1 /*
2 * Copyright (c) 2003, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "classfile/classLoaderDataGraph.hpp"
26 #include "classfile/javaClasses.inline.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/vmClasses.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "gc/shared/collectedHeap.hpp"
31 #include "jvmtifiles/jvmtiEnv.hpp"
32 #include "logging/log.hpp"
33 #include "memory/allocation.inline.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "memory/universe.hpp"
36 #include "oops/access.inline.hpp"
37 #include "oops/arrayOop.hpp"
38 #include "oops/constantPool.inline.hpp"
39 #include "oops/instanceMirrorKlass.hpp"
40 #include "oops/klass.inline.hpp"
41 #include "oops/objArrayKlass.hpp"
42 #include "oops/objArrayOop.inline.hpp"
43 #include "oops/oop.inline.hpp"
44 #include "oops/typeArrayOop.inline.hpp"
45 #include "prims/jvmtiEventController.hpp"
46 #include "prims/jvmtiEventController.inline.hpp"
47 #include "prims/jvmtiExport.hpp"
48 #include "prims/jvmtiImpl.hpp"
49 #include "prims/jvmtiTagMap.hpp"
50 #include "prims/jvmtiTagMapTable.hpp"
51 #include "prims/jvmtiThreadState.hpp"
52 #include "runtime/continuationWrapper.inline.hpp"
53 #include "runtime/deoptimization.hpp"
54 #include "runtime/frame.inline.hpp"
55 #include "runtime/handles.inline.hpp"
56 #include "runtime/interfaceSupport.inline.hpp"
57 #include "runtime/javaCalls.hpp"
58 #include "runtime/javaThread.inline.hpp"
59 #include "runtime/jniHandles.inline.hpp"
60 #include "runtime/mutex.hpp"
61 #include "runtime/mutexLocker.hpp"
62 #include "runtime/reflectionUtils.hpp"
63 #include "runtime/safepoint.hpp"
64 #include "runtime/timerTrace.hpp"
65 #include "runtime/threadSMR.hpp"
66 #include "runtime/vframe.hpp"
67 #include "runtime/vmThread.hpp"
68 #include "runtime/vmOperations.hpp"
69 #include "utilities/objectBitSet.inline.hpp"
70 #include "utilities/macros.hpp"
71
72 typedef ObjectBitSet<mtServiceability> JVMTIBitSet;
73
74
75 // Helper class to store objects to visit.
76 class JvmtiHeapwalkVisitStack {
77 private:
78 enum {
79 initial_visit_stack_size = 4000
80 };
81
82 GrowableArray<JvmtiHeapwalkObject>* _visit_stack;
83 JVMTIBitSet _bitset;
84
85 static GrowableArray<JvmtiHeapwalkObject>* create_visit_stack() {
86 return new (mtServiceability) GrowableArray<JvmtiHeapwalkObject>(initial_visit_stack_size, mtServiceability);
87 }
88
89 public:
90 JvmtiHeapwalkVisitStack(): _visit_stack(create_visit_stack()) {
91 }
92 ~JvmtiHeapwalkVisitStack() {
93 if (_visit_stack != nullptr) {
94 delete _visit_stack;
95 }
96 }
97
98 bool is_empty() const {
99 return _visit_stack->is_empty();
100 }
101
102 void push(const JvmtiHeapwalkObject& obj) {
103 _visit_stack->push(obj);
104 }
105
106 // If the object hasn't been visited then push it onto the visit stack
107 // so that it will be visited later.
108 void check_for_visit(const JvmtiHeapwalkObject& obj) {
109 if (!is_visited(obj)) {
110 _visit_stack->push(obj);
111 }
112 }
113
114 JvmtiHeapwalkObject pop() {
115 return _visit_stack->pop();
116 }
117
118 bool is_visited(const JvmtiHeapwalkObject& obj) /*const*/ { // TODO: _bitset.is_marked() should be const
119 // The method is called only for objects from visit_stack to ensure an object is not visited twice.
120 // Flat objects can be added to visit_stack only when we visit their holder object, so we cannot get duplicate reference to it.
121 if (obj.is_flat()) {
122 return false;
123 }
124 return _bitset.is_marked(obj.obj());
125 }
126
127 void mark_visited(const JvmtiHeapwalkObject& obj) {
128 if (!obj.is_flat()) {
129 _bitset.mark_obj(obj.obj());
130 }
131 }
132 };
133
134
135 bool JvmtiTagMap::_has_object_free_events = false;
136
137 // create a JvmtiTagMap
138 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
139 _env(env),
140 _lock(Mutex::nosafepoint, "JvmtiTagMap_lock"),
141 _needs_cleaning(false),
142 _posting_events(false),
143 _converting_flat_object(false) {
144
145 assert(JvmtiThreadState_lock->is_locked(), "sanity check");
146 assert(((JvmtiEnvBase *)env)->tag_map() == nullptr, "tag map already exists for environment");
147
148 _hashmap = new JvmtiTagMapTable();
149 _flat_hashmap = new JvmtiFlatTagMapTable();
150
151 // finally add us to the environment
152 ((JvmtiEnvBase *)env)->release_set_tag_map(this);
153 }
154
155 // destroy a JvmtiTagMap
156 JvmtiTagMap::~JvmtiTagMap() {
157
158 // no lock acquired as we assume the enclosing environment is
159 // also being destroyed.
160 ((JvmtiEnvBase *)_env)->set_tag_map(nullptr);
161
162 // finally destroy the hashmap
163 delete _hashmap;
164 _hashmap = nullptr;
165 delete _flat_hashmap;
166 }
167
168 // Called by env_dispose() to reclaim memory before deallocation.
169 // Remove all the entries but keep the empty table intact.
170 // This needs the table lock.
171 void JvmtiTagMap::clear() {
172 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
173 _hashmap->clear();
174 _flat_hashmap->clear();
175 }
176
177 // returns the tag map for the given environments. If the tag map
178 // doesn't exist then it is created.
179 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
180 JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map_acquire();
181 if (tag_map == nullptr) {
182 MutexLocker mu(JvmtiThreadState_lock);
183 tag_map = ((JvmtiEnvBase*)env)->tag_map();
184 if (tag_map == nullptr) {
185 tag_map = new JvmtiTagMap(env);
186 }
187 } else {
188 DEBUG_ONLY(JavaThread::current()->check_possible_safepoint());
189 }
190 return tag_map;
191 }
192
193 // returns true if the hashmaps are empty
194 bool JvmtiTagMap::is_empty() const {
195 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
196 return _hashmap->is_empty() && _flat_hashmap->is_empty();
197 }
198
199 // This checks for posting before operations that use
200 // this tagmap table.
201 void JvmtiTagMap::check_hashmap(GrowableArray<jlong>* objects) {
202 assert(is_locked(), "checking");
203
204 if (is_empty()) { return; }
205
206 if (_needs_cleaning &&
207 objects != nullptr &&
208 env()->is_enabled(JVMTI_EVENT_OBJECT_FREE)) {
209 remove_dead_entries_locked(objects);
210 }
211 }
212
213 // This checks for posting and is called from the heap walks.
214 void JvmtiTagMap::check_hashmaps_for_heapwalk(GrowableArray<jlong>* objects) {
215 assert(SafepointSynchronize::is_at_safepoint(), "called from safepoints");
216
217 // Verify that the tag map tables are valid and unconditionally post events
218 // that are expected to be posted before gc_notification.
219 JvmtiEnvIterator it;
220 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) {
221 JvmtiTagMap* tag_map = env->tag_map_acquire();
222 if (tag_map != nullptr) {
223 // The ZDriver may be walking the hashmaps concurrently so this lock is needed.
224 MutexLocker ml(tag_map->lock(), Mutex::_no_safepoint_check_flag);
225 tag_map->check_hashmap(objects);
226 }
227 }
228 }
229
230 // Converts entries from JvmtiFlatTagMapTable to JvmtiTagMapTable in batches.
231 // 1. (JvmtiTagMap is locked)
232 // reads entries from JvmtiFlatTagMapTable (describe flat value objects);
233 // 2. (JvmtiTagMap is unlocked)
234 // creates heap-allocated copies of the flat object;
235 // 3. (JvmtiTagMap is locked)
236 // ensures source entry still exists, removes it from JvmtiFlatTagMapTable, adds new entry to JvmtiTagMapTable.
237 // If some error occurs in step 2 (OOM?), the process stops.
238 class JvmtiTagMapFlatEntryConverter: public StackObj {
239 private:
240 struct Entry {
241 // source flat value object
242 Handle holder;
243 int offset;
244 InlineKlass* inline_klass;
245 LayoutKind layout_kind;
246 // converted heap-allocated object
247 Handle dst;
248
249 Entry(): holder(), offset(0), inline_klass(nullptr), dst() {}
250 Entry(Handle holder, int offset, InlineKlass* inline_klass, LayoutKind lk)
251 : holder(holder), offset(offset), inline_klass(inline_klass), layout_kind(lk), dst() {}
252 };
253
254 int _batch_size;
255 GrowableArray<Entry> _entries;
256 bool _has_error;
257
258 public:
259 JvmtiTagMapFlatEntryConverter(int batch_size): _batch_size(batch_size), _entries(batch_size, mtServiceability), _has_error(false) { }
260 ~JvmtiTagMapFlatEntryConverter() {}
261
262 // returns false if there is nothing to convert
263 bool import_entries(JvmtiFlatTagMapTable* table) {
264 if (_has_error) {
265 // stop the process to avoid infinite loop
266 return false;
267 }
268
269 class Importer: public JvmtiFlatTagMapKeyClosure {
270 private:
271 GrowableArray<Entry>& _entries;
272 int _batch_size;
273 public:
274 Importer(GrowableArray<Entry>& entries, int batch_size): _entries(entries), _batch_size(batch_size) {}
275
276 bool do_entry(JvmtiFlatTagMapKey& key, jlong& tag) {
277 Entry entry(Handle(Thread::current(), key.holder()), key.offset(), key.inline_klass(), key.layout_kind());
278 _entries.append(entry);
279
280 return _entries.length() < _batch_size;
281 }
282 } importer(_entries, _batch_size);
283 table->entry_iterate(&importer);
284
285 return !_entries.is_empty();
286 }
287
288 void convert() {
289 for (int i = 0; i < _entries.length(); i++) {
290 EXCEPTION_MARK;
291 Entry& entry = _entries.at(i);
292 oop obj = entry.inline_klass->read_payload_from_addr(entry.holder(), entry.offset, entry.layout_kind, JavaThread::current());
293
294 if (HAS_PENDING_EXCEPTION) {
295 tty->print_cr("Exception in JvmtiTagMapFlatEntryConverter: ");
296 java_lang_Throwable::print(PENDING_EXCEPTION, tty);
297 tty->cr();
298 CLEAR_PENDING_EXCEPTION;
299 // stop the conversion
300 _has_error = true;
301 } else {
302 entry.dst = Handle(Thread::current(), obj);
303 }
304 }
305 }
306
307 // returns number of converted entries
308 int move(JvmtiFlatTagMapTable* src_table, JvmtiTagMapTable* dst_table) {
309 int count = 0;
310 for (int i = 0; i < _entries.length(); i++) {
311 Entry& entry = _entries.at(i);
312 if (entry.dst() == nullptr) {
313 // some error during conversion, skip the entry
314 continue;
315 }
316 JvmtiHeapwalkObject obj(entry.holder(), entry.offset, entry.inline_klass, entry.layout_kind);
317 jlong tag = src_table->remove(obj);
318
319 if (tag != 0) { // ensure the entry is still in the src_table
320 dst_table->add(entry.dst(), tag);
321 count++;
322 } else {
323
324 }
325 }
326 // and clean the array
327 _entries.clear();
328 return count;
329 }
330 };
331
332
333 void JvmtiTagMap::convert_flat_object_entries() {
334 Thread* current = Thread::current();
335 assert(current->is_Java_thread(), "must be executed on JavaThread");
336
337 log_debug(jvmti, table)("convert_flat_object_entries, main table size = %d, flat table size = %d",
338 _hashmap->number_of_entries(), _flat_hashmap->number_of_entries());
339
340 {
341 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
342 // If another thread is converting, let it finish.
