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/classLoaderExt.hpp"
34 #include "classfile/classLoadInfo.hpp"
35 #include "classfile/dictionary.hpp"
36 #include "classfile/javaClasses.inline.hpp"
37 #include "classfile/klassFactory.hpp"
38 #include "classfile/loaderConstraints.hpp"
39 #include "classfile/packageEntry.hpp"
40 #include "classfile/placeholders.hpp"
41 #include "classfile/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/fieldStreams.inline.hpp"
59 #include "oops/instanceKlass.hpp"
60 #include "oops/klass.inline.hpp"
61 #include "oops/method.inline.hpp"
62 #include "oops/objArrayKlass.hpp"
63 #include "oops/objArrayOop.inline.hpp"
64 #include "oops/oop.inline.hpp"
65 #include "oops/oop.hpp"
66 #include "oops/oopHandle.hpp"
67 #include "oops/oopHandle.inline.hpp"
68 #include "oops/symbol.hpp"
69 #include "oops/typeArrayKlass.hpp"
70 #include "oops/inlineKlass.inline.hpp"
71 #include "prims/jvmtiExport.hpp"
72 #include "prims/methodHandles.hpp"
73 #include "runtime/arguments.hpp"
74 #include "runtime/atomic.hpp"
75 #include "runtime/handles.inline.hpp"
76 #include "runtime/java.hpp"
77 #include "runtime/javaCalls.hpp"
78 #include "runtime/mutexLocker.hpp"
79 #include "runtime/os.hpp"
80 #include "runtime/sharedRuntime.hpp"
81 #include "runtime/signature.hpp"
82 #include "runtime/synchronizer.hpp"
83 #include "services/classLoadingService.hpp"
84 #include "services/diagnosticCommand.hpp"
85 #include "services/finalizerService.hpp"
86 #include "services/threadService.hpp"
87 #include "utilities/growableArray.hpp"
88 #include "utilities/macros.hpp"
89 #include "utilities/utf8.hpp"
90 #if INCLUDE_CDS
91 #include "classfile/systemDictionaryShared.hpp"
92 #endif
93 #if INCLUDE_JFR
94 #include "jfr/jfr.hpp"
95 #endif
96
97 class InvokeMethodKey : public StackObj {
98 private:
99 Symbol* _symbol;
100 intptr_t _iid;
101
102 public:
103 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
104 _symbol(symbol),
105 _iid(iid) {}
106
107 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
108 return k1._symbol == k2._symbol && k1._iid == k2._iid;
109 }
110
111 static unsigned int compute_hash(const InvokeMethodKey &k) {
112 Symbol* sym = k._symbol;
113 intptr_t iid = k._iid;
114 unsigned int hash = (unsigned int) sym -> identity_hash();
115 return (unsigned int) (hash ^ iid);
116 }
117
118 };
119
120 using InvokeMethodIntrinsicTable = ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
121 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
122 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
123 using InvokeMethodTypeTable = ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
124 static InvokeMethodTypeTable* _invoke_method_type_table;
125
126 OopHandle SystemDictionary::_java_system_loader;
127 OopHandle SystemDictionary::_java_platform_loader;
128
129 // ----------------------------------------------------------------------------
130 // Java-level SystemLoader and PlatformLoader
131 oop SystemDictionary::java_system_loader() {
132 return _java_system_loader.resolve();
133 }
134
135 oop SystemDictionary::java_platform_loader() {
136 return _java_platform_loader.resolve();
137 }
138
139 void SystemDictionary::compute_java_loaders(TRAPS) {
140 if (_java_platform_loader.is_empty()) {
141 oop platform_loader = get_platform_class_loader_impl(CHECK);
142 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
143 } else {
144 // It must have been restored from the archived module graph
145 assert(CDSConfig::is_using_archive(), "must be");
146 assert(CDSConfig::is_using_full_module_graph(), "must be");
147 DEBUG_ONLY(
148 oop platform_loader = get_platform_class_loader_impl(CHECK);
149 assert(_java_platform_loader.resolve() == platform_loader, "must be");
150 )
151 }
152
153 if (_java_system_loader.is_empty()) {
154 oop system_loader = get_system_class_loader_impl(CHECK);
155 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
156 } else {
157 // It must have been restored from the archived module graph
158 assert(CDSConfig::is_using_archive(), "must be");
159 assert(CDSConfig::is_using_full_module_graph(), "must be");
160 DEBUG_ONLY(
161 oop system_loader = get_system_class_loader_impl(CHECK);
162 assert(_java_system_loader.resolve() == system_loader, "must be");
163 )
164 }
165 }
166
167 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
168 JavaValue result(T_OBJECT);
169 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
170 JavaCalls::call_static(&result,
171 class_loader_klass,
172 vmSymbols::getSystemClassLoader_name(),
173 vmSymbols::void_classloader_signature(),
174 CHECK_NULL);
175 return result.get_oop();
176 }
177
178 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
179 JavaValue result(T_OBJECT);
180 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
181 JavaCalls::call_static(&result,
182 class_loader_klass,
183 vmSymbols::getPlatformClassLoader_name(),
184 vmSymbols::void_classloader_signature(),
185 CHECK_NULL);
186 return result.get_oop();
187 }
188
189 // Helper function
190 inline ClassLoaderData* class_loader_data(Handle class_loader) {
191 return ClassLoaderData::class_loader_data(class_loader());
192 }
193
194 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
195 if (create_mirror_cld) {
196 // Add a new class loader data to the graph.
197 return ClassLoaderDataGraph::add(class_loader, true);
198 } else {
199 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
200 ClassLoaderDataGraph::find_or_create(class_loader);
201 }
202 }
203
204 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
205 assert(_java_system_loader.is_empty(), "already set!");
206 _java_system_loader = cld->class_loader_handle();
207
208 }
209
210 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
211 assert(_java_platform_loader.is_empty(), "already set!");
212 _java_platform_loader = cld->class_loader_handle();
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 ; (and Q and ; for value types).
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->java_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(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS");
925
926 // (1) Check if we are loading into the same loader as in dump time.
927
928 if (ik->is_shared_boot_class()) {
929 if (class_loader() != nullptr) {
930 return false;
931 }
932 } else if (ik->is_shared_platform_class()) {
933 if (class_loader() != java_platform_loader()) {
934 return false;
935 }
936 } else if (ik->is_shared_app_class()) {
937 if (class_loader() != java_system_loader()) {
938 return false;
939 }
940 } else {
941 // ik was loaded by a custom loader during dump time
942 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
943 return false;
944 } else {
945 return true;
946 }
947 }
948
949 // (2) Check if we are loading into the same module from the same location as in dump time.
950
951 if (CDSConfig::is_using_optimized_module_handling()) {
952 // Class visibility has not changed between dump time and run time, so a class
953 // that was visible (and thus archived) during dump time is always visible during runtime.
