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/fieldStreams.inline.hpp"
59 #include "oops/instanceKlass.hpp"
60 #include "oops/klass.inline.hpp"
61 #include "oops/method.inline.hpp"
62 #include "oops/objArrayKlass.hpp"
63 #include "oops/objArrayOop.inline.hpp"
64 #include "oops/oop.inline.hpp"
65 #include "oops/oop.hpp"
66 #include "oops/oopHandle.hpp"
67 #include "oops/oopHandle.inline.hpp"
68 #include "oops/symbol.hpp"
69 #include "oops/typeArrayKlass.hpp"
70 #include "oops/inlineKlass.inline.hpp"
71 #include "prims/jvmtiExport.hpp"
72 #include "prims/methodHandles.hpp"
73 #include "runtime/arguments.hpp"
74 #include "runtime/atomic.hpp"
75 #include "runtime/handles.inline.hpp"
76 #include "runtime/java.hpp"
77 #include "runtime/javaCalls.hpp"
78 #include "runtime/mutexLocker.hpp"
79 #include "runtime/os.hpp"
80 #include "runtime/sharedRuntime.hpp"
81 #include "runtime/signature.hpp"
82 #include "runtime/synchronizer.hpp"
83 #include "services/classLoadingService.hpp"
84 #include "services/diagnosticCommand.hpp"
85 #include "services/finalizerService.hpp"
86 #include "services/threadService.hpp"
87 #include "utilities/growableArray.hpp"
88 #include "utilities/macros.hpp"
89 #include "utilities/utf8.hpp"
90 #if INCLUDE_CDS
91 #include "classfile/systemDictionaryShared.hpp"
92 #endif
93 #if INCLUDE_JFR
94 #include "jfr/jfr.hpp"
95 #endif
96
97 class InvokeMethodKey : public StackObj {
98 private:
99 Symbol* _symbol;
100 intptr_t _iid;
101
102 public:
103 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
104 _symbol(symbol),
105 _iid(iid) {}
106
107 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
108 return k1._symbol == k2._symbol && k1._iid == k2._iid;
109 }
110
111 static unsigned int compute_hash(const InvokeMethodKey &k) {
112 Symbol* sym = k._symbol;
113 intptr_t iid = k._iid;
114 unsigned int hash = (unsigned int) sym -> identity_hash();
115 return (unsigned int) (hash ^ iid);
116 }
117
118 };
119
120 using InvokeMethodIntrinsicTable = ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
121 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
122 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
123 using InvokeMethodTypeTable = ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
124 static InvokeMethodTypeTable* _invoke_method_type_table;
125
126 OopHandle SystemDictionary::_java_system_loader;
127 OopHandle SystemDictionary::_java_platform_loader;
128
129 // ----------------------------------------------------------------------------
130 // Java-level SystemLoader and PlatformLoader
131 oop SystemDictionary::java_system_loader() {
132 return _java_system_loader.resolve();
133 }
134
135 oop SystemDictionary::java_platform_loader() {
136 return _java_platform_loader.resolve();
137 }
138
139 void SystemDictionary::compute_java_loaders(TRAPS) {
140 if (_java_platform_loader.is_empty()) {
141 oop platform_loader = get_platform_class_loader_impl(CHECK);
142 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
143 } else {
144 // It must have been restored from the archived module graph
145 assert(CDSConfig::is_using_archive(), "must be");
146 assert(CDSConfig::is_using_full_module_graph(), "must be");
147 DEBUG_ONLY(
148 oop platform_loader = get_platform_class_loader_impl(CHECK);
149 assert(_java_platform_loader.resolve() == platform_loader, "must be");
150 )
151 }
152
153 if (_java_system_loader.is_empty()) {
154 oop system_loader = get_system_class_loader_impl(CHECK);
155 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
156 } else {
157 // It must have been restored from the archived module graph
158 assert(CDSConfig::is_using_archive(), "must be");
159 assert(CDSConfig::is_using_full_module_graph(), "must be");
160 DEBUG_ONLY(
161 oop system_loader = get_system_class_loader_impl(CHECK);
162 assert(_java_system_loader.resolve() == system_loader, "must be");
163 )
164 }
165 }
166
167 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
168 JavaValue result(T_OBJECT);
169 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
170 JavaCalls::call_static(&result,
171 class_loader_klass,
172 vmSymbols::getSystemClassLoader_name(),
173 vmSymbols::void_classloader_signature(),
174 CHECK_NULL);
175 return result.get_oop();
176 }
177
178 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
179 JavaValue result(T_OBJECT);
180 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
181 JavaCalls::call_static(&result,
182 class_loader_klass,
183 vmSymbols::getPlatformClassLoader_name(),
184 vmSymbols::void_classloader_signature(),
185 CHECK_NULL);
186 return result.get_oop();
187 }
188
189 // Helper function
190 inline ClassLoaderData* class_loader_data(Handle class_loader) {
191 return ClassLoaderData::class_loader_data(class_loader());
192 }
193
194 static void add_wrapper_class(JavaThread* current, ClassLoaderData* cld, Symbol* classname) {
195 InstanceKlass* ik = SystemDictionary::find_instance_klass(current, classname, Handle(current, nullptr));
196 assert(ik != nullptr, "Must exist");
197 SystemDictionary::add_to_initiating_loader(current, ik, cld);
198 }
199
200 static void add_wrapper_classes(ClassLoaderData* cld) {
201 MonitorLocker mu1(SystemDictionary_lock);
202 JavaThread* current = JavaThread::current();
203 add_wrapper_class(current, cld, vmSymbols::java_lang_Boolean());
204 add_wrapper_class(current, cld, vmSymbols::java_lang_Byte());
205 add_wrapper_class(current, cld, vmSymbols::java_lang_Character());
206 add_wrapper_class(current, cld, vmSymbols::java_lang_Short());
207 add_wrapper_class(current, cld, vmSymbols::java_lang_Integer());
208 add_wrapper_class(current, cld, vmSymbols::java_lang_Long());
209 add_wrapper_class(current, cld, vmSymbols::java_lang_Float());
210 add_wrapper_class(current, cld, vmSymbols::java_lang_Double());
211 }
212
213 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
214 if (create_mirror_cld) {
215 // Add a new class loader data to the graph.
216 return ClassLoaderDataGraph::add(class_loader, true);
217 } else {
218 if (class_loader() == nullptr) {
219 return ClassLoaderData::the_null_class_loader_data();
220 } else {
221 ClassLoaderData* cld = ClassLoaderDataGraph::find_or_create(class_loader);
222 add_wrapper_classes(cld);
223 return cld;
224 }
225 }
226 }
227
228 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
229 assert(_java_system_loader.is_empty(), "already set!");
230 _java_system_loader = cld->class_loader_handle();
231
232 }
233
234 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
235 assert(_java_platform_loader.is_empty(), "already set!");
236 _java_platform_loader = cld->class_loader_handle();
237 }
238
239 // ----------------------------------------------------------------------------
240 // Parallel class loading check
241
242 static bool is_parallelCapable(Handle class_loader) {
243 if (class_loader.is_null()) return true;
244 return java_lang_ClassLoader::parallelCapable(class_loader());
245 }
246 // ----------------------------------------------------------------------------
247 // ParallelDefineClass flag does not apply to bootclass loader
248 static bool is_parallelDefine(Handle class_loader) {
249 if (class_loader.is_null()) return false;
250 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
251 return true;
252 }
253 return false;
254 }
255
256 // Returns true if the passed class loader is the builtin application class loader
257 // or a custom system class loader. A customer system class loader can be
258 // specified via -Djava.system.class.loader.
259 bool SystemDictionary::is_system_class_loader(oop class_loader) {
260 if (class_loader == nullptr) {
261 return false;
262 }
263 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
264 class_loader == _java_system_loader.peek());
265 }
266
267 // Returns true if the passed class loader is the platform class loader.
268 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
269 if (class_loader == nullptr) {
270 return false;
271 }
272 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
273 }
274
275 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
276 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
277 if (is_parallelCapable(class_loader)) {
278 return Handle();
279 } else {
280 return class_loader;
281 }
282 }
283
284 // ----------------------------------------------------------------------------
285 // Resolving of classes
286
287 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
288 if (name == nullptr) {
289 THROW_MSG_NULL(exception, "No class name given");
290 }
291 size_t name_len = strlen(name);
292 if (name_len > static_cast<size_t>(Symbol::max_length())) {
293 // It's impossible to create this class; the name cannot fit
294 // into the constant pool. If necessary report an abridged name
295 // in the exception message.
296 if (name_len > static_cast<size_t>(MaxStringPrintSize)) {
297 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
298 "Class name exceeds maximum length of %d: %.*s ... (%zu characters omitted) ... %.*s",
299 Symbol::max_length(),
300 MaxStringPrintSize / 2,
301 name,
302 name_len - 2 * (MaxStringPrintSize / 2), // allows for odd value
303 MaxStringPrintSize / 2,
304 name + name_len - MaxStringPrintSize / 2);
305 }
306 else {
307 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
308 "Class name exceeds maximum length of %d: %s",
309 Symbol::max_length(),
310 name);
311 }
312 return nullptr;
313 }
314 // Callers should ensure that the name is never an illegal UTF8 string.
315 assert(UTF8::is_legal_utf8((const unsigned char*)name, name_len, false),
316 "Class name is not a valid utf8 string.");
317
318 // Make a new symbol for the class name.
319 return SymbolTable::new_symbol(name);
320 }
321
322 #ifdef ASSERT
323 // Used to verify that class loading succeeded in adding k to the dictionary.
324 static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
325 MutexLocker mu(SystemDictionary_lock);
326 ClassLoaderData* loader_data = k->class_loader_data();
327 Dictionary* dictionary = loader_data->dictionary();
328 assert(class_name == k->name(), "Must be the same");
329 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
330 assert(kk == k, "should be present in dictionary");
331 }
332 #endif
333
334 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
335 if (HAS_PENDING_EXCEPTION) {
336 // If we have a pending exception we forward it to the caller, unless throw_error is true,
337 // in which case we have to check whether the pending exception is a ClassNotFoundException,
338 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
339 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
340 ResourceMark rm(THREAD);
341 Handle e(THREAD, PENDING_EXCEPTION);
342 CLEAR_PENDING_EXCEPTION;
343 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
344 } else {
345 return; // the caller will throw the incoming exception
346 }
347 }
348 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
349 // error or exception depending on the value of throw_error.
