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/backtrace.hpp" 27 #include "classfile/classLoaderData.inline.hpp" 28 #include "classfile/dictionary.hpp" 29 #include "classfile/javaClasses.inline.hpp" 30 #include "classfile/loaderConstraints.hpp" 31 #include "classfile/placeholders.hpp" 32 #include "classfile/resolutionErrors.hpp" 33 #include "classfile/stringTable.hpp" 34 #include "classfile/systemDictionary.hpp" 35 #include "classfile/vmSymbols.hpp" 36 #include "code/codeCache.hpp" 37 #include "compiler/compileBroker.hpp" 38 #include "gc/shared/gcLocker.hpp" 39 #include "interpreter/bytecodeStream.hpp" 40 #include "interpreter/interpreter.hpp" 41 #include "memory/filemap.hpp" 42 #include "memory/oopFactory.hpp" 43 #include "oops/instanceKlass.hpp" 44 #include "oops/instanceRefKlass.hpp" 45 #include "oops/klass.inline.hpp" 46 #include "oops/methodData.hpp" 47 #include "oops/objArrayKlass.hpp" 48 #include "oops/objArrayOop.inline.hpp" 49 #include "oops/oop.inline.hpp" 50 #include "oops/typeArrayKlass.hpp" 51 #include "prims/jvmtiEnvBase.hpp" 52 #include "prims/methodHandles.hpp" 53 #include "runtime/arguments.hpp" 54 #include "runtime/biasedLocking.hpp" 55 #include "runtime/fieldType.hpp" 56 #include "runtime/handles.inline.hpp" 57 #include "runtime/java.hpp" 58 #include "runtime/javaCalls.hpp" 59 #include "runtime/mutexLocker.hpp" 60 #include "runtime/orderAccess.inline.hpp" 61 #include "runtime/signature.hpp" 62 #include "services/classLoadingService.hpp" 63 #include "services/threadService.hpp" 64 #include "utilities/macros.hpp" 65 #include "utilities/ticks.hpp" 66 #if INCLUDE_CDS 67 #include "classfile/sharedClassUtil.hpp" 68 #include "classfile/systemDictionaryShared.hpp" 69 #endif 70 #if INCLUDE_JVMCI 71 #include "jvmci/jvmciRuntime.hpp" 72 #endif 73 #if INCLUDE_TRACE 74 #include "trace/tracing.hpp" 75 #endif 76 77 Dictionary* SystemDictionary::_dictionary = NULL; 78 PlaceholderTable* SystemDictionary::_placeholders = NULL; 79 Dictionary* SystemDictionary::_shared_dictionary = NULL; 80 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL; 81 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL; 82 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL; 83 84 85 int SystemDictionary::_number_of_modifications = 0; 86 int SystemDictionary::_sdgeneration = 0; 87 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103, 88 20201,40423,99991}; 89 90 oop SystemDictionary::_system_loader_lock_obj = NULL; 91 92 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT] 93 = { NULL /*, NULL...*/ }; 94 95 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ }; 96 97 oop SystemDictionary::_java_system_loader = NULL; 98 99 bool SystemDictionary::_has_loadClassInternal = false; 100 bool SystemDictionary::_has_checkPackageAccess = false; 101 102 // lazily initialized klass variables 103 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL; 104 105 106 // ---------------------------------------------------------------------------- 107 // Java-level SystemLoader 108 109 oop SystemDictionary::java_system_loader() { 110 return _java_system_loader; 111 } 112 113 void SystemDictionary::compute_java_system_loader(TRAPS) { 114 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass)); 115 JavaValue result(T_OBJECT); 116 JavaCalls::call_static(&result, 117 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)), 118 vmSymbols::getSystemClassLoader_name(), 119 vmSymbols::void_classloader_signature(), 120 CHECK); 121 122 _java_system_loader = (oop)result.get_jobject(); 123 124 CDS_ONLY(SystemDictionaryShared::initialize(CHECK);) 125 } 126 127 128 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) { 129 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data(); 130 return ClassLoaderDataGraph::find_or_create(class_loader, THREAD); 131 } 132 133 // ---------------------------------------------------------------------------- 134 // debugging 135 136 #ifdef ASSERT 137 138 // return true if class_name contains no '.' (internal format is '/') 139 bool SystemDictionary::is_internal_format(Symbol* class_name) { 140 if (class_name != NULL) { 141 ResourceMark rm; 142 char* name = class_name->as_C_string(); 143 return strchr(name, '.') == NULL; 144 } else { 145 return true; 146 } 147 } 148 149 #endif 150 151 // ---------------------------------------------------------------------------- 152 // Parallel class loading check 153 154 bool SystemDictionary::is_parallelCapable(Handle class_loader) { 155 if (UnsyncloadClass || class_loader.is_null()) return true; 156 if (AlwaysLockClassLoader) return false; 157 return java_lang_ClassLoader::parallelCapable(class_loader()); 158 } 159 // ---------------------------------------------------------------------------- 160 // ParallelDefineClass flag does not apply to bootclass loader 161 bool SystemDictionary::is_parallelDefine(Handle class_loader) { 162 if (class_loader.is_null()) return false; 163 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) { 164 return true; 165 } 166 return false; 167 } 168 169 /** 170 * Returns true if the passed class loader is the extension class loader. 171 */ 172 bool SystemDictionary::is_ext_class_loader(Handle class_loader) { 173 if (class_loader.is_null()) { 174 return false; 175 } 176 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader()); 177 } 178 179 // ---------------------------------------------------------------------------- 180 // Resolving of classes 181 182 // Forwards to resolve_or_null 183 184 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) { 185 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD); 186 if (HAS_PENDING_EXCEPTION || klass == NULL) { 187 KlassHandle k_h(THREAD, klass); 188 // can return a null klass 189 klass = handle_resolution_exception(class_name, throw_error, k_h, THREAD); 190 } 191 return klass; 192 } 193 194 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, 195 bool throw_error, 196 KlassHandle klass_h, TRAPS) { 197 if (HAS_PENDING_EXCEPTION) { 198 // If we have a pending exception we forward it to the caller, unless throw_error is true, 199 // in which case we have to check whether the pending exception is a ClassNotFoundException, 200 // and if so convert it to a NoClassDefFoundError 201 // And chain the original ClassNotFoundException 202 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) { 203 ResourceMark rm(THREAD); 204 assert(klass_h() == NULL, "Should not have result with exception pending"); 205 Handle e(THREAD, PENDING_EXCEPTION); 206 CLEAR_PENDING_EXCEPTION; 207 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e); 208 } else { 209 return NULL; 210 } 211 } 212 // Class not found, throw appropriate error or exception depending on value of throw_error 213 if (klass_h() == NULL) { 214 ResourceMark rm(THREAD); 215 if (throw_error) { 216 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string()); 217 } else { 218 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string()); 219 } 220 } 221 return (Klass*)klass_h(); 222 } 223 224 225 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, 226 bool throw_error, TRAPS) 227 { 228 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD); 229 } 230 231 232 // Forwards to resolve_instance_class_or_null 233 234 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) { 235 assert(THREAD->can_call_java(), 236 "can not load classes with compiler thread: class=%s, classloader=%s", 237 class_name->as_C_string(), 238 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()); 239 if (FieldType::is_array(class_name)) { 240 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD); 241 } else if (FieldType::is_obj(class_name)) { 242 ResourceMark rm(THREAD); 243 // Ignore wrapping L and ;. 244 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1, 245 class_name->utf8_length() - 2, CHECK_NULL); 246 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD); 247 } else { 248 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD); 249 } 250 } 251 252 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) { 253 return resolve_or_null(class_name, Handle(), Handle(), THREAD); 254 } 255 256 // Forwards to resolve_instance_class_or_null 257 258 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name, 259 Handle class_loader, 260 Handle protection_domain, 261 TRAPS) { 262 assert(FieldType::is_array(class_name), "must be array"); 263 Klass* k = NULL; 264 FieldArrayInfo fd; 265 // dimension and object_key in FieldArrayInfo are assigned as a side-effect 266 // of this call 267 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL); 268 if (t == T_OBJECT) { 269 // naked oop "k" is OK here -- we assign back into it 270 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(), 271 class_loader, 272 protection_domain, 273 CHECK_NULL); 274 if (k != NULL) { 275 k = k->array_klass(fd.dimension(), CHECK_NULL); 276 } 277 } else { 278 k = Universe::typeArrayKlassObj(t); 279 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL); 280 } 281 return k; 282 } 283 284 285 // Must be called for any super-class or super-interface resolution 286 // during class definition to allow class circularity checking 287 // super-interface callers: 288 // parse_interfaces - for defineClass & jvmtiRedefineClasses 289 // super-class callers: 290 // ClassFileParser - for defineClass & jvmtiRedefineClasses 291 // load_shared_class - while loading a class from shared archive 292 // resolve_instance_class_or_null: 293 // via: handle_parallel_super_load 294 // when resolving a class that has an existing placeholder with 295 // a saved superclass [i.e. a defineClass is currently in progress] 296 // if another thread is trying to resolve the class, it must do 297 // super-class checks on its own thread to catch class circularity 298 // This last call is critical in class circularity checking for cases 299 // where classloading is delegated to different threads and the 300 // classloader lock is released. 301 // Take the case: Base->Super->Base 302 // 1. If thread T1 tries to do a defineClass of class Base 303 // resolve_super_or_fail creates placeholder: T1, Base (super Super) 304 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super 305 // so it tries to load Super 306 // 3. If we load the class internally, or user classloader uses same thread 307 // loadClassFromxxx or defineClass via parseClassFile Super ... 308 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base) 309 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base 310 // 3.4 calls resolve_super_or_fail Base 311 // 3.5 finds T1,Base -> throws class circularity 312 //OR 4. If T2 tries to resolve Super via defineClass Super ... 313 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base) 314 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super) 315 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2 316 // 4.4 finds T2, Super -> throws class circularity 317 // Must be called, even if superclass is null, since this is 318 // where the placeholder entry is created which claims this 319 // thread is loading this class/classloader. 