954 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
955 "visibility cannot change between dump time and runtime");
956 return true;
957 }
958 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
959 }
960
961 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
962 InstanceKlass* ik,
963 PackageEntry* pkg_entry,
964 Handle class_loader) {
965 int scp_index = ik->shared_classpath_index();
966 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
967 assert(scp_index >= 0, "must be");
968 const AOTClassLocation* cl = AOTClassLocationConfig::runtime()->class_location_at(scp_index);
969 if (!Universe::is_module_initialized()) {
970 assert(cl != nullptr, "must be");
971 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
972 // has restricted the classes can be loaded at this step to be only:
973 // [1] cs->is_modules_image(): classes in java.base, or,
974 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
975 assert(cl->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
976 "only these classes can be loaded before the module system is initialized");
977 assert(class_loader.is_null(), "sanity");
978 return true;
979 }
980
981 if (pkg_entry == nullptr) {
982 // We might have looked up pkg_entry before the module system was initialized.
983 // Need to reload it now.
984 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
985 if (pkg_name != nullptr) {
986 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
987 }
988 }
989
990 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
991 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
992 bool was_archived_from_named_module = !cl->has_unnamed_module();
993 bool visible;
994
995 if (was_archived_from_named_module) {
996 if (should_be_in_named_module) {
997 // Is the module loaded from the same location as during dump time?
998 visible = mod_entry->shared_path_index() == scp_index;
999 if (visible) {
1000 assert(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS");
1001 }
1002 } else {
1003 // During dump time, this class was in a named module, but at run time, this class should be
1004 // in an unnamed module.
1005 visible = false;
1006 }
1007 } else {
1008 if (should_be_in_named_module) {
1009 // During dump time, this class was in an unnamed, but at run time, this class should be
1010 // in a named module.
1011 visible = false;
1012 } else {
1013 visible = true;
1014 }
1015 }
1016
1017 return visible;
1018 }
1019
1020 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1021 Handle class_loader, bool is_superclass, TRAPS) {
1022 assert(super_type->is_shared(), "must be");
1023
1024 // Quick check if the super type has been already loaded.
1025 // + Don't do it for unregistered classes -- they can be unloaded so
1026 // super_type->class_loader_data() could be stale.
1027 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1028 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {
1029 // Check if the superclass is loaded by the current class_loader
1030 Symbol* name = super_type->name();
1031 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader);
1032 if (check == super_type) {
1033 return true;
1034 }
1035 }
1036
1037 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(),
1038 class_loader, is_superclass, CHECK_false);
1039 if (found == super_type) {
1040 return true;
1041 } else {
1042 // The dynamically resolved super type is not the same as the one we used during dump time,
1043 // so we cannot use the class.
1044 return false;
1045 }
1046 }
1047
1048 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader, TRAPS) {
1049 // Check the superclass and interfaces. They must be the same
1050 // as in dump time, because the layout of <ik> depends on
1051 // the specific layout of ik->super() and ik->local_interfaces().
1052 //
1053 // If unexpected superclass or interfaces are found, we cannot
1054 // load <ik> from the shared archive.
1055
1056 if (ik->super() != nullptr) {
1057 bool check_super = check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1058 class_loader, true,
1059 CHECK_false);
1060 if (!check_super) {
1061 return false;
1062 }
1063 }
1064
1065 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1066 int num_interfaces = interfaces->length();
1067 for (int index = 0; index < num_interfaces; index++) {
1068 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, false,
1069 CHECK_false);
1070 if (!check_interface) {
1071 return false;
1072 }
1073 }
1074
1075 return true;
1076 }
1077
1078 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1079 Handle class_loader,
1080 Handle protection_domain,
1081 const ClassFileStream *cfs,
1082 PackageEntry* pkg_entry,
1083 TRAPS) {
1084 assert(ik != nullptr, "sanity");
1085 assert(ik->is_shared(), "sanity");
1086 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1087 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1088 Symbol* class_name = ik->name();
1089
1090 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1091 ik->set_shared_loading_failed();
1092 return nullptr;
1093 }
1094
1095 bool check = check_shared_class_super_types(ik, class_loader, CHECK_NULL);
1096 if (!check) {
1097 ik->set_shared_loading_failed();
1098 return nullptr;
1099 }
1100
1101 if (ik->has_inline_type_fields()) {
1102 for (AllFieldStream fs(ik); !fs.done(); fs.next()) {
1103 if (fs.access_flags().is_static()) continue;
1104 Symbol* sig = fs.signature();
1105 if (fs.is_null_free_inline_type()) {
1106 // Pre-load inline class
1107 TempNewSymbol name = Signature::strip_envelope(sig);
1108 Klass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name,
1109 class_loader, false, CHECK_NULL);
1110 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index());
1111 if (real_k != k) {
1112 // oops, the app has substituted a different version of k!
1113 return nullptr;
1114 }
1115 } else if (Signature::has_envelope(sig)) {
1116 TempNewSymbol name = Signature::strip_envelope(sig);
1117 if (name != ik->name() && ik->is_class_in_loadable_descriptors_attribute(name)) {
1118 Klass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name,
1119 class_loader, false, THREAD);
1120 if (HAS_PENDING_EXCEPTION) {
1121 CLEAR_PENDING_EXCEPTION;
1122 }
1123 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index());
1124 if (real_k != k) {
1125 // oops, the app has substituted a different version of k!
1126 return nullptr;
1127 }
1128 }
1129 }
1130 }
1131 }
1132
1133 InstanceKlass* new_ik = nullptr;
1134 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1135 // It will be skipped for shared VM hidden lambda proxy classes.
1136 if (!ik->is_hidden()) {
1137 new_ik = KlassFactory::check_shared_class_file_load_hook(
1138 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1139 }
1140 if (new_ik != nullptr) {
1141 // The class is changed by CFLH. Return the new class. The shared class is
1142 // not used.
1143 return new_ik;
1144 }
1145
1146 // Adjust methods to recover missing data. They need addresses for
1147 // interpreter entry points and their default native method address
1148 // must be reset.
1149
1150 // Shared classes are all currently loaded by either the bootstrap or
1151 // internal parallel class loaders, so this will never cause a deadlock
1152 // on a custom class loader lock.
1153 // Since this class is already locked with parallel capable class
1154 // loaders, including the bootstrap loader via the placeholder table,
1155 // this lock is currently a nop.
1156
1157 ClassLoaderData* loader_data = class_loader_data(class_loader);
1158 {
1159 HandleMark hm(THREAD);
1160 Handle lockObject = get_loader_lock_or_null(class_loader);
1161 ObjectLocker ol(lockObject, THREAD);
1162 // prohibited package check assumes all classes loaded from archive call
1163 // restore_unshareable_info which calls ik->set_package()
1164 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1165 }
1166
1167 load_shared_class_misc(ik, loader_data);
1168
1169 return ik;
1170 }
1171
1172 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1173 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1174
1175 // For boot loader, ensure that GetSystemPackage knows that a class in this
1176 // package was loaded.
1177 if (loader_data->is_the_null_class_loader_data()) {
1178 s2 path_index = ik->shared_classpath_index();
1179 ik->set_classpath_index(path_index);
1180 }
1181
1182 // notify a class loaded from shared object
1183 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1184
1185 if (CDSConfig::is_dumping_final_static_archive()) {
1186 SystemDictionaryShared::init_dumptime_info_from_preimage(ik);
1187 }
1188 }
1189
1190 #endif // INCLUDE_CDS
1191
1192 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1193
1194 if (class_loader.is_null()) {
1195 ResourceMark rm(THREAD);
1196 PackageEntry* pkg_entry = nullptr;
1197 bool search_only_bootloader_append = false;
1198
1199 // Find the package in the boot loader's package entry table.
