1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "cds/aotClassLocation.hpp"
26 #include "cds/cdsConfig.hpp"
27 #include "cds/heapShared.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/classLoadInfo.hpp"
34 #include "classfile/dictionary.hpp"
35 #include "classfile/javaClasses.inline.hpp"
36 #include "classfile/klassFactory.hpp"
37 #include "classfile/loaderConstraints.hpp"
38 #include "classfile/packageEntry.hpp"
39 #include "classfile/placeholders.hpp"
40 #include "classfile/resolutionErrors.hpp"
41 #include "classfile/stringTable.hpp"
42 #include "classfile/symbolTable.hpp"
43 #include "classfile/systemDictionary.hpp"
44 #include "classfile/vmClasses.hpp"
45 #include "classfile/vmSymbols.hpp"
46 #include "gc/shared/gcTraceTime.inline.hpp"
47 #include "interpreter/bootstrapInfo.hpp"
48 #include "jfr/jfrEvents.hpp"
49 #include "jvm.h"
50 #include "logging/log.hpp"
51 #include "logging/logStream.hpp"
52 #include "memory/metaspaceClosure.hpp"
53 #include "memory/oopFactory.hpp"
54 #include "memory/resourceArea.hpp"
55 #include "memory/universe.hpp"
56 #include "oops/access.inline.hpp"
57 #include "oops/instanceKlass.hpp"
58 #include "oops/klass.inline.hpp"
59 #include "oops/method.inline.hpp"
60 #include "oops/objArrayKlass.hpp"
61 #include "oops/objArrayOop.inline.hpp"
62 #include "oops/oop.inline.hpp"
63 #include "oops/oopHandle.inline.hpp"
64 #include "oops/symbol.hpp"
65 #include "oops/typeArrayKlass.hpp"
66 #include "prims/jvmtiExport.hpp"
67 #include "prims/methodHandles.hpp"
68 #include "runtime/arguments.hpp"
69 #include "runtime/atomicAccess.hpp"
70 #include "runtime/handles.inline.hpp"
71 #include "runtime/java.hpp"
72 #include "runtime/javaCalls.hpp"
73 #include "runtime/mutexLocker.hpp"
74 #include "runtime/sharedRuntime.hpp"
75 #include "runtime/signature.hpp"
76 #include "runtime/synchronizer.hpp"
77 #include "services/classLoadingService.hpp"
78 #include "services/diagnosticCommand.hpp"
79 #include "services/finalizerService.hpp"
80 #include "services/threadService.hpp"
81 #include "utilities/growableArray.hpp"
82 #include "utilities/macros.hpp"
83 #include "utilities/utf8.hpp"
84 #if INCLUDE_CDS
85 #include "classfile/systemDictionaryShared.hpp"
86 #endif
87 #if INCLUDE_JFR
88 #include "jfr/jfr.hpp"
89 #endif
90
91 class InvokeMethodKey : public StackObj {
92 private:
93 Symbol* _symbol;
94 intptr_t _iid;
95
96 public:
97 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
98 _symbol(symbol),
99 _iid(iid) {}
100
101 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
102 return k1._symbol == k2._symbol && k1._iid == k2._iid;
103 }
104
105 static unsigned int compute_hash(const InvokeMethodKey &k) {
106 Symbol* sym = k._symbol;
107 intptr_t iid = k._iid;
108 unsigned int hash = (unsigned int) sym -> identity_hash();
109 return (unsigned int) (hash ^ iid);
110 }
111
112 };
113
114 using InvokeMethodIntrinsicTable = HashTable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
115 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
116 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
117 using InvokeMethodTypeTable = HashTable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
118 static InvokeMethodTypeTable* _invoke_method_type_table;
119
120 OopHandle SystemDictionary::_java_system_loader;
121 OopHandle SystemDictionary::_java_platform_loader;
122
123 // ----------------------------------------------------------------------------
124 // Java-level SystemLoader and PlatformLoader
125 oop SystemDictionary::java_system_loader() {
126 return _java_system_loader.resolve();
127 }
128
129 oop SystemDictionary::java_platform_loader() {
130 return _java_platform_loader.resolve();
131 }
132
133 void SystemDictionary::compute_java_loaders(TRAPS) {
134 if (_java_platform_loader.is_empty()) {
135 oop platform_loader = get_platform_class_loader_impl(CHECK);
136 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
137 } else {
138 // It must have been restored from the archived module graph
139 assert(CDSConfig::is_using_archive(), "must be");
140 assert(CDSConfig::is_using_full_module_graph(), "must be");
141 DEBUG_ONLY(
142 oop platform_loader = get_platform_class_loader_impl(CHECK);
143 assert(_java_platform_loader.resolve() == platform_loader, "must be");
144 )
145 }
146
147 if (_java_system_loader.is_empty()) {
148 oop system_loader = get_system_class_loader_impl(CHECK);
149 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
150 } else {
151 // It must have been restored from the archived module graph
152 assert(CDSConfig::is_using_archive(), "must be");
153 assert(CDSConfig::is_using_full_module_graph(), "must be");
154 DEBUG_ONLY(
155 oop system_loader = get_system_class_loader_impl(CHECK);
156 assert(_java_system_loader.resolve() == system_loader, "must be");
157 )
158 }
159 }
160
161 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
162 JavaValue result(T_OBJECT);
163 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
164 JavaCalls::call_static(&result,
165 class_loader_klass,
166 vmSymbols::getSystemClassLoader_name(),
167 vmSymbols::void_classloader_signature(),
168 CHECK_NULL);
169 return result.get_oop();
170 }
171
172 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
173 JavaValue result(T_OBJECT);
174 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
175 JavaCalls::call_static(&result,
176 class_loader_klass,
177 vmSymbols::getPlatformClassLoader_name(),
178 vmSymbols::void_classloader_signature(),
179 CHECK_NULL);
180 return result.get_oop();
181 }
182
183 // Helper function
184 inline ClassLoaderData* class_loader_data(Handle class_loader) {
185 return ClassLoaderData::class_loader_data(class_loader());
186 }
187
188 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
189 if (create_mirror_cld) {
190 // Add a new class loader data to the graph.
191 return ClassLoaderDataGraph::add(class_loader, true);
192 } else {
193 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
194 ClassLoaderDataGraph::find_or_create(class_loader);
195 }
196 }
197
198 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
199 if (_java_system_loader.is_empty()) {
200 _java_system_loader = cld->class_loader_handle();
201 } else {
202 assert(_java_system_loader.resolve() == cld->class_loader(), "sanity");
203 }
204 }
205
206 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
207 if (_java_platform_loader.is_empty()) {
208 _java_platform_loader = cld->class_loader_handle();
209 } else {
210 assert(_java_platform_loader.resolve() == cld->class_loader(), "sanity");
211 }
212 }
213
214 // ----------------------------------------------------------------------------
215 // Parallel class loading check
216
217 static bool is_parallelCapable(Handle class_loader) {
218 if (class_loader.is_null()) return true;
219 return java_lang_ClassLoader::parallelCapable(class_loader());
220 }
221 // ----------------------------------------------------------------------------
222 // ParallelDefineClass flag does not apply to bootclass loader
223 static bool is_parallelDefine(Handle class_loader) {
224 if (class_loader.is_null()) return false;
225 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
226 return true;
227 }
228 return false;
229 }
230
231 // Returns true if the passed class loader is the builtin application class loader
232 // or a custom system class loader. A customer system class loader can be
233 // specified via -Djava.system.class.loader.
234 bool SystemDictionary::is_system_class_loader(oop class_loader) {
235 if (class_loader == nullptr) {
236 return false;
237 }
238 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
239 class_loader == _java_system_loader.peek());
240 }
241
242 // Returns true if the passed class loader is the platform class loader.
243 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
244 if (class_loader == nullptr) {
245 return false;
246 }
247 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
248 }
249
250 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
251 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
252 if (is_parallelCapable(class_loader)) {
253 return Handle();
254 } else {
255 return class_loader;
256 }
257 }
258
259 // ----------------------------------------------------------------------------
260 // Resolving of classes
261
262 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
263 if (name == nullptr) {
264 THROW_MSG_NULL(exception, "No class name given");
265 }
266 size_t name_len = strlen(name);
267 if (name_len > static_cast<size_t>(Symbol::max_length())) {
268 // It's impossible to create this class; the name cannot fit
269 // into the constant pool. If necessary report an abridged name
270 // in the exception message.
271 if (name_len > static_cast<size_t>(MaxStringPrintSize)) {
272 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
273 "Class name exceeds maximum length of %d: %.*s ... (%zu characters omitted) ... %.*s",
274 Symbol::max_length(),
275 MaxStringPrintSize / 2,
276 name,
277 name_len - 2 * (MaxStringPrintSize / 2), // allows for odd value
278 MaxStringPrintSize / 2,
279 name + name_len - MaxStringPrintSize / 2);
280 }
281 else {
282 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
283 "Class name exceeds maximum length of %d: %s",
284 Symbol::max_length(),
285 name);
286 }
287 return nullptr;
288 }
289 // Callers should ensure that the name is never an illegal UTF8 string.
290 assert(UTF8::is_legal_utf8((const unsigned char*)name, name_len, false),
291 "Class name is not a valid utf8 string.");
292
293 // Make a new symbol for the class name.
294 return SymbolTable::new_symbol(name);
295 }
296
297 #ifdef ASSERT
298 // Used to verify that class loading succeeded in adding k to the dictionary.
299 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
300 MutexLocker mu(SystemDictionary_lock);
301 ClassLoaderData* loader_data = k->class_loader_data();
302 Dictionary* dictionary = loader_data->dictionary();
303 assert(class_name == k->name(), "Must be the same");
304 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
305 assert(kk == k, "should be present in dictionary");
306 }
307 #endif
308
309 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
310 if (HAS_PENDING_EXCEPTION) {
311 // If we have a pending exception we forward it to the caller, unless throw_error is true,
312 // in which case we have to check whether the pending exception is a ClassNotFoundException,
313 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
314 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
315 ResourceMark rm(THREAD);
316 Handle e(THREAD, PENDING_EXCEPTION);
317 CLEAR_PENDING_EXCEPTION;
318 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
319 } else {
320 return; // the caller will throw the incoming exception
321 }
322 }
323 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
324 // error or exception depending on the value of throw_error.