320 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name, 321 Symbol* class_name, 322 Handle class_loader, 323 Handle protection_domain, 324 bool is_superclass, 325 TRAPS) { 326 // Double-check, if child class is already loaded, just return super-class,interface 327 // Don't add a placedholder if already loaded, i.e. already in system dictionary 328 // Make sure there's a placeholder for the *child* before resolving. 329 // Used as a claim that this thread is currently loading superclass/classloader 330 // Used here for ClassCircularity checks and also for heap verification 331 // (every InstanceKlass in the heap needs to be in the system dictionary 332 // or have a placeholder). 333 // Must check ClassCircularity before checking if super class is already loaded 334 // 335 // We might not already have a placeholder if this child_name was 336 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass); 337 // the name of the class might not be known until the stream is actually 338 // parsed. 339 // Bugs 4643874, 4715493 340 // compute_hash can have a safepoint 341 342 ClassLoaderData* loader_data = class_loader_data(class_loader); 343 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data); 344 int d_index = dictionary()->hash_to_index(d_hash); 345 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data); 346 int p_index = placeholders()->hash_to_index(p_hash); 347 // can't throw error holding a lock 348 bool child_already_loaded = false; 349 bool throw_circularity_error = false; 350 { 351 MutexLocker mu(SystemDictionary_lock, THREAD); 352 Klass* childk = find_class(d_index, d_hash, child_name, loader_data); 353 Klass* quicksuperk; 354 // to support // loading: if child done loading, just return superclass 355 // if class_name, & class_loader don't match: 356 // if initial define, SD update will give LinkageError 357 // if redefine: compare_class_versions will give HIERARCHY_CHANGED 358 // so we don't throw an exception here. 359 // see: nsk redefclass014 & java.lang.instrument Instrument032 360 if ((childk != NULL ) && (is_superclass) && 361 ((quicksuperk = childk->super()) != NULL) && 362 363 ((quicksuperk->name() == class_name) && 364 (quicksuperk->class_loader() == class_loader()))) { 365 return quicksuperk; 366 } else { 367 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data); 368 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) { 369 throw_circularity_error = true; 370 } 371 } 372 if (!throw_circularity_error) { 373 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD); 374 } 375 } 376 if (throw_circularity_error) { 377 ResourceMark rm(THREAD); 378 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string()); 379 } 380 381 // java.lang.Object should have been found above 382 assert(class_name != NULL, "null super class for resolving"); 383 // Resolve the super class or interface, check results on return 384 Klass* superk = SystemDictionary::resolve_or_null(class_name, 385 class_loader, 386 protection_domain, 387 THREAD); 388 389 KlassHandle superk_h(THREAD, superk); 390 391 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up 392 // It is no longer necessary to keep the placeholder table alive until update_dictionary 393 // or error. GC used to walk the placeholder table as strong roots. 394 // The instanceKlass is kept alive because the class loader is on the stack, 395 // which keeps the loader_data alive, as well as all instanceKlasses in 396 // the loader_data. parseClassFile adds the instanceKlass to loader_data. 397 { 398 MutexLocker mu(SystemDictionary_lock, THREAD); 399 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD); 400 SystemDictionary_lock->notify_all(); 401 } 402 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) { 403 // can null superk 404 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, true, superk_h, THREAD)); 405 } 406 407 return superk_h(); 408 } 409 410 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass, 411 Handle class_loader, 412 Handle protection_domain, 413 TRAPS) { 414 if(!has_checkPackageAccess()) return; 415 416 // Now we have to call back to java to check if the initating class has access 417 JavaValue result(T_VOID); 418 if (TraceProtectionDomainVerification) { 419 // Print out trace information 420 tty->print_cr("Checking package access"); 421 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr(); 422 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr(); 423 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr(); 424 } 425 426 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass()); 427 JavaCalls::call_special(&result, 428 class_loader, 429 system_loader, 430 vmSymbols::checkPackageAccess_name(), 431 vmSymbols::class_protectiondomain_signature(), 432 Handle(THREAD, klass->java_mirror()), 433 protection_domain, 434 THREAD); 435 436 if (TraceProtectionDomainVerification) { 437 if (HAS_PENDING_EXCEPTION) { 438 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!"); 439 } else { 440 tty->print_cr(" -> granted"); 441 } 442 tty->cr(); 443 } 444 445 if (HAS_PENDING_EXCEPTION) return; 446 447 // If no exception has been thrown, we have validated the protection domain 448 // Insert the protection domain of the initiating class into the set. 449 { 450 // We recalculate the entry here -- we've called out to java since 451 // the last time it was calculated. 452 ClassLoaderData* loader_data = class_loader_data(class_loader); 453 454 Symbol* kn = klass->name(); 455 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data); 456 int d_index = dictionary()->hash_to_index(d_hash); 457 458 MutexLocker mu(SystemDictionary_lock, THREAD); 459 { 460 // Note that we have an entry, and entries can be deleted only during GC, 461 // so we cannot allow GC to occur while we're holding this entry. 462 463 // We're using a No_Safepoint_Verifier to catch any place where we 464 // might potentially do a GC at all. 465 // Dictionary::do_unloading() asserts that classes in SD are only 466 // unloaded at a safepoint. Anonymous classes are not in SD. 467 No_Safepoint_Verifier nosafepoint; 468 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data, 469 protection_domain, THREAD); 470 } 471 } 472 } 473 474 // We only get here if this thread finds that another thread 475 // has already claimed the placeholder token for the current operation, 476 // but that other thread either never owned or gave up the 477 // object lock 478 // Waits on SystemDictionary_lock to indicate placeholder table updated 479 // On return, caller must recheck placeholder table state 480 // 481 // We only get here if 482 // 1) custom classLoader, i.e. not bootstrap classloader 483 // 2) UnsyncloadClass not set 484 // 3) custom classLoader has broken the class loader objectLock 485 // so another thread got here in parallel 486 // 487 // lockObject must be held. 488 // Complicated dance due to lock ordering: 489 // Must first release the classloader object lock to 490 // allow initial definer to complete the class definition 491 // and to avoid deadlock 492 // Reclaim classloader lock object with same original recursion count 493 // Must release SystemDictionary_lock after notify, since 494 // class loader lock must be claimed before SystemDictionary_lock 495 // to prevent deadlocks 496 // 497 // The notify allows applications that did an untimed wait() on 498 // the classloader object lock to not hang. 499 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) { 500 assert_lock_strong(SystemDictionary_lock); 501 502 bool calledholdinglock 503 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject); 504 assert(calledholdinglock,"must hold lock for notify"); 505 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait"); 506 ObjectSynchronizer::notifyall(lockObject, THREAD); 507 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD); 508 SystemDictionary_lock->wait(); 509 SystemDictionary_lock->unlock(); 510 ObjectSynchronizer::reenter(lockObject, recursions, THREAD); 511 SystemDictionary_lock->lock(); 512 } 513 514 // If the class in is in the placeholder table, class loading is in progress 515 // For cases where the application changes threads to load classes, it 516 // is critical to ClassCircularity detection that we try loading 517 // the superclass on the same thread internally, so we do parallel 518 // super class loading here. 519 // This also is critical in cases where the original thread gets stalled 520 // even in non-circularity situations. 521 // Note: must call resolve_super_or_fail even if null super - 522 // to force placeholder entry creation for this class for circularity detection 523 // Caller must check for pending exception 524 // Returns non-null Klass* if other thread has completed load 525 // and we are done, 526 // If return null Klass* and no pending exception, the caller must load the class 527 instanceKlassHandle SystemDictionary::handle_parallel_super_load( 528 Symbol* name, Symbol* superclassname, Handle class_loader, 529 Handle protection_domain, Handle lockObject, TRAPS) { 530 531 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 532 ClassLoaderData* loader_data = class_loader_data(class_loader); 533 unsigned int d_hash = dictionary()->compute_hash(name, loader_data); 534 int d_index = dictionary()->hash_to_index(d_hash); 535 unsigned int p_hash = placeholders()->compute_hash(name, loader_data); 536 int p_index = placeholders()->hash_to_index(p_hash); 537 538 // superk is not used, resolve_super called for circularity check only 539 // This code is reached in two situations. One if this thread 540 // is loading the same class twice (e.g. ClassCircularity, or 541 // java.lang.instrument). 542 // The second is if another thread started the resolve_super first 543 // and has not yet finished. 544 // In both cases the original caller will clean up the placeholder 545 // entry on error. 546 Klass* superk = SystemDictionary::resolve_super_or_fail(name, 547 superclassname, 548 class_loader, 549 protection_domain, 550 true, 551 CHECK_(nh)); 552 553 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete 554 // Serial class loaders and bootstrap classloader do wait for superclass loads 555 if (!class_loader.is_null() && is_parallelCapable(class_loader)) { 556 MutexLocker mu(SystemDictionary_lock, THREAD); 557 // Check if classloading completed while we were loading superclass or waiting 558 Klass* check = find_class(d_index, d_hash, name, loader_data); 559 if (check != NULL) { 560 // Klass is already loaded, so just return it 561 return(instanceKlassHandle(THREAD, check)); 562 } else { 563 return nh; 564 } 565 } 566 567 // must loop to both handle other placeholder updates 568 // and spurious notifications 569 bool super_load_in_progress = true; 570 PlaceholderEntry* placeholder; 571 while (super_load_in_progress) { 572 MutexLocker mu(SystemDictionary_lock, THREAD); 573 // Check if classloading completed while we were loading superclass or waiting 574 Klass* check = find_class(d_index, d_hash, name, loader_data); 575 if (check != NULL) { 576 // Klass is already loaded, so just return it 577 return(instanceKlassHandle(THREAD, check)); 578 } else { 579 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 580 if (placeholder && placeholder->super_load_in_progress() ){ 581 // Before UnsyncloadClass: 582 // We only get here if the application has released the 583 // classloader lock when another thread was in the middle of loading a 584 // superclass/superinterface for this class, and now 585 // this thread is also trying to load this class. 