libexec/rtld-elf/x86_64/reloc.c

   1 /*-
   2  * Copyright 1996, 1997, 1998, 1999 John D. Polstra.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   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.
  13  *
  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.
  24  *
  25  * $FreeBSD: src/libexec/rtld-elf/amd64/reloc.c,v 1.18 2006/03/28 06:09:24 davidxu Exp $
  26  */
  27
  28 /*
  29  * Dynamic linker for ELF.
  30  *
  31  * John Polstra <jdp@polstra.com>.
  32  */
  33
  34 #include <sys/param.h>
  35 #include <sys/mman.h>
  36 #include <sys/tls.h>
  37
  38 #include <machine/sysarch.h>
  39 #include <machine/tls.h>
  40
  41 #include <dlfcn.h>
  42 #include <err.h>
  43 #include <errno.h>
  44 #include <fcntl.h>
  45 #include <stdarg.h>
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include <string.h>
  49 #include <unistd.h>
  50
  51 #include "debug.h"
  52 #include "rtld.h"
  53
  54 /*
  55  * Process the special R_X86_64_COPY relocations in the main program.  These
  56  * copy data from a shared object into a region in the main program's BSS
  57  * segment.
  58  *
  59  * Returns 0 on success, -1 on failure.
  60  */
  61 int
  62 do_copy_relocations(Obj_Entry *dstobj)
  63 {
  64     const Elf_Rela *relalim;
  65     const Elf_Rela *rela;
  66
  67     assert(dstobj->mainprog);   /* COPY relocations are invalid elsewhere */
  68
  69     relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela + dstobj->relasize);
  70     for (rela = dstobj->rela;  rela < relalim;  rela++) {
  71         if (ELF_R_TYPE(rela->r_info) == R_X86_64_COPY) {
  72             void *dstaddr;
  73             const Elf_Sym *dstsym;
  74             const char *name;
  75             unsigned long hash;
  76             size_t size;
  77             const void *srcaddr;
  78             const Elf_Sym *srcsym;
  79             Obj_Entry *srcobj;
  80
  81             dstaddr = (void *) (dstobj->relocbase + rela->r_offset);
  82             dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
  83             name = dstobj->strtab + dstsym->st_name;
  84             hash = elf_hash(name);
  85             size = dstsym->st_size;
  86
  87             for (srcobj = dstobj->next;  srcobj != NULL;  srcobj = srcobj->next)
  88                 if ((srcsym = symlook_obj(name, hash, srcobj, false)) != NULL)
  89                     break;
  90
  91             if (srcobj == NULL) {
  92                 _rtld_error("Undefined symbol \"%s\" referenced from COPY"
  93                   " relocation in %s", name, dstobj->path);
  94                 return -1;
  95             }
  96
  97             srcaddr = (const void *) (srcobj->relocbase + srcsym->st_value);
  98             memcpy(dstaddr, srcaddr, size);
  99         }
 100     }
 101
 102     return 0;
 103 }
 104
 105 /* Initialize the special GOT entries. */
 106 void
 107 init_pltgot(Obj_Entry *obj)
 108 {
 109     if (obj->pltgot != NULL) {
 110         obj->pltgot[1] = (Elf_Addr) obj;
 111         obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
 112     }
 113 }
 114
 115 /* Process the non-PLT relocations. */
 116 int
 117 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
 118 {
 119         const Elf_Rela *relalim;
 120         const Elf_Rela *rela;
 121         SymCache *cache;
 122         int bytes = obj->nchains * sizeof(SymCache);
 123         int r = -1;
 124
 125         /*
 126          * The dynamic loader may be called from a thread, we have
 127          * limited amounts of stack available so we cannot use alloca().
