1 /* $NetBSD: rtld.c,v 1.151 2011/06/25 05:45:12 nonaka Exp $ */ 2 3 /* 4 * Copyright 1996 John D. Polstra. 5 * Copyright 1996 Matt Thomas <matt@3am-software.com> 6 * Copyright 2002 Charles M. Hannum <root@ihack.net> 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by John Polstra. 20 * 4. The name of the author may not be used to endorse or promote products 21 * derived from this software without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35 /* 36 * Dynamic linker for ELF. 37 * 38 * John Polstra <jdp@polstra.com>. 39 */ 40 41 #include <sys/cdefs.h> 42 #ifndef lint 43 __RCSID("$NetBSD: rtld.c,v 1.151 2011/06/25 05:45:12 nonaka Exp $"); 44 #endif /* not lint */ 45 46 #include <sys/param.h> 47 #include <sys/atomic.h> 48 #include <sys/mman.h> 49 #include <err.h> 50 #include <errno.h> 51 #include <fcntl.h> 52 #include <lwp.h> 53 #include <stdarg.h> 54 #include <stdio.h> 55 #include <stdlib.h> 56 #include <string.h> 57 #include <unistd.h> 58 #include <dirent.h> 59 60 #include <ctype.h> 61 62 #include <dlfcn.h> 63 #include "debug.h" 64 #include "rtld.h" 65 66 #if !defined(lint) 67 #include "sysident.h" 68 #endif 69 70 /* 71 * Function declarations. 72 */ 73 static void _rtld_init(caddr_t, caddr_t, const char *); 74 static void _rtld_exit(void); 75 76 Elf_Addr _rtld(Elf_Addr *, Elf_Addr); 77 78 79 /* 80 * Data declarations. 81 */ 82 static char *error_message; /* Message for dlopen(), or NULL */ 83 84 struct r_debug _rtld_debug; /* for GDB; */ 85 bool _rtld_trust; /* False for setuid and setgid programs */ 86 Obj_Entry *_rtld_objlist; /* Head of linked list of shared objects */ 87 Obj_Entry **_rtld_objtail; /* Link field of last object in list */ 88 Obj_Entry *_rtld_objmain; /* The main program shared object */ 89 Obj_Entry _rtld_objself; /* The dynamic linker shared object */ 90 u_int _rtld_objcount; /* Number of objects in _rtld_objlist */ 91 u_int _rtld_objloads; /* Number of objects loaded in _rtld_objlist */ 92 u_int _rtld_objgen; /* Generation count for _rtld_objlist */ 93 const char _rtld_path[] = _PATH_RTLD; 94 95 /* Initialize a fake symbol for resolving undefined weak references. */ 96 Elf_Sym _rtld_sym_zero = { 97 .st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE), 98 .st_shndx = SHN_ABS, 99 }; 100 size_t _rtld_pagesz; /* Page size, as provided by kernel */ 101 102 Search_Path *_rtld_default_paths; 103 Search_Path *_rtld_paths; 104 105 Library_Xform *_rtld_xforms; 106 107 /* 108 * Global declarations normally provided by crt0. 109 */ 110 char *__progname; 111 char **environ; 112 113 static volatile bool _rtld_mutex_may_recurse; 114 115 #if defined(RTLD_DEBUG) 116 #ifndef __sh__ 117 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[]; 118 #else /* 32-bit SuperH */ 119 register Elf_Addr *_GLOBAL_OFFSET_TABLE_ asm("r12"); 120 #endif 121 #endif /* RTLD_DEBUG */ 122 extern Elf_Dyn _DYNAMIC; 123 124 static void _rtld_call_fini_functions(sigset_t *, int); 125 static void _rtld_call_init_functions(sigset_t *); 126 static void _rtld_initlist_visit(Objlist *, Obj_Entry *, int); 127 static void _rtld_initlist_tsort(Objlist *, int); 128 static Obj_Entry *_rtld_dlcheck(void *); 129 static void _rtld_init_dag(Obj_Entry *); 130 static void _rtld_init_dag1(Obj_Entry *, Obj_Entry *); 131 static void _rtld_objlist_remove(Objlist *, Obj_Entry *); 132 static void _rtld_objlist_clear(Objlist *); 133 static void _rtld_unload_object(sigset_t *, Obj_Entry *, bool); 134 static void _rtld_unref_dag(Obj_Entry *); 135 static Obj_Entry *_rtld_obj_from_addr(const void *); 136 137 static void 138 _rtld_call_fini_functions(sigset_t *mask, int force) 139 { 140 Objlist_Entry *elm; 141 Objlist finilist; 142 Obj_Entry *obj; 143 void (*fini)(void); 144 u_int cur_objgen; 145 146 dbg(("_rtld_call_fini_functions(%d)", force)); 147 148 restart: 149 cur_objgen = ++_rtld_objgen; 150 SIMPLEQ_INIT(&finilist); 151 _rtld_initlist_tsort(&finilist, 1); 152 153 /* First pass: objects _not_ marked with DF_1_INITFIRST. */ 154 SIMPLEQ_FOREACH(elm, &finilist, link) { 155 obj = elm->obj; 156 if (obj->refcount > 0 && !force) { 157 continue; 158 } 159 if (obj->fini == NULL || obj->fini_called || obj->z_initfirst) { 160 continue; 161 } 162 dbg (("calling fini function %s at %p", obj->path, 163 (void *)obj->fini)); 164 obj->fini_called = 1; 165 /* 166 * XXX This can race against a concurrent dlclose(). 167 * XXX In that case, the object could be unmapped before 168 * XXX the fini() call is done. 169 */ 170 fini = obj->fini; 171 _rtld_exclusive_exit(mask); 172 (*fini)(); 173 _rtld_exclusive_enter(mask); 174 if (_rtld_objgen != cur_objgen) { 175 dbg(("restarting fini iteration")); 176 _rtld_objlist_clear(&finilist); 177 goto restart; 178 } 179 } 180 181 /* Second pass: objects marked with DF_1_INITFIRST. */ 182 SIMPLEQ_FOREACH(elm, &finilist, link) { 183 obj = elm->obj; 184 if (obj->refcount > 0 && !force) { 185 continue; 186 } 187 if (obj->fini == NULL || obj->fini_called) { 188 continue; 189 } 190 dbg (("calling fini function %s at %p (DF_1_INITFIRST)", 191 obj->path, (void *)obj->fini)); 192 obj->fini_called = 1; 193 /* XXX See above for the race condition here */ 194 fini = obj->fini; 195 _rtld_exclusive_exit(mask); 196 (*fini)(); 197 _rtld_exclusive_enter(mask); 198 if (_rtld_objgen != cur_objgen) { 199 dbg(("restarting fini iteration")); 200 _rtld_objlist_clear(&finilist); 201 goto restart; 202 } 203 } 204 205 _rtld_objlist_clear(&finilist); 206 } 207 208 static void 209 _rtld_call_init_functions(sigset_t *mask) 210 { 211 Objlist_Entry *elm; 212 Objlist initlist; 213 Obj_Entry *obj; 214 void (*init)(void); 215 u_int cur_objgen; 216 217 dbg(("_rtld_call_init_functions()")); 218 219 restart: 220 cur_objgen = ++_rtld_objgen; 221 SIMPLEQ_INIT(&initlist); 222 _rtld_initlist_tsort(&initlist, 0); 223 224 /* First pass: objects marked with DF_1_INITFIRST. */ 225 SIMPLEQ_FOREACH(elm, &initlist, link) { 226 obj = elm->obj; 227 if (obj->init == NULL || obj->init_called || !obj->z_initfirst) { 228 continue; 229 } 230 dbg (("calling init function %s at %p (DF_1_INITFIRST)", 231 obj->path, (void *)obj->init)); 232 obj->init_called = 1; 233 init = obj->init; 234 _rtld_exclusive_exit(mask); 235 (*init)(); 236 _rtld_exclusive_enter(mask); 237 if (_rtld_objgen != cur_objgen) { 238 dbg(("restarting init iteration")); 239 _rtld_objlist_clear(&initlist); 240 goto restart; 241 } 242 } 243 244 /* Second pass: all other objects. */ 245 SIMPLEQ_FOREACH(elm, &initlist, link) { 246 obj = elm->obj; 247 if (obj->init == NULL || obj->init_called) { 248 continue; 249 } 250 dbg (("calling init function %s at %p", obj->path, 251 (void *)obj->init)); 252 obj->init_called = 1; 253 init = obj->init; 254 _rtld_exclusive_exit(mask); 255 (*init)(); 256 _rtld_exclusive_enter(mask); 257 if (_rtld_objgen != cur_objgen) { 258 dbg(("restarting init iteration")); 259 _rtld_objlist_clear(&initlist); 260 goto restart; 261 } 262 } 263 264 _rtld_objlist_clear(&initlist); 265 } 266 267 /* 268 * Initialize the dynamic linker. The argument is the address at which 269 * the dynamic linker has been mapped into memory. The primary task of 270 * this function is to create an Obj_Entry for the dynamic linker and 271 * to resolve the PLT relocation for platforms that need it (those that 272 * define __HAVE_FUNCTION_DESCRIPTORS 273 */ 274 static void 275 _rtld_init(caddr_t mapbase, caddr_t relocbase, const char *execname) 276 { 277 278 /* Conjure up an Obj_Entry structure for the dynamic linker. */ 279 _rtld_objself.path = __UNCONST(_rtld_path); 280 _rtld_objself.pathlen = sizeof(_rtld_path)-1; 281 _rtld_objself.rtld = true; 282 _rtld_objself.mapbase = mapbase; 283 _rtld_objself.relocbase = relocbase; 284 _rtld_objself.dynamic = (Elf_Dyn *) &_DYNAMIC; 285 _rtld_objself.strtab = "_rtld_sym_zero"; 286 287 /* 288 * Set value to -relocbase so that 289 * 290 * _rtld_objself.relocbase + _rtld_sym_zero.st_value == 0 291 * 292 * This allows unresolved references to weak symbols to be computed 293 * to a value of 0. 294 */ 295 _rtld_sym_zero.st_value = -(uintptr_t)relocbase; 296 297 _rtld_digest_dynamic(_rtld_path, &_rtld_objself); 298 assert(!_rtld_objself.needed); 299 #if !defined(__hppa__) 300 assert(!_rtld_objself.pltrel && !_rtld_objself.pltrela); 301 #else 302 _rtld_relocate_plt_objects(&_rtld_objself); 303 #endif 304 #if !defined(__mips__) && !defined(__hppa__) 305 assert(!_rtld_objself.pltgot); 306 #endif 307 #if !defined(__arm__) && !defined(__mips__) && !defined(__sh__) 308 /* ARM, MIPS and SH{3,5} have a bogus DT_TEXTREL. */ 309 assert(!_rtld_objself.textrel); 310 #endif 311 312 _rtld_add_paths(execname, &_rtld_default_paths, 313 RTLD_DEFAULT_LIBRARY_PATH); 314 315 #ifdef RTLD_ARCH_SUBDIR 316 _rtld_add_paths(execname, &_rtld_default_paths, 317 RTLD_DEFAULT_LIBRARY_PATH "/" RTLD_ARCH_SUBDIR); 318 #endif 319 320 /* 321 * Set up the _rtld_objlist pointer, so that rtld symbols can be found. 322 */ 323 _rtld_objlist = &_rtld_objself; 324 325 /* Make the object list empty again. */ 326 _rtld_objlist = NULL; 327 _rtld_objtail = &_rtld_objlist; 328 _rtld_objcount = 0; 329 330 _rtld_debug.r_brk = _rtld_debug_state; 331 _rtld_debug.r_state = RT_CONSISTENT; 332 } 333 334 /* 335 * Cleanup procedure. It will be called (by the atexit() mechanism) just 336 * before the process exits. 337 */ 338 static void 339 _rtld_exit(void) 340 { 341 sigset_t mask; 342 343 dbg(("rtld_exit()")); 344 345 _rtld_exclusive_enter(&mask); 346 347 _rtld_call_fini_functions(&mask, 1); 348 349 _rtld_exclusive_exit(&mask); 350 } 351 352 /* 353 * Main entry point for dynamic linking. The argument is the stack 354 * pointer. The stack is expected to be laid out as described in the 355 * SVR4 ABI specification, Intel 386 Processor Supplement. Specifically, 356 * the stack pointer points to a word containing ARGC. Following that 357 * in the stack is a null-terminated sequence of pointers to argument 358 * strings. Then comes a null-terminated sequence of pointers to 359 * environment strings. Finally, there is a sequence of "auxiliary 360 * vector" entries. 361 * 362 * This function returns the entry point for the main program, the dynamic 363 * linker's exit procedure in sp[0], and a pointer to the main object in 364 * sp[1]. 