1 /* 2 * Copyright (c) 1997, 2020, 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 "jvm.h" 27 #include "aot/aotLoader.hpp" 28 #include "classfile/classFileParser.hpp" 29 #include "classfile/classFileStream.hpp" 30 #include "classfile/classLoader.hpp" 31 #include "classfile/classLoaderData.inline.hpp" 32 #include "classfile/classLoaderDataGraph.inline.hpp" 33 #include "classfile/classLoaderExt.hpp" 34 #include "classfile/dictionary.hpp" 35 #include "classfile/javaClasses.inline.hpp" 36 #include "classfile/klassFactory.hpp" 37 #include "classfile/loaderConstraints.hpp" 38 #include "classfile/packageEntry.hpp" 39 #include "classfile/placeholders.hpp" 40 #include "classfile/protectionDomainCache.hpp" 41 #include "classfile/resolutionErrors.hpp" 42 #include "classfile/stringTable.hpp" 43 #include "classfile/symbolTable.hpp" 44 #include "classfile/systemDictionary.hpp" 45 #include "classfile/vmSymbols.hpp" 46 #include "code/codeCache.hpp" 47 #include "compiler/compileBroker.hpp" 48 #include "gc/shared/gcTraceTime.inline.hpp" 49 #include "gc/shared/oopStorage.inline.hpp" 50 #include "gc/shared/oopStorageSet.hpp" 51 #include "interpreter/bytecodeStream.hpp" 52 #include "interpreter/interpreter.hpp" 53 #include "jfr/jfrEvents.hpp" 54 #include "logging/log.hpp" 55 #include "logging/logStream.hpp" 56 #include "memory/filemap.hpp" 57 #include "memory/heapShared.hpp" 58 #include "memory/metaspaceClosure.hpp" 59 #include "memory/oopFactory.hpp" 60 #include "memory/resourceArea.hpp" 61 #include "memory/universe.hpp" 62 #include "oops/access.inline.hpp" 63 #include "oops/instanceKlass.hpp" 64 #include "oops/instanceRefKlass.hpp" 65 #include "oops/klass.inline.hpp" 66 #include "oops/method.inline.hpp" 67 #include "oops/methodData.hpp" 68 #include "oops/objArrayKlass.hpp" 69 #include "oops/objArrayOop.inline.hpp" 70 #include "oops/oop.inline.hpp" 71 #include "oops/symbol.hpp" 72 #include "oops/typeArrayKlass.hpp" 73 #include "prims/jvmtiExport.hpp" 74 #include "prims/methodHandles.hpp" 75 #include "runtime/arguments.hpp" 76 #include "runtime/biasedLocking.hpp" 77 #include "runtime/handles.inline.hpp" 78 #include "runtime/java.hpp" 79 #include "runtime/javaCalls.hpp" 80 #include "runtime/mutexLocker.hpp" 81 #include "runtime/sharedRuntime.hpp" 82 #include "runtime/signature.hpp" 83 #include "services/classLoadingService.hpp" 84 #include "services/diagnosticCommand.hpp" 85 #include "services/threadService.hpp" 86 #include "utilities/macros.hpp" 87 #include "utilities/utf8.hpp" 88 #if INCLUDE_CDS 89 #include "classfile/systemDictionaryShared.hpp" 90 #endif 91 #if INCLUDE_JFR 92 #include "jfr/jfr.hpp" 93 #endif 94 95 PlaceholderTable* SystemDictionary::_placeholders = NULL; 96 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL; 97 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL; 98 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL; 99 ProtectionDomainCacheTable* SystemDictionary::_pd_cache_table = NULL; 100 101 oop SystemDictionary::_system_loader_lock_obj = NULL; 102 103 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT] 104 = { NULL /*, NULL...*/ }; 105 106 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ }; 107 108 oop SystemDictionary::_java_system_loader = NULL; 109 oop SystemDictionary::_java_platform_loader = NULL; 110 111 // Default ProtectionDomainCacheSize value 112 113 const int defaultProtectionDomainCacheSize = 1009; 114 115 ClassLoadInfo::ClassLoadInfo() { 116 _protection_domain = Handle(); 117 _unsafe_anonymous_host = NULL; 118 _cp_patches = NULL; 119 _class_hidden_info._dynamic_nest_host = NULL; 120 _class_hidden_info._class_data = Handle(); 121 _is_hidden = false; 122 _is_strong_hidden = false; 123 _can_access_vm_annotations = false; 124 } 125 126 ClassLoadInfo::ClassLoadInfo(Handle protection_domain) { 127 _protection_domain = protection_domain; 128 _unsafe_anonymous_host = NULL; 129 _cp_patches = NULL; 130 _class_hidden_info._dynamic_nest_host = NULL; 131 _class_hidden_info._class_data = Handle(); 132 _is_hidden = false; 133 _is_strong_hidden = false; 134 _can_access_vm_annotations = false; 135 } 136 137 ClassLoadInfo::ClassLoadInfo(Handle protection_domain, 138 const InstanceKlass* unsafe_anonymous_host, 139 GrowableArray<Handle>* cp_patches, 140 InstanceKlass* dynamic_nest_host, 141 Handle class_data, 142 bool is_hidden, 143 bool is_strong_hidden, 144 bool can_access_vm_annotations) { 145 _protection_domain = protection_domain; 146 _unsafe_anonymous_host = unsafe_anonymous_host; 147 _cp_patches = cp_patches; 148 _class_hidden_info._dynamic_nest_host = dynamic_nest_host; 149 _class_hidden_info._class_data = class_data; 150 _is_hidden = is_hidden; 151 _is_strong_hidden = is_strong_hidden; 152 _can_access_vm_annotations = can_access_vm_annotations; 153 } 154 155 // ---------------------------------------------------------------------------- 156 // Java-level SystemLoader and PlatformLoader 157 158 oop SystemDictionary::java_system_loader() { 159 return _java_system_loader; 160 } 161 162 oop SystemDictionary::java_platform_loader() { 163 return _java_platform_loader; 164 } 165 166 void SystemDictionary::compute_java_loaders(TRAPS) { 167 JavaValue result(T_OBJECT); 168 InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass(); 169 JavaCalls::call_static(&result, 170 class_loader_klass, 171 vmSymbols::getSystemClassLoader_name(), 172 vmSymbols::void_classloader_signature(), 173 CHECK); 174 175 _java_system_loader = (oop)result.get_jobject(); 176 177 JavaCalls::call_static(&result, 178 class_loader_klass, 179 vmSymbols::getPlatformClassLoader_name(), 180 vmSymbols::void_classloader_signature(), 181 CHECK); 182 183 _java_platform_loader = (oop)result.get_jobject(); 184 } 185 186 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) { 187 if (create_mirror_cld) { 188 // Add a new class loader data to the graph. 189 return ClassLoaderDataGraph::add(class_loader, true); 190 } else { 191 return (class_loader() == NULL) ? ClassLoaderData::the_null_class_loader_data() : 192 ClassLoaderDataGraph::find_or_create(class_loader); 193 } 194 } 195 196 // ---------------------------------------------------------------------------- 197 // Parallel class loading check 198 199 bool SystemDictionary::is_parallelCapable(Handle class_loader) { 200 if (class_loader.is_null()) return true; 201 if (AlwaysLockClassLoader) return false; 202 return java_lang_ClassLoader::parallelCapable(class_loader()); 203 } 204 // ---------------------------------------------------------------------------- 205 // ParallelDefineClass flag does not apply to bootclass loader 206 bool SystemDictionary::is_parallelDefine(Handle class_loader) { 207 if (class_loader.is_null()) return false; 208 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) { 209 return true; 210 } 211 return false; 212 } 213 214 // Returns true if the passed class loader is the builtin application class loader 215 // or a custom system class loader. A customer system class loader can be 216 // specified via -Djava.system.class.loader. 217 bool SystemDictionary::is_system_class_loader(oop class_loader) { 218 if (class_loader == NULL) { 219 return false; 220 } 221 return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() || 222 class_loader == _java_system_loader); 223 } 224 225 // Returns true if the passed class loader is the platform class loader. 226 bool SystemDictionary::is_platform_class_loader(oop class_loader) { 227 if (class_loader == NULL) { 228 return false; 229 } 230 return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass()); 231 } 232 233 // ---------------------------------------------------------------------------- 234 // Resolving of classes 235 236 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) { 237 if (name == NULL) { 238 THROW_MSG_0(exception, "No class name given"); 239 } 240 if ((int)strlen(name) > Symbol::max_length()) { 241 // It's impossible to create this class; the name cannot fit 242 // into the constant pool. 243 Exceptions::fthrow(THREAD_AND_LOCATION, exception, 244 "Class name exceeds maximum length of %d: %s", 245 Symbol::max_length(), 246 name); 247 return NULL; 248 } 249 // Callers should ensure that the name is never an illegal UTF8 string. 250 assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false), 251 "Class name is not a valid utf8 string."); 252 253 // Make a new symbol for the class name. 254 return SymbolTable::new_symbol(name); 255 } 256 257 // Forwards to resolve_or_null 258 259 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) { 260 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD); 261 if (HAS_PENDING_EXCEPTION || klass == NULL) { 262 // can return a null klass 263 klass = handle_resolution_exception(class_name, throw_error, klass, THREAD); 264 } 265 return klass; 266 } 267 268 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name, 269 bool throw_error, 270 Klass* klass, TRAPS) { 271 if (HAS_PENDING_EXCEPTION) { 272 // If we have a pending exception we forward it to the caller, unless throw_error is true, 273 // in which case we have to check whether the pending exception is a ClassNotFoundException, 274 // and if so convert it to a NoClassDefFoundError 275 // And chain the original ClassNotFoundException 276 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) { 277 ResourceMark rm(THREAD); 278 assert(klass == NULL, "Should not have result with exception pending"); 279 Handle e(THREAD, PENDING_EXCEPTION); 280 CLEAR_PENDING_EXCEPTION; 281 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e); 282 } else { 283 return NULL; 284 } 285 } 286 // Class not found, throw appropriate error or exception depending on value of throw_error 287 if (klass == NULL) { 288 ResourceMark rm(THREAD); 289 if (throw_error) { 290 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string()); 291 } else { 292 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string()); 293 } 294 } 295 return klass; 296 } 297 298 299 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, 300 bool throw_error, TRAPS) 301 { 302 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD); 303 } 304 305 306 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null 307 308 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) { 309 if (Signature::is_array(class_name)) { 310 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD); 311 } else { 312 return resolve_instance_class_or_null_helper(class_name, class_loader, protection_domain, THREAD); 313 } 314 } 315 316 // name may be in the form of "java/lang/Object" or "Ljava/lang/Object;" 317 InstanceKlass* SystemDictionary::resolve_instance_class_or_null_helper(Symbol* class_name, 318 Handle class_loader, 319 Handle protection_domain, 320 TRAPS) { 321 assert(class_name != NULL && !Signature::is_array(class_name), "must be"); 322 if (Signature::has_envelope(class_name)) { 323 ResourceMark rm(THREAD); 324 // Ignore wrapping L and ;. 325 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1, 326 class_name->utf8_length() - 2); 327 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD); 328 } else { 329 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD); 330 } 331 } 332 333 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) { 334 return resolve_or_null(class_name, Handle(), Handle(), THREAD); 335 } 336 337 // Forwards to resolve_instance_class_or_null 338 339 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name, 340 Handle class_loader, 341 Handle protection_domain, 342 TRAPS) { 343 assert(Signature::is_array(class_name), "must be array"); 344 ResourceMark rm(THREAD); 345 SignatureStream ss(class_name, false); 346 int ndims = ss.skip_array_prefix(); // skip all '['s 347 Klass* k = NULL; 348 BasicType t = ss.type(); 349 if (ss.has_envelope()) { 350 Symbol* obj_class = ss.as_symbol(); 351 k = SystemDictionary::resolve_instance_class_or_null(obj_class, 352 class_loader, 353 protection_domain, 354 CHECK_NULL); 355 if (k != NULL) { 356 k = k->array_klass(ndims, CHECK_NULL); 357 } 358 } else { 359 k = Universe::typeArrayKlassObj(t); 360 k = TypeArrayKlass::cast(k)->array_klass(ndims, CHECK_NULL); 361 } 362 return k; 363 } 364 365 366 // Must be called for any super-class or super-interface resolution 367 // during class definition to allow class circularity checking 368 // super-interface callers: 369 // parse_interfaces - for defineClass & jvmtiRedefineClasses 370 // super-class callers: 371 // ClassFileParser - for defineClass & jvmtiRedefineClasses 372 // load_shared_class - while loading a class from shared archive 373 // resolve_instance_class_or_null: 374 // via: handle_parallel_super_load 375 // when resolving a class that has an existing placeholder with 376 // a saved superclass [i.e. a defineClass is currently in progress] 377 // if another thread is trying to resolve the class, it must do 378 // super-class checks on its own thread to catch class circularity 379 // This last call is critical in class circularity checking for cases 380 // where classloading is delegated to different threads and the 381 // classloader lock is released. 382 // Take the case: Base->Super->Base 383 // 1. If thread T1 tries to do a defineClass of class Base 384 // resolve_super_or_fail creates placeholder: T1, Base (super Super) 385 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super 386 // so it tries to load Super 387 // 3. If we load the class internally, or user classloader uses same thread 388 // loadClassFromxxx or defineClass via parseClassFile Super ... 389 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base) 390 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base 391 // 3.4 calls resolve_super_or_fail Base 392 // 3.5 finds T1,Base -> throws class circularity 393 //OR 4. If T2 tries to resolve Super via defineClass Super ... 394 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base) 395 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super) 396 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2 397 // 4.4 finds T2, Super -> throws class circularity 398 // Must be called, even if superclass is null, since this is 399 // where the placeholder entry is created which claims this 400 // thread is loading this class/classloader. 401 // Be careful when modifying this code: once you have run 402 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER), 403 // you need to find_and_remove it before returning. 404 // So be careful to not exit with a CHECK_ macro betweeen these calls. 405 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* child_name, 406 Symbol* super_name, 407 Handle class_loader, 408 Handle protection_domain, 409 bool is_superclass, 410 TRAPS) { 411 assert(!Signature::is_array(super_name), "invalid super class name"); 412 #if INCLUDE_CDS 413 if (DumpSharedSpaces) { 414 // Special processing for handling UNREGISTERED shared classes. 