1 /*
2 * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/cdsConfig.hpp"
27 #include "cds/heapShared.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/classLoaderExt.hpp"
34 #include "classfile/classLoadInfo.hpp"
35 #include "classfile/dictionary.hpp"
36 #include "classfile/javaClasses.inline.hpp"
37 #include "classfile/klassFactory.hpp"
38 #include "classfile/loaderConstraints.hpp"
39 #include "classfile/packageEntry.hpp"
40 #include "classfile/placeholders.hpp"
41 #include "classfile/protectionDomainCache.hpp"
42 #include "classfile/resolutionErrors.hpp"
43 #include "classfile/stringTable.hpp"
44 #include "classfile/symbolTable.hpp"
45 #include "classfile/systemDictionary.hpp"
46 #include "classfile/vmClasses.hpp"
47 #include "classfile/vmSymbols.hpp"
48 #include "gc/shared/gcTraceTime.inline.hpp"
49 #include "interpreter/bootstrapInfo.hpp"
50 #include "jfr/jfrEvents.hpp"
51 #include "jvm.h"
52 #include "logging/log.hpp"
53 #include "logging/logStream.hpp"
54 #include "memory/metaspaceClosure.hpp"
55 #include "memory/oopFactory.hpp"
56 #include "memory/resourceArea.hpp"
57 #include "memory/universe.hpp"
58 #include "oops/access.inline.hpp"
59 #include "oops/instanceKlass.hpp"
60 #include "oops/klass.inline.hpp"
61 #include "oops/method.inline.hpp"
62 #include "oops/objArrayKlass.hpp"
63 #include "oops/objArrayOop.inline.hpp"
64 #include "oops/oop.inline.hpp"
65 #include "oops/oop.hpp"
66 #include "oops/oopHandle.hpp"
67 #include "oops/oopHandle.inline.hpp"
68 #include "oops/symbol.hpp"
69 #include "oops/typeArrayKlass.hpp"
70 #include "prims/jvmtiExport.hpp"
71 #include "prims/methodHandles.hpp"
72 #include "runtime/arguments.hpp"
73 #include "runtime/atomic.hpp"
74 #include "runtime/handles.inline.hpp"
75 #include "runtime/java.hpp"
76 #include "runtime/javaCalls.hpp"
77 #include "runtime/mutexLocker.hpp"
78 #include "runtime/sharedRuntime.hpp"
79 #include "runtime/signature.hpp"
80 #include "runtime/synchronizer.hpp"
81 #include "services/classLoadingService.hpp"
82 #include "services/diagnosticCommand.hpp"
83 #include "services/finalizerService.hpp"
84 #include "services/threadService.hpp"
85 #include "utilities/macros.hpp"
86 #include "utilities/utf8.hpp"
87 #if INCLUDE_CDS
88 #include "classfile/systemDictionaryShared.hpp"
89 #endif
90 #if INCLUDE_JFR
91 #include "jfr/jfr.hpp"
92 #endif
93
94 class InvokeMethodKey : public StackObj {
95 private:
96 Symbol* _symbol;
97 intptr_t _iid;
98
99 public:
100 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
101 _symbol(symbol),
102 _iid(iid) {}
103
104 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
105 return k1._symbol == k2._symbol && k1._iid == k2._iid;
106 }
107
108 static unsigned int compute_hash(const InvokeMethodKey &k) {
109 Symbol* sym = k._symbol;
110 intptr_t iid = k._iid;
111 unsigned int hash = (unsigned int) sym -> identity_hash();
112 return (unsigned int) (hash ^ iid);
113 }
114
115 };
116
117 using InvokeMethodIntrinsicTable = ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
118 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
119 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
120 using InvokeMethodTypeTable = ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
121 static InvokeMethodTypeTable* _invoke_method_type_table;
122
123 OopHandle SystemDictionary::_java_system_loader;
124 OopHandle SystemDictionary::_java_platform_loader;
125
126 // ----------------------------------------------------------------------------
127 // Java-level SystemLoader and PlatformLoader
128 oop SystemDictionary::java_system_loader() {
129 return _java_system_loader.resolve();
130 }
131
132 oop SystemDictionary::java_platform_loader() {
133 return _java_platform_loader.resolve();
134 }
135
136 void SystemDictionary::compute_java_loaders(TRAPS) {
137 if (_java_system_loader.is_empty()) {
138 oop system_loader = get_system_class_loader_impl(CHECK);
139 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
140 } else {
141 // It must have been restored from the archived module graph
142 assert(UseSharedSpaces, "must be");
143 assert(CDSConfig::is_loading_full_module_graph(), "must be");
144 DEBUG_ONLY(
145 oop system_loader = get_system_class_loader_impl(CHECK);
146 assert(_java_system_loader.resolve() == system_loader, "must be");
147 )
148 }
149
150 if (_java_platform_loader.is_empty()) {
151 oop platform_loader = get_platform_class_loader_impl(CHECK);
152 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
153 } else {
154 // It must have been restored from the archived module graph
155 assert(UseSharedSpaces, "must be");
156 assert(CDSConfig::is_loading_full_module_graph(), "must be");
157 DEBUG_ONLY(
158 oop platform_loader = get_platform_class_loader_impl(CHECK);
159 assert(_java_platform_loader.resolve() == platform_loader, "must be");
160 )
161 }
162 }
163
164 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
165 JavaValue result(T_OBJECT);
166 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
167 JavaCalls::call_static(&result,
168 class_loader_klass,
169 vmSymbols::getSystemClassLoader_name(),
170 vmSymbols::void_classloader_signature(),
171 CHECK_NULL);
172 return result.get_oop();
173 }
174
175 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
176 JavaValue result(T_OBJECT);
177 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
178 JavaCalls::call_static(&result,
179 class_loader_klass,
180 vmSymbols::getPlatformClassLoader_name(),
181 vmSymbols::void_classloader_signature(),
182 CHECK_NULL);
183 return result.get_oop();
184 }
185
186 // Helper function
187 inline ClassLoaderData* class_loader_data(Handle class_loader) {
188 return ClassLoaderData::class_loader_data(class_loader());
189 }
190
191 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
192 if (create_mirror_cld) {
193 // Add a new class loader data to the graph.
194 return ClassLoaderDataGraph::add(class_loader, true);
195 } else {
196 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
197 ClassLoaderDataGraph::find_or_create(class_loader);
198 }
199 }
200
201 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
202 assert(_java_system_loader.is_empty(), "already set!");
203 _java_system_loader = cld->class_loader_handle();
204
205 }
206
207 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
208 assert(_java_platform_loader.is_empty(), "already set!");
209 _java_platform_loader = cld->class_loader_handle();
210 }
211
212 // ----------------------------------------------------------------------------
213 // Parallel class loading check
214
215 bool is_parallelCapable(Handle class_loader) {
216 if (class_loader.is_null()) return true;
217 return java_lang_ClassLoader::parallelCapable(class_loader());
218 }
219 // ----------------------------------------------------------------------------
220 // ParallelDefineClass flag does not apply to bootclass loader
221 bool is_parallelDefine(Handle class_loader) {
222 if (class_loader.is_null()) return false;
223 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
224 return true;
225 }
226 return false;
227 }
228
229 // Returns true if the passed class loader is the builtin application class loader
230 // or a custom system class loader. A customer system class loader can be
231 // specified via -Djava.system.class.loader.
232 bool SystemDictionary::is_system_class_loader(oop class_loader) {
233 if (class_loader == nullptr) {
234 return false;
235 }
236 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
237 class_loader == _java_system_loader.peek());
238 }
239
240 // Returns true if the passed class loader is the platform class loader.
241 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
242 if (class_loader == nullptr) {
243 return false;
244 }
245 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
246 }
247
248 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
249 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
250 if (is_parallelCapable(class_loader)) {
251 return Handle();
252 } else {
253 return class_loader;
254 }
255 }
256
257 // ----------------------------------------------------------------------------
258 // Resolving of classes
259
260 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
261 if (name == nullptr) {
262 THROW_MSG_0(exception, "No class name given");
263 }
264 if ((int)strlen(name) > Symbol::max_length()) {
265 // It's impossible to create this class; the name cannot fit
266 // into the constant pool.
267 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
268 "Class name exceeds maximum length of %d: %s",
269 Symbol::max_length(),
270 name);
271 return nullptr;
272 }
273 // Callers should ensure that the name is never an illegal UTF8 string.
274 assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false),
275 "Class name is not a valid utf8 string.");
276
277 // Make a new symbol for the class name.
278 return SymbolTable::new_symbol(name);
279 }
280
281 #ifdef ASSERT
282 // Used to verify that class loading succeeded in adding k to the dictionary.
283 void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
284 MutexLocker mu(SystemDictionary_lock);
285 ClassLoaderData* loader_data = k->class_loader_data();
286 Dictionary* dictionary = loader_data->dictionary();
287 assert(class_name == k->name(), "Must be the same");
288 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
289 assert(kk == k, "should be present in dictionary");
290 }
291 #endif
292
293 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
294 if (HAS_PENDING_EXCEPTION) {
295 // If we have a pending exception we forward it to the caller, unless throw_error is true,
296 // in which case we have to check whether the pending exception is a ClassNotFoundException,
297 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
298 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
299 ResourceMark rm(THREAD);
300 Handle e(THREAD, PENDING_EXCEPTION);
301 CLEAR_PENDING_EXCEPTION;
302 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
303 } else {
304 return; // the caller will throw the incoming exception
305 }
306 }
307 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
308 // error or exception depending on the value of throw_error.