365 */ 366 Elf_Addr 367 _rtld(Elf_Addr *sp, Elf_Addr relocbase) 368 { 369 const AuxInfo *pAUX_base, *pAUX_entry, *pAUX_execfd, *pAUX_phdr, 370 *pAUX_phent, *pAUX_phnum, *pAUX_euid, *pAUX_egid, 371 *pAUX_ruid, *pAUX_rgid; 372 const AuxInfo *pAUX_pagesz; 373 char **env, **oenvp; 374 const AuxInfo *aux; 375 const AuxInfo *auxp; 376 Obj_Entry *obj; 377 Elf_Addr *const osp = sp; 378 bool bind_now = 0; 379 const char *ld_bind_now, *ld_preload, *ld_library_path; 380 const char **argv; 381 const char *execname; 382 long argc; 383 const char **real___progname; 384 const Obj_Entry **real___mainprog_obj; 385 char ***real_environ; 386 sigset_t mask; 387 #ifdef DEBUG 388 const char *ld_debug; 389 #endif 390 #ifdef RTLD_DEBUG 391 int i = 0; 392 #endif 393 394 /* 395 * On entry, the dynamic linker itself has not been relocated yet. 396 * Be very careful not to reference any global data until after 397 * _rtld_init has returned. It is OK to reference file-scope statics 398 * and string constants, and to call static and global functions. 399 */ 400 /* Find the auxiliary vector on the stack. */ 401 /* first Elf_Word reserved to address of exit routine */ 402 #if defined(RTLD_DEBUG) 403 debug = 1; 404 dbg(("sp = %p, argc = %ld, argv = %p <%s> relocbase %p", sp, 405 (long)sp[2], &sp[3], (char *) sp[3], (void *)relocbase)); 406 dbg(("got is at %p, dynamic is at %p", _GLOBAL_OFFSET_TABLE_, 407 &_DYNAMIC)); 408 dbg(("_ctype_ is %p", _ctype_)); 409 #endif 410 411 sp += 2; /* skip over return argument space */ 412 argv = (const char **) &sp[1]; 413 argc = *(long *)sp; 414 sp += 2 + argc; /* Skip over argc, arguments, and NULL 415 * terminator */ 416 env = (char **) sp; 417 while (*sp++ != 0) { /* Skip over environment, and NULL terminator */ 418 #if defined(RTLD_DEBUG) 419 dbg(("env[%d] = %p %s", i++, (void *)sp[-1], (char *)sp[-1])); 420 #endif 421 } 422 aux = (const AuxInfo *) sp; 423 424 pAUX_base = pAUX_entry = pAUX_execfd = NULL; 425 pAUX_phdr = pAUX_phent = pAUX_phnum = NULL; 426 pAUX_euid = pAUX_ruid = pAUX_egid = pAUX_rgid = NULL; 427 pAUX_pagesz = NULL; 428 429 execname = NULL; 430 431 /* Digest the auxiliary vector. */ 432 for (auxp = aux; auxp->a_type != AT_NULL; ++auxp) { 433 switch (auxp->a_type) { 434 case AT_BASE: 435 pAUX_base = auxp; 436 break; 437 case AT_ENTRY: 438 pAUX_entry = auxp; 439 break; 440 case AT_EXECFD: 441 pAUX_execfd = auxp; 442 break; 443 case AT_PHDR: 444 pAUX_phdr = auxp; 445 break; 446 case AT_PHENT: 447 pAUX_phent = auxp; 448 break; 449 case AT_PHNUM: 450 pAUX_phnum = auxp; 451 break; 452 #ifdef AT_EUID 453 case AT_EUID: 454 pAUX_euid = auxp; 455 break; 456 case AT_RUID: 457 pAUX_ruid = auxp; 458 break; 459 case AT_EGID: 460 pAUX_egid = auxp; 461 break; 462 case AT_RGID: 463 pAUX_rgid = auxp; 464 break; 465 #endif 466 #ifdef AT_SUN_EXECNAME 467 case AT_SUN_EXECNAME: 468 execname = (const char *)(const void *)auxp->a_v; 469 break; 470 #endif 471 case AT_PAGESZ: 472 pAUX_pagesz = auxp; 473 break; 474 } 475 } 476 477 /* Initialize and relocate ourselves. */ 478 if (pAUX_base == NULL) { 479 _rtld_error("Bad pAUX_base"); 480 _rtld_die(); 481 } 482 assert(pAUX_pagesz != NULL); 483 _rtld_pagesz = (int)pAUX_pagesz->a_v; 484 _rtld_init((caddr_t)pAUX_base->a_v, (caddr_t)relocbase, execname); 485 486 __progname = _rtld_objself.path; 487 environ = env; 488 489 _rtld_trust = ((pAUX_euid ? (uid_t)pAUX_euid->a_v : geteuid()) == 490 (pAUX_ruid ? (uid_t)pAUX_ruid->a_v : getuid())) && 491 ((pAUX_egid ? (gid_t)pAUX_egid->a_v : getegid()) == 492 (pAUX_rgid ? (gid_t)pAUX_rgid->a_v : getgid())); 493 494 #ifdef DEBUG 495 ld_debug = NULL; 496 #endif 497 ld_bind_now = NULL; 498 ld_library_path = NULL; 499 ld_preload = NULL; 500 /* 501 * Inline avoid using normal getenv/unsetenv here as the libc 502 * code is quite a bit more complicated. 503 */ 504 for (oenvp = env; *env != NULL; ++env) { 505 static const char bind_var[] = "LD_BIND_NOW="; 506 static const char debug_var[] = "LD_DEBUG="; 507 static const char path_var[] = "LD_LIBRARY_PATH="; 508 static const char preload_var[] = "LD_PRELOAD="; 509 #define LEN(x) (sizeof(x) - 1) 510 511 if ((*env)[0] != 'L' || (*env)[1] != 'D') { 512 /* 513 * Special case to skip most entries without 514 * the more expensive calls to strncmp. 515 */ 516 *oenvp++ = *env; 517 } else if (strncmp(*env, debug_var, LEN(debug_var)) == 0) { 518 if (_rtld_trust) { 519 #ifdef DEBUG 520 ld_debug = *env + LEN(debug_var); 521 #endif 522 *oenvp++ = *env; 523 } 524 } else if (strncmp(*env, bind_var, LEN(bind_var)) == 0) { 525 ld_bind_now = *env + LEN(bind_var); 526 } else if (strncmp(*env, path_var, LEN(path_var)) == 0) { 527 if (_rtld_trust) { 528 ld_library_path = *env + LEN(path_var); 529 *oenvp++ = *env; 530 } 531 } else if (strncmp(*env, preload_var, LEN(preload_var)) == 0) { 532 if (_rtld_trust) { 533 ld_preload = *env + LEN(preload_var); 534 *oenvp++ = *env; 535 } 536 } else { 537 *oenvp++ = *env; 538 } 539 #undef LEN 540 } 541 *oenvp++ = NULL; 542 543 if (ld_bind_now != NULL && *ld_bind_now != '\0') 544 bind_now = true; 545 if (_rtld_trust) { 546 #ifdef DEBUG 547 #ifdef RTLD_DEBUG 548 debug = 0; 549 #endif 550 if (ld_debug != NULL && *ld_debug != '\0') 551 debug = 1; 552 #endif 553 _rtld_add_paths(execname, &_rtld_paths, ld_library_path); 554 } else { 555 execname = NULL; 556 } 557 _rtld_process_hints(execname, &_rtld_paths, &_rtld_xforms, 558 _PATH_LD_HINTS); 559 dbg(("dynamic linker is initialized, mapbase=%p, relocbase=%p", 560 _rtld_objself.mapbase, _rtld_objself.relocbase)); 561 562 /* 563 * Load the main program, or process its program header if it is 564 * already loaded. 