segs);
673 if (!dso->loadmap) goto error;
674 dso->loadmap->nsegs = nsegs;
675 for (ph=ph0, i=0; i<nsegs; ph=(void *)((char *)ph+eh->e_phentsize)) {
676 if (ph->p_type != PT_LOAD) continue;
677 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
678 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
679 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
680 map = mmap(0, ph->p_memsz + (ph->p_vaddr & PAGE_SIZE-1),
682 fd, ph->p_offset & -PAGE_SIZE);
683 if (map == MAP_FAILED) {
687 dso->loadmap->segs[i].addr = (size_t)map +
688 (ph->p_vaddr & PAGE_SIZE-1);
689 dso->loadmap->segs[i].p_vaddr = ph->p_vaddr;
690 dso->loadmap->segs[i].p_memsz = ph->p_memsz;
692 if (prot & PROT_WRITE) {
693 size_t brk = (ph->p_vaddr & PAGE_SIZE-1)
695 size_t pgbrk = brk + PAGE_SIZE-1 & -PAGE_SIZE;
696 size_t pgend = brk + ph->p_memsz - ph->p_filesz
697 + PAGE_SIZE-1 & -PAGE_SIZE;
698 if (pgend > pgbrk && mmap_fixed(map+pgbrk,
700 MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
701 -1, off_start) == MAP_FAILED)
703 memset(map + brk, 0, pgbrk-brk);
706 map = (void *)dso->loadmap->segs[0].addr;
710 addr_max += PAGE_SIZE-1;
711 addr_max &= -PAGE_SIZE;
712 addr_min &= -PAGE_SIZE;
713 off_start &= -PAGE_SIZE;
714 map_len = addr_max - addr_min + off_start;
715 /* The first time, we map too much, possibly even more than
716 * the length of the file. This is okay because we will not
717 * use the invalid part; we just need to reserve the right
718 * amount of virtual address space to map over later. */
719 map = DL_NOMMU_SUPPORT
720 ? mmap((void *)addr_min, map_len, PROT_READ|PROT_WRITE|PROT_EXEC,
721 MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
722 : mmap((void *)addr_min, map_len, prot,
723 MAP_PRIVATE, fd, off_start);
724 if (map==MAP_FAILED) goto error;
726 dso->map_len = map_len;
727 /* If the loaded file is not relocatable and the requested address is
728 * not available, then the load operation must fail. */
729 if (eh->e_type != ET_DYN && addr_min && map!=(void *)addr_min) {
733 base = map - addr_min;
736 for (ph=ph0, i=eh->e_phnum; i; i--, ph=(void *)((char *)ph+eh->e_phentsize)) {
737 if (ph->p_type != PT_LOAD) continue;
738 /* Check if the programs headers are in this load segment, and
739 * if so, record the address for use by dl_iterate_phdr. */
740 if (!dso->phdr && eh->e_phoff >= ph->p_offset
741 && eh->e_phoff+phsize <= ph->p_offset+ph->p_filesz) {
742 dso->phdr = (void *)(base + ph->p_vaddr
743 + (eh->e_phoff-ph->p_offset));
744 dso->phnum = eh->e_phnum;
745 dso->phentsize = eh->e_phentsize;
747 this_min = ph->p_vaddr & -PAGE_SIZE;
748 this_max = ph->p_vaddr+ph->p_memsz+PAGE_SIZE-1 & -PAGE_SIZE;
749 off_start = ph->p_offset & -PAGE_SIZE;
750 prot = (((ph->p_flags&PF_R) ? PROT_READ : 0) |
751 ((ph->p_flags&PF_W) ? PROT_WRITE: 0) |
752 ((ph->p_flags&PF_X) ? PROT_EXEC : 0));
753 /* Reuse the existing mapping for the lowest-address LOAD */
754 if ((ph->p_vaddr & -PAGE_SIZE) != addr_min || DL_NOMMU_SUPPORT)
755 if (mmap_fixed(base+this_min, this_max-this_min, prot, MAP_PRIVATE|MAP_FIXED, fd, off_start) == MAP_FAILED)
757 if (ph->p_memsz > ph->p_filesz && (ph->p_flags&PF_W)) {
758 size_t brk = (size_t)base+ph->p_vaddr+ph->p_filesz;
759 size_t pgbrk = brk+PAGE_SIZE-1 & -PAGE_SIZE;
760 memset((void *)brk, 0, pgbrk-brk & PAGE_SIZE-1);
761 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)
765 for (i=0; ((size_t *)(base+dyn))[i]; i+=2)
766 if (((size_t *)(base+dyn))[i]==DT_TEXTREL) {
767 if (mprotect(map, map_len, PROT_READ|PROT_WRITE|PROT_EXEC)
774 dso->dynv = laddr(dso, dyn);
775 if (dso->tls.size) dso->tls.image = laddr(dso, tls_image);
781 if (map!=MAP_FAILED) unmap_library(dso);
786 static int path_open(const char *name, const char *s, char *buf, size_t buf_size)
791 s += strspn(s, ":\n");
792 l = strcspn(s, ":\n");
793 if (l-1 >= INT_MAX) return -1;
794 if (snprintf(buf, buf_size, "%.*s/%s", (int)l, s, name) < buf_size) {
795 if ((fd = open(buf, O_RDONLY|O_CLOEXEC))>=0) return fd;
803 /* Any negative value but -1 will inhibit
804 * futher path search. */
812 static int fixup_rpath(struct dso *p, char *buf, size_t buf_size)
815 const char *s, *t, *origin;
817 if (p->rpath || !p->rpath_orig) return 0;
818 if (!strchr(p->rpath_orig, '$')) {
819 p->rpath = p->rpath_orig;
824 while ((t=strchr(s, '$'))) {
825 if (strncmp(t, "$ORIGIN", 7) && strncmp(t, "${ORIGIN}", 9))
830 if (n > SSIZE_MAX/PATH_MAX) return 0;
832 if (p->kernel_mapped) {
833 /* $ORIGIN searches cannot be performed for the main program
834 * when it is suid/sgid/AT_SECURE. This is because the
835 * pathname is under the control of the caller of execve.
