1 /*
2 * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "cds/heapShared.hpp"
27 #include "classfile/classFileParser.hpp"
28 #include "classfile/classFileStream.hpp"
29 #include "classfile/classLoader.hpp"
30 #include "classfile/classLoaderData.inline.hpp"
31 #include "classfile/classLoaderDataGraph.inline.hpp"
32 #include "classfile/classLoaderExt.hpp"
33 #include "classfile/classLoadInfo.hpp"
34 #include "classfile/dictionary.hpp"
35 #include "classfile/javaClasses.inline.hpp"
36 #include "classfile/klassFactory.hpp"
37 #include "classfile/loaderConstraints.hpp"
38 #include "classfile/packageEntry.hpp"
39 #include "classfile/placeholders.hpp"
40 #include "classfile/protectionDomainCache.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/macros.hpp"
88 #include "utilities/utf8.hpp"
89 #if INCLUDE_CDS
90 #include "classfile/systemDictionaryShared.hpp"
91 #endif
92 #if INCLUDE_JFR
93 #include "jfr/jfr.hpp"
94 #endif
95
96 class InvokeMethodKey : public StackObj {
97 private:
98 Symbol* _symbol;
99 intptr_t _iid;
100
101 public:
102 InvokeMethodKey(Symbol* symbol, intptr_t iid) :
103 _symbol(symbol),
104 _iid(iid) {}
105
106 static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){
107 return k1._symbol == k2._symbol && k1._iid == k2._iid;
108 }
109
110 static unsigned int compute_hash(const InvokeMethodKey &k) {
111 Symbol* sym = k._symbol;
112 intptr_t iid = k._iid;
113 unsigned int hash = (unsigned int) sym -> identity_hash();
114 return (unsigned int) (hash ^ iid);
115 }
116
117 };
118
119 using InvokeMethodIntrinsicTable = ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
120 InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
121 static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
122 using InvokeMethodTypeTable = ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
123 static InvokeMethodTypeTable* _invoke_method_type_table;
124
125 OopHandle SystemDictionary::_java_system_loader;
126 OopHandle SystemDictionary::_java_platform_loader;
127
128 // ----------------------------------------------------------------------------
129 // Java-level SystemLoader and PlatformLoader
130 oop SystemDictionary::java_system_loader() {
131 return _java_system_loader.resolve();
132 }
133
134 oop SystemDictionary::java_platform_loader() {
135 return _java_platform_loader.resolve();
136 }
137
138 void SystemDictionary::compute_java_loaders(TRAPS) {
139 if (_java_system_loader.is_empty()) {
140 oop system_loader = get_system_class_loader_impl(CHECK);
141 _java_system_loader = OopHandle(Universe::vm_global(), system_loader);
142 } else {
143 // It must have been restored from the archived module graph
144 assert(UseSharedSpaces, "must be");
145 assert(MetaspaceShared::use_full_module_graph(), "must be");
146 DEBUG_ONLY(
147 oop system_loader = get_system_class_loader_impl(CHECK);
148 assert(_java_system_loader.resolve() == system_loader, "must be");
149 )
150 }
151
152 if (_java_platform_loader.is_empty()) {
153 oop platform_loader = get_platform_class_loader_impl(CHECK);
154 _java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
155 } else {
156 // It must have been restored from the archived module graph
157 assert(UseSharedSpaces, "must be");
158 assert(MetaspaceShared::use_full_module_graph(), "must be");
159 DEBUG_ONLY(
160 oop platform_loader = get_platform_class_loader_impl(CHECK);
161 assert(_java_platform_loader.resolve() == platform_loader, "must be");
162 )
163 }
164 }
165
166 oop SystemDictionary::get_system_class_loader_impl(TRAPS) {
167 JavaValue result(T_OBJECT);
168 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
169 JavaCalls::call_static(&result,
170 class_loader_klass,
171 vmSymbols::getSystemClassLoader_name(),
172 vmSymbols::void_classloader_signature(),
173 CHECK_NULL);
174 return result.get_oop();
175 }
176
177 oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {
178 JavaValue result(T_OBJECT);
179 InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
180 JavaCalls::call_static(&result,
181 class_loader_klass,
182 vmSymbols::getPlatformClassLoader_name(),
183 vmSymbols::void_classloader_signature(),
184 CHECK_NULL);
185 return result.get_oop();
186 }
187
188 // Helper function
189 inline ClassLoaderData* class_loader_data(Handle class_loader) {
190 return ClassLoaderData::class_loader_data(class_loader());
191 }
192
193 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
194 if (create_mirror_cld) {
195 // Add a new class loader data to the graph.
196 return ClassLoaderDataGraph::add(class_loader, true);
197 } else {
198 return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
199 ClassLoaderDataGraph::find_or_create(class_loader);
200 }
201 }
202
203 void SystemDictionary::set_system_loader(ClassLoaderData *cld) {
204 assert(_java_system_loader.is_empty(), "already set!");
205 _java_system_loader = cld->class_loader_handle();
206
207 }
208
209 void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {
210 assert(_java_platform_loader.is_empty(), "already set!");
211 _java_platform_loader = cld->class_loader_handle();
212 }
213
214 // ----------------------------------------------------------------------------
215 // Parallel class loading check
216
217 bool is_parallelCapable(Handle class_loader) {
218 if (class_loader.is_null()) return true;
219 return java_lang_ClassLoader::parallelCapable(class_loader());
220 }
221 // ----------------------------------------------------------------------------
222 // ParallelDefineClass flag does not apply to bootclass loader
223 bool is_parallelDefine(Handle class_loader) {
224 if (class_loader.is_null()) return false;
225 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
226 return true;
227 }
228 return false;
229 }
230
231 // Returns true if the passed class loader is the builtin application class loader
232 // or a custom system class loader. A customer system class loader can be
233 // specified via -Djava.system.class.loader.
234 bool SystemDictionary::is_system_class_loader(oop class_loader) {
235 if (class_loader == nullptr) {
236 return false;
237 }
238 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
239 class_loader == _java_system_loader.peek());
240 }
241
242 // Returns true if the passed class loader is the platform class loader.
243 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
244 if (class_loader == nullptr) {
245 return false;
246 }
247 return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
248 }
249
250 Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {
251 // If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
252 if (is_parallelCapable(class_loader)) {
253 return Handle();
254 } else {
255 return class_loader;
256 }
257 }
258
259 // ----------------------------------------------------------------------------
260 // Resolving of classes
261
262 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
263 if (name == nullptr) {
264 THROW_MSG_0(exception, "No class name given");
265 }
266 if ((int)strlen(name) > Symbol::max_length()) {
267 // It's impossible to create this class; the name cannot fit
268 // into the constant pool.
269 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
270 "Class name exceeds maximum length of %d: %s",
271 Symbol::max_length(),
272 name);
273 return nullptr;
274 }
275 // Callers should ensure that the name is never an illegal UTF8 string.
276 assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false),
277 "Class name is not a valid utf8 string.");
278
279 // Make a new symbol for the class name.
280 return SymbolTable::new_symbol(name);
281 }
282
283 #ifdef ASSERT
284 // Used to verify that class loading succeeded in adding k to the dictionary.
285 void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {
286 MutexLocker mu(SystemDictionary_lock);
287 ClassLoaderData* loader_data = k->class_loader_data();
288 Dictionary* dictionary = loader_data->dictionary();
289 assert(class_name == k->name(), "Must be the same");
290 InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
291 assert(kk == k, "should be present in dictionary");
292 }
293 #endif
294
295 static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {
296 if (HAS_PENDING_EXCEPTION) {
297 // If we have a pending exception we forward it to the caller, unless throw_error is true,
298 // in which case we have to check whether the pending exception is a ClassNotFoundException,
299 // and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
300 if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {
301 ResourceMark rm(THREAD);
302 Handle e(THREAD, PENDING_EXCEPTION);
303 CLEAR_PENDING_EXCEPTION;
304 THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
305 } else {
306 return; // the caller will throw the incoming exception
307 }
308 }
309 // If the class is not found, ie, caller has checked that klass is null, throw the appropriate
310 // error or exception depending on the value of throw_error.
311 ResourceMark rm(THREAD);
312 if (throw_error) {
313 THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
314 } else {
315 THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
316 }
317 }
318
319 // Forwards to resolve_or_null
320
321 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
322 bool throw_error, TRAPS) {
323 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
324 // Check for pending exception or null klass, and throw exception
325 if (HAS_PENDING_EXCEPTION || klass == nullptr) {
326 handle_resolution_exception(class_name, throw_error, CHECK_NULL);
327 }
328 return klass;
329 }
330
331 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
332
333 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
334 if (Signature::is_array(class_name)) {
335 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
336 } else {
337 assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
338 if (Signature::has_envelope(class_name)) {
339 ResourceMark rm(THREAD);
340 // Ignore wrapping L and ; (and Q and ; for value types).
