1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "cds/aotClassLocation.hpp"
26 #include "cds/cdsConfig.hpp"
27 #include "cds/heapShared.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/classLoadInfo.hpp"
34 #include "classfile/dictionary.hpp"
35 #include "classfile/javaClasses.inline.hpp"
36 #include "classfile/klassFactory.hpp"
37 #include "classfile/loaderConstraints.hpp"
38 #include "classfile/packageEntry.hpp"
39 #include "classfile/placeholders.hpp"
40 #include "classfile/resolutionErrors.hpp"
41 #include "classfile/stringTable.hpp"
42 #include "classfile/symbolTable.hpp"
43 #include "classfile/systemDictionary.hpp"
44 #include "classfile/vmClasses.hpp"
45 #include "classfile/vmSymbols.hpp"
46 #include "gc/shared/gcTraceTime.inline.hpp"
47 #include "interpreter/bootstrapInfo.hpp"
48 #include "jfr/jfrEvents.hpp"
49 #include "jvm.h"
50 #include "logging/log.hpp"
51 #include "logging/logStream.hpp"
52 #include "memory/metaspaceClosure.hpp"
53 #include "memory/oopFactory.hpp"
54 #include "memory/resourceArea.hpp"
55 #include "memory/universe.hpp"
56 #include "oops/access.inline.hpp"
57 #include "oops/constantPool.inline.hpp"
58 #include "oops/instanceKlass.hpp"
59 #include "oops/klass.inline.hpp"
60 #include "oops/method.inline.hpp"
61 #include "oops/objArrayKlass.hpp"
62 #include "oops/objArrayOop.inline.hpp"
63 #include "oops/oop.inline.hpp"
64 #include "oops/oopHandle.inline.hpp"
65 #include "oops/symbol.hpp"
66 #include "oops/typeArrayKlass.hpp"
67 #include "prims/jvmtiExport.hpp"
68 #include "prims/methodHandles.hpp"
69 #include "runtime/arguments.hpp"
70 #include "runtime/atomicAccess.hpp"
71 #include "runtime/handles.inline.hpp"
72 #include "runtime/java.hpp"
73 #include "runtime/javaCalls.hpp"
74 #include "runtime/mutexLocker.hpp"
75 #include "runtime/sharedRuntime.hpp"
76 #include "runtime/signature.hpp"
77 #include "runtime/synchronizer.hpp"
78 #include "services/classLoadingService.hpp"
79 #include "services/diagnosticCommand.hpp"
80 #include "services/finalizerService.hpp"
81 #include "services/threadService.hpp"
82 #include "utilities/growableArray.hpp"
83 #include "utilities/macros.hpp"
84 #include "utilities/utf8.hpp"
85 #if INCLUDE_CDS
86 #include "classfile/systemDictionaryShared.hpp"
87 #endif
88 #if INCLUDE_JFR
89 #include "jfr/jfr.hpp"
90 #endif
91
92 class InvokeMethodKey : public StackObj {
93 private:
94 Symbol* _symbol;
95 intptr_t _iid;
96
97 public:
98 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
99 _symbol(symbol),
100 _iid(iid) {}
101
102 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
103 return k1._symbol == k2._symbol && k1._iid == k2._iid;
104 }
105
106 static unsigned int compute_hash(const InvokeMethodKey &k) {
107 Symbol* sym = k._symbol;
108 intptr_t iid = k._iid;
109 unsigned int hash = (unsigned int) sym -> identity_hash();
110 return (unsigned int) (hash ^ iid);
111 }
112
113 };
114
115 using InvokeMethodIntrinsicTable = HashTable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
116 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
117 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
118 using InvokeMethodTypeTable = HashTable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
119 static InvokeMethodTypeTable* _invoke_method_type_table;
120
121 OopHandle SystemDictionary::_java_system_loader;
122 OopHandle SystemDictionary::_java_platform_loader;
123
124 // ----------------------------------------------------------------------------
125 // Java-level SystemLoader and PlatformLoader
126 oop SystemDictionary::java_system_loader() {
127 return _java_system_loader.resolve();
128 }
129
130 oop SystemDictionary::java_platform_loader() {
131 return _java_platform_loader.resolve();
132 }
133
134 void SystemDictionary::compute_java_loaders(TRAPS) {
135 if (_java_platform_loader.is_empty()) {
136 oop platform_loader = get_platform_class_loader_impl(CHECK);
137 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
138 } else {
139 // It must have been restored from the archived module graph
140 assert(CDSConfig::is_using_archive(), "must be");
141 assert(CDSConfig::is_using_full_module_graph(), "must be");
142 DEBUG_ONLY(
143 oop platform_loader = get_platform_class_loader_impl(CHECK);
144 assert(_java_platform_loader.resolve() == platform_loader, "must be");
145 )
146 }
147
148 if (_java_system_loader.is_empty()) {
149 oop system_loader = get_system_class_loader_impl(CHECK);
150 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
151 } else {
152 // It must have been restored from the archived module graph
153 assert(CDSConfig::is_using_archive(), "must be");
154 assert(CDSConfig::is_using_full_module_graph(), "must be");
155 DEBUG_ONLY(
156 oop system_loader = get_system_class_loader_impl(CHECK);
157 assert(_java_system_loader.resolve() == system_loader, "must be");
158 )
159 }
160 }
161
162 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
163 JavaValue result(T_OBJECT);
164 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
165 JavaCalls::call_static(&result,
166 class_loader_klass,
167 vmSymbols::getSystemClassLoader_name(),
168 vmSymbols::void_classloader_signature(),
169 CHECK_NULL);
170 return result.get_oop();
171 }
172
173 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
174 JavaValue result(T_OBJECT);
175 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
176 JavaCalls::call_static(&result,
177 class_loader_klass,
178 vmSymbols::getPlatformClassLoader_name(),
179 vmSymbols::void_classloader_signature(),
180 CHECK_NULL);
181 return result.get_oop();
182 }
183
184 // Helper function
185 inline ClassLoaderData* class_loader_data(Handle class_loader) {
186 return ClassLoaderData::class_loader_data(class_loader());
187 }
188
189 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
190 if (create_mirror_cld) {
191 // Add a new class loader data to the graph.
192 return ClassLoaderDataGraph::add(class_loader, true);
193 } else {
194 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
195 ClassLoaderDataGraph::find_or_create(class_loader);
196 }
197 }
198
199 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
200 if (_java_system_loader.is_empty()) {
201 _java_system_loader = cld->class_loader_handle();
202 } else {
203 assert(_java_system_loader.resolve() == cld->class_loader(), "sanity");
204 }
205 }
206
207 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
208 if (_java_platform_loader.is_empty()) {
209 _java_platform_loader = cld->class_loader_handle();
210 } else {
211 assert(_java_platform_loader.resolve() == cld->class_loader(), "sanity");
212 }
213 }
214
215 // ----------------------------------------------------------------------------
216 // Parallel class loading check
217
218 static bool is_parallelCapable(Handle class_loader) {
219 if (class_loader.is_null()) return true;
220 return java_lang_ClassLoader::parallelCapable(class_loader());
221 }
222 // ----------------------------------------------------------------------------
223 // ParallelDefineClass flag does not apply to bootclass loader
224 static bool is_parallelDefine(Handle class_loader) {
225 if (class_loader.is_null()) return false;
226 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
227 return true;
228 }
229 return false;
230 }
231
232 // Returns true if the passed class loader is the builtin application class loader
233 // or a custom system class loader. A customer system class loader can be
234 // specified via -Djava.system.class.loader.
235 bool SystemDictionary::is_system_class_loader(oop class_loader) {
236 if (class_loader == nullptr) {
237 return false;
238 }
239 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
240 class_loader == _java_system_loader.peek());
241 }
242
243 // Returns true if the passed class loader is the platform class loader.
244 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
245 if (class_loader == nullptr) {
246 return false;
247 }
248 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
249 }
250
251 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
252 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
253 if (is_parallelCapable(class_loader)) {
254 return Handle();
255 } else {
256 return class_loader;
257 }
258 }
259
260 // ----------------------------------------------------------------------------
261 // Resolving of classes
262
263 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
264 if (name == nullptr) {
265 THROW_MSG_NULL(exception, "No class name given");
266 }
267 size_t name_len = strlen(name);
268 if (name_len > static_cast<size_t>(Symbol::max_length())) {
269 // It's impossible to create this class; the name cannot fit
270 // into the constant pool. If necessary report an abridged name
271 // in the exception message.
272 if (name_len > static_cast<size_t>(MaxStringPrintSize)) {
273 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
274 "Class name exceeds maximum length of %d: %.*s ... (%zu characters omitted) ... %.*s",
275 Symbol::max_length(),
276 MaxStringPrintSize / 2,
277 name,
278 name_len - 2 * (MaxStringPrintSize / 2), // allows for odd value
279 MaxStringPrintSize / 2,
280 name + name_len - MaxStringPrintSize / 2);
281 }
282 else {
283 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
284 "Class name exceeds maximum length of %d: %s",
285 Symbol::max_length(),
286 name);
287 }
288 return nullptr;
289 }
290 // Callers should ensure that the name is never an illegal UTF8 string.
291 assert(UTF8::is_legal_utf8((const unsigned char*)name, name_len, false),
292 "Class name is not a valid utf8 string.");
293
294 // Make a new symbol for the class name.
295 return SymbolTable::new_symbol(name);
296 }
297
298 #ifdef ASSERT
299 // Used to verify that class loading succeeded in adding k to the dictionary.
300 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
301 MutexLocker mu(SystemDictionary_lock);
302 ClassLoaderData* loader_data = k->class_loader_data();
303 Dictionary* dictionary = loader_data->dictionary();
304 assert(class_name == k->name(), "Must be the same");
305 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
306 assert(kk == k, "should be present in dictionary");
307 }
308 #endif
309
310 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
311 if (HAS_PENDING_EXCEPTION) {
312 // If we have a pending exception we forward it to the caller, unless throw_error is true,
313 // in which case we have to check whether the pending exception is a ClassNotFoundException,
314 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
315 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
316 ResourceMark rm(THREAD);
317 Handle e(THREAD, PENDING_EXCEPTION);
318 CLEAR_PENDING_EXCEPTION;
319 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
320 } else {
321 return; // the caller will throw the incoming exception
322 }
323 }
324 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
325 // error or exception depending on the value of throw_error.