350 ResourceMark rm(THREAD);
351 if (throw_error) {
352 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
353 } else {
354 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
355 }
356 }
357
358 // Forwards to resolve_or_null
359
360 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader,
361 bool throw_error, TRAPS) {
362 Klass* klass = resolve_or_null(class_name, class_loader, THREAD);
363 // Check for pending exception or null klass, and throw exception
364 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
365 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
366 }
367 return klass;
368 }
369
370 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
371
372 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, TRAPS) {
373 if (Signature::is_array(class_name)) {
374 return resolve_array_class_or_null(class_name, class_loader, THREAD);
375 } else {
376 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
377 if (Signature::has_envelope(class_name)) {
378 ResourceMark rm(THREAD);
379 // Ignore wrapping L and ; (and Q and ; for value types).
380 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
381 class_name->utf8_length() - 2);
382 return resolve_instance_class_or_null(name, class_loader, THREAD);
383 } else {
384 return resolve_instance_class_or_null(class_name, class_loader, THREAD);
385 }
386 }
387 }
388
389 // Forwards to resolve_instance_class_or_null
390
391 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
392 Handle class_loader,
393 TRAPS) {
394 assert(Signature::is_array(class_name), "must be array");
395 ResourceMark rm(THREAD);
396 SignatureStream ss(class_name, false);
397 int ndims = ss.skip_array_prefix(); // skip all '['s
398 Klass* k = nullptr;
399 BasicType t = ss.type();
400 if (ss.has_envelope()) {
401 Symbol* obj_class = ss.as_symbol();
402 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
403 class_loader,
404 CHECK_NULL);
405 if (k != nullptr) {
406 k = k->array_klass(ndims, CHECK_NULL);
407 }
408 } else {
409 k = Universe::typeArrayKlass(t);
410 k = k->array_klass(ndims, CHECK_NULL);
411 }
412 return k;
413 }
414
415 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
416 LogTarget(Debug, class, load, placeholders) lt;
417 if (lt.is_enabled()) {
418 ResourceMark rm;
419 LogStream ls(lt);
420 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
421 probe->print_on(&ls);
422 ls.cr();
423 }
424 }
425
426 // Must be called for any superclass or superinterface resolution
427 // during class definition to allow class circularity checking
428 // superinterface callers:
429 // parse_interfaces - from defineClass
430 // superclass callers:
431 // ClassFileParser - from defineClass
432 // load_shared_class - while loading a class from shared archive
433 // resolve_instance_class_or_null:
434 // via: handle_parallel_super_load
435 // when resolving a class that has an existing placeholder with
436 // a saved superclass [i.e. a defineClass is currently in progress]
437 // If another thread is trying to resolve the class, it must do
438 // superclass checks on its own thread to catch class circularity and
439 // to avoid deadlock.
440 //
441 // resolve_with_circularity_detection adds a DETECT_CIRCULARITY placeholder to the placeholder table before calling
442 // resolve_instance_class_or_null. ClassCircularityError is detected when a DETECT_CIRCULARITY or LOAD_INSTANCE
443 // placeholder for the same thread, class, classloader is found.
444 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
445 //
446 InstanceKlass* SystemDictionary::resolve_with_circularity_detection(Symbol* class_name,
447 Symbol* next_name,
448 Handle class_loader,
449 bool is_superclass,
450 TRAPS) {
451
452 assert(next_name != nullptr, "null superclass for resolving");
453 assert(!Signature::is_array(next_name), "invalid superclass name");
454
455 ClassLoaderData* loader_data = class_loader_data(class_loader);
456
457 if (is_superclass) {
458 InstanceKlass* klassk = loader_data->dictionary()->find_class(THREAD, class_name);
459 if (klassk != nullptr) {
460 // We can come here for two reasons:
461 // (a) RedefineClasses -- the class is already loaded
462 // (b) Rarely, the class might have been loaded by a parallel thread
463 // We can do a quick check against the already assigned superclass's name and loader.
464 InstanceKlass* superk = klassk->java_super();
465 if (superk != nullptr &&
466 superk->name() == next_name &&
467 superk->class_loader() == class_loader()) {
468 return superk;
469 }
470 }
471 }
472
473 // can't throw error holding a lock
474 bool throw_circularity_error = false;
475 {
476 MutexLocker mu(THREAD, SystemDictionary_lock);
477
478 // Must check ClassCircularity before resolving next_name (superclass or interface).
479 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
480 if (probe != nullptr && probe->check_seen_thread(THREAD, PlaceholderTable::DETECT_CIRCULARITY)) {
481 log_circularity_error(class_name, probe);
482 throw_circularity_error = true;
483 }
484
485 // Make sure there's a placeholder for the class_name before resolving.
486 // This is used as a claim that this thread is currently loading superclass/classloader
487 // and for ClassCircularity checks.
488 if (!throw_circularity_error) {
489 // Be careful not to exit resolve_with_circularity_detection without removing this placeholder.
490 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
491 loader_data,
492 PlaceholderTable::DETECT_CIRCULARITY,
493 next_name, THREAD);
494 }
495 }
496
497 if (throw_circularity_error) {
498 ResourceMark rm(THREAD);
499 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
500 }
501
502 // Resolve the superclass or superinterface, check results on return
503 InstanceKlass* superk =
504 SystemDictionary::resolve_instance_class_or_null(next_name,
505 class_loader,
506 THREAD);
507
508 // Clean up placeholder entry.
509 {
510 MutexLocker mu(THREAD, SystemDictionary_lock);
511 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::DETECT_CIRCULARITY, THREAD);
512 SystemDictionary_lock->notify_all();
513 }
514
515 // Check for pending exception or null superk, and throw exception
516 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
517 handle_resolution_exception(next_name, true, CHECK_NULL);
518 }
519
520 return superk;
521 }
522
523 // If the class in is in the placeholder table, class loading is in progress.
524 // For cases where the application changes threads to load classes, it
525 // is critical to ClassCircularity detection that we try loading
526 // the superclass on the new thread internally, so we do parallel
527 // superclass loading here. This avoids deadlock for ClassCircularity
528 // detection for parallelCapable class loaders that lock on a per-class lock.
529 static void handle_parallel_super_load(Symbol* name,
530 Symbol* superclassname,
531 Handle class_loader,
532 TRAPS) {
533
534 // The result superk is not used; resolve_with_circularity_detection is called for circularity check only.
535 // This passes false to is_superclass to skip doing the unlikely optimization.
536 Klass* superk = SystemDictionary::resolve_with_circularity_detection(name,
537 superclassname,
538 class_loader,
539 false,
540 CHECK);
541 }
542
543 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
544 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
545 static bool needs_load_placeholder(Handle class_loader) {
546 return class_loader.is_null() || !is_parallelCapable(class_loader);
547 }
548
549 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
550 static InstanceKlass* handle_parallel_loading(JavaThread* current,
551 Symbol* name,
552 ClassLoaderData* loader_data,
553 bool must_wait_for_class_loading,
554 bool* throw_circularity_error) {
555 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
556 if (oldprobe != nullptr) {
557 // -Xcomp calls load_signature_classes which might result in loading
558 // a class that's already in the process of loading, so we detect CCE here also.
559 // Only need check_seen_thread once, not on each loop
560 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
561 log_circularity_error(name, oldprobe);
562 *throw_circularity_error = true;
563 return nullptr;
564 } else if (must_wait_for_class_loading) {
565 // Wait until the first thread has finished loading this class. Also wait until all the
566 // threads trying to load its superclass have removed their placeholders.
567 while (oldprobe != nullptr &&
568 (oldprobe->instance_load_in_progress() || oldprobe->circularity_detection_in_progress())) {
569
570 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
571 // for the bootclass loader.
572 SystemDictionary_lock->wait();
573
574 // Check if classloading completed while we were waiting
575 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
576 if (check != nullptr) {
577 // Klass is already loaded, so just return it
578 return check;
579 }
580 // check if other thread failed to load and cleaned up
581 oldprobe = PlaceholderTable::get_entry(name, loader_data);
582 }
583 }
584 }
585 return nullptr;
586 }
587
588 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
589 assert(event != nullptr, "invariant");
590 assert(k != nullptr, "invariant");
591 event->set_loadedClass(k);
592 event->set_definingClassLoader(k->class_loader_data());
593 event->set_initiatingClassLoader(init_cld);
594 event->commit();
595 }
596
597 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
598 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
599 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
600 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
601 // This can return null, an exception or an InstanceKlass.
602 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
603 Handle class_loader,
604 TRAPS) {
605 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
606 DEBUG_ONLY(ResourceMark rm(THREAD));
607 assert(name != nullptr && !Signature::is_array(name) &&
608 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
609
610 EventClassLoad class_load_start_event;
611
612 HandleMark hm(THREAD);
613
614 ClassLoaderData* loader_data = register_loader(class_loader);
615 Dictionary* dictionary = loader_data->dictionary();
616
617 // Do lookup to see if class already exists.
618 InstanceKlass* probe = dictionary->find_class(THREAD, name);
619 if (probe != nullptr) return probe;
620
621 // Non-bootstrap class loaders will call out to class loader and
622 // define via jvm/jni_DefineClass which will acquire the
623 // class loader object lock to protect against multiple threads
624 // defining the class in parallel by accident.
625 // This lock must be acquired here so the waiter will find
626 // any successful result in the SystemDictionary and not attempt
627 // the define.
628 // ParallelCapable class loaders and the bootstrap classloader
629 // do not acquire lock here.
630 Handle lockObject = get_loader_lock_or_null(class_loader);
631 ObjectLocker ol(lockObject, THREAD);
632
633 bool circularity_detection_in_progress = false;
634 InstanceKlass* loaded_class = nullptr;
635 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
636
637 guarantee(THREAD->can_call_java(),
638 "can not load classes with compiler thread: class=%s, classloader=%s",
639 name->as_C_string(),
640 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
641
642 // Check again (after locking) if the class already exists in SystemDictionary
643 {
644 MutexLocker mu(THREAD, SystemDictionary_lock);
645 InstanceKlass* check = dictionary->find_class(THREAD, name);
646 if (check != nullptr) {
647 // InstanceKlass is already loaded, but we still need to check protection domain below.
648 loaded_class = check;
649 } else {
650 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
651 if (placeholder != nullptr && placeholder->circularity_detection_in_progress()) {
652 circularity_detection_in_progress = true;
653 superclassname = placeholder->next_klass_name();
654 assert(superclassname != nullptr, "superclass has to have a name");
655 }
656 }
657 }
658
659 // If the class is in the placeholder table with super_class set,
660 // handle superclass loading in progress.
661 if (circularity_detection_in_progress) {
662 handle_parallel_super_load(name, superclassname,
663 class_loader,
664 CHECK_NULL);
665 }
666
667 bool throw_circularity_error = false;
668 if (loaded_class == nullptr) {
669 bool load_placeholder_added = false;
670
671 // Add placeholder entry to record loading instance class
672 // case 1. Bootstrap classloader
673 // This classloader supports parallelism at the classloader level
674 // but only allows a single thread to load a class/classloader pair.