341 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
342 class_name->utf8_length() - 2);
343 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
344 } else {
345 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
346 }
347 }
348 }
349
350 // Forwards to resolve_instance_class_or_null
351
352 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
353 Handle class_loader,
354 Handle protection_domain,
355 TRAPS) {
356 assert(Signature::is_array(class_name), "must be array");
357 ResourceMark rm(THREAD);
358 SignatureStream ss(class_name, false);
359 int ndims = ss.skip_array_prefix(); // skip all '['s
360 Klass* k = nullptr;
361 BasicType t = ss.type();
362 if (ss.has_envelope()) {
363 Symbol* obj_class = ss.as_symbol();
364 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
365 class_loader,
366 protection_domain,
367 CHECK_NULL);
368 if (k != nullptr) {
369 if (class_name->is_Q_array_signature()) {
370 if (!k->is_inline_klass()) {
371 THROW_MSG_NULL(vmSymbols::java_lang_IncompatibleClassChangeError(), "L/Q mismatch on bottom type");
372 }
373 k = InlineKlass::cast(k)->value_array_klass(ndims, CHECK_NULL);
374 } else {
375 k = k->array_klass(ndims, CHECK_NULL);
376 }
377 }
378 } else {
379 k = Universe::typeArrayKlassObj(t);
380 k = TypeArrayKlass::cast(k)->array_klass(ndims, CHECK_NULL);
381 }
382 return k;
383 }
384
385 static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {
386 LogTarget(Debug, class, load, placeholders) lt;
387 if (lt.is_enabled()) {
388 ResourceMark rm;
389 LogStream ls(lt);
390 ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());
391 probe->print_on(&ls);
392 ls.cr();
393 }
394 }
395
396 // Must be called for any superclass or superinterface resolution
397 // during class definition to allow class circularity checking
398 // superinterface callers:
399 // parse_interfaces - from defineClass
400 // superclass callers:
401 // ClassFileParser - from defineClass
402 // load_shared_class - while loading a class from shared archive
403 // resolve_instance_class_or_null:
404 // via: handle_parallel_super_load
405 // when resolving a class that has an existing placeholder with
406 // a saved superclass [i.e. a defineClass is currently in progress]
407 // If another thread is trying to resolve the class, it must do
408 // superclass checks on its own thread to catch class circularity and
409 // to avoid deadlock.
410 //
411 // resolve_super_or_fail adds a LOAD_SUPER placeholder to the placeholder table before calling
412 // resolve_instance_class_or_null. ClassCircularityError is detected when a LOAD_SUPER or LOAD_INSTANCE
413 // placeholder for the same thread, class, classloader is found.
414 // This can be seen with logging option: -Xlog:class+load+placeholders=debug.
415 //
416 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* class_name,
417 Symbol* super_name,
418 Handle class_loader,
419 Handle protection_domain,
420 bool is_superclass,
421 TRAPS) {
422
423 assert(super_name != nullptr, "null superclass for resolving");
424 assert(!Signature::is_array(super_name), "invalid superclass name");
425 #if INCLUDE_CDS
426 if (DumpSharedSpaces) {
427 // Special processing for handling UNREGISTERED shared classes.
428 InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
429 super_name, is_superclass);
430 if (k) {
431 return k;
432 }
433 }
434 #endif // INCLUDE_CDS
435
436 // If klass is already loaded, just return the superclass or superinterface.
437 // Make sure there's a placeholder for the class_name before resolving.
438 // This is used as a claim that this thread is currently loading superclass/classloader
439 // and for ClassCircularity checks.
440
441 ClassLoaderData* loader_data = class_loader_data(class_loader);
442 Dictionary* dictionary = loader_data->dictionary();
443
444 // can't throw error holding a lock
445 bool throw_circularity_error = false;
446 {
447 MutexLocker mu(THREAD, SystemDictionary_lock);
448 InstanceKlass* klassk = dictionary->find_class(THREAD, class_name);
449 InstanceKlass* quicksuperk;
450 // To support parallel loading: if class is done loading, just return the superclass
451 // if the super_name matches class->super()->name() and if the class loaders match.
452 // Otherwise, a LinkageError will be thrown later.
453 if (klassk != nullptr && is_superclass &&
454 ((quicksuperk = klassk->java_super()) != nullptr) &&
455 ((quicksuperk->name() == super_name) &&
456 (quicksuperk->class_loader() == class_loader()))) {
457 return quicksuperk;
458 } else {
459 // Must check ClassCircularity before checking if superclass is already loaded.
460 PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
461 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
462 log_circularity_error(class_name, probe);
463 throw_circularity_error = true;
464 }
465 }
466
467 if (!throw_circularity_error) {
468 // Be careful not to exit resolve_super without removing this placeholder.
469 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
470 loader_data,
471 PlaceholderTable::LOAD_SUPER,
472 super_name, THREAD);
473 }
474 }
475
476 if (throw_circularity_error) {
477 ResourceMark rm(THREAD);
478 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
479 }
480
481 // Resolve the superclass or superinterface, check results on return
482 InstanceKlass* superk =
483 SystemDictionary::resolve_instance_class_or_null(super_name,
484 class_loader,
485 protection_domain,
486 THREAD);
487
488 // Clean up placeholder entry.
489 {
490 MutexLocker mu(THREAD, SystemDictionary_lock);
491 PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
492 SystemDictionary_lock->notify_all();
493 }
494
495 // Check for pending exception or null superk, and throw exception
496 if (HAS_PENDING_EXCEPTION || superk == nullptr) {
497 handle_resolution_exception(super_name, true, CHECK_NULL);
498 }
499
500 return superk;
501 }
502
503 Klass* SystemDictionary::resolve_inline_type_field_or_fail(Symbol* signature,
504 Handle class_loader,
505 Handle protection_domain,
506 bool throw_error,
507 TRAPS) {
508 Symbol* class_name = signature->fundamental_name(THREAD);
509 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
510 ClassLoaderData* loader_data = class_loader_data(class_loader);
511 bool throw_circularity_error = false;
512 PlaceholderEntry* oldprobe;
513
514 {
515 MutexLocker mu(THREAD, SystemDictionary_lock);
516 oldprobe = PlaceholderTable::get_entry(class_name, loader_data);
517 if (oldprobe != nullptr &&
518 oldprobe->check_seen_thread(THREAD, PlaceholderTable::PRIMITIVE_OBJECT_FIELD)) {
519 throw_circularity_error = true;
520
521 } else {
522 PlaceholderTable::find_and_add(class_name, loader_data,
523 PlaceholderTable::PRIMITIVE_OBJECT_FIELD, nullptr, THREAD);
524 }
525 }
526
527 Klass* klass = nullptr;
528 if (!throw_circularity_error) {
529 klass = SystemDictionary::resolve_or_fail(class_name, class_loader,
530 protection_domain, true, THREAD);
531 } else {
532 ResourceMark rm(THREAD);
533 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
534 }
535
536 {
537 MutexLocker mu(THREAD, SystemDictionary_lock);
538 PlaceholderTable::find_and_remove(class_name, loader_data,
539 PlaceholderTable::PRIMITIVE_OBJECT_FIELD, THREAD);
540 }
541
542 class_name->decrement_refcount();
543 return klass;
544 }
545
546 // If the class in is in the placeholder table, class loading is in progress.
547 // For cases where the application changes threads to load classes, it
548 // is critical to ClassCircularity detection that we try loading
549 // the superclass on the new thread internally, so we do parallel
550 // superclass loading here. This avoids deadlock for ClassCircularity
551 // detection for parallelCapable class loaders that lock on a per-class lock.
552 static void handle_parallel_super_load(Symbol* name,
553 Symbol* superclassname,
554 Handle class_loader,
555 Handle protection_domain, TRAPS) {
556
557 // superk is not used; resolve_super_or_fail is called for circularity check only.
558 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
559 superclassname,
560 class_loader,
561 protection_domain,
562 true,
563 CHECK);
564 }
565
566 // Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
567 // wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
568 static bool needs_load_placeholder(Handle class_loader) {
569 return class_loader.is_null() || !is_parallelCapable(class_loader);
570 }
571
572 // Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
573 static InstanceKlass* handle_parallel_loading(JavaThread* current,
574 Symbol* name,
575 ClassLoaderData* loader_data,
576 bool must_wait_for_class_loading,
577 bool* throw_circularity_error) {
578 PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
579 if (oldprobe != nullptr) {
580 // -Xcomp calls load_signature_classes which might result in loading
581 // a class that's already in the process of loading, so we detect CCE here also.
582 // Only need check_seen_thread once, not on each loop
583 if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {
584 log_circularity_error(name, oldprobe);
585 *throw_circularity_error = true;
586 return nullptr;
587 } else if (must_wait_for_class_loading) {
588 // Wait until the first thread has finished loading this class. Also wait until all the
589 // threads trying to load its superclass have removed their placeholders.