836 * For libraries, however, $ORIGIN can be processed safely
837 * since the library's pathname came from a trusted source
838 * (either system paths or a call to dlopen). */
841 l = readlink("/proc/self/exe", buf, buf_size);
842 if (l == -1) switch (errno) {
857 t = strrchr(origin, '/');
861 /* Normally p->name will always be an absolute or relative
862 * pathname containing at least one '/' character, but in the
863 * case where ldso was invoked as a command to execute a
864 * program in the working directory, app.name may not. Fix. */
868 /* Disallow non-absolute origins for suid/sgid/AT_SECURE. */
869 if (libc.secure && *origin != '/')
871 p->rpath = malloc(strlen(p->rpath_orig) + n*l + 1);
872 if (!p->rpath) return -1;
876 while ((t=strchr(s, '$'))) {
879 memcpy(d, origin, l);
881 /* It was determined previously that the '$' is followed
882 * either by "ORIGIN" or "{ORIGIN}". */
883 s = t + 7 + 2*(t[1]=='{');
889 static void decode_dyn(struct dso *p)
892 decode_vec(p->dynv, dyn, DYN_CNT);
893 p->syms = laddr(p, dyn[DT_SYMTAB]);
894 p->strings = laddr(p, dyn[DT_STRTAB]);
895 if (dyn[0]&(1<<DT_HASH))
896 p->hashtab = laddr(p, dyn[DT_HASH]);
897 if (dyn[0]&(1<<DT_RPATH))
898 p->rpath_orig = p->strings + dyn[DT_RPATH];
899 if (dyn[0]&(1<<DT_RUNPATH))
900 p->rpath_orig = p->strings + dyn[DT_RUNPATH];
901 if (dyn[0]&(1<<DT_PLTGOT))
902 p->got = laddr(p, dyn[DT_PLTGOT]);
903 if (search_vec(p->dynv, dyn, DT_GNU_HASH))
904 p->ghashtab = laddr(p, *dyn);
905 if (search_vec(p->dynv, dyn, DT_VERSYM))
906 p->versym = laddr(p, *dyn);
909 static size_t count_syms(struct dso *p)
911 if (p->hashtab) return p->hashtab[1];
914 uint32_t *buckets = p->ghashtab + 4 + (p->ghashtab[2]*sizeof(size_t)/4);
916 for (i = nsym = 0; i < p->ghashtab[0]; i++) {
917 if (buckets[i] > nsym)
921 hashval = buckets + p->ghashtab[0] + (nsym - p->ghashtab[1]);
923 while (!(*hashval++ & 1));
928 static void *dl_mmap(size_t n)
931 int prot = PROT_READ|PROT_WRITE, flags = MAP_ANONYMOUS|MAP_PRIVATE;
933 p = (void *)__syscall(SYS_mmap2, 0, n, prot, flags, -1, 0);
935 p = (void *)__syscall(SYS_mmap, 0, n, prot, flags, -1, 0);
937 return (unsigned long)p > -4096UL ? 0 : p;
940 static void makefuncdescs(struct dso *p)
942 static int self_done;
943 size_t nsym = count_syms(p);
944 size_t i, size = nsym * sizeof(*p->funcdescs);
947 p->funcdescs = dl_mmap(size);
950 p->funcdescs = malloc(size);
953 if (!runtime) a_crash();
954 error("Error allocating function descriptors for %s", p->name);
955 longjmp(*rtld_fail, 1);
957 for (i=0; i<nsym; i++) {
958 if ((p->syms[i].st_info&0xf)==STT_FUNC && p->syms[i].st_shndx) {
959 p->funcdescs[i].addr = laddr(p, p->syms[i].st_value);
960 p->funcdescs[i].got = p->got;
962 p->funcdescs[i].addr = 0;
963 p->funcdescs[i].got = 0;
968 static struct dso *load_library(const char *name, struct dso *needed_by)
970 char buf[2*NAME_MAX+2];
971 const char *pathname;
973 struct dso *p, temp_dso = {0};
985 /* Catch and block attempts to reload the implementation itself */
986 if (name[0]=='l' && name[1]=='i' && name[2]=='b') {
987 static const char reserved[] =
988 "c.pthread.rt.m.dl.util.xnet.";
989 const char *rp, *next;
990 for (rp=reserved; *rp; rp=next) {
991 next = strchr(rp, '.') + 1;
992 if (strncmp(name+3, rp, next-rp) == 0)
997 /* Track which names have been resolved
998 * and only report each one once. */
999 static unsigned reported;
1000 unsigned mask = 1U<<(rp-reserved);
1001 if (!(reported & mask)) {
1003 dprintf(1, "\t%s => %s (%p)\n",
1011 if (!strcmp(name, ldso.name)) is_self = 1;
1020 if (strchr(name, '/')) {
1022 fd = open(name, O_RDONLY|O_CLOEXEC);
1024 /* Search for the name to see if it's already loaded */
1025 for (p=head->next; p; p=p->next) {
1026 if (p->shortname && !strcmp(p->shortname, name)) {
1030 if (strlen(name) > NAME_MAX) return 0;
1032 if (env_path) fd = path_open(name, env_path, buf, sizeof buf);
1033 for (p=needed_by; fd == -1 && p; p=p->needed_by) {
1034 if (fixup_rpath(p, buf, sizeof buf) < 0)
1035 fd = -2; /* Inhibit further search. */
1037 fd = path_open(name, p->rpath, buf, sizeof buf);
1043 if (ldso.name[0]=='/') {
1045 for (s=t=z=ldso.name; *s; s++)
1046 if (*s=='/') z=t, t=s;
1047 prefix_len = z-ldso.name;
1048 if (prefix_len < PATH_MAX)
1055 char etc_ldso_path[prefix_len + 1
1056 + sizeof "/etc/ld-musl-" LDSO_ARCH ".path"];
1057 snprintf(etc_ldso_path, sizeof etc_ldso_path,
1058 "%.*s/etc/ld-musl-" LDSO_ARCH ".path",
1059 (int)prefix_len, prefix);
1060 FILE *f = fopen(etc_ldso_path, "rbe");
1062 if (getdelim(&sys_path, (size_t[1]){0}, 0, f) <= 0) {
1067 } else if (errno != ENOENT) {
1071 if (!sys_path) sys_path = "/lib:/usr/local/lib:/usr/lib";
1072 fd = path_open(name, sys_path, buf, sizeof buf);
1076 if (fd < 0) return 0;
1077 if (fstat(fd, &st) < 0) {
1081 for (p=head->next; p; p=p->next) {
1082 if (p->dev == st.st_dev && p->ino == st.st_ino) {
1083 /* If this library was previously loaded with a
1084 * pathname but a search found the same inode,
1085 * setup its shortname so it can be found by name. */
1086 if (!p->shortname && pathname != name)
1087 p->shortname = strrchr(p->name, '/')+1;
1092 map = noload ? 0 : map_library(fd, &temp_dso);
1096 /* Avoid the danger of getting two versions of libc mapped into the
1097 * same process when an absolute pathname was used. The symbols
1098 * checked are chosen to catch both musl and glibc, and to avoid
1099 * false positives from interposition-hack libraries. */
1100 decode_dyn(&temp_dso);
1101 if (find_sym(&temp_dso, "__libc_start_main", 1).sym &&
1102 find_sym(&temp_dso, "stdin", 1).sym) {
1103 unmap_library(&temp_dso);
1104 return load_library("libc.so", needed_by);
1106 /* Past this point, if we haven't reached runtime yet, ldso has
1107 * committed either to use the mapped library or to abort execution.