586 // To minimize surprises, the first thread that started to 587 // load a class should be the one to complete the loading 588 // with the classfile it initially expected. 589 // This logic has the current thread wait once it has done 590 // all the superclass/superinterface loading it can, until 591 // the original thread completes the class loading or fails 592 // If it completes we will use the resulting InstanceKlass 593 // which we will find below in the systemDictionary. 594 // We also get here for parallel bootstrap classloader 595 if (class_loader.is_null()) { 596 SystemDictionary_lock->wait(); 597 } else { 598 double_lock_wait(lockObject, THREAD); 599 } 600 } else { 601 // If not in SD and not in PH, other thread's load must have failed 602 super_load_in_progress = false; 603 } 604 } 605 } 606 return (nh); 607 } 608 609 610 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, 611 Handle class_loader, 612 Handle protection_domain, 613 TRAPS) { 614 assert(name != NULL && !FieldType::is_array(name) && 615 !FieldType::is_obj(name), "invalid class name"); 616 617 Ticks class_load_start_time = Ticks::now(); 618 619 // Fix for 4474172; see evaluation for more details 620 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 621 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL); 622 623 // Do lookup to see if class already exist and the protection domain 624 // has the right access 625 // This call uses find which checks protection domain already matches 626 // All subsequent calls use find_class, and set has_loaded_class so that 627 // before we return a result we call out to java to check for valid protection domain 628 // to allow returning the Klass* and add it to the pd_set if it is valid 629 unsigned int d_hash = dictionary()->compute_hash(name, loader_data); 630 int d_index = dictionary()->hash_to_index(d_hash); 631 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data, 632 protection_domain, THREAD); 633 if (probe != NULL) return probe; 634 635 636 // Non-bootstrap class loaders will call out to class loader and 637 // define via jvm/jni_DefineClass which will acquire the 638 // class loader object lock to protect against multiple threads 639 // defining the class in parallel by accident. 640 // This lock must be acquired here so the waiter will find 641 // any successful result in the SystemDictionary and not attempt 642 // the define 643 // ParallelCapable Classloaders and the bootstrap classloader, 644 // or all classloaders with UnsyncloadClass do not acquire lock here 645 bool DoObjectLock = true; 646 if (is_parallelCapable(class_loader)) { 647 DoObjectLock = false; 648 } 649 650 unsigned int p_hash = placeholders()->compute_hash(name, loader_data); 651 int p_index = placeholders()->hash_to_index(p_hash); 652 653 // Class is not in SystemDictionary so we have to do loading. 654 // Make sure we are synchronized on the class loader before we proceed 655 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 656 check_loader_lock_contention(lockObject, THREAD); 657 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 658 659 // Check again (after locking) if class already exist in SystemDictionary 660 bool class_has_been_loaded = false; 661 bool super_load_in_progress = false; 662 bool havesupername = false; 663 instanceKlassHandle k; 664 PlaceholderEntry* placeholder; 665 Symbol* superclassname = NULL; 666 667 { 668 MutexLocker mu(SystemDictionary_lock, THREAD); 669 Klass* check = find_class(d_index, d_hash, name, loader_data); 670 if (check != NULL) { 671 // Klass is already loaded, so just return it 672 class_has_been_loaded = true; 673 k = instanceKlassHandle(THREAD, check); 674 } else { 675 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 676 if (placeholder && placeholder->super_load_in_progress()) { 677 super_load_in_progress = true; 678 if (placeholder->havesupername() == true) { 679 superclassname = placeholder->supername(); 680 havesupername = true; 681 } 682 } 683 } 684 } 685 686 // If the class is in the placeholder table, class loading is in progress 687 if (super_load_in_progress && havesupername==true) { 688 k = SystemDictionary::handle_parallel_super_load(name, superclassname, 689 class_loader, protection_domain, lockObject, THREAD); 690 if (HAS_PENDING_EXCEPTION) { 691 return NULL; 692 } 693 if (!k.is_null()) { 694 class_has_been_loaded = true; 695 } 696 } 697 698 bool throw_circularity_error = false; 699 if (!class_has_been_loaded) { 700 bool load_instance_added = false; 701 702 // add placeholder entry to record loading instance class 703 // Five cases: 704 // All cases need to prevent modifying bootclasssearchpath 705 // in parallel with a classload of same classname 706 // Redefineclasses uses existence of the placeholder for the duration 707 // of the class load to prevent concurrent redefinition of not completely 708 // defined classes. 709 // case 1. traditional classloaders that rely on the classloader object lock 710 // - no other need for LOAD_INSTANCE 711 // case 2. traditional classloaders that break the classloader object lock 712 // as a deadlock workaround. Detection of this case requires that 713 // this check is done while holding the classloader object lock, 714 // and that lock is still held when calling classloader's loadClass. 715 // For these classloaders, we ensure that the first requestor 716 // completes the load and other requestors wait for completion. 717 // case 3. UnsyncloadClass - don't use objectLocker 718 // With this flag, we allow parallel classloading of a 719 // class/classloader pair 720 // case4. Bootstrap classloader - don't own objectLocker 721 // This classloader supports parallelism at the classloader level, 722 // but only allows a single load of a class/classloader pair. 723 // No performance benefit and no deadlock issues. 724 // case 5. parallelCapable user level classloaders - without objectLocker 725 // Allow parallel classloading of a class/classloader pair 726 727 { 728 MutexLocker mu(SystemDictionary_lock, THREAD); 729 if (class_loader.is_null() || !is_parallelCapable(class_loader)) { 730 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 731 if (oldprobe) { 732 // only need check_seen_thread once, not on each loop 733 // 6341374 java/lang/Instrument with -Xcomp 734 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) { 735 throw_circularity_error = true; 736 } else { 737 // case 1: traditional: should never see load_in_progress. 738 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) { 739 740 // case 4: bootstrap classloader: prevent futile classloading, 741 // wait on first requestor 742 if (class_loader.is_null()) { 743 SystemDictionary_lock->wait(); 744 } else { 745 // case 2: traditional with broken classloader lock. wait on first 746 // requestor. 747 double_lock_wait(lockObject, THREAD); 748 } 749 // Check if classloading completed while we were waiting 750 Klass* check = find_class(d_index, d_hash, name, loader_data); 751 if (check != NULL) { 752 // Klass is already loaded, so just return it 753 k = instanceKlassHandle(THREAD, check); 754 class_has_been_loaded = true; 755 } 756 // check if other thread failed to load and cleaned up 757 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 758 } 759 } 760 } 761 } 762 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock 763 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try 764 // LOAD_INSTANCE in parallel 765 766 if (!throw_circularity_error && !class_has_been_loaded) { 767 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD); 768 load_instance_added = true; 769 // For class loaders that do not acquire the classloader object lock, 770 // if they did not catch another thread holding LOAD_INSTANCE, 771 // need a check analogous to the acquire ObjectLocker/find_class 772 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL 773 // one final check if the load has already completed 774 // class loaders holding the ObjectLock shouldn't find the class here 775 Klass* check = find_class(d_index, d_hash, name, loader_data); 776 if (check != NULL) { 777 // Klass is already loaded, so return it after checking/adding protection domain 778 k = instanceKlassHandle(THREAD, check); 779 class_has_been_loaded = true; 780 } 781 } 782 } 783 784 // must throw error outside of owning lock 785 if (throw_circularity_error) { 786 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup"); 787 ResourceMark rm(THREAD); 788 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string()); 789 } 790 791 if (!class_has_been_loaded) { 792 793 // Do actual loading 794 k = load_instance_class(name, class_loader, THREAD); 795 796 // For UnsyncloadClass only 797 // If they got a linkageError, check if a parallel class load succeeded. 798 // If it did, then for bytecode resolution the specification requires 799 // that we return the same result we did for the other thread, i.e. the 800 // successfully loaded InstanceKlass 801 // Should not get here for classloaders that support parallelism 802 // with the new cleaner mechanism, even with AllowParallelDefineClass 803 // Bootstrap goes through here to allow for an extra guarantee check 804 if (UnsyncloadClass || (class_loader.is_null())) { 805 if (k.is_null() && HAS_PENDING_EXCEPTION 806 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) { 807 MutexLocker mu(SystemDictionary_lock, THREAD); 808 Klass* check = find_class(d_index, d_hash, name, loader_data); 809 if (check != NULL) { 810 // Klass is already loaded, so just use it 811 k = instanceKlassHandle(THREAD, check); 812 CLEAR_PENDING_EXCEPTION; 813 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?"); 814 } 815 } 816 } 817 818 // If everything was OK (no exceptions, no null return value), and 819 // class_loader is NOT the defining loader, do a little more bookkeeping. 820 if (!HAS_PENDING_EXCEPTION && !k.is_null() && 821 k->class_loader() != class_loader()) { 822 823 check_constraints(d_index, d_hash, k, class_loader, false, THREAD); 824 825 // Need to check for a PENDING_EXCEPTION again; check_constraints 826 // can throw and doesn't use the CHECK macro. 