309 ResourceMark rm(THREAD);
310 if (throw_error) {
311 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
312 } else {
313 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
314 }
315 }
316
317 // Forwards to resolve_or_null
318
319 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
320 bool throw_error, TRAPS) {
321 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
322 // Check for pending exception or null klass, and throw exception
323 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
324 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
325 }
326 return klass;
327 }
328
329 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
330
331 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
332 if (Signature::is_array(class_name)) {
333 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
334 } else {
335 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
336 if (Signature::has_envelope(class_name)) {
337 ResourceMark rm(THREAD);
338 // Ignore wrapping L and ;.
339 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
340 class_name->utf8_length() - 2);
341 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
342 } else {
343 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
344 }
345 }
346 }
347
348 // Forwards to resolve_instance_class_or_null
349
350 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
351 Handle class_loader,
352 Handle protection_domain,
353 TRAPS) {
354 assert(Signature::is_array(class_name), "must be array");
355 ResourceMark rm(THREAD);
356 SignatureStream ss(class_name, false);
357 int ndims = ss.skip_array_prefix(); // skip all '['s
358 Klass* k = nullptr;
359 BasicType t = ss.type();
360 if (ss.has_envelope()) {
361 Symbol* obj_class = ss.as_symbol();
362 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
363 class_loader,
364 protection_domain,
365 CHECK_NULL);
366 if (k != nullptr) {
367 k = k->array_klass(ndims, CHECK_NULL);
368 }
369 } else {
370 k = Universe::typeArrayKlassObj(t);
371 k = TypeArrayKlass::cast(k)->array_klass(ndims, CHECK_NULL);
372 }
373 return k;
374 }
375
376 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
377 LogTarget(Debug, class, load, placeholders) lt;
378 if (lt.is_enabled()) {
379 ResourceMark rm;
380 LogStream ls(lt);
381 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
382 probe->print_on(&ls);
383 ls.cr();
384 }
385 }
386
387 // Must be called for any superclass or superinterface resolution
388 // during class definition to allow class circularity checking
389 // superinterface callers:
390 // parse_interfaces - from defineClass
391 // superclass callers:
392 // ClassFileParser - from defineClass
393 // load_shared_class - while loading a class from shared archive
394 // resolve_instance_class_or_null:
395 // via: handle_parallel_super_load
396 // when resolving a class that has an existing placeholder with
397 // a saved superclass [i.e. a defineClass is currently in progress]
398 // If another thread is trying to resolve the class, it must do
399 // superclass checks on its own thread to catch class circularity and
400 // to avoid deadlock.
401 //
402 // resolve_super_or_fail adds a LOAD_SUPER placeholder to the placeholder table before calling
403 // resolve_instance_class_or_null. ClassCircularityError is detected when a LOAD_SUPER or LOAD_INSTANCE
404 // placeholder for the same thread, class, classloader is found.
405 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
406 //
407 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* class_name,
408 Symbol* super_name,
409 Handle class_loader,
410 Handle protection_domain,
411 bool is_superclass,
412 TRAPS) {
413
414 assert(super_name != nullptr, "null superclass for resolving");
415 assert(!Signature::is_array(super_name), "invalid superclass name");
416 #if INCLUDE_CDS
417 if (CDSConfig::is_dumping_static_archive()) {
418 // Special processing for handling UNREGISTERED shared classes.
419 InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
420 super_name, is_superclass);
421 if (k) {
422 return k;
423 }
424 }
425 #endif // INCLUDE_CDS
426
427 // If klass is already loaded, just return the superclass or superinterface.
428 // Make sure there's a placeholder for the class_name before resolving.
429 // This is used as a claim that this thread is currently loading superclass/classloader
430 // and for ClassCircularity checks.
431
432 ClassLoaderData* loader_data = class_loader_data(class_loader);
433 Dictionary* dictionary = loader_data->dictionary();
434
435 // can't throw error holding a lock
436 bool throw_circularity_error = false;
437 {
438 MutexLocker mu(THREAD, SystemDictionary_lock);
439 InstanceKlass* klassk = dictionary->find_class(THREAD, class_name);
440 InstanceKlass* quicksuperk;
441 // To support parallel loading: if class is done loading, just return the superclass
442 // if the super_name matches class->super()->name() and if the class loaders match.
443 // Otherwise, a LinkageError will be thrown later.
444 if (klassk != nullptr && is_superclass &&
445 ((quicksuperk = klassk->java_super()) != nullptr) &&
446 ((quicksuperk->name() == super_name) &&
447 (quicksuperk->class_loader() == class_loader()))) {
448 return quicksuperk;
449 } else {
450 // Must check ClassCircularity before checking if superclass is already loaded.
451 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
452 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
453 log_circularity_error(class_name, probe);
454 throw_circularity_error = true;
455 }
456 }
457
458 if (!throw_circularity_error) {
459 // Be careful not to exit resolve_super without removing this placeholder.
460 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
461 loader_data,
462 PlaceholderTable::LOAD_SUPER,
463 super_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(super_name,
475 class_loader,
476 protection_domain,
477 THREAD);
478
479 // Clean up placeholder entry.
480 {
481 MutexLocker mu(THREAD, SystemDictionary_lock);
482 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
483 SystemDictionary_lock->notify_all();
484 }
485
486 // Check for pending exception or null superk, and throw exception
487 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
488 handle_resolution_exception(super_name, true, CHECK_NULL);
489 }
490
491 return superk;
492 }
493
494 // If the class in is in the placeholder table, class loading is in progress.
495 // For cases where the application changes threads to load classes, it
496 // is critical to ClassCircularity detection that we try loading
497 // the superclass on the new thread internally, so we do parallel
498 // superclass loading here. This avoids deadlock for ClassCircularity
499 // detection for parallelCapable class loaders that lock on a per-class lock.
500 static void handle_parallel_super_load(Symbol* name,
501 Symbol* superclassname,
502 Handle class_loader,
503 Handle protection_domain, TRAPS) {
504
505 // superk is not used; resolve_super_or_fail is called for circularity check only.
506 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
507 superclassname,
508 class_loader,
509 protection_domain,
510 true,
511 CHECK);
512 }
513
514 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
515 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
516 static bool needs_load_placeholder(Handle class_loader) {
517 return class_loader.is_null() || !is_parallelCapable(class_loader);
518 }
519
520 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
521 static InstanceKlass* handle_parallel_loading(JavaThread* current,
522 Symbol* name,
523 ClassLoaderData* loader_data,
524 bool must_wait_for_class_loading,
525 bool* throw_circularity_error) {
526 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
527 if (oldprobe != nullptr) {
528 // -Xcomp calls load_signature_classes which might result in loading
529 // a class that's already in the process of loading, so we detect CCE here also.
530 // Only need check_seen_thread once, not on each loop
531 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
532 log_circularity_error(name, oldprobe);
533 *throw_circularity_error = true;
534 return nullptr;
535 } else if (must_wait_for_class_loading) {
536 // Wait until the first thread has finished loading this class. Also wait until all the
537 // threads trying to load its superclass have removed their placeholders.
538 while (oldprobe != nullptr &&
539 (oldprobe->instance_load_in_progress() || oldprobe->super_load_in_progress())) {
540
541 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
542 // for the bootclass loader.
543 SystemDictionary_lock->wait();
544
545 // Check if classloading completed while we were waiting
546 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
547 if (check != nullptr) {
548 // Klass is already loaded, so just return it
549 return check;
550 }
551 // check if other thread failed to load and cleaned up
552 oldprobe = PlaceholderTable::get_entry(name, loader_data);
553 }
554 }
555 }
556 return nullptr;
557 }
558
559 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
560 assert(event != nullptr, "invariant");
561 assert(k != nullptr, "invariant");
562 event->set_loadedClass(k);
563 event->set_definingClassLoader(k->class_loader_data());
564 event->set_initiatingClassLoader(init_cld);
565 event->commit();
566 }
567
568 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
569 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
570 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
571 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
572 // This can return null, an exception or an InstanceKlass.
573 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
574 Handle class_loader,
575 Handle protection_domain,
576 TRAPS) {
577 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
578 assert(name != nullptr && !Signature::is_array(name) &&
579 !Signature::has_envelope(name), "invalid class name");
580
581 EventClassLoad class_load_start_event;
582
583 HandleMark hm(THREAD);
584
585 // Fix for 4474172; see evaluation for more details
586 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
587 ClassLoaderData* loader_data = register_loader(class_loader);
588 Dictionary* dictionary = loader_data->dictionary();
589
590 // Do lookup to see if class already exists and the protection domain
591 // has the right access.
592 // This call uses find which checks protection domain already matches
593 // All subsequent calls use find_class, and set loaded_class so that
594 // before we return a result, we call out to java to check for valid protection domain.
595 InstanceKlass* probe = dictionary->find(THREAD, name, protection_domain);
596 if (probe != nullptr) return probe;
597
598 // Non-bootstrap class loaders will call out to class loader and
599 // define via jvm/jni_DefineClass which will acquire the
600 // class loader object lock to protect against multiple threads
601 // defining the class in parallel by accident.
602 // This lock must be acquired here so the waiter will find
603 // any successful result in the SystemDictionary and not attempt
604 // the define.
605 // ParallelCapable class loaders and the bootstrap classloader
606 // do not acquire lock here.
607 Handle lockObject = get_loader_lock_or_null(class_loader);
608 ObjectLocker ol(lockObject, THREAD);
609
610 bool super_load_in_progress = false;
611 InstanceKlass* loaded_class = nullptr;
612 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
613
614 guarantee(THREAD->can_call_java(),
615 "can not load classes with compiler thread: class=%s, classloader=%s",
616 name->as_C_string(),
617 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
618
619 // Check again (after locking) if the class already exists in SystemDictionary
620 {
621 MutexLocker mu(THREAD, SystemDictionary_lock);
622 InstanceKlass* check = dictionary->find_class(THREAD, name);
623 if (check != nullptr) {
624 // InstanceKlass is already loaded, but we still need to check protection domain below.
