1 /*
2 * Copyright (c) 1997, 2015, 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 "classfile/classLoaderData.inline.hpp"
27 #include "classfile/dictionary.hpp"
28 #include "classfile/javaClasses.inline.hpp"
29 #include "classfile/loaderConstraints.hpp"
30 #include "classfile/placeholders.hpp"
31 #include "classfile/resolutionErrors.hpp"
32 #include "classfile/stringTable.hpp"
33 #include "classfile/systemDictionary.hpp"
34 #include "classfile/vmSymbols.hpp"
35 #include "code/codeCache.hpp"
36 #include "compiler/compileBroker.hpp"
37 #include "gc/shared/gcLocker.hpp"
38 #include "interpreter/bytecodeStream.hpp"
39 #include "interpreter/interpreter.hpp"
40 #include "logging/log.hpp"
41 #include "memory/filemap.hpp"
42 #include "memory/oopFactory.hpp"
43 #include "oops/instanceKlass.hpp"
44 #include "oops/instanceRefKlass.hpp"
45 #include "oops/klass.inline.hpp"
46 #include "oops/methodData.hpp"
47 #include "oops/objArrayKlass.hpp"
48 #include "oops/objArrayOop.inline.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "oops/typeArrayKlass.hpp"
51 #include "prims/jvmtiEnvBase.hpp"
52 #include "prims/methodHandles.hpp"
53 #include "runtime/arguments.hpp"
54 #include "runtime/biasedLocking.hpp"
55 #include "runtime/fieldType.hpp"
56 #include "runtime/handles.inline.hpp"
57 #include "runtime/java.hpp"
58 #include "runtime/javaCalls.hpp"
59 #include "runtime/mutexLocker.hpp"
60 #include "runtime/orderAccess.inline.hpp"
61 #include "runtime/signature.hpp"
62 #include "services/classLoadingService.hpp"
63 #include "services/threadService.hpp"
64 #include "utilities/macros.hpp"
65 #include "utilities/ticks.hpp"
66 #if INCLUDE_CDS
67 #include "classfile/sharedClassUtil.hpp"
68 #include "classfile/systemDictionaryShared.hpp"
69 #endif
70 #if INCLUDE_JVMCI
71 #include "jvmci/jvmciRuntime.hpp"
72 #endif
73 #if INCLUDE_TRACE
74 #include "trace/tracing.hpp"
75 #endif
76
77 Dictionary* SystemDictionary::_dictionary = NULL;
78 PlaceholderTable* SystemDictionary::_placeholders = NULL;
79 Dictionary* SystemDictionary::_shared_dictionary = NULL;
80 LoaderConstraintTable* SystemDictionary::_loader_constraints = NULL;
81 ResolutionErrorTable* SystemDictionary::_resolution_errors = NULL;
82 SymbolPropertyTable* SystemDictionary::_invoke_method_table = NULL;
83
84
85 int SystemDictionary::_number_of_modifications = 0;
86 int SystemDictionary::_sdgeneration = 0;
87 const int SystemDictionary::_primelist[_prime_array_size] = {1009,2017,4049,5051,10103,
88 20201,40423,99991};
89
90 oop SystemDictionary::_system_loader_lock_obj = NULL;
91
92 InstanceKlass* SystemDictionary::_well_known_klasses[SystemDictionary::WKID_LIMIT]
93 = { NULL /*, NULL...*/ };
94
95 InstanceKlass* SystemDictionary::_box_klasses[T_VOID+1] = { NULL /*, NULL...*/ };
96
97 oop SystemDictionary::_java_system_loader = NULL;
98
99 bool SystemDictionary::_has_loadClassInternal = false;
100 bool SystemDictionary::_has_checkPackageAccess = false;
101
102 // lazily initialized klass variables
103 InstanceKlass* volatile SystemDictionary::_abstract_ownable_synchronizer_klass = NULL;
104
105
106 // ----------------------------------------------------------------------------
107 // Java-level SystemLoader
108
109 oop SystemDictionary::java_system_loader() {
110 return _java_system_loader;
111 }
112
113 void SystemDictionary::compute_java_system_loader(TRAPS) {
114 KlassHandle system_klass(THREAD, WK_KLASS(ClassLoader_klass));
115 JavaValue result(T_OBJECT);
116 JavaCalls::call_static(&result,
117 KlassHandle(THREAD, WK_KLASS(ClassLoader_klass)),
118 vmSymbols::getSystemClassLoader_name(),
119 vmSymbols::void_classloader_signature(),
120 CHECK);
121
122 _java_system_loader = (oop)result.get_jobject();
123
124 CDS_ONLY(SystemDictionaryShared::initialize(CHECK);)
125 }
126
127
128 ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, TRAPS) {
129 if (class_loader() == NULL) return ClassLoaderData::the_null_class_loader_data();
130 return ClassLoaderDataGraph::find_or_create(class_loader, THREAD);
131 }
132
133 // ----------------------------------------------------------------------------
134 // debugging
135
136 #ifdef ASSERT
137
138 // return true if class_name contains no '.' (internal format is '/')
139 bool SystemDictionary::is_internal_format(Symbol* class_name) {
140 if (class_name != NULL) {
141 ResourceMark rm;
142 char* name = class_name->as_C_string();
143 return strchr(name, '.') == NULL;
144 } else {
145 return true;
146 }
147 }
148
149 #endif
150
151 // ----------------------------------------------------------------------------
152 // Parallel class loading check
153
154 bool SystemDictionary::is_parallelCapable(Handle class_loader) {
155 if (UnsyncloadClass || class_loader.is_null()) return true;
156 if (AlwaysLockClassLoader) return false;
157 return java_lang_ClassLoader::parallelCapable(class_loader());
158 }
159 // ----------------------------------------------------------------------------
160 // ParallelDefineClass flag does not apply to bootclass loader
161 bool SystemDictionary::is_parallelDefine(Handle class_loader) {
162 if (class_loader.is_null()) return false;
163 if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {
164 return true;
165 }
166 return false;
167 }
168
169 /**
170 * Returns true if the passed class loader is the extension class loader.
171 */
172 bool SystemDictionary::is_ext_class_loader(Handle class_loader) {
173 if (class_loader.is_null()) {
174 return false;
175 }
176 return (class_loader->klass()->name() == vmSymbols::sun_misc_Launcher_ExtClassLoader());
177 }
178
179 // ----------------------------------------------------------------------------
180 // Resolving of classes
181
182 // Forwards to resolve_or_null
183
184 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain, bool throw_error, TRAPS) {
185 Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
186 if (HAS_PENDING_EXCEPTION || klass == NULL) {
187 KlassHandle k_h(THREAD, klass);
188 // can return a null klass
189 klass = handle_resolution_exception(class_name, throw_error, k_h, THREAD);
190 }
191 return klass;
192 }
193
194 Klass* SystemDictionary::handle_resolution_exception(Symbol* class_name,
195 bool throw_error,
196 KlassHandle klass_h, TRAPS) {
197 if (HAS_PENDING_EXCEPTION) {
198 // If we have a pending exception we forward it to the caller, unless throw_error is true,
199 // in which case we have to check whether the pending exception is a ClassNotFoundException,
200 // and if so convert it to a NoClassDefFoundError
201 // And chain the original ClassNotFoundException
202 if (throw_error && PENDING_EXCEPTION->is_a(SystemDictionary::ClassNotFoundException_klass())) {
203 ResourceMark rm(THREAD);
204 assert(klass_h() == NULL, "Should not have result with exception pending");
205 Handle e(THREAD, PENDING_EXCEPTION);
206 CLEAR_PENDING_EXCEPTION;
207 THROW_MSG_CAUSE_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
208 } else {
209 return NULL;
210 }
211 }
212 // Class not found, throw appropriate error or exception depending on value of throw_error
213 if (klass_h() == NULL) {
214 ResourceMark rm(THREAD);
215 if (throw_error) {
216 THROW_MSG_NULL(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
217 } else {
218 THROW_MSG_NULL(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
219 }
220 }
221 return (Klass*)klass_h();
222 }
223
224
225 Klass* SystemDictionary::resolve_or_fail(Symbol* class_name,
226 bool throw_error, TRAPS)
227 {
228 return resolve_or_fail(class_name, Handle(), Handle(), throw_error, THREAD);
229 }
230
231
232 // Forwards to resolve_instance_class_or_null
233
234 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {
235 assert(THREAD->can_call_java(),
236 "can not load classes with compiler thread: class=%s, classloader=%s",
237 class_name->as_C_string(),
238 class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
239 if (FieldType::is_array(class_name)) {
240 return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
241 } else if (FieldType::is_obj(class_name)) {
242 ResourceMark rm(THREAD);
243 // Ignore wrapping L and ;.
244 TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
245 class_name->utf8_length() - 2, CHECK_NULL);
246 return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
247 } else {
248 return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
249 }
250 }
251
252 Klass* SystemDictionary::resolve_or_null(Symbol* class_name, TRAPS) {
253 return resolve_or_null(class_name, Handle(), Handle(), THREAD);
254 }
255
256 // Forwards to resolve_instance_class_or_null
257
258 Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
259 Handle class_loader,
260 Handle protection_domain,
261 TRAPS) {
262 assert(FieldType::is_array(class_name), "must be array");
263 Klass* k = NULL;
264 FieldArrayInfo fd;
265 // dimension and object_key in FieldArrayInfo are assigned as a side-effect
266 // of this call
267 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_NULL);
268 if (t == T_OBJECT) {
269 // naked oop "k" is OK here -- we assign back into it
270 k = SystemDictionary::resolve_instance_class_or_null(fd.object_key(),
271 class_loader,
272 protection_domain,
273 CHECK_NULL);
274 if (k != NULL) {
275 k = k->array_klass(fd.dimension(), CHECK_NULL);
276 }
277 } else {
278 k = Universe::typeArrayKlassObj(t);
279 k = TypeArrayKlass::cast(k)->array_klass(fd.dimension(), CHECK_NULL);
280 }
281 return k;
282 }
283
284
285 // Must be called for any super-class or super-interface resolution
286 // during class definition to allow class circularity checking
287 // super-interface callers:
288 // parse_interfaces - for defineClass & jvmtiRedefineClasses
289 // super-class callers:
290 // ClassFileParser - for defineClass & jvmtiRedefineClasses
291 // load_shared_class - while loading a class from shared archive
292 // resolve_instance_class_or_null:
293 // via: handle_parallel_super_load
294 // when resolving a class that has an existing placeholder with
295 // a saved superclass [i.e. a defineClass is currently in progress]
296 // if another thread is trying to resolve the class, it must do
297 // super-class checks on its own thread to catch class circularity
298 // This last call is critical in class circularity checking for cases
299 // where classloading is delegated to different threads and the
300 // classloader lock is released.
301 // Take the case: Base->Super->Base
302 // 1. If thread T1 tries to do a defineClass of class Base
303 // resolve_super_or_fail creates placeholder: T1, Base (super Super)
304 // 2. resolve_instance_class_or_null does not find SD or placeholder for Super
305 // so it tries to load Super
306 // 3. If we load the class internally, or user classloader uses same thread
307 // loadClassFromxxx or defineClass via parseClassFile Super ...
308 // 3.1 resolve_super_or_fail creates placeholder: T1, Super (super Base)
309 // 3.3 resolve_instance_class_or_null Base, finds placeholder for Base
310 // 3.4 calls resolve_super_or_fail Base
311 // 3.5 finds T1,Base -> throws class circularity
312 //OR 4. If T2 tries to resolve Super via defineClass Super ...
313 // 4.1 resolve_super_or_fail creates placeholder: T2, Super (super Base)
314 // 4.2 resolve_instance_class_or_null Base, finds placeholder for Base (super Super)
315 // 4.3 calls resolve_super_or_fail Super in parallel on own thread T2
316 // 4.4 finds T2, Super -> throws class circularity
317 // Must be called, even if superclass is null, since this is
318 // where the placeholder entry is created which claims this
319 // thread is loading this class/classloader.
320 Klass* SystemDictionary::resolve_super_or_fail(Symbol* child_name,
321 Symbol* class_name,
322 Handle class_loader,
323 Handle protection_domain,
324 bool is_superclass,
325 TRAPS) {
326 // Double-check, if child class is already loaded, just return super-class,interface
327 // Don't add a placedholder if already loaded, i.e. already in system dictionary
328 // Make sure there's a placeholder for the *child* before resolving.
329 // Used as a claim that this thread is currently loading superclass/classloader
330 // Used here for ClassCircularity checks and also for heap verification
331 // (every InstanceKlass in the heap needs to be in the system dictionary
332 // or have a placeholder).
333 // Must check ClassCircularity before checking if super class is already loaded
334 //
335 // We might not already have a placeholder if this child_name was
336 // first seen via resolve_from_stream (jni_DefineClass or JVM_DefineClass);
337 // the name of the class might not be known until the stream is actually
338 // parsed.
339 // Bugs 4643874, 4715493
340 // compute_hash can have a safepoint
341
342 ClassLoaderData* loader_data = class_loader_data(class_loader);
343 unsigned int d_hash = dictionary()->compute_hash(child_name, loader_data);
344 int d_index = dictionary()->hash_to_index(d_hash);
345 unsigned int p_hash = placeholders()->compute_hash(child_name, loader_data);
346 int p_index = placeholders()->hash_to_index(p_hash);
347 // can't throw error holding a lock
348 bool child_already_loaded = false;
349 bool throw_circularity_error = false;
350 {
351 MutexLocker mu(SystemDictionary_lock, THREAD);
352 Klass* childk = find_class(d_index, d_hash, child_name, loader_data);
353 Klass* quicksuperk;
354 // to support // loading: if child done loading, just return superclass
355 // if class_name, & class_loader don't match:
356 // if initial define, SD update will give LinkageError
357 // if redefine: compare_class_versions will give HIERARCHY_CHANGED
358 // so we don't throw an exception here.