675 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
676 // case 2. parallelCapable user level classloaders
677 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
678 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
679 // case 3. traditional classloaders that rely on the classloader object lock
680 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
681 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
682 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
683 {
684 MutexLocker mu(THREAD, SystemDictionary_lock);
685 if (needs_load_placeholder(class_loader)) {
686 loaded_class = handle_parallel_loading(THREAD,
687 name,
688 loader_data,
689 class_loader.is_null(),
690 &throw_circularity_error);
691 }
692
693 // Recheck if the class has been loaded for all class loader cases and
694 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
695 if (!throw_circularity_error && loaded_class == nullptr) {
696 InstanceKlass* check = dictionary->find_class(THREAD, name);
697 if (check != nullptr) {
698 loaded_class = check;
699 } else if (needs_load_placeholder(class_loader)) {
700 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
701 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
702 PlaceholderTable::LOAD_INSTANCE,
703 nullptr,
704 THREAD);
705 load_placeholder_added = true;
706 }
707 }
708 }
709
710 // Must throw error outside of owning lock
711 if (throw_circularity_error) {
712 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
713 ResourceMark rm(THREAD);
714 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
715 }
716
717 // Be careful when modifying this code: once you have run
718 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
719 // you need to find_and_remove it before returning.
720 // So be careful to not exit with a CHECK_ macro between these calls.
721
722 if (loaded_class == nullptr) {
723 // Do actual loading
724 loaded_class = load_instance_class(name, class_loader, THREAD);
725 }
726
727 if (load_placeholder_added) {
728 // clean up placeholder entries for LOAD_INSTANCE success or error
729 // This brackets the SystemDictionary updates for both defining
730 // and initiating loaders
731 MutexLocker mu(THREAD, SystemDictionary_lock);
732 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
733 SystemDictionary_lock->notify_all();
734 }
735 }
736
737 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
738 return nullptr;
739 }
740
741 if (class_load_start_event.should_commit()) {
742 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
743 }
744
745 // Make sure we have the right class in the dictionary
746 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
747
748 return loaded_class;
749 }
750
751
752 // This routine does not lock the system dictionary.
753 //
754 // Since readers don't hold a lock, we must make sure that system
755 // dictionary entries are added to in a safe way (all links must
756 // be updated in an MT-safe manner). All entries are removed during class
757 // unloading, when this class loader is no longer referenced.
758 //
759 // Callers should be aware that an entry could be added just after
760 // Dictionary is read here, so the caller will not see
761 // the new entry.
762
763 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
764 Symbol* class_name,
765 Handle class_loader) {
766
767 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
768 if (loader_data == nullptr) {
769 // If the ClassLoaderData has not been setup,
770 // then the class loader has no entries in the dictionary.
771 return nullptr;
772 }
773
774 Dictionary* dictionary = loader_data->dictionary();
775 return dictionary->find_class(current, class_name);
776 }
777
778 // Look for a loaded instance or array klass by name. Do not do any loading.
779 // return null in case of error.
780 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
781 Symbol* class_name,
782 Handle class_loader) {
783 Klass* k = nullptr;
784 assert(class_name != nullptr, "class name must be non nullptr");
785
786 if (Signature::is_array(class_name)) {
787 // The name refers to an array. Parse the name.
788 // dimension and object_key in FieldArrayInfo are assigned as a
789 // side-effect of this call
790 SignatureStream ss(class_name, false);
791 int ndims = ss.skip_array_prefix(); // skip all '['s
792 BasicType t = ss.type();
793 if (t != T_OBJECT) {
794 k = Universe::typeArrayKlass(t);
795 } else {
796 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader);
797 }
798 if (k != nullptr) {
799 k = k->array_klass_or_null(ndims);
800 }
801 } else {
802 k = find_instance_klass(current, class_name, class_loader);
803 }
804 return k;
805 }
806
807 // Note: this method is much like resolve_class_from_stream, but
808 // does not publish the classes in the SystemDictionary.
809 // Handles Lookup.defineClass hidden.
810 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
811 ClassFileStream* st,
812 Symbol* class_name,
813 Handle class_loader,
814 const ClassLoadInfo& cl_info,
815 TRAPS) {
816
817 EventClassLoad class_load_start_event;
818 ClassLoaderData* loader_data;
819
820 // - for hidden classes that are not strong: create a new CLD that has a class holder and
821 // whose loader is the Lookup class's loader.
822 // - for hidden class: add the class to the Lookup class's loader's CLD.
823 assert (cl_info.is_hidden(), "only used for hidden classes");
824 bool create_mirror_cld = !cl_info.is_strong_hidden();
825 loader_data = register_loader(class_loader, create_mirror_cld);
826
827 assert(st != nullptr, "invariant");
828
829 // Parse stream and create a klass.
830 InstanceKlass* k = KlassFactory::create_from_stream(st,
831 class_name,
832 loader_data,
833 cl_info,
834 CHECK_NULL);
835 assert(k != nullptr, "no klass created");
836
837 // Hidden classes that are not strong must update ClassLoaderData holder
838 // so that they can be unloaded when the mirror is no longer referenced.
839 if (!cl_info.is_strong_hidden()) {
840 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
841 }
842
843 // Add to class hierarchy, and do possible deoptimizations.
844 k->add_to_hierarchy(THREAD);
845 // But, do not add to dictionary.
846
847 k->link_class(CHECK_NULL);
848
849 // notify jvmti
850 if (JvmtiExport::should_post_class_load()) {
851 JvmtiExport::post_class_load(THREAD, k);
852 }
853 if (class_load_start_event.should_commit()) {
854 post_class_load_event(&class_load_start_event, k, loader_data);
855 }
856
857 return k;
858 }
859
860 // Add a klass to the system from a stream (called by jni_DefineClass and
861 // JVM_DefineClass).
862 // Note: class_name can be null. In that case we do not know the name of
863 // the class until we have parsed the stream.
864 // This function either returns an InstanceKlass or throws an exception. It does
865 // not return null without a pending exception.
866 InstanceKlass* SystemDictionary::resolve_class_from_stream(
867 ClassFileStream* st,
868 Symbol* class_name,
869 Handle class_loader,
870 const ClassLoadInfo& cl_info,
871 TRAPS) {
872
873 HandleMark hm(THREAD);
874
875 ClassLoaderData* loader_data = register_loader(class_loader);
876
877 // Classloaders that support parallelism, e.g. bootstrap classloader,
878 // do not acquire lock here
879 Handle lockObject = get_loader_lock_or_null(class_loader);
880 ObjectLocker ol(lockObject, THREAD);
881
882 // Parse the stream and create a klass.
883 // Note that we do this even though this klass might
884 // already be present in the SystemDictionary, otherwise we would not
885 // throw potential ClassFormatErrors.
886 InstanceKlass* k = nullptr;
887
888 #if INCLUDE_CDS
889 if (!CDSConfig::is_dumping_static_archive()) {
890 k = SystemDictionaryShared::lookup_from_stream(class_name,
891 class_loader,
892 cl_info.protection_domain(),
893 st,
894 CHECK_NULL);
895 }
896 #endif
897
898 if (k == nullptr) {
899 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
900 }
901
902 assert(k != nullptr, "no klass created");
903 Symbol* h_name = k->name();
904 assert(class_name == nullptr || class_name == h_name, "name mismatch");
905
906 // Add class just loaded
907 // If a class loader supports parallel classloading, handle parallel define requests.
908 // find_or_define_instance_class may return a different InstanceKlass,
909 // in which case the old k would be deallocated
910 if (is_parallelCapable(class_loader)) {
911 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
912 } else {
913 define_instance_class(k, class_loader, THREAD);
914
915 // If defining the class throws an exception register 'k' for cleanup.
916 if (HAS_PENDING_EXCEPTION) {
917 assert(k != nullptr, "Must have an instance klass here!");
918 loader_data->add_to_deallocate_list(k);
919 return nullptr;
920 }
921 }
922
923 // Make sure we have an entry in the SystemDictionary on success
924 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
925
926 return k;
927 }
928
929 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
930 Symbol* class_name,
931 Handle class_loader,
932 const ClassLoadInfo& cl_info,
933 TRAPS) {
934 if (cl_info.is_hidden()) {
935 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
936 } else {
937 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
938 }
939 }
940
941
942 #if INCLUDE_CDS
943 // Check if a shared class can be loaded by the specific classloader.
944 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
945 InstanceKlass* ik,
946 PackageEntry* pkg_entry,
947 Handle class_loader) {
948 assert(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS");
949
950 // (1) Check if we are loading into the same loader as in dump time.
951
952 if (ik->is_shared_boot_class()) {
953 if (class_loader() != nullptr) {
954 return false;
955 }
956 } else if (ik->is_shared_platform_class()) {
957 if (class_loader() != java_platform_loader()) {
958 return false;
959 }
960 } else if (ik->is_shared_app_class()) {
961 if (class_loader() != java_system_loader()) {
962 return false;
963 }
964 } else {
965 // ik was loaded by a custom loader during dump time
966 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
967 return false;
968 } else {
969 return true;
970 }
971 }
972
973 // (2) Check if we are loading into the same module from the same location as in dump time.
974
975 if (CDSConfig::is_using_optimized_module_handling()) {
976 // Class visibility has not changed between dump time and run time, so a class
977 // that was visible (and thus archived) during dump time is always visible during runtime.
978 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
979 "visibility cannot change between dump time and runtime");
980 return true;
981 }
982 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
983 }
984
985 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
986 InstanceKlass* ik,
987 PackageEntry* pkg_entry,
988 Handle class_loader) {
989 int scp_index = ik->shared_classpath_index();
990 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
991 assert(scp_index >= 0, "must be");
992 const AOTClassLocation* cl = AOTClassLocationConfig::runtime()->class_location_at(scp_index);
993 if (!Universe::is_module_initialized()) {
994 assert(cl != nullptr, "must be");
995 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
996 // has restricted the classes can be loaded at this step to be only:
997 // [1] cs->is_modules_image(): classes in java.base, or,
998 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
999 assert(cl->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
1000 "only these classes can be loaded before the module system is initialized");
1001 assert(class_loader.is_null(), "sanity");
1002 return true;
1003 }
1004
1005 if (pkg_entry == nullptr) {
1006 // We might have looked up pkg_entry before the module system was initialized.
1007 // Need to reload it now.
