1 /*
2 * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/heapShared.hpp"
27 #include "classfile/classFileParser.hpp"
28 #include "classfile/classFileStream.hpp"
29 #include "classfile/classLoader.hpp"
30 #include "classfile/classLoaderData.inline.hpp"
31 #include "classfile/classLoaderDataGraph.inline.hpp"
32 #include "classfile/classLoaderExt.hpp"
33 #include "classfile/classLoadInfo.hpp"
34 #include "classfile/dictionary.hpp"
35 #include "classfile/javaClasses.inline.hpp"
36 #include "classfile/klassFactory.hpp"
37 #include "classfile/loaderConstraints.hpp"
38 #include "classfile/packageEntry.hpp"
39 #include "classfile/placeholders.hpp"
40 #include "classfile/protectionDomainCache.hpp"
41 #include "classfile/resolutionErrors.hpp"
42 #include "classfile/stringTable.hpp"
43 #include "classfile/symbolTable.hpp"
44 #include "classfile/systemDictionary.hpp"
45 #include "classfile/vmClasses.hpp"
46 #include "classfile/vmSymbols.hpp"
47 #include "code/codeCache.hpp"
48 #include "gc/shared/gcTraceTime.inline.hpp"
49 #include "interpreter/bootstrapInfo.hpp"
50 #include "jfr/jfrEvents.hpp"
51 #include "jvm.h"
52 #include "logging/log.hpp"
53 #include "logging/logStream.hpp"
54 #include "memory/metaspaceClosure.hpp"
55 #include "memory/oopFactory.hpp"
56 #include "memory/resourceArea.hpp"
57 #include "memory/universe.hpp"
58 #include "oops/access.inline.hpp"
59 #include "oops/fieldStreams.inline.hpp"
60 #include "oops/instanceKlass.hpp"
61 #include "oops/klass.inline.hpp"
62 #include "oops/method.inline.hpp"
63 #include "oops/objArrayKlass.hpp"
64 #include "oops/objArrayOop.inline.hpp"
65 #include "oops/oop.inline.hpp"
66 #include "oops/oop.hpp"
67 #include "oops/oopHandle.hpp"
68 #include "oops/oopHandle.inline.hpp"
69 #include "oops/symbol.hpp"
70 #include "oops/typeArrayKlass.hpp"
71 #include "oops/inlineKlass.inline.hpp"
72 #include "prims/jvmtiExport.hpp"
73 #include "prims/methodHandles.hpp"
74 #include "runtime/arguments.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/macros.hpp"
88 #include "utilities/utf8.hpp"
89 #if INCLUDE_CDS
90 #include "classfile/systemDictionaryShared.hpp"
91 #endif
92 #if INCLUDE_JFR
93 #include "jfr/jfr.hpp"
94 #endif
95
96 class InvokeMethodKey : public StackObj {
97 private:
98 Symbol* _symbol;
99 intptr_t _iid;
100
101 public:
102 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
103 _symbol(symbol),
104 _iid(iid) {}
105
106 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
107 return k1._symbol == k2._symbol && k1._iid == k2._iid;
108 }
109
110 static unsigned int compute_hash(const InvokeMethodKey &k) {
111 Symbol* sym = k._symbol;
112 intptr_t iid = k._iid;
113 unsigned int hash = (unsigned int) sym -> identity_hash();
114 return (unsigned int) (hash ^ iid);
115 }
116
117 };
118
119 ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
120 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison> _invoke_method_intrinsic_table;
121 ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash> _invoke_method_type_table;
122
123 OopHandle SystemDictionary::_java_system_loader;
124 OopHandle SystemDictionary::_java_platform_loader;
125
126 // ----------------------------------------------------------------------------
127 // Java-level SystemLoader and PlatformLoader
128 oop SystemDictionary::java_system_loader() {
129 return _java_system_loader.resolve();
130 }
131
132 oop SystemDictionary::java_platform_loader() {
133 return _java_platform_loader.resolve();
134 }
135
136 void SystemDictionary::compute_java_loaders(TRAPS) {
137 if (_java_system_loader.is_empty()) {
138 oop system_loader = get_system_class_loader_impl(CHECK);
139 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
140 } else {
141 // It must have been restored from the archived module graph
142 assert(UseSharedSpaces, "must be");
143 assert(MetaspaceShared::use_full_module_graph(), "must be");
144 DEBUG_ONLY(
145 oop system_loader = get_system_class_loader_impl(CHECK);
146 assert(_java_system_loader.resolve() == system_loader, "must be");
147 )
148 }
149
150 if (_java_platform_loader.is_empty()) {
151 oop platform_loader = get_platform_class_loader_impl(CHECK);
152 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
153 } else {
154 // It must have been restored from the archived module graph
155 assert(UseSharedSpaces, "must be");
156 assert(MetaspaceShared::use_full_module_graph(), "must be");
157 DEBUG_ONLY(
158 oop platform_loader = get_platform_class_loader_impl(CHECK);
159 assert(_java_platform_loader.resolve() == platform_loader, "must be");
160 )
161 }
162 }
163
164 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
165 JavaValue result(T_OBJECT);
166 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
167 JavaCalls::call_static(&result,
168 class_loader_klass,
169 vmSymbols::getSystemClassLoader_name(),
170 vmSymbols::void_classloader_signature(),
171 CHECK_NULL);
172 return result.get_oop();
173 }
174
175 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
176 JavaValue result(T_OBJECT);
177 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
178 JavaCalls::call_static(&result,
179 class_loader_klass,
180 vmSymbols::getPlatformClassLoader_name(),
181 vmSymbols::void_classloader_signature(),
182 CHECK_NULL);
183 return result.get_oop();
184 }
185
186 // Helper function
187 inline ClassLoaderData* class_loader_data(Handle class_loader) {
188 return ClassLoaderData::class_loader_data(class_loader());
189 }
190
191 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
192 if (create_mirror_cld) {
193 // Add a new class loader data to the graph.
194 return ClassLoaderDataGraph::add(class_loader, true);
195 } else {
196 return (class_loader() == NULL) ? ClassLoaderData::the_null_class_loader_data() :
197 ClassLoaderDataGraph::find_or_create(class_loader);
198 }
199 }
200
201 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
202 assert(_java_system_loader.is_empty(), "already set!");
203 _java_system_loader = cld->class_loader_handle();
204
205 }
206
207 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
208 assert(_java_platform_loader.is_empty(), "already set!");
209 _java_platform_loader = cld->class_loader_handle();
210 }
211
212 // ----------------------------------------------------------------------------
213 // Parallel class loading check
214
215 bool is_parallelCapable(Handle class_loader) {
216 if (class_loader.is_null()) return true;
217 return java_lang_ClassLoader::parallelCapable(class_loader());
218 }
219 // ----------------------------------------------------------------------------
220 // ParallelDefineClass flag does not apply to bootclass loader
221 bool is_parallelDefine(Handle class_loader) {
222 if (class_loader.is_null()) return false;
223 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
224 return true;
225 }
226 return false;
227 }
228
229 // Returns true if the passed class loader is the builtin application class loader
230 // or a custom system class loader. A customer system class loader can be
231 // specified via -Djava.system.class.loader.
232 bool SystemDictionary::is_system_class_loader(oop class_loader) {
233 if (class_loader == NULL) {
234 return false;
235 }
236 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
237 class_loader == _java_system_loader.peek());
238 }
239
240 // Returns true if the passed class loader is the platform class loader.
241 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
242 if (class_loader == NULL) {
243 return false;
244 }
245 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
246 }
247
248 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
249 // If class_loader is NULL or parallelCapable, the JVM doesn't acquire a lock while loading.
250 if (is_parallelCapable(class_loader)) {
251 return Handle();
252 } else {
253 return class_loader;
254 }
255 }
256
257 // ----------------------------------------------------------------------------
258 // Resolving of classes
259
260 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
261 if (name == NULL) {
262 THROW_MSG_0(exception, "No class name given");
263 }
264 if ((int)strlen(name) > Symbol::max_length()) {
265 // It's impossible to create this class; the name cannot fit
266 // into the constant pool.
267 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
268 "Class name exceeds maximum length of %d: %s",
269 Symbol::max_length(),
270 name);
271 return NULL;
272 }
273 // Callers should ensure that the name is never an illegal UTF8 string.
274 assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false),
275 "Class name is not a valid utf8 string.");
276
277 // Make a new symbol for the class name.
278 return SymbolTable::new_symbol(name);
279 }
280
281 #ifdef ASSERT
282 // Used to verify that class loading succeeded in adding k to the dictionary.
283 void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
284 MutexLocker mu(SystemDictionary_lock);
285 ClassLoaderData* loader_data = k->class_loader_data();
286 Dictionary* dictionary = loader_data->dictionary();
287 assert(class_name == k->name(), "Must be the same");
288 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
289 assert(kk == k, "should be present in dictionary");
290 }
291 #endif
292
293 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
294 if (HAS_PENDING_EXCEPTION) {
295 // If we have a pending exception we forward it to the caller, unless throw_error is true,
296 // in which case we have to check whether the pending exception is a ClassNotFoundException,
297 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
298 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
299 ResourceMark rm(THREAD);
300 Handle e(THREAD, PENDING_EXCEPTION);
301 CLEAR_PENDING_EXCEPTION;
302 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
303 } else {
304 return; // the caller will throw the incoming exception
305 }
306 }
307 // If the class is not found, ie, caller has checked that klass is NULL, throw the appropriate
308 // error or exception depending on the value of throw_error.
309 ResourceMark rm(THREAD);
310 if (throw_error) {
311 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
312 } else {
313 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
314 }
315 }
316
317 // Forwards to resolve_or_null
318
319 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
320 bool throw_error, TRAPS) {
321 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
322 // Check for pending exception or null klass, and throw exception
323 if (HAS_PENDING_EXCEPTION || klass == NULL) {
324 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
325 }
326 return klass;
327 }
328
329 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
330
331 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
332 if (Signature::is_array(class_name)) {
333 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
334 } else {
335 assert(class_name != NULL && !Signature::is_array(class_name), "must be");
336 if (Signature::has_envelope(class_name)) {
337 ResourceMark rm(THREAD);
338 // Ignore wrapping L and ; (and Q and ; for value types).