827 if (!HAS_PENDING_EXCEPTION) { 828 { // Grabbing the Compile_lock prevents systemDictionary updates 829 // during compilations. 830 MutexLocker mu(Compile_lock, THREAD); 831 update_dictionary(d_index, d_hash, p_index, p_hash, 832 k, class_loader, THREAD); 833 } 834 835 if (JvmtiExport::should_post_class_load()) { 836 Thread *thread = THREAD; 837 assert(thread->is_Java_thread(), "thread->is_Java_thread()"); 838 JvmtiExport::post_class_load((JavaThread *) thread, k()); 839 } 840 } 841 } 842 } // load_instance_class loop 843 844 if (load_instance_added == true) { 845 // clean up placeholder entries for LOAD_INSTANCE success or error 846 // This brackets the SystemDictionary updates for both defining 847 // and initiating loaders 848 MutexLocker mu(SystemDictionary_lock, THREAD); 849 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD); 850 SystemDictionary_lock->notify_all(); 851 } 852 } 853 854 if (HAS_PENDING_EXCEPTION || k.is_null()) { 855 return NULL; 856 } 857 858 post_class_load_event(class_load_start_time, k, class_loader); 859 860 #ifdef ASSERT 861 { 862 ClassLoaderData* loader_data = k->class_loader_data(); 863 MutexLocker mu(SystemDictionary_lock, THREAD); 864 Klass* kk = find_class(name, loader_data); 865 assert(kk == k(), "should be present in dictionary"); 866 } 867 #endif 868 869 // return if the protection domain in NULL 870 if (protection_domain() == NULL) return k(); 871 872 // Check the protection domain has the right access 873 { 874 MutexLocker mu(SystemDictionary_lock, THREAD); 875 // Note that we have an entry, and entries can be deleted only during GC, 876 // so we cannot allow GC to occur while we're holding this entry. 877 // We're using a No_Safepoint_Verifier to catch any place where we 878 // might potentially do a GC at all. 879 // Dictionary::do_unloading() asserts that classes in SD are only 880 // unloaded at a safepoint. Anonymous classes are not in SD. 881 No_Safepoint_Verifier nosafepoint; 882 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name, 883 loader_data, 884 protection_domain)) { 885 return k(); 886 } 887 } 888 889 // Verify protection domain. If it fails an exception is thrown 890 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL); 891 892 return k(); 893 } 894 895 896 // This routine does not lock the system dictionary. 897 // 898 // Since readers don't hold a lock, we must make sure that system 899 // dictionary entries are only removed at a safepoint (when only one 900 // thread is running), and are added to in a safe way (all links must 901 // be updated in an MT-safe manner). 902 // 903 // Callers should be aware that an entry could be added just after 904 // _dictionary->bucket(index) is read here, so the caller will not see 905 // the new entry. 906 907 Klass* SystemDictionary::find(Symbol* class_name, 908 Handle class_loader, 909 Handle protection_domain, 910 TRAPS) { 911 912 // The result of this call should be consistent with the result 913 // of the call to resolve_instance_class_or_null(). 914 // See evaluation 6790209 and 4474172 for more details. 915 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 916 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader()); 917 918 if (loader_data == NULL) { 919 // If the ClassLoaderData has not been setup, 920 // then the class loader has no entries in the dictionary. 921 return NULL; 922 } 923 924 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data); 925 int d_index = dictionary()->hash_to_index(d_hash); 926 927 { 928 // Note that we have an entry, and entries can be deleted only during GC, 929 // so we cannot allow GC to occur while we're holding this entry. 930 // We're using a No_Safepoint_Verifier to catch any place where we 931 // might potentially do a GC at all. 932 // Dictionary::do_unloading() asserts that classes in SD are only 933 // unloaded at a safepoint. Anonymous classes are not in SD. 934 No_Safepoint_Verifier nosafepoint; 935 return dictionary()->find(d_index, d_hash, class_name, loader_data, 936 protection_domain, THREAD); 937 } 938 } 939 940 941 // Look for a loaded instance or array klass by name. Do not do any loading. 942 // return NULL in case of error. 943 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name, 944 Handle class_loader, 945 Handle protection_domain, 946 TRAPS) { 947 Klass* k = NULL; 948 assert(class_name != NULL, "class name must be non NULL"); 949 950 if (FieldType::is_array(class_name)) { 951 // The name refers to an array. Parse the name. 952 // dimension and object_key in FieldArrayInfo are assigned as a 953 // side-effect of this call 954 FieldArrayInfo fd; 955 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL)); 956 if (t != T_OBJECT) { 957 k = Universe::typeArrayKlassObj(t); 958 } else { 959 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD); 960 } 961 if (k != NULL) { 962 k = k->array_klass_or_null(fd.dimension()); 963 } 964 } else { 965 k = find(class_name, class_loader, protection_domain, THREAD); 966 } 967 return k; 968 } 969 970 // Note: this method is much like resolve_from_stream, but 971 // updates no supplemental data structures. 972 // TODO consolidate the two methods with a helper routine? 973 Klass* SystemDictionary::parse_stream(Symbol* class_name, 974 Handle class_loader, 975 Handle protection_domain, 976 ClassFileStream* st, 977 KlassHandle host_klass, 978 GrowableArray<Handle>* cp_patches, 979 TRAPS) { 980 TempNewSymbol parsed_name = NULL; 981 982 Ticks class_load_start_time = Ticks::now(); 983 984 ClassLoaderData* loader_data; 985 if (host_klass.not_null()) { 986 // Create a new CLD for anonymous class, that uses the same class loader 987 // as the host_klass 988 guarantee(host_klass->class_loader() == class_loader(), "should be the same"); 989 guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping"); 990 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL); 991 loader_data->record_dependency(host_klass(), CHECK_NULL); 992 } else { 993 loader_data = ClassLoaderData::class_loader_data(class_loader()); 994 } 995 996 // Parse the stream. Note that we do this even though this klass might 997 // already be present in the SystemDictionary, otherwise we would not 998 // throw potential ClassFormatErrors. 999 // 1000 // Note: "name" is updated. 1001 1002 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name, 1003 loader_data, 1004 protection_domain, 1005 host_klass, 1006 cp_patches, 1007 parsed_name, 1008 true, 1009 THREAD); 1010 1011 1012 if (host_klass.not_null() && k.not_null()) { 1013 // If it's anonymous, initialize it now, since nobody else will. 1014 1015 { 1016 MutexLocker mu_r(Compile_lock, THREAD); 1017 1018 // Add to class hierarchy, initialize vtables, and do possible 1019 // deoptimizations. 1020 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block 1021 1022 // But, do not add to system dictionary. 1023 1024 // compiled code dependencies need to be validated anyway 1025 notice_modification(); 1026 } 1027 1028 // Rewrite and patch constant pool here. 1029 k->link_class(CHECK_NULL); 1030 if (cp_patches != NULL) { 1031 k->constants()->patch_resolved_references(cp_patches); 1032 } 1033 k->eager_initialize(CHECK_NULL); 1034 1035 // notify jvmti 1036 if (JvmtiExport::should_post_class_load()) { 1037 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1038 JvmtiExport::post_class_load((JavaThread *) THREAD, k()); 1039 } 1040 1041 post_class_load_event(class_load_start_time, k, class_loader); 1042 } 1043 assert(host_klass.not_null() || cp_patches == NULL, 1044 "cp_patches only found with host_klass"); 1045 1046 return k(); 1047 } 1048 1049 // Add a klass to the system from a stream (called by jni_DefineClass and 1050 // JVM_DefineClass). 1051 // Note: class_name can be NULL. In that case we do not know the name of 1052 // the class until we have parsed the stream. 1053 1054 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name, 1055 Handle class_loader, 1056 Handle protection_domain, 1057 ClassFileStream* st, 1058 bool verify, 1059 TRAPS) { 1060 1061 // Classloaders that support parallelism, e.g. bootstrap classloader, 1062 // or all classloaders with UnsyncloadClass do not acquire lock here 1063 bool DoObjectLock = true; 1064 if (is_parallelCapable(class_loader)) { 1065 DoObjectLock = false; 1066 } 1067 1068 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL); 1069 1070 // Make sure we are synchronized on the class loader before we proceed 1071 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1072 check_loader_lock_contention(lockObject, THREAD); 1073 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 1074 1075 TempNewSymbol parsed_name = NULL; 1076 1077 // Parse the stream. Note that we do this even though this klass might 1078 // already be present in the SystemDictionary, otherwise we would not 1079 // throw potential ClassFormatErrors. 1080 // 1081 // Note: "name" is updated. 1082 1083 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name, 1084 loader_data, 1085 protection_domain, 1086 parsed_name, 1087 verify, 1088 THREAD); 1089 1090 const char* pkg = "java/"; 1091 if (!HAS_PENDING_EXCEPTION && 1092 !class_loader.is_null() && 1093 parsed_name != NULL && 1094 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) { 1095 // It is illegal to define classes in the "java." package from 1096 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader 1097 ResourceMark rm(THREAD); 1098 char* name = parsed_name->as_C_string(); 1099 char* index = strrchr(name, '/'); 1100 *index = '\0'; // chop to just the package name 1101 while ((index = strchr(name, '/')) != NULL) { 1102 *index = '.'; // replace '/' with '.' in package name 1103 } 1104 const char* fmt = "Prohibited package name: %s"; 1105 size_t len = strlen(fmt) + strlen(name); 1106 char* message = NEW_RESOURCE_ARRAY(char, len); 1107 jio_snprintf(message, len, fmt, name); 1108 Exceptions::_throw_msg(THREAD_AND_LOCATION, 1109 vmSymbols::java_lang_SecurityException(), message); 1110 } 1111 1112 if (!HAS_PENDING_EXCEPTION) { 1113 assert(parsed_name != NULL, "Sanity"); 1114 assert(class_name == NULL || class_name == parsed_name, "name mismatch"); 1115 // Verification prevents us from creating names with dots in them, this 1116 // asserts that that's the case. 1117 assert(is_internal_format(parsed_name), 1118 "external class name format used internally"); 1119 1120 // Add class just loaded 1121 // If a class loader supports parallel classloading handle parallel define requests 1122 // find_or_define_instance_class may return a different InstanceKlass 1123 if (is_parallelCapable(class_loader)) { 1124 k = find_or_define_instance_class(class_name, class_loader, k, THREAD); 1125 } else { 1126 define_instance_class(k, THREAD); 1127 } 1128 } 1129 1130 // Make sure we have an entry in the SystemDictionary on success 1131 debug_only( { 1132 if (!HAS_PENDING_EXCEPTION) { 1133 assert(parsed_name != NULL, "parsed_name is still null?"); 1134 Symbol* h_name = k->name(); 1135 ClassLoaderData *defining_loader_data = k->class_loader_data(); 1136 1137 MutexLocker mu(SystemDictionary_lock, THREAD); 1138 1139 Klass* check = find_class(parsed_name, loader_data); 1140 assert(check == k(), "should be present in the dictionary"); 1141 1142 Klass* check2 = find_class(h_name, defining_loader_data); 1143 assert(check == check2, "name inconsistancy in SystemDictionary"); 1144 } 1145 } ); 1146 1147 return k(); 1148 } 1149 1150 #if INCLUDE_CDS 1151 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length, 1152 int number_of_entries) { 1153 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>), 1154 "bad shared dictionary size."); 1155 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries); 1156 } 1157 1158 1159 // If there is a shared dictionary, then find the entry for the 1160 // given shared system class, if any. 1161 1162 Klass* SystemDictionary::find_shared_class(Symbol* class_name) { 1163 if (shared_dictionary() != NULL) { 1164 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL); 1165 int d_index = shared_dictionary()->hash_to_index(d_hash); 1166 1167 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name); 1168 } else { 1169 return NULL; 1170 } 1171 } 1172 1173 1174 // Load a class from the shared spaces (found through the shared system 1175 // dictionary). Force the superclass and all interfaces to be loaded. 