1 /* 2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/classLoaderData.inline.hpp" 27 #include "classfile/dictionary.hpp" 28 #include "classfile/javaClasses.inline.hpp" 29 #include "classfile/loaderConstraints.hpp" 30 #include "classfile/placeholders.hpp" 31 #include "classfile/resolutionErrors.hpp" 32 #include "classfile/stringTable.hpp" 33 #include "classfile/systemDictionary.hpp" 34 #include "classfile/vmSymbols.hpp" 35 #include "code/codeCache.hpp" 36 #include "compiler/compileBroker.hpp" 37 #include "gc/shared/gcLocker.hpp" 38 #include "interpreter/bytecodeStream.hpp" 39 #include "interpreter/interpreter.hpp" 40 #include "memory/filemap.hpp" 41 #include "memory/oopFactory.hpp" 42 #include "oops/instanceKlass.hpp" 43 #include "oops/instanceRefKlass.hpp" 44 #include "oops/klass.inline.hpp" 45 #include "oops/methodData.hpp" 46 #include "oops/objArrayKlass.hpp" 47 #include "oops/objArrayOop.inline.hpp" 48 #include "oops/oop.inline.hpp" 49 #include "oops/typeArrayKlass.hpp" 50 #include "prims/jvmtiEnvBase.hpp" 51 #include "prims/methodHandles.hpp" 52 #include "runtime/arguments.hpp" 53 #include "runtime/biasedLocking.hpp" 54 #include "runtime/fieldType.hpp" 55 #include "runtime/handles.inline.hpp" 56 #include "runtime/java.hpp" 57 #include "runtime/javaCalls.hpp" 58 #include "runtime/mutexLocker.hpp" 59 #include "runtime/orderAccess.inline.hpp" 60 #include "runtime/signature.hpp" 61 #include "services/classLoadingService.hpp" 62 #include "services/threadService.hpp" 63 #include "utilities/macros.hpp" 64 #include "utilities/ticks.hpp" 65 #if INCLUDE_CDS 66 #include "classfile/sharedClassUtil.hpp" 67 #include "classfile/systemDictionaryShared.hpp" 68 #endif 69 #if INCLUDE_JVMCI 70 #include "jvmci/jvmciRuntime.hpp" 71 #endif 72 #if INCLUDE_TRACE 73 #include "trace/tracing.hpp" 74 #endif 75 76 Dictionary* SystemDictionary::_dictionary = NULL; 77 PlaceholderTable* SystemDictionary::_placeholders = NULL; 78 Dictionary* SystemDictionary::_shared_dictionary = NULL; 79 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL; 80 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL; 81 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL; 82 83 84 int SystemDictionary::_number_of_modifications = 0; 85 int SystemDictionary::_sdgeneration = 0; 86 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103, 87 20201,40423,99991}; 88 89 oop SystemDictionary::_system_loader_lock_obj = NULL; 90 91 Klass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT] 92 = { NULL /*, NULL...*/ }; 93 94 Klass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ }; 95 96 oop SystemDictionary::_java_system_loader = NULL; 97 98 bool SystemDictionary::_has_loadClassInternal = false; 99 bool SystemDictionary::_has_checkPackageAccess = false; 100 101 // lazily initialized klass variables 102 Klass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL; 103 104 105 // ---------------------------------------------------------------------------- 106 // Java-level SystemLoader 107 108 oop SystemDictionary::java_system_loader() { 109 return _java_system_loader; 110 } 111 112 void SystemDictionary::compute_java_system_loader(TRAPS) { 113 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass)); 114 JavaValue result(T_OBJECT); 115 JavaCalls::call_static(&result, 116 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)), 117 vmSymbols::getSystemClassLoader_name(), 118 vmSymbols::void_classloader_signature(), 119 CHECK); 120 121 _java_system_loader = (oop)result.get_jobject(); 122 123 CDS_ONLY(SystemDictionaryShared::initialize(CHECK);) 124 } 125 126 127 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) { 128 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data(); 129 return ClassLoaderDataGraph::find_or_create(class_loader, THREAD); 130 } 131 132 // ---------------------------------------------------------------------------- 133 // debugging 134 135 #ifdef ASSERT 136 137 // return true if class_name contains no '.' (internal format is '/') 138 bool SystemDictionary::is_internal_format(Symbol* class_name) { 139 if (class_name != NULL) { 140 ResourceMark rm; 141 char* name = class_name->as_C_string(); 142 return strchr(name, '.') == NULL; 143 } else { 144 return true; 145 } 146 } 147 148 #endif 149 150 // ---------------------------------------------------------------------------- 151 // Parallel class loading check 152 153 bool SystemDictionary::is_parallelCapable(Handle class_loader) { 154 if (UnsyncloadClass || class_loader.is_null()) return true; 155 if (AlwaysLockClassLoader) return false; 156 return java_lang_ClassLoader::parallelCapable(class_loader()); 157 } 158 // ---------------------------------------------------------------------------- 159 // ParallelDefineClass flag does not apply to bootclass loader 160 bool SystemDictionary::is_parallelDefine(Handle class_loader) { 161 if (class_loader.is_null()) return false; 162 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) { 163 return true; 164 } 165 return false; 166 } 167 168 /** 169 * Returns true if the passed class loader is the extension class loader. 170 */ 171 bool SystemDictionary::is_ext_class_loader(Handle class_loader) { 172 if (class_loader.is_null()) { 173 return false; 174 } 175 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader()); 176 } 177 178 // ---------------------------------------------------------------------------- 179 // Resolving of classes 180 181 // Forwards to resolve_or_null 182 183 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) { 184 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD); 185 if (HAS_PENDING_EXCEPTION || klass == NULL) { 186 KlassHandle k_h(THREAD, klass); 187 // can return a null klass 188 klass = handle_resolution_exception(class_name, throw_error, k_h, THREAD); 189 } 190 return klass; 191 } 192 193 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, 194 bool throw_error, 195 KlassHandle klass_h, TRAPS) { 196 if (HAS_PENDING_EXCEPTION) { 197 // If we have a pending exception we forward it to the caller, unless throw_error is true, 198 // in which case we have to check whether the pending exception is a ClassNotFoundException, 199 // and if so convert it to a NoClassDefFoundError 200 // And chain the original ClassNotFoundException 201 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) { 202 ResourceMark rm(THREAD); 203 assert(klass_h() == NULL, "Should not have result with exception pending"); 204 Handle e(THREAD, PENDING_EXCEPTION); 205 CLEAR_PENDING_EXCEPTION; 206 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e); 207 } else { 208 return NULL; 209 } 210 } 211 // Class not found, throw appropriate error or exception depending on value of throw_error 212 if (klass_h() == NULL) { 213 ResourceMark rm(THREAD); 214 if (throw_error) { 215 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string()); 216 } else { 217 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string()); 218 } 219 } 220 return (Klass*)klass_h(); 221 } 222 223 224 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, 225 bool throw_error, TRAPS) 226 { 227 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD); 228 } 229 230 231 // Forwards to resolve_instance_class_or_null 232 233 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) { 234 assert(THREAD->can_call_java(), 235 err_msg("can not load classes with compiler thread: class=%s, classloader=%s", 236 class_name->as_C_string(), 237 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string())); 238 if (FieldType::is_array(class_name)) { 239 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD); 240 } else if (FieldType::is_obj(class_name)) { 241 ResourceMark rm(THREAD); 242 // Ignore wrapping L and ;. 243 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1, 244 class_name->utf8_length() - 2, CHECK_NULL); 245 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD); 246 } else { 247 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD); 248 } 249 } 250 251 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) { 252 return resolve_or_null(class_name, Handle(), Handle(), THREAD); 253 } 254 255 // Forwards to resolve_instance_class_or_null 256 257 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name, 258 Handle class_loader, 259 Handle protection_domain, 260 TRAPS) { 261 assert(FieldType::is_array(class_name), "must be array"); 262 Klass* k = NULL; 263 FieldArrayInfo fd; 264 // dimension and object_key in FieldArrayInfo are assigned as a side-effect 265 // of this call 266 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL); 267 if (t == T_OBJECT) { 268 // naked oop "k" is OK here -- we assign back into it 269 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(), 270 class_loader, 271 protection_domain, 272 CHECK_NULL); 273 if (k != NULL) { 274 k = k->array_klass(fd.dimension(), CHECK_NULL); 275 } 276 } else { 277 k = Universe::typeArrayKlassObj(t); 278 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL); 279 } 280 return k; 281 } 282 283 284 // Must be called for any super-class or super-interface resolution 285 // during class definition to allow class circularity checking 286 // super-interface callers: 287 // parse_interfaces - for defineClass & jvmtiRedefineClasses 288 // super-class callers: 289 // ClassFileParser - for defineClass & jvmtiRedefineClasses 290 // load_shared_class - while loading a class from shared archive 291 // resolve_instance_class_or_null: 292 // via: handle_parallel_super_load 293 // when resolving a class that has an existing placeholder with 294 // a saved superclass [i.e. a defineClass is currently in progress] 295 // if another thread is trying to resolve the class, it must do 296 // super-class checks on its own thread to catch class circularity 297 // This last call is critical in class circularity checking for cases 298 // where classloading is delegated to different threads and the 299 // classloader lock is released. 300 // Take the case: Base->Super->Base 301 // 1. If thread T1 tries to do a defineClass of class Base 302 // resolve_super_or_fail creates placeholder: T1, Base (super Super) 303 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super 304 // so it tries to load Super 305 // 3. If we load the class internally, or user classloader uses same thread 306 // loadClassFromxxx or defineClass via parseClassFile Super ... 307 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base) 308 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base 309 // 3.4 calls resolve_super_or_fail Base 310 // 3.5 finds T1,Base -> throws class circularity 311 //OR 4. If T2 tries to resolve Super via defineClass Super ... 312 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base) 313 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super) 314 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2 315 // 4.4 finds T2, Super -> throws class circularity 316 // Must be called, even if superclass is null, since this is 317 // where the placeholder entry is created which claims this 318 // thread is loading this class/classloader. 319 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name, 320 Symbol* class_name, 321 Handle class_loader, 322 Handle protection_domain, 323 bool is_superclass, 324 TRAPS) { 325 // Double-check, if child class is already loaded, just return super-class,interface 326 // Don't add a placedholder if already loaded, i.e. already in system dictionary 327 // Make sure there's a placeholder for the *child* before resolving. 328 // Used as a claim that this thread is currently loading superclass/classloader 329 // Used here for ClassCircularity checks and also for heap verification 330 // (every InstanceKlass in the heap needs to be in the system dictionary 331 // or have a placeholder). 332 // Must check ClassCircularity before checking if super class is already loaded 333 // 334 // We might not already have a placeholder if this child_name was 335 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass); 336 // the name of the class might not be known until the stream is actually 337 // parsed. 