339 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
340 class_name->utf8_length() - 2);
341 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
342 } else {
343 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
344 }
345 }
346 }
347
348 // Forwards to resolve_instance_class_or_null
349
350 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
351 Handle class_loader,
352 Handle protection_domain,
353 TRAPS) {
354 assert(Signature::is_array(class_name), "must be array");
355 ResourceMark rm(THREAD);
356 SignatureStream ss(class_name, false);
357 int ndims = ss.skip_array_prefix(); // skip all '['s
358 Klass* k = NULL;
359 BasicType t = ss.type();
360 if (ss.has_envelope()) {
361 Symbol* obj_class = ss.as_symbol();
362 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
363 class_loader,
364 protection_domain,
365 CHECK_NULL);
366 if (k != NULL) {
367 if (class_name->is_Q_array_signature()) {
368 if (!k->is_inline_klass()) {
369 THROW_MSG_NULL(vmSymbols::java_lang_IncompatibleClassChangeError(), "L/Q mismatch on bottom type");
370 }
371 k = InlineKlass::cast(k)->value_array_klass(ndims, CHECK_NULL);
372 } else {
373 k = k->array_klass(ndims, CHECK_NULL);
374 }
375 }
376 } else {
377 k = Universe::typeArrayKlassObj(t);
378 k = TypeArrayKlass::cast(k)->array_klass(ndims, CHECK_NULL);
379 }
380 return k;
381 }
382
383 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
384 LogTarget(Debug, class, load, placeholders) lt;
385 if (lt.is_enabled()) {
386 ResourceMark rm;
387 LogStream ls(lt);
388 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
389 probe->print_on(&ls);
390 ls.cr();
391 }
392 }
393
394 // Must be called for any superclass or superinterface resolution
395 // during class definition to allow class circularity checking
396 // superinterface callers:
397 // parse_interfaces - from defineClass
398 // superclass callers:
399 // ClassFileParser - from defineClass
400 // load_shared_class - while loading a class from shared archive
401 // resolve_instance_class_or_null:
402 // via: handle_parallel_super_load
403 // when resolving a class that has an existing placeholder with
404 // a saved superclass [i.e. a defineClass is currently in progress]
405 // If another thread is trying to resolve the class, it must do
406 // superclass checks on its own thread to catch class circularity and
407 // to avoid deadlock.
408 //
409 // resolve_super_or_fail adds a LOAD_SUPER placeholder to the placeholder table before calling
410 // resolve_instance_class_or_null. ClassCircularityError is detected when a LOAD_SUPER or LOAD_INSTANCE
411 // placeholder for the same thread, class, classloader is found.
412 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
413 //
414 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* class_name,
415 Symbol* super_name,
416 Handle class_loader,
417 Handle protection_domain,
418 bool is_superclass,
419 TRAPS) {
420
421 assert(super_name != NULL, "null superclass for resolving");
422 assert(!Signature::is_array(super_name), "invalid superclass name");
423 #if INCLUDE_CDS
424 if (DumpSharedSpaces) {
425 // Special processing for handling UNREGISTERED shared classes.
426 InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
427 super_name, is_superclass);
428 if (k) {
429 return k;
430 }
431 }
432 #endif // INCLUDE_CDS
433
434 // If klass is already loaded, just return the superclass or superinterface.
435 // Make sure there's a placeholder for the class_name before resolving.
436 // This is used as a claim that this thread is currently loading superclass/classloader
437 // and for ClassCircularity checks.
438
439 ClassLoaderData* loader_data = class_loader_data(class_loader);
440 Dictionary* dictionary = loader_data->dictionary();
441
442 // can't throw error holding a lock
443 bool throw_circularity_error = false;
444 {
445 MutexLocker mu(THREAD, SystemDictionary_lock);
446 InstanceKlass* klassk = dictionary->find_class(THREAD, class_name);
447 InstanceKlass* quicksuperk;
448 // To support parallel loading: if class is done loading, just return the superclass
449 // if the super_name matches class->super()->name() and if the class loaders match.
450 // Otherwise, a LinkageError will be thrown later.
451 if (klassk != NULL && is_superclass &&
452 ((quicksuperk = klassk->java_super()) != NULL) &&
453 ((quicksuperk->name() == super_name) &&
454 (quicksuperk->class_loader() == class_loader()))) {
455 return quicksuperk;
456 } else {
457 // Must check ClassCircularity before checking if superclass is already loaded.
458 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
459 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
460 log_circularity_error(class_name, probe);
461 throw_circularity_error = true;
462 }
463 }
464
465 if (!throw_circularity_error) {
466 // Be careful not to exit resolve_super without removing this placeholder.
467 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
468 loader_data,
469 PlaceholderTable::LOAD_SUPER,
470 super_name, THREAD);
471 }
472 }
473
474 if (throw_circularity_error) {
475 ResourceMark rm(THREAD);
476 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
477 }
478
479 // Resolve the superclass or superinterface, check results on return
480 InstanceKlass* superk =
481 SystemDictionary::resolve_instance_class_or_null(super_name,
482 class_loader,
483 protection_domain,
484 THREAD);
485
486 // Clean up placeholder entry.
487 {
488 MutexLocker mu(THREAD, SystemDictionary_lock);
489 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
490 SystemDictionary_lock->notify_all();
491 }
492
493 // Check for pending exception or null superk, and throw exception
494 if (HAS_PENDING_EXCEPTION || superk == NULL) {
495 handle_resolution_exception(super_name, true, CHECK_NULL);
496 }
497
498 return superk;
499 }
500
501 Klass* SystemDictionary::resolve_inline_type_field_or_fail(AllFieldStream* fs,
502 Handle class_loader,
503 Handle protection_domain,
504 bool throw_error,
505 TRAPS) {
506 Symbol* class_name = fs->signature()->fundamental_name(THREAD);
507 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
508 ClassLoaderData* loader_data = class_loader_data(class_loader);
509 bool throw_circularity_error = false;
510 PlaceholderEntry* oldprobe;
511
512 {
513 MutexLocker mu(THREAD, SystemDictionary_lock);
514 oldprobe = PlaceholderTable::get_entry(class_name, loader_data);
515 if (oldprobe != NULL &&
516 oldprobe->check_seen_thread(THREAD, PlaceholderTable::PRIMITIVE_OBJECT_FIELD)) {
517 throw_circularity_error = true;
518
519 } else {
520 PlaceholderTable::find_and_add(class_name, loader_data,
521 PlaceholderTable::PRIMITIVE_OBJECT_FIELD, NULL, THREAD);
522 }
523 }
524
525 Klass* klass = NULL;
526 if (!throw_circularity_error) {
527 klass = SystemDictionary::resolve_or_fail(class_name, class_loader,
528 protection_domain, true, THREAD);
529 } else {
530 ResourceMark rm(THREAD);
531 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
532 }
533
534 {
535 MutexLocker mu(THREAD, SystemDictionary_lock);
536 PlaceholderTable::find_and_remove(class_name, loader_data,
537 PlaceholderTable::PRIMITIVE_OBJECT_FIELD, THREAD);
538 }
539
540 class_name->decrement_refcount();
541 return klass;
542 }
543
544 // We only get here if this thread finds that another thread
545 // has already claimed the placeholder token for the current operation,
546 // but that other thread either never owned or gave up the
547 // object lock
548 // Waits on SystemDictionary_lock to indicate placeholder table updated
549 // On return, caller must recheck placeholder table state
550 //
551 // We only get here if
552 // 1) custom classLoader, i.e. not bootstrap classloader
553 // 2) custom classLoader has broken the class loader objectLock
554 // so another thread got here in parallel
555 //
556 // lockObject must be held.
557 // Complicated dance due to lock ordering:
558 // Must first release the classloader object lock to
559 // allow initial definer to complete the class definition
560 // and to avoid deadlock
561 // Reclaim classloader lock object with same original recursion count
562 // Must release SystemDictionary_lock after notify, since
563 // class loader lock must be claimed before SystemDictionary_lock
564 // to prevent deadlocks
565 //
566 // The notify allows applications that did an untimed wait() on
567 // the classloader object lock to not hang.
568 static void double_lock_wait(JavaThread* thread, Handle lockObject) {
569 assert_lock_strong(SystemDictionary_lock);
570
571 assert(EnableWaitForParallelLoad,
572 "Only called when enabling legacy parallel class loading logic "
573 "for non-parallel capable class loaders");
574 assert(lockObject() != NULL, "lockObject must be non-NULL");
575 bool calledholdinglock
576 = ObjectSynchronizer::current_thread_holds_lock(thread, lockObject);
577 assert(calledholdinglock, "must hold lock for notify");
578 assert(!is_parallelCapable(lockObject), "lockObject must not be parallelCapable");
579 // These don't throw exceptions.
580 ObjectSynchronizer::notifyall(lockObject, thread);
581 intx recursions = ObjectSynchronizer::complete_exit(lockObject, thread);
582 SystemDictionary_lock->wait();
583 SystemDictionary_lock->unlock();
584 ObjectSynchronizer::reenter(lockObject, recursions, thread);
585 SystemDictionary_lock->lock();
586 }
587
588 // If the class in is in the placeholder table, class loading is in progress.
589 // For cases where the application changes threads to load classes, it
590 // is critical to ClassCircularity detection that we try loading
591 // the superclass on the new thread internally, so we do parallel
592 // superclass loading here. This avoids deadlock for ClassCircularity
593 // detection for parallelCapable class loaders that lock on a per-class lock.
594 static void handle_parallel_super_load(Symbol* name,
595 Symbol* superclassname,
596 Handle class_loader,
597 Handle protection_domain, TRAPS) {
598
599 // superk is not used; resolve_super_or_fail is called for circularity check only.
600 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
601 superclassname,
602 class_loader,
603 protection_domain,
604 true,
605 CHECK);
606 }
607
608 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
609 // wait for parallel class loading and to check for circularity error for Xcomp when loading
610 // signature classes.
611 // parallelCapable class loaders do NOT wait for parallel loads to complete
612 static bool needs_load_placeholder(Handle class_loader) {
613 return class_loader.is_null() || !is_parallelCapable(class_loader);
614 }
615
616 // For bootstrap and non-parallelCapable class loaders, check and wait for
617 // another thread to complete loading this class.
618 InstanceKlass* SystemDictionary::handle_parallel_loading(JavaThread* current,
619 Symbol* name,
620 ClassLoaderData* loader_data,
621 Handle lockObject,
622 bool* throw_circularity_error) {
623 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
624 if (oldprobe != NULL) {
625 // only need check_seen_thread once, not on each loop
626 // 6341374 java/lang/Instrument with -Xcomp
627 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
628 log_circularity_error(name, oldprobe);
629 *throw_circularity_error = true;
630 return NULL;
631 } else {
632 // Wait until the first thread has finished loading this class. Also wait until all the
633 // threads trying to load its superclass have removed their placeholders.
634 while (oldprobe != NULL &&
635 (oldprobe->instance_load_in_progress() || oldprobe->super_load_in_progress())) {
636
637 // We only get here if the application has released the
638 // classloader lock when another thread was in the middle of loading a
639 // superclass/superinterface for this class, and now
640 // this thread is also trying to load this class.
641 // To minimize surprises, the first thread that started to
642 // load a class should be the one to complete the loading
643 // with the classfile it initially expected.
644 // This logic has the current thread wait once it has done
645 // all the superclass/superinterface loading it can, until
646 // the original thread completes the class loading or fails
647 // If it completes we will use the resulting InstanceKlass
648 // which we will find below in the systemDictionary.