326 ResourceMark rm(THREAD);
327 if (throw_error) {
328 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
329 } else {
330 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
331 }
332 }
333
334 // Forwards to resolve_or_null
335
336 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader,
337 bool throw_error, TRAPS) {
338 Klass* klass = resolve_or_null(class_name, class_loader, THREAD);
339 // Check for pending exception or null klass, and throw exception
340 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
341 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
342 }
343 return klass;
344 }
345
346 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
347
348 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, TRAPS) {
349 if (Signature::is_array(class_name)) {
350 return resolve_array_class_or_null(class_name, class_loader, THREAD);
351 } else {
352 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
353 if (Signature::has_envelope(class_name)) {
354 ResourceMark rm(THREAD);
355 // Ignore wrapping L and ;.
356 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
357 class_name->utf8_length() - 2);
358 return resolve_instance_class_or_null(name, class_loader, THREAD);
359 } else {
360 return resolve_instance_class_or_null(class_name, class_loader, THREAD);
361 }
362 }
363 }
364
365 // Forwards to resolve_instance_class_or_null
366
367 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
368 Handle class_loader,
369 TRAPS) {
370 assert(Signature::is_array(class_name), "must be array");
371 ResourceMark rm(THREAD);
372 SignatureStream ss(class_name, false);
373 int ndims = ss.skip_array_prefix(); // skip all '['s
374 Klass* k = nullptr;
375 BasicType t = ss.type();
376 if (ss.has_envelope()) {
377 Symbol* obj_class = ss.as_symbol();
378 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
379 class_loader,
380 CHECK_NULL);
381 if (k != nullptr) {
382 k = k->array_klass(ndims, CHECK_NULL);
383 }
384 } else {
385 k = Universe::typeArrayKlass(t);
386 k = k->array_klass(ndims, CHECK_NULL);
387 }
388 return k;
389 }
390
391 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
392 LogTarget(Debug, class, load, placeholders) lt;
393 if (lt.is_enabled()) {
394 ResourceMark rm;
395 LogStream ls(lt);
396 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
397 probe->print_on(&ls);
398 ls.cr();
399 }
400 }
401
402 // Must be called for any superclass or superinterface resolution
403 // during class definition to allow class circularity checking
404 // superinterface callers:
405 // parse_interfaces - from defineClass
406 // superclass callers:
407 // ClassFileParser - from defineClass
408 // load_shared_class - while loading a class from shared archive
409 // resolve_instance_class_or_null:
410 // via: handle_parallel_super_load
411 // when resolving a class that has an existing placeholder with
412 // a saved superclass [i.e. a defineClass is currently in progress]
413 // If another thread is trying to resolve the class, it must do
414 // superclass checks on its own thread to catch class circularity and
415 // to avoid deadlock.
416 //
417 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
418 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
419 // placeholder for the same thread, class, classloader is found.
420 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
421 //
422 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
423 Symbol* next_name,
424 Handle class_loader,
425 bool is_superclass,
426 TRAPS) {
427
428 assert(next_name != nullptr, "null superclass for resolving");
429 assert(!Signature::is_array(next_name), "invalid superclass name");
430
431 ClassLoaderData* loader_data = class_loader_data(class_loader);
432
433 if (is_superclass) {
434 InstanceKlass* klassk = loader_data->dictionary()->find_class(THREAD, class_name);
435 if (klassk != nullptr) {
436 // We can come here for two reasons:
437 // (a) RedefineClasses -- the class is already loaded
438 // (b) Rarely, the class might have been loaded by a parallel thread
439 // We can do a quick check against the already assigned superclass's name and loader.
440 InstanceKlass* superk = klassk->super();
441 if (superk != nullptr &&
442 superk->name() == next_name &&
443 superk->class_loader() == class_loader()) {
444 return superk;
445 }
446 }
447 }
448
449 // can't throw error holding a lock
450 bool throw_circularity_error = false;
451 {
452 MutexLocker mu(THREAD, SystemDictionary_lock);
453
454 // Must check ClassCircularity before resolving next_name (superclass or interface).
455 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
456 if (probe != nullptr && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
457 log_circularity_error(class_name, probe);
458 throw_circularity_error = true;
459 }
460
461 // Make sure there's a placeholder for the class_name before resolving.
462 // This is used as a claim that this thread is currently loading superclass/classloader
463 // and for ClassCircularity checks.
464 if (!throw_circularity_error) {
465 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
466 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
467 loader_data,
468 PlaceholderTable::DETECT_CIRCULARITY,
469 next_name, THREAD);
470 }
471 }
472
473 if (throw_circularity_error) {
474 ResourceMark rm(THREAD);
475 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
476 }
477
478 // Resolve the superclass or superinterface, check results on return
479 InstanceKlass* superk =
480 SystemDictionary::resolve_instance_class_or_null(next_name,
481 class_loader,
482 THREAD);
483
484 // Clean up placeholder entry.
485 {
486 MutexLocker mu(THREAD, SystemDictionary_lock);
487 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
488 SystemDictionary_lock->notify_all();
489 }
490
491 // Check for pending exception or null superk, and throw exception
492 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
493 handle_resolution_exception(next_name, true, CHECK_NULL);
494 }
495
496 return superk;
497 }
498
499 // If the class in is in the placeholder table, class loading is in progress.
500 // For cases where the application changes threads to load classes, it
501 // is critical to ClassCircularity detection that we try loading
502 // the superclass on the new thread internally, so we do parallel
503 // superclass loading here. This avoids deadlock for ClassCircularity
504 // detection for parallelCapable class loaders that lock on a per-class lock.
505 static void handle_parallel_super_load(Symbol* name,
506 Symbol* superclassname,
507 Handle class_loader,
508 TRAPS) {
509
510 // The result superk is not used; resolve_with_circularity_detection is called for circularity check only.
511 // This passes false to is_superclass to skip doing the unlikely optimization.
512 Klass* superk = SystemDictionary::resolve_with_circularity_detection(name,
513 superclassname,
514 class_loader,
515 false,
516 CHECK);
517 }
518
519 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
520 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
521 static bool needs_load_placeholder(Handle class_loader) {
522 return class_loader.is_null() || !is_parallelCapable(class_loader);
523 }
524
525 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
526 static InstanceKlass* handle_parallel_loading(JavaThread* current,
527 Symbol* name,
528 ClassLoaderData* loader_data,
529 bool must_wait_for_class_loading,
530 bool* throw_circularity_error) {
531 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
532 if (oldprobe != nullptr) {
533 // -Xcomp calls load_signature_classes which might result in loading
534 // a class that's already in the process of loading, so we detect CCE here also.
535 // Only need check_seen_thread once, not on each loop
536 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
537 log_circularity_error(name, oldprobe);
538 *throw_circularity_error = true;
539 return nullptr;
540 } else if (must_wait_for_class_loading) {
541 // Wait until the first thread has finished loading this class. Also wait until all the
542 // threads trying to load its superclass have removed their placeholders.
543 while (oldprobe != nullptr &&
544 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) {
545
546 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
547 // for the bootclass loader.
548 SystemDictionary_lock->wait();
549
550 // Check if classloading completed while we were waiting
551 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
552 if (check != nullptr) {
553 // Klass is already loaded, so just return it
554 return check;
555 }
556 // check if other thread failed to load and cleaned up
557 oldprobe = PlaceholderTable::get_entry(name, loader_data);
558 }
559 }
560 }
561 return nullptr;
562 }
563
564 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
565 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
566 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
567 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
568 // This can return null, an exception or an InstanceKlass.
569 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
570 Handle class_loader,
571 TRAPS) {
572 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
573 DEBUG_ONLY(ResourceMark rm(THREAD));
574 assert(name != nullptr && !Signature::is_array(name) &&
575 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
576
577 EventClassLoad class_load_event;
578
579 HandleMark hm(THREAD);
580
581 ClassLoaderData* loader_data = register_loader(class_loader);
582 Dictionary* dictionary = loader_data->dictionary();
583
584 // Do lookup to see if class already exists.
585 InstanceKlass* probe = dictionary->find_class(THREAD, name);
586 if (probe != nullptr) return probe;
587
588 // Non-bootstrap class loaders will call out to class loader and
589 // define via jvm/jni_DefineClass which will acquire the
590 // class loader object lock to protect against multiple threads
591 // defining the class in parallel by accident.
592 // This lock must be acquired here so the waiter will find
593 // any successful result in the SystemDictionary and not attempt
594 // the define.
595 // ParallelCapable class loaders and the bootstrap classloader
596 // do not acquire lock here.
597 Handle lockObject = get_loader_lock_or_null(class_loader);
598 ObjectLocker ol(lockObject, THREAD);
599
600 bool circularity_detection_in_progress = false;
601 InstanceKlass* loaded_class = nullptr;
602 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
603
604 guarantee(THREAD->can_call_java(),
605 "can not load classes with compiler thread: class=%s, classloader=%s",
606 name->as_C_string(),
607 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
608
609 // Check again (after locking) if the class already exists in SystemDictionary
610 {
611 MutexLocker mu(THREAD, SystemDictionary_lock);
612 InstanceKlass* check = dictionary->find_class(THREAD, name);
613 if (check != nullptr) {
614 // InstanceKlass is already loaded, but we still need to check protection domain below.
615 loaded_class = check;
616 } else {
617 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
618 if (placeholder != nullptr && placeholder->circularity_detection_in_progress()) {
619 circularity_detection_in_progress = true;
620 superclassname = placeholder->next_klass_name();
621 assert(superclassname != nullptr, "superclass has to have a name");
622 }
623 }
624 }
625
626 // If the class is in the placeholder table with super_class set,
627 // handle superclass loading in progress.
628 if (circularity_detection_in_progress) {
629 handle_parallel_super_load(name, superclassname,
630 class_loader,
631 CHECK_NULL);
632 }
633
634 bool throw_circularity_error = false;
635 if (loaded_class == nullptr) {
636 bool load_placeholder_added = false;
637
638 // Add placeholder entry to record loading instance class
639 // case 1. Bootstrap classloader
640 // This classloader supports parallelism at the classloader level
641 // but only allows a single thread to load a class/classloader pair.
