1 /*
2 * Copyright (c) 1997, 2020, 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 "jvm.h"
27 #include "aot/aotLoader.hpp"
28 #include "classfile/classFileParser.hpp"
29 #include "classfile/classFileStream.hpp"
30 #include "classfile/classLoader.hpp"
31 #include "classfile/classLoaderData.inline.hpp"
32 #include "classfile/classLoaderDataGraph.inline.hpp"
33 #include "classfile/classLoaderExt.hpp"
34 #include "classfile/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/vmSymbols.hpp"
46 #include "code/codeCache.hpp"
47 #include "compiler/compileBroker.hpp"
48 #include "gc/shared/gcTraceTime.inline.hpp"
49 #include "interpreter/bytecodeStream.hpp"
50 #include "interpreter/interpreter.hpp"
51 #include "jfr/jfrEvents.hpp"
52 #include "logging/log.hpp"
53 #include "logging/logStream.hpp"
54 #include "memory/filemap.hpp"
55 #include "memory/heapShared.hpp"
56 #include "memory/metaspaceClosure.hpp"
57 #include "memory/oopFactory.hpp"
58 #include "memory/resourceArea.hpp"
59 #include "memory/universe.hpp"
60 #include "oops/access.inline.hpp"
61 #include "oops/instanceKlass.hpp"
62 #include "oops/instanceRefKlass.hpp"
63 #include "oops/klass.inline.hpp"
64 #include "oops/method.inline.hpp"
65 #include "oops/methodData.hpp"
66 #include "oops/objArrayKlass.hpp"
67 #include "oops/objArrayOop.inline.hpp"
68 #include "oops/oop.inline.hpp"
69 #include "oops/oopHandle.inline.hpp"
70 #include "oops/symbol.hpp"
71 #include "oops/typeArrayKlass.hpp"
72 #include "prims/jvmtiExport.hpp"
73 #include "prims/methodHandles.hpp"
74 #include "runtime/arguments.hpp"
75 #include "runtime/biasedLocking.hpp"
76 #include "runtime/handles.inline.hpp"
77 #include "runtime/java.hpp"
78 #include "runtime/javaCalls.hpp"
79 #include "runtime/mutexLocker.hpp"
80 #include "runtime/sharedRuntime.hpp"
81 #include "runtime/signature.hpp"
82 #include "services/classLoadingService.hpp"
83 #include "services/diagnosticCommand.hpp"
84 #include "services/threadService.hpp"
85 #include "utilities/macros.hpp"
86 #include "utilities/utf8.hpp"
87 #if INCLUDE_CDS
88 #include "classfile/systemDictionaryShared.hpp"
89 #endif
90 #if INCLUDE_JFR
91 #include "jfr/jfr.hpp"
92 #endif
93
94 PlaceholderTable* SystemDictionary::_placeholders = NULL;
95 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
96 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
97 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
98 ProtectionDomainCacheTable* SystemDictionary::_pd_cache_table = NULL;
99
100 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
101 = { NULL /*, NULL...*/ };
102
103 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
104
105
106 OopHandle SystemDictionary::_system_loader_lock_obj;
107 OopHandle SystemDictionary::_java_system_loader;
108 OopHandle SystemDictionary::_java_platform_loader;
109
110 // Default ProtectionDomainCacheSize value
111
112 const int defaultProtectionDomainCacheSize = 1009;
113
114 ClassLoadInfo::ClassLoadInfo() {
115 _protection_domain = Handle();
116 _unsafe_anonymous_host = NULL;
117 _cp_patches = NULL;
118 _class_hidden_info._dynamic_nest_host = NULL;
119 _class_hidden_info._class_data = Handle();
120 _is_hidden = false;
121 _is_strong_hidden = false;
122 _can_access_vm_annotations = false;
123 }
124
125 ClassLoadInfo::ClassLoadInfo(Handle protection_domain) {
126 _protection_domain = protection_domain;
127 _unsafe_anonymous_host = NULL;
128 _cp_patches = NULL;
129 _class_hidden_info._dynamic_nest_host = NULL;
130 _class_hidden_info._class_data = Handle();
131 _is_hidden = false;
132 _is_strong_hidden = false;
133 _can_access_vm_annotations = false;
134 }
135
136 ClassLoadInfo::ClassLoadInfo(Handle protection_domain,
137 const InstanceKlass* unsafe_anonymous_host,
138 GrowableArray<Handle>* cp_patches,
139 InstanceKlass* dynamic_nest_host,
140 Handle class_data,
141 bool is_hidden,
142 bool is_strong_hidden,
143 bool can_access_vm_annotations) {
144 _protection_domain = protection_domain;
145 _unsafe_anonymous_host = unsafe_anonymous_host;
146 _cp_patches = cp_patches;
147 _class_hidden_info._dynamic_nest_host = dynamic_nest_host;
148 _class_hidden_info._class_data = class_data;
149 _is_hidden = is_hidden;
150 _is_strong_hidden = is_strong_hidden;
151 _can_access_vm_annotations = can_access_vm_annotations;
152 }
153
154 // ----------------------------------------------------------------------------
155 // Java-level SystemLoader and PlatformLoader
156
157 oop SystemDictionary::system_loader_lock() {
158 return _system_loader_lock_obj.resolve();
159 }
160
161 oop SystemDictionary::java_system_loader() {
162 return _java_system_loader.resolve();
163 }
164
165 oop SystemDictionary::java_platform_loader() {
166 return _java_platform_loader.resolve();
167 }
168
169 void SystemDictionary::compute_java_loaders(TRAPS) {
170 JavaValue result(T_OBJECT);
171 InstanceKlass* class_loader_klass = SystemDictionary::ClassLoader_klass();
172 JavaCalls::call_static(&result,
173 class_loader_klass,
174 vmSymbols::getSystemClassLoader_name(),
175 vmSymbols::void_classloader_signature(),
176 CHECK);
177
178 _java_system_loader = OopHandle::create((oop)result.get_jobject());
179
180 JavaCalls::call_static(&result,
181 class_loader_klass,
182 vmSymbols::getPlatformClassLoader_name(),
183 vmSymbols::void_classloader_signature(),
184 CHECK);
185
186 _java_platform_loader = OopHandle::create((oop)result.get_jobject());
187 }
188
189 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {
190 if (create_mirror_cld) {
191 // Add a new class loader data to the graph.
192 return ClassLoaderDataGraph::add(class_loader, true);
193 } else {
194 return (class_loader() == NULL) ? ClassLoaderData::the_null_class_loader_data() :
195 ClassLoaderDataGraph::find_or_create(class_loader);
196 }
197 }
198
199 // ----------------------------------------------------------------------------
200 // Parallel class loading check
201
202 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
203 if (class_loader.is_null()) return true;
204 if (AlwaysLockClassLoader) return false;
205 return java_lang_ClassLoader::parallelCapable(class_loader());
206 }
207 // ----------------------------------------------------------------------------
208 // ParallelDefineClass flag does not apply to bootclass loader
209 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
210 if (class_loader.is_null()) return false;
211 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
212 return true;
213 }
214 return false;
215 }
216
217 // Returns true if the passed class loader is the builtin application class loader
218 // or a custom system class loader. A customer system class loader can be
219 // specified via -Djava.system.class.loader.
220 bool SystemDictionary::is_system_class_loader(oop class_loader) {
221 if (class_loader == NULL) {
222 return false;
223 }
224 return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
225 class_loader == _java_system_loader.peek());
226 }
227
228 // Returns true if the passed class loader is the platform class loader.
229 bool SystemDictionary::is_platform_class_loader(oop class_loader) {
230 if (class_loader == NULL) {
231 return false;
232 }
233 return (class_loader->klass() == SystemDictionary::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
234 }
235
236 // ----------------------------------------------------------------------------
237 // Resolving of classes
238
239 Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {
240 if (name == NULL) {
241 THROW_MSG_0(exception, "No class name given");
242 }
243 if ((int)strlen(name) > Symbol::max_length()) {
244 // It's impossible to create this class; the name cannot fit
245 // into the constant pool.
246 Exceptions::fthrow(THREAD_AND_LOCATION, exception,
247 "Class name exceeds maximum length of %d: %s",
248 Symbol::max_length(),
249 name);
250 return NULL;
251 }
252 // Callers should ensure that the name is never an illegal UTF8 string.
253 assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false),
254 "Class name is not a valid utf8 string.");
255
256 // Make a new symbol for the class name.
257 return SymbolTable::new_symbol(name);
258 }
259
260 // Forwards to resolve_or_null
261
262 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
263 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
264 if (HAS_PENDING_EXCEPTION || klass == NULL) {
265 // can return a null klass
266 klass = handle_resolution_exception(class_name, throw_error, klass, THREAD);
267 }
268 return klass;
269 }
270
271 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
272 bool throw_error,
273 Klass* klass, TRAPS) {
274 if (HAS_PENDING_EXCEPTION) {
275 // If we have a pending exception we forward it to the caller, unless throw_error is true,
276 // in which case we have to check whether the pending exception is a ClassNotFoundException,
277 // and if so convert it to a NoClassDefFoundError
278 // And chain the original ClassNotFoundException
279 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
280 ResourceMark rm(THREAD);
281 assert(klass == NULL, "Should not have result with exception pending");
282 Handle e(THREAD, PENDING_EXCEPTION);
283 CLEAR_PENDING_EXCEPTION;
284 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
285 } else {
286 return NULL;
287 }
288 }
289 // Class not found, throw appropriate error or exception depending on value of throw_error
290 if (klass == NULL) {
291 ResourceMark rm(THREAD);
292 if (throw_error) {
293 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
294 } else {
295 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
296 }
297 }
298 return klass;
299 }
300
301
302 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
303 bool throw_error, TRAPS)
304 {
305 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
306 }
307
308
309 // Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
310
311 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
312 if (Signature::is_array(class_name)) {
313 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
314 } else {
315 return resolve_instance_class_or_null_helper(class_name, class_loader, protection_domain, THREAD);
316 }
317 }
318
319 // name may be in the form of "java/lang/Object" or "Ljava/lang/Object;"
320 InstanceKlass* SystemDictionary::resolve_instance_class_or_null_helper(Symbol* class_name,
321 Handle class_loader,
322 Handle protection_domain,
323 TRAPS) {
324 assert(class_name != NULL && !Signature::is_array(class_name), "must be");
325 if (Signature::has_envelope(class_name)) {
326 ResourceMark rm(THREAD);
327 // Ignore wrapping L and ;.
328 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
329 class_name->utf8_length() - 2);
330 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
331 } else {
332 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
333 }
334 }
335
336 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
337 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
338 }
339
340 // Forwards to resolve_instance_class_or_null
341
342 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
343 Handle class_loader,
344 Handle protection_domain,
345 TRAPS) {
346 assert(Signature::is_array(class_name), "must be array");
347 ResourceMark rm(THREAD);
348 SignatureStream ss(class_name, false);
349 int ndims = ss.skip_array_prefix(); // skip all '['s
350 Klass* k = NULL;
351 BasicType t = ss.type();
352 if (ss.has_envelope()) {
353 Symbol* obj_class = ss.as_symbol();
354 k = SystemDictionary::resolve_instance_class_or_null(obj_class,
355 class_loader,
356 protection_domain,
357 CHECK_NULL);
358 if (k != NULL) {
359 k = k->array_klass(ndims, CHECK_NULL);
360 }
361 } else {
362 k = Universe::typeArrayKlassObj(t);
363 k = TypeArrayKlass::cast(k)->array_klass(ndims, CHECK_NULL);
364 }
365 return k;
366 }
367
368
369 // Must be called for any super-class or super-interface resolution
370 // during class definition to allow class circularity checking
371 // super-interface callers:
372 // parse_interfaces - for defineClass & jvmtiRedefineClasses
373 // super-class callers:
374 // ClassFileParser - for defineClass & jvmtiRedefineClasses
375 // load_shared_class - while loading a class from shared archive
376 // resolve_instance_class_or_null:
377 // via: handle_parallel_super_load
378 // when resolving a class that has an existing placeholder with
379 // a saved superclass [i.e. a defineClass is currently in progress]
380 // if another thread is trying to resolve the class, it must do
381 // super-class checks on its own thread to catch class circularity
382 // This last call is critical in class circularity checking for cases
383 // where classloading is delegated to different threads and the
384 // classloader lock is released.
385 // Take the case: Base->Super->Base
386 // 1. If thread T1 tries to do a defineClass of class Base
387 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
388 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
389 // so it tries to load Super
390 // 3. If we load the class internally, or user classloader uses same thread
391 // loadClassFromxxx or defineClass via parseClassFile Super ...
392 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
393 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
394 // 3.4 calls resolve_super_or_fail Base
395 // 3.5 finds T1,Base -> throws class circularity
396 //OR 4. If T2 tries to resolve Super via defineClass Super ...
397 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
398 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
399 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
400 // 4.4 finds T2, Super -> throws class circularity
401 // Must be called, even if superclass is null, since this is
402 // where the placeholder entry is created which claims this
403 // thread is loading this class/classloader.
404 // Be careful when modifying this code: once you have run
405 // placeholders()->find_and_add(PlaceholderTable::LOAD_SUPER),
406 // you need to find_and_remove it before returning.
407 // So be careful to not exit with a CHECK_ macro betweeen these calls.
408 InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
409 Symbol* super_name,
410 Handle class_loader,
411 Handle protection_domain,
412 bool is_superclass,
413 TRAPS) {
414 assert(!Signature::is_array(super_name), "invalid super class name");
415 #if INCLUDE_CDS
416 if (DumpSharedSpaces) {
417 // Special processing for handling UNREGISTERED shared classes.