359 // see: nsk redefclass014 & java.lang.instrument Instrument032
360 if ((childk != NULL ) && (is_superclass) &&
361 ((quicksuperk = childk->super()) != NULL) &&
362
363 ((quicksuperk->name() == class_name) &&
364 (quicksuperk->class_loader() == class_loader()))) {
365 return quicksuperk;
366 } else {
367 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, child_name, loader_data);
368 if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {
369 throw_circularity_error = true;
370 }
371 }
372 if (!throw_circularity_error) {
373 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, class_name, THREAD);
374 }
375 }
376 if (throw_circularity_error) {
377 ResourceMark rm(THREAD);
378 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), child_name->as_C_string());
379 }
380
381 // java.lang.Object should have been found above
382 assert(class_name != NULL, "null super class for resolving");
383 // Resolve the super class or interface, check results on return
384 Klass* superk = SystemDictionary::resolve_or_null(class_name,
385 class_loader,
386 protection_domain,
387 THREAD);
388
389 KlassHandle superk_h(THREAD, superk);
390
391 // Clean up of placeholders moved so that each classloadAction registrar self-cleans up
392 // It is no longer necessary to keep the placeholder table alive until update_dictionary
393 // or error. GC used to walk the placeholder table as strong roots.
394 // The instanceKlass is kept alive because the class loader is on the stack,
395 // which keeps the loader_data alive, as well as all instanceKlasses in
396 // the loader_data. parseClassFile adds the instanceKlass to loader_data.
397 {
398 MutexLocker mu(SystemDictionary_lock, THREAD);
399 placeholders()->find_and_remove(p_index, p_hash, child_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
400 SystemDictionary_lock->notify_all();
401 }
402 if (HAS_PENDING_EXCEPTION || superk_h() == NULL) {
403 // can null superk
404 superk_h = KlassHandle(THREAD, handle_resolution_exception(class_name, true, superk_h, THREAD));
405 }
406
407 return superk_h();
408 }
409
410 void SystemDictionary::validate_protection_domain(instanceKlassHandle klass,
411 Handle class_loader,
412 Handle protection_domain,
413 TRAPS) {
414 if(!has_checkPackageAccess()) return;
415
416 // Now we have to call back to java to check if the initating class has access
417 JavaValue result(T_VOID);
418 if (TraceProtectionDomainVerification) {
419 // Print out trace information
420 tty->print_cr("Checking package access");
421 tty->print(" - class loader: "); class_loader()->print_value_on(tty); tty->cr();
422 tty->print(" - protection domain: "); protection_domain()->print_value_on(tty); tty->cr();
423 tty->print(" - loading: "); klass()->print_value_on(tty); tty->cr();
424 }
425
426 KlassHandle system_loader(THREAD, SystemDictionary::ClassLoader_klass());
427 JavaCalls::call_special(&result,
428 class_loader,
429 system_loader,
430 vmSymbols::checkPackageAccess_name(),
431 vmSymbols::class_protectiondomain_signature(),
432 Handle(THREAD, klass->java_mirror()),
433 protection_domain,
434 THREAD);
435
436 if (TraceProtectionDomainVerification) {
437 if (HAS_PENDING_EXCEPTION) {
438 tty->print_cr(" -> DENIED !!!!!!!!!!!!!!!!!!!!!");
439 } else {
440 tty->print_cr(" -> granted");
441 }
442 tty->cr();
443 }
444
445 if (HAS_PENDING_EXCEPTION) return;
446
447 // If no exception has been thrown, we have validated the protection domain
448 // Insert the protection domain of the initiating class into the set.
449 {
450 // We recalculate the entry here -- we've called out to java since
451 // the last time it was calculated.
452 ClassLoaderData* loader_data = class_loader_data(class_loader);
453
454 Symbol* kn = klass->name();
455 unsigned int d_hash = dictionary()->compute_hash(kn, loader_data);
456 int d_index = dictionary()->hash_to_index(d_hash);
457
458 MutexLocker mu(SystemDictionary_lock, THREAD);
459 {
460 // Note that we have an entry, and entries can be deleted only during GC,
461 // so we cannot allow GC to occur while we're holding this entry.
462
463 // We're using a No_Safepoint_Verifier to catch any place where we
464 // might potentially do a GC at all.
465 // Dictionary::do_unloading() asserts that classes in SD are only
466 // unloaded at a safepoint. Anonymous classes are not in SD.
467 No_Safepoint_Verifier nosafepoint;
468 dictionary()->add_protection_domain(d_index, d_hash, klass, loader_data,
469 protection_domain, THREAD);
470 }
471 }
472 }
473
474 // We only get here if this thread finds that another thread
475 // has already claimed the placeholder token for the current operation,
476 // but that other thread either never owned or gave up the
477 // object lock
478 // Waits on SystemDictionary_lock to indicate placeholder table updated
479 // On return, caller must recheck placeholder table state
480 //
481 // We only get here if
482 // 1) custom classLoader, i.e. not bootstrap classloader
483 // 2) UnsyncloadClass not set
484 // 3) custom classLoader has broken the class loader objectLock
485 // so another thread got here in parallel
486 //
487 // lockObject must be held.
488 // Complicated dance due to lock ordering:
489 // Must first release the classloader object lock to
490 // allow initial definer to complete the class definition
491 // and to avoid deadlock
492 // Reclaim classloader lock object with same original recursion count
493 // Must release SystemDictionary_lock after notify, since
494 // class loader lock must be claimed before SystemDictionary_lock
495 // to prevent deadlocks
496 //
497 // The notify allows applications that did an untimed wait() on
498 // the classloader object lock to not hang.
499 void SystemDictionary::double_lock_wait(Handle lockObject, TRAPS) {
500 assert_lock_strong(SystemDictionary_lock);
501
502 bool calledholdinglock
503 = ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD, lockObject);
504 assert(calledholdinglock,"must hold lock for notify");
505 assert((!(lockObject() == _system_loader_lock_obj) && !is_parallelCapable(lockObject)), "unexpected double_lock_wait");
506 ObjectSynchronizer::notifyall(lockObject, THREAD);
507 intptr_t recursions = ObjectSynchronizer::complete_exit(lockObject, THREAD);
508 SystemDictionary_lock->wait();
509 SystemDictionary_lock->unlock();
510 ObjectSynchronizer::reenter(lockObject, recursions, THREAD);
511 SystemDictionary_lock->lock();
512 }
513
514 // If the class in is in the placeholder table, class loading is in progress
515 // For cases where the application changes threads to load classes, it
516 // is critical to ClassCircularity detection that we try loading
517 // the superclass on the same thread internally, so we do parallel
518 // super class loading here.
519 // This also is critical in cases where the original thread gets stalled
520 // even in non-circularity situations.
521 // Note: must call resolve_super_or_fail even if null super -
522 // to force placeholder entry creation for this class for circularity detection
523 // Caller must check for pending exception
524 // Returns non-null Klass* if other thread has completed load
525 // and we are done,
526 // If return null Klass* and no pending exception, the caller must load the class
527 instanceKlassHandle SystemDictionary::handle_parallel_super_load(
528 Symbol* name, Symbol* superclassname, Handle class_loader,
529 Handle protection_domain, Handle lockObject, TRAPS) {
530
531 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
532 ClassLoaderData* loader_data = class_loader_data(class_loader);
533 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
534 int d_index = dictionary()->hash_to_index(d_hash);
535 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
536 int p_index = placeholders()->hash_to_index(p_hash);
537
538 // superk is not used, resolve_super called for circularity check only
539 // This code is reached in two situations. One if this thread
540 // is loading the same class twice (e.g. ClassCircularity, or
541 // java.lang.instrument).
542 // The second is if another thread started the resolve_super first
543 // and has not yet finished.
544 // In both cases the original caller will clean up the placeholder
545 // entry on error.
546 Klass* superk = SystemDictionary::resolve_super_or_fail(name,
547 superclassname,
548 class_loader,
549 protection_domain,
550 true,
551 CHECK_(nh));
552
553 // parallelCapable class loaders do NOT wait for parallel superclass loads to complete
554 // Serial class loaders and bootstrap classloader do wait for superclass loads
555 if (!class_loader.is_null() && is_parallelCapable(class_loader)) {
556 MutexLocker mu(SystemDictionary_lock, THREAD);
557 // Check if classloading completed while we were loading superclass or waiting
558 Klass* check = find_class(d_index, d_hash, name, loader_data);
559 if (check != NULL) {
560 // Klass is already loaded, so just return it
561 return(instanceKlassHandle(THREAD, check));
562 } else {
563 return nh;
564 }
565 }
566
567 // must loop to both handle other placeholder updates
568 // and spurious notifications
569 bool super_load_in_progress = true;
570 PlaceholderEntry* placeholder;
571 while (super_load_in_progress) {
572 MutexLocker mu(SystemDictionary_lock, THREAD);
573 // Check if classloading completed while we were loading superclass or waiting
574 Klass* check = find_class(d_index, d_hash, name, loader_data);
575 if (check != NULL) {
576 // Klass is already loaded, so just return it
577 return(instanceKlassHandle(THREAD, check));
578 } else {
579 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
580 if (placeholder && placeholder->super_load_in_progress() ){
581 // Before UnsyncloadClass:
582 // We only get here if the application has released the
583 // classloader lock when another thread was in the middle of loading a
584 // superclass/superinterface for this class, and now
585 // this thread is also trying to load this class.
586 // To minimize surprises, the first thread that started to
587 // load a class should be the one to complete the loading
588 // with the classfile it initially expected.
589 // This logic has the current thread wait once it has done
590 // all the superclass/superinterface loading it can, until
591 // the original thread completes the class loading or fails
592 // If it completes we will use the resulting InstanceKlass
593 // which we will find below in the systemDictionary.
594 // We also get here for parallel bootstrap classloader
595 if (class_loader.is_null()) {
596 SystemDictionary_lock->wait();
597 } else {
598 double_lock_wait(lockObject, THREAD);
599 }
600 } else {
601 // If not in SD and not in PH, other thread's load must have failed
602 super_load_in_progress = false;
603 }
604 }
605 }
606 return (nh);
607 }
608
609
610 Klass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
611 Handle class_loader,
612 Handle protection_domain,
613 TRAPS) {
614 assert(name != NULL && !FieldType::is_array(name) &&
615 !FieldType::is_obj(name), "invalid class name");
616
617 Ticks class_load_start_time = Ticks::now();
618
619 // Fix for 4474172; see evaluation for more details
620 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
621 ClassLoaderData *loader_data = register_loader(class_loader, CHECK_NULL);
622
623 // Do lookup to see if class already exist and the protection domain
624 // has the right access
625 // This call uses find which checks protection domain already matches
626 // All subsequent calls use find_class, and set has_loaded_class so that
627 // before we return a result we call out to java to check for valid protection domain
628 // to allow returning the Klass* and add it to the pd_set if it is valid
629 unsigned int d_hash = dictionary()->compute_hash(name, loader_data);
630 int d_index = dictionary()->hash_to_index(d_hash);
631 Klass* probe = dictionary()->find(d_index, d_hash, name, loader_data,
632 protection_domain, THREAD);
633 if (probe != NULL) return probe;
634
635
636 // Non-bootstrap class loaders will call out to class loader and
637 // define via jvm/jni_DefineClass which will acquire the
638 // class loader object lock to protect against multiple threads
639 // defining the class in parallel by accident.
640 // This lock must be acquired here so the waiter will find
641 // any successful result in the SystemDictionary and not attempt
642 // the define
643 // ParallelCapable Classloaders and the bootstrap classloader,
644 // or all classloaders with UnsyncloadClass do not acquire lock here
645 bool DoObjectLock = true;
646 if (is_parallelCapable(class_loader)) {
647 DoObjectLock = false;
648 }
649
650 unsigned int p_hash = placeholders()->compute_hash(name, loader_data);
651 int p_index = placeholders()->hash_to_index(p_hash);
652
653 // Class is not in SystemDictionary so we have to do loading.
654 // Make sure we are synchronized on the class loader before we proceed
655 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
656 check_loader_lock_contention(lockObject, THREAD);
657 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
658
659 // Check again (after locking) if class already exist in SystemDictionary
660 bool class_has_been_loaded = false;
661 bool super_load_in_progress = false;
662 bool havesupername = false;
663 instanceKlassHandle k;
664 PlaceholderEntry* placeholder;
665 Symbol* superclassname = NULL;
666
667 {
668 MutexLocker mu(SystemDictionary_lock, THREAD);
669 Klass* check = find_class(d_index, d_hash, name, loader_data);
670 if (check != NULL) {
671 // Klass is already loaded, so just return it
672 class_has_been_loaded = true;
673 k = instanceKlassHandle(THREAD, check);
674 } else {
675 placeholder = placeholders()->get_entry(p_index, p_hash, name, loader_data);
676 if (placeholder && placeholder->super_load_in_progress()) {
677 super_load_in_progress = true;
678 if (placeholder->havesupername() == true) {
679 superclassname = placeholder->supername();
680 havesupername = true;
681 }
682 }
683 }
684 }
685
686 // If the class is in the placeholder table, class loading is in progress
687 if (super_load_in_progress && havesupername==true) {
688 k = SystemDictionary::handle_parallel_super_load(name, superclassname,
689 class_loader, protection_domain, lockObject, THREAD);
690 if (HAS_PENDING_EXCEPTION) {
691 return NULL;
692 }
693 if (!k.is_null()) {
694 class_has_been_loaded = true;
695 }
696 }
697
698 bool throw_circularity_error = false;
699 if (!class_has_been_loaded) {
700 bool load_instance_added = false;
701
702 // add placeholder entry to record loading instance class
703 // Five cases:
704 // All cases need to prevent modifying bootclasssearchpath
705 // in parallel with a classload of same classname
706 // Redefineclasses uses existence of the placeholder for the duration
707 // of the class load to prevent concurrent redefinition of not completely
708 // defined classes.
709 // case 1. traditional classloaders that rely on the classloader object lock
710 // - no other need for LOAD_INSTANCE
711 // case 2. traditional classloaders that break the classloader object lock
712 // as a deadlock workaround. Detection of this case requires that
713 // this check is done while holding the classloader object lock,
714 // and that lock is still held when calling classloader's loadClass.
715 // For these classloaders, we ensure that the first requestor
716 // completes the load and other requestors wait for completion.
