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