418 InstanceKlass* k = SystemDictionaryShared::dump_time_resolve_super_or_fail(child_name,
419 super_name, class_loader, protection_domain, is_superclass, CHECK_NULL);
420 if (k) {
421 return k;
422 }
423 }
424 #endif // INCLUDE_CDS
425
426 // Double-check, if child class is already loaded, just return super-class,interface
427 // Don't add a placedholder if already loaded, i.e. already in appropriate class loader
428 // dictionary.
429 // Make sure there's a placeholder for the *child* before resolving.
430 // Used as a claim that this thread is currently loading superclass/classloader
431 // Used here for ClassCircularity checks and also for heap verification
432 // (every InstanceKlass needs to be in its class loader dictionary or have a placeholder).
433 // Must check ClassCircularity before checking if super class is already loaded.
434 //
435 // We might not already have a placeholder if this child_name was
436 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
437 // the name of the class might not be known until the stream is actually
438 // parsed.
439 // Bugs 4643874, 4715493
440
441 ClassLoaderData* loader_data = class_loader_data(class_loader);
442 Dictionary* dictionary = loader_data->dictionary();
443 unsigned int d_hash = dictionary->compute_hash(child_name);
444 unsigned int p_hash = placeholders()->compute_hash(child_name);
445 int p_index = placeholders()->hash_to_index(p_hash);
446 // can't throw error holding a lock
447 bool child_already_loaded = false;
448 bool throw_circularity_error = false;
449 {
450 MutexLocker mu(THREAD, SystemDictionary_lock);
451 InstanceKlass* childk = find_class(d_hash, child_name, dictionary);
452 InstanceKlass* quicksuperk;
453 // to support // loading: if child done loading, just return superclass
454 // if super_name, & class_loader don't match:
455 // if initial define, SD update will give LinkageError
456 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
457 // so we don't throw an exception here.
458 // see: nsk redefclass014 & java.lang.instrument Instrument032
459 if ((childk != NULL ) && (is_superclass) &&
460 ((quicksuperk = childk->java_super()) != NULL) &&
461 ((quicksuperk->name() == super_name) &&
462 (quicksuperk->class_loader() == class_loader()))) {
463 return quicksuperk;
464 } else {
465 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
466 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
467 throw_circularity_error = true;
468 }
469 }
470 if (!throw_circularity_error) {
471 // Be careful not to exit resolve_super
472 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, super_name, THREAD);
473 }
474 }
475 if (throw_circularity_error) {
476 ResourceMark rm(THREAD);
477 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
478 }
479
480 // java.lang.Object should have been found above
481 assert(super_name != NULL, "null super class for resolving");
482 // Resolve the super class or interface, check results on return
483 InstanceKlass* superk =
484 SystemDictionary::resolve_instance_class_or_null_helper(super_name,
485 class_loader,
486 protection_domain,
487 THREAD);
488
489 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
490 // It is no longer necessary to keep the placeholder table alive until update_dictionary
491 // or error. GC used to walk the placeholder table as strong roots.
492 // The instanceKlass is kept alive because the class loader is on the stack,
493 // which keeps the loader_data alive, as well as all instanceKlasses in
494 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
495 {
496 MutexLocker mu(THREAD, SystemDictionary_lock);
497 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
498 SystemDictionary_lock->notify_all();
499 }
500 if (HAS_PENDING_EXCEPTION || superk == NULL) {
501 // can null superk
502 Klass* k = handle_resolution_exception(super_name, true, superk, THREAD);
503 assert(k == NULL || k == superk, "must be");
504 if (k == NULL) {
505 superk = NULL;
506 }
507 }
508
509 return superk;
510 }
511
512 void SystemDictionary::validate_protection_domain(InstanceKlass* klass,
513 Handle class_loader,
514 Handle protection_domain,
515 TRAPS) {
516 // Now we have to call back to java to check if the initating class has access
517 JavaValue result(T_VOID);
518 LogTarget(Debug, protectiondomain) lt;
519 if (lt.is_enabled()) {
520 ResourceMark rm(THREAD);
521 // Print out trace information
522 LogStream ls(lt);
523 ls.print_cr("Checking package access");
524 if (class_loader() != NULL) {
525 ls.print("class loader: ");
526 class_loader()->print_value_on(&ls);
527 } else {
528 ls.print_cr("class loader: NULL");
529 }
530 if (protection_domain() != NULL) {
531 ls.print(" protection domain: ");
532 protection_domain()->print_value_on(&ls);
533 } else {
534 ls.print_cr(" protection domain: NULL");
535 }
536 ls.print(" loading: "); klass->print_value_on(&ls);
537 ls.cr();
538 }
539
540 // This handle and the class_loader handle passed in keeps this class from
541 // being unloaded through several GC points.
542 // The class_loader handle passed in is the initiating loader.
543 Handle mirror(THREAD, klass->java_mirror());
544
545 InstanceKlass* system_loader = SystemDictionary::ClassLoader_klass();
546 JavaCalls::call_special(&result,
547 class_loader,
548 system_loader,
549 vmSymbols::checkPackageAccess_name(),
550 vmSymbols::class_protectiondomain_signature(),
551 mirror,
552 protection_domain,
553 THREAD);
554
555 if (HAS_PENDING_EXCEPTION) {
556 log_debug(protectiondomain)("DENIED !!!!!!!!!!!!!!!!!!!!!");
557 } else {
558 log_debug(protectiondomain)("granted");
559 }
560
561 if (HAS_PENDING_EXCEPTION) return;
562
563 // If no exception has been thrown, we have validated the protection domain
564 // Insert the protection domain of the initiating class into the set.
565 {
566 ClassLoaderData* loader_data = class_loader_data(class_loader);
567 Dictionary* dictionary = loader_data->dictionary();
568
569 Symbol* kn = klass->name();
570 unsigned int d_hash = dictionary->compute_hash(kn);
571
572 MutexLocker mu(THREAD, SystemDictionary_lock);
573 int d_index = dictionary->hash_to_index(d_hash);
574 dictionary->add_protection_domain(d_index, d_hash, klass,
575 protection_domain, THREAD);
576 }
577 }
578
579 // We only get here if this thread finds that another thread
580 // has already claimed the placeholder token for the current operation,
581 // but that other thread either never owned or gave up the
582 // object lock
583 // Waits on SystemDictionary_lock to indicate placeholder table updated
584 // On return, caller must recheck placeholder table state
585 //
586 // We only get here if
587 // 1) custom classLoader, i.e. not bootstrap classloader
588 // 2) custom classLoader has broken the class loader objectLock
589 // so another thread got here in parallel
590 //
591 // lockObject must be held.
592 // Complicated dance due to lock ordering:
593 // Must first release the classloader object lock to
594 // allow initial definer to complete the class definition
595 // and to avoid deadlock
596 // Reclaim classloader lock object with same original recursion count
597 // Must release SystemDictionary_lock after notify, since
598 // class loader lock must be claimed before SystemDictionary_lock
599 // to prevent deadlocks
600 //
601 // The notify allows applications that did an untimed wait() on
602 // the classloader object lock to not hang.
603 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
604 assert_lock_strong(SystemDictionary_lock);
605
606 bool calledholdinglock
607 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
608 assert(calledholdinglock,"must hold lock for notify");
609 assert((lockObject() != _system_loader_lock_obj.resolve() &&
610 !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
611 ObjectSynchronizer::notifyall(lockObject, THREAD);
612 intx recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
613 SystemDictionary_lock->wait();
614 SystemDictionary_lock->unlock();
615 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
616 SystemDictionary_lock->lock();
617 }
618
619 // If the class in is in the placeholder table, class loading is in progress
620 // For cases where the application changes threads to load classes, it
621 // is critical to ClassCircularity detection that we try loading
622 // the superclass on the same thread internally, so we do parallel
623 // super class loading here.
624 // This also is critical in cases where the original thread gets stalled
625 // even in non-circularity situations.
626 // Note: must call resolve_super_or_fail even if null super -
627 // to force placeholder entry creation for this class for circularity detection
628 // Caller must check for pending exception
629 // Returns non-null Klass* if other thread has completed load
630 // and we are done,
631 // If return null Klass* and no pending exception, the caller must load the class
632 InstanceKlass* SystemDictionary::handle_parallel_super_load(
633 Symbol* name, Symbol* superclassname, Handle class_loader,
634 Handle protection_domain, Handle lockObject, TRAPS) {
635
636 ClassLoaderData* loader_data = class_loader_data(class_loader);
637 Dictionary* dictionary = loader_data->dictionary();
638 unsigned int d_hash = dictionary->compute_hash(name);
639 unsigned int p_hash = placeholders()->compute_hash(name);
640 int p_index = placeholders()->hash_to_index(p_hash);
641
642 // superk is not used, resolve_super called for circularity check only
643 // This code is reached in two situations. One if this thread
644 // is loading the same class twice (e.g. ClassCircularity, or
645 // java.lang.instrument).
646 // The second is if another thread started the resolve_super first
647 // and has not yet finished.
648 // In both cases the original caller will clean up the placeholder
649 // entry on error.
650 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
651 superclassname,
652 class_loader,
653 protection_domain,
654 true,
655 CHECK_NULL);
656
657 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
658 // Serial class loaders and bootstrap classloader do wait for superclass loads
659 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
660 MutexLocker mu(THREAD, SystemDictionary_lock);
661 // Check if classloading completed while we were loading superclass or waiting
662 return find_class(d_hash, name, dictionary);
663 }
664
665 // must loop to both handle other placeholder updates
666 // and spurious notifications
667 bool super_load_in_progress = true;
668 PlaceholderEntry* placeholder;
669 while (super_load_in_progress) {
670 MutexLocker mu(THREAD, SystemDictionary_lock);
671 // Check if classloading completed while we were loading superclass or waiting
672 InstanceKlass* check = find_class(d_hash, name, dictionary);
673 if (check != NULL) {
674 // Klass is already loaded, so just return it
675 return check;
676 } else {
677 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
678 if (placeholder && placeholder->super_load_in_progress() ){
679 // We only get here if the application has released the
680 // classloader lock when another thread was in the middle of loading a
681 // superclass/superinterface for this class, and now
682 // this thread is also trying to load this class.
683 // To minimize surprises, the first thread that started to
684 // load a class should be the one to complete the loading
685 // with the classfile it initially expected.
686 // This logic has the current thread wait once it has done
687 // all the superclass/superinterface loading it can, until
688 // the original thread completes the class loading or fails
689 // If it completes we will use the resulting InstanceKlass
690 // which we will find below in the systemDictionary.
691 // We also get here for parallel bootstrap classloader
692 if (class_loader.is_null()) {
693 SystemDictionary_lock->wait();
694 } else {
695 double_lock_wait(lockObject, THREAD);
696 }
697 } else {
698 // If not in SD and not in PH, other thread's load must have failed
699 super_load_in_progress = false;
700 }
701 }
702 }
703 return NULL;
704 }
705
706 static void post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {
707 assert(event != NULL, "invariant");
708 assert(k != NULL, "invariant");
709 assert(event->should_commit(), "invariant");
710 event->set_loadedClass(k);
711 event->set_definingClassLoader(k->class_loader_data());
712 event->set_initiatingClassLoader(init_cld);
713 event->commit();
714 }
715
716
717 // Be careful when modifying this code: once you have run
718 // placeholders()->find_and_add(PlaceholderTable::LOAD_INSTANCE),
719 // you need to find_and_remove it before returning.
720 // So be careful to not exit with a CHECK_ macro betweeen these calls.
721 //
722 // name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
723 InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
724 Handle class_loader,
725 Handle protection_domain,
726 TRAPS) {
727 assert(name != NULL && !Signature::is_array(name) &&
728 !Signature::has_envelope(name), "invalid class name");
729
730 EventClassLoad class_load_start_event;
731
732 HandleMark hm(THREAD);
733
734 // Fix for 4474172; see evaluation for more details
735 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
736 ClassLoaderData* loader_data = register_loader(class_loader);
737 Dictionary* dictionary = loader_data->dictionary();
738 unsigned int d_hash = dictionary->compute_hash(name);
739
740 // Do lookup to see if class already exist and the protection domain
741 // has the right access
742 // This call uses find which checks protection domain already matches
743 // All subsequent calls use find_class, and set has_loaded_class so that
744 // before we return a result we call out to java to check for valid protection domain
745 // to allow returning the Klass* and add it to the pd_set if it is valid
746 {
747 InstanceKlass* probe = dictionary->find(d_hash, name, protection_domain);
748 if (probe != NULL) return probe;
749 }
750
751 // Non-bootstrap class loaders will call out to class loader and
752 // define via jvm/jni_DefineClass which will acquire the
753 // class loader object lock to protect against multiple threads
754 // defining the class in parallel by accident.
755 // This lock must be acquired here so the waiter will find
756 // any successful result in the SystemDictionary and not attempt
757 // the define.
758 // ParallelCapable Classloaders and the bootstrap classloader
759 // do not acquire lock here.
760 bool DoObjectLock = true;
761 if (is_parallelCapable(class_loader)) {
762 DoObjectLock = false;
763 }
764
765 unsigned int p_hash = placeholders()->compute_hash(name);
766 int p_index = placeholders()->hash_to_index(p_hash);
767
768 // Class is not in SystemDictionary so we have to do loading.