415 InstanceKlass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name, 416 super_name, class_loader, protection_domain, is_superclass, CHECK_NULL); 417 if (k) { 418 return k; 419 } 420 } 421 #endif // INCLUDE_CDS 422 423 // Double-check, if child class is already loaded, just return super-class,interface 424 // Don't add a placedholder if already loaded, i.e. already in appropriate class loader 425 // dictionary. 426 // Make sure there's a placeholder for the *child* before resolving. 427 // Used as a claim that this thread is currently loading superclass/classloader 428 // Used here for ClassCircularity checks and also for heap verification 429 // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder). 430 // Must check ClassCircularity before checking if super class is already loaded. 431 // 432 // We might not already have a placeholder if this child_name was 433 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass); 434 // the name of the class might not be known until the stream is actually 435 // parsed. 436 // Bugs 4643874, 4715493 437 438 ClassLoaderData* loader_data = class_loader_data(class_loader); 439 Dictionary* dictionary = loader_data->dictionary(); 440 unsigned int d_hash = dictionary->compute_hash(child_name); 441 unsigned int p_hash = placeholders()->compute_hash(child_name); 442 int p_index = placeholders()->hash_to_index(p_hash); 443 // can't throw error holding a lock 444 bool child_already_loaded = false; 445 bool throw_circularity_error = false; 446 { 447 MutexLocker mu(THREAD, SystemDictionary_lock); 448 InstanceKlass* childk = find_class(d_hash, child_name, dictionary); 449 InstanceKlass* quicksuperk; 450 // to support // loading: if child done loading, just return superclass 451 // if super_name, & class_loader don't match: 452 // if initial define, SD update will give LinkageError 453 // if redefine: compare_class_versions will give HIERARCHY_CHANGED 454 // so we don't throw an exception here. 455 // see: nsk redefclass014 & java.lang.instrument Instrument032 456 if ((childk != NULL ) && (is_superclass) && 457 ((quicksuperk = childk->java_super()) != NULL) && 458 ((quicksuperk->name() == super_name) && 459 (quicksuperk->class_loader() == class_loader()))) { 460 return quicksuperk; 461 } else { 462 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data); 463 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) { 464 throw_circularity_error = true; 465 } 466 } 467 if (!throw_circularity_error) { 468 // Be careful not to exit resolve_super 469 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, super_name, THREAD); 470 } 471 } 472 if (throw_circularity_error) { 473 ResourceMark rm(THREAD); 474 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string()); 475 } 476 477 // java.lang.Object should have been found above 478 assert(super_name != NULL, "null super class for resolving"); 479 // Resolve the super class or interface, check results on return 480 InstanceKlass* superk = 481 SystemDictionary::resolve_instance_class_or_null_helper(super_name, 482 class_loader, 483 protection_domain, 484 THREAD); 485 486 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up 487 // It is no longer necessary to keep the placeholder table alive until update_dictionary 488 // or error. GC used to walk the placeholder table as strong roots. 489 // The instanceKlass is kept alive because the class loader is on the stack, 490 // which keeps the loader_data alive, as well as all instanceKlasses in 491 // the loader_data. parseClassFile adds the instanceKlass to loader_data. 492 { 493 MutexLocker mu(THREAD, SystemDictionary_lock); 494 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD); 495 SystemDictionary_lock->notify_all(); 496 } 497 if (HAS_PENDING_EXCEPTION || superk == NULL) { 498 // can null superk 499 Klass* k = handle_resolution_exception(super_name, true, superk, THREAD); 500 assert(k == NULL || k == superk, "must be"); 501 if (k == NULL) { 502 superk = NULL; 503 } 504 } 505 506 return superk; 507 } 508 509 void SystemDictionary::validate_protection_domain(InstanceKlass* klass, 510 Handle class_loader, 511 Handle protection_domain, 512 TRAPS) { 513 // Now we have to call back to java to check if the initating class has access 514 JavaValue result(T_VOID); 515 LogTarget(Debug, protectiondomain) lt; 516 if (lt.is_enabled()) { 517 ResourceMark rm(THREAD); 518 // Print out trace information 519 LogStream ls(lt); 520 ls.print_cr("Checking package access"); 521 if (class_loader() != NULL) { 522 ls.print("class loader: "); 523 class_loader()->print_value_on(&ls); 524 } else { 525 ls.print_cr("class loader: NULL"); 526 } 527 if (protection_domain() != NULL) { 528 ls.print(" protection domain: "); 529 protection_domain()->print_value_on(&ls); 530 } else { 531 ls.print_cr(" protection domain: NULL"); 532 } 533 ls.print(" loading: "); klass->print_value_on(&ls); 534 ls.cr(); 535 } 536 537 // This handle and the class_loader handle passed in keeps this class from 538 // being unloaded through several GC points. 539 // The class_loader handle passed in is the initiating loader. 540 Handle mirror(THREAD, klass->java_mirror()); 541 542 InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass(); 543 JavaCalls::call_special(&result, 544 class_loader, 545 system_loader, 546 vmSymbols::checkPackageAccess_name(), 547 vmSymbols::class_protectiondomain_signature(), 548 mirror, 549 protection_domain, 550 THREAD); 551 552 if (HAS_PENDING_EXCEPTION) { 553 log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!"); 554 } else { 555 log_debug(protectiondomain)("granted"); 556 } 557 558 if (HAS_PENDING_EXCEPTION) return; 559 560 // If no exception has been thrown, we have validated the protection domain 561 // Insert the protection domain of the initiating class into the set. 562 { 563 ClassLoaderData* loader_data = class_loader_data(class_loader); 564 Dictionary* dictionary = loader_data->dictionary(); 565 566 Symbol* kn = klass->name(); 567 unsigned int d_hash = dictionary->compute_hash(kn); 568 569 MutexLocker mu(THREAD, SystemDictionary_lock); 570 int d_index = dictionary->hash_to_index(d_hash); 571 dictionary->add_protection_domain(d_index, d_hash, klass, 572 protection_domain, THREAD); 573 } 574 } 575 576 // We only get here if this thread finds that another thread 577 // has already claimed the placeholder token for the current operation, 578 // but that other thread either never owned or gave up the 579 // object lock 580 // Waits on SystemDictionary_lock to indicate placeholder table updated 581 // On return, caller must recheck placeholder table state 582 // 583 // We only get here if 584 // 1) custom classLoader, i.e. not bootstrap classloader 585 // 2) custom classLoader has broken the class loader objectLock 586 // so another thread got here in parallel 587 // 588 // lockObject must be held. 589 // Complicated dance due to lock ordering: 590 // Must first release the classloader object lock to 591 // allow initial definer to complete the class definition 592 // and to avoid deadlock 593 // Reclaim classloader lock object with same original recursion count 594 // Must release SystemDictionary_lock after notify, since 595 // class loader lock must be claimed before SystemDictionary_lock 596 // to prevent deadlocks 597 // 598 // The notify allows applications that did an untimed wait() on 599 // the classloader object lock to not hang. 600 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) { 601 assert_lock_strong(SystemDictionary_lock); 602 603 bool calledholdinglock 604 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject); 605 assert(calledholdinglock,"must hold lock for notify"); 606 assert((lockObject() != _system_loader_lock_obj && !is_parallelCapable(lockObject)), "unexpected double_lock_wait"); 607 ObjectSynchronizer::notifyall(lockObject, THREAD); 608 intx recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD); 609 SystemDictionary_lock->wait(); 610 SystemDictionary_lock->unlock(); 611 ObjectSynchronizer::reenter(lockObject, recursions, THREAD); 612 SystemDictionary_lock->lock(); 613 } 614 615 // If the class in is in the placeholder table, class loading is in progress 616 // For cases where the application changes threads to load classes, it 617 // is critical to ClassCircularity detection that we try loading 618 // the superclass on the same thread internally, so we do parallel 619 // super class loading here. 620 // This also is critical in cases where the original thread gets stalled 621 // even in non-circularity situations. 622 // Note: must call resolve_super_or_fail even if null super - 623 // to force placeholder entry creation for this class for circularity detection 624 // Caller must check for pending exception 625 // Returns non-null Klass* if other thread has completed load 626 // and we are done, 627 // If return null Klass* and no pending exception, the caller must load the class 628 InstanceKlass* SystemDictionary::handle_parallel_super_load( 629 Symbol* name, Symbol* superclassname, Handle class_loader, 630 Handle protection_domain, Handle lockObject, TRAPS) { 631 632 ClassLoaderData* loader_data = class_loader_data(class_loader); 633 Dictionary* dictionary = loader_data->dictionary(); 634 unsigned int d_hash = dictionary->compute_hash(name); 635 unsigned int p_hash = placeholders()->compute_hash(name); 636 int p_index = placeholders()->hash_to_index(p_hash); 637 638 // superk is not used, resolve_super called for circularity check only 639 // This code is reached in two situations. One if this thread 640 // is loading the same class twice (e.g. ClassCircularity, or 641 // java.lang.instrument). 642 // The second is if another thread started the resolve_super first 643 // and has not yet finished. 644 // In both cases the original caller will clean up the placeholder 645 // entry on error. 646 Klass* superk = SystemDictionary::resolve_super_or_fail(name, 647 superclassname, 648 class_loader, 649 protection_domain, 650 true, 651 CHECK_NULL); 652 653 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete 654 // Serial class loaders and bootstrap classloader do wait for superclass loads 655 if (!class_loader.is_null() && is_parallelCapable(class_loader)) { 656 MutexLocker mu(THREAD, SystemDictionary_lock); 657 // Check if classloading completed while we were loading superclass or waiting 658 return find_class(d_hash, name, dictionary); 659 } 660 661 // must loop to both handle other placeholder updates 662 // and spurious notifications 663 bool super_load_in_progress = true; 664 PlaceholderEntry* placeholder; 665 while (super_load_in_progress) { 666 MutexLocker mu(THREAD, SystemDictionary_lock); 667 // Check if classloading completed while we were loading superclass or waiting 668 InstanceKlass* check = find_class(d_hash, name, dictionary); 669 if (check != NULL) { 670 // Klass is already loaded, so just return it 671 return check; 672 } else { 673 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 674 if (placeholder && placeholder->super_load_in_progress() ){ 675 // We only get here if the application has released the 676 // classloader lock when another thread was in the middle of loading a 677 // superclass/superinterface for this class, and now 678 // this thread is also trying to load this class. 679 // To minimize surprises, the first thread that started to 680 // load a class should be the one to complete the loading 681 // with the classfile it initially expected. 682 // This logic has the current thread wait once it has done 683 // all the superclass/superinterface loading it can, until 684 // the original thread completes the class loading or fails 685 // If it completes we will use the resulting InstanceKlass 686 // which we will find below in the systemDictionary. 687 // We also get here for parallel bootstrap classloader 688 if (class_loader.is_null()) { 689 SystemDictionary_lock->wait(); 690 } else { 691 double_lock_wait(lockObject, THREAD); 692 } 693 } else { 694 // If not in SD and not in PH, other thread's load must have failed 695 super_load_in_progress = false; 696 } 697 } 698 } 699 return NULL; 700 } 701 702 static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) { 703 assert(event != NULL, "invariant"); 704 assert(k != NULL, "invariant"); 705 assert(event->should_commit(), "invariant"); 706 event->set_loadedClass(k); 707 event->set_definingClassLoader(k->class_loader_data()); 708 event->set_initiatingClassLoader(init_cld); 709 event->commit(); 710 } 711 712 713 // Be careful when modifying this code: once you have run 714 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE), 715 // you need to find_and_remove it before returning. 716 // So be careful to not exit with a CHECK_ macro betweeen these calls. 717 // 718 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;" 719 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, 720 Handle class_loader, 721 Handle protection_domain, 722 TRAPS) { 723 assert(name != NULL && !Signature::is_array(name) && 724 !Signature::has_envelope(name), "invalid class name"); 725 726 EventClassLoad class_load_start_event; 727 728 HandleMark hm(THREAD); 729 730 // Fix for 4474172; see evaluation for more details 731 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 732 ClassLoaderData* loader_data = register_loader(class_loader); 733 Dictionary* dictionary = loader_data->dictionary(); 734 unsigned int d_hash = dictionary->compute_hash(name); 735 736 // Do lookup to see if class already exist and the protection domain 737 // has the right access 738 // This call uses find which checks protection domain already matches 739 // All subsequent calls use find_class, and set has_loaded_class so that 740 // before we return a result we call out to java to check for valid protection domain 741 // to allow returning the Klass* and add it to the pd_set if it is valid 742 { 743 InstanceKlass* probe = dictionary->find(d_hash, name, protection_domain); 744 if (probe != NULL) return probe; 745 } 746 747 // Non-bootstrap class loaders will call out to class loader and 748 // define via jvm/jni_DefineClass which will acquire the 749 // class loader object lock to protect against multiple threads 750 // defining the class in parallel by accident. 751 // This lock must be acquired here so the waiter will find 752 // any successful result in the SystemDictionary and not attempt 753 // the define. 754 // ParallelCapable Classloaders and the bootstrap classloader 755 // do not acquire lock here. 756 bool DoObjectLock = true; 757 if (is_parallelCapable(class_loader)) { 758 DoObjectLock = false; 759 } 760 761 unsigned int p_hash = placeholders()->compute_hash(name); 762 int p_index = placeholders()->hash_to_index(p_hash); 763 764 // Class is not in SystemDictionary so we have to do loading. 