1108 * Unmapping is not possible, so we can safely reclaim gaps. */
1109 if (!runtime) reclaim_gaps(&temp_dso);
1111 /* Allocate storage for the new DSO. When there is TLS, this
1112 * storage must include a reservation for all pre-existing
1113 * threads to obtain copies of both the new TLS, and an
1114 * extended DTV capable of storing an additional slot for
1115 * the newly-loaded DSO. */
1116 alloc_size = sizeof *p + strlen(pathname) + 1;
1117 if (runtime && temp_dso.tls.image) {
1118 size_t per_th = temp_dso.tls.size + temp_dso.tls.align
1119 + sizeof(void *) * (tls_cnt+3);
1120 n_th = libc.threads_minus_1 + 1;
1121 if (n_th > SSIZE_MAX / per_th) alloc_size = SIZE_MAX;
1122 else alloc_size += n_th * per_th;
1124 p = calloc(1, alloc_size);
1126 unmap_library(&temp_dso);
1129 memcpy(p, &temp_dso, sizeof temp_dso);
1132 p->needed_by = needed_by;
1134 p->runtime_loaded = runtime;
1135 strcpy(p->name, pathname);
1136 /* Add a shortname only if name arg was not an explicit pathname. */
1137 if (pathname != name) p->shortname = strrchr(p->name, '/')+1;
1139 p->tls_id = ++tls_cnt;
1140 tls_align = MAXP2(tls_align, p->tls.align);
1142 p->tls.offset = tls_offset + ( (p->tls.align-1) &
1143 (-tls_offset + (uintptr_t)p->tls.image) );
1144 tls_offset = p->tls.offset + p->tls.size;
1146 tls_offset += p->tls.size + p->tls.align - 1;
1147 tls_offset -= (tls_offset + (uintptr_t)p->tls.image)
1149 p->tls.offset = tls_offset;
1151 p->new_dtv = (void *)(-sizeof(size_t) &
1152 (uintptr_t)(p->name+strlen(p->name)+sizeof(size_t)));
1153 p->new_tls = (void *)(p->new_dtv + n_th*(tls_cnt+1));
1154 if (tls_tail) tls_tail->next = &p->tls;
1155 else libc.tls_head = &p->tls;
1163 if (DL_FDPIC) makefuncdescs(p);
1165 if (ldd_mode) dprintf(1, "\t%s => %s (%p)\n", name, pathname, p->base);
1170 static void load_direct_deps(struct dso *p)
1174 if (p->deps) return;
1175 /* For head, all preloads are direct pseudo-dependencies.
1176 * Count and include them now to avoid realloc later. */
1177 if (p==head) for (struct dso *q=p->next; q; q=q->next)
1179 for (i=0; p->dynv[i]; i+=2)
1180 if (p->dynv[i] == DT_NEEDED) cnt++;
1181 /* Use builtin buffer for apps with no external deps, to
1182 * preserve property of no runtime failure paths. */
1183 p->deps = (p==head && cnt<2) ? builtin_deps :
1184 calloc(cnt+1, sizeof *p->deps);
1186 error("Error loading dependencies for %s", p->name);
1187 if (runtime) longjmp(*rtld_fail, 1);
1190 if (p==head) for (struct dso *q=p->next; q; q=q->next)
1192 for (i=0; p->dynv[i]; i+=2) {
1193 if (p->dynv[i] != DT_NEEDED) continue;
1194 struct dso *dep = load_library(p->strings + p->dynv[i+1], p);
1196 error("Error loading shared library %s: %m (needed by %s)",
1197 p->strings + p->dynv[i+1], p->name);
1198 if (runtime) longjmp(*rtld_fail, 1);
1201 p->deps[cnt++] = dep;
1204 p->ndeps_direct = cnt;
1207 static void load_deps(struct dso *p)
1209 if (p->deps) return;
1210 for (; p; p=p->next)
1211 load_direct_deps(p);
1214 static void extend_bfs_deps(struct dso *p)
1216 size_t i, j, cnt, ndeps_all;
1219 /* Can't use realloc if the original p->deps was allocated at
1220 * program entry and malloc has been replaced, or if it's
1221 * the builtin non-allocated trivial main program deps array. */
1222 int no_realloc = (__malloc_replaced && !p->runtime_loaded)
1223 || p->deps == builtin_deps;
1225 if (p->bfs_built) return;
1226 ndeps_all = p->ndeps_direct;
1228 /* Mark existing (direct) deps so they won't be duplicated. */
1229 for (i=0; p->deps[i]; i++)
1230 p->deps[i]->mark = 1;
1232 /* For each dependency already in the list, copy its list of direct
1233 * dependencies to the list, excluding any items already in the
1234 * list. Note that the list this loop iterates over will grow during
1235 * the loop, but since duplicates are excluded, growth is bounded. */
1236 for (i=0; p->deps[i]; i++) {
1237 struct dso *dep = p->deps[i];
1238 for (j=cnt=0; j<dep->ndeps_direct; j++)
1239 if (!dep->deps[j]->mark) cnt++;
1241 malloc(sizeof(*tmp) * (ndeps_all+cnt+1)) :
1242 realloc(p->deps, sizeof(*tmp) * (ndeps_all+cnt+1));
1244 error("Error recording dependencies for %s", p->name);
1245 if (runtime) longjmp(*rtld_fail, 1);
1249 memcpy(tmp, p->deps, sizeof(*tmp) * (ndeps_all+1));
1253 for (j=0; j<dep->ndeps_direct; j++) {
1254 if (dep->deps[j]->mark) continue;
1255 dep->deps[j]->mark = 1;
1256 p->deps[ndeps_all++] = dep->deps[j];
1258 p->deps[ndeps_all] = 0;
1261 for (p=head; p; p=p->next)
1265 static void load_preload(char *s)
1269 for (z=s; *z; s=z) {
1270 for ( ; *s && (isspace(*s) || *s==':'); s++);
1271 for (z=s; *z && !isspace(*z) && *z!=':'; z++);
1279 static void add_syms(struct dso *p)
1281 if (!p->syms_next && syms_tail != p) {
1282 syms_tail->syms_next = p;
1287 static void revert_syms(struct dso *old_tail)
1289 struct dso *p, *next;
1290 /* Chop off the tail of the list of dsos that participate in
1291 * the global symbol table, reverting them to RTLD_LOCAL. */
1292 for (p=old_tail; p; p=next) {
1293 next = p->syms_next;
1296 syms_tail = old_tail;
