2
* Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5
* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
7
* published by the Free Software Foundation.
9
* This code is distributed in the hope that it will be useful, but WITHOUT
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* 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).
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.
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
25
#include "precompiled.hpp"
26
#include "cds/cdsConfig.hpp"
27
#include "cds/heapShared.hpp"
28
#include "classfile/classFileParser.hpp"
29
#include "classfile/classFileStream.hpp"
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#include "classfile/classLoader.hpp"
31
#include "classfile/classLoaderData.inline.hpp"
32
#include "classfile/classLoaderDataGraph.inline.hpp"
33
#include "classfile/classLoaderExt.hpp"
34
#include "classfile/classLoadInfo.hpp"
35
#include "classfile/dictionary.hpp"
36
#include "classfile/javaClasses.inline.hpp"
37
#include "classfile/klassFactory.hpp"
38
#include "classfile/loaderConstraints.hpp"
39
#include "classfile/packageEntry.hpp"
40
#include "classfile/placeholders.hpp"
41
#include "classfile/protectionDomainCache.hpp"
42
#include "classfile/resolutionErrors.hpp"
43
#include "classfile/stringTable.hpp"
44
#include "classfile/symbolTable.hpp"
45
#include "classfile/systemDictionary.hpp"
46
#include "classfile/vmClasses.hpp"
47
#include "classfile/vmSymbols.hpp"
48
#include "gc/shared/gcTraceTime.inline.hpp"
49
#include "interpreter/bootstrapInfo.hpp"
50
#include "jfr/jfrEvents.hpp"
52
#include "logging/log.hpp"
53
#include "logging/logStream.hpp"
54
#include "memory/metaspaceClosure.hpp"
55
#include "memory/oopFactory.hpp"
56
#include "memory/resourceArea.hpp"
57
#include "memory/universe.hpp"
58
#include "oops/access.inline.hpp"
59
#include "oops/instanceKlass.hpp"
60
#include "oops/klass.inline.hpp"
61
#include "oops/method.inline.hpp"
62
#include "oops/objArrayKlass.hpp"
63
#include "oops/objArrayOop.inline.hpp"
64
#include "oops/oop.inline.hpp"
65
#include "oops/oop.hpp"
66
#include "oops/oopHandle.hpp"
67
#include "oops/oopHandle.inline.hpp"
68
#include "oops/symbol.hpp"
69
#include "oops/typeArrayKlass.hpp"
70
#include "prims/jvmtiExport.hpp"
71
#include "prims/methodHandles.hpp"
72
#include "runtime/arguments.hpp"
73
#include "runtime/atomic.hpp"
74
#include "runtime/handles.inline.hpp"
75
#include "runtime/java.hpp"
76
#include "runtime/javaCalls.hpp"
77
#include "runtime/mutexLocker.hpp"
78
#include "runtime/sharedRuntime.hpp"
79
#include "runtime/signature.hpp"
80
#include "runtime/synchronizer.hpp"
81
#include "services/classLoadingService.hpp"
82
#include "services/diagnosticCommand.hpp"
83
#include "services/finalizerService.hpp"
84
#include "services/threadService.hpp"
85
#include "utilities/macros.hpp"
86
#include "utilities/utf8.hpp"
88
#include "classfile/systemDictionaryShared.hpp"
94
class InvokeMethodKey : public StackObj {100
InvokeMethodKey(Symbol* symbol, intptr_t iid) :
104
static bool key_comparison(InvokeMethodKey const &k1, InvokeMethodKey const &k2){105
return k1._symbol == k2._symbol && k1._iid == k2._iid;
108
static unsigned int compute_hash(const InvokeMethodKey &k) {109
Symbol* sym = k._symbol;
110
intptr_t iid = k._iid;
111
unsigned int hash = (unsigned int) sym -> identity_hash();
112
return (unsigned int) (hash ^ iid);
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using InvokeMethodIntrinsicTable = ResourceHashtable<InvokeMethodKey, Method*, 139, AnyObj::C_HEAP, mtClass,
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InvokeMethodKey::compute_hash, InvokeMethodKey::key_comparison>;
119
static InvokeMethodIntrinsicTable* _invoke_method_intrinsic_table;
120
using InvokeMethodTypeTable = ResourceHashtable<SymbolHandle, OopHandle, 139, AnyObj::C_HEAP, mtClass, SymbolHandle::compute_hash>;
121
static InvokeMethodTypeTable* _invoke_method_type_table;
123
OopHandle SystemDictionary::_java_system_loader;
124
OopHandle SystemDictionary::_java_platform_loader;
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// ----------------------------------------------------------------------------
127
// Java-level SystemLoader and PlatformLoader
128
oop SystemDictionary::java_system_loader() {129
return _java_system_loader.resolve();
132
oop SystemDictionary::java_platform_loader() {133
return _java_platform_loader.resolve();
136
void SystemDictionary::compute_java_loaders(TRAPS) {137
if (_java_system_loader.is_empty()) {138
oop system_loader = get_system_class_loader_impl(CHECK);
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_java_system_loader = OopHandle(Universe::vm_global(), system_loader);
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// It must have been restored from the archived module graph
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assert(CDSConfig::is_using_archive(), "must be");
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assert(CDSConfig::is_using_full_module_graph(), "must be");
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oop system_loader = get_system_class_loader_impl(CHECK);
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assert(_java_system_loader.resolve() == system_loader, "must be");
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if (_java_platform_loader.is_empty()) {151
oop platform_loader = get_platform_class_loader_impl(CHECK);
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_java_platform_loader = OopHandle(Universe::vm_global(), platform_loader);
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// It must have been restored from the archived module graph
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assert(CDSConfig::is_using_archive(), "must be");
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assert(CDSConfig::is_using_full_module_graph(), "must be");
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oop platform_loader = get_platform_class_loader_impl(CHECK);
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assert(_java_platform_loader.resolve() == platform_loader, "must be");
164
oop SystemDictionary::get_system_class_loader_impl(TRAPS) {165
JavaValue result(T_OBJECT);
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InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
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JavaCalls::call_static(&result,
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vmSymbols::getSystemClassLoader_name(),
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vmSymbols::void_classloader_signature(),
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return result.get_oop();
175
oop SystemDictionary::get_platform_class_loader_impl(TRAPS) {176
JavaValue result(T_OBJECT);
177
InstanceKlass* class_loader_klass = vmClasses::ClassLoader_klass();
178
JavaCalls::call_static(&result,
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vmSymbols::getPlatformClassLoader_name(),
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vmSymbols::void_classloader_signature(),
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return result.get_oop();
187
inline ClassLoaderData* class_loader_data(Handle class_loader) {188
return ClassLoaderData::class_loader_data(class_loader());
191
ClassLoaderData* SystemDictionary::register_loader(Handle class_loader, bool create_mirror_cld) {192
if (create_mirror_cld) {193
// Add a new class loader data to the graph.
194
return ClassLoaderDataGraph::add(class_loader, true);
196
return (class_loader() == nullptr) ? ClassLoaderData::the_null_class_loader_data() :
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ClassLoaderDataGraph::find_or_create(class_loader);
201
void SystemDictionary::set_system_loader(ClassLoaderData *cld) {202
assert(_java_system_loader.is_empty(), "already set!");
203
_java_system_loader = cld->class_loader_handle();
207
void SystemDictionary::set_platform_loader(ClassLoaderData *cld) {208
assert(_java_platform_loader.is_empty(), "already set!");
209
_java_platform_loader = cld->class_loader_handle();
212
// ----------------------------------------------------------------------------
213
// Parallel class loading check
215
static bool is_parallelCapable(Handle class_loader) {216
if (class_loader.is_null()) return true;
217
return java_lang_ClassLoader::parallelCapable(class_loader());
219
// ----------------------------------------------------------------------------
220
// ParallelDefineClass flag does not apply to bootclass loader
221
static bool is_parallelDefine(Handle class_loader) {222
if (class_loader.is_null()) return false;
223
if (AllowParallelDefineClass && java_lang_ClassLoader::parallelCapable(class_loader())) {229
// Returns true if the passed class loader is the builtin application class loader
230
// or a custom system class loader. A customer system class loader can be
231
// specified via -Djava.system.class.loader.
232
bool SystemDictionary::is_system_class_loader(oop class_loader) {233
if (class_loader == nullptr) {236
return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_AppClassLoader_klass() ||
237
class_loader == _java_system_loader.peek());
240
// Returns true if the passed class loader is the platform class loader.
241
bool SystemDictionary::is_platform_class_loader(oop class_loader) {242
if (class_loader == nullptr) {245
return (class_loader->klass() == vmClasses::jdk_internal_loader_ClassLoaders_PlatformClassLoader_klass());
248
Handle SystemDictionary::get_loader_lock_or_null(Handle class_loader) {249
// If class_loader is null or parallelCapable, the JVM doesn't acquire a lock while loading.
250
if (is_parallelCapable(class_loader)) {257
// ----------------------------------------------------------------------------
258
// Resolving of classes
260
Symbol* SystemDictionary::class_name_symbol(const char* name, Symbol* exception, TRAPS) {261
if (name == nullptr) {262
THROW_MSG_0(exception, "No class name given");
264
if ((int)strlen(name) > Symbol::max_length()) {265
// It's impossible to create this class; the name cannot fit
266
// into the constant pool.
267
Exceptions::fthrow(THREAD_AND_LOCATION, exception,
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"Class name exceeds maximum length of %d: %s",
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Symbol::max_length(),
273
// Callers should ensure that the name is never an illegal UTF8 string.
274
assert(UTF8::is_legal_utf8((const unsigned char*)name, (int)strlen(name), false),
275
"Class name is not a valid utf8 string.");
277
// Make a new symbol for the class name.
278
return SymbolTable::new_symbol(name);
282
// Used to verify that class loading succeeded in adding k to the dictionary.
283
static void verify_dictionary_entry(Symbol* class_name, InstanceKlass* k) {284
MutexLocker mu(SystemDictionary_lock);
285
ClassLoaderData* loader_data = k->class_loader_data();
286
Dictionary* dictionary = loader_data->dictionary();
287
assert(class_name == k->name(), "Must be the same");
288
InstanceKlass* kk = dictionary->find_class(JavaThread::current(), class_name);
289
assert(kk == k, "should be present in dictionary");
293
static void handle_resolution_exception(Symbol* class_name, bool throw_error, TRAPS) {294
if (HAS_PENDING_EXCEPTION) {295
// If we have a pending exception we forward it to the caller, unless throw_error is true,
296
// in which case we have to check whether the pending exception is a ClassNotFoundException,
297
// and convert it to a NoClassDefFoundError and chain the original ClassNotFoundException.
298
if (throw_error && PENDING_EXCEPTION->is_a(vmClasses::ClassNotFoundException_klass())) {299
ResourceMark rm(THREAD);
300
Handle e(THREAD, PENDING_EXCEPTION);
301
CLEAR_PENDING_EXCEPTION;
302
THROW_MSG_CAUSE(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string(), e);
304
return; // the caller will throw the incoming exception
307
// If the class is not found, ie, caller has checked that klass is null, throw the appropriate
308
// error or exception depending on the value of throw_error.