338 // Bugs 4643874, 4715493 339 // compute_hash can have a safepoint 340 341 ClassLoaderData* loader_data = class_loader_data(class_loader); 342 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data); 343 int d_index = dictionary()->hash_to_index(d_hash); 344 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data); 345 int p_index = placeholders()->hash_to_index(p_hash); 346 // can't throw error holding a lock 347 bool child_already_loaded = false; 348 bool throw_circularity_error = false; 349 { 350 MutexLocker mu(SystemDictionary_lock, THREAD); 351 Klass* childk = find_class(d_index, d_hash, child_name, loader_data); 352 Klass* quicksuperk; 353 // to support // loading: if child done loading, just return superclass 354 // if class_name, & class_loader don't match: 355 // if initial define, SD update will give LinkageError 356 // if redefine: compare_class_versions will give HIERARCHY_CHANGED 357 // so we don't throw an exception here. 358 // see: nsk redefclass014 & java.lang.instrument Instrument032 359 if ((childk != NULL ) && (is_superclass) && 360 ((quicksuperk = InstanceKlass::cast(childk)->super()) != NULL) && 361 362 ((quicksuperk->name() == class_name) && 363 (quicksuperk->class_loader() == class_loader()))) { 364 return quicksuperk; 365 } else { 366 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data); 367 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) { 368 throw_circularity_error = true; 369 } 370 } 371 if (!throw_circularity_error) { 372 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD); 373 } 374 } 375 if (throw_circularity_error) { 376 ResourceMark rm(THREAD); 377 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string()); 378 } 379 380 // java.lang.Object should have been found above 381 assert(class_name != NULL, "null super class for resolving"); 382 // Resolve the super class or interface, check results on return 383 Klass* superk = SystemDictionary::resolve_or_null(class_name, 384 class_loader, 385 protection_domain, 386 THREAD); 387 388 KlassHandle superk_h(THREAD, superk); 389 390 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up 391 // It is no longer necessary to keep the placeholder table alive until update_dictionary 392 // or error. GC used to walk the placeholder table as strong roots. 393 // The instanceKlass is kept alive because the class loader is on the stack, 394 // which keeps the loader_data alive, as well as all instanceKlasses in 395 // the loader_data. parseClassFile adds the instanceKlass to loader_data. 396 { 397 MutexLocker mu(SystemDictionary_lock, THREAD); 398 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD); 399 SystemDictionary_lock->notify_all(); 400 } 401 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) { 402 // can null superk 403 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, true, superk_h, THREAD)); 404 } 405 406 return superk_h(); 407 } 408 409 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass, 410 Handle class_loader, 411 Handle protection_domain, 412 TRAPS) { 413 if(!has_checkPackageAccess()) return; 414 415 // Now we have to call back to java to check if the initating class has access 416 JavaValue result(T_VOID); 417 if (TraceProtectionDomainVerification) { 418 // Print out trace information 419 tty->print_cr("Checking package access"); 420 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr(); 421 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr(); 422 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr(); 423 } 424 425 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass()); 426 JavaCalls::call_special(&result, 427 class_loader, 428 system_loader, 429 vmSymbols::checkPackageAccess_name(), 430 vmSymbols::class_protectiondomain_signature(), 431 Handle(THREAD, klass->java_mirror()), 432 protection_domain, 433 THREAD); 434 435 if (TraceProtectionDomainVerification) { 436 if (HAS_PENDING_EXCEPTION) { 437 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!"); 438 } else { 439 tty->print_cr(" -> granted"); 440 } 441 tty->cr(); 442 } 443 444 if (HAS_PENDING_EXCEPTION) return; 445 446 // If no exception has been thrown, we have validated the protection domain 447 // Insert the protection domain of the initiating class into the set. 448 { 449 // We recalculate the entry here -- we've called out to java since 450 // the last time it was calculated. 451 ClassLoaderData* loader_data = class_loader_data(class_loader); 452 453 Symbol* kn = klass->name(); 454 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data); 455 int d_index = dictionary()->hash_to_index(d_hash); 456 457 MutexLocker mu(SystemDictionary_lock, THREAD); 458 { 459 // Note that we have an entry, and entries can be deleted only during GC, 460 // so we cannot allow GC to occur while we're holding this entry. 461 462 // We're using a No_Safepoint_Verifier to catch any place where we 463 // might potentially do a GC at all. 464 // Dictionary::do_unloading() asserts that classes in SD are only 465 // unloaded at a safepoint. Anonymous classes are not in SD. 466 No_Safepoint_Verifier nosafepoint; 467 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data, 468 protection_domain, THREAD); 469 } 470 } 471 } 472 473 // We only get here if this thread finds that another thread 474 // has already claimed the placeholder token for the current operation, 475 // but that other thread either never owned or gave up the 476 // object lock 477 // Waits on SystemDictionary_lock to indicate placeholder table updated 478 // On return, caller must recheck placeholder table state 479 // 480 // We only get here if 481 // 1) custom classLoader, i.e. not bootstrap classloader 482 // 2) UnsyncloadClass not set 483 // 3) custom classLoader has broken the class loader objectLock 484 // so another thread got here in parallel 485 // 486 // lockObject must be held. 487 // Complicated dance due to lock ordering: 488 // Must first release the classloader object lock to 489 // allow initial definer to complete the class definition 490 // and to avoid deadlock 491 // Reclaim classloader lock object with same original recursion count 492 // Must release SystemDictionary_lock after notify, since 493 // class loader lock must be claimed before SystemDictionary_lock 494 // to prevent deadlocks 495 // 496 // The notify allows applications that did an untimed wait() on 497 // the classloader object lock to not hang. 498 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) { 499 assert_lock_strong(SystemDictionary_lock); 500 501 bool calledholdinglock 502 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject); 503 assert(calledholdinglock,"must hold lock for notify"); 504 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait"); 505 ObjectSynchronizer::notifyall(lockObject, THREAD); 506 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD); 507 SystemDictionary_lock->wait(); 508 SystemDictionary_lock->unlock(); 509 ObjectSynchronizer::reenter(lockObject, recursions, THREAD); 510 SystemDictionary_lock->lock(); 511 } 512 513 // If the class in is in the placeholder table, class loading is in progress 514 // For cases where the application changes threads to load classes, it 515 // is critical to ClassCircularity detection that we try loading 516 // the superclass on the same thread internally, so we do parallel 517 // super class loading here. 518 // This also is critical in cases where the original thread gets stalled 519 // even in non-circularity situations. 520 // Note: must call resolve_super_or_fail even if null super - 521 // to force placeholder entry creation for this class for circularity detection 522 // Caller must check for pending exception 523 // Returns non-null Klass* if other thread has completed load 524 // and we are done, 525 // If return null Klass* and no pending exception, the caller must load the class 526 instanceKlassHandle SystemDictionary::handle_parallel_super_load( 527 Symbol* name, Symbol* superclassname, Handle class_loader, 528 Handle protection_domain, Handle lockObject, TRAPS) { 529 530 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 531 ClassLoaderData* loader_data = class_loader_data(class_loader); 532 unsigned int d_hash = dictionary()->compute_hash(name, loader_data); 533 int d_index = dictionary()->hash_to_index(d_hash); 534 unsigned int p_hash = placeholders()->compute_hash(name, loader_data); 535 int p_index = placeholders()->hash_to_index(p_hash); 536 537 // superk is not used, resolve_super called for circularity check only 538 // This code is reached in two situations. One if this thread 539 // is loading the same class twice (e.g. ClassCircularity, or 540 // java.lang.instrument). 541 // The second is if another thread started the resolve_super first 542 // and has not yet finished. 543 // In both cases the original caller will clean up the placeholder 544 // entry on error. 545 Klass* superk = SystemDictionary::resolve_super_or_fail(name, 546 superclassname, 547 class_loader, 548 protection_domain, 549 true, 550 CHECK_(nh)); 551 552 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete 553 // Serial class loaders and bootstrap classloader do wait for superclass loads 554 if (!class_loader.is_null() && is_parallelCapable(class_loader)) { 555 MutexLocker mu(SystemDictionary_lock, THREAD); 556 // Check if classloading completed while we were loading superclass or waiting 557 Klass* check = find_class(d_index, d_hash, name, loader_data); 558 if (check != NULL) { 559 // Klass is already loaded, so just return it 560 return(instanceKlassHandle(THREAD, check)); 561 } else { 562 return nh; 563 } 564 } 565 566 // must loop to both handle other placeholder updates 567 // and spurious notifications 568 bool super_load_in_progress = true; 569 PlaceholderEntry* placeholder; 570 while (super_load_in_progress) { 571 MutexLocker mu(SystemDictionary_lock, THREAD); 572 // Check if classloading completed while we were loading superclass or waiting 573 Klass* check = find_class(d_index, d_hash, name, loader_data); 574 if (check != NULL) { 575 // Klass is already loaded, so just return it 576 return(instanceKlassHandle(THREAD, check)); 577 } else { 578 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 579 if (placeholder && placeholder->super_load_in_progress() ){ 580 // Before UnsyncloadClass: 581 // We only get here if the application has released the 582 // classloader lock when another thread was in the middle of loading a 583 // superclass/superinterface for this class, and now 584 // this thread is also trying to load this class. 585 // To minimize surprises, the first thread that started to 586 // load a class should be the one to complete the loading 587 // with the classfile it initially expected. 588 // This logic has the current thread wait once it has done 589 // all the superclass/superinterface loading it can, until 590 // the original thread completes the class loading or fails 591 // If it completes we will use the resulting InstanceKlass 592 // which we will find below in the systemDictionary. 593 // We also get here for parallel bootstrap classloader 594 if (class_loader.is_null()) { 595 SystemDictionary_lock->wait(); 596 } else { 597 double_lock_wait(lockObject, THREAD); 598 } 599 } else { 600 // If not in SD and not in PH, other thread's load must have failed 601 super_load_in_progress = false; 602 } 603 } 604 } 605 return (nh); 606 } 607 608 609 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, 610 Handle class_loader, 611 Handle protection_domain, 612 TRAPS) { 613 assert(name != NULL && !FieldType::is_array(name) && 614 !FieldType::is_obj(name), "invalid class name"); 615 616 Ticks class_load_start_time = Ticks::now(); 617 618 // Fix for 4474172; see evaluation for more details 619 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 620 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL); 621 622 // Do lookup to see if class already exist and the protection domain 623 // has the right access 624 // This call uses find which checks protection domain already matches 625 // All subsequent calls use find_class, and set has_loaded_class so that 626 // before we return a result we call out to java to check for valid protection domain 627 // to allow returning the Klass* and add it to the pd_set if it is valid 628 unsigned int d_hash = dictionary()->compute_hash(name, loader_data); 629 int d_index = dictionary()->hash_to_index(d_hash); 630 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data, 631 protection_domain, THREAD); 632 if (probe != NULL) return probe; 633 634 635 // Non-bootstrap class loaders will call out to class loader and 636 // define via jvm/jni_DefineClass which will acquire the 637 // class loader object lock to protect against multiple threads 638 // defining the class in parallel by accident. 639 // This lock must be acquired here so the waiter will find 640 // any successful result in the SystemDictionary and not attempt 641 // the define 642 // ParallelCapable Classloaders and the bootstrap classloader, 643 // or all classloaders with UnsyncloadClass do not acquire lock here 644 bool DoObjectLock = true; 645 if (is_parallelCapable(class_loader)) { 646 DoObjectLock = false; 647 } 648 649 unsigned int p_hash = placeholders()->compute_hash(name, loader_data); 650 int p_index = placeholders()->hash_to_index(p_hash); 651 652 // Class is not in SystemDictionary so we have to do loading. 