1200 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1201 if (pkg_name != nullptr) {
1202 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1203 }
1204
1205 // Prior to attempting to load the class, enforce the boot loader's
1206 // visibility boundaries.
1207 if (!Universe::is_module_initialized()) {
1208 // During bootstrapping, prior to module initialization, any
1209 // class attempting to be loaded must be checked against the
1210 // java.base packages in the boot loader's PackageEntryTable.
1211 // No class outside of java.base is allowed to be loaded during
1212 // this bootstrapping window.
1213 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1214 // Class is either in the unnamed package or in
1215 // a named package within the unnamed module. Either
1216 // case is outside of java.base, do not attempt to
1217 // load the class post java.base definition. If
1218 // java.base has not been defined, let the class load
1219 // and its package will be checked later by
1220 // ModuleEntryTable::verify_javabase_packages.
1221 if (ModuleEntryTable::javabase_defined()) {
1222 return nullptr;
1223 }
1224 } else {
1225 // Check that the class' package is defined within java.base.
1226 ModuleEntry* mod_entry = pkg_entry->module();
1227 Symbol* mod_entry_name = mod_entry->name();
1228 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1229 return nullptr;
1230 }
1231 }
1232 } else {
1233 // After the module system has been initialized, check if the class'
1234 // package is in a module defined to the boot loader.
1235 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1236 // Class is either in the unnamed package, in a named package
1237 // within a module not defined to the boot loader or in a
1238 // a named package within the unnamed module. In all cases,
1239 // limit visibility to search for the class only in the boot
1240 // loader's append path.
1241 if (!ClassLoader::has_bootclasspath_append()) {
1242 // If there is no bootclasspath append entry, no need to continue
1243 // searching.
1244 return nullptr;
1245 }
1246 search_only_bootloader_append = true;
1247 }
1248 }
1249
1250 // Prior to bootstrapping's module initialization, never load a class outside
1251 // of the boot loader's module path
1252 assert(Universe::is_module_initialized() ||
1253 !search_only_bootloader_append,
1254 "Attempt to load a class outside of boot loader's module path");
1255
1256 // Search for classes in the CDS archive.
1257 InstanceKlass* k = nullptr;
1258
1259 #if INCLUDE_CDS
1260 if (CDSConfig::is_using_archive())
1261 {
1262 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1263 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1264 if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1265 SharedClassLoadingMark slm(THREAD, ik);
1266 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1267 }
1268 }
1269 #endif
1270
1271 if (k == nullptr) {
1272 // Use VM class loader
1273 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1274 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1275 }
1276
1277 // find_or_define_instance_class may return a different InstanceKlass
1278 if (k != nullptr) {
1279 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1280 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1281 }
1282 return k;
1283 } else {
1284 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1285 ResourceMark rm(THREAD);
1286
1287 JavaThread* jt = THREAD;
1288
1289 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1290 ClassLoader::perf_app_classload_selftime(),
1291 ClassLoader::perf_app_classload_count(),
1292 jt->get_thread_stat()->perf_recursion_counts_addr(),
1293 jt->get_thread_stat()->perf_timers_addr(),
1294 PerfClassTraceTime::CLASS_LOAD);
1295
1296 // Translate to external class name format, i.e., convert '/' chars to '.'
1297 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1298
1299 JavaValue result(T_OBJECT);
1300
1301 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1302
1303 // Call public unsynchronized loadClass(String) directly for all class loaders.
1304 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1305 // acquire a class-name based lock rather than the class loader object lock.
1306 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1307 JavaCalls::call_virtual(&result,
1308 class_loader,
1309 spec_klass,
1310 vmSymbols::loadClass_name(),
1311 vmSymbols::string_class_signature(),
1312 string,
1313 CHECK_NULL);
1314
1315 assert(result.get_type() == T_OBJECT, "just checking");
1316 oop obj = result.get_oop();
1317
1318 // Primitive classes return null since forName() can not be
1319 // used to obtain any of the Class objects representing primitives or void
1320 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1321 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1322 // For user defined Java class loaders, check that the name returned is
1323 // the same as that requested. This check is done for the bootstrap
1324 // loader when parsing the class file.
1325 if (class_name == k->name()) {
1326 return k;
1327 }
1328 }
1329 // Class is not found or has the wrong name, return null
1330 return nullptr;
1331 }
1332 }
1333
1334 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1335 Handle class_loader,
1336 TRAPS) {
1337
1338 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1339
1340 // If everything was OK (no exceptions, no null return value), and
1341 // class_loader is NOT the defining loader, do a little more bookkeeping.
1342 if (loaded_class != nullptr &&
1343 loaded_class->class_loader() != class_loader()) {
1344
1345 ClassLoaderData* loader_data = class_loader_data(class_loader);
1346 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1347
1348 // Record dependency for non-parent delegation.
1349 // This recording keeps the defining class loader of the klass (loaded_class) found
1350 // from being unloaded while the initiating class loader is loaded
1351 // even if the reference to the defining class loader is dropped
1352 // before references to the initiating class loader.
1353 loader_data->record_dependency(loaded_class);
1354
1355 update_dictionary(THREAD, loaded_class, loader_data);
1356
1357 if (JvmtiExport::should_post_class_load()) {
1358 JvmtiExport::post_class_load(THREAD, loaded_class);
1359 }
1360 }
1361 return loaded_class;
1362 }
1363
1364 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1365 EventClassDefine event;
1366 if (event.should_commit()) {
1367 event.set_definedClass(k);
1368 event.set_definingClassLoader(def_cld);
1369 event.commit();
1370 }
1371 }
1372
1373 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1374
1375 ClassLoaderData* loader_data = k->class_loader_data();
1376 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1377
1378 // Bootstrap and other parallel classloaders don't acquire a lock,
1379 // they use placeholder token.
1380 // If a parallelCapable class loader calls define_instance_class instead of
1381 // find_or_define_instance_class to get here, we have a timing
1382 // hole with systemDictionary updates and check_constraints
1383 if (!is_parallelCapable(class_loader)) {
1384 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1385 get_loader_lock_or_null(class_loader)),
1386 "define called without lock");
1387 }
1388
1389 // Check class-loading constraints. Throw exception if violation is detected.
1390 // Grabs and releases SystemDictionary_lock
1391 // The check_constraints/find_class call and update_dictionary sequence
1392 // must be "atomic" for a specific class/classloader pair so we never
1393 // define two different instanceKlasses for that class/classloader pair.
1394 // Existing classloaders will call define_instance_class with the
1395 // classloader lock held
1396 // Parallel classloaders will call find_or_define_instance_class
1397 // which will require a token to perform the define class
1398 check_constraints(k, loader_data, true, CHECK);
1399
1400 // Register class just loaded with class loader (placed in ArrayList)
1401 // Note we do this before updating the dictionary, as this can
1402 // fail with an OutOfMemoryError (if it does, we will *not* put this
1403 // class in the dictionary and will not update the class hierarchy).