309
ResourceMark rm(THREAD);
311
THROW_MSG(vmSymbols::java_lang_NoClassDefFoundError(), class_name->as_C_string());
313
THROW_MSG(vmSymbols::java_lang_ClassNotFoundException(), class_name->as_C_string());
317
// Forwards to resolve_or_null
319
Klass* SystemDictionary::resolve_or_fail(Symbol* class_name, Handle class_loader, Handle protection_domain,
320
bool throw_error, TRAPS) {321
Klass* klass = resolve_or_null(class_name, class_loader, protection_domain, THREAD);
322
// Check for pending exception or null klass, and throw exception
323
if (HAS_PENDING_EXCEPTION || klass == nullptr) {324
handle_resolution_exception(class_name, throw_error, CHECK_NULL);
329
// Forwards to resolve_array_class_or_null or resolve_instance_class_or_null
331
Klass* SystemDictionary::resolve_or_null(Symbol* class_name, Handle class_loader, Handle protection_domain, TRAPS) {332
if (Signature::is_array(class_name)) {333
return resolve_array_class_or_null(class_name, class_loader, protection_domain, THREAD);
335
assert(class_name != nullptr && !Signature::is_array(class_name), "must be");
336
if (Signature::has_envelope(class_name)) {337
ResourceMark rm(THREAD);
338
// Ignore wrapping L and ;.
339
TempNewSymbol name = SymbolTable::new_symbol(class_name->as_C_string() + 1,
340
class_name->utf8_length() - 2);
341
return resolve_instance_class_or_null(name, class_loader, protection_domain, THREAD);
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return resolve_instance_class_or_null(class_name, class_loader, protection_domain, THREAD);
348
// Forwards to resolve_instance_class_or_null
350
Klass* SystemDictionary::resolve_array_class_or_null(Symbol* class_name,
352
Handle protection_domain,
354
assert(Signature::is_array(class_name), "must be array");
355
ResourceMark rm(THREAD);
356
SignatureStream ss(class_name, false);
357
int ndims = ss.skip_array_prefix(); // skip all '['s
359
BasicType t = ss.type();
360
if (ss.has_envelope()) {361
Symbol* obj_class = ss.as_symbol();
362
k = SystemDictionary::resolve_instance_class_or_null(obj_class,
367
k = k->array_klass(ndims, CHECK_NULL);
370
k = Universe::typeArrayKlass(t);
371
k = k->array_klass(ndims, CHECK_NULL);
376
static inline void log_circularity_error(Symbol* name, PlaceholderEntry* probe) {377
LogTarget(Debug, class, load, placeholders) lt;
378
if (lt.is_enabled()) {381
ls.print("ClassCircularityError detected for placeholder entry %s", name->as_C_string());382
probe->print_on(&ls);
387
// Must be called for any superclass or superinterface resolution
388
// during class definition to allow class circularity checking
389
// superinterface callers:
390
// parse_interfaces - from defineClass
391
// superclass callers:
392
// ClassFileParser - from defineClass
393
// load_shared_class - while loading a class from shared archive
394
// resolve_instance_class_or_null:
395
// via: handle_parallel_super_load
396
// when resolving a class that has an existing placeholder with
397
// a saved superclass [i.e. a defineClass is currently in progress]
398
// If another thread is trying to resolve the class, it must do
399
// superclass checks on its own thread to catch class circularity and
402
// resolve_super_or_fail adds a LOAD_SUPER placeholder to the placeholder table before calling
403
// resolve_instance_class_or_null. ClassCircularityError is detected when a LOAD_SUPER or LOAD_INSTANCE
404
// placeholder for the same thread, class, classloader is found.
405
// This can be seen with logging option: -Xlog:class+load+placeholders=debug.
407
InstanceKlass* SystemDictionary::resolve_super_or_fail(Symbol* class_name,
410
Handle protection_domain,
414
assert(super_name != nullptr, "null superclass for resolving");
415
assert(!Signature::is_array(super_name), "invalid superclass name");
417
if (CDSConfig::is_dumping_static_archive()) {418
// Special processing for handling UNREGISTERED shared classes.
419
InstanceKlass* k = SystemDictionaryShared::lookup_super_for_unregistered_class(class_name,
420
super_name, is_superclass);
427
// If klass is already loaded, just return the superclass or superinterface.
428
// Make sure there's a placeholder for the class_name before resolving.
429
// This is used as a claim that this thread is currently loading superclass/classloader
430
// and for ClassCircularity checks.
432
ClassLoaderData* loader_data = class_loader_data(class_loader);
433
Dictionary* dictionary = loader_data->dictionary();
435
// can't throw error holding a lock
436
bool throw_circularity_error = false;
438
MutexLocker mu(THREAD, SystemDictionary_lock);
439
InstanceKlass* klassk = dictionary->find_class(THREAD, class_name);
440
InstanceKlass* quicksuperk;
441
// To support parallel loading: if class is done loading, just return the superclass
442
// if the super_name matches class->super()->name() and if the class loaders match.
443
// Otherwise, a LinkageError will be thrown later.
444
if (klassk != nullptr && is_superclass &&
445
((quicksuperk = klassk->java_super()) != nullptr) &&
446
((quicksuperk->name() == super_name) &&
447
(quicksuperk->class_loader() == class_loader()))) {450
// Must check ClassCircularity before checking if superclass is already loaded.
451
PlaceholderEntry* probe = PlaceholderTable::get_entry(class_name, loader_data);
452
if (probe && probe->check_seen_thread(THREAD, PlaceholderTable::LOAD_SUPER)) {453
log_circularity_error(class_name, probe);
454
throw_circularity_error = true;
458
if (!throw_circularity_error) {459
// Be careful not to exit resolve_super without removing this placeholder.
460
PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(class_name,
462
PlaceholderTable::LOAD_SUPER,
467
if (throw_circularity_error) {468
ResourceMark rm(THREAD);
469
THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), class_name->as_C_string());
472
// Resolve the superclass or superinterface, check results on return
473
InstanceKlass* superk =
474
SystemDictionary::resolve_instance_class_or_null(super_name,
479
// Clean up placeholder entry.
481
MutexLocker mu(THREAD, SystemDictionary_lock);
482
PlaceholderTable::find_and_remove(class_name, loader_data, PlaceholderTable::LOAD_SUPER, THREAD);
483
SystemDictionary_lock->notify_all();
486
// Check for pending exception or null superk, and throw exception
487
if (HAS_PENDING_EXCEPTION || superk == nullptr) {488
handle_resolution_exception(super_name, true, CHECK_NULL);
494
// If the class in is in the placeholder table, class loading is in progress.
495
// For cases where the application changes threads to load classes, it
496
// is critical to ClassCircularity detection that we try loading
497
// the superclass on the new thread internally, so we do parallel
498
// superclass loading here. This avoids deadlock for ClassCircularity
499
// detection for parallelCapable class loaders that lock on a per-class lock.
500
static void handle_parallel_super_load(Symbol* name,
501
Symbol* superclassname,
503
Handle protection_domain, TRAPS) {505
// superk is not used; resolve_super_or_fail is called for circularity check only.
506
Klass* superk = SystemDictionary::resolve_super_or_fail(name,
514
// Bootstrap and non-parallel capable class loaders use the LOAD_INSTANCE placeholder to
515
// wait for parallel class loading and/or to check for circularity error for Xcomp when loading.
516
static bool needs_load_placeholder(Handle class_loader) {517
return class_loader.is_null() || !is_parallelCapable(class_loader);
520
// Check for other threads loading this class either to throw CCE or wait in the case of the boot loader.
521
static InstanceKlass* handle_parallel_loading(JavaThread* current,
523
ClassLoaderData* loader_data,
524
bool must_wait_for_class_loading,
525
bool* throw_circularity_error) {526
PlaceholderEntry* oldprobe = PlaceholderTable::get_entry(name, loader_data);
527
if (oldprobe != nullptr) {528
// -Xcomp calls load_signature_classes which might result in loading
529
// a class that's already in the process of loading, so we detect CCE here also.
530
// Only need check_seen_thread once, not on each loop
531
if (oldprobe->check_seen_thread(current, PlaceholderTable::LOAD_INSTANCE)) {532
log_circularity_error(name, oldprobe);
533
*throw_circularity_error = true;
535
} else if (must_wait_for_class_loading) {536
// Wait until the first thread has finished loading this class. Also wait until all the
537
// threads trying to load its superclass have removed their placeholders.
538
while (oldprobe != nullptr &&
539
(oldprobe->instance_load_in_progress() || oldprobe->super_load_in_progress())) {541
// LOAD_INSTANCE placeholders are used to implement parallel capable class loading
542
// for the bootclass loader.
543
SystemDictionary_lock->wait();
545
// Check if classloading completed while we were waiting
546
InstanceKlass* check = loader_data->dictionary()->find_class(current, name);
547
if (check != nullptr) {548
// Klass is already loaded, so just return it
551
// check if other thread failed to load and cleaned up
552
oldprobe = PlaceholderTable::get_entry(name, loader_data);
559
void SystemDictionary::post_class_load_event(EventClassLoad* event, const InstanceKlass* k, const ClassLoaderData* init_cld) {560
assert(event != nullptr, "invariant");
561
assert(k != nullptr, "invariant");
562
event->set_loadedClass(k);
563
event->set_definingClassLoader(k->class_loader_data());
564
event->set_initiatingClassLoader(init_cld);
568
// SystemDictionary::resolve_instance_class_or_null is the main function for class name resolution.
569
// After checking if the InstanceKlass already exists, it checks for ClassCircularityError and
570
// whether the thread must wait for loading in parallel. It eventually calls load_instance_class,
571
// which will load the class via the bootstrap loader or call ClassLoader.loadClass().
572
// This can return null, an exception or an InstanceKlass.
573
InstanceKlass* SystemDictionary::resolve_instance_class_or_null(Symbol* name,
575
Handle protection_domain,
577
// name must be in the form of "java/lang/Object" -- cannot be "Ljava/lang/Object;"
578
assert(name != nullptr && !Signature::is_array(name) &&
579
!Signature::has_envelope(name), "invalid class name");
581
EventClassLoad class_load_start_event;
583
HandleMark hm(THREAD);
585
// Fix for 4474172; see evaluation for more details
586
class_loader = Handle(THREAD, java_lang_ClassLoader::non_reflection_class_loader(class_loader()));
587
ClassLoaderData* loader_data = register_loader(class_loader);
588
Dictionary* dictionary = loader_data->dictionary();
590
// Do lookup to see if class already exists and the protection domain
591
// has the right access.
592
// This call uses find which checks protection domain already matches
593
// All subsequent calls use find_class, and set loaded_class so that
594
// before we return a result, we call out to java to check for valid protection domain.
595
InstanceKlass* probe = dictionary->find(THREAD, name, protection_domain);
596
if (probe != nullptr) return probe;
598
// Non-bootstrap class loaders will call out to class loader and
599
// define via jvm/jni_DefineClass which will acquire the
600
// class loader object lock to protect against multiple threads
601
// defining the class in parallel by accident.
602
// This lock must be acquired here so the waiter will find
603
// any successful result in the SystemDictionary and not attempt
605
// ParallelCapable class loaders and the bootstrap classloader
606
// do not acquire lock here.
607
Handle lockObject = get_loader_lock_or_null(class_loader);
608
ObjectLocker ol(lockObject, THREAD);
610
bool super_load_in_progress = false;
611
InstanceKlass* loaded_class = nullptr;
612
SymbolHandle superclassname; // Keep alive while loading in parallel thread.
614
guarantee(THREAD->can_call_java(),
615
"can not load classes with compiler thread: class=%s, classloader=%s",
617
class_loader.is_null() ? "null" : class_loader->klass()->name()->as_C_string());
619
// Check again (after locking) if the class already exists in SystemDictionary
621
MutexLocker mu(THREAD, SystemDictionary_lock);
622
InstanceKlass* check = dictionary->find_class(THREAD, name);
623
if (check != nullptr) {624
// InstanceKlass is already loaded, but we still need to check protection domain below.