343 while (_converting_flat_object) {
344 ml.wait();
345 }
346 if (_flat_hashmap->is_empty()) {
347 // nothing to convert
348 return;
349 }
350 _converting_flat_object = true;
351 }
352
353 const int BATCH_SIZE = 1024;
354 JvmtiTagMapFlatEntryConverter converter(BATCH_SIZE);
355
356 int count = 0;
357 while (true) {
358 HandleMark hm(current);
359 {
360 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
361 if (!converter.import_entries(_flat_hashmap)) {
362 break;
363 }
364 }
365 // Convert flat objects to heap-allocated without table lock (so agent callbacks can get/set tags).
366 converter.convert();
367 {
368 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
369 count += converter.move(_flat_hashmap, _hashmap);
370 }
371 }
372
373 log_info(jvmti, table)("%d flat value objects are converted, flat table size = %d",
374 count, _flat_hashmap->number_of_entries());
375 {
376 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
377 _converting_flat_object = false;
378 ml.notify_all();
379 }
380 }
381
382 jlong JvmtiTagMap::find(const JvmtiHeapwalkObject& obj) const {
383 jlong tag = _hashmap->find(obj);
384 if (tag == 0 && obj.is_value()) {
385 tag = _flat_hashmap->find(obj);
386 }
387 return tag;
388 }
389
390 void JvmtiTagMap::add(const JvmtiHeapwalkObject& obj, jlong tag) {
391 if (obj.is_flat()) {
392 // we may have tag for equal (non-flat) object in _hashmap, try to update it 1st
393 if (!_hashmap->update(obj, tag)) {
394 // no entry in _hashmap, add to _flat_hashmap
395 _flat_hashmap->add(obj, tag);
396 }
397 } else {
398 _hashmap->add(obj, tag);
399 }
400 }
401
402 void JvmtiTagMap::remove(const JvmtiHeapwalkObject& obj) {
403 if (!_hashmap->remove(obj)) {
404 if (obj.is_value()) {
405 _flat_hashmap->remove(obj);
406 }
407 }
408 }
409
410
411 // A CallbackWrapper is a support class for querying and tagging an object
412 // around a callback to a profiler. The constructor does pre-callback
413 // work to get the tag value, klass tag value, ... and the destructor
414 // does the post-callback work of tagging or untagging the object.
415 //
416 // {
417 // CallbackWrapper wrapper(tag_map, o);
418 //
419 // (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
420 //
421 // }
422 // wrapper goes out of scope here which results in the destructor
423 // checking to see if the object has been tagged, untagged, or the
424 // tag value has changed.
425 //
426 class CallbackWrapper : public StackObj {
427 private:
428 JvmtiTagMap* _tag_map;
429 const JvmtiHeapwalkObject& _o;
430 jlong _obj_size;
431 jlong _obj_tag;
432 jlong _klass_tag;
433
434 protected:
435 JvmtiTagMap* tag_map() const { return _tag_map; }
436
437 // invoked post-callback to tag, untag, or update the tag of an object
438 void inline post_callback_tag_update(const JvmtiHeapwalkObject& o, JvmtiTagMap* tag_map, jlong obj_tag);
439
440 public:
441 CallbackWrapper(JvmtiTagMap* tag_map, const JvmtiHeapwalkObject& o)
442 : _tag_map(tag_map), _o(o)
443 {
444 assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
445 "MT unsafe or must be VM thread");
446
447 // object size
448 if (!o.is_flat()) {
449 // common case: we have oop
450 _obj_size = (jlong)o.obj()->size() * wordSize;
451 } else {
452 // flat value object, we know its InstanceKlass
453 assert(_o.inline_klass() != nullptr, "must be");
454 _obj_size = _o.inline_klass()->size() * wordSize;;
455 }
456
457 // get object tag
458 _obj_tag = _tag_map->find(_o);
459
460 // get the class and the class's tag value
461 assert(vmClasses::Class_klass()->is_mirror_instance_klass(), "Is not?");
462
463 _klass_tag = _tag_map->find(_o.klass()->java_mirror());
464 }
465
466 ~CallbackWrapper() {
467 post_callback_tag_update(_o, _tag_map, _obj_tag);
468 }
469
470 inline jlong* obj_tag_p() { return &_obj_tag; }
471 inline jlong obj_size() const { return _obj_size; }
472 inline jlong obj_tag() const { return _obj_tag; }
473 inline jlong klass_tag() const { return _klass_tag; }
474 };
475
476 // callback post-callback to tag, untag, or update the tag of an object
477 void inline CallbackWrapper::post_callback_tag_update(const JvmtiHeapwalkObject& o,
478 JvmtiTagMap* tag_map,
479 jlong obj_tag) {
480 if (obj_tag == 0) {
481 // callback has untagged the object, remove the entry if present
482 tag_map->remove(o);
483 } else {
484 // object was previously tagged or not present - the callback may have
485 // changed the tag value
486 assert(Thread::current()->is_VM_thread(), "must be VMThread");
487 tag_map->add(o, obj_tag);
488 }
489 }
490
491 // An extended CallbackWrapper used when reporting an object reference
492 // to the agent.
493 //
494 // {
495 // TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
496 //
497 // (*callback)(wrapper.klass_tag(),
498 // wrapper.obj_size(),
499 // wrapper.obj_tag_p()
500 // wrapper.referrer_tag_p(), ...)
501 //
502 // }
503 // wrapper goes out of scope here which results in the destructor
504 // checking to see if the referrer object has been tagged, untagged,
505 // or the tag value has changed.
506 //
507 class TwoOopCallbackWrapper : public CallbackWrapper {
508 private:
509 const JvmtiHeapwalkObject& _referrer;
510 bool _is_reference_to_self;
511 jlong _referrer_obj_tag;
512 jlong _referrer_klass_tag;
513 jlong* _referrer_tag_p;
514
515 bool is_reference_to_self() const { return _is_reference_to_self; }
516
517 public:
518 TwoOopCallbackWrapper(JvmtiTagMap* tag_map, const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& o) :
519 CallbackWrapper(tag_map, o), _referrer(referrer)
520 {
521 // self reference needs to be handled in a special way
522 _is_reference_to_self = (referrer == o);
523
524 if (_is_reference_to_self) {
525 _referrer_klass_tag = klass_tag();
526 _referrer_tag_p = obj_tag_p();
527 } else {
528 // get object tag
529 _referrer_obj_tag = tag_map->find(_referrer);
530
531 _referrer_tag_p = &_referrer_obj_tag;
532
533 // get referrer class tag.
534 _referrer_klass_tag = tag_map->find(_referrer.klass()->java_mirror());
535 }
536 }
537
538 ~TwoOopCallbackWrapper() {
539 if (!is_reference_to_self()) {
540 post_callback_tag_update(_referrer,
541 tag_map(),
542 _referrer_obj_tag);
543 }
544 }
545
546 // address of referrer tag
547 // (for a self reference this will return the same thing as obj_tag_p())
548 inline jlong* referrer_tag_p() { return _referrer_tag_p; }
549
550 // referrer's class tag
551 inline jlong referrer_klass_tag() { return _referrer_klass_tag; }
552 };
553
554 // tag an object
555 //
556 // This function is performance critical. If many threads attempt to tag objects
557 // around the same time then it's possible that the Mutex associated with the
558 // tag map will be a hot lock.
559 void JvmtiTagMap::set_tag(jobject object, jlong tag) {
560 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
561
562 // SetTag should not post events because the JavaThread has to
563 // transition to native for the callback and this cannot stop for
564 // safepoints with the hashmap lock held.
565 check_hashmap(nullptr); /* don't collect dead objects */
566
567 // resolve the object
568 oop o = JNIHandles::resolve_non_null(object);
569 // see if the object is already tagged
570 JvmtiHeapwalkObject obj(o);
571 if (tag == 0) {
572 // remove the entry if present
573 _hashmap->remove(obj);
574 } else {
575 // if the object is already tagged or not present then we add/update
576 // the tag
577 add(obj, tag);
578 }
579 }
580
581 // get the tag for an object
582 jlong JvmtiTagMap::get_tag(jobject object) {
583 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
584
585 // GetTag should not post events because the JavaThread has to
586 // transition to native for the callback and this cannot stop for
587 // safepoints with the hashmap lock held.
588 check_hashmap(nullptr); /* don't collect dead objects */
589
590 // resolve the object
591 oop o = JNIHandles::resolve_non_null(object);
592
593 return find(o);
594 }
595
596
597 // Helper class used to describe the static or instance fields of a class.
598 // For each field it holds the field index (as defined by the JVMTI specification),
599 // the field type, and the offset.
600
601 class ClassFieldDescriptor: public CHeapObj<mtInternal> {
602 private:
603 int _field_index;
604 int _field_offset;
605 char _field_type;
606 InlineKlass* _inline_klass; // nullptr for heap object
607 LayoutKind _layout_kind;
608 public:
609 ClassFieldDescriptor(int index, const FieldStreamBase& fld) :
610 _field_index(index), _field_offset(fld.offset()), _field_type(fld.signature()->char_at(0)) {
611 if (fld.is_flat()) {
612 const fieldDescriptor& fd = fld.field_descriptor();
613 InstanceKlass* holder_klass = fd.field_holder();
614 InlineLayoutInfo* layout_info = holder_klass->inline_layout_info_adr(fd.index());
615 _inline_klass = layout_info->klass();
616 _layout_kind = layout_info->kind();
617 } else {
618 _inline_klass = nullptr;
619 _layout_kind = LayoutKind::REFERENCE;
620 }
621 }
622 int field_index() const { return _field_index; }
623 char field_type() const { return _field_type; }
624 int field_offset() const { return _field_offset; }
625 bool is_flat() const { return _inline_klass != nullptr; }
626 InlineKlass* inline_klass() const { return _inline_klass; }
627 LayoutKind layout_kind() const { return _layout_kind; }
628 };
629
630 class ClassFieldMap: public CHeapObj<mtInternal> {
631 private:
632 enum {
633 initial_field_count = 5
634 };
635
636 // list of field descriptors
637 GrowableArray<ClassFieldDescriptor*>* _fields;
638
639 // constructor
640 ClassFieldMap();
641
642 // calculates number of fields in all interfaces
643 static int interfaces_field_count(InstanceKlass* ik);
644
645 // add a field
646 void add(int index, const FieldStreamBase& fld);
647
648 public:
649 ~ClassFieldMap();
650
651 // access
652 int field_count() { return _fields->length(); }
653 ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
654
655 // functions to create maps of static or instance fields
656 static ClassFieldMap* create_map_of_static_fields(Klass* k);
657 static ClassFieldMap* create_map_of_instance_fields(Klass* k);
658 };
659
660 ClassFieldMap::ClassFieldMap() {
661 _fields = new (mtServiceability)
662 GrowableArray<ClassFieldDescriptor*>(initial_field_count, mtServiceability);
663 }
664
665 ClassFieldMap::~ClassFieldMap() {
666 for (int i=0; i<_fields->length(); i++) {
667 delete _fields->at(i);
668 }
669 delete _fields;
670 }
671
672 int ClassFieldMap::interfaces_field_count(InstanceKlass* ik) {
673 const Array<InstanceKlass*>* interfaces = ik->transitive_interfaces();
674 int count = 0;
675 for (int i = 0; i < interfaces->length(); i++) {
676 FilteredJavaFieldStream fld(interfaces->at(i));
677 count += fld.field_count();
678 }
679 return count;
680 }
681
682 void ClassFieldMap::add(int index, const FieldStreamBase& fld) {
683 ClassFieldDescriptor* field = new ClassFieldDescriptor(index, fld);
684 _fields->append(field);
685 }
686
687 // Returns a heap allocated ClassFieldMap to describe the static fields
688 // of the given class.