649
650 if (lockObject.is_null()) {
651 SystemDictionary_lock->wait();
652 } else if (EnableWaitForParallelLoad) {
653 double_lock_wait(current, lockObject);
654 } else {
655 return NULL;
656 }
657
658 // Check if classloading completed while we were waiting
659 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
660 if (check != NULL) {
661 // Klass is already loaded, so just return it
662 return check;
663 }
664 // check if other thread failed to load and cleaned up
665 oldprobe = PlaceholderTable::get_entry(name, loader_data);
666 }
667 }
668 }
669 return NULL;
670 }
671
672 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
673 assert(event != NULL, "invariant");
674 assert(k != NULL, "invariant");
675 event->set_loadedClass(k);
676 event->set_definingClassLoader(k->class_loader_data());
677 event->set_initiatingClassLoader(init_cld);
678 event->commit();
679 }
680
681 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
682 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
683 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
684 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
685 // This can return NULL, an exception or an InstanceKlass.
686 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
687 Handle class_loader,
688 Handle protection_domain,
689 TRAPS) {
690 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
691 assert(name != NULL && !Signature::is_array(name) &&
692 !Signature::has_envelope(name), "invalid class name: %s", name == NULL ? "NULL" : name->as_C_string());
693
694 EventClassLoad class_load_start_event;
695
696 HandleMark hm(THREAD);
697
698 // Fix for 4474172; see evaluation for more details
699 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
700 ClassLoaderData* loader_data = register_loader(class_loader);
701 Dictionary* dictionary = loader_data->dictionary();
702
703 // Do lookup to see if class already exists and the protection domain
704 // has the right access.
705 // This call uses find which checks protection domain already matches
706 // All subsequent calls use find_class, and set loaded_class so that
707 // before we return a result, we call out to java to check for valid protection domain.
708 InstanceKlass* probe = dictionary->find(THREAD, name, protection_domain);
709 if (probe != NULL) return probe;
710
711 // Non-bootstrap class loaders will call out to class loader and
712 // define via jvm/jni_DefineClass which will acquire the
713 // class loader object lock to protect against multiple threads
714 // defining the class in parallel by accident.
715 // This lock must be acquired here so the waiter will find
716 // any successful result in the SystemDictionary and not attempt
717 // the define.
718 // ParallelCapable class loaders and the bootstrap classloader
719 // do not acquire lock here.
720 Handle lockObject = get_loader_lock_or_null(class_loader);
721 ObjectLocker ol(lockObject, THREAD);
722
723 bool super_load_in_progress = false;
724 InstanceKlass* loaded_class = NULL;
725 Symbol* superclassname = NULL;
726
727 assert(THREAD->can_call_java(),
728 "can not load classes with compiler thread: class=%s, classloader=%s",
729 name->as_C_string(),
730 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
731
732 // Check again (after locking) if the class already exists in SystemDictionary
733 {
734 MutexLocker mu(THREAD, SystemDictionary_lock);
735 InstanceKlass* check = dictionary->find_class(THREAD, name);
736 if (check != NULL) {
737 // InstanceKlass is already loaded, but we still need to check protection domain below.
738 loaded_class = check;
739 } else {
740 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
741 if (placeholder != NULL && placeholder->super_load_in_progress()) {
742 super_load_in_progress = true;
743 superclassname = placeholder->supername();
744 assert(superclassname != NULL, "superclass has to have a name");
745 }
746 }
747 }
748
749 // If the class is in the placeholder table with super_class set,
750 // handle superclass loading in progress.
751 if (super_load_in_progress) {
752 handle_parallel_super_load(name, superclassname,
753 class_loader,
754 protection_domain,
755 CHECK_NULL);
756 }
757
758 bool throw_circularity_error = false;
759 if (loaded_class == NULL) {
760 bool load_placeholder_added = false;
761
762 // Add placeholder entry to record loading instance class
763 // Four cases:
764 // case 1. Bootstrap classloader
765 // This classloader supports parallelism at the classloader level
766 // but only allows a single thread to load a class/classloader pair.
767 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
768 // case 2. parallelCapable user level classloaders
769 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
770 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
771 // case 3. traditional classloaders that rely on the classloader object lock
772 // There should be no need for need for LOAD_INSTANCE, except:
773 // case 4. traditional class loaders that break the classloader object lock
774 // as a legacy deadlock workaround. Detection of this case requires that
775 // this check is done while holding the classloader object lock,
776 // and that lock is still held when calling classloader's loadClass.
777 // For these classloaders, we ensure that the first requestor
778 // completes the load and other requestors wait for completion.
779 {
780 MutexLocker mu(THREAD, SystemDictionary_lock);
781 if (needs_load_placeholder(class_loader)) {
782 loaded_class = handle_parallel_loading(THREAD,
783 name,
784 loader_data,
785 lockObject,
786 &throw_circularity_error);
787 }
788
789 // Recheck if the class has been loaded for all class loader cases and
790 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
791 if (!throw_circularity_error && loaded_class == NULL) {
792 InstanceKlass* check = dictionary->find_class(THREAD, name);
793 if (check != NULL) {
794 loaded_class = check;
795 } else if (needs_load_placeholder(class_loader)) {
796 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread,
797 // and check for ClassCircularityError with -Xcomp.
798 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
799 PlaceholderTable::LOAD_INSTANCE,
800 NULL,
801 THREAD);
802 load_placeholder_added = true;
803 }
804 }
805 }
806
807 // Must throw error outside of owning lock
808 if (throw_circularity_error) {
809 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
810 ResourceMark rm(THREAD);
811 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
812 }
813
814 // Be careful when modifying this code: once you have run
815 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
816 // you need to find_and_remove it before returning.
817 // So be careful to not exit with a CHECK_ macro between these calls.
818
819 if (loaded_class == NULL) {
820 // Do actual loading
821 loaded_class = load_instance_class(name, class_loader, THREAD);
822 }
823
824 if (load_placeholder_added) {
825 // clean up placeholder entries for LOAD_INSTANCE success or error
826 // This brackets the SystemDictionary updates for both defining
827 // and initiating loaders
828 MutexLocker mu(THREAD, SystemDictionary_lock);
829 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
830 SystemDictionary_lock->notify_all();
831 }
832 }
833
834 if (HAS_PENDING_EXCEPTION || loaded_class == NULL) {
835 return NULL;
836 }
837
838 if (class_load_start_event.should_commit()) {
839 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
840 }
841
842 // Make sure we have the right class in the dictionary
843 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
844
845 // Check if the protection domain is present it has the right access
846 if (protection_domain() != NULL) {
847 // Verify protection domain. If it fails an exception is thrown
848 dictionary->validate_protection_domain(loaded_class, class_loader, protection_domain, CHECK_NULL);
849 }
850
851 return loaded_class;
852 }
853
854
855 // This routine does not lock the system dictionary.
856 //
857 // Since readers don't hold a lock, we must make sure that system
858 // dictionary entries are added to in a safe way (all links must
859 // be updated in an MT-safe manner). All entries are removed during class
860 // unloading, when this class loader is no longer referenced.
861 //
862 // Callers should be aware that an entry could be added just after
863 // Dictionary is read here, so the caller will not see
864 // the new entry.
865
866 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
867 Symbol* class_name,
868 Handle class_loader,
869 Handle protection_domain) {
870
871 // The result of this call should be consistent with the result
872 // of the call to resolve_instance_class_or_null().
873 // See evaluation 6790209 and 4474172 for more details.
874 oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
875 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
876
877 if (loader_data == NULL) {
878 // If the ClassLoaderData has not been setup,
879 // then the class loader has no entries in the dictionary.
880 return NULL;
881 }
882
883 Dictionary* dictionary = loader_data->dictionary();
884 return dictionary->find(current, class_name, protection_domain);
885 }
886
887 // Look for a loaded instance or array klass by name. Do not do any loading.
888 // return NULL in case of error.
889 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
890 Symbol* class_name,
891 Handle class_loader,
892 Handle protection_domain) {
893 Klass* k = NULL;
894 assert(class_name != NULL, "class name must be non NULL");
895
896 if (Signature::is_array(class_name)) {
897 // The name refers to an array. Parse the name.
898 // dimension and object_key in FieldArrayInfo are assigned as a
899 // side-effect of this call
900 SignatureStream ss(class_name, false);
901 int ndims = ss.skip_array_prefix(); // skip all '['s
902 BasicType t = ss.type();
903 if (t != T_OBJECT && t != T_PRIMITIVE_OBJECT) {
904 k = Universe::typeArrayKlassObj(t);
905 } else {
906 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader, protection_domain);
907 }
908 if (k != NULL) {
909 if (class_name->is_Q_array_signature()) {
910 k = InlineKlass::cast(k)->value_array_klass_or_null(ndims);
911 } else {
912 k = k->array_klass_or_null(ndims);
913 }
914 }
915 } else {
916 k = find_instance_klass(current, class_name, class_loader, protection_domain);
917 }
918 return k;
919 }
920
921 // Note: this method is much like resolve_class_from_stream, but
922 // does not publish the classes in the SystemDictionary.
923 // Handles Lookup.defineClass hidden.
924 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
925 ClassFileStream* st,
926 Symbol* class_name,
927 Handle class_loader,
928 const ClassLoadInfo& cl_info,
929 TRAPS) {
930
931 EventClassLoad class_load_start_event;
932 ClassLoaderData* loader_data;
933
934 // - for hidden classes that are not strong: create a new CLD that has a class holder and
935 // whose loader is the Lookup class's loader.
936 // - for hidden class: add the class to the Lookup class's loader's CLD.
937 assert (cl_info.is_hidden(), "only used for hidden classes");
938 bool create_mirror_cld = !cl_info.is_strong_hidden();
939 loader_data = register_loader(class_loader, create_mirror_cld);
940
941 assert(st != NULL, "invariant");
942 assert(st->need_verify(), "invariant");
943
944 // Parse stream and create a klass.
945 InstanceKlass* k = KlassFactory::create_from_stream(st,
946 class_name,
947 loader_data,
948 cl_info,
949 CHECK_NULL);
950 assert(k != NULL, "no klass created");
951
952 // Hidden classes that are not strong must update ClassLoaderData holder
953 // so that they can be unloaded when the mirror is no longer referenced.
954 if (!cl_info.is_strong_hidden()) {
955 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
956 }
957
958 {
959 MutexLocker mu_r(THREAD, Compile_lock);
960 // Add to class hierarchy, and do possible deoptimizations.
961 add_to_hierarchy(k);
962 // But, do not add to dictionary.
963 }
964
965 k->link_class(CHECK_NULL);
966
967 // notify jvmti
968 if (JvmtiExport::should_post_class_load()) {
969 JvmtiExport::post_class_load(THREAD, k);
970 }
971 if (class_load_start_event.should_commit()) {
972 post_class_load_event(&class_load_start_event, k, loader_data);
973 }
974
975 return k;
976 }
977
978 // Add a klass to the system from a stream (called by jni_DefineClass and
979 // JVM_DefineClass).