590 while (oldprobe != nullptr &&
591 (oldprobe->instance_load_in_progress() || oldprobe->super_load_in_progress())) {
592
593 // LOAD_INSTANCE placeholders are used to implement parallel capable class loading
594 // for the bootclass loader.
595 SystemDictionary_lock->wait();
596
597 // Check if classloading completed while we were waiting
598 InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
599 if (check != nullptr) {
600 // Klass is already loaded, so just return it
601 return check;
602 }
603 // check if other thread failed to load and cleaned up
604 oldprobe = PlaceholderTable::get_entry(name, loader_data);
605 }
606 }
607 }
608 return nullptr;
609 }
610
611 void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
612 assert(event != nullptr, "invariant");
613 assert(k != nullptr, "invariant");
614 event->set_loadedClass(k);
615 event->set_definingClassLoader(k->class_loader_data());
616 event->set_initiatingClassLoader(init_cld);
617 event->commit();
618 }
619
620 // SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
621 // After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
622 // whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
623 // which will load the class via the bootstrap loader or call ClassLoader.loadClass().
624 // This can return null, an exception or an InstanceKlass.
625 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
626 Handle class_loader,
627 Handle protection_domain,
628 TRAPS) {
629 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
630 assert(name != nullptr && !Signature::is_array(name) &&
631 !Signature::has_envelope(name), "invalid class name: %s", name == nullptr ? "nullptr" : name->as_C_string());
632
633 EventClassLoad class_load_start_event;
634
635 HandleMark hm(THREAD);
636
637 // Fix for 4474172; see evaluation for more details
638 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
639 ClassLoaderData* loader_data = register_loader(class_loader);
640 Dictionary* dictionary = loader_data->dictionary();
641
642 // Do lookup to see if class already exists and the protection domain
643 // has the right access.
644 // This call uses find which checks protection domain already matches
645 // All subsequent calls use find_class, and set loaded_class so that
646 // before we return a result, we call out to java to check for valid protection domain.
647 InstanceKlass* probe = dictionary->find(THREAD, name, protection_domain);
648 if (probe != nullptr) return probe;
649
650 // Non-bootstrap class loaders will call out to class loader and
651 // define via jvm/jni_DefineClass which will acquire the
652 // class loader object lock to protect against multiple threads
653 // defining the class in parallel by accident.
654 // This lock must be acquired here so the waiter will find
655 // any successful result in the SystemDictionary and not attempt
656 // the define.
657 // ParallelCapable class loaders and the bootstrap classloader
658 // do not acquire lock here.
659 Handle lockObject = get_loader_lock_or_null(class_loader);
660 ObjectLocker ol(lockObject, THREAD);
661
662 bool super_load_in_progress = false;
663 InstanceKlass* loaded_class = nullptr;
664 SymbolHandle superclassname; // Keep alive while loading in parallel thread.
665
666 assert(THREAD->can_call_java(),
667 "can not load classes with compiler thread: class=%s, classloader=%s",
668 name->as_C_string(),
669 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
670
671 // Check again (after locking) if the class already exists in SystemDictionary
672 {
673 MutexLocker mu(THREAD, SystemDictionary_lock);
674 InstanceKlass* check = dictionary->find_class(THREAD, name);
675 if (check != nullptr) {
676 // InstanceKlass is already loaded, but we still need to check protection domain below.
677 loaded_class = check;
678 } else {
679 PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
680 if (placeholder != nullptr && placeholder->super_load_in_progress()) {
681 super_load_in_progress = true;
682 superclassname = placeholder->supername();
683 assert(superclassname != nullptr, "superclass has to have a name");
684 }
685 }
686 }
687
688 // If the class is in the placeholder table with super_class set,
689 // handle superclass loading in progress.
690 if (super_load_in_progress) {
691 handle_parallel_super_load(name, superclassname,
692 class_loader,
693 protection_domain,
694 CHECK_NULL);
695 }
696
697 bool throw_circularity_error = false;
698 if (loaded_class == nullptr) {
699 bool load_placeholder_added = false;
700
701 // Add placeholder entry to record loading instance class
702 // case 1. Bootstrap classloader
703 // This classloader supports parallelism at the classloader level
704 // but only allows a single thread to load a class/classloader pair.
705 // The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
706 // case 2. parallelCapable user level classloaders
707 // These class loaders lock a per-class object lock when ClassLoader.loadClass()
708 // is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
709 // case 3. traditional classloaders that rely on the classloader object lock
710 // There should be no need for need for LOAD_INSTANCE for mutual exclusion,
711 // except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
712 // TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
713 {
714 MutexLocker mu(THREAD, SystemDictionary_lock);
715 if (needs_load_placeholder(class_loader)) {
716 loaded_class = handle_parallel_loading(THREAD,
717 name,
718 loader_data,
719 class_loader.is_null(),
720 &throw_circularity_error);
721 }
722
723 // Recheck if the class has been loaded for all class loader cases and
724 // add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
725 if (!throw_circularity_error && loaded_class == nullptr) {
726 InstanceKlass* check = dictionary->find_class(THREAD, name);
727 if (check != nullptr) {
728 loaded_class = check;
729 } else if (needs_load_placeholder(class_loader)) {
730 // Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
731 PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
732 PlaceholderTable::LOAD_INSTANCE,
733 nullptr,
734 THREAD);
735 load_placeholder_added = true;
736 }
737 }
738 }
739
740 // Must throw error outside of owning lock
741 if (throw_circularity_error) {
742 assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
743 ResourceMark rm(THREAD);
744 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
745 }
746
747 // Be careful when modifying this code: once you have run
748 // PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
749 // you need to find_and_remove it before returning.
750 // So be careful to not exit with a CHECK_ macro between these calls.
751
752 if (loaded_class == nullptr) {
753 // Do actual loading
754 loaded_class = load_instance_class(name, class_loader, THREAD);
755 }
756
757 if (load_placeholder_added) {
758 // clean up placeholder entries for LOAD_INSTANCE success or error
759 // This brackets the SystemDictionary updates for both defining
760 // and initiating loaders
761 MutexLocker mu(THREAD, SystemDictionary_lock);
762 PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
763 SystemDictionary_lock->notify_all();
764 }
765 }
766
767 if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {
768 return nullptr;
769 }
770
771 if (class_load_start_event.should_commit()) {
772 post_class_load_event(&class_load_start_event, loaded_class, loader_data);
773 }
774
775 // Make sure we have the right class in the dictionary
776 DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
777
778 // Check if the protection domain is present it has the right access
779 if (protection_domain() != nullptr) {
780 // Verify protection domain. If it fails an exception is thrown
781 dictionary->validate_protection_domain(loaded_class, class_loader, protection_domain, CHECK_NULL);
782 }
783
784 return loaded_class;
785 }
786
787
788 // This routine does not lock the system dictionary.
789 //
790 // Since readers don't hold a lock, we must make sure that system
791 // dictionary entries are added to in a safe way (all links must
792 // be updated in an MT-safe manner). All entries are removed during class
793 // unloading, when this class loader is no longer referenced.
794 //
795 // Callers should be aware that an entry could be added just after
796 // Dictionary is read here, so the caller will not see
797 // the new entry.
798
799 InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
800 Symbol* class_name,
801 Handle class_loader,
802 Handle protection_domain) {
803
804 // The result of this call should be consistent with the result
805 // of the call to resolve_instance_class_or_null().
806 // See evaluation 6790209 and 4474172 for more details.
807 oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
808 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
809
810 if (loader_data == nullptr) {
811 // If the ClassLoaderData has not been setup,
812 // then the class loader has no entries in the dictionary.
813 return nullptr;
814 }
815
816 Dictionary* dictionary = loader_data->dictionary();
817 return dictionary->find(current, class_name, protection_domain);
818 }
819
820 // Look for a loaded instance or array klass by name. Do not do any loading.
821 // return null in case of error.
822 Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
823 Symbol* class_name,
824 Handle class_loader,
825 Handle protection_domain) {
826 Klass* k = nullptr;
827 assert(class_name != nullptr, "class name must be non nullptr");
828
829 if (Signature::is_array(class_name)) {
830 // The name refers to an array. Parse the name.
831 // dimension and object_key in FieldArrayInfo are assigned as a
832 // side-effect of this call
833 SignatureStream ss(class_name, false);
834 int ndims = ss.skip_array_prefix(); // skip all '['s
835 BasicType t = ss.type();
836 if (t != T_OBJECT && t != T_PRIMITIVE_OBJECT) {
837 k = Universe::typeArrayKlassObj(t);
838 } else {
839 k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader, protection_domain);
840 }
841 if (k != nullptr) {
842 if (class_name->is_Q_array_signature()) {
843 k = InlineKlass::cast(k)->value_array_klass_or_null(ndims);
844 } else {
845 k = k->array_klass_or_null(ndims);
846 }
847 }
848 } else {
849 k = find_instance_klass(current, class_name, class_loader, protection_domain);
850 }
851 return k;
852 }
853
854 // Note: this method is much like resolve_class_from_stream, but
855 // does not publish the classes in the SystemDictionary.