625
loaded_class = check;
627
PlaceholderEntry* placeholder = PlaceholderTable::get_entry(name, loader_data);
628
if (placeholder != nullptr && placeholder->super_load_in_progress()) {629
super_load_in_progress = true;
630
superclassname = placeholder->supername();
631
assert(superclassname != nullptr, "superclass has to have a name");
636
// If the class is in the placeholder table with super_class set,
637
// handle superclass loading in progress.
638
if (super_load_in_progress) {639
handle_parallel_super_load(name, superclassname,
645
bool throw_circularity_error = false;
646
if (loaded_class == nullptr) {647
bool load_placeholder_added = false;
649
// Add placeholder entry to record loading instance class
650
// case 1. Bootstrap classloader
651
// This classloader supports parallelism at the classloader level
652
// but only allows a single thread to load a class/classloader pair.
653
// The LOAD_INSTANCE placeholder is the mechanism for mutual exclusion.
654
// case 2. parallelCapable user level classloaders
655
// These class loaders lock a per-class object lock when ClassLoader.loadClass()
656
// is called. A LOAD_INSTANCE placeholder isn't used for mutual exclusion.
657
// case 3. traditional classloaders that rely on the classloader object lock
658
// There should be no need for need for LOAD_INSTANCE for mutual exclusion,
659
// except the LOAD_INSTANCE placeholder is used to detect CCE for -Xcomp.
660
// TODO: should also be used to detect CCE for parallel capable class loaders but it's not.
662
MutexLocker mu(THREAD, SystemDictionary_lock);
663
if (needs_load_placeholder(class_loader)) {664
loaded_class = handle_parallel_loading(THREAD,
667
class_loader.is_null(),
668
&throw_circularity_error);
671
// Recheck if the class has been loaded for all class loader cases and
672
// add a LOAD_INSTANCE placeholder while holding the SystemDictionary_lock.
673
if (!throw_circularity_error && loaded_class == nullptr) {674
InstanceKlass* check = dictionary->find_class(THREAD, name);
675
if (check != nullptr) {676
loaded_class = check;
677
} else if (needs_load_placeholder(class_loader)) {678
// Add the LOAD_INSTANCE token. Threads will wait on loading to complete for this thread.
679
PlaceholderEntry* newprobe = PlaceholderTable::find_and_add(name, loader_data,
680
PlaceholderTable::LOAD_INSTANCE,
683
load_placeholder_added = true;
688
// Must throw error outside of owning lock
689
if (throw_circularity_error) {690
assert(!HAS_PENDING_EXCEPTION && !load_placeholder_added, "circularity error cleanup");
691
ResourceMark rm(THREAD);
692
THROW_MSG_NULL(vmSymbols::java_lang_ClassCircularityError(), name->as_C_string());
695
// Be careful when modifying this code: once you have run
696
// PlaceholderTable::find_and_add(PlaceholderTable::LOAD_INSTANCE),
697
// you need to find_and_remove it before returning.
698
// So be careful to not exit with a CHECK_ macro between these calls.
700
if (loaded_class == nullptr) {702
loaded_class = load_instance_class(name, class_loader, THREAD);
705
if (load_placeholder_added) {706
// clean up placeholder entries for LOAD_INSTANCE success or error
707
// This brackets the SystemDictionary updates for both defining
708
// and initiating loaders
709
MutexLocker mu(THREAD, SystemDictionary_lock);
710
PlaceholderTable::find_and_remove(name, loader_data, PlaceholderTable::LOAD_INSTANCE, THREAD);
711
SystemDictionary_lock->notify_all();
715
if (HAS_PENDING_EXCEPTION || loaded_class == nullptr) {719
if (class_load_start_event.should_commit()) {720
post_class_load_event(&class_load_start_event, loaded_class, loader_data);
723
// Make sure we have the right class in the dictionary
724
DEBUG_ONLY(verify_dictionary_entry(name, loaded_class));
726
if (protection_domain() != nullptr) {727
// A SecurityManager (if installed) may prevent this protection_domain from accessing loaded_class
728
// by throwing a SecurityException.
729
dictionary->check_package_access(loaded_class, class_loader, protection_domain, CHECK_NULL);
736
// This routine does not lock the system dictionary.
738
// Since readers don't hold a lock, we must make sure that system
739
// dictionary entries are added to in a safe way (all links must
740
// be updated in an MT-safe manner). All entries are removed during class
741
// unloading, when this class loader is no longer referenced.
743
// Callers should be aware that an entry could be added just after
744
// Dictionary is read here, so the caller will not see
747
InstanceKlass* SystemDictionary::find_instance_klass(Thread* current,
750
Handle protection_domain) {752
// The result of this call should be consistent with the result
753
// of the call to resolve_instance_class_or_null().
754
// See evaluation 6790209 and 4474172 for more details.
755
oop class_loader_oop = java_lang_ClassLoader::non_reflection_class_loader(class_loader());
756
ClassLoaderData* loader_data = ClassLoaderData::class_loader_data_or_null(class_loader_oop);
758
if (loader_data == nullptr) {759
// If the ClassLoaderData has not been setup,
760
// then the class loader has no entries in the dictionary.
764
Dictionary* dictionary = loader_data->dictionary();
765
return dictionary->find(current, class_name, protection_domain);
768
// Look for a loaded instance or array klass by name. Do not do any loading.
769
// return null in case of error.
770
Klass* SystemDictionary::find_instance_or_array_klass(Thread* current,
773
Handle protection_domain) {775
assert(class_name != nullptr, "class name must be non nullptr");
777
if (Signature::is_array(class_name)) {778
// The name refers to an array. Parse the name.
779
// dimension and object_key in FieldArrayInfo are assigned as a
780
// side-effect of this call
781
SignatureStream ss(class_name, false);
782
int ndims = ss.skip_array_prefix(); // skip all '['s
783
BasicType t = ss.type();
785
k = Universe::typeArrayKlass(t);
787
k = SystemDictionary::find_instance_klass(current, ss.as_symbol(), class_loader, protection_domain);
790
k = k->array_klass_or_null(ndims);
793
k = find_instance_klass(current, class_name, class_loader, protection_domain);
798
// Note: this method is much like resolve_class_from_stream, but
799
// does not publish the classes in the SystemDictionary.
800
// Handles Lookup.defineClass hidden.
801
InstanceKlass* SystemDictionary::resolve_hidden_class_from_stream(
805
const ClassLoadInfo& cl_info,
808
EventClassLoad class_load_start_event;
809
ClassLoaderData* loader_data;
811
// - for hidden classes that are not strong: create a new CLD that has a class holder and
812
// whose loader is the Lookup class's loader.
813
// - for hidden class: add the class to the Lookup class's loader's CLD.
814
assert (cl_info.is_hidden(), "only used for hidden classes");
815
bool create_mirror_cld = !cl_info.is_strong_hidden();
816
loader_data = register_loader(class_loader, create_mirror_cld);
818
assert(st != nullptr, "invariant");
819
assert(st->need_verify(), "invariant");
821
// Parse stream and create a klass.
822
InstanceKlass* k = KlassFactory::create_from_stream(st,
827
assert(k != nullptr, "no klass created");
829
// Hidden classes that are not strong must update ClassLoaderData holder
830
// so that they can be unloaded when the mirror is no longer referenced.
831
if (!cl_info.is_strong_hidden()) {832
k->class_loader_data()->initialize_holder(Handle(THREAD, k->java_mirror()));
835
// Add to class hierarchy, and do possible deoptimizations.
836
k->add_to_hierarchy(THREAD);
837
// But, do not add to dictionary.
839
k->link_class(CHECK_NULL);
842
if (JvmtiExport::should_post_class_load()) {843
JvmtiExport::post_class_load(THREAD, k);
845
if (class_load_start_event.should_commit()) {846
post_class_load_event(&class_load_start_event, k, loader_data);
852
// Add a klass to the system from a stream (called by jni_DefineClass and
854
// Note: class_name can be null. In that case we do not know the name of
855
// the class until we have parsed the stream.
856
// This function either returns an InstanceKlass or throws an exception. It does
857
// not return null without a pending exception.
858
InstanceKlass* SystemDictionary::resolve_class_from_stream(
862
const ClassLoadInfo& cl_info,
865
HandleMark hm(THREAD);
867
ClassLoaderData* loader_data = register_loader(class_loader);
869
// Classloaders that support parallelism, e.g. bootstrap classloader,
870
// do not acquire lock here
871
Handle lockObject = get_loader_lock_or_null(class_loader);
872
ObjectLocker ol(lockObject, THREAD);
874
// Parse the stream and create a klass.
875
// Note that we do this even though this klass might
876
// already be present in the SystemDictionary, otherwise we would not
877
// throw potential ClassFormatErrors.
878
InstanceKlass* k = nullptr;
881
if (!CDSConfig::is_dumping_static_archive()) {882
k = SystemDictionaryShared::lookup_from_stream(class_name,
884
cl_info.protection_domain(),
891
k = KlassFactory::create_from_stream(st, class_name, loader_data, cl_info, CHECK_NULL);
894
assert(k != nullptr, "no klass created");
895
Symbol* h_name = k->name();
896
assert(class_name == nullptr || class_name == h_name, "name mismatch");
898
// Add class just loaded
899
// If a class loader supports parallel classloading, handle parallel define requests.
900
// find_or_define_instance_class may return a different InstanceKlass,
901
// in which case the old k would be deallocated
902
if (is_parallelCapable(class_loader)) {903
k = find_or_define_instance_class(h_name, class_loader, k, CHECK_NULL);
905
define_instance_class(k, class_loader, THREAD);
907
// If defining the class throws an exception register 'k' for cleanup.
908
if (HAS_PENDING_EXCEPTION) {909
assert(k != nullptr, "Must have an instance klass here!");
910
loader_data->add_to_deallocate_list(k);
915
// Make sure we have an entry in the SystemDictionary on success
916
DEBUG_ONLY(verify_dictionary_entry(h_name, k));
921
InstanceKlass* SystemDictionary::resolve_from_stream(ClassFileStream* st,
924
const ClassLoadInfo& cl_info,
926
if (cl_info.is_hidden()) {927
return resolve_hidden_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
929
return resolve_class_from_stream(st, class_name, class_loader, cl_info, CHECK_NULL);
935
// Check if a shared class can be loaded by the specific classloader.
936
bool SystemDictionary::is_shared_class_visible(Symbol* class_name,
938
PackageEntry* pkg_entry,
939
Handle class_loader) {940
assert(!ModuleEntryTable::javabase_moduleEntry()->is_patched(),
941
"Cannot use sharing if java.base is patched");
943
// (1) Check if we are loading into the same loader as in dump time.
945
if (ik->is_shared_boot_class()) {946
if (class_loader() != nullptr) {949
} else if (ik->is_shared_platform_class()) {950
if (class_loader() != java_platform_loader()) {953
} else if (ik->is_shared_app_class()) {954
if (class_loader() != java_system_loader()) {958
// ik was loaded by a custom loader during dump time
959
if (class_loader_data(class_loader)->is_builtin_class_loader_data()) {966
// (2) Check if we are loading into the same module from the same location as in dump time.
968
if (CDSConfig::is_using_optimized_module_handling()) {969
// Class visibility has not changed between dump time and run time, so a class
970
// that was visible (and thus archived) during dump time is always visible during runtime.