980 // Note: class_name can be NULL. In that case we do not know the name of
981 // the class until we have parsed the stream.
982 // This function either returns an InstanceKlass or throws an exception. It does
983 // not return NULL without a pending exception.
984 InstanceKlass* SystemDictionary::resolve_class_from_stream(
985 ClassFileStream* st,
986 Symbol* class_name,
987 Handle class_loader,
988 const ClassLoadInfo& cl_info,
989 TRAPS) {
990
991 HandleMark hm(THREAD);
992
993 ClassLoaderData* loader_data = register_loader(class_loader);
994
995 // Classloaders that support parallelism, e.g. bootstrap classloader,
996 // do not acquire lock here
997 Handle lockObject = get_loader_lock_or_null(class_loader);
998 ObjectLocker ol(lockObject, THREAD);
999
1000 // Parse the stream and create a klass.
1001 // Note that we do this even though this klass might
1002 // already be present in the SystemDictionary, otherwise we would not
1003 // throw potential ClassFormatErrors.
1004 InstanceKlass* k = NULL;
1005
1006 #if INCLUDE_CDS
1007 if (!DumpSharedSpaces) {
1008 k = SystemDictionaryShared::lookup_from_stream(class_name,
1009 class_loader,
1010 cl_info.protection_domain(),
1011 st,
1012 CHECK_NULL);
1013 }
1014 #endif
1015
1016 if (k == NULL) {
1017 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
1018 }
1019
1020 assert(k != NULL, "no klass created");
1021 Symbol* h_name = k->name();
1022 assert(class_name == NULL || class_name == h_name, "name mismatch");
1023
1024 // Add class just loaded
1025 // If a class loader supports parallel classloading, handle parallel define requests.
1026 // find_or_define_instance_class may return a different InstanceKlass,
1027 // in which case the old k would be deallocated
1028 if (is_parallelCapable(class_loader)) {
1029 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
1030 } else {
1031 define_instance_class(k, class_loader, THREAD);
1032
1033 // If defining the class throws an exception register 'k' for cleanup.
1034 if (HAS_PENDING_EXCEPTION) {
1035 assert(k != NULL, "Must have an instance klass here!");
1036 loader_data->add_to_deallocate_list(k);
1037 return NULL;
1038 }
1039 }
1040
1041 // Make sure we have an entry in the SystemDictionary on success
1042 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
1043
1044 return k;
1045 }
1046
1047 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
1048 Symbol* class_name,
1049 Handle class_loader,
1050 const ClassLoadInfo& cl_info,
1051 TRAPS) {
1052 if (cl_info.is_hidden()) {
1053 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
1054 } else {
1055 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
1056 }
1057 }
1058
1059
1060 #if INCLUDE_CDS
1061 // Check if a shared class can be loaded by the specific classloader.
1062 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1063 InstanceKlass* ik,
1064 PackageEntry* pkg_entry,
1065 Handle class_loader) {
1066 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1067 "Cannot use sharing if java.base is patched");
1068
1069 // (1) Check if we are loading into the same loader as in dump time.
1070
1071 if (ik->is_shared_boot_class()) {
1072 if (class_loader() != NULL) {
1073 return false;
1074 }
1075 } else if (ik->is_shared_platform_class()) {
1076 if (class_loader() != java_platform_loader()) {
1077 return false;
1078 }
1079 } else if (ik->is_shared_app_class()) {
1080 if (class_loader() != java_system_loader()) {
1081 return false;
1082 }
1083 } else {
1084 // ik was loaded by a custom loader during dump time
1085 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
1086 return false;
1087 } else {
1088 return true;
1089 }
1090 }
1091
1092 // (2) Check if we are loading into the same module from the same location as in dump time.
1093
1094 if (MetaspaceShared::use_optimized_module_handling()) {
1095 // Class visibility has not changed between dump time and run time, so a class
1096 // that was visible (and thus archived) during dump time is always visible during runtime.
1097 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
1098 "visibility cannot change between dump time and runtime");
1099 return true;
1100 }
1101 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
1102 }
1103
1104 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
1105 InstanceKlass* ik,
1106 PackageEntry* pkg_entry,
1107 Handle class_loader) {
1108 int scp_index = ik->shared_classpath_index();
1109 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
1110 assert(scp_index >= 0, "must be");
1111 SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
1112 if (!Universe::is_module_initialized()) {
1113 assert(scp_entry != NULL, "must be");
1114 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
1115 // has restricted the classes can be loaded at this step to be only:
1116 // [1] scp_entry->is_modules_image(): classes in java.base, or,
1117 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
1118 assert(scp_entry->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
1119 "only these classes can be loaded before the module system is initialized");
1120 assert(class_loader.is_null(), "sanity");
1121 return true;
1122 }
1123
1124 if (pkg_entry == NULL) {
1125 // We might have looked up pkg_entry before the module system was initialized.
1126 // Need to reload it now.
1127 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1128 if (pkg_name != NULL) {
1129 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1130 }
1131 }
1132
1133 ModuleEntry* mod_entry = (pkg_entry == NULL) ? NULL : pkg_entry->module();
1134 bool should_be_in_named_module = (mod_entry != NULL && mod_entry->is_named());
1135 bool was_archived_from_named_module = scp_entry->in_named_module();
1136 bool visible;
1137
1138 if (was_archived_from_named_module) {
1139 if (should_be_in_named_module) {
1140 // Is the module loaded from the same location as during dump time?
1141 visible = mod_entry->shared_path_index() == scp_index;
1142 if (visible) {
1143 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1144 }
1145 } else {
1146 // During dump time, this class was in a named module, but at run time, this class should be
1147 // in an unnamed module.
1148 visible = false;
1149 }
1150 } else {
1151 if (should_be_in_named_module) {
1152 // During dump time, this class was in an unnamed, but at run time, this class should be
1153 // in a named module.
1154 visible = false;
1155 } else {
1156 visible = true;
1157 }
1158 }
1159
1160 return visible;
1161 }
1162
1163 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1164 Handle class_loader, Handle protection_domain,
1165 bool is_superclass, TRAPS) {
1166 assert(super_type->is_shared(), "must be");
1167
1168 // Quick check if the super type has been already loaded.
1169 // + Don't do it for unregistered classes -- they can be unloaded so
1170 // super_type->class_loader_data() could be stale.
1171 // + Don't check if loader data is NULL, ie. the super_type isn't fully loaded.
1172 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != NULL) {
1173 // Check if the superclass is loaded by the current class_loader
1174 Symbol* name = super_type->name();
1175 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader, protection_domain);
1176 if (check == super_type) {
1177 return true;
1178 }
1179 }
1180
1181 Klass *found = resolve_super_or_fail(klass->name(), super_type->name(),
1182 class_loader, protection_domain, is_superclass, CHECK_0);
1183 if (found == super_type) {
1184 return true;
1185 } else {
1186 // The dynamically resolved super type is not the same as the one we used during dump time,
1187 // so we cannot use the class.
1188 return false;
1189 }
1190 }
1191
1192 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1193 Handle protection_domain, TRAPS) {
1194 // Check the superclass and interfaces. They must be the same
1195 // as in dump time, because the layout of <ik> depends on
1196 // the specific layout of ik->super() and ik->local_interfaces().
1197 //
1198 // If unexpected superclass or interfaces are found, we cannot
1199 // load <ik> from the shared archive.
1200
1201 if (ik->super() != NULL &&
1202 !check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1203 class_loader, protection_domain, true, THREAD)) {
1204 return false;
1205 }
1206
1207 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1208 int num_interfaces = interfaces->length();
1209 for (int index = 0; index < num_interfaces; index++) {
1210 if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) {
1211 return false;
1212 }
1213 }
1214
1215 return true;
1216 }
1217
1218 InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1219 Handle class_loader,
1220 Handle protection_domain,
1221 PackageEntry* pkg_entry,
1222 TRAPS) {
1223 InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1224 assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1225 Symbol* cn = shared_nest_host->name();
1226 Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1227 if (s != shared_nest_host) {
1228 // The dynamically resolved nest_host is not the same as the one we used during dump time,
1229 // so we cannot use ik.
1230 return NULL;
1231 } else {
1232 assert(s->is_shared(), "must be");
1233 }
1234
1235 InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, NULL, pkg_entry, CHECK_NULL);
1236
1237 if (loaded_ik != NULL) {
1238 assert(shared_nest_host->is_same_class_package(ik),
1239 "lambda proxy class and its nest host must be in the same package");
1240 }
1241
1242 // The lambda proxy class and its nest host have the same class loader and class loader data,
1243 // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1244 assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1245 assert(shared_nest_host->class_loader_data() == class_loader_data(class_loader), "mismatched class loader data");
1246 ik->set_nest_host(shared_nest_host);
1247
1248 return loaded_ik;
1249 }
1250
1251 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1252 Handle class_loader,
1253 Handle protection_domain,
1254 const ClassFileStream *cfs,
1255 PackageEntry* pkg_entry,
1256 TRAPS) {
1257 assert(ik != NULL, "sanity");
1258 assert(!ik->is_unshareable_info_restored(), "shared class can be loaded only once");
1259 Symbol* class_name = ik->name();
1260
1261 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1262 return NULL;
1263 }
1264
1265 if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {
1266 return NULL;
1267 }
1268
1269
1270 if (ik->has_inline_type_fields()) {
1271 for (AllFieldStream fs(ik->fields(), ik->constants()); !fs.done(); fs.next()) {
1272 if (Signature::basic_type(fs.signature()) == T_PRIMITIVE_OBJECT) {
1273 if (!fs.access_flags().is_static()) {
1274 // Pre-load inline class
1275 Klass* real_k = SystemDictionary::resolve_inline_type_field_or_fail(&fs,
1276 class_loader, protection_domain, true, CHECK_NULL);
1277 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index());
1278 if (real_k != k) {
1279 // oops, the app has substituted a different version of k!
1280 return NULL;
1281 }
1282 }
1283 }
1284 }
1285 }
1286
1287 InstanceKlass* new_ik = NULL;
1288 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1289 // It will be skipped for shared VM hidden lambda proxy classes.
1290 if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1291 new_ik = KlassFactory::check_shared_class_file_load_hook(
1292 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1293 }
1294 if (new_ik != NULL) {
1295 // The class is changed by CFLH. Return the new class. The shared class is
1296 // not used.
1297 return new_ik;
1298 }
1299
1300 // Adjust methods to recover missing data. They need addresses for
1301 // interpreter entry points and their default native method address
1302 // must be reset.
1303
1304 // Shared classes are all currently loaded by either the bootstrap or
1305 // internal parallel class loaders, so this will never cause a deadlock
1306 // on a custom class loader lock.
1307 // Since this class is already locked with parallel capable class
1308 // loaders, including the bootstrap loader via the placeholder table,
1309 // this lock is currently a nop.
