libexec/rtld-elf/i386/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/i386/reloc.c,v 1.6.2.2 2002/06/16 20:02:09 dillon Exp $
  26  * $DragonFly: src/libexec/rtld-elf/i386/reloc.c,v 1.13 2005/05/11 21:47:09 dillon Exp $
  27  */
  28
  29 /*
  30  * Dynamic linker for ELF.
  31  *
  32  * John Polstra <jdp@polstra.com>.
  33  */
  34
  35 #include <sys/param.h>
  36 #include <sys/mman.h>
  37 #include <sys/tls.h>
  38
  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_386_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_Rel *rellim;
  65     const Elf_Rel *rel;
  66
  67     assert(dstobj->mainprog);   /* COPY relocations are invalid elsewhere */
  68
  69     rellim = (const Elf_Rel *) ((c_caddr_t) dstobj->rel + dstobj->relsize);
  70     for (rel = dstobj->rel;  rel < rellim;  rel++) {
  71         if (ELF_R_TYPE(rel->r_info) == R_386_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 + rel->r_offset);
  82             dstsym = dstobj->symtab + ELF_R_SYM(rel->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 __unused)
 118 {
 119         const Elf_Rel *rellim;
 120         const Elf_Rel *rel;
 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         rellim = (const Elf_Rel *) ((c_caddr_t) obj->rel + obj->relsize);
 134         for (rel = obj->rel;  rel < rellim;  rel++) {
 135             Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
 136
 137             switch (ELF_R_TYPE(rel->r_info)) {
 138
 139             case R_386_NONE:
 140                 break;
 141
 142             case R_386_32:
 143                 {
 144                     const Elf_Sym *def;
 145                     const Obj_Entry *defobj;
 146
 147                     def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
 148                       false, cache);
 149                     if (def == NULL)
 150                         goto done;
 151
 152                     *where += (Elf_Addr) (defobj->relocbase + def->st_value);
 153                 }
 154                 break;
 155
 156             case R_386_PC32:
 157                 /*
 158                  * I don't think the dynamic linker should ever see this
 159                  * type of relocation.  But the binutils-2.6 tools sometimes
 160                  * generate it.
 161                  */
 162                 {
 163                     const Elf_Sym *def;
 164                     const Obj_Entry *defobj;
 165
 166                     def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
 167                       false, cache);
 168                     if (def == NULL)
 169                         goto done;
 170
 171                     *where +=
 172                       (Elf_Addr) (defobj->relocbase + def->st_value) -
 173                       (Elf_Addr) where;
 174                 }
 175                 break;
 176
 177             case R_386_COPY:
 178                 /*
 179                  * These are deferred until all other relocations have
 180                  * been done.  All we do here is make sure that the COPY
 181                  * relocation is not in a shared library.  They are allowed
 182                  * only in executable files.
 183                  */
 184                 if (!obj->mainprog) {
 185                     _rtld_error("%s: Unexpected R_386_COPY relocation"
 186                       " in shared library", obj->path);
 187                     goto done;
 188                 }
 189                 break;
 190
 191             case R_386_GLOB_DAT:
 192                 {
 193                     const Elf_Sym *def;
 194                     const Obj_Entry *defobj;
 195
 196                     def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
 197                       false, cache);
 198                     if (def == NULL)
 199                         goto done;
 200
 201                     *where = (Elf_Addr) (defobj->relocbase + def->st_value);
 202                 }
 203                 break;
 204
 205             case R_386_RELATIVE:
 206                 *where += (Elf_Addr) obj->relocbase;
 207                 break;
 208
 209             case R_386_TLS_TPOFF:
 210                 {
 211                     const Elf_Sym *def;
 212                     const Obj_Entry *defobj;
 213
 214                     def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
 215                       false, cache);
 216                     if (def == NULL)
 217                         goto done;
 218
 219                     /*
 220                      * We lazily allocate offsets for static TLS as we
 221                      * see the first relocation that references the
 222                      * TLS block. This allows us to support (small
 223                      * amounts of) static TLS in dynamically loaded
 224                      * modules. If we run out of space, we generate an
 225                      * error.
 226                      */
 227                     if (!defobj->tls_done) {
 228                         if (!allocate_tls_offset((Obj_Entry*) defobj)) {
 229                             _rtld_error("%s: No space available for static "
 230                                         "Thread Local Storage", obj->path);
 231                             goto done;
 232                         }
 233                     }
 234
 235                     *where += (Elf_Addr) (def->st_value - defobj->tlsoffset);
 236                 }
 237                 break;
 238
 239             case R_386_TLS_TPOFF32:
 240                 {
 241                     const Elf_Sym *def;
 242                     const Obj_Entry *defobj;
 243
 244                     def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
 245                       false, cache);
 246                     if (def == NULL)
 247                         goto done;
 248
 249                     /*
 250                      * We lazily allocate offsets for static TLS as we
 251                      * see the first relocation that references the
 252                      * TLS block. This allows us to support (small
 253                      * amounts of) static TLS in dynamically loaded
 254                      * modules. If we run out of space, we generate an
 255                      * error.