971
assert(SystemDictionary::is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader),
972
"visibility cannot change between dump time and runtime");
975
return is_shared_class_visible_impl(class_name, ik, pkg_entry, class_loader);
978
bool SystemDictionary::is_shared_class_visible_impl(Symbol* class_name,
980
PackageEntry* pkg_entry,
981
Handle class_loader) {982
int scp_index = ik->shared_classpath_index();
983
assert(!ik->is_shared_unregistered_class(), "this function should be called for built-in classes only");
984
assert(scp_index >= 0, "must be");
985
SharedClassPathEntry* scp_entry = FileMapInfo::shared_path(scp_index);
986
if (!Universe::is_module_initialized()) {987
assert(scp_entry != nullptr, "must be");
988
// At this point, no modules have been defined yet. KlassSubGraphInfo::check_allowed_klass()
989
// has restricted the classes can be loaded at this step to be only:
990
// [1] scp_entry->is_modules_image(): classes in java.base, or,
991
// [2] HeapShared::is_a_test_class_in_unnamed_module(ik): classes in bootstrap/unnamed module
992
assert(scp_entry->is_modules_image() || HeapShared::is_a_test_class_in_unnamed_module(ik),
993
"only these classes can be loaded before the module system is initialized");
994
assert(class_loader.is_null(), "sanity");
998
if (pkg_entry == nullptr) {999
// We might have looked up pkg_entry before the module system was initialized.
1000
// Need to reload it now.
1001
TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1002
if (pkg_name != nullptr) {1003
pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1007
ModuleEntry* mod_entry = (pkg_entry == nullptr) ? nullptr : pkg_entry->module();
1008
bool should_be_in_named_module = (mod_entry != nullptr && mod_entry->is_named());
1009
bool was_archived_from_named_module = scp_entry->in_named_module();
1012
if (was_archived_from_named_module) {1013
if (should_be_in_named_module) {1014
// Is the module loaded from the same location as during dump time?
1015
visible = mod_entry->shared_path_index() == scp_index;
1017
assert(!mod_entry->is_patched(), "cannot load archived classes for patched module");
1020
// During dump time, this class was in a named module, but at run time, this class should be
1021
// in an unnamed module.
1025
if (should_be_in_named_module) {1026
// During dump time, this class was in an unnamed, but at run time, this class should be
1027
// in a named module.
1037
bool SystemDictionary::check_shared_class_super_type(InstanceKlass* klass, InstanceKlass* super_type,
1038
Handle class_loader, Handle protection_domain,
1039
bool is_superclass, TRAPS) {1040
assert(super_type->is_shared(), "must be");
1042
// Quick check if the super type has been already loaded.
1043
// + Don't do it for unregistered classes -- they can be unloaded so
1044
// super_type->class_loader_data() could be stale.
1045
// + Don't check if loader data is null, ie. the super_type isn't fully loaded.
1046
if (!super_type->is_shared_unregistered_class() && super_type->class_loader_data() != nullptr) {1047
// Check if the superclass is loaded by the current class_loader
1048
Symbol* name = super_type->name();
1049
InstanceKlass* check = find_instance_klass(THREAD, name, class_loader, protection_domain);
1050
if (check == super_type) {1055
Klass *found = resolve_super_or_fail(klass->name(), super_type->name(),
1056
class_loader, protection_domain, is_superclass, CHECK_0);
1057
if (found == super_type) {1060
// The dynamically resolved super type is not the same as the one we used during dump time,
1061
// so we cannot use the class.
1066
bool SystemDictionary::check_shared_class_super_types(InstanceKlass* ik, Handle class_loader,
1067
Handle protection_domain, TRAPS) {1068
// Check the superclass and interfaces. They must be the same
1069
// as in dump time, because the layout of <ik> depends on
1070
// the specific layout of ik->super() and ik->local_interfaces().
1072
// If unexpected superclass or interfaces are found, we cannot
1073
// load <ik> from the shared archive.
1075
if (ik->super() != nullptr &&
1076
!check_shared_class_super_type(ik, InstanceKlass::cast(ik->super()),
1077
class_loader, protection_domain, true, THREAD)) {1081
Array<InstanceKlass*>* interfaces = ik->local_interfaces();
1082
int num_interfaces = interfaces->length();
1083
for (int index = 0; index < num_interfaces; index++) {1084
if (!check_shared_class_super_type(ik, interfaces->at(index), class_loader, protection_domain, false, THREAD)) {1092
InstanceKlass* SystemDictionary::load_shared_lambda_proxy_class(InstanceKlass* ik,
1093
Handle class_loader,
1094
Handle protection_domain,
1095
PackageEntry* pkg_entry,
1097
InstanceKlass* shared_nest_host = SystemDictionaryShared::get_shared_nest_host(ik);
1098
assert(shared_nest_host->is_shared(), "nest host must be in CDS archive");
1099
Symbol* cn = shared_nest_host->name();
1100
Klass *s = resolve_or_fail(cn, class_loader, protection_domain, true, CHECK_NULL);
1101
if (s != shared_nest_host) {1102
// The dynamically resolved nest_host is not the same as the one we used during dump time,
1103
// so we cannot use ik.
1106
assert(s->is_shared(), "must be");
1109
InstanceKlass* loaded_ik = load_shared_class(ik, class_loader, protection_domain, nullptr, pkg_entry, CHECK_NULL);
1111
if (loaded_ik != nullptr) {1112
assert(shared_nest_host->is_same_class_package(ik),
1113
"lambda proxy class and its nest host must be in the same package");
1114
// The lambda proxy class and its nest host have the same class loader and class loader data,
1115
// as verified in SystemDictionaryShared::add_lambda_proxy_class()
1116
assert(shared_nest_host->class_loader() == class_loader(), "mismatched class loader");
1117
assert(shared_nest_host->class_loader_data() == class_loader_data(class_loader), "mismatched class loader data");
1118
ik->set_nest_host(shared_nest_host);
1124
InstanceKlass* SystemDictionary::load_shared_class(InstanceKlass* ik,
1125
Handle class_loader,
1126
Handle protection_domain,
1127
const ClassFileStream *cfs,
1128
PackageEntry* pkg_entry,
1130
assert(ik != nullptr, "sanity");
1131
assert(!ik->is_unshareable_info_restored(), "shared class can be restored only once");
1132
assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1, "shared class loaded more than once");
1133
Symbol* class_name = ik->name();
1135
if (!is_shared_class_visible(class_name, ik, pkg_entry, class_loader)) {1139
if (!check_shared_class_super_types(ik, class_loader, protection_domain, THREAD)) {1143
InstanceKlass* new_ik = nullptr;
1144
// CFLH check is skipped for VM hidden classes (see KlassFactory::create_from_stream).
1145
// It will be skipped for shared VM hidden lambda proxy classes.
1146
if (!SystemDictionaryShared::is_hidden_lambda_proxy(ik)) {1147
new_ik = KlassFactory::check_shared_class_file_load_hook(
1148
ik, class_name, class_loader, protection_domain, cfs, CHECK_NULL);
1150
if (new_ik != nullptr) {1151
// The class is changed by CFLH. Return the new class. The shared class is
1156
// Adjust methods to recover missing data. They need addresses for
1157
// interpreter entry points and their default native method address
1160
// Shared classes are all currently loaded by either the bootstrap or
1161
// internal parallel class loaders, so this will never cause a deadlock
1162
// on a custom class loader lock.
1163
// Since this class is already locked with parallel capable class
1164
// loaders, including the bootstrap loader via the placeholder table,
1165
// this lock is currently a nop.
1167
ClassLoaderData* loader_data = class_loader_data(class_loader);
1169
HandleMark hm(THREAD);
1170
Handle lockObject = get_loader_lock_or_null(class_loader);
1171
ObjectLocker ol(lockObject, THREAD);
1172
// prohibited package check assumes all classes loaded from archive call
1173
// restore_unshareable_info which calls ik->set_package()
1174
ik->restore_unshareable_info(loader_data, protection_domain, pkg_entry, CHECK_NULL);
1177
load_shared_class_misc(ik, loader_data);
1181
void SystemDictionary::load_shared_class_misc(InstanceKlass* ik, ClassLoaderData* loader_data) {1182
ik->print_class_load_logging(loader_data, nullptr, nullptr);
1184
// For boot loader, ensure that GetSystemPackage knows that a class in this
1185
// package was loaded.
1186
if (loader_data->is_the_null_class_loader_data()) {1187
s2 path_index = ik->shared_classpath_index();
1188
ik->set_classpath_index(path_index);
1191
// notify a class loaded from shared object
1192
ClassLoadingService::notify_class_loaded(ik, true /* shared class */);
1195
#endif // INCLUDE_CDS
1197
InstanceKlass* SystemDictionary::load_instance_class_impl(Symbol* class_name, Handle class_loader, TRAPS) {1199
if (class_loader.is_null()) {1200
ResourceMark rm(THREAD);
1201
PackageEntry* pkg_entry = nullptr;
1202
bool search_only_bootloader_append = false;
1204
// Find the package in the boot loader's package entry table.
1205
TempNewSymbol pkg_name = ClassLoader::package_from_class_name(class_name);
1206
if (pkg_name != nullptr) {1207
pkg_entry = class_loader_data(class_loader)->packages()->lookup_only(pkg_name);
1210
// Prior to attempting to load the class, enforce the boot loader's
1211
// visibility boundaries.
1212
if (!Universe::is_module_initialized()) {1213
// During bootstrapping, prior to module initialization, any
1214
// class attempting to be loaded must be checked against the
1215
// java.base packages in the boot loader's PackageEntryTable.
1216
// No class outside of java.base is allowed to be loaded during
1217
// this bootstrapping window.
1218
if (pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {1219
// Class is either in the unnamed package or in
1220
// a named package within the unnamed module. Either
1221
// case is outside of java.base, do not attempt to
1222
// load the class post java.base definition. If
1223
// java.base has not been defined, let the class load
1224
// and its package will be checked later by
1225
// ModuleEntryTable::verify_javabase_packages.
1226
if (ModuleEntryTable::javabase_defined()) {1230
// Check that the class' package is defined within java.base.
1231
ModuleEntry* mod_entry = pkg_entry->module();
1232
Symbol* mod_entry_name = mod_entry->name();
1233
if (mod_entry_name->fast_compare(vmSymbols::java_base()) != 0) {1238
// After the module system has been initialized, check if the class'
1239
// package is in a module defined to the boot loader.
1240
if (pkg_name == nullptr || pkg_entry == nullptr || pkg_entry->in_unnamed_module()) {1241
// Class is either in the unnamed package, in a named package
1242
// within a module not defined to the boot loader or in a
1243
// a named package within the unnamed module. In all cases,
1244
// limit visibility to search for the class only in the boot
1245
// loader's append path.
1246
if (!ClassLoader::has_bootclasspath_append()) {1247
// If there is no bootclasspath append entry, no need to continue
1251
search_only_bootloader_append = true;
1255
// Prior to bootstrapping's module initialization, never load a class outside
1256
// of the boot loader's module path
1257
assert(Universe::is_module_initialized() ||
1258
!search_only_bootloader_append,
1259
"Attempt to load a class outside of boot loader's module path");
1261
// Search for classes in the CDS archive.
1262
InstanceKlass* k = nullptr;
1265
if (CDSConfig::is_using_archive())
1267
PerfTraceTime vmtimer(ClassLoader::perf_shared_classload_time());
1268
InstanceKlass* ik = SystemDictionaryShared::find_builtin_class(class_name);
1269
if (ik != nullptr && ik->is_shared_boot_class() && !ik->shared_loading_failed()) {1270
SharedClassLoadingMark slm(THREAD, ik);
1271
k = load_shared_class(ik, class_loader, Handle(), nullptr, pkg_entry, CHECK_NULL);
1277
// Use VM class loader
1278
PerfTraceTime vmtimer(ClassLoader::perf_sys_classload_time());
1279
k = ClassLoader::load_class(class_name, pkg_entry, search_only_bootloader_append, CHECK_NULL);
1282
// find_or_define_instance_class may return a different InstanceKlass
1284
CDS_ONLY(SharedClassLoadingMark slm(THREAD, k);)
1285
k = find_or_define_instance_class(class_name, class_loader, k, CHECK_NULL);
1289
// Use user specified class loader to load class. Call loadClass operation on class_loader.