1299 static void do_mips_relocs(struct dso *p, size_t *got)
1301 size_t i, j, rel[2];
1302 unsigned char *base = p->base;
1303 i=0; search_vec(p->dynv, &i, DT_MIPS_LOCAL_GOTNO);
1307 while (i--) *got++ += (size_t)base;
1309 j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1310 i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1311 Sym *sym = p->syms + j;
1312 rel[0] = (unsigned char *)got - base;
1313 for (i-=j; i; i--, sym++, rel[0]+=sizeof(size_t)) {
1314 rel[1] = R_INFO(sym-p->syms, R_MIPS_JUMP_SLOT);
1315 do_relocs(p, rel, sizeof rel, 2);
1319 static void reloc_all(struct dso *p)
1321 size_t dyn[DYN_CNT];
1322 for (; p; p=p->next) {
1323 if (p->relocated) continue;
1324 decode_vec(p->dynv, dyn, DYN_CNT);
1325 if (NEED_MIPS_GOT_RELOCS)
1326 do_mips_relocs(p, laddr(p, dyn[DT_PLTGOT]));
1327 do_relocs(p, laddr(p, dyn[DT_JMPREL]), dyn[DT_PLTRELSZ],
1328 2+(dyn[DT_PLTREL]==DT_RELA));
1329 do_relocs(p, laddr(p, dyn[DT_REL]), dyn[DT_RELSZ], 2);
1330 do_relocs(p, laddr(p, dyn[DT_RELA]), dyn[DT_RELASZ], 3);
1332 if (head != &ldso && p->relro_start != p->relro_end &&
1333 mprotect(laddr(p, p->relro_start), p->relro_end-p->relro_start, PROT_READ)
1334 && errno != ENOSYS) {
1335 error("Error relocating %s: RELRO protection failed: %m",
1337 if (runtime) longjmp(*rtld_fail, 1);
1344 static void kernel_mapped_dso(struct dso *p)
1346 size_t min_addr = -1, max_addr = 0, cnt;
1348 for (cnt = p->phnum; cnt--; ph = (void *)((char *)ph + p->phentsize)) {
1349 if (ph->p_type == PT_DYNAMIC) {
1350 p->dynv = laddr(p, ph->p_vaddr);
1351 } else if (ph->p_type == PT_GNU_RELRO) {
1352 p->relro_start = ph->p_vaddr & -PAGE_SIZE;
1353 p->relro_end = (ph->p_vaddr + ph->p_memsz) & -PAGE_SIZE;
1354 } else if (ph->p_type == PT_GNU_STACK) {
1355 if (!runtime && ph->p_memsz > __default_stacksize) {
1356 __default_stacksize =
1357 ph->p_memsz < DEFAULT_STACK_MAX ?
1358 ph->p_memsz : DEFAULT_STACK_MAX;
1361 if (ph->p_type != PT_LOAD) continue;
1362 if (ph->p_vaddr < min_addr)
1363 min_addr = ph->p_vaddr;
1364 if (ph->p_vaddr+ph->p_memsz > max_addr)
1365 max_addr = ph->p_vaddr+ph->p_memsz;
1367 min_addr &= -PAGE_SIZE;
1368 max_addr = (max_addr + PAGE_SIZE-1) & -PAGE_SIZE;
1369 p->map = p->base + min_addr;
1370 p->map_len = max_addr - min_addr;
1371 p->kernel_mapped = 1;
1374 void __libc_exit_fini()
1377 size_t dyn[DYN_CNT];
1378 int self = __pthread_self()->tid;
1380 /* Take both locks before setting shutting_down, so that
1381 * either lock is sufficient to read its value. The lock
1382 * order matches that in dlopen to avoid deadlock. */
1383 pthread_rwlock_wrlock(&lock);
1384 pthread_mutex_lock(&init_fini_lock);
1386 pthread_rwlock_unlock(&lock);
1387 for (p=fini_head; p; p=p->fini_next) {
1388 while (p->ctor_visitor && p->ctor_visitor!=self)
1389 pthread_cond_wait(&ctor_cond, &init_fini_lock);
1390 if (!p->constructed) continue;
1391 decode_vec(p->dynv, dyn, DYN_CNT);
1392 if (dyn[0] & (1<<DT_FINI_ARRAY)) {
1393 size_t n = dyn[DT_FINI_ARRAYSZ]/sizeof(size_t);
1394 size_t *fn = (size_t *)laddr(p, dyn[DT_FINI_ARRAY])+n;
1395 while (n--) ((void (*)(void))*--fn)();
1397 #ifndef NO_LEGACY_INITFINI
1398 if ((dyn[0] & (1<<DT_FINI)) && dyn[DT_FINI])
1399 fpaddr(p, dyn[DT_FINI])();
1404 static struct dso **queue_ctors(struct dso *dso)
1406 size_t cnt, qpos, spos, i;
1407 struct dso *p, **queue, **stack;
1409 if (ldd_mode) return 0;
1411 /* Bound on queue size is the total number of indirect deps.
1412 * If a bfs deps list was built, we can use it. Otherwise,
1413 * bound by the total number of DSOs, which is always safe and
1414 * is reasonable we use it (for main app at startup). */
1415 if (dso->bfs_built) {
1416 for (cnt=0; dso->deps[cnt]; cnt++)
1417 dso->deps[cnt]->mark = 0;
1418 cnt++; /* self, not included in deps */
1420 for (cnt=0, p=head; p; cnt++, p=p->next)
1423 cnt++; /* termination slot */
1424 if (dso==head && cnt <= countof(builtin_ctor_queue))
1425 queue = builtin_ctor_queue;
1427 queue = calloc(cnt, sizeof *queue);
1430 error("Error allocating constructor queue: %m\n");
1431 if (runtime) longjmp(*rtld_fail, 1);
1435 /* Opposite ends of the allocated buffer serve as an output queue
1436 * and a working stack. Setup initial stack with just the argument
1437 * dso and initial queue empty... */
1441 stack[--spos] = dso;
1445 /* Then perform pseudo-DFS sort, but ignoring circular deps. */
1448 while (p->next_dep < p->ndeps_direct) {
1449 if (p->deps[p->next_dep]->mark) {
1453 p = p->deps[p->next_dep];
1461 for (i=0; i<qpos; i++) queue[i]->mark = 0;
1466 static void do_init_fini(struct dso **queue)
1469 size_t dyn[DYN_CNT], i;
1470 int self = __pthread_self()->tid;
1472 pthread_mutex_lock(&init_fini_lock);
1473 for (i=0; (p=queue[i]); i++) {
1474 while ((p->ctor_visitor && p->ctor_visitor!=self) || shutting_down)
1475 pthread_cond_wait(&ctor_cond, &init_fini_lock);
1476 if (p->ctor_visitor || p->constructed)
1478 p->ctor_visitor = self;
1480 decode_vec(p->dynv, dyn, DYN_CNT);
1481 if (dyn[0] & ((1<<DT_FINI) | (1<<DT_FINI_ARRAY))) {
1482 p->fini_next = fini_head;
1486 pthread_mutex_unlock(&init_fini_lock);