765 // Make sure we are synchronized on the class loader before we proceed 766 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 767 check_loader_lock_contention(lockObject, THREAD); 768 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 769 770 // Check again (after locking) if class already exist in SystemDictionary 771 bool class_has_been_loaded = false; 772 bool super_load_in_progress = false; 773 bool havesupername = false; 774 InstanceKlass* k = NULL; 775 PlaceholderEntry* placeholder; 776 Symbol* superclassname = NULL; 777 778 assert(THREAD->can_call_java(), 779 "can not load classes with compiler thread: class=%s, classloader=%s", 780 name->as_C_string(), 781 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()); 782 { 783 MutexLocker mu(THREAD, SystemDictionary_lock); 784 InstanceKlass* check = find_class(d_hash, name, dictionary); 785 if (check != NULL) { 786 // InstanceKlass is already loaded, so just return it 787 class_has_been_loaded = true; 788 k = check; 789 } else { 790 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data); 791 if (placeholder && placeholder->super_load_in_progress()) { 792 super_load_in_progress = true; 793 if (placeholder->havesupername() == true) { 794 superclassname = placeholder->supername(); 795 havesupername = true; 796 } 797 } 798 } 799 } 800 801 // If the class is in the placeholder table, class loading is in progress 802 if (super_load_in_progress && havesupername==true) { 803 k = handle_parallel_super_load(name, 804 superclassname, 805 class_loader, 806 protection_domain, 807 lockObject, THREAD); 808 if (HAS_PENDING_EXCEPTION) { 809 return NULL; 810 } 811 if (k != NULL) { 812 class_has_been_loaded = true; 813 } 814 } 815 816 bool throw_circularity_error = false; 817 if (!class_has_been_loaded) { 818 bool load_instance_added = false; 819 820 // add placeholder entry to record loading instance class 821 // Five cases: 822 // All cases need to prevent modifying bootclasssearchpath 823 // in parallel with a classload of same classname 824 // Redefineclasses uses existence of the placeholder for the duration 825 // of the class load to prevent concurrent redefinition of not completely 826 // defined classes. 827 // case 1. traditional classloaders that rely on the classloader object lock 828 // - no other need for LOAD_INSTANCE 829 // case 2. traditional classloaders that break the classloader object lock 830 // as a deadlock workaround. Detection of this case requires that 831 // this check is done while holding the classloader object lock, 832 // and that lock is still held when calling classloader's loadClass. 833 // For these classloaders, we ensure that the first requestor 834 // completes the load and other requestors wait for completion. 835 // case 3. Bootstrap classloader - don't own objectLocker 836 // This classloader supports parallelism at the classloader level, 837 // but only allows a single load of a class/classloader pair. 838 // No performance benefit and no deadlock issues. 839 // case 4. parallelCapable user level classloaders - without objectLocker 840 // Allow parallel classloading of a class/classloader pair 841 842 { 843 MutexLocker mu(THREAD, SystemDictionary_lock); 844 if (class_loader.is_null() || !is_parallelCapable(class_loader)) { 845 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 846 if (oldprobe) { 847 // only need check_seen_thread once, not on each loop 848 // 6341374 java/lang/Instrument with -Xcomp 849 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) { 850 throw_circularity_error = true; 851 } else { 852 // case 1: traditional: should never see load_in_progress. 853 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) { 854 855 // case 3: bootstrap classloader: prevent futile classloading, 856 // wait on first requestor 857 if (class_loader.is_null()) { 858 SystemDictionary_lock->wait(); 859 } else { 860 // case 2: traditional with broken classloader lock. wait on first 861 // requestor. 862 double_lock_wait(lockObject, THREAD); 863 } 864 // Check if classloading completed while we were waiting 865 InstanceKlass* check = find_class(d_hash, name, dictionary); 866 if (check != NULL) { 867 // Klass is already loaded, so just return it 868 k = check; 869 class_has_been_loaded = true; 870 } 871 // check if other thread failed to load and cleaned up 872 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data); 873 } 874 } 875 } 876 } 877 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock 878 // case 4: parallelCapable: allow competing threads to try 879 // LOAD_INSTANCE in parallel 880 881 if (!throw_circularity_error && !class_has_been_loaded) { 882 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD); 883 load_instance_added = true; 884 // For class loaders that do not acquire the classloader object lock, 885 // if they did not catch another thread holding LOAD_INSTANCE, 886 // need a check analogous to the acquire ObjectLocker/find_class 887 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL 888 // one final check if the load has already completed 889 // class loaders holding the ObjectLock shouldn't find the class here 890 InstanceKlass* check = find_class(d_hash, name, dictionary); 891 if (check != NULL) { 892 // Klass is already loaded, so return it after checking/adding protection domain 893 k = check; 894 class_has_been_loaded = true; 895 } 896 } 897 } 898 899 // must throw error outside of owning lock 900 if (throw_circularity_error) { 901 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup"); 902 ResourceMark rm(THREAD); 903 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string()); 904 } 905 906 if (!class_has_been_loaded) { 907 908 // Do actual loading 909 k = load_instance_class(name, class_loader, THREAD); 910 911 // If everything was OK (no exceptions, no null return value), and 912 // class_loader is NOT the defining loader, do a little more bookkeeping. 913 if (!HAS_PENDING_EXCEPTION && k != NULL && 914 k->class_loader() != class_loader()) { 915 916 check_constraints(d_hash, k, class_loader, false, THREAD); 917 918 // Need to check for a PENDING_EXCEPTION again; check_constraints 919 // can throw but we may have to remove entry from the placeholder table below. 920 if (!HAS_PENDING_EXCEPTION) { 921 // Record dependency for non-parent delegation. 922 // This recording keeps the defining class loader of the klass (k) found 923 // from being unloaded while the initiating class loader is loaded 924 // even if the reference to the defining class loader is dropped 925 // before references to the initiating class loader. 926 loader_data->record_dependency(k); 927 928 { // Grabbing the Compile_lock prevents systemDictionary updates 929 // during compilations. 930 MutexLocker mu(THREAD, Compile_lock); 931 update_dictionary(d_hash, p_index, p_hash, 932 k, class_loader, THREAD); 933 } 934 935 if (JvmtiExport::should_post_class_load()) { 936 Thread *thread = THREAD; 937 assert(thread->is_Java_thread(), "thread->is_Java_thread()"); 938 JvmtiExport::post_class_load((JavaThread *) thread, k); 939 } 940 } 941 } 942 } // load_instance_class 943 944 if (load_instance_added == true) { 945 // clean up placeholder entries for LOAD_INSTANCE success or error 946 // This brackets the SystemDictionary updates for both defining 947 // and initiating loaders 948 MutexLocker mu(THREAD, SystemDictionary_lock); 949 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD); 950 SystemDictionary_lock->notify_all(); 951 } 952 } 953 954 if (HAS_PENDING_EXCEPTION || k == NULL) { 955 return NULL; 956 } 957 if (class_load_start_event.should_commit()) { 958 post_class_load_event(&class_load_start_event, k, loader_data); 959 } 960 #ifdef ASSERT 961 { 962 ClassLoaderData* loader_data = k->class_loader_data(); 963 MutexLocker mu(THREAD, SystemDictionary_lock); 964 InstanceKlass* kk = find_class(name, loader_data); 965 assert(kk == k, "should be present in dictionary"); 966 } 967 #endif 968 969 // return if the protection domain in NULL 970 if (protection_domain() == NULL) return k; 971 972 // Check the protection domain has the right access 973 if (dictionary->is_valid_protection_domain(d_hash, name, 974 protection_domain)) { 975 return k; 976 } 977 978 // Verify protection domain. If it fails an exception is thrown 979 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL); 980 981 return k; 982 } 983 984 985 // This routine does not lock the system dictionary. 986 // 987 // Since readers don't hold a lock, we must make sure that system 988 // dictionary entries are only removed at a safepoint (when only one 989 // thread is running), and are added to in a safe way (all links must 990 // be updated in an MT-safe manner). 991 // 992 // Callers should be aware that an entry could be added just after 993 // _dictionary->bucket(index) is read here, so the caller will not see 994 // the new entry. 995 996 Klass* SystemDictionary::find(Symbol* class_name, 997 Handle class_loader, 998 Handle protection_domain, 999 TRAPS) { 1000 1001 // The result of this call should be consistent with the result 1002 // of the call to resolve_instance_class_or_null(). 1003 // See evaluation 6790209 and 4474172 for more details. 1004 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader())); 1005 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader()); 1006 1007 if (loader_data == NULL) { 1008 // If the ClassLoaderData has not been setup, 1009 // then the class loader has no entries in the dictionary. 1010 return NULL; 1011 } 1012 1013 Dictionary* dictionary = loader_data->dictionary(); 1014 unsigned int d_hash = dictionary->compute_hash(class_name); 1015 return dictionary->find(d_hash, class_name, 1016 protection_domain); 1017 } 1018 1019 1020 // Look for a loaded instance or array klass by name. Do not do any loading. 1021 // return NULL in case of error. 1022 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name, 1023 Handle class_loader, 1024 Handle protection_domain, 1025 TRAPS) { 1026 Klass* k = NULL; 1027 assert(class_name != NULL, "class name must be non NULL"); 1028 1029 if (Signature::is_array(class_name)) { 1030 // The name refers to an array. Parse the name. 1031 // dimension and object_key in FieldArrayInfo are assigned as a 1032 // side-effect of this call 1033 SignatureStream ss(class_name, false); 1034 int ndims = ss.skip_array_prefix(); // skip all '['s 1035 BasicType t = ss.type(); 1036 if (t != T_OBJECT) { 1037 k = Universe::typeArrayKlassObj(t); 1038 } else { 1039 k = SystemDictionary::find(ss.as_symbol(), class_loader, protection_domain, THREAD); 1040 } 1041 if (k != NULL) { 1042 k = k->array_klass_or_null(ndims); 1043 } 1044 } else { 1045 k = find(class_name, class_loader, protection_domain, THREAD); 1046 } 1047 return k; 1048 } 1049 1050 // Note: this method is much like resolve_from_stream, but 1051 // does not publish the classes via the SystemDictionary. 1052 // Handles Lookup.defineClass hidden, unsafe_DefineAnonymousClass 1053 // and redefineclasses. RedefinedClasses do not add to the class hierarchy. 1054 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name, 1055 Handle class_loader, 1056 ClassFileStream* st, 1057 const ClassLoadInfo& cl_info, 1058 TRAPS) { 1059 1060 EventClassLoad class_load_start_event; 1061 ClassLoaderData* loader_data; 1062 bool is_unsafe_anon_class = cl_info.unsafe_anonymous_host() != NULL; 1063 1064 // - for unsafe anonymous class: create a new CLD whith a class holder that uses 1065 // the same class loader as the unsafe_anonymous_host. 1066 // - for hidden classes that are not strong: create a new CLD that has a class holder and 1067 // whose loader is the Lookup class's loader. 1068 // - for hidden class: add the class to the Lookup class's loader's CLD. 1069 if (is_unsafe_anon_class || cl_info.is_hidden()) { 1070 guarantee(!is_unsafe_anon_class || cl_info.unsafe_anonymous_host()->class_loader() == class_loader(), 1071 "should be NULL or the same"); 1072 bool create_mirror_cld = is_unsafe_anon_class || !cl_info.is_strong_hidden(); 1073 loader_data = register_loader(class_loader, create_mirror_cld); 1074 } else { 1075 loader_data = ClassLoaderData::class_loader_data(class_loader()); 1076 } 1077 1078 assert(st != NULL, "invariant"); 1079 assert(st->need_verify(), "invariant"); 1080 1081 // Parse stream and create a klass. 1082 // Note that we do this even though this klass might 1083 // already be present in the SystemDictionary, otherwise we would not 1084 // throw potential ClassFormatErrors. 1085 1086 InstanceKlass* k = KlassFactory::create_from_stream(st, 1087 class_name, 1088 loader_data, 1089 cl_info, 1090 CHECK_NULL); 1091 1092 if ((cl_info.is_hidden() || is_unsafe_anon_class) && k != NULL) { 1093 // Hidden classes that are not strong and unsafe anonymous classes must update 1094 // ClassLoaderData holder so that they can be unloaded when the mirror is no 1095 // longer referenced. 1096 if (!cl_info.is_strong_hidden() || is_unsafe_anon_class) { 1097 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror())); 1098 } 1099 1100 { 1101 MutexLocker mu_r(THREAD, Compile_lock); 1102 1103 // Add to class hierarchy, initialize vtables, and do possible 1104 // deoptimizations. 1105 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block 1106 // But, do not add to dictionary. 1107 } 1108 1109 // Rewrite and patch constant pool here. 1110 k->link_class(CHECK_NULL); 1111 if (cl_info.cp_patches() != NULL) { 1112 k->constants()->patch_resolved_references(cl_info.cp_patches()); 1113 } 1114 1115 // If it's anonymous, initialize it now, since nobody else will. 1116 if (is_unsafe_anon_class) { 1117 k->eager_initialize(CHECK_NULL); 1118 } 1119 1120 // notify jvmti 1121 if (JvmtiExport::should_post_class_load()) { 1122 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1123 JvmtiExport::post_class_load((JavaThread *) THREAD, k); 1124 } 1125 if (class_load_start_event.should_commit()) { 1126 post_class_load_event(&class_load_start_event, k, loader_data); 1127 } 1128 } 1129 assert(is_unsafe_anon_class || NULL == cl_info.cp_patches(), 1130 "cp_patches only found with unsafe_anonymous_host"); 1131 1132 return k; 1133 } 1134 1135 // Add a klass to the system from a stream (called by jni_DefineClass and 1136 // JVM_DefineClass). 1137 // Note: class_name can be NULL. In that case we do not know the name of 1138 // the class until we have parsed the stream. 1139 1140 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name, 1141 Handle class_loader, 1142 Handle protection_domain, 1143 ClassFileStream* st, 1144 TRAPS) { 1145 1146 HandleMark hm(THREAD); 1147 1148 // Classloaders that support parallelism, e.g. bootstrap classloader, 1149 // do not acquire lock here 1150 bool DoObjectLock = true; 1151 if (is_parallelCapable(class_loader)) { 1152 DoObjectLock = false; 1153 } 1154 1155 ClassLoaderData* loader_data = register_loader(class_loader); 1156 1157 // Make sure we are synchronized on the class loader before we proceed 1158 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1159 check_loader_lock_contention(lockObject, THREAD); 1160 ObjectLocker ol(lockObject, THREAD, DoObjectLock); 1161 1162 assert(st != NULL, "invariant"); 1163 1164 // Parse the stream and create a klass. 