689 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(Klass* k) {
690 InstanceKlass* ik = InstanceKlass::cast(k);
691
692 // create the field map
693 ClassFieldMap* field_map = new ClassFieldMap();
694
695 // Static fields of interfaces and superclasses are reported as references from the interfaces/superclasses.
696 // Need to calculate start index of this class fields: number of fields in all interfaces and superclasses.
697 int index = interfaces_field_count(ik);
698 for (InstanceKlass* super_klass = ik->java_super(); super_klass != nullptr; super_klass = super_klass->java_super()) {
699 FilteredJavaFieldStream super_fld(super_klass);
700 index += super_fld.field_count();
701 }
702
703 for (FilteredJavaFieldStream fld(ik); !fld.done(); fld.next(), index++) {
704 // ignore instance fields
705 if (!fld.access_flags().is_static()) {
706 continue;
707 }
708 field_map->add(index, fld);
709 }
710
711 return field_map;
712 }
713
714 // Returns a heap allocated ClassFieldMap to describe the instance fields
715 // of the given class. All instance fields are included (this means public
716 // and private fields declared in superclasses too).
717 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(Klass* k) {
718 InstanceKlass* ik = InstanceKlass::cast(k);
719
720 // create the field map
721 ClassFieldMap* field_map = new ClassFieldMap();
722
723 // fields of the superclasses are reported first, so need to know total field number to calculate field indices
724 int total_field_number = interfaces_field_count(ik);
725 for (InstanceKlass* klass = ik; klass != nullptr; klass = klass->java_super()) {
726 FilteredJavaFieldStream fld(klass);
727 total_field_number += fld.field_count();
728 }
729
730 for (InstanceKlass* klass = ik; klass != nullptr; klass = klass->java_super()) {
731 FilteredJavaFieldStream fld(klass);
732 int start_index = total_field_number - fld.field_count();
733 for (int index = 0; !fld.done(); fld.next(), index++) {
734 // ignore static fields
735 if (fld.access_flags().is_static()) {
736 continue;
737 }
738 field_map->add(start_index + index, fld);
739 }
740 // update total_field_number for superclass (decrease by the field count in the current class)
741 total_field_number = start_index;
742 }
743
744 return field_map;
745 }
746
747 // Helper class used to cache a ClassFileMap for the instance fields of
748 // a cache. A JvmtiCachedClassFieldMap can be cached by an InstanceKlass during
749 // heap iteration and avoid creating a field map for each object in the heap
750 // (only need to create the map when the first instance of a class is encountered).
751 //
752 class JvmtiCachedClassFieldMap : public CHeapObj<mtInternal> {
753 private:
754 enum {
755 initial_class_count = 200
756 };
757 ClassFieldMap* _field_map;
758
759 ClassFieldMap* field_map() const { return _field_map; }
760
761 JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
762 ~JvmtiCachedClassFieldMap();
763
764 static GrowableArray<InstanceKlass*>* _class_list;
765 static void add_to_class_list(InstanceKlass* ik);
766
767 public:
768 // returns the field map for a given klass (returning map cached
769 // by InstanceKlass if possible
770 static ClassFieldMap* get_map_of_instance_fields(Klass* k);
771
772 // removes the field map from all instanceKlasses - should be
773 // called before VM operation completes
774 static void clear_cache();
775
776 // returns the number of ClassFieldMap cached by instanceKlasses
777 static int cached_field_map_count();
778 };
779
780 GrowableArray<InstanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
781
782 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
783 _field_map = field_map;
784 }
785
786 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
787 if (_field_map != nullptr) {
788 delete _field_map;
789 }
790 }
791
792 // Marker class to ensure that the class file map cache is only used in a defined
793 // scope.
794 class ClassFieldMapCacheMark : public StackObj {
795 private:
796 static bool _is_active;
797 public:
798 ClassFieldMapCacheMark() {
799 assert(Thread::current()->is_VM_thread(), "must be VMThread");
800 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
801 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
802 _is_active = true;
803 }
804 ~ClassFieldMapCacheMark() {
805 JvmtiCachedClassFieldMap::clear_cache();
806 _is_active = false;
807 }
808 static bool is_active() { return _is_active; }
809 };
810
811 bool ClassFieldMapCacheMark::_is_active;
812
813 // record that the given InstanceKlass is caching a field map
814 void JvmtiCachedClassFieldMap::add_to_class_list(InstanceKlass* ik) {
815 if (_class_list == nullptr) {
816 _class_list = new (mtServiceability)
817 GrowableArray<InstanceKlass*>(initial_class_count, mtServiceability);
818 }
819 _class_list->push(ik);
820 }
821
822 // returns the instance field map for the given klass
823 // (returns field map cached by the InstanceKlass if possible)
824 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(Klass *k) {
825 assert(Thread::current()->is_VM_thread(), "must be VMThread");
826 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
827
828 InstanceKlass* ik = InstanceKlass::cast(k);
829
830 // return cached map if possible
831 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
832 if (cached_map != nullptr) {
833 assert(cached_map->field_map() != nullptr, "missing field list");
834 return cached_map->field_map();
835 } else {
836 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(k);
837 cached_map = new JvmtiCachedClassFieldMap(field_map);
838 ik->set_jvmti_cached_class_field_map(cached_map);
839 add_to_class_list(ik);
840 return field_map;
841 }
842 }
843
844 // remove the fields maps cached from all instanceKlasses
845 void JvmtiCachedClassFieldMap::clear_cache() {
846 assert(Thread::current()->is_VM_thread(), "must be VMThread");
847 if (_class_list != nullptr) {
848 for (int i = 0; i < _class_list->length(); i++) {
849 InstanceKlass* ik = _class_list->at(i);
850 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
851 assert(cached_map != nullptr, "should not be null");
852 ik->set_jvmti_cached_class_field_map(nullptr);
853 delete cached_map; // deletes the encapsulated field map
854 }
855 delete _class_list;
856 _class_list = nullptr;
857 }
858 }
859
860 // returns the number of ClassFieldMap cached by instanceKlasses
861 int JvmtiCachedClassFieldMap::cached_field_map_count() {
862 return (_class_list == nullptr) ? 0 : _class_list->length();
863 }
864
865 // helper function to indicate if an object is filtered by its tag or class tag
866 static inline bool is_filtered_by_heap_filter(jlong obj_tag,
867 jlong klass_tag,
868 int heap_filter) {
869 // apply the heap filter
870 if (obj_tag != 0) {
871 // filter out tagged objects
872 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
873 } else {
874 // filter out untagged objects
875 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
876 }
877 if (klass_tag != 0) {
878 // filter out objects with tagged classes
879 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
880 } else {
881 // filter out objects with untagged classes.
882 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
883 }
884 return false;
885 }
886
887 // helper function to indicate if an object is filtered by a klass filter
888 static inline bool is_filtered_by_klass_filter(const JvmtiHeapwalkObject& obj, Klass* klass_filter) {
889 if (klass_filter != nullptr) {
890 if (obj.klass() != klass_filter) {
891 return true;
892 }
893 }
894 return false;
895 }
896
897 // helper function to tell if a field is a primitive field or not
898 static inline bool is_primitive_field_type(char type) {
899 return (type != JVM_SIGNATURE_CLASS && type != JVM_SIGNATURE_ARRAY);
900 }
901
902 // helper function to copy the value from location addr to jvalue.
903 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
904 switch (value_type) {
905 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
906 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; }
907 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; }
908 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; }
909 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; }
910 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; }
911 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; }
912 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; }
913 default: ShouldNotReachHere();
914 }
915 }
916
917 // helper function to invoke string primitive value callback
918 // returns visit control flags
919 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
920 CallbackWrapper* wrapper,
921 const JvmtiHeapwalkObject& obj,
922 void* user_data)
923 {
924 assert(!obj.is_flat(), "cannot be flat");
925 oop str = obj.obj();
926 assert(str->klass() == vmClasses::String_klass(), "not a string");
927
928 typeArrayOop s_value = java_lang_String::value(str);
929
930 // JDK-6584008: the value field may be null if a String instance is
931 // partially constructed.
932 if (s_value == nullptr) {
933 return 0;
934 }
935 // get the string value and length
936 // (string value may be offset from the base)
937 int s_len = java_lang_String::length(str);
938 bool is_latin1 = java_lang_String::is_latin1(str);
939 jchar* value;
940 if (s_len > 0) {
941 if (!is_latin1) {
942 value = s_value->char_at_addr(0);
943 } else {
944 // Inflate latin1 encoded string to UTF16
945 jchar* buf = NEW_C_HEAP_ARRAY(jchar, s_len, mtInternal);
946 for (int i = 0; i < s_len; i++) {
947 buf[i] = ((jchar) s_value->byte_at(i)) & 0xff;
948 }
949 value = &buf[0];
950 }
951 } else {
952 // Don't use char_at_addr(0) if length is 0
953 value = (jchar*) s_value->base(T_CHAR);
954 }
955
956 // invoke the callback
957 jint res = (*cb)(wrapper->klass_tag(),
958 wrapper->obj_size(),
959 wrapper->obj_tag_p(),
960 value,
961 (jint)s_len,
962 user_data);
963
964 if (is_latin1 && s_len > 0) {
965 FREE_C_HEAP_ARRAY(jchar, value);
966 }
967 return res;
968 }
969
970 // helper function to invoke string primitive value callback
971 // returns visit control flags
972 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
973 CallbackWrapper* wrapper,
974 const JvmtiHeapwalkObject& obj,
975 void* user_data)
976 {
977 assert(!obj.is_flat(), "cannot be flat");
978 assert(obj.obj()->is_typeArray(), "not a primitive array");
979
980 // get base address of first element
981 typeArrayOop array = typeArrayOop(obj.obj());
982 BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
983 void* elements = array->base(type);
984
985 // jvmtiPrimitiveType is defined so this mapping is always correct
986 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
987
988 return (*cb)(wrapper->klass_tag(),
989 wrapper->obj_size(),
990 wrapper->obj_tag_p(),
991 (jint)array->length(),
992 elem_type,
993 elements,
994 user_data);
995 }
996
997 // helper function to invoke the primitive field callback for all static fields
998 // of a given class
999 static jint invoke_primitive_field_callback_for_static_fields
1000 (CallbackWrapper* wrapper,
1001 oop obj,
1002 jvmtiPrimitiveFieldCallback cb,
1003 void* user_data)
1004 {
1005 // for static fields only the index will be set
1006 static jvmtiHeapReferenceInfo reference_info = { 0 };
1007
1008 assert(obj->klass() == vmClasses::Class_klass(), "not a class");
1009 if (java_lang_Class::is_primitive(obj)) {
1010 return 0;
1011 }
1012 Klass* klass = java_lang_Class::as_Klass(obj);
1013
1014 // ignore classes for object and type arrays
1015 if (!klass->is_instance_klass()) {
1016 return 0;
1017 }
1018
1019 // ignore classes which aren't linked yet
1020 InstanceKlass* ik = InstanceKlass::cast(klass);
1021 if (!ik->is_linked()) {
1022 return 0;
1023 }
1024
1025 // get the field map
1026 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
1027
1028 // invoke the callback for each static primitive field
1029 for (int i=0; i<field_map->field_count(); i++) {
1030 ClassFieldDescriptor* field = field_map->field_at(i);
1031
1032 // ignore non-primitive fields
1033 char type = field->field_type();
1034 if (!is_primitive_field_type(type)) {
1035 continue;
1036 }
1037 // one-to-one mapping
1038 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1039
1040 // get offset and field value
1041 int offset = field->field_offset();
1042 address addr = cast_from_oop<address>(klass->java_mirror()) + offset;
1043 jvalue value;
1044 copy_to_jvalue(&value, addr, value_type);
1045
1046 // field index
1047 reference_info.field.index = field->field_index();
1048
1049 // invoke the callback
1050 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
1051 &reference_info,
1052 wrapper->klass_tag(),
1053 wrapper->obj_tag_p(),
1054 value,
1055 value_type,
1056 user_data);
1057 if (res & JVMTI_VISIT_ABORT) {
1058 delete field_map;
1059 return res;
1060 }
1061 }
1062
1063 delete field_map;
1064 return 0;
1065 }
1066
1067 // helper function to invoke the primitive field callback for all instance fields
1068 // of a given object
1069 static jint invoke_primitive_field_callback_for_instance_fields(
1070 CallbackWrapper* wrapper,
1071 const JvmtiHeapwalkObject& obj,
1072 jvmtiPrimitiveFieldCallback cb,
1073 void* user_data)
1074 {
1075 // for instance fields only the index will be set
1076 static jvmtiHeapReferenceInfo reference_info = { 0 };
1077
1078 // get the map of the instance fields
1079 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj.klass());
1080
1081 // invoke the callback for each instance primitive field
1082 for (int i=0; i<fields->field_count(); i++) {
1083 ClassFieldDescriptor* field = fields->field_at(i);
1084
1085 // ignore non-primitive fields
1086 char type = field->field_type();
1087 if (!is_primitive_field_type(type)) {
1088 continue;
1089 }
1090 // one-to-one mapping
1091 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1092
1093 // get field value
1094 address addr = cast_from_oop<address>(obj.obj()) + obj.offset() + field->field_offset();
1095 jvalue value;
1096 copy_to_jvalue(&value, addr, value_type);
1097
1098 // field index
1099 reference_info.field.index = field->field_index();
1100
1101 // invoke the callback
1102 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
1103 &reference_info,
1104 wrapper->klass_tag(),
1105 wrapper->obj_tag_p(),
1106 value,
1107 value_type,
1108 user_data);
1109 if (res & JVMTI_VISIT_ABORT) {
1110 return res;
1111 }
1112 }
1113 return 0;
1114 }
1115
1116
1117 // VM operation to iterate over all objects in the heap (both reachable
1118 // and unreachable)
1119 class VM_HeapIterateOperation: public VM_Operation {
1120 private:
1121 ObjectClosure* _blk;
1122 GrowableArray<jlong>* const _dead_objects;
1123 public:
1124 VM_HeapIterateOperation(ObjectClosure* blk, GrowableArray<jlong>* objects) :
1125 _blk(blk), _dead_objects(objects) { }
1126
1127 VMOp_Type type() const { return VMOp_HeapIterateOperation; }
1128 void doit() {
1129 // allows class files maps to be cached during iteration
1130 ClassFieldMapCacheMark cm;
1131
1132 JvmtiTagMap::check_hashmaps_for_heapwalk(_dead_objects);
1133
1134 // make sure that heap is parsable (fills TLABs with filler objects)
1135 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1136
1137 // Verify heap before iteration - if the heap gets corrupted then
1138 // JVMTI's IterateOverHeap will crash.
