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 * $FreeBSD$ 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 <machine/sysarch.h> 37 38 #include <dlfcn.h> 39 #include <err.h> 40 #include <errno.h> 41 #include <fcntl.h> 42 #include <stdarg.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <unistd.h> 47 48 #include "debug.h" 49 #include "rtld.h" 50 51 /* 52 * Process the special R_X86_64_COPY relocations in the main program. These 53 * copy data from a shared object into a region in the main program's BSS 54 * segment. 55 * 56 * Returns 0 on success, -1 on failure. 57 */ 58 int 59 do_copy_relocations(Obj_Entry *dstobj) 60 { 61 const Elf_Rela *relalim; 62 const Elf_Rela *rela; 63 64 assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */ 65 66 relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela + dstobj->relasize); 67 for (rela = dstobj->rela; rela < relalim; rela++) { 68 if (ELF_R_TYPE(rela->r_info) == R_X86_64_COPY) { 69 void *dstaddr; 70 const Elf_Sym *dstsym; 71 const char *name; 72 unsigned long hash; 73 size_t size; 74 const void *srcaddr; 75 const Elf_Sym *srcsym; 76 Obj_Entry *srcobj; 77 78 dstaddr = (void *) (dstobj->relocbase + rela->r_offset); 79 dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); 80 name = dstobj->strtab + dstsym->st_name; 81 hash = elf_hash(name); 82 size = dstsym->st_size; 83 84 for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next) 85 if ((srcsym = symlook_obj(name, hash, srcobj, false)) != NULL) 86 break; 87 88 if (srcobj == NULL) { 89 _rtld_error("Undefined symbol \"%s\" referenced from COPY" 90 " relocation in %s", name, dstobj->path); 91 return -1; 92 } 93 94 srcaddr = (const void *) (srcobj->relocbase + srcsym->st_value); 95 memcpy(dstaddr, srcaddr, size); 96 } 97 } 98 99 return 0; 100 } 101 102 /* Initialize the special GOT entries. */ 103 void 104 init_pltgot(Obj_Entry *obj) 105 { 106 if (obj->pltgot != NULL) { 107 obj->pltgot[1] = (Elf_Addr) obj; 108 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; 109 } 110 } 111 112 /* Process the non-PLT relocations. */ 113 int 114 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld) 115 { 116 const Elf_Rela *relalim; 117 const Elf_Rela *rela; 118 SymCache *cache; 119 int bytes = obj->nchains * sizeof(SymCache); 120 int r = -1; 121 122 /* 123 * The dynamic loader may be called from a thread, we have 124 * limited amounts of stack available so we cannot use alloca(). 125 */ 126 cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0); 127 if (cache == MAP_FAILED) 128 cache = NULL; 129 130 relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize); 131 for (rela = obj->rela; rela < relalim; rela++) { 132 Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset); 133 Elf32_Addr *where32 = (Elf32_Addr *)where; 134 135 switch (ELF_R_TYPE(rela->r_info)) { 136 137 case R_X86_64_NONE: 138 break; 139 140 case R_X86_64_64: 141 { 142 const Elf_Sym *def; 143 const Obj_Entry *defobj; 144 145 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 146 false, cache); 147 if (def == NULL) 148 goto done; 149 150 *where = (Elf_Addr) (defobj->relocbase + def->st_value + rela->r_addend); 151 } 152 break; 153 154 case R_X86_64_PC32: 155 /* 156 * I don't think the dynamic linker should ever see this 157 * type of relocation. But the binutils-2.6 tools sometimes 158 * generate it. 159 */ 160 { 161 const Elf_Sym *def; 162 const Obj_Entry *defobj; 163 164 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 165 false, cache); 166 if (def == NULL) 167 goto done; 168 169 *where32 = (Elf32_Addr) (unsigned long) (defobj->relocbase + 170 def->st_value + rela->r_addend - (Elf_Addr) where); 171 } 172 break; 173 /* missing: R_X86_64_GOT32 R_X86_64_PLT32 */ 174 175 case R_X86_64_COPY: 176 /* 177 * These are deferred until all other relocations have 178 * been done. All we do here is make sure that the COPY 179 * relocation is not in a shared library. They are allowed 180 * only in executable files. 181 */ 182 if (!obj->mainprog) { 183 _rtld_error("%s: Unexpected R_X86_64_COPY relocation" 184 " in shared library", obj->path); 185 goto done; 186 } 187 break; 188 189 case R_X86_64_GLOB_DAT: 190 { 191 const Elf_Sym *def; 192 const Obj_Entry *defobj; 193 194 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 195 false, cache); 196 if (def == NULL) 197 goto done; 198 199 *where = (Elf_Addr) (defobj->relocbase + def->st_value); 200 } 201 break; 202 203 case R_X86_64_TPOFF64: 204 { 205 const Elf_Sym *def; 206 const Obj_Entry *defobj; 207 208 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 209 false, cache); 210 if (def == NULL) 211 goto done; 212 213 /* 214 * We lazily allocate offsets for static TLS as we 215 * see the first relocation that references the 216 * TLS block. This allows us to support (small 217 * amounts of) static TLS in dynamically loaded 218 * modules. If we run out of space, we generate an 219 * error. 