1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "cds/aotClassLocation.hpp"
26 #include "cds/cdsConfig.hpp"
27 #include "cds/heapShared.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/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/resolutionErrors.hpp"
41 #include "classfile/stringTable.hpp"
42 #include "classfile/symbolTable.hpp"
43 #include "classfile/systemDictionary.hpp"
44 #include "classfile/vmClasses.hpp"
45 #include "classfile/vmSymbols.hpp"
46 #include "gc/shared/gcTraceTime.inline.hpp"
47 #include "interpreter/bootstrapInfo.hpp"
48 #include "jfr/jfrEvents.hpp"
49 #include "jvm.h"
50 #include "logging/log.hpp"
51 #include "logging/logStream.hpp"
52 #include "memory/metaspaceClosure.hpp"
53 #include "memory/oopFactory.hpp"
54 #include "memory/resourceArea.hpp"
55 #include "memory/universe.hpp"
56 #include "oops/access.inline.hpp"
57 #include "oops/instanceKlass.hpp"
58 #include "oops/klass.inline.hpp"
59 #include "oops/method.inline.hpp"
60 #include "oops/objArrayKlass.hpp"
61 #include "oops/objArrayOop.inline.hpp"
62 #include "oops/oop.inline.hpp"
63 #include "oops/oopHandle.inline.hpp"
64 #include "oops/symbol.hpp"
65 #include "oops/typeArrayKlass.hpp"
66 #include "prims/jvmtiExport.hpp"
67 #include "prims/methodHandles.hpp"
68 #include "runtime/arguments.hpp"
69 #include "runtime/atomic.hpp"
70 #include "runtime/handles.inline.hpp"
71 #include "runtime/java.hpp"
72 #include "runtime/javaCalls.hpp"
73 #include "runtime/mutexLocker.hpp"
74 #include "runtime/sharedRuntime.hpp"
75 #include "runtime/signature.hpp"
76 #include "runtime/synchronizer.hpp"
77 #include "services/classLoadingService.hpp"
78 #include "services/diagnosticCommand.hpp"
79 #include "services/finalizerService.hpp"
80 #include "services/threadService.hpp"
81 #include "utilities/growableArray.hpp"
82 #include "utilities/macros.hpp"
83 #include "utilities/utf8.hpp"
84 #if INCLUDE_CDS
85 #include "classfile/systemDictionaryShared.hpp"
86 #endif
87 #if INCLUDE_JFR
88 #include "jfr/jfr.hpp"
89 #endif
90
91 class InvokeMethodKey : public StackObj {
92 private:
93 Symbol* _symbol;
94 intptr_t _iid;
95
96 public:
97 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
98 _symbol(symbol),
99 _iid(iid) {}
100
101 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
102 return k1._symbol == k2._symbol && k1._iid == k2._iid;
103 }
104
105 static unsigned int compute_hash(const InvokeMethodKey &k) {
106 Symbol* sym = k._symbol;
107 intptr_t iid = k._iid;
108 unsigned int hash = (unsigned int) sym -> identity_hash();
109 return (unsigned int) (hash ^ iid);
110 }
111
112 };
113
114 using InvokeMethodIntrinsicTable = HashTable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
115 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
116 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
117 using InvokeMethodTypeTable = HashTable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
118 static InvokeMethodTypeTable* _invoke_method_type_table;
119
120 OopHandle SystemDictionary::_java_system_loader;
121 OopHandle SystemDictionary::_java_platform_loader;
122
123 // ----------------------------------------------------------------------------
124 // Java-level SystemLoader and PlatformLoader
125 oop SystemDictionary::java_system_loader() {
126 return _java_system_loader.resolve();
127 }
128
129 oop SystemDictionary::java_platform_loader() {
130 return _java_platform_loader.resolve();
131 }
132
133 void SystemDictionary::compute_java_loaders(TRAPS) {
134 if (_java_platform_loader.is_empty()) {
135 oop platform_loader = get_platform_class_loader_impl(CHECK);
136 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
137 } else {
138 // It must have been restored from the archived module graph
139 assert(CDSConfig::is_using_archive(), "must be");
140 assert(CDSConfig::is_using_full_module_graph(), "must be");
141 DEBUG_ONLY(
142 oop platform_loader = get_platform_class_loader_impl(CHECK);
143 assert(_java_platform_loader.resolve() == platform_loader, "must be");
144 )
145 }
146
147 if (_java_system_loader.is_empty()) {
148 oop system_loader = get_system_class_loader_impl(CHECK);
149 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
150 } else {
151 // It must have been restored from the archived module graph
152 assert(CDSConfig::is_using_archive(), "must be");
153 assert(CDSConfig::is_using_full_module_graph(), "must be");
154 DEBUG_ONLY(
155 oop system_loader = get_system_class_loader_impl(CHECK);
156 assert(_java_system_loader.resolve() == system_loader, "must be");
157 )
158 }
159 }
160
161 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
162 JavaValue result(T_OBJECT);
163 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
164 JavaCalls::call_static(&result,
165 class_loader_klass,
166 vmSymbols::getSystemClassLoader_name(),
167 vmSymbols::void_classloader_signature(),
168 CHECK_NULL);
169 return result.get_oop();
170 }
171
172 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
173 JavaValue result(T_OBJECT);
174 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
175 JavaCalls::call_static(&result,
176 class_loader_klass,
177 vmSymbols::getPlatformClassLoader_name(),
178 vmSymbols::void_classloader_signature(),
179 CHECK_NULL);
180 return result.get_oop();
181 }
182
183 // Helper function
184 inline ClassLoaderData* class_loader_data(Handle class_loader) {
185 return ClassLoaderData::class_loader_data(class_loader());
186 }
187
188 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
189 if (create_mirror_cld) {
190 // Add a new class loader data to the graph.
191 return ClassLoaderDataGraph::add(class_loader, true);
192 } else {
193 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
194 ClassLoaderDataGraph::find_or_create(class_loader);
195 }
196 }
197
198 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
199 assert(_java_system_loader.is_empty(), "already set!");
200 _java_system_loader = cld->class_loader_handle();
201
202 }
203
204 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
205 assert(_java_platform_loader.is_empty(), "already set!");
206 _java_platform_loader = cld->class_loader_handle();
207 }
208
209 // ----------------------------------------------------------------------------
210 // Parallel class loading check
211
212 static bool is_parallelCapable(Handle class_loader) {
213 if (class_loader.is_null()) return true;
214 return java_lang_ClassLoader::parallelCapable(class_loader());
215 }
216 // ----------------------------------------------------------------------------
217 // ParallelDefineClass flag does not apply to bootclass loader
218 static bool is_parallelDefine(Handle class_loader) {
219 if (class_loader.is_null()) return false;
220 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
221 return true;
222 }
223 return false;
224 }
225
226 // Returns true if the passed class loader is the builtin application class loader
227 // or a custom system class loader. A customer system class loader can be
228 // specified via -Djava.system.class.loader.
229 bool SystemDictionary::is_system_class_loader(oop class_loader) {
230 if (class_loader == nullptr) {
231 return false;
232 }
233 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
234 class_loader == _java_system_loader.peek());
235 }
236
237 // Returns true if the passed class loader is the platform class loader.
238 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
239 if (class_loader == nullptr) {
240 return false;
241 }
242 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
243 }
244
245 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
246 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
247 if (is_parallelCapable(class_loader)) {
248 return Handle();
249 } else {
250 return class_loader;
251 }
252 }
253
254 // ----------------------------------------------------------------------------
255 // Resolving of classes
256
257 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
258 if (name == nullptr) {
259 THROW_MSG_NULL(exception, "No class name given");
260 }
261 size_t name_len = strlen(name);
262 if (name_len > static_cast<size_t>(Symbol::max_length())) {
263 // It's impossible to create this class; the name cannot fit
264 // into the constant pool. If necessary report an abridged name
265 // in the exception message.
266 if (name_len > static_cast<size_t>(MaxStringPrintSize)) {
267 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
268 "Class name exceeds maximum length of %d: %.*s ... (%zu characters omitted) ... %.*s",
269 Symbol::max_length(),
270 MaxStringPrintSize / 2,
271 name,
272 name_len - 2 * (MaxStringPrintSize / 2), // allows for odd value
273 MaxStringPrintSize / 2,
274 name + name_len - MaxStringPrintSize / 2);
275 }
276 else {
277 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
278 "Class name exceeds maximum length of %d: %s",
279 Symbol::max_length(),
280 name);
281 }
282 return nullptr;
283 }
284 // Callers should ensure that the name is never an illegal UTF8 string.
285 assert(UTF8::is_legal_utf8((const unsigned char*)name, name_len, false),
286 "Class name is not a valid utf8 string.");
287
288 // Make a new symbol for the class name.
289 return SymbolTable::new_symbol(name);
290 }
291
292 #ifdef ASSERT
293 // Used to verify that class loading succeeded in adding k to the dictionary.
294 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
295 MutexLocker mu(SystemDictionary_lock);
296 ClassLoaderData* loader_data = k->class_loader_data();
297 Dictionary* dictionary = loader_data->dictionary();
298 assert(class_name == k->name(), "Must be the same");
299 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
300 assert(kk == k, "should be present in dictionary");
301 }
302 #endif
303
304 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
305 if (HAS_PENDING_EXCEPTION) {
306 // If we have a pending exception we forward it to the caller, unless throw_error is true,
307 // in which case we have to check whether the pending exception is a ClassNotFoundException,
308 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
309 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
310 ResourceMark rm(THREAD);
311 Handle e(THREAD, PENDING_EXCEPTION);
312 CLEAR_PENDING_EXCEPTION;
313 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
314 } else {
315 return; // the caller will throw the incoming exception
316 }
317 }
318 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
319 // error or exception depending on the value of throw_error.