325 ResourceMark rm(THREAD);
326 if (throw_error) {
327 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
328 } else {
329 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
330 }
331 }
332
333 // Forwards to resolve_or_null
334
335 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader,
336 bool throw_error, TRAPS) {
337 Klass* klass = resolve_or_null(class_name, class_loader, THREAD);
338 // Check for pending exception or null klass, and throw exception
339 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
340 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
341 }
342 return klass;
343 }
344
345 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
346
347 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, TRAPS) {
348 if (Signature::is_array(class_name)) {
349 return resolve_array_class_or_null(class_name, class_loader, THREAD);
350 } else {
351 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
352 if (Signature::has_envelope(class_name)) {
353 ResourceMark rm(THREAD);
354 // Ignore wrapping L and ;.
355 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
356 class_name->utf8_length() - 2);
357 return resolve_instance_class_or_null(name, class_loader, THREAD);
358 } else {
359 return resolve_instance_class_or_null(class_name, class_loader, THREAD);
360 }
361 }
362 }
363
364 // Forwards to resolve_instance_class_or_null
365
366 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
367 Handle class_loader,
368 TRAPS) {
369 assert(Signature::is_array(class_name), "must be array");
370 ResourceMark rm(THREAD);
371 SignatureStream ss(class_name, false);
372 int ndims = ss.skip_array_prefix(); // skip all '['s
373 Klass* k = nullptr;
374 BasicType t = ss.type();
375 if (ss.has_envelope()) {
376 Symbol* obj_class = ss.as_symbol();
377 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
378 class_loader,
379 CHECK_NULL);
380 if (k != nullptr) {
381 k = k->array_klass(ndims, CHECK_NULL);
382 }
383 } else {
384 k = Universe::typeArrayKlass(t);
385 k = k->array_klass(ndims, CHECK_NULL);
386 }
387 return k;
388 }
389
390 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
391 LogTarget(Debug, class, load, placeholders) lt;
392 if (lt.is_enabled()) {
393 ResourceMark rm;
394 LogStream ls(lt);
395 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
396 probe->print_on(&ls);
397 ls.cr();
398 }
399 }
400
401 // Must be called for any superclass or superinterface resolution
402 // during class definition to allow class circularity checking
403 // superinterface callers:
404 // parse_interfaces - from defineClass
405 // superclass callers:
406 // ClassFileParser - from defineClass
407 // load_shared_class - while loading a class from shared archive
408 // resolve_instance_class_or_null:
409 // via: handle_parallel_super_load
410 // when resolving a class that has an existing placeholder with
411 // a saved superclass [i.e. a defineClass is currently in progress]
412 // If another thread is trying to resolve the class, it must do
413 // superclass checks on its own thread to catch class circularity and
414 // to avoid deadlock.
415 //
416 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
417 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
418 // placeholder for the same thread, class, classloader is found.
419 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
420 //
421 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
422 Symbol* next_name,
423 Handle class_loader,
424 bool is_superclass,
425 TRAPS) {
426
427 assert(next_name != nullptr, "null superclass for resolving");
428 assert(!Signature::is_array(next_name), "invalid superclass name");
429
430 ClassLoaderData* loader_data = class_loader_data(class_loader);
431
432 if (is_superclass) {
433 InstanceKlass* klassk = loader_data->dictionary()->find_class(THREAD, class_name);
434 if (klassk != nullptr) {
435 // We can come here for two reasons:
436 // (a) RedefineClasses -- the class is already loaded
437 // (b) Rarely, the class might have been loaded by a parallel thread
438 // We can do a quick check against the already assigned superclass's name and loader.
439 InstanceKlass* superk = klassk->super();
440 if (superk != nullptr &&
441 superk->name() == next_name &&
442 superk->class_loader() == class_loader()) {
443 return superk;
444 }
445 }
446 }
447
448 // can't throw error holding a lock
449 bool throw_circularity_error = false;
450 {
451 MutexLocker mu(THREAD, SystemDictionary_lock);
452
453 // Must check ClassCircularity before resolving next_name (superclass or interface).
454 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
455 if (probe != nullptr && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
456 log_circularity_error(class_name, probe);
457 throw_circularity_error = true;
458 }
459
460 // Make sure there's a placeholder for the class_name before resolving.
461 // This is used as a claim that this thread is currently loading superclass/classloader
462 // and for ClassCircularity checks.
463 if (!throw_circularity_error) {
464 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
465 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
466 loader_data,
467 PlaceholderTable::DETECT_CIRCULARITY,
468 next_name, THREAD);
469 }
470 }
471
472 if (throw_circularity_error) {
473 ResourceMark rm(THREAD);
474 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
475 }
476
477 // Resolve the superclass or superinterface, check results on return
478 InstanceKlass* superk =
479 SystemDictionary::resolve_instance_class_or_null(next_name,
480 class_loader,
481 THREAD);
482
483 // Clean up placeholder entry.
484 {
485 MutexLocker mu(THREAD, SystemDictionary_lock);
486 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
487 SystemDictionary_lock->notify_all();
488 }
489
490 // Check for pending exception or null superk, and throw exception
491 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
492 handle_resolution_exception(next_name, true, CHECK_NULL);
493 }
494
495 return superk;
496 }
497
498 // If the class in is in the placeholder table, class loading is in progress.
499 // For cases where the application changes threads to load classes, it
500 // is critical to ClassCircularity detection that we try loading
501 // the superclass on the new thread internally, so we do parallel
502 // superclass loading here. This avoids deadlock for ClassCircularity
503 // detection for parallelCapable class loaders that lock on a per-class lock.
504 static void handle_parallel_super_load(Symbol* name,
505 Symbol* superclassname,
506 Handle class_loader,
507 TRAPS) {
508
509 // The result superk is not used; resolve_with_circularity_detection is called for circularity check only.
510 // This passes false to is_superclass to skip doing the unlikely optimization.
511 Klass* superk = SystemDictionary::resolve_with_circularity_detection(name,
512 superclassname,
513 class_loader,
514 false,
515 CHECK);
516 }
517
518 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
519 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
520 static bool needs_load_placeholder(Handle class_loader) {
521 return class_loader.is_null() || !is_parallelCapable(class_loader);
522 }
523
524 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
525 static InstanceKlass* handle_parallel_loading(JavaThread* current,
526 Symbol* name,
527 ClassLoaderData* loader_data,
528 bool must_wait_for_class_loading,
529 bool* throw_circularity_error) {
530 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
531 if (oldprobe != nullptr) {
532 // -Xcomp calls load_signature_classes which might result in loading
533 // a class that's already in the process of loading, so we detect CCE here also.
534 // Only need check_seen_thread once, not on each loop
535 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
536 log_circularity_error(name, oldprobe);
537 *throw_circularity_error = true;
538 return nullptr;
539 } else if (must_wait_for_class_loading) {
540 // Wait until the first thread has finished loading this class. Also wait until all the
541 // threads trying to load its superclass have removed their placeholders.
542 while (oldprobe != nullptr &&
543 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) {
544
545 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
546 // for the bootclass loader.
547 SystemDictionary_lock->wait();
548
549 // Check if classloading completed while we were waiting
550 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
551 if (check != nullptr) {
552 // Klass is already loaded, so just return it
553 return check;
554 }
555 // check if other thread failed to load and cleaned up
556 oldprobe = PlaceholderTable::get_entry(name, loader_data);
557 }
558 }
559 }
560 return nullptr;
561 }
562
563 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
564 assert(event != nullptr, "invariant");
565 assert(k != nullptr, "invariant");
566 event->set_loadedClass(k);
567 event->set_definingClassLoader(k->class_loader_data());
568 event->set_initiatingClassLoader(init_cld);
569 event->commit();
570 }
571
572 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
573 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
574 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
575 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
576 // This can return null, an exception or an InstanceKlass.
577 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
578 Handle class_loader,
579 TRAPS) {
580 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
581 DEBUG_ONLY(ResourceMark rm(THREAD));
582 assert(name != nullptr && !Signature::is_array(name) &&
583 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
584
585 EventClassLoad class_load_start_event;
586
587 HandleMark hm(THREAD);
588
589 ClassLoaderData* loader_data = register_loader(class_loader);
590 Dictionary* dictionary = loader_data->dictionary();
591
592 // Do lookup to see if class already exists.
593 InstanceKlass* probe = dictionary->find_class(THREAD, name);
594 if (probe != nullptr) return probe;
595
596 // Non-bootstrap class loaders will call out to class loader and
597 // define via jvm/jni_DefineClass which will acquire the
598 // class loader object lock to protect against multiple threads
599 // defining the class in parallel by accident.
600 // This lock must be acquired here so the waiter will find
601 // any successful result in the SystemDictionary and not attempt
602 // the define.
603 // ParallelCapable class loaders and the bootstrap classloader
604 // do not acquire lock here.
605 Handle lockObject = get_loader_lock_or_null(class_loader);
606 ObjectLocker ol(lockObject, THREAD);
607
608 bool circularity_detection_in_progress = false;
609 InstanceKlass* loaded_class = nullptr;
610 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
611
612 guarantee(THREAD->can_call_java(),
613 "can not load classes with compiler thread: class=%s, classloader=%s",
614 name->as_C_string(),
615 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
616
617 // Check again (after locking) if the class already exists in SystemDictionary
618 {
619 MutexLocker mu(THREAD, SystemDictionary_lock);
620 InstanceKlass* check = dictionary->find_class(THREAD, name);
621 if (check != nullptr) {
622 // InstanceKlass is already loaded, but we still need to check protection domain below.
623 loaded_class = check;
624 } else {
625 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
626 if (placeholder != nullptr && placeholder->circularity_detection_in_progress()) {
627 circularity_detection_in_progress = true;
628 superclassname = placeholder->next_klass_name();
629 assert(superclassname != nullptr, "superclass has to have a name");
630 }
631 }
632 }
633
634 // If the class is in the placeholder table with super_class set,
635 // handle superclass loading in progress.