1310
1311 ClassLoaderData* loader_data = class_loader_data(class_loader);
1312 {
1313 HandleMark hm(THREAD);
1314 Handle lockObject = get_loader_lock_or_null(class_loader);
1315 ObjectLocker ol(lockObject, THREAD);
1316 // prohibited package check assumes all classes loaded from archive call
1317 // restore_unshareable_info which calls ik->set_package()
1318 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1319 }
1320
1321 load_shared_class_misc(ik, loader_data);
1322
1323 return ik;
1324 }
1325
1326 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1327 ik->print_class_load_logging(loader_data, NULL, NULL);
1328
1329 // For boot loader, ensure that GetSystemPackage knows that a class in this
1330 // package was loaded.
1331 if (loader_data->is_the_null_class_loader_data()) {
1332 int path_index = ik->shared_classpath_index();
1333 ik->set_classpath_index(path_index);
1334 }
1335
1336 // notify a class loaded from shared object
1337 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1338 }
1339
1340 #endif // INCLUDE_CDS
1341
1342 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1343
1344 if (class_loader.is_null()) {
1345 ResourceMark rm(THREAD);
1346 PackageEntry* pkg_entry = NULL;
1347 bool search_only_bootloader_append = false;
1348
1349 // Find the package in the boot loader's package entry table.
1350 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1351 if (pkg_name != NULL) {
1352 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1353 }
1354
1355 // Prior to attempting to load the class, enforce the boot loader's
1356 // visibility boundaries.
1357 if (!Universe::is_module_initialized()) {
1358 // During bootstrapping, prior to module initialization, any
1359 // class attempting to be loaded must be checked against the
1360 // java.base packages in the boot loader's PackageEntryTable.
1361 // No class outside of java.base is allowed to be loaded during
1362 // this bootstrapping window.
1363 if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1364 // Class is either in the unnamed package or in
1365 // a named package within the unnamed module. Either
1366 // case is outside of java.base, do not attempt to
1367 // load the class post java.base definition. If
1368 // java.base has not been defined, let the class load
1369 // and its package will be checked later by
1370 // ModuleEntryTable::verify_javabase_packages.
1371 if (ModuleEntryTable::javabase_defined()) {
1372 return NULL;
1373 }
1374 } else {
1375 // Check that the class' package is defined within java.base.
1376 ModuleEntry* mod_entry = pkg_entry->module();
1377 Symbol* mod_entry_name = mod_entry->name();
1378 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1379 return NULL;
1380 }
1381 }
1382 } else {
1383 // After the module system has been initialized, check if the class'
1384 // package is in a module defined to the boot loader.
1385 if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1386 // Class is either in the unnamed package, in a named package
1387 // within a module not defined to the boot loader or in a
1388 // a named package within the unnamed module. In all cases,
1389 // limit visibility to search for the class only in the boot
1390 // loader's append path.
1391 if (!ClassLoader::has_bootclasspath_append()) {
1392 // If there is no bootclasspath append entry, no need to continue
1393 // searching.
1394 return NULL;
1395 }
1396 search_only_bootloader_append = true;
1397 }
1398 }
1399
1400 // Prior to bootstrapping's module initialization, never load a class outside
1401 // of the boot loader's module path
1402 assert(Universe::is_module_initialized() ||
1403 !search_only_bootloader_append,
1404 "Attempt to load a class outside of boot loader's module path");
1405
1406 // Search for classes in the CDS archive.
1407 InstanceKlass* k = NULL;
1408
1409 #if INCLUDE_CDS
1410 if (UseSharedSpaces)
1411 {
1412 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1413 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1414 if (ik != NULL && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1415 SharedClassLoadingMark slm(THREAD, ik);
1416 k = load_shared_class(ik, class_loader, Handle(), NULL, pkg_entry, CHECK_NULL);
1417 }
1418 }
1419 #endif
1420
1421 if (k == NULL) {
1422 // Use VM class loader
1423 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1424 k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1425 }
1426
1427 // find_or_define_instance_class may return a different InstanceKlass
1428 if (k != NULL) {
1429 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1430 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1431 }
1432 return k;
1433 } else {
1434 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1435 ResourceMark rm(THREAD);
1436
1437 JavaThread* jt = THREAD;
1438
1439 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1440 ClassLoader::perf_app_classload_selftime(),
1441 ClassLoader::perf_app_classload_count(),
1442 jt->get_thread_stat()->perf_recursion_counts_addr(),
1443 jt->get_thread_stat()->perf_timers_addr(),
1444 PerfClassTraceTime::CLASS_LOAD);
1445
1446 // Translate to external class name format, i.e., convert '/' chars to '.'
1447 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1448
1449 JavaValue result(T_OBJECT);
1450
1451 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1452
1453 // Call public unsynchronized loadClass(String) directly for all class loaders.
1454 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1455 // acquire a class-name based lock rather than the class loader object lock.
1456 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1457 JavaCalls::call_virtual(&result,
1458 class_loader,
1459 spec_klass,
1460 vmSymbols::loadClass_name(),
1461 vmSymbols::string_class_signature(),
1462 string,
1463 CHECK_NULL);
1464
1465 assert(result.get_type() == T_OBJECT, "just checking");
1466 oop obj = result.get_oop();
1467
1468 // Primitive classes return null since forName() can not be
1469 // used to obtain any of the Class objects representing primitives or void
1470 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1471 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1472 // For user defined Java class loaders, check that the name returned is
1473 // the same as that requested. This check is done for the bootstrap
1474 // loader when parsing the class file.
1475 if (class_name == k->name()) {
1476 return k;
1477 }
1478 }
1479 // Class is not found or has the wrong name, return NULL
1480 return NULL;
1481 }
1482 }
1483
1484 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1485 Handle class_loader,
1486 TRAPS) {
1487
1488 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1489
1490 // If everything was OK (no exceptions, no null return value), and
1491 // class_loader is NOT the defining loader, do a little more bookkeeping.
1492 if (loaded_class != NULL &&
1493 loaded_class->class_loader() != class_loader()) {
1494
1495 ClassLoaderData* loader_data = class_loader_data(class_loader);
1496 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1497
1498 // Record dependency for non-parent delegation.
1499 // This recording keeps the defining class loader of the klass (loaded_class) found
1500 // from being unloaded while the initiating class loader is loaded
1501 // even if the reference to the defining class loader is dropped
1502 // before references to the initiating class loader.
1503 loader_data->record_dependency(loaded_class);
1504
1505 { // Grabbing the Compile_lock prevents systemDictionary updates
1506 // during compilations.
1507 MutexLocker mu(THREAD, Compile_lock);
1508 update_dictionary(THREAD, loaded_class, loader_data);
1509 }
1510
1511 if (JvmtiExport::should_post_class_load()) {
1512 JvmtiExport::post_class_load(THREAD, loaded_class);
1513 }
1514 }
1515 return loaded_class;
1516 }
1517
1518 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1519 EventClassDefine event;
1520 if (event.should_commit()) {
1521 event.set_definedClass(k);
1522 event.set_definingClassLoader(def_cld);
1523 event.commit();
1524 }
1525 }
1526
1527 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1528
1529 ClassLoaderData* loader_data = k->class_loader_data();
1530 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1531
1532 // Bootstrap and other parallel classloaders don't acquire a lock,
1533 // they use placeholder token.
1534 // If a parallelCapable class loader calls define_instance_class instead of
1535 // find_or_define_instance_class to get here, we have a timing
1536 // hole with systemDictionary updates and check_constraints
1537 if (!is_parallelCapable(class_loader)) {
1538 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1539 get_loader_lock_or_null(class_loader)),
1540 "define called without lock");
1541 }
1542
1543 // Check class-loading constraints. Throw exception if violation is detected.
1544 // Grabs and releases SystemDictionary_lock
1545 // The check_constraints/find_class call and update_dictionary sequence
1546 // must be "atomic" for a specific class/classloader pair so we never
1547 // define two different instanceKlasses for that class/classloader pair.
1548 // Existing classloaders will call define_instance_class with the
1549 // classloader lock held
1550 // Parallel classloaders will call find_or_define_instance_class
1551 // which will require a token to perform the define class
1552 check_constraints(k, loader_data, true, CHECK);
1553
1554 // Register class just loaded with class loader (placed in ArrayList)
1555 // Note we do this before updating the dictionary, as this can
1556 // fail with an OutOfMemoryError (if it does, we will *not* put this
1557 // class in the dictionary and will not update the class hierarchy).
1558 // JVMTI FollowReferences needs to find the classes this way.
1559 if (k->class_loader() != NULL) {
1560 methodHandle m(THREAD, Universe::loader_addClass_method());
1561 JavaValue result(T_VOID);
1562 JavaCallArguments args(class_loader);
1563 args.push_oop(Handle(THREAD, k->java_mirror()));
1564 JavaCalls::call(&result, m, &args, CHECK);
1565 }
1566
1567 // Add the new class. We need recompile lock during update of CHA.
1568 {
1569 MutexLocker mu_r(THREAD, Compile_lock);
1570
1571 // Add to class hierarchy, and do possible deoptimizations.
1572 add_to_hierarchy(k);
1573
1574 // Add to systemDictionary - so other classes can see it.
1575 // Grabs and releases SystemDictionary_lock
1576 update_dictionary(THREAD, k, loader_data);
1577 }
1578
1579 // notify jvmti
1580 if (JvmtiExport::should_post_class_load()) {
1581 JvmtiExport::post_class_load(THREAD, k);
1582 }
1583 post_class_define_event(k, loader_data);
1584 }
1585
1586 // Support parallel classloading
1587 // All parallel class loaders, including bootstrap classloader
1588 // lock a placeholder entry for this class/class_loader pair
1589 // to allow parallel defines of different classes for this class loader
1590 // With AllowParallelDefine flag==true, in case they do not synchronize around
1591 // FindLoadedClass/DefineClass, calls, we check for parallel
1592 // loading for them, wait if a defineClass is in progress
1593 // and return the initial requestor's results
1594 // This flag does not apply to the bootstrap classloader.
1595 // With AllowParallelDefine flag==false, call through to define_instance_class
1596 // which will throw LinkageError: duplicate class definition.
1597 // False is the requested default.
1598 // For better performance, the class loaders should synchronize
1599 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1600 // potentially waste time reading and parsing the bytestream.
1601 // Note: VM callers should ensure consistency of k/class_name,class_loader
1602 // Be careful when modifying this code: once you have run
1603 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1604 // you need to find_and_remove it before returning.
1605 // So be careful to not exit with a CHECK_ macro between these calls.