1008 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1009 if (pkg_name != nullptr) {
1010 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1011 }
1012 }
1013
1014 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1015 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1016 bool was_archived_from_named_module = !cl->has_unnamed_module();
1017 bool visible;
1018
1019 if (was_archived_from_named_module) {
1020 if (should_be_in_named_module) {
1021 // Is the module loaded from the same location as during dump time?
1022 visible = mod_entry->shared_path_index() == scp_index;
1023 if (visible) {
1024 assert(!CDSConfig::module_patching_disables_cds(), "Cannot use CDS");
1025 }
1026 } else {
1027 // During dump time, this class was in a named module, but at run time, this class should be
1028 // in an unnamed module.
1029 visible = false;
1030 }
1031 } else {
1032 if (should_be_in_named_module) {
1033 // During dump time, this class was in an unnamed, but at run time, this class should be
1034 // in a named module.
1035 visible = false;
1036 } else {
1037 visible = true;
1038 }
1039 }
1040
1041 return visible;
1042 }
1043
1044 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1045 Handle class_loader, bool is_superclass, TRAPS) {
1046 assert(super_type->is_shared(), "must be");
1047
1048 // Quick check if the super type has been already loaded.
1049 // + Don't do it for unregistered classes -- they can be unloaded so
1050 // super_type->class_loader_data() could be stale.
1051 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1052 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {
1053 // Check if the superclass is loaded by the current class_loader
1054 Symbol* name = super_type->name();
1055 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader);
1056 if (check == super_type) {
1057 return true;
1058 }
1059 }
1060
1061 Klass *found = resolve_with_circularity_detection(klass->name(), super_type->name(),
1062 class_loader, is_superclass, CHECK_false);
1063 if (found == super_type) {
1064 return true;
1065 } else {
1066 // The dynamically resolved super type is not the same as the one we used during dump time,
1067 // so we cannot use the class.
1068 return false;
1069 }
1070 }
1071
1072 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader, TRAPS) {
1073 // Check the superclass and interfaces. They must be the same
1074 // as in dump time, because the layout of <ik> depends on
1075 // the specific layout of ik->super() and ik->local_interfaces().
1076 //
1077 // If unexpected superclass or interfaces are found, we cannot
1078 // load <ik> from the shared archive.
1079
1080 if (ik->super() != nullptr) {
1081 bool check_super = check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1082 class_loader, true,
1083 CHECK_false);
1084 if (!check_super) {
1085 return false;
1086 }
1087 }
1088
1089 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1090 int num_interfaces = interfaces->length();
1091 for (int index = 0; index < num_interfaces; index++) {
1092 bool check_interface = check_shared_class_super_type(ik, interfaces->at(index), class_loader, false,
1093 CHECK_false);
1094 if (!check_interface) {
1095 return false;
1096 }
1097 }
1098
1099 return true;
1100 }
1101
1102 // Pre-load class referred to in non-static null-free instance field. These fields trigger MANDATORY loading.
1103 // Some pre-loading does not fail fatally
1104 bool SystemDictionary::preload_from_null_free_field(InstanceKlass* ik, Handle class_loader, Symbol* sig, int field_index, TRAPS) {
1105 TempNewSymbol name = Signature::strip_envelope(sig);
1106 log_info(class, preload)("Preloading class %s during loading of shared class %s. "
1107 "Cause: a null-free non-static field is declared with this type",
1108 name->as_C_string(), ik->name()->as_C_string());
1109 InstanceKlass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name,
1110 class_loader, false, CHECK_false);
1111 if (HAS_PENDING_EXCEPTION) {
1112 log_warning(class, preload)("Preloading of class %s during loading of class %s "
1113 "(cause: null-free non-static field) failed: %s",
1114 name->as_C_string(), ik->name()->as_C_string(),
1115 PENDING_EXCEPTION->klass()->name()->as_C_string());
1116 return false; // Exception is still pending
1117 }
1118
1119 InstanceKlass* k = ik->get_inline_type_field_klass_or_null(field_index);
1120 if (real_k != k) {
1121 // oops, the app has substituted a different version of k! Does not fail fatally
1122 log_warning(class, preload)("Preloading of class %s during loading of shared class %s "
1123 "(cause: null-free non-static field) failed : "
1124 "app substituted a different version of %s",
1125 name->as_C_string(), ik->name()->as_C_string(),
1126 name->as_C_string());
1127 return false;
1128 }
1129 log_info(class, preload)("Preloading of class %s during loading of shared class %s "
1130 "(cause: null-free non-static field) succeeded",
1131 name->as_C_string(), ik->name()->as_C_string());
1132
1133 assert(real_k != nullptr, "Sanity check");
1134 InstanceKlass::check_can_be_annotated_with_NullRestricted(real_k, ik->name(), CHECK_false);
1135
1136 return true;
1137 }
1138
1139 // Tries to pre-load classes referred to in non-static nullable instance fields if they are found in the
1140 // loadable descriptors attribute. If loading fails, we can fail silently.
1141 void SystemDictionary::try_preload_from_loadable_descriptors(InstanceKlass* ik, Handle class_loader, Symbol* sig, int field_index, TRAPS) {
1142 TempNewSymbol name = Signature::strip_envelope(sig);
1143 if (name != ik->name() && ik->is_class_in_loadable_descriptors_attribute(sig)) {
1144 log_info(class, preload)("Preloading class %s during loading of shared class %s. "
1145 "Cause: field type in LoadableDescriptors attribute",
1146 name->as_C_string(), ik->name()->as_C_string());
1147 InstanceKlass* real_k = SystemDictionary::resolve_with_circularity_detection_or_fail(ik->name(), name,
1148 class_loader, false, THREAD);
1149 if (HAS_PENDING_EXCEPTION) {
1150 CLEAR_PENDING_EXCEPTION;
1151 }
1152
1153 InstanceKlass* k = ik->get_inline_type_field_klass_or_null(field_index);
1154 if (real_k != k) {
1155 // oops, the app has substituted a different version of k!
1156 log_warning(class, preload)("Preloading of class %s during loading of shared class %s "
1157 "(cause: field type in LoadableDescriptors attribute) failed : "
1158 "app substituted a different version of %s",
1159 name->as_C_string(), ik->name()->as_C_string(),
1160 k->name()->as_C_string());
1161 return;
1162 } else if (real_k != nullptr) {
1163 log_info(class, preload)("Preloading of class %s during loading of shared class %s "
1164 "(cause: field type in LoadableDescriptors attribute) succeeded",
1165 name->as_C_string(), ik->name()->as_C_string());
1166 }
1167 }
1168 }
1169
1170
1171 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1172 Handle class_loader,
1173 Handle protection_domain,
1174 const ClassFileStream *cfs,
1175 PackageEntry* pkg_entry,
1176 TRAPS) {
1177 assert(ik != nullptr, "sanity");
1178 assert(ik->is_shared(), "sanity");
1179 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1180 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1181 Symbol* class_name = ik->name();
1182
1183 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1184 ik->set_shared_loading_failed();
1185 return nullptr;
1186 }
1187
1188 bool check = check_shared_class_super_types(ik, class_loader, CHECK_NULL);
1189 if (!check) {
1190 ik->set_shared_loading_failed();
1191 return nullptr;
1192 }
1193
1194 if (ik->has_inline_type_fields()) {
1195 for (AllFieldStream fs(ik); !fs.done(); fs.next()) {
1196 if (fs.access_flags().is_static()) continue;
1197
1198 Symbol* sig = fs.signature();
1199 int field_index = fs.index();
1200
1201 if (fs.is_null_free_inline_type()) {
1202 // A false return means that the class didn't load for other reasons than an exception.
1203 bool check = preload_from_null_free_field(ik, class_loader, sig, field_index, CHECK_NULL);
1204 if (!check) {
1205 ik->set_shared_loading_failed();
1206 return nullptr;
1207 }
1208 } else if (Signature::has_envelope(sig)) {
1209 // Pending exceptions are cleared so we can fail silently
1210 try_preload_from_loadable_descriptors(ik, class_loader, sig, field_index, CHECK_NULL);
1211 }
1212 }
1213 }
1214
1215 InstanceKlass* new_ik = nullptr;
1216 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1217 // It will be skipped for shared VM hidden lambda proxy classes.
1218 if (!ik->is_hidden()) {
1219 new_ik = KlassFactory::check_shared_class_file_load_hook(
1220 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1221 }
1222 if (new_ik != nullptr) {
1223 // The class is changed by CFLH. Return the new class. The shared class is
1224 // not used.
1225 return new_ik;
1226 }
1227
1228 // Adjust methods to recover missing data. They need addresses for
1229 // interpreter entry points and their default native method address
1230 // must be reset.
1231
1232 // Shared classes are all currently loaded by either the bootstrap or
1233 // internal parallel class loaders, so this will never cause a deadlock
1234 // on a custom class loader lock.
1235 // Since this class is already locked with parallel capable class
1236 // loaders, including the bootstrap loader via the placeholder table,
1237 // this lock is currently a nop.
1238
1239 ClassLoaderData* loader_data = class_loader_data(class_loader);
1240 {
1241 HandleMark hm(THREAD);
1242 Handle lockObject = get_loader_lock_or_null(class_loader);
1243 ObjectLocker ol(lockObject, THREAD);
1244 // prohibited package check assumes all classes loaded from archive call
1245 // restore_unshareable_info which calls ik->set_package()
1246 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1247 }
1248
1249 load_shared_class_misc(ik, loader_data);
1250
1251 return ik;
1252 }
1253
1254 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1255 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1256
1257 // For boot loader, ensure that GetSystemPackage knows that a class in this
1258 // package was loaded.
1259 if (loader_data->is_the_null_class_loader_data()) {
1260 s2 path_index = ik->shared_classpath_index();
1261 ik->set_classpath_index(path_index);
1262 }
1263
1264 // notify a class loaded from shared object
1265 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1266
1267 if (CDSConfig::is_dumping_final_static_archive()) {
1268 SystemDictionaryShared::init_dumptime_info_from_preimage(ik);
1269 }
1270 }
1271
1272 #endif // INCLUDE_CDS
1273
1274 InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {
1275
1276 if (class_loader.is_null()) {
1277 ResourceMark rm(THREAD);
1278 PackageEntry* pkg_entry = nullptr;
1279 bool search_only_bootloader_append = false;
1280
1281 // Find the package in the boot loader's package entry table.
1282 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1283 if (pkg_name != nullptr) {
1284 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1285 }
1286
1287 // Prior to attempting to load the class, enforce the boot loader's
1288 // visibility boundaries.
1289 if (!Universe::is_module_initialized()) {
1290 // During bootstrapping, prior to module initialization, any
1291 // class attempting to be loaded must be checked against the
1292 // java.base packages in the boot loader's PackageEntryTable.