769 // Make sure we are synchronized on the class loader before we proceed
770 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
771 check_loader_lock_contention(lockObject, THREAD);
772 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
773
774 // Check again (after locking) if class already exist in SystemDictionary
775 bool class_has_been_loaded = false;
776 bool super_load_in_progress = false;
777 bool havesupername = false;
778 InstanceKlass* k = NULL;
779 PlaceholderEntry* placeholder;
780 Symbol* superclassname = NULL;
781
782 assert(THREAD->can_call_java(),
783 "can not load classes with compiler thread: class=%s, classloader=%s",
784 name->as_C_string(),
785 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
786 {
787 MutexLocker mu(THREAD, SystemDictionary_lock);
788 InstanceKlass* check = find_class(d_hash, name, dictionary);
789 if (check != NULL) {
790 // InstanceKlass is already loaded, so just return it
791 class_has_been_loaded = true;
792 k = check;
793 } else {
794 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
795 if (placeholder && placeholder->super_load_in_progress()) {
796 super_load_in_progress = true;
797 if (placeholder->havesupername() == true) {
798 superclassname = placeholder->supername();
799 havesupername = true;
800 }
801 }
802 }
803 }
804
805 // If the class is in the placeholder table, class loading is in progress
806 if (super_load_in_progress && havesupername==true) {
807 k = handle_parallel_super_load(name,
808 superclassname,
809 class_loader,
810 protection_domain,
811 lockObject, THREAD);
812 if (HAS_PENDING_EXCEPTION) {
813 return NULL;
814 }
815 if (k != NULL) {
816 class_has_been_loaded = true;
817 }
818 }
819
820 bool throw_circularity_error = false;
821 if (!class_has_been_loaded) {
822 bool load_instance_added = false;
823
824 // add placeholder entry to record loading instance class
825 // Five cases:
826 // All cases need to prevent modifying bootclasssearchpath
827 // in parallel with a classload of same classname
828 // Redefineclasses uses existence of the placeholder for the duration
829 // of the class load to prevent concurrent redefinition of not completely
830 // defined classes.
831 // case 1. traditional classloaders that rely on the classloader object lock
832 // - no other need for LOAD_INSTANCE
833 // case 2. traditional classloaders that break the classloader object lock
834 // as a deadlock workaround. Detection of this case requires that
835 // this check is done while holding the classloader object lock,
836 // and that lock is still held when calling classloader's loadClass.
837 // For these classloaders, we ensure that the first requestor
838 // completes the load and other requestors wait for completion.
839 // case 3. Bootstrap classloader - don't own objectLocker
840 // This classloader supports parallelism at the classloader level,
841 // but only allows a single load of a class/classloader pair.
842 // No performance benefit and no deadlock issues.
843 // case 4. parallelCapable user level classloaders - without objectLocker
844 // Allow parallel classloading of a class/classloader pair
845
846 {
847 MutexLocker mu(THREAD, SystemDictionary_lock);
848 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
849 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
850 if (oldprobe) {
851 // only need check_seen_thread once, not on each loop
852 // 6341374 java/lang/Instrument with -Xcomp
853 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
854 throw_circularity_error = true;
855 } else {
856 // case 1: traditional: should never see load_in_progress.
857 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
858
859 // case 3: bootstrap classloader: prevent futile classloading,
860 // wait on first requestor
861 if (class_loader.is_null()) {
862 SystemDictionary_lock->wait();
863 } else {
864 // case 2: traditional with broken classloader lock. wait on first
865 // requestor.
866 double_lock_wait(lockObject, THREAD);
867 }
868 // Check if classloading completed while we were waiting
869 InstanceKlass* check = find_class(d_hash, name, dictionary);
870 if (check != NULL) {
871 // Klass is already loaded, so just return it
872 k = check;
873 class_has_been_loaded = true;
874 }
875 // check if other thread failed to load and cleaned up
876 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
877 }
878 }
879 }
880 }
881 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
882 // case 4: parallelCapable: allow competing threads to try
883 // LOAD_INSTANCE in parallel
884
885 if (!throw_circularity_error && !class_has_been_loaded) {
886 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
887 load_instance_added = true;
888 // For class loaders that do not acquire the classloader object lock,
889 // if they did not catch another thread holding LOAD_INSTANCE,
890 // need a check analogous to the acquire ObjectLocker/find_class
891 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
892 // one final check if the load has already completed
893 // class loaders holding the ObjectLock shouldn't find the class here
894 InstanceKlass* check = find_class(d_hash, name, dictionary);
895 if (check != NULL) {
896 // Klass is already loaded, so return it after checking/adding protection domain
897 k = check;
898 class_has_been_loaded = true;
899 }
900 }
901 }
902
903 // must throw error outside of owning lock
904 if (throw_circularity_error) {
905 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
906 ResourceMark rm(THREAD);
907 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
908 }
909
910 if (!class_has_been_loaded) {
911
912 // Do actual loading
913 k = load_instance_class(name, class_loader, THREAD);
914
915 // If everything was OK (no exceptions, no null return value), and
916 // class_loader is NOT the defining loader, do a little more bookkeeping.
917 if (!HAS_PENDING_EXCEPTION && k != NULL &&
918 k->class_loader() != class_loader()) {
919
920 check_constraints(d_hash, k, class_loader, false, THREAD);
921
922 // Need to check for a PENDING_EXCEPTION again; check_constraints
923 // can throw but we may have to remove entry from the placeholder table below.
924 if (!HAS_PENDING_EXCEPTION) {
925 // Record dependency for non-parent delegation.
926 // This recording keeps the defining class loader of the klass (k) found
927 // from being unloaded while the initiating class loader is loaded
928 // even if the reference to the defining class loader is dropped
929 // before references to the initiating class loader.
930 loader_data->record_dependency(k);
931
932 { // Grabbing the Compile_lock prevents systemDictionary updates
933 // during compilations.
934 MutexLocker mu(THREAD, Compile_lock);
935 update_dictionary(d_hash, p_index, p_hash,
936 k, class_loader, THREAD);
937 }
938
939 if (JvmtiExport::should_post_class_load()) {
940 Thread *thread = THREAD;
941 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
942 JvmtiExport::post_class_load((JavaThread *) thread, k);
943 }
944 }
945 }
946 } // load_instance_class
947
948 if (load_instance_added == true) {
949 // clean up placeholder entries for LOAD_INSTANCE success or error
950 // This brackets the SystemDictionary updates for both defining
951 // and initiating loaders
952 MutexLocker mu(THREAD, SystemDictionary_lock);
953 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
954 SystemDictionary_lock->notify_all();
955 }
956 }
957
958 if (HAS_PENDING_EXCEPTION || k == NULL) {
959 return NULL;
960 }
961 if (class_load_start_event.should_commit()) {
962 post_class_load_event(&class_load_start_event, k, loader_data);
963 }
964 #ifdef ASSERT
965 {
966 ClassLoaderData* loader_data = k->class_loader_data();
967 MutexLocker mu(THREAD, SystemDictionary_lock);
968 InstanceKlass* kk = find_class(name, loader_data);
969 assert(kk == k, "should be present in dictionary");
970 }
971 #endif
972
973 // return if the protection domain in NULL
974 if (protection_domain() == NULL) return k;
975
976 // Check the protection domain has the right access
977 if (dictionary->is_valid_protection_domain(d_hash, name,
978 protection_domain)) {
979 return k;
980 }
981
982 // Verify protection domain. If it fails an exception is thrown
983 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
984
985 return k;
986 }
987
988
989 // This routine does not lock the system dictionary.
990 //
991 // Since readers don't hold a lock, we must make sure that system
992 // dictionary entries are only removed at a safepoint (when only one
993 // thread is running), and are added to in a safe way (all links must
994 // be updated in an MT-safe manner).
995 //
996 // Callers should be aware that an entry could be added just after
997 // _dictionary->bucket(index) is read here, so the caller will not see
998 // the new entry.
999
1000 Klass* SystemDictionary::find(Symbol* class_name,
1001 Handle class_loader,
1002 Handle protection_domain,
1003 TRAPS) {
1004
1005 // The result of this call should be consistent with the result
1006 // of the call to resolve_instance_class_or_null().
1007 // See evaluation 6790209 and 4474172 for more details.
1008 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
1009 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
1010
1011 if (loader_data == NULL) {
1012 // If the ClassLoaderData has not been setup,
1013 // then the class loader has no entries in the dictionary.
1014 return NULL;
1015 }
1016
1017 Dictionary* dictionary = loader_data->dictionary();
1018 unsigned int d_hash = dictionary->compute_hash(class_name);
1019 return dictionary->find(d_hash, class_name,
1020 protection_domain);
1021 }
1022
1023
1024 // Look for a loaded instance or array klass by name. Do not do any loading.
1025 // return NULL in case of error.
1026 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
1027 Handle class_loader,
1028 Handle protection_domain,
1029 TRAPS) {
1030 Klass* k = NULL;
1031 assert(class_name != NULL, "class name must be non NULL");
1032
1033 if (Signature::is_array(class_name)) {
1034 // The name refers to an array. Parse the name.
1035 // dimension and object_key in FieldArrayInfo are assigned as a
1036 // side-effect of this call
1037 SignatureStream ss(class_name, false);
1038 int ndims = ss.skip_array_prefix(); // skip all '['s
1039 BasicType t = ss.type();
1040 if (t != T_OBJECT) {
1041 k = Universe::typeArrayKlassObj(t);
1042 } else {
1043 k = SystemDictionary::find(ss.as_symbol(), class_loader, protection_domain, THREAD);
1044 }
1045 if (k != NULL) {
1046 k = k->array_klass_or_null(ndims);
1047 }
1048 } else {
1049 k = find(class_name, class_loader, protection_domain, THREAD);
1050 }
1051 return k;
1052 }
1053
1054 // Note: this method is much like resolve_from_stream, but
1055 // does not publish the classes via the SystemDictionary.
1056 // Handles Lookup.defineClass hidden, unsafe_DefineAnonymousClass
1057 // and redefineclasses. RedefinedClasses do not add to the class hierarchy.
1058 InstanceKlass* SystemDictionary::parse_stream(Symbol* class_name,
1059 Handle class_loader,
1060 ClassFileStream* st,
1061 const ClassLoadInfo& cl_info,
1062 TRAPS) {
1063
1064 EventClassLoad class_load_start_event;
1065 ClassLoaderData* loader_data;
1066 bool is_unsafe_anon_class = cl_info.unsafe_anonymous_host() != NULL;
1067
1068 // - for unsafe anonymous class: create a new CLD whith a class holder that uses
1069 // the same class loader as the unsafe_anonymous_host.
1070 // - for hidden classes that are not strong: create a new CLD that has a class holder and
1071 // whose loader is the Lookup class's loader.
1072 // - for hidden class: add the class to the Lookup class's loader's CLD.
1073 if (is_unsafe_anon_class || cl_info.is_hidden()) {
1074 guarantee(!is_unsafe_anon_class || cl_info.unsafe_anonymous_host()->class_loader() == class_loader(),
1075 "should be NULL or the same");
1076 bool create_mirror_cld = is_unsafe_anon_class || !cl_info.is_strong_hidden();
1077 loader_data = register_loader(class_loader, create_mirror_cld);
1078 } else {
1079 loader_data = ClassLoaderData::class_loader_data(class_loader());
1080 }
1081
1082 assert(st != NULL, "invariant");
1083 assert(st->need_verify(), "invariant");
1084
1085 // Parse stream and create a klass.
1086 // Note that we do this even though this klass might
1087 // already be present in the SystemDictionary, otherwise we would not
1088 // throw potential ClassFormatErrors.
1089
1090 InstanceKlass* k = KlassFactory::create_from_stream(st,
1091 class_name,
1092 loader_data,
1093 cl_info,
1094 CHECK_NULL);
1095
1096 if ((cl_info.is_hidden() || is_unsafe_anon_class) && k != NULL) {
1097 // Hidden classes that are not strong and unsafe anonymous classes must update
1098 // ClassLoaderData holder so that they can be unloaded when the mirror is no
1099 // longer referenced.
1100 if (!cl_info.is_strong_hidden() || is_unsafe_anon_class) {
1101 k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
1102 }
1103
1104 {
1105 MutexLocker mu_r(THREAD, Compile_lock);
1106
1107 // Add to class hierarchy, initialize vtables, and do possible
1108 // deoptimizations.
1109 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1110 // But, do not add to dictionary.
1111 }
1112
1113 // Rewrite and patch constant pool here.
1114 k->link_class(CHECK_NULL);
1115 if (cl_info.cp_patches() != NULL) {
1116 k->constants()->patch_resolved_references(cl_info.cp_patches());
1117 }
1118
1119 // If it's anonymous, initialize it now, since nobody else will.
1120 if (is_unsafe_anon_class) {
1121 k->eager_initialize(CHECK_NULL);
1122 }
1123
1124 // notify jvmti
1125 if (JvmtiExport::should_post_class_load()) {
1126 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1127 JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1128 }
1129 if (class_load_start_event.should_commit()) {
1130 post_class_load_event(&class_load_start_event, k, loader_data);
1131 }
1132 }
1133 assert(is_unsafe_anon_class || NULL == cl_info.cp_patches(),
1134 "cp_patches only found with unsafe_anonymous_host");
1135
1136 return k;
1137 }
1138
1139 // Add a klass to the system from a stream (called by jni_DefineClass and
1140 // JVM_DefineClass).
1141 // Note: class_name can be NULL. In that case we do not know the name of
1142 // the class until we have parsed the stream.
1143
1144 InstanceKlass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1145 Handle class_loader,
1146 Handle protection_domain,
1147 ClassFileStream* st,
1148 TRAPS) {
1149
1150 HandleMark hm(THREAD);
1151
1152 // Classloaders that support parallelism, e.g. bootstrap classloader,
1153 // do not acquire lock here
1154 bool DoObjectLock = true;
1155 if (is_parallelCapable(class_loader)) {
1156 DoObjectLock = false;
1157 }
1158
1159 ClassLoaderData* loader_data = register_loader(class_loader);
1160
1161 // Make sure we are synchronized on the class loader before we proceed
1162 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1163 check_loader_lock_contention(lockObject, THREAD);
1164 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1165
1166 assert(st != NULL, "invariant");
1167
1168 // Parse the stream and create a klass.