320 ResourceMark rm(THREAD);
321 if (throw_error) {
322 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
323 } else {
324 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
325 }
326 }
327
328 // Forwards to resolve_or_null
329
330 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader,
331 bool throw_error, TRAPS) {
332 Klass* klass = resolve_or_null(class_name, class_loader, THREAD);
333 // Check for pending exception or null klass, and throw exception
334 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
335 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
336 }
337 return klass;
338 }
339
340 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
341
342 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, TRAPS) {
343 if (Signature::is_array(class_name)) {
344 return resolve_array_class_or_null(class_name, class_loader, THREAD);
345 } else {
346 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
347 if (Signature::has_envelope(class_name)) {
348 ResourceMark rm(THREAD);
349 // Ignore wrapping L and ;.
350 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
351 class_name->utf8_length() - 2);
352 return resolve_instance_class_or_null(name, class_loader, THREAD);
353 } else {
354 return resolve_instance_class_or_null(class_name, class_loader, THREAD);
355 }
356 }
357 }
358
359 // Forwards to resolve_instance_class_or_null
360
361 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
362 Handle class_loader,
363 TRAPS) {
364 assert(Signature::is_array(class_name), "must be array");
365 ResourceMark rm(THREAD);
366 SignatureStream ss(class_name, false);
367 int ndims = ss.skip_array_prefix(); // skip all '['s
368 Klass* k = nullptr;
369 BasicType t = ss.type();
370 if (ss.has_envelope()) {
371 Symbol* obj_class = ss.as_symbol();
372 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
373 class_loader,
374 CHECK_NULL);
375 if (k != nullptr) {
376 k = k->array_klass(ndims, CHECK_NULL);
377 }
378 } else {
379 k = Universe::typeArrayKlass(t);
380 k = k->array_klass(ndims, CHECK_NULL);
381 }
382 return k;
383 }
384
385 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
386 LogTarget(Debug, class, load, placeholders) lt;
387 if (lt.is_enabled()) {
388 ResourceMark rm;
389 LogStream ls(lt);
390 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
391 probe->print_on(&ls);
392 ls.cr();
393 }
394 }
395
396 // Must be called for any superclass or superinterface resolution
397 // during class definition to allow class circularity checking
398 // superinterface callers:
399 // parse_interfaces - from defineClass
400 // superclass callers:
401 // ClassFileParser - from defineClass
402 // load_shared_class - while loading a class from shared archive
403 // resolve_instance_class_or_null:
404 // via: handle_parallel_super_load
405 // when resolving a class that has an existing placeholder with
406 // a saved superclass [i.e. a defineClass is currently in progress]
407 // If another thread is trying to resolve the class, it must do
408 // superclass checks on its own thread to catch class circularity and
409 // to avoid deadlock.
410 //
411 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
412 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
413 // placeholder for the same thread, class, classloader is found.
414 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
415 //
416 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
417 Symbol* next_name,
418 Handle class_loader,
419 bool is_superclass,
420 TRAPS) {
421
422 assert(next_name != nullptr, "null superclass for resolving");
423 assert(!Signature::is_array(next_name), "invalid superclass name");
424
425 ClassLoaderData* loader_data = class_loader_data(class_loader);
426
427 if (is_superclass) {
428 InstanceKlass* klassk = loader_data->dictionary()->find_class(THREAD, class_name);
429 if (klassk != nullptr) {
430 // We can come here for two reasons:
431 // (a) RedefineClasses -- the class is already loaded
432 // (b) Rarely, the class might have been loaded by a parallel thread
433 // We can do a quick check against the already assigned superclass's name and loader.
434 InstanceKlass* superk = klassk->super();
435 if (superk != nullptr &&
436 superk->name() == next_name &&
437 superk->class_loader() == class_loader()) {
438 return superk;
439 }
440 }
441 }
442
443 // can't throw error holding a lock
444 bool throw_circularity_error = false;
445 {
446 MutexLocker mu(THREAD, SystemDictionary_lock);
447
448 // Must check ClassCircularity before resolving next_name (superclass or interface).
449 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
450 if (probe != nullptr && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
451 log_circularity_error(class_name, probe);
452 throw_circularity_error = true;
453 }
454
455 // Make sure there's a placeholder for the class_name before resolving.
456 // This is used as a claim that this thread is currently loading superclass/classloader
457 // and for ClassCircularity checks.
458 if (!throw_circularity_error) {
459 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
460 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
461 loader_data,
462 PlaceholderTable::DETECT_CIRCULARITY,
463 next_name, THREAD);
464 }
465 }
466
467 if (throw_circularity_error) {
468 ResourceMark rm(THREAD);
469 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
470 }
471
472 // Resolve the superclass or superinterface, check results on return
473 InstanceKlass* superk =
474 SystemDictionary::resolve_instance_class_or_null(next_name,
475 class_loader,
476 THREAD);
477
478 // Clean up placeholder entry.
479 {
480 MutexLocker mu(THREAD, SystemDictionary_lock);
481 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
482 SystemDictionary_lock->notify_all();
483 }
484
485 // Check for pending exception or null superk, and throw exception
486 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
487 handle_resolution_exception(next_name, true, CHECK_NULL);
488 }
489
490 return superk;
491 }
492
493 // If the class in is in the placeholder table, class loading is in progress.
494 // For cases where the application changes threads to load classes, it
495 // is critical to ClassCircularity detection that we try loading
496 // the superclass on the new thread internally, so we do parallel
497 // superclass loading here. This avoids deadlock for ClassCircularity
498 // detection for parallelCapable class loaders that lock on a per-class lock.
499 static void handle_parallel_super_load(Symbol* name,
500 Symbol* superclassname,
501 Handle class_loader,
502 TRAPS) {
503
504 // The result superk is not used; resolve_with_circularity_detection is called for circularity check only.
505 // This passes false to is_superclass to skip doing the unlikely optimization.
506 Klass* superk = SystemDictionary::resolve_with_circularity_detection(name,
507 superclassname,
508 class_loader,
509 false,
510 CHECK);
511 }
512
513 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
514 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
515 static bool needs_load_placeholder(Handle class_loader) {
516 return class_loader.is_null() || !is_parallelCapable(class_loader);
517 }
518
519 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
520 static InstanceKlass* handle_parallel_loading(JavaThread* current,
521 Symbol* name,
522 ClassLoaderData* loader_data,
523 bool must_wait_for_class_loading,
524 bool* throw_circularity_error) {
525 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
526 if (oldprobe != nullptr) {
527 // -Xcomp calls load_signature_classes which might result in loading
528 // a class that's already in the process of loading, so we detect CCE here also.
529 // Only need check_seen_thread once, not on each loop
530 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
531 log_circularity_error(name, oldprobe);
532 *throw_circularity_error = true;
533 return nullptr;
534 } else if (must_wait_for_class_loading) {
535 // Wait until the first thread has finished loading this class. Also wait until all the
536 // threads trying to load its superclass have removed their placeholders.
537 while (oldprobe != nullptr &&
538 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) {
539
540 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
541 // for the bootclass loader.
542 SystemDictionary_lock->wait();
543
544 // Check if classloading completed while we were waiting
545 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
546 if (check != nullptr) {
547 // Klass is already loaded, so just return it
548 return check;
549 }
550 // check if other thread failed to load and cleaned up
551 oldprobe = PlaceholderTable::get_entry(name, loader_data);
552 }
553 }
554 }
555 return nullptr;
556 }
557
558 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
559 assert(event != nullptr, "invariant");
560 assert(k != nullptr, "invariant");
561 event->set_loadedClass(k);
562 event->set_definingClassLoader(k->class_loader_data());
563 event->set_initiatingClassLoader(init_cld);
564 event->commit();
565 }
566
567 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
568 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
569 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
570 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
571 // This can return null, an exception or an InstanceKlass.
572 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
573 Handle class_loader,
574 TRAPS) {
575 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
576 DEBUG_ONLY(ResourceMark rm(THREAD));
577 assert(name != nullptr && !Signature::is_array(name) &&
578 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
579
580 EventClassLoad class_load_start_event;
581
582 HandleMark hm(THREAD);
583
584 ClassLoaderData* loader_data = register_loader(class_loader);
585 Dictionary* dictionary = loader_data->dictionary();
586
587 // Do lookup to see if class already exists.
588 InstanceKlass* probe = dictionary->find_class(THREAD, name);
589 if (probe != nullptr) return probe;
590
591 // Non-bootstrap class loaders will call out to class loader and
592 // define via jvm/jni_DefineClass which will acquire the
593 // class loader object lock to protect against multiple threads
594 // defining the class in parallel by accident.
595 // This lock must be acquired here so the waiter will find
596 // any successful result in the SystemDictionary and not attempt
597 // the define.
598 // ParallelCapable class loaders and the bootstrap classloader
599 // do not acquire lock here.
600 Handle lockObject = get_loader_lock_or_null(class_loader);
601 ObjectLocker ol(lockObject, THREAD);
602
603 bool circularity_detection_in_progress = false;
604 InstanceKlass* loaded_class = nullptr;
605 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
606
607 guarantee(THREAD->can_call_java(),
608 "can not load classes with compiler thread: class=%s, classloader=%s",
609 name->as_C_string(),
610 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
611
612 // Check again (after locking) if the class already exists in SystemDictionary
613 {
614 MutexLocker mu(THREAD, SystemDictionary_lock);
615 InstanceKlass* check = dictionary->find_class(THREAD, name);
616 if (check != nullptr) {
617 // InstanceKlass is already loaded, but we still need to check protection domain below.
618 loaded_class = check;
619 } else {
620 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
621 if (placeholder != nullptr && placeholder->circularity_detection_in_progress()) {
622 circularity_detection_in_progress = true;
623 superclassname = placeholder->next_klass_name();
624 assert(superclassname != nullptr, "superclass has to have a name");
625 }
626 }
627 }
628
629 // If the class is in the placeholder table with super_class set,
630 // handle superclass loading in progress.