1165 // Note that we do this even though this klass might 1166 // already be present in the SystemDictionary, otherwise we would not 1167 // throw potential ClassFormatErrors. 1168 InstanceKlass* k = NULL; 1169 1170 #if INCLUDE_CDS 1171 if (!DumpSharedSpaces) { 1172 k = SystemDictionaryShared::lookup_from_stream(class_name, 1173 class_loader, 1174 protection_domain, 1175 st, 1176 CHECK_NULL); 1177 } 1178 #endif 1179 1180 if (k == NULL) { 1181 if (st->buffer() == NULL) { 1182 return NULL; 1183 } 1184 ClassLoadInfo cl_info(protection_domain); 1185 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL); 1186 } 1187 1188 assert(k != NULL, "no klass created"); 1189 Symbol* h_name = k->name(); 1190 assert(class_name == NULL || class_name == h_name, "name mismatch"); 1191 1192 // Add class just loaded 1193 // If a class loader supports parallel classloading handle parallel define requests 1194 // find_or_define_instance_class may return a different InstanceKlass 1195 if (is_parallelCapable(class_loader)) { 1196 InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD); 1197 if (!HAS_PENDING_EXCEPTION && defined_k != k) { 1198 // If a parallel capable class loader already defined this class, register 'k' for cleanup. 1199 assert(defined_k != NULL, "Should have a klass if there's no exception"); 1200 loader_data->add_to_deallocate_list(k); 1201 k = defined_k; 1202 } 1203 } else { 1204 define_instance_class(k, THREAD); 1205 } 1206 1207 // If defining the class throws an exception register 'k' for cleanup. 1208 if (HAS_PENDING_EXCEPTION) { 1209 assert(k != NULL, "Must have an instance klass here!"); 1210 loader_data->add_to_deallocate_list(k); 1211 return NULL; 1212 } 1213 1214 // Make sure we have an entry in the SystemDictionary on success 1215 debug_only( { 1216 MutexLocker mu(THREAD, SystemDictionary_lock); 1217 1218 Klass* check = find_class(h_name, k->class_loader_data()); 1219 assert(check == k, "should be present in the dictionary"); 1220 } ); 1221 1222 return k; 1223 } 1224 1225 #if INCLUDE_CDS 1226 // Load a class for boot loader from the shared spaces. This also 1227 // forces the super class and all interfaces to be loaded. 1228 InstanceKlass* SystemDictionary::load_shared_boot_class(Symbol* class_name, 1229 PackageEntry* pkg_entry, 1230 TRAPS) { 1231 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name); 1232 if (ik != NULL && ik->is_shared_boot_class()) { 1233 return load_shared_class(ik, Handle(), Handle(), NULL, pkg_entry, THREAD); 1234 } 1235 return NULL; 1236 } 1237 1238 // Check if a shared class can be loaded by the specific classloader: 1239 // 1240 // NULL classloader: 1241 // - Module class from "modules" jimage. ModuleEntry must be defined in the classloader. 1242 // - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must 1243 // be defined in an unnamed module. 1244 bool SystemDictionary::is_shared_class_visible(Symbol* class_name, 1245 InstanceKlass* ik, 1246 PackageEntry* pkg_entry, 1247 Handle class_loader, TRAPS) { 1248 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(), 1249 "Cannot use sharing if java.base is patched"); 1250 ResourceMark rm(THREAD); 1251 int path_index = ik->shared_classpath_index(); 1252 ClassLoaderData* loader_data = class_loader_data(class_loader); 1253 if (path_index < 0) { 1254 // path_index < 0 indicates that the class is intended for a custom loader 1255 // and should not be loaded by boot/platform/app loaders 1256 if (loader_data->is_builtin_class_loader_data()) { 1257 return false; 1258 } else { 1259 return true; 1260 } 1261 } 1262 SharedClassPathEntry* ent = 1263 (SharedClassPathEntry*)FileMapInfo::shared_path(path_index); 1264 if (!Universe::is_module_initialized()) { 1265 assert(ent != NULL && ent->is_modules_image(), 1266 "Loading non-bootstrap classes before the module system is initialized"); 1267 assert(class_loader.is_null(), "sanity"); 1268 return true; 1269 } 1270 // Get the pkg_entry from the classloader 1271 ModuleEntry* mod_entry = NULL; 1272 TempNewSymbol pkg_name = pkg_entry != NULL ? pkg_entry->name() : 1273 ClassLoader::package_from_class_name(class_name); 1274 if (pkg_name != NULL) { 1275 if (loader_data != NULL) { 1276 if (pkg_entry != NULL) { 1277 mod_entry = pkg_entry->module(); 1278 // If the archived class is from a module that has been patched at runtime, 1279 // the class cannot be loaded from the archive. 1280 if (mod_entry != NULL && mod_entry->is_patched()) { 1281 return false; 1282 } 1283 } 1284 } 1285 } 1286 1287 if (class_loader.is_null()) { 1288 assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry"); 1289 // The NULL classloader can load archived class originated from the 1290 // "modules" jimage and the -Xbootclasspath/a. For class from the 1291 // "modules" jimage, the PackageEntry/ModuleEntry must be defined 1292 // by the NULL classloader. 1293 if (mod_entry != NULL) { 1294 // PackageEntry/ModuleEntry is found in the classloader. Check if the 1295 // ModuleEntry's location agrees with the archived class' origination. 1296 if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) { 1297 return true; // Module class from the "module" jimage 1298 } 1299 } 1300 1301 // If the archived class is not from the "module" jimage, the class can be 1302 // loaded by the NULL classloader if 1303 // 1304 // 1. the class is from the unamed package 1305 // 2. or, the class is not from a module defined in the NULL classloader 1306 // 3. or, the class is from an unamed module 1307 if (!ent->is_modules_image() && ik->is_shared_boot_class()) { 1308 // the class is from the -Xbootclasspath/a 1309 if (pkg_name == NULL || 1310 pkg_entry == NULL || 1311 pkg_entry->in_unnamed_module()) { 1312 assert(mod_entry == NULL || 1313 mod_entry == loader_data->unnamed_module(), 1314 "the unnamed module is not defined in the classloader"); 1315 return true; 1316 } 1317 } 1318 return false; 1319 } else { 1320 bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader( 1321 ik, class_loader, pkg_name, pkg_entry, mod_entry, CHECK_(false)); 1322 return res; 1323 } 1324 } 1325 1326 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* child, InstanceKlass* super_type, 1327 Handle class_loader, Handle protection_domain, 1328 bool is_superclass, TRAPS) { 1329 assert(super_type->is_shared(), "must be"); 1330 1331 Klass *found = resolve_super_or_fail(child->name(), super_type->name(), 1332 class_loader, protection_domain, is_superclass, CHECK_0); 1333 if (found == super_type) { 1334 return true; 1335 } else { 1336 // The dynamically resolved super type is not the same as the one we used during dump time, 1337 // so we cannot use the child class. 1338 return false; 1339 } 1340 } 1341 1342 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader, 1343 Handle protection_domain, TRAPS) { 1344 // Check the superclass and interfaces. They must be the same 1345 // as in dump time, because the layout of <ik> depends on 1346 // the specific layout of ik->super() and ik->local_interfaces(). 1347 // 1348 // If unexpected superclass or interfaces are found, we cannot 1349 // load <ik> from the shared archive. 1350 1351 if (ik->super() != NULL && 1352 !check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()), 1353 class_loader, protection_domain, true, THREAD)) { 1354 return false; 1355 } 1356 1357 Array<InstanceKlass*>* interfaces = ik->local_interfaces(); 1358 int num_interfaces = interfaces->length(); 1359 for (int index = 0; index < num_interfaces; index++) { 1360 if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) { 1361 return false; 1362 } 1363 } 1364 1365 return true; 1366 } 1367 1368 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik, 1369 Handle class_loader, 1370 Handle protection_domain, 1371 const ClassFileStream *cfs, 1372 PackageEntry* pkg_entry, 1373 TRAPS) { 1374 assert(ik != NULL, "sanity"); 1375 assert(!ik->is_unshareable_info_restored(), "shared class can be loaded only once"); 1376 Symbol* class_name = ik->name(); 1377 1378 bool visible = is_shared_class_visible( 1379 class_name, ik, pkg_entry, class_loader, CHECK_NULL); 1380 if (!visible) { 1381 return NULL; 1382 } 1383 1384 if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) { 1385 return NULL; 1386 } 1387 1388 InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook( 1389 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL); 1390 if (new_ik != NULL) { 1391 // The class is changed by CFLH. Return the new class. The shared class is 1392 // not used. 1393 return new_ik; 1394 } 1395 1396 // Adjust methods to recover missing data. They need addresses for 1397 // interpreter entry points and their default native method address 1398 // must be reset. 1399 1400 // Updating methods must be done under a lock so multiple 1401 // threads don't update these in parallel 1402 // 1403 // Shared classes are all currently loaded by either the bootstrap or 1404 // internal parallel class loaders, so this will never cause a deadlock 1405 // on a custom class loader lock. 1406 1407 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader()); 1408 { 1409 HandleMark hm(THREAD); 1410 Handle lockObject = compute_loader_lock_object(class_loader, THREAD); 1411 check_loader_lock_contention(lockObject, THREAD); 1412 ObjectLocker ol(lockObject, THREAD, true); 1413 // prohibited package check assumes all classes loaded from archive call 1414 // restore_unshareable_info which calls ik->set_package() 1415 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL); 1416 } 1417 1418 load_shared_class_misc(ik, loader_data, CHECK_NULL); 1419 return ik; 1420 } 1421 1422 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data, TRAPS) { 1423 ik->print_class_load_logging(loader_data, NULL, NULL); 1424 1425 // For boot loader, ensure that GetSystemPackage knows that a class in this 1426 // package was loaded. 1427 if (loader_data->is_the_null_class_loader_data()) { 1428 int path_index = ik->shared_classpath_index(); 1429 ik->set_classpath_index(path_index, THREAD); 1430 } 1431 1432 if (DumpLoadedClassList != NULL && classlist_file->is_open()) { 1433 // Only dump the classes that can be stored into CDS archive 1434 if (SystemDictionaryShared::is_sharing_possible(loader_data)) { 1435 ResourceMark rm(THREAD); 1436 classlist_file->print_cr("%s", ik->name()->as_C_string()); 1437 classlist_file->flush(); 1438 } 1439 } 1440 1441 // notify a class loaded from shared object 1442 ClassLoadingService::notify_class_loaded(ik, true /* shared class */); 1443 1444 ik->set_has_passed_fingerprint_check(false); 1445 if (UseAOT && ik->supers_have_passed_fingerprint_checks()) { 1446 uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik); 1447 uint64_t cds_fp = ik->get_stored_fingerprint(); 1448 if (aot_fp != 0 && aot_fp == cds_fp) { 1449 // This class matches with a class saved in an AOT library 1450 ik->set_has_passed_fingerprint_check(true); 1451 } else { 1452 if (log_is_enabled(Info, class, fingerprint)) { 1453 ResourceMark rm(THREAD); 1454 log_info(class, fingerprint)("%s : expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp); 1455 } 1456 } 1457 } 1458 } 1459 1460 void SystemDictionary::quick_resolve(InstanceKlass* klass, ClassLoaderData* loader_data, Handle domain, TRAPS) { 1461 assert(!Universe::is_fully_initialized(), "We can make short cuts only during VM initialization"); 1462 assert(klass->is_shared(), "Must be shared class"); 1463 if (klass->class_loader_data() != NULL) { 1464 return; 1465 } 1466 1467 // add super and interfaces first 1468 Klass* super = klass->super(); 1469 if (super != NULL && super->class_loader_data() == NULL) { 1470 assert(super->is_instance_klass(), "Super should be instance klass"); 1471 quick_resolve(InstanceKlass::cast(super), loader_data, domain, CHECK); 1472 } 1473 1474 Array<InstanceKlass*>* ifs = klass->local_interfaces(); 1475 for (int i = 0; i < ifs->length(); i++) { 1476 InstanceKlass* ik = ifs->at(i); 1477 if (ik->class_loader_data() == NULL) { 1478 quick_resolve(ik, loader_data, domain, CHECK); 1479 } 1480 } 1481 1482 klass->restore_unshareable_info(loader_data, domain, NULL, THREAD); 1483 load_shared_class_misc(klass, loader_data, CHECK); 1484 Dictionary* dictionary = loader_data->dictionary(); 1485 unsigned int hash = dictionary->compute_hash(klass->name()); 1486 dictionary->add_klass(hash, klass->name(), klass); 1487 add_to_hierarchy(klass, CHECK); 1488 assert(klass->is_loaded(), "Must be in at least loaded state"); 1489 } 1490 #endif // INCLUDE_CDS 1491 1492 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) { 1493 1494 if (class_loader.is_null()) { 1495 ResourceMark rm(THREAD); 1496 PackageEntry* pkg_entry = NULL; 1497 bool search_only_bootloader_append = false; 1498 ClassLoaderData *loader_data = class_loader_data(class_loader); 1499 1500 // Find the package in the boot loader's package entry table. 1501 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name); 1502 if (pkg_name != NULL) { 1503 pkg_entry = loader_data->packages()->lookup_only(pkg_name); 1504 } 1505 1506 // Prior to attempting to load the class, enforce the boot loader's 1507 // visibility boundaries. 1508 if (!Universe::is_module_initialized()) { 1509 // During bootstrapping, prior to module initialization, any 1510 // class attempting to be loaded must be checked against the 1511 // java.base packages in the boot loader's PackageEntryTable. 1512 // No class outside of java.base is allowed to be loaded during 1513 // this bootstrapping window. 1514 if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) { 1515 // Class is either in the unnamed package or in 1516 // a named package within the unnamed module. Either 1517 // case is outside of java.base, do not attempt to 1518 // load the class post java.base definition. If 1519 // java.base has not been defined, let the class load 1520 // and its package will be checked later by 1521 // ModuleEntryTable::verify_javabase_packages. 1522 if (ModuleEntryTable::javabase_defined()) { 1523 return NULL; 1524 } 1525 } else { 1526 // Check that the class' package is defined within java.base. 1527 ModuleEntry* mod_entry = pkg_entry->module(); 1528 Symbol* mod_entry_name = mod_entry->name(); 1529 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) { 1530 return NULL; 1531 } 1532 } 1533 } else { 1534 // After the module system has been initialized, check if the class' 1535 // package is in a module defined to the boot loader. 