1 /* 2 * Copyright (c) 1997, 2025, 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 "cds/aotClassLocation.hpp" 26 #include "cds/cdsConfig.hpp" 27 #include "cds/heapShared.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/classLoadInfo.hpp" 35 #include "classfile/dictionary.hpp" 36 #include "classfile/javaClasses.inline.hpp" 37 #include "classfile/klassFactory.hpp" 38 #include "classfile/loaderConstraints.hpp" 39 #include "classfile/packageEntry.hpp" 40 #include "classfile/placeholders.hpp" 41 #include "classfile/resolutionErrors.hpp" 42 #include "classfile/stringTable.hpp" 43 #include "classfile/symbolTable.hpp" 44 #include "classfile/systemDictionary.hpp" 45 #include "classfile/vmClasses.hpp" 46 #include "classfile/vmSymbols.hpp" 47 #include "gc/shared/gcTraceTime.inline.hpp" 48 #include "interpreter/bootstrapInfo.hpp" 49 #include "jfr/jfrEvents.hpp" 50 #include "jvm.h" 51 #include "logging/log.hpp" 52 #include "logging/logStream.hpp" 53 #include "memory/metaspaceClosure.hpp" 54 #include "memory/oopFactory.hpp" 55 #include "memory/resourceArea.hpp" 56 #include "memory/universe.hpp" 57 #include "oops/access.inline.hpp" 58 #include "oops/fieldStreams.inline.hpp" 59 #include "oops/instanceKlass.hpp" 60 #include "oops/klass.inline.hpp" 61 #include "oops/method.inline.hpp" 62 #include "oops/objArrayKlass.hpp" 63 #include "oops/objArrayOop.inline.hpp" 64 #include "oops/oop.inline.hpp" 65 #include "oops/oop.hpp" 66 #include "oops/oopHandle.hpp" 67 #include "oops/oopHandle.inline.hpp" 68 #include "oops/symbol.hpp" 69 #include "oops/typeArrayKlass.hpp" 70 #include "oops/inlineKlass.inline.hpp" 71 #include "prims/jvmtiExport.hpp" 72 #include "prims/methodHandles.hpp" 73 #include "runtime/arguments.hpp" 74 #include "runtime/atomic.hpp" 75 #include "runtime/handles.inline.hpp" 76 #include "runtime/java.hpp" 77 #include "runtime/javaCalls.hpp" 78 #include "runtime/mutexLocker.hpp" 79 #include "runtime/os.hpp" 80 #include "runtime/sharedRuntime.hpp" 81 #include "runtime/signature.hpp" 82 #include "runtime/synchronizer.hpp" 83 #include "services/classLoadingService.hpp" 84 #include "services/diagnosticCommand.hpp" 85 #include "services/finalizerService.hpp" 86 #include "services/threadService.hpp" 87 #include "utilities/growableArray.hpp" 88 #include "utilities/macros.hpp" 89 #include "utilities/utf8.hpp" 90 #if INCLUDE_CDS 91 #include "classfile/systemDictionaryShared.hpp" 92 #endif 93 #if INCLUDE_JFR 94 #include "jfr/jfr.hpp" 95 #endif 96 97 class InvokeMethodKey : public StackObj { 98 private: 99 Symbol* _symbol; 100 intptr_t _iid; 101 102 public: 103 InvokeMethodKey(Symbol* symbol, intptr_t iid) : 104 _symbol(symbol), 105 _iid(iid) {} 106 107 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){ 108 return k1._symbol == k2._symbol && k1._iid == k2._iid; 109 } 110 111 static unsigned int compute_hash(const InvokeMethodKey &k) { 112 Symbol* sym = k._symbol; 113 intptr_t iid = k._iid; 114 unsigned int hash = (unsigned int) sym -> identity_hash(); 115 return (unsigned int) (hash ^ iid); 116 } 117 118 }; 119 120 using InvokeMethodIntrinsicTable = ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass, 121 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>; 122 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table; 123 using InvokeMethodTypeTable = ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>; 124 static InvokeMethodTypeTable* _invoke_method_type_table; 125 126 OopHandle SystemDictionary::_java_system_loader; 127 OopHandle SystemDictionary::_java_platform_loader; 128 129 // ---------------------------------------------------------------------------- 130 // Java-level SystemLoader and PlatformLoader 131 oop SystemDictionary::java_system_loader() { 132 return _java_system_loader.resolve(); 133 } 134 135 oop SystemDictionary::java_platform_loader() { 136 return _java_platform_loader.resolve(); 137 } 138 139 void SystemDictionary::compute_java_loaders(TRAPS) { 140 if (_java_platform_loader.is_empty()) { 141 oop platform_loader = get_platform_class_loader_impl(CHECK); 142 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader); 143 } else { 144 // It must have been restored from the archived module graph 145 assert(CDSConfig::is_using_archive(), "must be"); 146 assert(CDSConfig::is_using_full_module_graph(), "must be"); 147 DEBUG_ONLY( 148 oop platform_loader = get_platform_class_loader_impl(CHECK); 149 assert(_java_platform_loader.resolve() == platform_loader, "must be"); 150 ) 151 } 152 153 if (_java_system_loader.is_empty()) { 154 oop system_loader = get_system_class_loader_impl(CHECK); 155 _java_system_loader = OopHandle(Universe::vm_global(), system_loader); 156 } else { 157 // It must have been restored from the archived module graph 158 assert(CDSConfig::is_using_archive(), "must be"); 159 assert(CDSConfig::is_using_full_module_graph(), "must be"); 160 DEBUG_ONLY( 161 oop system_loader = get_system_class_loader_impl(CHECK); 162 assert(_java_system_loader.resolve() == system_loader, "must be"); 163 ) 164 } 165 } 166 167 oop SystemDictionary::get_system_class_loader_impl(TRAPS) { 168 JavaValue result(T_OBJECT); 169 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass(); 170 JavaCalls::call_static(&result, 171 class_loader_klass, 172 vmSymbols::getSystemClassLoader_name(), 173 vmSymbols::void_classloader_signature(), 174 CHECK_NULL); 175 return result.get_oop(); 176 } 177 178 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) { 179 JavaValue result(T_OBJECT); 180 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass(); 181 JavaCalls::call_static(&result, 182 class_loader_klass, 183 vmSymbols::getPlatformClassLoader_name(), 184 vmSymbols::void_classloader_signature(), 185 CHECK_NULL); 186 return result.get_oop(); 187 } 188 189 // Helper function 190 inline ClassLoaderData* class_loader_data(Handle class_loader) { 191 return ClassLoaderData::class_loader_data(class_loader()); 192 } 193 194 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) { 195 if (create_mirror_cld) { 196 // Add a new class loader data to the graph. 197 return ClassLoaderDataGraph::add(class_loader, true); 198 } else { 199 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() : 200 ClassLoaderDataGraph::find_or_create(class_loader); 201 } 202 } 203 204 void SystemDictionary::set_system_loader(ClassLoaderData *cld) { 205 assert(_java_system_loader.is_empty(), "already set!"); 206 _java_system_loader = cld->class_loader_handle(); 207 208 } 209 210 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) { 211 assert(_java_platform_loader.is_empty(), "already set!"); 212 _java_platform_loader = cld->class_loader_handle(); 213 } 214 215 // ---------------------------------------------------------------------------- 216 // Parallel class loading check 217 218 static bool is_parallelCapable(Handle class_loader) { 219 if (class_loader.is_null()) return true; 220 return java_lang_ClassLoader::parallelCapable(class_loader()); 221 } 222 // ---------------------------------------------------------------------------- 223 // ParallelDefineClass flag does not apply to bootclass loader 224 static bool is_parallelDefine(Handle class_loader) { 225 if (class_loader.is_null()) return false; 226 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) { 227 return true; 228 } 229 return false; 230 } 231 232 // Returns true if the passed class loader is the builtin application class loader 233 // or a custom system class loader. A customer system class loader can be 234 // specified via -Djava.system.class.loader. 235 bool SystemDictionary::is_system_class_loader(oop class_loader) { 236 if (class_loader == nullptr) { 237 return false; 238 } 239 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() || 240 class_loader == _java_system_loader.peek()); 241 } 242 243 // Returns true if the passed class loader is the platform class loader. 244 bool SystemDictionary::is_platform_class_loader(oop class_loader) { 245 if (class_loader == nullptr) { 246 return false; 247 } 248 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass()); 249 } 250 251 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) { 252 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading. 253 if (is_parallelCapable(class_loader)) { 254 return Handle(); 255 } else { 256 return class_loader; 257 } 258 } 259 260 // ---------------------------------------------------------------------------- 261 // Resolving of classes 262 263 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) { 264 if (name == nullptr) { 265 THROW_MSG_NULL(exception, "No class name given"); 266 } 267 size_t name_len = strlen(name); 268 if (name_len > static_cast<size_t>(Symbol::max_length())) { 269 // It's impossible to create this class; the name cannot fit 270 // into the constant pool. If necessary report an abridged name 271 // in the exception message. 272 if (name_len > static_cast<size_t>(MaxStringPrintSize)) { 273 Exceptions::fthrow(THREAD_AND_LOCATION, exception, 274 "Class name exceeds maximum length of %d: %.*s ... (%zu characters omitted) ... %.*s", 275 Symbol::max_length(), 276 MaxStringPrintSize / 2, 277 name, 278 name_len - 2 * (MaxStringPrintSize / 2), // allows for odd value 279 MaxStringPrintSize / 2, 280 name + name_len - MaxStringPrintSize / 2); 281 } 282 else { 283 Exceptions::fthrow(THREAD_AND_LOCATION, exception, 284 "Class name exceeds maximum length of %d: %s", 285 Symbol::max_length(), 286 name); 287 } 288 return nullptr; 289 } 290 // Callers should ensure that the name is never an illegal UTF8 string. 291 assert(UTF8::is_legal_utf8((const unsigned char*)name, name_len, false), 292 "Class name is not a valid utf8 string."); 293 294 // Make a new symbol for the class name. 295 return SymbolTable::new_symbol(name); 296 } 297 298 #ifdef ASSERT 299 // Used to verify that class loading succeeded in adding k to the dictionary. 300 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) { 301 MutexLocker mu(SystemDictionary_lock); 302 ClassLoaderData* loader_data = k->class_loader_data(); 303 Dictionary* dictionary = loader_data->dictionary(); 304 assert(class_name == k->name(), "Must be the same"); 305 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name); 306 assert(kk == k, "should be present in dictionary"); 307 } 308 #endif 309 310 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) { 311 if (HAS_PENDING_EXCEPTION) { 312 // If we have a pending exception we forward it to the caller, unless throw_error is true, 313 // in which case we have to check whether the pending exception is a ClassNotFoundException, 314 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException. 315 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) { 316 ResourceMark rm(THREAD); 317 Handle e(THREAD, PENDING_EXCEPTION); 318 CLEAR_PENDING_EXCEPTION; 319 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e); 320 } else { 321 return; // the caller will throw the incoming exception 322 } 323 } 324 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate 325 // error or exception depending on the value of throw_error. 326 ResourceMark rm(THREAD); 327 if (throw_error) { 328 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string()); 329 } else { 330 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string()); 331 } 332 } 333 334 // Forwards to resolve_or_null 335 336 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, 337 bool throw_error, TRAPS) { 338 Klass* klass = resolve_or_null(class_name, class_loader, THREAD); 339 // Check for pending exception or null klass, and throw exception 340 if (HAS_PENDING_EXCEPTION || klass == nullptr) { 341 handle_resolution_exception(class_name, throw_error, CHECK_NULL); 342 } 343 return klass; 344 } 345 346 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null 347 348 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, TRAPS) { 349 if (Signature::is_array(class_name)) { 350 return resolve_array_class_or_null(class_name, class_loader, THREAD); 351 } else { 352 assert(class_name != nullptr && !Signature::is_array(class_name), "must be"); 353 if (Signature::has_envelope(class_name)) { 354 ResourceMark rm(THREAD); 355 // Ignore wrapping L and ; (and Q and ; for value types). 