1290
ResourceMark rm(THREAD);
1292
JavaThread* jt = THREAD;
1294
PerfClassTraceTime vmtimer(ClassLoader::perf_app_classload_time(),
1295
ClassLoader::perf_app_classload_selftime(),
1296
ClassLoader::perf_app_classload_count(),
1297
jt->get_thread_stat()->perf_recursion_counts_addr(),
1298
jt->get_thread_stat()->perf_timers_addr(),
1299
PerfClassTraceTime::CLASS_LOAD);
1301
// Translate to external class name format, i.e., convert '/' chars to '.'
1302
Handle string = java_lang_String::externalize_classname(class_name, CHECK_NULL);
1304
JavaValue result(T_OBJECT);
1306
InstanceKlass* spec_klass = vmClasses::ClassLoader_klass();
1308
// Call public unsynchronized loadClass(String) directly for all class loaders.
1309
// For parallelCapable class loaders, JDK >=7, loadClass(String, boolean) will
1310
// acquire a class-name based lock rather than the class loader object lock.
1311
// JDK < 7 already acquire the class loader lock in loadClass(String, boolean).
1312
JavaCalls::call_virtual(&result,
1315
vmSymbols::loadClass_name(),
1316
vmSymbols::string_class_signature(),
1320
assert(result.get_type() == T_OBJECT, "just checking");
1321
oop obj = result.get_oop();
1323
// Primitive classes return null since forName() can not be
1324
// used to obtain any of the Class objects representing primitives or void
1325
if ((obj != nullptr) && !(java_lang_Class::is_primitive(obj))) {1326
InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(obj));
1327
// For user defined Java class loaders, check that the name returned is
1328
// the same as that requested. This check is done for the bootstrap
1329
// loader when parsing the class file.
1330
if (class_name == k->name()) {1334
// Class is not found or has the wrong name, return null
1339
InstanceKlass* SystemDictionary::load_instance_class(Symbol* name,
1340
Handle class_loader,
1343
InstanceKlass* loaded_class = load_instance_class_impl(name, class_loader, CHECK_NULL);
1345
// If everything was OK (no exceptions, no null return value), and
1346
// class_loader is NOT the defining loader, do a little more bookkeeping.
1347
if (loaded_class != nullptr &&
1348
loaded_class->class_loader() != class_loader()) {1350
ClassLoaderData* loader_data = class_loader_data(class_loader);
1351
check_constraints(loaded_class, loader_data, false, CHECK_NULL);
1353
// Record dependency for non-parent delegation.
1354
// This recording keeps the defining class loader of the klass (loaded_class) found
1355
// from being unloaded while the initiating class loader is loaded
1356
// even if the reference to the defining class loader is dropped
1357
// before references to the initiating class loader.
1358
loader_data->record_dependency(loaded_class);
1360
update_dictionary(THREAD, loaded_class, loader_data);
1362
if (JvmtiExport::should_post_class_load()) {1363
JvmtiExport::post_class_load(THREAD, loaded_class);
1366
return loaded_class;
1369
static void post_class_define_event(InstanceKlass* k, const ClassLoaderData* def_cld) {1370
EventClassDefine event;
1371
if (event.should_commit()) {1372
event.set_definedClass(k);
1373
event.set_definingClassLoader(def_cld);
1378
void SystemDictionary::define_instance_class(InstanceKlass* k, Handle class_loader, TRAPS) {1380
ClassLoaderData* loader_data = k->class_loader_data();
1381
assert(loader_data->class_loader() == class_loader(), "they must be the same");
1383
// Bootstrap and other parallel classloaders don't acquire a lock,
1384
// they use placeholder token.
1385
// If a parallelCapable class loader calls define_instance_class instead of
1386
// find_or_define_instance_class to get here, we have a timing
1387
// hole with systemDictionary updates and check_constraints
1388
if (!is_parallelCapable(class_loader)) {1389
assert(ObjectSynchronizer::current_thread_holds_lock(THREAD,
1390
get_loader_lock_or_null(class_loader)),
1391
"define called without lock");
1394
// Check class-loading constraints. Throw exception if violation is detected.
1395
// Grabs and releases SystemDictionary_lock
1396
// The check_constraints/find_class call and update_dictionary sequence
1397
// must be "atomic" for a specific class/classloader pair so we never
1398
// define two different instanceKlasses for that class/classloader pair.
1399
// Existing classloaders will call define_instance_class with the
1400
// classloader lock held
1401
// Parallel classloaders will call find_or_define_instance_class
1402
// which will require a token to perform the define class
1403
check_constraints(k, loader_data, true, CHECK);
1405
// Register class just loaded with class loader (placed in ArrayList)
1406
// Note we do this before updating the dictionary, as this can
1407
// fail with an OutOfMemoryError (if it does, we will *not* put this
1408
// class in the dictionary and will not update the class hierarchy).
1409
// JVMTI FollowReferences needs to find the classes this way.
1410
if (k->class_loader() != nullptr) {1411
methodHandle m(THREAD, Universe::loader_addClass_method());
1412
JavaValue result(T_VOID);
1413
JavaCallArguments args(class_loader);
1414
args.push_oop(Handle(THREAD, k->java_mirror()));
1415
JavaCalls::call(&result, m, &args, CHECK);
1418
// Add to class hierarchy, and do possible deoptimizations.
1419
k->add_to_hierarchy(THREAD);
1421
// Add to systemDictionary - so other classes can see it.
1422
// Grabs and releases SystemDictionary_lock
1423
update_dictionary(THREAD, k, loader_data);
1426
if (JvmtiExport::should_post_class_load()) {1427
JvmtiExport::post_class_load(THREAD, k);
1429
post_class_define_event(k, loader_data);
1432
// Support parallel classloading
1433
// All parallel class loaders, including bootstrap classloader
1434
// lock a placeholder entry for this class/class_loader pair
1435
// to allow parallel defines of different classes for this class loader
1436
// With AllowParallelDefine flag==true, in case they do not synchronize around
1437
// FindLoadedClass/DefineClass, calls, we check for parallel
1438
// loading for them, wait if a defineClass is in progress
1439
// and return the initial requestor's results
1440
// This flag does not apply to the bootstrap classloader.
1441
// With AllowParallelDefine flag==false, call through to define_instance_class
1442
// which will throw LinkageError: duplicate class definition.
1443
// False is the requested default.
1444
// For better performance, the class loaders should synchronize
1445
// findClass(), i.e. FindLoadedClass/DefineClassIfAbsent or they
1446
// potentially waste time reading and parsing the bytestream.
1447
// Note: VM callers should ensure consistency of k/class_name,class_loader
1448
// Be careful when modifying this code: once you have run
1449
// PlaceholderTable::find_and_add(PlaceholderTable::DEFINE_CLASS),
1450
// you need to find_and_remove it before returning.
1451
// So be careful to not exit with a CHECK_ macro between these calls.
1452
InstanceKlass* SystemDictionary::find_or_define_helper(Symbol* class_name, Handle class_loader,
1453
InstanceKlass* k, TRAPS) {1455
Symbol* name_h = k->name();
1456
ClassLoaderData* loader_data = class_loader_data(class_loader);
1457
Dictionary* dictionary = loader_data->dictionary();
1459
// Hold SD lock around find_class and placeholder creation for DEFINE_CLASS
1461
MutexLocker mu(THREAD, SystemDictionary_lock);
1462
// First check if class already defined
1463
if (is_parallelDefine(class_loader)) {1464
InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1465
if (check != nullptr) {1470
// Acquire define token for this class/classloader
1471
PlaceholderEntry* probe = PlaceholderTable::find_and_add(name_h, loader_data,
1472
PlaceholderTable::DEFINE_CLASS, nullptr, THREAD);
1473
// Wait if another thread defining in parallel
1474
// All threads wait - even those that will throw duplicate class: otherwise
1475
// caller is surprised by LinkageError: duplicate, but findLoadedClass fails
1476
// if other thread has not finished updating dictionary
1477
while (probe->definer() != nullptr) {1478
SystemDictionary_lock->wait();
1480
// Only special cases allow parallel defines and can use other thread's results
1481
// Other cases fall through, and may run into duplicate defines
1482
// caught by finding an entry in the SystemDictionary
1483
if (is_parallelDefine(class_loader) && (probe->instance_klass() != nullptr)) {1484
InstanceKlass* ik = probe->instance_klass();
1485
PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1486
SystemDictionary_lock->notify_all();
1488
InstanceKlass* check = dictionary->find_class(THREAD, name_h);
1489
assert(check != nullptr, "definer missed recording success");
1493
// This thread will define the class (even if earlier thread tried and had an error)
1494
probe->set_definer(THREAD);
1498
define_instance_class(k, class_loader, THREAD);
1500
// definer must notify any waiting threads
1502
MutexLocker mu(THREAD, SystemDictionary_lock);
1503
PlaceholderEntry* probe = PlaceholderTable::get_entry(name_h, loader_data);
1504
assert(probe != nullptr, "DEFINE_CLASS placeholder lost?");
1505
if (!HAS_PENDING_EXCEPTION) {1506
probe->set_instance_klass(k);
1508
probe->set_definer(nullptr);
1509
PlaceholderTable::find_and_remove(name_h, loader_data, PlaceholderTable::DEFINE_CLASS, THREAD);
1510
SystemDictionary_lock->notify_all();
1513
return HAS_PENDING_EXCEPTION ? nullptr : k;
1516
// If a class loader supports parallel classloading handle parallel define requests.
1517
// find_or_define_instance_class may return a different InstanceKlass
1518
InstanceKlass* SystemDictionary::find_or_define_instance_class(Symbol* class_name, Handle class_loader,
1519
InstanceKlass* k, TRAPS) {1520
InstanceKlass* defined_k = find_or_define_helper(class_name, class_loader, k, THREAD);
1521
// Clean up original InstanceKlass if duplicate or error
1522
if (!HAS_PENDING_EXCEPTION && defined_k != k) {1523
// If a parallel capable class loader already defined this class, register 'k' for cleanup.
1524
assert(defined_k != nullptr, "Should have a klass if there's no exception");
1525
k->class_loader_data()->add_to_deallocate_list(k);
1526
} else if (HAS_PENDING_EXCEPTION) {1527
// Remove this InstanceKlass from the LoaderConstraintTable if added.
1528
LoaderConstraintTable::remove_failed_loaded_klass(k, class_loader_data(class_loader));
1529
assert(defined_k == nullptr, "Should not have a klass if there's an exception");
1530
k->class_loader_data()->add_to_deallocate_list(k);
1536
// ----------------------------------------------------------------------------
1539
// Assumes classes in the SystemDictionary are only unloaded at a safepoint
1540
bool SystemDictionary::do_unloading(GCTimer* gc_timer) {1542
bool unloading_occurred;
1543
bool is_concurrent = !SafepointSynchronize::is_at_safepoint();
1545
GCTraceTime(Debug, gc, phases) t("ClassLoaderData", gc_timer);1546
assert_locked_or_safepoint(ClassLoaderDataGraph_lock); // caller locks.
1547
// First, mark for unload all ClassLoaderData referencing a dead class loader.