1536 if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) { 1537 // Class is either in the unnamed package, in a named package 1538 // within a module not defined to the boot loader or in a 1539 // a named package within the unnamed module. In all cases, 1540 // limit visibility to search for the class only in the boot 1541 // loader's append path. 1542 if (!ClassLoader::has_bootclasspath_append()) { 1543 // If there is no bootclasspath append entry, no need to continue 1544 // searching. 1545 return NULL; 1546 } 1547 search_only_bootloader_append = true; 1548 } 1549 } 1550 1551 // Prior to bootstrapping's module initialization, never load a class outside 1552 // of the boot loader's module path 1553 assert(Universe::is_module_initialized() || 1554 !search_only_bootloader_append, 1555 "Attempt to load a class outside of boot loader's module path"); 1556 1557 // Search for classes in the CDS archive. 1558 InstanceKlass* k = NULL; 1559 { 1560 #if INCLUDE_CDS 1561 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time()); 1562 k = load_shared_boot_class(class_name, pkg_entry, THREAD); 1563 #endif 1564 } 1565 1566 if (k == NULL) { 1567 // Use VM class loader 1568 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time()); 1569 k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL); 1570 } 1571 1572 // find_or_define_instance_class may return a different InstanceKlass 1573 if (k != NULL) { 1574 InstanceKlass* defined_k = 1575 find_or_define_instance_class(class_name, class_loader, k, THREAD); 1576 if (!HAS_PENDING_EXCEPTION && defined_k != k) { 1577 // If a parallel capable class loader already defined this class, register 'k' for cleanup. 1578 assert(defined_k != NULL, "Should have a klass if there's no exception"); 1579 loader_data->add_to_deallocate_list(k); 1580 k = defined_k; 1581 } else if (HAS_PENDING_EXCEPTION) { 1582 loader_data->add_to_deallocate_list(k); 1583 return NULL; 1584 } 1585 } 1586 return k; 1587 } else { 1588 // Use user specified class loader to load class. Call loadClass operation on class_loader. 1589 ResourceMark rm(THREAD); 1590 1591 assert(THREAD->is_Java_thread(), "must be a JavaThread"); 1592 JavaThread* jt = (JavaThread*) THREAD; 1593 1594 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(), 1595 ClassLoader::perf_app_classload_selftime(), 1596 ClassLoader::perf_app_classload_count(), 1597 jt->get_thread_stat()->perf_recursion_counts_addr(), 1598 jt->get_thread_stat()->perf_timers_addr(), 1599 PerfClassTraceTime::CLASS_LOAD); 1600 1601 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL); 1602 // Translate to external class name format, i.e., convert '/' chars to '.' 1603 Handle string = java_lang_String::externalize_classname(s, CHECK_NULL); 1604 1605 JavaValue result(T_OBJECT); 1606 1607 InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass(); 1608 1609 // Call public unsynchronized loadClass(String) directly for all class loaders. 1610 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will 1611 // acquire a class-name based lock rather than the class loader object lock. 1612 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean). 1613 JavaCalls::call_virtual(&result, 1614 class_loader, 1615 spec_klass, 1616 vmSymbols::loadClass_name(), 1617 vmSymbols::string_class_signature(), 1618 string, 1619 CHECK_NULL); 1620 1621 assert(result.get_type() == T_OBJECT, "just checking"); 1622 oop obj = (oop) result.get_jobject(); 1623 1624 // Primitive classes return null since forName() can not be 1625 // used to obtain any of the Class objects representing primitives or void 1626 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) { 1627 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj)); 1628 // For user defined Java class loaders, check that the name returned is 1629 // the same as that requested. This check is done for the bootstrap 1630 // loader when parsing the class file. 1631 if (class_name == k->name()) { 1632 return k; 1633 } 1634 } 1635 // Class is not found or has the wrong name, return NULL 1636 return NULL; 1637 } 1638 } 1639 1640 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) { 1641 EventClassDefine event; 1642 if (event.should_commit()) { 1643 event.set_definedClass(k); 1644 event.set_definingClassLoader(def_cld); 1645 event.commit(); 1646 } 1647 } 1648 1649 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) { 1650 1651 HandleMark hm(THREAD); 1652 ClassLoaderData* loader_data = k->class_loader_data(); 1653 Handle class_loader_h(THREAD, loader_data->class_loader()); 1654 1655 // for bootstrap and other parallel classloaders don't acquire lock, 1656 // use placeholder token 1657 // If a parallelCapable class loader calls define_instance_class instead of 1658 // find_or_define_instance_class to get here, we have a timing 1659 // hole with systemDictionary updates and check_constraints 1660 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) { 1661 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, 1662 compute_loader_lock_object(class_loader_h, THREAD)), 1663 "define called without lock"); 1664 } 1665 1666 // Check class-loading constraints. Throw exception if violation is detected. 1667 // Grabs and releases SystemDictionary_lock 1668 // The check_constraints/find_class call and update_dictionary sequence 1669 // must be "atomic" for a specific class/classloader pair so we never 1670 // define two different instanceKlasses for that class/classloader pair. 1671 // Existing classloaders will call define_instance_class with the 1672 // classloader lock held 1673 // Parallel classloaders will call find_or_define_instance_class 1674 // which will require a token to perform the define class 1675 Symbol* name_h = k->name(); 1676 Dictionary* dictionary = loader_data->dictionary(); 1677 unsigned int d_hash = dictionary->compute_hash(name_h); 1678 check_constraints(d_hash, k, class_loader_h, true, CHECK); 1679 1680 // Register class just loaded with class loader (placed in ArrayList) 1681 // Note we do this before updating the dictionary, as this can 1682 // fail with an OutOfMemoryError (if it does, we will *not* put this 1683 // class in the dictionary and will not update the class hierarchy). 1684 // JVMTI FollowReferences needs to find the classes this way. 1685 if (k->class_loader() != NULL) { 1686 methodHandle m(THREAD, Universe::loader_addClass_method()); 1687 JavaValue result(T_VOID); 1688 JavaCallArguments args(class_loader_h); 1689 args.push_oop(Handle(THREAD, k->java_mirror())); 1690 JavaCalls::call(&result, m, &args, CHECK); 1691 } 1692 1693 // Add the new class. We need recompile lock during update of CHA. 1694 { 1695 unsigned int p_hash = placeholders()->compute_hash(name_h); 1696 int p_index = placeholders()->hash_to_index(p_hash); 1697 1698 MutexLocker mu_r(THREAD, Compile_lock); 1699 1700 // Add to class hierarchy, initialize vtables, and do possible 1701 // deoptimizations. 1702 add_to_hierarchy(k, CHECK); // No exception, but can block 1703 1704 // Add to systemDictionary - so other classes can see it. 1705 // Grabs and releases SystemDictionary_lock 1706 update_dictionary(d_hash, p_index, p_hash, 1707 k, class_loader_h, THREAD); 1708 } 1709 k->eager_initialize(THREAD); 1710 1711 // notify jvmti 1712 if (JvmtiExport::should_post_class_load()) { 1713 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()"); 1714 JvmtiExport::post_class_load((JavaThread *) THREAD, k); 1715 1716 } 1717 post_class_define_event(k, loader_data); 1718 } 1719 1720 // Support parallel classloading 1721 // All parallel class loaders, including bootstrap classloader 1722 // lock a placeholder entry for this class/class_loader pair 1723 // to allow parallel defines of different classes for this class loader 1724 // With AllowParallelDefine flag==true, in case they do not synchronize around 1725 // FindLoadedClass/DefineClass, calls, we check for parallel 1726 // loading for them, wait if a defineClass is in progress 1727 // and return the initial requestor's results 1728 // This flag does not apply to the bootstrap classloader. 1729 // With AllowParallelDefine flag==false, call through to define_instance_class 1730 // which will throw LinkageError: duplicate class definition. 1731 // False is the requested default. 1732 // For better performance, the class loaders should synchronize 1733 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they 1734 // potentially waste time reading and parsing the bytestream. 1735 // Note: VM callers should ensure consistency of k/class_name,class_loader 1736 // Be careful when modifying this code: once you have run 1737 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS), 1738 // you need to find_and_remove it before returning. 1739 // So be careful to not exit with a CHECK_ macro betweeen these calls. 1740 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, 1741 InstanceKlass* k, TRAPS) { 1742 1743 Symbol* name_h = k->name(); // passed in class_name may be null 1744 ClassLoaderData* loader_data = class_loader_data(class_loader); 1745 Dictionary* dictionary = loader_data->dictionary(); 1746 1747 unsigned int d_hash = dictionary->compute_hash(name_h); 1748 1749 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS 1750 unsigned int p_hash = placeholders()->compute_hash(name_h); 1751 int p_index = placeholders()->hash_to_index(p_hash); 1752 PlaceholderEntry* probe; 1753 1754 { 1755 MutexLocker mu(THREAD, SystemDictionary_lock); 1756 // First check if class already defined 1757 if (is_parallelDefine(class_loader)) { 1758 InstanceKlass* check = find_class(d_hash, name_h, dictionary); 1759 if (check != NULL) { 1760 return check; 1761 } 1762 } 1763 1764 // Acquire define token for this class/classloader 1765 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD); 1766 // Wait if another thread defining in parallel 1767 // All threads wait - even those that will throw duplicate class: otherwise 1768 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails 1769 // if other thread has not finished updating dictionary 1770 while (probe->definer() != NULL) { 1771 SystemDictionary_lock->wait(); 1772 } 1773 // Only special cases allow parallel defines and can use other thread's results 1774 // Other cases fall through, and may run into duplicate defines 1775 // caught by finding an entry in the SystemDictionary 1776 if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) { 1777 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1778 SystemDictionary_lock->notify_all(); 1779 #ifdef ASSERT 1780 InstanceKlass* check = find_class(d_hash, name_h, dictionary); 1781 assert(check != NULL, "definer missed recording success"); 1782 #endif 1783 return probe->instance_klass(); 1784 } else { 1785 // This thread will define the class (even if earlier thread tried and had an error) 1786 probe->set_definer(THREAD); 1787 } 1788 } 1789 1790 define_instance_class(k, THREAD); 1791 1792 Handle linkage_exception = Handle(); // null handle 1793 1794 // definer must notify any waiting threads 1795 { 1796 MutexLocker mu(THREAD, SystemDictionary_lock); 1797 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data); 1798 assert(probe != NULL, "DEFINE_CLASS placeholder lost?"); 1799 if (probe != NULL) { 1800 if (HAS_PENDING_EXCEPTION) { 1801 linkage_exception = Handle(THREAD,PENDING_EXCEPTION); 1802 CLEAR_PENDING_EXCEPTION; 1803 } else { 1804 probe->set_instance_klass(k); 1805 } 1806 probe->set_definer(NULL); 1807 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1808 SystemDictionary_lock->notify_all(); 1809 } 1810 } 1811 1812 // Can't throw exception while holding lock due to rank ordering 1813 if (linkage_exception() != NULL) { 1814 THROW_OOP_(linkage_exception(), NULL); // throws exception and returns 1815 } 1816 1817 return k; 1818 } 1819 1820 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) { 1821 // If class_loader is NULL we synchronize on _system_loader_lock_obj 1822 if (class_loader.is_null()) { 1823 return Handle(THREAD, _system_loader_lock_obj); 1824 } else { 1825 return class_loader; 1826 } 1827 } 1828 1829 // This method is added to check how often we have to wait to grab loader 1830 // lock. The results are being recorded in the performance counters defined in 1831 // ClassLoader::_sync_systemLoaderLockContentionRate and 1832 // ClassLoader::_sync_nonSystemLoaderLockConteionRate. 1833 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) { 1834 if (!UsePerfData) { 1835 return; 1836 } 1837 1838 assert(!loader_lock.is_null(), "NULL lock object"); 1839 1840 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock) 1841 == ObjectSynchronizer::owner_other) { 1842 // contention will likely happen, so increment the corresponding 1843 // contention counter. 1844 if (loader_lock() == _system_loader_lock_obj) { 1845 ClassLoader::sync_systemLoaderLockContentionRate()->inc(); 1846 } else { 1847 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc(); 1848 } 1849 } 1850 } 1851 1852 // ---------------------------------------------------------------------------- 1853 // Lookup 1854 1855 InstanceKlass* SystemDictionary::find_class(unsigned int hash, 1856 Symbol* class_name, 1857 Dictionary* dictionary) { 1858 assert_locked_or_safepoint(SystemDictionary_lock); 1859 int index = dictionary->hash_to_index(hash); 1860 return dictionary->find_class(index, hash, class_name); 1861 } 1862 1863 1864 // Basic find on classes in the midst of being loaded 1865 Symbol* SystemDictionary::find_placeholder(Symbol* class_name, 1866 ClassLoaderData* loader_data) { 1867 assert_locked_or_safepoint(SystemDictionary_lock); 1868 unsigned int p_hash = placeholders()->compute_hash(class_name); 1869 int p_index = placeholders()->hash_to_index(p_hash); 1870 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data); 1871 } 1872 1873 1874 // Used for assertions and verification only 1875 // Precalculating the hash and index is an optimization because there are many lookups 1876 // before adding the class. 1877 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) { 1878 assert_locked_or_safepoint(SystemDictionary_lock); 1879 #ifndef ASSERT 1880 guarantee(VerifyBeforeGC || 1881 VerifyDuringGC || 1882 VerifyBeforeExit || 1883 VerifyDuringStartup || 1884 VerifyAfterGC, "too expensive"); 1885 #endif 1886 1887 Dictionary* dictionary = loader_data->dictionary(); 1888 unsigned int d_hash = dictionary->compute_hash(class_name); 1889 return find_class(d_hash, class_name, dictionary); 1890 } 1891 1892 1893 // ---------------------------------------------------------------------------- 1894 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock 1895 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in 1896 // before a new class is used. 1897 1898 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) { 1899 assert(k != NULL, "just checking"); 1900 if (Universe::is_fully_initialized()) { 1901 assert_locked_or_safepoint(Compile_lock); 1902 } 1903 1904 k->set_init_state(InstanceKlass::loaded); 1905 // make sure init_state store is already done. 1906 // The compiler reads the hierarchy outside of the Compile_lock. 1907 // Access ordering is used to add to hierarchy. 