356 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1, 357 class_name->utf8_length() - 2); 358 return resolve_instance_class_or_null(name, class_loader, THREAD); 359 } else { 360 return resolve_instance_class_or_null(class_name, class_loader, THREAD); 361 } 362 } 363 } 364 365 // Forwards to resolve_instance_class_or_null 366 367 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name, 368 Handle class_loader, 369 TRAPS) { 370 assert(Signature::is_array(class_name), "must be array"); 371 ResourceMark rm(THREAD); 372 SignatureStream ss(class_name, false); 373 int ndims = ss.skip_array_prefix(); // skip all '['s 374 Klass* k = nullptr; 375 BasicType t = ss.type(); 376 if (ss.has_envelope()) { 377 Symbol* obj_class = ss.as_symbol(); 378 k = SystemDictionary::resolve_instance_class_or_null(obj_class, 379 class_loader, 380 CHECK_NULL); 381 if (k != nullptr) { 382 k = k->array_klass(ndims, CHECK_NULL); 383 } 384 } else { 385 k = Universe::typeArrayKlass(t); 386 k = k->array_klass(ndims, CHECK_NULL); 387 } 388 return k; 389 } 390 391 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) { 392 LogTarget(Debug, class, load, placeholders) lt; 393 if (lt.is_enabled()) { 394 ResourceMark rm; 395 LogStream ls(lt); 396 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string()); 397 probe->print_on(&ls); 398 ls.cr(); 399 } 400 } 401 402 // Must be called for any superclass or superinterface resolution 403 // during class definition to allow class circularity checking 404 // superinterface callers: 405 // parse_interfaces - from defineClass 406 // superclass callers: 407 // ClassFileParser - from defineClass 408 // load_shared_class - while loading a class from shared archive 409 // resolve_instance_class_or_null: 410 // via: handle_parallel_super_load 411 // when resolving a class that has an existing placeholder with 412 // a saved superclass [i.e. a defineClass is currently in progress] 413 // If another thread is trying to resolve the class, it must do 414 // superclass checks on its own thread to catch class circularity and 415 // to avoid deadlock. 416 // 417 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling 418 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE 419 // placeholder for the same thread, class, classloader is found. 420 // This can be seen with logging option: -Xlog:class+load+placeholders=debug. 421 // 422 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name, 423 Symbol* next_name, 424 Handle class_loader, 425 bool is_superclass, 426 TRAPS) { 427 428 assert(next_name != nullptr, "null superclass for resolving"); 429 assert(!Signature::is_array(next_name), "invalid superclass name"); 430 431 ClassLoaderData* loader_data = class_loader_data(class_loader); 432 433 if (is_superclass) { 434 InstanceKlass* klassk = loader_data->dictionary()->find_class(THREAD, class_name); 435 if (klassk != nullptr) { 436 // We can come here for two reasons: 437 // (a) RedefineClasses -- the class is already loaded 438 // (b) Rarely, the class might have been loaded by a parallel thread 439 // We can do a quick check against the already assigned superclass's name and loader. 440 InstanceKlass* superk = klassk->java_super(); 441 if (superk != nullptr && 442 superk->name() == next_name && 443 superk->class_loader() == class_loader()) { 444 return superk; 445 } 446 } 447 } 448 449 // can't throw error holding a lock 450 bool throw_circularity_error = false; 451 { 452 MutexLocker mu(THREAD, SystemDictionary_lock); 453 454 // Must check ClassCircularity before resolving next_name (superclass or interface). 455 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data); 456 if (probe != nullptr && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) { 457 log_circularity_error(class_name, probe); 458 throw_circularity_error = true; 459 } 460 461 // Make sure there's a placeholder for the class_name before resolving. 462 // This is used as a claim that this thread is currently loading superclass/classloader 463 // and for ClassCircularity checks. 464 if (!throw_circularity_error) { 465 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder. 466 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name, 467 loader_data, 468 PlaceholderTable::DETECT_CIRCULARITY, 469 next_name, THREAD); 470 } 471 } 472 473 if (throw_circularity_error) { 474 ResourceMark rm(THREAD); 475 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string()); 476 } 477 478 // Resolve the superclass or superinterface, check results on return 479 InstanceKlass* superk = 480 SystemDictionary::resolve_instance_class_or_null(next_name, 481 class_loader, 482 THREAD); 483 484 // Clean up placeholder entry. 485 { 486 MutexLocker mu(THREAD, SystemDictionary_lock); 487 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD); 488 SystemDictionary_lock->notify_all(); 489 } 490 491 // Check for pending exception or null superk, and throw exception 492 if (HAS_PENDING_EXCEPTION || superk == nullptr) { 493 handle_resolution_exception(next_name, true, CHECK_NULL); 494 } 495 496 return superk; 497 } 498 499 // If the class in is in the placeholder table, class loading is in progress. 500 // For cases where the application changes threads to load classes, it 501 // is critical to ClassCircularity detection that we try loading 502 // the superclass on the new thread internally, so we do parallel 503 // superclass loading here. This avoids deadlock for ClassCircularity 504 // detection for parallelCapable class loaders that lock on a per-class lock. 505 static void handle_parallel_super_load(Symbol* name, 506 Symbol* superclassname, 507 Handle class_loader, 508 TRAPS) { 509 510 // The result superk is not used; resolve_with_circularity_detection is called for circularity check only. 511 // This passes false to is_superclass to skip doing the unlikely optimization. 512 Klass* superk = SystemDictionary::resolve_with_circularity_detection(name, 513 superclassname, 514 class_loader, 515 false, 516 CHECK); 517 } 518 519 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to 520 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading. 521 static bool needs_load_placeholder(Handle class_loader) { 522 return class_loader.is_null() || !is_parallelCapable(class_loader); 523 } 524 525 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader. 526 static InstanceKlass* handle_parallel_loading(JavaThread* current, 527 Symbol* name, 528 ClassLoaderData* loader_data, 529 bool must_wait_for_class_loading, 530 bool* throw_circularity_error) { 531 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data); 532 if (oldprobe != nullptr) { 533 // -Xcomp calls load_signature_classes which might result in loading 534 // a class that's already in the process of loading, so we detect CCE here also. 535 // Only need check_seen_thread once, not on each loop 536 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) { 537 log_circularity_error(name, oldprobe); 538 *throw_circularity_error = true; 539 return nullptr; 540 } else if (must_wait_for_class_loading) { 541 // Wait until the first thread has finished loading this class. Also wait until all the 542 // threads trying to load its superclass have removed their placeholders. 543 while (oldprobe != nullptr && 544 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) { 545 546 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading 547 // for the bootclass loader. 548 SystemDictionary_lock->wait(); 549 550 // Check if classloading completed while we were waiting 551 InstanceKlass* check = loader_data->dictionary()->find_class(current, name); 552 if (check != nullptr) { 553 // Klass is already loaded, so just return it 554 return check; 555 } 556 // check if other thread failed to load and cleaned up 557 oldprobe = PlaceholderTable::get_entry(name, loader_data); 558 } 559 } 560 } 561 return nullptr; 562 } 563 564 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) { 565 assert(event != nullptr, "invariant"); 566 assert(k != nullptr, "invariant"); 567 event->set_loadedClass(k); 568 event->set_definingClassLoader(k->class_loader_data()); 569 event->set_initiatingClassLoader(init_cld); 570 event->commit(); 571 } 572 573 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution. 574 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and 575 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class, 576 // which will load the class via the bootstrap loader or call ClassLoader.loadClass(). 577 // This can return null, an exception or an InstanceKlass. 578 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name, 579 Handle class_loader, 580 TRAPS) { 581 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;" 582 DEBUG_ONLY(ResourceMark rm(THREAD)); 583 assert(name != nullptr && !Signature::is_array(name) && 584 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string()); 585 586 EventClassLoad class_load_start_event; 587 588 HandleMark hm(THREAD); 589 590 ClassLoaderData* loader_data = register_loader(class_loader); 591 Dictionary* dictionary = loader_data->dictionary(); 592 593 // Do lookup to see if class already exists. 594 InstanceKlass* probe = dictionary->find_class(THREAD, name); 595 if (probe != nullptr) return probe; 596 597 // Non-bootstrap class loaders will call out to class loader and 598 // define via jvm/jni_DefineClass which will acquire the 599 // class loader object lock to protect against multiple threads 600 // defining the class in parallel by accident. 601 // This lock must be acquired here so the waiter will find 602 // any successful result in the SystemDictionary and not attempt 603 // the define. 604 // ParallelCapable class loaders and the bootstrap classloader 605 // do not acquire lock here. 606 Handle lockObject = get_loader_lock_or_null(class_loader); 607 ObjectLocker ol(lockObject, THREAD); 608 609 bool circularity_detection_in_progress = false; 610 InstanceKlass* loaded_class = nullptr; 611 SymbolHandle superclassname; // Keep alive while loading in parallel thread. 612 613 guarantee(THREAD->can_call_java(), 614 "can not load classes with compiler thread: class=%s, classloader=%s", 615 name->as_C_string(), 616 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string()); 617 618 // Check again (after locking) if the class already exists in SystemDictionary 619 { 620 MutexLocker mu(THREAD, SystemDictionary_lock); 621 InstanceKlass* check = dictionary->find_class(THREAD, name); 622 if (check != nullptr) { 623 // InstanceKlass is already loaded, but we still need to check protection domain below. 624 loaded_class = check; 625 } else { 626 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data); 627 if (placeholder != nullptr && placeholder->circularity_detection_in_progress()) { 628 circularity_detection_in_progress = true; 629 superclassname = placeholder->next_klass_name(); 630 assert(superclassname != nullptr, "superclass has to have a name"); 631 } 632 } 633 } 634 635 // If the class is in the placeholder table with super_class set, 636 // handle superclass loading in progress. 