717 // case 3. UnsyncloadClass - don't use objectLocker
718 // With this flag, we allow parallel classloading of a
719 // class/classloader pair
720 // case4. Bootstrap classloader - don't own objectLocker
721 // This classloader supports parallelism at the classloader level,
722 // but only allows a single load of a class/classloader pair.
723 // No performance benefit and no deadlock issues.
724 // case 5. parallelCapable user level classloaders - without objectLocker
725 // Allow parallel classloading of a class/classloader pair
726
727 {
728 MutexLocker mu(SystemDictionary_lock, THREAD);
729 if (class_loader.is_null() || !is_parallelCapable(class_loader)) {
730 PlaceholderEntry* oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
731 if (oldprobe) {
732 // only need check_seen_thread once, not on each loop
733 // 6341374 java/lang/Instrument with -Xcomp
734 if (oldprobe->check_seen_thread(THREAD, PlaceholderTable::LOAD_INSTANCE)) {
735 throw_circularity_error = true;
736 } else {
737 // case 1: traditional: should never see load_in_progress.
738 while (!class_has_been_loaded && oldprobe && oldprobe->instance_load_in_progress()) {
739
740 // case 4: bootstrap classloader: prevent futile classloading,
741 // wait on first requestor
742 if (class_loader.is_null()) {
743 SystemDictionary_lock->wait();
744 } else {
745 // case 2: traditional with broken classloader lock. wait on first
746 // requestor.
747 double_lock_wait(lockObject, THREAD);
748 }
749 // Check if classloading completed while we were waiting
750 Klass* check = find_class(d_index, d_hash, name, loader_data);
751 if (check != NULL) {
752 // Klass is already loaded, so just return it
753 k = instanceKlassHandle(THREAD, check);
754 class_has_been_loaded = true;
755 }
756 // check if other thread failed to load and cleaned up
757 oldprobe = placeholders()->get_entry(p_index, p_hash, name, loader_data);
758 }
759 }
760 }
761 }
762 // All cases: add LOAD_INSTANCE holding SystemDictionary_lock
763 // case 3: UnsyncloadClass || case 5: parallelCapable: allow competing threads to try
764 // LOAD_INSTANCE in parallel
765
766 if (!throw_circularity_error && !class_has_been_loaded) {
767 PlaceholderEntry* newprobe = placeholders()->find_and_add(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, NULL, THREAD);
768 load_instance_added = true;
769 // For class loaders that do not acquire the classloader object lock,
770 // if they did not catch another thread holding LOAD_INSTANCE,
771 // need a check analogous to the acquire ObjectLocker/find_class
772 // i.e. now that we hold the LOAD_INSTANCE token on loading this class/CL
773 // one final check if the load has already completed
774 // class loaders holding the ObjectLock shouldn't find the class here
775 Klass* check = find_class(d_index, d_hash, name, loader_data);
776 if (check != NULL) {
777 // Klass is already loaded, so return it after checking/adding protection domain
778 k = instanceKlassHandle(THREAD, check);
779 class_has_been_loaded = true;
780 }
781 }
782 }
783
784 // must throw error outside of owning lock
785 if (throw_circularity_error) {
786 assert(!HAS_PENDING_EXCEPTION && load_instance_added == false,"circularity error cleanup");
787 ResourceMark rm(THREAD);
788 THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
789 }
790
791 if (!class_has_been_loaded) {
792
793 // Do actual loading
794 k = load_instance_class(name, class_loader, THREAD);
795
796 // For UnsyncloadClass only
797 // If they got a linkageError, check if a parallel class load succeeded.
798 // If it did, then for bytecode resolution the specification requires
799 // that we return the same result we did for the other thread, i.e. the
800 // successfully loaded InstanceKlass
801 // Should not get here for classloaders that support parallelism
802 // with the new cleaner mechanism, even with AllowParallelDefineClass
803 // Bootstrap goes through here to allow for an extra guarantee check
804 if (UnsyncloadClass || (class_loader.is_null())) {
805 if (k.is_null() && HAS_PENDING_EXCEPTION
806 && PENDING_EXCEPTION->is_a(SystemDictionary::LinkageError_klass())) {
807 MutexLocker mu(SystemDictionary_lock, THREAD);
808 Klass* check = find_class(d_index, d_hash, name, loader_data);
809 if (check != NULL) {
810 // Klass is already loaded, so just use it
811 k = instanceKlassHandle(THREAD, check);
812 CLEAR_PENDING_EXCEPTION;
813 guarantee((!class_loader.is_null()), "dup definition for bootstrap loader?");
814 }
815 }
816 }
817
818 // If everything was OK (no exceptions, no null return value), and
819 // class_loader is NOT the defining loader, do a little more bookkeeping.
820 if (!HAS_PENDING_EXCEPTION && !k.is_null() &&
821 k->class_loader() != class_loader()) {
822
823 check_constraints(d_index, d_hash, k, class_loader, false, THREAD);
824
825 // Need to check for a PENDING_EXCEPTION again; check_constraints
826 // can throw and doesn't use the CHECK macro.
827 if (!HAS_PENDING_EXCEPTION) {
828 { // Grabbing the Compile_lock prevents systemDictionary updates
829 // during compilations.
830 MutexLocker mu(Compile_lock, THREAD);
831 update_dictionary(d_index, d_hash, p_index, p_hash,
832 k, class_loader, THREAD);
833 }
834
835 if (JvmtiExport::should_post_class_load()) {
836 Thread *thread = THREAD;
837 assert(thread->is_Java_thread(), "thread->is_Java_thread()");
838 JvmtiExport::post_class_load((JavaThread *) thread, k());
839 }
840 }
841 }
842 } // load_instance_class loop
843
844 if (load_instance_added == true) {
845 // clean up placeholder entries for LOAD_INSTANCE success or error
846 // This brackets the SystemDictionary updates for both defining
847 // and initiating loaders
848 MutexLocker mu(SystemDictionary_lock, THREAD);
849 placeholders()->find_and_remove(p_index, p_hash, name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
850 SystemDictionary_lock->notify_all();
851 }
852 }
853
854 if (HAS_PENDING_EXCEPTION || k.is_null()) {
855 return NULL;
856 }
857
858 post_class_load_event(class_load_start_time, k, class_loader);
859
860 #ifdef ASSERT
861 {
862 ClassLoaderData* loader_data = k->class_loader_data();
863 MutexLocker mu(SystemDictionary_lock, THREAD);
864 Klass* kk = find_class(name, loader_data);
865 assert(kk == k(), "should be present in dictionary");
866 }
867 #endif
868
869 // return if the protection domain in NULL
870 if (protection_domain() == NULL) return k();
871
872 // Check the protection domain has the right access
873 {
874 MutexLocker mu(SystemDictionary_lock, THREAD);
875 // Note that we have an entry, and entries can be deleted only during GC,
876 // so we cannot allow GC to occur while we're holding this entry.
877 // We're using a No_Safepoint_Verifier to catch any place where we
878 // might potentially do a GC at all.
879 // Dictionary::do_unloading() asserts that classes in SD are only
880 // unloaded at a safepoint. Anonymous classes are not in SD.
881 No_Safepoint_Verifier nosafepoint;
882 if (dictionary()->is_valid_protection_domain(d_index, d_hash, name,
883 loader_data,
884 protection_domain)) {
885 return k();
886 }
887 }
888
889 // Verify protection domain. If it fails an exception is thrown
890 validate_protection_domain(k, class_loader, protection_domain, CHECK_NULL);
891
892 return k();
893 }
894
895
896 // This routine does not lock the system dictionary.
897 //
898 // Since readers don't hold a lock, we must make sure that system
899 // dictionary entries are only removed at a safepoint (when only one
900 // thread is running), and are added to in a safe way (all links must
901 // be updated in an MT-safe manner).
902 //
903 // Callers should be aware that an entry could be added just after
904 // _dictionary->bucket(index) is read here, so the caller will not see
905 // the new entry.
906
907 Klass* SystemDictionary::find(Symbol* class_name,
908 Handle class_loader,
909 Handle protection_domain,
910 TRAPS) {
911
912 // The result of this call should be consistent with the result
913 // of the call to resolve_instance_class_or_null().
914 // See evaluation 6790209 and 4474172 for more details.
915 class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
916 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader());
917
918 if (loader_data == NULL) {
919 // If the ClassLoaderData has not been setup,
920 // then the class loader has no entries in the dictionary.
921 return NULL;
922 }
923
924 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
925 int d_index = dictionary()->hash_to_index(d_hash);
926
927 {
928 // Note that we have an entry, and entries can be deleted only during GC,
929 // so we cannot allow GC to occur while we're holding this entry.
930 // We're using a No_Safepoint_Verifier to catch any place where we
931 // might potentially do a GC at all.
932 // Dictionary::do_unloading() asserts that classes in SD are only
933 // unloaded at a safepoint. Anonymous classes are not in SD.
934 No_Safepoint_Verifier nosafepoint;
935 return dictionary()->find(d_index, d_hash, class_name, loader_data,
936 protection_domain, THREAD);
937 }
938 }
939
940
941 // Look for a loaded instance or array klass by name. Do not do any loading.
942 // return NULL in case of error.
943 Klass* SystemDictionary::find_instance_or_array_klass(Symbol* class_name,
944 Handle class_loader,
945 Handle protection_domain,
946 TRAPS) {
947 Klass* k = NULL;
948 assert(class_name != NULL, "class name must be non NULL");
949
950 if (FieldType::is_array(class_name)) {
951 // The name refers to an array. Parse the name.
952 // dimension and object_key in FieldArrayInfo are assigned as a
953 // side-effect of this call
954 FieldArrayInfo fd;
955 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
956 if (t != T_OBJECT) {
957 k = Universe::typeArrayKlassObj(t);
958 } else {
959 k = SystemDictionary::find(fd.object_key(), class_loader, protection_domain, THREAD);
960 }
961 if (k != NULL) {
962 k = k->array_klass_or_null(fd.dimension());
963 }
964 } else {
965 k = find(class_name, class_loader, protection_domain, THREAD);
966 }
967 return k;
968 }
969
970 // Note: this method is much like resolve_from_stream, but
971 // updates no supplemental data structures.
972 // TODO consolidate the two methods with a helper routine?
973 Klass* SystemDictionary::parse_stream(Symbol* class_name,
974 Handle class_loader,
975 Handle protection_domain,
976 ClassFileStream* st,
977 KlassHandle host_klass,
978 GrowableArray<Handle>* cp_patches,
979 TRAPS) {
980 TempNewSymbol parsed_name = NULL;
981
982 Ticks class_load_start_time = Ticks::now();
983
984 ClassLoaderData* loader_data;
985 if (host_klass.not_null()) {
986 // Create a new CLD for anonymous class, that uses the same class loader
987 // as the host_klass
988 guarantee(host_klass->class_loader() == class_loader(), "should be the same");
989 guarantee(!DumpSharedSpaces, "must not create anonymous classes when dumping");
990 loader_data = ClassLoaderData::anonymous_class_loader_data(class_loader(), CHECK_NULL);
991 loader_data->record_dependency(host_klass(), CHECK_NULL);
992 } else {
993 loader_data = ClassLoaderData::class_loader_data(class_loader());
994 }
995
996 // Parse the stream. Note that we do this even though this klass might
997 // already be present in the SystemDictionary, otherwise we would not
998 // throw potential ClassFormatErrors.
999 //
1000 // Note: "name" is updated.
1001
1002 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1003 loader_data,
1004 protection_domain,
1005 host_klass,
1006 cp_patches,
1007 parsed_name,
1008 true,
1009 THREAD);
1010
1011
1012 if (host_klass.not_null() && k.not_null()) {
1013 // If it's anonymous, initialize it now, since nobody else will.
1014
1015 {
1016 MutexLocker mu_r(Compile_lock, THREAD);
1017
1018 // Add to class hierarchy, initialize vtables, and do possible
1019 // deoptimizations.
1020 add_to_hierarchy(k, CHECK_NULL); // No exception, but can block
1021
1022 // But, do not add to system dictionary.
1023
1024 // compiled code dependencies need to be validated anyway
1025 notice_modification();
1026 }
1027
1028 // Rewrite and patch constant pool here.
1029 k->link_class(CHECK_NULL);
1030 if (cp_patches != NULL) {
1031 k->constants()->patch_resolved_references(cp_patches);
1032 }
1033 k->eager_initialize(CHECK_NULL);
1034
1035 // notify jvmti
1036 if (JvmtiExport::should_post_class_load()) {
1037 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1038 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1039 }
1040
1041 post_class_load_event(class_load_start_time, k, class_loader);
1042 }
1043 assert(host_klass.not_null() || cp_patches == NULL,
1044 "cp_patches only found with host_klass");
1045
1046 return k();
1047 }
1048
1049 // Add a klass to the system from a stream (called by jni_DefineClass and
1050 // JVM_DefineClass).
1051 // Note: class_name can be NULL. In that case we do not know the name of
1052 // the class until we have parsed the stream.
1053
1054 Klass* SystemDictionary::resolve_from_stream(Symbol* class_name,
1055 Handle class_loader,
1056 Handle protection_domain,
1057 ClassFileStream* st,
1058 bool verify,
1059 TRAPS) {
1060
1061 // Classloaders that support parallelism, e.g. bootstrap classloader,
1062 // or all classloaders with UnsyncloadClass do not acquire lock here
1063 bool DoObjectLock = true;
1064 if (is_parallelCapable(class_loader)) {
1065 DoObjectLock = false;
1066 }
1067
1068 ClassLoaderData* loader_data = register_loader(class_loader, CHECK_NULL);
1069
1070 // Make sure we are synchronized on the class loader before we proceed
1071 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1072 check_loader_lock_contention(lockObject, THREAD);
1073 ObjectLocker ol(lockObject, THREAD, DoObjectLock);
1074
1075 TempNewSymbol parsed_name = NULL;
1076
1077 // Parse the stream. Note that we do this even though this klass might
1078 // already be present in the SystemDictionary, otherwise we would not
1079 // throw potential ClassFormatErrors.
1080 //
1081 // Note: "name" is updated.