631 if (circularity_detection_in_progress) {
632 handle_parallel_super_load(name, superclassname,
633 class_loader,
634 CHECK_NULL);
635 }
636
637 bool throw_circularity_error = false;
638 if (loaded_class == nullptr) {
639 bool load_placeholder_added = false;
640
641 // Add placeholder entry to record loading instance class
642 // case 1. Bootstrap classloader
643 // This classloader supports parallelism at the classloader level
644 // but only allows a single thread to load a class/classloader pair.
645 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
646 // case 2. parallelCapable user level classloaders
647 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
648 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
649 // case 3. traditional classloaders that rely on the classloader object lock
650 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
651 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
652 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
653 {
654 MutexLocker mu(THREAD, SystemDictionary_lock);
655 if (needs_load_placeholder(class_loader)) {
656 loaded_class = handle_parallel_loading(THREAD,
657 name,
658 loader_data,
659 class_loader.is_null(),
660 &throw_circularity_error);
661 }
662
663 // Recheck if the class has been loaded for all class loader cases and
664 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
665 if (!throw_circularity_error && loaded_class == nullptr) {
666 InstanceKlass* check = dictionary->find_class(THREAD, name);
667 if (check != nullptr) {
668 loaded_class = check;
669 } else if (needs_load_placeholder(class_loader)) {
670 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
671 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
672 PlaceholderTable::LOAD_INSTANCE,
673 nullptr,
674 THREAD);
675 load_placeholder_added = true;
676 }
677 }
678 }
679
680 // Must throw error outside of owning lock
681 if (throw_circularity_error) {
682 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
683 ResourceMark rm(THREAD);
684 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
685 }
686
687 // Be careful when modifying this code: once you have run
688 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
689 // you need to find_and_remove it before returning.
690 // So be careful to not exit with a CHECK_ macro between these calls.
691
692 if (loaded_class == nullptr) {
693 // Do actual loading
694 loaded_class = load_instance_class(name, class_loader, THREAD);
695 }
696
697 if (load_placeholder_added) {
698 // clean up placeholder entries for LOAD_INSTANCE success or error
699 // This brackets the SystemDictionary updates for both defining
700 // and initiating loaders
701 MutexLocker mu(THREAD, SystemDictionary_lock);
702 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
703 SystemDictionary_lock->notify_all();
704 }
705 }
706
707 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
708 return nullptr;
709 }
710
711 if (class_load_start_event.should_commit()) {
712 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
713 }
714
715 // Make sure we have the right class in the dictionary
716 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
717
718 return loaded_class;
719 }
720
721
722 // This routine does not lock the system dictionary.
723 //
724 // Since readers don't hold a lock, we must make sure that system
725 // dictionary entries are added to in a safe way (all links must
726 // be updated in an MT-safe manner). All entries are removed during class
727 // unloading, when this class loader is no longer referenced.
728 //
729 // Callers should be aware that an entry could be added just after
730 // Dictionary is read here, so the caller will not see
731 // the new entry.
732
733 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
734 Symbol* class_name,
735 Handle class_loader) {
736
737 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
738 if (loader_data == nullptr) {
739 // If the ClassLoaderData has not been setup,
740 // then the class loader has no entries in the dictionary.
741 return nullptr;
742 }
743
744 Dictionary* dictionary = loader_data->dictionary();
745 return dictionary->find_class(current, class_name);
746 }
747
748 // Look for a loaded instance or array klass by name. Do not do any loading.
749 // return null in case of error.
750 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
751 Symbol* class_name,
752 Handle class_loader) {
753 Klass* k = nullptr;
754 assert(class_name != nullptr, "class name must be non nullptr");
755
756 if (Signature::is_array(class_name)) {
757 // The name refers to an array. Parse the name.
758 // dimension and object_key in FieldArrayInfo are assigned as a
759 // side-effect of this call
760 SignatureStream ss(class_name, false);
761 int ndims = ss.skip_array_prefix(); // skip all '['s
762 BasicType t = ss.type();
763 if (t != T_OBJECT) {
764 k = Universe::typeArrayKlass(t);
765 } else {
766 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader);
767 }
768 if (k != nullptr) {
769 k = k->array_klass_or_null(ndims);
770 }
771 } else {
772 k = find_instance_klass(current, class_name, class_loader);
773 }
774 return k;
775 }
776
777 // Note: this method is much like resolve_class_from_stream, but
778 // does not publish the classes in the SystemDictionary.
779 // Handles Lookup.defineClass hidden.
780 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
781 ClassFileStream* st,
782 Symbol* class_name,
783 Handle class_loader,
784 const ClassLoadInfo& cl_info,
785 TRAPS) {
786
787 EventClassLoad class_load_start_event;
788 ClassLoaderData* loader_data;
789
790 // - for hidden classes that are not strong: create a new CLD that has a class holder and
791 // whose loader is the Lookup class's loader.
792 // - for hidden class: add the class to the Lookup class's loader's CLD.
793 assert (cl_info.is_hidden(), "only used for hidden classes");
794 bool create_mirror_cld = !cl_info.is_strong_hidden();
795 loader_data = register_loader(class_loader, create_mirror_cld);
796
797 assert(st != nullptr, "invariant");
798
799 // Parse stream and create a klass.
800 InstanceKlass* k = KlassFactory::create_from_stream(st,
801 class_name,
802 loader_data,
803 cl_info,
804 CHECK_NULL);
805 assert(k != nullptr, "no klass created");
806
807 // Hidden classes that are not strong must update ClassLoaderData holder
808 // so that they can be unloaded when the mirror is no longer referenced.
809 if (!cl_info.is_strong_hidden()) {
810 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
811 }
812
813 // Add to class hierarchy, and do possible deoptimizations.
814 k->add_to_hierarchy(THREAD);
815 // But, do not add to dictionary.
816
817 k->link_class(CHECK_NULL);
818
819 // notify jvmti
820 if (JvmtiExport::should_post_class_load()) {
821 JvmtiExport::post_class_load(THREAD, k);
822 }
823 if (class_load_start_event.should_commit()) {
824 post_class_load_event(&class_load_start_event, k, loader_data);
825 }
826
827 return k;
828 }
829
830 // Add a klass to the system from a stream (called by jni_DefineClass and
831 // JVM_DefineClass).
832 // Note: class_name can be null. In that case we do not know the name of
833 // the class until we have parsed the stream.
834 // This function either returns an InstanceKlass or throws an exception. It does
835 // not return null without a pending exception.
836 InstanceKlass* SystemDictionary::resolve_class_from_stream(
837 ClassFileStream* st,
838 Symbol* class_name,
839 Handle class_loader,
840 const ClassLoadInfo& cl_info,
841 TRAPS) {
842
843 HandleMark hm(THREAD);
844
845 ClassLoaderData* loader_data = register_loader(class_loader);
846
847 // Classloaders that support parallelism, e.g. bootstrap classloader,
848 // do not acquire lock here
849 Handle lockObject = get_loader_lock_or_null(class_loader);
850 ObjectLocker ol(lockObject, THREAD);
851
852 // Parse the stream and create a klass.
853 // Note that we do this even though this klass might
854 // already be present in the SystemDictionary, otherwise we would not
855 // throw potential ClassFormatErrors.
856 InstanceKlass* k = nullptr;
857
858 #if INCLUDE_CDS
859 if (!CDSConfig::is_dumping_static_archive()) {
860 k = SystemDictionaryShared::lookup_from_stream(class_name,
861 class_loader,
862 cl_info.protection_domain(),
863 st,
864 CHECK_NULL);
865 }
866 #endif
867
868 if (k == nullptr) {
869 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
870 }
871
872 assert(k != nullptr, "no klass created");
873 Symbol* h_name = k->name();
874 assert(class_name == nullptr || class_name == h_name, "name mismatch");
875
876 // Add class just loaded
877 // If a class loader supports parallel classloading, handle parallel define requests.
878 // find_or_define_instance_class may return a different InstanceKlass,
879 // in which case the old k would be deallocated
880 if (is_parallelCapable(class_loader)) {
881 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
882 } else {
883 define_instance_class(k, class_loader, THREAD);
884
885 // If defining the class throws an exception register 'k' for cleanup.
886 if (HAS_PENDING_EXCEPTION) {
887 assert(k != nullptr, "Must have an instance klass here!");
888 loader_data->add_to_deallocate_list(k);
889 return nullptr;
890 }
891 }
892
893 // Make sure we have an entry in the SystemDictionary on success
894 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
895
896 return k;
897 }
898
899 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
900 Symbol* class_name,
901 Handle class_loader,
902 const ClassLoadInfo& cl_info,
903 TRAPS) {
904 if (cl_info.is_hidden()) {
905 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
906 } else {
907 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
908 }
909 }
910
911
912 #if INCLUDE_CDS
913 // Check if a shared class can be loaded by the specific classloader.
914 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
915 InstanceKlass* ik,
916 PackageEntry* pkg_entry,
917 Handle class_loader) {
918 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
919 "Cannot use sharing if java.base is patched");
920
921 // (1) Check if we are loading into the same loader as in dump time.
922
923 if (ik->defined_by_boot_loader()) {
924 if (class_loader() != nullptr) {
925 return false;
926 }
927 } else if (ik->defined_by_platform_loader()) {
928 if (class_loader() != java_platform_loader()) {
929 return false;
930 }
931 } else if (ik->defined_by_app_loader()) {
932 if (class_loader() != java_system_loader()) {
933 return false;
934 }
935 } else {
936 // ik was loaded by a custom loader during dump time
937 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
938 return false;
939 } else {
940 return true;
941 }
942 }
943
944 // (2) Check if we are loading into the same module from the same location as in dump time.