856 // Handles Lookup.defineClass hidden.
857 InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
858 ClassFileStream* st,
859 Symbol* class_name,
860 Handle class_loader,
861 const ClassLoadInfo& cl_info,
862 TRAPS) {
863
864 EventClassLoad class_load_start_event;
865 ClassLoaderData* loader_data;
866
867 // - for hidden classes that are not strong: create a new CLD that has a class holder and
868 // whose loader is the Lookup class's loader.
869 // - for hidden class: add the class to the Lookup class's loader's CLD.
870 assert (cl_info.is_hidden(), "only used for hidden classes");
871 bool create_mirror_cld = !cl_info.is_strong_hidden();
872 loader_data = register_loader(class_loader, create_mirror_cld);
873
874 assert(st != nullptr, "invariant");
875 assert(st->need_verify(), "invariant");
876
877 // Parse stream and create a klass.
878 InstanceKlass* k = KlassFactory::create_from_stream(st,
879 class_name,
880 loader_data,
881 cl_info,
882 CHECK_NULL);
883 assert(k != nullptr, "no klass created");
884
885 // Hidden classes that are not strong must update ClassLoaderData holder
886 // so that they can be unloaded when the mirror is no longer referenced.
887 if (!cl_info.is_strong_hidden()) {
888 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
889 }
890
891 // Add to class hierarchy, and do possible deoptimizations.
892 k->add_to_hierarchy(THREAD);
893 // But, do not add to dictionary.
894
895 k->link_class(CHECK_NULL);
896
897 // notify jvmti
898 if (JvmtiExport::should_post_class_load()) {
899 JvmtiExport::post_class_load(THREAD, k);
900 }
901 if (class_load_start_event.should_commit()) {
902 post_class_load_event(&class_load_start_event, k, loader_data);
903 }
904
905 return k;
906 }
907
908 // Add a klass to the system from a stream (called by jni_DefineClass and
909 // JVM_DefineClass).
910 // Note: class_name can be null. In that case we do not know the name of
911 // the class until we have parsed the stream.
912 // This function either returns an InstanceKlass or throws an exception. It does
913 // not return null without a pending exception.
914 InstanceKlass* SystemDictionary::resolve_class_from_stream(
915 ClassFileStream* st,
916 Symbol* class_name,
917 Handle class_loader,
918 const ClassLoadInfo& cl_info,
919 TRAPS) {
920
921 HandleMark hm(THREAD);
922
923 ClassLoaderData* loader_data = register_loader(class_loader);
924
925 // Classloaders that support parallelism, e.g. bootstrap classloader,
926 // do not acquire lock here
927 Handle lockObject = get_loader_lock_or_null(class_loader);
928 ObjectLocker ol(lockObject, THREAD);
929
930 // Parse the stream and create a klass.
931 // Note that we do this even though this klass might
932 // already be present in the SystemDictionary, otherwise we would not
933 // throw potential ClassFormatErrors.
934 InstanceKlass* k = nullptr;
935
936 #if INCLUDE_CDS
937 if (!DumpSharedSpaces) {
938 k = SystemDictionaryShared::lookup_from_stream(class_name,
939 class_loader,
940 cl_info.protection_domain(),
941 st,
942 CHECK_NULL);
943 }
944 #endif
945
946 if (k == nullptr) {
947 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
948 }
949
950 assert(k != nullptr, "no klass created");
951 Symbol* h_name = k->name();
952 assert(class_name == nullptr || class_name == h_name, "name mismatch");
953
954 // Add class just loaded
955 // If a class loader supports parallel classloading, handle parallel define requests.
956 // find_or_define_instance_class may return a different InstanceKlass,
957 // in which case the old k would be deallocated
958 if (is_parallelCapable(class_loader)) {
959 k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
960 } else {
961 define_instance_class(k, class_loader, THREAD);
962
963 // If defining the class throws an exception register 'k' for cleanup.
964 if (HAS_PENDING_EXCEPTION) {
965 assert(k != nullptr, "Must have an instance klass here!");
966 loader_data->add_to_deallocate_list(k);
967 return nullptr;
968 }
969 }
970
971 // Make sure we have an entry in the SystemDictionary on success
972 DEBUG_ONLY(verify_dictionary_entry(h_name, k));
973
974 return k;
975 }
976
977 InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
978 Symbol* class_name,
979 Handle class_loader,
980 const ClassLoadInfo& cl_info,
981 TRAPS) {
982 if (cl_info.is_hidden()) {
983 return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
984 } else {
985 return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
986 }
987 }
988
989
990 #if INCLUDE_CDS
991 // Check if a shared class can be loaded by the specific classloader.
992 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
993 InstanceKlass* ik,
994 PackageEntry* pkg_entry,
995 Handle class_loader) {
996 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
997 "Cannot use sharing if java.base is patched");
998
999 // (1) Check if we are loading into the same loader as in dump time.
1000
1001 if (ik->is_shared_boot_class()) {
1002 if (class_loader() != nullptr) {
1003 return false;
1004 }
1005 } else if (ik->is_shared_platform_class()) {
1006 if (class_loader() != java_platform_loader()) {
1007 return false;
1008 }
1009 } else if (ik->is_shared_app_class()) {
1010 if (class_loader() != java_system_loader()) {
1011 return false;
1012 }
1013 } else {
1014 // ik was loaded by a custom loader during dump time
1015 if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {
1016 return false;
1017 } else {
1018 return true;
1019 }
1020 }
1021
1022 // (2) Check if we are loading into the same module from the same location as in dump time.
1023
1024 if (MetaspaceShared::use_optimized_module_handling()) {
1025 // Class visibility has not changed between dump time and run time, so a class
1026 // that was visible (and thus archived) during dump time is always visible during runtime.
1027 assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
1028 "visibility cannot change between dump time and runtime");
1029 return true;
1030 }
1031 return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
1032 }
1033
1034 bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
1035 InstanceKlass* ik,
1036 PackageEntry* pkg_entry,
1037 Handle class_loader) {
1038 int scp_index = ik->shared_classpath_index();
1039 assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
1040 assert(scp_index >= 0, "must be");
1041 SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
1042 if (!Universe::is_module_initialized()) {
1043 assert(scp_entry != nullptr, "must be");
1044 // At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
1045 // has restricted the classes can be loaded at this step to be only:
1046 // [1] scp_entry->is_modules_image(): classes in java.base, or,
1047 // [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
1048 assert(scp_entry->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
1049 "only these classes can be loaded before the module system is initialized");
1050 assert(class_loader.is_null(), "sanity");
1051 return true;
1052 }
1053
1054 if (pkg_entry == nullptr) {
1055 // We might have looked up pkg_entry before the module system was initialized.
1056 // Need to reload it now.
1057 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1058 if (pkg_name != nullptr) {
1059 pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1060 }
1061 }
1062
1063 ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1064 bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1065 bool was_archived_from_named_module = scp_entry->in_named_module();
1066 bool visible;
1067
1068 if (was_archived_from_named_module) {
1069 if (should_be_in_named_module) {
1070 // Is the module loaded from the same location as during dump time?
1071 visible = mod_entry->shared_path_index() == scp_index;
1072 if (visible) {
1073 assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1074 }
1075 } else {
1076 // During dump time, this class was in a named module, but at run time, this class should be
1077 // in an unnamed module.
1078 visible = false;
1079 }
1080 } else {
1081 if (should_be_in_named_module) {
1082 // During dump time, this class was in an unnamed, but at run time, this class should be
1083 // in a named module.
1084 visible = false;
1085 } else {
1086 visible = true;
1087 }
1088 }
1089
1090 return visible;
1091 }
1092
1093 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1094 Handle class_loader, Handle protection_domain,
1095 bool is_superclass, TRAPS) {
1096 assert(super_type->is_shared(), "must be");
1097
1098 // Quick check if the super type has been already loaded.
1099 // + Don't do it for unregistered classes -- they can be unloaded so
1100 // super_type->class_loader_data() could be stale.
1101 // + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1102 if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {
1103 // Check if the superclass is loaded by the current class_loader
1104 Symbol* name = super_type->name();
1105 InstanceKlass* check = find_instance_klass(THREAD, name, class_loader, protection_domain);
1106 if (check == super_type) {
1107 return true;
1108 }
1109 }
1110
1111 Klass *found = resolve_super_or_fail(klass->name(), super_type->name(),
1112 class_loader, protection_domain, is_superclass, CHECK_0);
1113 if (found == super_type) {
1114 return true;
1115 } else {
1116 // The dynamically resolved super type is not the same as the one we used during dump time,
1117 // so we cannot use the class.