637 if (circularity_detection_in_progress) { 638 handle_parallel_super_load(name, superclassname, 639 class_loader, 640 CHECK_NULL); 641 } 642 643 bool throw_circularity_error = false; 644 if (loaded_class == nullptr) { 645 bool load_placeholder_added = false; 646 647 // Add placeholder entry to record loading instance class 648 // case 1. Bootstrap classloader 649 // This classloader supports parallelism at the classloader level 650 // but only allows a single thread to load a class/classloader pair. 651 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion. 652 // case 2. parallelCapable user level classloaders 653 // These class loaders lock a per-class object lock when ClassLoader.loadClass() 654 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion. 655 // case 3. traditional classloaders that rely on the classloader object lock 656 // There should be no need for need for LOAD_INSTANCE for mutual exclusion, 657 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp. 658 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not. 659 { 660 MutexLocker mu(THREAD, SystemDictionary_lock); 661 if (needs_load_placeholder(class_loader)) { 662 loaded_class = handle_parallel_loading(THREAD, 663 name, 664 loader_data, 665 class_loader.is_null(), 666 &throw_circularity_error); 667 } 668 669 // Recheck if the class has been loaded for all class loader cases and 670 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock. 671 if (!throw_circularity_error && loaded_class == nullptr) { 672 InstanceKlass* check = dictionary->find_class(THREAD, name); 673 if (check != nullptr) { 674 loaded_class = check; 675 } else if (needs_load_placeholder(class_loader)) { 676 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread. 677 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data, 678 PlaceholderTable::LOAD_INSTANCE, 679 nullptr, 680 THREAD); 681 load_placeholder_added = true; 682 } 683 } 684 } 685 686 // Must throw error outside of owning lock 687 if (throw_circularity_error) { 688 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup"); 689 ResourceMark rm(THREAD); 690 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string()); 691 } 692 693 // Be careful when modifying this code: once you have run 694 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE), 695 // you need to find_and_remove it before returning. 696 // So be careful to not exit with a CHECK_ macro between these calls. 697 698 if (loaded_class == nullptr) { 699 // Do actual loading 700 loaded_class = load_instance_class(name, class_loader, THREAD); 701 } 702 703 if (load_placeholder_added) { 704 // clean up placeholder entries for LOAD_INSTANCE success or error 705 // This brackets the SystemDictionary updates for both defining 706 // and initiating loaders 707 MutexLocker mu(THREAD, SystemDictionary_lock); 708 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD); 709 SystemDictionary_lock->notify_all(); 710 } 711 } 712 713 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) { 714 return nullptr; 715 } 716 717 if (class_load_start_event.should_commit()) { 718 post_class_load_event(&class_load_start_event, loaded_class, loader_data); 719 } 720 721 // Make sure we have the right class in the dictionary 722 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class)); 723 724 return loaded_class; 725 } 726 727 728 // This routine does not lock the system dictionary. 729 // 730 // Since readers don't hold a lock, we must make sure that system 731 // dictionary entries are added to in a safe way (all links must 732 // be updated in an MT-safe manner). All entries are removed during class 733 // unloading, when this class loader is no longer referenced. 734 // 735 // Callers should be aware that an entry could be added just after 736 // Dictionary is read here, so the caller will not see 737 // the new entry. 738 739 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current, 740 Symbol* class_name, 741 Handle class_loader) { 742 743 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader()); 744 if (loader_data == nullptr) { 745 // If the ClassLoaderData has not been setup, 746 // then the class loader has no entries in the dictionary. 747 return nullptr; 748 } 749 750 Dictionary* dictionary = loader_data->dictionary(); 751 return dictionary->find_class(current, class_name); 752 } 753 754 // Look for a loaded instance or array klass by name. Do not do any loading. 755 // return null in case of error. 756 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current, 757 Symbol* class_name, 758 Handle class_loader) { 759 Klass* k = nullptr; 760 assert(class_name != nullptr, "class name must be non nullptr"); 761 762 if (Signature::is_array(class_name)) { 763 // The name refers to an array. Parse the name. 764 // dimension and object_key in FieldArrayInfo are assigned as a 765 // side-effect of this call 766 SignatureStream ss(class_name, false); 767 int ndims = ss.skip_array_prefix(); // skip all '['s 768 BasicType t = ss.type(); 769 if (t != T_OBJECT) { 770 k = Universe::typeArrayKlass(t); 771 } else { 772 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader); 773 } 774 if (k != nullptr) { 775 k = k->array_klass_or_null(ndims); 776 } 777 } else { 778 k = find_instance_klass(current, class_name, class_loader); 779 } 780 return k; 781 } 782 783 // Note: this method is much like resolve_class_from_stream, but 784 // does not publish the classes in the SystemDictionary. 785 // Handles Lookup.defineClass hidden. 786 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream( 787 ClassFileStream* st, 788 Symbol* class_name, 789 Handle class_loader, 790 const ClassLoadInfo& cl_info, 791 TRAPS) { 792 793 EventClassLoad class_load_start_event; 794 ClassLoaderData* loader_data; 795 796 // - for hidden classes that are not strong: create a new CLD that has a class holder and 797 // whose loader is the Lookup class's loader. 798 // - for hidden class: add the class to the Lookup class's loader's CLD. 799 assert (cl_info.is_hidden(), "only used for hidden classes"); 800 bool create_mirror_cld = !cl_info.is_strong_hidden(); 801 loader_data = register_loader(class_loader, create_mirror_cld); 802 803 assert(st != nullptr, "invariant"); 804 805 // Parse stream and create a klass. 806 InstanceKlass* k = KlassFactory::create_from_stream(st, 807 class_name, 808 loader_data, 809 cl_info, 810 CHECK_NULL); 811 assert(k != nullptr, "no klass created"); 812 813 // Hidden classes that are not strong must update ClassLoaderData holder 814 // so that they can be unloaded when the mirror is no longer referenced. 815 if (!cl_info.is_strong_hidden()) { 816 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror())); 817 } 818 819 // Add to class hierarchy, and do possible deoptimizations. 820 k->add_to_hierarchy(THREAD); 821 // But, do not add to dictionary. 822 823 k->link_class(CHECK_NULL); 824 825 // notify jvmti 826 if (JvmtiExport::should_post_class_load()) { 827 JvmtiExport::post_class_load(THREAD, k); 828 } 829 if (class_load_start_event.should_commit()) { 830 post_class_load_event(&class_load_start_event, k, loader_data); 831 } 832 833 return k; 834 } 835 836 // Add a klass to the system from a stream (called by jni_DefineClass and 837 // JVM_DefineClass). 838 // Note: class_name can be null. In that case we do not know the name of 839 // the class until we have parsed the stream. 840 // This function either returns an InstanceKlass or throws an exception. It does 841 // not return null without a pending exception. 842 InstanceKlass* SystemDictionary::resolve_class_from_stream( 843 ClassFileStream* st, 844 Symbol* class_name, 845 Handle class_loader, 846 const ClassLoadInfo& cl_info, 847 TRAPS) { 848 849 HandleMark hm(THREAD); 850 851 ClassLoaderData* loader_data = register_loader(class_loader); 852 853 // Classloaders that support parallelism, e.g. bootstrap classloader, 854 // do not acquire lock here 855 Handle lockObject = get_loader_lock_or_null(class_loader); 856 ObjectLocker ol(lockObject, THREAD); 857 858 // Parse the stream and create a klass. 859 // Note that we do this even though this klass might 860 // already be present in the SystemDictionary, otherwise we would not 861 // throw potential ClassFormatErrors. 862 InstanceKlass* k = nullptr; 863 864 #if INCLUDE_CDS 865 if (!CDSConfig::is_dumping_static_archive()) { 866 k = SystemDictionaryShared::lookup_from_stream(class_name, 867 class_loader, 868 cl_info.protection_domain(), 869 st, 870 CHECK_NULL); 871 } 872 #endif 873 874 if (k == nullptr) { 875 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL); 876 } 877 878 assert(k != nullptr, "no klass created"); 879 Symbol* h_name = k->name(); 880 assert(class_name == nullptr || class_name == h_name, "name mismatch"); 881 882 // Add class just loaded 883 // If a class loader supports parallel classloading, handle parallel define requests. 884 // find_or_define_instance_class may return a different InstanceKlass, 885 // in which case the old k would be deallocated 886 if (is_parallelCapable(class_loader)) { 887 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL); 888 } else { 889 define_instance_class(k, class_loader, THREAD); 890 891 // If defining the class throws an exception register 'k' for cleanup. 892 if (HAS_PENDING_EXCEPTION) { 893 assert(k != nullptr, "Must have an instance klass here!"); 894 loader_data->add_to_deallocate_list(k); 895 return nullptr; 896 } 897 } 898 899 // Make sure we have an entry in the SystemDictionary on success 900 DEBUG_ONLY(verify_dictionary_entry(h_name, k)); 901 902 return k; 903 } 904 905 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st, 906 Symbol* class_name, 907 Handle class_loader, 908 const ClassLoadInfo& cl_info, 909 TRAPS) { 910 if (cl_info.is_hidden()) { 911 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL); 912 } else { 913 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL); 914 } 915 } 916 917 918 #if INCLUDE_CDS 919 // Check if a shared class can be loaded by the specific classloader. 920 bool SystemDictionary::is_shared_class_visible(Symbol* class_name, 921 InstanceKlass* ik, 922 PackageEntry* pkg_entry, 923 Handle class_loader) { 924 assert(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS"); 925 926 // (1) Check if we are loading into the same loader as in dump time. 927 928 if (ik->is_shared_boot_class()) { 929 if (class_loader() != nullptr) { 930 return false; 931 } 932 } else if (ik->is_shared_platform_class()) { 933 if (class_loader() != java_platform_loader()) { 934 return false; 935 } 936 } else if (ik->is_shared_app_class()) { 937 if (class_loader() != java_system_loader()) { 938 return false; 939 } 940 } else { 941 // ik was loaded by a custom loader during dump time 942 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) { 943 return false; 944 } else { 945 return true; 946 } 947 } 948 949 // (2) Check if we are loading into the same module from the same location as in dump time. 950 951 if (CDSConfig::is_using_optimized_module_handling()) { 952 // Class visibility has not changed between dump time and run time, so a class 953 // that was visible (and thus archived) during dump time is always visible during runtime. 954 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader), 955 "visibility cannot change between dump time and runtime"); 956 return true; 957 } 958 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader); 959 } 960 961 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name, 962 InstanceKlass* ik, 963 PackageEntry* pkg_entry, 964 Handle class_loader) { 965 int scp_index = ik->shared_classpath_index(); 966 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only"); 967 assert(scp_index >= 0, "must be"); 968 const AOTClassLocation* cl = AOTClassLocationConfig::runtime()->class_location_at(scp_index); 969 if (!Universe::is_module_initialized()) { 970 assert(cl != nullptr, "must be"); 971 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass() 972 // has restricted the classes can be loaded at this step to be only: 973 // [1] cs->is_modules_image(): classes in java.base, or, 974 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module 975 assert(cl->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik), 976 "only these classes can be loaded before the module system is initialized"); 977 assert(class_loader.is_null(), "sanity"); 978 return true; 979 } 980 981 if (pkg_entry == nullptr) { 982 // We might have looked up pkg_entry before the module system was initialized. 