636 if (circularity_detection_in_progress) {
637 handle_parallel_super_load(name, superclassname,
638 class_loader,
639 CHECK_NULL);
640 }
641
642 bool throw_circularity_error = false;
643 if (loaded_class == nullptr) {
644 bool load_placeholder_added = false;
645
646 // Add placeholder entry to record loading instance class
647 // case 1. Bootstrap classloader
648 // This classloader supports parallelism at the classloader level
649 // but only allows a single thread to load a class/classloader pair.
650 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
651 // case 2. parallelCapable user level classloaders
652 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
653 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
654 // case 3. traditional classloaders that rely on the classloader object lock
655 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
656 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
657 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
658 {
659 MutexLocker mu(THREAD, SystemDictionary_lock);
660 if (needs_load_placeholder(class_loader)) {
661 loaded_class = handle_parallel_loading(THREAD,
662 name,
663 loader_data,
664 class_loader.is_null(),
665 &throw_circularity_error);
666 }
667
668 // Recheck if the class has been loaded for all class loader cases and
669 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
670 if (!throw_circularity_error && loaded_class == nullptr) {
671 InstanceKlass* check = dictionary->find_class(THREAD, name);
672 if (check != nullptr) {
673 loaded_class = check;
674 } else if (needs_load_placeholder(class_loader)) {
675 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
676 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
677 PlaceholderTable::LOAD_INSTANCE,
678 nullptr,
679 THREAD);
680 load_placeholder_added = true;
681 }
682 }
683 }
684
685 // Must throw error outside of owning lock
686 if (throw_circularity_error) {
687 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
688 ResourceMark rm(THREAD);
689 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
690 }
691
692 // Be careful when modifying this code: once you have run
693 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
694 // you need to find_and_remove it before returning.
695 // So be careful to not exit with a CHECK_ macro between these calls.
696
697 if (loaded_class == nullptr) {
698 // Do actual loading
699 loaded_class = load_instance_class(name, class_loader, THREAD);
700 }
701
702 if (load_placeholder_added) {
703 // clean up placeholder entries for LOAD_INSTANCE success or error
704 // This brackets the SystemDictionary updates for both defining
705 // and initiating loaders
706 MutexLocker mu(THREAD, SystemDictionary_lock);
707 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
708 SystemDictionary_lock->notify_all();
709 }
710 }
711
712 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
713 return nullptr;
714 }
715
716 if (class_load_start_event.should_commit()) {
717 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
718 }
719
720 // Make sure we have the right class in the dictionary
721 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
722
723 return loaded_class;
724 }
725
726
727 // This routine does not lock the system dictionary.
728 //
729 // Since readers don't hold a lock, we must make sure that system
730 // dictionary entries are added to in a safe way (all links must
731 // be updated in an MT-safe manner). All entries are removed during class
732 // unloading, when this class loader is no longer referenced.
733 //
734 // Callers should be aware that an entry could be added just after
735 // Dictionary is read here, so the caller will not see
736 // the new entry.
737
738 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
739 Symbol* class_name,
740 Handle class_loader) {
741
742 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
743 if (loader_data == nullptr) {
744 // If the ClassLoaderData has not been setup,
745 // then the class loader has no entries in the dictionary.
746 return nullptr;
747 }
748
749 Dictionary* dictionary = loader_data->dictionary();
750 return dictionary->find_class(current, class_name);
751 }
752
753 // Look for a loaded instance or array klass by name. Do not do any loading.
754 // return null in case of error.
755 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
756 Symbol* class_name,
757 Handle class_loader) {
758 Klass* k = nullptr;
759 assert(class_name != nullptr, "class name must be non nullptr");
760
761 if (Signature::is_array(class_name)) {
762 // The name refers to an array. Parse the name.
763 // dimension and object_key in FieldArrayInfo are assigned as a
764 // side-effect of this call
765 SignatureStream ss(class_name, false);
766 int ndims = ss.skip_array_prefix(); // skip all '['s
767 BasicType t = ss.type();
768 if (t != T_OBJECT) {
769 k = Universe::typeArrayKlass(t);
770 } else {
771 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader);
772 }
773 if (k != nullptr) {
774 k = k->array_klass_or_null(ndims);
775 }
776 } else {
777 k = find_instance_klass(current, class_name, class_loader);
778 }
779 return k;
780 }
781
782 // Note: this method is much like resolve_class_from_stream, but
783 // does not publish the classes in the SystemDictionary.
784 // Handles Lookup.defineClass hidden.
785 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
786 ClassFileStream* st,
787 Symbol* class_name,
788 Handle class_loader,
789 const ClassLoadInfo& cl_info,
790 TRAPS) {
791
792 EventClassLoad class_load_start_event;
793 ClassLoaderData* loader_data;
794
795 // - for hidden classes that are not strong: create a new CLD that has a class holder and
796 // whose loader is the Lookup class's loader.
797 // - for hidden class: add the class to the Lookup class's loader's CLD.
798 assert (cl_info.is_hidden(), "only used for hidden classes");
799 bool create_mirror_cld = !cl_info.is_strong_hidden();
800 loader_data = register_loader(class_loader, create_mirror_cld);
801
802 assert(st != nullptr, "invariant");
803
804 // Parse stream and create a klass.
805 InstanceKlass* k = KlassFactory::create_from_stream(st,
806 class_name,
807 loader_data,
808 cl_info,
809 CHECK_NULL);
810 assert(k != nullptr, "no klass created");
811
812 // Hidden classes that are not strong must update ClassLoaderData holder
813 // so that they can be unloaded when the mirror is no longer referenced.
814 if (!cl_info.is_strong_hidden()) {
815 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
816 }
817
818 // Add to class hierarchy, and do possible deoptimizations.
819 k->add_to_hierarchy(THREAD);
820 // But, do not add to dictionary.
821
822 k->link_class(CHECK_NULL);
823
824 // notify jvmti
825 if (JvmtiExport::should_post_class_load()) {
826 JvmtiExport::post_class_load(THREAD, k);
827 }
828 if (class_load_start_event.should_commit()) {
829 post_class_load_event(&class_load_start_event, k, loader_data);
830 }
831
832 return k;
833 }
834
835 // Add a klass to the system from a stream (called by jni_DefineClass and
836 // JVM_DefineClass).
837 // Note: class_name can be null. In that case we do not know the name of
838 // the class until we have parsed the stream.
839 // This function either returns an InstanceKlass or throws an exception. It does
840 // not return null without a pending exception.
841 InstanceKlass* SystemDictionary::resolve_class_from_stream(
842 ClassFileStream* st,
843 Symbol* class_name,
844 Handle class_loader,
845 const ClassLoadInfo& cl_info,
846 TRAPS) {
847
848 HandleMark hm(THREAD);
849
850 ClassLoaderData* loader_data = register_loader(class_loader);
851
852 // Classloaders that support parallelism, e.g. bootstrap classloader,
853 // do not acquire lock here
854 Handle lockObject = get_loader_lock_or_null(class_loader);
855 ObjectLocker ol(lockObject, THREAD);
856
857 // Parse the stream and create a klass.
858 // Note that we do this even though this klass might
859 // already be present in the SystemDictionary, otherwise we would not
860 // throw potential ClassFormatErrors.
861 InstanceKlass* k = nullptr;
862
863 #if INCLUDE_CDS
864 if (!CDSConfig::is_dumping_static_archive()) {
865 k = SystemDictionaryShared::lookup_from_stream(class_name,
866 class_loader,
867 cl_info.protection_domain(),
868 st,
869 CHECK_NULL);
870 }
871 #endif
872
873 if (k == nullptr) {
874 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
875 }
876
877 assert(k != nullptr, "no klass created");
878 Symbol* h_name = k->name();
879 assert(class_name == nullptr || class_name == h_name, "name mismatch");
880
881 // Add class just loaded
882 // If a class loader supports parallel classloading, handle parallel define requests.
883 // find_or_define_instance_class may return a different InstanceKlass,
884 // in which case the old k would be deallocated
885 if (is_parallelCapable(class_loader)) {
886 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
887 } else {
888 define_instance_class(k, class_loader, THREAD);
889
890 // If defining the class throws an exception register 'k' for cleanup.
891 if (HAS_PENDING_EXCEPTION) {
892 assert(k != nullptr, "Must have an instance klass here!");
893 loader_data->add_to_deallocate_list(k);
894 return nullptr;
895 }
896 }
897
898 // Make sure we have an entry in the SystemDictionary on success
899 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
900
901 return k;
902 }
903
904 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
905 Symbol* class_name,
906 Handle class_loader,
907 const ClassLoadInfo& cl_info,
908 TRAPS) {
909 if (cl_info.is_hidden()) {
910 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
911 } else {
912 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
913 }
914 }
915
916
917 #if INCLUDE_CDS
918 // Check if a shared class can be loaded by the specific classloader.
919 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
920 InstanceKlass* ik,
921 PackageEntry* pkg_entry,
922 Handle class_loader) {
923 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
924 "Cannot use sharing if java.base is patched");
925
926 // (1) Check if we are loading into the same loader as in dump time.
927
928 if (ik->defined_by_boot_loader()) {
929 if (class_loader() != nullptr) {
930 return false;
931 }
932 } else if (ik->defined_by_platform_loader()) {
933 if (class_loader() != java_platform_loader()) {
934 return false;
935 }
936 } else if (ik->defined_by_app_loader()) {
937 if (class_loader() != java_system_loader()) {
938 return false;
939 }
940 } else {
941 // ik was loaded by a custom loader during dump time
942 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
943 return false;
944 } else {
945 return true;
946 }
947 }
948
949 // (2) Check if we are loading into the same module from the same location as in dump time.
950
951 if (CDSConfig::is_using_optimized_module_handling()) {
952 // Class visibility has not changed between dump time and run time, so a class
953 // that was visible (and thus archived) during dump time is always visible during runtime.