625 loaded_class = check;
626 } else {
627 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
628 if (placeholder != nullptr && placeholder->super_load_in_progress()) {
629 super_load_in_progress = true;
630 superclassname = placeholder->supername();
631 assert(superclassname != nullptr, "superclass has to have a name");
632 }
633 }
634 }
635
636 // If the class is in the placeholder table with super_class set,
637 // handle superclass loading in progress.
638 if (super_load_in_progress) {
639 handle_parallel_super_load(name, superclassname,
640 class_loader,
641 protection_domain,
642 CHECK_NULL);
643 }
644
645 bool throw_circularity_error = false;
646 if (loaded_class == nullptr) {
647 bool load_placeholder_added = false;
648
649 // Add placeholder entry to record loading instance class
650 // case 1. Bootstrap classloader
651 // This classloader supports parallelism at the classloader level
652 // but only allows a single thread to load a class/classloader pair.
653 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
654 // case 2. parallelCapable user level classloaders
655 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
656 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
657 // case 3. traditional classloaders that rely on the classloader object lock
658 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
659 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
660 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
661 {
662 MutexLocker mu(THREAD, SystemDictionary_lock);
663 if (needs_load_placeholder(class_loader)) {
664 loaded_class = handle_parallel_loading(THREAD,
665 name,
666 loader_data,
667 class_loader.is_null(),
668 &throw_circularity_error);
669 }
670
671 // Recheck if the class has been loaded for all class loader cases and
672 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
673 if (!throw_circularity_error && loaded_class == nullptr) {
674 InstanceKlass* check = dictionary->find_class(THREAD, name);
675 if (check != nullptr) {
676 loaded_class = check;
677 } else if (needs_load_placeholder(class_loader)) {
678 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
679 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
680 PlaceholderTable::LOAD_INSTANCE,
681 nullptr,
682 THREAD);
683 load_placeholder_added = true;
684 }
685 }
686 }
687
688 // Must throw error outside of owning lock
689 if (throw_circularity_error) {
690 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
691 ResourceMark rm(THREAD);
692 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
693 }
694
695 // Be careful when modifying this code: once you have run
696 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
697 // you need to find_and_remove it before returning.
698 // So be careful to not exit with a CHECK_ macro between these calls.
699
700 if (loaded_class == nullptr) {
701 // Do actual loading
702 loaded_class = load_instance_class(name, class_loader, THREAD);
703 }
704
705 if (load_placeholder_added) {
706 // clean up placeholder entries for LOAD_INSTANCE success or error
707 // This brackets the SystemDictionary updates for both defining
708 // and initiating loaders
709 MutexLocker mu(THREAD, SystemDictionary_lock);
710 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
711 SystemDictionary_lock->notify_all();
712 }
713 }
714
715 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
716 return nullptr;
717 }
718
719 if (class_load_start_event.should_commit()) {
720 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
721 }
722
723 // Make sure we have the right class in the dictionary
724 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
725
726 // Check if the protection domain is present it has the right access
727 if (protection_domain() != nullptr) {
728 // Verify protection domain. If it fails an exception is thrown
729 dictionary->validate_protection_domain(loaded_class, class_loader, protection_domain, CHECK_NULL);
730 }
731
732 return loaded_class;
733 }
734
735
736 // This routine does not lock the system dictionary.
737 //
738 // Since readers don't hold a lock, we must make sure that system
739 // dictionary entries are added to in a safe way (all links must
740 // be updated in an MT-safe manner). All entries are removed during class
741 // unloading, when this class loader is no longer referenced.
742 //
743 // Callers should be aware that an entry could be added just after
744 // Dictionary is read here, so the caller will not see
745 // the new entry.
746
747 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
748 Symbol* class_name,
749 Handle class_loader,
750 Handle protection_domain) {
751
752 // The result of this call should be consistent with the result
753 // of the call to resolve_instance_class_or_null().
754 // See evaluation 6790209 and 4474172 for more details.
755 oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
756 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
757
758 if (loader_data == nullptr) {
759 // If the ClassLoaderData has not been setup,
760 // then the class loader has no entries in the dictionary.
761 return nullptr;
762 }
763
764 Dictionary* dictionary = loader_data->dictionary();
765 return dictionary->find(current, class_name, protection_domain);
766 }
767
768 // Look for a loaded instance or array klass by name. Do not do any loading.
769 // return null in case of error.
770 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
771 Symbol* class_name,
772 Handle class_loader,
773 Handle protection_domain) {
774 Klass* k = nullptr;
775 assert(class_name != nullptr, "class name must be non nullptr");
776
777 if (Signature::is_array(class_name)) {
778 // The name refers to an array. Parse the name.
779 // dimension and object_key in FieldArrayInfo are assigned as a
780 // side-effect of this call
781 SignatureStream ss(class_name, false);
782 int ndims = ss.skip_array_prefix(); // skip all '['s
783 BasicType t = ss.type();
784 if (t != T_OBJECT) {
785 k = Universe::typeArrayKlassObj(t);
786 } else {
787 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader, protection_domain);
788 }
789 if (k != nullptr) {
790 k = k->array_klass_or_null(ndims);
791 }
792 } else {
793 k = find_instance_klass(current, class_name, class_loader, protection_domain);
794 }
795 return k;
796 }
797
798 // Note: this method is much like resolve_class_from_stream, but
799 // does not publish the classes in the SystemDictionary.
800 // Handles Lookup.defineClass hidden.
801 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
802 ClassFileStream* st,
803 Symbol* class_name,
804 Handle class_loader,
805 const ClassLoadInfo& cl_info,
806 TRAPS) {
807
808 EventClassLoad class_load_start_event;
809 ClassLoaderData* loader_data;
810
811 // - for hidden classes that are not strong: create a new CLD that has a class holder and
812 // whose loader is the Lookup class's loader.
813 // - for hidden class: add the class to the Lookup class's loader's CLD.
814 assert (cl_info.is_hidden(), "only used for hidden classes");
815 bool create_mirror_cld = !cl_info.is_strong_hidden();
816 loader_data = register_loader(class_loader, create_mirror_cld);
817
818 assert(st != nullptr, "invariant");
819 assert(st->need_verify(), "invariant");
820
821 // Parse stream and create a klass.
822 InstanceKlass* k = KlassFactory::create_from_stream(st,
823 class_name,
824 loader_data,
825 cl_info,
826 CHECK_NULL);
827 assert(k != nullptr, "no klass created");
828
829 // Hidden classes that are not strong must update ClassLoaderData holder
830 // so that they can be unloaded when the mirror is no longer referenced.
831 if (!cl_info.is_strong_hidden()) {
832 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
833 }
834
835 // Add to class hierarchy, and do possible deoptimizations.
836 k->add_to_hierarchy(THREAD);
837 // But, do not add to dictionary.
838
839 k->link_class(CHECK_NULL);
840
841 // notify jvmti
842 if (JvmtiExport::should_post_class_load()) {
843 JvmtiExport::post_class_load(THREAD, k);
844 }
845 if (class_load_start_event.should_commit()) {
846 post_class_load_event(&class_load_start_event, k, loader_data);
847 }
848
849 return k;
850 }
851
852 // Add a klass to the system from a stream (called by jni_DefineClass and
853 // JVM_DefineClass).
854 // Note: class_name can be null. In that case we do not know the name of
855 // the class until we have parsed the stream.
856 // This function either returns an InstanceKlass or throws an exception. It does
857 // not return null without a pending exception.
858 InstanceKlass* SystemDictionary::resolve_class_from_stream(
859 ClassFileStream* st,
860 Symbol* class_name,
861 Handle class_loader,
862 const ClassLoadInfo& cl_info,
863 TRAPS) {
864
865 HandleMark hm(THREAD);
866
867 ClassLoaderData* loader_data = register_loader(class_loader);
868
869 // Classloaders that support parallelism, e.g. bootstrap classloader,
870 // do not acquire lock here
871 Handle lockObject = get_loader_lock_or_null(class_loader);
872 ObjectLocker ol(lockObject, THREAD);
873
874 // Parse the stream and create a klass.
875 // Note that we do this even though this klass might
876 // already be present in the SystemDictionary, otherwise we would not
877 // throw potential ClassFormatErrors.
878 InstanceKlass* k = nullptr;
879
880 #if INCLUDE_CDS
881 if (!CDSConfig::is_dumping_static_archive()) {
882 k = SystemDictionaryShared::lookup_from_stream(class_name,
883 class_loader,
884 cl_info.protection_domain(),
885 st,
886 CHECK_NULL);
887 }
888 #endif
889
890 if (k == nullptr) {
891 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
892 }
893
894 assert(k != nullptr, "no klass created");
895 Symbol* h_name = k->name();
896 assert(class_name == nullptr || class_name == h_name, "name mismatch");
897
898 // Add class just loaded
899 // If a class loader supports parallel classloading, handle parallel define requests.
900 // find_or_define_instance_class may return a different InstanceKlass,
901 // in which case the old k would be deallocated
902 if (is_parallelCapable(class_loader)) {
903 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
904 } else {
905 define_instance_class(k, class_loader, THREAD);
906
907 // If defining the class throws an exception register 'k' for cleanup.
908 if (HAS_PENDING_EXCEPTION) {
909 assert(k != nullptr, "Must have an instance klass here!");
910 loader_data->add_to_deallocate_list(k);
911 return nullptr;
912 }
913 }
914
915 // Make sure we have an entry in the SystemDictionary on success
916 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
917
918 return k;
919 }
920
921 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
922 Symbol* class_name,
923 Handle class_loader,
924 const ClassLoadInfo& cl_info,
925 TRAPS) {
926 if (cl_info.is_hidden()) {
927 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
928 } else {
929 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
930 }
931 }
932
933
934 #if INCLUDE_CDS
935 // Check if a shared class can be loaded by the specific classloader.