1139 if (VerifyBeforeIteration) {
1140 Universe::verify();
1141 }
1142
1143 // do the iteration
1144 Universe::heap()->object_iterate(_blk);
1145 }
1146 };
1147
1148
1149 // An ObjectClosure used to support the deprecated IterateOverHeap and
1150 // IterateOverInstancesOfClass functions
1151 class IterateOverHeapObjectClosure: public ObjectClosure {
1152 private:
1153 JvmtiTagMap* _tag_map;
1154 Klass* _klass;
1155 jvmtiHeapObjectFilter _object_filter;
1156 jvmtiHeapObjectCallback _heap_object_callback;
1157 const void* _user_data;
1158
1159 // accessors
1160 JvmtiTagMap* tag_map() const { return _tag_map; }
1161 jvmtiHeapObjectFilter object_filter() const { return _object_filter; }
1162 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
1163 Klass* klass() const { return _klass; }
1164 const void* user_data() const { return _user_data; }
1165
1166 // indicates if iteration has been aborted
1167 bool _iteration_aborted;
1168 bool is_iteration_aborted() const { return _iteration_aborted; }
1169 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; }
1170
1171 public:
1172 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
1173 Klass* klass,
1174 jvmtiHeapObjectFilter object_filter,
1175 jvmtiHeapObjectCallback heap_object_callback,
1176 const void* user_data) :
1177 _tag_map(tag_map),
1178 _klass(klass),
1179 _object_filter(object_filter),
1180 _heap_object_callback(heap_object_callback),
1181 _user_data(user_data),
1182 _iteration_aborted(false)
1183 {
1184 }
1185
1186 void do_object(oop o);
1187 };
1188
1189 // invoked for each object in the heap
1190 void IterateOverHeapObjectClosure::do_object(oop o) {
1191 // check if iteration has been halted
1192 if (is_iteration_aborted()) return;
1193
1194 // instanceof check when filtering by klass
1195 if (klass() != nullptr && !o->is_a(klass())) {
1196 return;
1197 }
1198
1199 // skip if object is a dormant shared object whose mirror hasn't been loaded
1200 if (o != nullptr && o->klass()->java_mirror() == nullptr) {
1201 log_debug(aot, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s)", p2i(o),
1202 o->klass()->external_name());
1203 return;
1204 }
1205
1206 // prepare for the calllback
1207 JvmtiHeapwalkObject wrapper_obj(o);
1208 CallbackWrapper wrapper(tag_map(), wrapper_obj);
1209
1210 // if the object is tagged and we're only interested in untagged objects
1211 // then don't invoke the callback. Similarly, if the object is untagged
1212 // and we're only interested in tagged objects we skip the callback.
1213 if (wrapper.obj_tag() != 0) {
1214 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
1215 } else {
1216 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
1217 }
1218
1219 // invoke the agent's callback
1220 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
1221 wrapper.obj_size(),
1222 wrapper.obj_tag_p(),
1223 (void*)user_data());
1224 if (control == JVMTI_ITERATION_ABORT) {
1225 set_iteration_aborted(true);
1226 }
1227 }
1228
1229 // An ObjectClosure used to support the IterateThroughHeap function
1230 class IterateThroughHeapObjectClosure: public ObjectClosure {
1231 private:
1232 JvmtiTagMap* _tag_map;
1233 Klass* _klass;
1234 int _heap_filter;
1235 const jvmtiHeapCallbacks* _callbacks;
1236 const void* _user_data;
1237
1238 // accessor functions
1239 JvmtiTagMap* tag_map() const { return _tag_map; }
1240 int heap_filter() const { return _heap_filter; }
1241 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; }
1242 Klass* klass() const { return _klass; }
1243 const void* user_data() const { return _user_data; }
1244
1245 // indicates if the iteration has been aborted
1246 bool _iteration_aborted;
1247 bool is_iteration_aborted() const { return _iteration_aborted; }
1248
1249 // used to check the visit control flags. If the abort flag is set
1250 // then we set the iteration aborted flag so that the iteration completes
1251 // without processing any further objects
1252 bool check_flags_for_abort(jint flags) {
1253 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
1254 if (is_abort) {
1255 _iteration_aborted = true;
1256 }
1257 return is_abort;
1258 }
1259
1260 void visit_object(const JvmtiHeapwalkObject& obj);
1261 void visit_flat_fields(const JvmtiHeapwalkObject& obj);
1262 void visit_flat_array_elements(const JvmtiHeapwalkObject& obj);
1263
1264 public:
1265 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
1266 Klass* klass,
1267 int heap_filter,
1268 const jvmtiHeapCallbacks* heap_callbacks,
1269 const void* user_data) :
1270 _tag_map(tag_map),
1271 _klass(klass),
1272 _heap_filter(heap_filter),
1273 _callbacks(heap_callbacks),
1274 _user_data(user_data),
1275 _iteration_aborted(false)
1276 {
1277 }
1278
1279 void do_object(oop obj);
1280 };
1281
1282 // invoked for each object in the heap
1283 void IterateThroughHeapObjectClosure::do_object(oop obj) {
1284 // check if iteration has been halted
1285 if (is_iteration_aborted()) return;
1286
1287 // skip if object is a dormant shared object whose mirror hasn't been loaded
1288 if (obj != nullptr && obj->klass()->java_mirror() == nullptr) {
1289 log_debug(aot, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s)", p2i(obj),
1290 obj->klass()->external_name());
1291 return;
1292 }
1293
1294 visit_object(obj);
1295 }
1296
1297 void IterateThroughHeapObjectClosure::visit_object(const JvmtiHeapwalkObject& obj) {
1298 // apply class filter
1299 if (is_filtered_by_klass_filter(obj, klass())) return;
1300
1301 // prepare for callback
1302 CallbackWrapper wrapper(tag_map(), obj);
1303
1304 // check if filtered by the heap filter
1305 if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
1306 return;
1307 }
1308
1309 // for arrays we need the length, otherwise -1
1310 bool is_array = obj.klass()->is_array_klass();
1311 int len = is_array ? arrayOop(obj.obj())->length() : -1;
1312
1313 // invoke the object callback (if callback is provided)
1314 if (callbacks()->heap_iteration_callback != nullptr) {
1315 jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
1316 jint res = (*cb)(wrapper.klass_tag(),
1317 wrapper.obj_size(),
1318 wrapper.obj_tag_p(),
1319 (jint)len,
1320 (void*)user_data());
1321 if (check_flags_for_abort(res)) return;
1322 }
1323
1324 // for objects and classes we report primitive fields if callback provided
1325 if (callbacks()->primitive_field_callback != nullptr && obj.klass()->is_instance_klass()) {
1326 jint res;
1327 jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
1328 if (obj.klass() == vmClasses::Class_klass()) {
1329 assert(!obj.is_flat(), "Class object cannot be flattened");
1330 res = invoke_primitive_field_callback_for_static_fields(&wrapper,
1331 obj.obj(),
1332 cb,
1333 (void*)user_data());
1334 } else {
1335 res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
1336 obj,
1337 cb,
1338 (void*)user_data());
1339 }
1340 if (check_flags_for_abort(res)) return;
1341 }
1342
1343 // string callback
1344 if (!is_array &&
1345 callbacks()->string_primitive_value_callback != nullptr &&
1346 obj.klass() == vmClasses::String_klass()) {
1347 jint res = invoke_string_value_callback(
1348 callbacks()->string_primitive_value_callback,
1349 &wrapper,
1350 obj,
1351 (void*)user_data());
1352 if (check_flags_for_abort(res)) return;
1353 }
1354
1355 // array callback
1356 if (is_array &&
1357 callbacks()->array_primitive_value_callback != nullptr &&
1358 obj.klass()->is_typeArray_klass()) {
1359 jint res = invoke_array_primitive_value_callback(
1360 callbacks()->array_primitive_value_callback,
1361 &wrapper,
1362 obj,
1363 (void*)user_data());
1364 if (check_flags_for_abort(res)) return;
1365 }
1366
1367 // All info for the object is reported.
1368
1369 // If the object has flat fields, report them as heap objects.
1370 if (obj.klass()->is_instance_klass()) {
1371 if (InstanceKlass::cast(obj.klass())->has_inline_type_fields()) {
1372 visit_flat_fields(obj);
1373 // check if iteration has been halted
1374 if (is_iteration_aborted()) {
1375 return;
1376 }
1377 }
1378 }
1379 // If the object is flat array, report all elements as heap objects.