642 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
643 // case 2. parallelCapable user level classloaders
644 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
645 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
646 // case 3. traditional classloaders that rely on the classloader object lock
647 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
648 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
649 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
650 {
651 MutexLocker mu(THREAD, SystemDictionary_lock);
652 if (needs_load_placeholder(class_loader)) {
653 loaded_class = handle_parallel_loading(THREAD,
654 name,
655 loader_data,
656 class_loader.is_null(),
657 &throw_circularity_error);
658 }
659
660 // Recheck if the class has been loaded for all class loader cases and
661 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
662 if (!throw_circularity_error && loaded_class == nullptr) {
663 InstanceKlass* check = dictionary->find_class(THREAD, name);
664 if (check != nullptr) {
665 loaded_class = check;
666 } else if (needs_load_placeholder(class_loader)) {
667 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
668 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
669 PlaceholderTable::LOAD_INSTANCE,
670 nullptr,
671 THREAD);
672 load_placeholder_added = true;
673 }
674 }
675 }
676
677 // Must throw error outside of owning lock
678 if (throw_circularity_error) {
679 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
680 ResourceMark rm(THREAD);
681 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
682 }
683
684 // Be careful when modifying this code: once you have run
685 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
686 // you need to find_and_remove it before returning.
687 // So be careful to not exit with a CHECK_ macro between these calls.
688
689 if (loaded_class == nullptr) {
690 // Do actual loading
691 loaded_class = load_instance_class(name, class_loader, THREAD);
692 }
693
694 if (load_placeholder_added) {
695 // clean up placeholder entries for LOAD_INSTANCE success or error
696 // This brackets the SystemDictionary updates for both defining
697 // and initiating loaders
698 MutexLocker mu(THREAD, SystemDictionary_lock);
699 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
700 SystemDictionary_lock->notify_all();
701 }
702 }
703
704 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
705 return nullptr;
706 }
707
708 if (class_load_event.should_commit()) {
709 JFR_ONLY(post_class_load_event(&class_load_event, loaded_class, loader_data);)
710 }
711
712 // Make sure we have the right class in the dictionary
713 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
714
715 return loaded_class;
716 }
717
718
719 // This routine does not lock the system dictionary.
720 //
721 // Since readers don't hold a lock, we must make sure that system
722 // dictionary entries are added to in a safe way (all links must
723 // be updated in an MT-safe manner). All entries are removed during class
724 // unloading, when this class loader is no longer referenced.
725 //
726 // Callers should be aware that an entry could be added just after
727 // Dictionary is read here, so the caller will not see
728 // the new entry.
729
730 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
731 Symbol* class_name,
732 Handle class_loader) {
733
734 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
735 if (loader_data == nullptr) {
736 // If the ClassLoaderData has not been setup,
737 // then the class loader has no entries in the dictionary.
738 return nullptr;
739 }
740
741 Dictionary* dictionary = loader_data->dictionary();
742 return dictionary->find_class(current, class_name);
743 }
744
745 // Look for a loaded instance or array klass by name. Do not do any loading.
746 // return null in case of error.
747 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
748 Symbol* class_name,
749 Handle class_loader) {
750 Klass* k = nullptr;
751 assert(class_name != nullptr, "class name must be non nullptr");
752
753 if (Signature::is_array(class_name)) {
754 // The name refers to an array. Parse the name.
755 // dimension and object_key in FieldArrayInfo are assigned as a
756 // side-effect of this call
757 SignatureStream ss(class_name, false);
758 int ndims = ss.skip_array_prefix(); // skip all '['s
759 BasicType t = ss.type();
760 if (t != T_OBJECT) {
761 k = Universe::typeArrayKlass(t);
762 } else {
763 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader);
764 }
765 if (k != nullptr) {
766 k = k->array_klass_or_null(ndims);
767 }
768 } else {
769 k = find_instance_klass(current, class_name, class_loader);
770 }
771 return k;
772 }
773
774 // Note: this method is much like resolve_class_from_stream, but
775 // does not publish the classes in the SystemDictionary.
776 // Handles Lookup.defineClass hidden.
777 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
778 ClassFileStream* st,
779 Symbol* class_name,
780 Handle class_loader,
781 const ClassLoadInfo& cl_info,
782 TRAPS) {
783
784 EventClassLoad class_load_event;
785 ClassLoaderData* loader_data;
786
787 // - for hidden classes that are not strong: create a new CLD that has a class holder and
788 // whose loader is the Lookup class's loader.
789 // - for hidden class: add the class to the Lookup class's loader's CLD.
790 assert (cl_info.is_hidden(), "only used for hidden classes");
791 bool create_mirror_cld = !cl_info.is_strong_hidden();
792 loader_data = register_loader(class_loader, create_mirror_cld);
793
794 assert(st != nullptr, "invariant");
795
796 // Parse stream and create a klass.
797 InstanceKlass* k = KlassFactory::create_from_stream(st,
798 class_name,
799 loader_data,
800 cl_info,
801 CHECK_NULL);
802 assert(k != nullptr, "no klass created");
803
804 // Hidden classes that are not strong must update ClassLoaderData holder
805 // so that they can be unloaded when the mirror is no longer referenced.
806 if (!cl_info.is_strong_hidden()) {
807 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
808 }
809
810 // Add to class hierarchy, and do possible deoptimizations.
811 k->add_to_hierarchy(THREAD);
812 // But, do not add to dictionary.
813
814 if (class_load_event.should_commit()) {
815 JFR_ONLY(post_class_load_event(&class_load_event, k, loader_data);)
816 }
817
818 k->link_class(CHECK_NULL);
819
820 // notify jvmti
821 if (JvmtiExport::should_post_class_load()) {
822 JvmtiExport::post_class_load(THREAD, k);
823 }
824
825 return k;
826 }
827
828 // Add a klass to the system from a stream (called by jni_DefineClass and
829 // JVM_DefineClass).
830 // Note: class_name can be null. In that case we do not know the name of
831 // the class until we have parsed the stream.
832 // This function either returns an InstanceKlass or throws an exception. It does
833 // not return null without a pending exception.
834 InstanceKlass* SystemDictionary::resolve_class_from_stream(
835 ClassFileStream* st,
836 Symbol* class_name,
837 Handle class_loader,
838 const ClassLoadInfo& cl_info,
839 TRAPS) {
840
841 HandleMark hm(THREAD);
842
843 ClassLoaderData* loader_data = register_loader(class_loader);
844
845 // Classloaders that support parallelism, e.g. bootstrap classloader,
846 // do not acquire lock here
847 Handle lockObject = get_loader_lock_or_null(class_loader);
848 ObjectLocker ol(lockObject, THREAD);
849
850 // Parse the stream and create a klass.
851 // Note that we do this even though this klass might
852 // already be present in the SystemDictionary, otherwise we would not
853 // throw potential ClassFormatErrors.
854 InstanceKlass* k = nullptr;
855
856 #if INCLUDE_CDS
857 if (!CDSConfig::is_dumping_static_archive()) {
858 k = SystemDictionaryShared::lookup_from_stream(class_name,
859 class_loader,
860 cl_info.protection_domain(),
861 st,
862 CHECK_NULL);
863 }
864 #endif
865
866 if (k == nullptr) {
867 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
868 }
869
870 assert(k != nullptr, "no klass created");
871 Symbol* h_name = k->name();
872 assert(class_name == nullptr || class_name == h_name, "name mismatch");
873
874 // Add class just loaded
875 // If a class loader supports parallel classloading, handle parallel define requests.
876 // find_or_define_instance_class may return a different InstanceKlass,
877 // in which case the old k would be deallocated
878 if (is_parallelCapable(class_loader)) {
879 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
880 } else {
881 define_instance_class(k, class_loader, THREAD);
882
883 // If defining the class throws an exception register 'k' for cleanup.
884 if (HAS_PENDING_EXCEPTION) {
885 assert(k != nullptr, "Must have an instance klass here!");
886 loader_data->add_to_deallocate_list(k);
887 return nullptr;
888 }
889 }
890
891 // Make sure we have an entry in the SystemDictionary on success
892 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
893
894 return k;
895 }
896
897 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
898 Symbol* class_name,
899 Handle class_loader,
900 const ClassLoadInfo& cl_info,
901 TRAPS) {
902 if (cl_info.is_hidden()) {
903 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
904 } else {
905 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
906 }
907 }
908
909
910 #if INCLUDE_CDS
911 // Check if a shared class can be loaded by the specific classloader.
912 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
913 InstanceKlass* ik,
914 PackageEntry* pkg_entry,
915 Handle class_loader) {
916 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
917 "Cannot use sharing if java.base is patched");
918
919 // (1) Check if we are loading into the same loader as in dump time.
920
921 if (ik->defined_by_boot_loader()) {
922 if (class_loader() != nullptr) {
923 return false;
924 }
925 } else if (ik->defined_by_platform_loader()) {
926 if (class_loader() != java_platform_loader()) {
927 return false;
928 }
929 } else if (ik->defined_by_app_loader()) {
930 if (class_loader() != java_system_loader()) {
931 return false;
932 }
933 } else {
934 // ik was loaded by a custom loader during dump time
935 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
936 return false;
937 } else {
938 return true;
939 }
940 }
941
942 // (2) Check if we are loading into the same module from the same location as in dump time.
943
944 if (CDSConfig::is_using_optimized_module_handling()) {
945 // Class visibility has not changed between dump time and run time, so a class
946 // that was visible (and thus archived) during dump time is always visible during runtime.
947 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
948 "visibility cannot change between dump time and runtime");
949 return true;
950 }
951 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
952 }
953
954 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
955 InstanceKlass* ik,
956 PackageEntry* pkg_entry,
957 Handle class_loader) {
958 int scp_index = ik->shared_classpath_index();
959 assert(!ik->defined_by_other_loaders(), "this function should be called for built-in classes only");
960 assert(scp_index >= 0, "must be");
961 const AOTClassLocation* cl = AOTClassLocationConfig::runtime()->class_location_at(scp_index);
962 if (!Universe::is_module_initialized()) {
963 assert(cl != nullptr, "must be");
964 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
965 // has restricted the classes can be loaded at this step to be only:
966 // [1] cs->is_modules_image(): classes in java.base, or,
967 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
968 assert(cl->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
969 "only these classes can be loaded before the module system is initialized");
970 assert(class_loader.is_null(), "sanity");
971 return true;
972 }
973
974 if (pkg_entry == nullptr) {
975 // We might have looked up pkg_entry before the module system was initialized.