1488 #ifndef NO_LEGACY_INITFINI
1489 if ((dyn[0] & (1<<DT_INIT)) && dyn[DT_INIT])
1490 fpaddr(p, dyn[DT_INIT])();
1492 if (dyn[0] & (1<<DT_INIT_ARRAY)) {
1493 size_t n = dyn[DT_INIT_ARRAYSZ]/sizeof(size_t);
1494 size_t *fn = laddr(p, dyn[DT_INIT_ARRAY]);
1495 while (n--) ((void (*)(void))*fn++)();
1498 pthread_mutex_lock(&init_fini_lock);
1499 p->ctor_visitor = 0;
1501 pthread_cond_broadcast(&ctor_cond);
1503 pthread_mutex_unlock(&init_fini_lock);
1506 void __libc_start_init(void)
1508 do_init_fini(main_ctor_queue);
1509 if (!__malloc_replaced && main_ctor_queue != builtin_ctor_queue)
1510 free(main_ctor_queue);
1511 main_ctor_queue = 0;
1514 static void dl_debug_state(void)
1518 weak_alias(dl_debug_state, _dl_debug_state);
1520 void __init_tls(size_t *auxv)
1524 static void update_tls_size()
1526 libc.tls_cnt = tls_cnt;
1527 libc.tls_align = tls_align;
1528 libc.tls_size = ALIGN(
1529 (1+tls_cnt) * sizeof(void *) +
1531 sizeof(struct pthread) +
1536 static void install_new_tls(void)
1539 pthread_t self = __pthread_self(), td;
1540 struct dso *dtv_provider = container_of(tls_tail, struct dso, tls);
1541 uintptr_t (*newdtv)[tls_cnt+1] = (void *)dtv_provider->new_dtv;
1544 size_t old_cnt = self->dtv[0];
1546 __block_app_sigs(&set);
1548 /* Copy existing dtv contents from all existing threads. */
1549 for (i=0, td=self; !i || td!=self; i++, td=td->next) {
1550 memcpy(newdtv+i, td->dtv,
1551 (old_cnt+1)*sizeof(uintptr_t));
1552 newdtv[i][0] = tls_cnt;
1554 /* Install new dtls into the enlarged, uninstalled dtv copies. */
1555 for (p=head; ; p=p->next) {
1556 if (p->tls_id <= old_cnt) continue;
1557 unsigned char *mem = p->new_tls;
1558 for (j=0; j<i; j++) {
1559 unsigned char *new = mem;
1560 new += ((uintptr_t)p->tls.image - (uintptr_t)mem)
1562 memcpy(new, p->tls.image, p->tls.len);
1563 newdtv[j][p->tls_id] =
1564 (uintptr_t)new + DTP_OFFSET;
1565 mem += p->tls.size + p->tls.align;
1567 if (p->tls_id == tls_cnt) break;
1570 /* Broadcast barrier to ensure contents of new dtv is visible
1571 * if the new dtv pointer is. The __membarrier function has a
1572 * fallback emulation using signals for kernels that lack the
1573 * feature at the syscall level. */
1575 __membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0);
1577 /* Install new dtv for each thread. */
1578 for (j=0, td=self; !j || td!=self; j++, td=td->next) {
1579 td->dtv = td->dtv_copy = newdtv[j];
1583 __restore_sigs(&set);
1586 /* Stage 1 of the dynamic linker is defined in dlstart.c. It calls the
1587 * following stage 2 and stage 3 functions via primitive symbolic lookup
1588 * since it does not have access to their addresses to begin with. */
1590 /* Stage 2 of the dynamic linker is called after relative relocations
1591 * have been processed. It can make function calls to static functions
1592 * and access string literals and static data, but cannot use extern
1593 * symbols. Its job is to perform symbolic relocations on the dynamic
1594 * linker itself, but some of the relocations performed may need to be
1595 * replaced later due to copy relocations in the main program. */
1597 hidden void __dls2(unsigned char *base, size_t *sp)
1600 for (auxv=sp+1+*sp+1; *auxv; auxv++);
1603 void *p1 = (void *)sp[-2];
1604 void *p2 = (void *)sp[-1];
1606 size_t aux[AUX_CNT];
1607 decode_vec(auxv, aux, AUX_CNT);
1608 if (aux[AT_BASE]) ldso.base = (void *)aux[AT_BASE];
1609 else ldso.base = (void *)(aux[AT_PHDR] & -4096);
1611 app_loadmap = p2 ? p1 : 0;
1612 ldso.loadmap = p2 ? p2 : p1;
1613 ldso.base = laddr(&ldso, 0);
1617 Ehdr *ehdr = (void *)ldso.base;
1618 ldso.name = ldso.shortname = "libc.so";
1619 ldso.phnum = ehdr->e_phnum;
1620 ldso.phdr = laddr(&ldso, ehdr->e_phoff);
1621 ldso.phentsize = ehdr->e_phentsize;
1622 kernel_mapped_dso(&ldso);
1625 if (DL_FDPIC) makefuncdescs(&ldso);
1627 /* Prepare storage for to save clobbered REL addends so they
1628 * can be reused in stage 3. There should be very few. If
1629 * something goes wrong and there are a huge number, abort
1630 * instead of risking stack overflow. */
1631 size_t dyn[DYN_CNT];
1632 decode_vec(ldso.dynv, dyn, DYN_CNT);
1633 size_t *rel = laddr(&ldso, dyn[DT_REL]);
1634 size_t rel_size = dyn[DT_RELSZ];
1635 size_t symbolic_rel_cnt = 0;
1636 apply_addends_to = rel;
1637 for (; rel_size; rel+=2, rel_size-=2*sizeof(size_t))
1638 if (!IS_RELATIVE(rel[1], ldso.syms)) symbolic_rel_cnt++;
1639 if (symbolic_rel_cnt >= ADDEND_LIMIT) a_crash();
1640 size_t addends[symbolic_rel_cnt+1];
1641 saved_addends = addends;
1648 /* Call dynamic linker stage-2b, __dls2b, looking it up
1649 * symbolically as a barrier against moving the address
1650 * load across the above relocation processing. */
1651 struct symdef dls2b_def = find_sym(&ldso, "__dls2b", 0);
1652 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls2b_def.sym-ldso.syms])(sp, auxv);
1653 else ((stage3_func)laddr(&ldso, dls2b_def.sym->st_value))(sp, auxv);
1656 /* Stage 2b sets up a valid thread pointer, which requires relocations
1657 * completed in stage 2, and on which stage 3 is permitted to depend.