1908 1909 // Link into hierachy. 1910 k->append_to_sibling_list(); // add to superklass/sibling list 1911 k->process_interfaces(THREAD); // handle all "implements" declarations 1912 1913 // Now flush all code that depended on old class hierarchy. 1914 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97) 1915 if (Universe::is_fully_initialized()) { 1916 CodeCache::flush_dependents_on(k); 1917 } 1918 } 1919 1920 // ---------------------------------------------------------------------------- 1921 // GC support 1922 1923 // Assumes classes in the SystemDictionary are only unloaded at a safepoint 1924 // Note: anonymous classes are not in the SD. 1925 bool SystemDictionary::do_unloading(GCTimer* gc_timer) { 1926 1927 bool unloading_occurred; 1928 bool is_concurrent = !SafepointSynchronize::is_at_safepoint(); 1929 { 1930 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer); 1931 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks. 1932 // First, mark for unload all ClassLoaderData referencing a dead class loader. 1933 unloading_occurred = ClassLoaderDataGraph::do_unloading(); 1934 if (unloading_occurred) { 1935 MutexLocker ml2(is_concurrent ? Module_lock : NULL); 1936 JFR_ONLY(Jfr::on_unloading_classes();) 1937 1938 MutexLocker ml1(is_concurrent ? SystemDictionary_lock : NULL); 1939 ClassLoaderDataGraph::clean_module_and_package_info(); 1940 constraints()->purge_loader_constraints(); 1941 resolution_errors()->purge_resolution_errors(); 1942 } 1943 } 1944 1945 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer); 1946 1947 if (unloading_occurred) { 1948 SymbolTable::trigger_cleanup(); 1949 1950 // Oops referenced by the protection domain cache table may get unreachable independently 1951 // of the class loader (eg. cached protection domain oops). So we need to 1952 // explicitly unlink them here. 1953 // All protection domain oops are linked to the caller class, so if nothing 1954 // unloads, this is not needed. 1955 _pd_cache_table->trigger_cleanup(); 1956 } 1957 1958 return unloading_occurred; 1959 } 1960 1961 void SystemDictionary::oops_do(OopClosure* f, bool include_handles) { 1962 f->do_oop(&_java_system_loader); 1963 f->do_oop(&_java_platform_loader); 1964 f->do_oop(&_system_loader_lock_obj); 1965 CDS_ONLY(SystemDictionaryShared::oops_do(f);) 1966 1967 // Visit extra methods 1968 invoke_method_table()->oops_do(f); 1969 1970 if (include_handles) { 1971 OopStorageSet::vm_global()->oops_do(f); 1972 } 1973 } 1974 1975 // CDS: scan and relocate all classes referenced by _well_known_klasses[]. 1976 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) { 1977 for (int id = FIRST_WKID; id < WKID_LIMIT; id++) { 1978 it->push(well_known_klass_addr((WKID)id)); 1979 } 1980 } 1981 1982 void SystemDictionary::methods_do(void f(Method*)) { 1983 // Walk methods in loaded classes 1984 MutexLocker ml(ClassLoaderDataGraph_lock); 1985 ClassLoaderDataGraph::methods_do(f); 1986 // Walk method handle intrinsics 1987 invoke_method_table()->methods_do(f); 1988 } 1989 1990 // ---------------------------------------------------------------------------- 1991 // Initialization 1992 1993 void SystemDictionary::initialize(TRAPS) { 1994 // Allocate arrays 1995 _placeholders = new PlaceholderTable(_placeholder_table_size); 1996 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size); 1997 _resolution_errors = new ResolutionErrorTable(_resolution_error_size); 1998 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size); 1999 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize); 2000 2001 // Allocate private object used as system class loader lock 2002 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK); 2003 // Initialize basic classes 2004 resolve_well_known_classes(CHECK); 2005 } 2006 2007 // Compact table of directions on the initialization of klasses: 2008 static const short wk_init_info[] = { 2009 #define WK_KLASS_INIT_INFO(name, symbol) \ 2010 ((short)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol)), 2011 2012 WK_KLASSES_DO(WK_KLASS_INIT_INFO) 2013 #undef WK_KLASS_INIT_INFO 2014 0 2015 }; 2016 2017 #ifdef ASSERT 2018 bool SystemDictionary::is_well_known_klass(Symbol* class_name) { 2019 int sid; 2020 for (int i = 0; (sid = wk_init_info[i]) != 0; i++) { 2021 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid); 2022 if (class_name == symbol) { 2023 return true; 2024 } 2025 } 2026 return false; 2027 } 2028 #endif 2029 2030 bool SystemDictionary::resolve_wk_klass(WKID id, TRAPS) { 2031 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 2032 int sid = wk_init_info[id - FIRST_WKID]; 2033 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid); 2034 InstanceKlass** klassp = &_well_known_klasses[id]; 2035 2036 #if INCLUDE_CDS 2037 if (UseSharedSpaces && !JvmtiExport::should_post_class_prepare()) { 2038 InstanceKlass* k = *klassp; 2039 assert(k->is_shared_boot_class(), "must be"); 2040 2041 ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data(); 2042 quick_resolve(k, loader_data, Handle(), CHECK_false); 2043 return true; 2044 } 2045 #endif // INCLUDE_CDS 2046 2047 if (!is_wk_klass_loaded(*klassp)) { 2048 Klass* k = resolve_or_fail(symbol, true, CHECK_false); 2049 (*klassp) = InstanceKlass::cast(k); 2050 } 2051 return ((*klassp) != NULL); 2052 } 2053 2054 void SystemDictionary::resolve_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) { 2055 assert((int)start_id <= (int)limit_id, "IDs are out of order!"); 2056 for (int id = (int)start_id; id < (int)limit_id; id++) { 2057 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob"); 2058 resolve_wk_klass((WKID)id, CHECK); 2059 } 2060 2061 // move the starting value forward to the limit: 2062 start_id = limit_id; 2063 } 2064 2065 void SystemDictionary::resolve_well_known_classes(TRAPS) { 2066 assert(!Object_klass_loaded(), "well-known classes should only be initialized once"); 2067 2068 // Create the ModuleEntry for java.base. This call needs to be done here, 2069 // after vmSymbols::initialize() is called but before any classes are pre-loaded. 2070 ClassLoader::classLoader_init2(CHECK); 2071 2072 // Preload commonly used klasses 2073 WKID scan = FIRST_WKID; 2074 // first do Object, then String, Class 2075 #if INCLUDE_CDS 2076 if (UseSharedSpaces) { 2077 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK); 2078 2079 // It's unsafe to access the archived heap regions before they 2080 // are fixed up, so we must do the fixup as early as possible 2081 // before the archived java objects are accessed by functions 2082 // such as java_lang_Class::restore_archived_mirror and 2083 // ConstantPool::restore_unshareable_info (restores the archived 2084 // resolved_references array object). 2085 // 2086 // HeapShared::fixup_mapped_heap_regions() fills the empty 2087 // spaces in the archived heap regions and may use 2088 // SystemDictionary::Object_klass(), so we can do this only after 2089 // Object_klass is resolved. See the above resolve_wk_klasses_through() 2090 // call. No mirror objects are accessed/restored in the above call. 2091 // Mirrors are restored after java.lang.Class is loaded. 2092 HeapShared::fixup_mapped_heap_regions(); 2093 2094 // Initialize the constant pool for the Object_class 2095 assert(Object_klass()->is_shared(), "must be"); 2096 Object_klass()->constants()->restore_unshareable_info(CHECK); 2097 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 2098 } else 2099 #endif 2100 { 2101 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK); 2102 } 2103 2104 assert(WK_KLASS(Object_klass) != NULL, "well-known classes should now be initialized"); 2105 2106 java_lang_Object::register_natives(CHECK); 2107 2108 // Calculate offsets for String and Class classes since they are loaded and 2109 // can be used after this point. 2110 java_lang_String::compute_offsets(); 2111 java_lang_Class::compute_offsets(); 2112 2113 // Fixup mirrors for classes loaded before java.lang.Class. 2114 Universe::initialize_basic_type_mirrors(CHECK); 2115 Universe::fixup_mirrors(CHECK); 2116 2117 // do a bunch more: 2118 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK); 2119 2120 // The offsets for jlr.Reference must be computed before 2121 // InstanceRefKlass::update_nonstatic_oop_maps is called. That function uses 2122 // the offsets to remove the referent and discovered fields from the oop maps, 2123 // as they are treated in a special way by the GC. Removing these oops from the 2124 // oop maps must be done before the usual subclasses of jlr.Reference are loaded. 2125 java_lang_ref_Reference::compute_offsets(); 2126 2127 // Preload ref klasses and set reference types 2128 WK_KLASS(Reference_klass)->set_reference_type(REF_OTHER); 2129 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass)); 2130 2131 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK); 2132 WK_KLASS(SoftReference_klass)->set_reference_type(REF_SOFT); 2133 WK_KLASS(WeakReference_klass)->set_reference_type(REF_WEAK); 2134 WK_KLASS(FinalReference_klass)->set_reference_type(REF_FINAL); 2135 WK_KLASS(PhantomReference_klass)->set_reference_type(REF_PHANTOM); 2136 2137 // JSR 292 classes 2138 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass); 2139 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass); 2140 resolve_wk_klasses_until(jsr292_group_start, scan, CHECK); 2141 resolve_wk_klasses_through(jsr292_group_end, scan, CHECK); 2142 WKID last = WKID_LIMIT; 2143 resolve_wk_klasses_until(last, scan, CHECK); 2144 2145 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass); 2146 _box_klasses[T_CHAR] = WK_KLASS(Character_klass); 2147 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass); 2148 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass); 2149 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass); 2150 _box_klasses[T_SHORT] = WK_KLASS(Short_klass); 2151 _box_klasses[T_INT] = WK_KLASS(Integer_klass); 2152 _box_klasses[T_LONG] = WK_KLASS(Long_klass); 2153 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass); 2154 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass); 2155 2156 #ifdef ASSERT 2157 if (UseSharedSpaces) { 2158 JVMTI_ONLY(assert(JvmtiExport::is_early_phase(), 2159 "All well known classes must be resolved in JVMTI early phase")); 2160 for (int i = FIRST_WKID; i < last; i++) { 2161 InstanceKlass* k = _well_known_klasses[i]; 2162 assert(k->is_shared(), "must not be replaced by JVMTI class file load hook"); 2163 } 2164 } 2165 #endif 2166 } 2167 2168 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer). 2169 // If so, returns the basic type it holds. If not, returns T_OBJECT. 2170 BasicType SystemDictionary::box_klass_type(Klass* k) { 2171 assert(k != NULL, ""); 2172 for (int i = T_BOOLEAN; i < T_VOID+1; i++) { 2173 if (_box_klasses[i] == k) 2174 return (BasicType)i; 2175 } 2176 return T_OBJECT; 2177 } 2178 2179 // Constraints on class loaders. The details of the algorithm can be 2180 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java 2181 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is 2182 // that the dictionary needs to maintain a set of contraints that 2183 // must be satisfied by all classes in the dictionary. 2184 // if defining is true, then LinkageError if already in dictionary 2185 // if initiating loader, then ok if InstanceKlass matches existing entry 2186 2187 void SystemDictionary::check_constraints(unsigned int d_hash, 2188 InstanceKlass* k, 2189 Handle class_loader, 2190 bool defining, 2191 TRAPS) { 2192 ResourceMark rm(THREAD); 2193 stringStream ss; 2194 bool throwException = false; 2195 2196 { 2197 Symbol *name = k->name(); 2198 ClassLoaderData *loader_data = class_loader_data(class_loader); 2199 2200 MutexLocker mu(THREAD, SystemDictionary_lock); 2201 2202 InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary()); 2203 if (check != NULL) { 2204 // If different InstanceKlass - duplicate class definition, 2205 // else - ok, class loaded by a different thread in parallel. 2206 // We should only have found it if it was done loading and ok to use. 2207 // The dictionary only holds instance classes, placeholders 2208 // also hold array classes. 2209 2210 assert(check->is_instance_klass(), "noninstance in systemdictionary"); 2211 if ((defining == true) || (k != check)) { 2212 throwException = true; 2213 ss.print("loader %s", loader_data->loader_name_and_id()); 2214 ss.print(" attempted duplicate %s definition for %s. (%s)", 2215 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true)); 2216 } else { 2217 return; 2218 } 2219 } 2220 2221 #ifdef ASSERT 2222 Symbol* ph_check = find_placeholder(name, loader_data); 2223 assert(ph_check == NULL || ph_check == name, "invalid symbol"); 2224 #endif 2225 2226 if (throwException == false) { 2227 if (constraints()->check_or_update(k, class_loader, name) == false) { 2228 throwException = true; 2229 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id()); 2230 ss.print(" wants to load %s %s.", 2231 k->external_kind(), k->external_name()); 2232 Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader); 2233 if (existing_klass != NULL && existing_klass->class_loader() != class_loader()) { 2234 ss.print(" A different %s with the same name was previously loaded by %s. (%s)", 2235 existing_klass->external_kind(), 2236 existing_klass->class_loader_data()->loader_name_and_id(), 2237 existing_klass->class_in_module_of_loader(false, true)); 2238 } else { 2239 ss.print(" (%s)", k->class_in_module_of_loader(false, true)); 2240 } 2241 } 2242 } 2243 } 2244 2245 // Throw error now if needed (cannot throw while holding 2246 // SystemDictionary_lock because of rank ordering) 2247 if (throwException == true) { 2248 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string()); 2249 } 2250 } 2251 2252 // Update class loader data dictionary - done after check_constraint and add_to_hierachy 2253 // have been called. 2254 void SystemDictionary::update_dictionary(unsigned int d_hash, 2255 int p_index, unsigned int p_hash, 2256 InstanceKlass* k, 2257 Handle class_loader, 2258 TRAPS) { 2259 // Compile_lock prevents systemDictionary updates during compilations 2260 assert_locked_or_safepoint(Compile_lock); 2261 Symbol* name = k->name(); 2262 ClassLoaderData *loader_data = class_loader_data(class_loader); 2263 2264 { 2265 MutexLocker mu1(THREAD, SystemDictionary_lock); 2266 2267 // Make a new dictionary entry. 