1169 // Note that we do this even though this klass might
1170 // already be present in the SystemDictionary, otherwise we would not
1171 // throw potential ClassFormatErrors.
1172 InstanceKlass* k = NULL;
1173
1174 #if INCLUDE_CDS
1175 if (!DumpSharedSpaces) {
1176 k = SystemDictionaryShared::lookup_from_stream(class_name,
1177 class_loader,
1178 protection_domain,
1179 st,
1180 CHECK_NULL);
1181 }
1182 #endif
1183
1184 if (k == NULL) {
1185 if (st->buffer() == NULL) {
1186 return NULL;
1187 }
1188 ClassLoadInfo cl_info(protection_domain);
1189 k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
1190 }
1191
1192 assert(k != NULL, "no klass created");
1193 Symbol* h_name = k->name();
1194 assert(class_name == NULL || class_name == h_name, "name mismatch");
1195
1196 // Add class just loaded
1197 // If a class loader supports parallel classloading handle parallel define requests
1198 // find_or_define_instance_class may return a different InstanceKlass
1199 if (is_parallelCapable(class_loader)) {
1200 InstanceKlass* defined_k = find_or_define_instance_class(h_name, class_loader, k, THREAD);
1201 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1202 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1203 assert(defined_k != NULL, "Should have a klass if there's no exception");
1204 loader_data->add_to_deallocate_list(k);
1205 k = defined_k;
1206 }
1207 } else {
1208 define_instance_class(k, THREAD);
1209 }
1210
1211 // If defining the class throws an exception register 'k' for cleanup.
1212 if (HAS_PENDING_EXCEPTION) {
1213 assert(k != NULL, "Must have an instance klass here!");
1214 loader_data->add_to_deallocate_list(k);
1215 return NULL;
1216 }
1217
1218 // Make sure we have an entry in the SystemDictionary on success
1219 debug_only( {
1220 MutexLocker mu(THREAD, SystemDictionary_lock);
1221
1222 Klass* check = find_class(h_name, k->class_loader_data());
1223 assert(check == k, "should be present in the dictionary");
1224 } );
1225
1226 return k;
1227 }
1228
1229 #if INCLUDE_CDS
1230 // Load a class for boot loader from the shared spaces. This also
1231 // forces the super class and all interfaces to be loaded.
1232 InstanceKlass* SystemDictionary::load_shared_boot_class(Symbol* class_name,
1233 PackageEntry* pkg_entry,
1234 TRAPS) {
1235 InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1236 if (ik != NULL && ik->is_shared_boot_class()) {
1237 return load_shared_class(ik, Handle(), Handle(), NULL, pkg_entry, THREAD);
1238 }
1239 return NULL;
1240 }
1241
1242 // Check if a shared class can be loaded by the specific classloader:
1243 //
1244 // NULL classloader:
1245 // - Module class from "modules" jimage. ModuleEntry must be defined in the classloader.
1246 // - Class from -Xbootclasspath/a. The class has no defined PackageEntry, or must
1247 // be defined in an unnamed module.
1248 bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
1249 InstanceKlass* ik,
1250 PackageEntry* pkg_entry,
1251 Handle class_loader, TRAPS) {
1252 assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
1253 "Cannot use sharing if java.base is patched");
1254 ResourceMark rm(THREAD);
1255 int path_index = ik->shared_classpath_index();
1256 ClassLoaderData* loader_data = class_loader_data(class_loader);
1257 if (path_index < 0) {
1258 // path_index < 0 indicates that the class is intended for a custom loader
1259 // and should not be loaded by boot/platform/app loaders
1260 if (loader_data->is_builtin_class_loader_data()) {
1261 return false;
1262 } else {
1263 return true;
1264 }
1265 }
1266 SharedClassPathEntry* ent =
1267 (SharedClassPathEntry*)FileMapInfo::shared_path(path_index);
1268 if (!Universe::is_module_initialized()) {
1269 assert(ent != NULL && ent->is_modules_image(),
1270 "Loading non-bootstrap classes before the module system is initialized");
1271 assert(class_loader.is_null(), "sanity");
1272 return true;
1273 }
1274 // Get the pkg_entry from the classloader
1275 ModuleEntry* mod_entry = NULL;
1276 TempNewSymbol pkg_name = pkg_entry != NULL ? pkg_entry->name() :
1277 ClassLoader::package_from_class_name(class_name);
1278 if (pkg_name != NULL) {
1279 if (loader_data != NULL) {
1280 if (pkg_entry != NULL) {
1281 mod_entry = pkg_entry->module();
1282 // If the archived class is from a module that has been patched at runtime,
1283 // the class cannot be loaded from the archive.
1284 if (mod_entry != NULL && mod_entry->is_patched()) {
1285 return false;
1286 }
1287 }
1288 }
1289 }
1290
1291 if (class_loader.is_null()) {
1292 assert(ent != NULL, "Shared class for NULL classloader must have valid SharedClassPathEntry");
1293 // The NULL classloader can load archived class originated from the
1294 // "modules" jimage and the -Xbootclasspath/a. For class from the
1295 // "modules" jimage, the PackageEntry/ModuleEntry must be defined
1296 // by the NULL classloader.
1297 if (mod_entry != NULL) {
1298 // PackageEntry/ModuleEntry is found in the classloader. Check if the
1299 // ModuleEntry's location agrees with the archived class' origination.
1300 if (ent->is_modules_image() && mod_entry->location()->starts_with("jrt:")) {
1301 return true; // Module class from the "module" jimage
1302 }
1303 }
1304
1305 // If the archived class is not from the "module" jimage, the class can be
1306 // loaded by the NULL classloader if
1307 //
1308 // 1. the class is from the unamed package
1309 // 2. or, the class is not from a module defined in the NULL classloader
1310 // 3. or, the class is from an unamed module
1311 if (!ent->is_modules_image() && ik->is_shared_boot_class()) {
1312 // the class is from the -Xbootclasspath/a
1313 if (pkg_name == NULL ||
1314 pkg_entry == NULL ||
1315 pkg_entry->in_unnamed_module()) {
1316 assert(mod_entry == NULL ||
1317 mod_entry == loader_data->unnamed_module(),
1318 "the unnamed module is not defined in the classloader");
1319 return true;
1320 }
1321 }
1322 return false;
1323 } else {
1324 bool res = SystemDictionaryShared::is_shared_class_visible_for_classloader(
1325 ik, class_loader, pkg_name, pkg_entry, mod_entry, CHECK_(false));
1326 return res;
1327 }
1328 }
1329
1330 bool SystemDictionary::check_shared_class_super_type(InstanceKlass* child, InstanceKlass* super_type,
1331 Handle class_loader, Handle protection_domain,
1332 bool is_superclass, TRAPS) {
1333 assert(super_type->is_shared(), "must be");
1334
1335 Klass *found = resolve_super_or_fail(child->name(), super_type->name(),
1336 class_loader, protection_domain, is_superclass, CHECK_0);
1337 if (found == super_type) {
1338 return true;
1339 } else {
1340 // The dynamically resolved super type is not the same as the one we used during dump time,
1341 // so we cannot use the child class.
1342 return false;
1343 }
1344 }
1345
1346 bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1347 Handle protection_domain, TRAPS) {
1348 // Check the superclass and interfaces. They must be the same
1349 // as in dump time, because the layout of <ik> depends on
1350 // the specific layout of ik->super() and ik->local_interfaces().
1351 //
1352 // If unexpected superclass or interfaces are found, we cannot
1353 // load <ik> from the shared archive.
1354
1355 if (ik->super() != NULL &&
1356 !check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1357 class_loader, protection_domain, true, THREAD)) {
1358 return false;
1359 }
1360
1361 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1362 int num_interfaces = interfaces->length();
1363 for (int index = 0; index < num_interfaces; index++) {
1364 if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) {
1365 return false;
1366 }
1367 }
1368
1369 return true;
1370 }
1371
1372 InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1373 Handle class_loader,
1374 Handle protection_domain,
1375 const ClassFileStream *cfs,
1376 PackageEntry* pkg_entry,
1377 TRAPS) {
1378 assert(ik != NULL, "sanity");
1379 assert(!ik->is_unshareable_info_restored(), "shared class can be loaded only once");
1380 Symbol* class_name = ik->name();
1381
1382 bool visible = is_shared_class_visible(
1383 class_name, ik, pkg_entry, class_loader, CHECK_NULL);
1384 if (!visible) {
1385 return NULL;
1386 }
1387
1388 if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {
1389 return NULL;
1390 }
1391
1392 InstanceKlass* new_ik = KlassFactory::check_shared_class_file_load_hook(
1393 ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1394 if (new_ik != NULL) {
1395 // The class is changed by CFLH. Return the new class. The shared class is
1396 // not used.
1397 return new_ik;
1398 }
1399
1400 // Adjust methods to recover missing data. They need addresses for
1401 // interpreter entry points and their default native method address
1402 // must be reset.
1403
1404 // Updating methods must be done under a lock so multiple
1405 // threads don't update these in parallel
1406 //
1407 // Shared classes are all currently loaded by either the bootstrap or
1408 // internal parallel class loaders, so this will never cause a deadlock
1409 // on a custom class loader lock.
1410
1411 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1412 {
1413 HandleMark hm(THREAD);
1414 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1415 check_loader_lock_contention(lockObject, THREAD);
1416 ObjectLocker ol(lockObject, THREAD, true);
1417 // prohibited package check assumes all classes loaded from archive call
1418 // restore_unshareable_info which calls ik->set_package()
1419 ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1420 }
1421
1422 load_shared_class_misc(ik, loader_data, CHECK_NULL);
1423 return ik;
1424 }
1425
1426 void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data, TRAPS) {
1427 ik->print_class_load_logging(loader_data, NULL, NULL);
1428
1429 // For boot loader, ensure that GetSystemPackage knows that a class in this
1430 // package was loaded.
1431 if (loader_data->is_the_null_class_loader_data()) {
1432 int path_index = ik->shared_classpath_index();
1433 ik->set_classpath_index(path_index, THREAD);
1434 }
1435
1436 if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1437 // Only dump the classes that can be stored into CDS archive
1438 if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1439 ResourceMark rm(THREAD);
1440 classlist_file->print_cr("%s", ik->name()->as_C_string());
1441 classlist_file->flush();
1442 }
1443 }
1444
1445 // notify a class loaded from shared object
1446 ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1447
1448 ik->set_has_passed_fingerprint_check(false);
1449 if (UseAOT && ik->supers_have_passed_fingerprint_checks()) {
1450 uint64_t aot_fp = AOTLoader::get_saved_fingerprint(ik);
1451 uint64_t cds_fp = ik->get_stored_fingerprint();
1452 if (aot_fp != 0 && aot_fp == cds_fp) {
1453 // This class matches with a class saved in an AOT library
1454 ik->set_has_passed_fingerprint_check(true);
1455 } else {
1456 if (log_is_enabled(Info, class, fingerprint)) {
1457 ResourceMark rm(THREAD);
1458 log_info(class, fingerprint)("%s : expected = " PTR64_FORMAT " actual = " PTR64_FORMAT, ik->external_name(), aot_fp, cds_fp);
1459 }
1460 }
1461 }
1462 }
1463
1464 void SystemDictionary::quick_resolve(InstanceKlass* klass, ClassLoaderData* loader_data, Handle domain, TRAPS) {
1465 assert(!Universe::is_fully_initialized(), "We can make short cuts only during VM initialization");
1466 assert(klass->is_shared(), "Must be shared class");
1467 if (klass->class_loader_data() != NULL) {
1468 return;
1469 }
1470
1471 // add super and interfaces first
1472 Klass* super = klass->super();
1473 if (super != NULL && super->class_loader_data() == NULL) {
1474 assert(super->is_instance_klass(), "Super should be instance klass");
1475 quick_resolve(InstanceKlass::cast(super), loader_data, domain, CHECK);
1476 }
1477
1478 Array<InstanceKlass*>* ifs = klass->local_interfaces();
1479 for (int i = 0; i < ifs->length(); i++) {
1480 InstanceKlass* ik = ifs->at(i);
1481 if (ik->class_loader_data() == NULL) {
1482 quick_resolve(ik, loader_data, domain, CHECK);
1483 }
1484 }
1485
1486 klass->restore_unshareable_info(loader_data, domain, NULL, THREAD);
1487 load_shared_class_misc(klass, loader_data, CHECK);
1488 Dictionary* dictionary = loader_data->dictionary();
1489 unsigned int hash = dictionary->compute_hash(klass->name());
1490 dictionary->add_klass(hash, klass->name(), klass);
1491 add_to_hierarchy(klass, CHECK);
1492 assert(klass->is_loaded(), "Must be in at least loaded state");
1493 }
1494 #endif // INCLUDE_CDS
1495
1496 InstanceKlass* SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1497
1498 if (class_loader.is_null()) {
1499 ResourceMark rm(THREAD);
1500 PackageEntry* pkg_entry = NULL;
1501 bool search_only_bootloader_append = false;
1502 ClassLoaderData *loader_data = class_loader_data(class_loader);
1503
1504 // Find the package in the boot loader's package entry table.
1505 TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1506 if (pkg_name != NULL) {
1507 pkg_entry = loader_data->packages()->lookup_only(pkg_name);
1508 }
1509
1510 // Prior to attempting to load the class, enforce the boot loader's
1511 // visibility boundaries.
1512 if (!Universe::is_module_initialized()) {
1513 // During bootstrapping, prior to module initialization, any
1514 // class attempting to be loaded must be checked against the
1515 // java.base packages in the boot loader's PackageEntryTable.
1516 // No class outside of java.base is allowed to be loaded during
1517 // this bootstrapping window.
