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