1118 return false;
1119 }
1120 }
1121
1122 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1123 Handle protection_domain, TRAPS) {
1124 // Check the superclass and interfaces. They must be the same
1125 // as in dump time, because the layout of <ik> depends on
1126 // the specific layout of ik->super() and ik->local_interfaces().
1127 //
1128 // If unexpected superclass or interfaces are found, we cannot
1129 // load <ik> from the shared archive.
1130
1131 if (ik->super() != nullptr &&
1132 !check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1133 class_loader, protection_domain, true, THREAD)) {
1134 return false;
1135 }
1136
1137 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1138 int num_interfaces = interfaces->length();
1139 for (int index = 0; index < num_interfaces; index++) {
1140 if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) {
1141 return false;
1142 }
1143 }
1144
1145 return true;
1146 }
1147
1148 InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1149 Handle class_loader,
1150 Handle protection_domain,
1151 PackageEntry* pkg_entry,
1152 TRAPS) {
1153 InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1154 assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1155 Symbol* cn = shared_nest_host->name();
1156 Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1157 if (s != shared_nest_host) {
1158 // The dynamically resolved nest_host is not the same as the one we used during dump time,
1159 // so we cannot use ik.
1160 return nullptr;
1161 } else {
1162 assert(s->is_shared(), "must be");
1163 }
1164
1165 InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, nullptr, pkg_entry, CHECK_NULL);
1166
1167 if (loaded_ik != nullptr) {
1168 assert(shared_nest_host->is_same_class_package(ik),
1169 "lambda proxy class and its nest host must be in the same package");
1170 }
1171
1172 // The lambda proxy class and its nest host have the same class loader and class loader data,
1173 // as verified in SystemDictionaryShared::add_lambda_proxy_class()
1174 assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1175 assert(shared_nest_host->class_loader_data() == class_loader_data(class_loader), "mismatched class loader data");
1176 ik->set_nest_host(shared_nest_host);
1177
1178 return loaded_ik;
1179 }
1180
1181 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1182 Handle class_loader,
1183 Handle protection_domain,
1184 const ClassFileStream *cfs,
1185 PackageEntry* pkg_entry,
1186 TRAPS) {
1187 assert(ik != nullptr, "sanity");
1188 assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1189 assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1190 Symbol* class_name = ik->name();
1191
1192 if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {
1193 return nullptr;
1194 }
1195
1196 if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {
1197 return nullptr;
1198 }
1199
1200
1201 if (ik->has_inline_type_fields()) {
1202 for (AllFieldStream fs(ik); !fs.done(); fs.next()) {
1203 Symbol* sig = fs.signature();
1204 if (fs.is_null_free_inline_type()) {
1205 if (!fs.access_flags().is_static()) {
1206 // Pre-load inline class
1207 Klass* real_k = SystemDictionary::resolve_inline_type_field_or_fail(sig,
1208 class_loader, protection_domain, true, CHECK_NULL);
1209 Klass* k = ik->get_inline_type_field_klass_or_null(fs.index());
1210 if (real_k != k) {
1211 // oops, the app has substituted a different version of k!
1212 return nullptr;
1213 }
1214 }
1215 }
1216 }
1217 }
1218
1219 InstanceKlass* new_ik = nullptr;
1220 // CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1221 // It will be skipped for shared VM hidden lambda proxy classes.
1222 if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {
1223 new_ik = KlassFactory::check_shared_class_file_load_hook(
1224 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1225 }
1226 if (new_ik != nullptr) {
1227 // The class is changed by CFLH. Return the new class. The shared class is
1228 // not used.
1229 return new_ik;
1230 }
1231
1232 // Adjust methods to recover missing data. They need addresses for
1233 // interpreter entry points and their default native method address
1234 // must be reset.
1235
1236 // Shared classes are all currently loaded by either the bootstrap or
1237 // internal parallel class loaders, so this will never cause a deadlock
1238 // on a custom class loader lock.
1239 // Since this class is already locked with parallel capable class
1240 // loaders, including the bootstrap loader via the placeholder table,
1241 // this lock is currently a nop.
1242
1243 ClassLoaderData* loader_data = class_loader_data(class_loader);
1244 {
1245 HandleMark hm(THREAD);
1246 Handle lockObject = get_loader_lock_or_null(class_loader);
1247 ObjectLocker ol(lockObject, THREAD);
1248 // prohibited package check assumes all classes loaded from archive call
1249 // restore_unshareable_info which calls ik->set_package()
1250 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1251 }
1252
1253 load_shared_class_misc(ik, loader_data);
1254
1255 return ik;
1256 }
1257
1258 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {
1259 ik->print_class_load_logging(loader_data, nullptr, nullptr);
1260
1261 // For boot loader, ensure that GetSystemPackage knows that a class in this
1262 // package was loaded.
1263 if (loader_data->is_the_null_class_loader_data()) {
1264 s2 path_index = ik->shared_classpath_index();
1265 ik->set_classpath_index(path_index);
1266 }
1267
1268 // notify a class loaded from shared object
1269 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
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 (UseSharedSpaces)
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, 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 assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1605 k->class_loader_data()->add_to_deallocate_list(k);
1606 }
1607 return defined_k;
1608 }
1609
1610
1611 // ----------------------------------------------------------------------------
1612 // GC support
1613
1614 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1615 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1616
1617 bool unloading_occurred;
1618 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1619 {
1620 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1621 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1622 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1623 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1624 if (unloading_occurred) {
1625 MutexLocker ml2(is_concurrent ? Module_lock : nullptr);
1626 JFR_ONLY(Jfr::on_unloading_classes();)
1627 MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1628 MutexLocker ml1(is_concurrent ? SystemDictionary_lock : nullptr);
1629 ClassLoaderDataGraph::clean_module_and_package_info();
1630 LoaderConstraintTable::purge_loader_constraints();
1631 ResolutionErrorTable::purge_resolution_errors();
1632 }
1633 }
1634
1635 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1636
1637 if (unloading_occurred) {
1638 SymbolTable::trigger_cleanup();
1639
1640 if (java_lang_System::allow_security_manager()) {
1641 // Oops referenced by the protection domain cache table may get unreachable independently
1642 // of the class loader (eg. cached protection domain oops). So we need to
1643 // explicitly unlink them here.
1644 // All protection domain oops are linked to the caller class, so if nothing
1645 // unloads, this is not needed.
1646 ProtectionDomainCacheTable::trigger_cleanup();
1647 } else {
1648 assert(ProtectionDomainCacheTable::number_of_entries() == 0, "should be empty");
1649 }
1650
1651 MutexLocker ml(is_concurrent ? ClassInitError_lock : nullptr);
1652 InstanceKlass::clean_initialization_error_table();
1653 }
1654
1655 return unloading_occurred;
1656 }
1657
1658 void SystemDictionary::methods_do(void f(Method*)) {
1659 // Walk methods in loaded classes
1660
1661 {
1662 MutexLocker ml(ClassLoaderDataGraph_lock);
1663 ClassLoaderDataGraph::methods_do(f);
1664 }
1665
1666 auto doit = [&] (InvokeMethodKey key, Method* method) {
1667 if (method != nullptr) {
1668 f(method);
1669 }
1670 };
1671
1672 {
1673 MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1674 _invoke_method_intrinsic_table->iterate_all(doit);
1675 }
1676
1677 }
1678
1679 // ----------------------------------------------------------------------------
1680 // Initialization
1681
1682 void SystemDictionary::initialize(TRAPS) {
1683 _invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1684 _invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1685 ResolutionErrorTable::initialize();
1686 LoaderConstraintTable::initialize();
1687 PlaceholderTable::initialize();
1688 ProtectionDomainCacheTable::initialize();
1689 #if INCLUDE_CDS
1690 SystemDictionaryShared::initialize();
1691 #endif
1692 // Resolve basic classes
1693 vmClasses::resolve_all(CHECK);
1694 // Resolve classes used by archived heap objects
1695 if (UseSharedSpaces) {
1696 HeapShared::resolve_classes(THREAD);
1697 }
1698 }
1699
1700 // Constraints on class loaders. The details of the algorithm can be
1701 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1702 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1703 // that the dictionary needs to maintain a set of constraints that
1704 // must be satisfied by all classes in the dictionary.
1705 // if defining is true, then LinkageError if already in dictionary
1706 // if initiating loader, then ok if InstanceKlass matches existing entry
1707
1708 void SystemDictionary::check_constraints(InstanceKlass* k,
1709 ClassLoaderData* loader_data,
1710 bool defining,
1711 TRAPS) {
1712 ResourceMark rm(THREAD);
1713 stringStream ss;
1714 bool throwException = false;
1715
1716 {
1717 Symbol* name = k->name();
1718
1719 MutexLocker mu(THREAD, SystemDictionary_lock);
1720
1721 InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1722 if (check != nullptr) {
1723 // If different InstanceKlass - duplicate class definition,
1724 // else - ok, class loaded by a different thread in parallel.