2268 Dictionary* dictionary = loader_data->dictionary(); 2269 InstanceKlass* sd_check = find_class(d_hash, name, dictionary); 2270 if (sd_check == NULL) { 2271 dictionary->add_klass(d_hash, name, k); 2272 } 2273 #ifdef ASSERT 2274 sd_check = find_class(d_hash, name, dictionary); 2275 assert (sd_check != NULL, "should have entry in dictionary"); 2276 // Note: there may be a placeholder entry: for circularity testing 2277 // or for parallel defines 2278 #endif 2279 SystemDictionary_lock->notify_all(); 2280 } 2281 } 2282 2283 2284 // Try to find a class name using the loader constraints. The 2285 // loader constraints might know about a class that isn't fully loaded 2286 // yet and these will be ignored. 2287 Klass* SystemDictionary::find_constrained_instance_or_array_klass( 2288 Symbol* class_name, Handle class_loader, TRAPS) { 2289 2290 // First see if it has been loaded directly. 2291 // Force the protection domain to be null. (This removes protection checks.) 2292 Handle no_protection_domain; 2293 Klass* klass = find_instance_or_array_klass(class_name, class_loader, 2294 no_protection_domain, CHECK_NULL); 2295 if (klass != NULL) 2296 return klass; 2297 2298 // Now look to see if it has been loaded elsewhere, and is subject to 2299 // a loader constraint that would require this loader to return the 2300 // klass that is already loaded. 2301 if (Signature::is_array(class_name)) { 2302 // For array classes, their Klass*s are not kept in the 2303 // constraint table. The element Klass*s are. 2304 SignatureStream ss(class_name, false); 2305 int ndims = ss.skip_array_prefix(); // skip all '['s 2306 BasicType t = ss.type(); 2307 if (t != T_OBJECT) { 2308 klass = Universe::typeArrayKlassObj(t); 2309 } else { 2310 MutexLocker mu(THREAD, SystemDictionary_lock); 2311 klass = constraints()->find_constrained_klass(ss.as_symbol(), class_loader); 2312 } 2313 // If element class already loaded, allocate array klass 2314 if (klass != NULL) { 2315 klass = klass->array_klass_or_null(ndims); 2316 } 2317 } else { 2318 MutexLocker mu(THREAD, SystemDictionary_lock); 2319 // Non-array classes are easy: simply check the constraint table. 2320 klass = constraints()->find_constrained_klass(class_name, class_loader); 2321 } 2322 2323 return klass; 2324 } 2325 2326 bool SystemDictionary::add_loader_constraint(Symbol* class_name, 2327 Klass* klass_being_linked, 2328 Handle class_loader1, 2329 Handle class_loader2, 2330 Thread* THREAD) { 2331 ClassLoaderData* loader_data1 = class_loader_data(class_loader1); 2332 ClassLoaderData* loader_data2 = class_loader_data(class_loader2); 2333 2334 Symbol* constraint_name = NULL; 2335 2336 if (!Signature::is_array(class_name)) { 2337 constraint_name = class_name; 2338 } else { 2339 // For array classes, their Klass*s are not kept in the 2340 // constraint table. The element classes are. 2341 SignatureStream ss(class_name, false); 2342 ss.skip_array_prefix(); // skip all '['s 2343 if (!ss.has_envelope()) { 2344 return true; // primitive types always pass 2345 } 2346 constraint_name = ss.as_symbol(); 2347 // Increment refcount to keep constraint_name alive after 2348 // SignatureStream is destructed. It will be decremented below 2349 // before returning. 2350 constraint_name->increment_refcount(); 2351 } 2352 2353 Dictionary* dictionary1 = loader_data1->dictionary(); 2354 unsigned int d_hash1 = dictionary1->compute_hash(constraint_name); 2355 2356 Dictionary* dictionary2 = loader_data2->dictionary(); 2357 unsigned int d_hash2 = dictionary2->compute_hash(constraint_name); 2358 2359 { 2360 MutexLocker mu_s(THREAD, SystemDictionary_lock); 2361 InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1); 2362 InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2); 2363 bool result = constraints()->add_entry(constraint_name, klass1, class_loader1, 2364 klass2, class_loader2); 2365 #if INCLUDE_CDS 2366 if (Arguments::is_dumping_archive() && klass_being_linked != NULL && 2367 !klass_being_linked->is_shared()) { 2368 SystemDictionaryShared::record_linking_constraint(constraint_name, 2369 InstanceKlass::cast(klass_being_linked), 2370 class_loader1, class_loader2, THREAD); 2371 } 2372 #endif // INCLUDE_CDS 2373 if (Signature::is_array(class_name)) { 2374 constraint_name->decrement_refcount(); 2375 } 2376 return result; 2377 } 2378 } 2379 2380 // Add entry to resolution error table to record the error when the first 2381 // attempt to resolve a reference to a class has failed. 2382 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which, 2383 Symbol* error, Symbol* message) { 2384 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2385 int index = resolution_errors()->hash_to_index(hash); 2386 { 2387 MutexLocker ml(Thread::current(), SystemDictionary_lock); 2388 resolution_errors()->add_entry(index, hash, pool, which, error, message); 2389 } 2390 } 2391 2392 // Delete a resolution error for RedefineClasses for a constant pool is going away 2393 void SystemDictionary::delete_resolution_error(ConstantPool* pool) { 2394 resolution_errors()->delete_entry(pool); 2395 } 2396 2397 // Lookup resolution error table. Returns error if found, otherwise NULL. 2398 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which, 2399 Symbol** message) { 2400 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2401 int index = resolution_errors()->hash_to_index(hash); 2402 { 2403 MutexLocker ml(Thread::current(), SystemDictionary_lock); 2404 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which); 2405 if (entry != NULL) { 2406 *message = entry->message(); 2407 return entry->error(); 2408 } else { 2409 return NULL; 2410 } 2411 } 2412 } 2413 2414 // Add an entry to resolution error table to record an error in resolving or 2415 // validating a nest host. This is used to construct informative error 2416 // messages when IllegalAccessError's occur. If an entry already exists it will 2417 // be updated with the nest host error message. 2418 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool, 2419 int which, 2420 const char* message) { 2421 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2422 int index = resolution_errors()->hash_to_index(hash); 2423 { 2424 MutexLocker ml(Thread::current(), SystemDictionary_lock); 2425 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which); 2426 if (entry != NULL) { 2427 assert(entry->nest_host_error() == NULL, "Nest host error message already set!"); 2428 entry->set_nest_host_error(message); 2429 } else { 2430 resolution_errors()->add_entry(index, hash, pool, which, message); 2431 } 2432 } 2433 } 2434 2435 // Lookup any nest host error 2436 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) { 2437 unsigned int hash = resolution_errors()->compute_hash(pool, which); 2438 int index = resolution_errors()->hash_to_index(hash); 2439 { 2440 MutexLocker ml(Thread::current(), SystemDictionary_lock); 2441 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which); 2442 if (entry != NULL) { 2443 return entry->nest_host_error(); 2444 } else { 2445 return NULL; 2446 } 2447 } 2448 } 2449 2450 2451 // Signature constraints ensure that callers and callees agree about 2452 // the meaning of type names in their signatures. This routine is the 2453 // intake for constraints. It collects them from several places: 2454 // 2455 // * LinkResolver::resolve_method (if check_access is true) requires 2456 // that the resolving class (the caller) and the defining class of 2457 // the resolved method (the callee) agree on each type in the 2458 // method's signature. 2459 // 2460 // * LinkResolver::resolve_interface_method performs exactly the same 2461 // checks. 2462 // 2463 // * LinkResolver::resolve_field requires that the constant pool 2464 // attempting to link to a field agree with the field's defining 2465 // class about the type of the field signature. 2466 // 2467 // * klassVtable::initialize_vtable requires that, when a class 2468 // overrides a vtable entry allocated by a superclass, that the 2469 // overriding method (i.e., the callee) agree with the superclass 2470 // on each type in the method's signature. 2471 // 2472 // * klassItable::initialize_itable requires that, when a class fills 2473 // in its itables, for each non-abstract method installed in an 2474 // itable, the method (i.e., the callee) agree with the interface 2475 // on each type in the method's signature. 2476 // 2477 // All those methods have a boolean (check_access, checkconstraints) 2478 // which turns off the checks. This is used from specialized contexts 2479 // such as bootstrapping, dumping, and debugging. 2480 // 2481 // No direct constraint is placed between the class and its 2482 // supertypes. Constraints are only placed along linked relations 2483 // between callers and callees. When a method overrides or implements 2484 // an abstract method in a supertype (superclass or interface), the 2485 // constraints are placed as if the supertype were the caller to the 2486 // overriding method. (This works well, since callers to the 2487 // supertype have already established agreement between themselves and 2488 // the supertype.) As a result of all this, a class can disagree with 2489 // its supertype about the meaning of a type name, as long as that 2490 // class neither calls a relevant method of the supertype, nor is 2491 // called (perhaps via an override) from the supertype. 2492 // 2493 // 2494 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2) 2495 // 2496 // Make sure all class components (including arrays) in the given 2497 // signature will be resolved to the same class in both loaders. 2498 // Returns the name of the type that failed a loader constraint check, or 2499 // NULL if no constraint failed. No exception except OOME is thrown. 2500 // Arrays are not added to the loader constraint table, their elements are. 2501 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature, 2502 Klass* klass_being_linked, 2503 Handle loader1, Handle loader2, 2504 bool is_method, TRAPS) { 2505 // Nothing to do if loaders are the same. 2506 if (loader1() == loader2()) { 2507 return NULL; 2508 } 2509 2510 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) { 2511 if (ss.is_reference()) { 2512 Symbol* sig = ss.as_symbol(); 2513 // Note: In the future, if template-like types can take 2514 // arguments, we will want to recognize them and dig out class 2515 // names hiding inside the argument lists. 2516 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2, THREAD)) { 2517 return sig; 2518 } 2519 } 2520 } 2521 return NULL; 2522 } 2523 2524 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid, 2525 Symbol* signature, 2526 TRAPS) { 2527 methodHandle empty; 2528 assert(MethodHandles::is_signature_polymorphic(iid) && 2529 MethodHandles::is_signature_polymorphic_intrinsic(iid) && 2530 iid != vmIntrinsics::_invokeGeneric, 2531 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid)); 2532 2533 unsigned int hash = invoke_method_table()->compute_hash(signature, iid); 2534 int index = invoke_method_table()->hash_to_index(hash); 2535 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid); 2536 methodHandle m; 2537 if (spe == NULL || spe->method() == NULL) { 2538 spe = NULL; 2539 // Must create lots of stuff here, but outside of the SystemDictionary lock. 2540 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_NULL); 2541 if (!Arguments::is_interpreter_only()) { 2542 // Generate a compiled form of the MH intrinsic. 2543 AdapterHandlerLibrary::create_native_wrapper(m); 2544 // Check if have the compiled code. 2545 if (!m->has_compiled_code()) { 2546 THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(), 2547 "Out of space in CodeCache for method handle intrinsic"); 2548 } 2549 } 2550 // Now grab the lock. We might have to throw away the new method, 2551 // if a racing thread has managed to install one at the same time. 2552 { 2553 MutexLocker ml(THREAD, SystemDictionary_lock); 2554 spe = invoke_method_table()->find_entry(index, hash, signature, iid); 2555 if (spe == NULL) 2556 spe = invoke_method_table()->add_entry(index, hash, signature, iid); 2557 if (spe->method() == NULL) 2558 spe->set_method(m()); 2559 } 2560 } 2561 2562 assert(spe != NULL && spe->method() != NULL, ""); 2563 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() && 2564 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()), 2565 "MH intrinsic invariant"); 2566 return spe->method(); 2567 } 2568 2569 // Helper for unpacking the return value from linkMethod and linkCallSite. 2570 static Method* unpack_method_and_appendix(Handle mname, 2571 Klass* accessing_klass, 2572 objArrayHandle appendix_box, 2573 Handle* appendix_result, 2574 TRAPS) { 2575 if (mname.not_null()) { 2576 Method* m = java_lang_invoke_MemberName::vmtarget(mname()); 2577 if (m != NULL) { 2578 oop appendix = appendix_box->obj_at(0); 2579 LogTarget(Info, methodhandles) lt; 2580 if (lt.develop_is_enabled()) { 2581 ResourceMark rm(THREAD); 2582 LogStream ls(lt); 2583 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m)); 2584 m->print_on(&ls); 2585 if (appendix != NULL) { ls.print("appendix = "); appendix->print_on(&ls); } 2586 ls.cr(); 2587 } 2588 2589 (*appendix_result) = Handle(THREAD, appendix); 2590 // the target is stored in the cpCache and if a reference to this 2591 // MemberName is dropped we need a way to make sure the 2592 // class_loader containing this method is kept alive. 2593 methodHandle mh(THREAD, m); // record_dependency can safepoint. 2594 ClassLoaderData* this_key = accessing_klass->class_loader_data(); 2595 this_key->record_dependency(m->method_holder()); 2596 return mh(); 2597 } 2598 } 2599 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives"); 2600 } 2601 2602 Method* SystemDictionary::find_method_handle_invoker(Klass* klass, 2603 Symbol* name, 2604 Symbol* signature, 2605 Klass* accessing_klass, 2606 Handle *appendix_result, 2607 TRAPS) { 2608 assert(THREAD->can_call_java() ,""); 2609 Handle method_type = 2610 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL); 2611 2612 int ref_kind = JVM_REF_invokeVirtual; 2613 oop name_oop = StringTable::intern(name, CHECK_NULL); 2614 Handle name_str (THREAD, name_oop); 2615 objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_NULL); 2616 assert(appendix_box->obj_at(0) == NULL, ""); 2617 2618 // This should not happen. JDK code should take care of that. 2619 if (accessing_klass == NULL || method_type.is_null()) { 2620 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle"); 2621 } 2622 2623 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName 2624 JavaCallArguments args; 2625 args.push_oop(Handle(THREAD, accessing_klass->java_mirror())); 2626 args.push_int(ref_kind); 2627 args.push_oop(Handle(THREAD, klass->java_mirror())); 2628 args.push_oop(name_str); 2629 args.push_oop(method_type); 2630 args.push_oop(appendix_box); 2631 JavaValue result(T_OBJECT); 2632 JavaCalls::call_static(&result, 2633 SystemDictionary::MethodHandleNatives_klass(), 2634 vmSymbols::linkMethod_name(), 2635 vmSymbols::linkMethod_signature(), 2636 &args, CHECK_NULL); 2637 Handle mname(THREAD, (oop) result.get_jobject()); 2638 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD); 2639 } 2640 2641 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks. 2642 // We must ensure that all class loaders everywhere will reach this class, for any client. 