1176 // Update the class definition to include sibling classes and no 1177 // subclasses (yet). [Classes in the shared space are not part of the 1178 // object hierarchy until loaded.] 1179 1180 instanceKlassHandle SystemDictionary::load_shared_class( 1181 Symbol* class_name, Handle class_loader, TRAPS) { 1182 instanceKlassHandle ik (THREAD, find_shared_class(class_name)); 1183 // Make sure we only return the boot class for the NULL classloader. 1184 if (ik.not_null() && 1185 SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) { 1186 Handle protection_domain; 1187 return load_shared_class(ik, class_loader, protection_domain, THREAD); 1188 } 1189 return instanceKlassHandle(); 1190 } 1191 1192 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik, 1193 Handle class_loader, 1194 Handle protection_domain, TRAPS) { 1195 if (ik.not_null()) { 1196 instanceKlassHandle nh = instanceKlassHandle(); // null Handle 1197 Symbol* class_name = ik->name(); 1198 1199 // Found the class, now load the superclass and interfaces. If they 1200 // are shared, add them to the main system dictionary and reset 1201 // their hierarchy references (supers, subs, and interfaces). 1202 1203 if (ik->super() != NULL) { 1204 Symbol* cn = ik->super()->name(); 1205 resolve_super_or_fail(class_name, cn, 1206 class_loader, protection_domain, true, CHECK_(nh)); 1207 } 1208 1209 Array<Klass*>* interfaces = ik->local_interfaces(); 1210 int num_interfaces = interfaces->length(); 1211 for (int index = 0; index < num_interfaces; index++) { 1212 Klass* k = interfaces->at(index); 1213 1214 // Note: can not use InstanceKlass::cast here because 1215 // interfaces' InstanceKlass's C++ vtbls haven't been 1216 // reinitialized yet (they will be once the interface classes 1217 // are loaded) 1218 Symbol* name = k->name(); 1219 resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh)); 1220 } 1221 1222 // Adjust methods to recover missing data. They need addresses for 1223 // interpreter entry points and their default native method address 1224 // must be reset. 1225 1226 // Updating methods must be done under a lock so multiple 1227 // threads don't update these in parallel 1228 // 1229 // Shared classes are all currently loaded by either the bootstrap or 1230 // internal parallel class loaders, so this will never cause a deadlock 1231 // on a custom class loader lock. 1232 1233 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader()); 1234 { 1235 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1236 check_loader_lock_contention(lockObject, THREAD); 1237 ObjectLocker ol(lockObject, THREAD, true); 1238 ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh)); 1239 } 1240 1241 if (TraceClassLoading) { 1242 ResourceMark rm; 1243 tty->print("[Loaded %s", ik->external_name()); 1244 tty->print(" from shared objects file"); 1245 if (class_loader.not_null()) { 1246 tty->print(" by %s", loader_data->loader_name()); 1247 } 1248 tty->print_cr("]"); 1249 } 1250 1251 if (DumpLoadedClassList != NULL && classlist_file->is_open()) { 1252 // Only dump the classes that can be stored into CDS archive 1253 if (SystemDictionaryShared::is_sharing_possible(loader_data)) { 1254 ResourceMark rm(THREAD); 1255 classlist_file->print_cr("%s", ik->name()->as_C_string()); 1256 classlist_file->flush(); 1257 } 1258 } 1259 1260 // notify a class loaded from shared object 1261 ClassLoadingService::notify_class_loaded(ik(), 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 1713 // Unload deallocated backtraces 1714 BacktraceList::unlink(is_alive); 1715 return unloading_occurred; 1716 } 1717 1718 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) { 1719 strong->do_oop(&_java_system_loader); 1720 strong->do_oop(&_system_loader_lock_obj); 1721 CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);) 1722 1723 // Adjust dictionary 1724 dictionary()->roots_oops_do(strong, weak); 1725 1726 // Visit extra methods 1727 invoke_method_table()->oops_do(strong); 1728 1729 // BacktraceList are weak roots 1730 if (weak != NULL) { 1731 BacktraceList::oops_do(weak); 1732 } 1733 } 1734 1735 void SystemDictionary::oops_do(OopClosure* f) { 1736 f->do_oop(&_java_system_loader); 1737 f->do_oop(&_system_loader_lock_obj); 1738 CDS_ONLY(SystemDictionaryShared::oops_do(f);) 1739 1740 // Adjust dictionary 1741 dictionary()->oops_do(f); 1742 1743 // Visit extra methods 1744 invoke_method_table()->oops_do(f); 1745 1746 // BacktraceList are weak roots 1747 BacktraceList::oops_do(f); 1748 } 1749 1750 // Extended Class redefinition support. 1751 // If one of these classes is replaced, we need to replace it in these places. 1752 // KlassClosure::do_klass should take the address of a class but we can 1753 // change that later. 1754 void SystemDictionary::preloaded_classes_do(KlassClosure* f) { 1755 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) { 1756 f->do_klass(_well_known_klasses[k]); 1757 } 1758 1759 { 1760 for (int i = 0; i < T_VOID+1; i++) { 1761 if (_box_klasses[i] != NULL) { 1762 assert(i >= T_BOOLEAN, "checking"); 1763 f->do_klass(_box_klasses[i]); 1764 } 1765 } 1766 } 1767 1768 FilteredFieldsMap::classes_do(f); 1769 } 1770 1771 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) { 1772 f->do_klass(_abstract_ownable_synchronizer_klass); 1773 } 1774 1775 // Just the classes from defining class loaders 1776 // Don't iterate over placeholders 1777 void SystemDictionary::classes_do(void f(Klass*)) { 1778 dictionary()->classes_do(f); 1779 } 1780 1781 // Added for initialize_itable_for_klass 1782 // Just the classes from defining class loaders 1783 // Don't iterate over placeholders 1784 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) { 1785 dictionary()->classes_do(f, CHECK); 1786 } 1787 1788 // All classes, and their class loaders 1789 // Don't iterate over placeholders 1790 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) { 1791 dictionary()->classes_do(f); 1792 } 1793 1794 void SystemDictionary::placeholders_do(void f(Symbol*)) { 1795 placeholders()->entries_do(f); 1796 } 1797 1798 void SystemDictionary::methods_do(void f(Method*)) { 1799 dictionary()->methods_do(f); 1800 invoke_method_table()->methods_do(f); 1801 } 1802 1803 void SystemDictionary::remove_classes_in_error_state() { 1804 dictionary()->remove_classes_in_error_state(); 1805 } 1806 1807 // ---------------------------------------------------------------------------- 1808 // Lazily load klasses 1809 1810 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) { 1811 // if multiple threads calling this function, only one thread will load 1812 // the class. The other threads will find the loaded version once the 1813 // class is loaded. 1814 Klass* aos = _abstract_ownable_synchronizer_klass; 1815 if (aos == NULL) { 1816 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK); 1817 // Force a fence to prevent any read before the write completes 1818 OrderAccess::fence(); 1819 _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k); 1820 } 1821 } 1822 1823 // ---------------------------------------------------------------------------- 1824 // Initialization 1825 1826 void SystemDictionary::initialize(TRAPS) { 1827 // Allocate arrays 1828 assert(dictionary() == NULL, 1829 "SystemDictionary should only be initialized once"); 1830 _sdgeneration = 0; 1831 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount)); 1832 _placeholders = new PlaceholderTable(_nof_buckets); 1833 _number_of_modifications = 0; 1834 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size); 1835 _resolution_errors = new ResolutionErrorTable(_resolution_error_size); 1836 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size); 1837 1838 // Allocate private object used as system class loader lock 1839 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK); 1840 // Initialize basic classes 1841 initialize_preloaded_classes(CHECK); 1842 } 1843 1844 // Compact table of directions on the initialization of klasses: 1845 static const short wk_init_info[] = { 1846 #define WK_KLASS_INIT_INFO(name, symbol, option) \ 1847 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \ 1848 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \ 1849 | (int)SystemDictionary::option ), 1850 WK_KLASSES_DO(WK_KLASS_INIT_INFO) 1851 #undef WK_KLASS_INIT_INFO 1852 0 1853 }; 1854 1855 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) { 1856 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 1857 int info = wk_init_info[id - FIRST_WKID]; 1858 int sid = (info >> CEIL_LG_OPTION_LIMIT); 1859 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid); 1860 InstanceKlass** klassp = &_well_known_klasses[id]; 1861 bool must_load = (init_opt < SystemDictionary::Opt); 1862 if ((*klassp) == NULL) { 1863 Klass* k; 1864 if (must_load) { 1865 k = resolve_or_fail(symbol, true, CHECK_0); // load required class 1866 } else { 1867 k = resolve_or_null(symbol, CHECK_0); // load optional klass 1868 } 1869 (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k); 1870 } 1871 return ((*klassp) != NULL); 1872 } 1873 1874 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) { 1875 assert((int)start_id <= (int)limit_id, "IDs are out of order!"); 1876 for (int id = (int)start_id; id < (int)limit_id; id++) { 1877 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 1878 int info = wk_init_info[id - FIRST_WKID]; 1879 int sid = (info >> CEIL_LG_OPTION_LIMIT); 1880 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT)); 1881 1882 initialize_wk_klass((WKID)id, opt, CHECK); 1883 } 1884 1885 // move the starting value forward to the limit: 1886 start_id = limit_id; 1887 } 1888 1889 void SystemDictionary::initialize_preloaded_classes(TRAPS) { 1890 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once"); 1891 // Preload commonly used klasses 1892 WKID scan = FIRST_WKID; 1893 // first do Object, then String, Class 1894 if (UseSharedSpaces) { 1895 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK); 1896 // Initialize the constant pool for the Object_class 1897 InstanceKlass* ik = InstanceKlass::cast(Object_klass()); 1898 ik->constants()->restore_unshareable_info(CHECK); 1899 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 1900 } else { 1901 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 1902 } 1903 1904 // Calculate offsets for String and Class classes since they are loaded and 1905 // can be used after this point. 