 128          */
 129         cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
 130         if (cache == MAP_FAILED)
 131             cache = NULL;
 132
 133         relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize);
 134         for (rela = obj->rela;  rela < relalim;  rela++) {
 135             Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset);
 136             Elf32_Addr *where32 = (Elf32_Addr *)where;
 137
 138             switch (ELF_R_TYPE(rela->r_info)) {
 139
 140             case R_X86_64_NONE:
 141                 break;
 142
 143             case R_X86_64_64:
 144                 {
 145                     const Elf_Sym *def;
 146                     const Obj_Entry *defobj;
 147
 148                     def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
 149                       false, cache);
 150                     if (def == NULL)
 151                         goto done;
 152
 153                     *where = (Elf_Addr) (defobj->relocbase + def->st_value + rela->r_addend);
 154                 }
 155                 break;
 156
 157             case R_X86_64_PC32:
 158                 /*
 159                  * I don't think the dynamic linker should ever see this
 160                  * type of relocation.  But the binutils-2.6 tools sometimes
 161                  * generate it.
 162                  */
 163                 {
 164                     const Elf_Sym *def;
 165                     const Obj_Entry *defobj;
 166
 167                     def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
 168                       false, cache);
 169                     if (def == NULL)
 170                         goto done;
 171
 172                     *where32 = (Elf32_Addr) (unsigned long) (defobj->relocbase +
 173                         def->st_value + rela->r_addend - (Elf_Addr) where);
 174                 }
 175                 break;
 176         /* missing: R_X86_64_GOT32 R_X86_64_PLT32 */
 177
 178             case R_X86_64_COPY:
 179                 /*
 180                  * These are deferred until all other relocations have
 181                  * been done.  All we do here is make sure that the COPY
 182                  * relocation is not in a shared library.  They are allowed
 183                  * only in executable files.
 184                  */
 185                 if (!obj->mainprog) {
 186                     _rtld_error("%s: Unexpected R_X86_64_COPY relocation"
 187                       " in shared library", obj->path);
 188                     goto done;
 189                 }
 190                 break;
 191
 192             case R_X86_64_GLOB_DAT:
 193                 {
 194                     const Elf_Sym *def;
 195                     const Obj_Entry *defobj;
 196
 197                     def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
 198                       false, cache);
 199                     if (def == NULL)
 200                         goto done;
 201
 202                     *where = (Elf_Addr) (defobj->relocbase + def->st_value);
 203                 }
 204                 break;
 205
 206             case R_X86_64_TPOFF64:
 207                 {
 208                     const Elf_Sym *def;
 209                     const Obj_Entry *defobj;
 210
 211                     def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
 212                       false, cache);
 213                     if (def == NULL)
 214                         goto done;
 215
 216                     /*
 217                      * We lazily allocate offsets for static TLS as we
 218                      * see the first relocation that references the
 219                      * TLS block. This allows us to support (small
 220                      * amounts of) static TLS in dynamically loaded
 221                      * modules. If we run out of space, we generate an
 222                      * error.
 223                      */
 224                     if (!defobj->tls_done) {
 225                         if (!allocate_tls_offset((Obj_Entry*) defobj)) {
 226                             _rtld_error("%s: No space available for static "
 227                                         "Thread Local Storage", obj->path);
 228                             goto done;
 229                         }
 230                     }
 231
 232                     *where = (Elf_Addr) (def->st_value - defobj->tlsoffset +
 233                                          rela->r_addend);
 234                 }
 235                 break;
 236
 237             case R_X86_64_TPOFF32:
 238                 {
 239                     const Elf_Sym *def;
 240                     const Obj_Entry *defobj;
 241
 242                     def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
 243                       false, cache);
 244                     if (def == NULL)
 245                         goto done;
 246
 247                     /*
 248                      * We lazily allocate offsets for static TLS as we
 249                      * see the first relocation that references the
 250                      * TLS block. This allows us to support (small
 251                      * amounts of) static TLS in dynamically loaded
 252                      * modules. If we run out of space, we generate an
 253                      * error.