1725 // We should only have found it if it was done loading and ok to use.
1726
1727 if ((defining == true) || (k != check)) {
1728 throwException = true;
1729 ss.print("loader %s", loader_data->loader_name_and_id());
1730 ss.print(" attempted duplicate %s definition for %s. (%s)",
1731 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1732 } else {
1733 return;
1734 }
1735 }
1736
1737 if (throwException == false) {
1738 if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {
1739 throwException = true;
1740 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
1741 ss.print(" wants to load %s %s.",
1742 k->external_kind(), k->external_name());
1743 Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1744 if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {
1745 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
1746 existing_klass->external_kind(),
1747 existing_klass->class_loader_data()->loader_name_and_id(),
1748 existing_klass->class_in_module_of_loader(false, true));
1749 } else {
1750 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
1751 }
1752 }
1753 }
1754 }
1755
1756 // Throw error now if needed (cannot throw while holding
1757 // SystemDictionary_lock because of rank ordering)
1758 if (throwException == true) {
1759 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1760 }
1761 }
1762
1763 // Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1764 // have been called.
1765 void SystemDictionary::update_dictionary(JavaThread* current,
1766 InstanceKlass* k,
1767 ClassLoaderData* loader_data) {
1768 MonitorLocker mu1(SystemDictionary_lock);
1769
1770 // Make a new dictionary entry.
1771 Symbol* name = k->name();
1772 Dictionary* dictionary = loader_data->dictionary();
1773 InstanceKlass* sd_check = dictionary->find_class(current, name);
1774 if (sd_check == nullptr) {
1775 dictionary->add_klass(current, name, k);
1776 }
1777 mu1.notify_all();
1778 }
1779
1780
1781 // Try to find a class name using the loader constraints. The
1782 // loader constraints might know about a class that isn't fully loaded
1783 // yet and these will be ignored.
1784 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1785 Thread* current, Symbol* class_name, Handle class_loader) {
1786
1787 // First see if it has been loaded directly.
1788 // Force the protection domain to be null. (This removes protection checks.)
1789 Handle no_protection_domain;
1790 Klass* klass = find_instance_or_array_klass(current, class_name, class_loader,
1791 no_protection_domain);
1792 if (klass != nullptr)
1793 return klass;
1794
1795 // Now look to see if it has been loaded elsewhere, and is subject to
1796 // a loader constraint that would require this loader to return the
1797 // klass that is already loaded.
1798 if (Signature::is_array(class_name)) {
1799 // For array classes, their Klass*s are not kept in the
1800 // constraint table. The element Klass*s are.
1801 SignatureStream ss(class_name, false);
1802 int ndims = ss.skip_array_prefix(); // skip all '['s
1803 BasicType t = ss.type();
1804 if (t != T_OBJECT && t != T_PRIMITIVE_OBJECT) {
1805 klass = Universe::typeArrayKlassObj(t);
1806 } else {
1807 MutexLocker mu(current, SystemDictionary_lock);
1808 klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1809 }
1810 // If element class already loaded, allocate array klass
1811 if (klass != nullptr) {
1812 if (class_name->is_Q_array_signature()) {
1813 klass = InlineKlass::cast(klass)->value_array_klass_or_null(ndims);
1814 } else {
1815 klass = klass->array_klass_or_null(ndims);
1816 }
1817 }
1818 } else {
1819 MutexLocker mu(current, SystemDictionary_lock);
1820 // Non-array classes are easy: simply check the constraint table.
1821 klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1822 }
1823
1824 return klass;
1825 }
1826
1827 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1828 Klass* klass_being_linked,
1829 Handle class_loader1,
1830 Handle class_loader2) {
1831 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1832 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1833
1834 Symbol* constraint_name = nullptr;
1835
1836 if (!Signature::is_array(class_name)) {
1837 constraint_name = class_name;
1838 } else {
1839 // For array classes, their Klass*s are not kept in the
1840 // constraint table. The element classes are.
1841 SignatureStream ss(class_name, false);
1842 ss.skip_array_prefix(); // skip all '['s
1843 if (!ss.has_envelope()) {
1844 return true; // primitive types always pass
1845 }
1846 constraint_name = ss.as_symbol();
1847 // Increment refcount to keep constraint_name alive after
1848 // SignatureStream is destructed. It will be decremented below
1849 // before returning.
1850 constraint_name->increment_refcount();
1851 }
1852
1853 Dictionary* dictionary1 = loader_data1->dictionary();
1854 Dictionary* dictionary2 = loader_data2->dictionary();
1855
1856 JavaThread* current = JavaThread::current();
1857 {
1858 MutexLocker mu_s(SystemDictionary_lock);
1859 InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1860 InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1861 bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1862 klass2, loader_data2);
1863 #if INCLUDE_CDS
1864 if (Arguments::is_dumping_archive() && klass_being_linked != nullptr &&
1865 !klass_being_linked->is_shared()) {
1866 SystemDictionaryShared::record_linking_constraint(constraint_name,
1867 InstanceKlass::cast(klass_being_linked),
1868 class_loader1, class_loader2);
1869 }
1870 #endif // INCLUDE_CDS
1871 if (Signature::is_array(class_name)) {
1872 constraint_name->decrement_refcount();
1873 }
1874 return result;
1875 }
1876 }
1877
1878 // Add entry to resolution error table to record the error when the first
1879 // attempt to resolve a reference to a class has failed.
1880 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1881 Symbol* error, Symbol* message,
1882 Symbol* cause, Symbol* cause_msg) {
1883 {
1884 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1885 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1886 if (entry == nullptr) {
1887 ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1888 }
1889 }
1890 }
1891
1892 // Delete a resolution error for RedefineClasses for a constant pool is going away
1893 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
1894 ResolutionErrorTable::delete_entry(pool);
1895 }
1896
1897 // Lookup resolution error table. Returns error if found, otherwise null.
1898 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1899 Symbol** message, Symbol** cause, Symbol** cause_msg) {
1900
1901 {
1902 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1903 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1904 if (entry != nullptr) {
1905 *message = entry->message();
1906 *cause = entry->cause();
1907 *cause_msg = entry->cause_msg();
1908 return entry->error();
1909 } else {
1910 return nullptr;
1911 }
1912 }
1913 }
1914
1915 // Add an entry to resolution error table to record an error in resolving or
1916 // validating a nest host. This is used to construct informative error
1917 // messages when IllegalAccessError's occur. If an entry already exists it will
1918 // be updated with the nest host error message.
1919
1920 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1921 int which,
1922 const char* message) {
1923 {
1924 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1925 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1926 if (entry != nullptr && entry->nest_host_error() == nullptr) {
1927 // An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1928 // still want to add the error message for the higher-level access checks to report. We should
1929 // only reach here under the same error condition, so we can ignore the potential race with setting
1930 // the message. If we see it is already set then we can ignore it.
1931 entry->set_nest_host_error(message);
1932 } else {
1933 ResolutionErrorTable::add_entry(pool, which, message);
1934 }
1935 }
1936 }
1937
1938 // Lookup any nest host error
1939 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
1940 {
1941 MutexLocker ml(Thread::current(), SystemDictionary_lock);
1942 ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1943 if (entry != nullptr) {
1944 return entry->nest_host_error();
1945 } else {
1946 return nullptr;
1947 }
1948 }
1949 }
1950
1951 // Signature constraints ensure that callers and callees agree about
1952 // the meaning of type names in their signatures. This routine is the
1953 // intake for constraints. It collects them from several places:
1954 //
1955 // * LinkResolver::resolve_method (if check_access is true) requires
1956 // that the resolving class (the caller) and the defining class of
1957 // the resolved method (the callee) agree on each type in the
1958 // method's signature.
1959 //
1960 // * LinkResolver::resolve_interface_method performs exactly the same
1961 // checks.
1962 //
1963 // * LinkResolver::resolve_field requires that the constant pool
1964 // attempting to link to a field agree with the field's defining
1965 // class about the type of the field signature.
1966 //
1967 // * klassVtable::initialize_vtable requires that, when a class
1968 // overrides a vtable entry allocated by a superclass, that the
1969 // overriding method (i.e., the callee) agree with the superclass
1970 // on each type in the method's signature.
1971 //
1972 // * klassItable::initialize_itable requires that, when a class fills
1973 // in its itables, for each non-abstract method installed in an
1974 // itable, the method (i.e., the callee) agree with the interface
1975 // on each type in the method's signature.
1976 //
1977 // All those methods have a boolean (check_access, checkconstraints)
1978 // which turns off the checks. This is used from specialized contexts
1979 // such as bootstrapping, dumping, and debugging.