1518 if (pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1519 // Class is either in the unnamed package or in
1520 // a named package within the unnamed module. Either
1521 // case is outside of java.base, do not attempt to
1522 // load the class post java.base definition. If
1523 // java.base has not been defined, let the class load
1524 // and its package will be checked later by
1525 // ModuleEntryTable::verify_javabase_packages.
1526 if (ModuleEntryTable::javabase_defined()) {
1527 return NULL;
1528 }
1529 } else {
1530 // Check that the class' package is defined within java.base.
1531 ModuleEntry* mod_entry = pkg_entry->module();
1532 Symbol* mod_entry_name = mod_entry->name();
1533 if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {
1534 return NULL;
1535 }
1536 }
1537 } else {
1538 // After the module system has been initialized, check if the class'
1539 // package is in a module defined to the boot loader.
1540 if (pkg_name == NULL || pkg_entry == NULL || pkg_entry->in_unnamed_module()) {
1541 // Class is either in the unnamed package, in a named package
1542 // within a module not defined to the boot loader or in a
1543 // a named package within the unnamed module. In all cases,
1544 // limit visibility to search for the class only in the boot
1545 // loader's append path.
1546 if (!ClassLoader::has_bootclasspath_append()) {
1547 // If there is no bootclasspath append entry, no need to continue
1548 // searching.
1549 return NULL;
1550 }
1551 search_only_bootloader_append = true;
1552 }
1553 }
1554
1555 // Prior to bootstrapping's module initialization, never load a class outside
1556 // of the boot loader's module path
1557 assert(Universe::is_module_initialized() ||
1558 !search_only_bootloader_append,
1559 "Attempt to load a class outside of boot loader's module path");
1560
1561 // Search for classes in the CDS archive.
1562 InstanceKlass* k = NULL;
1563 {
1564 #if INCLUDE_CDS
1565 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1566 k = load_shared_boot_class(class_name, pkg_entry, THREAD);
1567 #endif
1568 }
1569
1570 if (k == NULL) {
1571 // Use VM class loader
1572 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1573 k = ClassLoader::load_class(class_name, search_only_bootloader_append, CHECK_NULL);
1574 }
1575
1576 // find_or_define_instance_class may return a different InstanceKlass
1577 if (k != NULL) {
1578 InstanceKlass* defined_k =
1579 find_or_define_instance_class(class_name, class_loader, k, THREAD);
1580 if (!HAS_PENDING_EXCEPTION && defined_k != k) {
1581 // If a parallel capable class loader already defined this class, register 'k' for cleanup.
1582 assert(defined_k != NULL, "Should have a klass if there's no exception");
1583 loader_data->add_to_deallocate_list(k);
1584 k = defined_k;
1585 } else if (HAS_PENDING_EXCEPTION) {
1586 loader_data->add_to_deallocate_list(k);
1587 return NULL;
1588 }
1589 }
1590 return k;
1591 } else {
1592 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1593 ResourceMark rm(THREAD);
1594
1595 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1596 JavaThread* jt = (JavaThread*) THREAD;
1597
1598 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1599 ClassLoader::perf_app_classload_selftime(),
1600 ClassLoader::perf_app_classload_count(),
1601 jt->get_thread_stat()->perf_recursion_counts_addr(),
1602 jt->get_thread_stat()->perf_timers_addr(),
1603 PerfClassTraceTime::CLASS_LOAD);
1604
1605 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_NULL);
1606 // Translate to external class name format, i.e., convert '/' chars to '.'
1607 Handle string = java_lang_String::externalize_classname(s, CHECK_NULL);
1608
1609 JavaValue result(T_OBJECT);
1610
1611 InstanceKlass* spec_klass = SystemDictionary::ClassLoader_klass();
1612
1613 // Call public unsynchronized loadClass(String) directly for all class loaders.
1614 // For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1615 // acquire a class-name based lock rather than the class loader object lock.
1616 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1617 JavaCalls::call_virtual(&result,
1618 class_loader,
1619 spec_klass,
1620 vmSymbols::loadClass_name(),
1621 vmSymbols::string_class_signature(),
1622 string,
1623 CHECK_NULL);
1624
1625 assert(result.get_type() == T_OBJECT, "just checking");
1626 oop obj = (oop) result.get_jobject();
1627
1628 // Primitive classes return null since forName() can not be
1629 // used to obtain any of the Class objects representing primitives or void
1630 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1631 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1632 // For user defined Java class loaders, check that the name returned is
1633 // the same as that requested. This check is done for the bootstrap
1634 // loader when parsing the class file.
1635 if (class_name == k->name()) {
1636 return k;
1637 }
1638 }
1639 // Class is not found or has the wrong name, return NULL
1640 return NULL;
1641 }
1642 }
1643
1644 static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {
1645 EventClassDefine event;
1646 if (event.should_commit()) {
1647 event.set_definedClass(k);
1648 event.set_definingClassLoader(def_cld);
1649 event.commit();
1650 }
1651 }
1652
1653 void SystemDictionary::define_instance_class(InstanceKlass* k, TRAPS) {
1654
1655 HandleMark hm(THREAD);
1656 ClassLoaderData* loader_data = k->class_loader_data();
1657 Handle class_loader_h(THREAD, loader_data->class_loader());
1658
1659 // for bootstrap and other parallel classloaders don't acquire lock,
1660 // use placeholder token
1661 // If a parallelCapable class loader calls define_instance_class instead of
1662 // find_or_define_instance_class to get here, we have a timing
1663 // hole with systemDictionary updates and check_constraints
1664 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1665 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1666 compute_loader_lock_object(class_loader_h, THREAD)),
1667 "define called without lock");
1668 }
1669
1670 // Check class-loading constraints. Throw exception if violation is detected.
1671 // Grabs and releases SystemDictionary_lock
1672 // The check_constraints/find_class call and update_dictionary sequence
1673 // must be "atomic" for a specific class/classloader pair so we never
1674 // define two different instanceKlasses for that class/classloader pair.
1675 // Existing classloaders will call define_instance_class with the
1676 // classloader lock held
1677 // Parallel classloaders will call find_or_define_instance_class
1678 // which will require a token to perform the define class
1679 Symbol* name_h = k->name();
1680 Dictionary* dictionary = loader_data->dictionary();
1681 unsigned int d_hash = dictionary->compute_hash(name_h);
1682 check_constraints(d_hash, k, class_loader_h, true, CHECK);
1683
1684 // Register class just loaded with class loader (placed in ArrayList)
1685 // Note we do this before updating the dictionary, as this can
1686 // fail with an OutOfMemoryError (if it does, we will *not* put this
1687 // class in the dictionary and will not update the class hierarchy).
1688 // JVMTI FollowReferences needs to find the classes this way.
1689 if (k->class_loader() != NULL) {
1690 methodHandle m(THREAD, Universe::loader_addClass_method());
1691 JavaValue result(T_VOID);
1692 JavaCallArguments args(class_loader_h);
1693 args.push_oop(Handle(THREAD, k->java_mirror()));
1694 JavaCalls::call(&result, m, &args, CHECK);
1695 }
1696
1697 // Add the new class. We need recompile lock during update of CHA.
1698 {
1699 unsigned int p_hash = placeholders()->compute_hash(name_h);
1700 int p_index = placeholders()->hash_to_index(p_hash);
1701
1702 MutexLocker mu_r(THREAD, Compile_lock);
1703
1704 // Add to class hierarchy, initialize vtables, and do possible
1705 // deoptimizations.
1706 add_to_hierarchy(k, CHECK); // No exception, but can block
1707
1708 // Add to systemDictionary - so other classes can see it.
1709 // Grabs and releases SystemDictionary_lock
1710 update_dictionary(d_hash, p_index, p_hash,
1711 k, class_loader_h, THREAD);
1712 }
1713 k->eager_initialize(THREAD);
1714
1715 // notify jvmti
1716 if (JvmtiExport::should_post_class_load()) {
1717 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1718 JvmtiExport::post_class_load((JavaThread *) THREAD, k);
1719
1720 }
1721 post_class_define_event(k, loader_data);
1722 }
1723
1724 // Support parallel classloading
1725 // All parallel class loaders, including bootstrap classloader
1726 // lock a placeholder entry for this class/class_loader pair
1727 // to allow parallel defines of different classes for this class loader
1728 // With AllowParallelDefine flag==true, in case they do not synchronize around
1729 // FindLoadedClass/DefineClass, calls, we check for parallel
1730 // loading for them, wait if a defineClass is in progress
1731 // and return the initial requestor's results
1732 // This flag does not apply to the bootstrap classloader.
1733 // With AllowParallelDefine flag==false, call through to define_instance_class
1734 // which will throw LinkageError: duplicate class definition.
1735 // False is the requested default.
1736 // For better performance, the class loaders should synchronize
1737 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1738 // potentially waste time reading and parsing the bytestream.
1739 // Note: VM callers should ensure consistency of k/class_name,class_loader
1740 // Be careful when modifying this code: once you have run
1741 // placeholders()->find_and_add(PlaceholderTable::DEFINE_CLASS),
1742 // you need to find_and_remove it before returning.
1743 // So be careful to not exit with a CHECK_ macro betweeen these calls.
1744 InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1745 InstanceKlass* k, TRAPS) {
1746
1747 Symbol* name_h = k->name(); // passed in class_name may be null
1748 ClassLoaderData* loader_data = class_loader_data(class_loader);
1749 Dictionary* dictionary = loader_data->dictionary();
1750
1751 unsigned int d_hash = dictionary->compute_hash(name_h);
1752
1753 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1754 unsigned int p_hash = placeholders()->compute_hash(name_h);
1755 int p_index = placeholders()->hash_to_index(p_hash);
1756 PlaceholderEntry* probe;
1757
1758 {
1759 MutexLocker mu(THREAD, SystemDictionary_lock);
1760 // First check if class already defined
1761 if (is_parallelDefine(class_loader)) {
1762 InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1763 if (check != NULL) {
1764 return check;
1765 }
1766 }
1767
1768 // Acquire define token for this class/classloader
1769 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1770 // Wait if another thread defining in parallel
1771 // All threads wait - even those that will throw duplicate class: otherwise
1772 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1773 // if other thread has not finished updating dictionary
1774 while (probe->definer() != NULL) {
1775 SystemDictionary_lock->wait();
1776 }
1777 // Only special cases allow parallel defines and can use other thread's results
1778 // Other cases fall through, and may run into duplicate defines
1779 // caught by finding an entry in the SystemDictionary
1780 if (is_parallelDefine(class_loader) && (probe->instance_klass() != NULL)) {
1781 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1782 SystemDictionary_lock->notify_all();
1783 #ifdef ASSERT
1784 InstanceKlass* check = find_class(d_hash, name_h, dictionary);
1785 assert(check != NULL, "definer missed recording success");
1786 #endif
1787 return probe->instance_klass();
1788 } else {
1789 // This thread will define the class (even if earlier thread tried and had an error)
1790 probe->set_definer(THREAD);
1791 }
1792 }
1793
1794 define_instance_class(k, THREAD);
1795
1796 Handle linkage_exception = Handle(); // null handle
1797
1798 // definer must notify any waiting threads
1799 {
1800 MutexLocker mu(THREAD, SystemDictionary_lock);
1801 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1802 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1803 if (probe != NULL) {
1804 if (HAS_PENDING_EXCEPTION) {
1805 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1806 CLEAR_PENDING_EXCEPTION;
1807 } else {
1808 probe->set_instance_klass(k);
1809 }
1810 probe->set_definer(NULL);
1811 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1812 SystemDictionary_lock->notify_all();
1813 }
1814 }
1815
1816 // Can't throw exception while holding lock due to rank ordering
1817 if (linkage_exception() != NULL) {
1818 THROW_OOP_(linkage_exception(), NULL); // throws exception and returns
1819 }
1820
1821 return k;
1822 }
1823
1824 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1825 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1826 if (class_loader.is_null()) {
1827 return Handle(THREAD, _system_loader_lock_obj.resolve());
1828 } else {
1829 return class_loader;
1830 }
1831 }
1832
1833 // This method is added to check how often we have to wait to grab loader
1834 // lock. The results are being recorded in the performance counters defined in
1835 // ClassLoader::_sync_systemLoaderLockContentionRate and
1836 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1837 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1838 if (!UsePerfData) {
1839 return;
1840 }
1841
1842 assert(!loader_lock.is_null(), "NULL lock object");
1843
1844 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1845 == ObjectSynchronizer::owner_other) {
1846 // contention will likely happen, so increment the corresponding
1847 // contention counter.
1848 if (loader_lock() == _system_loader_lock_obj.resolve()) {
1849 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1850 } else {
1851 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1852 }
1853 }
1854 }
1855
1856 // ----------------------------------------------------------------------------
1857 // Lookup
1858
1859 InstanceKlass* SystemDictionary::find_class(unsigned int hash,
1860 Symbol* class_name,
1861 Dictionary* dictionary) {
1862 assert_locked_or_safepoint(SystemDictionary_lock);
1863 int index = dictionary->hash_to_index(hash);
1864 return dictionary->find_class(index, hash, class_name);
1865 }
1866
1867
1868 // Basic find on classes in the midst of being loaded
1869 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1870 ClassLoaderData* loader_data) {
1871 assert_locked_or_safepoint(SystemDictionary_lock);
1872 unsigned int p_hash = placeholders()->compute_hash(class_name);
1873 int p_index = placeholders()->hash_to_index(p_hash);
1874 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1875 }
1876
1877
1878 // Used for assertions and verification only
1879 // Precalculating the hash and index is an optimization because there are many lookups
1880 // before adding the class.