983 // Need to reload it now. 984 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name); 985 if (pkg_name != nullptr) { 986 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name); 987 } 988 } 989 990 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module(); 991 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named()); 992 bool was_archived_from_named_module = !cl->has_unnamed_module(); 993 bool visible; 994 995 if (was_archived_from_named_module) { 996 if (should_be_in_named_module) { 997 // Is the module loaded from the same location as during dump time? 998 visible = mod_entry->shared_path_index() == scp_index; 999 if (visible) { 1000 assert(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS"); 1001 } 1002 } else { 1003 // During dump time, this class was in a named module, but at run time, this class should be 1004 // in an unnamed module. 1005 visible = false; 1006 } 1007 } else { 1008 if (should_be_in_named_module) { 1009 // During dump time, this class was in an unnamed, but at run time, this class should be 1010 // in a named module. 1011 visible = false; 1012 } else { 1013 visible = true; 1014 } 1015 } 1016 1017 return visible; 1018 } 1019 1020 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type, 1021 Handle class_loader, bool is_superclass, TRAPS) { 1022 assert(super_type->is_shared(), "must be"); 1023 1024 // Quick check if the super type has been already loaded. 1025 // + Don't do it for unregistered classes -- they can be unloaded so 1026 // super_type->class_loader_data() could be stale. 1027 // + Don't check if loader data is null, ie. the super_type isn't fully loaded. 1028 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) { 1029 // Check if the superclass is loaded by the current class_loader 1030 Symbol* name = super_type->name(); 1031 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader); 1032 if (check == super_type) { 1033 return true; 1034 } 1035 } 1036 1037 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(), 1038 class_loader, is_superclass, CHECK_false); 1039 if (found == super_type) { 1040 return true; 1041 } else { 1042 // The dynamically resolved super type is not the same as the one we used during dump time, 1043 // so we cannot use the class. 1044 return false; 1045 } 1046 } 1047 1048 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader, TRAPS) { 1049 // Check the superclass and interfaces. They must be the same 1050 // as in dump time, because the layout of <ik> depends on 1051 // the specific layout of ik->super() and ik->local_interfaces(). 1052 // 1053 // If unexpected superclass or interfaces are found, we cannot 1054 // load <ik> from the shared archive. 1055 1056 if (ik->super() != nullptr) { 1057 bool check_super = check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()), 1058 class_loader, true, 1059 CHECK_false); 1060 if (!check_super) { 1061 return false; 1062 } 1063 } 1064 1065 Array<InstanceKlass*>* interfaces = ik->local_interfaces(); 1066 int num_interfaces = interfaces->length(); 1067 for (int index = 0; index < num_interfaces; index++) { 1068 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, false, 1069 CHECK_false); 1070 if (!check_interface) { 1071 return false; 1072 } 1073 } 1074 1075 return true; 1076 } 1077 1078 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik, 1079 Handle class_loader, 1080 Handle protection_domain, 1081 const ClassFileStream *cfs, 1082 PackageEntry* pkg_entry, 1083 TRAPS) { 1084 assert(ik != nullptr, "sanity"); 1085 assert(ik->is_shared(), "sanity"); 1086 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once"); 1087 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once"); 1088 Symbol* class_name = ik->name(); 1089 1090 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) { 1091 ik->set_shared_loading_failed(); 1092 return nullptr; 1093 } 1094 1095 bool check = check_shared_class_super_types(ik, class_loader, CHECK_NULL); 1096 if (!check) { 1097 ik->set_shared_loading_failed(); 1098 return nullptr; 1099 } 1100 1101 if (ik->has_inline_type_fields()) { 1102 for (AllFieldStream fs(ik); !fs.done(); fs.next()) { 1103 if (fs.access_flags().is_static()) continue; 1104 Symbol* sig = fs.signature(); 1105 if (fs.is_null_free_inline_type()) { 1106 // Pre-load inline class 1107 TempNewSymbol name = Signature::strip_envelope(sig); 1108 log_info(class, preload)("Preloading class %s during loading of shared class %s. Cause: field type in LoadableDescriptors attribute", name->as_C_string(), ik->name()->as_C_string()); 1109 Klass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name, 1110 class_loader, false, CHECK_NULL); 1111 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index()); 1112 if (real_k != k) { 1113 // oops, the app has substituted a different version of k! 1114 log_warning(class, preload)("Preloading of class %s during loading of shared class %s (cause: field type in LoadableDescriptors attribute) failed : %s", 1115 name->as_C_string(), ik->name()->as_C_string(), PENDING_EXCEPTION->klass()->name()->as_C_string()); 1116 return nullptr; 1117 } else if (real_k != nullptr) { 1118 log_info(class, preload)("Preloading of class %s during loading of shared class %s (cause: field type in LoadableDescriptors attribute) succeeded", 1119 name->as_C_string(), ik->name()->as_C_string()); 1120 } 1121 } else if (Signature::has_envelope(sig)) { 1122 TempNewSymbol name = Signature::strip_envelope(sig); 1123 if (name != ik->name() && ik->is_class_in_loadable_descriptors_attribute(sig)) { 1124 log_info(class, preload)("Preloading class %s during loading of shared class %s. Cause: field type in LoadableDescriptors attribute", 1125 name->as_C_string(), ik->name()->as_C_string()); 1126 Klass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name, 1127 class_loader, false, THREAD); 1128 if (HAS_PENDING_EXCEPTION) { 1129 CLEAR_PENDING_EXCEPTION; 1130 } 1131 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index()); 1132 if (real_k != k) { 1133 // oops, the app has substituted a different version of k! 1134 log_warning(class, preload)("Preloading of class %s during loading of shared class %s (cause: field type in LoadableDescriptors attribute) failed : %s", 1135 name->as_C_string(), ik->name()->as_C_string(), PENDING_EXCEPTION->klass()->name()->as_C_string()); 1136 return nullptr; 1137 } else if (real_k != nullptr) { 1138 log_info(class, preload)("Preloading of class %s during loading of shared class %s (cause: field type in LoadableDescriptors attribute) succeeded", 1139 name->as_C_string(), ik->name()->as_C_string()); 1140 } 1141 } 1142 } 1143 } 1144 } 1145 1146 InstanceKlass* new_ik = nullptr; 1147 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream). 1148 // It will be skipped for shared VM hidden lambda proxy classes. 1149 if (!ik->is_hidden()) { 1150 new_ik = KlassFactory::check_shared_class_file_load_hook( 1151 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL); 1152 } 1153 if (new_ik != nullptr) { 1154 // The class is changed by CFLH. Return the new class. The shared class is 1155 // not used. 1156 return new_ik; 1157 } 1158 1159 // Adjust methods to recover missing data. They need addresses for 1160 // interpreter entry points and their default native method address 1161 // must be reset. 1162 1163 // Shared classes are all currently loaded by either the bootstrap or 1164 // internal parallel class loaders, so this will never cause a deadlock 1165 // on a custom class loader lock. 1166 // Since this class is already locked with parallel capable class 1167 // loaders, including the bootstrap loader via the placeholder table, 1168 // this lock is currently a nop. 1169 1170 ClassLoaderData* loader_data = class_loader_data(class_loader); 1171 { 1172 HandleMark hm(THREAD); 1173 Handle lockObject = get_loader_lock_or_null(class_loader); 1174 ObjectLocker ol(lockObject, THREAD); 1175 // prohibited package check assumes all classes loaded from archive call 1176 // restore_unshareable_info which calls ik->set_package() 1177 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL); 1178 } 1179 1180 load_shared_class_misc(ik, loader_data); 1181 1182 return ik; 1183 } 1184 1185 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) { 1186 ik->print_class_load_logging(loader_data, nullptr, nullptr); 1187 1188 // For boot loader, ensure that GetSystemPackage knows that a class in this 1189 // package was loaded. 1190 if (loader_data->is_the_null_class_loader_data()) { 1191 s2 path_index = ik->shared_classpath_index(); 1192 ik->set_classpath_index(path_index); 1193 } 1194 1195 // notify a class loaded from shared object 1196 ClassLoadingService::notify_class_loaded(ik, true /* shared class */); 1197 1198 if (CDSConfig::is_dumping_final_static_archive()) { 1199 SystemDictionaryShared::init_dumptime_info_from_preimage(ik); 1200 } 1201 } 1202 1203 #endif // INCLUDE_CDS 1204 1205 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) { 1206 1207 if (class_loader.is_null()) { 1208 ResourceMark rm(THREAD); 1209 PackageEntry* pkg_entry = nullptr; 1210 bool search_only_bootloader_append = false; 1211 1212 // Find the package in the boot loader's package entry table. 1213 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name); 1214 if (pkg_name != nullptr) { 1215 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name); 1216 } 1217 1218 // Prior to attempting to load the class, enforce the boot loader's 1219 // visibility boundaries. 1220 if (!Universe::is_module_initialized()) { 1221 // During bootstrapping, prior to module initialization, any 1222 // class attempting to be loaded must be checked against the 1223 // java.base packages in the boot loader's PackageEntryTable. 1224 // No class outside of java.base is allowed to be loaded during 1225 // this bootstrapping window. 1226 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) { 1227 // Class is either in the unnamed package or in 1228 // a named package within the unnamed module. Either 1229 // case is outside of java.base, do not attempt to 1230 // load the class post java.base definition. If 1231 // java.base has not been defined, let the class load 1232 // and its package will be checked later by 1233 // ModuleEntryTable::verify_javabase_packages. 1234 if (ModuleEntryTable::javabase_defined()) { 1235 return nullptr; 1236 } 1237 } else { 1238 // Check that the class' package is defined within java.base. 1239 ModuleEntry* mod_entry = pkg_entry->module(); 1240 Symbol* mod_entry_name = mod_entry->name(); 1241 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) { 1242 return nullptr; 1243 } 1244 } 1245 } else { 1246 // After the module system has been initialized, check if the class' 1247 // package is in a module defined to the boot loader. 1248 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) { 1249 // Class is either in the unnamed package, in a named package 1250 // within a module not defined to the boot loader or in a 1251 // a named package within the unnamed module. In all cases, 1252 // limit visibility to search for the class only in the boot 1253 // loader's append path. 1254 if (!ClassLoader::has_bootclasspath_append()) { 1255 // If there is no bootclasspath append entry, no need to continue 1256 // searching. 1257 return nullptr; 1258 } 1259 search_only_bootloader_append = true; 1260 } 1261 } 1262 1263 // Prior to bootstrapping's module initialization, never load a class outside 1264 // of the boot loader's module path 1265 assert(Universe::is_module_initialized() || 1266 !search_only_bootloader_append, 1267 "Attempt to load a class outside of boot loader's module path"); 1268 1269 // Search for classes in the CDS archive. 