2 * Copyright 1996, 1997, 1998, 1999 John D. Polstra.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 * Dynamic linker for ELF.
31 * John Polstra <jdp@polstra.com>.
34 #include <sys/param.h>
36 #include <machine/ia64_cpu.h>
51 extern Elf_Dyn _DYNAMIC;
54 * Macros for loading/storing unaligned 64-bit values. These are
55 * needed because relocations can point to unaligned data. This
56 * occurs in the DWARF2 exception frame tables generated by the
57 * compiler, for instance.
59 * We don't use these when relocating jump slots and GOT entries,
60 * since they are guaranteed to be aligned.
62 * XXX dfr stub for now.
64 #define load64(p) (*(u_int64_t *) (p))
65 #define store64(p, v) (*(u_int64_t *) (p) = (v))
67 /* Allocate an @fptr. */
69 #define FPTR_CHUNK_SIZE 64
72 struct fptr fptrs[FPTR_CHUNK_SIZE];
75 static struct fptr_chunk first_chunk;
76 static struct fptr_chunk *current_chunk = &first_chunk;
77 static struct fptr *next_fptr = &first_chunk.fptrs[0];
78 static struct fptr *last_fptr = &first_chunk.fptrs[FPTR_CHUNK_SIZE];
81 * We use static storage initially so that we don't have to call
82 * malloc during init_rtld().
85 alloc_fptr(Elf_Addr target, Elf_Addr gp)
89 if (next_fptr == last_fptr) {
90 current_chunk = malloc(sizeof(struct fptr_chunk));
91 next_fptr = ¤t_chunk->fptrs[0];
92 last_fptr = ¤t_chunk->fptrs[FPTR_CHUNK_SIZE];
96 fptr->target = target;
101 static struct fptr **
102 alloc_fptrs(Obj_Entry *obj, bool mapped)
107 fbytes = obj->nchains * sizeof(struct fptr *);
110 * Avoid malloc, if requested. Happens when relocating
111 * rtld itself on startup.
114 fptrs = mmap(NULL, fbytes, PROT_READ|PROT_WRITE,
116 if (fptrs == MAP_FAILED)
119 fptrs = malloc(fbytes);
121 memset(fptrs, 0, fbytes);
125 * This assertion is necessary to guarantee function pointer
128 assert(fptrs != NULL);
130 return (obj->priv = fptrs);
134 free_fptrs(Obj_Entry *obj, bool mapped)
143 fbytes = obj->nchains * sizeof(struct fptr *);
145 munmap(fptrs, fbytes);
151 /* Relocate a non-PLT object with addend. */
153 reloc_non_plt_obj(Obj_Entry *obj_rtld, Obj_Entry *obj, const Elf_Rela *rela,
157 Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset);
159 switch (ELF_R_TYPE(rela->r_info)) {
160 case R_IA_64_REL64LSB:
162 * We handle rtld's relocations in rtld_start.S
166 load64(where) + (Elf_Addr) obj->relocbase);
169 case R_IA_64_DIR64LSB: {
171 const Obj_Entry *defobj;
174 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
179 target = (def->st_shndx != SHN_UNDEF)
180 ? (Elf_Addr)(defobj->relocbase + def->st_value) : 0;
181 store64(where, target + rela->r_addend);
185 case R_IA_64_FPTR64LSB: {
187 * We have to make sure that all @fptr references to
188 * the same function are identical so that code can
189 * compare function pointers.
192 const Obj_Entry *defobj;
193 struct fptr *fptr = 0;
197 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
202 if (def->st_shndx != SHN_UNDEF) {
203 target = (Elf_Addr)(defobj->relocbase + def->st_value);
204 gp = (Elf_Addr)defobj->pltgot;
206 /* rtld is allowed to reference itself only */
207 assert(!obj->rtld || obj == defobj);
208 fptrs = defobj->priv;
210 fptrs = alloc_fptrs((Obj_Entry *) defobj,
213 sym_index = def - defobj->symtab;
216 * Find the @fptr, using fptrs as a helper.
219 fptr = fptrs[sym_index];
221 fptr = alloc_fptr(target, gp);
223 fptrs[sym_index] = fptr;
228 store64(where, (Elf_Addr)fptr);
232 case R_IA_64_IPLTLSB: {
234 * Relocation typically used to populate C++ virtual function
235 * tables. It creates a 128-bit function descriptor at the
236 * specified memory address.