1881 InstanceKlass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1882 assert_locked_or_safepoint(SystemDictionary_lock);
1883 #ifndef ASSERT
1884 guarantee(VerifyBeforeGC ||
1885 VerifyDuringGC ||
1886 VerifyBeforeExit ||
1887 VerifyDuringStartup ||
1888 VerifyAfterGC, "too expensive");
1889 #endif
1890
1891 Dictionary* dictionary = loader_data->dictionary();
1892 unsigned int d_hash = dictionary->compute_hash(class_name);
1893 return find_class(d_hash, class_name, dictionary);
1894 }
1895
1896
1897 // ----------------------------------------------------------------------------
1898 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1899 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1900 // before a new class is used.
1901
1902 void SystemDictionary::add_to_hierarchy(InstanceKlass* k, TRAPS) {
1903 assert(k != NULL, "just checking");
1904 if (Universe::is_fully_initialized()) {
1905 assert_locked_or_safepoint(Compile_lock);
1906 }
1907
1908 k->set_init_state(InstanceKlass::loaded);
1909 // make sure init_state store is already done.
1910 // The compiler reads the hierarchy outside of the Compile_lock.
1911 // Access ordering is used to add to hierarchy.
1912
1913 // Link into hierachy.
1914 k->append_to_sibling_list(); // add to superklass/sibling list
1915 k->process_interfaces(THREAD); // handle all "implements" declarations
1916
1917 // Now flush all code that depended on old class hierarchy.
1918 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1919 if (Universe::is_fully_initialized()) {
1920 CodeCache::flush_dependents_on(k);
1921 }
1922 }
1923
1924 // ----------------------------------------------------------------------------
1925 // GC support
1926
1927 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1928 // Note: anonymous classes are not in the SD.
1929 bool SystemDictionary::do_unloading(GCTimer* gc_timer) {
1930
1931 bool unloading_occurred;
1932 bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1933 {
1934 GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);
1935 assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1936 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1937 unloading_occurred = ClassLoaderDataGraph::do_unloading();
1938 if (unloading_occurred) {
1939 MutexLocker ml2(is_concurrent ? Module_lock : NULL);
1940 JFR_ONLY(Jfr::on_unloading_classes();)
1941
1942 MutexLocker ml1(is_concurrent ? SystemDictionary_lock : NULL);
1943 ClassLoaderDataGraph::clean_module_and_package_info();
1944 constraints()->purge_loader_constraints();
1945 resolution_errors()->purge_resolution_errors();
1946 }
1947 }
1948
1949 GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);
1950
1951 if (unloading_occurred) {
1952 SymbolTable::trigger_cleanup();
1953
1954 // Oops referenced by the protection domain cache table may get unreachable independently
1955 // of the class loader (eg. cached protection domain oops). So we need to
1956 // explicitly unlink them here.
1957 // All protection domain oops are linked to the caller class, so if nothing
1958 // unloads, this is not needed.
1959 _pd_cache_table->trigger_cleanup();
1960 }
1961
1962 return unloading_occurred;
1963 }
1964
1965 // CDS: scan and relocate all classes referenced by _well_known_klasses[].
1966 void SystemDictionary::well_known_klasses_do(MetaspaceClosure* it) {
1967 for (int id = FIRST_WKID; id < WKID_LIMIT; id++) {
1968 it->push(well_known_klass_addr((WKID)id));
1969 }
1970 }
1971
1972 void SystemDictionary::methods_do(void f(Method*)) {
1973 // Walk methods in loaded classes
1974 MutexLocker ml(ClassLoaderDataGraph_lock);
1975 ClassLoaderDataGraph::methods_do(f);
1976 // Walk method handle intrinsics
1977 invoke_method_table()->methods_do(f);
1978 }
1979
1980 // ----------------------------------------------------------------------------
1981 // Initialization
1982
1983 void SystemDictionary::initialize(TRAPS) {
1984 // Allocate arrays
1985 _placeholders = new PlaceholderTable(_placeholder_table_size);
1986 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1987 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1988 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1989 _pd_cache_table = new ProtectionDomainCacheTable(defaultProtectionDomainCacheSize);
1990
1991 // Allocate private object used as system class loader lock
1992 oop lock_obj = oopFactory::new_intArray(0, CHECK);
1993 _system_loader_lock_obj = OopHandle::create(lock_obj);
1994
1995 // Initialize basic classes
1996 resolve_well_known_classes(CHECK);
1997 }
1998
1999 // Compact table of directions on the initialization of klasses:
2000 static const short wk_init_info[] = {
2001 #define WK_KLASS_INIT_INFO(name, symbol) \
2002 ((short)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol)),
2003
2004 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
2005 #undef WK_KLASS_INIT_INFO
2006 0
2007 };
2008
2009 #ifdef ASSERT
2010 bool SystemDictionary::is_well_known_klass(Symbol* class_name) {
2011 int sid;
2012 for (int i = 0; (sid = wk_init_info[i]) != 0; i++) {
2013 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
2014 if (class_name == symbol) {
2015 return true;
2016 }
2017 }
2018 return false;
2019 }
2020 #endif
2021
2022 bool SystemDictionary::resolve_wk_klass(WKID id, TRAPS) {
2023 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
2024 int sid = wk_init_info[id - FIRST_WKID];
2025 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
2026 InstanceKlass** klassp = &_well_known_klasses[id];
2027
2028 #if INCLUDE_CDS
2029 if (UseSharedSpaces && !JvmtiExport::should_post_class_prepare()) {
2030 InstanceKlass* k = *klassp;
2031 assert(k->is_shared_boot_class(), "must be");
2032
2033 ClassLoaderData* loader_data = ClassLoaderData::the_null_class_loader_data();
2034 quick_resolve(k, loader_data, Handle(), CHECK_false);
2035 return true;
2036 }
2037 #endif // INCLUDE_CDS
2038
2039 if (!is_wk_klass_loaded(*klassp)) {
2040 Klass* k = resolve_or_fail(symbol, true, CHECK_false);
2041 (*klassp) = InstanceKlass::cast(k);
2042 }
2043 return ((*klassp) != NULL);
2044 }
2045
2046 void SystemDictionary::resolve_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
2047 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
2048 for (int id = (int)start_id; id < (int)limit_id; id++) {
2049 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
2050 resolve_wk_klass((WKID)id, CHECK);
2051 }
2052
2053 // move the starting value forward to the limit:
2054 start_id = limit_id;
2055 }
2056
2057 void SystemDictionary::resolve_well_known_classes(TRAPS) {
2058 assert(!Object_klass_loaded(), "well-known classes should only be initialized once");
2059
2060 // Create the ModuleEntry for java.base. This call needs to be done here,
2061 // after vmSymbols::initialize() is called but before any classes are pre-loaded.
2062 ClassLoader::classLoader_init2(CHECK);
2063
2064 // Preload commonly used klasses
2065 WKID scan = FIRST_WKID;
2066 // first do Object, then String, Class
2067 #if INCLUDE_CDS
2068 if (UseSharedSpaces) {
2069 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
2070
2071 // It's unsafe to access the archived heap regions before they
2072 // are fixed up, so we must do the fixup as early as possible
2073 // before the archived java objects are accessed by functions
2074 // such as java_lang_Class::restore_archived_mirror and
2075 // ConstantPool::restore_unshareable_info (restores the archived
2076 // resolved_references array object).
2077 //
2078 // HeapShared::fixup_mapped_heap_regions() fills the empty
2079 // spaces in the archived heap regions and may use
2080 // SystemDictionary::Object_klass(), so we can do this only after
2081 // Object_klass is resolved. See the above resolve_wk_klasses_through()
2082 // call. No mirror objects are accessed/restored in the above call.
2083 // Mirrors are restored after java.lang.Class is loaded.
2084 HeapShared::fixup_mapped_heap_regions();
2085
2086 // Initialize the constant pool for the Object_class
2087 assert(Object_klass()->is_shared(), "must be");
2088 Object_klass()->constants()->restore_unshareable_info(CHECK);
2089 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2090 } else
2091 #endif
2092 {
2093 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
2094 }
2095
2096 assert(WK_KLASS(Object_klass) != NULL, "well-known classes should now be initialized");
2097
2098 java_lang_Object::register_natives(CHECK);
2099
2100 // Calculate offsets for String and Class classes since they are loaded and
2101 // can be used after this point.
2102 java_lang_String::compute_offsets();
2103 java_lang_Class::compute_offsets();
2104
2105 // Fixup mirrors for classes loaded before java.lang.Class.
2106 Universe::initialize_basic_type_mirrors(CHECK);
2107 Universe::fixup_mirrors(CHECK);
2108
2109 // do a bunch more:
2110 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
2111
2112 // The offsets for jlr.Reference must be computed before
2113 // InstanceRefKlass::update_nonstatic_oop_maps is called. That function uses
2114 // the offsets to remove the referent and discovered fields from the oop maps,
2115 // as they are treated in a special way by the GC. Removing these oops from the
2116 // oop maps must be done before the usual subclasses of jlr.Reference are loaded.
2117 java_lang_ref_Reference::compute_offsets();
2118
2119 // Preload ref klasses and set reference types
2120 WK_KLASS(Reference_klass)->set_reference_type(REF_OTHER);
2121 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
2122
2123 resolve_wk_klasses_through(WK_KLASS_ENUM_NAME(PhantomReference_klass), scan, CHECK);
2124 WK_KLASS(SoftReference_klass)->set_reference_type(REF_SOFT);
2125 WK_KLASS(WeakReference_klass)->set_reference_type(REF_WEAK);
2126 WK_KLASS(FinalReference_klass)->set_reference_type(REF_FINAL);
2127 WK_KLASS(PhantomReference_klass)->set_reference_type(REF_PHANTOM);
2128
2129 // JSR 292 classes
2130 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
2131 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
2132 resolve_wk_klasses_until(jsr292_group_start, scan, CHECK);
2133 resolve_wk_klasses_through(jsr292_group_end, scan, CHECK);
2134 WKID last = WKID_LIMIT;
2135 resolve_wk_klasses_until(last, scan, CHECK);
2136
2137 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
2138 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
2139 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
2140 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
2141 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
2142 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
2143 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
2144 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
2145 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
2146 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
2147
2148 #ifdef ASSERT
2149 if (UseSharedSpaces) {
2150 JVMTI_ONLY(assert(JvmtiExport::is_early_phase(),
2151 "All well known classes must be resolved in JVMTI early phase"));
2152 for (int i = FIRST_WKID; i < last; i++) {
2153 InstanceKlass* k = _well_known_klasses[i];
2154 assert(k->is_shared(), "must not be replaced by JVMTI class file load hook");
2155 }
2156 }
2157 #endif
2158 }
2159
2160 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
2161 // If so, returns the basic type it holds. If not, returns T_OBJECT.
2162 BasicType SystemDictionary::box_klass_type(Klass* k) {
2163 assert(k != NULL, "");
2164 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
2165 if (_box_klasses[i] == k)
2166 return (BasicType)i;
2167 }
2168 return T_OBJECT;
2169 }
2170
2171 // Constraints on class loaders. The details of the algorithm can be
2172 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
2173 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
2174 // that the dictionary needs to maintain a set of contraints that
2175 // must be satisfied by all classes in the dictionary.
2176 // if defining is true, then LinkageError if already in dictionary
2177 // if initiating loader, then ok if InstanceKlass matches existing entry
2178
2179 void SystemDictionary::check_constraints(unsigned int d_hash,
2180 InstanceKlass* k,
2181 Handle class_loader,
2182 bool defining,
2183 TRAPS) {
2184 ResourceMark rm(THREAD);
2185 stringStream ss;
2186 bool throwException = false;
2187
2188 {
2189 Symbol *name = k->name();
2190 ClassLoaderData *loader_data = class_loader_data(class_loader);
2191
2192 MutexLocker mu(THREAD, SystemDictionary_lock);
2193
2194 InstanceKlass* check = find_class(d_hash, name, loader_data->dictionary());
2195 if (check != NULL) {
2196 // If different InstanceKlass - duplicate class definition,
2197 // else - ok, class loaded by a different thread in parallel.
2198 // We should only have found it if it was done loading and ok to use.
2199 // The dictionary only holds instance classes, placeholders
2200 // also hold array classes.
2201
2202 assert(check->is_instance_klass(), "noninstance in systemdictionary");
2203 if ((defining == true) || (k != check)) {
2204 throwException = true;
2205 ss.print("loader %s", loader_data->loader_name_and_id());
2206 ss.print(" attempted duplicate %s definition for %s. (%s)",
2207 k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
2208 } else {
2209 return;
2210 }
2211 }
2212
2213 #ifdef ASSERT
2214 Symbol* ph_check = find_placeholder(name, loader_data);
2215 assert(ph_check == NULL || ph_check == name, "invalid symbol");
2216 #endif
2217
2218 if (throwException == false) {
2219 if (constraints()->check_or_update(k, class_loader, name) == false) {
2220 throwException = true;
2221 ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());
2222 ss.print(" wants to load %s %s.",
2223 k->external_kind(), k->external_name());
2224 Klass *existing_klass = constraints()->find_constrained_klass(name, class_loader);
2225 if (existing_klass != NULL && existing_klass->class_loader() != class_loader()) {
2226 ss.print(" A different %s with the same name was previously loaded by %s. (%s)",
2227 existing_klass->external_kind(),
2228 existing_klass->class_loader_data()->loader_name_and_id(),
2229 existing_klass->class_in_module_of_loader(false, true));
2230 } else {
2231 ss.print(" (%s)", k->class_in_module_of_loader(false, true));
2232 }
2233 }
2234 }
2235 }
2236
2237 // Throw error now if needed (cannot throw while holding
2238 // SystemDictionary_lock because of rank ordering)
2239 if (throwException == true) {
2240 THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
2241 }
2242 }
2243
2244 // Update class loader data dictionary - done after check_constraint and add_to_hierachy
2245 // have been called.