1270 InstanceKlass* k = nullptr; 1271 1272 #if INCLUDE_CDS 1273 if (CDSConfig::is_using_archive()) 1274 { 1275 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time()); 1276 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name); 1277 if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) { 1278 SharedClassLoadingMark slm(THREAD, ik); 1279 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL); 1280 } 1281 } 1282 #endif 1283 1284 if (k == nullptr) { 1285 // Use VM class loader 1286 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time()); 1287 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL); 1288 } 1289 1290 // find_or_define_instance_class may return a different InstanceKlass 1291 if (k != nullptr) { 1292 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);) 1293 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL); 1294 } 1295 return k; 1296 } else { 1297 // Use user specified class loader to load class. Call loadClass operation on class_loader. 1298 ResourceMark rm(THREAD); 1299 1300 JavaThread* jt = THREAD; 1301 1302 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(), 1303 ClassLoader::perf_app_classload_selftime(), 1304 ClassLoader::perf_app_classload_count(), 1305 jt->get_thread_stat()->perf_recursion_counts_addr(), 1306 jt->get_thread_stat()->perf_timers_addr(), 1307 PerfClassTraceTime::CLASS_LOAD); 1308 1309 // Translate to external class name format, i.e., convert '/' chars to '.' 1310 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL); 1311 1312 JavaValue result(T_OBJECT); 1313 1314 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass(); 1315 1316 // Call public unsynchronized loadClass(String) directly for all class loaders. 1317 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will 1318 // acquire a class-name based lock rather than the class loader object lock. 1319 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean). 1320 JavaCalls::call_virtual(&result, 1321 class_loader, 1322 spec_klass, 1323 vmSymbols::loadClass_name(), 1324 vmSymbols::string_class_signature(), 1325 string, 1326 CHECK_NULL); 1327 1328 assert(result.get_type() == T_OBJECT, "just checking"); 1329 oop obj = result.get_oop(); 1330 1331 // Primitive classes return null since forName() can not be 1332 // used to obtain any of the Class objects representing primitives or void 1333 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) { 1334 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj)); 1335 // For user defined Java class loaders, check that the name returned is 1336 // the same as that requested. This check is done for the bootstrap 1337 // loader when parsing the class file. 1338 if (class_name == k->name()) { 1339 return k; 1340 } 1341 } 1342 // Class is not found or has the wrong name, return null 1343 return nullptr; 1344 } 1345 } 1346 1347 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name, 1348 Handle class_loader, 1349 TRAPS) { 1350 1351 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL); 1352 1353 // If everything was OK (no exceptions, no null return value), and 1354 // class_loader is NOT the defining loader, do a little more bookkeeping. 1355 if (loaded_class != nullptr && 1356 loaded_class->class_loader() != class_loader()) { 1357 1358 ClassLoaderData* loader_data = class_loader_data(class_loader); 1359 check_constraints(loaded_class, loader_data, false, CHECK_NULL); 1360 1361 // Record dependency for non-parent delegation. 1362 // This recording keeps the defining class loader of the klass (loaded_class) found 1363 // from being unloaded while the initiating class loader is loaded 1364 // even if the reference to the defining class loader is dropped 1365 // before references to the initiating class loader. 1366 loader_data->record_dependency(loaded_class); 1367 1368 update_dictionary(THREAD, loaded_class, loader_data); 1369 1370 if (JvmtiExport::should_post_class_load()) { 1371 JvmtiExport::post_class_load(THREAD, loaded_class); 1372 } 1373 } 1374 return loaded_class; 1375 } 1376 1377 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) { 1378 EventClassDefine event; 1379 if (event.should_commit()) { 1380 event.set_definedClass(k); 1381 event.set_definingClassLoader(def_cld); 1382 event.commit(); 1383 } 1384 } 1385 1386 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) { 1387 1388 ClassLoaderData* loader_data = k->class_loader_data(); 1389 assert(loader_data->class_loader() == class_loader(), "they must be the same"); 1390 1391 // Bootstrap and other parallel classloaders don't acquire a lock, 1392 // they use placeholder token. 1393 // If a parallelCapable class loader calls define_instance_class instead of 1394 // find_or_define_instance_class to get here, we have a timing 1395 // hole with systemDictionary updates and check_constraints 1396 if (!is_parallelCapable(class_loader)) { 1397 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD, 1398 get_loader_lock_or_null(class_loader)), 1399 "define called without lock"); 1400 } 1401 1402 // Check class-loading constraints. Throw exception if violation is detected. 1403 // Grabs and releases SystemDictionary_lock 1404 // The check_constraints/find_class call and update_dictionary sequence 1405 // must be "atomic" for a specific class/classloader pair so we never 1406 // define two different instanceKlasses for that class/classloader pair. 1407 // Existing classloaders will call define_instance_class with the 1408 // classloader lock held 1409 // Parallel classloaders will call find_or_define_instance_class 1410 // which will require a token to perform the define class 1411 check_constraints(k, loader_data, true, CHECK); 1412 1413 // Register class just loaded with class loader (placed in ArrayList) 1414 // Note we do this before updating the dictionary, as this can 1415 // fail with an OutOfMemoryError (if it does, we will *not* put this 1416 // class in the dictionary and will not update the class hierarchy). 1417 // JVMTI FollowReferences needs to find the classes this way. 1418 if (k->class_loader() != nullptr) { 1419 methodHandle m(THREAD, Universe::loader_addClass_method()); 1420 JavaValue result(T_VOID); 1421 JavaCallArguments args(class_loader); 1422 args.push_oop(Handle(THREAD, k->java_mirror())); 1423 JavaCalls::call(&result, m, &args, CHECK); 1424 } 1425 1426 // Add to class hierarchy, and do possible deoptimizations. 1427 k->add_to_hierarchy(THREAD); 1428 1429 // Add to systemDictionary - so other classes can see it. 1430 // Grabs and releases SystemDictionary_lock 1431 update_dictionary(THREAD, k, loader_data); 1432 1433 // notify jvmti 1434 if (JvmtiExport::should_post_class_load()) { 1435 JvmtiExport::post_class_load(THREAD, k); 1436 } 1437 post_class_define_event(k, loader_data); 1438 } 1439 1440 // Support parallel classloading 1441 // All parallel class loaders, including bootstrap classloader 1442 // lock a placeholder entry for this class/class_loader pair 1443 // to allow parallel defines of different classes for this class loader 1444 // With AllowParallelDefine flag==true, in case they do not synchronize around 1445 // FindLoadedClass/DefineClass, calls, we check for parallel 1446 // loading for them, wait if a defineClass is in progress 1447 // and return the initial requestor's results 1448 // This flag does not apply to the bootstrap classloader. 1449 // With AllowParallelDefine flag==false, call through to define_instance_class 1450 // which will throw LinkageError: duplicate class definition. 1451 // False is the requested default. 1452 // For better performance, the class loaders should synchronize 1453 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they 1454 // potentially waste time reading and parsing the bytestream. 1455 // Note: VM callers should ensure consistency of k/class_name,class_loader 1456 // Be careful when modifying this code: once you have run 1457 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS), 1458 // you need to find_and_remove it before returning. 1459 // So be careful to not exit with a CHECK_ macro between these calls. 1460 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader, 1461 InstanceKlass* k, TRAPS) { 1462 1463 Symbol* name_h = k->name(); 1464 ClassLoaderData* loader_data = class_loader_data(class_loader); 1465 Dictionary* dictionary = loader_data->dictionary(); 1466 1467 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS 1468 { 1469 MutexLocker mu(THREAD, SystemDictionary_lock); 1470 // First check if class already defined 1471 if (is_parallelDefine(class_loader)) { 1472 InstanceKlass* check = dictionary->find_class(THREAD, name_h); 1473 if (check != nullptr) { 1474 return check; 1475 } 1476 } 1477 1478 // Acquire define token for this class/classloader 1479 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data, 1480 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD); 1481 // Wait if another thread defining in parallel 1482 // All threads wait - even those that will throw duplicate class: otherwise 1483 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails 1484 // if other thread has not finished updating dictionary 1485 while (probe->definer() != nullptr) { 1486 SystemDictionary_lock->wait(); 1487 } 1488 // Only special cases allow parallel defines and can use other thread's results 1489 // Other cases fall through, and may run into duplicate defines 1490 // caught by finding an entry in the SystemDictionary 1491 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) { 1492 InstanceKlass* ik = probe->instance_klass(); 1493 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1494 SystemDictionary_lock->notify_all(); 1495 #ifdef ASSERT 1496 InstanceKlass* check = dictionary->find_class(THREAD, name_h); 1497 assert(check != nullptr, "definer missed recording success"); 1498 #endif 1499 return ik; 1500 } else { 1501 // This thread will define the class (even if earlier thread tried and had an error) 1502 probe->set_definer(THREAD); 1503 } 1504 } 1505 1506 define_instance_class(k, class_loader, THREAD); 1507 1508 // definer must notify any waiting threads 1509 { 1510 MutexLocker mu(THREAD, SystemDictionary_lock); 1511 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data); 1512 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?"); 1513 if (!HAS_PENDING_EXCEPTION) { 1514 probe->set_instance_klass(k); 1515 } 1516 probe->set_definer(nullptr); 1517 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD); 1518 SystemDictionary_lock->notify_all(); 1519 } 1520 1521 return HAS_PENDING_EXCEPTION ? nullptr : k; 1522 } 1523 1524 // If a class loader supports parallel classloading handle parallel define requests. 1525 // find_or_define_instance_class may return a different InstanceKlass 1526 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, 1527 InstanceKlass* k, TRAPS) { 1528 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD); 1529 // Clean up original InstanceKlass if duplicate or error 1530 if (!HAS_PENDING_EXCEPTION && defined_k != k) { 1531 // If a parallel capable class loader already defined this class, register 'k' for cleanup. 1532 assert(defined_k != nullptr, "Should have a klass if there's no exception"); 1533 k->class_loader_data()->add_to_deallocate_list(k); 1534 } else if (HAS_PENDING_EXCEPTION) { 1535 // Remove this InstanceKlass from the LoaderConstraintTable if added. 1536 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader)); 1537 assert(defined_k == nullptr, "Should not have a klass if there's an exception"); 1538 k->class_loader_data()->add_to_deallocate_list(k); 1539 } 1540 return defined_k; 1541 } 1542 1543 1544 // ---------------------------------------------------------------------------- 1545 // GC support 1546 1547 // Assumes classes in the SystemDictionary are only unloaded at a safepoint 1548 bool SystemDictionary::do_unloading(GCTimer* gc_timer) { 1549 1550 bool unloading_occurred; 1551 bool is_concurrent = !SafepointSynchronize::is_at_safepoint(); 1552 { 1553 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer); 1554 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks. 1555 // First, mark for unload all ClassLoaderData referencing a dead class loader. 