239 const Obj_Entry *defobj;
243 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
248 if (def->st_shndx != SHN_UNDEF) {
249 target = (Elf_Addr)(defobj->relocbase + def->st_value);
250 gp = (Elf_Addr)defobj->pltgot;
257 store64(&fptr->target, target);
258 store64(&fptr->gp, gp);
262 case R_IA_64_DTPMOD64LSB: {
264 const Obj_Entry *defobj;
266 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
271 store64(where, defobj->tlsindex);
275 case R_IA_64_DTPREL64LSB: {
277 const Obj_Entry *defobj;
279 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
284 store64(where, def->st_value + rela->r_addend);
288 case R_IA_64_TPREL64LSB: {
290 const Obj_Entry *defobj;
292 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
298 * We lazily allocate offsets for static TLS as we
299 * see the first relocation that references the
300 * TLS block. This allows us to support (small
301 * amounts of) static TLS in dynamically loaded
302 * modules. If we run out of space, we generate an
305 if (!defobj->tls_done) {
306 if (!allocate_tls_offset((Obj_Entry*) defobj)) {
307 _rtld_error("%s: No space available for static "
308 "Thread Local Storage", obj->path);
313 store64(where, defobj->tlsoffset + def->st_value + rela->r_addend);
321 _rtld_error("%s: Unsupported relocation type %u"
322 " in non-PLT relocations\n", obj->path,
323 (unsigned int)ELF_R_TYPE(rela->r_info));
330 /* Process the non-PLT relocations. */
332 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
334 const Elf_Rel *rellim;
336 const Elf_Rela *relalim;
337 const Elf_Rela *rela;
339 int bytes = obj->nchains * sizeof(SymCache);
343 * The dynamic loader may be called from a thread, we have
344 * limited amounts of stack available so we cannot use alloca().
346 cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
347 if (cache == MAP_FAILED)
350 /* Perform relocations without addend if there are any: */
351 rellim = (const Elf_Rel *) ((caddr_t) obj->rel + obj->relsize);
352 for (rel = obj->rel; obj->rel != NULL && rel < rellim; rel++) {
355 locrela.r_info = rel->r_info;
356 locrela.r_offset = rel->r_offset;
357 locrela.r_addend = 0;
358 if (reloc_non_plt_obj(obj_rtld, obj, &locrela, cache))
362 /* Perform relocations with addend if there are any: */
363 relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize);
364 for (rela = obj->rela; obj->rela != NULL && rela < relalim; rela++) {
365 if (reloc_non_plt_obj(obj_rtld, obj, rela, cache))
372 munmap(cache, bytes);
375 * Release temporarily mapped fptrs if relocating
376 * rtld object itself. A new table will be created
377 * in make_function_pointer using malloc when needed.
379 if (obj->rtld && obj->priv)
380 free_fptrs(obj, true);
385 /* Process the PLT relocations. */
387 reloc_plt(Obj_Entry *obj)
389 /* All PLT relocations are the same kind: Elf_Rel or Elf_Rela. */
390 if (obj->pltrelsize != 0) {
391 const Elf_Rel *rellim;
394 rellim = (const Elf_Rel *)
395 ((char *)obj->pltrel + obj->pltrelsize);
396 for (rel = obj->pltrel; rel < rellim; rel++) {
399 assert(ELF_R_TYPE(rel->r_info) == R_IA_64_IPLTLSB);
401 /* Relocate the @fptr pointing into the PLT. */
402 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
403 *where += (Elf_Addr)obj->relocbase;
406 const Elf_Rela *relalim;
407 const Elf_Rela *rela;
409 relalim = (const Elf_Rela *)
410 ((char *)obj->pltrela + obj->pltrelasize);
411 for (rela = obj->pltrela; rela < relalim; rela++) {
414 assert(ELF_R_TYPE(rela->r_info) == R_IA_64_IPLTLSB);
416 /* Relocate the @fptr pointing into the PLT. */
417 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
418 *where += (Elf_Addr)obj->relocbase;
424 /* Relocate the jump slots in an object. */
426 reloc_jmpslots(Obj_Entry *obj)
428 if (obj->jmpslots_done)
430 /* All PLT relocations are the same kind: Elf_Rel or Elf_Rela. */