1658 * This is done as a separate stage, with symbolic lookup as a barrier,
1659 * so that loads of the thread pointer and &errno can be pure/const and
1660 * thereby hoistable. */
1662 void __dls2b(size_t *sp, size_t *auxv)
1664 /* Setup early thread pointer in builtin_tls for ldso/libc itself to
1665 * use during dynamic linking. If possible it will also serve as the
1666 * thread pointer at runtime. */
1668 libc.tls_size = sizeof builtin_tls;
1669 libc.tls_align = tls_align;
1670 if (__init_tp(__copy_tls((void *)builtin_tls)) < 0) {
1674 struct symdef dls3_def = find_sym(&ldso, "__dls3", 0);
1675 if (DL_FDPIC) ((stage3_func)&ldso.funcdescs[dls3_def.sym-ldso.syms])(sp, auxv);
1676 else ((stage3_func)laddr(&ldso, dls3_def.sym->st_value))(sp, auxv);
1679 /* Stage 3 of the dynamic linker is called with the dynamic linker/libc
1680 * fully functional. Its job is to load (if not already loaded) and
1681 * process dependencies and relocations for the main application and
1682 * transfer control to its entry point. */
1684 void __dls3(size_t *sp, size_t *auxv)
1686 static struct dso app, vdso;
1687 size_t aux[AUX_CNT];
1689 char *env_preload=0;
1690 char *replace_argv0=0;
1693 char **argv = (void *)(sp+1);
1694 char **argv_orig = argv;
1695 char **envp = argv+argc+1;
1697 /* Find aux vector just past environ[] and use it to initialize
1698 * global data that may be needed before we can make syscalls. */
1700 decode_vec(auxv, aux, AUX_CNT);
1701 __hwcap = aux[AT_HWCAP];
1702 search_vec(auxv, &__sysinfo, AT_SYSINFO);
1703 __pthread_self()->sysinfo = __sysinfo;
1704 libc.page_size = aux[AT_PAGESZ];
1705 libc.secure = ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID]
1706 || aux[AT_GID]!=aux[AT_EGID] || aux[AT_SECURE]);
1708 /* Only trust user/env if kernel says we're not suid/sgid */
1710 env_path = getenv("LD_LIBRARY_PATH");
1711 env_preload = getenv("LD_PRELOAD");
1714 /* If the main program was already loaded by the kernel,
1715 * AT_PHDR will point to some location other than the dynamic
1716 * linker's program headers. */
1717 if (aux[AT_PHDR] != (size_t)ldso.phdr) {
1718 size_t interp_off = 0;
1719 size_t tls_image = 0;
1720 /* Find load address of the main program, via AT_PHDR vs PT_PHDR. */
1721 Phdr *phdr = app.phdr = (void *)aux[AT_PHDR];
1722 app.phnum = aux[AT_PHNUM];
1723 app.phentsize = aux[AT_PHENT];
1724 for (i=aux[AT_PHNUM]; i; i--, phdr=(void *)((char *)phdr + aux[AT_PHENT])) {
1725 if (phdr->p_type == PT_PHDR)
1726 app.base = (void *)(aux[AT_PHDR] - phdr->p_vaddr);
1727 else if (phdr->p_type == PT_INTERP)
1728 interp_off = (size_t)phdr->p_vaddr;
1729 else if (phdr->p_type == PT_TLS) {
1730 tls_image = phdr->p_vaddr;
1731 app.tls.len = phdr->p_filesz;
1732 app.tls.size = phdr->p_memsz;
1733 app.tls.align = phdr->p_align;
1736 if (DL_FDPIC) app.loadmap = app_loadmap;
1737 if (app.tls.size) app.tls.image = laddr(&app, tls_image);
1738 if (interp_off) ldso.name = laddr(&app, interp_off);
1739 if ((aux[0] & (1UL<<AT_EXECFN))
1740 && strncmp((char *)aux[AT_EXECFN], "/proc/", 6))
1741 app.name = (char *)aux[AT_EXECFN];
1744 kernel_mapped_dso(&app);
1747 char *ldname = argv[0];
1748 size_t l = strlen(ldname);
1749 if (l >= 3 && !strcmp(ldname+l-3, "ldd")) ldd_mode = 1;
1751 while (argv[0] && argv[0][0]=='-' && argv[0][1]=='-') {
1752 char *opt = argv[0]+2;
1753 *argv++ = (void *)-1;
1756 } else if (!memcmp(opt, "list", 5)) {
1758 } else if (!memcmp(opt, "library-path", 12)) {
1759 if (opt[12]=='=') env_path = opt+13;
1760 else if (opt[12]) *argv = 0;
1761 else if (*argv) env_path = *argv++;
1762 } else if (!memcmp(opt, "preload", 7)) {
1763 if (opt[7]=='=') env_preload = opt+8;
1764 else if (opt[7]) *argv = 0;
1765 else if (*argv) env_preload = *argv++;
1766 } else if (!memcmp(opt, "argv0", 5)) {
1767 if (opt[5]=='=') replace_argv0 = opt+6;
1768 else if (opt[5]) *argv = 0;
1769 else if (*argv) replace_argv0 = *argv++;
1774 argv[-1] = (void *)(argc - (argv-argv_orig));
1776 dprintf(2, "musl libc (" LDSO_ARCH ")\n"
1778 "Dynamic Program Loader\n"
1779 "Usage: %s [options] [--] pathname%s\n",
1780 __libc_version, ldname,
1781 ldd_mode ? "" : " [args]");
1784 fd = open(argv[0], O_RDONLY);
1786 dprintf(2, "%s: cannot load %s: %s\n", ldname, argv[0], strerror(errno));
1789 Ehdr *ehdr = (void *)map_library(fd, &app);
1791 dprintf(2, "%s: %s: Not a valid dynamic program\n", ldname, argv[0]);
1797 aux[AT_ENTRY] = (size_t)laddr(&app, ehdr->e_entry);
1798 /* Find the name that would have been used for the dynamic
1799 * linker had ldd not taken its place. */
1801 for (i=0; i<app.phnum; i++) {
1802 if (app.phdr[i].p_type == PT_INTERP)
1803 ldso.name = laddr(&app, app.phdr[i].p_vaddr);
1805 dprintf(1, "\t%s (%p)\n", ldso.name, ldso.base);
1809 libc.tls_head = tls_tail = &app.tls;
1810 app.tls_id = tls_cnt = 1;
1812 app.tls.offset = GAP_ABOVE_TP;
1813 app.tls.offset += (-GAP_ABOVE_TP + (uintptr_t)app.tls.image)
1814 & (app.tls.align-1);
1815 tls_offset = app.tls.offset + app.tls.size;
1817 tls_offset = app.tls.offset = app.tls.size
1818 + ( -((uintptr_t)app.tls.image + app.tls.size)
1819 & (app.tls.align-1) );
1821 tls_align = MAXP2(tls_align, app.tls.align);
1825 makefuncdescs(&app);
1827 app.loadmap = (void *)&app_dummy_loadmap;
1828 app.loadmap->nsegs = 1;
1829 app.loadmap->segs[0].addr = (size_t)app.map;
1830 app.loadmap->segs[0].p_vaddr = (size_t)app.map
1832 app.loadmap->segs[0].p_memsz = app.map_len;
1834 argv[-3] = (void *)app.loadmap;
1837 /* Initial dso chain consists only of the app. */