1404 // JVMTI FollowReferences needs to find the classes this way.
1405 if (k->class_loader() != nullptr) {
1406 methodHandle m(THREAD, Universe::loader_addClass_method());
1407 JavaValue result(T_VOID);
1408 JavaCallArguments args(class_loader);
1409 args.push_oop(Handle(THREAD, k->java_mirror()));
1410 JavaCalls::call(&result, m, &args, CHECK);
1411 }
1412
1413 // Add to class hierarchy, and do possible deoptimizations.
1414 k->add_to_hierarchy(THREAD);
1415
1416 // Add to systemDictionary - so other classes can see it.
1417 // Grabs and releases SystemDictionary_lock
1418 update_dictionary(THREAD, k, loader_data);
1419
1420 // notify jvmti
1421 if (JvmtiExport::should_post_class_load()) {
1422 JvmtiExport::post_class_load(THREAD, k);
1423 }
1424 post_class_define_event(k, loader_data);
1425 }
1426
1427 // Support parallel classloading
1428 // All parallel class loaders, including bootstrap classloader
1429 // lock a placeholder entry for this class/class_loader pair
1430 // to allow parallel defines of different classes for this class loader
1431 // With AllowParallelDefine flag==true, in case they do not synchronize around
1432 // FindLoadedClass/DefineClass, calls, we check for parallel
1433 // loading for them, wait if a defineClass is in progress
1434 // and return the initial requestor's results
1435 // This flag does not apply to the bootstrap classloader.
1436 // With AllowParallelDefine flag==false, call through to define_instance_class
1437 // which will throw LinkageError: duplicate class definition.
1438 // False is the requested default.
1439 // For better performance, the class loaders should synchronize
1440 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1441 // potentially waste time reading and parsing the bytestream.
1442 // Note: VM callers should ensure consistency of k/class_name,class_loader
1443 // Be careful when modifying this code: once you have run
1444 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1445 // you need to find_and_remove it before returning.
1446 // So be careful to not exit with a CHECK_ macro between these calls.
1447 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1448 InstanceKlass* k, TRAPS) {
1449
1450 Symbol* name_h = k->name();
1451 ClassLoaderData* loader_data = class_loader_data(class_loader);
1452 Dictionary* dictionary = loader_data->dictionary();
1453
1454 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1455 {
1456 MutexLocker mu(THREAD, SystemDictionary_lock);
1457 // First check if class already defined
1458 if (is_parallelDefine(class_loader)) {
1459 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1460 if (check != nullptr) {
1461 return check;
1462 }
1463 }
1464
1465 // Acquire define token for this class/classloader
1466 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1467 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1468 // Wait if another thread defining in parallel
1469 // All threads wait - even those that will throw duplicate class: otherwise
1470 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1471 // if other thread has not finished updating dictionary
1472 while (probe->definer() != nullptr) {
1473 SystemDictionary_lock->wait();
1474 }
1475 // Only special cases allow parallel defines and can use other thread's results
1476 // Other cases fall through, and may run into duplicate defines
1477 // caught by finding an entry in the SystemDictionary
1478 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1479 InstanceKlass* ik = probe->instance_klass();
1480 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1481 SystemDictionary_lock->notify_all();
1482 #ifdef ASSERT
1483 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1484 assert(check != nullptr, "definer missed recording success");
1485 #endif
1486 return ik;
1487 } else {
1488 // This thread will define the class (even if earlier thread tried and had an error)
1489 probe->set_definer(THREAD);
1490 }
1491 }
1492
1493 define_instance_class(k, class_loader, THREAD);
1494
1495 // definer must notify any waiting threads
1496 {
1497 MutexLocker mu(THREAD, SystemDictionary_lock);
1498 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1499 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1500 if (!HAS_PENDING_EXCEPTION) {
1501 probe->set_instance_klass(k);
1502 }
1503 probe->set_definer(nullptr);
1504 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1505 SystemDictionary_lock->notify_all();
1506 }
1507
1508 return HAS_PENDING_EXCEPTION ? nullptr : k;
1509 }
1510
1511 // If a class loader supports parallel classloading handle parallel define requests.
1512 // find_or_define_instance_class may return a different InstanceKlass
1513 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1514 InstanceKlass* k, TRAPS) {
1515 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1516 // Clean up original InstanceKlass if duplicate or error
1517 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1518 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1519 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1520 k->class_loader_data()->add_to_deallocate_list(k);
1521 } else if (HAS_PENDING_EXCEPTION) {
1522 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1523 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1524 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1525 k->class_loader_data()->add_to_deallocate_list(k);
1526 }
1527 return defined_k;
1528 }
1529
1530
1531 // ----------------------------------------------------------------------------
1532 // GC support
1533
1534 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1535 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1536
1537 bool unloading_occurred;
1538 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1539 {
1540 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1541 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1542 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1543 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1544 if (unloading_occurred) {
1545 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1546 JFR_ONLY(Jfr::on_unloading_classes();)
1547 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1548 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1549 ClassLoaderDataGraph::clean_module_and_package_info();
1550 LoaderConstraintTable::purge_loader_constraints();
1551 ResolutionErrorTable::purge_resolution_errors();
1552 }
1553 }
1554
1555 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1556
1557 if (unloading_occurred) {
1558 SymbolTable::trigger_cleanup();
1559
1560 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1561 InstanceKlass::clean_initialization_error_table();
1562 }
1563
1564 return unloading_occurred;
1565 }
1566
1567 void SystemDictionary::methods_do(void f(Method*)) {
1568 // Walk methods in loaded classes
1569
1570 {
1571 MutexLocker ml(ClassLoaderDataGraph_lock);
1572 ClassLoaderDataGraph::methods_do(f);
1573 }
1574
1575 auto doit = [&] (InvokeMethodKey key, Method* method) {
1576 if (method != nullptr) {
1577 f(method);
1578 }
1579 };
1580
1581 {
1582 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1583 _invoke_method_intrinsic_table->iterate_all(doit);
1584 }
1585
1586 }
1587
1588 // ----------------------------------------------------------------------------
1589 // Initialization
1590
1591 void SystemDictionary::initialize(TRAPS) {
1592 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1593 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1594 ResolutionErrorTable::initialize();
1595 LoaderConstraintTable::initialize();
1596 PlaceholderTable::initialize();
1597 #if INCLUDE_CDS
1598 SystemDictionaryShared::initialize();
1599 if (CDSConfig::is_dumping_archive()) {
1600 AOTClassLocationConfig::dumptime_init(THREAD);
1601 }
1602 #endif
1603 // Resolve basic classes
1604 vmClasses::resolve_all(CHECK);
1605 // Resolve classes used by archived heap objects
1606 if (CDSConfig::is_using_archive()) {
1607 HeapShared::resolve_classes(THREAD);
1608 }
1609 }
1610
1611 // Constraints on class loaders. The details of the algorithm can be
1612 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1613 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1614 // that the dictionary needs to maintain a set of constraints that
1615 // must be satisfied by all classes in the dictionary.