431 if (obj->pltrelsize != 0) {
432 const Elf_Rel *rellim;
435 rellim = (const Elf_Rel *)
436 ((char *)obj->pltrel + obj->pltrelsize);
437 for (rel = obj->pltrel; rel < rellim; rel++) {
440 const Obj_Entry *defobj;
442 assert(ELF_R_TYPE(rel->r_info) == R_IA_64_IPLTLSB);
443 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
444 def = find_symdef(ELF_R_SYM(rel->r_info), obj,
445 &defobj, true, NULL);
449 (Elf_Addr)(defobj->relocbase
454 const Elf_Rela *relalim;
455 const Elf_Rela *rela;
457 relalim = (const Elf_Rela *)
458 ((char *)obj->pltrela + obj->pltrelasize);
459 for (rela = obj->pltrela; rela < relalim; rela++) {
462 const Obj_Entry *defobj;
464 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
465 def = find_symdef(ELF_R_SYM(rela->r_info), obj,
466 &defobj, true, NULL);
470 (Elf_Addr)(defobj->relocbase
472 defobj, obj, (Elf_Rel *)rela);
475 obj->jmpslots_done = true;
479 /* Fixup the jump slot at "where" to transfer control to "target". */
481 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, const Obj_Entry *obj,
482 const Obj_Entry *refobj, const Elf_Rel *rel)
486 dbg(" reloc_jmpslot: where=%p, target=%p, gp=%p",
487 (void *)where, (void *)target, (void *)obj->pltgot);
489 if (stubaddr != target) {
492 * Point this @fptr directly at the target. Update the
493 * gp value first so that we don't break another cpu
494 * which is currently executing the PLT entry.
496 where[1] = (Elf_Addr) obj->pltgot;
503 * The caller needs an @fptr for the adjusted entry. The PLT
504 * entry serves this purpose nicely.
506 return (Elf_Addr) where;
510 * XXX ia64 doesn't seem to have copy relocations.
512 * Returns 0 on success, -1 on failure.
515 do_copy_relocations(Obj_Entry *dstobj)
522 * Return the @fptr representing a given function symbol.
525 make_function_pointer(const Elf_Sym *sym, const Obj_Entry *obj)
527 struct fptr **fptrs = obj->priv;
528 int index = sym - obj->symtab;
532 * This should only happen for something like
533 * dlsym("dlopen"). Actually, I'm not sure it can ever
536 fptrs = alloc_fptrs((Obj_Entry *) obj, false);
540 target = (Elf_Addr) (obj->relocbase + sym->st_value);
541 gp = (Elf_Addr) obj->pltgot;
542 fptrs[index] = alloc_fptr(target, gp);
548 call_initfini_pointer(const Obj_Entry *obj, Elf_Addr target)
552 fptr.gp = (Elf_Addr) obj->pltgot;
553 fptr.target = target;
554 dbg(" initfini: target=%p, gp=%p",
555 (void *) fptr.target, (void *) fptr.gp);
556 ((InitFunc) &fptr)();
559 /* Initialize the special PLT entries. */
561 init_pltgot(Obj_Entry *obj)
564 Elf_Addr *pltres = 0;
567 * When there are no PLT relocations, the DT_IA_64_PLT_RESERVE entry
568 * is bogus. Do not setup the BOR pointers in that case. An example
569 * of where this happens is /usr/lib/libxpg4.so.3.
571 if (obj->pltrelasize == 0 && obj->pltrelsize == 0)
575 * Find the PLT RESERVE section.
577 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
578 if (dynp->d_tag == DT_IA_64_PLT_RESERVE)
579 pltres = (u_int64_t *)
580 (obj->relocbase + dynp->d_un.d_ptr);
583 errx(1, "Can't find DT_IA_64_PLT_RESERVE entry");
586 * The PLT RESERVE section is used to get values to pass to
587 * _rtld_bind when lazy binding.
589 pltres[0] = (Elf_Addr) obj;
590 pltres[1] = FPTR_TARGET(_rtld_bind_start);
591 pltres[2] = FPTR_GP(_rtld_bind_start);
595 allocate_initial_tls(Obj_Entry *list)
600 * Fix the size of the static TLS block by using the maximum
601 * offset allocated so far and adding a bit for dynamic modules to
604 tls_static_space = tls_last_offset + tls_last_size + RTLD_STATIC_TLS_EXTRA;
606 tpval = allocate_tls(list, NULL, TLS_TCB_SIZE, 16);
607 __asm __volatile("mov r13 = %0" :: "r"(tpval));
610 void *__tls_get_addr(unsigned long module, unsigned long offset)
612 register Elf_Addr** tp __asm__("r13");
614 return tls_get_addr_common(tp, module, offset);