976 // Need to reload it now.
977 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
978 if (pkg_name != nullptr) {
979 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
980 }
981 }
982
983 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
984 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
985 bool was_archived_from_named_module = !cl->has_unnamed_module();
986 bool visible;
987
988 if (was_archived_from_named_module) {
989 if (should_be_in_named_module) {
990 // Is the module loaded from the same location as during dump time?
991 visible = mod_entry->shared_path_index() == scp_index;
992 if (visible) {
993 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
994 }
995 } else {
996 // During dump time, this class was in a named module, but at run time, this class should be
997 // in an unnamed module.
998 visible = false;
999 }
1000 } else {
1001 if (should_be_in_named_module) {
1002 // During dump time, this class was in an unnamed, but at run time, this class should be
1003 // in a named module.
1004 visible = false;
1005 } else {
1006 visible = true;
1007 }
1008 }
1009
1010 return visible;
1011 }
1012
1013 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1014 Handle class_loader, bool is_superclass, TRAPS) {
1015 assert(super_type->in_aot_cache(), "must be");
1016
1017 // Quick check if the super type has been already loaded.
1018 // + Don't do it for unregistered classes -- they can be unloaded so
1019 // super_type->class_loader_data() could be stale.
1020 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1021 if (!super_type->defined_by_other_loaders() && super_type->class_loader_data() != nullptr) {
1022 // Check if the superclass is loaded by the current class_loader
1023 Symbol* name = super_type->name();
1024 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader);
1025 if (check == super_type) {
1026 return true;
1027 }
1028 }
1029
1030 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(),
1031 class_loader, is_superclass, CHECK_false);
1032 if (found == super_type) {
1033 return true;
1034 } else {
1035 // The dynamically resolved super type is not the same as the one we used during dump time,
1036 // so we cannot use the class.
1037 return false;
1038 }
1039 }
1040
1041 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader, TRAPS) {
1042 // Check the superclass and interfaces. They must be the same
1043 // as in dump time, because the layout of <ik> depends on
1044 // the specific layout of ik->super() and ik->local_interfaces().
1045 //
1046 // If unexpected superclass or interfaces are found, we cannot
1047 // load <ik> from the shared archive.
1048
1049 if (ik->super() != nullptr) {
1050 bool check_super = check_shared_class_super_type(ik, ik->super(),
1051 class_loader, true,
1052 CHECK_false);
1053 if (!check_super) {
1054 return false;
1055 }
1056 }
1057
1058 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1059 int num_interfaces = interfaces->length();
1060 for (int index = 0; index < num_interfaces; index++) {
1061 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, false,
1062 CHECK_false);
1063 if (!check_interface) {
1064 return false;
1065 }
1066 }
1067
1068 return true;
1069 }
1070
1071 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1072 Handle class_loader,
1073 Handle protection_domain,
1074 const ClassFileStream *cfs,
1075 PackageEntry* pkg_entry,
1076 TRAPS) {
1077 assert(ik != nullptr, "sanity");
1078 assert(ik->in_aot_cache(), "sanity");
1079 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1080 assert(AtomicAccess::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1081 Symbol* class_name = ik->name();
1082
1083 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1084 ik->set_shared_loading_failed();
1085 return nullptr;
1086 }
1087
1088 bool check = check_shared_class_super_types(ik, class_loader, CHECK_NULL);
1089 if (!check) {
1090 ik->set_shared_loading_failed();
1091 return nullptr;
1092 }
1093
1094 InstanceKlass* new_ik = nullptr;
1095 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1096 // It will be skipped for shared VM hidden lambda proxy classes.
1097 if (!ik->is_hidden()) {
1098 new_ik = KlassFactory::check_shared_class_file_load_hook(
1099 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1100 }
1101 if (new_ik != nullptr) {
1102 // The class is changed by CFLH. Return the new class. The shared class is
1103 // not used.
1104 return new_ik;
1105 }
1106
1107 // Adjust methods to recover missing data. They need addresses for
1108 // interpreter entry points and their default native method address
1109 // must be reset.
1110
1111 // Shared classes are all currently loaded by either the bootstrap or
1112 // internal parallel class loaders, so this will never cause a deadlock
1113 // on a custom class loader lock.
1114 // Since this class is already locked with parallel capable class
1115 // loaders, including the bootstrap loader via the placeholder table,
1116 // this lock is currently a nop.
1117
1118 ClassLoaderData* loader_data = class_loader_data(class_loader);
1119 {
1120 HandleMark hm(THREAD);
1121 Handle lockObject = get_loader_lock_or_null(class_loader);
1122 ObjectLocker ol(lockObject, THREAD);
1123 // prohibited package check assumes all classes loaded from archive call
1124 // restore_unshareable_info which calls ik->set_package()
1125 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1126 }
1127
1128 load_shared_class_misc(ik, loader_data);
1129 return ik;
1130 }
1131
1132 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1133 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1134
1135 // For boot loader, ensure that GetSystemPackage knows that a class in this
1136 // package was loaded.
1137 if (loader_data->is_the_null_class_loader_data()) {
1138 s2 path_index = ik->shared_classpath_index();
1139 ik->set_classpath_index(path_index);
1140 }
1141
1142 // notify a class loaded from shared object
1143 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1144
1145 if (CDSConfig::is_dumping_final_static_archive()) {
1146 SystemDictionaryShared::init_dumptime_info_from_preimage(ik);
1147 }
1148 }
1149
1150 // This is much more lightweight than SystemDictionary::resolve_or_null
1151 // - There's only a single Java thread at this point. No need for placeholder.
1152 // - All supertypes of ik have been loaded
1153 // - There's no circularity (checked in AOT assembly phase)
1154 // - There's no need to call java.lang.ClassLoader::load_class() because the boot/platform/app
1155 // loaders are well-behaved
1156 void SystemDictionary::preload_class(Handle class_loader, InstanceKlass* ik, TRAPS) {
1157 precond(Universe::is_bootstrapping());
1158 precond(java_platform_loader() != nullptr && java_system_loader() != nullptr);
1159 precond(class_loader() == nullptr || class_loader() == java_platform_loader() ||class_loader() == java_system_loader());
1160 precond(CDSConfig::is_using_aot_linked_classes());
1161 precond(AOTMetaspace::in_aot_cache_static_region((void*)ik));
1162 precond(!ik->is_loaded());
1163
1164 #ifdef ASSERT
1165 // preload_class() must be called in the correct order -- all super types must have
1166 // already been loaded.
1167 if (ik->java_super() != nullptr) {
1168 assert(ik->java_super()->is_loaded(), "must be");
1169 }
1170
1171 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1172 int num_interfaces = interfaces->length();
1173 for (int index = 0; index < num_interfaces; index++) {
1174 assert(interfaces->at(index)->is_loaded(), "must be");
1175 }
1176 #endif
1177
1178 EventClassLoad class_load_event;
1179
1180 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1181 oop java_mirror = ik->archived_java_mirror();
1182 precond(java_mirror != nullptr);
1183 assert(java_lang_Class::module(java_mirror) != nullptr, "must have been archived");
1184
1185 Handle pd(THREAD, java_lang_Class::protection_domain(java_mirror));
1186 PackageEntry* pkg_entry = ik->package();
1187 assert(pkg_entry != nullptr || ClassLoader::package_from_class_name(ik->name()) == nullptr,
1188 "non-empty packages must have been archived");
1189
1190 // TODO: the following assert requires JDK-8365580
1191 // assert(is_shared_class_visible(ik->name(), ik, pkg_entry, class_loader), "must be");
1192
1193 ik->restore_unshareable_info(loader_data, pd, pkg_entry, CHECK);
1194 load_shared_class_misc(ik, loader_data);
1195 ik->add_to_hierarchy(THREAD);
1196
1197 if (!ik->is_hidden()) {
1198 update_dictionary(THREAD, ik, loader_data);
1199 }
1200
1201 if (class_load_event.should_commit()) {
1202 JFR_ONLY(post_class_load_event(&class_load_event, ik, loader_data);)
1203 }
1204
1205 assert(ik->is_loaded(), "Must be in at least loaded state");
1206 }
1207
1208 #endif // INCLUDE_CDS
1209
1210 #if INCLUDE_JFR
1211 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
1212 assert(event != nullptr, "invariant");
1213 assert(k != nullptr, "invariant");
1214 event->set_loadedClass(k);
1215 event->set_definingClassLoader(k->class_loader_data());
1216 event->set_initiatingClassLoader(init_cld);
1217 event->commit();
1218 }
1219 #endif // INCLUDE_JFR
1220
1221 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1222
1223 if (class_loader.is_null()) {
1224 ResourceMark rm(THREAD);
1225 PackageEntry* pkg_entry = nullptr;
1226 bool search_only_bootloader_append = false;
1227
1228 // Find the package in the boot loader's package entry table.
1229 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1230 if (pkg_name != nullptr) {
1231 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1232 }
1233
1234 // Prior to attempting to load the class, enforce the boot loader's
1235 // visibility boundaries.
1236 if (!Universe::is_module_initialized()) {
1237 // During bootstrapping, prior to module initialization, any
1238 // class attempting to be loaded must be checked against the
1239 // java.base packages in the boot loader's PackageEntryTable.
1240 // No class outside of java.base is allowed to be loaded during
1241 // this bootstrapping window.
1242 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1243 // Class is either in the unnamed package or in
1244 // a named package within the unnamed module. Either
1245 // case is outside of java.base, do not attempt to
1246 // load the class post java.base definition. If
1247 // java.base has not been defined, let the class load
1248 // and its package will be checked later by
1249 // ModuleEntryTable::verify_javabase_packages.
1250 if (ModuleEntryTable::javabase_defined()) {
1251 return nullptr;
1252 }
1253 } else {
1254 // Check that the class' package is defined within java.base.
1255 ModuleEntry* mod_entry = pkg_entry->module();
1256 Symbol* mod_entry_name = mod_entry->name();
1257 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1258 return nullptr;
1259 }
1260 }
1261 } else {
1262 // After the module system has been initialized, check if the class'
1263 // package is in a module defined to the boot loader.
1264 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1265 // Class is either in the unnamed package, in a named package
1266 // within a module not defined to the boot loader or in a
1267 // a named package within the unnamed module. In all cases,
1268 // limit visibility to search for the class only in the boot
1269 // loader's append path.