1616 // if defining is true, then LinkageError if already in dictionary
1617 // if initiating loader, then ok if InstanceKlass matches existing entry
1618
1619 void SystemDictionary::check_constraints(InstanceKlass* k,
1620 ClassLoaderData* loader_data,
1621 bool defining,
1622 TRAPS) {
1623 ResourceMark rm(THREAD);
1624 stringStream ss;
1625 bool throwException = false;
1626
1627 {
1628 Symbol* name = k->name();
1629
1630 MutexLocker mu(THREAD, SystemDictionary_lock);
1631
1632 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1633 if (check != nullptr) {
1634 // If different InstanceKlass - duplicate class definition,
1635 // else - ok, class loaded by a different thread in parallel.
1636 // We should only have found it if it was done loading and ok to use.
1637
1638 if ((defining == true) || (k != check)) {
1639 throwException = true;
1640 ss.print("loader %s", loader_data->loader_name_and_id());
1641 ss.print(" attempted duplicate %s definition for %s. (%s)",
1642 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1643 } else {
1644 return;
1645 }
1646 }
1647
1648 if (throwException == false) {
1649 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1650 throwException = true;
1651 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1652 ss.print(" wants to load %s %s.",
1653 k->external_kind(), k->external_name());
1654 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1655 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1656 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1657 existing_klass->external_kind(),
1658 existing_klass->class_loader_data()->loader_name_and_id(),
1659 existing_klass->class_in_module_of_loader(false, true));
1660 } else {
1661 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1662 }
1663 }
1664 }
1665 }
1666
1667 // Throw error now if needed (cannot throw while holding
1668 // SystemDictionary_lock because of rank ordering)
1669 if (throwException == true) {
1670 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1671 }
1672 }
1673
1674 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1675 // have been called.
1676 void SystemDictionary::update_dictionary(JavaThread* current,
1677 InstanceKlass* k,
1678 ClassLoaderData* loader_data) {
1679 MonitorLocker mu1(SystemDictionary_lock);
1680
1681 // Make a new dictionary entry.
1682 Symbol* name = k->name();
1683 Dictionary* dictionary = loader_data->dictionary();
1684 InstanceKlass* sd_check = dictionary->find_class(current, name);
1685 if (sd_check == nullptr) {
1686 dictionary->add_klass(current, name, k);
1687 }
1688 mu1.notify_all();
1689 }
1690
1691 #if INCLUDE_CDS
1692 // Indicate that loader_data has initiated the loading of class k, which
1693 // has already been defined by a parent loader.
1694 // This API should be used only by AOTLinkedClassBulkLoader
1695 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1696 InstanceKlass* k,
1697 ClassLoaderData* loader_data) {
1698 assert(CDSConfig::is_using_aot_linked_classes(), "must be");
1699 assert_locked_or_safepoint(SystemDictionary_lock);
1700 Symbol* name = k->name();
1701 Dictionary* dictionary = loader_data->dictionary();
1702 assert(k->is_loaded(), "must be");
1703 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1704 assert(dictionary->find_class(current, name) == nullptr, "sanity");
1705 dictionary->add_klass(current, name, k);
1706 }
1707 #endif
1708
1709 // Try to find a class name using the loader constraints. The
1710 // loader constraints might know about a class that isn't fully loaded
1711 // yet and these will be ignored.
1712 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1713 Thread* current, Symbol* class_name, Handle class_loader) {
1714
1715 // First see if it has been loaded directly.
1716 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader);
1717 if (klass != nullptr)
1718 return klass;
1719
1720 // Now look to see if it has been loaded elsewhere, and is subject to
1721 // a loader constraint that would require this loader to return the
1722 // klass that is already loaded.
1723 if (Signature::is_array(class_name)) {
1724 // For array classes, their Klass*s are not kept in the
1725 // constraint table. The element Klass*s are.
1726 SignatureStream ss(class_name, false);
1727 int ndims = ss.skip_array_prefix(); // skip all '['s
1728 BasicType t = ss.type();
1729 if (t != T_OBJECT) {
1730 klass = Universe::typeArrayKlass(t);
1731 } else {
1732 MutexLocker mu(current, SystemDictionary_lock);
1733 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1734 }
1735 // If element class already loaded, allocate array klass
1736 if (klass != nullptr) {
1737 klass = klass->array_klass_or_null(ndims);
1738 }
1739 } else {
1740 MutexLocker mu(current, SystemDictionary_lock);
1741 // Non-array classes are easy: simply check the constraint table.
1742 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1743 }
1744
1745 return klass;
1746 }
1747
1748 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1749 Klass* klass_being_linked,
1750 Handle class_loader1,
1751 Handle class_loader2) {
1752 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1753 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1754
1755 Symbol* constraint_name = nullptr;
1756
1757 if (!Signature::is_array(class_name)) {
1758 constraint_name = class_name;
1759 } else {
1760 // For array classes, their Klass*s are not kept in the
1761 // constraint table. The element classes are.
1762 SignatureStream ss(class_name, false);
1763 ss.skip_array_prefix(); // skip all '['s
1764 if (!ss.has_envelope()) {
1765 return true; // primitive types always pass
1766 }
1767 constraint_name = ss.as_symbol();
1768 // Increment refcount to keep constraint_name alive after
1769 // SignatureStream is destructed. It will be decremented below
1770 // before returning.
1771 constraint_name->increment_refcount();
1772 }
1773
1774 Dictionary* dictionary1 = loader_data1->dictionary();
1775 Dictionary* dictionary2 = loader_data2->dictionary();
1776
1777 JavaThread* current = JavaThread::current();
1778 {
1779 MutexLocker mu_s(SystemDictionary_lock);
1780 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1781 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1782 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1783 klass2, loader_data2);
1784 #if INCLUDE_CDS
1785 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1786 !klass_being_linked->is_shared()) {
1787 SystemDictionaryShared::record_linking_constraint(constraint_name,
1788 InstanceKlass::cast(klass_being_linked),
1789 class_loader1, class_loader2);
1790 }
1791 #endif // INCLUDE_CDS
1792 if (Signature::is_array(class_name)) {
1793 constraint_name->decrement_refcount();
1794 }
1795 return result;
1796 }
1797 }
1798
1799 // Add entry to resolution error table to record the error when the first
1800 // attempt to resolve a reference to a class has failed.
1801 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1802 Symbol* error, const char* message,
1803 Symbol* cause, const char* cause_msg) {
1804 {
1805 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1806 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1807 if (entry == nullptr) {
1808 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1809 }
1810 }
1811 }
1812
1813 // Delete a resolution error for RedefineClasses for a constant pool is going away
1814 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1815 ResolutionErrorTable::delete_entry(pool);
1816 }
1817
1818 // Lookup resolution error table. Returns error if found, otherwise null.