 254                      */
 255                     if (!defobj->tls_done) {
 256                         if (!allocate_tls_offset((Obj_Entry*) defobj)) {
 257                             _rtld_error("%s: No space available for static "
 258                                         "Thread Local Storage", obj->path);
 259                             goto done;
 260                         }
 261                     }
 262
 263                     *where32 = (Elf32_Addr) (def->st_value -
 264                                              defobj->tlsoffset +
 265                                              rela->r_addend);
 266                 }
 267                 break;
 268
 269             case R_X86_64_DTPMOD64:
 270                 {
 271                     const Elf_Sym *def;
 272                     const Obj_Entry *defobj;
 273
 274                     def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
 275                       false, cache);
 276                     if (def == NULL)
 277                         goto done;
 278
 279                     *where += (Elf_Addr) defobj->tlsindex;
 280                 }
 281                 break;
 282
 283             case R_X86_64_DTPOFF64:
 284                 {
 285                     const Elf_Sym *def;
 286                     const Obj_Entry *defobj;
 287
 288                     def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
 289                       false, cache);
 290                     if (def == NULL)
 291                         goto done;
 292
 293                     *where += (Elf_Addr) (def->st_value + rela->r_addend);
 294                 }
 295                 break;
 296
 297             case R_X86_64_DTPOFF32:
 298                 {
 299                     const Elf_Sym *def;
 300                     const Obj_Entry *defobj;
 301
 302                     def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
 303                       false, cache);
 304                     if (def == NULL)
 305                         goto done;
 306
 307                     *where32 += (Elf32_Addr) (def->st_value + rela->r_addend);
 308                 }
 309                 break;
 310
 311             case R_X86_64_RELATIVE:
 312                 *where = (Elf_Addr)(obj->relocbase + rela->r_addend);
 313                 break;
 314
 315         /* missing: R_X86_64_GOTPCREL, R_X86_64_32, R_X86_64_32S, R_X86_64_16, R_X86_64_PC16, R_X86_64_8, R_X86_64_PC8 */
 316
 317             default:
 318                 _rtld_error("%s: Unsupported relocation type %u"
 319                   " in non-PLT relocations\n", obj->path,
 320                   (unsigned int)ELF_R_TYPE(rela->r_info));
 321                 goto done;
 322             }
 323         }
 324         r = 0;
 325 done:
 326         if (cache)
 327             munmap(cache, bytes);
 328         return(r);
 329 }
 330
 331 /* Process the PLT relocations. */
 332 int
 333 reloc_plt(Obj_Entry *obj)
 334 {
 335     const Elf_Rela *relalim;
 336     const Elf_Rela *rela;
 337
 338     relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
 339     for (rela = obj->pltrela;  rela < relalim;  rela++) {
 340         Elf_Addr *where;
 341
 342         assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT);
 343
 344         /* Relocate the GOT slot pointing into the PLT. */
 345         where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
 346         *where += (Elf_Addr)obj->relocbase;
 347     }
 348     return 0;
 349 }
 350
 351 /* Relocate the jump slots in an object. */
 352 int
 353 reloc_jmpslots(Obj_Entry *obj)
 354 {
 355     const Elf_Rela *relalim;
 356     const Elf_Rela *rela;
 357
 358     if (obj->jmpslots_done)
 359         return 0;
 360     relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
 361     for (rela = obj->pltrela;  rela < relalim;  rela++) {
 362         Elf_Addr *where, target;
 363         const Elf_Sym *def;
 364         const Obj_Entry *defobj;
 365
 366         assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT);
 367         where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
 368         def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true, NULL);
 369         if (def == NULL)
 370             return -1;
 371         target = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend);
 372         reloc_jmpslot(where, target);
 373     }
 374     obj->jmpslots_done = true;
 375     return 0;
 376 }
 377
 378 void *__tls_get_addr(tls_index *ti)
 379 {
 380     struct tls_tcb *tcb;
 381
 382     tcb = tls_get_tcb();
 383     return tls_get_addr_common(&tcb->tcb_dtv, ti->ti_module, ti->ti_offset);
 384 }
 385
 386 void *
 387 __tls_get_addr_tcb(struct tls_tcb *tcb, tls_index *ti)
 388 {
 389     return tls_get_addr_common(&tcb->tcb_dtv, ti->ti_module, ti->ti_offset);
 390 }