1556 unloading_occurred = ClassLoaderDataGraph::do_unloading(); 1557 if (unloading_occurred) { 1558 ConditionalMutexLocker ml2(Module_lock, is_concurrent); 1559 JFR_ONLY(Jfr::on_unloading_classes();) 1560 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();) 1561 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent); 1562 ClassLoaderDataGraph::clean_module_and_package_info(); 1563 LoaderConstraintTable::purge_loader_constraints(); 1564 ResolutionErrorTable::purge_resolution_errors(); 1565 } 1566 } 1567 1568 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer); 1569 1570 if (unloading_occurred) { 1571 SymbolTable::trigger_cleanup(); 1572 1573 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent); 1574 InstanceKlass::clean_initialization_error_table(); 1575 } 1576 1577 return unloading_occurred; 1578 } 1579 1580 void SystemDictionary::methods_do(void f(Method*)) { 1581 // Walk methods in loaded classes 1582 1583 { 1584 MutexLocker ml(ClassLoaderDataGraph_lock); 1585 ClassLoaderDataGraph::methods_do(f); 1586 } 1587 1588 auto doit = [&] (InvokeMethodKey key, Method* method) { 1589 if (method != nullptr) { 1590 f(method); 1591 } 1592 }; 1593 1594 { 1595 MutexLocker ml(InvokeMethodIntrinsicTable_lock); 1596 _invoke_method_intrinsic_table->iterate_all(doit); 1597 } 1598 1599 } 1600 1601 // ---------------------------------------------------------------------------- 1602 // Initialization 1603 1604 void SystemDictionary::initialize(TRAPS) { 1605 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable(); 1606 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable(); 1607 ResolutionErrorTable::initialize(); 1608 LoaderConstraintTable::initialize(); 1609 PlaceholderTable::initialize(); 1610 #if INCLUDE_CDS 1611 SystemDictionaryShared::initialize(); 1612 if (CDSConfig::is_dumping_archive()) { 1613 AOTClassLocationConfig::dumptime_init(THREAD); 1614 } 1615 #endif 1616 // Resolve basic classes 1617 vmClasses::resolve_all(CHECK); 1618 // Resolve classes used by archived heap objects 1619 if (CDSConfig::is_using_archive()) { 1620 HeapShared::resolve_classes(THREAD); 1621 } 1622 } 1623 1624 // Constraints on class loaders. The details of the algorithm can be 1625 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java 1626 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is 1627 // that the dictionary needs to maintain a set of constraints that 1628 // must be satisfied by all classes in the dictionary. 1629 // if defining is true, then LinkageError if already in dictionary 1630 // if initiating loader, then ok if InstanceKlass matches existing entry 1631 1632 void SystemDictionary::check_constraints(InstanceKlass* k, 1633 ClassLoaderData* loader_data, 1634 bool defining, 1635 TRAPS) { 1636 ResourceMark rm(THREAD); 1637 stringStream ss; 1638 bool throwException = false; 1639 1640 { 1641 Symbol* name = k->name(); 1642 1643 MutexLocker mu(THREAD, SystemDictionary_lock); 1644 1645 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name); 1646 if (check != nullptr) { 1647 // If different InstanceKlass - duplicate class definition, 1648 // else - ok, class loaded by a different thread in parallel. 1649 // We should only have found it if it was done loading and ok to use. 1650 1651 if ((defining == true) || (k != check)) { 1652 throwException = true; 1653 ss.print("loader %s", loader_data->loader_name_and_id()); 1654 ss.print(" attempted duplicate %s definition for %s. (%s)", 1655 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true)); 1656 } else { 1657 return; 1658 } 1659 } 1660 1661 if (throwException == false) { 1662 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) { 1663 throwException = true; 1664 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id()); 1665 ss.print(" wants to load %s %s.", 1666 k->external_kind(), k->external_name()); 1667 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data); 1668 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) { 1669 ss.print(" A different %s with the same name was previously loaded by %s. (%s)", 1670 existing_klass->external_kind(), 1671 existing_klass->class_loader_data()->loader_name_and_id(), 1672 existing_klass->class_in_module_of_loader(false, true)); 1673 } else { 1674 ss.print(" (%s)", k->class_in_module_of_loader(false, true)); 1675 } 1676 } 1677 } 1678 } 1679 1680 // Throw error now if needed (cannot throw while holding 1681 // SystemDictionary_lock because of rank ordering) 1682 if (throwException == true) { 1683 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string()); 1684 } 1685 } 1686 1687 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy 1688 // have been called. 1689 void SystemDictionary::update_dictionary(JavaThread* current, 1690 InstanceKlass* k, 1691 ClassLoaderData* loader_data) { 1692 MonitorLocker mu1(SystemDictionary_lock); 1693 1694 // Make a new dictionary entry. 1695 Symbol* name = k->name(); 1696 Dictionary* dictionary = loader_data->dictionary(); 1697 InstanceKlass* sd_check = dictionary->find_class(current, name); 1698 if (sd_check == nullptr) { 1699 dictionary->add_klass(current, name, k); 1700 } 1701 mu1.notify_all(); 1702 } 1703 1704 #if INCLUDE_CDS 1705 // Indicate that loader_data has initiated the loading of class k, which 1706 // has already been defined by a parent loader. 1707 // This API should be used only by AOTLinkedClassBulkLoader 1708 void SystemDictionary::add_to_initiating_loader(JavaThread* current, 1709 InstanceKlass* k, 1710 ClassLoaderData* loader_data) { 1711 assert(CDSConfig::is_using_aot_linked_classes(), "must be"); 1712 assert_locked_or_safepoint(SystemDictionary_lock); 1713 Symbol* name = k->name(); 1714 Dictionary* dictionary = loader_data->dictionary(); 1715 assert(k->is_loaded(), "must be"); 1716 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader"); 1717 assert(dictionary->find_class(current, name) == nullptr, "sanity"); 1718 dictionary->add_klass(current, name, k); 1719 } 1720 #endif 1721 1722 // Try to find a class name using the loader constraints. The 1723 // loader constraints might know about a class that isn't fully loaded 1724 // yet and these will be ignored. 1725 Klass* SystemDictionary::find_constrained_instance_or_array_klass( 1726 Thread* current, Symbol* class_name, Handle class_loader) { 1727 1728 // First see if it has been loaded directly. 1729 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader); 1730 if (klass != nullptr) 1731 return klass; 1732 1733 // Now look to see if it has been loaded elsewhere, and is subject to 1734 // a loader constraint that would require this loader to return the 1735 // klass that is already loaded. 1736 if (Signature::is_array(class_name)) { 1737 // For array classes, their Klass*s are not kept in the 1738 // constraint table. The element Klass*s are. 1739 SignatureStream ss(class_name, false); 1740 int ndims = ss.skip_array_prefix(); // skip all '['s 1741 BasicType t = ss.type(); 1742 if (t != T_OBJECT) { 1743 klass = Universe::typeArrayKlass(t); 1744 } else { 1745 MutexLocker mu(current, SystemDictionary_lock); 1746 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader)); 1747 } 1748 // If element class already loaded, allocate array klass 1749 if (klass != nullptr) { 1750 klass = klass->array_klass_or_null(ndims); 1751 } 1752 } else { 1753 MutexLocker mu(current, SystemDictionary_lock); 1754 // Non-array classes are easy: simply check the constraint table. 1755 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader)); 1756 } 1757 1758 return klass; 1759 } 1760 1761 bool SystemDictionary::add_loader_constraint(Symbol* class_name, 1762 Klass* klass_being_linked, 1763 Handle class_loader1, 1764 Handle class_loader2) { 1765 ClassLoaderData* loader_data1 = class_loader_data(class_loader1); 1766 ClassLoaderData* loader_data2 = class_loader_data(class_loader2); 1767 1768 Symbol* constraint_name = nullptr; 1769 1770 if (!Signature::is_array(class_name)) { 1771 constraint_name = class_name; 1772 } else { 1773 // For array classes, their Klass*s are not kept in the 1774 // constraint table. The element classes are. 1775 SignatureStream ss(class_name, false); 1776 ss.skip_array_prefix(); // skip all '['s 1777 if (!ss.has_envelope()) { 1778 return true; // primitive types always pass 1779 } 1780 constraint_name = ss.as_symbol(); 1781 // Increment refcount to keep constraint_name alive after 1782 // SignatureStream is destructed. It will be decremented below 1783 // before returning. 1784 constraint_name->increment_refcount(); 1785 } 1786 1787 Dictionary* dictionary1 = loader_data1->dictionary(); 1788 Dictionary* dictionary2 = loader_data2->dictionary(); 1789 1790 JavaThread* current = JavaThread::current(); 1791 { 1792 MutexLocker mu_s(SystemDictionary_lock); 1793 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name); 1794 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name); 1795 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1, 1796 klass2, loader_data2); 1797 #if INCLUDE_CDS 1798 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr && 1799 !klass_being_linked->is_shared()) { 1800 SystemDictionaryShared::record_linking_constraint(constraint_name, 1801 InstanceKlass::cast(klass_being_linked), 1802 class_loader1, class_loader2); 1803 } 1804 #endif // INCLUDE_CDS 1805 if (Signature::is_array(class_name)) { 1806 constraint_name->decrement_refcount(); 1807 } 1808 return result; 1809 } 1810 } 1811 1812 // Add entry to resolution error table to record the error when the first 1813 // attempt to resolve a reference to a class has failed. 1814 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which, 1815 Symbol* error, const char* message, 1816 Symbol* cause, const char* cause_msg) { 1817 { 1818 MutexLocker ml(Thread::current(), SystemDictionary_lock); 1819 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which); 1820 if (entry == nullptr) { 1821 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg); 1822 } 1823 } 1824 } 1825 1826 // Delete a resolution error for RedefineClasses for a constant pool is going away 1827 void SystemDictionary::delete_resolution_error(ConstantPool* pool) { 1828 ResolutionErrorTable::delete_entry(pool); 1829 } 1830 1831 // Lookup resolution error table. Returns error if found, otherwise null. 1832 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which, 1833 const char** message, 1834 Symbol** cause, const char** cause_msg) { 1835 1836 { 1837 MutexLocker ml(Thread::current(), SystemDictionary_lock); 1838 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which); 1839 if (entry != nullptr) { 1840 *message = entry->message(); 1841 *cause = entry->cause(); 1842 *cause_msg = entry->cause_msg(); 1843 return entry->error(); 1844 } else { 1845 return nullptr; 1846 } 1847 } 1848 } 1849 1850 // Add an entry to resolution error table to record an error in resolving or 1851 // validating a nest host. This is used to construct informative error 1852 // messages when IllegalAccessError's occur. If an entry already exists it will 1853 // be updated with the nest host error message. 1854 1855 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool, 1856 int which, 1857 const char* message) { 1858 { 1859 MutexLocker ml(Thread::current(), SystemDictionary_lock); 1860 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which); 1861 if (entry != nullptr && entry->nest_host_error() == nullptr) { 1862 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we 1863 // still want to add the error message for the higher-level access checks to report. We should 1864 // only reach here under the same error condition, so we can ignore the potential race with setting 1865 // the message. If we see it is already set then we can ignore it. 1866 entry->set_nest_host_error(message); 1867 } else { 1868 ResolutionErrorTable::add_entry(pool, which, message); 1869 } 1870 } 1871 } 1872 1873 // Lookup any nest host error 1874 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) { 1875 { 1876 MutexLocker ml(Thread::current(), SystemDictionary_lock); 1877 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which); 1878 if (entry != nullptr) { 1879 return entry->nest_host_error(); 1880 } else { 1881 return nullptr; 1882 } 1883 } 1884 } 1885 1886 // Signature constraints ensure that callers and callees agree about 1887 // the meaning of type names in their signatures. This routine is the 1888 // intake for constraints. It collects them from several places: 1889 // 1890 // * LinkResolver::resolve_method (if check_access is true) requires 1891 // that the resolving class (the caller) and the defining class of 1892 // the resolved method (the callee) agree on each type in the 1893 // method's signature. 