936 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
937 InstanceKlass* ik,
938 PackageEntry* pkg_entry,
939 Handle class_loader) {
940 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
941 "Cannot use sharing if java.base is patched");
942
943 // (1) Check if we are loading into the same loader as in dump time.
944
945 if (ik->is_shared_boot_class()) {
946 if (class_loader() != nullptr) {
947 return false;
948 }
949 } else if (ik->is_shared_platform_class()) {
950 if (class_loader() != java_platform_loader()) {
951 return false;
952 }
953 } else if (ik->is_shared_app_class()) {
954 if (class_loader() != java_system_loader()) {
955 return false;
956 }
957 } else {
958 // ik was loaded by a custom loader during dump time
959 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
960 return false;
961 } else {
962 return true;
963 }
964 }
965
966 // (2) Check if we are loading into the same module from the same location as in dump time.
967
968 if (MetaspaceShared::use_optimized_module_handling()) {
969 // Class visibility has not changed between dump time and run time, so a class
970 // that was visible (and thus archived) during dump time is always visible during runtime.
971 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
972 "visibility cannot change between dump time and runtime");
973 return true;
974 }
975 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
976 }
977
978 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
979 InstanceKlass* ik,
980 PackageEntry* pkg_entry,
981 Handle class_loader) {
982 int scp_index = ik->shared_classpath_index();
983 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
984 assert(scp_index >= 0, "must be");
985 SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
986 if (!Universe::is_module_initialized()) {
987 assert(scp_entry != nullptr, "must be");
988 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
989 // has restricted the classes can be loaded at this step to be only:
990 // [1] scp_entry->is_modules_image(): classes in java.base, or,
991 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
992 assert(scp_entry->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
993 "only these classes can be loaded before the module system is initialized");
994 assert(class_loader.is_null(), "sanity");
995 return true;
996 }
997
998 if (pkg_entry == nullptr) {
999 // We might have looked up pkg_entry before the module system was initialized.
1000 // Need to reload it now.
1001 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1002 if (pkg_name != nullptr) {
1003 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1004 }
1005 }
1006
1007 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1008 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1009 bool was_archived_from_named_module = scp_entry->in_named_module();
1010 bool visible;
1011
1012 if (was_archived_from_named_module) {
1013 if (should_be_in_named_module) {
1014 // Is the module loaded from the same location as during dump time?
1015 visible = mod_entry->shared_path_index() == scp_index;
1016 if (visible) {
1017 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1018 }
1019 } else {
1020 // During dump time, this class was in a named module, but at run time, this class should be
1021 // in an unnamed module.
1022 visible = false;
1023 }
1024 } else {
1025 if (should_be_in_named_module) {
1026 // During dump time, this class was in an unnamed, but at run time, this class should be
1027 // in a named module.
1028 visible = false;
1029 } else {
1030 visible = true;
1031 }
1032 }
1033
1034 return visible;
1035 }
1036
1037 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1038 Handle class_loader, Handle protection_domain,
1039 bool is_superclass, TRAPS) {
1040 assert(super_type->is_shared(), "must be");
1041
1042 // Quick check if the super type has been already loaded.
1043 // + Don't do it for unregistered classes -- they can be unloaded so
1044 // super_type->class_loader_data() could be stale.
1045 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1046 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {
1047 // Check if the superclass is loaded by the current class_loader
1048 Symbol* name = super_type->name();
1049 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader, protection_domain);
1050 if (check == super_type) {
1051 return true;
1052 }
1053 }
1054
1055 Klass *found = resolve_super_or_fail(klass->name(), super_type->name(),
1056 class_loader, protection_domain, is_superclass, CHECK_0);
1057 if (found == super_type) {
1058 return true;
1059 } else {
1060 // The dynamically resolved super type is not the same as the one we used during dump time,
1061 // so we cannot use the class.
1062 return false;
1063 }
1064 }
1065
1066 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1067 Handle protection_domain, TRAPS) {
1068 // Check the superclass and interfaces. They must be the same
1069 // as in dump time, because the layout of <ik> depends on
1070 // the specific layout of ik->super() and ik->local_interfaces().
1071 //
1072 // If unexpected superclass or interfaces are found, we cannot
1073 // load <ik> from the shared archive.
1074
1075 if (ik->super() != nullptr &&
1076 !check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1077 class_loader, protection_domain, true, THREAD)) {
1078 return false;
1079 }
1080
1081 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1082 int num_interfaces = interfaces->length();
1083 for (int index = 0; index < num_interfaces; index++) {
1084 if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) {
1085 return false;
1086 }
1087 }
1088
1089 return true;
1090 }
1091
1092 InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1093 Handle class_loader,
1094 Handle protection_domain,
1095 PackageEntry* pkg_entry,
1096 TRAPS) {
1097 InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1098 assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1099 Symbol* cn = shared_nest_host->name();
1100 Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1101 if (s != shared_nest_host) {
1102 // The dynamically resolved nest_host is not the same as the one we used during dump time,
1103 // so we cannot use ik.
1104 return nullptr;
1105 } else {
1106 assert(s->is_shared(), "must be");
1107 }
1108
1109 InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, nullptr, pkg_entry, CHECK_NULL);
1110
1111 if (loaded_ik != nullptr) {
1112 assert(shared_nest_host->is_same_class_package(ik),
1113 "lambda proxy class and its nest host must be in the same package");
1114 }
1115
1116 // The lambda proxy class and its nest host have the same class loader and class loader data,
1117 // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1118 assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1119 assert(shared_nest_host->class_loader_data() == class_loader_data(class_loader), "mismatched class loader data");
1120 ik->set_nest_host(shared_nest_host);
1121
1122 return loaded_ik;
1123 }
1124
1125 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1126 Handle class_loader,
1127 Handle protection_domain,
1128 const ClassFileStream *cfs,
1129 PackageEntry* pkg_entry,
1130 TRAPS) {
1131 assert(ik != nullptr, "sanity");
1132 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1133 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1134 Symbol* class_name = ik->name();
1135
1136 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1137 return nullptr;
1138 }
1139
1140 if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {
1141 return nullptr;
1142 }
1143
1144 InstanceKlass* new_ik = nullptr;
1145 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1146 // It will be skipped for shared VM hidden lambda proxy classes.
1147 if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1148 new_ik = KlassFactory::check_shared_class_file_load_hook(
1149 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1150 }
1151 if (new_ik != nullptr) {
1152 // The class is changed by CFLH. Return the new class. The shared class is
1153 // not used.
1154 return new_ik;
1155 }
1156
1157 // Adjust methods to recover missing data. They need addresses for
1158 // interpreter entry points and their default native method address
1159 // must be reset.
1160
1161 // Shared classes are all currently loaded by either the bootstrap or
1162 // internal parallel class loaders, so this will never cause a deadlock
1163 // on a custom class loader lock.
1164 // Since this class is already locked with parallel capable class
1165 // loaders, including the bootstrap loader via the placeholder table,
1166 // this lock is currently a nop.
1167
1168 ClassLoaderData* loader_data = class_loader_data(class_loader);
1169 {
1170 HandleMark hm(THREAD);
1171 Handle lockObject = get_loader_lock_or_null(class_loader);
1172 ObjectLocker ol(lockObject, THREAD);
1173 // prohibited package check assumes all classes loaded from archive call
1174 // restore_unshareable_info which calls ik->set_package()
1175 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1176 }
1177
1178 load_shared_class_misc(ik, loader_data);
1179 return ik;
1180 }
1181
1182 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1183 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1184
1185 // For boot loader, ensure that GetSystemPackage knows that a class in this
1186 // package was loaded.
1187 if (loader_data->is_the_null_class_loader_data()) {
1188 s2 path_index = ik->shared_classpath_index();
1189 ik->set_classpath_index(path_index);
1190 }
1191
1192 // notify a class loaded from shared object
1193 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1194 }
1195
1196 #endif // INCLUDE_CDS
1197
1198 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1199
1200 if (class_loader.is_null()) {
1201 ResourceMark rm(THREAD);
1202 PackageEntry* pkg_entry = nullptr;
1203 bool search_only_bootloader_append = false;
1204
1205 // Find the package in the boot loader's package entry table.
1206 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1207 if (pkg_name != nullptr) {
1208 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1209 }
1210
1211 // Prior to attempting to load the class, enforce the boot loader's
1212 // visibility boundaries.
1213 if (!Universe::is_module_initialized()) {
1214 // During bootstrapping, prior to module initialization, any
1215 // class attempting to be loaded must be checked against the
1216 // java.base packages in the boot loader's PackageEntryTable.
1217 // No class outside of java.base is allowed to be loaded during
1218 // this bootstrapping window.
1219 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1220 // Class is either in the unnamed package or in
1221 // a named package within the unnamed module. Either
1222 // case is outside of java.base, do not attempt to
1223 // load the class post java.base definition. If
1224 // java.base has not been defined, let the class load
1225 // and its package will be checked later by
1226 // ModuleEntryTable::verify_javabase_packages.
1227 if (ModuleEntryTable::javabase_defined()) {
1228 return nullptr;
1229 }
1230 } else {
1231 // Check that the class' package is defined within java.base.
1232 ModuleEntry* mod_entry = pkg_entry->module();
1233 Symbol* mod_entry_name = mod_entry->name();
1234 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1235 return nullptr;
1236 }
1237 }
1238 } else {
1239 // After the module system has been initialized, check if the class'
1240 // package is in a module defined to the boot loader.
1241 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1242 // Class is either in the unnamed package, in a named package
1243 // within a module not defined to the boot loader or in a
1244 // a named package within the unnamed module. In all cases,
1245 // limit visibility to search for the class only in the boot
1246 // loader's append path.