565 */ 566 if (pAUX_execfd != NULL) { /* Load the main program. */ 567 int fd = pAUX_execfd->a_v; 568 const char *obj_name = argv[0] ? argv[0] : "main program"; 569 dbg(("loading main program")); 570 _rtld_objmain = _rtld_map_object(obj_name, fd, NULL); 571 close(fd); 572 if (_rtld_objmain == NULL) 573 _rtld_die(); 574 } else { /* Main program already loaded. */ 575 const Elf_Phdr *phdr; 576 int phnum; 577 caddr_t entry; 578 579 dbg(("processing main program's program header")); 580 assert(pAUX_phdr != NULL); 581 phdr = (const Elf_Phdr *) pAUX_phdr->a_v; 582 assert(pAUX_phnum != NULL); 583 phnum = pAUX_phnum->a_v; 584 assert(pAUX_phent != NULL); 585 assert(pAUX_phent->a_v == sizeof(Elf_Phdr)); 586 assert(pAUX_entry != NULL); 587 entry = (caddr_t) pAUX_entry->a_v; 588 _rtld_objmain = _rtld_digest_phdr(phdr, phnum, entry); 589 _rtld_objmain->path = xstrdup(argv[0] ? argv[0] : 590 "main program"); 591 _rtld_objmain->pathlen = strlen(_rtld_objmain->path); 592 } 593 594 _rtld_objmain->mainprog = true; 595 596 /* 597 * Get the actual dynamic linker pathname from the executable if 598 * possible. (It should always be possible.) That ensures that 599 * gdb will find the right dynamic linker even if a non-standard 600 * one is being used. 601 */ 602 if (_rtld_objmain->interp != NULL && 603 strcmp(_rtld_objmain->interp, _rtld_objself.path) != 0) 604 _rtld_objself.path = xstrdup(_rtld_objmain->interp); 605 dbg(("actual dynamic linker is %s", _rtld_objself.path)); 606 607 _rtld_digest_dynamic(execname, _rtld_objmain); 608 609 /* Link the main program into the list of objects. */ 610 *_rtld_objtail = _rtld_objmain; 611 _rtld_objtail = &_rtld_objmain->next; 612 _rtld_objcount++; 613 _rtld_objloads++; 614 615 _rtld_linkmap_add(_rtld_objmain); 616 _rtld_linkmap_add(&_rtld_objself); 617 618 ++_rtld_objmain->refcount; 619 _rtld_objmain->mainref = 1; 620 _rtld_objlist_push_tail(&_rtld_list_main, _rtld_objmain); 621 622 if (ld_preload) { 623 /* 624 * Pre-load user-specified objects after the main program 625 * but before any shared object dependencies. 626 */ 627 dbg(("preloading objects")); 628 if (_rtld_preload(ld_preload) == -1) 629 _rtld_die(); 630 } 631 632 dbg(("loading needed objects")); 633 if (_rtld_load_needed_objects(_rtld_objmain, _RTLD_MAIN) == -1) 634 _rtld_die(); 635 636 dbg(("checking for required versions")); 637 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) { 638 if (_rtld_verify_object_versions(obj) == -1) 639 _rtld_die(); 640 } 641 642 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 643 dbg(("initializing initial Thread Local Storage")); 644 /* 645 * All initial objects get the TLS space from the static block. 646 */ 647 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) 648 _rtld_tls_offset_allocate(obj); 649 _rtld_tls_initial_allocation(); 650 #endif 651 652 dbg(("relocating objects")); 653 if (_rtld_relocate_objects(_rtld_objmain, bind_now) == -1) 654 _rtld_die(); 655 656 dbg(("doing copy relocations")); 657 if (_rtld_do_copy_relocations(_rtld_objmain) == -1) 658 _rtld_die(); 659 660 /* 661 * Set the __progname, environ and, __mainprog_obj before 662 * calling anything that might use them. 663 */ 664 real___progname = _rtld_objmain_sym("__progname"); 665 if (real___progname) { 666 if (argv[0] != NULL) { 667 if ((*real___progname = strrchr(argv[0], '/')) == NULL) 668 (*real___progname) = argv[0]; 669 else 670 (*real___progname)++; 671 } else { 672 (*real___progname) = NULL; 673 } 674 } 675 real_environ = _rtld_objmain_sym("environ"); 676 if (real_environ) 677 *real_environ = environ; 678 /* 679 * Set __mainprog_obj for old binaries. 680 */ 681 real___mainprog_obj = _rtld_objmain_sym("__mainprog_obj"); 682 if (real___mainprog_obj) 683 *real___mainprog_obj = _rtld_objmain; 684 685 _rtld_exclusive_enter(&mask); 686 687 dbg(("calling _init functions")); 688 _rtld_call_init_functions(&mask); 689 690 dbg(("control at program entry point = %p, obj = %p, exit = %p", 691 _rtld_objmain->entry, _rtld_objmain, _rtld_exit)); 692 693 _rtld_exclusive_exit(&mask); 694 695 /* 696 * Return with the entry point and the exit procedure in at the top 697 * of stack. 698 */ 699 700 _rtld_debug_state(); /* say hello to gdb! */ 701 702 ((void **) osp)[0] = _rtld_exit; 703 ((void **) osp)[1] = _rtld_objmain; 704 return (Elf_Addr) _rtld_objmain->entry; 705 } 706 707 void 708 _rtld_die(void) 709 { 710 const char *msg = dlerror(); 711 712 if (msg == NULL) 713 msg = "Fatal error"; 714 xerrx(1, "%s", msg); 715 } 716 717 static Obj_Entry * 718 _rtld_dlcheck(void *handle) 719 { 720 Obj_Entry *obj; 721 722 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) 723 if (obj == (Obj_Entry *) handle) 724 break; 725 726 if (obj == NULL || obj->dl_refcount == 0) { 727 xwarnx("Invalid shared object handle %p", handle); 728 return NULL; 729 } 730 return obj; 731 } 732 733 static void 734 _rtld_initlist_visit(Objlist* list, Obj_Entry *obj, int rev) 735 { 736 Needed_Entry* elm; 737 738 /* dbg(("_rtld_initlist_visit(%s)", obj->path)); */ 739 740 if (obj->init_done) 741 return; 