1894 // 1895 // * LinkResolver::resolve_interface_method performs exactly the same 1896 // checks. 1897 // 1898 // * LinkResolver::resolve_field requires that the constant pool 1899 // attempting to link to a field agree with the field's defining 1900 // class about the type of the field signature. 1901 // 1902 // * klassVtable::initialize_vtable requires that, when a class 1903 // overrides a vtable entry allocated by a superclass, that the 1904 // overriding method (i.e., the callee) agree with the superclass 1905 // on each type in the method's signature. 1906 // 1907 // * klassItable::initialize_itable requires that, when a class fills 1908 // in its itables, for each non-abstract method installed in an 1909 // itable, the method (i.e., the callee) agree with the interface 1910 // on each type in the method's signature. 1911 // 1912 // All those methods have a boolean (check_access, checkconstraints) 1913 // which turns off the checks. This is used from specialized contexts 1914 // such as bootstrapping, dumping, and debugging. 1915 // 1916 // No direct constraint is placed between the class and its 1917 // supertypes. Constraints are only placed along linked relations 1918 // between callers and callees. When a method overrides or implements 1919 // an abstract method in a supertype (superclass or interface), the 1920 // constraints are placed as if the supertype were the caller to the 1921 // overriding method. (This works well, since callers to the 1922 // supertype have already established agreement between themselves and 1923 // the supertype.) As a result of all this, a class can disagree with 1924 // its supertype about the meaning of a type name, as long as that 1925 // class neither calls a relevant method of the supertype, nor is 1926 // called (perhaps via an override) from the supertype. 1927 // 1928 // 1929 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2) 1930 // 1931 // Make sure all class components (including arrays) in the given 1932 // signature will be resolved to the same class in both loaders. 1933 // Returns the name of the type that failed a loader constraint check, or 1934 // null if no constraint failed. No exception except OOME is thrown. 1935 // Arrays are not added to the loader constraint table, their elements are. 1936 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature, 1937 Klass* klass_being_linked, 1938 Handle loader1, Handle loader2, 1939 bool is_method) { 1940 // Nothing to do if loaders are the same. 1941 if (loader1() == loader2()) { 1942 return nullptr; 1943 } 1944 1945 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) { 1946 if (ss.is_reference()) { 1947 Symbol* sig = ss.as_symbol(); 1948 // Note: In the future, if template-like types can take 1949 // arguments, we will want to recognize them and dig out class 1950 // names hiding inside the argument lists. 1951 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) { 1952 return sig; 1953 } 1954 } 1955 } 1956 return nullptr; 1957 } 1958 1959 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid, 1960 Symbol* signature, 1961 TRAPS) { 1962 1963 const int iid_as_int = vmIntrinsics::as_int(iid); 1964 assert(MethodHandles::is_signature_polymorphic(iid) && 1965 MethodHandles::is_signature_polymorphic_intrinsic(iid) && 1966 iid != vmIntrinsics::_invokeGeneric, 1967 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid)); 1968 1969 InvokeMethodKey key(signature, iid_as_int); 1970 Method** met = nullptr; 1971 1972 // We only want one entry in the table for this (signature/id, method) pair but the code 1973 // to create the intrinsic method needs to be outside the lock. 1974 // The first thread claims the entry by adding the key and the other threads wait, until the 1975 // Method has been added as the value. 1976 { 1977 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock); 1978 while (true) { 1979 bool created; 1980 met = _invoke_method_intrinsic_table->put_if_absent(key, &created); 1981 assert(met != nullptr, "either created or found"); 1982 if (*met != nullptr) { 1983 return *met; 1984 } else if (created) { 1985 // The current thread won the race and will try to create the full entry. 1986 break; 1987 } else { 1988 // Another thread beat us to it, so wait for them to complete 1989 // and return *met; or if they hit an error we get another try. 1990 ml.wait(); 1991 // Note it is not safe to read *met here as that entry could have 1992 // been deleted, so we must loop and try put_if_absent again. 1993 } 1994 } 1995 } 1996 1997 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD); 1998 bool throw_error = HAS_PENDING_EXCEPTION; 1999 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) { 2000 // Generate a compiled form of the MH intrinsic 2001 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version. 2002 AdapterHandlerLibrary::create_native_wrapper(m); 2003 // Check if have the compiled code. 2004 throw_error = (!m->has_compiled_code()); 2005 } 2006 2007 { 2008 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock); 2009 if (throw_error) { 2010 // Remove the entry and let another thread try, or get the same exception. 2011 bool removed = _invoke_method_intrinsic_table->remove(key); 2012 assert(removed, "must be the owner"); 2013 ml.notify_all(); 2014 } else { 2015 signature->make_permanent(); // The signature is never unloaded. 2016 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() && 2017 m->code()->entry_point() == m->from_compiled_entry()), 2018 "MH intrinsic invariant"); 2019 *met = m(); // insert the element 2020 ml.notify_all(); 2021 return m(); 2022 } 2023 } 2024 2025 // Throw OOM or the pending exception in the JavaThread 2026 if (throw_error && !HAS_PENDING_EXCEPTION) { 2027 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(), 2028 "Out of space in CodeCache for method handle intrinsic"); 2029 } 2030 return nullptr; 2031 } 2032 2033 #if INCLUDE_CDS 2034 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) { 2035 assert(SafepointSynchronize::is_at_safepoint(), "must be"); 2036 auto do_method = [&] (InvokeMethodKey& key, Method*& m) { 2037 methods->append(m); 2038 }; 2039 _invoke_method_intrinsic_table->iterate_all(do_method); 2040 } 2041 2042 void SystemDictionary::restore_archived_method_handle_intrinsics() { 2043 if (UseSharedSpaces) { 2044 EXCEPTION_MARK; 2045 restore_archived_method_handle_intrinsics_impl(THREAD); 2046 if (HAS_PENDING_EXCEPTION) { 2047 // This is probably caused by OOM -- other parts of the CDS archive have direct pointers to 2048 // the archived method handle intrinsics, so we can't really recover from this failure. 2049 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics. Try to increase heap size.")); 2050 } 2051 } 2052 } 2053 2054 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) { 2055 Array<Method*>* list = MetaspaceShared::archived_method_handle_intrinsics(); 2056 for (int i = 0; i < list->length(); i++) { 2057 methodHandle m(THREAD, list->at(i)); 2058 Method::restore_archived_method_handle_intrinsic(m, CHECK); 2059 m->constants()->restore_unshareable_info(CHECK); 2060 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) { 2061 AdapterHandlerLibrary::create_native_wrapper(m); 2062 if (!m->has_compiled_code()) { 2063 ResourceMark rm(THREAD); 2064 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name())); 2065 } 2066 } 2067 2068 // There's no need to grab the InvokeMethodIntrinsicTable_lock, as we are still very early in 2069 // VM start-up -- in init_globals2() -- so we are still running a single Java thread. It's not 2070 // possible to have a contention. 2071 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id()); 2072 InvokeMethodKey key(m->signature(), iid_as_int); 2073 bool created = _invoke_method_intrinsic_table->put(key, m()); 2074 assert(created, "unexpected contention"); 2075 } 2076 } 2077 #endif // INCLUDE_CDS 2078 2079 // Helper for unpacking the return value from linkMethod and linkCallSite. 2080 static Method* unpack_method_and_appendix(Handle mname, 2081 Klass* accessing_klass, 2082 objArrayHandle appendix_box, 2083 Handle* appendix_result, 2084 TRAPS) { 2085 if (mname.not_null()) { 2086 Method* m = java_lang_invoke_MemberName::vmtarget(mname()); 2087 if (m != nullptr) { 2088 oop appendix = appendix_box->obj_at(0); 2089 LogTarget(Info, methodhandles) lt; 2090 if (lt.develop_is_enabled()) { 2091 ResourceMark rm(THREAD); 2092 LogStream ls(lt); 2093 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m)); 2094 m->print_on(&ls); 2095 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); } 2096 ls.cr(); 2097 } 2098 2099 (*appendix_result) = Handle(THREAD, appendix); 2100 // the target is stored in the cpCache and if a reference to this 2101 // MemberName is dropped we need a way to make sure the 2102 // class_loader containing this method is kept alive. 2103 methodHandle mh(THREAD, m); // record_dependency can safepoint. 2104 ClassLoaderData* this_key = accessing_klass->class_loader_data(); 2105 this_key->record_dependency(m->method_holder()); 2106 return mh(); 2107 } 2108 } 2109 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives"); 2110 } 2111 2112 Method* SystemDictionary::find_method_handle_invoker(Klass* klass, 2113 Symbol* name, 2114 Symbol* signature, 2115 Klass* accessing_klass, 2116 Handle* appendix_result, 2117 TRAPS) { 2118 guarantee(THREAD->can_call_java(), ""); 2119 Handle method_type = 2120 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL); 2121 2122 int ref_kind = JVM_REF_invokeVirtual; 2123 oop name_oop = StringTable::intern(name, CHECK_NULL); 2124 Handle name_str (THREAD, name_oop); 2125 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL); 2126 assert(appendix_box->obj_at(0) == nullptr, ""); 2127 2128 // This should not happen. JDK code should take care of that. 2129 if (accessing_klass == nullptr || method_type.is_null()) { 2130 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle"); 2131 } 2132 2133 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName 2134 JavaCallArguments args; 2135 args.push_oop(Handle(THREAD, accessing_klass->java_mirror())); 2136 args.push_int(ref_kind); 2137 args.push_oop(Handle(THREAD, klass->java_mirror())); 2138 args.push_oop(name_str); 2139 args.push_oop(method_type); 2140 args.push_oop(appendix_box); 2141 JavaValue result(T_OBJECT); 2142 JavaCalls::call_static(&result, 2143 vmClasses::MethodHandleNatives_klass(), 2144 vmSymbols::linkMethod_name(), 2145 vmSymbols::linkMethod_signature(), 2146 &args, CHECK_NULL); 2147 Handle mname(THREAD, result.get_oop()); 2148 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD); 2149 } 2150 2151 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks. 2152 // We must ensure that all class loaders everywhere will reach this class, for any client. 2153 // This is a safe bet for public classes in java.lang, such as Object and String. 2154 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types. 2155 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util. 2156 static bool is_always_visible_class(oop mirror) { 2157 Klass* klass = java_lang_Class::as_Klass(mirror); 2158 if (klass->is_objArray_klass()) { 2159 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type 2160 } 2161 if (klass->is_typeArray_klass()) { 2162 return true; // primitive array 2163 } 2164 assert(klass->is_instance_klass(), "%s", klass->external_name()); 2165 return klass->is_public() && 2166 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang 2167 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke 2168 } 2169 2170 // Find or construct the Java mirror (java.lang.Class instance) for 2171 // the given field type signature, as interpreted relative to the 2172 // given class loader. Handles primitives, void, references, arrays, 2173 // and all other reflectable types, except method types. 