1247 if (!ClassLoader::has_bootclasspath_append()) {
1248 // If there is no bootclasspath append entry, no need to continue
1249 // searching.
1250 return nullptr;
1251 }
1252 search_only_bootloader_append = true;
1253 }
1254 }
1255
1256 // Prior to bootstrapping's module initialization, never load a class outside
1257 // of the boot loader's module path
1258 assert(Universe::is_module_initialized() ||
1259 !search_only_bootloader_append,
1260 "Attempt to load a class outside of boot loader's module path");
1261
1262 // Search for classes in the CDS archive.
1263 InstanceKlass* k = nullptr;
1264
1265 #if INCLUDE_CDS
1266 if (UseSharedSpaces)
1267 {
1268 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1269 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1270 if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1271 SharedClassLoadingMark slm(THREAD, ik);
1272 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1273 }
1274 }
1275 #endif
1276
1277 if (k == nullptr) {
1278 // Use VM class loader
1279 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1280 k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1281 }
1282
1283 // find_or_define_instance_class may return a different InstanceKlass
1284 if (k != nullptr) {
1285 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1286 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1287 }
1288 return k;
1289 } else {
1290 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1291 ResourceMark rm(THREAD);
1292
1293 JavaThread* jt = THREAD;
1294
1295 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1296 ClassLoader::perf_app_classload_selftime(),
1297 ClassLoader::perf_app_classload_count(),
1298 jt->get_thread_stat()->perf_recursion_counts_addr(),
1299 jt->get_thread_stat()->perf_timers_addr(),
1300 PerfClassTraceTime::CLASS_LOAD);
1301
1302 // Translate to external class name format, i.e., convert '/' chars to '.'
1303 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1304
1305 JavaValue result(T_OBJECT);
1306
1307 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1308
1309 // Call public unsynchronized loadClass(String) directly for all class loaders.
1310 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1311 // acquire a class-name based lock rather than the class loader object lock.
1312 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1313 JavaCalls::call_virtual(&result,
1314 class_loader,
1315 spec_klass,
1316 vmSymbols::loadClass_name(),
1317 vmSymbols::string_class_signature(),
1318 string,
1319 CHECK_NULL);
1320
1321 assert(result.get_type() == T_OBJECT, "just checking");
1322 oop obj = result.get_oop();
1323
1324 // Primitive classes return null since forName() can not be
1325 // used to obtain any of the Class objects representing primitives or void
1326 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1327 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1328 // For user defined Java class loaders, check that the name returned is
1329 // the same as that requested. This check is done for the bootstrap
1330 // loader when parsing the class file.
1331 if (class_name == k->name()) {
1332 return k;
1333 }
1334 }
1335 // Class is not found or has the wrong name, return null
1336 return nullptr;
1337 }
1338 }
1339
1340 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1341 Handle class_loader,
1342 TRAPS) {
1343
1344 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1345
1346 // If everything was OK (no exceptions, no null return value), and
1347 // class_loader is NOT the defining loader, do a little more bookkeeping.
1348 if (loaded_class != nullptr &&
1349 loaded_class->class_loader() != class_loader()) {
1350
1351 ClassLoaderData* loader_data = class_loader_data(class_loader);
1352 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1353
1354 // Record dependency for non-parent delegation.
1355 // This recording keeps the defining class loader of the klass (loaded_class) found
1356 // from being unloaded while the initiating class loader is loaded
1357 // even if the reference to the defining class loader is dropped
1358 // before references to the initiating class loader.
1359 loader_data->record_dependency(loaded_class);
1360
1361 update_dictionary(THREAD, loaded_class, loader_data);
1362
1363 if (JvmtiExport::should_post_class_load()) {
1364 JvmtiExport::post_class_load(THREAD, loaded_class);
1365 }
1366 }
1367 return loaded_class;
1368 }
1369
1370 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1371 EventClassDefine event;
1372 if (event.should_commit()) {
1373 event.set_definedClass(k);
1374 event.set_definingClassLoader(def_cld);
1375 event.commit();
1376 }
1377 }
1378
1379 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1380
1381 ClassLoaderData* loader_data = k->class_loader_data();
1382 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1383
1384 // Bootstrap and other parallel classloaders don't acquire a lock,
1385 // they use placeholder token.
1386 // If a parallelCapable class loader calls define_instance_class instead of
1387 // find_or_define_instance_class to get here, we have a timing
1388 // hole with systemDictionary updates and check_constraints
1389 if (!is_parallelCapable(class_loader)) {
1390 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1391 get_loader_lock_or_null(class_loader)),
1392 "define called without lock");
1393 }
1394
1395 // Check class-loading constraints. Throw exception if violation is detected.
1396 // Grabs and releases SystemDictionary_lock
1397 // The check_constraints/find_class call and update_dictionary sequence
1398 // must be "atomic" for a specific class/classloader pair so we never
1399 // define two different instanceKlasses for that class/classloader pair.
1400 // Existing classloaders will call define_instance_class with the
1401 // classloader lock held
1402 // Parallel classloaders will call find_or_define_instance_class
1403 // which will require a token to perform the define class
1404 check_constraints(k, loader_data, true, CHECK);
1405
1406 // Register class just loaded with class loader (placed in ArrayList)
1407 // Note we do this before updating the dictionary, as this can
1408 // fail with an OutOfMemoryError (if it does, we will *not* put this
1409 // class in the dictionary and will not update the class hierarchy).
1410 // JVMTI FollowReferences needs to find the classes this way.
1411 if (k->class_loader() != nullptr) {
1412 methodHandle m(THREAD, Universe::loader_addClass_method());
1413 JavaValue result(T_VOID);
1414 JavaCallArguments args(class_loader);
1415 args.push_oop(Handle(THREAD, k->java_mirror()));
1416 JavaCalls::call(&result, m, &args, CHECK);
1417 }
1418
1419 // Add to class hierarchy, and do possible deoptimizations.
1420 k->add_to_hierarchy(THREAD);
1421
1422 // Add to systemDictionary - so other classes can see it.
1423 // Grabs and releases SystemDictionary_lock
1424 update_dictionary(THREAD, k, loader_data);
1425
1426 // notify jvmti
1427 if (JvmtiExport::should_post_class_load()) {
1428 JvmtiExport::post_class_load(THREAD, k);
1429 }
1430 post_class_define_event(k, loader_data);
1431 }
1432
1433 // Support parallel classloading
1434 // All parallel class loaders, including bootstrap classloader
1435 // lock a placeholder entry for this class/class_loader pair
1436 // to allow parallel defines of different classes for this class loader
1437 // With AllowParallelDefine flag==true, in case they do not synchronize around
1438 // FindLoadedClass/DefineClass, calls, we check for parallel
1439 // loading for them, wait if a defineClass is in progress
1440 // and return the initial requestor's results
1441 // This flag does not apply to the bootstrap classloader.
1442 // With AllowParallelDefine flag==false, call through to define_instance_class
1443 // which will throw LinkageError: duplicate class definition.
1444 // False is the requested default.
1445 // For better performance, the class loaders should synchronize
1446 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1447 // potentially waste time reading and parsing the bytestream.
1448 // Note: VM callers should ensure consistency of k/class_name,class_loader
1449 // Be careful when modifying this code: once you have run
1450 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1451 // you need to find_and_remove it before returning.
1452 // So be careful to not exit with a CHECK_ macro between these calls.
1453 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1454 InstanceKlass* k, TRAPS) {
1455
1456 Symbol* name_h = k->name();
1457 ClassLoaderData* loader_data = class_loader_data(class_loader);
1458 Dictionary* dictionary = loader_data->dictionary();
1459
1460 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1461 {
1462 MutexLocker mu(THREAD, SystemDictionary_lock);
1463 // First check if class already defined
1464 if (is_parallelDefine(class_loader)) {
1465 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1466 if (check != nullptr) {
1467 return check;
1468 }
1469 }
1470
1471 // Acquire define token for this class/classloader
1472 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1473 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1474 // Wait if another thread defining in parallel
1475 // All threads wait - even those that will throw duplicate class: otherwise
1476 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1477 // if other thread has not finished updating dictionary
1478 while (probe->definer() != nullptr) {
1479 SystemDictionary_lock->wait();
1480 }
1481 // Only special cases allow parallel defines and can use other thread's results
1482 // Other cases fall through, and may run into duplicate defines
1483 // caught by finding an entry in the SystemDictionary
1484 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1485 InstanceKlass* ik = probe->instance_klass();
1486 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1487 SystemDictionary_lock->notify_all();
1488 #ifdef ASSERT
1489 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1490 assert(check != nullptr, "definer missed recording success");
1491 #endif
1492 return ik;
1493 } else {
1494 // This thread will define the class (even if earlier thread tried and had an error)
1495 probe->set_definer(THREAD);
1496 }
1497 }
1498
1499 define_instance_class(k, class_loader, THREAD);
1500
1501 // definer must notify any waiting threads
1502 {
1503 MutexLocker mu(THREAD, SystemDictionary_lock);
1504 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1505 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1506 if (!HAS_PENDING_EXCEPTION) {
1507 probe->set_instance_klass(k);
1508 }
1509 probe->set_definer(nullptr);
1510 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1511 SystemDictionary_lock->notify_all();
1512 }
1513
1514 return HAS_PENDING_EXCEPTION ? nullptr : k;
1515 }
1516
1517 // If a class loader supports parallel classloading handle parallel define requests.