1082
1083 instanceKlassHandle k = ClassFileParser(st).parseClassFile(class_name,
1084 loader_data,
1085 protection_domain,
1086 parsed_name,
1087 verify,
1088 THREAD);
1089
1090 const char* pkg = "java/";
1091 if (!HAS_PENDING_EXCEPTION &&
1092 !class_loader.is_null() &&
1093 parsed_name != NULL &&
1094 !strncmp((const char*)parsed_name->bytes(), pkg, strlen(pkg))) {
1095 // It is illegal to define classes in the "java." package from
1096 // JVM_DefineClass or jni_DefineClass unless you're the bootclassloader
1097 ResourceMark rm(THREAD);
1098 char* name = parsed_name->as_C_string();
1099 char* index = strrchr(name, '/');
1100 *index = '\0'; // chop to just the package name
1101 while ((index = strchr(name, '/')) != NULL) {
1102 *index = '.'; // replace '/' with '.' in package name
1103 }
1104 const char* fmt = "Prohibited package name: %s";
1105 size_t len = strlen(fmt) + strlen(name);
1106 char* message = NEW_RESOURCE_ARRAY(char, len);
1107 jio_snprintf(message, len, fmt, name);
1108 Exceptions::_throw_msg(THREAD_AND_LOCATION,
1109 vmSymbols::java_lang_SecurityException(), message);
1110 }
1111
1112 if (!HAS_PENDING_EXCEPTION) {
1113 assert(parsed_name != NULL, "Sanity");
1114 assert(class_name == NULL || class_name == parsed_name, "name mismatch");
1115 // Verification prevents us from creating names with dots in them, this
1116 // asserts that that's the case.
1117 assert(is_internal_format(parsed_name),
1118 "external class name format used internally");
1119
1120 // Add class just loaded
1121 // If a class loader supports parallel classloading handle parallel define requests
1122 // find_or_define_instance_class may return a different InstanceKlass
1123 if (is_parallelCapable(class_loader)) {
1124 k = find_or_define_instance_class(class_name, class_loader, k, THREAD);
1125 } else {
1126 define_instance_class(k, THREAD);
1127 }
1128 }
1129
1130 // Make sure we have an entry in the SystemDictionary on success
1131 debug_only( {
1132 if (!HAS_PENDING_EXCEPTION) {
1133 assert(parsed_name != NULL, "parsed_name is still null?");
1134 Symbol* h_name = k->name();
1135 ClassLoaderData *defining_loader_data = k->class_loader_data();
1136
1137 MutexLocker mu(SystemDictionary_lock, THREAD);
1138
1139 Klass* check = find_class(parsed_name, loader_data);
1140 assert(check == k(), "should be present in the dictionary");
1141
1142 Klass* check2 = find_class(h_name, defining_loader_data);
1143 assert(check == check2, "name inconsistancy in SystemDictionary");
1144 }
1145 } );
1146
1147 return k();
1148 }
1149
1150 #if INCLUDE_CDS
1151 void SystemDictionary::set_shared_dictionary(HashtableBucket<mtClass>* t, int length,
1152 int number_of_entries) {
1153 assert(length == _nof_buckets * sizeof(HashtableBucket<mtClass>),
1154 "bad shared dictionary size.");
1155 _shared_dictionary = new Dictionary(_nof_buckets, t, number_of_entries);
1156 }
1157
1158
1159 // If there is a shared dictionary, then find the entry for the
1160 // given shared system class, if any.
1161
1162 Klass* SystemDictionary::find_shared_class(Symbol* class_name) {
1163 if (shared_dictionary() != NULL) {
1164 unsigned int d_hash = shared_dictionary()->compute_hash(class_name, NULL);
1165 int d_index = shared_dictionary()->hash_to_index(d_hash);
1166
1167 return shared_dictionary()->find_shared_class(d_index, d_hash, class_name);
1168 } else {
1169 return NULL;
1170 }
1171 }
1172
1173
1174 // Load a class from the shared spaces (found through the shared system
1175 // dictionary). Force the superclass and all interfaces to be loaded.
1176 // Update the class definition to include sibling classes and no
1177 // subclasses (yet). [Classes in the shared space are not part of the
1178 // object hierarchy until loaded.]
1179
1180 instanceKlassHandle SystemDictionary::load_shared_class(
1181 Symbol* class_name, Handle class_loader, TRAPS) {
1182 instanceKlassHandle ik (THREAD, find_shared_class(class_name));
1183 // Make sure we only return the boot class for the NULL classloader.
1184 if (ik.not_null() &&
1185 SharedClassUtil::is_shared_boot_class(ik()) && class_loader.is_null()) {
1186 Handle protection_domain;
1187 return load_shared_class(ik, class_loader, protection_domain, THREAD);
1188 }
1189 return instanceKlassHandle();
1190 }
1191
1192 instanceKlassHandle SystemDictionary::load_shared_class(instanceKlassHandle ik,
1193 Handle class_loader,
1194 Handle protection_domain, TRAPS) {
1195 if (ik.not_null()) {
1196 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1197 Symbol* class_name = ik->name();
1198
1199 // Found the class, now load the superclass and interfaces. If they
1200 // are shared, add them to the main system dictionary and reset
1201 // their hierarchy references (supers, subs, and interfaces).
1202
1203 if (ik->super() != NULL) {
1204 Symbol* cn = ik->super()->name();
1205 resolve_super_or_fail(class_name, cn,
1206 class_loader, protection_domain, true, CHECK_(nh));
1207 }
1208
1209 Array<Klass*>* interfaces = ik->local_interfaces();
1210 int num_interfaces = interfaces->length();
1211 for (int index = 0; index < num_interfaces; index++) {
1212 Klass* k = interfaces->at(index);
1213
1214 // Note: can not use InstanceKlass::cast here because
1215 // interfaces' InstanceKlass's C++ vtbls haven't been
1216 // reinitialized yet (they will be once the interface classes
1217 // are loaded)
1218 Symbol* name = k->name();
1219 resolve_super_or_fail(class_name, name, class_loader, protection_domain, false, CHECK_(nh));
1220 }
1221
1222 // Adjust methods to recover missing data. They need addresses for
1223 // interpreter entry points and their default native method address
1224 // must be reset.
1225
1226 // Updating methods must be done under a lock so multiple
1227 // threads don't update these in parallel
1228 //
1229 // Shared classes are all currently loaded by either the bootstrap or
1230 // internal parallel class loaders, so this will never cause a deadlock
1231 // on a custom class loader lock.
1232
1233 ClassLoaderData* loader_data = ClassLoaderData::class_loader_data(class_loader());
1234 {
1235 Handle lockObject = compute_loader_lock_object(class_loader, THREAD);
1236 check_loader_lock_contention(lockObject, THREAD);
1237 ObjectLocker ol(lockObject, THREAD, true);
1238 ik->restore_unshareable_info(loader_data, protection_domain, CHECK_(nh));
1239 }
1240
1241 if (TraceClassLoading) {
1242 ResourceMark rm;
1243 tty->print("[Loaded %s", ik->external_name());
1244 tty->print(" from shared objects file");
1245 if (class_loader.not_null()) {
1246 tty->print(" by %s", loader_data->loader_name());
1247 }
1248 tty->print_cr("]");
1249 }
1250
1251 if (log_is_enabled(Debug, classload)) {
1252 ik()->print_loading_log(LogLevel::Debug, loader_data, NULL);
1253 }
1254 if (log_is_enabled(Trace, classload)) {
1255 ik()->print_loading_log(LogLevel::Trace, loader_data, NULL);
1256 }
1257
1258 if (DumpLoadedClassList != NULL && classlist_file->is_open()) {
1259 // Only dump the classes that can be stored into CDS archive
1260 if (SystemDictionaryShared::is_sharing_possible(loader_data)) {
1261 ResourceMark rm(THREAD);
1262 classlist_file->print_cr("%s", ik->name()->as_C_string());
1263 classlist_file->flush();
1264 }
1265 }
1266
1267 // notify a class loaded from shared object
1268 ClassLoadingService::notify_class_loaded(ik(), true /* shared class */);
1269 }
1270 return ik;
1271 }
1272 #endif // INCLUDE_CDS
1273
1274 instanceKlassHandle SystemDictionary::load_instance_class(Symbol* class_name, Handle class_loader, TRAPS) {
1275 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1276 if (class_loader.is_null()) {
1277
1278 // Search the shared system dictionary for classes preloaded into the
1279 // shared spaces.
1280 instanceKlassHandle k;
1281 {
1282 #if INCLUDE_CDS
1283 PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1284 k = load_shared_class(class_name, class_loader, THREAD);
1285 #endif
1286 }
1287
1288 if (k.is_null()) {
1289 // Use VM class loader
1290 PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1291 k = ClassLoader::load_classfile(class_name, CHECK_(nh));
1292 }
1293
1294 // find_or_define_instance_class may return a different InstanceKlass
1295 if (!k.is_null()) {
1296 k = find_or_define_instance_class(class_name, class_loader, k, CHECK_(nh));
1297 }
1298 return k;
1299 } else {
1300 // Use user specified class loader to load class. Call loadClass operation on class_loader.
1301 ResourceMark rm(THREAD);
1302
1303 assert(THREAD->is_Java_thread(), "must be a JavaThread");
1304 JavaThread* jt = (JavaThread*) THREAD;
1305
1306 PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1307 ClassLoader::perf_app_classload_selftime(),
1308 ClassLoader::perf_app_classload_count(),
1309 jt->get_thread_stat()->perf_recursion_counts_addr(),
1310 jt->get_thread_stat()->perf_timers_addr(),
1311 PerfClassTraceTime::CLASS_LOAD);
1312
1313 Handle s = java_lang_String::create_from_symbol(class_name, CHECK_(nh));
1314 // Translate to external class name format, i.e., convert '/' chars to '.'
1315 Handle string = java_lang_String::externalize_classname(s, CHECK_(nh));
1316
1317 JavaValue result(T_OBJECT);
1318
1319 KlassHandle spec_klass (THREAD, SystemDictionary::ClassLoader_klass());
1320
1321 // Call public unsynchronized loadClass(String) directly for all class loaders
1322 // for parallelCapable class loaders. JDK >=7, loadClass(String, boolean) will
1323 // acquire a class-name based lock rather than the class loader object lock.
1324 // JDK < 7 already acquire the class loader lock in loadClass(String, boolean),
1325 // so the call to loadClassInternal() was not required.
1326 //
1327 // UnsyncloadClass flag means both call loadClass(String) and do
1328 // not acquire the class loader lock even for class loaders that are
1329 // not parallelCapable. This was a risky transitional
1330 // flag for diagnostic purposes only. It is risky to call
1331 // custom class loaders without synchronization.
1332 // WARNING If a custom class loader does NOT synchronizer findClass, or callers of
1333 // findClass, the UnsyncloadClass flag risks unexpected timing bugs in the field.
1334 // Do NOT assume this will be supported in future releases.
1335 //
1336 // Added MustCallLoadClassInternal in case we discover in the field
1337 // a customer that counts on this call
1338 if (MustCallLoadClassInternal && has_loadClassInternal()) {
1339 JavaCalls::call_special(&result,
1340 class_loader,
1341 spec_klass,
1342 vmSymbols::loadClassInternal_name(),
1343 vmSymbols::string_class_signature(),
1344 string,
1345 CHECK_(nh));
1346 } else {
1347 JavaCalls::call_virtual(&result,
1348 class_loader,
1349 spec_klass,
1350 vmSymbols::loadClass_name(),
1351 vmSymbols::string_class_signature(),
1352 string,
1353 CHECK_(nh));
1354 }
1355
1356 assert(result.get_type() == T_OBJECT, "just checking");
1357 oop obj = (oop) result.get_jobject();
1358
1359 // Primitive classes return null since forName() can not be
1360 // used to obtain any of the Class objects representing primitives or void
1361 if ((obj != NULL) && !(java_lang_Class::is_primitive(obj))) {
1362 instanceKlassHandle k =
1363 instanceKlassHandle(THREAD, java_lang_Class::as_Klass(obj));
1364 // For user defined Java class loaders, check that the name returned is
1365 // the same as that requested. This check is done for the bootstrap
1366 // loader when parsing the class file.
1367 if (class_name == k->name()) {
1368 return k;
1369 }
1370 }
1371 // Class is not found or has the wrong name, return NULL
1372 return nh;
1373 }
1374 }
1375
1376 void SystemDictionary::define_instance_class(instanceKlassHandle k, TRAPS) {
1377
1378 ClassLoaderData* loader_data = k->class_loader_data();
1379 Handle class_loader_h(THREAD, loader_data->class_loader());
1380
1381 // for bootstrap and other parallel classloaders don't acquire lock,
1382 // use placeholder token
1383 // If a parallelCapable class loader calls define_instance_class instead of
1384 // find_or_define_instance_class to get here, we have a timing
1385 // hole with systemDictionary updates and check_constraints
1386 if (!class_loader_h.is_null() && !is_parallelCapable(class_loader_h)) {
1387 assert(ObjectSynchronizer::current_thread_holds_lock((JavaThread*)THREAD,
1388 compute_loader_lock_object(class_loader_h, THREAD)),
1389 "define called without lock");
1390 }
1391
1392 // Check class-loading constraints. Throw exception if violation is detected.
1393 // Grabs and releases SystemDictionary_lock
1394 // The check_constraints/find_class call and update_dictionary sequence
1395 // must be "atomic" for a specific class/classloader pair so we never
1396 // define two different instanceKlasses for that class/classloader pair.
1397 // Existing classloaders will call define_instance_class with the
1398 // classloader lock held
1399 // Parallel classloaders will call find_or_define_instance_class
1400 // which will require a token to perform the define class
1401 Symbol* name_h = k->name();
1402 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1403 int d_index = dictionary()->hash_to_index(d_hash);
1404 check_constraints(d_index, d_hash, k, class_loader_h, true, CHECK);
1405
1406 // Register class just loaded with class loader (placed in Vector)
1407 // Note we do this before updating the dictionary, as this can
1408 // fail with an OutOfMemoryError (if it does, we will *not* put this
1409 // class in the dictionary and will not update the class hierarchy).
1410 // JVMTI FollowReferences needs to find the classes this way.
