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,
154 SymCache *cache, RtldLockState *lockstate)
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,
175 false, cache, lockstate);
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,
198 true, cache, lockstate);
201 * XXX r_debug_state is problematic and find_symdef()
202 * returns NULL for it. This probably has something to
203 * do with symbol versioning (r_debug_state is in the
204 * symbol map). If we return -1 in that case we abort
205 * relocating rtld, which typically is fatal. So, for
206 * now just skip the symbol when we're relocating
207 * rtld. We don't care about r_debug_state unless we
208 * are being debugged.
215 if (def->st_shndx != SHN_UNDEF) {
216 target = (Elf_Addr)(defobj->relocbase + def->st_value);
217 gp = (Elf_Addr)defobj->pltgot;
219 /* rtld is allowed to reference itself only */
220 assert(!obj->rtld || obj == defobj);
221 fptrs = defobj->priv;
223 fptrs = alloc_fptrs((Obj_Entry *) defobj,
226 sym_index = def - defobj->symtab;
229 * Find the @fptr, using fptrs as a helper.
232 fptr = fptrs[sym_index];
234 fptr = alloc_fptr(target, gp);
236 fptrs[sym_index] = fptr;
241 store64(where, (Elf_Addr)fptr);
245 case R_IA_64_IPLTLSB: {
247 * Relocation typically used to populate C++ virtual function
248 * tables. It creates a 128-bit function descriptor at the
249 * specified memory address.
252 const Obj_Entry *defobj;
256 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
257 false, cache, lockstate);
261 if (def->st_shndx != SHN_UNDEF) {
262 target = (Elf_Addr)(defobj->relocbase + def->st_value);
263 gp = (Elf_Addr)defobj->pltgot;
270 store64(&fptr->target, target);
271 store64(&fptr->gp, gp);
275 case R_IA_64_DTPMOD64LSB: {
277 const Obj_Entry *defobj;
279 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
280 false, cache, lockstate);
284 store64(where, defobj->tlsindex);
288 case R_IA_64_DTPREL64LSB: {
290 const Obj_Entry *defobj;
292 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
293 false, cache, lockstate);
297 store64(where, def->st_value + rela->r_addend);
301 case R_IA_64_TPREL64LSB: {
303 const Obj_Entry *defobj;
305 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
306 false, cache, lockstate);
311 * We lazily allocate offsets for static TLS as we
312 * see the first relocation that references the
313 * TLS block. This allows us to support (small
314 * amounts of) static TLS in dynamically loaded
315 * modules. If we run out of space, we generate an
318 if (!defobj->tls_done) {
319 if (!allocate_tls_offset((Obj_Entry*) defobj)) {
320 _rtld_error("%s: No space available for static "
321 "Thread Local Storage", obj->path);
326 store64(where, defobj->tlsoffset + def->st_value + rela->r_addend);
334 _rtld_error("%s: Unsupported relocation type %u"
335 " in non-PLT relocations\n", obj->path,
336 (unsigned int)ELF_R_TYPE(rela->r_info));
343 /* Process the non-PLT relocations. */
345 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, RtldLockState *lockstate)
347 const Elf_Rel *rellim;
349 const Elf_Rela *relalim;
350 const Elf_Rela *rela;
352 int bytes = obj->nchains * sizeof(SymCache);
356 * The dynamic loader may be called from a thread, we have
357 * limited amounts of stack available so we cannot use alloca().
359 cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
360 if (cache == MAP_FAILED)
363 /* Perform relocations without addend if there are any: */
364 rellim = (const Elf_Rel *) ((caddr_t) obj->rel + obj->relsize);
365 for (rel = obj->rel; obj->rel != NULL && rel < rellim; rel++) {
368 locrela.r_info = rel->r_info;
369 locrela.r_offset = rel->r_offset;
370 locrela.r_addend = 0;
371 if (reloc_non_plt_obj(obj_rtld, obj, &locrela, cache,
376 /* Perform relocations with addend if there are any: */
377 relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize);
378 for (rela = obj->rela; obj->rela != NULL && rela < relalim; rela++) {
379 if (reloc_non_plt_obj(obj_rtld, obj, rela, cache, lockstate))
386 munmap(cache, bytes);
389 * Release temporarily mapped fptrs if relocating
390 * rtld object itself. A new table will be created
391 * in make_function_pointer using malloc when needed.
