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