954 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
955 "visibility cannot change between dump time and runtime");
956 return true;
957 }
958 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
959 }
960
961 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
962 InstanceKlass* ik,
963 PackageEntry* pkg_entry,
964 Handle class_loader) {
965 int scp_index = ik->shared_classpath_index();
966 assert(!ik->defined_by_other_loaders(), "this function should be called for built-in classes only");
967 assert(scp_index >= 0, "must be");
968 const AOTClassLocation* cl = AOTClassLocationConfig::runtime()->class_location_at(scp_index);
969 if (!Universe::is_module_initialized()) {
970 assert(cl != nullptr, "must be");
971 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
972 // has restricted the classes can be loaded at this step to be only:
973 // [1] cs->is_modules_image(): classes in java.base, or,
974 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
975 assert(cl->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
976 "only these classes can be loaded before the module system is initialized");
977 assert(class_loader.is_null(), "sanity");
978 return true;
979 }
980
981 if (pkg_entry == nullptr) {
982 // We might have looked up pkg_entry before the module system was initialized.
983 // Need to reload it now.
984 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
985 if (pkg_name != nullptr) {
986 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
987 }
988 }
989
990 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
991 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
992 bool was_archived_from_named_module = !cl->has_unnamed_module();
993 bool visible;
994
995 if (was_archived_from_named_module) {
996 if (should_be_in_named_module) {
997 // Is the module loaded from the same location as during dump time?
998 visible = mod_entry->shared_path_index() == scp_index;
999 if (visible) {
1000 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1001 }
1002 } else {
1003 // During dump time, this class was in a named module, but at run time, this class should be
1004 // in an unnamed module.
1005 visible = false;
1006 }
1007 } else {
1008 if (should_be_in_named_module) {
1009 // During dump time, this class was in an unnamed, but at run time, this class should be
1010 // in a named module.
1011 visible = false;
1012 } else {
1013 visible = true;
1014 }
1015 }
1016
1017 return visible;
1018 }
1019
1020 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1021 Handle class_loader, bool is_superclass, TRAPS) {
1022 assert(super_type->in_aot_cache(), "must be");
1023
1024 // Quick check if the super type has been already loaded.
1025 // + Don't do it for unregistered classes -- they can be unloaded so
1026 // super_type->class_loader_data() could be stale.
1027 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1028 if (!super_type->defined_by_other_loaders() && super_type->class_loader_data() != nullptr) {
1029 // Check if the superclass is loaded by the current class_loader
1030 Symbol* name = super_type->name();
1031 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader);
1032 if (check == super_type) {
1033 return true;
1034 }
1035 }
1036
1037 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(),
1038 class_loader, is_superclass, CHECK_false);
1039 if (found == super_type) {
1040 return true;
1041 } else {
1042 // The dynamically resolved super type is not the same as the one we used during dump time,
1043 // so we cannot use the class.
1044 return false;
1045 }
1046 }
1047
1048 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader, TRAPS) {
1049 // Check the superclass and interfaces. They must be the same
1050 // as in dump time, because the layout of <ik> depends on
1051 // the specific layout of ik->super() and ik->local_interfaces().
1052 //
1053 // If unexpected superclass or interfaces are found, we cannot
1054 // load <ik> from the shared archive.
1055
1056 if (ik->super() != nullptr) {
1057 bool check_super = check_shared_class_super_type(ik, ik->super(),
1058 class_loader, true,
1059 CHECK_false);
1060 if (!check_super) {
1061 return false;
1062 }
1063 }
1064
1065 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1066 int num_interfaces = interfaces->length();
1067 for (int index = 0; index < num_interfaces; index++) {
1068 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, false,
1069 CHECK_false);
1070 if (!check_interface) {
1071 return false;
1072 }
1073 }
1074
1075 return true;
1076 }
1077
1078 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1079 Handle class_loader,
1080 Handle protection_domain,
1081 const ClassFileStream *cfs,
1082 PackageEntry* pkg_entry,
1083 TRAPS) {
1084 assert(ik != nullptr, "sanity");
1085 assert(ik->in_aot_cache(), "sanity");
1086 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1087 assert(AtomicAccess::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1088 Symbol* class_name = ik->name();
1089
1090 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1091 ik->set_shared_loading_failed();
1092 return nullptr;
1093 }
1094
1095 bool check = check_shared_class_super_types(ik, class_loader, CHECK_NULL);
1096 if (!check) {
1097 ik->set_shared_loading_failed();
1098 return nullptr;
1099 }
1100
1101 InstanceKlass* new_ik = nullptr;
1102 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1103 // It will be skipped for shared VM hidden lambda proxy classes.
1104 if (!ik->is_hidden()) {
1105 new_ik = KlassFactory::check_shared_class_file_load_hook(
1106 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1107 }
1108 if (new_ik != nullptr) {
1109 // The class is changed by CFLH. Return the new class. The shared class is
1110 // not used.
1111 return new_ik;
1112 }
1113
1114 // Adjust methods to recover missing data. They need addresses for
1115 // interpreter entry points and their default native method address
1116 // must be reset.
1117
1118 // Shared classes are all currently loaded by either the bootstrap or
1119 // internal parallel class loaders, so this will never cause a deadlock
1120 // on a custom class loader lock.
1121 // Since this class is already locked with parallel capable class
1122 // loaders, including the bootstrap loader via the placeholder table,
1123 // this lock is currently a nop.
1124
1125 ClassLoaderData* loader_data = class_loader_data(class_loader);
1126 {
1127 HandleMark hm(THREAD);
1128 Handle lockObject = get_loader_lock_or_null(class_loader);
1129 ObjectLocker ol(lockObject, THREAD);
1130 // prohibited package check assumes all classes loaded from archive call
1131 // restore_unshareable_info which calls ik->set_package()
1132 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1133 }
1134
1135 load_shared_class_misc(ik, loader_data);
1136 return ik;
1137 }
1138
1139 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1140 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1141
1142 // For boot loader, ensure that GetSystemPackage knows that a class in this
1143 // package was loaded.
1144 if (loader_data->is_the_null_class_loader_data()) {
1145 s2 path_index = ik->shared_classpath_index();
1146 ik->set_classpath_index(path_index);
1147 }
1148
1149 // notify a class loaded from shared object
1150 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1151
1152 if (CDSConfig::is_dumping_final_static_archive()) {
1153 SystemDictionaryShared::init_dumptime_info_from_preimage(ik);
1154 }
1155 }
1156
1157 // This is much more lightweight than SystemDictionary::resolve_or_null
1158 // - There's only a single Java thread at this point. No need for placeholder.
1159 // - All supertypes of ik have been loaded
1160 // - There's no circularity (checked in AOT assembly phase)
1161 // - There's no need to call java.lang.ClassLoader::load_class() because the boot/platform/app
1162 // loaders are well-behaved
1163 void SystemDictionary::preload_class(Handle class_loader, InstanceKlass* ik, TRAPS) {
1164 precond(Universe::is_bootstrapping());
1165 precond(java_platform_loader() != nullptr && java_system_loader() != nullptr);
1166 precond(class_loader() == nullptr || class_loader() == java_platform_loader() ||class_loader() == java_system_loader());
1167 precond(CDSConfig::is_using_aot_linked_classes());
1168 precond(AOTMetaspace::in_aot_cache_static_region((void*)ik));
1169 precond(!ik->is_loaded());
1170
1171 #ifdef ASSERT
1172 // preload_class() must be called in the correct order -- all super types must have
1173 // already been loaded.
1174 if (ik->java_super() != nullptr) {
1175 assert(ik->java_super()->is_loaded(), "must be");
1176 }
1177
1178 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1179 int num_interfaces = interfaces->length();
1180 for (int index = 0; index < num_interfaces; index++) {
1181 assert(interfaces->at(index)->is_loaded(), "must be");
1182 }
1183 #endif
1184
1185 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1186 oop java_mirror = ik->archived_java_mirror();
1187 precond(java_mirror != nullptr);
1188
1189 Handle pd(THREAD, java_lang_Class::protection_domain(java_mirror));
1190 PackageEntry* pkg_entry = ik->package();
1191 assert(pkg_entry != nullptr || ClassLoader::package_from_class_name(ik->name()) == nullptr,
1192 "non-empty packages must have been archived");
1193
1194 // TODO: the following assert requires JDK-8365580
1195 // assert(is_shared_class_visible(ik->name(), ik, pkg_entry, class_loader), "must be");
1196
1197 ik->restore_unshareable_info(loader_data, pd, pkg_entry, CHECK);
1198 load_shared_class_misc(ik, loader_data);
1199 ik->add_to_hierarchy(THREAD);
1200
1201 if (!ik->is_hidden()) {
1202 update_dictionary(THREAD, ik, loader_data);
1203 }
1204
1205 assert(java_lang_Class::module(java_mirror) != nullptr, "must have been archived");
1206 assert(ik->is_loaded(), "Must be in at least loaded state");
1207 }
1208
1209 #endif // INCLUDE_CDS
1210
1211 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1212
1213 if (class_loader.is_null()) {
1214 ResourceMark rm(THREAD);
1215 PackageEntry* pkg_entry = nullptr;
1216 bool search_only_bootloader_append = false;
1217
1218 // Find the package in the boot loader's package entry table.
1219 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1220 if (pkg_name != nullptr) {
1221 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1222 }
1223
1224 // Prior to attempting to load the class, enforce the boot loader's
1225 // visibility boundaries.
1226 if (!Universe::is_module_initialized()) {
1227 // During bootstrapping, prior to module initialization, any
1228 // class attempting to be loaded must be checked against the
1229 // java.base packages in the boot loader's PackageEntryTable.
1230 // No class outside of java.base is allowed to be loaded during
1231 // this bootstrapping window.
1232 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1233 // Class is either in the unnamed package or in
1234 // a named package within the unnamed module. Either
1235 // case is outside of java.base, do not attempt to
1236 // load the class post java.base definition. If
1237 // java.base has not been defined, let the class load
1238 // and its package will be checked later by
1239 // ModuleEntryTable::verify_javabase_packages.
1240 if (ModuleEntryTable::javabase_defined()) {
1241 return nullptr;
1242 }
1243 } else {
1244 // Check that the class' package is defined within java.base.
1245 ModuleEntry* mod_entry = pkg_entry->module();
1246 Symbol* mod_entry_name = mod_entry->name();
1247 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1248 return nullptr;
1249 }
1250 }
1251 } else {
1252 // After the module system has been initialized, check if the class'
1253 // package is in a module defined to the boot loader.
