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