1270 if (!ClassLoader::has_bootclasspath_append()) {
1271 // If there is no bootclasspath append entry, no need to continue
1272 // searching.
1273 return nullptr;
1274 }
1275 search_only_bootloader_append = true;
1276 }
1277 }
1278
1279 // Prior to bootstrapping's module initialization, never load a class outside
1280 // of the boot loader's module path
1281 assert(Universe::is_module_initialized() ||
1282 !search_only_bootloader_append,
1283 "Attempt to load a class outside of boot loader's module path");
1284
1285 // Search for classes in the CDS archive.
1286 InstanceKlass* k = nullptr;
1287
1288 #if INCLUDE_CDS
1289 if (CDSConfig::is_using_archive())
1290 {
1291 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1292 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1293 if (ik != nullptr && ik->defined_by_boot_loader() && !ik->shared_loading_failed()) {
1294 SharedClassLoadingMark slm(THREAD, ik);
1295 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1296 }
1297 }
1298 #endif
1299
1300 if (k == nullptr) {
1301 // Use VM class loader
1302 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1303 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1304 }
1305
1306 // find_or_define_instance_class may return a different InstanceKlass
1307 if (k != nullptr) {
1308 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1309 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1310 }
1311 return k;
1312 } else {
1313 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1314 ResourceMark rm(THREAD);
1315
1316 JavaThread* jt = THREAD;
1317
1318 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1319 ClassLoader::perf_app_classload_selftime(),
1320 ClassLoader::perf_app_classload_count(),
1321 jt->get_thread_stat()->perf_recursion_counts_addr(),
1322 jt->get_thread_stat()->perf_timers_addr(),
1323 PerfClassTraceTime::CLASS_LOAD);
1324
1325 // Translate to external class name format, i.e., convert '/' chars to '.'
1326 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1327
1328 JavaValue result(T_OBJECT);
1329
1330 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1331
1332 // Call public unsynchronized loadClass(String) directly for all class loaders.
1333 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1334 // acquire a class-name based lock rather than the class loader object lock.
1335 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1336 JavaCalls::call_virtual(&result,
1337 class_loader,
1338 spec_klass,
1339 vmSymbols::loadClass_name(),
1340 vmSymbols::string_class_signature(),
1341 string,
1342 CHECK_NULL);
1343
1344 assert(result.get_type() == T_OBJECT, "just checking");
1345 oop obj = result.get_oop();
1346
1347 // Primitive classes return null since forName() cannot be
1348 // used to obtain any of the Class objects representing primitives or void
1349 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1350 InstanceKlass* k = java_lang_Class::as_InstanceKlass(obj);
1351 // For user defined Java class loaders, check that the name returned is
1352 // the same as that requested. This check is done for the bootstrap
1353 // loader when parsing the class file.
1354 if (class_name == k->name()) {
1355 return k;
1356 }
1357 }
1358 // Class is not found or has the wrong name, return null
1359 return nullptr;
1360 }
1361 }
1362
1363 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1364 Handle class_loader,
1365 TRAPS) {
1366
1367 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1368
1369 // If everything was OK (no exceptions, no null return value), and
1370 // class_loader is NOT the defining loader, do a little more bookkeeping.
1371 if (loaded_class != nullptr &&
1372 loaded_class->class_loader() != class_loader()) {
1373
1374 ClassLoaderData* loader_data = class_loader_data(class_loader);
1375 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1376
1377 // Record dependency for non-parent delegation.
1378 // This recording keeps the defining class loader of the klass (loaded_class) found
1379 // from being unloaded while the initiating class loader is loaded
1380 // even if the reference to the defining class loader is dropped
1381 // before references to the initiating class loader.
1382 loader_data->record_dependency(loaded_class);
1383
1384 update_dictionary(THREAD, loaded_class, loader_data);
1385
1386 if (JvmtiExport::should_post_class_load()) {
1387 JvmtiExport::post_class_load(THREAD, loaded_class);
1388 }
1389 }
1390 return loaded_class;
1391 }
1392
1393 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1394
1395 ClassLoaderData* loader_data = k->class_loader_data();
1396 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1397
1398 // Bootstrap and other parallel classloaders don't acquire a lock,
1399 // they use placeholder token.
1400 // If a parallelCapable class loader calls define_instance_class instead of
1401 // find_or_define_instance_class to get here, we have a timing
1402 // hole with systemDictionary updates and check_constraints
1403 if (!is_parallelCapable(class_loader)) {
1404 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1405 get_loader_lock_or_null(class_loader)),
1406 "define called without lock");
1407 }
1408
1409 // Check class-loading constraints. Throw exception if violation is detected.
1410 // Grabs and releases SystemDictionary_lock
1411 // The check_constraints/find_class call and update_dictionary sequence
1412 // must be "atomic" for a specific class/classloader pair so we never
1413 // define two different instanceKlasses for that class/classloader pair.
1414 // Existing classloaders will call define_instance_class with the
1415 // classloader lock held
1416 // Parallel classloaders will call find_or_define_instance_class
1417 // which will require a token to perform the define class
1418 check_constraints(k, loader_data, true, CHECK);
1419
1420 // Register class just loaded with class loader (placed in ArrayList)
1421 // Note we do this before updating the dictionary, as this can
1422 // fail with an OutOfMemoryError (if it does, we will *not* put this
1423 // class in the dictionary and will not update the class hierarchy).
1424 // JVMTI FollowReferences needs to find the classes this way.
1425 if (k->class_loader() != nullptr) {
1426 methodHandle m(THREAD, Universe::loader_addClass_method());
1427 JavaValue result(T_VOID);
1428 JavaCallArguments args(class_loader);
1429 args.push_oop(Handle(THREAD, k->java_mirror()));
1430 JavaCalls::call(&result, m, &args, CHECK);
1431 }
1432
1433 // Add to class hierarchy, and do possible deoptimizations.
1434 k->add_to_hierarchy(THREAD);
1435
1436 // Add to systemDictionary - so other classes can see it.
1437 // Grabs and releases SystemDictionary_lock
1438 update_dictionary(THREAD, k, loader_data);
1439
1440 // notify jvmti
1441 if (JvmtiExport::should_post_class_load()) {
1442 JvmtiExport::post_class_load(THREAD, k);
1443 }
1444 }
1445
1446 // Support parallel classloading
1447 // All parallel class loaders, including bootstrap classloader
1448 // lock a placeholder entry for this class/class_loader pair
1449 // to allow parallel defines of different classes for this class loader
1450 // With AllowParallelDefine flag==true, in case they do not synchronize around
1451 // FindLoadedClass/DefineClass, calls, we check for parallel
1452 // loading for them, wait if a defineClass is in progress
1453 // and return the initial requestor's results
1454 // This flag does not apply to the bootstrap classloader.
1455 // With AllowParallelDefine flag==false, call through to define_instance_class
1456 // which will throw LinkageError: duplicate class definition.
1457 // False is the requested default.
1458 // For better performance, the class loaders should synchronize
1459 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1460 // potentially waste time reading and parsing the bytestream.
1461 // Note: VM callers should ensure consistency of k/class_name,class_loader
1462 // Be careful when modifying this code: once you have run
1463 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1464 // you need to find_and_remove it before returning.
1465 // So be careful to not exit with a CHECK_ macro between these calls.
1466 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1467 InstanceKlass* k, TRAPS) {
1468
1469 Symbol* name_h = k->name();
1470 ClassLoaderData* loader_data = class_loader_data(class_loader);
1471 Dictionary* dictionary = loader_data->dictionary();
1472
1473 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1474 {
1475 MutexLocker mu(THREAD, SystemDictionary_lock);
1476 // First check if class already defined
1477 if (is_parallelDefine(class_loader)) {
1478 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1479 if (check != nullptr) {
1480 return check;
1481 }
1482 }
1483
1484 // Acquire define token for this class/classloader
1485 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1486 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1487 // Wait if another thread defining in parallel
1488 // All threads wait - even those that will throw duplicate class: otherwise
1489 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1490 // if other thread has not finished updating dictionary
1491 while (probe->definer() != nullptr) {
1492 SystemDictionary_lock->wait();
1493 }
1494 // Only special cases allow parallel defines and can use other thread's results
1495 // Other cases fall through, and may run into duplicate defines
1496 // caught by finding an entry in the SystemDictionary
1497 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1498 InstanceKlass* ik = probe->instance_klass();
1499 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1500 SystemDictionary_lock->notify_all();
1501 #ifdef ASSERT
1502 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1503 assert(check != nullptr, "definer missed recording success");
1504 #endif
1505 return ik;
1506 } else {
1507 // This thread will define the class (even if earlier thread tried and had an error)
1508 probe->set_definer(THREAD);
1509 }
1510 }
1511
1512 define_instance_class(k, class_loader, THREAD);
1513
1514 // definer must notify any waiting threads
1515 {
1516 MutexLocker mu(THREAD, SystemDictionary_lock);
1517 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1518 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1519 if (!HAS_PENDING_EXCEPTION) {
1520 probe->set_instance_klass(k);
1521 }
1522 probe->set_definer(nullptr);
1523 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1524 SystemDictionary_lock->notify_all();
1525 }
1526
1527 return HAS_PENDING_EXCEPTION ? nullptr : k;
1528 }
1529
1530 // If a class loader supports parallel classloading handle parallel define requests.