1548
unloading_occurred = ClassLoaderDataGraph::do_unloading();
1549
if (unloading_occurred) {1550
ConditionalMutexLocker ml2(Module_lock, is_concurrent);
1551
JFR_ONLY(Jfr::on_unloading_classes();)
1552
MANAGEMENT_ONLY(FinalizerService::purge_unloaded();)
1553
ConditionalMutexLocker ml1(SystemDictionary_lock, is_concurrent);
1554
ClassLoaderDataGraph::clean_module_and_package_info();
1555
LoaderConstraintTable::purge_loader_constraints();
1556
ResolutionErrorTable::purge_resolution_errors();
1560
GCTraceTime(Debug, gc, phases) t("Trigger cleanups", gc_timer);1562
if (unloading_occurred) {1563
SymbolTable::trigger_cleanup();
1565
if (java_lang_System::allow_security_manager()) {1566
// Oops referenced by the protection domain cache table may get unreachable independently
1567
// of the class loader (eg. cached protection domain oops). So we need to
1568
// explicitly unlink them here.
1569
// All protection domain oops are linked to the caller class, so if nothing
1570
// unloads, this is not needed.
1571
ProtectionDomainCacheTable::trigger_cleanup();
1573
assert(ProtectionDomainCacheTable::number_of_entries() == 0, "should be empty");
1576
ConditionalMutexLocker ml(ClassInitError_lock, is_concurrent);
1577
InstanceKlass::clean_initialization_error_table();
1580
return unloading_occurred;
1583
void SystemDictionary::methods_do(void f(Method*)) {1584
// Walk methods in loaded classes
1587
MutexLocker ml(ClassLoaderDataGraph_lock);
1588
ClassLoaderDataGraph::methods_do(f);
1591
auto doit = [&] (InvokeMethodKey key, Method* method) {1592
if (method != nullptr) {1598
MutexLocker ml(InvokeMethodIntrinsicTable_lock);
1599
_invoke_method_intrinsic_table->iterate_all(doit);
1604
// ----------------------------------------------------------------------------
1607
void SystemDictionary::initialize(TRAPS) {1608
_invoke_method_intrinsic_table = new (mtClass) InvokeMethodIntrinsicTable();
1609
_invoke_method_type_table = new (mtClass) InvokeMethodTypeTable();
1610
ResolutionErrorTable::initialize();
1611
LoaderConstraintTable::initialize();
1612
PlaceholderTable::initialize();
1613
ProtectionDomainCacheTable::initialize();
1615
SystemDictionaryShared::initialize();
1617
// Resolve basic classes
1618
vmClasses::resolve_all(CHECK);
1619
// Resolve classes used by archived heap objects
1620
if (CDSConfig::is_using_archive()) {1621
HeapShared::resolve_classes(THREAD);
1625
// Constraints on class loaders. The details of the algorithm can be
1626
// found in the OOPSLA'98 paper "Dynamic Class Loading in the Java
1627
// Virtual Machine" by Sheng Liang and Gilad Bracha. The basic idea is
1628
// that the dictionary needs to maintain a set of constraints that
1629
// must be satisfied by all classes in the dictionary.
1630
// if defining is true, then LinkageError if already in dictionary
1631
// if initiating loader, then ok if InstanceKlass matches existing entry
1633
void SystemDictionary::check_constraints(InstanceKlass* k,
1634
ClassLoaderData* loader_data,
1637
ResourceMark rm(THREAD);
1639
bool throwException = false;
1642
Symbol* name = k->name();
1644
MutexLocker mu(THREAD, SystemDictionary_lock);
1646
InstanceKlass* check = loader_data->dictionary()->find_class(THREAD, name);
1647
if (check != nullptr) {1648
// If different InstanceKlass - duplicate class definition,
1649
// else - ok, class loaded by a different thread in parallel.
1650
// We should only have found it if it was done loading and ok to use.
1652
if ((defining == true) || (k != check)) {1653
throwException = true;
1654
ss.print("loader %s", loader_data->loader_name_and_id());1655
ss.print(" attempted duplicate %s definition for %s. (%s)",1656
k->external_kind(), k->external_name(), k->class_in_module_of_loader(false, true));
1662
if (throwException == false) {1663
if (LoaderConstraintTable::check_or_update(k, loader_data, name) == false) {1664
throwException = true;
1665
ss.print("loader constraint violation: loader %s", loader_data->loader_name_and_id());1666
ss.print(" wants to load %s %s.",1667
k->external_kind(), k->external_name());
1668
Klass *existing_klass = LoaderConstraintTable::find_constrained_klass(name, loader_data);
1669
if (existing_klass != nullptr && existing_klass->class_loader_data() != loader_data) {1670
ss.print(" A different %s with the same name was previously loaded by %s. (%s)",1671
existing_klass->external_kind(),
1672
existing_klass->class_loader_data()->loader_name_and_id(),
1673
existing_klass->class_in_module_of_loader(false, true));
1675
ss.print(" (%s)", k->class_in_module_of_loader(false, true));1681
// Throw error now if needed (cannot throw while holding
1682
// SystemDictionary_lock because of rank ordering)
1683
if (throwException == true) {1684
THROW_MSG(vmSymbols::java_lang_LinkageError(), ss.as_string());
1688
// Update class loader data dictionary - done after check_constraint and add_to_hierarchy
1690
void SystemDictionary::update_dictionary(JavaThread* current,
1692
ClassLoaderData* loader_data) {1693
MonitorLocker mu1(SystemDictionary_lock);
1695
// Make a new dictionary entry.
1696
Symbol* name = k->name();
1697
Dictionary* dictionary = loader_data->dictionary();
1698
InstanceKlass* sd_check = dictionary->find_class(current, name);
1699
if (sd_check == nullptr) {1700
dictionary->add_klass(current, name, k);
1706
// Try to find a class name using the loader constraints. The
1707
// loader constraints might know about a class that isn't fully loaded
1708
// yet and these will be ignored.
1709
Klass* SystemDictionary::find_constrained_instance_or_array_klass(
1710
Thread* current, Symbol* class_name, Handle class_loader) {1712
// First see if it has been loaded directly.
1713
// Force the protection domain to be null. (This removes protection checks.)
1714
Handle no_protection_domain;
1715
Klass* klass = find_instance_or_array_klass(current, class_name, class_loader,
1716
no_protection_domain);
1717
if (klass != nullptr)
1720
// Now look to see if it has been loaded elsewhere, and is subject to
1721
// a loader constraint that would require this loader to return the
1722
// klass that is already loaded.
1723
if (Signature::is_array(class_name)) {1724
// For array classes, their Klass*s are not kept in the
1725
// constraint table. The element Klass*s are.
1726
SignatureStream ss(class_name, false);
1727
int ndims = ss.skip_array_prefix(); // skip all '['s
1728
BasicType t = ss.type();
1729
if (t != T_OBJECT) {1730
klass = Universe::typeArrayKlass(t);
1732
MutexLocker mu(current, SystemDictionary_lock);
1733
klass = LoaderConstraintTable::find_constrained_klass(ss.as_symbol(), class_loader_data(class_loader));
1735
// If element class already loaded, allocate array klass
1736
if (klass != nullptr) {1737
klass = klass->array_klass_or_null(ndims);
1740
MutexLocker mu(current, SystemDictionary_lock);
1741
// Non-array classes are easy: simply check the constraint table.
1742
klass = LoaderConstraintTable::find_constrained_klass(class_name, class_loader_data(class_loader));
1748
bool SystemDictionary::add_loader_constraint(Symbol* class_name,
1749
Klass* klass_being_linked,
1750
Handle class_loader1,
1751
Handle class_loader2) {1752
ClassLoaderData* loader_data1 = class_loader_data(class_loader1);
1753
ClassLoaderData* loader_data2 = class_loader_data(class_loader2);
1755
Symbol* constraint_name = nullptr;
1757
if (!Signature::is_array(class_name)) {1758
constraint_name = class_name;
1760
// For array classes, their Klass*s are not kept in the
1761
// constraint table. The element classes are.
1762
SignatureStream ss(class_name, false);
1763
ss.skip_array_prefix(); // skip all '['s
1764
if (!ss.has_envelope()) {1765
return true; // primitive types always pass
1767
constraint_name = ss.as_symbol();
1768
// Increment refcount to keep constraint_name alive after
1769
// SignatureStream is destructed. It will be decremented below
1770
// before returning.
1771
constraint_name->increment_refcount();
1774
Dictionary* dictionary1 = loader_data1->dictionary();
1775
Dictionary* dictionary2 = loader_data2->dictionary();
1777
JavaThread* current = JavaThread::current();
1779
MutexLocker mu_s(SystemDictionary_lock);
1780
InstanceKlass* klass1 = dictionary1->find_class(current, constraint_name);
1781
InstanceKlass* klass2 = dictionary2->find_class(current, constraint_name);
1782
bool result = LoaderConstraintTable::add_entry(constraint_name, klass1, loader_data1,
1783
klass2, loader_data2);
1785
if (CDSConfig::is_dumping_archive() && klass_being_linked != nullptr &&
1786
!klass_being_linked->is_shared()) {1787
SystemDictionaryShared::record_linking_constraint(constraint_name,
1788
InstanceKlass::cast(klass_being_linked),
1789
class_loader1, class_loader2);
1791
#endif // INCLUDE_CDS
1792
if (Signature::is_array(class_name)) {1793
constraint_name->decrement_refcount();
1799
// Add entry to resolution error table to record the error when the first
1800
// attempt to resolve a reference to a class has failed.
1801
void SystemDictionary::add_resolution_error(const constantPoolHandle& pool, int which,
1802
Symbol* error, const char* message,
1803
Symbol* cause, const char* cause_msg) {1805
MutexLocker ml(Thread::current(), SystemDictionary_lock);
1806
ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1807
if (entry == nullptr) {1808
ResolutionErrorTable::add_entry(pool, which, error, message, cause, cause_msg);
1813
// Delete a resolution error for RedefineClasses for a constant pool is going away
1814
void SystemDictionary::delete_resolution_error(ConstantPool* pool) {1815
ResolutionErrorTable::delete_entry(pool);
1818
// Lookup resolution error table. Returns error if found, otherwise null.
1819
Symbol* SystemDictionary::find_resolution_error(const constantPoolHandle& pool, int which,
1820
const char** message,
1821
Symbol** cause, const char** cause_msg) {1824
MutexLocker ml(Thread::current(), SystemDictionary_lock);
1825
ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1826
if (entry != nullptr) {1827
*message = entry->message();
1828
*cause = entry->cause();
1829
*cause_msg = entry->cause_msg();
1830
return entry->error();
1837
// Add an entry to resolution error table to record an error in resolving or
1838
// validating a nest host. This is used to construct informative error
1839
// messages when IllegalAccessError's occur. If an entry already exists it will
1840
// be updated with the nest host error message.
1842
void SystemDictionary::add_nest_host_error(const constantPoolHandle& pool,
1844
const char* message) {1846
MutexLocker ml(Thread::current(), SystemDictionary_lock);
1847
ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1848
if (entry != nullptr && entry->nest_host_error() == nullptr) {1849
// An existing entry means we had a true resolution failure (LinkageError) with our nest host, but we
1850
// still want to add the error message for the higher-level access checks to report. We should
1851
// only reach here under the same error condition, so we can ignore the potential race with setting
1852
// the message. If we see it is already set then we can ignore it.
1853
entry->set_nest_host_error(message);
1855
ResolutionErrorTable::add_entry(pool, which, message);
1860
// Lookup any nest host error
1861
const char* SystemDictionary::find_nest_host_error(const constantPoolHandle& pool, int which) {1863
MutexLocker ml(Thread::current(), SystemDictionary_lock);
1864
ResolutionErrorEntry* entry = ResolutionErrorTable::find_entry(pool, which);
1865
if (entry != nullptr) {1866
return entry->nest_host_error();
1873
// Signature constraints ensure that callers and callees agree about
1874
// the meaning of type names in their signatures. This routine is the
1875
// intake for constraints. It collects them from several places:
1877
// * LinkResolver::resolve_method (if check_access is true) requires
1878
// that the resolving class (the caller) and the defining class of
1879
// the resolved method (the callee) agree on each type in the
1880
// method's signature.