2643 // This is a safe bet for public classes in java.lang, such as Object and String. 2644 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types. 2645 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util. 2646 static bool is_always_visible_class(oop mirror) { 2647 Klass* klass = java_lang_Class::as_Klass(mirror); 2648 if (klass->is_objArray_klass()) { 2649 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type 2650 } 2651 if (klass->is_typeArray_klass()) { 2652 return true; // primitive array 2653 } 2654 assert(klass->is_instance_klass(), "%s", klass->external_name()); 2655 return klass->is_public() && 2656 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang 2657 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke 2658 } 2659 2660 // Find or construct the Java mirror (java.lang.Class instance) for 2661 // the given field type signature, as interpreted relative to the 2662 // given class loader. Handles primitives, void, references, arrays, 2663 // and all other reflectable types, except method types. 2664 // N.B. Code in reflection should use this entry point. 2665 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature, 2666 Klass* accessing_klass, 2667 Handle class_loader, 2668 Handle protection_domain, 2669 SignatureStream::FailureMode failure_mode, 2670 TRAPS) { 2671 assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()), 2672 "one or the other, or perhaps neither"); 2673 2674 // What we have here must be a valid field descriptor, 2675 // and all valid field descriptors are supported. 2676 // Produce the same java.lang.Class that reflection reports. 2677 if (accessing_klass != NULL) { 2678 class_loader = Handle(THREAD, accessing_klass->class_loader()); 2679 protection_domain = Handle(THREAD, accessing_klass->protection_domain()); 2680 } 2681 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false); 2682 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH); 2683 if (mirror_oop == NULL) { 2684 return Handle(); // report failure this way 2685 } 2686 Handle mirror(THREAD, mirror_oop); 2687 2688 if (accessing_klass != NULL) { 2689 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve. 2690 Klass* sel_klass = java_lang_Class::as_Klass(mirror()); 2691 if (sel_klass != NULL) { 2692 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH); 2693 } 2694 } 2695 return mirror; 2696 } 2697 2698 2699 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given 2700 // signature, as interpreted relative to the given class loader. 2701 // Because of class loader constraints, all method handle usage must be 2702 // consistent with this loader. 2703 Handle SystemDictionary::find_method_handle_type(Symbol* signature, 2704 Klass* accessing_klass, 2705 TRAPS) { 2706 Handle empty; 2707 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics 2708 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid); 2709 int index = invoke_method_table()->hash_to_index(hash); 2710 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2711 if (spe != NULL && spe->method_type() != NULL) { 2712 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), ""); 2713 return Handle(THREAD, spe->method_type()); 2714 } else if (!THREAD->can_call_java()) { 2715 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME 2716 return Handle(); // do not attempt from within compiler, unless it was cached 2717 } 2718 2719 Handle class_loader, protection_domain; 2720 if (accessing_klass != NULL) { 2721 class_loader = Handle(THREAD, accessing_klass->class_loader()); 2722 protection_domain = Handle(THREAD, accessing_klass->protection_domain()); 2723 } 2724 bool can_be_cached = true; 2725 int npts = ArgumentCount(signature).size(); 2726 objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty)); 2727 int arg = 0; 2728 Handle rt; // the return type from the signature 2729 ResourceMark rm(THREAD); 2730 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) { 2731 oop mirror = NULL; 2732 if (can_be_cached) { 2733 // Use neutral class loader to lookup candidate classes to be placed in the cache. 2734 mirror = ss.as_java_mirror(Handle(), Handle(), 2735 SignatureStream::ReturnNull, CHECK_(empty)); 2736 if (mirror == NULL || (ss.is_reference() && !is_always_visible_class(mirror))) { 2737 // Fall back to accessing_klass context. 2738 can_be_cached = false; 2739 } 2740 } 2741 if (!can_be_cached) { 2742 // Resolve, throwing a real error if it doesn't work. 2743 mirror = ss.as_java_mirror(class_loader, protection_domain, 2744 SignatureStream::NCDFError, CHECK_(empty)); 2745 } 2746 assert(mirror != NULL, "%s", ss.as_symbol()->as_C_string()); 2747 if (ss.at_return_type()) 2748 rt = Handle(THREAD, mirror); 2749 else 2750 pts->obj_at_put(arg++, mirror); 2751 2752 // Check accessibility. 2753 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) { 2754 Klass* sel_klass = java_lang_Class::as_Klass(mirror); 2755 mirror = NULL; // safety 2756 // Emulate ConstantPool::verify_constant_pool_resolve. 2757 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty)); 2758 } 2759 } 2760 assert(arg == npts, ""); 2761 2762 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType 2763 JavaCallArguments args(Handle(THREAD, rt())); 2764 args.push_oop(pts); 2765 JavaValue result(T_OBJECT); 2766 JavaCalls::call_static(&result, 2767 SystemDictionary::MethodHandleNatives_klass(), 2768 vmSymbols::findMethodHandleType_name(), 2769 vmSymbols::findMethodHandleType_signature(), 2770 &args, CHECK_(empty)); 2771 Handle method_type(THREAD, (oop) result.get_jobject()); 2772 2773 if (can_be_cached) { 2774 // We can cache this MethodType inside the JVM. 2775 MutexLocker ml(THREAD, SystemDictionary_lock); 2776 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid); 2777 if (spe == NULL) 2778 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid); 2779 if (spe->method_type() == NULL) { 2780 spe->set_method_type(method_type()); 2781 } 2782 } 2783 2784 // report back to the caller with the MethodType 2785 return method_type; 2786 } 2787 2788 Handle SystemDictionary::find_field_handle_type(Symbol* signature, 2789 Klass* accessing_klass, 2790 TRAPS) { 2791 Handle empty; 2792 ResourceMark rm(THREAD); 2793 SignatureStream ss(signature, /*is_method=*/ false); 2794 if (!ss.is_done()) { 2795 Handle class_loader, protection_domain; 2796 if (accessing_klass != NULL) { 2797 class_loader = Handle(THREAD, accessing_klass->class_loader()); 2798 protection_domain = Handle(THREAD, accessing_klass->protection_domain()); 2799 } 2800 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty)); 2801 ss.next(); 2802 if (ss.is_done()) { 2803 return Handle(THREAD, mirror); 2804 } 2805 } 2806 return empty; 2807 } 2808 2809 // Ask Java code to find or construct a method handle constant. 2810 Handle SystemDictionary::link_method_handle_constant(Klass* caller, 2811 int ref_kind, //e.g., JVM_REF_invokeVirtual 2812 Klass* callee, 2813 Symbol* name, 2814 Symbol* signature, 2815 TRAPS) { 2816 Handle empty; 2817 if (caller == NULL) { 2818 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty); 2819 } 2820 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty)); 2821 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty)); 2822 2823 // Put symbolic info from the MH constant into freshly created MemberName and resolve it. 2824 Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty)); 2825 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror()); 2826 java_lang_invoke_MemberName::set_name (mname(), name_str()); 2827 java_lang_invoke_MemberName::set_type (mname(), signature_str()); 2828 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind)); 2829 2830 if (ref_kind == JVM_REF_invokeVirtual && 2831 MethodHandles::is_signature_polymorphic_public_name(callee, name)) { 2832 // Skip resolution for public signature polymorphic methods such as 2833 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle 2834 // They require appendix argument which MemberName resolution doesn't handle. 2835 // There's special logic on JDK side to handle them 2836 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()). 2837 } else { 2838 MethodHandles::resolve_MemberName(mname, caller, /*speculative_resolve*/false, CHECK_(empty)); 2839 } 2840 2841 // After method/field resolution succeeded, it's safe to resolve MH signature as well. 2842 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty)); 2843 2844 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle 2845 JavaCallArguments args; 2846 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class 2847 args.push_int(ref_kind); 2848 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class 2849 args.push_oop(name_str); 2850 args.push_oop(type); 2851 JavaValue result(T_OBJECT); 2852 JavaCalls::call_static(&result, 2853 SystemDictionary::MethodHandleNatives_klass(), 2854 vmSymbols::linkMethodHandleConstant_name(), 2855 vmSymbols::linkMethodHandleConstant_signature(), 2856 &args, CHECK_(empty)); 2857 return Handle(THREAD, (oop) result.get_jobject()); 2858 } 2859 2860 // Ask Java to run a bootstrap method, in order to create a dynamic call site 2861 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry 2862 // with linkage results being stored back into the bootstrap specifier. 2863 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) { 2864 // Resolve the bootstrap specifier, its name, type, and static arguments 2865 bootstrap_specifier.resolve_bsm(CHECK); 2866 2867 // This should not happen. JDK code should take care of that. 2868 if (bootstrap_specifier.caller() == NULL || bootstrap_specifier.type_arg().is_null()) { 2869 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument"); 2870 } 2871 2872 bool is_indy = bootstrap_specifier.is_method_call(); 2873 objArrayHandle appendix_box; 2874 if (is_indy) { 2875 // Some method calls may require an appendix argument. Arrange to receive it. 2876 appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK); 2877 assert(appendix_box->obj_at(0) == NULL, ""); 2878 } 2879 2880 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, condy_index, bsm, type, info) 2881 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix) 2882 JavaCallArguments args; 2883 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror())); 2884 args.push_int(bootstrap_specifier.bss_index()); 2885 args.push_oop(bootstrap_specifier.bsm()); 2886 args.push_oop(bootstrap_specifier.name_arg()); 2887 args.push_oop(bootstrap_specifier.type_arg()); 2888 args.push_oop(bootstrap_specifier.arg_values()); 2889 if (is_indy) { 2890 args.push_oop(appendix_box); 2891 } 2892 JavaValue result(T_OBJECT); 2893 JavaCalls::call_static(&result, 2894 SystemDictionary::MethodHandleNatives_klass(), 2895 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(), 2896 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(), 2897 &args, CHECK); 2898 2899 Handle value(THREAD, (oop) result.get_jobject()); 2900 if (is_indy) { 2901 Handle appendix; 2902 Method* method = unpack_method_and_appendix(value, 2903 bootstrap_specifier.caller(), 2904 appendix_box, 2905 &appendix, CHECK); 2906 methodHandle mh(THREAD, method); 2907 bootstrap_specifier.set_resolved_method(mh, appendix); 2908 } else { 2909 bootstrap_specifier.set_resolved_value(value); 2910 } 2911 2912 // sanity check 2913 assert(bootstrap_specifier.is_resolved() || 2914 (bootstrap_specifier.is_method_call() && 2915 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed"); 2916 } 2917 2918 // Protection domain cache table handling 2919 2920 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) { 2921 return _pd_cache_table->get(protection_domain); 2922 } 2923 2924 // ---------------------------------------------------------------------------- 2925 2926 void SystemDictionary::print_on(outputStream *st) { 2927 CDS_ONLY(SystemDictionaryShared::print_on(st)); 2928 GCMutexLocker mu(SystemDictionary_lock); 2929 2930 ClassLoaderDataGraph::print_dictionary(st); 2931 2932 // Placeholders 2933 placeholders()->print_on(st); 2934 st->cr(); 2935 2936 // loader constraints - print under SD_lock 2937 constraints()->print_on(st); 2938 st->cr(); 2939 2940 _pd_cache_table->print_on(st); 2941 st->cr(); 2942 } 2943 2944 void SystemDictionary::print() { print_on(tty); } 2945 2946 void SystemDictionary::verify() { 2947 guarantee(constraints() != NULL, 2948 "Verify of loader constraints failed"); 2949 guarantee(placeholders()->number_of_entries() >= 0, 2950 "Verify of placeholders failed"); 2951 2952 GCMutexLocker mu(SystemDictionary_lock); 2953 2954 // Verify dictionary 2955 ClassLoaderDataGraph::verify_dictionary(); 2956 2957 placeholders()->verify(); 2958 2959 // Verify constraint table 2960 guarantee(constraints() != NULL, "Verify of loader constraints failed"); 2961 constraints()->verify(placeholders()); 2962 2963 _pd_cache_table->verify(); 2964 } 2965 2966 void SystemDictionary::dump(outputStream *st, bool verbose) { 2967 assert_locked_or_safepoint(SystemDictionary_lock); 2968 if (verbose) { 2969 print_on(st); 2970 } else { 2971 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st)); 2972 ClassLoaderDataGraph::print_table_statistics(st); 2973 placeholders()->print_table_statistics(st, "Placeholder Table"); 2974 constraints()->print_table_statistics(st, "LoaderConstraints Table"); 2975 pd_cache_table()->print_table_statistics(st, "ProtectionDomainCache Table"); 2976 } 2977 } 2978 2979 TableStatistics SystemDictionary::placeholders_statistics() { 2980 MutexLocker ml(SystemDictionary_lock); 2981 return placeholders()->statistics_calculate(); 2982 } 2983 2984 TableStatistics SystemDictionary::loader_constraints_statistics() { 2985 MutexLocker ml(SystemDictionary_lock); 2986 return constraints()->statistics_calculate(); 2987 } 2988 2989 TableStatistics SystemDictionary::protection_domain_cache_statistics() { 2990 MutexLocker ml(SystemDictionary_lock); 2991 return pd_cache_table()->statistics_calculate(); 2992 } 2993 2994 // Utility for dumping dictionaries. 2995 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) : 2996 DCmdWithParser(output, heap), 2997 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders", 2998 "BOOLEAN", false, "false") { 2999 _dcmdparser.add_dcmd_option(&_verbose); 3000 } 3001 3002 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) { 3003 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict, 3004 _verbose.value()); 3005 VMThread::execute(&dumper); 3006 } 3007 3008 int SystemDictionaryDCmd::num_arguments() { 3009 ResourceMark rm; 3010 SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false); 3011 if (dcmd != NULL) { 3012 DCmdMark mark(dcmd); 3013 return dcmd->_dcmdparser.num_arguments(); 3014 } else { 3015 return 0; 3016 } 3017 }