1980 //
1981 // No direct constraint is placed between the class and its
1982 // supertypes. Constraints are only placed along linked relations
1983 // between callers and callees. When a method overrides or implements
1984 // an abstract method in a supertype (superclass or interface), the
1985 // constraints are placed as if the supertype were the caller to the
1986 // overriding method. (This works well, since callers to the
1987 // supertype have already established agreement between themselves and
1988 // the supertype.) As a result of all this, a class can disagree with
1989 // its supertype about the meaning of a type name, as long as that
1990 // class neither calls a relevant method of the supertype, nor is
1991 // called (perhaps via an override) from the supertype.
1992 //
1993 //
1994 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1995 //
1996 // Make sure all class components (including arrays) in the given
1997 // signature will be resolved to the same class in both loaders.
1998 // Returns the name of the type that failed a loader constraint check, or
1999 // null if no constraint failed. No exception except OOME is thrown.
2000 // Arrays are not added to the loader constraint table, their elements are.
2001 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2002 Klass* klass_being_linked,
2003 Handle loader1, Handle loader2,
2004 bool is_method) {
2005 // Nothing to do if loaders are the same.
2006 if (loader1() == loader2()) {
2007 return nullptr;
2008 }
2009
2010 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
2011 if (ss.is_reference()) {
2012 Symbol* sig = ss.as_symbol();
2013 // Note: In the future, if template-like types can take
2014 // arguments, we will want to recognize them and dig out class
2015 // names hiding inside the argument lists.
2016 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {
2017 return sig;
2018 }
2019 }
2020 }
2021 return nullptr;
2022 }
2023
2024 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
2025 Symbol* signature,
2026 TRAPS) {
2027
2028 const int iid_as_int = vmIntrinsics::as_int(iid);
2029 assert(MethodHandles::is_signature_polymorphic(iid) &&
2030 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2031 iid != vmIntrinsics::_invokeGeneric,
2032 "must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
2033
2034 InvokeMethodKey key(signature, iid_as_int);
2035 Method** met = nullptr;
2036
2037 // We only want one entry in the table for this (signature/id, method) pair but the code
2038 // to create the intrinsic method needs to be outside the lock.
2039 // The first thread claims the entry by adding the key and the other threads wait, until the
2040 // Method has been added as the value.
2041 {
2042 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2043 while (true) {
2044 bool created;
2045 met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
2046 assert(met != nullptr, "either created or found");
2047 if (*met != nullptr) {
2048 return *met;
2049 } else if (created) {
2050 // The current thread won the race and will try to create the full entry.
2051 break;
2052 } else {
2053 // Another thread beat us to it, so wait for them to complete
2054 // and return *met; or if they hit an error we get another try.
2055 ml.wait();
2056 // Note it is not safe to read *met here as that entry could have
2057 // been deleted, so we must loop and try put_if_absent again.
2058 }
2059 }
2060 }
2061
2062 methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
2063 bool throw_error = HAS_PENDING_EXCEPTION;
2064 if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {
2065 // Generate a compiled form of the MH intrinsic
2066 // linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
2067 AdapterHandlerLibrary::create_native_wrapper(m);
2068 // Check if have the compiled code.
2069 throw_error = (!m->has_compiled_code());
2070 }
2071
2072 {
2073 MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
2074 if (throw_error) {
2075 // Remove the entry and let another thread try, or get the same exception.
2076 bool removed = _invoke_method_intrinsic_table->remove(key);
2077 assert(removed, "must be the owner");
2078 ml.notify_all();
2079 } else {
2080 signature->make_permanent(); // The signature is never unloaded.
2081 assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2082 m->code()->entry_point() == m->from_compiled_entry()),
2083 "MH intrinsic invariant");
2084 *met = m(); // insert the element
2085 ml.notify_all();
2086 return m();
2087 }
2088 }
2089
2090 // Throw VirtualMachineError or the pending exception in the JavaThread
2091 if (throw_error && !HAS_PENDING_EXCEPTION) {
2092 THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
2093 "Out of space in CodeCache for method handle intrinsic");
2094 }
2095 return nullptr;
2096 }
2097
2098 // Helper for unpacking the return value from linkMethod and linkCallSite.
2099 static Method* unpack_method_and_appendix(Handle mname,
2100 Klass* accessing_klass,
2101 objArrayHandle appendix_box,
2102 Handle* appendix_result,
2103 TRAPS) {
2104 if (mname.not_null()) {
2105 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2106 if (m != nullptr) {
2107 oop appendix = appendix_box->obj_at(0);
2108 LogTarget(Info, methodhandles) lt;
2109 if (lt.develop_is_enabled()) {
2110 ResourceMark rm(THREAD);
2111 LogStream ls(lt);
2112 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2113 m->print_on(&ls);
2114 if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }
2115 ls.cr();
2116 }
2117
2118 (*appendix_result) = Handle(THREAD, appendix);
2119 // the target is stored in the cpCache and if a reference to this
2120 // MemberName is dropped we need a way to make sure the
2121 // class_loader containing this method is kept alive.
2122 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2123 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2124 this_key->record_dependency(m->method_holder());
2125 return mh();
2126 }
2127 }
2128 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2129 }
2130
2131 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2132 Symbol* name,
2133 Symbol* signature,
2134 Klass* accessing_klass,
2135 Handle* appendix_result,
2136 TRAPS) {
2137 assert(THREAD->can_call_java() ,"");
2138 Handle method_type =
2139 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2140
2141 int ref_kind = JVM_REF_invokeVirtual;
2142 oop name_oop = StringTable::intern(name, CHECK_NULL);
2143 Handle name_str (THREAD, name_oop);
2144 objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2145 assert(appendix_box->obj_at(0) == nullptr, "");
2146
2147 // This should not happen. JDK code should take care of that.
2148 if (accessing_klass == nullptr || method_type.is_null()) {
2149 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2150 }
2151
2152 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2153 JavaCallArguments args;
2154 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2155 args.push_int(ref_kind);
2156 args.push_oop(Handle(THREAD, klass->java_mirror()));
2157 args.push_oop(name_str);
2158 args.push_oop(method_type);
2159 args.push_oop(appendix_box);
2160 JavaValue result(T_OBJECT);
2161 JavaCalls::call_static(&result,
2162 vmClasses::MethodHandleNatives_klass(),
2163 vmSymbols::linkMethod_name(),
2164 vmSymbols::linkMethod_signature(),
2165 &args, CHECK_NULL);
2166 Handle mname(THREAD, result.get_oop());
2167 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2168 }
2169
2170 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2171 // We must ensure that all class loaders everywhere will reach this class, for any client.
2172 // This is a safe bet for public classes in java.lang, such as Object and String.
2173 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2174 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2175 static bool is_always_visible_class(oop mirror) {
2176 Klass* klass = java_lang_Class::as_Klass(mirror);
2177 if (klass->is_objArray_klass()) {
2178 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2179 }
2180 if (klass->is_typeArray_klass()) {
2181 return true; // primitive array
2182 }
2183 assert(klass->is_instance_klass(), "%s", klass->external_name());
2184 return klass->is_public() &&
2185 (InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2186 InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2187 }
2188
2189 // Find or construct the Java mirror (java.lang.Class instance) for
2190 // the given field type signature, as interpreted relative to the
2191 // given class loader. Handles primitives, void, references, arrays,
2192 // and all other reflectable types, except method types.
2193 // N.B. Code in reflection should use this entry point.
2194 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2195 Klass* accessing_klass,
2196 Handle class_loader,
2197 Handle protection_domain,
2198 SignatureStream::FailureMode failure_mode,
2199 TRAPS) {
2200 assert(accessing_klass == nullptr || (class_loader.is_null() && protection_domain.is_null()),
2201 "one or the other, or perhaps neither");
2202
2203 // What we have here must be a valid field descriptor,
2204 // and all valid field descriptors are supported.
2205 // Produce the same java.lang.Class that reflection reports.
2206 if (accessing_klass != nullptr) {
2207 class_loader = Handle(THREAD, accessing_klass->class_loader());
2208 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2209 }
2210 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2211 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2212 if (mirror_oop == nullptr) {
2213 return Handle(); // report failure this way
2214 }
2215 Handle mirror(THREAD, mirror_oop);
2216
2217 if (accessing_klass != nullptr) {
2218 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2219 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2220 if (sel_klass != nullptr) {
2221 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2222 }
2223 }
2224 return mirror;
2225 }
2226
2227
2228 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2229 // signature, as interpreted relative to the given class loader.
2230 // Because of class loader constraints, all method handle usage must be
2231 // consistent with this loader.