1906 java_lang_String::compute_offsets(); 1907 java_lang_Class::compute_offsets(); 1908 1909 // Fixup mirrors for classes loaded before java.lang.Class. 1910 // These calls iterate over the objects currently in the perm gen 1911 // so calling them at this point is matters (not before when there 1912 // are fewer objects and not later after there are more objects 1913 // in the perm gen. 1914 Universe::initialize_basic_type_mirrors(CHECK); 1915 Universe::fixup_mirrors(CHECK); 1916 1917 // do a bunch more: 1918 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK); 1919 1920 // Preload ref klasses and set reference types 1921 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER); 1922 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass)); 1923 1924 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK); 1925 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT); 1926 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK); 1927 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL); 1928 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM); 1929 InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER); 1930 1931 // JSR 292 classes 1932 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass); 1933 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass); 1934 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK); 1935 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK); 1936 initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK); 1937 1938 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass); 1939 _box_klasses[T_CHAR] = WK_KLASS(Character_klass); 1940 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass); 1941 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass); 1942 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass); 1943 _box_klasses[T_SHORT] = WK_KLASS(Short_klass); 1944 _box_klasses[T_INT] = WK_KLASS(Integer_klass); 1945 _box_klasses[T_LONG] = WK_KLASS(Long_klass); 1946 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass); 1947 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass); 1948 1949 { // Compute whether we should use loadClass or loadClassInternal when loading classes. 1950 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature()); 1951 _has_loadClassInternal = (method != NULL); 1952 } 1953 { // Compute whether we should use checkPackageAccess or NOT 1954 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature()); 1955 _has_checkPackageAccess = (method != NULL); 1956 } 1957 } 1958 1959 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer). 1960 // If so, returns the basic type it holds. If not, returns T_OBJECT. 1961 BasicType SystemDictionary::box_klass_type(Klass* k) { 1962 assert(k != NULL, ""); 1963 for (int i = T_BOOLEAN; i < T_VOID+1; i++) { 1964 if (_box_klasses[i] == k) 1965 return (BasicType)i; 1966 } 1967 return T_OBJECT; 1968 } 1969 1970 // Constraints on class loaders. The details of the algorithm can be 1971 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java 1972 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is 1973 // that the system dictionary needs to maintain a set of contraints that 1974 // must be satisfied by all classes in the dictionary. 1975 // if defining is true, then LinkageError if already in systemDictionary 1976 // if initiating loader, then ok if InstanceKlass matches existing entry 1977 1978 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash, 1979 instanceKlassHandle k, 1980 Handle class_loader, bool defining, 1981 TRAPS) { 1982 const char *linkage_error1 = NULL; 1983 const char *linkage_error2 = NULL; 1984 { 1985 Symbol* name = k->name(); 1986 ClassLoaderData *loader_data = class_loader_data(class_loader); 1987 1988 MutexLocker mu(SystemDictionary_lock, THREAD); 1989 1990 Klass* check = find_class(d_index, d_hash, name, loader_data); 1991 if (check != (Klass*)NULL) { 1992 // if different InstanceKlass - duplicate class definition, 1993 // else - ok, class loaded by a different thread in parallel, 1994 // we should only have found it if it was done loading and ok to use 1995 // system dictionary only holds instance classes, placeholders 1996 // also holds array classes 1997 1998 assert(check->is_instance_klass(), "noninstance in systemdictionary"); 1999 if ((defining == true) || (k() != check)) { 2000 linkage_error1 = "loader (instance of "; 2001 linkage_error2 = "): attempted duplicate class definition for name: \""; 2002 } else { 2003 return; 2004 } 2005 } 2006 2007 #ifdef ASSERT 2008 Symbol* ph_check = find_placeholder(name, loader_data); 2009 assert(ph_check == NULL || ph_check == name, "invalid symbol"); 2010 #endif 2011 2012 if (linkage_error1 == NULL) { 2013 if (constraints()->check_or_update(k, class_loader, name) == false) { 2014 linkage_error1 = "loader constraint violation: loader (instance of "; 2015 linkage_error2 = ") previously initiated loading for a different type with name \""; 2016 } 2017 } 2018 } 2019 2020 // Throw error now if needed (cannot throw while holding 2021 // SystemDictionary_lock because of rank ordering) 2022 2023 if (linkage_error1) { 2024 ResourceMark rm(THREAD); 2025 const char* class_loader_name = loader_name(class_loader()); 2026 char* type_name = k->name()->as_C_string(); 2027 size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) + 2028 strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte. 2029 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen); 2030 jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name); 2031 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf); 2032 } 2033 } 2034 2035 2036 // Update system dictionary - done after check_constraint and add_to_hierachy 2037 // have been called. 2038 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash, 2039 int p_index, unsigned int p_hash, 2040 instanceKlassHandle k, 2041 Handle class_loader, 2042 TRAPS) { 2043 // Compile_lock prevents systemDictionary updates during compilations 2044 assert_locked_or_safepoint(Compile_lock); 2045 Symbol* name = k->name(); 2046 ClassLoaderData *loader_data = class_loader_data(class_loader); 2047 2048 { 2049 MutexLocker mu1(SystemDictionary_lock, THREAD); 2050 2051 // See whether biased locking is enabled and if so set it for this 2052 // klass. 2053 // Note that this must be done past the last potential blocking 2054 // point / safepoint. We enable biased locking lazily using a 2055 // VM_Operation to iterate the SystemDictionary and installing the 2056 // biasable mark word into each InstanceKlass's prototype header. 2057 // To avoid race conditions where we accidentally miss enabling the 2058 // optimization for one class in the process of being added to the 2059 // dictionary, we must not safepoint after the test of 2060 // BiasedLocking::enabled(). 2061 if (UseBiasedLocking && BiasedLocking::enabled()) { 2062 // Set biased locking bit for all loaded classes; it will be 2063 // cleared if revocation occurs too often for this type 2064 // NOTE that we must only do this when the class is initally 2065 // defined, not each time it is referenced from a new class loader 2066 if (k->class_loader() == class_loader()) { 2067 k->set_prototype_header(markOopDesc::biased_locking_prototype()); 2068 } 2069 } 2070 2071 // Make a new system dictionary entry. 2072 Klass* sd_check = find_class(d_index, d_hash, name, loader_data); 2073 if (sd_check == NULL) { 2074 dictionary()->add_klass(name, loader_data, k); 2075 notice_modification(); 2076 } 2077 #ifdef ASSERT 2078 sd_check = find_class(d_index, d_hash, name, loader_data); 2079 assert (sd_check != NULL, "should have entry in system dictionary"); 2080 // Note: there may be a placeholder entry: for circularity testing 2081 // or for parallel defines 2082 #endif 2083 SystemDictionary_lock->notify_all(); 2084 } 2085 } 2086 2087 2088 // Try to find a class name using the loader constraints. The 2089 // loader constraints might know about a class that isn't fully loaded 2090 // yet and these will be ignored. 2091 Klass* SystemDictionary::find_constrained_instance_or_array_klass( 2092 Symbol* class_name, Handle class_loader, TRAPS) { 2093 2094 // First see if it has been loaded directly. 2095 // Force the protection domain to be null. (This removes protection checks.) 2096 Handle no_protection_domain; 2097 Klass* klass = find_instance_or_array_klass(class_name, class_loader, 2098 no_protection_domain, CHECK_NULL); 2099 if (klass != NULL) 2100 return klass; 2101 2102 // Now look to see if it has been loaded elsewhere, and is subject to 2103 // a loader constraint that would require this loader to return the 2104 // klass that is already loaded. 2105 if (FieldType::is_array(class_name)) { 2106 // For array classes, their Klass*s are not kept in the 2107 // constraint table. The element Klass*s are. 2108 FieldArrayInfo fd; 2109 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL)); 2110 if (t != T_OBJECT) { 2111 klass = Universe::typeArrayKlassObj(t); 2112 } else { 2113 MutexLocker mu(SystemDictionary_lock, THREAD); 2114 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader); 2115 } 2116 // If element class already loaded, allocate array klass 2117 if (klass != NULL) { 2118 klass = klass->array_klass_or_null(fd.dimension()); 2119 } 2120 } else { 2121 MutexLocker mu(SystemDictionary_lock, THREAD); 2122 // Non-array classes are easy: simply check the constraint table. 