1819 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1820 const char** message,
1821 Symbol** cause, const char** cause_msg) {
1822
1823 {
1824 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1825 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1826 if (entry != nullptr) {
1827 *message = entry->message();
1828 *cause = entry->cause();
1829 *cause_msg = entry->cause_msg();
1830 return entry->error();
1831 } else {
1832 return nullptr;
1833 }
1834 }
1835 }
1836
1837 // Add an entry to resolution error table to record an error in resolving or
1838 // validating a nest host. This is used to construct informative error
1839 // messages when IllegalAccessError's occur. If an entry already exists it will
1840 // be updated with the nest host error message.
1841
1842 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1843 int which,
1844 const char* message) {
1845 {
1846 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1847 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1848 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1849 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1850 // still want to add the error message for the higher-level access checks to report. We should
1851 // only reach here under the same error condition, so we can ignore the potential race with setting
1852 // the message. If we see it is already set then we can ignore it.
1853 entry->set_nest_host_error(message);
1854 } else {
1855 ResolutionErrorTable::add_entry(pool, which, message);
1856 }
1857 }
1858 }
1859
1860 // Lookup any nest host error
1861 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1862 {
1863 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1864 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1865 if (entry != nullptr) {
1866 return entry->nest_host_error();
1867 } else {
1868 return nullptr;
1869 }
1870 }
1871 }
1872
1873 // Signature constraints ensure that callers and callees agree about
1874 // the meaning of type names in their signatures. This routine is the
1875 // intake for constraints. It collects them from several places:
1876 //
1877 // * LinkResolver::resolve_method (if check_access is true) requires
1878 // that the resolving class (the caller) and the defining class of
1879 // the resolved method (the callee) agree on each type in the
1880 // method's signature.
1881 //
1882 // * LinkResolver::resolve_interface_method performs exactly the same
1883 // checks.
1884 //
1885 // * LinkResolver::resolve_field requires that the constant pool
1886 // attempting to link to a field agree with the field's defining
1887 // class about the type of the field signature.
1888 //
1889 // * klassVtable::initialize_vtable requires that, when a class
1890 // overrides a vtable entry allocated by a superclass, that the
1891 // overriding method (i.e., the callee) agree with the superclass
1892 // on each type in the method's signature.
1893 //
1894 // * klassItable::initialize_itable requires that, when a class fills
1895 // in its itables, for each non-abstract method installed in an
1896 // itable, the method (i.e., the callee) agree with the interface
1897 // on each type in the method's signature.
1898 //
1899 // All those methods have a boolean (check_access, checkconstraints)
1900 // which turns off the checks. This is used from specialized contexts
1901 // such as bootstrapping, dumping, and debugging.
1902 //
1903 // No direct constraint is placed between the class and its
1904 // supertypes. Constraints are only placed along linked relations
1905 // between callers and callees. When a method overrides or implements
1906 // an abstract method in a supertype (superclass or interface), the
1907 // constraints are placed as if the supertype were the caller to the
1908 // overriding method. (This works well, since callers to the
1909 // supertype have already established agreement between themselves and
1910 // the supertype.) As a result of all this, a class can disagree with
1911 // its supertype about the meaning of a type name, as long as that
1912 // class neither calls a relevant method of the supertype, nor is
1913 // called (perhaps via an override) from the supertype.
1914 //
1915 //
1916 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1917 //
1918 // Make sure all class components (including arrays) in the given
1919 // signature will be resolved to the same class in both loaders.
1920 // Returns the name of the type that failed a loader constraint check, or
1921 // null if no constraint failed. No exception except OOME is thrown.
1922 // Arrays are not added to the loader constraint table, their elements are.
1923 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1924 Klass* klass_being_linked,
1925 Handle loader1, Handle loader2,
1926 bool is_method) {
1927 // Nothing to do if loaders are the same.
1928 if (loader1() == loader2()) {
1929 return nullptr;
1930 }
1931
1932 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
1933 if (ss.is_reference()) {
1934 Symbol* sig = ss.as_symbol();
1935 // Note: In the future, if template-like types can take
1936 // arguments, we will want to recognize them and dig out class
1937 // names hiding inside the argument lists.
1938 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
1939 return sig;
1940 }
1941 }
1942 }
1943 return nullptr;
1944 }
1945
1946 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
1947 Symbol* signature,
1948 TRAPS) {
1949
1950 const int iid_as_int = vmIntrinsics::as_int(iid);
1951 assert(MethodHandles::is_signature_polymorphic(iid) &&
1952 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
1953 iid != vmIntrinsics::_invokeGeneric,
1954 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
1955
1956 InvokeMethodKey key(signature, iid_as_int);
1957 Method** met = nullptr;
1958
1959 // We only want one entry in the table for this (signature/id, method) pair but the code
1960 // to create the intrinsic method needs to be outside the lock.
1961 // The first thread claims the entry by adding the key and the other threads wait, until the
1962 // Method has been added as the value.
1963 {
1964 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1965 while (true) {
1966 bool created;
1967 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
1968 assert(met != nullptr, "either created or found");
1969 if (*met != nullptr) {
1970 return *met;
1971 } else if (created) {
1972 // The current thread won the race and will try to create the full entry.
1973 break;
1974 } else {
1975 // Another thread beat us to it, so wait for them to complete
1976 // and return *met; or if they hit an error we get another try.
1977 ml.wait();
1978 // Note it is not safe to read *met here as that entry could have
1979 // been deleted, so we must loop and try put_if_absent again.
1980 }
1981 }
1982 }
1983
1984 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
1985 bool throw_error = HAS_PENDING_EXCEPTION;
1986 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
1987 // Generate a compiled form of the MH intrinsic
1988 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
1989 AdapterHandlerLibrary::create_native_wrapper(m);
1990 // Check if have the compiled code.
1991 throw_error = (!m->has_compiled_code());
1992 }
1993
1994 {
1995 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1996 if (throw_error) {
1997 // Remove the entry and let another thread try, or get the same exception.
1998 bool removed = _invoke_method_intrinsic_table->remove(key);
1999 assert(removed, "must be the owner");
2000 ml.notify_all();
2001 } else {
2002 signature->make_permanent(); // The signature is never unloaded.
2003 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2004 m->code()->entry_point() == m->from_compiled_entry()),
2005 "MH intrinsic invariant");
2006 *met = m(); // insert the element
2007 ml.notify_all();
2008 return m();
2009 }
2010 }
2011
2012 // Throw OOM or the pending exception in the JavaThread
2013 if (throw_error && !HAS_PENDING_EXCEPTION) {
2014 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2015 "Out of space in CodeCache for method handle intrinsic");
2016 }
2017 return nullptr;
2018 }
2019
2020 #if INCLUDE_CDS
2021 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) {
2022 assert(SafepointSynchronize::is_at_safepoint(), "must be");
2023 auto do_method = [&] (InvokeMethodKey& key, Method*& m) {
2024 methods->append(m);
2025 };
2026 _invoke_method_intrinsic_table->iterate_all(do_method);
2027 }
2028
2029 void SystemDictionary::restore_archived_method_handle_intrinsics() {
2030 if (UseSharedSpaces) {
2031 EXCEPTION_MARK;
2032 restore_archived_method_handle_intrinsics_impl(THREAD);
2033 if (HAS_PENDING_EXCEPTION) {
2034 // This is probably caused by OOM -- other parts of the CDS archive have direct pointers to
2035 // the archived method handle intrinsics, so we can't really recover from this failure.