1518 // find_or_define_instance_class may return a different InstanceKlass
1519 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1520 InstanceKlass* k, TRAPS) {
1521 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1522 // Clean up original InstanceKlass if duplicate or error
1523 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1524 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1525 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1526 k->class_loader_data()->add_to_deallocate_list(k);
1527 } else if (HAS_PENDING_EXCEPTION) {
1528 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1529 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1530 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1531 k->class_loader_data()->add_to_deallocate_list(k);
1532 }
1533 return defined_k;
1534 }
1535
1536
1537 // ----------------------------------------------------------------------------
1538 // GC support
1539
1540 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1541 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1542
1543 bool unloading_occurred;
1544 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1545 {
1546 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1547 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1548 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1549 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1550 if (unloading_occurred) {
1551 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1552 JFR_ONLY(Jfr::on_unloading_classes();)
1553 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1554 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1555 ClassLoaderDataGraph::clean_module_and_package_info();
1556 LoaderConstraintTable::purge_loader_constraints();
1557 ResolutionErrorTable::purge_resolution_errors();
1558 }
1559 }
1560
1561 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1562
1563 if (unloading_occurred) {
1564 SymbolTable::trigger_cleanup();
1565
1566 if (java_lang_System::allow_security_manager()) {
1567 // Oops referenced by the protection domain cache table may get unreachable independently
1568 // of the class loader (eg. cached protection domain oops). So we need to
1569 // explicitly unlink them here.
1570 // All protection domain oops are linked to the caller class, so if nothing
1571 // unloads, this is not needed.
1572 ProtectionDomainCacheTable::trigger_cleanup();
1573 } else {
1574 assert(ProtectionDomainCacheTable::number_of_entries() == 0, "should be empty");
1575 }
1576
1577 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1578 InstanceKlass::clean_initialization_error_table();
1579 }
1580
1581 return unloading_occurred;
1582 }
1583
1584 void SystemDictionary::methods_do(void f(Method*)) {
1585 // Walk methods in loaded classes
1586
1587 {
1588 MutexLocker ml(ClassLoaderDataGraph_lock);
1589 ClassLoaderDataGraph::methods_do(f);
1590 }
1591
1592 auto doit = [&] (InvokeMethodKey key, Method* method) {
1593 if (method != nullptr) {
1594 f(method);
1595 }
1596 };
1597
1598 {
1599 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1600 _invoke_method_intrinsic_table->iterate_all(doit);
1601 }
1602
1603 }
1604
1605 // ----------------------------------------------------------------------------
1606 // Initialization
1607
1608 void SystemDictionary::initialize(TRAPS) {
1609 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1610 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1611 ResolutionErrorTable::initialize();
1612 LoaderConstraintTable::initialize();
1613 PlaceholderTable::initialize();
1614 ProtectionDomainCacheTable::initialize();
1615 #if INCLUDE_CDS
1616 SystemDictionaryShared::initialize();
1617 #endif
1618 // Resolve basic classes
1619 vmClasses::resolve_all(CHECK);
1620 // Resolve classes used by archived heap objects
1621 if (UseSharedSpaces) {
1622 HeapShared::resolve_classes(THREAD);
1623 }
1624 }
1625
1626 // Constraints on class loaders. The details of the algorithm can be
1627 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1628 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1629 // that the dictionary needs to maintain a set of constraints that
1630 // must be satisfied by all classes in the dictionary.
1631 // if defining is true, then LinkageError if already in dictionary
1632 // if initiating loader, then ok if InstanceKlass matches existing entry
1633
1634 void SystemDictionary::check_constraints(InstanceKlass* k,
1635 ClassLoaderData* loader_data,
1636 bool defining,
1637 TRAPS) {
1638 ResourceMark rm(THREAD);
1639 stringStream ss;
1640 bool throwException = false;
1641
1642 {
1643 Symbol* name = k->name();
1644
1645 MutexLocker mu(THREAD, SystemDictionary_lock);
1646
1647 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1648 if (check != nullptr) {
1649 // If different InstanceKlass - duplicate class definition,
1650 // else - ok, class loaded by a different thread in parallel.
1651 // We should only have found it if it was done loading and ok to use.
1652
1653 if ((defining == true) || (k != check)) {
1654 throwException = true;
1655 ss.print("loader %s", loader_data->loader_name_and_id());
1656 ss.print(" attempted duplicate %s definition for %s. (%s)",
1657 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1658 } else {
1659 return;
1660 }
1661 }
1662
1663 if (throwException == false) {
1664 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1665 throwException = true;
1666 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1667 ss.print(" wants to load %s %s.",
1668 k->external_kind(), k->external_name());
1669 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1670 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1671 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1672 existing_klass->external_kind(),
1673 existing_klass->class_loader_data()->loader_name_and_id(),
1674 existing_klass->class_in_module_of_loader(false, true));
1675 } else {
1676 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1677 }
1678 }
1679 }
1680 }
1681
1682 // Throw error now if needed (cannot throw while holding
1683 // SystemDictionary_lock because of rank ordering)
1684 if (throwException == true) {
1685 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1686 }
1687 }
1688
1689 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1690 // have been called.
1691 void SystemDictionary::update_dictionary(JavaThread* current,
1692 InstanceKlass* k,
1693 ClassLoaderData* loader_data) {
1694 MonitorLocker mu1(SystemDictionary_lock);
1695
1696 // Make a new dictionary entry.
1697 Symbol* name = k->name();
1698 Dictionary* dictionary = loader_data->dictionary();
1699 InstanceKlass* sd_check = dictionary->find_class(current, name);
1700 if (sd_check == nullptr) {
1701 dictionary->add_klass(current, name, k);
1702 }
1703 mu1.notify_all();
1704 }
1705
1706
1707 // Try to find a class name using the loader constraints. The
1708 // loader constraints might know about a class that isn't fully loaded
1709 // yet and these will be ignored.
1710 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1711 Thread* current, Symbol* class_name, Handle class_loader) {
1712
1713 // First see if it has been loaded directly.
1714 // Force the protection domain to be null. (This removes protection checks.)
1715 Handle no_protection_domain;
1716 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader,
1717 no_protection_domain);
1718 if (klass != nullptr)
1719 return klass;
1720
1721 // Now look to see if it has been loaded elsewhere, and is subject to
1722 // a loader constraint that would require this loader to return the
1723 // klass that is already loaded.
1724 if (Signature::is_array(class_name)) {
1725 // For array classes, their Klass*s are not kept in the
1726 // constraint table. The element Klass*s are.
1727 SignatureStream ss(class_name, false);
1728 int ndims = ss.skip_array_prefix(); // skip all '['s
1729 BasicType t = ss.type();
1730 if (t != T_OBJECT) {
1731 klass = Universe::typeArrayKlassObj(t);
1732 } else {
1733 MutexLocker mu(current, SystemDictionary_lock);
1734 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1735 }
1736 // If element class already loaded, allocate array klass
1737 if (klass != nullptr) {
1738 klass = klass->array_klass_or_null(ndims);
1739 }
1740 } else {
1741 MutexLocker mu(current, SystemDictionary_lock);
1742 // Non-array classes are easy: simply check the constraint table.
1743 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1744 }
1745
1746 return klass;
1747 }
1748
1749 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1750 Klass* klass_being_linked,
1751 Handle class_loader1,
1752 Handle class_loader2) {
1753 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1754 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1755
1756 Symbol* constraint_name = nullptr;
1757
1758 if (!Signature::is_array(class_name)) {
1759 constraint_name = class_name;
1760 } else {
1761 // For array classes, their Klass*s are not kept in the
1762 // constraint table. The element classes are.
1763 SignatureStream ss(class_name, false);
1764 ss.skip_array_prefix(); // skip all '['s
1765 if (!ss.has_envelope()) {
1766 return true; // primitive types always pass
1767 }
1768 constraint_name = ss.as_symbol();
1769 // Increment refcount to keep constraint_name alive after
1770 // SignatureStream is destructed. It will be decremented below
1771 // before returning.
1772 constraint_name->increment_refcount();
1773 }
1774
1775 Dictionary* dictionary1 = loader_data1->dictionary();
1776 Dictionary* dictionary2 = loader_data2->dictionary();
1777
1778 JavaThread* current = JavaThread::current();
1779 {
1780 MutexLocker mu_s(SystemDictionary_lock);
1781 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1782 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1783 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1784 klass2, loader_data2);
1785 #if INCLUDE_CDS
1786 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1787 !klass_being_linked->is_shared()) {
1788 SystemDictionaryShared::record_linking_constraint(constraint_name,
1789 InstanceKlass::cast(klass_being_linked),
1790 class_loader1, class_loader2);
1791 }
1792 #endif // INCLUDE_CDS
1793 if (Signature::is_array(class_name)) {
1794 constraint_name->decrement_refcount();
1795 }
1796 return result;
1797 }
1798 }
1799
1800 // Add entry to resolution error table to record the error when the first
1801 // attempt to resolve a reference to a class has failed.
1802 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1803 Symbol* error, Symbol* message,
1804 Symbol* cause, Symbol* cause_msg) {
1805 {
1806 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1807 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1808 if (entry == nullptr) {
1809 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1810 }
1811 }
1812 }
1813
1814 // Delete a resolution error for RedefineClasses for a constant pool is going away
1815 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1816 ResolutionErrorTable::delete_entry(pool);
1817 }
1818
1819 // Lookup resolution error table. Returns error if found, otherwise null.
1820 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1821 Symbol** message, Symbol** cause, Symbol** cause_msg) {
1822
1823 {
1824 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1825 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1826 if (entry != nullptr) {
1827 *message = entry->message();
1828 *cause = entry->cause();
1829 *cause_msg = entry->cause_msg();
1830 return entry->error();
1831 } else {
1832 return nullptr;
1833 }
1834 }
1835 }
1836
1837 // Add an entry to resolution error table to record an error in resolving or
1838 // validating a nest host. This is used to construct informative error
1839 // messages when IllegalAccessError's occur. If an entry already exists it will
1840 // be updated with the nest host error message.