653 // Make sure we are synchronized on the class loader before we proceed 654 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 655 check_loader_lock_contention(lockObject, THREAD); 656 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 657 658 // Check again (after locking) if class already exist in SystemDictionary 659 bool class_has_been_loaded = false; 660 bool super_load_in_progress = false; 661 bool havesupername = false; 662 instanceKlassHandle k; 663 PlaceholderEntry* placeholder; 664 Symbol* superclassname = NULL; 665 666 { 667 MutexLocker mu(SystemDictionary_lock, THREAD); 668 Klass* check = find_class(d_index, d_hash, name, loader_data); 669 if (check != NULL) { 670 // Klass is already loaded, so just return it 671 class_has_been_loaded = true; 672 k = instanceKlassHandle(THREAD, check); 673 } else { 674 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 675 if (placeholder && placeholder->super_load_in_progress()) { 676 super_load_in_progress = true; 677 if (placeholder->havesupername() == true) { 678 superclassname = placeholder->supername(); 679 havesupername = true; 680 } 681 } 682 } 683 } 684 685 // If the class is in the placeholder table, class loading is in progress 686 if (super_load_in_progress && havesupername==true) { 687 k = SystemDictionary::handle_parallel_super_load(name, superclassname, 688 class_loader, protection_domain, lockObject, THREAD); 689 if (HAS_PENDING_EXCEPTION) { 690 return NULL; 691 } 692 if (!k.is_null()) { 693 class_has_been_loaded = true; 694 } 695 } 696 697 bool throw_circularity_error = false; 698 if (!class_has_been_loaded) { 699 bool load_instance_added = false; 700 701 // add placeholder entry to record loading instance class 702 // Five cases: 703 // All cases need to prevent modifying bootclasssearchpath 704 // in parallel with a classload of same classname 705 // Redefineclasses uses existence of the placeholder for the duration 706 // of the class load to prevent concurrent redefinition of not completely 707 // defined classes. 708 // case 1. traditional classloaders that rely on the classloader object lock 709 // - no other need for LOAD_INSTANCE 710 // case 2. traditional classloaders that break the classloader object lock 711 // as a deadlock workaround. Detection of this case requires that 712 // this check is done while holding the classloader object lock, 713 // and that lock is still held when calling classloader's loadClass. 714 // For these classloaders, we ensure that the first requestor 715 // completes the load and other requestors wait for completion. 716 // case 3. UnsyncloadClass - don't use objectLocker 717 // With this flag, we allow parallel classloading of a 718 // class/classloader pair 719 // case4. Bootstrap classloader - don't own objectLocker 720 // This classloader supports parallelism at the classloader level, 721 // but only allows a single load of a class/classloader pair. 722 // No performance benefit and no deadlock issues. 723 // case 5. parallelCapable user level classloaders - without objectLocker 724 // Allow parallel classloading of a class/classloader pair 725 726 { 727 MutexLocker mu(SystemDictionary_lock, THREAD); 728 if (class_loader.is_null() || !is_parallelCapable(class_loader)) { 729 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 730 if (oldprobe) { 731 // only need check_seen_thread once, not on each loop 732 // 6341374 java/lang/Instrument with -Xcomp 733 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) { 734 throw_circularity_error = true; 735 } else { 736 // case 1: traditional: should never see load_in_progress. 737 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) { 738 739 // case 4: bootstrap classloader: prevent futile classloading, 740 // wait on first requestor 741 if (class_loader.is_null()) { 742 SystemDictionary_lock->wait(); 743 } else { 744 // case 2: traditional with broken classloader lock. wait on first 745 // requestor. 746 double_lock_wait(lockObject, THREAD); 747 } 748 // Check if classloading completed while we were waiting 749 Klass* check = find_class(d_index, d_hash, name, loader_data); 750 if (check != NULL) { 751 // Klass is already loaded, so just return it 752 k = instanceKlassHandle(THREAD, check); 753 class_has_been_loaded = true; 754 } 755 // check if other thread failed to load and cleaned up 756 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 757 } 758 } 759 } 760 } 761 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock 762 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try 763 // LOAD_INSTANCE in parallel 764 765 if (!throw_circularity_error && !class_has_been_loaded) { 766 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD); 767 load_instance_added = true; 768 // For class loaders that do not acquire the classloader object lock, 769 // if they did not catch another thread holding LOAD_INSTANCE, 770 // need a check analogous to the acquire ObjectLocker/find_class 771 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL 772 // one final check if the load has already completed 773 // class loaders holding the ObjectLock shouldn't find the class here 774 Klass* check = find_class(d_index, d_hash, name, loader_data); 775 if (check != NULL) { 776 // Klass is already loaded, so return it after checking/adding protection domain 777 k = instanceKlassHandle(THREAD, check); 778 class_has_been_loaded = true; 779 } 780 } 781 } 782 783 // must throw error outside of owning lock 784 if (throw_circularity_error) { 785 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup"); 786 ResourceMark rm(THREAD); 787 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string()); 788 } 789 790 if (!class_has_been_loaded) { 791 792 // Do actual loading 793 k = load_instance_class(name, class_loader, THREAD); 794 795 // For UnsyncloadClass only 796 // If they got a linkageError, check if a parallel class load succeeded. 797 // If it did, then for bytecode resolution the specification requires 798 // that we return the same result we did for the other thread, i.e. the 799 // successfully loaded InstanceKlass 800 // Should not get here for classloaders that support parallelism 801 // with the new cleaner mechanism, even with AllowParallelDefineClass 802 // Bootstrap goes through here to allow for an extra guarantee check 803 if (UnsyncloadClass || (class_loader.is_null())) { 804 if (k.is_null() && HAS_PENDING_EXCEPTION 805 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) { 806 MutexLocker mu(SystemDictionary_lock, THREAD); 807 Klass* check = find_class(d_index, d_hash, name, loader_data); 808 if (check != NULL) { 809 // Klass is already loaded, so just use it 810 k = instanceKlassHandle(THREAD, check); 811 CLEAR_PENDING_EXCEPTION; 812 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?"); 813 } 814 } 815 } 816 817 // If everything was OK (no exceptions, no null return value), and 818 // class_loader is NOT the defining loader, do a little more bookkeeping. 819 if (!HAS_PENDING_EXCEPTION && !k.is_null() && 820 k->class_loader() != class_loader()) { 821 822 check_constraints(d_index, d_hash, k, class_loader, false, THREAD); 823 824 // Need to check for a PENDING_EXCEPTION again; check_constraints 825 // can throw and doesn't use the CHECK macro. 826 if (!HAS_PENDING_EXCEPTION) { 827 { // Grabbing the Compile_lock prevents systemDictionary updates 828 // during compilations. 829 MutexLocker mu(Compile_lock, THREAD); 830 update_dictionary(d_index, d_hash, p_index, p_hash, 831 k, class_loader, THREAD); 832 } 833 834 if (JvmtiExport::should_post_class_load()) { 835 Thread *thread = THREAD; 836 assert(thread->is_Java_thread(), "thread->is_Java_thread()"); 837 JvmtiExport::post_class_load((JavaThread *) thread, k()); 838 } 839 } 840 } 841 } // load_instance_class loop 842 843 if (load_instance_added == true) { 844 // clean up placeholder entries for LOAD_INSTANCE success or error 845 // This brackets the SystemDictionary updates for both defining 846 // and initiating loaders 847 MutexLocker mu(SystemDictionary_lock, THREAD); 848 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD); 849 SystemDictionary_lock->notify_all(); 850 } 851 } 852 853 if (HAS_PENDING_EXCEPTION || k.is_null()) { 854 return NULL; 855 } 856 857 post_class_load_event(class_load_start_time, k, class_loader); 858 859 #ifdef ASSERT 860 { 861 ClassLoaderData* loader_data = k->class_loader_data(); 862 MutexLocker mu(SystemDictionary_lock, THREAD); 863 Klass* kk = find_class(name, loader_data); 864 assert(kk == k(), "should be present in dictionary"); 865 } 866 #endif 867 868 // return if the protection domain in NULL 869 if (protection_domain() == NULL) return k(); 870 871 // Check the protection domain has the right access 872 { 873 MutexLocker mu(SystemDictionary_lock, THREAD); 874 // Note that we have an entry, and entries can be deleted only during GC, 875 // so we cannot allow GC to occur while we're holding this entry. 876 // We're using a No_Safepoint_Verifier to catch any place where we 877 // might potentially do a GC at all. 878 // Dictionary::do_unloading() asserts that classes in SD are only 879 // unloaded at a safepoint. Anonymous classes are not in SD. 880 No_Safepoint_Verifier nosafepoint; 881 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name, 882 loader_data, 883 protection_domain)) { 884 return k(); 885 } 886 } 887 888 // Verify protection domain. If it fails an exception is thrown 889 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL); 890 891 return k(); 892 } 893 894 895 // This routine does not lock the system dictionary. 896 // 897 // Since readers don't hold a lock, we must make sure that system 898 // dictionary entries are only removed at a safepoint (when only one 899 // thread is running), and are added to in a safe way (all links must 900 // be updated in an MT-safe manner). 901 // 902 // Callers should be aware that an entry could be added just after 903 // _dictionary->bucket(index) is read here, so the caller will not see 904 // the new entry. 905 906 Klass* SystemDictionary::find(Symbol* class_name, 907 Handle class_loader, 908 Handle protection_domain, 909 TRAPS) { 910 911 // The result of this call should be consistent with the result 912 // of the call to resolve_instance_class_or_null(). 913 // See evaluation 6790209 and 4474172 for more details. 914 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 915 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader()); 916 917 if (loader_data == NULL) { 918 // If the ClassLoaderData has not been setup, 919 // then the class loader has no entries in the dictionary. 920 return NULL; 921 } 922 923 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data); 924 int d_index = dictionary()->hash_to_index(d_hash); 925 926 { 927 // Note that we have an entry, and entries can be deleted only during GC, 928 // so we cannot allow GC to occur while we're holding this entry. 929 // We're using a No_Safepoint_Verifier to catch any place where we 930 // might potentially do a GC at all. 931 // Dictionary::do_unloading() asserts that classes in SD are only 932 // unloaded at a safepoint. Anonymous classes are not in SD. 933 No_Safepoint_Verifier nosafepoint; 934 return dictionary()->find(d_index, d_hash, class_name, loader_data, 935 protection_domain, THREAD); 936 } 937 } 938 939 940 // Look for a loaded instance or array klass by name. Do not do any loading. 941 // return NULL in case of error. 942 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name, 943 Handle class_loader, 944 Handle protection_domain, 945 TRAPS) { 946 Klass* k = NULL; 947 assert(class_name != NULL, "class name must be non NULL"); 948 949 if (FieldType::is_array(class_name)) { 950 // The name refers to an array. Parse the name. 951 // dimension and object_key in FieldArrayInfo are assigned as a 952 // side-effect of this call 953 FieldArrayInfo fd; 954 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL)); 955 if (t != T_OBJECT) { 956 k = Universe::typeArrayKlassObj(t); 957 } else { 958 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD); 959 } 960 if (k != NULL) { 961 k = k->array_klass_or_null(fd.dimension()); 962 } 963 } else { 964 k = find(class_name, class_loader, protection_domain, THREAD); 965 } 966 return k; 967 } 968 969 // Note: this method is much like resolve_from_stream, but 970 // updates no supplemental data structures. 971 // TODO consolidate the two methods with a helper routine? 972 Klass* SystemDictionary::parse_stream(Symbol* class_name, 973 Handle class_loader, 974 Handle protection_domain, 975 ClassFileStream* st, 976 KlassHandle host_klass, 977 GrowableArray<Handle>* cp_patches, 978 TRAPS) { 979 TempNewSymbol parsed_name = NULL; 980 981 Ticks class_load_start_time = Ticks::now(); 982 983 ClassLoaderData* loader_data; 984 if (host_klass.not_null()) { 985 // Create a new CLD for anonymous class, that uses the same class loader 986 // as the host_klass 987 guarantee(host_klass->class_loader() == class_loader(), "should be the same"); 988 guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping"); 989 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL); 990 loader_data->record_dependency(host_klass(), CHECK_NULL); 991 } else { 992 loader_data = ClassLoaderData::class_loader_data(class_loader()); 993 } 994 995 // Parse the stream. Note that we do this even though this klass might 996 // already be present in the SystemDictionary, otherwise we would not 997 // throw potential ClassFormatErrors. 998 // 999 // Note: "name" is updated. 1000 1001 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name, 1002 loader_data, 1003 protection_domain, 1004 host_klass, 1005 cp_patches, 1006 parsed_name, 1007 true, 1008 THREAD); 1009 1010 1011 if (host_klass.not_null() && k.not_null()) { 1012 // If it's anonymous, initialize it now, since nobody else will. 1013 1014 { 1015 MutexLocker mu_r(Compile_lock, THREAD); 1016 1017 // Add to class hierarchy, initialize vtables, and do possible 1018 // deoptimizations. 