742 obj->init_done = 1; 743 744 for (elm = obj->needed; elm != NULL; elm = elm->next) { 745 if (elm->obj != NULL) { 746 _rtld_initlist_visit(list, elm->obj, rev); 747 } 748 } 749 750 if (rev) { 751 _rtld_objlist_push_head(list, obj); 752 } else { 753 _rtld_objlist_push_tail(list, obj); 754 } 755 } 756 757 static void 758 _rtld_initlist_tsort(Objlist* list, int rev) 759 { 760 dbg(("_rtld_initlist_tsort")); 761 762 Obj_Entry* obj; 763 764 for (obj = _rtld_objlist->next; obj; obj = obj->next) { 765 obj->init_done = 0; 766 } 767 768 for (obj = _rtld_objlist->next; obj; obj = obj->next) { 769 _rtld_initlist_visit(list, obj, rev); 770 } 771 } 772 773 static void 774 _rtld_init_dag(Obj_Entry *root) 775 { 776 777 _rtld_init_dag1(root, root); 778 } 779 780 static void 781 _rtld_init_dag1(Obj_Entry *root, Obj_Entry *obj) 782 { 783 const Needed_Entry *needed; 784 785 if (!obj->mainref) { 786 if (_rtld_objlist_find(&obj->dldags, root)) 787 return; 788 dbg(("add %p (%s) to %p (%s) DAG", obj, obj->path, root, 789 root->path)); 790 _rtld_objlist_push_tail(&obj->dldags, root); 791 _rtld_objlist_push_tail(&root->dagmembers, obj); 792 } 793 for (needed = obj->needed; needed != NULL; needed = needed->next) 794 if (needed->obj != NULL) 795 _rtld_init_dag1(root, needed->obj); 796 } 797 798 /* 799 * Note, this is called only for objects loaded by dlopen(). 800 */ 801 static void 802 _rtld_unload_object(sigset_t *mask, Obj_Entry *root, bool do_fini_funcs) 803 { 804 805 _rtld_unref_dag(root); 806 if (root->refcount == 0) { /* We are finished with some objects. */ 807 Obj_Entry *obj; 808 Obj_Entry **linkp; 809 Objlist_Entry *elm; 810 811 /* Finalize objects that are about to be unmapped. */ 812 if (do_fini_funcs) 813 _rtld_call_fini_functions(mask, 0); 814 815 /* Remove the DAG from all objects' DAG lists. */ 816 SIMPLEQ_FOREACH(elm, &root->dagmembers, link) 817 _rtld_objlist_remove(&elm->obj->dldags, root); 818 819 /* Remove the DAG from the RTLD_GLOBAL list. */ 820 if (root->globalref) { 821 root->globalref = 0; 822 _rtld_objlist_remove(&_rtld_list_global, root); 823 } 824 825 /* Unmap all objects that are no longer referenced. */ 826 linkp = &_rtld_objlist->next; 827 while ((obj = *linkp) != NULL) { 828 if (obj->refcount == 0) { 829 dbg(("unloading \"%s\"", obj->path)); 830 if (obj->ehdr != MAP_FAILED) 831 munmap(obj->ehdr, _rtld_pagesz); 832 munmap(obj->mapbase, obj->mapsize); 833 _rtld_objlist_remove(&_rtld_list_global, obj); 834 _rtld_linkmap_delete(obj); 835 *linkp = obj->next; 836 _rtld_objcount--; 837 _rtld_obj_free(obj); 838 } else 839 linkp = &obj->next; 840 } 841 _rtld_objtail = linkp; 842 } 843 } 844 845 void 846 _rtld_ref_dag(Obj_Entry *root) 847 { 848 const Needed_Entry *needed; 849 850 assert(root); 851 852 ++root->refcount; 853 854 dbg(("incremented reference on \"%s\" (%d)", root->path, 855 root->refcount)); 856 for (needed = root->needed; needed != NULL; 857 needed = needed->next) { 858 if (needed->obj != NULL) 859 _rtld_ref_dag(needed->obj); 860 } 861 } 862 863 static void 864 _rtld_unref_dag(Obj_Entry *root) 865 { 866 867 assert(root); 868 assert(root->refcount != 0); 869 870 --root->refcount; 871 dbg(("decremented reference on \"%s\" (%d)", root->path, 872 root->refcount)); 873 874 if (root->refcount == 0) { 875 const Needed_Entry *needed; 876 877 for (needed = root->needed; needed != NULL; 878 needed = needed->next) { 879 if (needed->obj != NULL) 880 _rtld_unref_dag(needed->obj); 881 } 882 } 883 } 884 885 __strong_alias(__dlclose,dlclose) 886 int 887 dlclose(void *handle) 888 { 889 Obj_Entry *root; 890 sigset_t mask; 891 892 dbg(("dlclose of %p", handle)); 893 894 _rtld_exclusive_enter(&mask); 895 896 root = _rtld_dlcheck(handle); 897 898 if (root == NULL) { 899 _rtld_exclusive_exit(&mask); 900 return -1; 901 } 902 903 _rtld_debug.r_state = RT_DELETE; 904 _rtld_debug_state(); 905 906 --root->dl_refcount; 907 _rtld_unload_object(&mask, root, true); 908 909 _rtld_debug.r_state = RT_CONSISTENT; 910 _rtld_debug_state(); 911 912 _rtld_exclusive_exit(&mask); 913 914 return 0; 915 } 916 917 __strong_alias(__dlerror,dlerror) 918 char * 919 dlerror(void) 920 { 921 char *msg = error_message; 922 923 error_message = NULL; 924 return msg; 925 } 926 927 __strong_alias(__dlopen,dlopen) 928 void * 929 dlopen(const char *name, int mode) 930 { 931 Obj_Entry **old_obj_tail = _rtld_objtail; 932 Obj_Entry *obj = NULL; 933 int flags = _RTLD_DLOPEN; 934 bool nodelete; 935 bool now; 936 sigset_t mask; 937 int result; 938 939 dbg(("dlopen of %s %d", name, mode)); 940 941 _rtld_exclusive_enter(&mask); 942 943 flags |= (mode & RTLD_GLOBAL) ? _RTLD_GLOBAL : 0; 944 flags |= (mode & RTLD_NOLOAD) ? _RTLD_NOLOAD : 0; 945 946 nodelete = (mode & RTLD_NODELETE) ? true : false; 947 now = ((mode & RTLD_MODEMASK) == RTLD_NOW) ? true : false; 948 949 _rtld_debug.r_state = RT_ADD; 950 _rtld_debug_state(); 951 952 if (name == NULL) { 953 obj = _rtld_objmain; 954 obj->refcount++; 955 } else 956 obj = _rtld_load_library(name, _rtld_objmain, flags); 957 958 959 if (obj != NULL) { 960 ++obj->dl_refcount; 961 if (*old_obj_tail != NULL) { /* We loaded something new. */ 962 assert(*old_obj_tail == obj); 963 964 result = _rtld_load_needed_objects(obj, flags); 