1411 if (k->class_loader() != NULL) {
1412 methodHandle m(THREAD, Universe::loader_addClass_method());
1413 JavaValue result(T_VOID);
1414 JavaCallArguments args(class_loader_h);
1415 args.push_oop(Handle(THREAD, k->java_mirror()));
1416 JavaCalls::call(&result, m, &args, CHECK);
1417 }
1418
1419 // Add the new class. We need recompile lock during update of CHA.
1420 {
1421 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1422 int p_index = placeholders()->hash_to_index(p_hash);
1423
1424 MutexLocker mu_r(Compile_lock, THREAD);
1425
1426 // Add to class hierarchy, initialize vtables, and do possible
1427 // deoptimizations.
1428 add_to_hierarchy(k, CHECK); // No exception, but can block
1429
1430 // Add to systemDictionary - so other classes can see it.
1431 // Grabs and releases SystemDictionary_lock
1432 update_dictionary(d_index, d_hash, p_index, p_hash,
1433 k, class_loader_h, THREAD);
1434 }
1435 k->eager_initialize(THREAD);
1436
1437 // notify jvmti
1438 if (JvmtiExport::should_post_class_load()) {
1439 assert(THREAD->is_Java_thread(), "thread->is_Java_thread()");
1440 JvmtiExport::post_class_load((JavaThread *) THREAD, k());
1441
1442 }
1443
1444 }
1445
1446 // Support parallel classloading
1447 // All parallel class loaders, including bootstrap classloader
1448 // lock a placeholder entry for this class/class_loader pair
1449 // to allow parallel defines of different classes for this class loader
1450 // With AllowParallelDefine flag==true, in case they do not synchronize around
1451 // FindLoadedClass/DefineClass, calls, we check for parallel
1452 // loading for them, wait if a defineClass is in progress
1453 // and return the initial requestor's results
1454 // This flag does not apply to the bootstrap classloader.
1455 // With AllowParallelDefine flag==false, call through to define_instance_class
1456 // which will throw LinkageError: duplicate class definition.
1457 // False is the requested default.
1458 // For better performance, the class loaders should synchronize
1459 // findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1460 // potentially waste time reading and parsing the bytestream.
1461 // Note: VM callers should ensure consistency of k/class_name,class_loader
1462 instanceKlassHandle SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader, instanceKlassHandle k, TRAPS) {
1463
1464 instanceKlassHandle nh = instanceKlassHandle(); // null Handle
1465 Symbol* name_h = k->name(); // passed in class_name may be null
1466 ClassLoaderData* loader_data = class_loader_data(class_loader);
1467
1468 unsigned int d_hash = dictionary()->compute_hash(name_h, loader_data);
1469 int d_index = dictionary()->hash_to_index(d_hash);
1470
1471 // Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1472 unsigned int p_hash = placeholders()->compute_hash(name_h, loader_data);
1473 int p_index = placeholders()->hash_to_index(p_hash);
1474 PlaceholderEntry* probe;
1475
1476 {
1477 MutexLocker mu(SystemDictionary_lock, THREAD);
1478 // First check if class already defined
1479 if (UnsyncloadClass || (is_parallelDefine(class_loader))) {
1480 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1481 if (check != NULL) {
1482 return(instanceKlassHandle(THREAD, check));
1483 }
1484 }
1485
1486 // Acquire define token for this class/classloader
1487 probe = placeholders()->find_and_add(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, NULL, THREAD);
1488 // Wait if another thread defining in parallel
1489 // All threads wait - even those that will throw duplicate class: otherwise
1490 // caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1491 // if other thread has not finished updating dictionary
1492 while (probe->definer() != NULL) {
1493 SystemDictionary_lock->wait();
1494 }
1495 // Only special cases allow parallel defines and can use other thread's results
1496 // Other cases fall through, and may run into duplicate defines
1497 // caught by finding an entry in the SystemDictionary
1498 if ((UnsyncloadClass || is_parallelDefine(class_loader)) && (probe->instance_klass() != NULL)) {
1499 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1500 SystemDictionary_lock->notify_all();
1501 #ifdef ASSERT
1502 Klass* check = find_class(d_index, d_hash, name_h, loader_data);
1503 assert(check != NULL, "definer missed recording success");
1504 #endif
1505 return(instanceKlassHandle(THREAD, probe->instance_klass()));
1506 } else {
1507 // This thread will define the class (even if earlier thread tried and had an error)
1508 probe->set_definer(THREAD);
1509 }
1510 }
1511
1512 define_instance_class(k, THREAD);
1513
1514 Handle linkage_exception = Handle(); // null handle
1515
1516 // definer must notify any waiting threads
1517 {
1518 MutexLocker mu(SystemDictionary_lock, THREAD);
1519 PlaceholderEntry* probe = placeholders()->get_entry(p_index, p_hash, name_h, loader_data);
1520 assert(probe != NULL, "DEFINE_CLASS placeholder lost?");
1521 if (probe != NULL) {
1522 if (HAS_PENDING_EXCEPTION) {
1523 linkage_exception = Handle(THREAD,PENDING_EXCEPTION);
1524 CLEAR_PENDING_EXCEPTION;
1525 } else {
1526 probe->set_instance_klass(k());
1527 }
1528 probe->set_definer(NULL);
1529 placeholders()->find_and_remove(p_index, p_hash, name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1530 SystemDictionary_lock->notify_all();
1531 }
1532 }
1533
1534 // Can't throw exception while holding lock due to rank ordering
1535 if (linkage_exception() != NULL) {
1536 THROW_OOP_(linkage_exception(), nh); // throws exception and returns
1537 }
1538
1539 return k;
1540 }
1541 Handle SystemDictionary::compute_loader_lock_object(Handle class_loader, TRAPS) {
1542 // If class_loader is NULL we synchronize on _system_loader_lock_obj
1543 if (class_loader.is_null()) {
1544 return Handle(THREAD, _system_loader_lock_obj);
1545 } else {
1546 return class_loader;
1547 }
1548 }
1549
1550 // This method is added to check how often we have to wait to grab loader
1551 // lock. The results are being recorded in the performance counters defined in
1552 // ClassLoader::_sync_systemLoaderLockContentionRate and
1553 // ClassLoader::_sync_nonSystemLoaderLockConteionRate.
1554 void SystemDictionary::check_loader_lock_contention(Handle loader_lock, TRAPS) {
1555 if (!UsePerfData) {
1556 return;
1557 }
1558
1559 assert(!loader_lock.is_null(), "NULL lock object");
1560
1561 if (ObjectSynchronizer::query_lock_ownership((JavaThread*)THREAD, loader_lock)
1562 == ObjectSynchronizer::owner_other) {
1563 // contention will likely happen, so increment the corresponding
1564 // contention counter.
1565 if (loader_lock() == _system_loader_lock_obj) {
1566 ClassLoader::sync_systemLoaderLockContentionRate()->inc();
1567 } else {
1568 ClassLoader::sync_nonSystemLoaderLockContentionRate()->inc();
1569 }
1570 }
1571 }
1572
1573 // ----------------------------------------------------------------------------
1574 // Lookup
1575
1576 Klass* SystemDictionary::find_class(int index, unsigned int hash,
1577 Symbol* class_name,
1578 ClassLoaderData* loader_data) {
1579 assert_locked_or_safepoint(SystemDictionary_lock);
1580 assert (index == dictionary()->index_for(class_name, loader_data),
1581 "incorrect index?");
1582
1583 Klass* k = dictionary()->find_class(index, hash, class_name, loader_data);
1584 return k;
1585 }
1586
1587
1588 // Basic find on classes in the midst of being loaded
1589 Symbol* SystemDictionary::find_placeholder(Symbol* class_name,
1590 ClassLoaderData* loader_data) {
1591 assert_locked_or_safepoint(SystemDictionary_lock);
1592 unsigned int p_hash = placeholders()->compute_hash(class_name, loader_data);
1593 int p_index = placeholders()->hash_to_index(p_hash);
1594 return placeholders()->find_entry(p_index, p_hash, class_name, loader_data);
1595 }
1596
1597
1598 // Used for assertions and verification only
1599 Klass* SystemDictionary::find_class(Symbol* class_name, ClassLoaderData* loader_data) {
1600 #ifndef ASSERT
1601 guarantee(VerifyBeforeGC ||
1602 VerifyDuringGC ||
1603 VerifyBeforeExit ||
1604 VerifyDuringStartup ||
1605 VerifyAfterGC, "too expensive");
1606 #endif
1607 assert_locked_or_safepoint(SystemDictionary_lock);
1608
1609 // First look in the loaded class array
1610 unsigned int d_hash = dictionary()->compute_hash(class_name, loader_data);
1611 int d_index = dictionary()->hash_to_index(d_hash);
1612 return find_class(d_index, d_hash, class_name, loader_data);
1613 }
1614
1615
1616 // Get the next class in the diictionary.
1617 Klass* SystemDictionary::try_get_next_class() {
1618 return dictionary()->try_get_next_class();
1619 }
1620
1621
1622 // ----------------------------------------------------------------------------
1623 // Update hierachy. This is done before the new klass has been added to the SystemDictionary. The Recompile_lock
1624 // is held, to ensure that the compiler is not using the class hierachy, and that deoptimization will kick in
1625 // before a new class is used.
1626
1627 void SystemDictionary::add_to_hierarchy(instanceKlassHandle k, TRAPS) {
1628 assert(k.not_null(), "just checking");
1629 assert_locked_or_safepoint(Compile_lock);
1630
1631 // Link into hierachy. Make sure the vtables are initialized before linking into
1632 k->append_to_sibling_list(); // add to superklass/sibling list
1633 k->process_interfaces(THREAD); // handle all "implements" declarations
1634 k->set_init_state(InstanceKlass::loaded);
1635 // Now flush all code that depended on old class hierarchy.
1636 // Note: must be done *after* linking k into the hierarchy (was bug 12/9/97)
1637 // Also, first reinitialize vtable because it may have gotten out of synch
1638 // while the new class wasn't connected to the class hierarchy.
1639 CodeCache::flush_dependents_on(k);
1640 }
1641
1642 // ----------------------------------------------------------------------------
1643 // GC support
1644
1645 // Following roots during mark-sweep is separated in two phases.
1646 //
1647 // The first phase follows preloaded classes and all other system
1648 // classes, since these will never get unloaded anyway.
1649 //
1650 // The second phase removes (unloads) unreachable classes from the
1651 // system dictionary and follows the remaining classes' contents.
1652
1653 void SystemDictionary::always_strong_oops_do(OopClosure* blk) {
1654 roots_oops_do(blk, NULL);
1655 }
1656
1657 void SystemDictionary::always_strong_classes_do(KlassClosure* closure) {
1658 // Follow all system classes and temporary placeholders in dictionary
1659 dictionary()->always_strong_classes_do(closure);
1660
1661 // Placeholders. These represent classes we're actively loading.
1662 placeholders()->classes_do(closure);
1663 }
1664
1665 // Calculate a "good" systemdictionary size based
1666 // on predicted or current loaded classes count
1667 int SystemDictionary::calculate_systemdictionary_size(int classcount) {
1668 int newsize = _old_default_sdsize;
1669 if ((classcount > 0) && !DumpSharedSpaces) {
1670 int desiredsize = classcount/_average_depth_goal;
1671 for (newsize = _primelist[_sdgeneration]; _sdgeneration < _prime_array_size -1;
1672 newsize = _primelist[++_sdgeneration]) {
1673 if (desiredsize <= newsize) {
1674 break;
1675 }
1676 }
1677 }
1678 return newsize;
1679 }
1680
1681 #ifdef ASSERT
1682 class VerifySDReachableAndLiveClosure : public OopClosure {
1683 private:
1684 BoolObjectClosure* _is_alive;
1685
1686 template <class T> void do_oop_work(T* p) {
1687 oop obj = oopDesc::load_decode_heap_oop(p);
1688 guarantee(_is_alive->do_object_b(obj), "Oop in system dictionary must be live");
1689 }
1690
1691 public:
1692 VerifySDReachableAndLiveClosure(BoolObjectClosure* is_alive) : OopClosure(), _is_alive(is_alive) { }
1693
1694 virtual void do_oop(oop* p) { do_oop_work(p); }
1695 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
1696 };
1697 #endif
1698
1699 // Assumes classes in the SystemDictionary are only unloaded at a safepoint
1700 // Note: anonymous classes are not in the SD.
1701 bool SystemDictionary::do_unloading(BoolObjectClosure* is_alive,
1702 bool clean_previous_versions) {
1703 // First, mark for unload all ClassLoaderData referencing a dead class loader.
1704 bool unloading_occurred = ClassLoaderDataGraph::do_unloading(is_alive,
1705 clean_previous_versions);
1706 if (unloading_occurred) {
1707 dictionary()->do_unloading();
1708 constraints()->purge_loader_constraints();
1709 resolution_errors()->purge_resolution_errors();
1710 }
1711 // Oops referenced by the system dictionary may get unreachable independently
1712 // of the class loader (eg. cached protection domain oops). So we need to
1713 // explicitly unlink them here instead of in Dictionary::do_unloading.
1714 dictionary()->unlink(is_alive);
1715 #ifdef ASSERT
1716 VerifySDReachableAndLiveClosure cl(is_alive);
1717 dictionary()->oops_do(&cl);
1718 #endif
1719 return unloading_occurred;
1720 }
1721
1722 void SystemDictionary::roots_oops_do(OopClosure* strong, OopClosure* weak) {
1723 strong->do_oop(&_java_system_loader);
1724 strong->do_oop(&_system_loader_lock_obj);
1725 CDS_ONLY(SystemDictionaryShared::roots_oops_do(strong);)
1726
1727 // Adjust dictionary
1728 dictionary()->roots_oops_do(strong, weak);
1729
1730 // Visit extra methods
1731 invoke_method_table()->oops_do(strong);
1732 }
1733
1734 void SystemDictionary::oops_do(OopClosure* f) {
1735 f->do_oop(&_java_system_loader);
1736 f->do_oop(&_system_loader_lock_obj);
1737 CDS_ONLY(SystemDictionaryShared::oops_do(f);)
1738
1739 // Adjust dictionary
1740 dictionary()->oops_do(f);
1741
1742 // Visit extra methods
1743 invoke_method_table()->oops_do(f);
1744 }
1745
1746 // Extended Class redefinition support.
