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