965 if (result != -1) { 966 Objlist_Entry *entry; 967 _rtld_init_dag(obj); 968 SIMPLEQ_FOREACH(entry, &obj->dagmembers, link) { 969 result = _rtld_verify_object_versions(entry->obj); 970 if (result == -1) 971 break; 972 } 973 } 974 if (result == -1 || _rtld_relocate_objects(obj, 975 (now || obj->z_now)) == -1) { 976 _rtld_unload_object(&mask, obj, false); 977 obj->dl_refcount--; 978 obj = NULL; 979 } else { 980 _rtld_call_init_functions(&mask); 981 } 982 } 983 if (obj != NULL) { 984 if ((nodelete || obj->z_nodelete) && !obj->ref_nodel) { 985 dbg(("dlopen obj %s nodelete", obj->path)); 986 _rtld_ref_dag(obj); 987 obj->z_nodelete = obj->ref_nodel = true; 988 } 989 } 990 } 991 _rtld_debug.r_state = RT_CONSISTENT; 992 _rtld_debug_state(); 993 994 _rtld_exclusive_exit(&mask); 995 996 return obj; 997 } 998 999 /* 1000 * Find a symbol in the main program. 1001 */ 1002 void * 1003 _rtld_objmain_sym(const char *name) 1004 { 1005 unsigned long hash; 1006 const Elf_Sym *def; 1007 const Obj_Entry *obj; 1008 DoneList donelist; 1009 1010 hash = _rtld_elf_hash(name); 1011 obj = _rtld_objmain; 1012 _rtld_donelist_init(&donelist); 1013 1014 def = _rtld_symlook_list(name, hash, &_rtld_list_main, &obj, 0, 1015 NULL, &donelist); 1016 1017 if (def != NULL) 1018 return obj->relocbase + def->st_value; 1019 return NULL; 1020 } 1021 1022 #ifdef __powerpc__ 1023 static void * 1024 hackish_return_address(void) 1025 { 1026 return __builtin_return_address(1); 1027 } 1028 #endif 1029 1030 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1031 #define lookup_mutex_enter() _rtld_exclusive_enter(&mask) 1032 #define lookup_mutex_exit() _rtld_exclusive_exit(&mask) 1033 #else 1034 #define lookup_mutex_enter() _rtld_shared_enter() 1035 #define lookup_mutex_exit() _rtld_shared_exit() 1036 #endif 1037 1038 static void * 1039 do_dlsym(void *handle, const char *name, const Ver_Entry *ventry) 1040 { 1041 const Obj_Entry *obj; 1042 unsigned long hash; 1043 const Elf_Sym *def; 1044 const Obj_Entry *defobj; 1045 void *retaddr; 1046 DoneList donelist; 1047 const u_int flags = SYMLOOK_DLSYM | SYMLOOK_IN_PLT; 1048 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1049 sigset_t mask; 1050 #endif 1051 1052 lookup_mutex_enter(); 1053 1054 hash = _rtld_elf_hash(name); 1055 def = NULL; 1056 defobj = NULL; 1057 1058 switch ((intptr_t)handle) { 1059 case (intptr_t)NULL: 1060 case (intptr_t)RTLD_NEXT: 1061 case (intptr_t)RTLD_DEFAULT: 1062 case (intptr_t)RTLD_SELF: 1063 #ifdef __powerpc__ 1064 retaddr = hackish_return_address(); 1065 #else 1066 retaddr = __builtin_return_address(0); 1067 #endif 1068 if ((obj = _rtld_obj_from_addr(retaddr)) == NULL) { 1069 _rtld_error("Cannot determine caller's shared object"); 1070 lookup_mutex_exit(); 1071 return NULL; 1072 } 1073 1074 switch ((intptr_t)handle) { 1075 case (intptr_t)NULL: /* Just the caller's shared object. */ 1076 def = _rtld_symlook_obj(name, hash, obj, flags, ventry); 1077 defobj = obj; 1078 break; 1079 1080 case (intptr_t)RTLD_NEXT: /* Objects after callers */ 1081 obj = obj->next; 1082 /*FALLTHROUGH*/ 1083 1084 case (intptr_t)RTLD_SELF: /* Caller included */ 1085 for (; obj; obj = obj->next) { 1086 if ((def = _rtld_symlook_obj(name, hash, obj, 1087 flags, ventry)) != NULL) { 1088 defobj = obj; 1089 break; 1090 } 1091 } 1092 break; 1093 1094 case (intptr_t)RTLD_DEFAULT: 1095 def = _rtld_symlook_default(name, hash, obj, &defobj, 1096 flags, ventry); 1097 break; 1098 1099 default: 1100 abort(); 1101 } 1102 break; 1103 1104 default: 1105 if ((obj = _rtld_dlcheck(handle)) == NULL) { 1106 lookup_mutex_exit(); 1107 return NULL; 1108 } 1109 1110 _rtld_donelist_init(&donelist); 1111 1112 if (obj->mainprog) { 1113 /* Search main program and all libraries loaded by it */ 1114 def = _rtld_symlook_list(name, hash, &_rtld_list_main, 1115 &defobj, flags, ventry, &donelist); 1116 } else { 1117 Needed_Entry fake; 1118 DoneList depth; 1119 1120 /* Search the object and all the libraries loaded by it. */ 1121 fake.next = NULL; 1122 fake.obj = __UNCONST(obj); 1123 fake.name = 0; 1124 1125 _rtld_donelist_init(&depth); 1126 def = _rtld_symlook_needed(name, hash, &fake, &defobj, 1127 flags, ventry, &donelist, &depth); 1128 } 1129 1130 break; 1131 } 1132 1133 if (def != NULL) { 1134 void *p; 1135 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1136 if (ELF_ST_TYPE(def->st_info) == STT_FUNC) { 1137 p = (void *)_rtld_function_descriptor_alloc(defobj, 1138 def, 0); 1139 lookup_mutex_exit(); 1140 return p; 1141 } 1142 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 1143 p = defobj->relocbase + def->st_value; 1144 lookup_mutex_exit(); 1145 return p; 1146 } 1147 1148 _rtld_error("Undefined symbol \"%s\"", name); 1149 lookup_mutex_exit(); 1150 return NULL; 1151 } 1152 1153 __strong_alias(__dlsym,dlsym) 1154 void * 1155 dlsym(void *handle, const char *name) 1156 { 1157 1158 dbg(("dlsym of %s in %p", name, handle)); 1159 1160 return do_dlsym(handle, name, NULL); 1161 } 1162 1163 __strong_alias(__dlvsym,dlvsym) 1164 void * 1165 dlvsym(void *handle, const char *name, const char *version) 1166 { 1167 Ver_Entry *ventry = NULL; 1168 Ver_Entry ver_entry; 1169 1170 dbg(("dlvsym of %s@%s in %p", name, version ? version : NULL, handle)); 