1293 // No class outside of java.base is allowed to be loaded during
1294 // this bootstrapping window.
1295 if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1296 // Class is either in the unnamed package or in
1297 // a named package within the unnamed module. Either
1298 // case is outside of java.base, do not attempt to
1299 // load the class post java.base definition. If
1300 // java.base has not been defined, let the class load
1301 // and its package will be checked later by
1302 // ModuleEntryTable::verify_javabase_packages.
1303 if (ModuleEntryTable::javabase_defined()) {
1304 return nullptr;
1305 }
1306 } else {
1307 // Check that the class' package is defined within java.base.
1308 ModuleEntry* mod_entry = pkg_entry->module();
1309 Symbol* mod_entry_name = mod_entry->name();
1310 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1311 return nullptr;
1312 }
1313 }
1314 } else {
1315 // After the module system has been initialized, check if the class'
1316 // package is in a module defined to the boot loader.
1317 if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {
1318 // Class is either in the unnamed package, in a named package
1319 // within a module not defined to the boot loader or in a
1320 // a named package within the unnamed module. In all cases,
1321 // limit visibility to search for the class only in the boot
1322 // loader's append path.
1323 if (!ClassLoader::has_bootclasspath_append()) {
1324 // If there is no bootclasspath append entry, no need to continue
1325 // searching.
1326 return nullptr;
1327 }
1328 search_only_bootloader_append = true;
1329 }
1330 }
1331
1332 // Prior to bootstrapping's module initialization, never load a class outside
1333 // of the boot loader's module path
1334 assert(Universe::is_module_initialized() ||
1335 !search_only_bootloader_append,
1336 "Attempt to load a class outside of boot loader's module path");
1337
1338 // Search for classes in the CDS archive.
1339 InstanceKlass* k = nullptr;
1340
1341 #if INCLUDE_CDS
1342 if (CDSConfig::is_using_archive())
1343 {
1344 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1345 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1346 if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {
1347 SharedClassLoadingMark slm(THREAD, ik);
1348 k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1349 }
1350 }
1351 #endif
1352
1353 if (k == nullptr) {
1354 // Use VM class loader
1355 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1356 k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1357 }
1358
1359 // find_or_define_instance_class may return a different InstanceKlass
1360 if (k != nullptr) {
1361 CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1362 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1363 }
1364 return k;
1365 } else {
1366 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1367 ResourceMark rm(THREAD);
1368
1369 JavaThread* jt = THREAD;
1370
1371 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1372 ClassLoader::perf_app_classload_selftime(),
1373 ClassLoader::perf_app_classload_count(),
1374 jt->get_thread_stat()->perf_recursion_counts_addr(),
1375 jt->get_thread_stat()->perf_timers_addr(),
1376 PerfClassTraceTime::CLASS_LOAD);
1377
1378 // Translate to external class name format, i.e., convert '/' chars to '.'
1379 Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1380
1381 JavaValue result(T_OBJECT);
1382
1383 InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1384
1385 // Call public unsynchronized loadClass(String) directly for all class loaders.
1386 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1387 // acquire a class-name based lock rather than the class loader object lock.
1388 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1389 JavaCalls::call_virtual(&result,
1390 class_loader,
1391 spec_klass,
1392 vmSymbols::loadClass_name(),
1393 vmSymbols::string_class_signature(),
1394 string,
1395 CHECK_NULL);
1396
1397 assert(result.get_type() == T_OBJECT, "just checking");
1398 oop obj = result.get_oop();
1399
1400 // Primitive classes return null since forName() can not be
1401 // used to obtain any of the Class objects representing primitives or void
1402 if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {
1403 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1404 // For user defined Java class loaders, check that the name returned is
1405 // the same as that requested. This check is done for the bootstrap
1406 // loader when parsing the class file.
1407 if (class_name == k->name()) {
1408 return k;
1409 }
1410 }
1411 // Class is not found or has the wrong name, return null
1412 return nullptr;
1413 }
1414 }
1415
1416 InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1417 Handle class_loader,
1418 TRAPS) {
1419
1420 InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1421
1422 // If everything was OK (no exceptions, no null return value), and
1423 // class_loader is NOT the defining loader, do a little more bookkeeping.
1424 if (loaded_class != nullptr &&
1425 loaded_class->class_loader() != class_loader()) {
1426
1427 ClassLoaderData* loader_data = class_loader_data(class_loader);
1428 check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1429
1430 // Record dependency for non-parent delegation.
1431 // This recording keeps the defining class loader of the klass (loaded_class) found
1432 // from being unloaded while the initiating class loader is loaded
1433 // even if the reference to the defining class loader is dropped
1434 // before references to the initiating class loader.
1435 loader_data->record_dependency(loaded_class);
1436
1437 update_dictionary(THREAD, loaded_class, loader_data);
1438
1439 if (JvmtiExport::should_post_class_load()) {
1440 JvmtiExport::post_class_load(THREAD, loaded_class);
1441 }
1442 }
1443 return loaded_class;
1444 }
1445
1446 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1447 EventClassDefine event;
1448 if (event.should_commit()) {
1449 event.set_definedClass(k);
1450 event.set_definingClassLoader(def_cld);
1451 event.commit();
1452 }
1453 }
1454
1455 void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {
1456
1457 ClassLoaderData* loader_data = k->class_loader_data();
1458 assert(loader_data->class_loader() == class_loader(), "they must be the same");
1459
1460 // Bootstrap and other parallel classloaders don't acquire a lock,
1461 // they use placeholder token.
1462 // If a parallelCapable class loader calls define_instance_class instead of
1463 // find_or_define_instance_class to get here, we have a timing
1464 // hole with systemDictionary updates and check_constraints
1465 if (!is_parallelCapable(class_loader)) {
1466 assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1467 get_loader_lock_or_null(class_loader)),
1468 "define called without lock");
1469 }
1470
1471 // Check class-loading constraints. Throw exception if violation is detected.
1472 // Grabs and releases SystemDictionary_lock
1473 // The check_constraints/find_class call and update_dictionary sequence
1474 // must be "atomic" for a specific class/classloader pair so we never
1475 // define two different instanceKlasses for that class/classloader pair.
1476 // Existing classloaders will call define_instance_class with the
1477 // classloader lock held
1478 // Parallel classloaders will call find_or_define_instance_class
1479 // which will require a token to perform the define class
1480 check_constraints(k, loader_data, true, CHECK);
1481
1482 // Register class just loaded with class loader (placed in ArrayList)
1483 // Note we do this before updating the dictionary, as this can
1484 // fail with an OutOfMemoryError (if it does, we will *not* put this
1485 // class in the dictionary and will not update the class hierarchy).
1486 // JVMTI FollowReferences needs to find the classes this way.
1487 if (k->class_loader() != nullptr) {
1488 methodHandle m(THREAD, Universe::loader_addClass_method());
1489 JavaValue result(T_VOID);
1490 JavaCallArguments args(class_loader);
1491 args.push_oop(Handle(THREAD, k->java_mirror()));
1492 JavaCalls::call(&result, m, &args, CHECK);
1493 }
1494
1495 // Add to class hierarchy, and do possible deoptimizations.
1496 k->add_to_hierarchy(THREAD);
1497
1498 // Add to systemDictionary - so other classes can see it.
1499 // Grabs and releases SystemDictionary_lock
1500 update_dictionary(THREAD, k, loader_data);
1501
1502 // notify jvmti
1503 if (JvmtiExport::should_post_class_load()) {
1504 JvmtiExport::post_class_load(THREAD, k);
1505 }
1506 post_class_define_event(k, loader_data);
1507 }
1508
1509 // Support parallel classloading
1510 // All parallel class loaders, including bootstrap classloader
1511 // lock a placeholder entry for this class/class_loader pair
1512 // to allow parallel defines of different classes for this class loader
1513 // With AllowParallelDefine flag==true, in case they do not synchronize around
1514 // FindLoadedClass/DefineClass, calls, we check for parallel
1515 // loading for them, wait if a defineClass is in progress
1516 // and return the initial requestor's results
1517 // This flag does not apply to the bootstrap classloader.
1518 // With AllowParallelDefine flag==false, call through to define_instance_class
1519 // which will throw LinkageError: duplicate class definition.
1520 // False is the requested default.
1521 // For better performance, the class loaders should synchronize
1522 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1523 // potentially waste time reading and parsing the bytestream.
1524 // Note: VM callers should ensure consistency of k/class_name,class_loader
1525 // Be careful when modifying this code: once you have run
1526 // PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1527 // you need to find_and_remove it before returning.
1528 // So be careful to not exit with a CHECK_ macro between these calls.
1529 InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1530 InstanceKlass* k, TRAPS) {
1531
1532 Symbol* name_h = k->name();
1533 ClassLoaderData* loader_data = class_loader_data(class_loader);
1534 Dictionary* dictionary = loader_data->dictionary();
1535
1536 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1537 {
1538 MutexLocker mu(THREAD, SystemDictionary_lock);
1539 // First check if class already defined
1540 if (is_parallelDefine(class_loader)) {
1541 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1542 if (check != nullptr) {
1543 return check;
1544 }
1545 }
1546
1547 // Acquire define token for this class/classloader
1548 PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1549 PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1550 // Wait if another thread defining in parallel
1551 // All threads wait - even those that will throw duplicate class: otherwise
1552 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1553 // if other thread has not finished updating dictionary
1554 while (probe->definer() != nullptr) {
1555 SystemDictionary_lock->wait();
1556 }
1557 // Only special cases allow parallel defines and can use other thread's results
1558 // Other cases fall through, and may run into duplicate defines
1559 // caught by finding an entry in the SystemDictionary
1560 if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {
1561 InstanceKlass* ik = probe->instance_klass();
1562 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1563 SystemDictionary_lock->notify_all();
1564 #ifdef ASSERT
1565 InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1566 assert(check != nullptr, "definer missed recording success");
1567 #endif
1568 return ik;
1569 } else {
1570 // This thread will define the class (even if earlier thread tried and had an error)
1571 probe->set_definer(THREAD);
1572 }
1573 }
1574
1575 define_instance_class(k, class_loader, THREAD);
1576
1577 // definer must notify any waiting threads
1578 {
1579 MutexLocker mu(THREAD, SystemDictionary_lock);
1580 PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1581 assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1582 if (!HAS_PENDING_EXCEPTION) {
1583 probe->set_instance_klass(k);
1584 }
1585 probe->set_definer(nullptr);
1586 PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1587 SystemDictionary_lock->notify_all();
1588 }
1589
1590 return HAS_PENDING_EXCEPTION ? nullptr : k;
1591 }
1592
1593 // If a class loader supports parallel classloading handle parallel define requests.