1019 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block 1020 1021 // But, do not add to system dictionary. 1022 1023 // compiled code dependencies need to be validated anyway 1024 notice_modification(); 1025 } 1026 1027 // Rewrite and patch constant pool here. 1028 k->link_class(CHECK_NULL); 1029 if (cp_patches != NULL) { 1030 k->constants()->patch_resolved_references(cp_patches); 1031 } 1032 k->eager_initialize(CHECK_NULL); 1033 1034 // notify jvmti 1035 if (JvmtiExport::should_post_class_load()) { 1036 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1037 JvmtiExport::post_class_load((JavaThread *) THREAD, k()); 1038 } 1039 1040 post_class_load_event(class_load_start_time, k, class_loader); 1041 } 1042 assert(host_klass.not_null() || cp_patches == NULL, 1043 "cp_patches only found with host_klass"); 1044 1045 return k(); 1046 } 1047 1048 // Add a klass to the system from a stream (called by jni_DefineClass and 1049 // JVM_DefineClass). 1050 // Note: class_name can be NULL. In that case we do not know the name of 1051 // the class until we have parsed the stream. 1052 1053 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name, 1054 Handle class_loader, 1055 Handle protection_domain, 1056 ClassFileStream* st, 1057 bool verify, 1058 TRAPS) { 1059 1060 // Classloaders that support parallelism, e.g. bootstrap classloader, 1061 // or all classloaders with UnsyncloadClass do not acquire lock here 1062 bool DoObjectLock = true; 1063 if (is_parallelCapable(class_loader)) { 1064 DoObjectLock = false; 1065 } 1066 1067 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL); 1068 1069 // Make sure we are synchronized on the class loader before we proceed 1070 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1071 check_loader_lock_contention(lockObject, THREAD); 1072 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 1073 1074 TempNewSymbol parsed_name = NULL; 1075 1076 // Parse the stream. Note that we do this even though this klass might 1077 // already be present in the SystemDictionary, otherwise we would not 1078 // throw potential ClassFormatErrors. 1079 // 1080 // Note: "name" is updated. 1081 1082 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name, 1083 loader_data, 1084 protection_domain, 1085 parsed_name, 1086 verify, 1087 THREAD); 1088 1089 const char* pkg = "java/"; 1090 if (!HAS_PENDING_EXCEPTION && 1091 !class_loader.is_null() && 1092 parsed_name != NULL && 1093 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) { 1094 // It is illegal to define classes in the "java." package from 1095 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader 1096 ResourceMark rm(THREAD); 1097 char* name = parsed_name->as_C_string(); 1098 char* index = strrchr(name, '/'); 1099 *index = '\0'; // chop to just the package name 1100 while ((index = strchr(name, '/')) != NULL) { 1101 *index = '.'; // replace '/' with '.' in package name 1102 } 1103 const char* fmt = "Prohibited package name: %s"; 1104 size_t len = strlen(fmt) + strlen(name); 1105 char* message = NEW_RESOURCE_ARRAY(char, len); 1106 jio_snprintf(message, len, fmt, name); 1107 Exceptions::_throw_msg(THREAD_AND_LOCATION, 1108 vmSymbols::java_lang_SecurityException(), message); 1109 } 1110 1111 if (!HAS_PENDING_EXCEPTION) { 1112 assert(parsed_name != NULL, "Sanity"); 1113 assert(class_name == NULL || class_name == parsed_name, "name mismatch"); 1114 // Verification prevents us from creating names with dots in them, this 1115 // asserts that that's the case. 1116 assert(is_internal_format(parsed_name), 1117 "external class name format used internally"); 1118 1119 // Add class just loaded 1120 // If a class loader supports parallel classloading handle parallel define requests 1121 // find_or_define_instance_class may return a different InstanceKlass 1122 if (is_parallelCapable(class_loader)) { 1123 k = find_or_define_instance_class(class_name, class_loader, k, THREAD); 1124 } else { 1125 define_instance_class(k, THREAD); 1126 } 1127 } 1128 1129 // Make sure we have an entry in the SystemDictionary on success 1130 debug_only( { 1131 if (!HAS_PENDING_EXCEPTION) { 1132 assert(parsed_name != NULL, "parsed_name is still null?"); 1133 Symbol* h_name = k->name(); 1134 ClassLoaderData *defining_loader_data = k->class_loader_data(); 1135 1136 MutexLocker mu(SystemDictionary_lock, THREAD); 1137 1138 Klass* check = find_class(parsed_name, loader_data); 1139 assert(check == k(), "should be present in the dictionary"); 1140 1141 Klass* check2 = find_class(h_name, defining_loader_data); 1142 assert(check == check2, "name inconsistancy in SystemDictionary"); 1143 } 1144 } ); 1145 1146 return k(); 1147 } 1148 1149 #if INCLUDE_CDS 1150 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length, 1151 int number_of_entries) { 1152 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>), 1153 "bad shared dictionary size."); 1154 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries); 1155 } 1156 1157 1158 // If there is a shared dictionary, then find the entry for the 1159 // given shared system class, if any. 1160 1161 Klass* SystemDictionary::find_shared_class(Symbol* class_name) { 1162 if (shared_dictionary() != NULL) { 1163 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL); 1164 int d_index = shared_dictionary()->hash_to_index(d_hash); 1165 1166 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name); 1167 } else { 1168 return NULL; 1169 } 1170 } 1171 1172 1173 // Load a class from the shared spaces (found through the shared system 1174 // dictionary). Force the superclass and all interfaces to be loaded. 1175 // Update the class definition to include sibling classes and no 1176 // subclasses (yet). [Classes in the shared space are not part of the 1177 // object hierarchy until loaded.] 1178 1179 instanceKlassHandle SystemDictionary::load_shared_class( 1180 Symbol* class_name, Handle class_loader, TRAPS) { 1181 instanceKlassHandle ik (THREAD, find_shared_class(class_name)); 1182 // Make sure we only return the boot class for the NULL classloader. 1183 if (ik.not_null() && 1184 SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) { 1185 Handle protection_domain; 1186 return load_shared_class(ik, class_loader, protection_domain, THREAD); 1187 } 1188 return instanceKlassHandle(); 1189 } 1190 1191 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik, 1192 Handle class_loader, 1193 Handle protection_domain, TRAPS) { 1194 if (ik.not_null()) { 1195 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1196 Symbol* class_name = ik->name(); 1197 1198 // Found the class, now load the superclass and interfaces. If they 1199 // are shared, add them to the main system dictionary and reset 1200 // their hierarchy references (supers, subs, and interfaces). 1201 1202 if (ik->super() != NULL) { 1203 Symbol* cn = ik->super()->name(); 1204 resolve_super_or_fail(class_name, cn, 1205 class_loader, protection_domain, true, CHECK_(nh)); 1206 } 1207 1208 Array<Klass*>* interfaces = ik->local_interfaces(); 1209 int num_interfaces = interfaces->length(); 1210 for (int index = 0; index < num_interfaces; index++) { 1211 Klass* k = interfaces->at(index); 1212 1213 // Note: can not use InstanceKlass::cast here because 1214 // interfaces' InstanceKlass's C++ vtbls haven't been 1215 // reinitialized yet (they will be once the interface classes 1216 // are loaded) 1217 Symbol* name = k->name(); 1218 resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh)); 1219 } 1220 1221 // Adjust methods to recover missing data. They need addresses for 1222 // interpreter entry points and their default native method address 1223 // must be reset. 1224 1225 // Updating methods must be done under a lock so multiple 1226 // threads don't update these in parallel 1227 // 1228 // Shared classes are all currently loaded by either the bootstrap or 1229 // internal parallel class loaders, so this will never cause a deadlock 1230 // on a custom class loader lock. 1231 1232 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader()); 1233 { 1234 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1235 check_loader_lock_contention(lockObject, THREAD); 1236 ObjectLocker ol(lockObject, THREAD, true); 1237 ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh)); 1238 } 1239 1240 if (TraceClassLoading) { 1241 ResourceMark rm; 1242 tty->print("[Loaded %s", ik->external_name()); 1243 tty->print(" from shared objects file"); 1244 if (class_loader.not_null()) { 1245 tty->print(" by %s", loader_data->loader_name()); 1246 } 1247 tty->print_cr("]"); 1248 } 1249 1250 if (DumpLoadedClassList != NULL && classlist_file->is_open()) { 1251 // Only dump the classes that can be stored into CDS archive 1252 if (SystemDictionaryShared::is_sharing_possible(loader_data)) { 1253 ResourceMark rm(THREAD); 1254 classlist_file->print_cr("%s", ik->name()->as_C_string()); 1255 classlist_file->flush(); 1256 } 1257 } 1258 1259 // notify a class loaded from shared object 1260 ClassLoadingService::notify_class_loaded(InstanceKlass::cast(ik()), 1261 true /* shared class */); 1262 } 1263 return ik; 1264 } 1265 #endif // INCLUDE_CDS 1266 1267 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) { 1268 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1269 if (class_loader.is_null()) { 1270 1271 // Search the shared system dictionary for classes preloaded into the 1272 // shared spaces. 1273 instanceKlassHandle k; 1274 { 1275 #if INCLUDE_CDS 1276 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time()); 1277 k = load_shared_class(class_name, class_loader, THREAD); 1278 #endif 1279 } 1280 1281 if (k.is_null()) { 1282 // Use VM class loader 1283 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time()); 1284 k = ClassLoader::load_classfile(class_name, CHECK_(nh)); 1285 } 1286 1287 // find_or_define_instance_class may return a different InstanceKlass 1288 if (!k.is_null()) { 1289 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh)); 1290 } 1291 return k; 1292 } else { 1293 // Use user specified class loader to load class. Call loadClass operation on class_loader. 1294 ResourceMark rm(THREAD); 1295 1296 assert(THREAD->is_Java_thread(), "must be a JavaThread"); 1297 JavaThread* jt = (JavaThread*) THREAD; 1298 1299 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(), 1300 ClassLoader::perf_app_classload_selftime(), 1301 ClassLoader::perf_app_classload_count(), 1302 jt->get_thread_stat()->perf_recursion_counts_addr(), 1303 jt->get_thread_stat()->perf_timers_addr(), 1304 PerfClassTraceTime::CLASS_LOAD); 1305 1306 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh)); 1307 // Translate to external class name format, i.e., convert '/' chars to '.' 1308 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh)); 1309 1310 JavaValue result(T_OBJECT); 1311 1312 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass()); 1313 1314 // Call public unsynchronized loadClass(String) directly for all class loaders 1315 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will 1316 // acquire a class-name based lock rather than the class loader object lock. 1317 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean), 1318 // so the call to loadClassInternal() was not required. 1319 // 1320 // UnsyncloadClass flag means both call loadClass(String) and do 1321 // not acquire the class loader lock even for class loaders that are 1322 // not parallelCapable. This was a risky transitional 1323 // flag for diagnostic purposes only. It is risky to call 1324 // custom class loaders without synchronization. 1325 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of 1326 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field. 1327 // Do NOT assume this will be supported in future releases. 1328 // 1329 // Added MustCallLoadClassInternal in case we discover in the field 1330 // a customer that counts on this call 1331 if (MustCallLoadClassInternal && has_loadClassInternal()) { 1332 JavaCalls::call_special(&result, 1333 class_loader, 1334 spec_klass, 1335 vmSymbols::loadClassInternal_name(), 1336 vmSymbols::string_class_signature(), 1337 string, 1338 CHECK_(nh)); 1339 } else { 1340 JavaCalls::call_virtual(&result, 1341 class_loader, 1342 spec_klass, 1343 vmSymbols::loadClass_name(), 1344 vmSymbols::string_class_signature(), 1345 string, 1346 CHECK_(nh)); 1347 } 1348 1349 assert(result.get_type() == T_OBJECT, "just checking"); 1350 oop obj = (oop) result.get_jobject(); 1351 1352 // Primitive classes return null since forName() can not be 1353 // used to obtain any of the Class objects representing primitives or void 1354 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) { 1355 instanceKlassHandle k = 1356 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj)); 1357 // For user defined Java class loaders, check that the name returned is 1358 // the same as that requested. This check is done for the bootstrap 1359 // loader when parsing the class file. 1360 if (class_name == k->name()) { 1361 return k; 1362 } 1363 } 1364 // Class is not found or has the wrong name, return NULL 1365 return nh; 1366 } 1367 } 1368 1369 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) { 1370 1371 ClassLoaderData* loader_data = k->class_loader_data(); 1372 Handle class_loader_h(THREAD, loader_data->class_loader()); 1373 1374 // for bootstrap and other parallel classloaders don't acquire lock, 1375 // use placeholder token 1376 // If a parallelCapable class loader calls define_instance_class instead of 1377 // find_or_define_instance_class to get here, we have a timing 1378 // hole with systemDictionary updates and check_constraints 1379 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) { 1380 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, 1381 compute_loader_lock_object(class_loader_h, THREAD)), 1382 "define called without lock"); 1383 } 1384 1385 // Check class-loading constraints. Throw exception if violation is detected. 