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