1747 // If one of these classes is replaced, we need to replace it in these places.
1748 // KlassClosure::do_klass should take the address of a class but we can
1749 // change that later.
1750 void SystemDictionary::preloaded_classes_do(KlassClosure* f) {
1751 for (int k = (int)FIRST_WKID; k < (int)WKID_LIMIT; k++) {
1752 f->do_klass(_well_known_klasses[k]);
1753 }
1754
1755 {
1756 for (int i = 0; i < T_VOID+1; i++) {
1757 if (_box_klasses[i] != NULL) {
1758 assert(i >= T_BOOLEAN, "checking");
1759 f->do_klass(_box_klasses[i]);
1760 }
1761 }
1762 }
1763
1764 FilteredFieldsMap::classes_do(f);
1765 }
1766
1767 void SystemDictionary::lazily_loaded_classes_do(KlassClosure* f) {
1768 f->do_klass(_abstract_ownable_synchronizer_klass);
1769 }
1770
1771 // Just the classes from defining class loaders
1772 // Don't iterate over placeholders
1773 void SystemDictionary::classes_do(void f(Klass*)) {
1774 dictionary()->classes_do(f);
1775 }
1776
1777 // Added for initialize_itable_for_klass
1778 // Just the classes from defining class loaders
1779 // Don't iterate over placeholders
1780 void SystemDictionary::classes_do(void f(Klass*, TRAPS), TRAPS) {
1781 dictionary()->classes_do(f, CHECK);
1782 }
1783
1784 // All classes, and their class loaders
1785 // Don't iterate over placeholders
1786 void SystemDictionary::classes_do(void f(Klass*, ClassLoaderData*)) {
1787 dictionary()->classes_do(f);
1788 }
1789
1790 void SystemDictionary::placeholders_do(void f(Symbol*)) {
1791 placeholders()->entries_do(f);
1792 }
1793
1794 void SystemDictionary::methods_do(void f(Method*)) {
1795 dictionary()->methods_do(f);
1796 invoke_method_table()->methods_do(f);
1797 }
1798
1799 void SystemDictionary::remove_classes_in_error_state() {
1800 dictionary()->remove_classes_in_error_state();
1801 }
1802
1803 // ----------------------------------------------------------------------------
1804 // Lazily load klasses
1805
1806 void SystemDictionary::load_abstract_ownable_synchronizer_klass(TRAPS) {
1807 // if multiple threads calling this function, only one thread will load
1808 // the class. The other threads will find the loaded version once the
1809 // class is loaded.
1810 Klass* aos = _abstract_ownable_synchronizer_klass;
1811 if (aos == NULL) {
1812 Klass* k = resolve_or_fail(vmSymbols::java_util_concurrent_locks_AbstractOwnableSynchronizer(), true, CHECK);
1813 // Force a fence to prevent any read before the write completes
1814 OrderAccess::fence();
1815 _abstract_ownable_synchronizer_klass = InstanceKlass::cast(k);
1816 }
1817 }
1818
1819 // ----------------------------------------------------------------------------
1820 // Initialization
1821
1822 void SystemDictionary::initialize(TRAPS) {
1823 // Allocate arrays
1824 assert(dictionary() == NULL,
1825 "SystemDictionary should only be initialized once");
1826 _sdgeneration = 0;
1827 _dictionary = new Dictionary(calculate_systemdictionary_size(PredictedLoadedClassCount));
1828 _placeholders = new PlaceholderTable(_nof_buckets);
1829 _number_of_modifications = 0;
1830 _loader_constraints = new LoaderConstraintTable(_loader_constraint_size);
1831 _resolution_errors = new ResolutionErrorTable(_resolution_error_size);
1832 _invoke_method_table = new SymbolPropertyTable(_invoke_method_size);
1833
1834 // Allocate private object used as system class loader lock
1835 _system_loader_lock_obj = oopFactory::new_intArray(0, CHECK);
1836 // Initialize basic classes
1837 initialize_preloaded_classes(CHECK);
1838 }
1839
1840 // Compact table of directions on the initialization of klasses:
1841 static const short wk_init_info[] = {
1842 #define WK_KLASS_INIT_INFO(name, symbol, option) \
1843 ( ((int)vmSymbols::VM_SYMBOL_ENUM_NAME(symbol) \
1844 << SystemDictionary::CEIL_LG_OPTION_LIMIT) \
1845 | (int)SystemDictionary::option ),
1846 WK_KLASSES_DO(WK_KLASS_INIT_INFO)
1847 #undef WK_KLASS_INIT_INFO
1848 0
1849 };
1850
1851 bool SystemDictionary::initialize_wk_klass(WKID id, int init_opt, TRAPS) {
1852 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1853 int info = wk_init_info[id - FIRST_WKID];
1854 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1855 Symbol* symbol = vmSymbols::symbol_at((vmSymbols::SID)sid);
1856 InstanceKlass** klassp = &_well_known_klasses[id];
1857 bool must_load = (init_opt < SystemDictionary::Opt);
1858 if ((*klassp) == NULL) {
1859 Klass* k;
1860 if (must_load) {
1861 k = resolve_or_fail(symbol, true, CHECK_0); // load required class
1862 } else {
1863 k = resolve_or_null(symbol, CHECK_0); // load optional klass
1864 }
1865 (*klassp) = (k == NULL) ? NULL : InstanceKlass::cast(k);
1866 }
1867 return ((*klassp) != NULL);
1868 }
1869
1870 void SystemDictionary::initialize_wk_klasses_until(WKID limit_id, WKID &start_id, TRAPS) {
1871 assert((int)start_id <= (int)limit_id, "IDs are out of order!");
1872 for (int id = (int)start_id; id < (int)limit_id; id++) {
1873 assert(id >= (int)FIRST_WKID && id < (int)WKID_LIMIT, "oob");
1874 int info = wk_init_info[id - FIRST_WKID];
1875 int sid = (info >> CEIL_LG_OPTION_LIMIT);
1876 int opt = (info & right_n_bits(CEIL_LG_OPTION_LIMIT));
1877
1878 initialize_wk_klass((WKID)id, opt, CHECK);
1879 }
1880
1881 // move the starting value forward to the limit:
1882 start_id = limit_id;
1883 }
1884
1885 void SystemDictionary::initialize_preloaded_classes(TRAPS) {
1886 assert(WK_KLASS(Object_klass) == NULL, "preloaded classes should only be initialized once");
1887 // Preload commonly used klasses
1888 WKID scan = FIRST_WKID;
1889 // first do Object, then String, Class
1890 if (UseSharedSpaces) {
1891 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Object_klass), scan, CHECK);
1892 // Initialize the constant pool for the Object_class
1893 InstanceKlass* ik = InstanceKlass::cast(Object_klass());
1894 ik->constants()->restore_unshareable_info(CHECK);
1895 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1896 } else {
1897 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Class_klass), scan, CHECK);
1898 }
1899
1900 // Calculate offsets for String and Class classes since they are loaded and
1901 // can be used after this point.
1902 java_lang_String::compute_offsets();
1903 java_lang_Class::compute_offsets();
1904
1905 // Fixup mirrors for classes loaded before java.lang.Class.
1906 // These calls iterate over the objects currently in the perm gen
1907 // so calling them at this point is matters (not before when there
1908 // are fewer objects and not later after there are more objects
1909 // in the perm gen.
1910 Universe::initialize_basic_type_mirrors(CHECK);
1911 Universe::fixup_mirrors(CHECK);
1912
1913 // do a bunch more:
1914 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Reference_klass), scan, CHECK);
1915
1916 // Preload ref klasses and set reference types
1917 InstanceKlass::cast(WK_KLASS(Reference_klass))->set_reference_type(REF_OTHER);
1918 InstanceRefKlass::update_nonstatic_oop_maps(WK_KLASS(Reference_klass));
1919
1920 initialize_wk_klasses_through(WK_KLASS_ENUM_NAME(Cleaner_klass), scan, CHECK);
1921 InstanceKlass::cast(WK_KLASS(SoftReference_klass))->set_reference_type(REF_SOFT);
1922 InstanceKlass::cast(WK_KLASS(WeakReference_klass))->set_reference_type(REF_WEAK);
1923 InstanceKlass::cast(WK_KLASS(FinalReference_klass))->set_reference_type(REF_FINAL);
1924 InstanceKlass::cast(WK_KLASS(PhantomReference_klass))->set_reference_type(REF_PHANTOM);
1925 InstanceKlass::cast(WK_KLASS(Cleaner_klass))->set_reference_type(REF_CLEANER);
1926
1927 // JSR 292 classes
1928 WKID jsr292_group_start = WK_KLASS_ENUM_NAME(MethodHandle_klass);
1929 WKID jsr292_group_end = WK_KLASS_ENUM_NAME(VolatileCallSite_klass);
1930 initialize_wk_klasses_until(jsr292_group_start, scan, CHECK);
1931 initialize_wk_klasses_through(jsr292_group_end, scan, CHECK);
1932 initialize_wk_klasses_until(NOT_JVMCI(WKID_LIMIT) JVMCI_ONLY(FIRST_JVMCI_WKID), scan, CHECK);
1933
1934 _box_klasses[T_BOOLEAN] = WK_KLASS(Boolean_klass);
1935 _box_klasses[T_CHAR] = WK_KLASS(Character_klass);
1936 _box_klasses[T_FLOAT] = WK_KLASS(Float_klass);
1937 _box_klasses[T_DOUBLE] = WK_KLASS(Double_klass);
1938 _box_klasses[T_BYTE] = WK_KLASS(Byte_klass);
1939 _box_klasses[T_SHORT] = WK_KLASS(Short_klass);
1940 _box_klasses[T_INT] = WK_KLASS(Integer_klass);
1941 _box_klasses[T_LONG] = WK_KLASS(Long_klass);
1942 //_box_klasses[T_OBJECT] = WK_KLASS(object_klass);
1943 //_box_klasses[T_ARRAY] = WK_KLASS(object_klass);
1944
1945 { // Compute whether we should use loadClass or loadClassInternal when loading classes.
1946 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::loadClassInternal_name(), vmSymbols::string_class_signature());
1947 _has_loadClassInternal = (method != NULL);
1948 }
1949 { // Compute whether we should use checkPackageAccess or NOT
1950 Method* method = InstanceKlass::cast(ClassLoader_klass())->find_method(vmSymbols::checkPackageAccess_name(), vmSymbols::class_protectiondomain_signature());
1951 _has_checkPackageAccess = (method != NULL);
1952 }
1953 }
1954
1955 // Tells if a given klass is a box (wrapper class, such as java.lang.Integer).
1956 // If so, returns the basic type it holds. If not, returns T_OBJECT.
1957 BasicType SystemDictionary::box_klass_type(Klass* k) {
1958 assert(k != NULL, "");
1959 for (int i = T_BOOLEAN; i < T_VOID+1; i++) {
1960 if (_box_klasses[i] == k)
1961 return (BasicType)i;
1962 }
1963 return T_OBJECT;
1964 }
1965
1966 // Constraints on class loaders. The details of the algorithm can be
1967 // found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1968 // Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1969 // that the system dictionary needs to maintain a set of contraints that
1970 // must be satisfied by all classes in the dictionary.
1971 // if defining is true, then LinkageError if already in systemDictionary
1972 // if initiating loader, then ok if InstanceKlass matches existing entry
1973
1974 void SystemDictionary::check_constraints(int d_index, unsigned int d_hash,
1975 instanceKlassHandle k,
1976 Handle class_loader, bool defining,
1977 TRAPS) {
1978 const char *linkage_error1 = NULL;
1979 const char *linkage_error2 = NULL;
1980 {
1981 Symbol* name = k->name();
1982 ClassLoaderData *loader_data = class_loader_data(class_loader);
1983
1984 MutexLocker mu(SystemDictionary_lock, THREAD);
1985
1986 Klass* check = find_class(d_index, d_hash, name, loader_data);
1987 if (check != (Klass*)NULL) {
1988 // if different InstanceKlass - duplicate class definition,
1989 // else - ok, class loaded by a different thread in parallel,
1990 // we should only have found it if it was done loading and ok to use
1991 // system dictionary only holds instance classes, placeholders
1992 // also holds array classes
1993
1994 assert(check->is_instance_klass(), "noninstance in systemdictionary");
1995 if ((defining == true) || (k() != check)) {
1996 linkage_error1 = "loader (instance of ";
1997 linkage_error2 = "): attempted duplicate class definition for name: \"";
1998 } else {
1999 return;
2000 }
2001 }
2002
2003 #ifdef ASSERT
2004 Symbol* ph_check = find_placeholder(name, loader_data);
2005 assert(ph_check == NULL || ph_check == name, "invalid symbol");
2006 #endif
2007
2008 if (linkage_error1 == NULL) {
2009 if (constraints()->check_or_update(k, class_loader, name) == false) {
2010 linkage_error1 = "loader constraint violation: loader (instance of ";
2011 linkage_error2 = ") previously initiated loading for a different type with name \"";
2012 }
2013 }
2014 }
2015
2016 // Throw error now if needed (cannot throw while holding
2017 // SystemDictionary_lock because of rank ordering)
2018
2019 if (linkage_error1) {
2020 ResourceMark rm(THREAD);
2021 const char* class_loader_name = loader_name(class_loader());
2022 char* type_name = k->name()->as_C_string();
2023 size_t buflen = strlen(linkage_error1) + strlen(class_loader_name) +
2024 strlen(linkage_error2) + strlen(type_name) + 2; // +2 for '"' and null byte.
2025 char* buf = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, buflen);
2026 jio_snprintf(buf, buflen, "%s%s%s%s\"", linkage_error1, class_loader_name, linkage_error2, type_name);
2027 THROW_MSG(vmSymbols::java_lang_LinkageError(), buf);
2028 }
2029 }
2030
2031
2032 // Update system dictionary - done after check_constraint and add_to_hierachy
2033 // have been called.