1386 // Grabs and releases SystemDictionary_lock 1387 // The check_constraints/find_class call and update_dictionary sequence 1388 // must be "atomic" for a specific class/classloader pair so we never 1389 // define two different instanceKlasses for that class/classloader pair. 1390 // Existing classloaders will call define_instance_class with the 1391 // classloader lock held 1392 // Parallel classloaders will call find_or_define_instance_class 1393 // which will require a token to perform the define class 1394 Symbol* name_h = k->name(); 1395 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data); 1396 int d_index = dictionary()->hash_to_index(d_hash); 1397 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK); 1398 1399 // Register class just loaded with class loader (placed in Vector) 1400 // Note we do this before updating the dictionary, as this can 1401 // fail with an OutOfMemoryError (if it does, we will *not* put this 1402 // class in the dictionary and will not update the class hierarchy). 1403 // JVMTI FollowReferences needs to find the classes this way. 1404 if (k->class_loader() != NULL) { 1405 methodHandle m(THREAD, Universe::loader_addClass_method()); 1406 JavaValue result(T_VOID); 1407 JavaCallArguments args(class_loader_h); 1408 args.push_oop(Handle(THREAD, k->java_mirror())); 1409 JavaCalls::call(&result, m, &args, CHECK); 1410 } 1411 1412 // Add the new class. We need recompile lock during update of CHA. 1413 { 1414 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data); 1415 int p_index = placeholders()->hash_to_index(p_hash); 1416 1417 MutexLocker mu_r(Compile_lock, THREAD); 1418 1419 // Add to class hierarchy, initialize vtables, and do possible 1420 // deoptimizations. 1421 add_to_hierarchy(k, CHECK); // No exception, but can block 1422 1423 // Add to systemDictionary - so other classes can see it. 1424 // Grabs and releases SystemDictionary_lock 1425 update_dictionary(d_index, d_hash, p_index, p_hash, 1426 k, class_loader_h, THREAD); 1427 } 1428 k->eager_initialize(THREAD); 1429 1430 // notify jvmti 1431 if (JvmtiExport::should_post_class_load()) { 1432 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1433 JvmtiExport::post_class_load((JavaThread *) THREAD, k()); 1434 1435 } 1436 1437 } 1438 1439 // Support parallel classloading 1440 // All parallel class loaders, including bootstrap classloader 1441 // lock a placeholder entry for this class/class_loader pair 1442 // to allow parallel defines of different classes for this class loader 1443 // With AllowParallelDefine flag==true, in case they do not synchronize around 1444 // FindLoadedClass/DefineClass, calls, we check for parallel 1445 // loading for them, wait if a defineClass is in progress 1446 // and return the initial requestor's results 1447 // This flag does not apply to the bootstrap classloader. 1448 // With AllowParallelDefine flag==false, call through to define_instance_class 1449 // which will throw LinkageError: duplicate class definition. 1450 // False is the requested default. 1451 // For better performance, the class loaders should synchronize 1452 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they 1453 // potentially waste time reading and parsing the bytestream. 1454 // Note: VM callers should ensure consistency of k/class_name,class_loader 1455 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) { 1456 1457 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1458 Symbol* name_h = k->name(); // passed in class_name may be null 1459 ClassLoaderData* loader_data = class_loader_data(class_loader); 1460 1461 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data); 1462 int d_index = dictionary()->hash_to_index(d_hash); 1463 1464 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS 1465 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data); 1466 int p_index = placeholders()->hash_to_index(p_hash); 1467 PlaceholderEntry* probe; 1468 1469 { 1470 MutexLocker mu(SystemDictionary_lock, THREAD); 1471 // First check if class already defined 1472 if (UnsyncloadClass || (is_parallelDefine(class_loader))) { 1473 Klass* check = find_class(d_index, d_hash, name_h, loader_data); 1474 if (check != NULL) { 1475 return(instanceKlassHandle(THREAD, check)); 1476 } 1477 } 1478 1479 // Acquire define token for this class/classloader 1480 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD); 1481 // Wait if another thread defining in parallel 1482 // All threads wait - even those that will throw duplicate class: otherwise 1483 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails 1484 // if other thread has not finished updating dictionary 1485 while (probe->definer() != NULL) { 1486 SystemDictionary_lock->wait(); 1487 } 1488 // Only special cases allow parallel defines and can use other thread's results 1489 // Other cases fall through, and may run into duplicate defines 1490 // caught by finding an entry in the SystemDictionary 1491 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) { 1492 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1493 SystemDictionary_lock->notify_all(); 1494 #ifdef ASSERT 1495 Klass* check = find_class(d_index, d_hash, name_h, loader_data); 1496 assert(check != NULL, "definer missed recording success"); 1497 #endif 1498 return(instanceKlassHandle(THREAD, probe->instance_klass())); 1499 } else { 1500 // This thread will define the class (even if earlier thread tried and had an error) 1501 probe->set_definer(THREAD); 1502 } 1503 } 1504 1505 define_instance_class(k, THREAD); 1506 1507 Handle linkage_exception = Handle(); // null handle 1508 1509 // definer must notify any waiting threads 1510 { 1511 MutexLocker mu(SystemDictionary_lock, THREAD); 1512 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data); 1513 assert(probe != NULL, "DEFINE_CLASS placeholder lost?"); 1514 if (probe != NULL) { 1515 if (HAS_PENDING_EXCEPTION) { 1516 linkage_exception = Handle(THREAD,PENDING_EXCEPTION); 1517 CLEAR_PENDING_EXCEPTION; 1518 } else { 1519 probe->set_instance_klass(k()); 1520 } 1521 probe->set_definer(NULL); 1522 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1523 SystemDictionary_lock->notify_all(); 1524 } 1525 } 1526 1527 // Can't throw exception while holding lock due to rank ordering 1528 if (linkage_exception() != NULL) { 1529 THROW_OOP_(linkage_exception(), nh); // throws exception and returns 1530 } 1531 1532 return k; 1533 } 1534 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) { 1535 // If class_loader is NULL we synchronize on _system_loader_lock_obj 1536 if (class_loader.is_null()) { 1537 return Handle(THREAD, _system_loader_lock_obj); 1538 } else { 1539 return class_loader; 1540 } 1541 } 1542 1543 // This method is added to check how often we have to wait to grab loader 1544 // lock. The results are being recorded in the performance counters defined in 1545 // ClassLoader::_sync_systemLoaderLockContentionRate and 1546 // ClassLoader::_sync_nonSystemLoaderLockConteionRate. 1547 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) { 1548 if (!UsePerfData) { 1549 return; 1550 } 1551 1552 assert(!loader_lock.is_null(), "NULL lock object"); 1553 1554 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock) 1555 == ObjectSynchronizer::owner_other) { 1556 // contention will likely happen, so increment the corresponding 1557 // contention counter. 1558 if (loader_lock() == _system_loader_lock_obj) { 1559 ClassLoader::sync_systemLoaderLockContentionRate()->inc(); 1560 } else { 1561 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc(); 1562 } 1563 } 1564 } 1565 1566 // ---------------------------------------------------------------------------- 1567 // Lookup 1568 1569 Klass* SystemDictionary::find_class(int index, unsigned int hash, 1570 Symbol* class_name, 1571 ClassLoaderData* loader_data) { 1572 assert_locked_or_safepoint(SystemDictionary_lock); 1573 assert (index == dictionary()->index_for(class_name, loader_data), 1574 "incorrect index?"); 1575 1576 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data); 1577 return k; 1578 } 1579 1580 1581 // Basic find on classes in the midst of being loaded 1582 Symbol* SystemDictionary::find_placeholder(Symbol* class_name, 1583 ClassLoaderData* loader_data) { 1584 assert_locked_or_safepoint(SystemDictionary_lock); 1585 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data); 1586 int p_index = placeholders()->hash_to_index(p_hash); 1587 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data); 1588 } 1589 1590 1591 // Used for assertions and verification only 1592 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) { 1593 #ifndef ASSERT 1594 guarantee(VerifyBeforeGC || 1595 VerifyDuringGC || 1596 VerifyBeforeExit || 1597 VerifyDuringStartup || 1598 VerifyAfterGC, "too expensive"); 1599 #endif 1600 assert_locked_or_safepoint(SystemDictionary_lock); 1601 1602 // First look in the loaded class array 1603 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data); 1604 int d_index = dictionary()->hash_to_index(d_hash); 1605 return find_class(d_index, d_hash, class_name, loader_data); 1606 } 1607 1608 1609 // Get the next class in the diictionary. 1610 Klass* SystemDictionary::try_get_next_class() { 1611 return dictionary()->try_get_next_class(); 1612 } 1613 1614 1615 // ---------------------------------------------------------------------------- 1616 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock 1617 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in 1618 // before a new class is used. 1619 1620 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) { 1621 assert(k.not_null(), "just checking"); 1622 assert_locked_or_safepoint(Compile_lock); 1623 1624 // Link into hierachy. Make sure the vtables are initialized before linking into 1625 k->append_to_sibling_list(); // add to superklass/sibling list 1626 k->process_interfaces(THREAD); // handle all "implements" declarations 1627 k->set_init_state(InstanceKlass::loaded); 1628 // Now flush all code that depended on old class hierarchy. 1629 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97) 1630 // Also, first reinitialize vtable because it may have gotten out of synch 1631 // while the new class wasn't connected to the class hierarchy. 1632 CodeCache::flush_dependents_on(k); 1633 } 1634 1635 // ---------------------------------------------------------------------------- 1636 // GC support 1637 1638 // Following roots during mark-sweep is separated in two phases. 1639 // 1640 // The first phase follows preloaded classes and all other system 1641 // classes, since these will never get unloaded anyway. 1642 // 1643 // The second phase removes (unloads) unreachable classes from the 1644 // system dictionary and follows the remaining classes' contents. 1645 1646 void SystemDictionary::always_strong_oops_do(OopClosure* blk) { 1647 roots_oops_do(blk, NULL); 1648 } 1649 1650 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) { 1651 // Follow all system classes and temporary placeholders in dictionary 1652 dictionary()->always_strong_classes_do(closure); 1653 1654 // Placeholders. These represent classes we're actively loading. 1655 placeholders()->classes_do(closure); 1656 } 1657 1658 // Calculate a "good" systemdictionary size based 1659 // on predicted or current loaded classes count 1660 int SystemDictionary::calculate_systemdictionary_size(int classcount) { 1661 int newsize = _old_default_sdsize; 1662 if ((classcount > 0) && !DumpSharedSpaces) { 1663 int desiredsize = classcount/_average_depth_goal; 1664 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1; 1665 newsize = _primelist[++_sdgeneration]) { 1666 if (desiredsize <= newsize) { 1667 break; 1668 } 1669 } 1670 } 1671 return newsize; 1672 } 1673 1674 #ifdef ASSERT 1675 class VerifySDReachableAndLiveClosure : public OopClosure { 1676 private: 1677 BoolObjectClosure* _is_alive; 1678 1679 template <class T> void do_oop_work(T* p) { 1680 oop obj = oopDesc::load_decode_heap_oop(p); 1681 guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live"); 1682 } 1683 1684 public: 1685 VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { } 1686 1687 virtual void do_oop(oop* p) { do_oop_work(p); } 1688 virtual void do_oop(narrowOop* p) { do_oop_work(p); } 1689 }; 1690 #endif 1691 1692 // Assumes classes in the SystemDictionary are only unloaded at a safepoint 1693 // Note: anonymous classes are not in the SD. 1694 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive, 1695 bool clean_previous_versions) { 1696 // First, mark for unload all ClassLoaderData referencing a dead class loader. 