2123 klass = constraints()->find_constrained_klass(class_name, class_loader); 2124 } 2125 2126 return klass; 2127 } 2128 2129 2130 bool SystemDictionary::add_loader_constraint(Symbol* class_name, 2131 Handle class_loader1, 2132 Handle class_loader2, 2133 Thread* THREAD) { 2134 ClassLoaderData* loader_data1 = class_loader_data(class_loader1); 2135 ClassLoaderData* loader_data2 = class_loader_data(class_loader2); 2136 2137 Symbol* constraint_name = NULL; 2138 if (!FieldType::is_array(class_name)) { 2139 constraint_name = class_name; 2140 } else { 2141 // For array classes, their Klass*s are not kept in the 2142 // constraint table. The element classes are. 2143 FieldArrayInfo fd; 2144 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false)); 2145 // primitive types always pass 2146 if (t != T_OBJECT) { 2147 return true; 2148 } else { 2149 constraint_name = fd.object_key(); 2150 } 2151 } 2152 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1); 2153 int d_index1 = dictionary()->hash_to_index(d_hash1); 2154 2155 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2); 2156 int d_index2 = dictionary()->hash_to_index(d_hash2); 2157 { 2158 MutexLocker mu_s(SystemDictionary_lock, THREAD); 2159 2160 // Better never do a GC while we're holding these oops 2161 No_Safepoint_Verifier nosafepoint; 2162 2163 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1); 2164 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2); 2165 return constraints()->add_entry(constraint_name, klass1, class_loader1, 2166 klass2, class_loader2); 2167 } 2168 } 2169 2170 // Add entry to resolution error table to record the error when the first 2171 // attempt to resolve a reference to a class has failed. 2172 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which, 2173 Symbol* error, Symbol* message) { 2174 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2175 int index = resolution_errors()->hash_to_index(hash); 2176 { 2177 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2178 resolution_errors()->add_entry(index, hash, pool, which, error, message); 2179 } 2180 } 2181 2182 // Delete a resolution error for RedefineClasses for a constant pool is going away 2183 void SystemDictionary::delete_resolution_error(ConstantPool* pool) { 2184 resolution_errors()->delete_entry(pool); 2185 } 2186 2187 // Lookup resolution error table. Returns error if found, otherwise NULL. 2188 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which, 2189 Symbol** message) { 2190 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2191 int index = resolution_errors()->hash_to_index(hash); 2192 { 2193 MutexLocker ml(SystemDictionary_lock, Thread::current()); 2194 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which); 2195 if (entry != NULL) { 2196 *message = entry->message(); 2197 return entry->error(); 2198 } else { 2199 return NULL; 2200 } 2201 } 2202 } 2203 2204 2205 // Signature constraints ensure that callers and callees agree about 2206 // the meaning of type names in their signatures. This routine is the 2207 // intake for constraints. It collects them from several places: 2208 // 2209 // * LinkResolver::resolve_method (if check_access is true) requires 2210 // that the resolving class (the caller) and the defining class of 2211 // the resolved method (the callee) agree on each type in the 2212 // method's signature. 2213 // 2214 // * LinkResolver::resolve_interface_method performs exactly the same 2215 // checks. 2216 // 2217 // * LinkResolver::resolve_field requires that the constant pool 2218 // attempting to link to a field agree with the field's defining 2219 // class about the type of the field signature. 2220 // 2221 // * klassVtable::initialize_vtable requires that, when a class 2222 // overrides a vtable entry allocated by a superclass, that the 2223 // overriding method (i.e., the callee) agree with the superclass 2224 // on each type in the method's signature. 2225 // 2226 // * klassItable::initialize_itable requires that, when a class fills 2227 // in its itables, for each non-abstract method installed in an 2228 // itable, the method (i.e., the callee) agree with the interface 2229 // on each type in the method's signature. 2230 // 2231 // All those methods have a boolean (check_access, checkconstraints) 2232 // which turns off the checks. This is used from specialized contexts 2233 // such as bootstrapping, dumping, and debugging. 2234 // 2235 // No direct constraint is placed between the class and its 2236 // supertypes. Constraints are only placed along linked relations 2237 // between callers and callees. When a method overrides or implements 2238 // an abstract method in a supertype (superclass or interface), the 2239 // constraints are placed as if the supertype were the caller to the 2240 // overriding method. (This works well, since callers to the 2241 // supertype have already established agreement between themselves and 2242 // the supertype.) As a result of all this, a class can disagree with 2243 // its supertype about the meaning of a type name, as long as that 2244 // class neither calls a relevant method of the supertype, nor is 2245 // called (perhaps via an override) from the supertype. 2246 // 2247 // 2248 // SystemDictionary::check_signature_loaders(sig, l1, l2) 2249 // 2250 // Make sure all class components (including arrays) in the given 2251 // signature will be resolved to the same class in both loaders. 2252 // Returns the name of the type that failed a loader constraint check, or 2253 // NULL if no constraint failed. No exception except OOME is thrown. 2254 // Arrays are not added to the loader constraint table, their elements are. 2255 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature, 2256 Handle loader1, Handle loader2, 2257 bool is_method, TRAPS) { 2258 // Nothing to do if loaders are the same. 2259 if (loader1() == loader2()) { 2260 return NULL; 2261 } 2262 2263 SignatureStream sig_strm(signature, is_method); 2264 while (!sig_strm.is_done()) { 2265 if (sig_strm.is_object()) { 2266 Symbol* sig = sig_strm.as_symbol(CHECK_NULL); 2267 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) { 2268 return sig; 2269 } 2270 } 2271 sig_strm.next(); 2272 } 2273 return NULL; 2274 } 2275 2276 2277 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid, 2278 Symbol* signature, 2279 TRAPS) { 2280 methodHandle empty; 2281 assert(MethodHandles::is_signature_polymorphic(iid) && 2282 MethodHandles::is_signature_polymorphic_intrinsic(iid) && 2283 iid != vmIntrinsics::_invokeGeneric, 2284 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)); 2285 2286 unsigned int hash = invoke_method_table()->compute_hash(signature, iid); 2287 int index = invoke_method_table()->hash_to_index(hash); 2288 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid); 2289 methodHandle m; 2290 if (spe == NULL || spe->method() == NULL) { 2291 spe = NULL; 2292 // Must create lots of stuff here, but outside of the SystemDictionary lock. 2293 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty)); 2294 if (!Arguments::is_interpreter_only()) { 2295 // Generate a compiled form of the MH intrinsic. 2296 AdapterHandlerLibrary::create_native_wrapper(m); 2297 // Check if have the compiled code. 2298 if (!m->has_compiled_code()) { 2299 THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(), 2300 "out of space in CodeCache for method handle intrinsic", empty); 2301 } 2302 } 2303 // Now grab the lock. We might have to throw away the new method, 2304 // if a racing thread has managed to install one at the same time. 2305 { 2306 MutexLocker ml(SystemDictionary_lock, THREAD); 2307 spe = invoke_method_table()->find_entry(index, hash, signature, iid); 2308 if (spe == NULL) 2309 spe = invoke_method_table()->add_entry(index, hash, signature, iid); 2310 if (spe->method() == NULL) 2311 spe->set_method(m()); 2312 } 2313 } 2314 2315 assert(spe != NULL && spe->method() != NULL, ""); 2316 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() && 2317 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()), 2318 "MH intrinsic invariant"); 2319 return spe->method(); 2320 } 2321 2322 // Helper for unpacking the return value from linkMethod and linkCallSite. 2323 static methodHandle unpack_method_and_appendix(Handle mname, 2324 KlassHandle accessing_klass, 2325 objArrayHandle appendix_box, 2326 Handle* appendix_result, 2327 TRAPS) { 2328 methodHandle empty; 2329 if (mname.not_null()) { 2330 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname()); 2331 if (vmtarget != NULL && vmtarget->is_method()) { 2332 Method* m = (Method*)vmtarget; 2333 oop appendix = appendix_box->obj_at(0); 2334 if (TraceMethodHandles) { 2335 #ifndef PRODUCT 2336 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m)); 2337 m->print(); 2338 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); } 2339 tty->cr(); 2340 #endif //PRODUCT 2341 } 2342 (*appendix_result) = Handle(THREAD, appendix); 2343 // the target is stored in the cpCache and if a reference to this 2344 // MethodName is dropped we need a way to make sure the 2345 // class_loader containing this method is kept alive. 2346 // FIXME: the appendix might also preserve this dependency. 2347 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data(); 2348 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM 2349 return methodHandle(THREAD, m); 2350 } 2351 } 2352 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty); 2353 return empty; 2354 } 2355 2356 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name, 2357 Symbol* signature, 2358 KlassHandle accessing_klass, 2359 Handle *appendix_result, 2360 Handle *method_type_result, 2361 TRAPS) { 2362 methodHandle empty; 2363 assert(THREAD->can_call_java() ,""); 2364 Handle method_type = 2365 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty)); 2366 2367 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass(); 2368 int ref_kind = JVM_REF_invokeVirtual; 2369 Handle name_str = StringTable::intern(name, CHECK_(empty)); 2370 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty)); 2371 assert(appendix_box->obj_at(0) == NULL, ""); 2372 2373 // This should not happen. JDK code should take care of that. 2374 if (accessing_klass.is_null() || method_type.is_null()) { 2375 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty); 2376 } 2377 2378 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName 2379 JavaCallArguments args; 2380 args.push_oop(accessing_klass()->java_mirror()); 2381 args.push_int(ref_kind); 2382 args.push_oop(mh_klass()->java_mirror()); 2383 args.push_oop(name_str()); 2384 args.push_oop(method_type()); 2385 args.push_oop(appendix_box()); 2386 JavaValue result(T_OBJECT); 2387 JavaCalls::call_static(&result, 2388 SystemDictionary::MethodHandleNatives_klass(), 2389 vmSymbols::linkMethod_name(), 2390 vmSymbols::linkMethod_signature(), 2391 &args, CHECK_(empty)); 2392 Handle mname(THREAD, (oop) result.get_jobject()); 2393 (*method_type_result) = method_type; 2394 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD); 2395 } 2396 2397 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks. 2398 // We must ensure that all class loaders everywhere will reach this class, for any client. 2399 // This is a safe bet for public classes in java.lang, such as Object and String. 2400 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types. 