1171 1172 if (version != NULL) { 1173 ver_entry.name = version; 1174 ver_entry.file = NULL; 1175 ver_entry.hash = _rtld_elf_hash(version); 1176 ver_entry.flags = 0; 1177 ventry = &ver_entry; 1178 } 1179 return do_dlsym(handle, name, ventry); 1180 } 1181 1182 __strong_alias(__dladdr,dladdr) 1183 int 1184 dladdr(const void *addr, Dl_info *info) 1185 { 1186 const Obj_Entry *obj; 1187 const Elf_Sym *def, *best_def; 1188 void *symbol_addr; 1189 unsigned long symoffset; 1190 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1191 sigset_t mask; 1192 #endif 1193 1194 dbg(("dladdr of %p", addr)); 1195 1196 lookup_mutex_enter(); 1197 1198 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1199 addr = _rtld_function_descriptor_function(addr); 1200 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 1201 1202 obj = _rtld_obj_from_addr(addr); 1203 if (obj == NULL) { 1204 _rtld_error("No shared object contains address"); 1205 lookup_mutex_enter(); 1206 return 0; 1207 } 1208 info->dli_fname = obj->path; 1209 info->dli_fbase = obj->mapbase; 1210 info->dli_saddr = (void *)0; 1211 info->dli_sname = NULL; 1212 1213 /* 1214 * Walk the symbol list looking for the symbol whose address is 1215 * closest to the address sent in. 1216 */ 1217 best_def = NULL; 1218 for (symoffset = 0; symoffset < obj->nchains; symoffset++) { 1219 def = obj->symtab + symoffset; 1220 1221 /* 1222 * For skip the symbol if st_shndx is either SHN_UNDEF or 1223 * SHN_COMMON. 1224 */ 1225 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON) 1226 continue; 1227 1228 /* 1229 * If the symbol is greater than the specified address, or if it 1230 * is further away from addr than the current nearest symbol, 1231 * then reject it. 1232 */ 1233 symbol_addr = obj->relocbase + def->st_value; 1234 if (symbol_addr > addr || symbol_addr < info->dli_saddr) 1235 continue; 1236 1237 /* Update our idea of the nearest symbol. */ 1238 info->dli_sname = obj->strtab + def->st_name; 1239 info->dli_saddr = symbol_addr; 1240 best_def = def; 1241 1242 /* Exact match? */ 1243 if (info->dli_saddr == addr) 1244 break; 1245 } 1246 1247 #ifdef __HAVE_FUNCTION_DESCRIPTORS 1248 if (best_def != NULL && ELF_ST_TYPE(best_def->st_info) == STT_FUNC) 1249 info->dli_saddr = (void *)_rtld_function_descriptor_alloc(obj, 1250 best_def, 0); 1251 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 1252 1253 lookup_mutex_exit(); 1254 return 1; 1255 } 1256 1257 __strong_alias(__dlinfo,dlinfo) 1258 int 1259 dlinfo(void *handle, int req, void *v) 1260 { 1261 const Obj_Entry *obj; 1262 void *retaddr; 1263 1264 dbg(("dlinfo for %p %d", handle, req)); 1265 1266 _rtld_shared_enter(); 1267 1268 if (handle == RTLD_SELF) { 1269 #ifdef __powerpc__ 1270 retaddr = hackish_return_address(); 1271 #else 1272 retaddr = __builtin_return_address(0); 1273 #endif 1274 if ((obj = _rtld_obj_from_addr(retaddr)) == NULL) { 1275 _rtld_error("Cannot determine caller's shared object"); 1276 _rtld_shared_exit(); 1277 return -1; 1278 } 1279 } else { 1280 if ((obj = _rtld_dlcheck(handle)) == NULL) { 1281 _rtld_error("Invalid handle"); 1282 _rtld_shared_exit(); 1283 return -1; 1284 } 1285 } 1286 1287 switch (req) { 1288 case RTLD_DI_LINKMAP: 1289 { 1290 const struct link_map **map = v; 1291 1292 *map = &obj->linkmap; 1293 break; 1294 } 1295 1296 default: 1297 _rtld_error("Invalid request"); 1298 _rtld_shared_exit(); 1299 return -1; 1300 } 1301 1302 _rtld_shared_exit(); 1303 return 0; 1304 } 1305 1306 __strong_alias(__dl_iterate_phdr,dl_iterate_phdr); 1307 int 1308 dl_iterate_phdr(int (*callback)(struct dl_phdr_info *, size_t, void *), void *param) 1309 { 1310 struct dl_phdr_info phdr_info; 1311 const Obj_Entry *obj; 1312 int error = 0; 1313 1314 dbg(("dl_iterate_phdr")); 1315 1316 _rtld_shared_enter(); 1317 1318 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) { 1319 phdr_info.dlpi_addr = (Elf_Addr)obj->relocbase; 1320 phdr_info.dlpi_name = STAILQ_FIRST(&obj->names) ? 1321 STAILQ_FIRST(&obj->names)->name : obj->path; 1322 phdr_info.dlpi_phdr = obj->phdr; 1323 phdr_info.dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]); 1324 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) 1325 phdr_info.dlpi_tls_modid = obj->tlsindex; 1326 phdr_info.dlpi_tls_data = obj->tlsinit; 1327 #else 1328 phdr_info.dlpi_tls_modid = 0; 1329 phdr_info.dlpi_tls_data = 0; 1330 #endif 1331 phdr_info.dlpi_adds = _rtld_objloads; 1332 phdr_info.dlpi_subs = _rtld_objloads - _rtld_objcount; 1333 1334 /* XXXlocking: exit point */ 1335 error = callback(&phdr_info, sizeof(phdr_info), param); 1336 if (error) 1337 break; 1338 } 1339 1340 _rtld_shared_exit(); 1341 return error; 1342 } 1343 1344 /* 1345 * Error reporting function. Use it like printf. If formats the message 1346 * into a buffer, and sets things up so that the next call to dlerror() 1347 * will return the message. 1348 */ 1349 void 1350 _rtld_error(const char *fmt,...) 