1254 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1255 // Class is either in the unnamed package, in a named package
1256 // within a module not defined to the boot loader or in a
1257 // a named package within the unnamed module. In all cases,
1258 // limit visibility to search for the class only in the boot
1259 // loader's append path.
1260 if (!ClassLoader::has_bootclasspath_append()) {
1261 // If there is no bootclasspath append entry, no need to continue
1262 // searching.
1263 return nullptr;
1264 }
1265 search_only_bootloader_append = true;
1266 }
1267 }
1268
1269 // Prior to bootstrapping's module initialization, never load a class outside
1270 // of the boot loader's module path
1271 assert(Universe::is_module_initialized() ||
1272 !search_only_bootloader_append,
1273 "Attempt to load a class outside of boot loader's module path");
1274
1275 // Search for classes in the CDS archive.
1276 InstanceKlass* k = nullptr;
1277
1278 #if INCLUDE_CDS
1279 if (CDSConfig::is_using_archive())
1280 {
1281 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1282 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1283 if (ik != nullptr && ik->defined_by_boot_loader() && !ik->shared_loading_failed()) {
1284 SharedClassLoadingMark slm(THREAD, ik);
1285 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1286 }
1287 }
1288 #endif
1289
1290 if (k == nullptr) {
1291 // Use VM class loader
1292 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1293 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1294 }
1295
1296 // find_or_define_instance_class may return a different InstanceKlass
1297 if (k != nullptr) {
1298 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1299 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1300 }
1301 return k;
1302 } else {
1303 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1304 ResourceMark rm(THREAD);
1305
1306 JavaThread* jt = THREAD;
1307
1308 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1309 ClassLoader::perf_app_classload_selftime(),
1310 ClassLoader::perf_app_classload_count(),
1311 jt->get_thread_stat()->perf_recursion_counts_addr(),
1312 jt->get_thread_stat()->perf_timers_addr(),
1313 PerfClassTraceTime::CLASS_LOAD);
1314
1315 // Translate to external class name format, i.e., convert '/' chars to '.'
1316 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1317
1318 JavaValue result(T_OBJECT);
1319
1320 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1321
1322 // Call public unsynchronized loadClass(String) directly for all class loaders.
1323 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1324 // acquire a class-name based lock rather than the class loader object lock.
1325 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1326 JavaCalls::call_virtual(&result,
1327 class_loader,
1328 spec_klass,
1329 vmSymbols::loadClass_name(),
1330 vmSymbols::string_class_signature(),
1331 string,
1332 CHECK_NULL);
1333
1334 assert(result.get_type() == T_OBJECT, "just checking");
1335 oop obj = result.get_oop();
1336
1337 // Primitive classes return null since forName() cannot be
1338 // used to obtain any of the Class objects representing primitives or void
1339 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1340 InstanceKlass* k = java_lang_Class::as_InstanceKlass(obj);
1341 // For user defined Java class loaders, check that the name returned is
1342 // the same as that requested. This check is done for the bootstrap
1343 // loader when parsing the class file.
1344 if (class_name == k->name()) {
1345 return k;
1346 }
1347 }
1348 // Class is not found or has the wrong name, return null
1349 return nullptr;
1350 }
1351 }
1352
1353 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1354 Handle class_loader,
1355 TRAPS) {
1356
1357 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1358
1359 // If everything was OK (no exceptions, no null return value), and
1360 // class_loader is NOT the defining loader, do a little more bookkeeping.
1361 if (loaded_class != nullptr &&
1362 loaded_class->class_loader() != class_loader()) {
1363
1364 ClassLoaderData* loader_data = class_loader_data(class_loader);
1365 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1366
1367 // Record dependency for non-parent delegation.
1368 // This recording keeps the defining class loader of the klass (loaded_class) found
1369 // from being unloaded while the initiating class loader is loaded
1370 // even if the reference to the defining class loader is dropped
1371 // before references to the initiating class loader.
1372 loader_data->record_dependency(loaded_class);
1373
1374 update_dictionary(THREAD, loaded_class, loader_data);
1375
1376 if (JvmtiExport::should_post_class_load()) {
1377 JvmtiExport::post_class_load(THREAD, loaded_class);
1378 }
1379 }
1380 return loaded_class;
1381 }
1382
1383 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1384 EventClassDefine event;
1385 if (event.should_commit()) {
1386 event.set_definedClass(k);
1387 event.set_definingClassLoader(def_cld);
1388 event.commit();
1389 }
1390 }
1391
1392 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1393
1394 ClassLoaderData* loader_data = k->class_loader_data();
1395 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1396
1397 // Bootstrap and other parallel classloaders don't acquire a lock,
1398 // they use placeholder token.
1399 // If a parallelCapable class loader calls define_instance_class instead of
1400 // find_or_define_instance_class to get here, we have a timing
1401 // hole with systemDictionary updates and check_constraints
1402 if (!is_parallelCapable(class_loader)) {
1403 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1404 get_loader_lock_or_null(class_loader)),
1405 "define called without lock");
1406 }
1407
1408 // Check class-loading constraints. Throw exception if violation is detected.
1409 // Grabs and releases SystemDictionary_lock
1410 // The check_constraints/find_class call and update_dictionary sequence
1411 // must be "atomic" for a specific class/classloader pair so we never
1412 // define two different instanceKlasses for that class/classloader pair.
1413 // Existing classloaders will call define_instance_class with the
1414 // classloader lock held
1415 // Parallel classloaders will call find_or_define_instance_class
1416 // which will require a token to perform the define class
1417 check_constraints(k, loader_data, true, CHECK);
1418
1419 // Register class just loaded with class loader (placed in ArrayList)
1420 // Note we do this before updating the dictionary, as this can
1421 // fail with an OutOfMemoryError (if it does, we will *not* put this
1422 // class in the dictionary and will not update the class hierarchy).
1423 // JVMTI FollowReferences needs to find the classes this way.
1424 if (k->class_loader() != nullptr) {
1425 methodHandle m(THREAD, Universe::loader_addClass_method());
1426 JavaValue result(T_VOID);
1427 JavaCallArguments args(class_loader);
1428 args.push_oop(Handle(THREAD, k->java_mirror()));
1429 JavaCalls::call(&result, m, &args, CHECK);
1430 }
1431
1432 // Add to class hierarchy, and do possible deoptimizations.
1433 k->add_to_hierarchy(THREAD);
1434
1435 // Add to systemDictionary - so other classes can see it.
1436 // Grabs and releases SystemDictionary_lock
1437 update_dictionary(THREAD, k, loader_data);
1438
1439 // notify jvmti
1440 if (JvmtiExport::should_post_class_load()) {
1441 JvmtiExport::post_class_load(THREAD, k);
1442 }
1443 post_class_define_event(k, loader_data);
1444 }
1445
1446 // Support parallel classloading
1447 // All parallel class loaders, including bootstrap classloader
1448 // lock a placeholder entry for this class/class_loader pair
1449 // to allow parallel defines of different classes for this class loader
1450 // With AllowParallelDefine flag==true, in case they do not synchronize around
1451 // FindLoadedClass/DefineClass, calls, we check for parallel
1452 // loading for them, wait if a defineClass is in progress
1453 // and return the initial requestor's results
1454 // This flag does not apply to the bootstrap classloader.
1455 // With AllowParallelDefine flag==false, call through to define_instance_class
1456 // which will throw LinkageError: duplicate class definition.
1457 // False is the requested default.
1458 // For better performance, the class loaders should synchronize
1459 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1460 // potentially waste time reading and parsing the bytestream.
1461 // Note: VM callers should ensure consistency of k/class_name,class_loader
1462 // Be careful when modifying this code: once you have run
1463 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1464 // you need to find_and_remove it before returning.
1465 // So be careful to not exit with a CHECK_ macro between these calls.
1466 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1467 InstanceKlass* k, TRAPS) {
1468
1469 Symbol* name_h = k->name();
1470 ClassLoaderData* loader_data = class_loader_data(class_loader);
1471 Dictionary* dictionary = loader_data->dictionary();
1472
1473 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1474 {
1475 MutexLocker mu(THREAD, SystemDictionary_lock);
1476 // First check if class already defined
1477 if (is_parallelDefine(class_loader)) {
1478 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1479 if (check != nullptr) {
1480 return check;
1481 }
1482 }
1483
1484 // Acquire define token for this class/classloader
1485 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1486 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1487 // Wait if another thread defining in parallel
1488 // All threads wait - even those that will throw duplicate class: otherwise
1489 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1490 // if other thread has not finished updating dictionary
1491 while (probe->definer() != nullptr) {
1492 SystemDictionary_lock->wait();
1493 }
1494 // Only special cases allow parallel defines and can use other thread's results
1495 // Other cases fall through, and may run into duplicate defines
1496 // caught by finding an entry in the SystemDictionary
1497 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1498 InstanceKlass* ik = probe->instance_klass();
1499 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1500 SystemDictionary_lock->notify_all();
1501 #ifdef ASSERT
1502 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1503 assert(check != nullptr, "definer missed recording success");
1504 #endif
1505 return ik;
1506 } else {
1507 // This thread will define the class (even if earlier thread tried and had an error)
1508 probe->set_definer(THREAD);
1509 }
1510 }
1511
1512 define_instance_class(k, class_loader, THREAD);
1513
1514 // definer must notify any waiting threads
1515 {
1516 MutexLocker mu(THREAD, SystemDictionary_lock);
1517 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1518 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1519 if (!HAS_PENDING_EXCEPTION) {
1520 probe->set_instance_klass(k);
1521 }
1522 probe->set_definer(nullptr);
1523 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1524 SystemDictionary_lock->notify_all();
1525 }
1526
1527 return HAS_PENDING_EXCEPTION ? nullptr : k;
1528 }
1529
1530 // If a class loader supports parallel classloading handle parallel define requests.