1882
// * LinkResolver::resolve_interface_method performs exactly the same
1885
// * LinkResolver::resolve_field requires that the constant pool
1886
// attempting to link to a field agree with the field's defining
1887
// class about the type of the field signature.
1889
// * klassVtable::initialize_vtable requires that, when a class
1890
// overrides a vtable entry allocated by a superclass, that the
1891
// overriding method (i.e., the callee) agree with the superclass
1892
// on each type in the method's signature.
1894
// * klassItable::initialize_itable requires that, when a class fills
1895
// in its itables, for each non-abstract method installed in an
1896
// itable, the method (i.e., the callee) agree with the interface
1897
// on each type in the method's signature.
1899
// All those methods have a boolean (check_access, checkconstraints)
1900
// which turns off the checks. This is used from specialized contexts
1901
// such as bootstrapping, dumping, and debugging.
1903
// No direct constraint is placed between the class and its
1904
// supertypes. Constraints are only placed along linked relations
1905
// between callers and callees. When a method overrides or implements
1906
// an abstract method in a supertype (superclass or interface), the
1907
// constraints are placed as if the supertype were the caller to the
1908
// overriding method. (This works well, since callers to the
1909
// supertype have already established agreement between themselves and
1910
// the supertype.) As a result of all this, a class can disagree with
1911
// its supertype about the meaning of a type name, as long as that
1912
// class neither calls a relevant method of the supertype, nor is
1913
// called (perhaps via an override) from the supertype.
1916
// SystemDictionary::check_signature_loaders(sig, klass_being_linked, l1, l2)
1918
// Make sure all class components (including arrays) in the given
1919
// signature will be resolved to the same class in both loaders.
1920
// Returns the name of the type that failed a loader constraint check, or
1921
// null if no constraint failed. No exception except OOME is thrown.
1922
// Arrays are not added to the loader constraint table, their elements are.
1923
Symbol* SystemDictionary::check_signature_loaders(Symbol* signature,
1924
Klass* klass_being_linked,
1925
Handle loader1, Handle loader2,
1927
// Nothing to do if loaders are the same.
1928
if (loader1() == loader2()) {1932
for (SignatureStream ss(signature, is_method); !ss.is_done(); ss.next()) {1933
if (ss.is_reference()) {1934
Symbol* sig = ss.as_symbol();
1935
// Note: In the future, if template-like types can take
1936
// arguments, we will want to recognize them and dig out class
1937
// names hiding inside the argument lists.
1938
if (!add_loader_constraint(sig, klass_being_linked, loader1, loader2)) {1946
Method* SystemDictionary::find_method_handle_intrinsic(vmIntrinsicID iid,
1950
const int iid_as_int = vmIntrinsics::as_int(iid);
1951
assert(MethodHandles::is_signature_polymorphic(iid) &&
1952
MethodHandles::is_signature_polymorphic_intrinsic(iid) &&
1953
iid != vmIntrinsics::_invokeGeneric,
1954
"must be a known MH intrinsic iid=%d: %s", iid_as_int, vmIntrinsics::name_at(iid));
1956
InvokeMethodKey key(signature, iid_as_int);
1957
Method** met = nullptr;
1959
// We only want one entry in the table for this (signature/id, method) pair but the code
1960
// to create the intrinsic method needs to be outside the lock.
1961
// The first thread claims the entry by adding the key and the other threads wait, until the
1962
// Method has been added as the value.
1964
MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1967
met = _invoke_method_intrinsic_table->put_if_absent(key, &created);
1968
assert(met != nullptr, "either created or found");
1969
if (*met != nullptr) {1971
} else if (created) {1972
// The current thread won the race and will try to create the full entry.
1975
// Another thread beat us to it, so wait for them to complete
1976
// and return *met; or if they hit an error we get another try.
1978
// Note it is not safe to read *met here as that entry could have
1979
// been deleted, so we must loop and try put_if_absent again.
1984
methodHandle m = Method::make_method_handle_intrinsic(iid, signature, THREAD);
1985
bool throw_error = HAS_PENDING_EXCEPTION;
1986
if (!throw_error && (!Arguments::is_interpreter_only() || iid == vmIntrinsics::_linkToNative)) {1987
// Generate a compiled form of the MH intrinsic
1988
// linkToNative doesn't have interpreter-specific implementation, so always has to go through compiled version.
1989
AdapterHandlerLibrary::create_native_wrapper(m);
1990
// Check if have the compiled code.
1991
throw_error = (!m->has_compiled_code());
1995
MonitorLocker ml(THREAD, InvokeMethodIntrinsicTable_lock);
1997
// Remove the entry and let another thread try, or get the same exception.
1998
bool removed = _invoke_method_intrinsic_table->remove(key);
1999
assert(removed, "must be the owner");
2002
signature->make_permanent(); // The signature is never unloaded.
2003
assert(Arguments::is_interpreter_only() || (m->has_compiled_code() &&
2004
m->code()->entry_point() == m->from_compiled_entry()),
2005
"MH intrinsic invariant");
2006
*met = m(); // insert the element
2012
// Throw OOM or the pending exception in the JavaThread
2013
if (throw_error && !HAS_PENDING_EXCEPTION) {2014
THROW_MSG_NULL(vmSymbols::java_lang_OutOfMemoryError(),
2015
"Out of space in CodeCache for method handle intrinsic");
2020
// Helper for unpacking the return value from linkMethod and linkCallSite.
2021
static Method* unpack_method_and_appendix(Handle mname,
2022
Klass* accessing_klass,
2023
objArrayHandle appendix_box,
2024
Handle* appendix_result,
2026
if (mname.not_null()) {2027
Method* m = java_lang_invoke_MemberName::vmtarget(mname());
2029
oop appendix = appendix_box->obj_at(0);
2030
LogTarget(Info, methodhandles) lt;
2031
if (lt.develop_is_enabled()) {2032
ResourceMark rm(THREAD);
2034
ls.print("Linked method=" INTPTR_FORMAT ": ", p2i(m));2036
if (appendix != nullptr) { ls.print("appendix = "); appendix->print_on(&ls); }2040
(*appendix_result) = Handle(THREAD, appendix);
2041
// the target is stored in the cpCache and if a reference to this
2042
// MemberName is dropped we need a way to make sure the
2043
// class_loader containing this method is kept alive.
2044
methodHandle mh(THREAD, m); // record_dependency can safepoint.
2045
ClassLoaderData* this_key = accessing_klass->class_loader_data();
2046
this_key->record_dependency(m->method_holder());
2050
THROW_MSG_NULL(vmSymbols::java_lang_LinkageError(), "bad value from MethodHandleNatives");
2053
Method* SystemDictionary::find_method_handle_invoker(Klass* klass,
2056
Klass* accessing_klass,
2057
Handle* appendix_result,
2059
guarantee(THREAD->can_call_java(), "");
2060
Handle method_type =
2061
SystemDictionary::find_method_handle_type(signature, accessing_klass, CHECK_NULL);
2063
int ref_kind = JVM_REF_invokeVirtual;
2064
oop name_oop = StringTable::intern(name, CHECK_NULL);
2065
Handle name_str (THREAD, name_oop);
2066
objArrayHandle appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK_NULL);
2067
assert(appendix_box->obj_at(0) == nullptr, "");
2069
// This should not happen. JDK code should take care of that.
2070
if (accessing_klass == nullptr || method_type.is_null()) {2071
THROW_MSG_NULL(vmSymbols::java_lang_InternalError(), "bad invokehandle");
2074
// call java.lang.invoke.MethodHandleNatives::linkMethod(... String, MethodType) -> MemberName
2075
JavaCallArguments args;
2076
args.push_oop(Handle(THREAD, accessing_klass->java_mirror()));
2077
args.push_int(ref_kind);
2078
args.push_oop(Handle(THREAD, klass->java_mirror()));
2079
args.push_oop(name_str);
2080
args.push_oop(method_type);
2081
args.push_oop(appendix_box);
2082
JavaValue result(T_OBJECT);
2083
JavaCalls::call_static(&result,
2084
vmClasses::MethodHandleNatives_klass(),
2085
vmSymbols::linkMethod_name(),
2086
vmSymbols::linkMethod_signature(),
2088
Handle mname(THREAD, result.get_oop());
2089
return unpack_method_and_appendix(mname, accessing_klass, appendix_box, appendix_result, THREAD);
2092
// Decide if we can globally cache a lookup of this class, to be returned to any client that asks.
2093
// We must ensure that all class loaders everywhere will reach this class, for any client.
2094
// This is a safe bet for public classes in java.lang, such as Object and String.
2095
// We also include public classes in java.lang.invoke, because they appear frequently in system-level method types.
2096
// Out of an abundance of caution, we do not include any other classes, not even for packages like java.util.
2097
static bool is_always_visible_class(oop mirror) {2098
Klass* klass = java_lang_Class::as_Klass(mirror);
2099
if (klass->is_objArray_klass()) {2100
klass = ObjArrayKlass::cast(klass)->bottom_klass(); // check element type
2102
if (klass->is_typeArray_klass()) {2103
return true; // primitive array
2105
assert(klass->is_instance_klass(), "%s", klass->external_name());
2106
return klass->is_public() &&
2107
(InstanceKlass::cast(klass)->is_same_class_package(vmClasses::Object_klass()) || // java.lang
2108
InstanceKlass::cast(klass)->is_same_class_package(vmClasses::MethodHandle_klass())); // java.lang.invoke
2111
// Find or construct the Java mirror (java.lang.Class instance) for
2112
// the given field type signature, as interpreted relative to the
2113
// given class loader. Handles primitives, void, references, arrays,
2114
// and all other reflectable types, except method types.
2115
// N.B. Code in reflection should use this entry point.
2116
Handle SystemDictionary::find_java_mirror_for_type(Symbol* signature,
2117
Klass* accessing_klass,
2118
Handle class_loader,
2119
Handle protection_domain,
2120
SignatureStream::FailureMode failure_mode,
2122
assert(accessing_klass == nullptr || (class_loader.is_null() && protection_domain.is_null()),
2123
"one or the other, or perhaps neither");
2125
// What we have here must be a valid field descriptor,
2126
// and all valid field descriptors are supported.
2127
// Produce the same java.lang.Class that reflection reports.
2128
if (accessing_klass != nullptr) {2129
class_loader = Handle(THREAD, accessing_klass->class_loader());
2130
protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2132
ResolvingSignatureStream ss(signature, class_loader, protection_domain, false);
2133
oop mirror_oop = ss.as_java_mirror(failure_mode, CHECK_NH);
2134
if (mirror_oop == nullptr) {2135
return Handle(); // report failure this way
2137
Handle mirror(THREAD, mirror_oop);
2139
if (accessing_klass != nullptr) {2140
// Check accessibility, emulating ConstantPool::verify_constant_pool_resolve.
2141
Klass* sel_klass = java_lang_Class::as_Klass(mirror());
2142
if (sel_klass != nullptr) {2143
LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_NH);
2150
// Ask Java code to find or construct a java.lang.invoke.MethodType for the given
2151
// signature, as interpreted relative to the given class loader.
2152
// Because of class loader constraints, all method handle usage must be
2153
// consistent with this loader.