945
946 if (CDSConfig::is_using_optimized_module_handling()) {
947 // Class visibility has not changed between dump time and run time, so a class
948 // that was visible (and thus archived) during dump time is always visible during runtime.
949 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
950 "visibility cannot change between dump time and runtime");
951 return true;
952 }
953 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
954 }
955
956 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
957 InstanceKlass* ik,
958 PackageEntry* pkg_entry,
959 Handle class_loader) {
960 int scp_index = ik->shared_classpath_index();
961 assert(!ik->defined_by_other_loaders(), "this function should be called for built-in classes only");
962 assert(scp_index >= 0, "must be");
963 const AOTClassLocation* cl = AOTClassLocationConfig::runtime()->class_location_at(scp_index);
964 if (!Universe::is_module_initialized()) {
965 assert(cl != nullptr, "must be");
966 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
967 // has restricted the classes can be loaded at this step to be only:
968 // [1] cs->is_modules_image(): classes in java.base, or,
969 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
970 assert(cl->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
971 "only these classes can be loaded before the module system is initialized");
972 assert(class_loader.is_null(), "sanity");
973 return true;
974 }
975
976 if (pkg_entry == nullptr) {
977 // We might have looked up pkg_entry before the module system was initialized.
978 // Need to reload it now.
979 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
980 if (pkg_name != nullptr) {
981 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
982 }
983 }
984
985 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
986 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
987 bool was_archived_from_named_module = !cl->has_unnamed_module();
988 bool visible;
989
990 if (was_archived_from_named_module) {
991 if (should_be_in_named_module) {
992 // Is the module loaded from the same location as during dump time?
993 visible = mod_entry->shared_path_index() == scp_index;
994 if (visible) {
995 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
996 }
997 } else {
998 // During dump time, this class was in a named module, but at run time, this class should be
999 // in an unnamed module.
1000 visible = false;
1001 }
1002 } else {
1003 if (should_be_in_named_module) {
1004 // During dump time, this class was in an unnamed, but at run time, this class should be
1005 // in a named module.
1006 visible = false;
1007 } else {
1008 visible = true;
1009 }
1010 }
1011
1012 return visible;
1013 }
1014
1015 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1016 Handle class_loader, bool is_superclass, TRAPS) {
1017 assert(super_type->in_aot_cache(), "must be");
1018
1019 // Quick check if the super type has been already loaded.
1020 // + Don't do it for unregistered classes -- they can be unloaded so
1021 // super_type->class_loader_data() could be stale.
1022 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1023 if (!super_type->defined_by_other_loaders() && super_type->class_loader_data() != nullptr) {
1024 // Check if the superclass is loaded by the current class_loader
1025 Symbol* name = super_type->name();
1026 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader);
1027 if (check == super_type) {
1028 return true;
1029 }
1030 }
1031
1032 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(),
1033 class_loader, is_superclass, CHECK_false);
1034 if (found == super_type) {
1035 return true;
1036 } else {
1037 // The dynamically resolved super type is not the same as the one we used during dump time,
1038 // so we cannot use the class.
1039 return false;
1040 }
1041 }
1042
1043 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader, TRAPS) {
1044 // Check the superclass and interfaces. They must be the same
1045 // as in dump time, because the layout of <ik> depends on
1046 // the specific layout of ik->super() and ik->local_interfaces().
1047 //
1048 // If unexpected superclass or interfaces are found, we cannot
1049 // load <ik> from the shared archive.
1050
1051 if (ik->super() != nullptr) {
1052 bool check_super = check_shared_class_super_type(ik, ik->super(),
1053 class_loader, true,
1054 CHECK_false);
1055 if (!check_super) {
1056 return false;
1057 }
1058 }
1059
1060 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1061 int num_interfaces = interfaces->length();
1062 for (int index = 0; index < num_interfaces; index++) {
1063 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, false,
1064 CHECK_false);
1065 if (!check_interface) {
1066 return false;
1067 }
1068 }
1069
1070 return true;
1071 }
1072
1073 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1074 Handle class_loader,
1075 Handle protection_domain,
1076 const ClassFileStream *cfs,
1077 PackageEntry* pkg_entry,
1078 TRAPS) {
1079 assert(ik != nullptr, "sanity");
1080 assert(ik->in_aot_cache(), "sanity");
1081 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1082 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1083 Symbol* class_name = ik->name();
1084
1085 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1086 ik->set_shared_loading_failed();
1087 return nullptr;
1088 }
1089
1090 bool check = check_shared_class_super_types(ik, class_loader, CHECK_NULL);
1091 if (!check) {
1092 ik->set_shared_loading_failed();
1093 return nullptr;
1094 }
1095
1096 InstanceKlass* new_ik = nullptr;
1097 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1098 // It will be skipped for shared VM hidden lambda proxy classes.
1099 if (!ik->is_hidden()) {
1100 new_ik = KlassFactory::check_shared_class_file_load_hook(
1101 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1102 }
1103 if (new_ik != nullptr) {
1104 // The class is changed by CFLH. Return the new class. The shared class is
1105 // not used.
1106 return new_ik;
1107 }
1108
1109 // Adjust methods to recover missing data. They need addresses for
1110 // interpreter entry points and their default native method address
1111 // must be reset.
1112
1113 // Shared classes are all currently loaded by either the bootstrap or
1114 // internal parallel class loaders, so this will never cause a deadlock
1115 // on a custom class loader lock.
1116 // Since this class is already locked with parallel capable class
1117 // loaders, including the bootstrap loader via the placeholder table,
1118 // this lock is currently a nop.
1119
1120 ClassLoaderData* loader_data = class_loader_data(class_loader);
1121 {
1122 HandleMark hm(THREAD);
1123 Handle lockObject = get_loader_lock_or_null(class_loader);
1124 ObjectLocker ol(lockObject, THREAD);
1125 // prohibited package check assumes all classes loaded from archive call
1126 // restore_unshareable_info which calls ik->set_package()
1127 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1128 }
1129
1130 load_shared_class_misc(ik, loader_data);
1131 return ik;
1132 }
1133
1134 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1135 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1136
1137 // For boot loader, ensure that GetSystemPackage knows that a class in this
1138 // package was loaded.
1139 if (loader_data->is_the_null_class_loader_data()) {
1140 s2 path_index = ik->shared_classpath_index();
1141 ik->set_classpath_index(path_index);
1142 }
1143
1144 // notify a class loaded from shared object
1145 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1146
1147 if (CDSConfig::is_dumping_final_static_archive()) {
1148 SystemDictionaryShared::init_dumptime_info_from_preimage(ik);
1149 }
1150 }
1151
1152 #endif // INCLUDE_CDS
1153
1154 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1155
1156 if (class_loader.is_null()) {
1157 ResourceMark rm(THREAD);
1158 PackageEntry* pkg_entry = nullptr;
1159 bool search_only_bootloader_append = false;
1160
1161 // Find the package in the boot loader's package entry table.
1162 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1163 if (pkg_name != nullptr) {
1164 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1165 }
1166
1167 // Prior to attempting to load the class, enforce the boot loader's
1168 // visibility boundaries.
1169 if (!Universe::is_module_initialized()) {
1170 // During bootstrapping, prior to module initialization, any
1171 // class attempting to be loaded must be checked against the
1172 // java.base packages in the boot loader's PackageEntryTable.
1173 // No class outside of java.base is allowed to be loaded during
1174 // this bootstrapping window.
1175 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1176 // Class is either in the unnamed package or in
1177 // a named package within the unnamed module. Either
1178 // case is outside of java.base, do not attempt to
1179 // load the class post java.base definition. If
1180 // java.base has not been defined, let the class load
1181 // and its package will be checked later by
1182 // ModuleEntryTable::verify_javabase_packages.
1183 if (ModuleEntryTable::javabase_defined()) {
1184 return nullptr;
1185 }
1186 } else {
1187 // Check that the class' package is defined within java.base.
1188 ModuleEntry* mod_entry = pkg_entry->module();
1189 Symbol* mod_entry_name = mod_entry->name();
1190 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1191 return nullptr;
1192 }
1193 }
1194 } else {
1195 // After the module system has been initialized, check if the class'
1196 // package is in a module defined to the boot loader.
1197 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1198 // Class is either in the unnamed package, in a named package
1199 // within a module not defined to the boot loader or in a
1200 // a named package within the unnamed module. In all cases,
1201 // limit visibility to search for the class only in the boot
1202 // loader's append path.
1203 if (!ClassLoader::has_bootclasspath_append()) {
1204 // If there is no bootclasspath append entry, no need to continue
1205 // searching.
1206 return nullptr;
1207 }
1208 search_only_bootloader_append = true;
1209 }
1210 }
1211
1212 // Prior to bootstrapping's module initialization, never load a class outside
1213 // of the boot loader's module path
1214 assert(Universe::is_module_initialized() ||
1215 !search_only_bootloader_append,
1216 "Attempt to load a class outside of boot loader's module path");
1217
1218 // Search for classes in the CDS archive.
1219 InstanceKlass* k = nullptr;
1220
1221 #if INCLUDE_CDS
1222 if (CDSConfig::is_using_archive())
1223 {
1224 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1225 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1226 if (ik != nullptr && ik->defined_by_boot_loader() && !ik->shared_loading_failed()) {
1227 SharedClassLoadingMark slm(THREAD, ik);
1228 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1229 }
1230 }
1231 #endif
1232
1233 if (k == nullptr) {
1234 // Use VM class loader
1235 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1236 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1237 }
1238
1239 // find_or_define_instance_class may return a different InstanceKlass
1240 if (k != nullptr) {
1241 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1242 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1243 }
1244 return k;
1245 } else {
1246 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1247 ResourceMark rm(THREAD);
1248
1249 JavaThread* jt = THREAD;
1250
1251 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1252 ClassLoader::perf_app_classload_selftime(),
1253 ClassLoader::perf_app_classload_count(),
1254 jt->get_thread_stat()->perf_recursion_counts_addr(),
1255 jt->get_thread_stat()->perf_timers_addr(),
1256 PerfClassTraceTime::CLASS_LOAD);
1257
1258 // Translate to external class name format, i.e., convert '/' chars to '.'