1531 // find_or_define_instance_class may return a different InstanceKlass
1532 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1533 InstanceKlass* k, TRAPS) {
1534 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1535 // Clean up original InstanceKlass if duplicate or error
1536 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1537 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1538 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1539 k->class_loader_data()->add_to_deallocate_list(k);
1540 } else if (HAS_PENDING_EXCEPTION) {
1541 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1542 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1543 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1544 k->class_loader_data()->add_to_deallocate_list(k);
1545 }
1546 return defined_k;
1547 }
1548
1549
1550 // ----------------------------------------------------------------------------
1551 // GC support
1552
1553 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1554 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1555
1556 bool unloading_occurred;
1557 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1558 {
1559 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1560 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1561 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1562 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1563 if (unloading_occurred) {
1564 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1565 JFR_ONLY(Jfr::on_unloading_classes();)
1566 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1567 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1568 ClassLoaderDataGraph::clean_module_and_package_info();
1569 LoaderConstraintTable::purge_loader_constraints();
1570 ResolutionErrorTable::purge_resolution_errors();
1571 }
1572 }
1573
1574 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1575
1576 if (unloading_occurred) {
1577 SymbolTable::trigger_cleanup();
1578
1579 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1580 InstanceKlass::clean_initialization_error_table();
1581 }
1582
1583 return unloading_occurred;
1584 }
1585
1586 void SystemDictionary::methods_do(void f(Method*)) {
1587 // Walk methods in loaded classes
1588
1589 {
1590 MutexLocker ml(ClassLoaderDataGraph_lock);
1591 ClassLoaderDataGraph::methods_do(f);
1592 }
1593
1594 auto doit = [&] (InvokeMethodKey key, Method* method) {
1595 if (method != nullptr) {
1596 f(method);
1597 }
1598 };
1599
1600 {
1601 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1602 _invoke_method_intrinsic_table->iterate_all(doit);
1603 }
1604
1605 }
1606
1607 // ----------------------------------------------------------------------------
1608 // Initialization
1609
1610 void SystemDictionary::initialize(TRAPS) {
1611 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1612 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1613 ResolutionErrorTable::initialize();
1614 LoaderConstraintTable::initialize();
1615 PlaceholderTable::initialize();
1616 #if INCLUDE_CDS
1617 SystemDictionaryShared::initialize();
1618 if (CDSConfig::is_dumping_archive()) {
1619 AOTClassLocationConfig::dumptime_init(THREAD);
1620 }
1621 #endif
1622 // Resolve basic classes
1623 vmClasses::resolve_all(CHECK);
1624 // Resolve classes used by archived heap objects
1625 if (CDSConfig::is_using_archive()) {
1626 HeapShared::resolve_classes(THREAD);
1627 }
1628 }
1629
1630 // Constraints on class loaders. The details of the algorithm can be
1631 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1632 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1633 // that the dictionary needs to maintain a set of constraints that
1634 // must be satisfied by all classes in the dictionary.
1635 // if defining is true, then LinkageError if already in dictionary
1636 // if initiating loader, then ok if InstanceKlass matches existing entry
1637
1638 void SystemDictionary::check_constraints(InstanceKlass* k,
1639 ClassLoaderData* loader_data,
1640 bool defining,
1641 TRAPS) {
1642 ResourceMark rm(THREAD);
1643 stringStream ss;
1644 bool throwException = false;
1645
1646 {
1647 Symbol* name = k->name();
1648
1649 MutexLocker mu(THREAD, SystemDictionary_lock);
1650
1651 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1652 if (check != nullptr) {
1653 // If different InstanceKlass - duplicate class definition,
1654 // else - ok, class loaded by a different thread in parallel.
1655 // We should only have found it if it was done loading and ok to use.
1656
1657 if ((defining == true) || (k != check)) {
1658 throwException = true;
1659 ss.print("loader %s", loader_data->loader_name_and_id());
1660 ss.print(" attempted duplicate %s definition for %s. (%s)",
1661 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1662 } else {
1663 return;
1664 }
1665 }
1666
1667 if (throwException == false) {
1668 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1669 throwException = true;
1670 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1671 ss.print(" wants to load %s %s.",
1672 k->external_kind(), k->external_name());
1673 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1674 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1675 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1676 existing_klass->external_kind(),
1677 existing_klass->class_loader_data()->loader_name_and_id(),
1678 existing_klass->class_in_module_of_loader(false, true));
1679 } else {
1680 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1681 }
1682 }
1683 }
1684 }
1685
1686 // Throw error now if needed (cannot throw while holding
1687 // SystemDictionary_lock because of rank ordering)
1688 if (throwException == true) {
1689 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1690 }
1691 }
1692
1693 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1694 // have been called.
1695 void SystemDictionary::update_dictionary(JavaThread* current,
1696 InstanceKlass* k,
1697 ClassLoaderData* loader_data) {
1698 MonitorLocker mu1(SystemDictionary_lock);
1699
1700 // Make a new dictionary entry.
1701 Symbol* name = k->name();
1702 Dictionary* dictionary = loader_data->dictionary();
1703 InstanceKlass* sd_check = dictionary->find_class(current, name);
1704 if (sd_check == nullptr) {
1705 dictionary->add_klass(current, name, k);
1706 }
1707 mu1.notify_all();
1708 }
1709
1710 #if INCLUDE_CDS
1711 // Indicate that loader_data has initiated the loading of class k, which
1712 // has already been defined by a parent loader.
1713 // This API should be used only by AOTLinkedClassBulkLoader
1714 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1715 InstanceKlass* k,
1716 ClassLoaderData* loader_data) {
1717 assert(CDSConfig::is_using_aot_linked_classes(), "must be");
1718 assert_locked_or_safepoint(SystemDictionary_lock);
1719 Symbol* name = k->name();
1720 Dictionary* dictionary = loader_data->dictionary();
1721 assert(k->is_loaded(), "must be");
1722 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1723 assert(dictionary->find_class(current, name) == nullptr, "sanity");
1724 dictionary->add_klass(current, name, k);
1725 }
1726 #endif
1727
1728 // Try to find a class name using the loader constraints. The
1729 // loader constraints might know about a class that isn't fully loaded
1730 // yet and these will be ignored.
1731 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1732 Thread* current, Symbol* class_name, Handle class_loader) {
1733
1734 // First see if it has been loaded directly.
1735 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader);
1736 if (klass != nullptr)
1737 return klass;
1738
1739 // Now look to see if it has been loaded elsewhere, and is subject to
1740 // a loader constraint that would require this loader to return the
1741 // klass that is already loaded.
1742 if (Signature::is_array(class_name)) {
1743 // For array classes, their Klass*s are not kept in the
1744 // constraint table. The element Klass*s are.
1745 SignatureStream ss(class_name, false);
1746 int ndims = ss.skip_array_prefix(); // skip all '['s
1747 BasicType t = ss.type();
1748 if (t != T_OBJECT) {
1749 klass = Universe::typeArrayKlass(t);
1750 } else {
1751 MutexLocker mu(current, SystemDictionary_lock);
1752 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1753 }
1754 // If element class already loaded, allocate array klass
1755 if (klass != nullptr) {
1756 klass = klass->array_klass_or_null(ndims);
1757 }
1758 } else {
1759 MutexLocker mu(current, SystemDictionary_lock);
1760 // Non-array classes are easy: simply check the constraint table.
1761 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1762 }
1763
1764 return klass;
1765 }
1766
1767 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1768 Klass* klass_being_linked,
1769 Handle class_loader1,
1770 Handle class_loader2) {
1771 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1772 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1773
1774 Symbol* constraint_name = nullptr;
1775
1776 if (!Signature::is_array(class_name)) {
1777 constraint_name = class_name;
1778 } else {
1779 // For array classes, their Klass*s are not kept in the
1780 // constraint table. The element classes are.
1781 SignatureStream ss(class_name, false);
1782 ss.skip_array_prefix(); // skip all '['s
1783 if (!ss.has_envelope()) {
1784 return true; // primitive types always pass
1785 }
1786 constraint_name = ss.as_symbol();
1787 // Increment refcount to keep constraint_name alive after
1788 // SignatureStream is destructed. It will be decremented below
1789 // before returning.
1790 constraint_name->increment_refcount();
1791 }
1792
1793 Dictionary* dictionary1 = loader_data1->dictionary();
1794 Dictionary* dictionary2 = loader_data2->dictionary();
1795
1796 JavaThread* current = JavaThread::current();
1797 {
1798 MutexLocker mu_s(SystemDictionary_lock);
1799 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1800 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1801 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1802 klass2, loader_data2);
1803 #if INCLUDE_CDS
1804 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1805 !klass_being_linked->in_aot_cache()) {
1806 SystemDictionaryShared::record_linking_constraint(constraint_name,
1807 InstanceKlass::cast(klass_being_linked),
1808 class_loader1, class_loader2);
1809 }
1810 #endif // INCLUDE_CDS
1811 if (Signature::is_array(class_name)) {
1812 constraint_name->decrement_refcount();
1813 }
1814 return result;
1815 }
1816 }
1817
1818 // Add entry to resolution error table to record the error when the first
1819 // attempt to resolve a reference to a class has failed.
1820 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1821 Symbol* error, const char* message,
1822 Symbol* cause, const char* cause_msg) {
1823 {
1824 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1825 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1826 if (entry == nullptr) {
1827 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1828 }
1829 }
1830 }
1831
1832 // Delete a resolution error for RedefineClasses for a constant pool is going away
1833 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1834 ResolutionErrorTable::delete_entry(pool);
1835 }
1836
1837 // Lookup resolution error table. Returns error if found, otherwise null.
1838 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1839 const char** message,
1840 Symbol** cause, const char** cause_msg) {
1841
1842 {
1843 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1844 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1845 if (entry != nullptr) {
1846 *message = entry->message();
1847 *cause = entry->cause();
1848 *cause_msg = entry->cause_msg();
1849 return entry->error();
1850 } else {
1851 return nullptr;
1852 }
1853 }
1854 }
1855
1856 // Add an entry to resolution error table to record an error in resolving or
1857 // validating a nest host. This is used to construct informative error
1858 // messages when IllegalAccessError's occur. If an entry already exists it will
1859 // be updated with the nest host error message.
1860
1861 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1862 int which,
1863 const char* message) {
1864 {
1865 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1866 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1867 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1868 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1869 // still want to add the error message for the higher-level access checks to report. We should
1870 // only reach here under the same error condition, so we can ignore the potential race with setting
1871 // the message. If we see it is already set then we can ignore it.