2036 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics. Try to increase heap size."));
2037 }
2038 }
2039 }
2040
2041 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) {
2042 Array<Method*>* list = MetaspaceShared::archived_method_handle_intrinsics();
2043 for (int i = 0; i < list->length(); i++) {
2044 methodHandle m(THREAD, list->at(i));
2045 Method::restore_archived_method_handle_intrinsic(m, CHECK);
2046 m->constants()->restore_unshareable_info(CHECK);
2047 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) {
2048 AdapterHandlerLibrary::create_native_wrapper(m);
2049 if (!m->has_compiled_code()) {
2050 ResourceMark rm(THREAD);
2051 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name()));
2052 }
2053 }
2054
2055 // There's no need to grab the InvokeMethodIntrinsicTable_lock, as we are still very early in
2056 // VM start-up -- in init_globals2() -- so we are still running a single Java thread. It's not
2057 // possible to have a contention.
2058 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id());
2059 InvokeMethodKey key(m->signature(), iid_as_int);
2060 bool created = _invoke_method_intrinsic_table->put(key, m());
2061 assert(created, "unexpected contention");
2062 }
2063 }
2064 #endif // INCLUDE_CDS
2065
2066 // Helper for unpacking the return value from linkMethod and linkCallSite.
2067 static Method* unpack_method_and_appendix(Handle mname,
2068 Klass* accessing_klass,
2069 objArrayHandle appendix_box,
2070 Handle* appendix_result,
2071 TRAPS) {
2072 if (mname.not_null()) {
2073 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2074 if (m != nullptr) {
2075 oop appendix = appendix_box->obj_at(0);
2076 LogTarget(Info, methodhandles) lt;
2077 if (lt.develop_is_enabled()) {
2078 ResourceMark rm(THREAD);
2079 LogStream ls(lt);
2080 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2081 m->print_on(&ls);
2082 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2083 ls.cr();
2084 }
2085
2086 (*appendix_result) = Handle(THREAD, appendix);
2087 // the target is stored in the cpCache and if a reference to this
2088 // MemberName is dropped we need a way to make sure the
2089 // class_loader containing this method is kept alive.
2090 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2091 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2092 this_key->record_dependency(m->method_holder());
2093 return mh();
2094 }
2095 }
2096 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2097 }
2098
2099 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2100 Symbol* name,
2101 Symbol* signature,
2102 Klass* accessing_klass,
2103 Handle* appendix_result,
2104 TRAPS) {
2105 guarantee(THREAD->can_call_java(), "");
2106 Handle method_type =
2107 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2108
2109 int ref_kind = JVM_REF_invokeVirtual;
2110 oop name_oop = StringTable::intern(name, CHECK_NULL);
2111 Handle name_str (THREAD, name_oop);
2112 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2113 assert(appendix_box->obj_at(0) == nullptr, "");
2114
2115 // This should not happen. JDK code should take care of that.
2116 if (accessing_klass == nullptr || method_type.is_null()) {
2117 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2118 }
2119
2120 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2121 JavaCallArguments args;
2122 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2123 args.push_int(ref_kind);
2124 args.push_oop(Handle(THREAD, klass->java_mirror()));
2125 args.push_oop(name_str);
2126 args.push_oop(method_type);
2127 args.push_oop(appendix_box);
2128 JavaValue result(T_OBJECT);
2129 JavaCalls::call_static(&result,
2130 vmClasses::MethodHandleNatives_klass(),
2131 vmSymbols::linkMethod_name(),
2132 vmSymbols::linkMethod_signature(),
2133 &args, CHECK_NULL);
2134 Handle mname(THREAD, result.get_oop());
2135 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2136 }
2137
2138 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2139 // We must ensure that all class loaders everywhere will reach this class, for any client.
2140 // This is a safe bet for public classes in java.lang, such as Object and String.
2141 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2142 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2143 static bool is_always_visible_class(oop mirror) {
2144 Klass* klass = java_lang_Class::as_Klass(mirror);
2145 if (klass->is_objArray_klass()) {
2146 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2147 }
2148 if (klass->is_typeArray_klass()) {
2149 return true; // primitive array
2150 }
2151 assert(klass->is_instance_klass(), "%s", klass->external_name());
2152 return klass->is_public() &&
2153 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2154 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2155 }
2156
2157 // Find or construct the Java mirror (java.lang.Class instance) for
2158 // the given field type signature, as interpreted relative to the
2159 // given class loader. Handles primitives, void, references, arrays,
2160 // and all other reflectable types, except method types.
2161 // N.B. Code in reflection should use this entry point.
2162 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2163 Klass* accessing_klass,
2164 SignatureStream::FailureMode failure_mode,
2165 TRAPS) {
2166
2167 Handle class_loader;
2168
2169 // What we have here must be a valid field descriptor,
2170 // and all valid field descriptors are supported.
2171 // Produce the same java.lang.Class that reflection reports.
2172 if (accessing_klass != nullptr) {
2173 class_loader = Handle(THREAD, accessing_klass->class_loader());
2174 }
2175 ResolvingSignatureStream ss(signature, class_loader, false);
2176 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2177 if (mirror_oop == nullptr) {
2178 return Handle(); // report failure this way
2179 }
2180 Handle mirror(THREAD, mirror_oop);
2181
2182 if (accessing_klass != nullptr) {
2183 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2184 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2185 if (sel_klass != nullptr) {
2186 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2187 }
2188 }
2189 return mirror;
2190 }
2191
2192
2193 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2194 // signature, as interpreted relative to the given class loader.
2195 // Because of class loader constraints, all method handle usage must be
2196 // consistent with this loader.
2197 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2198 Klass* accessing_klass,
2199 TRAPS) {
2200 Handle empty;
2201 OopHandle* o;
2202 {
2203 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2204 o = _invoke_method_type_table->get(signature);
2205 }
2206
2207 if (o != nullptr) {
2208 oop mt = o->resolve();
2209 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2210 return Handle(THREAD, mt);
2211 } else if (!THREAD->can_call_java()) {
2212 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2213 return Handle(); // do not attempt from within compiler, unless it was cached
2214 }
2215
2216 Handle class_loader;
2217 if (accessing_klass != nullptr) {
2218 class_loader = Handle(THREAD, accessing_klass->class_loader());
2219 }
2220 bool can_be_cached = true;
2221 int npts = ArgumentCount(signature).size();
2222 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2223 int arg = 0;
2224 Handle rt; // the return type from the signature
2225 ResourceMark rm(THREAD);
2226 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2227 oop mirror = nullptr;
2228 if (can_be_cached) {
2229 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2230 mirror = ss.as_java_mirror(Handle(), SignatureStream::ReturnNull, CHECK_(empty));
2231 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2232 // Fall back to accessing_klass context.
2233 can_be_cached = false;
2234 }
2235 }
2236 if (!can_be_cached) {
2237 // Resolve, throwing a real error if it doesn't work.
2238 mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2239 }
2240 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2241 if (ss.at_return_type())
2242 rt = Handle(THREAD, mirror);
2243 else
2244 pts->obj_at_put(arg++, mirror);
2245
2246 // Check accessibility.