1594 // find_or_define_instance_class may return a different InstanceKlass
1595 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1596 InstanceKlass* k, TRAPS) {
1597 InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1598 // Clean up original InstanceKlass if duplicate or error
1599 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1600 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1601 assert(defined_k != nullptr, "Should have a klass if there's no exception");
1602 k->class_loader_data()->add_to_deallocate_list(k);
1603 } else if (HAS_PENDING_EXCEPTION) {
1604 // Remove this InstanceKlass from the LoaderConstraintTable if added.
1605 LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1606 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1607 k->class_loader_data()->add_to_deallocate_list(k);
1608 }
1609 return defined_k;
1610 }
1611
1612
1613 // ----------------------------------------------------------------------------
1614 // GC support
1615
1616 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1617 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1618
1619 bool unloading_occurred;
1620 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1621 {
1622 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1623 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1624 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1625 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1626 if (unloading_occurred) {
1627 ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1628 JFR_ONLY(Jfr::on_unloading_classes();)
1629 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1630 ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1631 ClassLoaderDataGraph::clean_module_and_package_info();
1632 LoaderConstraintTable::purge_loader_constraints();
1633 ResolutionErrorTable::purge_resolution_errors();
1634 }
1635 }
1636
1637 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1638
1639 if (unloading_occurred) {
1640 SymbolTable::trigger_cleanup();
1641
1642 ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1643 InstanceKlass::clean_initialization_error_table();
1644 }
1645
1646 return unloading_occurred;
1647 }
1648
1649 void SystemDictionary::methods_do(void f(Method*)) {
1650 // Walk methods in loaded classes
1651
1652 {
1653 MutexLocker ml(ClassLoaderDataGraph_lock);
1654 ClassLoaderDataGraph::methods_do(f);
1655 }
1656
1657 auto doit = [&] (InvokeMethodKey key, Method* method) {
1658 if (method != nullptr) {
1659 f(method);
1660 }
1661 };
1662
1663 {
1664 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1665 _invoke_method_intrinsic_table->iterate_all(doit);
1666 }
1667
1668 }
1669
1670 // ----------------------------------------------------------------------------
1671 // Initialization
1672
1673 void SystemDictionary::initialize(TRAPS) {
1674 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1675 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1676 ResolutionErrorTable::initialize();
1677 LoaderConstraintTable::initialize();
1678 PlaceholderTable::initialize();
1679 #if INCLUDE_CDS
1680 SystemDictionaryShared::initialize();
1681 if (CDSConfig::is_dumping_archive()) {
1682 AOTClassLocationConfig::dumptime_init(THREAD);
1683 }
1684 #endif
1685 // Resolve basic classes
1686 vmClasses::resolve_all(CHECK);
1687 // Resolve classes used by archived heap objects
1688 if (CDSConfig::is_using_archive()) {
1689 HeapShared::resolve_classes(THREAD);
1690 }
1691 }
1692
1693 // Constraints on class loaders. The details of the algorithm can be
1694 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1695 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1696 // that the dictionary needs to maintain a set of constraints that
1697 // must be satisfied by all classes in the dictionary.
1698 // if defining is true, then LinkageError if already in dictionary
1699 // if initiating loader, then ok if InstanceKlass matches existing entry
1700
1701 void SystemDictionary::check_constraints(InstanceKlass* k,
1702 ClassLoaderData* loader_data,
1703 bool defining,
1704 TRAPS) {
1705 ResourceMark rm(THREAD);
1706 stringStream ss;
1707 bool throwException = false;
1708
1709 {
1710 Symbol* name = k->name();
1711
1712 MutexLocker mu(THREAD, SystemDictionary_lock);
1713
1714 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1715 if (check != nullptr) {
1716 // If different InstanceKlass - duplicate class definition,
1717 // else - ok, class loaded by a different thread in parallel.
1718 // We should only have found it if it was done loading and ok to use.
1719
1720 if ((defining == true) || (k != check)) {
1721 throwException = true;
1722 ss.print("loader %s", loader_data->loader_name_and_id());
1723 ss.print(" attempted duplicate %s definition for %s. (%s)",
1724 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1725 } else {
1726 return;
1727 }
1728 }
1729
1730 if (throwException == false) {
1731 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1732 throwException = true;
1733 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1734 ss.print(" wants to load %s %s.",
1735 k->external_kind(), k->external_name());
1736 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1737 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1738 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1739 existing_klass->external_kind(),
1740 existing_klass->class_loader_data()->loader_name_and_id(),
1741 existing_klass->class_in_module_of_loader(false, true));
1742 } else {
1743 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1744 }
1745 }
1746 }
1747 }
1748
1749 // Throw error now if needed (cannot throw while holding
1750 // SystemDictionary_lock because of rank ordering)
1751 if (throwException == true) {
1752 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1753 }
1754 }
1755
1756 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1757 // have been called.
1758 void SystemDictionary::update_dictionary(JavaThread* current,
1759 InstanceKlass* k,
1760 ClassLoaderData* loader_data) {
1761 MonitorLocker mu1(SystemDictionary_lock);
1762
1763 // Make a new dictionary entry.
1764 Symbol* name = k->name();
1765 Dictionary* dictionary = loader_data->dictionary();
1766 InstanceKlass* sd_check = dictionary->find_class(current, name);
1767 if (sd_check == nullptr) {
1768 dictionary->add_klass(current, name, k);
1769 }
1770 mu1.notify_all();
1771 }
1772
1773 // Indicate that loader_data has initiated the loading of class k, which
1774 // has already been defined by a parent loader.
1775 // This API is used by AOTLinkedClassBulkLoader and to register boxing
1776 // classes from java.lang in all class loaders to enable more value
1777 // classes optimizations
1778 void SystemDictionary::add_to_initiating_loader(JavaThread* current,
1779 InstanceKlass* k,
1780 ClassLoaderData* loader_data) {
1781 assert_locked_or_safepoint(SystemDictionary_lock);
1782 Symbol* name = k->name();
1783 Dictionary* dictionary = loader_data->dictionary();
1784 assert(k->is_loaded(), "must be");
1785 assert(k->class_loader_data() != loader_data, "only for classes defined by a parent loader");
1786 if (dictionary->find_class(current, name) == nullptr) {
1787 dictionary->add_klass(current, name, k);
1788 }
1789 }
1790
1791 // Try to find a class name using the loader constraints. The
1792 // loader constraints might know about a class that isn't fully loaded
1793 // yet and these will be ignored.
1794 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1795 Thread* current, Symbol* class_name, Handle class_loader) {
1796
1797 // First see if it has been loaded directly.
1798 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader);
1799 if (klass != nullptr)
1800 return klass;
1801
1802 // Now look to see if it has been loaded elsewhere, and is subject to
1803 // a loader constraint that would require this loader to return the
1804 // klass that is already loaded.
1805 if (Signature::is_array(class_name)) {
1806 // For array classes, their Klass*s are not kept in the
1807 // constraint table. The element Klass*s are.
1808 SignatureStream ss(class_name, false);
1809 int ndims = ss.skip_array_prefix(); // skip all '['s
1810 BasicType t = ss.type();
1811 if (t != T_OBJECT) {
1812 klass = Universe::typeArrayKlass(t);
1813 } else {
1814 MutexLocker mu(current, SystemDictionary_lock);
1815 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1816 }
1817 // If element class already loaded, allocate array klass
1818 if (klass != nullptr) {
1819 klass = klass->array_klass_or_null(ndims);
1820 }
1821 } else {
1822 MutexLocker mu(current, SystemDictionary_lock);
1823 // Non-array classes are easy: simply check the constraint table.
1824 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1825 }
1826
1827 return klass;
1828 }
1829
1830 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1831 Klass* klass_being_linked,
1832 Handle class_loader1,
1833 Handle class_loader2) {
1834 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1835 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1836
1837 Symbol* constraint_name = nullptr;
1838
1839 if (!Signature::is_array(class_name)) {
1840 constraint_name = class_name;
1841 } else {
1842 // For array classes, their Klass*s are not kept in the
1843 // constraint table. The element classes are.
1844 SignatureStream ss(class_name, false);
1845 ss.skip_array_prefix(); // skip all '['s
1846 if (!ss.has_envelope()) {
1847 return true; // primitive types always pass
1848 }
1849 constraint_name = ss.as_symbol();
1850 // Increment refcount to keep constraint_name alive after
1851 // SignatureStream is destructed. It will be decremented below
1852 // before returning.
1853 constraint_name->increment_refcount();
1854 }
1855
1856 Dictionary* dictionary1 = loader_data1->dictionary();
1857 Dictionary* dictionary2 = loader_data2->dictionary();
1858
1859 JavaThread* current = JavaThread::current();
1860 {
1861 MutexLocker mu_s(SystemDictionary_lock);
1862 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1863 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1864 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1865 klass2, loader_data2);
1866 #if INCLUDE_CDS
1867 if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1868 !klass_being_linked->is_shared()) {
1869 SystemDictionaryShared::record_linking_constraint(constraint_name,
1870 InstanceKlass::cast(klass_being_linked),
1871 class_loader1, class_loader2);
1872 }
1873 #endif // INCLUDE_CDS
1874 if (Signature::is_array(class_name)) {
1875 constraint_name->decrement_refcount();
1876 }
1877 return result;
1878 }
1879 }
1880
1881 // Add entry to resolution error table to record the error when the first
1882 // attempt to resolve a reference to a class has failed.
1883 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1884 Symbol* error, const char* message,
1885 Symbol* cause, const char* cause_msg) {
1886 {
1887 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1888 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1889 if (entry == nullptr) {
1890 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1891 }
1892 }
1893 }
1894
1895 // Delete a resolution error for RedefineClasses for a constant pool is going away
1896 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1897 ResolutionErrorTable::delete_entry(pool);
1898 }
1899
1900 // Lookup resolution error table. Returns error if found, otherwise null.
1901 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1902 const char** message,
1903 Symbol** cause, const char** cause_msg) {
1904
1905 {
1906 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1907 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1908 if (entry != nullptr) {
1909 *message = entry->message();
1910 *cause = entry->cause();
1911 *cause_msg = entry->cause_msg();
1912 return entry->error();
1913 } else {
1914 return nullptr;
1915 }
1916 }
1917 }
1918
1919 // Add an entry to resolution error table to record an error in resolving or
1920 // validating a nest host. This is used to construct informative error
1921 // messages when IllegalAccessError's occur. If an entry already exists it will
1922 // be updated with the nest host error message.