1259 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1260
1261 JavaValue result(T_OBJECT);
1262
1263 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1264
1265 // Call public unsynchronized loadClass(String) directly for all class loaders.
1266 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1267 // acquire a class-name based lock rather than the class loader object lock.
1268 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1269 JavaCalls::call_virtual(&result,
1270 class_loader,
1271 spec_klass,
1272 vmSymbols::loadClass_name(),
1273 vmSymbols::string_class_signature(),
1274 string,
1275 CHECK_NULL);
1276
1277 assert(result.get_type() == T_OBJECT, "just checking");
1278 oop obj = result.get_oop();
1279
1280 // Primitive classes return null since forName() can not be
1281 // used to obtain any of the Class objects representing primitives or void
1282 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1283 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1284 // For user defined Java class loaders, check that the name returned is
1285 // the same as that requested. This check is done for the bootstrap
1286 // loader when parsing the class file.
1287 if (class_name == k->name()) {
1288 return k;
1289 }
1290 }
1291 // Class is not found or has the wrong name, return null
1292 return nullptr;
1293 }
1294 }
1295
1296 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1297 Handle class_loader,
1298 TRAPS) {
1299
1300 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1301
1302 // If everything was OK (no exceptions, no null return value), and
1303 // class_loader is NOT the defining loader, do a little more bookkeeping.
1304 if (loaded_class != nullptr &&
1305 loaded_class->class_loader() != class_loader()) {
1306
1307 ClassLoaderData* loader_data = class_loader_data(class_loader);
1308 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1309
1310 // Record dependency for non-parent delegation.
1311 // This recording keeps the defining class loader of the klass (loaded_class) found
1312 // from being unloaded while the initiating class loader is loaded
1313 // even if the reference to the defining class loader is dropped
1314 // before references to the initiating class loader.
1315 loader_data->record_dependency(loaded_class);
1316
1317 update_dictionary(THREAD, loaded_class, loader_data);
1318
1319 if (JvmtiExport::should_post_class_load()) {
1320 JvmtiExport::post_class_load(THREAD, loaded_class);
1321 }
1322 }
1323 return loaded_class;
1324 }
1325
1326 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1327 EventClassDefine event;
1328 if (event.should_commit()) {
1329 event.set_definedClass(k);
1330 event.set_definingClassLoader(def_cld);
1331 event.commit();
1332 }
1333 }
1334
1335 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1336
1337 ClassLoaderData* loader_data = k->class_loader_data();
1338 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1339
1340 // Bootstrap and other parallel classloaders don't acquire a lock,
1341 // they use placeholder token.
1342 // If a parallelCapable class loader calls define_instance_class instead of
1343 // find_or_define_instance_class to get here, we have a timing
1344 // hole with systemDictionary updates and check_constraints
1345 if (!is_parallelCapable(class_loader)) {
1346 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1347 get_loader_lock_or_null(class_loader)),
1348 "define called without lock");
1349 }
1350
1351 // Check class-loading constraints. Throw exception if violation is detected.
1352 // Grabs and releases SystemDictionary_lock
1353 // The check_constraints/find_class call and update_dictionary sequence
1354 // must be "atomic" for a specific class/classloader pair so we never
1355 // define two different instanceKlasses for that class/classloader pair.
1356 // Existing classloaders will call define_instance_class with the
1357 // classloader lock held
1358 // Parallel classloaders will call find_or_define_instance_class
1359 // which will require a token to perform the define class
1360 check_constraints(k, loader_data, true, CHECK);
1361
1362 // Register class just loaded with class loader (placed in ArrayList)
1363 // Note we do this before updating the dictionary, as this can
1364 // fail with an OutOfMemoryError (if it does, we will *not* put this
1365 // class in the dictionary and will not update the class hierarchy).
1366 // JVMTI FollowReferences needs to find the classes this way.
1367 if (k->class_loader() != nullptr) {
1368 methodHandle m(THREAD, Universe::loader_addClass_method());
1369 JavaValue result(T_VOID);
1370 JavaCallArguments args(class_loader);
1371 args.push_oop(Handle(THREAD, k->java_mirror()));
1372 JavaCalls::call(&result, m, &args, CHECK);
1373 }
1374
1375 // Add to class hierarchy, and do possible deoptimizations.
1376 k->add_to_hierarchy(THREAD);
1377
1378 // Add to systemDictionary - so other classes can see it.
1379 // Grabs and releases SystemDictionary_lock
1380 update_dictionary(THREAD, k, loader_data);
1381
1382 // notify jvmti
1383 if (JvmtiExport::should_post_class_load()) {
1384 JvmtiExport::post_class_load(THREAD, k);
1385 }
1386 post_class_define_event(k, loader_data);
1387 }
1388
1389 // Support parallel classloading
1390 // All parallel class loaders, including bootstrap classloader
1391 // lock a placeholder entry for this class/class_loader pair
1392 // to allow parallel defines of different classes for this class loader
1393 // With AllowParallelDefine flag==true, in case they do not synchronize around
1394 // FindLoadedClass/DefineClass, calls, we check for parallel
1395 // loading for them, wait if a defineClass is in progress
1396 // and return the initial requestor's results
1397 // This flag does not apply to the bootstrap classloader.
1398 // With AllowParallelDefine flag==false, call through to define_instance_class
1399 // which will throw LinkageError: duplicate class definition.
1400 // False is the requested default.
1401 // For better performance, the class loaders should synchronize
1402 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1403 // potentially waste time reading and parsing the bytestream.
1404 // Note: VM callers should ensure consistency of k/class_name,class_loader
1405 // Be careful when modifying this code: once you have run
1406 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1407 // you need to find_and_remove it before returning.
1408 // So be careful to not exit with a CHECK_ macro between these calls.
1409 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1410 InstanceKlass* k, TRAPS) {
1411
1412 Symbol* name_h = k->name();
1413 ClassLoaderData* loader_data = class_loader_data(class_loader);
1414 Dictionary* dictionary = loader_data->dictionary();
1415
1416 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1417 {
1418 MutexLocker mu(THREAD, SystemDictionary_lock);
1419 // First check if class already defined
1420 if (is_parallelDefine(class_loader)) {
1421 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1422 if (check != nullptr) {
1423 return check;
1424 }
1425 }
1426
1427 // Acquire define token for this class/classloader
1428 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1429 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1430 // Wait if another thread defining in parallel
1431 // All threads wait - even those that will throw duplicate class: otherwise
1432 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1433 // if other thread has not finished updating dictionary
1434 while (probe->definer() != nullptr) {
1435 SystemDictionary_lock->wait();
1436 }
1437 // Only special cases allow parallel defines and can use other thread's results
1438 // Other cases fall through, and may run into duplicate defines
1439 // caught by finding an entry in the SystemDictionary
1440 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1441 InstanceKlass* ik = probe->instance_klass();
1442 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1443 SystemDictionary_lock->notify_all();
1444 #ifdef ASSERT
1445 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1446 assert(check != nullptr, "definer missed recording success");
1447 #endif
1448 return ik;
1449 } else {
1450 // This thread will define the class (even if earlier thread tried and had an error)
1451 probe->set_definer(THREAD);
1452 }
1453 }
1454
1455 define_instance_class(k, class_loader, THREAD);
1456
1457 // definer must notify any waiting threads
1458 {
1459 MutexLocker mu(THREAD, SystemDictionary_lock);
1460 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1461 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1462 if (!HAS_PENDING_EXCEPTION) {
1463 probe->set_instance_klass(k);
1464 }
1465 probe->set_definer(nullptr);
1466 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1467 SystemDictionary_lock->notify_all();
1468 }
1469
1470 return HAS_PENDING_EXCEPTION ? nullptr : k;
1471 }
1472
1473 // If a class loader supports parallel classloading handle parallel define requests.
1474 // find_or_define_instance_class may return a different InstanceKlass
1475 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1476 InstanceKlass* k, TRAPS) {
1477 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1478 // Clean up original InstanceKlass if duplicate or error
1479 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1480 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1481 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1482 k->class_loader_data()->add_to_deallocate_list(k);
1483 } else if (HAS_PENDING_EXCEPTION) {
1484 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1485 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1486 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1487 k->class_loader_data()->add_to_deallocate_list(k);
1488 }
1489 return defined_k;
1490 }
1491
1492
1493 // ----------------------------------------------------------------------------
1494 // GC support
1495
1496 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1497 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1498
1499 bool unloading_occurred;
1500 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1501 {
1502 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1503 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1504 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1505 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1506 if (unloading_occurred) {
1507 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1508 JFR_ONLY(Jfr::on_unloading_classes();)
1509 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1510 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1511 ClassLoaderDataGraph::clean_module_and_package_info();
1512 LoaderConstraintTable::purge_loader_constraints();
1513 ResolutionErrorTable::purge_resolution_errors();
1514 }
1515 }
1516
1517 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1518
1519 if (unloading_occurred) {
1520 SymbolTable::trigger_cleanup();
1521
1522 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1523 InstanceKlass::clean_initialization_error_table();
1524 }
1525
1526 return unloading_occurred;
1527 }
1528
1529 void SystemDictionary::methods_do(void f(Method*)) {
1530 // Walk methods in loaded classes
1531
1532 {
1533 MutexLocker ml(ClassLoaderDataGraph_lock);
1534 ClassLoaderDataGraph::methods_do(f);
1535 }
1536
1537 auto doit = [&] (InvokeMethodKey key, Method* method) {
1538 if (method != nullptr) {
1539 f(method);
1540 }
1541 };
1542
1543 {
1544 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1545 _invoke_method_intrinsic_table->iterate_all(doit);
1546 }
1547
1548 }
1549
1550 // ----------------------------------------------------------------------------
1551 // Initialization
1552
1553 void SystemDictionary::initialize(TRAPS) {
1554 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1555 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1556 ResolutionErrorTable::initialize();
1557 LoaderConstraintTable::initialize();
1558 PlaceholderTable::initialize();
1559 #if INCLUDE_CDS
1560 SystemDictionaryShared::initialize();
1561 if (CDSConfig::is_dumping_archive()) {
1562 AOTClassLocationConfig::dumptime_init(THREAD);
1563 }
1564 #endif
1565 // Resolve basic classes
1566 vmClasses::resolve_all(CHECK);
1567 // Resolve classes used by archived heap objects
1568 if (CDSConfig::is_using_archive()) {
1569 HeapShared::resolve_classes(THREAD);
1570 }
1571 }
1572
1573 // Constraints on class loaders. The details of the algorithm can be
1574 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1575 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1576 // that the dictionary needs to maintain a set of constraints that
1577 // must be satisfied by all classes in the dictionary.