2401 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util. 2402 static bool is_always_visible_class(oop mirror) { 2403 Klass* klass = java_lang_Class::as_Klass(mirror); 2404 if (klass->is_objArray_klass()) { 2405 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type 2406 } 2407 if (klass->is_typeArray_klass()) { 2408 return true; // primitive array 2409 } 2410 assert(klass->is_instance_klass(), "%s", klass->external_name()); 2411 return klass->is_public() && 2412 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang 2413 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke 2414 } 2415 2416 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given 2417 // signature, as interpreted relative to the given class loader. 2418 // Because of class loader constraints, all method handle usage must be 2419 // consistent with this loader. 2420 Handle SystemDictionary::find_method_handle_type(Symbol* signature, 2421 KlassHandle accessing_klass, 2422 TRAPS) { 2423 Handle empty; 2424 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics 2425 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid); 2426 int index = invoke_method_table()->hash_to_index(hash); 2427 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2428 if (spe != NULL && spe->method_type() != NULL) { 2429 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), ""); 2430 return Handle(THREAD, spe->method_type()); 2431 } else if (!THREAD->can_call_java()) { 2432 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME 2433 return Handle(); // do not attempt from within compiler, unless it was cached 2434 } 2435 2436 Handle class_loader, protection_domain; 2437 if (accessing_klass.not_null()) { 2438 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader()); 2439 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain()); 2440 } 2441 bool can_be_cached = true; 2442 int npts = ArgumentCount(signature).size(); 2443 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty)); 2444 int arg = 0; 2445 Handle rt; // the return type from the signature 2446 ResourceMark rm(THREAD); 2447 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) { 2448 oop mirror = NULL; 2449 if (can_be_cached) { 2450 // Use neutral class loader to lookup candidate classes to be placed in the cache. 2451 mirror = ss.as_java_mirror(Handle(), Handle(), 2452 SignatureStream::ReturnNull, CHECK_(empty)); 2453 if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) { 2454 // Fall back to accessing_klass context. 2455 can_be_cached = false; 2456 } 2457 } 2458 if (!can_be_cached) { 2459 // Resolve, throwing a real error if it doesn't work. 2460 mirror = ss.as_java_mirror(class_loader, protection_domain, 2461 SignatureStream::NCDFError, CHECK_(empty)); 2462 } 2463 assert(!oopDesc::is_null(mirror), "%s", ss.as_symbol(THREAD)->as_C_string()); 2464 if (ss.at_return_type()) 2465 rt = Handle(THREAD, mirror); 2466 else 2467 pts->obj_at_put(arg++, mirror); 2468 2469 // Check accessibility. 2470 if (ss.is_object() && accessing_klass.not_null()) { 2471 Klass* sel_klass = java_lang_Class::as_Klass(mirror); 2472 mirror = NULL; // safety 2473 // Emulate ConstantPool::verify_constant_pool_resolve. 2474 if (sel_klass->is_objArray_klass()) 2475 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass(); 2476 if (sel_klass->is_instance_klass()) { 2477 KlassHandle sel_kh(THREAD, sel_klass); 2478 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty)); 2479 } 2480 } 2481 } 2482 assert(arg == npts, ""); 2483 2484 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType 2485 JavaCallArguments args(Handle(THREAD, rt())); 2486 args.push_oop(pts()); 2487 JavaValue result(T_OBJECT); 2488 JavaCalls::call_static(&result, 2489 SystemDictionary::MethodHandleNatives_klass(), 2490 vmSymbols::findMethodHandleType_name(), 2491 vmSymbols::findMethodHandleType_signature(), 2492 &args, CHECK_(empty)); 2493 Handle method_type(THREAD, (oop) result.get_jobject()); 2494 2495 if (can_be_cached) { 2496 // We can cache this MethodType inside the JVM. 2497 MutexLocker ml(SystemDictionary_lock, THREAD); 2498 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2499 if (spe == NULL) 2500 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid); 2501 if (spe->method_type() == NULL) { 2502 spe->set_method_type(method_type()); 2503 } 2504 } 2505 2506 // report back to the caller with the MethodType 2507 return method_type; 2508 } 2509 2510 // Ask Java code to find or construct a method handle constant. 2511 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller, 2512 int ref_kind, //e.g., JVM_REF_invokeVirtual 2513 KlassHandle callee, 2514 Symbol* name_sym, 2515 Symbol* signature, 2516 TRAPS) { 2517 Handle empty; 2518 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty)); 2519 Handle type; 2520 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') { 2521 type = find_method_handle_type(signature, caller, CHECK_(empty)); 2522 } else if (caller.is_null()) { 2523 // This should not happen. JDK code should take care of that. 2524 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty); 2525 } else { 2526 ResourceMark rm(THREAD); 2527 SignatureStream ss(signature, false); 2528 if (!ss.is_done()) { 2529 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(), 2530 SignatureStream::NCDFError, CHECK_(empty)); 2531 type = Handle(THREAD, mirror); 2532 ss.next(); 2533 if (!ss.is_done()) type = Handle(); // error! 2534 } 2535 } 2536 if (type.is_null()) { 2537 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty); 2538 } 2539 2540 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle 2541 JavaCallArguments args; 2542 args.push_oop(caller->java_mirror()); // the referring class 2543 args.push_int(ref_kind); 2544 args.push_oop(callee->java_mirror()); // the target class 2545 args.push_oop(name()); 2546 args.push_oop(type()); 2547 JavaValue result(T_OBJECT); 2548 JavaCalls::call_static(&result, 2549 SystemDictionary::MethodHandleNatives_klass(), 2550 vmSymbols::linkMethodHandleConstant_name(), 2551 vmSymbols::linkMethodHandleConstant_signature(), 2552 &args, CHECK_(empty)); 2553 return Handle(THREAD, (oop) result.get_jobject()); 2554 } 2555 2556 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given 2557 // name and signature, as interpreted relative to the given class loader. 2558 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller, 2559 Handle bootstrap_specifier, 2560 Symbol* name, 2561 Symbol* type, 2562 Handle *appendix_result, 2563 Handle *method_type_result, 2564 TRAPS) { 2565 methodHandle empty; 2566 Handle bsm, info; 2567 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) { 2568 bsm = bootstrap_specifier; 2569 } else { 2570 assert(bootstrap_specifier->is_objArray(), ""); 2571 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier()); 2572 int len = args->length(); 2573 assert(len >= 1, ""); 2574 bsm = Handle(THREAD, args->obj_at(0)); 2575 if (len > 1) { 2576 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty)); 2577 for (int i = 1; i < len; i++) 2578 args1->obj_at_put(i-1, args->obj_at(i)); 2579 info = Handle(THREAD, args1); 2580 } 2581 } 2582 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()), 2583 "caller must supply a valid BSM"); 2584 2585 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty)); 2586 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty)); 2587 2588 // This should not happen. JDK code should take care of that. 2589 if (caller.is_null() || method_type.is_null()) { 2590 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty); 2591 } 2592 2593 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty)); 2594 assert(appendix_box->obj_at(0) == NULL, ""); 2595 2596 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix) 2597 JavaCallArguments args; 2598 args.push_oop(caller->java_mirror()); 2599 args.push_oop(bsm()); 2600 args.push_oop(method_name()); 2601 args.push_oop(method_type()); 2602 args.push_oop(info()); 2603 args.push_oop(appendix_box); 2604 JavaValue result(T_OBJECT); 2605 JavaCalls::call_static(&result, 2606 SystemDictionary::MethodHandleNatives_klass(), 2607 vmSymbols::linkCallSite_name(), 2608 vmSymbols::linkCallSite_signature(), 2609 &args, CHECK_(empty)); 2610 Handle mname(THREAD, (oop) result.get_jobject()); 2611 (*method_type_result) = method_type; 2612 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD); 2613 } 2614 2615 // Since the identity hash code for symbols changes when the symbols are 2616 // moved from the regular perm gen (hash in the mark word) to the shared 2617 // spaces (hash is the address), the classes loaded into the dictionary 2618 // may be in the wrong buckets. 2619 2620 void SystemDictionary::reorder_dictionary() { 2621 dictionary()->reorder_dictionary(); 2622 } 2623 2624 2625 void SystemDictionary::copy_buckets(char** top, char* end) { 2626 dictionary()->copy_buckets(top, end); 2627 } 2628 2629 2630 void SystemDictionary::copy_table(char** top, char* end) { 2631 dictionary()->copy_table(top, end); 2632 } 2633 2634 2635 void SystemDictionary::reverse() { 2636 dictionary()->reverse(); 2637 } 2638 2639 int SystemDictionary::number_of_classes() { 2640 return dictionary()->number_of_entries(); 2641 } 2642 2643 2644 // ---------------------------------------------------------------------------- 2645 void SystemDictionary::print_shared(bool details) { 2646 shared_dictionary()->print(details); 2647 } 2648 2649 void SystemDictionary::print(bool details) { 2650 dictionary()->print(details); 2651 2652 // Placeholders 2653 GCMutexLocker mu(SystemDictionary_lock); 2654 placeholders()->print(); 2655 2656 // loader constraints - print under SD_lock 2657 constraints()->print(); 2658 } 2659 2660 2661 void SystemDictionary::verify() { 2662 guarantee(dictionary() != NULL, "Verify of system dictionary failed"); 2663 guarantee(constraints() != NULL, 2664 "Verify of loader constraints failed"); 2665 guarantee(dictionary()->number_of_entries() >= 0 && 2666 placeholders()->number_of_entries() >= 0, 2667 "Verify of system dictionary failed"); 2668 2669 // Verify dictionary 2670 dictionary()->verify(); 2671 2672 GCMutexLocker mu(SystemDictionary_lock); 2673 placeholders()->verify(); 2674 2675 // Verify constraint table 2676 guarantee(constraints() != NULL, "Verify of loader constraints failed"); 2677 constraints()->verify(dictionary(), placeholders()); 2678 } 2679 2680 // utility function for class load event 2681 void SystemDictionary::post_class_load_event(const Ticks& start_time, 2682 instanceKlassHandle k, 2683 Handle initiating_loader) { 2684 #if INCLUDE_TRACE 2685 EventClassLoad event(UNTIMED); 2686 if (event.should_commit()) { 2687 event.set_starttime(start_time); 2688 event.set_loadedClass(k()); 2689 oop defining_class_loader = k->class_loader(); 2690 event.set_definingClassLoader(defining_class_loader != NULL ? 2691 defining_class_loader->klass() : (Klass*)NULL); 2692 oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader(); 2693 event.set_initiatingClassLoader(class_loader != NULL ? 2694 class_loader->klass() : (Klass*)NULL); 2695 event.commit(); 2696 } 2697 #endif // INCLUDE_TRACE 2698 } 2699