1697 bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive, 1698 clean_previous_versions); 1699 if (unloading_occurred) { 1700 dictionary()->do_unloading(); 1701 constraints()->purge_loader_constraints(); 1702 resolution_errors()->purge_resolution_errors(); 1703 } 1704 // Oops referenced by the system dictionary may get unreachable independently 1705 // of the class loader (eg. cached protection domain oops). So we need to 1706 // explicitly unlink them here instead of in Dictionary::do_unloading. 1707 dictionary()->unlink(is_alive); 1708 #ifdef ASSERT 1709 VerifySDReachableAndLiveClosure cl(is_alive); 1710 dictionary()->oops_do(&cl); 1711 #endif 1712 return unloading_occurred; 1713 } 1714 1715 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) { 1716 strong->do_oop(&_java_system_loader); 1717 strong->do_oop(&_system_loader_lock_obj); 1718 CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);) 1719 1720 // Adjust dictionary 1721 dictionary()->roots_oops_do(strong, weak); 1722 1723 // Visit extra methods 1724 invoke_method_table()->oops_do(strong); 1725 } 1726 1727 void SystemDictionary::oops_do(OopClosure* f) { 1728 f->do_oop(&_java_system_loader); 1729 f->do_oop(&_system_loader_lock_obj); 1730 CDS_ONLY(SystemDictionaryShared::oops_do(f);) 1731 1732 // Adjust dictionary 1733 dictionary()->oops_do(f); 1734 1735 // Visit extra methods 1736 invoke_method_table()->oops_do(f); 1737 } 1738 1739 // Extended Class redefinition support. 1740 // If one of these classes is replaced, we need to replace it in these places. 1741 // KlassClosure::do_klass should take the address of a class but we can 1742 // change that later. 1743 void SystemDictionary::preloaded_classes_do(KlassClosure* f) { 1744 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) { 1745 f->do_klass(_well_known_klasses[k]); 1746 } 1747 1748 { 1749 for (int i = 0; i < T_VOID+1; i++) { 1750 if (_box_klasses[i] != NULL) { 1751 assert(i >= T_BOOLEAN, "checking"); 1752 f->do_klass(_box_klasses[i]); 1753 } 1754 } 1755 } 1756 1757 FilteredFieldsMap::classes_do(f); 1758 } 1759 1760 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) { 1761 f->do_klass(_abstract_ownable_synchronizer_klass); 1762 } 1763 1764 // Just the classes from defining class loaders 1765 // Don't iterate over placeholders 1766 void SystemDictionary::classes_do(void f(Klass*)) { 1767 dictionary()->classes_do(f); 1768 } 1769 1770 // Added for initialize_itable_for_klass 1771 // Just the classes from defining class loaders 1772 // Don't iterate over placeholders 1773 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) { 1774 dictionary()->classes_do(f, CHECK); 1775 } 1776 1777 // All classes, and their class loaders 1778 // Don't iterate over placeholders 1779 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) { 1780 dictionary()->classes_do(f); 1781 } 1782 1783 void SystemDictionary::placeholders_do(void f(Symbol*)) { 1784 placeholders()->entries_do(f); 1785 } 1786 1787 void SystemDictionary::methods_do(void f(Method*)) { 1788 dictionary()->methods_do(f); 1789 invoke_method_table()->methods_do(f); 1790 } 1791 1792 void SystemDictionary::remove_classes_in_error_state() { 1793 dictionary()->remove_classes_in_error_state(); 1794 } 1795 1796 // ---------------------------------------------------------------------------- 1797 // Lazily load klasses 1798 1799 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) { 1800 // if multiple threads calling this function, only one thread will load 1801 // the class. The other threads will find the loaded version once the 1802 // class is loaded. 1803 Klass* aos = _abstract_ownable_synchronizer_klass; 1804 if (aos == NULL) { 1805 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK); 1806 // Force a fence to prevent any read before the write completes 1807 OrderAccess::fence(); 1808 _abstract_ownable_synchronizer_klass = k; 1809 } 1810 } 1811 1812 // ---------------------------------------------------------------------------- 1813 // Initialization 1814 1815 void SystemDictionary::initialize(TRAPS) { 1816 // Allocate arrays 1817 assert(dictionary() == NULL, 1818 "SystemDictionary should only be initialized once"); 1819 _sdgeneration = 0; 1820 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount)); 1821 _placeholders = new PlaceholderTable(_nof_buckets); 1822 _number_of_modifications = 0; 1823 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size); 1824 _resolution_errors = new ResolutionErrorTable(_resolution_error_size); 1825 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size); 1826 1827 // Allocate private object used as system class loader lock 1828 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK); 1829 // Initialize basic classes 1830 initialize_preloaded_classes(CHECK); 1831 } 1832 1833 // Compact table of directions on the initialization of klasses: 1834 static const short wk_init_info[] = { 1835 #define WK_KLASS_INIT_INFO(name, symbol, option) \ 1836 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \ 1837 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \ 1838 | (int)SystemDictionary::option ), 1839 WK_KLASSES_DO(WK_KLASS_INIT_INFO) 1840 #undef WK_KLASS_INIT_INFO 1841 0 1842 }; 1843 1844 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) { 1845 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 1846 int info = wk_init_info[id - FIRST_WKID]; 1847 int sid = (info >> CEIL_LG_OPTION_LIMIT); 1848 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid); 1849 Klass** klassp = &_well_known_klasses[id]; 1850 bool must_load = (init_opt < SystemDictionary::Opt); 1851 if ((*klassp) == NULL) { 1852 if (must_load) { 1853 (*klassp) = resolve_or_fail(symbol, true, CHECK_0); // load required class 1854 } else { 1855 (*klassp) = resolve_or_null(symbol, CHECK_0); // load optional klass 1856 } 1857 } 1858 return ((*klassp) != NULL); 1859 } 1860 1861 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) { 1862 assert((int)start_id <= (int)limit_id, "IDs are out of order!"); 1863 for (int id = (int)start_id; id < (int)limit_id; id++) { 1864 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 1865 int info = wk_init_info[id - FIRST_WKID]; 1866 int sid = (info >> CEIL_LG_OPTION_LIMIT); 1867 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT)); 1868 1869 initialize_wk_klass((WKID)id, opt, CHECK); 1870 } 1871 1872 // move the starting value forward to the limit: 1873 start_id = limit_id; 1874 } 1875 1876 void SystemDictionary::initialize_preloaded_classes(TRAPS) { 1877 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once"); 1878 // Preload commonly used klasses 1879 WKID scan = FIRST_WKID; 1880 // first do Object, then String, Class 1881 if (UseSharedSpaces) { 1882 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK); 1883 // Initialize the constant pool for the Object_class 1884 InstanceKlass* ik = InstanceKlass::cast(Object_klass()); 1885 ik->constants()->restore_unshareable_info(CHECK); 1886 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 1887 } else { 1888 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 1889 } 1890 1891 // Calculate offsets for String and Class classes since they are loaded and 1892 // can be used after this point. 1893 java_lang_String::compute_offsets(); 1894 java_lang_Class::compute_offsets(); 1895 1896 // Fixup mirrors for classes loaded before java.lang.Class. 1897 // These calls iterate over the objects currently in the perm gen 1898 // so calling them at this point is matters (not before when there 1899 // are fewer objects and not later after there are more objects 1900 // in the perm gen. 1901 Universe::initialize_basic_type_mirrors(CHECK); 1902 Universe::fixup_mirrors(CHECK); 1903 1904 // do a bunch more: 1905 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK); 1906 1907 // Preload ref klasses and set reference types 1908 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER); 1909 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass)); 1910 1911 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK); 1912 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT); 1913 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK); 1914 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL); 1915 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM); 1916 InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER); 1917 1918 // JSR 292 classes 1919 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass); 1920 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass); 1921 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK); 1922 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK); 1923 initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK); 1924 1925 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass); 1926 _box_klasses[T_CHAR] = WK_KLASS(Character_klass); 1927 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass); 1928 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass); 1929 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass); 1930 _box_klasses[T_SHORT] = WK_KLASS(Short_klass); 1931 _box_klasses[T_INT] = WK_KLASS(Integer_klass); 1932 _box_klasses[T_LONG] = WK_KLASS(Long_klass); 1933 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass); 1934 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass); 1935 1936 { // Compute whether we should use loadClass or loadClassInternal when loading classes. 1937 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature()); 1938 _has_loadClassInternal = (method != NULL); 1939 } 1940 { // Compute whether we should use checkPackageAccess or NOT 1941 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature()); 1942 _has_checkPackageAccess = (method != NULL); 1943 } 1944 } 1945 1946 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer). 1947 // If so, returns the basic type it holds. If not, returns T_OBJECT. 1948 BasicType SystemDictionary::box_klass_type(Klass* k) { 1949 assert(k != NULL, ""); 1950 for (int i = T_BOOLEAN; i < T_VOID+1; i++) { 1951 if (_box_klasses[i] == k) 1952 return (BasicType)i; 1953 } 1954 return T_OBJECT; 1955 } 1956 1957 // Constraints on class loaders. The details of the algorithm can be 1958 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java 1959 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is 1960 // that the system dictionary needs to maintain a set of contraints that 1961 // must be satisfied by all classes in the dictionary. 1962 // if defining is true, then LinkageError if already in systemDictionary 1963 // if initiating loader, then ok if InstanceKlass matches existing entry 1964 1965 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash, 1966 instanceKlassHandle k, 1967 Handle class_loader, bool defining, 1968 TRAPS) { 1969 const char *linkage_error = NULL; 1970 { 1971 Symbol* name = k->name(); 1972 ClassLoaderData *loader_data = class_loader_data(class_loader); 1973 1974 MutexLocker mu(SystemDictionary_lock, THREAD); 1975 1976 Klass* check = find_class(d_index, d_hash, name, loader_data); 1977 if (check != (Klass*)NULL) { 1978 // if different InstanceKlass - duplicate class definition, 1979 // else - ok, class loaded by a different thread in parallel, 1980 // we should only have found it if it was done loading and ok to use 1981 // system dictionary only holds instance classes, placeholders 1982 // also holds array classes 1983 1984 assert(check->oop_is_instance(), "noninstance in systemdictionary"); 1985 if ((defining == true) || (k() != check)) { 1986 linkage_error = "loader (instance of %s): attempted duplicate class " 1987 "definition for name: \"%s\""; 1988 } else { 1989 return; 1990 } 1991 } 1992 1993 #ifdef ASSERT 1994 Symbol* ph_check = find_placeholder(name, loader_data); 1995 assert(ph_check == NULL || ph_check == name, "invalid symbol"); 1996 #endif 1997 1998 if (linkage_error == NULL) { 1999 if (constraints()->check_or_update(k, class_loader, name) == false) { 2000 linkage_error = "loader constraint violation: loader (instance of %s)" 2001 " previously initiated loading for a different type with name \"%s\""; 2002 } 2003 } 2004 } 2005 2006 // Throw error now if needed (cannot throw while holding 2007 // SystemDictionary_lock because of rank ordering) 2008 2009 if (linkage_error) { 2010 ResourceMark rm(THREAD); 2011 const char* class_loader_name = loader_name(class_loader()); 2012 char* type_name = k->name()->as_C_string(); 2013 size_t buflen = strlen(linkage_error) + strlen(class_loader_name) + 2014 strlen(type_name); 2015 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 2016 jio_snprintf(buf, buflen, linkage_error, class_loader_name, type_name); 2017 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 2018 } 2019 } 2020 2021 2022 // Update system dictionary - done after check_constraint and add_to_hierachy 2023 // have been called. 