1531 // find_or_define_instance_class may return a different InstanceKlass
1532 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1533 InstanceKlass* k, TRAPS) {
1534 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1535 // Clean up original InstanceKlass if duplicate or error
1536 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1537 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1538 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1539 k->class_loader_data()->add_to_deallocate_list(k);
1540 } else if (HAS_PENDING_EXCEPTION) {
1541 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1542 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1543 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1544 k->class_loader_data()->add_to_deallocate_list(k);
1545 }
1546 return defined_k;
1547 }
1548
1549
1550 // ----------------------------------------------------------------------------
1551 // GC support
1552
1553 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1554 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1555
1556 bool unloading_occurred;
1557 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1558 {
1559 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1560 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1561 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1562 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1563 if (unloading_occurred) {
1564 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1565 JFR_ONLY(Jfr::on_unloading_classes();)
1566 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1567 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1568 ClassLoaderDataGraph::clean_module_and_package_info();
1569 LoaderConstraintTable::purge_loader_constraints();
1570 ResolutionErrorTable::purge_resolution_errors();
1571 }
1572 }
1573
1574 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1575
1576 if (unloading_occurred) {
1577 SymbolTable::trigger_cleanup();
1578
1579 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1580 InstanceKlass::clean_initialization_error_table();
1581 }
1582
1583 return unloading_occurred;
1584 }
1585
1586 void SystemDictionary::methods_do(void f(Method*)) {
1587 // Walk methods in loaded classes
1588
1589 {
1590 MutexLocker ml(ClassLoaderDataGraph_lock);
1591 ClassLoaderDataGraph::methods_do(f);
1592 }
1593
1594 auto doit = [&] (InvokeMethodKey key, Method* method) {
1595 if (method != nullptr) {
1596 f(method);
1597 }
1598 };
1599
1600 {
1601 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1602 _invoke_method_intrinsic_table->iterate_all(doit);
1603 }
1604
1605 }
1606
1607 // ----------------------------------------------------------------------------
1608 // Initialization
1609
1610 void SystemDictionary::initialize(TRAPS) {
1611 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1612 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1613 ResolutionErrorTable::initialize();
1614 LoaderConstraintTable::initialize();
1615 PlaceholderTable::initialize();
1616 #if INCLUDE_CDS
1617 SystemDictionaryShared::initialize();
1618 if (CDSConfig::is_dumping_archive()) {
1619 AOTClassLocationConfig::dumptime_init(THREAD);
1620 }
1621 #endif
1622 // Resolve basic classes
1623 vmClasses::resolve_all(CHECK);
1624 // Resolve classes used by archived heap objects
1625 if (CDSConfig::is_using_archive()) {
1626 HeapShared::resolve_classes(THREAD);
1627 }
1628 }
1629
1630 // Constraints on class loaders. The details of the algorithm can be
1631 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1632 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1633 // that the dictionary needs to maintain a set of constraints that
1634 // must be satisfied by all classes in the dictionary.
1635 // if defining is true, then LinkageError if already in dictionary
1636 // if initiating loader, then ok if InstanceKlass matches existing entry
1637
1638 void SystemDictionary::check_constraints(InstanceKlass* k,
1639 ClassLoaderData* loader_data,
1640 bool defining,
1641 TRAPS) {
1642 ResourceMark rm(THREAD);
1643 stringStream ss;
1644 bool throwException = false;
1645
1646 {
1647 Symbol* name = k->name();
1648
1649 MutexLocker mu(THREAD, SystemDictionary_lock);
1650
1651 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1652 if (check != nullptr) {
1653 // If different InstanceKlass - duplicate class definition,
1654 // else - ok, class loaded by a different thread in parallel.
1655 // We should only have found it if it was done loading and ok to use.
1656
1657 if ((defining == true) || (k != check)) {
1658 throwException = true;
1659 ss.print("loader %s", loader_data->loader_name_and_id());
1660 ss.print(" attempted duplicate %s definition for %s. (%s)",
1661 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1662 } else {
1663 return;
1664 }
1665 }
1666
1667 if (throwException == false) {
1668 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1669 throwException = true;
1670 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1671 ss.print(" wants to load %s %s.",
1672 k->external_kind(), k->external_name());
1673 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1674 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1675 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1676 existing_klass->external_kind(),
1677 existing_klass->class_loader_data()->loader_name_and_id(),
1678 existing_klass->class_in_module_of_loader(false, true));
1679 } else {
1680 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1681 }
1682 }
1683 }
1684 }
1685
1686 // Throw error now if needed (cannot throw while holding
1687 // SystemDictionary_lock because of rank ordering)
1688 if (throwException == true) {
1689 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1690 }
1691 }
1692
1693 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1694 // have been called.
1695 void SystemDictionary::update_dictionary(JavaThread* current,
1696 InstanceKlass* k,
1697 ClassLoaderData* loader_data) {
1698 MonitorLocker mu1(SystemDictionary_lock);
1699
1700 // Make a new dictionary entry.
1701 Symbol* name = k->name();
1702 Dictionary* dictionary = loader_data->dictionary();
1703 InstanceKlass* sd_check = dictionary->find_class(current, name);
1704 if (sd_check == nullptr) {
1705 dictionary->add_klass(current, name, k);
1706 }
1707 mu1.notify_all();
1708 }
1709
1710 #if INCLUDE_CDS
1711 // Indicate that loader_data has initiated the loading of class k, which
1712 // has already been defined by a parent loader.
1713 // This API should be used only by AOTLinkedClassBulkLoader
1714 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1715 InstanceKlass* k,
1716 ClassLoaderData* loader_data) {
1717 assert(CDSConfig::is_using_aot_linked_classes(), "must be");
1718 assert_locked_or_safepoint(SystemDictionary_lock);
1719 Symbol* name = k->name();
1720 Dictionary* dictionary = loader_data->dictionary();
1721 assert(k->is_loaded(), "must be");
1722 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1723 assert(dictionary->find_class(current, name) == nullptr, "sanity");
1724 dictionary->add_klass(current, name, k);
1725 }
1726 #endif
1727
1728 // Try to find a class name using the loader constraints. The
1729 // loader constraints might know about a class that isn't fully loaded
1730 // yet and these will be ignored.
1731 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1732 Thread* current, Symbol* class_name, Handle class_loader) {
1733
1734 // First see if it has been loaded directly.
1735 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader);
1736 if (klass != nullptr)
1737 return klass;
1738
1739 // Now look to see if it has been loaded elsewhere, and is subject to
1740 // a loader constraint that would require this loader to return the
1741 // klass that is already loaded.
1742 if (Signature::is_array(class_name)) {
1743 // For array classes, their Klass*s are not kept in the
1744 // constraint table. The element Klass*s are.
1745 SignatureStream ss(class_name, false);
1746 int ndims = ss.skip_array_prefix(); // skip all '['s
1747 BasicType t = ss.type();
1748 if (t != T_OBJECT) {
1749 klass = Universe::typeArrayKlass(t);
1750 } else {
1751 MutexLocker mu(current, SystemDictionary_lock);
1752 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1753 }
1754 // If element class already loaded, allocate array klass
1755 if (klass != nullptr) {
1756 klass = klass->array_klass_or_null(ndims);
1757 }
1758 } else {
1759 MutexLocker mu(current, SystemDictionary_lock);
1760 // Non-array classes are easy: simply check the constraint table.
1761 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1762 }
1763
1764 return klass;
1765 }
1766
1767 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1768 Klass* klass_being_linked,
1769 Handle class_loader1,
1770 Handle class_loader2) {
1771 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1772 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1773
1774 Symbol* constraint_name = nullptr;
1775
1776 if (!Signature::is_array(class_name)) {
1777 constraint_name = class_name;
1778 } else {
1779 // For array classes, their Klass*s are not kept in the
1780 // constraint table. The element classes are.
1781 SignatureStream ss(class_name, false);
1782 ss.skip_array_prefix(); // skip all '['s
1783 if (!ss.has_envelope()) {
1784 return true; // primitive types always pass
1785 }
1786 constraint_name = ss.as_symbol();
1787 // Increment refcount to keep constraint_name alive after
1788 // SignatureStream is destructed. It will be decremented below
1789 // before returning.
1790 constraint_name->increment_refcount();
1791 }
1792
1793 Dictionary* dictionary1 = loader_data1->dictionary();
1794 Dictionary* dictionary2 = loader_data2->dictionary();
1795
1796 JavaThread* current = JavaThread::current();
1797 {
1798 MutexLocker mu_s(SystemDictionary_lock);
1799 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1800 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1801 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1802 klass2, loader_data2);
1803 #if INCLUDE_CDS
1804 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1805 !klass_being_linked->in_aot_cache()) {
1806 SystemDictionaryShared::record_linking_constraint(constraint_name,
1807 InstanceKlass::cast(klass_being_linked),
1808 class_loader1, class_loader2);
1809 }
1810 #endif // INCLUDE_CDS
1811 if (Signature::is_array(class_name)) {
1812 constraint_name->decrement_refcount();
1813 }
1814 return result;
1815 }
1816 }
1817
1818 // Add entry to resolution error table to record the error when the first
1819 // attempt to resolve a reference to a class has failed.
1820 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1821 Symbol* error, const char* message,
1822 Symbol* cause, const char* cause_msg) {
1823 {
1824 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1825 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1826 if (entry == nullptr) {
1827 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1828 }
1829 }
1830 }
1831
1832 // Delete a resolution error for RedefineClasses for a constant pool is going away
1833 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1834 ResolutionErrorTable::delete_entry(pool);
1835 }
1836
1837 // Lookup resolution error table. Returns error if found, otherwise null.
1838 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1839 const char** message,
1840 Symbol** cause, const char** cause_msg) {
1841
1842 {
1843 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1844 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1845 if (entry != nullptr) {
1846 *message = entry->message();
1847 *cause = entry->cause();
1848 *cause_msg = entry->cause_msg();
1849 return entry->error();
1850 } else {
1851 return nullptr;
1852 }
1853 }
1854 }
1855
1856 // Add an entry to resolution error table to record an error in resolving or
1857 // validating a nest host. This is used to construct informative error
1858 // messages when IllegalAccessError's occur. If an entry already exists it will
1859 // be updated with the nest host error message.
1860
1861 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1862 int which,
1863 const stringStream& message) {
1864 {
1865 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1866 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1867 if (entry == nullptr) {
1868 // Only add a new entry to the resolution error table if one hasn't been found for this
1869 // constant pool index. In this case resolution succeeded but there's an error in this nest host
1870 // that we use the table to record.
1871 assert(pool->resolved_klass_at(which) != nullptr, "klass should be resolved if there is no entry");
1872 ResolutionErrorTable::add_entry(pool, which, message.as_string(true /* on C-heap */));
1873 } else {
1874 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1875 // still want to add the error message for the higher-level access checks to report. We should
1876 // only reach here under the same error condition, so we can ignore the potential race with setting
1877 // the message.