1923
1924 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1925 int which,
1926 const char* message) {
1927 {
1928 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1929 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1930 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1931 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1932 // still want to add the error message for the higher-level access checks to report. We should
1933 // only reach here under the same error condition, so we can ignore the potential race with setting
1934 // the message. If we see it is already set then we can ignore it.
1935 entry->set_nest_host_error(message);
1936 } else {
1937 ResolutionErrorTable::add_entry(pool, which, message);
1938 }
1939 }
1940 }
1941
1942 // Lookup any nest host error
1943 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1944 {
1945 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1946 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1947 if (entry != nullptr) {
1948 return entry->nest_host_error();
1949 } else {
1950 return nullptr;
1951 }
1952 }
1953 }
1954
1955 // Signature constraints ensure that callers and callees agree about
1956 // the meaning of type names in their signatures. This routine is the
1957 // intake for constraints. It collects them from several places:
1958 //
1959 // * LinkResolver::resolve_method (if check_access is true) requires
1960 // that the resolving class (the caller) and the defining class of
1961 // the resolved method (the callee) agree on each type in the
1962 // method's signature.
1963 //
1964 // * LinkResolver::resolve_interface_method performs exactly the same
1965 // checks.
1966 //
1967 // * LinkResolver::resolve_field requires that the constant pool
1968 // attempting to link to a field agree with the field's defining
1969 // class about the type of the field signature.
1970 //
1971 // * klassVtable::initialize_vtable requires that, when a class
1972 // overrides a vtable entry allocated by a superclass, that the
1973 // overriding method (i.e., the callee) agree with the superclass
1974 // on each type in the method's signature.
1975 //
1976 // * klassItable::initialize_itable requires that, when a class fills
1977 // in its itables, for each non-abstract method installed in an
1978 // itable, the method (i.e., the callee) agree with the interface
1979 // on each type in the method's signature.
1980 //
1981 // All those methods have a boolean (check_access, checkconstraints)
1982 // which turns off the checks. This is used from specialized contexts
1983 // such as bootstrapping, dumping, and debugging.
1984 //
1985 // No direct constraint is placed between the class and its
1986 // supertypes. Constraints are only placed along linked relations
1987 // between callers and callees. When a method overrides or implements
1988 // an abstract method in a supertype (superclass or interface), the
1989 // constraints are placed as if the supertype were the caller to the
1990 // overriding method. (This works well, since callers to the
1991 // supertype have already established agreement between themselves and
1992 // the supertype.) As a result of all this, a class can disagree with
1993 // its supertype about the meaning of a type name, as long as that
1994 // class neither calls a relevant method of the supertype, nor is
1995 // called (perhaps via an override) from the supertype.
1996 //
1997 //
1998 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1999 //
2000 // Make sure all class components (including arrays) in the given
2001 // signature will be resolved to the same class in both loaders.
2002 // Returns the name of the type that failed a loader constraint check, or
2003 // null if no constraint failed. No exception except OOME is thrown.
2004 // Arrays are not added to the loader constraint table, their elements are.
2005 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2006 Klass* klass_being_linked,
2007 Handle loader1, Handle loader2,
2008 bool is_method) {
2009 // Nothing to do if loaders are the same.
2010 if (loader1() == loader2()) {
2011 return nullptr;
2012 }
2013
2014 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
2015 if (ss.is_reference()) {
2016 Symbol* sig = ss.as_symbol();
2017 // Note: In the future, if template-like types can take
2018 // arguments, we will want to recognize them and dig out class
2019 // names hiding inside the argument lists.
2020 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
2021 return sig;
2022 }
2023 }
2024 }
2025 return nullptr;
2026 }
2027
2028 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
2029 Symbol* signature,
2030 TRAPS) {
2031
2032 const int iid_as_int = vmIntrinsics::as_int(iid);
2033 assert(MethodHandles::is_signature_polymorphic(iid) &&
2034 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2035 iid != vmIntrinsics::_invokeGeneric,
2036 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
2037
2038 InvokeMethodKey key(signature, iid_as_int);
2039 Method** met = nullptr;
2040
2041 // We only want one entry in the table for this (signature/id, method) pair but the code
2042 // to create the intrinsic method needs to be outside the lock.
2043 // The first thread claims the entry by adding the key and the other threads wait, until the
2044 // Method has been added as the value.
2045 {
2046 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2047 while (true) {
2048 bool created;
2049 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
2050 assert(met != nullptr, "either created or found");
2051 if (*met != nullptr) {
2052 return *met;
2053 } else if (created) {
2054 // The current thread won the race and will try to create the full entry.
2055 break;
2056 } else {
2057 // Another thread beat us to it, so wait for them to complete
2058 // and return *met; or if they hit an error we get another try.
2059 ml.wait();
2060 // Note it is not safe to read *met here as that entry could have
2061 // been deleted, so we must loop and try put_if_absent again.
2062 }
2063 }
2064 }
2065
2066 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
2067 bool throw_error = HAS_PENDING_EXCEPTION;
2068 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
2069 // Generate a compiled form of the MH intrinsic
2070 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2071 AdapterHandlerLibrary::create_native_wrapper(m);
2072 // Check if have the compiled code.
2073 throw_error = (!m->has_compiled_code());
2074 }
2075
2076 {
2077 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2078 if (throw_error) {
2079 // Remove the entry and let another thread try, or get the same exception.
2080 bool removed = _invoke_method_intrinsic_table->remove(key);
2081 assert(removed, "must be the owner");
2082 ml.notify_all();
2083 } else {
2084 signature->make_permanent(); // The signature is never unloaded.
2085 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2086 m->code()->entry_point() == m->from_compiled_entry()),
2087 "MH intrinsic invariant");
2088 *met = m(); // insert the element
2089 ml.notify_all();
2090 return m();
2091 }
2092 }
2093
2094 // Throw OOM or the pending exception in the JavaThread
2095 if (throw_error && !HAS_PENDING_EXCEPTION) {
2096 THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2097 "Out of space in CodeCache for method handle intrinsic");
2098 }
2099 return nullptr;
2100 }
2101
2102 #if INCLUDE_CDS
2103 void SystemDictionary::get_all_method_handle_intrinsics(GrowableArray<Method*>* methods) {
2104 assert(SafepointSynchronize::is_at_safepoint(), "must be");
2105 auto do_method = [&] (InvokeMethodKey& key, Method*& m) {
2106 methods->append(m);
2107 };
2108 _invoke_method_intrinsic_table->iterate_all(do_method);
2109 }
2110
2111 void SystemDictionary::restore_archived_method_handle_intrinsics() {
2112 if (UseSharedSpaces) {
2113 EXCEPTION_MARK;
2114 restore_archived_method_handle_intrinsics_impl(THREAD);
2115 if (HAS_PENDING_EXCEPTION) {
2116 // This is probably caused by OOM -- other parts of the CDS archive have direct pointers to
2117 // the archived method handle intrinsics, so we can't really recover from this failure.
2118 vm_exit_during_initialization(err_msg("Failed to restore archived method handle intrinsics. Try to increase heap size."));
2119 }
2120 }
2121 }
2122
2123 void SystemDictionary::restore_archived_method_handle_intrinsics_impl(TRAPS) {
2124 Array<Method*>* list = MetaspaceShared::archived_method_handle_intrinsics();
2125 for (int i = 0; i < list->length(); i++) {
2126 methodHandle m(THREAD, list->at(i));
2127 Method::restore_archived_method_handle_intrinsic(m, CHECK);
2128 m->constants()->restore_unshareable_info(CHECK);
2129 if (!Arguments::is_interpreter_only() || m->intrinsic_id() == vmIntrinsics::_linkToNative) {
2130 AdapterHandlerLibrary::create_native_wrapper(m);
2131 if (!m->has_compiled_code()) {
2132 ResourceMark rm(THREAD);
2133 vm_exit_during_initialization(err_msg("Failed to initialize method %s", m->external_name()));
2134 }
2135 }
2136
2137 // There's no need to grab the InvokeMethodIntrinsicTable_lock, as we are still very early in
2138 // VM start-up -- in init_globals2() -- so we are still running a single Java thread. It's not
2139 // possible to have a contention.
2140 const int iid_as_int = vmIntrinsics::as_int(m->intrinsic_id());
2141 InvokeMethodKey key(m->signature(), iid_as_int);
2142 bool created = _invoke_method_intrinsic_table->put(key, m());
2143 assert(created, "unexpected contention");
2144 }
2145 }
2146 #endif // INCLUDE_CDS
2147
2148 // Helper for unpacking the return value from linkMethod and linkCallSite.
2149 static Method* unpack_method_and_appendix(Handle mname,
2150 Klass* accessing_klass,
2151 objArrayHandle appendix_box,
2152 Handle* appendix_result,
2153 TRAPS) {
2154 if (mname.not_null()) {
2155 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2156 if (m != nullptr) {
2157 oop appendix = appendix_box->obj_at(0);
2158 LogTarget(Info, methodhandles) lt;
2159 if (lt.develop_is_enabled()) {
2160 ResourceMark rm(THREAD);
2161 LogStream ls(lt);
2162 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2163 m->print_on(&ls);
2164 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2165 ls.cr();
2166 }
2167
2168 (*appendix_result) = Handle(THREAD, appendix);
2169 // the target is stored in the cpCache and if a reference to this
2170 // MemberName is dropped we need a way to make sure the
2171 // class_loader containing this method is kept alive.
2172 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2173 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2174 this_key->record_dependency(m->method_holder());
2175 return mh();
2176 }
2177 }
2178 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2179 }
2180
2181 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2182 Symbol* name,
2183 Symbol* signature,
2184 Klass* accessing_klass,
2185 Handle* appendix_result,
2186 TRAPS) {
2187 guarantee(THREAD->can_call_java(), "");
2188 Handle method_type =
2189 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2190
2191 int ref_kind = JVM_REF_invokeVirtual;
2192 oop name_oop = StringTable::intern(name, CHECK_NULL);
2193 Handle name_str (THREAD, name_oop);
2194 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2195 assert(appendix_box->obj_at(0) == nullptr, "");
2196
2197 // This should not happen. JDK code should take care of that.
2198 if (accessing_klass == nullptr || method_type.is_null()) {
2199 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2200 }
2201
2202 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2203 JavaCallArguments args;
2204 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2205 args.push_int(ref_kind);
2206 args.push_oop(Handle(THREAD, klass->java_mirror()));
2207 args.push_oop(name_str);
2208 args.push_oop(method_type);
2209 args.push_oop(appendix_box);
2210 JavaValue result(T_OBJECT);
2211 JavaCalls::call_static(&result,
2212 vmClasses::MethodHandleNatives_klass(),
2213 vmSymbols::linkMethod_name(),
2214 vmSymbols::linkMethod_signature(),
2215 &args, CHECK_NULL);
2216 Handle mname(THREAD, result.get_oop());
2217 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2218 }
2219
2220 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2221 // We must ensure that all class loaders everywhere will reach this class, for any client.