1872 entry->set_nest_host_error(message);
1873 } else {
1874 ResolutionErrorTable::add_entry(pool, which, message);
1875 }
1876 }
1877 }
1878
1879 // Lookup any nest host error
1880 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1881 {
1882 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1883 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1884 if (entry != nullptr) {
1885 return entry->nest_host_error();
1886 } else {
1887 return nullptr;
1888 }
1889 }
1890 }
1891
1892 // Signature constraints ensure that callers and callees agree about
1893 // the meaning of type names in their signatures. This routine is the
1894 // intake for constraints. It collects them from several places:
1895 //
1896 // * LinkResolver::resolve_method (if check_access is true) requires
1897 // that the resolving class (the caller) and the defining class of
1898 // the resolved method (the callee) agree on each type in the
1899 // method's signature.
1900 //
1901 // * LinkResolver::resolve_interface_method performs exactly the same
1902 // checks.
1903 //
1904 // * LinkResolver::resolve_field requires that the constant pool
1905 // attempting to link to a field agree with the field's defining
1906 // class about the type of the field signature.
1907 //
1908 // * klassVtable::initialize_vtable requires that, when a class
1909 // overrides a vtable entry allocated by a superclass, that the
1910 // overriding method (i.e., the callee) agree with the superclass
1911 // on each type in the method's signature.
1912 //
1913 // * klassItable::initialize_itable requires that, when a class fills
1914 // in its itables, for each non-abstract method installed in an
1915 // itable, the method (i.e., the callee) agree with the interface
1916 // on each type in the method's signature.
1917 //
1918 // All those methods have a boolean (check_access, checkconstraints)
1919 // which turns off the checks. This is used from specialized contexts
1920 // such as bootstrapping, dumping, and debugging.
1921 //
1922 // No direct constraint is placed between the class and its
1923 // supertypes. Constraints are only placed along linked relations
1924 // between callers and callees. When a method overrides or implements
1925 // an abstract method in a supertype (superclass or interface), the
1926 // constraints are placed as if the supertype were the caller to the
1927 // overriding method. (This works well, since callers to the
1928 // supertype have already established agreement between themselves and
1929 // the supertype.) As a result of all this, a class can disagree with
1930 // its supertype about the meaning of a type name, as long as that
1931 // class neither calls a relevant method of the supertype, nor is
1932 // called (perhaps via an override) from the supertype.
1933 //
1934 //
1935 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1936 //
1937 // Make sure all class components (including arrays) in the given
1938 // signature will be resolved to the same class in both loaders.
1939 // Returns the name of the type that failed a loader constraint check, or
1940 // null if no constraint failed. No exception except OOME is thrown.
1941 // Arrays are not added to the loader constraint table, their elements are.
1942 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1943 Klass* klass_being_linked,
1944 Handle loader1, Handle loader2,
1945 bool is_method) {
1946 // Nothing to do if loaders are the same.
1947 if (loader1() == loader2()) {
1948 return nullptr;
1949 }
1950
1951 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
1952 if (ss.is_reference()) {
1953 Symbol* sig = ss.as_symbol();
1954 // Note: In the future, if template-like types can take
1955 // arguments, we will want to recognize them and dig out class
1956 // names hiding inside the argument lists.
1957 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
1958 return sig;
1959 }
1960 }
1961 }
1962 return nullptr;
1963 }
1964
1965 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
1966 Symbol* signature,
1967 TRAPS) {
1968
1969 const int iid_as_int = vmIntrinsics::as_int(iid);
1970 assert(MethodHandles::is_signature_polymorphic(iid) &&
1971 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
1972 iid != vmIntrinsics::_invokeGeneric,
1973 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
1974
1975 InvokeMethodKey key(signature, iid_as_int);
1976 Method** met = nullptr;
1977
1978 // We only want one entry in the table for this (signature/id, method) pair but the code
1979 // to create the intrinsic method needs to be outside the lock.
1980 // The first thread claims the entry by adding the key and the other threads wait, until the
1981 // Method has been added as the value.
1982 {
1983 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1984 while (true) {
1985 bool created;
1986 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
1987 assert(met != nullptr, "either created or found");
1988 if (*met != nullptr) {
1989 return *met;
1990 } else if (created) {
1991 // The current thread won the race and will try to create the full entry.
1992 break;
1993 } else {
1994 // Another thread beat us to it, so wait for them to complete
1995 // and return *met; or if they hit an error we get another try.
1996 ml.wait();
1997 // Note it is not safe to read *met here as that entry could have
1998 // been deleted, so we must loop and try put_if_absent again.
1999 }
2000 }
2001 }
2002
2003 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
2004 bool throw_error = HAS_PENDING_EXCEPTION;
2005 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
2006 // Generate a compiled form of the MH intrinsic
2007 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2008 AdapterHandlerLibrary::create_native_wrapper(m);
2009 // Check if have the compiled code.
2010 throw_error = (!m->has_compiled_code());
2011 }
2012
2013 {
2014 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2015 if (throw_error) {
2016 // Remove the entry and let another thread try, or get the same exception.
2017 bool removed = _invoke_method_intrinsic_table->remove(key);
2018 assert(removed, "must be the owner");
2019 ml.notify_all();
2020 } else {
2021 signature->make_permanent(); // The signature is never unloaded.
2022 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2023 m->code()->entry_point() == m->from_compiled_entry()),
2024 "MH intrinsic invariant");
2025 *met = m(); // insert the element
2026 ml.notify_all();
2027 return m();
2028 }
2029 }
2030
2031 // Throw OOM or the pending exception in the JavaThread
2032 if (throw_error && !HAS_PENDING_EXCEPTION) {
2033 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2034 "Out of space in CodeCache for method handle intrinsic");
2035 }
2036 return nullptr;
2037 }
2038
2039 #if INCLUDE_CDS
2040 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) {
2041 assert(SafepointSynchronize::is_at_safepoint(), "must be");
2042 auto do_method = [&] (InvokeMethodKey& key, Method*& m) {
2043 methods->append(m);
2044 };
2045 _invoke_method_intrinsic_table->iterate_all(do_method);
2046 }
2047
2048 void SystemDictionary::restore_archived_method_handle_intrinsics() {
2049 if (UseSharedSpaces) {
2050 EXCEPTION_MARK;
2051 restore_archived_method_handle_intrinsics_impl(THREAD);
2052 if (HAS_PENDING_EXCEPTION) {
2053 // This is probably caused by OOM -- other parts of the CDS archive have direct pointers to
2054 // the archived method handle intrinsics, so we can't really recover from this failure.
2055 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics. Try to increase heap size."));
2056 }
2057 }
2058 }
2059
2060 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) {
2061 Array<Method*>* list = AOTMetaspace::archived_method_handle_intrinsics();
2062 for (int i = 0; i < list->length(); i++) {
2063 methodHandle m(THREAD, list->at(i));
2064 Method::restore_archived_method_handle_intrinsic(m, CHECK);
2065 m->constants()->restore_unshareable_info(CHECK);
2066 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) {
2067 AdapterHandlerLibrary::create_native_wrapper(m);
2068 if (!m->has_compiled_code()) {
2069 ResourceMark rm(THREAD);
2070 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name()));
2071 }
2072 }
2073
2074 // There's no need to grab the InvokeMethodIntrinsicTable_lock, as we are still very early in
2075 // VM start-up -- in init_globals2() -- so we are still running a single Java thread. It's not
2076 // possible to have a contention.
2077 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id());
2078 InvokeMethodKey key(m->signature(), iid_as_int);
2079 bool created = _invoke_method_intrinsic_table->put(key, m());
2080 assert(created, "unexpected contention");
2081 }
2082 }
2083 #endif // INCLUDE_CDS
2084
2085 // Helper for unpacking the return value from linkMethod and linkCallSite.
2086 static Method* unpack_method_and_appendix(Handle mname,
2087 Klass* accessing_klass,
2088 objArrayHandle appendix_box,
2089 Handle* appendix_result,
2090 TRAPS) {
2091 if (mname.not_null()) {
2092 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2093 if (m != nullptr) {
2094 oop appendix = appendix_box->obj_at(0);
2095 LogTarget(Info, methodhandles) lt;
2096 if (lt.develop_is_enabled()) {
2097 ResourceMark rm(THREAD);
2098 LogStream ls(lt);
2099 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2100 m->print_on(&ls);
2101 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2102 ls.cr();
2103 }
2104
2105 (*appendix_result) = Handle(THREAD, appendix);
2106 // the target is stored in the cpCache and if a reference to this
2107 // MemberName is dropped we need a way to make sure the
2108 // class_loader containing this method is kept alive.
2109 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2110 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2111 this_key->record_dependency(m->method_holder());
2112 return mh();
2113 }
2114 }
2115 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2116 }
2117
2118 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2119 Symbol* name,
2120 Symbol* signature,
2121 Klass* accessing_klass,
2122 Handle* appendix_result,
2123 TRAPS) {
2124 guarantee(THREAD->can_call_java(), "");
2125 Handle method_type =
2126 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2127
2128 int ref_kind = JVM_REF_invokeVirtual;
2129 oop name_oop = StringTable::intern(name, CHECK_NULL);
2130 Handle name_str (THREAD, name_oop);
2131 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2132 assert(appendix_box->obj_at(0) == nullptr, "");
2133
2134 // This should not happen. JDK code should take care of that.
2135 if (accessing_klass == nullptr || method_type.is_null()) {
2136 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2137 }
2138
2139 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2140 JavaCallArguments args;
2141 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2142 args.push_int(ref_kind);
2143 args.push_oop(Handle(THREAD, klass->java_mirror()));
2144 args.push_oop(name_str);
2145 args.push_oop(method_type);
2146 args.push_oop(appendix_box);
2147 JavaValue result(T_OBJECT);
2148 JavaCalls::call_static(&result,
2149 vmClasses::MethodHandleNatives_klass(),
2150 vmSymbols::linkMethod_name(),
2151 vmSymbols::linkMethod_signature(),
2152 &args, CHECK_NULL);
2153 Handle mname(THREAD, result.get_oop());
2154 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2155 }
2156
2157 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2158 // We must ensure that all class loaders everywhere will reach this class, for any client.
2159 // This is a safe bet for public classes in java.lang, such as Object and String.