2247 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2248 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2249 mirror = nullptr; // safety
2250 // Emulate ConstantPool::verify_constant_pool_resolve.
2251 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2252 }
2253 }
2254 assert(arg == npts, "");
2255
2256 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2257 JavaCallArguments args(Handle(THREAD, rt()));
2258 args.push_oop(pts);
2259 JavaValue result(T_OBJECT);
2260 JavaCalls::call_static(&result,
2261 vmClasses::MethodHandleNatives_klass(),
2262 vmSymbols::findMethodHandleType_name(),
2263 vmSymbols::findMethodHandleType_signature(),
2264 &args, CHECK_(empty));
2265 Handle method_type(THREAD, result.get_oop());
2266
2267 if (can_be_cached) {
2268 // We can cache this MethodType inside the JVM.
2269 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2270 bool created = false;
2271 assert(method_type != nullptr, "unexpected null");
2272 OopHandle* h = _invoke_method_type_table->get(signature);
2273 if (h == nullptr) {
2274 signature->make_permanent(); // The signature is never unloaded.
2275 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2276 bool created = _invoke_method_type_table->put(signature, elem);
2277 assert(created, "better be created");
2278 }
2279 }
2280 // report back to the caller with the MethodType
2281 return method_type;
2282 }
2283
2284 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2285 Klass* accessing_klass,
2286 TRAPS) {
2287 Handle empty;
2288 ResourceMark rm(THREAD);
2289 SignatureStream ss(signature, /*is_method=*/ false);
2290 if (!ss.is_done()) {
2291 Handle class_loader;
2292 if (accessing_klass != nullptr) {
2293 class_loader = Handle(THREAD, accessing_klass->class_loader());
2294 }
2295 oop mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2296 ss.next();
2297 if (ss.is_done()) {
2298 return Handle(THREAD, mirror);
2299 }
2300 }
2301 return empty;
2302 }
2303
2304 // Ask Java code to find or construct a method handle constant.
2305 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2306 int ref_kind, //e.g., JVM_REF_invokeVirtual
2307 Klass* callee,
2308 Symbol* name,
2309 Symbol* signature,
2310 TRAPS) {
2311 Handle empty;
2312 if (caller == nullptr) {
2313 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2314 }
2315 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2316 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2317
2318 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2319 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2320 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2321 java_lang_invoke_MemberName::set_name (mname(), name_str());
2322 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2323 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2324
2325 if (ref_kind == JVM_REF_invokeVirtual &&
2326 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2327 // Skip resolution for public signature polymorphic methods such as
2328 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2329 // They require appendix argument which MemberName resolution doesn't handle.
2330 // There's special logic on JDK side to handle them
2331 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2332 } else {
2333 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2334 }
2335
2336 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2337 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2338
2339 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2340 JavaCallArguments args;
2341 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2342 args.push_int(ref_kind);
2343 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2344 args.push_oop(name_str);
2345 args.push_oop(type);
2346 JavaValue result(T_OBJECT);
2347 JavaCalls::call_static(&result,
2348 vmClasses::MethodHandleNatives_klass(),
2349 vmSymbols::linkMethodHandleConstant_name(),
2350 vmSymbols::linkMethodHandleConstant_signature(),
2351 &args, CHECK_(empty));
2352 return Handle(THREAD, result.get_oop());
2353 }
2354
2355 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2356 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2357 // with linkage results being stored back into the bootstrap specifier.
2358 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2359 // Resolve the bootstrap specifier, its name, type, and static arguments
2360 bootstrap_specifier.resolve_bsm(CHECK);
2361
2362 // This should not happen. JDK code should take care of that.
2363 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2364 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2365 }
2366
2367 bool is_indy = bootstrap_specifier.is_method_call();
2368 objArrayHandle appendix_box;
2369 if (is_indy) {
2370 // Some method calls may require an appendix argument. Arrange to receive it.
2371 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2372 assert(appendix_box->obj_at(0) == nullptr, "");
2373 }
2374
2375 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2376 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2377 JavaCallArguments args;
2378 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2379 args.push_oop(bootstrap_specifier.bsm());
2380 args.push_oop(bootstrap_specifier.name_arg());
2381 args.push_oop(bootstrap_specifier.type_arg());
2382 args.push_oop(bootstrap_specifier.arg_values());
2383 if (is_indy) {
2384 args.push_oop(appendix_box);
2385 }
2386 JavaValue result(T_OBJECT);
2387 JavaCalls::call_static(&result,
2388 vmClasses::MethodHandleNatives_klass(),
2389 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2390 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2391 &args, CHECK);
2392
2393 Handle value(THREAD, result.get_oop());
2394 if (is_indy) {
2395 Handle appendix;
2396 Method* method = unpack_method_and_appendix(value,
2397 bootstrap_specifier.caller(),
2398 appendix_box,
2399 &appendix, CHECK);
2400 methodHandle mh(THREAD, method);
2401 bootstrap_specifier.set_resolved_method(mh, appendix);
2402 } else {
2403 bootstrap_specifier.set_resolved_value(value);
2404 }
2405
2406 // sanity check
2407 assert(bootstrap_specifier.is_resolved() ||
2408 (bootstrap_specifier.is_method_call() &&
2409 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2410 }
2411
2412
2413 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2414 assert(m != nullptr, "Unexpected nullptr Method*");
2415 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2416 }
2417
2418 // ----------------------------------------------------------------------------
2419
2420 void SystemDictionary::print_on(outputStream *st) {
2421 CDS_ONLY(SystemDictionaryShared::print_on(st));
2422 GCMutexLocker mu(SystemDictionary_lock);
2423
2424 ClassLoaderDataGraph::print_dictionary(st);
2425
2426 // Placeholders
2427 PlaceholderTable::print_on(st);
2428 st->cr();
2429
2430 // loader constraints - print under SD_lock
2431 LoaderConstraintTable::print_on(st);
2432 st->cr();
2433 }
2434
2435 void SystemDictionary::print() { print_on(tty); }
2436
2437 void SystemDictionary::verify() {
2438
2439 GCMutexLocker mu(SystemDictionary_lock);
2440
2441 // Verify dictionary
2442 ClassLoaderDataGraph::verify_dictionary();
2443
2444 // Verify constraint table
2445 LoaderConstraintTable::verify();
2446 }
2447
2448 void SystemDictionary::dump(outputStream *st, bool verbose) {
2449 assert_locked_or_safepoint(SystemDictionary_lock);
2450 if (verbose) {
2451 print_on(st);
2452 } else {
2453 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2454 ClassLoaderDataGraph::print_table_statistics(st);
2455 LoaderConstraintTable::print_table_statistics(st);
2456 }
2457 }
2458
2459 // Utility for dumping dictionaries.
2460 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2461 DCmdWithParser(output, heap),
2462 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2463 "BOOLEAN", false, "false") {
2464 _dcmdparser.add_dcmd_option(&_verbose);
2465 }
2466
2467 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2468 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2469 _verbose.value());
2470 VMThread::execute(&dumper);
2471 }