393 if (obj->rtld && obj->priv)
394 free_fptrs(obj, true);
399 /* Process the PLT relocations. */
401 reloc_plt(Obj_Entry *obj)
403 /* All PLT relocations are the same kind: Elf_Rel or Elf_Rela. */
404 if (obj->pltrelsize != 0) {
405 const Elf_Rel *rellim;
408 rellim = (const Elf_Rel *)
409 ((char *)obj->pltrel + obj->pltrelsize);
410 for (rel = obj->pltrel; rel < rellim; rel++) {
413 assert(ELF_R_TYPE(rel->r_info) == R_IA_64_IPLTLSB);
415 /* Relocate the @fptr pointing into the PLT. */
416 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
417 *where += (Elf_Addr)obj->relocbase;
420 const Elf_Rela *relalim;
421 const Elf_Rela *rela;
423 relalim = (const Elf_Rela *)
424 ((char *)obj->pltrela + obj->pltrelasize);
425 for (rela = obj->pltrela; rela < relalim; rela++) {
428 assert(ELF_R_TYPE(rela->r_info) == R_IA_64_IPLTLSB);
430 /* Relocate the @fptr pointing into the PLT. */
431 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
432 *where += (Elf_Addr)obj->relocbase;
438 /* Relocate the jump slots in an object. */
440 reloc_jmpslots(Obj_Entry *obj, RtldLockState *lockstate)
442 if (obj->jmpslots_done)
444 /* All PLT relocations are the same kind: Elf_Rel or Elf_Rela. */
445 if (obj->pltrelsize != 0) {
446 const Elf_Rel *rellim;
449 rellim = (const Elf_Rel *)
450 ((char *)obj->pltrel + obj->pltrelsize);
451 for (rel = obj->pltrel; rel < rellim; rel++) {
454 const Obj_Entry *defobj;
456 assert(ELF_R_TYPE(rel->r_info) == R_IA_64_IPLTLSB);
457 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
458 def = find_symdef(ELF_R_SYM(rel->r_info), obj,
459 &defobj, true, NULL, lockstate);
463 (Elf_Addr)(defobj->relocbase
468 const Elf_Rela *relalim;
469 const Elf_Rela *rela;
471 relalim = (const Elf_Rela *)
472 ((char *)obj->pltrela + obj->pltrelasize);
473 for (rela = obj->pltrela; rela < relalim; rela++) {
476 const Obj_Entry *defobj;
478 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
479 def = find_symdef(ELF_R_SYM(rela->r_info), obj,
480 &defobj, true, NULL, lockstate);
484 (Elf_Addr)(defobj->relocbase
486 defobj, obj, (Elf_Rel *)rela);
489 obj->jmpslots_done = true;
493 /* Fixup the jump slot at "where" to transfer control to "target". */
495 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, const Obj_Entry *obj,
496 const Obj_Entry *refobj, const Elf_Rel *rel)
500 dbg(" reloc_jmpslot: where=%p, target=%p, gp=%p",
501 (void *)where, (void *)target, (void *)obj->pltgot);
503 if (stubaddr != target) {
506 * Point this @fptr directly at the target. Update the
507 * gp value first so that we don't break another cpu
508 * which is currently executing the PLT entry.
510 where[1] = (Elf_Addr) obj->pltgot;
517 * The caller needs an @fptr for the adjusted entry. The PLT
518 * entry serves this purpose nicely.
520 return (Elf_Addr) where;
524 * XXX ia64 doesn't seem to have copy relocations.
526 * Returns 0 on success, -1 on failure.
529 do_copy_relocations(Obj_Entry *dstobj)
536 * Return the @fptr representing a given function symbol.
539 make_function_pointer(const Elf_Sym *sym, const Obj_Entry *obj)
541 struct fptr **fptrs = obj->priv;
542 int index = sym - obj->symtab;
546 * This should only happen for something like
547 * dlsym("dlopen"). Actually, I'm not sure it can ever
550 fptrs = alloc_fptrs((Obj_Entry *) obj, false);
554 target = (Elf_Addr) (obj->relocbase + sym->st_value);
555 gp = (Elf_Addr) obj->pltgot;
556 fptrs[index] = alloc_fptr(target, gp);
562 call_initfini_pointer(const Obj_Entry *obj, Elf_Addr target)
566 fptr.gp = (Elf_Addr) obj->pltgot;
567 fptr.target = target;
568 dbg(" initfini: target=%p, gp=%p",
569 (void *) fptr.target, (void *) fptr.gp);
570 ((InitFunc) &fptr)();
573 /* Initialize the special PLT entries. */
575 init_pltgot(Obj_Entry *obj)
578 Elf_Addr *pltres = 0;
581 * When there are no PLT relocations, the DT_IA_64_PLT_RESERVE entry
582 * is bogus. Do not setup the BOR pointers in that case. An example
583 * of where this happens is /usr/lib/libxpg4.so.3.
585 if (obj->pltrelasize == 0 && obj->pltrelsize == 0)
589 * Find the PLT RESERVE section.
591 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
592 if (dynp->d_tag == DT_IA_64_PLT_RESERVE)
593 pltres = (u_int64_t *)
594 (obj->relocbase + dynp->d_un.d_ptr);
597 errx(1, "Can't find DT_IA_64_PLT_RESERVE entry");
600 * The PLT RESERVE section is used to get values to pass to
601 * _rtld_bind when lazy binding.
603 pltres[0] = (Elf_Addr) obj;
604 pltres[1] = FPTR_TARGET(_rtld_bind_start);
605 pltres[2] = FPTR_GP(_rtld_bind_start);
609 allocate_initial_tls(Obj_Entry *list)
614 * Fix the size of the static TLS block by using the maximum
615 * offset allocated so far and adding a bit for dynamic modules to
618 tls_static_space = tls_last_offset + tls_last_size + RTLD_STATIC_TLS_EXTRA;
620 tpval = allocate_tls(list, NULL, TLS_TCB_SIZE, 16);
621 __asm __volatile("mov r13 = %0" :: "r"(tpval));
624 void *__tls_get_addr(unsigned long module, unsigned long offset)
626 register Elf_Addr** tp __asm__("r13");
628 return tls_get_addr_common(tp, module, offset);