1838 head = tail = syms_tail = &app;
1840 /* Donate unused parts of app and library mapping to malloc */
1842 reclaim_gaps(&ldso);
1844 /* Load preload/needed libraries, add symbols to global namespace. */
1845 ldso.deps = (struct dso **)no_deps;
1846 if (env_preload) load_preload(env_preload);
1848 for (struct dso *p=head; p; p=p->next)
1851 /* Attach to vdso, if provided by the kernel, last so that it does
1852 * not become part of the global namespace. */
1853 if (search_vec(auxv, &vdso_base, AT_SYSINFO_EHDR) && vdso_base) {
1854 Ehdr *ehdr = (void *)vdso_base;
1855 Phdr *phdr = vdso.phdr = (void *)(vdso_base + ehdr->e_phoff);
1856 vdso.phnum = ehdr->e_phnum;
1857 vdso.phentsize = ehdr->e_phentsize;
1858 for (i=ehdr->e_phnum; i; i--, phdr=(void *)((char *)phdr + ehdr->e_phentsize)) {
1859 if (phdr->p_type == PT_DYNAMIC)
1860 vdso.dynv = (void *)(vdso_base + phdr->p_offset);
1861 if (phdr->p_type == PT_LOAD)
1862 vdso.base = (void *)(vdso_base - phdr->p_vaddr + phdr->p_offset);
1865 vdso.shortname = "linux-gate.so.1";
1867 vdso.deps = (struct dso **)no_deps;
1874 for (i=0; app.dynv[i]; i+=2) {
1875 if (!DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG)
1876 app.dynv[i+1] = (size_t)&debug;
1877 if (DT_DEBUG_INDIRECT && app.dynv[i]==DT_DEBUG_INDIRECT) {
1878 size_t *ptr = (size_t *) app.dynv[i+1];
1879 *ptr = (size_t)&debug;
1883 /* This must be done before final relocations, since it calls
1884 * malloc, which may be provided by the application. Calling any
1885 * application code prior to the jump to its entry point is not
1886 * valid in our model and does not work with FDPIC, where there
1887 * are additional relocation-like fixups that only the entry point
1888 * code can see to perform. */
1889 main_ctor_queue = queue_ctors(&app);
1891 /* Initial TLS must also be allocated before final relocations
1892 * might result in calloc being a call to application code. */
1894 void *initial_tls = builtin_tls;
1895 if (libc.tls_size > sizeof builtin_tls || tls_align > MIN_TLS_ALIGN) {
1896 initial_tls = calloc(libc.tls_size, 1);
1898 dprintf(2, "%s: Error getting %zu bytes thread-local storage: %m\n",
1899 argv[0], libc.tls_size);
1903 static_tls_cnt = tls_cnt;
1905 /* The main program must be relocated LAST since it may contain
1906 * copy relocations which depend on libraries' relocations. */
1907 reloc_all(app.next);
1910 /* Actual copying to new TLS needs to happen after relocations,
1911 * since the TLS images might have contained relocated addresses. */
1912 if (initial_tls != builtin_tls) {
1913 if (__init_tp(__copy_tls(initial_tls)) < 0) {
1917 size_t tmp_tls_size = libc.tls_size;
1918 pthread_t self = __pthread_self();
1919 /* Temporarily set the tls size to the full size of
1920 * builtin_tls so that __copy_tls will use the same layout
1921 * as it did for before. Then check, just to be safe. */
1922 libc.tls_size = sizeof builtin_tls;
1923 if (__copy_tls((void*)builtin_tls) != self) a_crash();
1924 libc.tls_size = tmp_tls_size;
1927 if (ldso_fail) _exit(127);
1928 if (ldd_mode) _exit(0);
1930 /* Determine if malloc was interposed by a replacement implementation
1931 * so that calloc and the memalign family can harden against the
1932 * possibility of incomplete replacement. */
1933 if (find_sym(head, "malloc", 1).dso != &ldso)
1934 __malloc_replaced = 1;
1936 /* Switch to runtime mode: any further failures in the dynamic
1937 * linker are a reportable failure rather than a fatal startup
1942 debug.bp = dl_debug_state;
1944 debug.base = ldso.base;
1948 if (replace_argv0) argv[0] = replace_argv0;
1952 CRTJMP((void *)aux[AT_ENTRY], argv-1);
1956 static void prepare_lazy(struct dso *p)
1958 size_t dyn[DYN_CNT], n, flags1=0;
1959 decode_vec(p->dynv, dyn, DYN_CNT);
1960 search_vec(p->dynv, &flags1, DT_FLAGS_1);
1961 if (dyn[DT_BIND_NOW] || (dyn[DT_FLAGS] & DF_BIND_NOW) || (flags1 & DF_1_NOW))
1963 n = dyn[DT_RELSZ]/2 + dyn[DT_RELASZ]/3 + dyn[DT_PLTRELSZ]/2 + 1;
1964 if (NEED_MIPS_GOT_RELOCS) {
1965 size_t j=0; search_vec(p->dynv, &j, DT_MIPS_GOTSYM);
1966 size_t i=0; search_vec(p->dynv, &i, DT_MIPS_SYMTABNO);
1969 p->lazy = calloc(n, 3*sizeof(size_t));
1971 error("Error preparing lazy relocation for %s: %m", p->name);
1972 longjmp(*rtld_fail, 1);
1974 p->lazy_next = lazy_head;
1978 void *dlopen(const char *file, int mode)
1980 struct dso *volatile p, *orig_tail, *orig_syms_tail, *orig_lazy_head, *next;
1981 struct tls_module *orig_tls_tail;
1982 size_t orig_tls_cnt, orig_tls_offset, orig_tls_align;
1986 struct dso **volatile ctor_queue = 0;
1988 if (!file) return head;
1990 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
1991 pthread_rwlock_wrlock(&lock);
1995 if (shutting_down) {
1996 error("Cannot dlopen while program is exiting.");
1999 orig_tls_tail = tls_tail;
2000 orig_tls_cnt = tls_cnt;
2001 orig_tls_offset = tls_offset;
2002 orig_tls_align = tls_align;
2003 orig_lazy_head = lazy_head;
2004 orig_syms_tail = syms_tail;
2006 noload = mode & RTLD_NOLOAD;
2009 if (setjmp(*rtld_fail)) {
2010 /* Clean up anything new that was (partially) loaded */
2011 revert_syms(orig_syms_tail);
2012 for (p=orig_tail->next; p; p=next) {
2014 while (p->td_index) {
2015 void *tmp = p->td_index->next;
2020 if (p->rpath != p->rpath_orig)
2028 if (!orig_tls_tail) libc.tls_head = 0;
2029 tls_tail = orig_tls_tail;
2030 if (tls_tail) tls_tail->next = 0;
2031 tls_cnt = orig_tls_cnt;
2032 tls_offset = orig_tls_offset;
2033 tls_align = orig_tls_align;
2034 lazy_head = orig_lazy_head;
2039 } else p = load_library(file, head);