1841
1842 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1843 int which,
1844 const char* message) {
1845 {
1846 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1847 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1848 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1849 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1850 // still want to add the error message for the higher-level access checks to report. We should
1851 // only reach here under the same error condition, so we can ignore the potential race with setting
1852 // the message. If we see it is already set then we can ignore it.
1853 entry->set_nest_host_error(message);
1854 } else {
1855 ResolutionErrorTable::add_entry(pool, which, message);
1856 }
1857 }
1858 }
1859
1860 // Lookup any nest host error
1861 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1862 {
1863 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1864 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1865 if (entry != nullptr) {
1866 return entry->nest_host_error();
1867 } else {
1868 return nullptr;
1869 }
1870 }
1871 }
1872
1873 // Signature constraints ensure that callers and callees agree about
1874 // the meaning of type names in their signatures. This routine is the
1875 // intake for constraints. It collects them from several places:
1876 //
1877 // * LinkResolver::resolve_method (if check_access is true) requires
1878 // that the resolving class (the caller) and the defining class of
1879 // the resolved method (the callee) agree on each type in the
1880 // method's signature.
1881 //
1882 // * LinkResolver::resolve_interface_method performs exactly the same
1883 // checks.
1884 //
1885 // * LinkResolver::resolve_field requires that the constant pool
1886 // attempting to link to a field agree with the field's defining
1887 // class about the type of the field signature.
1888 //
1889 // * klassVtable::initialize_vtable requires that, when a class
1890 // overrides a vtable entry allocated by a superclass, that the
1891 // overriding method (i.e., the callee) agree with the superclass
1892 // on each type in the method's signature.
1893 //
1894 // * klassItable::initialize_itable requires that, when a class fills
1895 // in its itables, for each non-abstract method installed in an
1896 // itable, the method (i.e., the callee) agree with the interface
1897 // on each type in the method's signature.
1898 //
1899 // All those methods have a boolean (check_access, checkconstraints)
1900 // which turns off the checks. This is used from specialized contexts
1901 // such as bootstrapping, dumping, and debugging.
1902 //
1903 // No direct constraint is placed between the class and its
1904 // supertypes. Constraints are only placed along linked relations
1905 // between callers and callees. When a method overrides or implements
1906 // an abstract method in a supertype (superclass or interface), the
1907 // constraints are placed as if the supertype were the caller to the
1908 // overriding method. (This works well, since callers to the
1909 // supertype have already established agreement between themselves and
1910 // the supertype.) As a result of all this, a class can disagree with
1911 // its supertype about the meaning of a type name, as long as that
1912 // class neither calls a relevant method of the supertype, nor is
1913 // called (perhaps via an override) from the supertype.
1914 //
1915 //
1916 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1917 //
1918 // Make sure all class components (including arrays) in the given
1919 // signature will be resolved to the same class in both loaders.
1920 // Returns the name of the type that failed a loader constraint check, or
1921 // null if no constraint failed. No exception except OOME is thrown.
1922 // Arrays are not added to the loader constraint table, their elements are.
1923 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1924 Klass* klass_being_linked,
1925 Handle loader1, Handle loader2,
1926 bool is_method) {
1927 // Nothing to do if loaders are the same.
1928 if (loader1() == loader2()) {
1929 return nullptr;
1930 }
1931
1932 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
1933 if (ss.is_reference()) {
1934 Symbol* sig = ss.as_symbol();
1935 // Note: In the future, if template-like types can take
1936 // arguments, we will want to recognize them and dig out class
1937 // names hiding inside the argument lists.
1938 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
1939 return sig;
1940 }
1941 }
1942 }
1943 return nullptr;
1944 }
1945
1946 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
1947 Symbol* signature,
1948 TRAPS) {
1949
1950 const int iid_as_int = vmIntrinsics::as_int(iid);
1951 assert(MethodHandles::is_signature_polymorphic(iid) &&
1952 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
1953 iid != vmIntrinsics::_invokeGeneric,
1954 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
1955
1956 InvokeMethodKey key(signature, iid_as_int);
1957 Method** met = nullptr;
1958
1959 // We only want one entry in the table for this (signature/id, method) pair but the code
1960 // to create the intrinsic method needs to be outside the lock.
1961 // The first thread claims the entry by adding the key and the other threads wait, until the
1962 // Method has been added as the value.
1963 {
1964 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1965 while (true) {
1966 bool created;
1967 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
1968 assert(met != nullptr, "either created or found");
1969 if (*met != nullptr) {
1970 return *met;
1971 } else if (created) {
1972 // The current thread won the race and will try to create the full entry.
1973 break;
1974 } else {
1975 // Another thread beat us to it, so wait for them to complete
1976 // and return *met; or if they hit an error we get another try.
1977 ml.wait();
1978 // Note it is not safe to read *met here as that entry could have
1979 // been deleted, so we must loop and try put_if_absent again.
1980 }
1981 }
1982 }
1983
1984 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
1985 bool throw_error = HAS_PENDING_EXCEPTION;
1986 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
1987 // Generate a compiled form of the MH intrinsic
1988 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
1989 AdapterHandlerLibrary::create_native_wrapper(m);
1990 // Check if have the compiled code.
1991 throw_error = (!m->has_compiled_code());
1992 }
1993
1994 {
1995 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1996 if (throw_error) {
1997 // Remove the entry and let another thread try, or get the same exception.
1998 bool removed = _invoke_method_intrinsic_table->remove(key);
1999 assert(removed, "must be the owner");
2000 ml.notify_all();
2001 } else {
2002 signature->make_permanent(); // The signature is never unloaded.
2003 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2004 m->code()->entry_point() == m->from_compiled_entry()),
2005 "MH intrinsic invariant");
2006 *met = m(); // insert the element
2007 ml.notify_all();
2008 return m();
2009 }
2010 }
2011
2012 // Throw VirtualMachineError or the pending exception in the JavaThread
2013 if (throw_error && !HAS_PENDING_EXCEPTION) {
2014 THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
2015 "Out of space in CodeCache for method handle intrinsic");
2016 }
2017 return nullptr;
2018 }
2019
2020 // Helper for unpacking the return value from linkMethod and linkCallSite.
2021 static Method* unpack_method_and_appendix(Handle mname,
2022 Klass* accessing_klass,
2023 objArrayHandle appendix_box,
2024 Handle* appendix_result,
2025 TRAPS) {
2026 if (mname.not_null()) {
2027 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2028 if (m != nullptr) {
2029 oop appendix = appendix_box->obj_at(0);
2030 LogTarget(Info, methodhandles) lt;
2031 if (lt.develop_is_enabled()) {
2032 ResourceMark rm(THREAD);
2033 LogStream ls(lt);
2034 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2035 m->print_on(&ls);
2036 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2037 ls.cr();
2038 }
2039
2040 (*appendix_result) = Handle(THREAD, appendix);
2041 // the target is stored in the cpCache and if a reference to this
2042 // MemberName is dropped we need a way to make sure the
2043 // class_loader containing this method is kept alive.
2044 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2045 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2046 this_key->record_dependency(m->method_holder());
2047 return mh();
2048 }
2049 }
2050 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2051 }
2052
2053 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2054 Symbol* name,
2055 Symbol* signature,
2056 Klass* accessing_klass,
2057 Handle* appendix_result,
2058 TRAPS) {
2059 guarantee(THREAD->can_call_java(), "");
2060 Handle method_type =
2061 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2062
2063 int ref_kind = JVM_REF_invokeVirtual;
2064 oop name_oop = StringTable::intern(name, CHECK_NULL);
2065 Handle name_str (THREAD, name_oop);
2066 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2067 assert(appendix_box->obj_at(0) == nullptr, "");
2068
2069 // This should not happen. JDK code should take care of that.
2070 if (accessing_klass == nullptr || method_type.is_null()) {
2071 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2072 }
2073
2074 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2075 JavaCallArguments args;
2076 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2077 args.push_int(ref_kind);
2078 args.push_oop(Handle(THREAD, klass->java_mirror()));
2079 args.push_oop(name_str);
2080 args.push_oop(method_type);
2081 args.push_oop(appendix_box);
2082 JavaValue result(T_OBJECT);
2083 JavaCalls::call_static(&result,
2084 vmClasses::MethodHandleNatives_klass(),
2085 vmSymbols::linkMethod_name(),
2086 vmSymbols::linkMethod_signature(),
2087 &args, CHECK_NULL);
2088 Handle mname(THREAD, result.get_oop());
2089 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2090 }
2091
2092 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2093 // We must ensure that all class loaders everywhere will reach this class, for any client.
2094 // This is a safe bet for public classes in java.lang, such as Object and String.
2095 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2096 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2097 static bool is_always_visible_class(oop mirror) {
2098 Klass* klass = java_lang_Class::as_Klass(mirror);
2099 if (klass->is_objArray_klass()) {
2100 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2101 }
2102 if (klass->is_typeArray_klass()) {
2103 return true; // primitive array
2104 }
2105 assert(klass->is_instance_klass(), "%s", klass->external_name());
2106 return klass->is_public() &&
2107 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2108 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2109 }
2110
2111 // Find or construct the Java mirror (java.lang.Class instance) for
2112 // the given field type signature, as interpreted relative to the
2113 // given class loader. Handles primitives, void, references, arrays,
2114 // and all other reflectable types, except method types.
2115 // N.B. Code in reflection should use this entry point.
2116 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2117 Klass* accessing_klass,
2118 Handle class_loader,
2119 Handle protection_domain,
2120 SignatureStream::FailureMode failure_mode,
2121 TRAPS) {
2122 assert(accessing_klass == nullptr || (class_loader.is_null() && protection_domain.is_null()),
2123 "one or the other, or perhaps neither");
2124
2125 // What we have here must be a valid field descriptor,
2126 // and all valid field descriptors are supported.