2024 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash, 2025 int p_index, unsigned int p_hash, 2026 instanceKlassHandle k, 2027 Handle class_loader, 2028 TRAPS) { 2029 // Compile_lock prevents systemDictionary updates during compilations 2030 assert_locked_or_safepoint(Compile_lock); 2031 Symbol* name = k->name(); 2032 ClassLoaderData *loader_data = class_loader_data(class_loader); 2033 2034 { 2035 MutexLocker mu1(SystemDictionary_lock, THREAD); 2036 2037 // See whether biased locking is enabled and if so set it for this 2038 // klass. 2039 // Note that this must be done past the last potential blocking 2040 // point / safepoint. We enable biased locking lazily using a 2041 // VM_Operation to iterate the SystemDictionary and installing the 2042 // biasable mark word into each InstanceKlass's prototype header. 2043 // To avoid race conditions where we accidentally miss enabling the 2044 // optimization for one class in the process of being added to the 2045 // dictionary, we must not safepoint after the test of 2046 // BiasedLocking::enabled(). 2047 if (UseBiasedLocking && BiasedLocking::enabled()) { 2048 // Set biased locking bit for all loaded classes; it will be 2049 // cleared if revocation occurs too often for this type 2050 // NOTE that we must only do this when the class is initally 2051 // defined, not each time it is referenced from a new class loader 2052 if (k->class_loader() == class_loader()) { 2053 k->set_prototype_header(markOopDesc::biased_locking_prototype()); 2054 } 2055 } 2056 2057 // Make a new system dictionary entry. 2058 Klass* sd_check = find_class(d_index, d_hash, name, loader_data); 2059 if (sd_check == NULL) { 2060 dictionary()->add_klass(name, loader_data, k); 2061 notice_modification(); 2062 } 2063 #ifdef ASSERT 2064 sd_check = find_class(d_index, d_hash, name, loader_data); 2065 assert (sd_check != NULL, "should have entry in system dictionary"); 2066 // Note: there may be a placeholder entry: for circularity testing 2067 // or for parallel defines 2068 #endif 2069 SystemDictionary_lock->notify_all(); 2070 } 2071 } 2072 2073 2074 // Try to find a class name using the loader constraints. The 2075 // loader constraints might know about a class that isn't fully loaded 2076 // yet and these will be ignored. 2077 Klass* SystemDictionary::find_constrained_instance_or_array_klass( 2078 Symbol* class_name, Handle class_loader, TRAPS) { 2079 2080 // First see if it has been loaded directly. 2081 // Force the protection domain to be null. (This removes protection checks.) 2082 Handle no_protection_domain; 2083 Klass* klass = find_instance_or_array_klass(class_name, class_loader, 2084 no_protection_domain, CHECK_NULL); 2085 if (klass != NULL) 2086 return klass; 2087 2088 // Now look to see if it has been loaded elsewhere, and is subject to 2089 // a loader constraint that would require this loader to return the 2090 // klass that is already loaded. 2091 if (FieldType::is_array(class_name)) { 2092 // For array classes, their Klass*s are not kept in the 2093 // constraint table. The element Klass*s are. 2094 FieldArrayInfo fd; 2095 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL)); 2096 if (t != T_OBJECT) { 2097 klass = Universe::typeArrayKlassObj(t); 2098 } else { 2099 MutexLocker mu(SystemDictionary_lock, THREAD); 2100 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader); 2101 } 2102 // If element class already loaded, allocate array klass 2103 if (klass != NULL) { 2104 klass = klass->array_klass_or_null(fd.dimension()); 2105 } 2106 } else { 2107 MutexLocker mu(SystemDictionary_lock, THREAD); 2108 // Non-array classes are easy: simply check the constraint table. 2109 klass = constraints()->find_constrained_klass(class_name, class_loader); 2110 } 2111 2112 return klass; 2113 } 2114 2115 2116 bool SystemDictionary::add_loader_constraint(Symbol* class_name, 2117 Handle class_loader1, 2118 Handle class_loader2, 2119 Thread* THREAD) { 2120 ClassLoaderData* loader_data1 = class_loader_data(class_loader1); 2121 ClassLoaderData* loader_data2 = class_loader_data(class_loader2); 2122 2123 Symbol* constraint_name = NULL; 2124 if (!FieldType::is_array(class_name)) { 2125 constraint_name = class_name; 2126 } else { 2127 // For array classes, their Klass*s are not kept in the 2128 // constraint table. The element classes are. 2129 FieldArrayInfo fd; 2130 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false)); 2131 // primitive types always pass 2132 if (t != T_OBJECT) { 2133 return true; 2134 } else { 2135 constraint_name = fd.object_key(); 2136 } 2137 } 2138 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1); 2139 int d_index1 = dictionary()->hash_to_index(d_hash1); 2140 2141 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2); 2142 int d_index2 = dictionary()->hash_to_index(d_hash2); 2143 { 2144 MutexLocker mu_s(SystemDictionary_lock, THREAD); 2145 2146 // Better never do a GC while we're holding these oops 2147 No_Safepoint_Verifier nosafepoint; 2148 2149 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1); 2150 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2); 2151 return constraints()->add_entry(constraint_name, klass1, class_loader1, 2152 klass2, class_loader2); 2153 } 2154 } 2155 2156 // Add entry to resolution error table to record the error when the first 2157 // attempt to resolve a reference to a class has failed. 2158 void SystemDictionary::add_resolution_error(constantPoolHandle pool, int which, 2159 Symbol* error, Symbol* message) { 2160 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2161 int index = resolution_errors()->hash_to_index(hash); 2162 { 2163 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2164 resolution_errors()->add_entry(index, hash, pool, which, error, message); 2165 } 2166 } 2167 2168 // Delete a resolution error for RedefineClasses for a constant pool is going away 2169 void SystemDictionary::delete_resolution_error(ConstantPool* pool) { 2170 resolution_errors()->delete_entry(pool); 2171 } 2172 2173 // Lookup resolution error table. Returns error if found, otherwise NULL. 2174 Symbol* SystemDictionary::find_resolution_error(constantPoolHandle pool, int which, 2175 Symbol** message) { 2176 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2177 int index = resolution_errors()->hash_to_index(hash); 2178 { 2179 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2180 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which); 2181 if (entry != NULL) { 2182 *message = entry->message(); 2183 return entry->error(); 2184 } else { 2185 return NULL; 2186 } 2187 } 2188 } 2189 2190 2191 // Signature constraints ensure that callers and callees agree about 2192 // the meaning of type names in their signatures. This routine is the 2193 // intake for constraints. It collects them from several places: 2194 // 2195 // * LinkResolver::resolve_method (if check_access is true) requires 2196 // that the resolving class (the caller) and the defining class of 2197 // the resolved method (the callee) agree on each type in the 2198 // method's signature. 2199 // 2200 // * LinkResolver::resolve_interface_method performs exactly the same 2201 // checks. 2202 // 2203 // * LinkResolver::resolve_field requires that the constant pool 2204 // attempting to link to a field agree with the field's defining 2205 // class about the type of the field signature. 2206 // 2207 // * klassVtable::initialize_vtable requires that, when a class 2208 // overrides a vtable entry allocated by a superclass, that the 2209 // overriding method (i.e., the callee) agree with the superclass 2210 // on each type in the method's signature. 2211 // 2212 // * klassItable::initialize_itable requires that, when a class fills 2213 // in its itables, for each non-abstract method installed in an 2214 // itable, the method (i.e., the callee) agree with the interface 2215 // on each type in the method's signature. 2216 // 2217 // All those methods have a boolean (check_access, checkconstraints) 2218 // which turns off the checks. This is used from specialized contexts 2219 // such as bootstrapping, dumping, and debugging. 2220 // 2221 // No direct constraint is placed between the class and its 2222 // supertypes. Constraints are only placed along linked relations 2223 // between callers and callees. When a method overrides or implements 2224 // an abstract method in a supertype (superclass or interface), the 2225 // constraints are placed as if the supertype were the caller to the 2226 // overriding method. (This works well, since callers to the 2227 // supertype have already established agreement between themselves and 2228 // the supertype.) As a result of all this, a class can disagree with 2229 // its supertype about the meaning of a type name, as long as that 2230 // class neither calls a relevant method of the supertype, nor is 2231 // called (perhaps via an override) from the supertype. 2232 // 2233 // 2234 // SystemDictionary::check_signature_loaders(sig, l1, l2) 2235 // 2236 // Make sure all class components (including arrays) in the given 2237 // signature will be resolved to the same class in both loaders. 2238 // Returns the name of the type that failed a loader constraint check, or 2239 // NULL if no constraint failed. No exception except OOME is thrown. 2240 // Arrays are not added to the loader constraint table, their elements are. 2241 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature, 2242 Handle loader1, Handle loader2, 2243 bool is_method, TRAPS) { 2244 // Nothing to do if loaders are the same. 2245 if (loader1() == loader2()) { 2246 return NULL; 2247 } 2248 2249 SignatureStream sig_strm(signature, is_method); 2250 while (!sig_strm.is_done()) { 2251 if (sig_strm.is_object()) { 2252 Symbol* sig = sig_strm.as_symbol(CHECK_NULL); 2253 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) { 2254 return sig; 2255 } 2256 } 2257 sig_strm.next(); 2258 } 2259 return NULL; 2260 } 2261 2262 2263 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid, 2264 Symbol* signature, 2265 TRAPS) { 2266 methodHandle empty; 2267 assert(MethodHandles::is_signature_polymorphic(iid) && 2268 MethodHandles::is_signature_polymorphic_intrinsic(iid) && 2269 iid != vmIntrinsics::_invokeGeneric, 2270 err_msg("must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid))); 2271 2272 unsigned int hash = invoke_method_table()->compute_hash(signature, iid); 2273 int index = invoke_method_table()->hash_to_index(hash); 2274 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid); 2275 methodHandle m; 2276 if (spe == NULL || spe->method() == NULL) { 2277 spe = NULL; 2278 // Must create lots of stuff here, but outside of the SystemDictionary lock. 2279 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty)); 2280 if (!Arguments::is_interpreter_only()) { 2281 // Generate a compiled form of the MH intrinsic. 2282 AdapterHandlerLibrary::create_native_wrapper(m); 2283 // Check if have the compiled code. 2284 if (!m->has_compiled_code()) { 2285 THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(), 2286 "out of space in CodeCache for method handle intrinsic", empty); 2287 } 2288 } 2289 // Now grab the lock. We might have to throw away the new method, 2290 // if a racing thread has managed to install one at the same time. 2291 { 2292 MutexLocker ml(SystemDictionary_lock, THREAD); 2293 spe = invoke_method_table()->find_entry(index, hash, signature, iid); 2294 if (spe == NULL) 2295 spe = invoke_method_table()->add_entry(index, hash, signature, iid); 2296 if (spe->method() == NULL) 2297 spe->set_method(m()); 2298 } 2299 } 2300 2301 assert(spe != NULL && spe->method() != NULL, ""); 2302 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() && 2303 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()), 2304 "MH intrinsic invariant"); 2305 return spe->method(); 2306 } 2307 2308 // Helper for unpacking the return value from linkMethod and linkCallSite. 2309 static methodHandle unpack_method_and_appendix(Handle mname, 2310 KlassHandle accessing_klass, 2311 objArrayHandle appendix_box, 2312 Handle* appendix_result, 2313 TRAPS) { 2314 methodHandle empty; 2315 if (mname.not_null()) { 2316 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname()); 2317 if (vmtarget != NULL && vmtarget->is_method()) { 2318 Method* m = (Method*)vmtarget; 2319 oop appendix = appendix_box->obj_at(0); 2320 if (TraceMethodHandles) { 2321 #ifndef PRODUCT 2322 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m)); 2323 m->print(); 2324 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); } 2325 tty->cr(); 2326 #endif //PRODUCT 2327 } 2328 (*appendix_result) = Handle(THREAD, appendix); 2329 // the target is stored in the cpCache and if a reference to this 2330 // MethodName is dropped we need a way to make sure the 2331 // class_loader containing this method is kept alive. 2332 // FIXME: the appendix might also preserve this dependency. 