1351 { 1352 static char buf[512]; 1353 va_list ap; 1354 1355 va_start(ap, fmt); 1356 xvsnprintf(buf, sizeof buf, fmt, ap); 1357 error_message = buf; 1358 va_end(ap); 1359 } 1360 1361 void 1362 _rtld_debug_state(void) 1363 { 1364 1365 /* do nothing */ 1366 } 1367 1368 void 1369 _rtld_linkmap_add(Obj_Entry *obj) 1370 { 1371 struct link_map *l = &obj->linkmap; 1372 struct link_map *prev; 1373 1374 obj->linkmap.l_name = obj->path; 1375 obj->linkmap.l_addr = obj->relocbase; 1376 obj->linkmap.l_ld = obj->dynamic; 1377 #ifdef __mips__ 1378 /* XXX This field is not standard and will be removed eventually. */ 1379 obj->linkmap.l_offs = obj->relocbase; 1380 #endif 1381 1382 if (_rtld_debug.r_map == NULL) { 1383 _rtld_debug.r_map = l; 1384 return; 1385 } 1386 1387 /* 1388 * Scan to the end of the list, but not past the entry for the 1389 * dynamic linker, which we want to keep at the very end. 1390 */ 1391 for (prev = _rtld_debug.r_map; 1392 prev->l_next != NULL && prev->l_next != &_rtld_objself.linkmap; 1393 prev = prev->l_next); 1394 1395 l->l_prev = prev; 1396 l->l_next = prev->l_next; 1397 if (l->l_next != NULL) 1398 l->l_next->l_prev = l; 1399 prev->l_next = l; 1400 } 1401 1402 void 1403 _rtld_linkmap_delete(Obj_Entry *obj) 1404 { 1405 struct link_map *l = &obj->linkmap; 1406 1407 if (l->l_prev == NULL) { 1408 if ((_rtld_debug.r_map = l->l_next) != NULL) 1409 l->l_next->l_prev = NULL; 1410 return; 1411 } 1412 if ((l->l_prev->l_next = l->l_next) != NULL) 1413 l->l_next->l_prev = l->l_prev; 1414 } 1415 1416 static Obj_Entry * 1417 _rtld_obj_from_addr(const void *addr) 1418 { 1419 Obj_Entry *obj; 1420 1421 for (obj = _rtld_objlist; obj != NULL; obj = obj->next) { 1422 if (addr < (void *) obj->mapbase) 1423 continue; 1424 if (addr < (void *) (obj->mapbase + obj->mapsize)) 1425 return obj; 1426 } 1427 return NULL; 1428 } 1429 1430 static void 1431 _rtld_objlist_clear(Objlist *list) 1432 { 1433 while (!SIMPLEQ_EMPTY(list)) { 1434 Objlist_Entry* elm = SIMPLEQ_FIRST(list); 1435 SIMPLEQ_REMOVE_HEAD(list, link); 1436 xfree(elm); 1437 } 1438 } 1439 1440 static void 1441 _rtld_objlist_remove(Objlist *list, Obj_Entry *obj) 1442 { 1443 Objlist_Entry *elm; 1444 1445 if ((elm = _rtld_objlist_find(list, obj)) != NULL) { 1446 SIMPLEQ_REMOVE(list, elm, Struct_Objlist_Entry, link); 1447 xfree(elm); 1448 } 1449 } 1450 1451 #define RTLD_EXCLUSIVE_MASK 0x80000000U 1452 static volatile unsigned int _rtld_mutex; 1453 static volatile unsigned int _rtld_waiter_exclusive; 1454 static volatile unsigned int _rtld_waiter_shared; 1455 1456 void 1457 _rtld_shared_enter(void) 1458 { 1459 unsigned int cur; 1460 lwpid_t waiter, self = 0; 1461 1462 membar_enter(); 1463 1464 for (;;) { 1465 cur = _rtld_mutex; 1466 /* 1467 * First check if we are currently not exclusively locked. 1468 */ 1469 if ((cur & RTLD_EXCLUSIVE_MASK) == 0) { 1470 /* Yes, so increment use counter */ 1471 if (atomic_cas_uint(&_rtld_mutex, cur, cur + 1) != cur) 1472 continue; 1473 return; 1474 } 1475 /* 1476 * Someone has an exclusive lock. Puts us on the waiter list. 1477 */ 1478 if (!self) 1479 self = _lwp_self(); 1480 if (cur == (self | RTLD_EXCLUSIVE_MASK)) { 1481 if (_rtld_mutex_may_recurse) 1482 return; 1483 _rtld_error("dead lock detected"); 1484 _rtld_die(); 1485 } 1486 waiter = atomic_swap_uint(&_rtld_waiter_shared, self); 1487 /* 1488 * Check for race against _rtld_exclusive_exit before sleeping. 1489 */ 1490 if ((_rtld_mutex & RTLD_EXCLUSIVE_MASK) || 1491 _rtld_waiter_exclusive) 1492 _lwp_park(NULL, -1, __UNVOLATILE(&_rtld_mutex), NULL); 1493 /* Try to remove us from the waiter list. */ 1494 atomic_cas_uint(&_rtld_waiter_shared, self, 0); 1495 if (waiter) 1496 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1497 } 1498 } 1499 1500 void 1501 _rtld_shared_exit(void) 1502 { 1503 lwpid_t waiter; 1504 1505 /* 1506 * Shared lock taken after an exclusive lock. 1507 * Just assume this is a partial recursion. 1508 */ 1509 if (_rtld_mutex & RTLD_EXCLUSIVE_MASK) 1510 return; 1511 1512 /* 1513 * Wakeup LWPs waiting for an exclusive lock if this is the last 1514 * LWP on the shared lock. 1515 */ 1516 if (atomic_dec_uint_nv(&_rtld_mutex)) 1517 return; 1518 if ((waiter = _rtld_waiter_exclusive) != 0) 1519 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1520 1521 membar_exit(); 1522 } 1523 1524 void 1525 _rtld_exclusive_enter(sigset_t *mask) 1526 { 1527 lwpid_t waiter, self = _lwp_self(); 1528 unsigned int locked_value = (unsigned int)self | RTLD_EXCLUSIVE_MASK; 1529 unsigned int cur; 1530 sigset_t blockmask; 1531 1532 sigfillset(&blockmask); 1533 sigprocmask(SIG_BLOCK, &blockmask, mask); 1534 1535 membar_enter(); 1536 1537 for (;;) { 1538 if (atomic_cas_uint(&_rtld_mutex, 0, locked_value) == 0) 1539 break; 1540 waiter = atomic_swap_uint(&_rtld_waiter_exclusive, self); 1541 cur = _rtld_mutex; 1542 if (cur == locked_value) { 1543 _rtld_error("dead lock detected"); 1544 _rtld_die(); 1545 } 1546 if (cur) 1547 _lwp_park(NULL, -1, __UNVOLATILE(&_rtld_mutex), NULL); 1548 atomic_cas_uint(&_rtld_waiter_exclusive, self, 0); 1549 if (waiter) 1550 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1551 } 1552 } 1553 1554 void 1555 _rtld_exclusive_exit(sigset_t *mask) 1556 { 1557 lwpid_t waiter; 1558 1559 _rtld_mutex = 0; 1560 if ((waiter = _rtld_waiter_exclusive) != 0) 1561 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1562 1563 if ((waiter = _rtld_waiter_shared) != 0) 1564 _lwp_unpark(waiter, __UNVOLATILE(&_rtld_mutex)); 1565 1566 membar_exit(); 1567 sigprocmask(SIG_SETMASK, mask, NULL); 1568 } 1569