1878 const char* nhe = entry->nest_host_error();
1879 if (nhe == nullptr) {
1880 entry->set_nest_host_error(message.as_string(true /* on C-heap */));
1881 } else {
1882 DEBUG_ONLY(const char* msg = message.base();)
1883 assert(strcmp(nhe, msg) == 0, "New message %s, differs from original %s", msg, nhe);
1884 }
1885 }
1886 }
1887 }
1888
1889 // Lookup any nest host error
1890 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1891 {
1892 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1893 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1894 if (entry != nullptr) {
1895 return entry->nest_host_error();
1896 } else {
1897 return nullptr;
1898 }
1899 }
1900 }
1901
1902 // Signature constraints ensure that callers and callees agree about
1903 // the meaning of type names in their signatures. This routine is the
1904 // intake for constraints. It collects them from several places:
1905 //
1906 // * LinkResolver::resolve_method (if check_access is true) requires
1907 // that the resolving class (the caller) and the defining class of
1908 // the resolved method (the callee) agree on each type in the
1909 // method's signature.
1910 //
1911 // * LinkResolver::resolve_interface_method performs exactly the same
1912 // checks.
1913 //
1914 // * LinkResolver::resolve_field requires that the constant pool
1915 // attempting to link to a field agree with the field's defining
1916 // class about the type of the field signature.
1917 //
1918 // * klassVtable::initialize_vtable requires that, when a class
1919 // overrides a vtable entry allocated by a superclass, that the
1920 // overriding method (i.e., the callee) agree with the superclass
1921 // on each type in the method's signature.
1922 //
1923 // * klassItable::initialize_itable requires that, when a class fills
1924 // in its itables, for each non-abstract method installed in an
1925 // itable, the method (i.e., the callee) agree with the interface
1926 // on each type in the method's signature.
1927 //
1928 // All those methods have a boolean (check_access, checkconstraints)
1929 // which turns off the checks. This is used from specialized contexts
1930 // such as bootstrapping, dumping, and debugging.
1931 //
1932 // No direct constraint is placed between the class and its
1933 // supertypes. Constraints are only placed along linked relations
1934 // between callers and callees. When a method overrides or implements
1935 // an abstract method in a supertype (superclass or interface), the
1936 // constraints are placed as if the supertype were the caller to the
1937 // overriding method. (This works well, since callers to the
1938 // supertype have already established agreement between themselves and
1939 // the supertype.) As a result of all this, a class can disagree with
1940 // its supertype about the meaning of a type name, as long as that
1941 // class neither calls a relevant method of the supertype, nor is
1942 // called (perhaps via an override) from the supertype.
1943 //
1944 //
1945 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1946 //
1947 // Make sure all class components (including arrays) in the given
1948 // signature will be resolved to the same class in both loaders.
1949 // Returns the name of the type that failed a loader constraint check, or
1950 // null if no constraint failed. No exception except OOME is thrown.
1951 // Arrays are not added to the loader constraint table, their elements are.
1952 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1953 Klass* klass_being_linked,
1954 Handle loader1, Handle loader2,
1955 bool is_method) {
1956 // Nothing to do if loaders are the same.
1957 if (loader1() == loader2()) {
1958 return nullptr;
1959 }
1960
1961 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
1962 if (ss.is_reference()) {
1963 Symbol* sig = ss.as_symbol();
1964 // Note: In the future, if template-like types can take
1965 // arguments, we will want to recognize them and dig out class
1966 // names hiding inside the argument lists.
1967 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
1968 return sig;
1969 }
1970 }
1971 }
1972 return nullptr;
1973 }
1974
1975 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
1976 Symbol* signature,
1977 TRAPS) {
1978
1979 const int iid_as_int = vmIntrinsics::as_int(iid);
1980 assert(MethodHandles::is_signature_polymorphic(iid) &&
1981 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
1982 iid != vmIntrinsics::_invokeGeneric,
1983 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
1984
1985 InvokeMethodKey key(signature, iid_as_int);
1986 Method** met = nullptr;
1987
1988 // We only want one entry in the table for this (signature/id, method) pair but the code
1989 // to create the intrinsic method needs to be outside the lock.
1990 // The first thread claims the entry by adding the key and the other threads wait, until the
1991 // Method has been added as the value.
1992 {
1993 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1994 while (true) {
1995 bool created;
1996 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
1997 assert(met != nullptr, "either created or found");
1998 if (*met != nullptr) {
1999 return *met;
2000 } else if (created) {
2001 // The current thread won the race and will try to create the full entry.
2002 break;
2003 } else {
2004 // Another thread beat us to it, so wait for them to complete
2005 // and return *met; or if they hit an error we get another try.
2006 ml.wait();
2007 // Note it is not safe to read *met here as that entry could have
2008 // been deleted, so we must loop and try put_if_absent again.
2009 }
2010 }
2011 }
2012
2013 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
2014 bool throw_error = HAS_PENDING_EXCEPTION;
2015 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
2016 // Generate a compiled form of the MH intrinsic
2017 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2018 AdapterHandlerLibrary::create_native_wrapper(m);
2019 // Check if have the compiled code.
2020 throw_error = (!m->has_compiled_code());
2021 }
2022
2023 {
2024 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2025 if (throw_error) {
2026 // Remove the entry and let another thread try, or get the same exception.
2027 bool removed = _invoke_method_intrinsic_table->remove(key);
2028 assert(removed, "must be the owner");
2029 ml.notify_all();
2030 } else {
2031 signature->make_permanent(); // The signature is never unloaded.
2032 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2033 m->code()->entry_point() == m->from_compiled_entry()),
2034 "MH intrinsic invariant");
2035 *met = m(); // insert the element
2036 ml.notify_all();
2037 return m();
2038 }
2039 }
2040
2041 // Throw OOM or the pending exception in the JavaThread
2042 if (throw_error && !HAS_PENDING_EXCEPTION) {
2043 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2044 "Out of space in CodeCache for method handle intrinsic");
2045 }
2046 return nullptr;
2047 }
2048
2049 #if INCLUDE_CDS
2050 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) {
2051 assert(SafepointSynchronize::is_at_safepoint(), "must be");
2052 auto do_method = [&] (InvokeMethodKey& key, Method*& m) {
2053 methods->append(m);
2054 };
2055 _invoke_method_intrinsic_table->iterate_all(do_method);
2056 }
2057
2058 void SystemDictionary::restore_archived_method_handle_intrinsics() {
2059 if (UseSharedSpaces) {
2060 EXCEPTION_MARK;
2061 restore_archived_method_handle_intrinsics_impl(THREAD);
2062 if (HAS_PENDING_EXCEPTION) {
2063 // This is probably caused by OOM -- other parts of the CDS archive have direct pointers to
2064 // the archived method handle intrinsics, so we can't really recover from this failure.
2065 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics. Try to increase heap size."));
2066 }
2067 }
2068 }
2069
2070 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) {
2071 Array<Method*>* list = AOTMetaspace::archived_method_handle_intrinsics();
2072 for (int i = 0; i < list->length(); i++) {
2073 methodHandle m(THREAD, list->at(i));
2074 Method::restore_archived_method_handle_intrinsic(m, CHECK);
2075 m->constants()->restore_unshareable_info(CHECK);
2076 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) {
2077 AdapterHandlerLibrary::create_native_wrapper(m);
2078 if (!m->has_compiled_code()) {
2079 ResourceMark rm(THREAD);
2080 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name()));
2081 }
2082 }
2083
2084 // There's no need to grab the InvokeMethodIntrinsicTable_lock, as we are still very early in
2085 // VM start-up -- in init_globals2() -- so we are still running a single Java thread. It's not
2086 // possible to have a contention.
2087 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id());
2088 InvokeMethodKey key(m->signature(), iid_as_int);
2089 bool created = _invoke_method_intrinsic_table->put(key, m());
2090 assert(created, "unexpected contention");
2091 }
2092 }
2093 #endif // INCLUDE_CDS
2094
2095 // Helper for unpacking the return value from linkMethod and linkCallSite.
2096 static Method* unpack_method_and_appendix(Handle mname,
2097 Klass* accessing_klass,
2098 objArrayHandle appendix_box,
2099 Handle* appendix_result,
2100 TRAPS) {
2101 if (mname.not_null()) {
2102 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2103 if (m != nullptr) {
2104 oop appendix = appendix_box->obj_at(0);
2105 LogTarget(Info, methodhandles) lt;
2106 if (lt.develop_is_enabled()) {
2107 ResourceMark rm(THREAD);
2108 LogStream ls(lt);
2109 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2110 m->print_on(&ls);
2111 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2112 ls.cr();
2113 }
2114
2115 (*appendix_result) = Handle(THREAD, appendix);
2116 // the target is stored in the cpCache and if a reference to this
2117 // MemberName is dropped we need a way to make sure the
2118 // class_loader containing this method is kept alive.
2119 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2120 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2121 this_key->record_dependency(m->method_holder());
2122 return mh();
2123 }
2124 }
2125 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2126 }
2127
2128 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2129 Symbol* name,
2130 Symbol* signature,
2131 Klass* accessing_klass,
2132 Handle* appendix_result,
2133 TRAPS) {
2134 guarantee(THREAD->can_call_java(), "");
2135 Handle method_type =
2136 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2137
2138 int ref_kind = JVM_REF_invokeVirtual;
2139 oop name_oop = StringTable::intern(name, CHECK_NULL);
2140 Handle name_str (THREAD, name_oop);
2141 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2142 assert(appendix_box->obj_at(0) == nullptr, "");
2143
2144 // This should not happen. JDK code should take care of that.
2145 if (accessing_klass == nullptr || method_type.is_null()) {
2146 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2147 }
2148
2149 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2150 JavaCallArguments args;
2151 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2152 args.push_int(ref_kind);
2153 args.push_oop(Handle(THREAD, klass->java_mirror()));
2154 args.push_oop(name_str);
2155 args.push_oop(method_type);
2156 args.push_oop(appendix_box);
2157 JavaValue result(T_OBJECT);
2158 JavaCalls::call_static(&result,
2159 vmClasses::MethodHandleNatives_klass(),
2160 vmSymbols::linkMethod_name(),
2161 vmSymbols::linkMethod_signature(),
2162 &args, CHECK_NULL);
2163 Handle mname(THREAD, result.get_oop());
2164 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2165 }
2166
2167 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2168 // We must ensure that all class loaders everywhere will reach this class, for any client.
2169 // This is a safe bet for public classes in java.lang, such as Object and String.