2246 void SystemDictionary::update_dictionary(unsigned int d_hash,
2247 int p_index, unsigned int p_hash,
2248 InstanceKlass* k,
2249 Handle class_loader,
2250 TRAPS) {
2251 // Compile_lock prevents systemDictionary updates during compilations
2252 assert_locked_or_safepoint(Compile_lock);
2253 Symbol* name = k->name();
2254 ClassLoaderData *loader_data = class_loader_data(class_loader);
2255
2256 {
2257 MutexLocker mu1(THREAD, SystemDictionary_lock);
2258
2259 // Make a new dictionary entry.
2260 Dictionary* dictionary = loader_data->dictionary();
2261 InstanceKlass* sd_check = find_class(d_hash, name, dictionary);
2262 if (sd_check == NULL) {
2263 dictionary->add_klass(d_hash, name, k);
2264 }
2265 #ifdef ASSERT
2266 sd_check = find_class(d_hash, name, dictionary);
2267 assert (sd_check != NULL, "should have entry in dictionary");
2268 // Note: there may be a placeholder entry: for circularity testing
2269 // or for parallel defines
2270 #endif
2271 SystemDictionary_lock->notify_all();
2272 }
2273 }
2274
2275
2276 // Try to find a class name using the loader constraints. The
2277 // loader constraints might know about a class that isn't fully loaded
2278 // yet and these will be ignored.
2279 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2280 Symbol* class_name, Handle class_loader, TRAPS) {
2281
2282 // First see if it has been loaded directly.
2283 // Force the protection domain to be null. (This removes protection checks.)
2284 Handle no_protection_domain;
2285 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2286 no_protection_domain, CHECK_NULL);
2287 if (klass != NULL)
2288 return klass;
2289
2290 // Now look to see if it has been loaded elsewhere, and is subject to
2291 // a loader constraint that would require this loader to return the
2292 // klass that is already loaded.
2293 if (Signature::is_array(class_name)) {
2294 // For array classes, their Klass*s are not kept in the
2295 // constraint table. The element Klass*s are.
2296 SignatureStream ss(class_name, false);
2297 int ndims = ss.skip_array_prefix(); // skip all '['s
2298 BasicType t = ss.type();
2299 if (t != T_OBJECT) {
2300 klass = Universe::typeArrayKlassObj(t);
2301 } else {
2302 MutexLocker mu(THREAD, SystemDictionary_lock);
2303 klass = constraints()->find_constrained_klass(ss.as_symbol(), class_loader);
2304 }
2305 // If element class already loaded, allocate array klass
2306 if (klass != NULL) {
2307 klass = klass->array_klass_or_null(ndims);
2308 }
2309 } else {
2310 MutexLocker mu(THREAD, SystemDictionary_lock);
2311 // Non-array classes are easy: simply check the constraint table.
2312 klass = constraints()->find_constrained_klass(class_name, class_loader);
2313 }
2314
2315 return klass;
2316 }
2317
2318 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2319 Klass* klass_being_linked,
2320 Handle class_loader1,
2321 Handle class_loader2,
2322 Thread* THREAD) {
2323 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2324 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2325
2326 Symbol* constraint_name = NULL;
2327
2328 if (!Signature::is_array(class_name)) {
2329 constraint_name = class_name;
2330 } else {
2331 // For array classes, their Klass*s are not kept in the
2332 // constraint table. The element classes are.
2333 SignatureStream ss(class_name, false);
2334 ss.skip_array_prefix(); // skip all '['s
2335 if (!ss.has_envelope()) {
2336 return true; // primitive types always pass
2337 }
2338 constraint_name = ss.as_symbol();
2339 // Increment refcount to keep constraint_name alive after
2340 // SignatureStream is destructed. It will be decremented below
2341 // before returning.
2342 constraint_name->increment_refcount();
2343 }
2344
2345 Dictionary* dictionary1 = loader_data1->dictionary();
2346 unsigned int d_hash1 = dictionary1->compute_hash(constraint_name);
2347
2348 Dictionary* dictionary2 = loader_data2->dictionary();
2349 unsigned int d_hash2 = dictionary2->compute_hash(constraint_name);
2350
2351 {
2352 MutexLocker mu_s(THREAD, SystemDictionary_lock);
2353 InstanceKlass* klass1 = find_class(d_hash1, constraint_name, dictionary1);
2354 InstanceKlass* klass2 = find_class(d_hash2, constraint_name, dictionary2);
2355 bool result = constraints()->add_entry(constraint_name, klass1, class_loader1,
2356 klass2, class_loader2);
2357 #if INCLUDE_CDS
2358 if (Arguments::is_dumping_archive() && klass_being_linked != NULL &&
2359 !klass_being_linked->is_shared()) {
2360 SystemDictionaryShared::record_linking_constraint(constraint_name,
2361 InstanceKlass::cast(klass_being_linked),
2362 class_loader1, class_loader2, THREAD);
2363 }
2364 #endif // INCLUDE_CDS
2365 if (Signature::is_array(class_name)) {
2366 constraint_name->decrement_refcount();
2367 }
2368 return result;
2369 }
2370 }
2371
2372 // Add entry to resolution error table to record the error when the first
2373 // attempt to resolve a reference to a class has failed.
2374 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2375 Symbol* error, Symbol* message) {
2376 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2377 int index = resolution_errors()->hash_to_index(hash);
2378 {
2379 MutexLocker ml(Thread::current(), SystemDictionary_lock);
2380 resolution_errors()->add_entry(index, hash, pool, which, error, message);
2381 }
2382 }
2383
2384 // Delete a resolution error for RedefineClasses for a constant pool is going away
2385 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2386 resolution_errors()->delete_entry(pool);
2387 }
2388
2389 // Lookup resolution error table. Returns error if found, otherwise NULL.
2390 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2391 Symbol** message) {
2392 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2393 int index = resolution_errors()->hash_to_index(hash);
2394 {
2395 MutexLocker ml(Thread::current(), SystemDictionary_lock);
2396 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2397 if (entry != NULL) {
2398 *message = entry->message();
2399 return entry->error();
2400 } else {
2401 return NULL;
2402 }
2403 }
2404 }
2405
2406 // Add an entry to resolution error table to record an error in resolving or
2407 // validating a nest host. This is used to construct informative error
2408 // messages when IllegalAccessError's occur. If an entry already exists it will
2409 // be updated with the nest host error message.
2410 void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
2411 int which,
2412 const char* message) {
2413 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2414 int index = resolution_errors()->hash_to_index(hash);
2415 {
2416 MutexLocker ml(Thread::current(), SystemDictionary_lock);
2417 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2418 if (entry != NULL) {
2419 assert(entry->nest_host_error() == NULL, "Nest host error message already set!");
2420 entry->set_nest_host_error(message);
2421 } else {
2422 resolution_errors()->add_entry(index, hash, pool, which, message);
2423 }
2424 }
2425 }
2426
2427 // Lookup any nest host error
2428 const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {
2429 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2430 int index = resolution_errors()->hash_to_index(hash);
2431 {
2432 MutexLocker ml(Thread::current(), SystemDictionary_lock);
2433 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2434 if (entry != NULL) {
2435 return entry->nest_host_error();
2436 } else {
2437 return NULL;
2438 }
2439 }
2440 }
2441
2442
2443 // Signature constraints ensure that callers and callees agree about
2444 // the meaning of type names in their signatures. This routine is the
2445 // intake for constraints. It collects them from several places:
2446 //
2447 // * LinkResolver::resolve_method (if check_access is true) requires
2448 // that the resolving class (the caller) and the defining class of
2449 // the resolved method (the callee) agree on each type in the
2450 // method's signature.
2451 //
2452 // * LinkResolver::resolve_interface_method performs exactly the same
2453 // checks.
2454 //
2455 // * LinkResolver::resolve_field requires that the constant pool
2456 // attempting to link to a field agree with the field's defining
2457 // class about the type of the field signature.
2458 //
2459 // * klassVtable::initialize_vtable requires that, when a class
2460 // overrides a vtable entry allocated by a superclass, that the
2461 // overriding method (i.e., the callee) agree with the superclass
2462 // on each type in the method's signature.
2463 //
2464 // * klassItable::initialize_itable requires that, when a class fills
2465 // in its itables, for each non-abstract method installed in an
2466 // itable, the method (i.e., the callee) agree with the interface
2467 // on each type in the method's signature.
2468 //
2469 // All those methods have a boolean (check_access, checkconstraints)
2470 // which turns off the checks. This is used from specialized contexts
2471 // such as bootstrapping, dumping, and debugging.
2472 //
2473 // No direct constraint is placed between the class and its
2474 // supertypes. Constraints are only placed along linked relations
2475 // between callers and callees. When a method overrides or implements
2476 // an abstract method in a supertype (superclass or interface), the
2477 // constraints are placed as if the supertype were the caller to the
2478 // overriding method. (This works well, since callers to the
2479 // supertype have already established agreement between themselves and
2480 // the supertype.) As a result of all this, a class can disagree with
2481 // its supertype about the meaning of a type name, as long as that
2482 // class neither calls a relevant method of the supertype, nor is
2483 // called (perhaps via an override) from the supertype.
2484 //
2485 //
2486 // SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
2487 //
2488 // Make sure all class components (including arrays) in the given
2489 // signature will be resolved to the same class in both loaders.
2490 // Returns the name of the type that failed a loader constraint check, or
2491 // NULL if no constraint failed. No exception except OOME is thrown.
2492 // Arrays are not added to the loader constraint table, their elements are.
2493 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2494 Klass* klass_being_linked,
2495 Handle loader1, Handle loader2,
2496 bool is_method, TRAPS) {
2497 // Nothing to do if loaders are the same.
2498 if (loader1() == loader2()) {
2499 return NULL;
2500 }
2501
2502 for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {
2503 if (ss.is_reference()) {
2504 Symbol* sig = ss.as_symbol();
2505 // Note: In the future, if template-like types can take
2506 // arguments, we will want to recognize them and dig out class
2507 // names hiding inside the argument lists.
2508 if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2, THREAD)) {
2509 return sig;
2510 }
2511 }
2512 }
2513 return NULL;
2514 }
2515
2516 Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2517 Symbol* signature,
2518 TRAPS) {
2519 methodHandle empty;
2520 assert(MethodHandles::is_signature_polymorphic(iid) &&
2521 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2522 iid != vmIntrinsics::_invokeGeneric,
2523 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2524
2525 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2526 int index = invoke_method_table()->hash_to_index(hash);
2527 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2528 methodHandle m;
2529 if (spe == NULL || spe->method() == NULL) {
2530 spe = NULL;
2531 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2532 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_NULL);
2533 if (!Arguments::is_interpreter_only()) {
2534 // Generate a compiled form of the MH intrinsic.
2535 AdapterHandlerLibrary::create_native_wrapper(m);
2536 // Check if have the compiled code.
2537 if (!m->has_compiled_code()) {
2538 THROW_MSG_NULL(vmSymbols::java_lang_VirtualMachineError(),
2539 "Out of space in CodeCache for method handle intrinsic");
2540 }
2541 }
2542 // Now grab the lock. We might have to throw away the new method,
2543 // if a racing thread has managed to install one at the same time.
2544 {
2545 MutexLocker ml(THREAD, SystemDictionary_lock);
2546 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2547 if (spe == NULL)
2548 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2549 if (spe->method() == NULL)
2550 spe->set_method(m());
2551 }
2552 }
2553
2554 assert(spe != NULL && spe->method() != NULL, "");
2555 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2556 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2557 "MH intrinsic invariant");
2558 return spe->method();
2559 }
2560
2561 // Helper for unpacking the return value from linkMethod and linkCallSite.
2562 static Method* unpack_method_and_appendix(Handle mname,
2563 Klass* accessing_klass,
2564 objArrayHandle appendix_box,
2565 Handle* appendix_result,
2566 TRAPS) {
2567 if (mname.not_null()) {
2568 Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2569 if (m != NULL) {
2570 oop appendix = appendix_box->obj_at(0);
2571 LogTarget(Info, methodhandles) lt;
2572 if (lt.develop_is_enabled()) {
2573 ResourceMark rm(THREAD);
2574 LogStream ls(lt);
2575 ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2576 m->print_on(&ls);
2577 if (appendix != NULL) { ls.print("appendix = "); appendix->print_on(&ls); }
2578 ls.cr();
2579 }
2580
2581 (*appendix_result) = Handle(THREAD, appendix);
2582 // the target is stored in the cpCache and if a reference to this
2583 // MemberName is dropped we need a way to make sure the
2584 // class_loader containing this method is kept alive.
2585 methodHandle mh(THREAD, m); // record_dependency can safepoint.
2586 ClassLoaderData* this_key = accessing_klass->class_loader_data();
2587 this_key->record_dependency(m->method_holder());
2588 return mh();
2589 }
2590 }
2591 THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2592 }
2593
2594 Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2595 Symbol* name,
2596 Symbol* signature,
2597 Klass* accessing_klass,
2598 Handle *appendix_result,
2599 TRAPS) {
2600 assert(THREAD->can_call_java() ,"");
2601 Handle method_type =
2602 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2603
2604 int ref_kind = JVM_REF_invokeVirtual;
2605 oop name_oop = StringTable::intern(name, CHECK_NULL);
2606 Handle name_str (THREAD, name_oop);
2607 objArrayHandle appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK_NULL);
2608 assert(appendix_box->obj_at(0) == NULL, "");
2609
2610 // This should not happen. JDK code should take care of that.