1578 // if defining is true, then LinkageError if already in dictionary
1579 // if initiating loader, then ok if InstanceKlass matches existing entry
1580
1581 void SystemDictionary::check_constraints(InstanceKlass* k,
1582 ClassLoaderData* loader_data,
1583 bool defining,
1584 TRAPS) {
1585 ResourceMark rm(THREAD);
1586 stringStream ss;
1587 bool throwException = false;
1588
1589 {
1590 Symbol* name = k->name();
1591
1592 MutexLocker mu(THREAD, SystemDictionary_lock);
1593
1594 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1595 if (check != nullptr) {
1596 // If different InstanceKlass - duplicate class definition,
1597 // else - ok, class loaded by a different thread in parallel.
1598 // We should only have found it if it was done loading and ok to use.
1599
1600 if ((defining == true) || (k != check)) {
1601 throwException = true;
1602 ss.print("loader %s", loader_data->loader_name_and_id());
1603 ss.print(" attempted duplicate %s definition for %s. (%s)",
1604 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1605 } else {
1606 return;
1607 }
1608 }
1609
1610 if (throwException == false) {
1611 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1612 throwException = true;
1613 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1614 ss.print(" wants to load %s %s.",
1615 k->external_kind(), k->external_name());
1616 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1617 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1618 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1619 existing_klass->external_kind(),
1620 existing_klass->class_loader_data()->loader_name_and_id(),
1621 existing_klass->class_in_module_of_loader(false, true));
1622 } else {
1623 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1624 }
1625 }
1626 }
1627 }
1628
1629 // Throw error now if needed (cannot throw while holding
1630 // SystemDictionary_lock because of rank ordering)
1631 if (throwException == true) {
1632 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1633 }
1634 }
1635
1636 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1637 // have been called.
1638 void SystemDictionary::update_dictionary(JavaThread* current,
1639 InstanceKlass* k,
1640 ClassLoaderData* loader_data) {
1641 MonitorLocker mu1(SystemDictionary_lock);
1642
1643 // Make a new dictionary entry.
1644 Symbol* name = k->name();
1645 Dictionary* dictionary = loader_data->dictionary();
1646 InstanceKlass* sd_check = dictionary->find_class(current, name);
1647 if (sd_check == nullptr) {
1648 dictionary->add_klass(current, name, k);
1649 }
1650 mu1.notify_all();
1651 }
1652
1653 #if INCLUDE_CDS
1654 // Indicate that loader_data has initiated the loading of class k, which
1655 // has already been defined by a parent loader.
1656 // This API should be used only by AOTLinkedClassBulkLoader
1657 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1658 InstanceKlass* k,
1659 ClassLoaderData* loader_data) {
1660 assert(CDSConfig::is_using_aot_linked_classes(), "must be");
1661 assert_locked_or_safepoint(SystemDictionary_lock);
1662 Symbol* name = k->name();
1663 Dictionary* dictionary = loader_data->dictionary();
1664 assert(k->is_loaded(), "must be");
1665 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1666 assert(dictionary->find_class(current, name) == nullptr, "sanity");
1667 dictionary->add_klass(current, name, k);
1668 }
1669 #endif
1670
1671 // Try to find a class name using the loader constraints. The
1672 // loader constraints might know about a class that isn't fully loaded
1673 // yet and these will be ignored.
1674 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1675 Thread* current, Symbol* class_name, Handle class_loader) {
1676
1677 // First see if it has been loaded directly.
1678 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader);
1679 if (klass != nullptr)
1680 return klass;
1681
1682 // Now look to see if it has been loaded elsewhere, and is subject to
1683 // a loader constraint that would require this loader to return the
1684 // klass that is already loaded.
1685 if (Signature::is_array(class_name)) {
1686 // For array classes, their Klass*s are not kept in the
1687 // constraint table. The element Klass*s are.
1688 SignatureStream ss(class_name, false);
1689 int ndims = ss.skip_array_prefix(); // skip all '['s
1690 BasicType t = ss.type();
1691 if (t != T_OBJECT) {
1692 klass = Universe::typeArrayKlass(t);
1693 } else {
1694 MutexLocker mu(current, SystemDictionary_lock);
1695 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1696 }
1697 // If element class already loaded, allocate array klass
1698 if (klass != nullptr) {
1699 klass = klass->array_klass_or_null(ndims);
1700 }
1701 } else {
1702 MutexLocker mu(current, SystemDictionary_lock);
1703 // Non-array classes are easy: simply check the constraint table.
1704 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1705 }
1706
1707 return klass;
1708 }
1709
1710 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1711 Klass* klass_being_linked,
1712 Handle class_loader1,
1713 Handle class_loader2) {
1714 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1715 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1716
1717 Symbol* constraint_name = nullptr;
1718
1719 if (!Signature::is_array(class_name)) {
1720 constraint_name = class_name;
1721 } else {
1722 // For array classes, their Klass*s are not kept in the
1723 // constraint table. The element classes are.
1724 SignatureStream ss(class_name, false);
1725 ss.skip_array_prefix(); // skip all '['s
1726 if (!ss.has_envelope()) {
1727 return true; // primitive types always pass
1728 }
1729 constraint_name = ss.as_symbol();
1730 // Increment refcount to keep constraint_name alive after
1731 // SignatureStream is destructed. It will be decremented below
1732 // before returning.
1733 constraint_name->increment_refcount();
1734 }
1735
1736 Dictionary* dictionary1 = loader_data1->dictionary();
1737 Dictionary* dictionary2 = loader_data2->dictionary();
1738
1739 JavaThread* current = JavaThread::current();
1740 {
1741 MutexLocker mu_s(SystemDictionary_lock);
1742 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1743 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1744 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1745 klass2, loader_data2);
1746 #if INCLUDE_CDS
1747 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1748 !klass_being_linked->in_aot_cache()) {
1749 SystemDictionaryShared::record_linking_constraint(constraint_name,
1750 InstanceKlass::cast(klass_being_linked),
1751 class_loader1, class_loader2);
1752 }
1753 #endif // INCLUDE_CDS
1754 if (Signature::is_array(class_name)) {
1755 constraint_name->decrement_refcount();
1756 }
1757 return result;
1758 }
1759 }
1760
1761 // Add entry to resolution error table to record the error when the first
1762 // attempt to resolve a reference to a class has failed.
1763 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1764 Symbol* error, const char* message,
1765 Symbol* cause, const char* cause_msg) {
1766 {
1767 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1768 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1769 if (entry == nullptr) {
1770 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1771 }
1772 }
1773 }
1774
1775 // Delete a resolution error for RedefineClasses for a constant pool is going away
1776 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1777 ResolutionErrorTable::delete_entry(pool);
1778 }
1779
1780 // Lookup resolution error table. Returns error if found, otherwise null.
1781 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1782 const char** message,
1783 Symbol** cause, const char** cause_msg) {
1784
1785 {
1786 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1787 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1788 if (entry != nullptr) {
1789 *message = entry->message();
1790 *cause = entry->cause();
1791 *cause_msg = entry->cause_msg();
1792 return entry->error();
1793 } else {
1794 return nullptr;
1795 }
1796 }
1797 }
1798
1799 // Add an entry to resolution error table to record an error in resolving or
1800 // validating a nest host. This is used to construct informative error
1801 // messages when IllegalAccessError's occur. If an entry already exists it will
1802 // be updated with the nest host error message.
1803
1804 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1805 int which,
1806 const char* message) {
1807 {
1808 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1809 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1810 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1811 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1812 // still want to add the error message for the higher-level access checks to report. We should
1813 // only reach here under the same error condition, so we can ignore the potential race with setting
1814 // the message. If we see it is already set then we can ignore it.
1815 entry->set_nest_host_error(message);
1816 } else {
1817 ResolutionErrorTable::add_entry(pool, which, message);
1818 }
1819 }
1820 }
1821
1822 // Lookup any nest host error
1823 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1824 {
1825 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1826 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1827 if (entry != nullptr) {
1828 return entry->nest_host_error();
1829 } else {
1830 return nullptr;
1831 }
1832 }
1833 }
1834
1835 // Signature constraints ensure that callers and callees agree about
1836 // the meaning of type names in their signatures. This routine is the
1837 // intake for constraints. It collects them from several places:
1838 //
1839 // * LinkResolver::resolve_method (if check_access is true) requires
1840 // that the resolving class (the caller) and the defining class of
1841 // the resolved method (the callee) agree on each type in the
1842 // method's signature.
1843 //
1844 // * LinkResolver::resolve_interface_method performs exactly the same
1845 // checks.