1606 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1607 InstanceKlass* k, TRAPS) {
1608
1609 Symbol* name_h = k->name();
1610 ClassLoaderData* loader_data = class_loader_data(class_loader);
1611 Dictionary* dictionary = loader_data->dictionary();
1612
1613 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1614 {
1615 MutexLocker mu(THREAD, SystemDictionary_lock);
1616 // First check if class already defined
1617 if (is_parallelDefine(class_loader)) {
1618 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1619 if (check != NULL) {
1620 return check;
1621 }
1622 }
1623
1624 // Acquire define token for this class/classloader
1625 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1626 PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1627 // Wait if another thread defining in parallel
1628 // All threads wait - even those that will throw duplicate class: otherwise
1629 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1630 // if other thread has not finished updating dictionary
1631 while (probe->definer() != NULL) {
1632 SystemDictionary_lock->wait();
1633 }
1634 // Only special cases allow parallel defines and can use other thread's results
1635 // Other cases fall through, and may run into duplicate defines
1636 // caught by finding an entry in the SystemDictionary
1637 if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1638 InstanceKlass* ik = probe->instance_klass();
1639 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1640 SystemDictionary_lock->notify_all();
1641 #ifdef ASSERT
1642 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1643 assert(check != NULL, "definer missed recording success");
1644 #endif
1645 return ik;
1646 } else {
1647 // This thread will define the class (even if earlier thread tried and had an error)
1648 probe->set_definer(THREAD);
1649 }
1650 }
1651
1652 define_instance_class(k, class_loader, THREAD);
1653
1654 // definer must notify any waiting threads
1655 {
1656 MutexLocker mu(THREAD, SystemDictionary_lock);
1657 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1658 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1659 if (!HAS_PENDING_EXCEPTION) {
1660 probe->set_instance_klass(k);
1661 }
1662 probe->set_definer(NULL);
1663 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1664 SystemDictionary_lock->notify_all();
1665 }
1666
1667 return HAS_PENDING_EXCEPTION ? NULL : k;
1668 }
1669
1670 // If a class loader supports parallel classloading handle parallel define requests.
1671 // find_or_define_instance_class may return a different InstanceKlass
1672 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1673 InstanceKlass* k, TRAPS) {
1674 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1675 // Clean up original InstanceKlass if duplicate or error
1676 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1677 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1678 assert(defined_k != NULL, "Should have a klass if there's no exception");
1679 k->class_loader_data()->add_to_deallocate_list(k);
1680 } else if (HAS_PENDING_EXCEPTION) {
1681 assert(defined_k == NULL, "Should not have a klass if there's an exception");
1682 k->class_loader_data()->add_to_deallocate_list(k);
1683 }
1684 return defined_k;
1685 }
1686
1687
1688 // ----------------------------------------------------------------------------
1689 // Update hierarchy. This is done before the new klass has been added to the SystemDictionary. The Compile_lock
1690 // is held, to ensure that the compiler is not using the class hierarchy, and that deoptimization will kick in
1691 // before a new class is used.
1692
1693 void SystemDictionary::add_to_hierarchy(InstanceKlass* k) {
1694 assert(k != NULL, "just checking");
1695 if (Universe::is_fully_initialized()) {
1696 assert_locked_or_safepoint(Compile_lock);
1697 }
1698
1699 k->set_init_state(InstanceKlass::loaded);
1700 // make sure init_state store is already done.
1701 // The compiler reads the hierarchy outside of the Compile_lock.
1702 // Access ordering is used to add to hierarchy.
1703
1704 // Link into hierarchy.
1705 k->append_to_sibling_list(); // add to superklass/sibling list
1706 k->process_interfaces(); // handle all "implements" declarations
1707
1708 // Now flush all code that depended on old class hierarchy.
1709 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1710 if (Universe::is_fully_initialized()) {
1711 CodeCache::flush_dependents_on(k);
1712 }
1713 }
1714
1715 // ----------------------------------------------------------------------------
1716 // GC support
1717
1718 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1719 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1720
1721 bool unloading_occurred;
1722 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1723 {
1724 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1725 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1726 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1727 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1728 if (unloading_occurred) {
1729 MutexLocker ml2(is_concurrent ? Module_lock : NULL);
1730 JFR_ONLY(Jfr::on_unloading_classes();)
1731 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1732 MutexLocker ml1(is_concurrent ? SystemDictionary_lock : NULL);
1733 ClassLoaderDataGraph::clean_module_and_package_info();
1734 LoaderConstraintTable::purge_loader_constraints();
1735 ResolutionErrorTable::purge_resolution_errors();
1736 }
1737 }
1738
1739 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1740
1741 if (unloading_occurred) {
1742 SymbolTable::trigger_cleanup();
1743
1744 if (java_lang_System::allow_security_manager()) {
1745 // Oops referenced by the protection domain cache table may get unreachable independently
1746 // of the class loader (eg. cached protection domain oops). So we need to
1747 // explicitly unlink them here.
1748 // All protection domain oops are linked to the caller class, so if nothing
1749 // unloads, this is not needed.
1750 ProtectionDomainCacheTable::trigger_cleanup();
1751 } else {
1752 assert(ProtectionDomainCacheTable::number_of_entries() == 0, "should be empty");
1753 }
1754
1755 MutexLocker ml(is_concurrent ? ClassInitError_lock : NULL);
1756 InstanceKlass::clean_initialization_error_table();
1757 }
1758
1759 return unloading_occurred;
1760 }
1761
1762 void SystemDictionary::methods_do(void f(Method*)) {
1763 // Walk methods in loaded classes
1764
1765 {
1766 MutexLocker ml(ClassLoaderDataGraph_lock);
1767 ClassLoaderDataGraph::methods_do(f);
1768 }
1769
1770 auto doit = [&] (InvokeMethodKey key, Method* method) {
1771 f(method);
1772 };
1773
1774 {
1775 MutexLocker ml(InvokeMethodTable_lock);
1776 _invoke_method_intrinsic_table.iterate_all(doit);
1777 }
1778
1779 }
1780
1781 // ----------------------------------------------------------------------------
1782 // Initialization
1783
1784 void SystemDictionary::initialize(TRAPS) {
1785 #if INCLUDE_CDS
1786 SystemDictionaryShared::initialize();
1787 #endif
1788
1789 // Resolve basic classes
1790 vmClasses::resolve_all(CHECK);
1791 // Resolve classes used by archived heap objects
1792 if (UseSharedSpaces) {
1793 HeapShared::resolve_classes(THREAD);
1794 }
1795 }
1796
1797 // Constraints on class loaders. The details of the algorithm can be
1798 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1799 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1800 // that the dictionary needs to maintain a set of constraints that
1801 // must be satisfied by all classes in the dictionary.
1802 // if defining is true, then LinkageError if already in dictionary
1803 // if initiating loader, then ok if InstanceKlass matches existing entry
1804
1805 void SystemDictionary::check_constraints(InstanceKlass* k,
1806 ClassLoaderData* loader_data,
1807 bool defining,
1808 TRAPS) {
1809 ResourceMark rm(THREAD);
1810 stringStream ss;
1811 bool throwException = false;
1812
1813 {
1814 Symbol* name = k->name();
1815
1816 MutexLocker mu(THREAD, SystemDictionary_lock);
1817
1818 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1819 if (check != NULL) {
1820 // If different InstanceKlass - duplicate class definition,
1821 // else - ok, class loaded by a different thread in parallel.
1822 // We should only have found it if it was done loading and ok to use.
1823
1824 if ((defining == true) || (k != check)) {
1825 throwException = true;
1826 ss.print("loader %s", loader_data->loader_name_and_id());
1827 ss.print(" attempted duplicate %s definition for %s. (%s)",
1828 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1829 } else {
1830 return;
1831 }
1832 }
1833
1834 if (throwException == false) {
1835 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1836 throwException = true;
1837 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1838 ss.print(" wants to load %s %s.",
1839 k->external_kind(), k->external_name());
1840 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1841 if (existing_klass != NULL && existing_klass->class_loader_data() != loader_data) {
1842 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1843 existing_klass->external_kind(),
1844 existing_klass->class_loader_data()->loader_name_and_id(),
1845 existing_klass->class_in_module_of_loader(false, true));
1846 } else {
1847 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1848 }
1849 }
1850 }
1851 }
1852
1853 // Throw error now if needed (cannot throw while holding
1854 // SystemDictionary_lock because of rank ordering)
1855 if (throwException == true) {
1856 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1857 }
1858 }
1859
1860 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1861 // have been called.
1862 void SystemDictionary::update_dictionary(JavaThread* current,
1863 InstanceKlass* k,
1864 ClassLoaderData* loader_data) {
1865 // Compile_lock prevents systemDictionary updates during compilations
1866 assert_locked_or_safepoint(Compile_lock);
1867 Symbol* name = k->name();
1868
1869 MutexLocker mu1(SystemDictionary_lock);
1870
1871 // Make a new dictionary entry.
1872 Dictionary* dictionary = loader_data->dictionary();
1873 InstanceKlass* sd_check = dictionary->find_class(current, name);
1874 if (sd_check == NULL) {
1875 dictionary->add_klass(current, name, k);
1876 }
1877 SystemDictionary_lock->notify_all();
1878 }
1879
1880
1881 // Try to find a class name using the loader constraints. The
1882 // loader constraints might know about a class that isn't fully loaded
1883 // yet and these will be ignored.
1884 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1885 Thread* current, Symbol* class_name, Handle class_loader) {
1886
1887 // First see if it has been loaded directly.
1888 // Force the protection domain to be null. (This removes protection checks.)
1889 Handle no_protection_domain;
1890 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader,
1891 no_protection_domain);
1892 if (klass != NULL)
1893 return klass;
1894
1895 // Now look to see if it has been loaded elsewhere, and is subject to
1896 // a loader constraint that would require this loader to return the
1897 // klass that is already loaded.
1898 if (Signature::is_array(class_name)) {
1899 // For array classes, their Klass*s are not kept in the
1900 // constraint table. The element Klass*s are.
1901 SignatureStream ss(class_name, false);
1902 int ndims = ss.skip_array_prefix(); // skip all '['s
1903 BasicType t = ss.type();
1904 if (t != T_OBJECT && t != T_PRIMITIVE_OBJECT) {
1905 klass = Universe::typeArrayKlassObj(t);
1906 } else {
1907 MutexLocker mu(current, SystemDictionary_lock);
1908 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1909 }
1910 // If element class already loaded, allocate array klass
1911 if (klass != NULL) {
1912 if (class_name->is_Q_array_signature()) {
1913 klass = InlineKlass::cast(klass)->value_array_klass_or_null(ndims);
1914 } else {
1915 klass = klass->array_klass_or_null(ndims);
1916 }
1917 }
1918 } else {
1919 MutexLocker mu(current, SystemDictionary_lock);
1920 // Non-array classes are easy: simply check the constraint table.
1921 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1922 }
1923
1924 return klass;
1925 }
1926
1927 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1928 Klass* klass_being_linked,
1929 Handle class_loader1,
1930 Handle class_loader2) {
1931 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1932 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1933
1934 Symbol* constraint_name = NULL;
1935
1936 if (!Signature::is_array(class_name)) {
1937 constraint_name = class_name;
1938 } else {
1939 // For array classes, their Klass*s are not kept in the
1940 // constraint table. The element classes are.