 256                      */
 257                     if (!defobj->tls_done) {
 258                         if (!allocate_tls_offset((Obj_Entry*) defobj)) {
 259                             _rtld_error("%s: No space available for static "
 260                                         "Thread Local Storage", obj->path);
 261                             goto done;
 262                         }
 263                     }
 264
 265                     *where += (Elf_Addr) (defobj->tlsoffset - def->st_value);
 266                 }
 267                 break;
 268
 269             case R_386_TLS_DTPMOD32:
 270                 {
 271                     const Elf_Sym *def;
 272                     const Obj_Entry *defobj;
 273
 274                     def = find_symdef(ELF_R_SYM(rel->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_386_TLS_DTPOFF32:
 284                 {
 285                     const Elf_Sym *def;
 286                     const Obj_Entry *defobj;
 287
 288                     def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
 289                       false, cache);
 290                     if (def == NULL)
 291                         goto done;
 292
 293                     *where += (Elf_Addr) def->st_value;
 294                 }
 295                 break;
 296
 297             default:
 298                 _rtld_error("%s: Unsupported relocation type %d"
 299                   " in non-PLT relocations\n", obj->path,
 300                   ELF_R_TYPE(rel->r_info));
 301                 goto done;
 302             }
 303         }
 304         r = 0;
 305 done:
 306         if (cache)
 307             munmap(cache, bytes);
 308         return(r);
 309 }
 310
 311 /* Process the PLT relocations. */
 312 int
 313 reloc_plt(Obj_Entry *obj)
 314 {
 315     const Elf_Rel *rellim;
 316     const Elf_Rel *rel;
 317
 318     rellim = (const Elf_Rel *)((const char *)obj->pltrel + obj->pltrelsize);
 319     for (rel = obj->pltrel;  rel < rellim;  rel++) {
 320         Elf_Addr *where;
 321
 322         assert(ELF_R_TYPE(rel->r_info) == R_386_JMP_SLOT);
 323
 324         /* Relocate the GOT slot pointing into the PLT. */
 325         where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
 326         *where += (Elf_Addr)obj->relocbase;
 327     }
 328     return 0;
 329 }
 330
 331 /* Relocate the jump slots in an object. */
 332 int
 333 reloc_jmpslots(Obj_Entry *obj)
 334 {
 335     const Elf_Rel *rellim;
 336     const Elf_Rel *rel;
 337
 338     if (obj->jmpslots_done)
 339         return 0;
 340     rellim = (const Elf_Rel *)((const char *)obj->pltrel + obj->pltrelsize);
 341     for (rel = obj->pltrel;  rel < rellim;  rel++) {
 342         Elf_Addr *where;
 343         const Elf_Sym *def;
 344         const Obj_Entry *defobj;
 345
 346         assert(ELF_R_TYPE(rel->r_info) == R_386_JMP_SLOT);
 347         where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
 348         def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
 349         if (def == NULL)
 350             return -1;
 351         reloc_jmpslot(where, (Elf_Addr)(defobj->relocbase + def->st_value));
 352     }
 353     obj->jmpslots_done = true;
 354     return 0;
 355 }
 356
 357 /* GNU ABI */
 358 __attribute__((__regparm__(1)))
 359 void *
 360 ___tls_get_addr(tls_index *ti)
 361 {
 362     struct tls_tcb *tcb;
 363
 364     tcb = tls_get_tcb();
 365     return tls_get_addr_common(&tcb->tcb_dtv, ti->ti_module, ti->ti_offset);
 366 }
 367
 368 /* Sun ABI */
 369 void *
 370 __tls_get_addr(tls_index *ti)
 371 {
 372     struct tls_tcb *tcb;
 373
 374     tcb = tls_get_tcb();
 375     return tls_get_addr_common(&tcb->tcb_dtv, ti->ti_module, ti->ti_offset);
 376 }
 377
 378 /* Sun ABI */
 379 void *
 380 __tls_get_addr_tcb(struct tls_tcb *tcb, tls_index *ti)
 381 {
 382     return tls_get_addr_common(&tcb->tcb_dtv, ti->ti_module, ti->ti_offset);
 383 }
 384