2034 void SystemDictionary::update_dictionary(int d_index, unsigned int d_hash,
2035 int p_index, unsigned int p_hash,
2036 instanceKlassHandle k,
2037 Handle class_loader,
2038 TRAPS) {
2039 // Compile_lock prevents systemDictionary updates during compilations
2040 assert_locked_or_safepoint(Compile_lock);
2041 Symbol* name = k->name();
2042 ClassLoaderData *loader_data = class_loader_data(class_loader);
2043
2044 {
2045 MutexLocker mu1(SystemDictionary_lock, THREAD);
2046
2047 // See whether biased locking is enabled and if so set it for this
2048 // klass.
2049 // Note that this must be done past the last potential blocking
2050 // point / safepoint. We enable biased locking lazily using a
2051 // VM_Operation to iterate the SystemDictionary and installing the
2052 // biasable mark word into each InstanceKlass's prototype header.
2053 // To avoid race conditions where we accidentally miss enabling the
2054 // optimization for one class in the process of being added to the
2055 // dictionary, we must not safepoint after the test of
2056 // BiasedLocking::enabled().
2057 if (UseBiasedLocking && BiasedLocking::enabled()) {
2058 // Set biased locking bit for all loaded classes; it will be
2059 // cleared if revocation occurs too often for this type
2060 // NOTE that we must only do this when the class is initally
2061 // defined, not each time it is referenced from a new class loader
2062 if (k->class_loader() == class_loader()) {
2063 k->set_prototype_header(markOopDesc::biased_locking_prototype());
2064 }
2065 }
2066
2067 // Make a new system dictionary entry.
2068 Klass* sd_check = find_class(d_index, d_hash, name, loader_data);
2069 if (sd_check == NULL) {
2070 dictionary()->add_klass(name, loader_data, k);
2071 notice_modification();
2072 }
2073 #ifdef ASSERT
2074 sd_check = find_class(d_index, d_hash, name, loader_data);
2075 assert (sd_check != NULL, "should have entry in system dictionary");
2076 // Note: there may be a placeholder entry: for circularity testing
2077 // or for parallel defines
2078 #endif
2079 SystemDictionary_lock->notify_all();
2080 }
2081 }
2082
2083
2084 // Try to find a class name using the loader constraints. The
2085 // loader constraints might know about a class that isn't fully loaded
2086 // yet and these will be ignored.
2087 Klass* SystemDictionary::find_constrained_instance_or_array_klass(
2088 Symbol* class_name, Handle class_loader, TRAPS) {
2089
2090 // First see if it has been loaded directly.
2091 // Force the protection domain to be null. (This removes protection checks.)
2092 Handle no_protection_domain;
2093 Klass* klass = find_instance_or_array_klass(class_name, class_loader,
2094 no_protection_domain, CHECK_NULL);
2095 if (klass != NULL)
2096 return klass;
2097
2098 // Now look to see if it has been loaded elsewhere, and is subject to
2099 // a loader constraint that would require this loader to return the
2100 // klass that is already loaded.
2101 if (FieldType::is_array(class_name)) {
2102 // For array classes, their Klass*s are not kept in the
2103 // constraint table. The element Klass*s are.
2104 FieldArrayInfo fd;
2105 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(NULL));
2106 if (t != T_OBJECT) {
2107 klass = Universe::typeArrayKlassObj(t);
2108 } else {
2109 MutexLocker mu(SystemDictionary_lock, THREAD);
2110 klass = constraints()->find_constrained_klass(fd.object_key(), class_loader);
2111 }
2112 // If element class already loaded, allocate array klass
2113 if (klass != NULL) {
2114 klass = klass->array_klass_or_null(fd.dimension());
2115 }
2116 } else {
2117 MutexLocker mu(SystemDictionary_lock, THREAD);
2118 // Non-array classes are easy: simply check the constraint table.
2119 klass = constraints()->find_constrained_klass(class_name, class_loader);
2120 }
2121
2122 return klass;
2123 }
2124
2125
2126 bool SystemDictionary::add_loader_constraint(Symbol* class_name,
2127 Handle class_loader1,
2128 Handle class_loader2,
2129 Thread* THREAD) {
2130 ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
2131 ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
2132
2133 Symbol* constraint_name = NULL;
2134 if (!FieldType::is_array(class_name)) {
2135 constraint_name = class_name;
2136 } else {
2137 // For array classes, their Klass*s are not kept in the
2138 // constraint table. The element classes are.
2139 FieldArrayInfo fd;
2140 BasicType t = FieldType::get_array_info(class_name, fd, CHECK_(false));
2141 // primitive types always pass
2142 if (t != T_OBJECT) {
2143 return true;
2144 } else {
2145 constraint_name = fd.object_key();
2146 }
2147 }
2148 unsigned int d_hash1 = dictionary()->compute_hash(constraint_name, loader_data1);
2149 int d_index1 = dictionary()->hash_to_index(d_hash1);
2150
2151 unsigned int d_hash2 = dictionary()->compute_hash(constraint_name, loader_data2);
2152 int d_index2 = dictionary()->hash_to_index(d_hash2);
2153 {
2154 MutexLocker mu_s(SystemDictionary_lock, THREAD);
2155
2156 // Better never do a GC while we're holding these oops
2157 No_Safepoint_Verifier nosafepoint;
2158
2159 Klass* klass1 = find_class(d_index1, d_hash1, constraint_name, loader_data1);
2160 Klass* klass2 = find_class(d_index2, d_hash2, constraint_name, loader_data2);
2161 return constraints()->add_entry(constraint_name, klass1, class_loader1,
2162 klass2, class_loader2);
2163 }
2164 }
2165
2166 // Add entry to resolution error table to record the error when the first
2167 // attempt to resolve a reference to a class has failed.
2168 void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
2169 Symbol* error, Symbol* message) {
2170 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2171 int index = resolution_errors()->hash_to_index(hash);
2172 {
2173 MutexLocker ml(SystemDictionary_lock, Thread::current());
2174 resolution_errors()->add_entry(index, hash, pool, which, error, message);
2175 }
2176 }
2177
2178 // Delete a resolution error for RedefineClasses for a constant pool is going away
2179 void SystemDictionary::delete_resolution_error(ConstantPool* pool) {
2180 resolution_errors()->delete_entry(pool);
2181 }
2182
2183 // Lookup resolution error table. Returns error if found, otherwise NULL.
2184 Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
2185 Symbol** message) {
2186 unsigned int hash = resolution_errors()->compute_hash(pool, which);
2187 int index = resolution_errors()->hash_to_index(hash);
2188 {
2189 MutexLocker ml(SystemDictionary_lock, Thread::current());
2190 ResolutionErrorEntry* entry = resolution_errors()->find_entry(index, hash, pool, which);
2191 if (entry != NULL) {
2192 *message = entry->message();
2193 return entry->error();
2194 } else {
2195 return NULL;
2196 }
2197 }
2198 }
2199
2200
2201 // Signature constraints ensure that callers and callees agree about
2202 // the meaning of type names in their signatures. This routine is the
2203 // intake for constraints. It collects them from several places:
2204 //
2205 // * LinkResolver::resolve_method (if check_access is true) requires
2206 // that the resolving class (the caller) and the defining class of
2207 // the resolved method (the callee) agree on each type in the
2208 // method's signature.
2209 //
2210 // * LinkResolver::resolve_interface_method performs exactly the same
2211 // checks.
2212 //
2213 // * LinkResolver::resolve_field requires that the constant pool
2214 // attempting to link to a field agree with the field's defining
2215 // class about the type of the field signature.
2216 //
2217 // * klassVtable::initialize_vtable requires that, when a class
2218 // overrides a vtable entry allocated by a superclass, that the
2219 // overriding method (i.e., the callee) agree with the superclass
2220 // on each type in the method's signature.
2221 //
2222 // * klassItable::initialize_itable requires that, when a class fills
2223 // in its itables, for each non-abstract method installed in an
2224 // itable, the method (i.e., the callee) agree with the interface
2225 // on each type in the method's signature.
2226 //
2227 // All those methods have a boolean (check_access, checkconstraints)
2228 // which turns off the checks. This is used from specialized contexts
2229 // such as bootstrapping, dumping, and debugging.
2230 //
2231 // No direct constraint is placed between the class and its
2232 // supertypes. Constraints are only placed along linked relations
2233 // between callers and callees. When a method overrides or implements
2234 // an abstract method in a supertype (superclass or interface), the
2235 // constraints are placed as if the supertype were the caller to the
2236 // overriding method. (This works well, since callers to the
2237 // supertype have already established agreement between themselves and
2238 // the supertype.) As a result of all this, a class can disagree with
2239 // its supertype about the meaning of a type name, as long as that
2240 // class neither calls a relevant method of the supertype, nor is
2241 // called (perhaps via an override) from the supertype.
2242 //
2243 //
2244 // SystemDictionary::check_signature_loaders(sig, l1, l2)
2245 //
2246 // Make sure all class components (including arrays) in the given
2247 // signature will be resolved to the same class in both loaders.
2248 // Returns the name of the type that failed a loader constraint check, or
2249 // NULL if no constraint failed. No exception except OOME is thrown.
2250 // Arrays are not added to the loader constraint table, their elements are.
2251 Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
2252 Handle loader1, Handle loader2,
2253 bool is_method, TRAPS) {
2254 // Nothing to do if loaders are the same.
2255 if (loader1() == loader2()) {
2256 return NULL;
2257 }
2258
2259 SignatureStream sig_strm(signature, is_method);
2260 while (!sig_strm.is_done()) {
2261 if (sig_strm.is_object()) {
2262 Symbol* sig = sig_strm.as_symbol(CHECK_NULL);
2263 if (!add_loader_constraint(sig, loader1, loader2, THREAD)) {
2264 return sig;
2265 }
2266 }
2267 sig_strm.next();
2268 }
2269 return NULL;
2270 }
2271
2272
2273 methodHandle SystemDictionary::find_method_handle_intrinsic(vmIntrinsics::ID iid,
2274 Symbol* signature,
2275 TRAPS) {
2276 methodHandle empty;
2277 assert(MethodHandles::is_signature_polymorphic(iid) &&
2278 MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
2279 iid != vmIntrinsics::_invokeGeneric,
2280 "must be a known MH intrinsic iid=%d: %s", iid, vmIntrinsics::name_at(iid));
2281
2282 unsigned int hash = invoke_method_table()->compute_hash(signature, iid);
2283 int index = invoke_method_table()->hash_to_index(hash);
2284 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2285 methodHandle m;
2286 if (spe == NULL || spe->method() == NULL) {
2287 spe = NULL;
2288 // Must create lots of stuff here, but outside of the SystemDictionary lock.
2289 m = Method::make_method_handle_intrinsic(iid, signature, CHECK_(empty));
2290 if (!Arguments::is_interpreter_only()) {
2291 // Generate a compiled form of the MH intrinsic.
2292 AdapterHandlerLibrary::create_native_wrapper(m);
2293 // Check if have the compiled code.
2294 if (!m->has_compiled_code()) {
2295 THROW_MSG_(vmSymbols::java_lang_VirtualMachineError(),
2296 "out of space in CodeCache for method handle intrinsic", empty);
2297 }
2298 }
2299 // Now grab the lock. We might have to throw away the new method,
2300 // if a racing thread has managed to install one at the same time.
2301 {
2302 MutexLocker ml(SystemDictionary_lock, THREAD);
2303 spe = invoke_method_table()->find_entry(index, hash, signature, iid);
2304 if (spe == NULL)
2305 spe = invoke_method_table()->add_entry(index, hash, signature, iid);
2306 if (spe->method() == NULL)
2307 spe->set_method(m());
2308 }
2309 }
2310
2311 assert(spe != NULL && spe->method() != NULL, "");
2312 assert(Arguments::is_interpreter_only() || (spe->method()->has_compiled_code() &&
2313 spe->method()->code()->entry_point() == spe->method()->from_compiled_entry()),
2314 "MH intrinsic invariant");
2315 return spe->method();
2316 }
2317
2318 // Helper for unpacking the return value from linkMethod and linkCallSite.
2319 static methodHandle unpack_method_and_appendix(Handle mname,
2320 KlassHandle accessing_klass,
2321 objArrayHandle appendix_box,
2322 Handle* appendix_result,
2323 TRAPS) {
2324 methodHandle empty;
2325 if (mname.not_null()) {
2326 Metadata* vmtarget = java_lang_invoke_MemberName::vmtarget(mname());
2327 if (vmtarget != NULL && vmtarget->is_method()) {
2328 Method* m = (Method*)vmtarget;
2329 oop appendix = appendix_box->obj_at(0);
2330 if (TraceMethodHandles) {
2331 #ifndef PRODUCT
2332 tty->print("Linked method=" INTPTR_FORMAT ": ", p2i(m));
2333 m->print();
2334 if (appendix != NULL) { tty->print("appendix = "); appendix->print(); }
2335 tty->cr();
2336 #endif //PRODUCT
2337 }
2338 (*appendix_result) = Handle(THREAD, appendix);
2339 // the target is stored in the cpCache and if a reference to this
2340 // MethodName is dropped we need a way to make sure the
2341 // class_loader containing this method is kept alive.
2342 // FIXME: the appendix might also preserve this dependency.
2343 ClassLoaderData* this_key = InstanceKlass::cast(accessing_klass())->class_loader_data();
2344 this_key->record_dependency(m->method_holder(), CHECK_NULL); // Can throw OOM
2345 return methodHandle(THREAD, m);
2346 }
2347 }
2348 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives", empty);
2349 return empty;
2350 }
2351
2352 methodHandle SystemDictionary::find_method_handle_invoker(Symbol* name,
2353 Symbol* signature,
2354 KlassHandle accessing_klass,
2355 Handle *appendix_result,
2356 Handle *method_type_result,
2357 TRAPS) {
2358 methodHandle empty;
2359 assert(THREAD->can_call_java() ,"");
2360 Handle method_type =
2361 SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_(empty));
2362
2363 KlassHandle mh_klass = SystemDictionary::MethodHandle_klass();
2364 int ref_kind = JVM_REF_invokeVirtual;
2365 Handle name_str = StringTable::intern(name, CHECK_(empty));
2366 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2367 assert(appendix_box->obj_at(0) == NULL, "");
2368
2369 // This should not happen. JDK code should take care of that.