2127 // Produce the same java.lang.Class that reflection reports.
2128 if (accessing_klass != nullptr) {
2129 class_loader = Handle(THREAD, accessing_klass->class_loader());
2130 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2131 }
2132 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2133 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2134 if (mirror_oop == nullptr) {
2135 return Handle(); // report failure this way
2136 }
2137 Handle mirror(THREAD, mirror_oop);
2138
2139 if (accessing_klass != nullptr) {
2140 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2141 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2142 if (sel_klass != nullptr) {
2143 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2144 }
2145 }
2146 return mirror;
2147 }
2148
2149
2150 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2151 // signature, as interpreted relative to the given class loader.
2152 // Because of class loader constraints, all method handle usage must be
2153 // consistent with this loader.
2154 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2155 Klass* accessing_klass,
2156 TRAPS) {
2157 Handle empty;
2158 OopHandle* o;
2159 {
2160 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2161 o = _invoke_method_type_table->get(signature);
2162 }
2163
2164 if (o != nullptr) {
2165 oop mt = o->resolve();
2166 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2167 return Handle(THREAD, mt);
2168 } else if (!THREAD->can_call_java()) {
2169 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2170 return Handle(); // do not attempt from within compiler, unless it was cached
2171 }
2172
2173 Handle class_loader, protection_domain;
2174 if (accessing_klass != nullptr) {
2175 class_loader = Handle(THREAD, accessing_klass->class_loader());
2176 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2177 }
2178 bool can_be_cached = true;
2179 int npts = ArgumentCount(signature).size();
2180 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2181 int arg = 0;
2182 Handle rt; // the return type from the signature
2183 ResourceMark rm(THREAD);
2184 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2185 oop mirror = nullptr;
2186 if (can_be_cached) {
2187 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2188 mirror = ss.as_java_mirror(Handle(), Handle(),
2189 SignatureStream::ReturnNull, CHECK_(empty));
2190 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2191 // Fall back to accessing_klass context.
2192 can_be_cached = false;
2193 }
2194 }
2195 if (!can_be_cached) {
2196 // Resolve, throwing a real error if it doesn't work.
2197 mirror = ss.as_java_mirror(class_loader, protection_domain,
2198 SignatureStream::NCDFError, CHECK_(empty));
2199 }
2200 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2201 if (ss.at_return_type())
2202 rt = Handle(THREAD, mirror);
2203 else
2204 pts->obj_at_put(arg++, mirror);
2205
2206 // Check accessibility.
2207 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2208 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2209 mirror = nullptr; // safety
2210 // Emulate ConstantPool::verify_constant_pool_resolve.
2211 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2212 }
2213 }
2214 assert(arg == npts, "");
2215
2216 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2217 JavaCallArguments args(Handle(THREAD, rt()));
2218 args.push_oop(pts);
2219 JavaValue result(T_OBJECT);
2220 JavaCalls::call_static(&result,
2221 vmClasses::MethodHandleNatives_klass(),
2222 vmSymbols::findMethodHandleType_name(),
2223 vmSymbols::findMethodHandleType_signature(),
2224 &args, CHECK_(empty));
2225 Handle method_type(THREAD, result.get_oop());
2226
2227 if (can_be_cached) {
2228 // We can cache this MethodType inside the JVM.
2229 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2230 bool created = false;
2231 assert(method_type != nullptr, "unexpected null");
2232 OopHandle* h = _invoke_method_type_table->get(signature);
2233 if (h == nullptr) {
2234 signature->make_permanent(); // The signature is never unloaded.
2235 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2236 bool created = _invoke_method_type_table->put(signature, elem);
2237 assert(created, "better be created");
2238 }
2239 }
2240 // report back to the caller with the MethodType
2241 return method_type;
2242 }
2243
2244 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2245 Klass* accessing_klass,
2246 TRAPS) {
2247 Handle empty;
2248 ResourceMark rm(THREAD);
2249 SignatureStream ss(signature, /*is_method=*/ false);
2250 if (!ss.is_done()) {
2251 Handle class_loader, protection_domain;
2252 if (accessing_klass != nullptr) {
2253 class_loader = Handle(THREAD, accessing_klass->class_loader());
2254 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2255 }
2256 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2257 ss.next();
2258 if (ss.is_done()) {
2259 return Handle(THREAD, mirror);
2260 }
2261 }
2262 return empty;
2263 }
2264
2265 // Ask Java code to find or construct a method handle constant.
2266 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2267 int ref_kind, //e.g., JVM_REF_invokeVirtual
2268 Klass* callee,
2269 Symbol* name,
2270 Symbol* signature,
2271 TRAPS) {
2272 Handle empty;
2273 if (caller == nullptr) {
2274 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2275 }
2276 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2277 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2278
2279 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2280 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2281 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2282 java_lang_invoke_MemberName::set_name (mname(), name_str());
2283 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2284 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2285
2286 if (ref_kind == JVM_REF_invokeVirtual &&
2287 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2288 // Skip resolution for public signature polymorphic methods such as
2289 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2290 // They require appendix argument which MemberName resolution doesn't handle.
2291 // There's special logic on JDK side to handle them
2292 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2293 } else {
2294 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2295 }
2296
2297 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2298 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2299
2300 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2301 JavaCallArguments args;
2302 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2303 args.push_int(ref_kind);
2304 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2305 args.push_oop(name_str);
2306 args.push_oop(type);
2307 JavaValue result(T_OBJECT);
2308 JavaCalls::call_static(&result,
2309 vmClasses::MethodHandleNatives_klass(),
2310 vmSymbols::linkMethodHandleConstant_name(),
2311 vmSymbols::linkMethodHandleConstant_signature(),
2312 &args, CHECK_(empty));
2313 return Handle(THREAD, result.get_oop());
2314 }
2315
2316 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2317 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2318 // with linkage results being stored back into the bootstrap specifier.
2319 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2320 // Resolve the bootstrap specifier, its name, type, and static arguments
2321 bootstrap_specifier.resolve_bsm(CHECK);
2322
2323 // This should not happen. JDK code should take care of that.
2324 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2325 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2326 }
2327
2328 bool is_indy = bootstrap_specifier.is_method_call();
2329 objArrayHandle appendix_box;
2330 if (is_indy) {
2331 // Some method calls may require an appendix argument. Arrange to receive it.
2332 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2333 assert(appendix_box->obj_at(0) == nullptr, "");
2334 }
2335
2336 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2337 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2338 JavaCallArguments args;
2339 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2340 args.push_oop(bootstrap_specifier.bsm());
2341 args.push_oop(bootstrap_specifier.name_arg());
2342 args.push_oop(bootstrap_specifier.type_arg());
2343 args.push_oop(bootstrap_specifier.arg_values());
2344 if (is_indy) {
2345 args.push_oop(appendix_box);
2346 }
2347 JavaValue result(T_OBJECT);
2348 JavaCalls::call_static(&result,
2349 vmClasses::MethodHandleNatives_klass(),
2350 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2351 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2352 &args, CHECK);
2353
2354 Handle value(THREAD, result.get_oop());
2355 if (is_indy) {
2356 Handle appendix;
2357 Method* method = unpack_method_and_appendix(value,
2358 bootstrap_specifier.caller(),
2359 appendix_box,
2360 &appendix, CHECK);
2361 methodHandle mh(THREAD, method);
2362 bootstrap_specifier.set_resolved_method(mh, appendix);
2363 } else {
2364 bootstrap_specifier.set_resolved_value(value);
2365 }
2366
2367 // sanity check
2368 assert(bootstrap_specifier.is_resolved() ||
2369 (bootstrap_specifier.is_method_call() &&
2370 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2371 }
2372
2373
2374 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2375 assert(m != nullptr, "Unexpected nullptr Method*");
2376 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2377 }
2378
2379 // ----------------------------------------------------------------------------
2380
2381 void SystemDictionary::print_on(outputStream *st) {
2382 CDS_ONLY(SystemDictionaryShared::print_on(st));
2383 GCMutexLocker mu(SystemDictionary_lock);
2384
2385 ClassLoaderDataGraph::print_dictionary(st);
2386
2387 // Placeholders
2388 PlaceholderTable::print_on(st);
2389 st->cr();
2390
2391 // loader constraints - print under SD_lock
2392 LoaderConstraintTable::print_on(st);
2393 st->cr();
2394
2395 ProtectionDomainCacheTable::print_on(st);
2396 st->cr();
2397 }
2398
2399 void SystemDictionary::print() { print_on(tty); }
2400
2401 void SystemDictionary::verify() {
2402
2403 GCMutexLocker mu(SystemDictionary_lock);
2404
2405 // Verify dictionary
2406 ClassLoaderDataGraph::verify_dictionary();
2407
2408 // Verify constraint table
2409 LoaderConstraintTable::verify();
2410
2411 // Verify protection domain table
2412 ProtectionDomainCacheTable::verify();
2413 }
2414
2415 void SystemDictionary::dump(outputStream *st, bool verbose) {
2416 assert_locked_or_safepoint(SystemDictionary_lock);
2417 if (verbose) {
2418 print_on(st);
2419 } else {
2420 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2421 ClassLoaderDataGraph::print_table_statistics(st);
2422 LoaderConstraintTable::print_table_statistics(st);
2423 ProtectionDomainCacheTable::print_table_statistics(st);
2424 }
2425 }
2426
2427 // Utility for dumping dictionaries.
2428 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2429 DCmdWithParser(output, heap),
2430 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2431 "BOOLEAN", false, "false") {
2432 _dcmdparser.add_dcmd_option(&_verbose);
2433 }
2434
2435 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2436 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2437 _verbose.value());
2438 VMThread::execute(&dumper);
2439 }