1380 if (is_array && obj.obj()->is_flatArray()) {
1381 assert(!obj.is_flat(), "Array object cannot be flattened");
1382 visit_flat_array_elements(obj);
1383 }
1384 }
1385
1386 void IterateThroughHeapObjectClosure::visit_flat_fields(const JvmtiHeapwalkObject& obj) {
1387 // iterate over instance fields
1388 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj.klass());
1389 for (int i = 0; i < fields->field_count(); i++) {
1390 ClassFieldDescriptor* field = fields->field_at(i);
1391 // skip non-flat and (for safety) primitive fields
1392 if (!field->is_flat() || is_primitive_field_type(field->field_type())) {
1393 continue;
1394 }
1395
1396 int field_offset = field->field_offset();
1397 if (obj.is_flat()) {
1398 // the object is inlined, its fields are stored without the header
1399 field_offset += obj.offset() - obj.inline_klass()->payload_offset();
1400 }
1401 // check for possible nulls
1402 bool can_be_null = field->layout_kind() == LayoutKind::NULLABLE_ATOMIC_FLAT;
1403 if (can_be_null) {
1404 address payload = cast_from_oop<address>(obj.obj()) + field_offset;
1405 if (field->inline_klass()->is_payload_marked_as_null(payload)) {
1406 continue;
1407 }
1408 }
1409 JvmtiHeapwalkObject field_obj(obj.obj(), field_offset, field->inline_klass(), field->layout_kind());
1410
1411 visit_object(field_obj);
1412
1413 // check if iteration has been halted
1414 if (is_iteration_aborted()) {
1415 return;
1416 }
1417 }
1418 }
1419
1420 void IterateThroughHeapObjectClosure::visit_flat_array_elements(const JvmtiHeapwalkObject& obj) {
1421 assert(!obj.is_flat() && obj.obj()->is_flatArray() , "sanity check");
1422 flatArrayOop array = flatArrayOop(obj.obj());
1423 FlatArrayKlass* faklass = FlatArrayKlass::cast(array->klass());
1424 InlineKlass* vk = InlineKlass::cast(faklass->element_klass());
1425 bool need_null_check = faklass->layout_kind() == LayoutKind::NULLABLE_ATOMIC_FLAT;
1426
1427 for (int index = 0; index < array->length(); index++) {
1428 address addr = (address)array->value_at_addr(index, faklass->layout_helper());
1429 // check for null
1430 if (need_null_check) {
1431 if (vk->is_payload_marked_as_null(addr)) {
1432 continue;
1433 }
1434 }
1435
1436 // offset in the array oop
1437 int offset = (int)(addr - cast_from_oop<address>(array));
1438 JvmtiHeapwalkObject elem(obj.obj(), offset, vk, faklass->layout_kind());
1439
1440 visit_object(elem);
1441
1442 // check if iteration has been halted
1443 if (is_iteration_aborted()) {
1444 return;
1445 }
1446 }
1447 }
1448
1449 // Deprecated function to iterate over all objects in the heap
1450 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
1451 Klass* klass,
1452 jvmtiHeapObjectCallback heap_object_callback,
1453 const void* user_data)
1454 {
1455 // EA based optimizations on tagged objects are already reverted.
1456 EscapeBarrier eb(object_filter == JVMTI_HEAP_OBJECT_UNTAGGED ||
1457 object_filter == JVMTI_HEAP_OBJECT_EITHER,
1458 JavaThread::current());
1459 eb.deoptimize_objects_all_threads();
1460 Arena dead_object_arena(mtServiceability);
1461 GrowableArray <jlong> dead_objects(&dead_object_arena, 10, 0, 0);
1462 {
1463 MutexLocker ml(Heap_lock);
1464 IterateOverHeapObjectClosure blk(this,
1465 klass,
1466 object_filter,
1467 heap_object_callback,
1468 user_data);
1469 VM_HeapIterateOperation op(&blk, &dead_objects);
1470 VMThread::execute(&op);
1471 }
1472 convert_flat_object_entries();
1473
1474 // Post events outside of Heap_lock
1475 post_dead_objects(&dead_objects);
1476 }
1477
1478
1479 // Iterates over all objects in the heap
1480 void JvmtiTagMap::iterate_through_heap(jint heap_filter,
1481 Klass* klass,
1482 const jvmtiHeapCallbacks* callbacks,
1483 const void* user_data)
1484 {
1485 // EA based optimizations on tagged objects are already reverted.
1486 EscapeBarrier eb(!(heap_filter & JVMTI_HEAP_FILTER_UNTAGGED), JavaThread::current());
1487 eb.deoptimize_objects_all_threads();
1488
1489 Arena dead_object_arena(mtServiceability);
1490 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
1491 {
1492 MutexLocker ml(Heap_lock);
1493 IterateThroughHeapObjectClosure blk(this,
1494 klass,
1495 heap_filter,
1496 callbacks,
1497 user_data);
1498 VM_HeapIterateOperation op(&blk, &dead_objects);
1499 VMThread::execute(&op);
1500 }
1501 convert_flat_object_entries();
1502
1503 // Post events outside of Heap_lock
1504 post_dead_objects(&dead_objects);
1505 }
1506
1507 void JvmtiTagMap::remove_dead_entries_locked(GrowableArray<jlong>* objects) {
1508 assert(is_locked(), "precondition");
1509 if (_needs_cleaning) {
1510 // Recheck whether to post object free events under the lock.
1511 if (!env()->is_enabled(JVMTI_EVENT_OBJECT_FREE)) {
1512 objects = nullptr;
1513 }
1514 log_info(jvmti, table)("TagMap table needs cleaning%s",
1515 ((objects != nullptr) ? " and posting" : ""));
1516 _hashmap->remove_dead_entries(objects);
1517 _needs_cleaning = false;
1518 }
1519 }
1520
1521 void JvmtiTagMap::remove_dead_entries(GrowableArray<jlong>* objects) {
1522 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1523 remove_dead_entries_locked(objects);
1524 }
1525
1526 void JvmtiTagMap::post_dead_objects(GrowableArray<jlong>* const objects) {
1527 assert(Thread::current()->is_Java_thread(), "Must post from JavaThread");
1528 if (objects != nullptr && objects->length() > 0) {
1529 JvmtiExport::post_object_free(env(), objects);
1530 log_info(jvmti, table)("%d free object posted", objects->length());
1531 }
1532 }
1533
1534 void JvmtiTagMap::remove_and_post_dead_objects() {
1535 ResourceMark rm;
1536 GrowableArray<jlong> objects;
1537 remove_dead_entries(&objects);
1538 post_dead_objects(&objects);
1539 }
1540
1541 void JvmtiTagMap::flush_object_free_events() {
1542 assert_not_at_safepoint();
1543 if (env()->is_enabled(JVMTI_EVENT_OBJECT_FREE)) {
1544 {
1545 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1546 // If another thread is posting events, let it finish
1547 while (_posting_events) {
1548 ml.wait();
1549 }
1550
1551 if (!_needs_cleaning || is_empty()) {
1552 _needs_cleaning = false;
1553 return;
1554 }
1555 _posting_events = true;
1556 } // Drop the lock so we can do the cleaning on the VM thread.
1557 // Needs both cleaning and event posting (up to some other thread
1558 // getting there first after we dropped the lock).
1559 remove_and_post_dead_objects();
1560 {
1561 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1562 _posting_events = false;
1563 ml.notify_all();
1564 }
1565 } else {
1566 remove_dead_entries(nullptr);
1567 }
1568 }
1569
1570 // support class for get_objects_with_tags
1571
1572 class TagObjectCollector : public JvmtiTagMapKeyClosure {
1573 private:
1574 JvmtiEnv* _env;
1575 JavaThread* _thread;
1576 jlong* _tags;
1577 jint _tag_count;
1578 bool _some_dead_found;
1579
1580 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs)
1581 GrowableArray<uint64_t>* _tag_results; // collected tags
1582
1583 public:
1584 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) :
1585 _env(env),
1586 _thread(JavaThread::current()),
1587 _tags((jlong*)tags),
1588 _tag_count(tag_count),
1589 _some_dead_found(false),
1590 _object_results(new (mtServiceability) GrowableArray<jobject>(1, mtServiceability)),
1591 _tag_results(new (mtServiceability) GrowableArray<uint64_t>(1, mtServiceability)) { }
1592
1593 ~TagObjectCollector() {
1594 delete _object_results;
1595 delete _tag_results;
1596 }
1597
1598 bool some_dead_found() const { return _some_dead_found; }
1599
1600 // for each tagged object check if the tag value matches
1601 // - if it matches then we create a JNI local reference to the object
1602 // and record the reference and tag value.
1603 // Always return true so the iteration continues.
1604 bool do_entry(JvmtiTagMapKey& key, jlong& value) {
1605 for (int i = 0; i < _tag_count; i++) {
1606 if (_tags[i] == value) {
1607 // The reference in this tag map could be the only (implicitly weak)
1608 // reference to that object. If we hand it out, we need to keep it live wrt
1609 // SATB marking similar to other j.l.ref.Reference referents. This is
1610 // achieved by using a phantom load in the object() accessor.
1611 oop o = key.object();
1612 if (o == nullptr) {
1613 _some_dead_found = true;
1614 // skip this whole entry
1615 return true;
1616 }
1617 assert(o != nullptr && Universe::heap()->is_in(o), "sanity check");
1618 jobject ref = JNIHandles::make_local(_thread, o);
1619 _object_results->append(ref);
1620 _tag_results->append(value);
1621 }
1622 }
1623 return true;
1624 }
1625
1626 // return the results from the collection
1627 //
1628 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1629 jvmtiError error;
1630 int count = _object_results->length();
1631 assert(count >= 0, "sanity check");
1632
1633 // if object_result_ptr is not null then allocate the result and copy
1634 // in the object references.
1635 if (object_result_ptr != nullptr) {
1636 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
1637 if (error != JVMTI_ERROR_NONE) {
1638 return error;
1639 }
1640 for (int i=0; i<count; i++) {
1641 (*object_result_ptr)[i] = _object_results->at(i);
1642 }
1643 }
1644
1645 // if tag_result_ptr is not null then allocate the result and copy
1646 // in the tag values.
1647 if (tag_result_ptr != nullptr) {
1648 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
1649 if (error != JVMTI_ERROR_NONE) {
1650 if (object_result_ptr != nullptr) {
1651 _env->Deallocate((unsigned char*)object_result_ptr);
1652 }
1653 return error;
1654 }
1655 for (int i=0; i<count; i++) {
1656 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
1657 }
1658 }
1659
1660 *count_ptr = count;
1661 return JVMTI_ERROR_NONE;
1662 }
1663 };
1664
1665 // return the list of objects with the specified tags
1666 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
1667 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1668
1669 // ensure flat object conversion is completed
1670 convert_flat_object_entries();
1671
1672 TagObjectCollector collector(env(), tags, count);
1673 {
1674 // iterate over all tagged objects
1675 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1676 // Can't post ObjectFree events here from a JavaThread, so this
1677 // will race with the gc_notification thread in the tiny
1678 // window where the object is not marked but hasn't been notified that
1679 // it is collected yet.
1680 _hashmap->entry_iterate(&collector);
1681 }
1682 return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
1683 }
1684
1685 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
1686 // (not performance critical as only used for roots)
1687 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
1688 switch (kind) {
1689 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL;
1690 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
1691 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL;
1692 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL;
1693 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD;
1694 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER;
1695 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER;
1696 }
1697 }
1698
1699 // Base class for all heap walk contexts. The base class maintains a flag
1700 // to indicate if the context is valid or not.
1701 class HeapWalkContext {
1702 private:
1703 bool _valid;
1704 public:
1705 HeapWalkContext(bool valid) { _valid = valid; }
1706 void invalidate() { _valid = false; }
1707 bool is_valid() const { return _valid; }
1708 };
1709
1710 // A basic heap walk context for the deprecated heap walking functions.
1711 // The context for a basic heap walk are the callbacks and fields used by
1712 // the referrer caching scheme.