2370 if (accessing_klass.is_null() || method_type.is_null()) {
2371 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokehandle", empty);
2372 }
2373
2374 // call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2375 JavaCallArguments args;
2376 args.push_oop(accessing_klass()->java_mirror());
2377 args.push_int(ref_kind);
2378 args.push_oop(mh_klass()->java_mirror());
2379 args.push_oop(name_str());
2380 args.push_oop(method_type());
2381 args.push_oop(appendix_box());
2382 JavaValue result(T_OBJECT);
2383 JavaCalls::call_static(&result,
2384 SystemDictionary::MethodHandleNatives_klass(),
2385 vmSymbols::linkMethod_name(),
2386 vmSymbols::linkMethod_signature(),
2387 &args, CHECK_(empty));
2388 Handle mname(THREAD, (oop) result.get_jobject());
2389 (*method_type_result) = method_type;
2390 return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2391 }
2392
2393 // Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2394 // We must ensure that all class loaders everywhere will reach this class, for any client.
2395 // This is a safe bet for public classes in java.lang, such as Object and String.
2396 // We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2397 // Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2398 static bool is_always_visible_class(oop mirror) {
2399 Klass* klass = java_lang_Class::as_Klass(mirror);
2400 if (klass->is_objArray_klass()) {
2401 klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2402 }
2403 if (klass->is_typeArray_klass()) {
2404 return true; // primitive array
2405 }
2406 assert(klass->is_instance_klass(), "%s", klass->external_name());
2407 return klass->is_public() &&
2408 (InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::Object_klass()) || // java.lang
2409 InstanceKlass::cast(klass)->is_same_class_package(SystemDictionary::MethodHandle_klass())); // java.lang.invoke
2410 }
2411
2412 // Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2413 // signature, as interpreted relative to the given class loader.
2414 // Because of class loader constraints, all method handle usage must be
2415 // consistent with this loader.
2416 Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2417 KlassHandle accessing_klass,
2418 TRAPS) {
2419 Handle empty;
2420 vmIntrinsics::ID null_iid = vmIntrinsics::_none; // distinct from all method handle invoker intrinsics
2421 unsigned int hash = invoke_method_table()->compute_hash(signature, null_iid);
2422 int index = invoke_method_table()->hash_to_index(hash);
2423 SymbolPropertyEntry* spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2424 if (spe != NULL && spe->method_type() != NULL) {
2425 assert(java_lang_invoke_MethodType::is_instance(spe->method_type()), "");
2426 return Handle(THREAD, spe->method_type());
2427 } else if (!THREAD->can_call_java()) {
2428 warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME
2429 return Handle(); // do not attempt from within compiler, unless it was cached
2430 }
2431
2432 Handle class_loader, protection_domain;
2433 if (accessing_klass.not_null()) {
2434 class_loader = Handle(THREAD, InstanceKlass::cast(accessing_klass())->class_loader());
2435 protection_domain = Handle(THREAD, InstanceKlass::cast(accessing_klass())->protection_domain());
2436 }
2437 bool can_be_cached = true;
2438 int npts = ArgumentCount(signature).size();
2439 objArrayHandle pts = oopFactory::new_objArray(SystemDictionary::Class_klass(), npts, CHECK_(empty));
2440 int arg = 0;
2441 Handle rt; // the return type from the signature
2442 ResourceMark rm(THREAD);
2443 for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {
2444 oop mirror = NULL;
2445 if (can_be_cached) {
2446 // Use neutral class loader to lookup candidate classes to be placed in the cache.
2447 mirror = ss.as_java_mirror(Handle(), Handle(),
2448 SignatureStream::ReturnNull, CHECK_(empty));
2449 if (mirror == NULL || (ss.is_object() && !is_always_visible_class(mirror))) {
2450 // Fall back to accessing_klass context.
2451 can_be_cached = false;
2452 }
2453 }
2454 if (!can_be_cached) {
2455 // Resolve, throwing a real error if it doesn't work.
2456 mirror = ss.as_java_mirror(class_loader, protection_domain,
2457 SignatureStream::NCDFError, CHECK_(empty));
2458 }
2459 assert(!oopDesc::is_null(mirror), "%s", ss.as_symbol(THREAD)->as_C_string());
2460 if (ss.at_return_type())
2461 rt = Handle(THREAD, mirror);
2462 else
2463 pts->obj_at_put(arg++, mirror);
2464
2465 // Check accessibility.
2466 if (ss.is_object() && accessing_klass.not_null()) {
2467 Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2468 mirror = NULL; // safety
2469 // Emulate ConstantPool::verify_constant_pool_resolve.
2470 if (sel_klass->is_objArray_klass())
2471 sel_klass = ObjArrayKlass::cast(sel_klass)->bottom_klass();
2472 if (sel_klass->is_instance_klass()) {
2473 KlassHandle sel_kh(THREAD, sel_klass);
2474 LinkResolver::check_klass_accessability(accessing_klass, sel_kh, CHECK_(empty));
2475 }
2476 }
2477 }
2478 assert(arg == npts, "");
2479
2480 // call java.lang.invoke.MethodHandleNatives::findMethodType(Class rt, Class[] pts) -> MethodType
2481 JavaCallArguments args(Handle(THREAD, rt()));
2482 args.push_oop(pts());
2483 JavaValue result(T_OBJECT);
2484 JavaCalls::call_static(&result,
2485 SystemDictionary::MethodHandleNatives_klass(),
2486 vmSymbols::findMethodHandleType_name(),
2487 vmSymbols::findMethodHandleType_signature(),
2488 &args, CHECK_(empty));
2489 Handle method_type(THREAD, (oop) result.get_jobject());
2490
2491 if (can_be_cached) {
2492 // We can cache this MethodType inside the JVM.
2493 MutexLocker ml(SystemDictionary_lock, THREAD);
2494 spe = invoke_method_table()->find_entry(index, hash, signature, null_iid);
2495 if (spe == NULL)
2496 spe = invoke_method_table()->add_entry(index, hash, signature, null_iid);
2497 if (spe->method_type() == NULL) {
2498 spe->set_method_type(method_type());
2499 }
2500 }
2501
2502 // report back to the caller with the MethodType
2503 return method_type;
2504 }
2505
2506 // Ask Java code to find or construct a method handle constant.
2507 Handle SystemDictionary::link_method_handle_constant(KlassHandle caller,
2508 int ref_kind, //e.g., JVM_REF_invokeVirtual
2509 KlassHandle callee,
2510 Symbol* name_sym,
2511 Symbol* signature,
2512 TRAPS) {
2513 Handle empty;
2514 Handle name = java_lang_String::create_from_symbol(name_sym, CHECK_(empty));
2515 Handle type;
2516 if (signature->utf8_length() > 0 && signature->byte_at(0) == '(') {
2517 type = find_method_handle_type(signature, caller, CHECK_(empty));
2518 } else if (caller.is_null()) {
2519 // This should not happen. JDK code should take care of that.
2520 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2521 } else {
2522 ResourceMark rm(THREAD);
2523 SignatureStream ss(signature, false);
2524 if (!ss.is_done()) {
2525 oop mirror = ss.as_java_mirror(caller->class_loader(), caller->protection_domain(),
2526 SignatureStream::NCDFError, CHECK_(empty));
2527 type = Handle(THREAD, mirror);
2528 ss.next();
2529 if (!ss.is_done()) type = Handle(); // error!
2530 }
2531 }
2532 if (type.is_null()) {
2533 THROW_MSG_(vmSymbols::java_lang_LinkageError(), "bad signature", empty);
2534 }
2535
2536 // call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2537 JavaCallArguments args;
2538 args.push_oop(caller->java_mirror()); // the referring class
2539 args.push_int(ref_kind);
2540 args.push_oop(callee->java_mirror()); // the target class
2541 args.push_oop(name());
2542 args.push_oop(type());
2543 JavaValue result(T_OBJECT);
2544 JavaCalls::call_static(&result,
2545 SystemDictionary::MethodHandleNatives_klass(),
2546 vmSymbols::linkMethodHandleConstant_name(),
2547 vmSymbols::linkMethodHandleConstant_signature(),
2548 &args, CHECK_(empty));
2549 return Handle(THREAD, (oop) result.get_jobject());
2550 }
2551
2552 // Ask Java code to find or construct a java.lang.invoke.CallSite for the given
2553 // name and signature, as interpreted relative to the given class loader.
2554 methodHandle SystemDictionary::find_dynamic_call_site_invoker(KlassHandle caller,
2555 Handle bootstrap_specifier,
2556 Symbol* name,
2557 Symbol* type,
2558 Handle *appendix_result,
2559 Handle *method_type_result,
2560 TRAPS) {
2561 methodHandle empty;
2562 Handle bsm, info;
2563 if (java_lang_invoke_MethodHandle::is_instance(bootstrap_specifier())) {
2564 bsm = bootstrap_specifier;
2565 } else {
2566 assert(bootstrap_specifier->is_objArray(), "");
2567 objArrayHandle args(THREAD, (objArrayOop) bootstrap_specifier());
2568 int len = args->length();
2569 assert(len >= 1, "");
2570 bsm = Handle(THREAD, args->obj_at(0));
2571 if (len > 1) {
2572 objArrayOop args1 = oopFactory::new_objArray(SystemDictionary::Object_klass(), len-1, CHECK_(empty));
2573 for (int i = 1; i < len; i++)
2574 args1->obj_at_put(i-1, args->obj_at(i));
2575 info = Handle(THREAD, args1);
2576 }
2577 }
2578 guarantee(java_lang_invoke_MethodHandle::is_instance(bsm()),
2579 "caller must supply a valid BSM");
2580
2581 Handle method_name = java_lang_String::create_from_symbol(name, CHECK_(empty));
2582 Handle method_type = find_method_handle_type(type, caller, CHECK_(empty));
2583
2584 // This should not happen. JDK code should take care of that.
2585 if (caller.is_null() || method_type.is_null()) {
2586 THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad invokedynamic", empty);
2587 }
2588
2589 objArrayHandle appendix_box = oopFactory::new_objArray(SystemDictionary::Object_klass(), 1, CHECK_(empty));
2590 assert(appendix_box->obj_at(0) == NULL, "");
2591
2592 // call java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2593 JavaCallArguments args;
2594 args.push_oop(caller->java_mirror());
2595 args.push_oop(bsm());
2596 args.push_oop(method_name());
2597 args.push_oop(method_type());
2598 args.push_oop(info());
2599 args.push_oop(appendix_box);
2600 JavaValue result(T_OBJECT);
2601 JavaCalls::call_static(&result,
2602 SystemDictionary::MethodHandleNatives_klass(),
2603 vmSymbols::linkCallSite_name(),
2604 vmSymbols::linkCallSite_signature(),
2605 &args, CHECK_(empty));
2606 Handle mname(THREAD, (oop) result.get_jobject());
2607 (*method_type_result) = method_type;
2608 return unpack_method_and_appendix(mname, caller, appendix_box, appendix_result, THREAD);
2609 }
2610
2611 // Since the identity hash code for symbols changes when the symbols are
2612 // moved from the regular perm gen (hash in the mark word) to the shared
2613 // spaces (hash is the address), the classes loaded into the dictionary
2614 // may be in the wrong buckets.
2615
2616 void SystemDictionary::reorder_dictionary() {
2617 dictionary()->reorder_dictionary();
2618 }
2619
2620
2621 void SystemDictionary::copy_buckets(char** top, char* end) {
2622 dictionary()->copy_buckets(top, end);
2623 }
2624
2625
2626 void SystemDictionary::copy_table(char** top, char* end) {
2627 dictionary()->copy_table(top, end);
2628 }
2629
2630
2631 void SystemDictionary::reverse() {
2632 dictionary()->reverse();
2633 }
2634
2635 int SystemDictionary::number_of_classes() {
2636 return dictionary()->number_of_entries();
2637 }
2638
2639
2640 // ----------------------------------------------------------------------------
2641 void SystemDictionary::print_shared(bool details) {
2642 shared_dictionary()->print(details);
2643 }
2644
2645 void SystemDictionary::print(bool details) {
2646 dictionary()->print(details);
2647
2648 // Placeholders
2649 GCMutexLocker mu(SystemDictionary_lock);
2650 placeholders()->print();
2651
2652 // loader constraints - print under SD_lock
2653 constraints()->print();
2654 }
2655
2656
2657 void SystemDictionary::verify() {
2658 guarantee(dictionary() != NULL, "Verify of system dictionary failed");
2659 guarantee(constraints() != NULL,
2660 "Verify of loader constraints failed");
2661 guarantee(dictionary()->number_of_entries() >= 0 &&
2662 placeholders()->number_of_entries() >= 0,
2663 "Verify of system dictionary failed");
2664
2665 // Verify dictionary
2666 dictionary()->verify();
2667
2668 GCMutexLocker mu(SystemDictionary_lock);
2669 placeholders()->verify();
2670
2671 // Verify constraint table
2672 guarantee(constraints() != NULL, "Verify of loader constraints failed");
2673 constraints()->verify(dictionary(), placeholders());
2674 }
2675
2676 // utility function for class load event
2677 void SystemDictionary::post_class_load_event(const Ticks& start_time,
2678 instanceKlassHandle k,
2679 Handle initiating_loader) {
2680 #if INCLUDE_TRACE
2681 EventClassLoad event(UNTIMED);
2682 if (event.should_commit()) {
2683 event.set_starttime(start_time);
2684 event.set_loadedClass(k());
2685 oop defining_class_loader = k->class_loader();
2686 event.set_definingClassLoader(defining_class_loader != NULL ?
2687 defining_class_loader->klass() : (Klass*)NULL);
2688 oop class_loader = initiating_loader.is_null() ? (oop)NULL : initiating_loader();
2689 event.set_initiatingClassLoader(class_loader != NULL ?
2690 class_loader->klass() : (Klass*)NULL);
2691 event.commit();
2692 }
2693 #endif // INCLUDE_TRACE
2694 }
2695