2611 if (accessing_klass == NULL || method_type.is_null()) {
2612 THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2613 }
2614
2615 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2616 JavaCallArguments args;
2617 args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2618 args.push_int(ref_kind);
2619 args.push_oop(Handle(THREAD, klass->java_mirror()));
2620 args.push_oop(name_str);
2621 args.push_oop(method_type);
2622 args.push_oop(appendix_box);
2623 JavaValue result(T_OBJECT);
2624 JavaCalls::call_static(&result,
2625 SystemDictionary::MethodHandleNatives_klass(),
2626 vmSymbols::linkMethod_name(),
2627 vmSymbols::linkMethod_signature(),
2628 &args, CHECK_NULL);
2629 Handle mname(THREAD, (oop) result.get_jobject());
2630 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2631 }
2632
2633 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2634 // We must ensure that all class loaders everywhere will reach this class, for any client.
2635 // This is a safe bet for public classes in java.lang, such as Object and String.
2636 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2637 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2638 static bool is_always_visible_class(oop mirror) {
2639 Klass* klass = java_lang_Class::as_Klass(mirror);
2640 if (klass->is_objArray_klass()) {
2641 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2642 }
2643 if (klass->is_typeArray_klass()) {
2644 return true; // primitive array
2645 }
2646 assert(klass->is_instance_klass(), "%s", klass->external_name());
2647 return klass->is_public() &&
2648 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang
2649 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke
2650 }
2651
2652 // Find or construct the Java mirror (java.lang.Class instance) for
2653 // the given field type signature, as interpreted relative to the
2654 // given class loader. Handles primitives, void, references, arrays,
2655 // and all other reflectable types, except method types.
2656 // N.B. Code in reflection should use this entry point.
2657 Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2658 Klass* accessing_klass,
2659 Handle class_loader,
2660 Handle protection_domain,
2661 SignatureStream::FailureMode failure_mode,
2662 TRAPS) {
2663 assert(accessing_klass == NULL || (class_loader.is_null() && protection_domain.is_null()),
2664 "one or the other, or perhaps neither");
2665
2666 // What we have here must be a valid field descriptor,
2667 // and all valid field descriptors are supported.
2668 // Produce the same java.lang.Class that reflection reports.
2669 if (accessing_klass != NULL) {
2670 class_loader = Handle(THREAD, accessing_klass->class_loader());
2671 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2672 }
2673 ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2674 oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2675 if (mirror_oop == NULL) {
2676 return Handle(); // report failure this way
2677 }
2678 Handle mirror(THREAD, mirror_oop);
2679
2680 if (accessing_klass != NULL) {
2681 // Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2682 Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2683 if (sel_klass != NULL) {
2684 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2685 }
2686 }
2687 return mirror;
2688 }
2689
2690
2691 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2692 // signature, as interpreted relative to the given class loader.
2693 // Because of class loader constraints, all method handle usage must be
2694 // consistent with this loader.
2695 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2696 Klass* accessing_klass,
2697 TRAPS) {
2698 Handle empty;
2699 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2700 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2701 int index = invoke_method_table()->hash_to_index(hash);
2702 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2703 if (spe != NULL && spe->method_type() != NULL) {
2704 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2705 return Handle(THREAD, spe->method_type());
2706 } else if (!THREAD->can_call_java()) {
2707 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2708 return Handle(); // do not attempt from within compiler, unless it was cached
2709 }
2710
2711 Handle class_loader, protection_domain;
2712 if (accessing_klass != NULL) {
2713 class_loader = Handle(THREAD, accessing_klass->class_loader());
2714 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2715 }
2716 bool can_be_cached = true;
2717 int npts = ArgumentCount(signature).size();
2718 objArrayHandle pts = oopFactory::new_objArray_handle(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2719 int arg = 0;
2720 Handle rt; // the return type from the signature
2721 ResourceMark rm(THREAD);
2722 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2723 oop mirror = NULL;
2724 if (can_be_cached) {
2725 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2726 mirror = ss.as_java_mirror(Handle(), Handle(),
2727 SignatureStream::ReturnNull, CHECK_(empty));
2728 if (mirror == NULL || (ss.is_reference() && !is_always_visible_class(mirror))) {
2729 // Fall back to accessing_klass context.
2730 can_be_cached = false;
2731 }
2732 }
2733 if (!can_be_cached) {
2734 // Resolve, throwing a real error if it doesn't work.
2735 mirror = ss.as_java_mirror(class_loader, protection_domain,
2736 SignatureStream::NCDFError, CHECK_(empty));
2737 }
2738 assert(mirror != NULL, "%s", ss.as_symbol()->as_C_string());
2739 if (ss.at_return_type())
2740 rt = Handle(THREAD, mirror);
2741 else
2742 pts->obj_at_put(arg++, mirror);
2743
2744 // Check accessibility.
2745 if (!java_lang_Class::is_primitive(mirror) && accessing_klass != NULL) {
2746 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2747 mirror = NULL; // safety
2748 // Emulate ConstantPool::verify_constant_pool_resolve.
2749 LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2750 }
2751 }
2752 assert(arg == npts, "");
2753
2754 // call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2755 JavaCallArguments args(Handle(THREAD, rt()));
2756 args.push_oop(pts);
2757 JavaValue result(T_OBJECT);
2758 JavaCalls::call_static(&result,
2759 SystemDictionary::MethodHandleNatives_klass(),
2760 vmSymbols::findMethodHandleType_name(),
2761 vmSymbols::findMethodHandleType_signature(),
2762 &args, CHECK_(empty));
2763 Handle method_type(THREAD, (oop) result.get_jobject());
2764
2765 if (can_be_cached) {
2766 // We can cache this MethodType inside the JVM.
2767 MutexLocker ml(THREAD, SystemDictionary_lock);
2768 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2769 if (spe == NULL)
2770 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2771 if (spe->method_type() == NULL) {
2772 spe->set_method_type(method_type());
2773 }
2774 }
2775
2776 // report back to the caller with the MethodType
2777 return method_type;
2778 }
2779
2780 Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2781 Klass* accessing_klass,
2782 TRAPS) {
2783 Handle empty;
2784 ResourceMark rm(THREAD);
2785 SignatureStream ss(signature, /*is_method=*/ false);
2786 if (!ss.is_done()) {
2787 Handle class_loader, protection_domain;
2788 if (accessing_klass != NULL) {
2789 class_loader = Handle(THREAD, accessing_klass->class_loader());
2790 protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2791 }
2792 oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2793 ss.next();
2794 if (ss.is_done()) {
2795 return Handle(THREAD, mirror);
2796 }
2797 }
2798 return empty;
2799 }
2800
2801 // Ask Java code to find or construct a method handle constant.
2802 Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2803 int ref_kind, //e.g., JVM_REF_invokeVirtual
2804 Klass* callee,
2805 Symbol* name,
2806 Symbol* signature,
2807 TRAPS) {
2808 Handle empty;
2809 if (caller == NULL) {
2810 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2811 }
2812 Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2813 Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2814
2815 // Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2816 Handle mname = MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2817 java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2818 java_lang_invoke_MemberName::set_name (mname(), name_str());
2819 java_lang_invoke_MemberName::set_type (mname(), signature_str());
2820 java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2821
2822 if (ref_kind == JVM_REF_invokeVirtual &&
2823 MethodHandles::is_signature_polymorphic_public_name(callee, name)) {
2824 // Skip resolution for public signature polymorphic methods such as
2825 // j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2826 // They require appendix argument which MemberName resolution doesn't handle.
2827 // There's special logic on JDK side to handle them
2828 // (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2829 } else {
2830 MethodHandles::resolve_MemberName(mname, caller, /*speculative_resolve*/false, CHECK_(empty));
2831 }
2832
2833 // After method/field resolution succeeded, it's safe to resolve MH signature as well.
2834 Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2835
2836 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2837 JavaCallArguments args;
2838 args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2839 args.push_int(ref_kind);
2840 args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2841 args.push_oop(name_str);
2842 args.push_oop(type);
2843 JavaValue result(T_OBJECT);
2844 JavaCalls::call_static(&result,
2845 SystemDictionary::MethodHandleNatives_klass(),
2846 vmSymbols::linkMethodHandleConstant_name(),
2847 vmSymbols::linkMethodHandleConstant_signature(),
2848 &args, CHECK_(empty));
2849 return Handle(THREAD, (oop) result.get_jobject());
2850 }
2851
2852 // Ask Java to run a bootstrap method, in order to create a dynamic call site
2853 // while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2854 // with linkage results being stored back into the bootstrap specifier.
2855 void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {
2856 // Resolve the bootstrap specifier, its name, type, and static arguments
2857 bootstrap_specifier.resolve_bsm(CHECK);
2858
2859 // This should not happen. JDK code should take care of that.
2860 if (bootstrap_specifier.caller() == NULL || bootstrap_specifier.type_arg().is_null()) {
2861 THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2862 }
2863
2864 bool is_indy = bootstrap_specifier.is_method_call();
2865 objArrayHandle appendix_box;
2866 if (is_indy) {
2867 // Some method calls may require an appendix argument. Arrange to receive it.
2868 appendix_box = oopFactory::new_objArray_handle(SystemDictionary::Object_klass(), 1, CHECK);
2869 assert(appendix_box->obj_at(0) == NULL, "");
2870 }
2871
2872 // call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, condy_index, bsm, type, info)
2873 // indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, indy_index, bsm, name, mtype, info, &appendix)
2874 JavaCallArguments args;
2875 args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2876 args.push_int(bootstrap_specifier.bss_index());
2877 args.push_oop(bootstrap_specifier.bsm());
2878 args.push_oop(bootstrap_specifier.name_arg());
2879 args.push_oop(bootstrap_specifier.type_arg());
2880 args.push_oop(bootstrap_specifier.arg_values());
2881 if (is_indy) {
2882 args.push_oop(appendix_box);
2883 }
2884 JavaValue result(T_OBJECT);
2885 JavaCalls::call_static(&result,
2886 SystemDictionary::MethodHandleNatives_klass(),
2887 is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2888 is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2889 &args, CHECK);
2890
2891 Handle value(THREAD, (oop) result.get_jobject());
2892 if (is_indy) {
2893 Handle appendix;
2894 Method* method = unpack_method_and_appendix(value,
2895 bootstrap_specifier.caller(),
2896 appendix_box,
2897 &appendix, CHECK);
2898 methodHandle mh(THREAD, method);
2899 bootstrap_specifier.set_resolved_method(mh, appendix);
2900 } else {
2901 bootstrap_specifier.set_resolved_value(value);
2902 }
2903
2904 // sanity check
2905 assert(bootstrap_specifier.is_resolved() ||
2906 (bootstrap_specifier.is_method_call() &&
2907 bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2908 }
2909
2910 // Protection domain cache table handling
2911
2912 ProtectionDomainCacheEntry* SystemDictionary::cache_get(Handle protection_domain) {
2913 return _pd_cache_table->get(protection_domain);
2914 }
2915
2916 // ----------------------------------------------------------------------------
2917
2918 void SystemDictionary::print_on(outputStream *st) {
2919 CDS_ONLY(SystemDictionaryShared::print_on(st));
2920 GCMutexLocker mu(SystemDictionary_lock);
2921
2922 ClassLoaderDataGraph::print_dictionary(st);
2923
2924 // Placeholders
2925 placeholders()->print_on(st);
2926 st->cr();
2927
2928 // loader constraints - print under SD_lock
2929 constraints()->print_on(st);
2930 st->cr();
2931
2932 _pd_cache_table->print_on(st);
2933 st->cr();
2934 }
2935
2936 void SystemDictionary::print() { print_on(tty); }
2937
2938 void SystemDictionary::verify() {
2939 guarantee(constraints() != NULL,
2940 "Verify of loader constraints failed");
2941 guarantee(placeholders()->number_of_entries() >= 0,
2942 "Verify of placeholders failed");
2943
2944 GCMutexLocker mu(SystemDictionary_lock);
2945
2946 // Verify dictionary
2947 ClassLoaderDataGraph::verify_dictionary();
2948
2949 placeholders()->verify();
2950
2951 // Verify constraint table
2952 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2953 constraints()->verify(placeholders());
2954
2955 _pd_cache_table->verify();
2956 }
2957
2958 void SystemDictionary::dump(outputStream *st, bool verbose) {
2959 assert_locked_or_safepoint(SystemDictionary_lock);
2960 if (verbose) {
2961 print_on(st);
2962 } else {
2963 CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2964 ClassLoaderDataGraph::print_table_statistics(st);
2965 placeholders()->print_table_statistics(st, "Placeholder Table");
2966 constraints()->print_table_statistics(st, "LoaderConstraints Table");
2967 pd_cache_table()->print_table_statistics(st, "ProtectionDomainCache Table");
2968 }
2969 }
2970
2971 TableStatistics SystemDictionary::placeholders_statistics() {
2972 MutexLocker ml(SystemDictionary_lock);
2973 return placeholders()->statistics_calculate();
2974 }
2975
2976 TableStatistics SystemDictionary::loader_constraints_statistics() {
2977 MutexLocker ml(SystemDictionary_lock);
2978 return constraints()->statistics_calculate();
2979 }
2980
2981 TableStatistics SystemDictionary::protection_domain_cache_statistics() {
2982 MutexLocker ml(SystemDictionary_lock);
2983 return pd_cache_table()->statistics_calculate();
2984 }
2985
2986 // Utility for dumping dictionaries.
2987 SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2988 DCmdWithParser(output, heap),
2989 _verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",
2990 "BOOLEAN", false, "false") {
2991 _dcmdparser.add_dcmd_option(&_verbose);
2992 }
2993
2994 void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {
2995 VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2996 _verbose.value());
2997 VMThread::execute(&dumper);
2998 }
2999
3000 int SystemDictionaryDCmd::num_arguments() {
3001 ResourceMark rm;
3002 SystemDictionaryDCmd* dcmd = new SystemDictionaryDCmd(NULL, false);
3003 if (dcmd != NULL) {
3004 DCmdMark mark(dcmd);
3005 return dcmd->_dcmdparser.num_arguments();
3006 } else {
3007 return 0;
3008 }
3009 }