1713 class BasicHeapWalkContext: public HeapWalkContext {
1714 private:
1715 jvmtiHeapRootCallback _heap_root_callback;
1716 jvmtiStackReferenceCallback _stack_ref_callback;
1717 jvmtiObjectReferenceCallback _object_ref_callback;
1718
1719 // used for caching
1720 JvmtiHeapwalkObject _last_referrer;
1721 jlong _last_referrer_tag;
1722
1723 public:
1724 BasicHeapWalkContext() : HeapWalkContext(false) { }
1725
1726 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
1727 jvmtiStackReferenceCallback stack_ref_callback,
1728 jvmtiObjectReferenceCallback object_ref_callback) :
1729 HeapWalkContext(true),
1730 _heap_root_callback(heap_root_callback),
1731 _stack_ref_callback(stack_ref_callback),
1732 _object_ref_callback(object_ref_callback),
1733 _last_referrer(),
1734 _last_referrer_tag(0) {
1735 }
1736
1737 // accessors
1738 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; }
1739 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; }
1740 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; }
1741
1742 JvmtiHeapwalkObject last_referrer() const { return _last_referrer; }
1743 void set_last_referrer(const JvmtiHeapwalkObject& referrer) { _last_referrer = referrer; }
1744 jlong last_referrer_tag() const { return _last_referrer_tag; }
1745 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
1746 };
1747
1748 // The advanced heap walk context for the FollowReferences functions.
1749 // The context is the callbacks, and the fields used for filtering.
1750 class AdvancedHeapWalkContext: public HeapWalkContext {
1751 private:
1752 jint _heap_filter;
1753 Klass* _klass_filter;
1754 const jvmtiHeapCallbacks* _heap_callbacks;
1755
1756 public:
1757 AdvancedHeapWalkContext() : HeapWalkContext(false) { }
1758
1759 AdvancedHeapWalkContext(jint heap_filter,
1760 Klass* klass_filter,
1761 const jvmtiHeapCallbacks* heap_callbacks) :
1762 HeapWalkContext(true),
1763 _heap_filter(heap_filter),
1764 _klass_filter(klass_filter),
1765 _heap_callbacks(heap_callbacks) {
1766 }
1767
1768 // accessors
1769 jint heap_filter() const { return _heap_filter; }
1770 Klass* klass_filter() const { return _klass_filter; }
1771
1772 jvmtiHeapReferenceCallback heap_reference_callback() const {
1773 return _heap_callbacks->heap_reference_callback;
1774 };
1775 jvmtiPrimitiveFieldCallback primitive_field_callback() const {
1776 return _heap_callbacks->primitive_field_callback;
1777 }
1778 jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
1779 return _heap_callbacks->array_primitive_value_callback;
1780 }
1781 jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
1782 return _heap_callbacks->string_primitive_value_callback;
1783 }
1784 };
1785
1786 // The CallbackInvoker is a class with static functions that the heap walk can call
1787 // into to invoke callbacks. It works in one of two modes. The "basic" mode is
1788 // used for the deprecated IterateOverReachableObjects functions. The "advanced"
1789 // mode is for the newer FollowReferences function which supports a lot of
1790 // additional callbacks.
1791 class CallbackInvoker : AllStatic {
1792 private:
1793 // heap walk styles
1794 enum { basic, advanced };
1795 static int _heap_walk_type;
1796 static bool is_basic_heap_walk() { return _heap_walk_type == basic; }
1797 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; }
1798
1799 // context for basic style heap walk
1800 static BasicHeapWalkContext _basic_context;
1801 static BasicHeapWalkContext* basic_context() {
1802 assert(_basic_context.is_valid(), "invalid");
1803 return &_basic_context;
1804 }
1805
1806 // context for advanced style heap walk
1807 static AdvancedHeapWalkContext _advanced_context;
1808 static AdvancedHeapWalkContext* advanced_context() {
1809 assert(_advanced_context.is_valid(), "invalid");
1810 return &_advanced_context;
1811 }
1812
1813 // context needed for all heap walks
1814 static JvmtiTagMap* _tag_map;
1815 static const void* _user_data;
1816 static JvmtiHeapwalkVisitStack* _visit_stack;
1817
1818 // accessors
1819 static JvmtiTagMap* tag_map() { return _tag_map; }
1820 static const void* user_data() { return _user_data; }
1821 static JvmtiHeapwalkVisitStack* visit_stack() { return _visit_stack; }
1822
1823 // if the object hasn't been visited then push it onto the visit stack
1824 // so that it will be visited later
1825 static inline bool check_for_visit(const JvmtiHeapwalkObject&obj) {
1826 visit_stack()->check_for_visit(obj);
1827 return true;
1828 }
1829
1830 // return element count if the obj is array, -1 otherwise
1831 static jint get_array_length(const JvmtiHeapwalkObject& obj) {
1832 if (!obj.klass()->is_array_klass()) {
1833 return -1;
1834 }
1835 assert(!obj.is_flat(), "array cannot be flat");
1836 return (jint)arrayOop(obj.obj())->length();
1837 }
1838
1839
1840 // invoke basic style callbacks
1841 static inline bool invoke_basic_heap_root_callback
1842 (jvmtiHeapRootKind root_kind, const JvmtiHeapwalkObject& obj);
1843 static inline bool invoke_basic_stack_ref_callback
1844 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
1845 int slot, const JvmtiHeapwalkObject& obj);
1846 static inline bool invoke_basic_object_reference_callback
1847 (jvmtiObjectReferenceKind ref_kind, const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1848
1849 // invoke advanced style callbacks
1850 static inline bool invoke_advanced_heap_root_callback
1851 (jvmtiHeapReferenceKind ref_kind, const JvmtiHeapwalkObject& obj);
1852 static inline bool invoke_advanced_stack_ref_callback
1853 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
1854 jmethodID method, jlocation bci, jint slot, const JvmtiHeapwalkObject& obj);
1855 static inline bool invoke_advanced_object_reference_callback
1856 (jvmtiHeapReferenceKind ref_kind, const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1857
1858 // used to report the value of primitive fields
1859 static inline bool report_primitive_field
1860 (jvmtiHeapReferenceKind ref_kind, const JvmtiHeapwalkObject& obj, jint index, address addr, char type);
1861
1862 public:
1863 // initialize for basic mode
1864 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1865 const void* user_data,
1866 BasicHeapWalkContext context,
1867 JvmtiHeapwalkVisitStack* visit_stack);
1868
1869 // initialize for advanced mode
1870 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1871 const void* user_data,
1872 AdvancedHeapWalkContext context,
1873 JvmtiHeapwalkVisitStack* visit_stack);
1874
1875 // functions to report roots
1876 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, const JvmtiHeapwalkObject& o);
1877 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
1878 jmethodID m, const JvmtiHeapwalkObject& o);
1879 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
1880 jmethodID method, jlocation bci, jint slot, const JvmtiHeapwalkObject& o);
1881
1882 // functions to report references
1883 static inline bool report_array_element_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1884 static inline bool report_class_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1885 static inline bool report_class_loader_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1886 static inline bool report_signers_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1887 static inline bool report_protection_domain_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1888 static inline bool report_superclass_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1889 static inline bool report_interface_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1890 static inline bool report_static_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot);
1891 static inline bool report_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot);
1892 static inline bool report_constant_pool_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1893 static inline bool report_primitive_array_values(const JvmtiHeapwalkObject& array);
1894 static inline bool report_string_value(const JvmtiHeapwalkObject& str);
1895 static inline bool report_primitive_instance_field(const JvmtiHeapwalkObject& o, jint index, address value, char type);
1896 static inline bool report_primitive_static_field(const JvmtiHeapwalkObject& o, jint index, address value, char type);
1897 };
1898
1899 // statics
1900 int CallbackInvoker::_heap_walk_type;
1901 BasicHeapWalkContext CallbackInvoker::_basic_context;
1902 AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
1903 JvmtiTagMap* CallbackInvoker::_tag_map;
1904 const void* CallbackInvoker::_user_data;
1905 JvmtiHeapwalkVisitStack* CallbackInvoker::_visit_stack;
1906
1907 // initialize for basic heap walk (IterateOverReachableObjects et al)
1908 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1909 const void* user_data,
1910 BasicHeapWalkContext context,
1911 JvmtiHeapwalkVisitStack* visit_stack) {
1912 _tag_map = tag_map;
1913 _user_data = user_data;
1914 _basic_context = context;
1915 _advanced_context.invalidate(); // will trigger assertion if used
1916 _heap_walk_type = basic;
1917 _visit_stack = visit_stack;
1918 }
1919
1920 // initialize for advanced heap walk (FollowReferences)
1921 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1922 const void* user_data,
1923 AdvancedHeapWalkContext context,
1924 JvmtiHeapwalkVisitStack* visit_stack) {
1925 _tag_map = tag_map;
1926 _user_data = user_data;
1927 _advanced_context = context;
1928 _basic_context.invalidate(); // will trigger assertion if used
1929 _heap_walk_type = advanced;
1930 _visit_stack = visit_stack;
1931 }
1932
1933
1934 // invoke basic style heap root callback
1935 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, const JvmtiHeapwalkObject& obj) {
1936 // if we heap roots should be reported
1937 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
1938 if (cb == nullptr) {
1939 return check_for_visit(obj);
1940 }
1941
1942 CallbackWrapper wrapper(tag_map(), obj);
1943 jvmtiIterationControl control = (*cb)(root_kind,
1944 wrapper.klass_tag(),
1945 wrapper.obj_size(),
1946 wrapper.obj_tag_p(),
1947 (void*)user_data());
1948 // push root to visit stack when following references
1949 if (control == JVMTI_ITERATION_CONTINUE &&
1950 basic_context()->object_ref_callback() != nullptr) {
1951 visit_stack()->push(obj);
1952 }
1953 return control != JVMTI_ITERATION_ABORT;
1954 }
1955
1956 // invoke basic style stack ref callback
1957 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
1958 jlong thread_tag,
1959 jint depth,
1960 jmethodID method,
1961 int slot,
1962 const JvmtiHeapwalkObject& obj) {
1963 // if we stack refs should be reported
1964 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
1965 if (cb == nullptr) {
1966 return check_for_visit(obj);
1967 }
1968
1969 CallbackWrapper wrapper(tag_map(), obj);
1970 jvmtiIterationControl control = (*cb)(root_kind,
1971 wrapper.klass_tag(),
1972 wrapper.obj_size(),
1973 wrapper.obj_tag_p(),
1974 thread_tag,
1975 depth,
1976 method,
1977 slot,
1978 (void*)user_data());
1979 // push root to visit stack when following references
1980 if (control == JVMTI_ITERATION_CONTINUE &&
1981 basic_context()->object_ref_callback() != nullptr) {
1982 visit_stack()->push(obj);
1983 }
1984 return control != JVMTI_ITERATION_ABORT;
1985 }
1986
1987 // invoke basic style object reference callback
1988 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
1989 const JvmtiHeapwalkObject& referrer,
1990 const JvmtiHeapwalkObject& referree,
1991 jint index) {
1992
1993 BasicHeapWalkContext* context = basic_context();
1994
1995 // callback requires the referrer's tag. If it's the same referrer
1996 // as the last call then we use the cached value.
1997 jlong referrer_tag;
1998 if (referrer == context->last_referrer()) {
1999 referrer_tag = context->last_referrer_tag();
2000 } else {
2001 referrer_tag = tag_map()->find(referrer);
2002 }
2003
2004 // do the callback
2005 CallbackWrapper wrapper(tag_map(), referree);
2006 jvmtiObjectReferenceCallback cb = context->object_ref_callback();
2007 jvmtiIterationControl control = (*cb)(ref_kind,
2008 wrapper.klass_tag(),
2009 wrapper.obj_size(),
2010 wrapper.obj_tag_p(),
2011 referrer_tag,
2012 index,
2013 (void*)user_data());
2014
2015 // record referrer and referrer tag. For self-references record the
2016 // tag value from the callback as this might differ from referrer_tag.