2154
Handle SystemDictionary::find_method_handle_type(Symbol* signature,
2155
Klass* accessing_klass,
2160
MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2161
o = _invoke_method_type_table->get(signature);
2165
oop mt = o->resolve();
2166
assert(java_lang_invoke_MethodType::is_instance(mt), "");
2167
return Handle(THREAD, mt);
2168
} else if (!THREAD->can_call_java()) {2169
warning("SystemDictionary::find_method_handle_type called from compiler thread"); // FIXME2170
return Handle(); // do not attempt from within compiler, unless it was cached
2173
Handle class_loader, protection_domain;
2174
if (accessing_klass != nullptr) {2175
class_loader = Handle(THREAD, accessing_klass->class_loader());
2176
protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2178
bool can_be_cached = true;
2179
int npts = ArgumentCount(signature).size();
2180
objArrayHandle pts = oopFactory::new_objArray_handle(vmClasses::Class_klass(), npts, CHECK_(empty));
2182
Handle rt; // the return type from the signature
2183
ResourceMark rm(THREAD);
2184
for (SignatureStream ss(signature); !ss.is_done(); ss.next()) {2185
oop mirror = nullptr;
2186
if (can_be_cached) {2187
// Use neutral class loader to lookup candidate classes to be placed in the cache.
2188
mirror = ss.as_java_mirror(Handle(), Handle(),
2189
SignatureStream::ReturnNull, CHECK_(empty));
2190
if (mirror == nullptr || (ss.is_reference() && !is_always_visible_class(mirror))) {2191
// Fall back to accessing_klass context.
2192
can_be_cached = false;
2195
if (!can_be_cached) {2196
// Resolve, throwing a real error if it doesn't work.
2197
mirror = ss.as_java_mirror(class_loader, protection_domain,
2198
SignatureStream::NCDFError, CHECK_(empty));
2200
assert(mirror != nullptr, "%s", ss.as_symbol()->as_C_string());
2201
if (ss.at_return_type())
2202
rt = Handle(THREAD, mirror);
2204
pts->obj_at_put(arg++, mirror);
2206
// Check accessibility.
2207
if (!java_lang_Class::is_primitive(mirror) && accessing_klass != nullptr) {2208
Klass* sel_klass = java_lang_Class::as_Klass(mirror);
2209
mirror = nullptr; // safety
2210
// Emulate ConstantPool::verify_constant_pool_resolve.
2211
LinkResolver::check_klass_accessibility(accessing_klass, sel_klass, CHECK_(empty));
2214
assert(arg == npts, "");
2216
// call java.lang.invoke.MethodHandleNatives::findMethodHandleType(Class rt, Class[] pts) -> MethodType
2217
JavaCallArguments args(Handle(THREAD, rt()));
2219
JavaValue result(T_OBJECT);
2220
JavaCalls::call_static(&result,
2221
vmClasses::MethodHandleNatives_klass(),
2222
vmSymbols::findMethodHandleType_name(),
2223
vmSymbols::findMethodHandleType_signature(),
2224
&args, CHECK_(empty));
2225
Handle method_type(THREAD, result.get_oop());
2227
if (can_be_cached) {2228
// We can cache this MethodType inside the JVM.
2229
MutexLocker ml(THREAD, InvokeMethodTypeTable_lock);
2230
bool created = false;
2231
assert(method_type != nullptr, "unexpected null");
2232
OopHandle* h = _invoke_method_type_table->get(signature);
2234
signature->make_permanent(); // The signature is never unloaded.
2235
OopHandle elem = OopHandle(Universe::vm_global(), method_type());
2236
bool created = _invoke_method_type_table->put(signature, elem);
2237
assert(created, "better be created");
2240
// report back to the caller with the MethodType
2244
Handle SystemDictionary::find_field_handle_type(Symbol* signature,
2245
Klass* accessing_klass,
2248
ResourceMark rm(THREAD);
2249
SignatureStream ss(signature, /*is_method=*/ false);
2250
if (!ss.is_done()) {2251
Handle class_loader, protection_domain;
2252
if (accessing_klass != nullptr) {2253
class_loader = Handle(THREAD, accessing_klass->class_loader());
2254
protection_domain = Handle(THREAD, accessing_klass->protection_domain());
2256
oop mirror = ss.as_java_mirror(class_loader, protection_domain, SignatureStream::NCDFError, CHECK_(empty));
2259
return Handle(THREAD, mirror);
2265
// Ask Java code to find or construct a method handle constant.
2266
Handle SystemDictionary::link_method_handle_constant(Klass* caller,
2267
int ref_kind, //e.g., JVM_REF_invokeVirtual
2273
if (caller == nullptr) {2274
THROW_MSG_(vmSymbols::java_lang_InternalError(), "bad MH constant", empty);
2276
Handle name_str = java_lang_String::create_from_symbol(name, CHECK_(empty));
2277
Handle signature_str = java_lang_String::create_from_symbol(signature, CHECK_(empty));
2279
// Put symbolic info from the MH constant into freshly created MemberName and resolve it.
2280
Handle mname = vmClasses::MemberName_klass()->allocate_instance_handle(CHECK_(empty));
2281
java_lang_invoke_MemberName::set_clazz(mname(), callee->java_mirror());
2282
java_lang_invoke_MemberName::set_name (mname(), name_str());
2283
java_lang_invoke_MemberName::set_type (mname(), signature_str());
2284
java_lang_invoke_MemberName::set_flags(mname(), MethodHandles::ref_kind_to_flags(ref_kind));
2286
if (ref_kind == JVM_REF_invokeVirtual &&
2287
MethodHandles::is_signature_polymorphic_public_name(callee, name)) {2288
// Skip resolution for public signature polymorphic methods such as
2289
// j.l.i.MethodHandle.invoke()/invokeExact() and those on VarHandle
2290
// They require appendix argument which MemberName resolution doesn't handle.
2291
// There's special logic on JDK side to handle them
2292
// (see MethodHandles.linkMethodHandleConstant() and MethodHandles.findVirtualForMH()).
2294
MethodHandles::resolve_MemberName(mname, caller, 0, false /*speculative_resolve*/, CHECK_(empty));
2297
// After method/field resolution succeeded, it's safe to resolve MH signature as well.
2298
Handle type = MethodHandles::resolve_MemberName_type(mname, caller, CHECK_(empty));
2300
// call java.lang.invoke.MethodHandleNatives::linkMethodHandleConstant(Class caller, int refKind, Class callee, String name, Object type) -> MethodHandle
2301
JavaCallArguments args;
2302
args.push_oop(Handle(THREAD, caller->java_mirror())); // the referring class
2303
args.push_int(ref_kind);
2304
args.push_oop(Handle(THREAD, callee->java_mirror())); // the target class
2305
args.push_oop(name_str);
2306
args.push_oop(type);
2307
JavaValue result(T_OBJECT);
2308
JavaCalls::call_static(&result,
2309
vmClasses::MethodHandleNatives_klass(),
2310
vmSymbols::linkMethodHandleConstant_name(),
2311
vmSymbols::linkMethodHandleConstant_signature(),
2312
&args, CHECK_(empty));
2313
return Handle(THREAD, result.get_oop());
2316
// Ask Java to run a bootstrap method, in order to create a dynamic call site
2317
// while linking an invokedynamic op, or compute a constant for Dynamic_info CP entry
2318
// with linkage results being stored back into the bootstrap specifier.
2319
void SystemDictionary::invoke_bootstrap_method(BootstrapInfo& bootstrap_specifier, TRAPS) {2320
// Resolve the bootstrap specifier, its name, type, and static arguments
2321
bootstrap_specifier.resolve_bsm(CHECK);
2323
// This should not happen. JDK code should take care of that.
2324
if (bootstrap_specifier.caller() == nullptr || bootstrap_specifier.type_arg().is_null()) {2325
THROW_MSG(vmSymbols::java_lang_InternalError(), "Invalid bootstrap method invocation with no caller or type argument");
2328
bool is_indy = bootstrap_specifier.is_method_call();
2329
objArrayHandle appendix_box;
2331
// Some method calls may require an appendix argument. Arrange to receive it.
2332
appendix_box = oopFactory::new_objArray_handle(vmClasses::Object_klass(), 1, CHECK);
2333
assert(appendix_box->obj_at(0) == nullptr, "");
2336
// call condy: java.lang.invoke.MethodHandleNatives::linkDynamicConstant(caller, bsm, type, info)
2337
// indy: java.lang.invoke.MethodHandleNatives::linkCallSite(caller, bsm, name, mtype, info, &appendix)
2338
JavaCallArguments args;
2339
args.push_oop(Handle(THREAD, bootstrap_specifier.caller_mirror()));
2340
args.push_oop(bootstrap_specifier.bsm());
2341
args.push_oop(bootstrap_specifier.name_arg());
2342
args.push_oop(bootstrap_specifier.type_arg());
2343
args.push_oop(bootstrap_specifier.arg_values());
2345
args.push_oop(appendix_box);
2347
JavaValue result(T_OBJECT);
2348
JavaCalls::call_static(&result,
2349
vmClasses::MethodHandleNatives_klass(),
2350
is_indy ? vmSymbols::linkCallSite_name() : vmSymbols::linkDynamicConstant_name(),
2351
is_indy ? vmSymbols::linkCallSite_signature() : vmSymbols::linkDynamicConstant_signature(),
2354
Handle value(THREAD, result.get_oop());
2357
Method* method = unpack_method_and_appendix(value,
2358
bootstrap_specifier.caller(),
2361
methodHandle mh(THREAD, method);
2362
bootstrap_specifier.set_resolved_method(mh, appendix);
2364
bootstrap_specifier.set_resolved_value(value);
2368
assert(bootstrap_specifier.is_resolved() ||
2369
(bootstrap_specifier.is_method_call() &&
2370
bootstrap_specifier.resolved_method().not_null()), "bootstrap method call failed");
2374
bool SystemDictionary::is_nonpublic_Object_method(Method* m) {2375
assert(m != nullptr, "Unexpected nullptr Method*");
2376
return !m->is_public() && m->method_holder() == vmClasses::Object_klass();
2379
// ----------------------------------------------------------------------------
2381
void SystemDictionary::print_on(outputStream *st) {2382
CDS_ONLY(SystemDictionaryShared::print_on(st));
2383
GCMutexLocker mu(SystemDictionary_lock);
2385
ClassLoaderDataGraph::print_dictionary(st);
2388
PlaceholderTable::print_on(st);
2391
// loader constraints - print under SD_lock
2392
LoaderConstraintTable::print_on(st);
2395
ProtectionDomainCacheTable::print_on(st);
2399
void SystemDictionary::print() { print_on(tty); }2401
void SystemDictionary::verify() {2403
GCMutexLocker mu(SystemDictionary_lock);
2405
// Verify dictionary
2406
ClassLoaderDataGraph::verify_dictionary();
2408
// Verify constraint table
2409
LoaderConstraintTable::verify();
2411
// Verify protection domain table
2412
ProtectionDomainCacheTable::verify();
2415
void SystemDictionary::dump(outputStream *st, bool verbose) {2416
assert_locked_or_safepoint(SystemDictionary_lock);
2420
CDS_ONLY(SystemDictionaryShared::print_table_statistics(st));
2421
ClassLoaderDataGraph::print_table_statistics(st);
2422
LoaderConstraintTable::print_table_statistics(st);
2423
ProtectionDomainCacheTable::print_table_statistics(st);
2427
// Utility for dumping dictionaries.
2428
SystemDictionaryDCmd::SystemDictionaryDCmd(outputStream* output, bool heap) :
2429
DCmdWithParser(output, heap),
2430
_verbose("-verbose", "Dump the content of each dictionary entry for all class loaders",2431
"BOOLEAN", false, "false") {2432
_dcmdparser.add_dcmd_option(&_verbose);
2435
void SystemDictionaryDCmd::execute(DCmdSource source, TRAPS) {2436
VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSysDict,
2438
VMThread::execute(&dumper);