220 */ 221 if (!defobj->tls_done) { 222 if (!allocate_tls_offset((Obj_Entry*) defobj)) { 223 _rtld_error("%s: No space available for static " 224 "Thread Local Storage", obj->path); 225 goto done; 226 } 227 } 228 229 *where = (Elf_Addr) (def->st_value - defobj->tlsoffset + 230 rela->r_addend); 231 } 232 break; 233 234 case R_X86_64_TPOFF32: 235 { 236 const Elf_Sym *def; 237 const Obj_Entry *defobj; 238 239 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 240 false, cache); 241 if (def == NULL) 242 goto done; 243 244 /* 245 * We lazily allocate offsets for static TLS as we 246 * see the first relocation that references the 247 * TLS block. This allows us to support (small 248 * amounts of) static TLS in dynamically loaded 249 * modules. If we run out of space, we generate an 250 * error. 251 */ 252 if (!defobj->tls_done) { 253 if (!allocate_tls_offset((Obj_Entry*) defobj)) { 254 _rtld_error("%s: No space available for static " 255 "Thread Local Storage", obj->path); 256 goto done; 257 } 258 } 259 260 *where32 = (Elf32_Addr) (def->st_value - 261 defobj->tlsoffset + 262 rela->r_addend); 263 } 264 break; 265 266 case R_X86_64_DTPMOD64: 267 { 268 const Elf_Sym *def; 269 const Obj_Entry *defobj; 270 271 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 272 false, cache); 273 if (def == NULL) 274 goto done; 275 276 *where += (Elf_Addr) defobj->tlsindex; 277 } 278 break; 279 280 case R_X86_64_DTPOFF64: 281 { 282 const Elf_Sym *def; 283 const Obj_Entry *defobj; 284 285 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 286 false, cache); 287 if (def == NULL) 288 goto done; 289 290 *where += (Elf_Addr) (def->st_value + rela->r_addend); 291 } 292 break; 293 294 case R_X86_64_DTPOFF32: 295 { 296 const Elf_Sym *def; 297 const Obj_Entry *defobj; 298 299 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, 300 false, cache); 301 if (def == NULL) 302 goto done; 303 304 *where32 += (Elf32_Addr) (def->st_value + rela->r_addend); 305 } 306 break; 307 308 case R_X86_64_RELATIVE: 309 *where = (Elf_Addr)(obj->relocbase + rela->r_addend); 310 break; 311 312 /* 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 */ 313 314 default: 315 _rtld_error("%s: Unsupported relocation type %d" 316 " in non-PLT relocations\n", obj->path, 317 ELF_R_TYPE(rela->r_info)); 318 goto done; 319 } 320 } 321 r = 0; 322 done: 323 if (cache) 324 munmap(cache, bytes); 325 return(r); 326 } 327 328 /* Process the PLT relocations. */ 329 int 330 reloc_plt(Obj_Entry *obj) 331 { 332 const Elf_Rela *relalim; 333 const Elf_Rela *rela; 334 335 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize); 336 for (rela = obj->pltrela; rela < relalim; rela++) { 337 Elf_Addr *where; 338 339 assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT); 340 341 /* Relocate the GOT slot pointing into the PLT. */ 342 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 343 *where += (Elf_Addr)obj->relocbase; 344 } 345 return 0; 346 } 347 348 /* Relocate the jump slots in an object. */ 349 int 350 reloc_jmpslots(Obj_Entry *obj) 351 { 352 const Elf_Rela *relalim; 353 const Elf_Rela *rela; 354 355 if (obj->jmpslots_done) 356 return 0; 357 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize); 358 for (rela = obj->pltrela; rela < relalim; rela++) { 359 Elf_Addr *where, target; 360 const Elf_Sym *def; 361 const Obj_Entry *defobj; 362 363 assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT); 364 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 365 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true, NULL); 366 if (def == NULL) 367 return -1; 368 target = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend); 369 reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *)rela); 370 } 371 obj->jmpslots_done = true; 372 return 0; 373 } 374 375 void 376 allocate_initial_tls(Obj_Entry *objs) 377 { 378 /* 379 * Fix the size of the static TLS block by using the maximum 380 * offset allocated so far and adding a bit for dynamic modules to 381 * use. 382 */ 383 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA; 384 amd64_set_fsbase(allocate_tls(objs, 0, 385 2*sizeof(Elf_Addr), sizeof(Elf_Addr))); 386 } 387 388 void *__tls_get_addr(tls_index *ti) 389 { 390 Elf_Addr** segbase; 391 Elf_Addr* dtv; 392 393 __asm __volatile("movq %%fs:0, %0" : "=r" (segbase)); 394 dtv = segbase[1]; 395 396 return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset); 397 } 398