2174 // N.B. Code in reflection should use this entry point. 2175 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature, 2176 Klass* accessing_klass, 2177 SignatureStream::FailureMode failure_mode, 2178 TRAPS) { 2179 2180 Handle class_loader; 2181 2182 // What we have here must be a valid field descriptor, 2183 // and all valid field descriptors are supported. 2184 // Produce the same java.lang.Class that reflection reports. 2185 if (accessing_klass != nullptr) { 2186 class_loader = Handle(THREAD, accessing_klass->class_loader()); 2187 } 2188 ResolvingSignatureStream ss(signature, class_loader, false); 2189 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH); 2190 if (mirror_oop == nullptr) { 2191 return Handle(); // report failure this way 2192 } 2193 Handle mirror(THREAD, mirror_oop); 2194 2195 if (accessing_klass != nullptr) { 2196 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve. 2197 Klass* sel_klass = java_lang_Class::as_Klass(mirror()); 2198 if (sel_klass != nullptr) { 2199 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH); 2200 } 2201 } 2202 return mirror; 2203 } 2204 2205 2206 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given 2207 // signature, as interpreted relative to the given class loader. 2208 // Because of class loader constraints, all method handle usage must be 2209 // consistent with this loader. 2210 Handle SystemDictionary::find_method_handle_type(Symbol* signature, 2211 Klass* accessing_klass, 2212 TRAPS) { 2213 Handle empty; 2214 OopHandle* o; 2215 { 2216 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock); 2217 o = _invoke_method_type_table->get(signature); 2218 } 2219 2220 if (o != nullptr) { 2221 oop mt = o->resolve(); 2222 assert(java_lang_invoke_MethodType::is_instance(mt), ""); 2223 return Handle(THREAD, mt); 2224 } else if (!THREAD->can_call_java()) { 2225 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME 2226 return Handle(); // do not attempt from within compiler, unless it was cached 2227 } 2228 2229 Handle class_loader; 2230 if (accessing_klass != nullptr) { 2231 class_loader = Handle(THREAD, accessing_klass->class_loader()); 2232 } 2233 bool can_be_cached = true; 2234 int npts = ArgumentCount(signature).size(); 2235 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty)); 2236 int arg = 0; 2237 Handle rt; // the return type from the signature 2238 ResourceMark rm(THREAD); 2239 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) { 2240 oop mirror = nullptr; 2241 if (can_be_cached) { 2242 // Use neutral class loader to lookup candidate classes to be placed in the cache. 2243 mirror = ss.as_java_mirror(Handle(), SignatureStream::ReturnNull, CHECK_(empty)); 2244 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) { 2245 // Fall back to accessing_klass context. 2246 can_be_cached = false; 2247 } 2248 } 2249 if (!can_be_cached) { 2250 // Resolve, throwing a real error if it doesn't work. 2251 mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty)); 2252 } 2253 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string()); 2254 if (ss.at_return_type()) 2255 rt = Handle(THREAD, mirror); 2256 else 2257 pts->obj_at_put(arg++, mirror); 2258 2259 // Check accessibility. 2260 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) { 2261 Klass* sel_klass = java_lang_Class::as_Klass(mirror); 2262 mirror = nullptr; // safety 2263 // Emulate ConstantPool::verify_constant_pool_resolve. 2264 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty)); 2265 } 2266 } 2267 assert(arg == npts, ""); 2268 2269 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType 2270 JavaCallArguments args(Handle(THREAD, rt())); 2271 args.push_oop(pts); 2272 JavaValue result(T_OBJECT); 2273 JavaCalls::call_static(&result, 2274 vmClasses::MethodHandleNatives_klass(), 2275 vmSymbols::findMethodHandleType_name(), 2276 vmSymbols::findMethodHandleType_signature(), 2277 &args, CHECK_(empty)); 2278 Handle method_type(THREAD, result.get_oop()); 2279 2280 if (can_be_cached) { 2281 // We can cache this MethodType inside the JVM. 2282 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock); 2283 bool created = false; 2284 assert(method_type != nullptr, "unexpected null"); 2285 OopHandle* h = _invoke_method_type_table->get(signature); 2286 if (h == nullptr) { 2287 signature->make_permanent(); // The signature is never unloaded. 2288 OopHandle elem = OopHandle(Universe::vm_global(), method_type()); 2289 bool created = _invoke_method_type_table->put(signature, elem); 2290 assert(created, "better be created"); 2291 } 2292 } 2293 // report back to the caller with the MethodType 2294 return method_type; 2295 } 2296 2297 Handle SystemDictionary::find_field_handle_type(Symbol* signature, 2298 Klass* accessing_klass, 2299 TRAPS) { 2300 Handle empty; 2301 ResourceMark rm(THREAD); 2302 SignatureStream ss(signature, /*is_method=*/ false); 2303 if (!ss.is_done()) { 2304 Handle class_loader; 2305 if (accessing_klass != nullptr) { 2306 class_loader = Handle(THREAD, accessing_klass->class_loader()); 2307 } 2308 oop mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty)); 2309 ss.next(); 2310 if (ss.is_done()) { 2311 return Handle(THREAD, mirror); 2312 } 2313 } 2314 return empty; 2315 } 2316 2317 // Ask Java code to find or construct a method handle constant. 2318 Handle SystemDictionary::link_method_handle_constant(Klass* caller, 2319 int ref_kind, //e.g., JVM_REF_invokeVirtual 2320 Klass* callee, 2321 Symbol* name, 2322 Symbol* signature, 2323 TRAPS) { 2324 Handle empty; 2325 if (caller == nullptr) { 2326 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty); 2327 } 2328 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty)); 2329 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty)); 2330 2331 // Put symbolic info from the MH constant into freshly created MemberName and resolve it. 2332 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty)); 2333 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror()); 2334 java_lang_invoke_MemberName::set_name (mname(), name_str()); 2335 java_lang_invoke_MemberName::set_type (mname(), signature_str()); 2336 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind)); 2337 2338 if (ref_kind == JVM_REF_invokeVirtual && 2339 MethodHandles::is_signature_polymorphic_public_name(callee, name)) { 2340 // Skip resolution for public signature polymorphic methods such as 2341 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle 2342 // They require appendix argument which MemberName resolution doesn't handle. 2343 // There's special logic on JDK side to handle them 2344 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()). 2345 } else { 2346 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty)); 2347 } 2348 2349 // After method/field resolution succeeded, it's safe to resolve MH signature as well. 2350 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty)); 2351 2352 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle 2353 JavaCallArguments args; 2354 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class 2355 args.push_int(ref_kind); 2356 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class 2357 args.push_oop(name_str); 2358 args.push_oop(type); 2359 JavaValue result(T_OBJECT); 2360 JavaCalls::call_static(&result, 2361 vmClasses::MethodHandleNatives_klass(), 2362 vmSymbols::linkMethodHandleConstant_name(), 2363 vmSymbols::linkMethodHandleConstant_signature(), 2364 &args, CHECK_(empty)); 2365 return Handle(THREAD, result.get_oop()); 2366 } 2367 2368 // Ask Java to run a bootstrap method, in order to create a dynamic call site 2369 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry 2370 // with linkage results being stored back into the bootstrap specifier. 2371 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) { 2372 // Resolve the bootstrap specifier, its name, type, and static arguments 2373 bootstrap_specifier.resolve_bsm(CHECK); 2374 2375 // This should not happen. JDK code should take care of that. 2376 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) { 2377 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument"); 2378 } 2379 2380 bool is_indy = bootstrap_specifier.is_method_call(); 2381 objArrayHandle appendix_box; 2382 if (is_indy) { 2383 // Some method calls may require an appendix argument. Arrange to receive it. 2384 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK); 2385 assert(appendix_box->obj_at(0) == nullptr, ""); 2386 } 2387 2388 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info) 2389 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix) 2390 JavaCallArguments args; 2391 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror())); 2392 args.push_oop(bootstrap_specifier.bsm()); 2393 args.push_oop(bootstrap_specifier.name_arg()); 2394 args.push_oop(bootstrap_specifier.type_arg()); 2395 args.push_oop(bootstrap_specifier.arg_values()); 2396 if (is_indy) { 2397 args.push_oop(appendix_box); 2398 } 2399 JavaValue result(T_OBJECT); 2400 JavaCalls::call_static(&result, 2401 vmClasses::MethodHandleNatives_klass(), 2402 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(), 2403 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(), 2404 &args, CHECK); 2405 2406 Handle value(THREAD, result.get_oop()); 2407 if (is_indy) { 2408 Handle appendix; 2409 Method* method = unpack_method_and_appendix(value, 2410 bootstrap_specifier.caller(), 2411 appendix_box, 2412 &appendix, CHECK); 2413 methodHandle mh(THREAD, method); 2414 bootstrap_specifier.set_resolved_method(mh, appendix); 2415 } else { 2416 bootstrap_specifier.set_resolved_value(value); 2417 } 2418 2419 // sanity check 2420 assert(bootstrap_specifier.is_resolved() || 2421 (bootstrap_specifier.is_method_call() && 2422 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed"); 2423 } 2424 2425 2426 bool SystemDictionary::is_nonpublic_Object_method(Method* m) { 2427 assert(m != nullptr, "Unexpected nullptr Method*"); 2428 return !m->is_public() && m->method_holder() == vmClasses::Object_klass(); 2429 } 2430 2431 // ---------------------------------------------------------------------------- 2432 2433 void SystemDictionary::print_on(outputStream *st) { 2434 CDS_ONLY(SystemDictionaryShared::print_on(st)); 2435 GCMutexLocker mu(SystemDictionary_lock); 2436 2437 ClassLoaderDataGraph::print_dictionary(st); 2438 2439 // Placeholders 2440 PlaceholderTable::print_on(st); 2441 st->cr(); 2442 2443 // loader constraints - print under SD_lock 2444 LoaderConstraintTable::print_on(st); 2445 st->cr(); 2446 } 2447 2448 void SystemDictionary::print() { print_on(tty); } 2449 2450 void SystemDictionary::verify() { 2451 2452 GCMutexLocker mu(SystemDictionary_lock); 2453 2454 // Verify dictionary 2455 ClassLoaderDataGraph::verify_dictionary(); 2456 2457 // Verify constraint table 2458 LoaderConstraintTable::verify(); 2459 } 2460 2461 void SystemDictionary::dump(outputStream *st, bool verbose) { 2462 assert_locked_or_safepoint(SystemDictionary_lock); 2463 if (verbose) { 2464 print_on(st); 2465 } else { 2466 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st)); 2467 ClassLoaderDataGraph::print_table_statistics(st); 2468 LoaderConstraintTable::print_table_statistics(st); 2469 } 2470 } 2471 2472 // Utility for dumping dictionaries. 2473 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) : 2474 DCmdWithParser(output, heap), 2475 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders", 2476 "BOOLEAN", false, "false") { 2477 _dcmdparser.add_dcmd_option(&_verbose); 2478 } 2479 2480 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) { 2481 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict, 2482 _verbose.value()); 2483 VMThread::execute(&dumper); 2484 }