2160 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2161 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2162 static bool is_always_visible_class(oop mirror) {
2163 Klass* klass = java_lang_Class::as_Klass(mirror);
2164 if (klass->is_objArray_klass()) {
2165 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2166 }
2167 if (klass->is_typeArray_klass()) {
2168 return true; // primitive array
2169 }
2170 assert(klass->is_instance_klass(), "%s", klass->external_name());
2171 return klass->is_public() &&
2172 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2173 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2174 }
2175
2176 // Find or construct the Java mirror (java.lang.Class instance) for
2177 // the given field type signature, as interpreted relative to the
2178 // given class loader. Handles primitives, void, references, arrays,
2179 // and all other reflectable types, except method types.
2180 // N.B. Code in reflection should use this entry point.
2181 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2182 Klass* accessing_klass,
2183 SignatureStream::FailureMode failure_mode,
2184 TRAPS) {
2185
2186 Handle class_loader;
2187
2188 // What we have here must be a valid field descriptor,
2189 // and all valid field descriptors are supported.
2190 // Produce the same java.lang.Class that reflection reports.
2191 if (accessing_klass != nullptr) {
2192 class_loader = Handle(THREAD, accessing_klass->class_loader());
2193 }
2194 ResolvingSignatureStream ss(signature, class_loader, false);
2195 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2196 if (mirror_oop == nullptr) {
2197 return Handle(); // report failure this way
2198 }
2199 Handle mirror(THREAD, mirror_oop);
2200
2201 if (accessing_klass != nullptr) {
2202 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2203 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2204 if (sel_klass != nullptr) {
2205 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2206 }
2207 }
2208 return mirror;
2209 }
2210
2211
2212 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2213 // signature, as interpreted relative to the given class loader.
2214 // Because of class loader constraints, all method handle usage must be
2215 // consistent with this loader.
2216 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2217 Klass* accessing_klass,
2218 TRAPS) {
2219 Handle empty;
2220 OopHandle* o;
2221 {
2222 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2223 o = _invoke_method_type_table->get(signature);
2224 }
2225
2226 if (o != nullptr) {
2227 oop mt = o->resolve();
2228 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2229 return Handle(THREAD, mt);
2230 } else if (!THREAD->can_call_java()) {
2231 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2232 return Handle(); // do not attempt from within compiler, unless it was cached
2233 }
2234
2235 Handle class_loader;
2236 if (accessing_klass != nullptr) {
2237 class_loader = Handle(THREAD, accessing_klass->class_loader());
2238 }
2239 bool can_be_cached = true;
2240 int npts = ArgumentCount(signature).size();
2241 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2242 int arg = 0;
2243 Handle rt; // the return type from the signature
2244 ResourceMark rm(THREAD);
2245 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2246 oop mirror = nullptr;
2247 if (can_be_cached) {
2248 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2249 mirror = ss.as_java_mirror(Handle(), SignatureStream::ReturnNull, CHECK_(empty));
2250 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2251 // Fall back to accessing_klass context.
2252 can_be_cached = false;
2253 }
2254 }
2255 if (!can_be_cached) {
2256 // Resolve, throwing a real error if it doesn't work.
2257 mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2258 }
2259 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2260 if (ss.at_return_type())
2261 rt = Handle(THREAD, mirror);
2262 else
2263 pts->obj_at_put(arg++, mirror);
2264
2265 // Check accessibility.
2266 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2267 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2268 mirror = nullptr; // safety
2269 // Emulate ConstantPool::verify_constant_pool_resolve.
2270 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2271 }
2272 }
2273 assert(arg == npts, "");
2274
2275 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2276 JavaCallArguments args(Handle(THREAD, rt()));
2277 args.push_oop(pts);
2278 JavaValue result(T_OBJECT);
2279 JavaCalls::call_static(&result,
2280 vmClasses::MethodHandleNatives_klass(),
2281 vmSymbols::findMethodHandleType_name(),
2282 vmSymbols::findMethodHandleType_signature(),
2283 &args, CHECK_(empty));
2284 Handle method_type(THREAD, result.get_oop());
2285
2286 if (can_be_cached) {
2287 // We can cache this MethodType inside the JVM.
2288 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2289 bool created = false;
2290 assert(method_type != nullptr, "unexpected null");
2291 OopHandle* h = _invoke_method_type_table->get(signature);
2292 if (h == nullptr) {
2293 signature->make_permanent(); // The signature is never unloaded.
2294 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2295 bool created = _invoke_method_type_table->put(signature, elem);
2296 assert(created, "better be created");
2297 }
2298 }
2299 // report back to the caller with the MethodType
2300 return method_type;
2301 }
2302
2303 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2304 Klass* accessing_klass,
2305 TRAPS) {
2306 Handle empty;
2307 ResourceMark rm(THREAD);
2308 SignatureStream ss(signature, /*is_method=*/ false);
2309 if (!ss.is_done()) {
2310 Handle class_loader;
2311 if (accessing_klass != nullptr) {
2312 class_loader = Handle(THREAD, accessing_klass->class_loader());
2313 }
2314 oop mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2315 ss.next();
2316 if (ss.is_done()) {
2317 return Handle(THREAD, mirror);
2318 }
2319 }
2320 return empty;
2321 }
2322
2323 // Ask Java code to find or construct a method handle constant.
2324 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2325 int ref_kind, //e.g., JVM_REF_invokeVirtual
2326 Klass* callee,
2327 Symbol* name,
2328 Symbol* signature,
2329 TRAPS) {
2330 Handle empty;
2331 if (caller == nullptr) {
2332 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2333 }
2334 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2335 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2336
2337 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2338 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2339 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2340 java_lang_invoke_MemberName::set_name (mname(), name_str());
2341 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2342 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2343
2344 if (ref_kind == JVM_REF_invokeVirtual &&
2345 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2346 // Skip resolution for public signature polymorphic methods such as
2347 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2348 // They require appendix argument which MemberName resolution doesn't handle.
2349 // There's special logic on JDK side to handle them
2350 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2351 } else {
2352 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2353 }
2354
2355 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2356 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2357
2358 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2359 JavaCallArguments args;
2360 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2361 args.push_int(ref_kind);
2362 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2363 args.push_oop(name_str);
2364 args.push_oop(type);
2365 JavaValue result(T_OBJECT);
2366 JavaCalls::call_static(&result,
2367 vmClasses::MethodHandleNatives_klass(),
2368 vmSymbols::linkMethodHandleConstant_name(),
2369 vmSymbols::linkMethodHandleConstant_signature(),
2370 &args, CHECK_(empty));
2371 return Handle(THREAD, result.get_oop());
2372 }
2373
2374 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2375 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2376 // with linkage results being stored back into the bootstrap specifier.
2377 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2378 // Resolve the bootstrap specifier, its name, type, and static arguments
2379 bootstrap_specifier.resolve_bsm(CHECK);
2380
2381 // This should not happen. JDK code should take care of that.
2382 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2383 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2384 }
2385
2386 bool is_indy = bootstrap_specifier.is_method_call();
2387 objArrayHandle appendix_box;
2388 if (is_indy) {
2389 // Some method calls may require an appendix argument. Arrange to receive it.
2390 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2391 assert(appendix_box->obj_at(0) == nullptr, "");
2392 }
2393
2394 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2395 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2396 JavaCallArguments args;
2397 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2398 args.push_oop(bootstrap_specifier.bsm());
2399 args.push_oop(bootstrap_specifier.name_arg());
2400 args.push_oop(bootstrap_specifier.type_arg());
2401 args.push_oop(bootstrap_specifier.arg_values());
2402 if (is_indy) {
2403 args.push_oop(appendix_box);
2404 }
2405 JavaValue result(T_OBJECT);
2406 JavaCalls::call_static(&result,
2407 vmClasses::MethodHandleNatives_klass(),
2408 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2409 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2410 &args, CHECK);
2411
2412 Handle value(THREAD, result.get_oop());
2413 if (is_indy) {
2414 Handle appendix;
2415 Method* method = unpack_method_and_appendix(value,
2416 bootstrap_specifier.caller(),
2417 appendix_box,
2418 &appendix, CHECK);
2419 methodHandle mh(THREAD, method);
2420 bootstrap_specifier.set_resolved_method(mh, appendix);
2421 } else {
2422 bootstrap_specifier.set_resolved_value(value);
2423 }
2424
2425 // sanity check
2426 assert(bootstrap_specifier.is_resolved() ||
2427 (bootstrap_specifier.is_method_call() &&
2428 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2429 }
2430
2431
2432 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2433 assert(m != nullptr, "Unexpected nullptr Method*");
2434 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2435 }
2436
2437 // ----------------------------------------------------------------------------
2438
2439 void SystemDictionary::print_on(outputStream *st) {
2440 CDS_ONLY(SystemDictionaryShared::print_on(st));
2441 GCMutexLocker mu(SystemDictionary_lock);
2442
2443 ClassLoaderDataGraph::print_dictionary(st);
2444
2445 // Placeholders
2446 PlaceholderTable::print_on(st);
2447 st->cr();
2448
2449 // loader constraints - print under SD_lock
2450 LoaderConstraintTable::print_on(st);
2451 st->cr();
2452 }
2453
2454 void SystemDictionary::print() { print_on(tty); }
2455
2456 void SystemDictionary::verify() {
2457
2458 GCMutexLocker mu(SystemDictionary_lock);
2459
2460 // Verify dictionary
2461 ClassLoaderDataGraph::verify_dictionary();
2462
2463 // Verify constraint table
2464 LoaderConstraintTable::verify();
2465 }
2466
2467 void SystemDictionary::dump(outputStream *st, bool verbose) {
2468 assert_locked_or_safepoint(SystemDictionary_lock);
2469 if (verbose) {
2470 print_on(st);
2471 } else {
2472 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2473 ClassLoaderDataGraph::print_table_statistics(st);
2474 LoaderConstraintTable::print_table_statistics(st);
2475 }
2476 }
2477
2478 // Utility for dumping dictionaries.
2479 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2480 DCmdWithParser(output, heap),
2481 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2482 "BOOLEAN", false, "false") {
2483 _dcmdparser.add_dcmd_option(&_verbose);
2484 }
2485
2486 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2487 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2488 _verbose.value());
2489 VMThread::execute(&dumper);
2490 }