2017 context->set_last_referrer(referrer);
2018 if (referrer == referree) {
2019 context->set_last_referrer_tag(*wrapper.obj_tag_p());
2020 } else {
2021 context->set_last_referrer_tag(referrer_tag);
2022 }
2023
2024 if (control == JVMTI_ITERATION_CONTINUE) {
2025 return check_for_visit(referree);
2026 } else {
2027 return control != JVMTI_ITERATION_ABORT;
2028 }
2029 }
2030
2031 // invoke advanced style heap root callback
2032 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
2033 const JvmtiHeapwalkObject& obj) {
2034 AdvancedHeapWalkContext* context = advanced_context();
2035
2036 // check that callback is provided
2037 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2038 if (cb == nullptr) {
2039 return check_for_visit(obj);
2040 }
2041
2042 // apply class filter
2043 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2044 return check_for_visit(obj);
2045 }
2046
2047 // setup the callback wrapper
2048 CallbackWrapper wrapper(tag_map(), obj);
2049
2050 // apply tag filter
2051 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2052 wrapper.klass_tag(),
2053 context->heap_filter())) {
2054 return check_for_visit(obj);
2055 }
2056
2057 // for arrays we need the length, otherwise -1
2058 jint len = get_array_length(obj);
2059
2060 // invoke the callback
2061 jint res = (*cb)(ref_kind,
2062 nullptr, // referrer info
2063 wrapper.klass_tag(),
2064 0, // referrer_class_tag is 0 for heap root
2065 wrapper.obj_size(),
2066 wrapper.obj_tag_p(),
2067 nullptr, // referrer_tag_p
2068 len,
2069 (void*)user_data());
2070 if (res & JVMTI_VISIT_ABORT) {
2071 return false;// referrer class tag
2072 }
2073 if (res & JVMTI_VISIT_OBJECTS) {
2074 check_for_visit(obj);
2075 }
2076 return true;
2077 }
2078
2079 // report a reference from a thread stack to an object
2080 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
2081 jlong thread_tag,
2082 jlong tid,
2083 int depth,
2084 jmethodID method,
2085 jlocation bci,
2086 jint slot,
2087 const JvmtiHeapwalkObject& obj) {
2088 AdvancedHeapWalkContext* context = advanced_context();
2089
2090 // check that callback is provider
2091 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2092 if (cb == nullptr) {
2093 return check_for_visit(obj);
2094 }
2095
2096 // apply class filter
2097 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2098 return check_for_visit(obj);
2099 }
2100
2101 // setup the callback wrapper
2102 CallbackWrapper wrapper(tag_map(), obj);
2103
2104 // apply tag filter
2105 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2106 wrapper.klass_tag(),
2107 context->heap_filter())) {
2108 return check_for_visit(obj);
2109 }
2110
2111 // setup the referrer info
2112 jvmtiHeapReferenceInfo reference_info;
2113 reference_info.stack_local.thread_tag = thread_tag;
2114 reference_info.stack_local.thread_id = tid;
2115 reference_info.stack_local.depth = depth;
2116 reference_info.stack_local.method = method;
2117 reference_info.stack_local.location = bci;
2118 reference_info.stack_local.slot = slot;
2119
2120 // for arrays we need the length, otherwise -1
2121 jint len = get_array_length(obj);
2122
2123 // call into the agent
2124 int res = (*cb)(ref_kind,
2125 &reference_info,
2126 wrapper.klass_tag(),
2127 0, // referrer_class_tag is 0 for heap root (stack)
2128 wrapper.obj_size(),
2129 wrapper.obj_tag_p(),
2130 nullptr, // referrer_tag is 0 for root
2131 len,
2132 (void*)user_data());
2133
2134 if (res & JVMTI_VISIT_ABORT) {
2135 return false;
2136 }
2137 if (res & JVMTI_VISIT_OBJECTS) {
2138 check_for_visit(obj);
2139 }
2140 return true;
2141 }
2142
2143 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
2144 // only for ref_kinds defined by the JVM TI spec. Otherwise, null is passed.
2145 #define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \
2146 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \
2147 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
2148 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
2149 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \
2150 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
2151
2152 // invoke the object reference callback to report a reference
2153 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
2154 const JvmtiHeapwalkObject& referrer,
2155 const JvmtiHeapwalkObject& obj,
2156 jint index)
2157 {
2158 // field index is only valid field in reference_info
2159 static jvmtiHeapReferenceInfo reference_info = { 0 };
2160
2161 AdvancedHeapWalkContext* context = advanced_context();
2162
2163 // check that callback is provider
2164 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2165 if (cb == nullptr) {
2166 return check_for_visit(obj);
2167 }
2168
2169 // apply class filter
2170 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2171 return check_for_visit(obj);
2172 }
2173
2174 // setup the callback wrapper
2175 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
2176
2177 // apply tag filter
2178 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2179 wrapper.klass_tag(),
2180 context->heap_filter())) {
2181 return check_for_visit(obj);
2182 }
2183
2184 // field index is only valid field in reference_info
2185 reference_info.field.index = index;
2186
2187 // for arrays we need the length, otherwise -1
2188 jint len = get_array_length(obj);
2189
2190 // invoke the callback
2191 int res = (*cb)(ref_kind,
2192 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : nullptr,
2193 wrapper.klass_tag(),
2194 wrapper.referrer_klass_tag(),
2195 wrapper.obj_size(),
2196 wrapper.obj_tag_p(),
2197 wrapper.referrer_tag_p(),
2198 len,
2199 (void*)user_data());
2200
2201 if (res & JVMTI_VISIT_ABORT) {
2202 return false;
2203 }
2204 if (res & JVMTI_VISIT_OBJECTS) {
2205 check_for_visit(obj);
2206 }
2207 return true;
2208 }
2209
2210 // report a "simple root"
2211 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, const JvmtiHeapwalkObject& obj) {
2212 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
2213 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
2214
2215 if (is_basic_heap_walk()) {
2216 // map to old style root kind
2217 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
2218 return invoke_basic_heap_root_callback(root_kind, obj);
2219 } else {
2220 assert(is_advanced_heap_walk(), "wrong heap walk type");
2221 return invoke_advanced_heap_root_callback(kind, obj);
2222 }
2223 }
2224
2225
2226 // invoke the primitive array values
2227 inline bool CallbackInvoker::report_primitive_array_values(const JvmtiHeapwalkObject& obj) {
2228 assert(obj.klass()->is_typeArray_klass(), "not a primitive array");
2229
2230 AdvancedHeapWalkContext* context = advanced_context();
2231 assert(context->array_primitive_value_callback() != nullptr, "no callback");
2232
2233 // apply class filter
2234 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2235 return true;
2236 }
2237
2238 CallbackWrapper wrapper(tag_map(), obj);
2239
2240 // apply tag filter
2241 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2242 wrapper.klass_tag(),
2243 context->heap_filter())) {
2244 return true;
2245 }
2246
2247 // invoke the callback
2248 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
2249 &wrapper,
2250 obj,
2251 (void*)user_data());
2252 return (!(res & JVMTI_VISIT_ABORT));
2253 }
2254
2255 // invoke the string value callback
2256 inline bool CallbackInvoker::report_string_value(const JvmtiHeapwalkObject& str) {
2257 assert(str.klass() == vmClasses::String_klass(), "not a string");
2258
2259 AdvancedHeapWalkContext* context = advanced_context();
2260 assert(context->string_primitive_value_callback() != nullptr, "no callback");
2261
2262 // apply class filter
2263 if (is_filtered_by_klass_filter(str, context->klass_filter())) {
2264 return true;
2265 }
2266
2267 CallbackWrapper wrapper(tag_map(), str);
2268
2269 // apply tag filter
2270 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2271 wrapper.klass_tag(),
2272 context->heap_filter())) {
2273 return true;
2274 }
2275
2276 // invoke the callback
2277 int res = invoke_string_value_callback(context->string_primitive_value_callback(),
2278 &wrapper,
2279 str,
2280 (void*)user_data());
2281 return (!(res & JVMTI_VISIT_ABORT));
2282 }
2283
2284 // invoke the primitive field callback
2285 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
2286 const JvmtiHeapwalkObject& obj,
2287 jint index,
2288 address addr,
2289 char type)
2290 {
2291 // for primitive fields only the index will be set
2292 static jvmtiHeapReferenceInfo reference_info = { 0 };
2293
2294 AdvancedHeapWalkContext* context = advanced_context();
2295 assert(context->primitive_field_callback() != nullptr, "no callback");
2296
2297 // apply class filter
2298 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2299 return true;
2300 }
2301
2302 CallbackWrapper wrapper(tag_map(), obj);
2303
2304 // apply tag filter
2305 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2306 wrapper.klass_tag(),
2307 context->heap_filter())) {
2308 return true;
2309 }
2310
2311 // the field index in the referrer
2312 reference_info.field.index = index;
2313
2314 // map the type
2315 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
2316
2317 // setup the jvalue
2318 jvalue value;
2319 copy_to_jvalue(&value, addr, value_type);
2320
2321 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
2322 int res = (*cb)(ref_kind,
2323 &reference_info,
2324 wrapper.klass_tag(),
2325 wrapper.obj_tag_p(),
2326 value,
2327 value_type,
2328 (void*)user_data());
2329 return (!(res & JVMTI_VISIT_ABORT));
2330 }
2331
2332
2333 // instance field
2334 inline bool CallbackInvoker::report_primitive_instance_field(const JvmtiHeapwalkObject& obj,
2335 jint index,
2336 address value,
2337 char type) {
2338 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
2339 obj,
2340 index,
2341 value,
2342 type);
2343 }
2344
2345 // static field
2346 inline bool CallbackInvoker::report_primitive_static_field(const JvmtiHeapwalkObject& obj,
2347 jint index,
2348 address value,
2349 char type) {
2350 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
2351 obj,
2352 index,
2353 value,
2354 type);
2355 }
2356
2357 // report a JNI local (root object) to the profiler
2358 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, const JvmtiHeapwalkObject& obj) {
2359 if (is_basic_heap_walk()) {
2360 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
2361 thread_tag,
2362 depth,
2363 m,
2364 -1,
2365 obj);
2366 } else {
2367 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
2368 thread_tag, tid,
2369 depth,
2370 m,
2371 (jlocation)-1,
2372 -1,
2373 obj);
2374 }
2375 }
2376
2377
2378 // report a local (stack reference, root object)
2379 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
2380 jlong tid,
2381 jint depth,
2382 jmethodID method,
2383 jlocation bci,
2384 jint slot,
2385 const JvmtiHeapwalkObject& obj) {
2386 if (is_basic_heap_walk()) {
2387 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
2388 thread_tag,
2389 depth,
2390 method,
2391 slot,
2392 obj);
2393 } else {
2394 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
2395 thread_tag,
2396 tid,
2397 depth,
2398 method,
2399 bci,
2400 slot,
2401 obj);
2402 }
2403 }
2404
2405 // report an object referencing a class.
2406 inline bool CallbackInvoker::report_class_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2407 if (is_basic_heap_walk()) {
2408 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2409 } else {
2410 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
2411 }
2412 }
2413
2414 // report a class referencing its class loader.
2415 inline bool CallbackInvoker::report_class_loader_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2416 if (is_basic_heap_walk()) {
2417 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2418 } else {
2419 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2420 }
2421 }
2422
2423 // report a class referencing its signers.
2424 inline bool CallbackInvoker::report_signers_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2425 if (is_basic_heap_walk()) {
2426 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
2427 } else {
2428 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
2429 }
2430 }
2431
2432 // report a class referencing its protection domain..
2433 inline bool CallbackInvoker::report_protection_domain_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2434 if (is_basic_heap_walk()) {
2435 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2436 } else {
2437 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2438 }
2439 }
2440
2441 // report a class referencing its superclass.