1846 //
1847 // * LinkResolver::resolve_field requires that the constant pool
1848 // attempting to link to a field agree with the field's defining
1849 // class about the type of the field signature.
1850 //
1851 // * klassVtable::initialize_vtable requires that, when a class
1852 // overrides a vtable entry allocated by a superclass, that the
1853 // overriding method (i.e., the callee) agree with the superclass
1854 // on each type in the method's signature.
1855 //
1856 // * klassItable::initialize_itable requires that, when a class fills
1857 // in its itables, for each non-abstract method installed in an
1858 // itable, the method (i.e., the callee) agree with the interface
1859 // on each type in the method's signature.
1860 //
1861 // All those methods have a boolean (check_access, checkconstraints)
1862 // which turns off the checks. This is used from specialized contexts
1863 // such as bootstrapping, dumping, and debugging.
1864 //
1865 // No direct constraint is placed between the class and its
1866 // supertypes. Constraints are only placed along linked relations
1867 // between callers and callees. When a method overrides or implements
1868 // an abstract method in a supertype (superclass or interface), the
1869 // constraints are placed as if the supertype were the caller to the
1870 // overriding method. (This works well, since callers to the
1871 // supertype have already established agreement between themselves and
1872 // the supertype.) As a result of all this, a class can disagree with
1873 // its supertype about the meaning of a type name, as long as that
1874 // class neither calls a relevant method of the supertype, nor is
1875 // called (perhaps via an override) from the supertype.
1876 //
1877 //
1878 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1879 //
1880 // Make sure all class components (including arrays) in the given
1881 // signature will be resolved to the same class in both loaders.
1882 // Returns the name of the type that failed a loader constraint check, or
1883 // null if no constraint failed. No exception except OOME is thrown.
1884 // Arrays are not added to the loader constraint table, their elements are.
1885 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1886 Klass* klass_being_linked,
1887 Handle loader1, Handle loader2,
1888 bool is_method) {
1889 // Nothing to do if loaders are the same.
1890 if (loader1() == loader2()) {
1891 return nullptr;
1892 }
1893
1894 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
1895 if (ss.is_reference()) {
1896 Symbol* sig = ss.as_symbol();
1897 // Note: In the future, if template-like types can take
1898 // arguments, we will want to recognize them and dig out class
1899 // names hiding inside the argument lists.
1900 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
1901 return sig;
1902 }
1903 }
1904 }
1905 return nullptr;
1906 }
1907
1908 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
1909 Symbol* signature,
1910 TRAPS) {
1911
1912 const int iid_as_int = vmIntrinsics::as_int(iid);
1913 assert(MethodHandles::is_signature_polymorphic(iid) &&
1914 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
1915 iid != vmIntrinsics::_invokeGeneric,
1916 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
1917
1918 InvokeMethodKey key(signature, iid_as_int);
1919 Method** met = nullptr;
1920
1921 // We only want one entry in the table for this (signature/id, method) pair but the code
1922 // to create the intrinsic method needs to be outside the lock.
1923 // The first thread claims the entry by adding the key and the other threads wait, until the
1924 // Method has been added as the value.
1925 {
1926 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1927 while (true) {
1928 bool created;
1929 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
1930 assert(met != nullptr, "either created or found");
1931 if (*met != nullptr) {
1932 return *met;
1933 } else if (created) {
1934 // The current thread won the race and will try to create the full entry.
1935 break;
1936 } else {
1937 // Another thread beat us to it, so wait for them to complete
1938 // and return *met; or if they hit an error we get another try.
1939 ml.wait();
1940 // Note it is not safe to read *met here as that entry could have
1941 // been deleted, so we must loop and try put_if_absent again.
1942 }
1943 }
1944 }
1945
1946 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
1947 bool throw_error = HAS_PENDING_EXCEPTION;
1948 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
1949 // Generate a compiled form of the MH intrinsic
1950 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
1951 AdapterHandlerLibrary::create_native_wrapper(m);
1952 // Check if have the compiled code.
1953 throw_error = (!m->has_compiled_code());
1954 }
1955
1956 {
1957 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1958 if (throw_error) {
1959 // Remove the entry and let another thread try, or get the same exception.
1960 bool removed = _invoke_method_intrinsic_table->remove(key);
1961 assert(removed, "must be the owner");
1962 ml.notify_all();
1963 } else {
1964 signature->make_permanent(); // The signature is never unloaded.
1965 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
1966 m->code()->entry_point() == m->from_compiled_entry()),
1967 "MH intrinsic invariant");
1968 *met = m(); // insert the element
1969 ml.notify_all();
1970 return m();
1971 }
1972 }
1973
1974 // Throw OOM or the pending exception in the JavaThread
1975 if (throw_error && !HAS_PENDING_EXCEPTION) {
1976 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
1977 "Out of space in CodeCache for method handle intrinsic");
1978 }
1979 return nullptr;
1980 }
1981
1982 #if INCLUDE_CDS
1983 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) {
1984 assert(SafepointSynchronize::is_at_safepoint(), "must be");
1985 auto do_method = [&] (InvokeMethodKey& key, Method*& m) {
1986 methods->append(m);
1987 };
1988 _invoke_method_intrinsic_table->iterate_all(do_method);
1989 }
1990
1991 void SystemDictionary::restore_archived_method_handle_intrinsics() {
1992 if (UseSharedSpaces) {
1993 EXCEPTION_MARK;
1994 restore_archived_method_handle_intrinsics_impl(THREAD);
1995 if (HAS_PENDING_EXCEPTION) {
1996 // This is probably caused by OOM -- other parts of the CDS archive have direct pointers to
1997 // the archived method handle intrinsics, so we can't really recover from this failure.
1998 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics. Try to increase heap size."));
1999 }
2000 }
2001 }
2002
2003 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) {
2004 Array<Method*>* list = AOTMetaspace::archived_method_handle_intrinsics();
2005 for (int i = 0; i < list->length(); i++) {
2006 methodHandle m(THREAD, list->at(i));
2007 Method::restore_archived_method_handle_intrinsic(m, CHECK);
2008 m->constants()->restore_unshareable_info(CHECK);
2009 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) {
2010 AdapterHandlerLibrary::create_native_wrapper(m);
2011 if (!m->has_compiled_code()) {
2012 ResourceMark rm(THREAD);
2013 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name()));
2014 }
2015 }
2016
2017 // There's no need to grab the InvokeMethodIntrinsicTable_lock, as we are still very early in
2018 // VM start-up -- in init_globals2() -- so we are still running a single Java thread. It's not
2019 // possible to have a contention.
2020 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id());
2021 InvokeMethodKey key(m->signature(), iid_as_int);
2022 bool created = _invoke_method_intrinsic_table->put(key, m());
2023 assert(created, "unexpected contention");
2024 }
2025 }
2026 #endif // INCLUDE_CDS
2027
2028 // Helper for unpacking the return value from linkMethod and linkCallSite.
2029 static Method* unpack_method_and_appendix(Handle mname,
2030 Klass* accessing_klass,
2031 objArrayHandle appendix_box,
2032 Handle* appendix_result,
2033 TRAPS) {
2034 if (mname.not_null()) {
2035 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2036 if (m != nullptr) {
2037 oop appendix = appendix_box->obj_at(0);
2038 LogTarget(Info, methodhandles) lt;
2039 if (lt.develop_is_enabled()) {
2040 ResourceMark rm(THREAD);
2041 LogStream ls(lt);
2042 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2043 m->print_on(&ls);
2044 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2045 ls.cr();
2046 }
2047
2048 (*appendix_result) = Handle(THREAD, appendix);
2049 // the target is stored in the cpCache and if a reference to this
2050 // MemberName is dropped we need a way to make sure the
2051 // class_loader containing this method is kept alive.
2052 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2053 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2054 this_key->record_dependency(m->method_holder());
2055 return mh();
2056 }
2057 }
2058 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2059 }
2060
2061 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2062 Symbol* name,
2063 Symbol* signature,
2064 Klass* accessing_klass,
2065 Handle* appendix_result,
2066 TRAPS) {
2067 guarantee(THREAD->can_call_java(), "");
2068 Handle method_type =
2069 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2070
2071 int ref_kind = JVM_REF_invokeVirtual;
2072 oop name_oop = StringTable::intern(name, CHECK_NULL);
2073 Handle name_str (THREAD, name_oop);
2074 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2075 assert(appendix_box->obj_at(0) == nullptr, "");
2076
2077 // This should not happen. JDK code should take care of that.
2078 if (accessing_klass == nullptr || method_type.is_null()) {
2079 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2080 }
2081
2082 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2083 JavaCallArguments args;
2084 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2085 args.push_int(ref_kind);
2086 args.push_oop(Handle(THREAD, klass->java_mirror()));
2087 args.push_oop(name_str);
2088 args.push_oop(method_type);
2089 args.push_oop(appendix_box);
2090 JavaValue result(T_OBJECT);
2091 JavaCalls::call_static(&result,
2092 vmClasses::MethodHandleNatives_klass(),
2093 vmSymbols::linkMethod_name(),
2094 vmSymbols::linkMethod_signature(),
2095 &args, CHECK_NULL);
2096 Handle mname(THREAD, result.get_oop());
2097 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2098 }
2099
2100 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2101 // We must ensure that all class loaders everywhere will reach this class, for any client.
2102 // This is a safe bet for public classes in java.lang, such as Object and String.
2103 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2104 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2105 static bool is_always_visible_class(oop mirror) {
2106 Klass* klass = java_lang_Class::as_Klass(mirror);
2107 if (klass->is_objArray_klass()) {
2108 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2109 }
2110 if (klass->is_typeArray_klass()) {
2111 return true; // primitive array
2112 }
2113 assert(klass->is_instance_klass(), "%s", klass->external_name());
2114 return klass->is_public() &&
2115 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2116 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2117 }
2118
2119 // Find or construct the Java mirror (java.lang.Class instance) for
2120 // the given field type signature, as interpreted relative to the
2121 // given class loader. Handles primitives, void, references, arrays,
2122 // and all other reflectable types, except method types.