2043 "Library %s is not already loaded" :
2044 "Error loading shared library %s: %m",
2049 /* First load handling */
2052 pthread_mutex_lock(&init_fini_lock);
2053 if (!p->constructed) ctor_queue = queue_ctors(p);
2054 pthread_mutex_unlock(&init_fini_lock);
2055 if (!p->relocated && (mode & RTLD_LAZY)) {
2057 for (i=0; p->deps[i]; i++)
2058 if (!p->deps[i]->relocated)
2059 prepare_lazy(p->deps[i]);
2061 if (!p->relocated || (mode & RTLD_GLOBAL)) {
2062 /* Make new symbols global, at least temporarily, so we can do
2063 * relocations. If not RTLD_GLOBAL, this is reverted below. */
2065 for (i=0; p->deps[i]; i++)
2066 add_syms(p->deps[i]);
2068 if (!p->relocated) {
2072 /* If RTLD_GLOBAL was not specified, undo any new additions
2073 * to the global symbol table. This is a nop if the library was
2074 * previously loaded and already global. */
2075 if (!(mode & RTLD_GLOBAL))
2076 revert_syms(orig_syms_tail);
2078 /* Processing of deferred lazy relocations must not happen until
2079 * the new libraries are committed; otherwise we could end up with
2080 * relocations resolved to symbol definitions that get removed. */
2084 if (tls_cnt != orig_tls_cnt)
2091 pthread_rwlock_unlock(&lock);
2093 do_init_fini(ctor_queue);
2096 pthread_setcancelstate(cs, 0);
2100 hidden int __dl_invalid_handle(void *h)
2103 for (p=head; p; p=p->next) if (h==p) return 0;
2104 error("Invalid library handle %p", (void *)h);
2108 static void *addr2dso(size_t a)
2112 if (DL_FDPIC) for (p=head; p; p=p->next) {
2114 if (a-(size_t)p->funcdescs < i*sizeof(*p->funcdescs))
2117 for (p=head; p; p=p->next) {
2118 if (DL_FDPIC && p->loadmap) {
2119 for (i=0; i<p->loadmap->nsegs; i++) {
2120 if (a-p->loadmap->segs[i].p_vaddr
2121 < p->loadmap->segs[i].p_memsz)
2126 size_t phcnt = p->phnum;
2127 size_t entsz = p->phentsize;
2128 size_t base = (size_t)p->base;
2129 for (; phcnt--; ph=(void *)((char *)ph+entsz)) {
2130 if (ph->p_type != PT_LOAD) continue;
2131 if (a-base-ph->p_vaddr < ph->p_memsz)
2134 if (a-(size_t)p->map < p->map_len)
2141 static void *do_dlsym(struct dso *p, const char *s, void *ra)
2144 if (p == head || p == RTLD_DEFAULT) {
2146 } else if (p == RTLD_NEXT) {
2147 p = addr2dso((size_t)ra);
2150 } else if (__dl_invalid_handle(p)) {
2154 struct symdef def = find_sym2(p, s, 0, use_deps);
2156 error("Symbol not found: %s", s);
2159 if ((def.sym->st_info&0xf) == STT_TLS)
2160 return __tls_get_addr((tls_mod_off_t []){def.dso->tls_id, def.sym->st_value-DTP_OFFSET});
2161 if (DL_FDPIC && (def.sym->st_info&0xf) == STT_FUNC)
2162 return def.dso->funcdescs + (def.sym - def.dso->syms);
2163 return laddr(def.dso, def.sym->st_value);
2166 int dladdr(const void *addr_arg, Dl_info *info)
2168 size_t addr = (size_t)addr_arg;
2174 size_t besterr = -1;
2176 pthread_rwlock_rdlock(&lock);
2178 pthread_rwlock_unlock(&lock);
2183 strings = p->strings;
2184 nsym = count_syms(p);
2187 size_t idx = (addr-(size_t)p->funcdescs)
2188 / sizeof(*p->funcdescs);
2189 if (idx < nsym && (sym[idx].st_info&0xf) == STT_FUNC) {
2190 best = (size_t)(p->funcdescs + idx);
2191 bestsym = sym + idx;
2196 if (!best) for (; nsym; nsym--, sym++) {
2198 && (1<<(sym->st_info&0xf) & OK_TYPES)
2199 && (1<<(sym->st_info>>4) & OK_BINDS)) {
2200 size_t symaddr = (size_t)laddr(p, sym->st_value);
2201 if (symaddr > addr || symaddr <= best)
2205 besterr = addr - symaddr;
2206 if (addr == symaddr)
2211 if (best && besterr > bestsym->st_size-1) {
2216 info->dli_fname = p->name;
2217 info->dli_fbase = p->map;
2220 info->dli_sname = 0;
2221 info->dli_saddr = 0;
2225 if (DL_FDPIC && (bestsym->st_info&0xf) == STT_FUNC)
2226 best = (size_t)(p->funcdescs + (bestsym - p->syms));
2227 info->dli_sname = strings + bestsym->st_name;
2228 info->dli_saddr = (void *)best;
2233 hidden void *__dlsym(void *restrict p, const char *restrict s, void *restrict ra)
2236 pthread_rwlock_rdlock(&lock);
2237 res = do_dlsym(p, s, ra);
2238 pthread_rwlock_unlock(&lock);
2242 hidden void *__dlsym_redir_time64(void *restrict p, const char *restrict s, void *restrict ra)
2245 const char *suffix, *suffix2 = "";
2248 /* Map the symbol name to a time64 version of itself according to the
2249 * pattern used for naming the redirected time64 symbols. */
2250 size_t l = strnlen(s, sizeof redir);
2251 if (l<4 || l==sizeof redir) goto no_redir;
2252 if (s[l-2]=='_' && s[l-1]=='r') {
2256 if (l<4) goto no_redir;
2257 if (!strcmp(s+l-4, "time")) suffix = "64";
2258 else suffix = "_time64";
2260 /* Use the presence of the remapped symbol name in libc to determine
2261 * whether it's one that requires time64 redirection; replace if so. */
2262 snprintf(redir, sizeof redir, "__%.*s%s%s", (int)l, s, suffix, suffix2);
2263 if (find_sym(&ldso, redir, 1).sym) s = redir;
2266 return __dlsym(p, s, ra);
2269 int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void *data), void *data)
2271 struct dso *current;
2272 struct dl_phdr_info info;
2274 for(current = head; current;) {
2275 info.dlpi_addr = (uintptr_t)current->base;
2276 info.dlpi_name = current->name;
2277 info.dlpi_phdr = current->phdr;
2278 info.dlpi_phnum = current->phnum;
2279 info.dlpi_adds = gencnt;
2281 info.dlpi_tls_modid = current->tls_id;
2282 info.dlpi_tls_data = current->tls.image;
2284 ret = (callback)(&info, sizeof (info), data);
2286 if (ret != 0) break;
2288 pthread_rwlock_rdlock(&lock);
2289 current = current->next;
2290 pthread_rwlock_unlock(&lock);
2295 static void error(const char *fmt, ...)
2300 vdprintf(2, fmt, ap);
2306 __dl_vseterr(fmt, ap);