2222 // This is a safe bet for public classes in java.lang, such as Object and String.
2223 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2224 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2225 static bool is_always_visible_class(oop mirror) {
2226 Klass* klass = java_lang_Class::as_Klass(mirror);
2227 if (klass->is_objArray_klass()) {
2228 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2229 }
2230 if (klass->is_typeArray_klass()) {
2231 return true; // primitive array
2232 }
2233 assert(klass->is_instance_klass(), "%s", klass->external_name());
2234 return klass->is_public() &&
2235 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2236 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2237 }
2238
2239 // Find or construct the Java mirror (java.lang.Class instance) for
2240 // the given field type signature, as interpreted relative to the
2241 // given class loader. Handles primitives, void, references, arrays,
2242 // and all other reflectable types, except method types.
2243 // N.B. Code in reflection should use this entry point.
2244 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2245 Klass* accessing_klass,
2246 SignatureStream::FailureMode failure_mode,
2247 TRAPS) {
2248
2249 Handle class_loader;
2250
2251 // What we have here must be a valid field descriptor,
2252 // and all valid field descriptors are supported.
2253 // Produce the same java.lang.Class that reflection reports.
2254 if (accessing_klass != nullptr) {
2255 class_loader = Handle(THREAD, accessing_klass->class_loader());
2256 }
2257 ResolvingSignatureStream ss(signature, class_loader, false);
2258 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2259 if (mirror_oop == nullptr) {
2260 return Handle(); // report failure this way
2261 }
2262 Handle mirror(THREAD, mirror_oop);
2263
2264 if (accessing_klass != nullptr) {
2265 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2266 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2267 if (sel_klass != nullptr) {
2268 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2269 }
2270 }
2271 return mirror;
2272 }
2273
2274
2275 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2276 // signature, as interpreted relative to the given class loader.
2277 // Because of class loader constraints, all method handle usage must be
2278 // consistent with this loader.
2279 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2280 Klass* accessing_klass,
2281 TRAPS) {
2282 Handle empty;
2283 OopHandle* o;
2284 {
2285 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2286 o = _invoke_method_type_table->get(signature);
2287 }
2288
2289 if (o != nullptr) {
2290 oop mt = o->resolve();
2291 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2292 return Handle(THREAD, mt);
2293 } else if (!THREAD->can_call_java()) {
2294 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2295 return Handle(); // do not attempt from within compiler, unless it was cached
2296 }
2297
2298 Handle class_loader;
2299 if (accessing_klass != nullptr) {
2300 class_loader = Handle(THREAD, accessing_klass->class_loader());
2301 }
2302 bool can_be_cached = true;
2303 int npts = ArgumentCount(signature).size();
2304 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2305 int arg = 0;
2306 Handle rt; // the return type from the signature
2307 ResourceMark rm(THREAD);
2308 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2309 oop mirror = nullptr;
2310 if (can_be_cached) {
2311 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2312 mirror = ss.as_java_mirror(Handle(), SignatureStream::ReturnNull, CHECK_(empty));
2313 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2314 // Fall back to accessing_klass context.
2315 can_be_cached = false;
2316 }
2317 }
2318 if (!can_be_cached) {
2319 // Resolve, throwing a real error if it doesn't work.
2320 mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2321 }
2322 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2323 if (ss.at_return_type())
2324 rt = Handle(THREAD, mirror);
2325 else
2326 pts->obj_at_put(arg++, mirror);
2327
2328 // Check accessibility.
2329 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2330 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2331 mirror = nullptr; // safety
2332 // Emulate ConstantPool::verify_constant_pool_resolve.
2333 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2334 }
2335 }
2336 assert(arg == npts, "");
2337
2338 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2339 JavaCallArguments args(Handle(THREAD, rt()));
2340 args.push_oop(pts);
2341 JavaValue result(T_OBJECT);
2342 JavaCalls::call_static(&result,
2343 vmClasses::MethodHandleNatives_klass(),
2344 vmSymbols::findMethodHandleType_name(),
2345 vmSymbols::findMethodHandleType_signature(),
2346 &args, CHECK_(empty));
2347 Handle method_type(THREAD, result.get_oop());
2348
2349 if (can_be_cached) {
2350 // We can cache this MethodType inside the JVM.
2351 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2352 bool created = false;
2353 assert(method_type != nullptr, "unexpected null");
2354 OopHandle* h = _invoke_method_type_table->get(signature);
2355 if (h == nullptr) {
2356 signature->make_permanent(); // The signature is never unloaded.
2357 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2358 bool created = _invoke_method_type_table->put(signature, elem);
2359 assert(created, "better be created");
2360 }
2361 }
2362 // report back to the caller with the MethodType
2363 return method_type;
2364 }
2365
2366 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2367 Klass* accessing_klass,
2368 TRAPS) {
2369 Handle empty;
2370 ResourceMark rm(THREAD);
2371 SignatureStream ss(signature, /*is_method=*/ false);
2372 if (!ss.is_done()) {
2373 Handle class_loader;
2374 if (accessing_klass != nullptr) {
2375 class_loader = Handle(THREAD, accessing_klass->class_loader());
2376 }
2377 oop mirror = ss.as_java_mirror(class_loader, SignatureStream::NCDFError, CHECK_(empty));
2378 ss.next();
2379 if (ss.is_done()) {
2380 return Handle(THREAD, mirror);
2381 }
2382 }
2383 return empty;
2384 }
2385
2386 // Ask Java code to find or construct a method handle constant.
2387 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2388 int ref_kind, //e.g., JVM_REF_invokeVirtual
2389 Klass* callee,
2390 Symbol* name,
2391 Symbol* signature,
2392 TRAPS) {
2393 Handle empty;
2394 if (caller == nullptr) {
2395 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2396 }
2397 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2398 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2399
2400 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2401 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2402 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2403 java_lang_invoke_MemberName::set_name (mname(), name_str());
2404 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2405 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2406
2407 if (ref_kind == JVM_REF_invokeVirtual &&
2408 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2409 // Skip resolution for public signature polymorphic methods such as
2410 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2411 // They require appendix argument which MemberName resolution doesn't handle.
2412 // There's special logic on JDK side to handle them
2413 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2414 } else {
2415 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2416 }
2417
2418 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2419 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2420
2421 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2422 JavaCallArguments args;
2423 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2424 args.push_int(ref_kind);
2425 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2426 args.push_oop(name_str);
2427 args.push_oop(type);
2428 JavaValue result(T_OBJECT);
2429 JavaCalls::call_static(&result,
2430 vmClasses::MethodHandleNatives_klass(),
2431 vmSymbols::linkMethodHandleConstant_name(),
2432 vmSymbols::linkMethodHandleConstant_signature(),
2433 &args, CHECK_(empty));
2434 return Handle(THREAD, result.get_oop());
2435 }
2436
2437 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2438 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2439 // with linkage results being stored back into the bootstrap specifier.
2440 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2441 // Resolve the bootstrap specifier, its name, type, and static arguments
2442 bootstrap_specifier.resolve_bsm(CHECK);
2443
2444 // This should not happen. JDK code should take care of that.
2445 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2446 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2447 }
2448
2449 bool is_indy = bootstrap_specifier.is_method_call();
2450 objArrayHandle appendix_box;
2451 if (is_indy) {
2452 // Some method calls may require an appendix argument. Arrange to receive it.
2453 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2454 assert(appendix_box->obj_at(0) == nullptr, "");
2455 }
2456
2457 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2458 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2459 JavaCallArguments args;
2460 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2461 args.push_oop(bootstrap_specifier.bsm());
2462 args.push_oop(bootstrap_specifier.name_arg());
2463 args.push_oop(bootstrap_specifier.type_arg());
2464 args.push_oop(bootstrap_specifier.arg_values());
2465 if (is_indy) {
2466 args.push_oop(appendix_box);
2467 }
2468 JavaValue result(T_OBJECT);
2469 JavaCalls::call_static(&result,
2470 vmClasses::MethodHandleNatives_klass(),
2471 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2472 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2473 &args, CHECK);
2474
2475 Handle value(THREAD, result.get_oop());
2476 if (is_indy) {
2477 Handle appendix;
2478 Method* method = unpack_method_and_appendix(value,
2479 bootstrap_specifier.caller(),
2480 appendix_box,
2481 &appendix, CHECK);
2482 methodHandle mh(THREAD, method);
2483 bootstrap_specifier.set_resolved_method(mh, appendix);
2484 } else {
2485 bootstrap_specifier.set_resolved_value(value);
2486 }
2487
2488 // sanity check
2489 assert(bootstrap_specifier.is_resolved() ||
2490 (bootstrap_specifier.is_method_call() &&
2491 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2492 }
2493
2494
2495 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2496 assert(m != nullptr, "Unexpected nullptr Method*");
2497 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2498 }
2499
2500 // ----------------------------------------------------------------------------
2501
2502 void SystemDictionary::print_on(outputStream *st) {
2503 CDS_ONLY(SystemDictionaryShared::print_on(st));
2504 GCMutexLocker mu(SystemDictionary_lock);
2505
2506 ClassLoaderDataGraph::print_dictionary(st);
2507
2508 // Placeholders
2509 PlaceholderTable::print_on(st);
2510 st->cr();
2511
2512 // loader constraints - print under SD_lock
2513 LoaderConstraintTable::print_on(st);
2514 st->cr();
2515 }
2516
2517 void SystemDictionary::print() { print_on(tty); }
2518
2519 void SystemDictionary::verify() {
2520
2521 GCMutexLocker mu(SystemDictionary_lock);
2522
2523 // Verify dictionary
2524 ClassLoaderDataGraph::verify_dictionary();
2525
2526 // Verify constraint table
2527 LoaderConstraintTable::verify();
2528 }
2529
2530 void SystemDictionary::dump(outputStream *st, bool verbose) {
2531 assert_locked_or_safepoint(SystemDictionary_lock);
2532 if (verbose) {
2533 print_on(st);
2534 } else {
2535 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2536 ClassLoaderDataGraph::print_table_statistics(st);
2537 LoaderConstraintTable::print_table_statistics(st);
2538 }
2539 }
2540
2541 // Utility for dumping dictionaries.
2542 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2543 DCmdWithParser(output, heap),
2544 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2545 "BOOLEAN", false, "false") {
2546 _dcmdparser.add_dcmd_option(&_verbose);
2547 }
2548
2549 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2550 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2551 _verbose.value());
2552 VMThread::execute(&dumper);
2553 }