2123 // N.B. Code in reflection should use this entry point.
2124 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2125 Klass* accessing_klass,
2126 SignatureStream::FailureMode failure_mode,
2127 TRAPS) {
2128
2129 Handle class_loader;
2130
2131 // What we have here must be a valid field descriptor,
2132 // and all valid field descriptors are supported.
2133 // Produce the same java.lang.Class that reflection reports.
2134 if (accessing_klass != nullptr) {
2135 class_loader = Handle(THREAD, accessing_klass->class_loader());
2136 }
2137 ResolvingSignatureStream ss(signature, class_loader, false);
2138 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2139 if (mirror_oop == nullptr) {
2140 return Handle(); // report failure this way
2141 }
2142 Handle mirror(THREAD, mirror_oop);
2143
2144 if (accessing_klass != nullptr) {
2145 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2146 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2147 if (sel_klass != nullptr) {
2148 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2149 }
2150 }
2151 return mirror;
2152 }
2153
2154
2155 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2156 // signature, as interpreted relative to the given class loader.
2157 // Because of class loader constraints, all method handle usage must be
2158 // consistent with this loader.
2159 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2160 Klass* accessing_klass,
2161 TRAPS) {
2162 Handle empty;
2163 OopHandle* o;
2164 {
2165 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2166 o = _invoke_method_type_table->get(signature);
2167 }
2168
2169 if (o != nullptr) {
2170 oop mt = o->resolve();
2171 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2172 return Handle(THREAD, mt);
2173 } else if (!THREAD->can_call_java()) {
2174 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2175 return Handle(); // do not attempt from within compiler, unless it was cached
2176 }
2177
2178 Handle class_loader;
2179 if (accessing_klass != nullptr) {
2180 class_loader = Handle(THREAD, accessing_klass->class_loader());
2181 }
2182 bool can_be_cached = true;
2183 int npts = ArgumentCount(signature).size();
2184 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2185 int arg = 0;
2186 Handle rt; // the return type from the signature
2187 ResourceMark rm(THREAD);
2188 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2189 oop mirror = nullptr;
2190 if (can_be_cached) {
2191 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2192 mirror = ss.as_java_mirror(Handle(), SignatureStream::ReturnNull, CHECK_(empty));
2193 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2194 // Fall back to accessing_klass context.
2195 can_be_cached = false;
2196 }
2197 }
2198 if (!can_be_cached) {
2199 // Resolve, throwing a real error if it doesn't work.
2200 mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2201 }
2202 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2203 if (ss.at_return_type())
2204 rt = Handle(THREAD, mirror);
2205 else
2206 pts->obj_at_put(arg++, mirror);
2207
2208 // Check accessibility.
2209 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2210 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2211 mirror = nullptr; // safety
2212 // Emulate ConstantPool::verify_constant_pool_resolve.
2213 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2214 }
2215 }
2216 assert(arg == npts, "");
2217
2218 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2219 JavaCallArguments args(Handle(THREAD, rt()));
2220 args.push_oop(pts);
2221 JavaValue result(T_OBJECT);
2222 JavaCalls::call_static(&result,
2223 vmClasses::MethodHandleNatives_klass(),
2224 vmSymbols::findMethodHandleType_name(),
2225 vmSymbols::findMethodHandleType_signature(),
2226 &args, CHECK_(empty));
2227 Handle method_type(THREAD, result.get_oop());
2228
2229 if (can_be_cached) {
2230 // We can cache this MethodType inside the JVM.
2231 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2232 bool created = false;
2233 assert(method_type != nullptr, "unexpected null");
2234 OopHandle* h = _invoke_method_type_table->get(signature);
2235 if (h == nullptr) {
2236 signature->make_permanent(); // The signature is never unloaded.
2237 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2238 bool created = _invoke_method_type_table->put(signature, elem);
2239 assert(created, "better be created");
2240 }
2241 }
2242 // report back to the caller with the MethodType
2243 return method_type;
2244 }
2245
2246 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2247 Klass* accessing_klass,
2248 TRAPS) {
2249 Handle empty;
2250 ResourceMark rm(THREAD);
2251 SignatureStream ss(signature, /*is_method=*/ false);
2252 if (!ss.is_done()) {
2253 Handle class_loader;
2254 if (accessing_klass != nullptr) {
2255 class_loader = Handle(THREAD, accessing_klass->class_loader());
2256 }
2257 oop mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2258 ss.next();
2259 if (ss.is_done()) {
2260 return Handle(THREAD, mirror);
2261 }
2262 }
2263 return empty;
2264 }
2265
2266 // Ask Java code to find or construct a method handle constant.
2267 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2268 int ref_kind, //e.g., JVM_REF_invokeVirtual
2269 Klass* callee,
2270 Symbol* name,
2271 Symbol* signature,
2272 TRAPS) {
2273 Handle empty;
2274 if (caller == nullptr) {
2275 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2276 }
2277 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2278 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2279
2280 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2281 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2282 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2283 java_lang_invoke_MemberName::set_name (mname(), name_str());
2284 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2285 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2286
2287 if (ref_kind == JVM_REF_invokeVirtual &&
2288 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2289 // Skip resolution for public signature polymorphic methods such as
2290 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2291 // They require appendix argument which MemberName resolution doesn't handle.
2292 // There's special logic on JDK side to handle them
2293 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2294 } else {
2295 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2296 }
2297
2298 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2299 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2300
2301 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2302 JavaCallArguments args;
2303 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2304 args.push_int(ref_kind);
2305 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2306 args.push_oop(name_str);
2307 args.push_oop(type);
2308 JavaValue result(T_OBJECT);
2309 JavaCalls::call_static(&result,
2310 vmClasses::MethodHandleNatives_klass(),
2311 vmSymbols::linkMethodHandleConstant_name(),
2312 vmSymbols::linkMethodHandleConstant_signature(),
2313 &args, CHECK_(empty));
2314 return Handle(THREAD, result.get_oop());
2315 }
2316
2317 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2318 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2319 // with linkage results being stored back into the bootstrap specifier.
2320 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2321 // Resolve the bootstrap specifier, its name, type, and static arguments
2322 bootstrap_specifier.resolve_bsm(CHECK);
2323
2324 // This should not happen. JDK code should take care of that.
2325 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2326 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2327 }
2328
2329 bool is_indy = bootstrap_specifier.is_method_call();
2330 objArrayHandle appendix_box;
2331 if (is_indy) {
2332 // Some method calls may require an appendix argument. Arrange to receive it.
2333 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2334 assert(appendix_box->obj_at(0) == nullptr, "");
2335 }
2336
2337 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2338 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2339 JavaCallArguments args;
2340 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2341 args.push_oop(bootstrap_specifier.bsm());
2342 args.push_oop(bootstrap_specifier.name_arg());
2343 args.push_oop(bootstrap_specifier.type_arg());
2344 args.push_oop(bootstrap_specifier.arg_values());
2345 if (is_indy) {
2346 args.push_oop(appendix_box);
2347 }
2348 JavaValue result(T_OBJECT);
2349 JavaCalls::call_static(&result,
2350 vmClasses::MethodHandleNatives_klass(),
2351 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2352 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2353 &args, CHECK);
2354
2355 Handle value(THREAD, result.get_oop());
2356 if (is_indy) {
2357 Handle appendix;
2358 Method* method = unpack_method_and_appendix(value,
2359 bootstrap_specifier.caller(),
2360 appendix_box,
2361 &appendix, CHECK);
2362 methodHandle mh(THREAD, method);
2363 bootstrap_specifier.set_resolved_method(mh, appendix);
2364 } else {
2365 bootstrap_specifier.set_resolved_value(value);
2366 }
2367
2368 // sanity check
2369 assert(bootstrap_specifier.is_resolved() ||
2370 (bootstrap_specifier.is_method_call() &&
2371 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2372 }
2373
2374
2375 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2376 assert(m != nullptr, "Unexpected nullptr Method*");
2377 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2378 }
2379
2380 // ----------------------------------------------------------------------------
2381
2382 void SystemDictionary::print_on(outputStream *st) {
2383 CDS_ONLY(SystemDictionaryShared::print_on(st));
2384 GCMutexLocker mu(SystemDictionary_lock);
2385
2386 ClassLoaderDataGraph::print_dictionary(st);
2387
2388 // Placeholders
2389 PlaceholderTable::print_on(st);
2390 st->cr();
2391
2392 // loader constraints - print under SD_lock
2393 LoaderConstraintTable::print_on(st);
2394 st->cr();
2395 }
2396
2397 void SystemDictionary::print() { print_on(tty); }
2398
2399 void SystemDictionary::verify() {
2400
2401 GCMutexLocker mu(SystemDictionary_lock);
2402
2403 // Verify dictionary
2404 ClassLoaderDataGraph::verify_dictionary();
2405
2406 // Verify constraint table
2407 LoaderConstraintTable::verify();
2408 }
2409
2410 void SystemDictionary::dump(outputStream *st, bool verbose) {
2411 assert_locked_or_safepoint(SystemDictionary_lock);
2412 if (verbose) {
2413 print_on(st);
2414 } else {
2415 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2416 ClassLoaderDataGraph::print_table_statistics(st);
2417 LoaderConstraintTable::print_table_statistics(st);
2418 }
2419 }
2420
2421 // Utility for dumping dictionaries.
2422 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2423 DCmdWithParser(output, heap),
2424 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2425 "BOOLEAN", false, "false") {
2426 _dcmdparser.add_dcmd_option(&_verbose);
2427 }
2428
2429 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2430 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2431 _verbose.value());
2432 VMThread::execute(&dumper);
2433 }