2333 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data(); 2334 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM 2335 return methodHandle(THREAD, m); 2336 } 2337 } 2338 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty); 2339 return empty; 2340 } 2341 2342 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name, 2343 Symbol* signature, 2344 KlassHandle accessing_klass, 2345 Handle *appendix_result, 2346 Handle *method_type_result, 2347 TRAPS) { 2348 methodHandle empty; 2349 assert(THREAD->can_call_java() ,""); 2350 Handle method_type = 2351 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty)); 2352 2353 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass(); 2354 int ref_kind = JVM_REF_invokeVirtual; 2355 Handle name_str = StringTable::intern(name, CHECK_(empty)); 2356 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty)); 2357 assert(appendix_box->obj_at(0) == NULL, ""); 2358 2359 // This should not happen. JDK code should take care of that. 2360 if (accessing_klass.is_null() || method_type.is_null()) { 2361 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty); 2362 } 2363 2364 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName 2365 JavaCallArguments args; 2366 args.push_oop(accessing_klass()->java_mirror()); 2367 args.push_int(ref_kind); 2368 args.push_oop(mh_klass()->java_mirror()); 2369 args.push_oop(name_str()); 2370 args.push_oop(method_type()); 2371 args.push_oop(appendix_box()); 2372 JavaValue result(T_OBJECT); 2373 JavaCalls::call_static(&result, 2374 SystemDictionary::MethodHandleNatives_klass(), 2375 vmSymbols::linkMethod_name(), 2376 vmSymbols::linkMethod_signature(), 2377 &args, CHECK_(empty)); 2378 Handle mname(THREAD, (oop) result.get_jobject()); 2379 (*method_type_result) = method_type; 2380 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD); 2381 } 2382 2383 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks. 2384 // We must ensure that all class loaders everywhere will reach this class, for any client. 2385 // This is a safe bet for public classes in java.lang, such as Object and String. 2386 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types. 2387 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util. 2388 static bool is_always_visible_class(oop mirror) { 2389 Klass* klass = java_lang_Class::as_Klass(mirror); 2390 if (klass->oop_is_objArray()) { 2391 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type 2392 } 2393 if (klass->oop_is_typeArray()) { 2394 return true; // primitive array 2395 } 2396 assert(klass->oop_is_instance(), klass->external_name()); 2397 return klass->is_public() && 2398 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang 2399 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke 2400 } 2401 2402 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given 2403 // signature, as interpreted relative to the given class loader. 2404 // Because of class loader constraints, all method handle usage must be 2405 // consistent with this loader. 2406 Handle SystemDictionary::find_method_handle_type(Symbol* signature, 2407 KlassHandle accessing_klass, 2408 TRAPS) { 2409 Handle empty; 2410 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics 2411 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid); 2412 int index = invoke_method_table()->hash_to_index(hash); 2413 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2414 if (spe != NULL && spe->method_type() != NULL) { 2415 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), ""); 2416 return Handle(THREAD, spe->method_type()); 2417 } else if (!THREAD->can_call_java()) { 2418 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME 2419 return Handle(); // do not attempt from within compiler, unless it was cached 2420 } 2421 2422 Handle class_loader, protection_domain; 2423 if (accessing_klass.not_null()) { 2424 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader()); 2425 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain()); 2426 } 2427 bool can_be_cached = true; 2428 int npts = ArgumentCount(signature).size(); 2429 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty)); 2430 int arg = 0; 2431 Handle rt; // the return type from the signature 2432 ResourceMark rm(THREAD); 2433 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) { 2434 oop mirror = NULL; 2435 if (can_be_cached) { 2436 // Use neutral class loader to lookup candidate classes to be placed in the cache. 2437 mirror = ss.as_java_mirror(Handle(), Handle(), 2438 SignatureStream::ReturnNull, CHECK_(empty)); 2439 if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) { 2440 // Fall back to accessing_klass context. 2441 can_be_cached = false; 2442 } 2443 } 2444 if (!can_be_cached) { 2445 // Resolve, throwing a real error if it doesn't work. 2446 mirror = ss.as_java_mirror(class_loader, protection_domain, 2447 SignatureStream::NCDFError, CHECK_(empty)); 2448 } 2449 assert(!oopDesc::is_null(mirror), ss.as_symbol(THREAD)->as_C_string()); 2450 if (ss.at_return_type()) 2451 rt = Handle(THREAD, mirror); 2452 else 2453 pts->obj_at_put(arg++, mirror); 2454 2455 // Check accessibility. 2456 if (ss.is_object() && accessing_klass.not_null()) { 2457 Klass* sel_klass = java_lang_Class::as_Klass(mirror); 2458 mirror = NULL; // safety 2459 // Emulate ConstantPool::verify_constant_pool_resolve. 2460 if (sel_klass->oop_is_objArray()) 2461 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass(); 2462 if (sel_klass->oop_is_instance()) { 2463 KlassHandle sel_kh(THREAD, sel_klass); 2464 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty)); 2465 } 2466 } 2467 } 2468 assert(arg == npts, ""); 2469 2470 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType 2471 JavaCallArguments args(Handle(THREAD, rt())); 2472 args.push_oop(pts()); 2473 JavaValue result(T_OBJECT); 2474 JavaCalls::call_static(&result, 2475 SystemDictionary::MethodHandleNatives_klass(), 2476 vmSymbols::findMethodHandleType_name(), 2477 vmSymbols::findMethodHandleType_signature(), 2478 &args, CHECK_(empty)); 2479 Handle method_type(THREAD, (oop) result.get_jobject()); 2480 2481 if (can_be_cached) { 2482 // We can cache this MethodType inside the JVM. 2483 MutexLocker ml(SystemDictionary_lock, THREAD); 2484 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2485 if (spe == NULL) 2486 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid); 2487 if (spe->method_type() == NULL) { 2488 spe->set_method_type(method_type()); 2489 } 2490 } 2491 2492 // report back to the caller with the MethodType 2493 return method_type; 2494 } 2495 2496 // Ask Java code to find or construct a method handle constant. 2497 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller, 2498 int ref_kind, //e.g., JVM_REF_invokeVirtual 2499 KlassHandle callee, 2500 Symbol* name_sym, 2501 Symbol* signature, 2502 TRAPS) { 2503 Handle empty; 2504 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty)); 2505 Handle type; 2506 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') { 2507 type = find_method_handle_type(signature, caller, CHECK_(empty)); 2508 } else if (caller.is_null()) { 2509 // This should not happen. JDK code should take care of that. 2510 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty); 2511 } else { 2512 ResourceMark rm(THREAD); 2513 SignatureStream ss(signature, false); 2514 if (!ss.is_done()) { 2515 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(), 2516 SignatureStream::NCDFError, CHECK_(empty)); 2517 type = Handle(THREAD, mirror); 2518 ss.next(); 2519 if (!ss.is_done()) type = Handle(); // error! 2520 } 2521 } 2522 if (type.is_null()) { 2523 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty); 2524 } 2525 2526 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle 2527 JavaCallArguments args; 2528 args.push_oop(caller->java_mirror()); // the referring class 2529 args.push_int(ref_kind); 2530 args.push_oop(callee->java_mirror()); // the target class 2531 args.push_oop(name()); 2532 args.push_oop(type()); 2533 JavaValue result(T_OBJECT); 2534 JavaCalls::call_static(&result, 2535 SystemDictionary::MethodHandleNatives_klass(), 2536 vmSymbols::linkMethodHandleConstant_name(), 2537 vmSymbols::linkMethodHandleConstant_signature(), 2538 &args, CHECK_(empty)); 2539 return Handle(THREAD, (oop) result.get_jobject()); 2540 } 2541 2542 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given 2543 // name and signature, as interpreted relative to the given class loader. 2544 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller, 2545 Handle bootstrap_specifier, 2546 Symbol* name, 2547 Symbol* type, 2548 Handle *appendix_result, 2549 Handle *method_type_result, 2550 TRAPS) { 2551 methodHandle empty; 2552 Handle bsm, info; 2553 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) { 2554 bsm = bootstrap_specifier; 2555 } else { 2556 assert(bootstrap_specifier->is_objArray(), ""); 2557 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier()); 2558 int len = args->length(); 2559 assert(len >= 1, ""); 2560 bsm = Handle(THREAD, args->obj_at(0)); 2561 if (len > 1) { 2562 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty)); 2563 for (int i = 1; i < len; i++) 2564 args1->obj_at_put(i-1, args->obj_at(i)); 2565 info = Handle(THREAD, args1); 2566 } 2567 } 2568 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()), 2569 "caller must supply a valid BSM"); 2570 2571 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty)); 2572 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty)); 2573 2574 // This should not happen. JDK code should take care of that. 2575 if (caller.is_null() || method_type.is_null()) { 2576 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty); 2577 } 2578 2579 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty)); 2580 assert(appendix_box->obj_at(0) == NULL, ""); 2581 2582 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix) 2583 JavaCallArguments args; 2584 args.push_oop(caller->java_mirror()); 2585 args.push_oop(bsm()); 2586 args.push_oop(method_name()); 2587 args.push_oop(method_type()); 2588 args.push_oop(info()); 2589 args.push_oop(appendix_box); 2590 JavaValue result(T_OBJECT); 2591 JavaCalls::call_static(&result, 2592 SystemDictionary::MethodHandleNatives_klass(), 2593 vmSymbols::linkCallSite_name(), 2594 vmSymbols::linkCallSite_signature(), 2595 &args, CHECK_(empty)); 2596 Handle mname(THREAD, (oop) result.get_jobject()); 2597 (*method_type_result) = method_type; 2598 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD); 2599 } 2600 2601 // Since the identity hash code for symbols changes when the symbols are 2602 // moved from the regular perm gen (hash in the mark word) to the shared 2603 // spaces (hash is the address), the classes loaded into the dictionary 2604 // may be in the wrong buckets. 2605 2606 void SystemDictionary::reorder_dictionary() { 2607 dictionary()->reorder_dictionary(); 2608 } 2609 2610 2611 void SystemDictionary::copy_buckets(char** top, char* end) { 2612 dictionary()->copy_buckets(top, end); 2613 } 2614 2615 2616 void SystemDictionary::copy_table(char** top, char* end) { 2617 dictionary()->copy_table(top, end); 2618 } 2619 2620 2621 void SystemDictionary::reverse() { 2622 dictionary()->reverse(); 2623 } 2624 2625 int SystemDictionary::number_of_classes() { 2626 return dictionary()->number_of_entries(); 2627 } 2628 2629 2630 // ---------------------------------------------------------------------------- 2631 void SystemDictionary::print_shared(bool details) { 2632 shared_dictionary()->print(details); 2633 } 2634 2635 void SystemDictionary::print(bool details) { 2636 dictionary()->print(details); 2637 2638 // Placeholders 2639 GCMutexLocker mu(SystemDictionary_lock); 2640 placeholders()->print(); 2641 2642 // loader constraints - print under SD_lock 2643 constraints()->print(); 2644 } 2645 2646 2647 void SystemDictionary::verify() { 2648 guarantee(dictionary() != NULL, "Verify of system dictionary failed"); 2649 guarantee(constraints() != NULL, 2650 "Verify of loader constraints failed"); 2651 guarantee(dictionary()->number_of_entries() >= 0 && 2652 placeholders()->number_of_entries() >= 0, 2653 "Verify of system dictionary failed"); 2654 2655 // Verify dictionary 2656 dictionary()->verify(); 2657 2658 GCMutexLocker mu(SystemDictionary_lock); 2659 placeholders()->verify(); 2660 2661 // Verify constraint table 2662 guarantee(constraints() != NULL, "Verify of loader constraints failed"); 2663 constraints()->verify(dictionary(), placeholders()); 2664 } 2665 2666 // utility function for class load event 2667 void SystemDictionary::post_class_load_event(const Ticks& start_time, 2668 instanceKlassHandle k, 2669 Handle initiating_loader) { 2670 #if INCLUDE_TRACE 2671 EventClassLoad event(UNTIMED); 2672 if (event.should_commit()) { 2673 event.set_starttime(start_time); 2674 event.set_loadedClass(k()); 2675 oop defining_class_loader = k->class_loader(); 2676 event.set_definingClassLoader(defining_class_loader != NULL ? 2677 defining_class_loader->klass() : (Klass*)NULL); 2678 oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader(); 2679 event.set_initiatingClassLoader(class_loader != NULL ? 2680 class_loader->klass() : (Klass*)NULL); 2681 event.commit(); 2682 } 2683 #endif // INCLUDE_TRACE 2684 } 2685