2170 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2171 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2172 static bool is_always_visible_class(oop mirror) {
2173 Klass* klass = java_lang_Class::as_Klass(mirror);
2174 if (klass->is_objArray_klass()) {
2175 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2176 }
2177 if (klass->is_typeArray_klass()) {
2178 return true; // primitive array
2179 }
2180 assert(klass->is_instance_klass(), "%s", klass->external_name());
2181 InstanceKlass* ik = InstanceKlass::cast(klass);
2182 return ik->is_public() &&
2183 (ik->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2184 ik->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2185 }
2186
2187 // Find or construct the Java mirror (java.lang.Class instance) for
2188 // the given field type signature, as interpreted relative to the
2189 // given class loader. Handles primitives, void, references, arrays,
2190 // and all other reflectable types, except method types.
2191 // N.B. Code in reflection should use this entry point.
2192 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2193 Klass* accessing_klass,
2194 SignatureStream::FailureMode failure_mode,
2195 TRAPS) {
2196
2197 Handle class_loader;
2198
2199 // What we have here must be a valid field descriptor,
2200 // and all valid field descriptors are supported.
2201 // Produce the same java.lang.Class that reflection reports.
2202 if (accessing_klass != nullptr) {
2203 class_loader = Handle(THREAD, accessing_klass->class_loader());
2204 }
2205 ResolvingSignatureStream ss(signature, class_loader, false);
2206 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2207 if (mirror_oop == nullptr) {
2208 return Handle(); // report failure this way
2209 }
2210 Handle mirror(THREAD, mirror_oop);
2211
2212 if (accessing_klass != nullptr) {
2213 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2214 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2215 if (sel_klass != nullptr) {
2216 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2217 }
2218 }
2219 return mirror;
2220 }
2221
2222
2223 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2224 // signature, as interpreted relative to the given class loader.
2225 // Because of class loader constraints, all method handle usage must be
2226 // consistent with this loader.
2227 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2228 Klass* accessing_klass,
2229 TRAPS) {
2230 Handle empty;
2231 OopHandle* o;
2232 {
2233 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2234 o = _invoke_method_type_table->get(signature);
2235 }
2236
2237 if (o != nullptr) {
2238 oop mt = o->resolve();
2239 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2240 return Handle(THREAD, mt);
2241 } else if (!THREAD->can_call_java()) {
2242 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2243 return Handle(); // do not attempt from within compiler, unless it was cached
2244 }
2245
2246 Handle class_loader;
2247 if (accessing_klass != nullptr) {
2248 class_loader = Handle(THREAD, accessing_klass->class_loader());
2249 }
2250 bool can_be_cached = true;
2251 int npts = ArgumentCount(signature).size();
2252 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2253 int arg = 0;
2254 Handle rt; // the return type from the signature
2255 ResourceMark rm(THREAD);
2256 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2257 oop mirror = nullptr;
2258 if (can_be_cached) {
2259 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2260 mirror = ss.as_java_mirror(Handle(), SignatureStream::ReturnNull, CHECK_(empty));
2261 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2262 // Fall back to accessing_klass context.
2263 can_be_cached = false;
2264 }
2265 }
2266 if (!can_be_cached) {
2267 // Resolve, throwing a real error if it doesn't work.
2268 mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2269 }
2270 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2271 if (ss.at_return_type())
2272 rt = Handle(THREAD, mirror);
2273 else
2274 pts->obj_at_put(arg++, mirror);
2275
2276 // Check accessibility.
2277 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2278 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2279 mirror = nullptr; // safety
2280 // Emulate ConstantPool::verify_constant_pool_resolve.
2281 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2282 }
2283 }
2284 assert(arg == npts, "");
2285
2286 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2287 JavaCallArguments args(Handle(THREAD, rt()));
2288 args.push_oop(pts);
2289 JavaValue result(T_OBJECT);
2290 JavaCalls::call_static(&result,
2291 vmClasses::MethodHandleNatives_klass(),
2292 vmSymbols::findMethodHandleType_name(),
2293 vmSymbols::findMethodHandleType_signature(),
2294 &args, CHECK_(empty));
2295 Handle method_type(THREAD, result.get_oop());
2296
2297 if (can_be_cached) {
2298 // We can cache this MethodType inside the JVM.
2299 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2300 bool created = false;
2301 assert(method_type != nullptr, "unexpected null");
2302 OopHandle* h = _invoke_method_type_table->get(signature);
2303 if (h == nullptr) {
2304 signature->make_permanent(); // The signature is never unloaded.
2305 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2306 bool created = _invoke_method_type_table->put(signature, elem);
2307 assert(created, "better be created");
2308 }
2309 }
2310 // report back to the caller with the MethodType
2311 return method_type;
2312 }
2313
2314 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2315 Klass* accessing_klass,
2316 TRAPS) {
2317 Handle empty;
2318 ResourceMark rm(THREAD);
2319 SignatureStream ss(signature, /*is_method=*/ false);
2320 if (!ss.is_done()) {
2321 Handle class_loader;
2322 if (accessing_klass != nullptr) {
2323 class_loader = Handle(THREAD, accessing_klass->class_loader());
2324 }
2325 oop mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2326 ss.next();
2327 if (ss.is_done()) {
2328 return Handle(THREAD, mirror);
2329 }
2330 }
2331 return empty;
2332 }
2333
2334 // Ask Java code to find or construct a method handle constant.
2335 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2336 int ref_kind, //e.g., JVM_REF_invokeVirtual
2337 Klass* callee,
2338 Symbol* name,
2339 Symbol* signature,
2340 TRAPS) {
2341 Handle empty;
2342 if (caller == nullptr) {
2343 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2344 }
2345 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2346 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2347
2348 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2349 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2350 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2351 java_lang_invoke_MemberName::set_name (mname(), name_str());
2352 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2353 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2354
2355 if (ref_kind == JVM_REF_invokeVirtual &&
2356 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2357 // Skip resolution for public signature polymorphic methods such as
2358 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2359 // They require appendix argument which MemberName resolution doesn't handle.
2360 // There's special logic on JDK side to handle them
2361 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2362 } else {
2363 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2364 }
2365
2366 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2367 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2368
2369 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2370 JavaCallArguments args;
2371 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2372 args.push_int(ref_kind);
2373 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2374 args.push_oop(name_str);
2375 args.push_oop(type);
2376 JavaValue result(T_OBJECT);
2377 JavaCalls::call_static(&result,
2378 vmClasses::MethodHandleNatives_klass(),
2379 vmSymbols::linkMethodHandleConstant_name(),
2380 vmSymbols::linkMethodHandleConstant_signature(),
2381 &args, CHECK_(empty));
2382 return Handle(THREAD, result.get_oop());
2383 }
2384
2385 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2386 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2387 // with linkage results being stored back into the bootstrap specifier.
2388 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2389 // Resolve the bootstrap specifier, its name, type, and static arguments
2390 bootstrap_specifier.resolve_bsm(CHECK);
2391
2392 // This should not happen. JDK code should take care of that.
2393 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2394 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2395 }
2396
2397 bool is_indy = bootstrap_specifier.is_method_call();
2398 objArrayHandle appendix_box;
2399 if (is_indy) {
2400 // Some method calls may require an appendix argument. Arrange to receive it.
2401 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2402 assert(appendix_box->obj_at(0) == nullptr, "");
2403 }
2404
2405 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2406 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2407 JavaCallArguments args;
2408 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2409 args.push_oop(bootstrap_specifier.bsm());
2410 args.push_oop(bootstrap_specifier.name_arg());
2411 args.push_oop(bootstrap_specifier.type_arg());
2412 args.push_oop(bootstrap_specifier.arg_values());
2413 if (is_indy) {
2414 args.push_oop(appendix_box);
2415 }
2416 JavaValue result(T_OBJECT);
2417 JavaCalls::call_static(&result,
2418 vmClasses::MethodHandleNatives_klass(),
2419 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2420 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2421 &args, CHECK);
2422
2423 Handle value(THREAD, result.get_oop());
2424 if (is_indy) {
2425 Handle appendix;
2426 Method* method = unpack_method_and_appendix(value,
2427 bootstrap_specifier.caller(),
2428 appendix_box,
2429 &appendix, CHECK);
2430 methodHandle mh(THREAD, method);
2431 bootstrap_specifier.set_resolved_method(mh, appendix);
2432 } else {
2433 bootstrap_specifier.set_resolved_value(value);
2434 }
2435
2436 // sanity check
2437 assert(bootstrap_specifier.is_resolved() ||
2438 (bootstrap_specifier.is_method_call() &&
2439 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2440 }
2441
2442
2443 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2444 assert(m != nullptr, "Unexpected nullptr Method*");
2445 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2446 }
2447
2448 // ----------------------------------------------------------------------------
2449
2450 void SystemDictionary::print_on(outputStream *st) {
2451 CDS_ONLY(SystemDictionaryShared::print_on(st));
2452 GCMutexLocker mu(SystemDictionary_lock);
2453
2454 ClassLoaderDataGraph::print_dictionary(st);
2455
2456 // Placeholders
2457 PlaceholderTable::print_on(st);
2458 st->cr();
2459
2460 // loader constraints - print under SD_lock
2461 LoaderConstraintTable::print_on(st);
2462 st->cr();
2463 }
2464
2465 void SystemDictionary::print() { print_on(tty); }
2466
2467 void SystemDictionary::verify() {
2468
2469 GCMutexLocker mu(SystemDictionary_lock);
2470
2471 // Verify dictionary
2472 ClassLoaderDataGraph::verify_dictionary();
2473
2474 // Verify constraint table
2475 LoaderConstraintTable::verify();
2476 }
2477
2478 void SystemDictionary::dump(outputStream *st, bool verbose) {
2479 assert_locked_or_safepoint(SystemDictionary_lock);
2480 if (verbose) {
2481 print_on(st);
2482 } else {
2483 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2484 ClassLoaderDataGraph::print_table_statistics(st);
2485 LoaderConstraintTable::print_table_statistics(st);
2486 }
2487 }
2488
2489 // Utility for dumping dictionaries.
2490 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2491 DCmdWithParser(output, heap),
2492 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2493 "BOOLEAN", false, "false") {
2494 _dcmdparser.add_dcmd_option(&_verbose);
2495 }
2496
2497 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2498 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2499 _verbose.value());
2500 VMThread::execute(&dumper);
2501 }