1941 SignatureStream ss(class_name, false);
1942 ss.skip_array_prefix(); // skip all '['s
1943 if (!ss.has_envelope()) {
1944 return true; // primitive types always pass
1945 }
1946 constraint_name = ss.as_symbol();
1947 // Increment refcount to keep constraint_name alive after
1948 // SignatureStream is destructed. It will be decremented below
1949 // before returning.
1950 constraint_name->increment_refcount();
1951 }
1952
1953 Dictionary* dictionary1 = loader_data1->dictionary();
1954 Dictionary* dictionary2 = loader_data2->dictionary();
1955
1956 JavaThread* current = JavaThread::current();
1957 {
1958 MutexLocker mu_s(SystemDictionary_lock);
1959 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1960 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1961 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1962 klass2, loader_data2);
1963 #if INCLUDE_CDS
1964 if (Arguments::is_dumping_archive() && klass_being_linked != NULL &&
1965 !klass_being_linked->is_shared()) {
1966 SystemDictionaryShared::record_linking_constraint(constraint_name,
1967 InstanceKlass::cast(klass_being_linked),
1968 class_loader1, class_loader2);
1969 }
1970 #endif // INCLUDE_CDS
1971 if (Signature::is_array(class_name)) {
1972 constraint_name->decrement_refcount();
1973 }
1974 return result;
1975 }
1976 }
1977
1978 // Add entry to resolution error table to record the error when the first
1979 // attempt to resolve a reference to a class has failed.
1980 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1981 Symbol* error, Symbol* message,
1982 Symbol* cause, Symbol* cause_msg) {
1983 {
1984 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1985 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1986 if (entry == NULL) {
1987 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1988 }
1989 }
1990 }
1991
1992 // Delete a resolution error for RedefineClasses for a constant pool is going away
1993 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1994 ResolutionErrorTable::delete_entry(pool);
1995 }
1996
1997 // Lookup resolution error table. Returns error if found, otherwise NULL.
1998 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1999 Symbol** message, Symbol** cause, Symbol** cause_msg) {
2000
2001 {
2002 MutexLocker ml(Thread::current(), SystemDictionary_lock);
2003 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
2004 if (entry != NULL) {
2005 *message = entry->message();
2006 *cause = entry->cause();
2007 *cause_msg = entry->cause_msg();
2008 return entry->error();
2009 } else {
2010 return NULL;
2011 }
2012 }
2013 }
2014
2015 // Add an entry to resolution error table to record an error in resolving or
2016 // validating a nest host. This is used to construct informative error
2017 // messages when IllegalAccessError's occur. If an entry already exists it will
2018 // be updated with the nest host error message.
2019
2020 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
2021 int which,
2022 const char* message) {
2023 {
2024 MutexLocker ml(Thread::current(), SystemDictionary_lock);
2025 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
2026 if (entry != NULL && entry->nest_host_error() == NULL) {
2027 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
2028 // still want to add the error message for the higher-level access checks to report. We should
2029 // only reach here under the same error condition, so we can ignore the potential race with setting
2030 // the message. If we see it is already set then we can ignore it.
2031 entry->set_nest_host_error(message);
2032 } else {
2033 ResolutionErrorTable::add_entry(pool, which, message);
2034 }
2035 }
2036 }
2037
2038 // Lookup any nest host error
2039 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
2040 {
2041 MutexLocker ml(Thread::current(), SystemDictionary_lock);
2042 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
2043 if (entry != NULL) {
2044 return entry->nest_host_error();
2045 } else {
2046 return NULL;
2047 }
2048 }
2049 }
2050
2051 // Signature constraints ensure that callers and callees agree about
2052 // the meaning of type names in their signatures. This routine is the
2053 // intake for constraints. It collects them from several places:
2054 //
2055 // * LinkResolver::resolve_method (if check_access is true) requires
2056 // that the resolving class (the caller) and the defining class of
2057 // the resolved method (the callee) agree on each type in the
2058 // method's signature.
2059 //
2060 // * LinkResolver::resolve_interface_method performs exactly the same
2061 // checks.
2062 //
2063 // * LinkResolver::resolve_field requires that the constant pool
2064 // attempting to link to a field agree with the field's defining
2065 // class about the type of the field signature.
2066 //
2067 // * klassVtable::initialize_vtable requires that, when a class
2068 // overrides a vtable entry allocated by a superclass, that the
2069 // overriding method (i.e., the callee) agree with the superclass
2070 // on each type in the method's signature.
2071 //
2072 // * klassItable::initialize_itable requires that, when a class fills
2073 // in its itables, for each non-abstract method installed in an
2074 // itable, the method (i.e., the callee) agree with the interface
2075 // on each type in the method's signature.
2076 //
2077 // All those methods have a boolean (check_access, checkconstraints)
2078 // which turns off the checks. This is used from specialized contexts
2079 // such as bootstrapping, dumping, and debugging.
2080 //
2081 // No direct constraint is placed between the class and its
2082 // supertypes. Constraints are only placed along linked relations
2083 // between callers and callees. When a method overrides or implements
2084 // an abstract method in a supertype (superclass or interface), the
2085 // constraints are placed as if the supertype were the caller to the
2086 // overriding method. (This works well, since callers to the
2087 // supertype have already established agreement between themselves and
2088 // the supertype.) As a result of all this, a class can disagree with
2089 // its supertype about the meaning of a type name, as long as that
2090 // class neither calls a relevant method of the supertype, nor is
2091 // called (perhaps via an override) from the supertype.
2092 //
2093 //
2094 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
2095 //
2096 // Make sure all class components (including arrays) in the given
2097 // signature will be resolved to the same class in both loaders.
2098 // Returns the name of the type that failed a loader constraint check, or
2099 // NULL if no constraint failed. No exception except OOME is thrown.
2100 // Arrays are not added to the loader constraint table, their elements are.
2101 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2102 Klass* klass_being_linked,
2103 Handle loader1, Handle loader2,
2104 bool is_method) {
2105 // Nothing to do if loaders are the same.
2106 if (loader1() == loader2()) {
2107 return NULL;
2108 }
2109
2110 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
2111 if (ss.is_reference()) {
2112 Symbol* sig = ss.as_symbol();
2113 // Note: In the future, if template-like types can take
2114 // arguments, we will want to recognize them and dig out class
2115 // names hiding inside the argument lists.
2116 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
2117 return sig;
2118 }
2119 }
2120 }
2121 return NULL;
2122 }
2123
2124 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
2125 Symbol* signature,
2126 TRAPS) {
2127
2128 const int iid_as_int = vmIntrinsics::as_int(iid);
2129 assert(MethodHandles::is_signature_polymorphic(iid) &&
2130 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2131 iid != vmIntrinsics::_invokeGeneric,
2132 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
2133
2134 {
2135 MutexLocker ml(THREAD, InvokeMethodTable_lock);
2136 InvokeMethodKey key(signature, iid_as_int);
2137 Method** met = _invoke_method_intrinsic_table.get(key);
2138 if (met != nullptr) {
2139 return *met;
2140 }
2141
2142 bool throw_error = false;
2143 // This function could get an OOM but it is safe to call inside of a lock because
2144 // throwing OutOfMemoryError doesn't call Java code.
2145 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, CHECK_NULL);
2146 if (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative) {
2147 // Generate a compiled form of the MH intrinsic
2148 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2149 AdapterHandlerLibrary::create_native_wrapper(m);
2150 // Check if have the compiled code.
2151 throw_error = (!m->has_compiled_code());
2152 }
2153
2154 if (!throw_error) {
2155 signature->make_permanent(); // The signature is never unloaded.
2156 bool created = _invoke_method_intrinsic_table.put(key, m());
2157 assert(created, "must be since we still hold the lock");
2158 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2159 m->code()->entry_point() == m->from_compiled_entry()),
2160 "MH intrinsic invariant");
2161 return m();
2162 }
2163 }
2164
2165 // Throw error outside of the lock.
2166 THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
2167 "Out of space in CodeCache for method handle intrinsic");
2168 }
2169
2170 // Helper for unpacking the return value from linkMethod and linkCallSite.
2171 static Method* unpack_method_and_appendix(Handle mname,
2172 Klass* accessing_klass,
2173 objArrayHandle appendix_box,
2174 Handle* appendix_result,
2175 TRAPS) {
2176 if (mname.not_null()) {
2177 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2178 if (m != NULL) {
2179 oop appendix = appendix_box->obj_at(0);
2180 LogTarget(Info, methodhandles) lt;
2181 if (lt.develop_is_enabled()) {
2182 ResourceMark rm(THREAD);
2183 LogStream ls(lt);
2184 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2185 m->print_on(&ls);
2186 if (appendix != NULL) { ls.print("appendix = "); appendix->print_on(&ls); }
2187 ls.cr();
2188 }
2189
2190 (*appendix_result) = Handle(THREAD, appendix);
2191 // the target is stored in the cpCache and if a reference to this
2192 // MemberName is dropped we need a way to make sure the
2193 // class_loader containing this method is kept alive.
2194 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2195 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2196 this_key->record_dependency(m->method_holder());
2197 return mh();
2198 }
2199 }
2200 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2201 }
2202
2203 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2204 Symbol* name,
2205 Symbol* signature,
2206 Klass* accessing_klass,
2207 Handle* appendix_result,
2208 TRAPS) {
2209 assert(THREAD->can_call_java() ,"");
2210 Handle method_type =
2211 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2212
2213 int ref_kind = JVM_REF_invokeVirtual;
2214 oop name_oop = StringTable::intern(name, CHECK_NULL);
2215 Handle name_str (THREAD, name_oop);
2216 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2217 assert(appendix_box->obj_at(0) == NULL, "");
2218
2219 // This should not happen. JDK code should take care of that.
2220 if (accessing_klass == NULL || method_type.is_null()) {
2221 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2222 }
2223
2224 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2225 JavaCallArguments args;
2226 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2227 args.push_int(ref_kind);
2228 args.push_oop(Handle(THREAD, klass->java_mirror()));
2229 args.push_oop(name_str);
2230 args.push_oop(method_type);
2231 args.push_oop(appendix_box);
2232 JavaValue result(T_OBJECT);
2233 JavaCalls::call_static(&result,
2234 vmClasses::MethodHandleNatives_klass(),
2235 vmSymbols::linkMethod_name(),
2236 vmSymbols::linkMethod_signature(),
2237 &args, CHECK_NULL);
2238 Handle mname(THREAD, result.get_oop());
2239 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2240 }
2241
2242 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2243 // We must ensure that all class loaders everywhere will reach this class, for any client.
2244 // This is a safe bet for public classes in java.lang, such as Object and String.