2232 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2233 Klass* accessing_klass,
2234 TRAPS) {
2235 Handle empty;
2236 OopHandle* o;
2237 {
2238 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2239 o = _invoke_method_type_table->get(signature);
2240 }
2241
2242 if (o != nullptr) {
2243 oop mt = o->resolve();
2244 assert(java_lang_invoke_MethodType::is_instance(mt), "");
2245 return Handle(THREAD, mt);
2246 } else if (!THREAD->can_call_java()) {
2247 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2248 return Handle(); // do not attempt from within compiler, unless it was cached
2249 }
2250
2251 Handle class_loader, protection_domain;
2252 if (accessing_klass != nullptr) {
2253 class_loader = Handle(THREAD, accessing_klass->class_loader());
2254 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2255 }
2256 bool can_be_cached = true;
2257 int npts = ArgumentCount(signature).size();
2258 objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2259 int arg = 0;
2260 Handle rt; // the return type from the signature
2261 ResourceMark rm(THREAD);
2262 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2263 oop mirror = nullptr;
2264 if (can_be_cached) {
2265 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2266 mirror = ss.as_java_mirror(Handle(), Handle(),
2267 SignatureStream::ReturnNull, CHECK_(empty));
2268 if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {
2269 // Fall back to accessing_klass context.
2270 can_be_cached = false;
2271 }
2272 }
2273 if (!can_be_cached) {
2274 // Resolve, throwing a real error if it doesn't work.
2275 mirror = ss.as_java_mirror(class_loader, protection_domain,
2276 SignatureStream::NCDFError, CHECK_(empty));
2277 }
2278 assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2279 if (ss.at_return_type())
2280 rt = Handle(THREAD, mirror);
2281 else
2282 pts->obj_at_put(arg++, mirror);
2283
2284 // Check accessibility.
2285 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {
2286 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2287 mirror = nullptr; // safety
2288 // Emulate ConstantPool::verify_constant_pool_resolve.
2289 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2290 }
2291 }
2292 assert(arg == npts, "");
2293
2294 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2295 JavaCallArguments args(Handle(THREAD, rt()));
2296 args.push_oop(pts);
2297 JavaValue result(T_OBJECT);
2298 JavaCalls::call_static(&result,
2299 vmClasses::MethodHandleNatives_klass(),
2300 vmSymbols::findMethodHandleType_name(),
2301 vmSymbols::findMethodHandleType_signature(),
2302 &args, CHECK_(empty));
2303 Handle method_type(THREAD, result.get_oop());
2304
2305 if (can_be_cached) {
2306 // We can cache this MethodType inside the JVM.
2307 MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2308 bool created = false;
2309 assert(method_type != nullptr, "unexpected null");
2310 OopHandle* h = _invoke_method_type_table->get(signature);
2311 if (h == nullptr) {
2312 signature->make_permanent(); // The signature is never unloaded.
2313 OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2314 bool created = _invoke_method_type_table->put(signature, elem);
2315 assert(created, "better be created");
2316 }
2317 }
2318 // report back to the caller with the MethodType
2319 return method_type;
2320 }
2321
2322 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2323 Klass* accessing_klass,
2324 TRAPS) {
2325 Handle empty;
2326 ResourceMark rm(THREAD);
2327 SignatureStream ss(signature, /*is_method=*/ false);
2328 if (!ss.is_done()) {
2329 Handle class_loader, protection_domain;
2330 if (accessing_klass != nullptr) {
2331 class_loader = Handle(THREAD, accessing_klass->class_loader());
2332 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2333 }
2334 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2335 ss.next();
2336 if (ss.is_done()) {
2337 return Handle(THREAD, mirror);
2338 }
2339 }
2340 return empty;
2341 }
2342
2343 // Ask Java code to find or construct a method handle constant.
2344 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2345 int ref_kind, //e.g., JVM_REF_invokeVirtual
2346 Klass* callee,
2347 Symbol* name,
2348 Symbol* signature,
2349 TRAPS) {
2350 Handle empty;
2351 if (caller == nullptr) {
2352 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2353 }
2354 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2355 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2356
2357 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2358 Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2359 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2360 java_lang_invoke_MemberName::set_name (mname(), name_str());
2361 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2362 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2363
2364 if (ref_kind == JVM_REF_invokeVirtual &&
2365 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2366 // Skip resolution for public signature polymorphic methods such as
2367 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2368 // They require appendix argument which MemberName resolution doesn't handle.
2369 // There's special logic on JDK side to handle them
2370 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2371 } else {
2372 MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2373 }
2374
2375 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2376 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2377
2378 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2379 JavaCallArguments args;
2380 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2381 args.push_int(ref_kind);
2382 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2383 args.push_oop(name_str);
2384 args.push_oop(type);
2385 JavaValue result(T_OBJECT);
2386 JavaCalls::call_static(&result,
2387 vmClasses::MethodHandleNatives_klass(),
2388 vmSymbols::linkMethodHandleConstant_name(),
2389 vmSymbols::linkMethodHandleConstant_signature(),
2390 &args, CHECK_(empty));
2391 return Handle(THREAD, result.get_oop());
2392 }
2393
2394 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2395 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2396 // with linkage results being stored back into the bootstrap specifier.
2397 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2398 // Resolve the bootstrap specifier, its name, type, and static arguments
2399 bootstrap_specifier.resolve_bsm(CHECK);
2400
2401 // This should not happen. JDK code should take care of that.
2402 if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {
2403 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2404 }
2405
2406 bool is_indy = bootstrap_specifier.is_method_call();
2407 objArrayHandle appendix_box;
2408 if (is_indy) {
2409 // Some method calls may require an appendix argument. Arrange to receive it.
2410 appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2411 assert(appendix_box->obj_at(0) == nullptr, "");
2412 }
2413
2414 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2415 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2416 JavaCallArguments args;
2417 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2418 args.push_oop(bootstrap_specifier.bsm());
2419 args.push_oop(bootstrap_specifier.name_arg());
2420 args.push_oop(bootstrap_specifier.type_arg());
2421 args.push_oop(bootstrap_specifier.arg_values());
2422 if (is_indy) {
2423 args.push_oop(appendix_box);
2424 }
2425 JavaValue result(T_OBJECT);
2426 JavaCalls::call_static(&result,
2427 vmClasses::MethodHandleNatives_klass(),
2428 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2429 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2430 &args, CHECK);
2431
2432 Handle value(THREAD, result.get_oop());
2433 if (is_indy) {
2434 Handle appendix;
2435 Method* method = unpack_method_and_appendix(value,
2436 bootstrap_specifier.caller(),
2437 appendix_box,
2438 &appendix, CHECK);
2439 methodHandle mh(THREAD, method);
2440 bootstrap_specifier.set_resolved_method(mh, appendix);
2441 } else {
2442 bootstrap_specifier.set_resolved_value(value);
2443 }
2444
2445 // sanity check
2446 assert(bootstrap_specifier.is_resolved() ||
2447 (bootstrap_specifier.is_method_call() &&
2448 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2449 }
2450
2451
2452 bool SystemDictionary::is_nonpublic_Object_method(Method* m) {
2453 assert(m != nullptr, "Unexpected nullptr Method*");
2454 return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2455 }
2456
2457 // ----------------------------------------------------------------------------
2458
2459 void SystemDictionary::print_on(outputStream *st) {
2460 CDS_ONLY(SystemDictionaryShared::print_on(st));
2461 GCMutexLocker mu(SystemDictionary_lock);
2462
2463 ClassLoaderDataGraph::print_dictionary(st);
2464
2465 // Placeholders
2466 PlaceholderTable::print_on(st);
2467 st->cr();
2468
2469 // loader constraints - print under SD_lock
2470 LoaderConstraintTable::print_on(st);
2471 st->cr();
2472
2473 ProtectionDomainCacheTable::print_on(st);
2474 st->cr();
2475 }
2476
2477 void SystemDictionary::print() { print_on(tty); }
2478
2479 void SystemDictionary::verify() {
2480
2481 GCMutexLocker mu(SystemDictionary_lock);
2482
2483 // Verify dictionary
2484 ClassLoaderDataGraph::verify_dictionary();
2485
2486 // Verify constraint table
2487 LoaderConstraintTable::verify();
2488
2489 // Verify protection domain table
2490 ProtectionDomainCacheTable::verify();
2491 }
2492
2493 void SystemDictionary::dump(outputStream *st, bool verbose) {
2494 assert_locked_or_safepoint(SystemDictionary_lock);
2495 if (verbose) {
2496 print_on(st);
2497 } else {
2498 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2499 ClassLoaderDataGraph::print_table_statistics(st);
2500 LoaderConstraintTable::print_table_statistics(st);
2501 ProtectionDomainCacheTable::print_table_statistics(st);
2502 }
2503 }
2504
2505 // Utility for dumping dictionaries.
2506 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2507 DCmdWithParser(output, heap),
2508 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2509 "BOOLEAN", false, "false") {
2510 _dcmdparser.add_dcmd_option(&_verbose);
2511 }
2512
2513 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2514 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2515 _verbose.value());
2516 VMThread::execute(&dumper);
2517 }