2245 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2246 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2247 static bool is_always_visible_class(oop mirror) {
2248 Klass* klass = java_lang_Class::as_Klass(mirror);
2249 if (klass->is_objArray_klass()) {
2250 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2251 }
2252 if (klass->is_typeArray_klass()) {
2253 return true; // primitive array
2254 }
2255 assert(klass->is_instance_klass(), "%s", klass->external_name());
2256 return klass->is_public() &&
2257 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2258 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2259 }
2260
2261 // Find or construct the Java mirror (java.lang.Class instance) for
2262 // the given field type signature, as interpreted relative to the
2263 // given class loader. Handles primitives, void, references, arrays,
2264 // and all other reflectable types, except method types.
2265 // N.B. Code in reflection should use this entry point.
2266 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2267 Klass* accessing_klass,
2268 Handle class_loader,
2269 Handle protection_domain,
2270 SignatureStream::FailureMode failure_mode,
2271 TRAPS) {
2272 assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2273 "one or the other, or perhaps neither");
2274
2275 // What we have here must be a valid field descriptor,
2276 // and all valid field descriptors are supported.
2277 // Produce the same java.lang.Class that reflection reports.
2278 if (accessing_klass != NULL) {
2279 class_loader = Handle(THREAD, accessing_klass->class_loader());
2280 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2281 }
2282 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2283 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2284 if (mirror_oop == NULL) {
2285 return Handle(); // report failure this way
2286 }
2287 Handle mirror(THREAD, mirror_oop);
2288
2289 if (accessing_klass != NULL) {
2290 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2291 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2292 if (sel_klass != NULL) {
2293 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2294 }
2295 }
2296 return mirror;
2297 }
2298
2299
2300 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2301 // signature, as interpreted relative to the given class loader.
2302 // Because of class loader constraints, all method handle usage must be
2303 // consistent with this loader.
2304 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2305 Klass* accessing_klass,
2306 TRAPS) {
2307 Handle empty;
2308 OopHandle* o;
2309 {
2310 MutexLocker ml(THREAD, InvokeMethodTable_lock);
2311 o = _invoke_method_type_table.get(signature);
2312 }
2313
2314 if (o != nullptr) {
2315 oop mt = o->resolve();
2316 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2317 return Handle(THREAD, mt);
2318 } else if (!THREAD->can_call_java()) {
2319 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2320 return Handle(); // do not attempt from within compiler, unless it was cached
2321 }
2322
2323 Handle class_loader, protection_domain;
2324 if (accessing_klass != NULL) {
2325 class_loader = Handle(THREAD, accessing_klass->class_loader());
2326 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2327 }
2328 bool can_be_cached = true;
2329 int npts = ArgumentCount(signature).size();
2330 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2331 int arg = 0;
2332 Handle rt; // the return type from the signature
2333 ResourceMark rm(THREAD);
2334 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2335 oop mirror = NULL;
2336 if (can_be_cached) {
2337 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2338 mirror = ss.as_java_mirror(Handle(), Handle(),
2339 SignatureStream::ReturnNull, CHECK_(empty));
2340 if (mirror == NULL || (ss.is_reference() && !is_always_visible_class(mirror))) {
2341 // Fall back to accessing_klass context.
2342 can_be_cached = false;
2343 }
2344 }
2345 if (!can_be_cached) {
2346 // Resolve, throwing a real error if it doesn't work.
2347 mirror = ss.as_java_mirror(class_loader, protection_domain,
2348 SignatureStream::NCDFError, CHECK_(empty));
2349 }
2350 assert(mirror != NULL, "%s", ss.as_symbol()->as_C_string());
2351 if (ss.at_return_type())
2352 rt = Handle(THREAD, mirror);
2353 else
2354 pts->obj_at_put(arg++, mirror);
2355
2356 // Check accessibility.
2357 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2358 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2359 mirror = NULL; // safety
2360 // Emulate ConstantPool::verify_constant_pool_resolve.
2361 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2362 }
2363 }
2364 assert(arg == npts, "");
2365
2366 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2367 JavaCallArguments args(Handle(THREAD, rt()));
2368 args.push_oop(pts);
2369 JavaValue result(T_OBJECT);
2370 JavaCalls::call_static(&result,
2371 vmClasses::MethodHandleNatives_klass(),
2372 vmSymbols::findMethodHandleType_name(),
2373 vmSymbols::findMethodHandleType_signature(),
2374 &args, CHECK_(empty));
2375 Handle method_type(THREAD, result.get_oop());
2376
2377 if (can_be_cached) {
2378 // We can cache this MethodType inside the JVM.
2379 MutexLocker ml(THREAD, InvokeMethodTable_lock);
2380 bool created = false;
2381 assert(method_type != NULL, "unexpected null");
2382 OopHandle* h = _invoke_method_type_table.get(signature);
2383 if (h == nullptr) {
2384 signature->make_permanent(); // The signature is never unloaded.
2385 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2386 bool created = _invoke_method_type_table.put(signature, elem);
2387 assert(created, "better be created");
2388 }
2389 }
2390 // report back to the caller with the MethodType
2391 return method_type;
2392 }
2393
2394 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2395 Klass* accessing_klass,
2396 TRAPS) {
2397 Handle empty;
2398 ResourceMark rm(THREAD);
2399 SignatureStream ss(signature, /*is_method=*/ false);
2400 if (!ss.is_done()) {
2401 Handle class_loader, protection_domain;
2402 if (accessing_klass != NULL) {
2403 class_loader = Handle(THREAD, accessing_klass->class_loader());
2404 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2405 }
2406 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2407 ss.next();
2408 if (ss.is_done()) {
2409 return Handle(THREAD, mirror);
2410 }
2411 }
2412 return empty;
2413 }
2414
2415 // Ask Java code to find or construct a method handle constant.
2416 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2417 int ref_kind, //e.g., JVM_REF_invokeVirtual
2418 Klass* callee,
2419 Symbol* name,
2420 Symbol* signature,
2421 TRAPS) {
2422 Handle empty;
2423 if (caller == NULL) {
2424 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2425 }
2426 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2427 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2428
2429 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2430 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2431 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2432 java_lang_invoke_MemberName::set_name (mname(), name_str());
2433 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2434 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2435
2436 if (ref_kind == JVM_REF_invokeVirtual &&
2437 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2438 // Skip resolution for public signature polymorphic methods such as
2439 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2440 // They require appendix argument which MemberName resolution doesn't handle.
2441 // There's special logic on JDK side to handle them
2442 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2443 } else {
2444 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2445 }
2446
2447 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2448 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2449
2450 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2451 JavaCallArguments args;
2452 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2453 args.push_int(ref_kind);
2454 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2455 args.push_oop(name_str);
2456 args.push_oop(type);
2457 JavaValue result(T_OBJECT);
2458 JavaCalls::call_static(&result,
2459 vmClasses::MethodHandleNatives_klass(),
2460 vmSymbols::linkMethodHandleConstant_name(),
2461 vmSymbols::linkMethodHandleConstant_signature(),
2462 &args, CHECK_(empty));
2463 return Handle(THREAD, result.get_oop());
2464 }
2465
2466 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2467 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2468 // with linkage results being stored back into the bootstrap specifier.
2469 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2470 // Resolve the bootstrap specifier, its name, type, and static arguments
2471 bootstrap_specifier.resolve_bsm(CHECK);
2472
2473 // This should not happen. JDK code should take care of that.
2474 if (bootstrap_specifier.caller() == NULL || bootstrap_specifier.type_arg().is_null()) {
2475 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2476 }
2477
2478 bool is_indy = bootstrap_specifier.is_method_call();
2479 objArrayHandle appendix_box;
2480 if (is_indy) {
2481 // Some method calls may require an appendix argument. Arrange to receive it.
2482 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2483 assert(appendix_box->obj_at(0) == NULL, "");
2484 }
2485
2486 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2487 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2488 JavaCallArguments args;
2489 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2490 args.push_oop(bootstrap_specifier.bsm());
2491 args.push_oop(bootstrap_specifier.name_arg());
2492 args.push_oop(bootstrap_specifier.type_arg());
2493 args.push_oop(bootstrap_specifier.arg_values());
2494 if (is_indy) {
2495 args.push_oop(appendix_box);
2496 }
2497 JavaValue result(T_OBJECT);
2498 JavaCalls::call_static(&result,
2499 vmClasses::MethodHandleNatives_klass(),
2500 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2501 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2502 &args, CHECK);
2503
2504 Handle value(THREAD, result.get_oop());
2505 if (is_indy) {
2506 Handle appendix;
2507 Method* method = unpack_method_and_appendix(value,
2508 bootstrap_specifier.caller(),
2509 appendix_box,
2510 &appendix, CHECK);
2511 methodHandle mh(THREAD, method);
2512 bootstrap_specifier.set_resolved_method(mh, appendix);
2513 } else {
2514 bootstrap_specifier.set_resolved_value(value);
2515 }
2516
2517 // sanity check
2518 assert(bootstrap_specifier.is_resolved() ||
2519 (bootstrap_specifier.is_method_call() &&
2520 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2521 }
2522
2523
2524 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2525 assert(m != NULL, "Unexpected NULL Method*");
2526 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2527 }
2528
2529 // ----------------------------------------------------------------------------
2530
2531 void SystemDictionary::print_on(outputStream *st) {
2532 CDS_ONLY(SystemDictionaryShared::print_on(st));
2533 GCMutexLocker mu(SystemDictionary_lock);
2534
2535 ClassLoaderDataGraph::print_dictionary(st);
2536
2537 // Placeholders
2538 PlaceholderTable::print_on(st);
2539 st->cr();
2540
2541 // loader constraints - print under SD_lock
2542 LoaderConstraintTable::print_on(st);
2543 st->cr();
2544
2545 ProtectionDomainCacheTable::print_on(st);
2546 st->cr();
2547 }
2548
2549 void SystemDictionary::print() { print_on(tty); }
2550
2551 void SystemDictionary::verify() {
2552
2553 GCMutexLocker mu(SystemDictionary_lock);
2554
2555 // Verify dictionary
2556 ClassLoaderDataGraph::verify_dictionary();
2557
2558 // Verify constraint table
2559 LoaderConstraintTable::verify();
2560
2561 // Verify protection domain table
2562 ProtectionDomainCacheTable::verify();
2563 }
2564
2565 void SystemDictionary::dump(outputStream *st, bool verbose) {
2566 assert_locked_or_safepoint(SystemDictionary_lock);
2567 if (verbose) {
2568 print_on(st);
2569 } else {
2570 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2571 ClassLoaderDataGraph::print_table_statistics(st);
2572 LoaderConstraintTable::print_table_statistics(st);
2573 ProtectionDomainCacheTable::print_table_statistics(st);
2574 }
2575 }
2576
2577 // Utility for dumping dictionaries.
2578 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2579 DCmdWithParser(output, heap),
2580 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2581 "BOOLEAN", false, "false") {
2582 _dcmdparser.add_dcmd_option(&_verbose);
2583 }
2584
2585 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2586 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2587 _verbose.value());
2588 VMThread::execute(&dumper);
2589 }