2442 inline bool CallbackInvoker::report_superclass_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2443 if (is_basic_heap_walk()) {
2444 // Send this to be consistent with past implementation
2445 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2446 } else {
2447 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
2448 }
2449 }
2450
2451 // report a class referencing one of its interfaces.
2452 inline bool CallbackInvoker::report_interface_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2453 if (is_basic_heap_walk()) {
2454 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
2455 } else {
2456 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
2457 }
2458 }
2459
2460 // report a class referencing one of its static fields.
2461 inline bool CallbackInvoker::report_static_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot) {
2462 if (is_basic_heap_walk()) {
2463 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2464 } else {
2465 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2466 }
2467 }
2468
2469 // report an array referencing an element object
2470 inline bool CallbackInvoker::report_array_element_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index) {
2471 if (is_basic_heap_walk()) {
2472 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2473 } else {
2474 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2475 }
2476 }
2477
2478 // report an object referencing an instance field object
2479 inline bool CallbackInvoker::report_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot) {
2480 if (is_basic_heap_walk()) {
2481 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
2482 } else {
2483 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
2484 }
2485 }
2486
2487 // report an array referencing an element object
2488 inline bool CallbackInvoker::report_constant_pool_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index) {
2489 if (is_basic_heap_walk()) {
2490 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2491 } else {
2492 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2493 }
2494 }
2495
2496 // A supporting closure used to process simple roots
2497 class SimpleRootsClosure : public OopClosure {
2498 private:
2499 jvmtiHeapReferenceKind _kind;
2500 bool _continue;
2501
2502 jvmtiHeapReferenceKind root_kind() { return _kind; }
2503
2504 public:
2505 void set_kind(jvmtiHeapReferenceKind kind) {
2506 _kind = kind;
2507 _continue = true;
2508 }
2509
2510 inline bool stopped() {
2511 return !_continue;
2512 }
2513
2514 void do_oop(oop* obj_p) {
2515 // iteration has terminated
2516 if (stopped()) {
2517 return;
2518 }
2519
2520 oop o = NativeAccess<AS_NO_KEEPALIVE>::oop_load(obj_p);
2521 // ignore null
2522 if (o == nullptr) {
2523 return;
2524 }
2525
2526 assert(Universe::heap()->is_in(o), "should be impossible");
2527
2528 jvmtiHeapReferenceKind kind = root_kind();
2529
2530 // invoke the callback
2531 _continue = CallbackInvoker::report_simple_root(kind, o);
2532
2533 }
2534 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2535 };
2536
2537 // A supporting closure used to process JNI locals
2538 class JNILocalRootsClosure : public OopClosure {
2539 private:
2540 jlong _thread_tag;
2541 jlong _tid;
2542 jint _depth;
2543 jmethodID _method;
2544 bool _continue;
2545 public:
2546 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
2547 _thread_tag = thread_tag;
2548 _tid = tid;
2549 _depth = depth;
2550 _method = method;
2551 _continue = true;
2552 }
2553
2554 inline bool stopped() {
2555 return !_continue;
2556 }
2557
2558 void do_oop(oop* obj_p) {
2559 // iteration has terminated
2560 if (stopped()) {
2561 return;
2562 }
2563
2564 oop o = *obj_p;
2565 // ignore null
2566 if (o == nullptr) {
2567 return;
2568 }
2569
2570 // invoke the callback
2571 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
2572 }
2573 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2574 };
2575
2576 // Helper class to collect/report stack references.
2577 class StackRefCollector {
2578 private:
2579 JvmtiTagMap* _tag_map;
2580 JNILocalRootsClosure* _blk;
2581 // java_thread is needed only to report JNI local on top native frame;
2582 // I.e. it's required only for platform/carrier threads or mounted virtual threads.
2583 JavaThread* _java_thread;
2584
2585 oop _threadObj;
2586 jlong _thread_tag;
2587 jlong _tid;
2588
2589 bool _is_top_frame;
2590 int _depth;
2591 frame* _last_entry_frame;
2592
2593 bool report_java_stack_refs(StackValueCollection* values, jmethodID method, jlocation bci, jint slot_offset);
2594 bool report_native_stack_refs(jmethodID method);
2595
2596 public:
2597 StackRefCollector(JvmtiTagMap* tag_map, JNILocalRootsClosure* blk, JavaThread* java_thread)
2598 : _tag_map(tag_map), _blk(blk), _java_thread(java_thread),
2599 _threadObj(nullptr), _thread_tag(0), _tid(0),
2600 _is_top_frame(true), _depth(0), _last_entry_frame(nullptr)
2601 {
2602 }
2603
2604 bool set_thread(oop o);
2605 // Sets the thread and reports the reference to it with the specified kind.
2606 bool set_thread(jvmtiHeapReferenceKind kind, oop o);
2607
2608 bool do_frame(vframe* vf);
2609 // Handles frames until vf->sender() is null.
2610 bool process_frames(vframe* vf);
2611 };
2612
2613 bool StackRefCollector::set_thread(oop o) {
2614 _threadObj = o;
2615 _thread_tag = _tag_map->find(_threadObj);
2616 _tid = java_lang_Thread::thread_id(_threadObj);
2617
2618 _is_top_frame = true;
2619 _depth = 0;
2620 _last_entry_frame = nullptr;
2621
2622 return true;
2623 }
2624
2625 bool StackRefCollector::set_thread(jvmtiHeapReferenceKind kind, oop o) {
2626 return set_thread(o)
2627 && CallbackInvoker::report_simple_root(kind, _threadObj);
2628 }
2629
2630 bool StackRefCollector::report_java_stack_refs(StackValueCollection* values, jmethodID method, jlocation bci, jint slot_offset) {
2631 for (int index = 0; index < values->size(); index++) {
2632 if (values->at(index)->type() == T_OBJECT) {
2633 oop obj = values->obj_at(index)();
2634 if (obj == nullptr) {
2635 continue;
2636 }
2637 // stack reference
2638 if (!CallbackInvoker::report_stack_ref_root(_thread_tag, _tid, _depth, method,
2639 bci, slot_offset + index, obj)) {
2640 return false;
2641 }
2642 }
2643 }
2644 return true;
2645 }
2646
2647 bool StackRefCollector::report_native_stack_refs(jmethodID method) {
2648 _blk->set_context(_thread_tag, _tid, _depth, method);
2649 if (_is_top_frame) {
2650 // JNI locals for the top frame.
2651 if (_java_thread != nullptr) {
2652 _java_thread->active_handles()->oops_do(_blk);
2653 if (_blk->stopped()) {
2654 return false;
2655 }
2656 }
2657 } else {
2658 if (_last_entry_frame != nullptr) {
2659 // JNI locals for the entry frame.
2660 assert(_last_entry_frame->is_entry_frame(), "checking");
2661 _last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(_blk);
2662 if (_blk->stopped()) {
2663 return false;
2664 }
2665 }
2666 }
2667 return true;
2668 }
2669
2670 bool StackRefCollector::do_frame(vframe* vf) {
2671 if (vf->is_java_frame()) {
2672 // java frame (interpreted, compiled, ...)
2673 javaVFrame* jvf = javaVFrame::cast(vf);
2674
2675 jmethodID method = jvf->method()->jmethod_id();
2676
2677 if (!(jvf->method()->is_native())) {
2678 jlocation bci = (jlocation)jvf->bci();
2679 StackValueCollection* locals = jvf->locals();
2680 if (!report_java_stack_refs(locals, method, bci, 0)) {
2681 return false;
2682 }
2683 if (!report_java_stack_refs(jvf->expressions(), method, bci, locals->size())) {
2684 return false;
2685 }
2686
2687 // Follow oops from compiled nmethod.
2688 if (jvf->cb() != nullptr && jvf->cb()->is_nmethod()) {
2689 _blk->set_context(_thread_tag, _tid, _depth, method);
2690 // Need to apply load barriers for unmounted vthreads.
2691 nmethod* nm = jvf->cb()->as_nmethod();
2692 nm->run_nmethod_entry_barrier();
2693 nm->oops_do(_blk);
2694 if (_blk->stopped()) {
2695 return false;
2696 }
2697 }
2698 } else {
2699 // native frame
2700 if (!report_native_stack_refs(method)) {
2701 return false;
2702 }
2703 }
2704 _last_entry_frame = nullptr;
2705 _depth++;
2706 } else {
2707 // externalVFrame - for an entry frame then we report the JNI locals
2708 // when we find the corresponding javaVFrame
2709 frame* fr = vf->frame_pointer();
2710 assert(fr != nullptr, "sanity check");
2711 if (fr->is_entry_frame()) {
2712 _last_entry_frame = fr;
2713 }
2714 }
2715
2716 _is_top_frame = false;
2717
2718 return true;
2719 }
2720
2721 bool StackRefCollector::process_frames(vframe* vf) {
2722 while (vf != nullptr) {
2723 if (!do_frame(vf)) {
2724 return false;
2725 }
2726 vf = vf->sender();
2727 }
2728 return true;
2729 }
2730
2731
2732 // A VM operation to iterate over objects that are reachable from
2733 // a set of roots or an initial object.
2734 //
2735 // For VM_HeapWalkOperation the set of roots used is :-
2736 //
2737 // - All JNI global references
2738 // - All inflated monitors
2739 // - All classes loaded by the boot class loader (or all classes
2740 // in the event that class unloading is disabled)
2741 // - All java threads
2742 // - For each java thread then all locals and JNI local references
2743 // on the thread's execution stack
2744 // - All visible/explainable objects from Universes::oops_do
2745 //
2746 class VM_HeapWalkOperation: public VM_Operation {
2747 private:
2748 bool _is_advanced_heap_walk; // indicates FollowReferences
2749 JvmtiTagMap* _tag_map;
2750 Handle _initial_object;
2751 JvmtiHeapwalkVisitStack _visit_stack;
2752
2753 // Dead object tags in JvmtiTagMap
2754 GrowableArray<jlong>* _dead_objects;
2755
2756 bool _following_object_refs; // are we following object references
2757
2758 bool _reporting_primitive_fields; // optional reporting
2759 bool _reporting_primitive_array_values;
2760 bool _reporting_string_values;
2761
2762 // accessors
2763 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; }
2764 JvmtiTagMap* tag_map() const { return _tag_map; }
2765 Handle initial_object() const { return _initial_object; }
2766
2767 bool is_following_references() const { return _following_object_refs; }
2768
2769 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; }
2770 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
2771 bool is_reporting_string_values() const { return _reporting_string_values; }
2772
2773 JvmtiHeapwalkVisitStack* visit_stack() { return &_visit_stack; }
2774
2775 // iterate over the various object types
2776 inline bool iterate_over_array(const JvmtiHeapwalkObject& o);
2777 inline bool iterate_over_flat_array(const JvmtiHeapwalkObject& o);
2778 inline bool iterate_over_type_array(const JvmtiHeapwalkObject& o);
2779 inline bool iterate_over_class(const JvmtiHeapwalkObject& o);
2780 inline bool iterate_over_object(const JvmtiHeapwalkObject& o);
2781
2782 // root collection
2783 inline bool collect_simple_roots();
2784 inline bool collect_stack_roots();
2785 inline bool collect_stack_refs(JavaThread* java_thread, JNILocalRootsClosure* blk);
2786 inline bool collect_vthread_stack_refs(oop vt);
2787
2788 // visit an object
2789 inline bool visit(const JvmtiHeapwalkObject& o);
2790
2791 public:
2792 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2793 Handle initial_object,
2794 BasicHeapWalkContext callbacks,
2795 const void* user_data,
2796 GrowableArray<jlong>* objects);
2797
2798 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2799 Handle initial_object,
2800 AdvancedHeapWalkContext callbacks,
2801 const void* user_data,
2802 GrowableArray<jlong>* objects);
2803
2804 ~VM_HeapWalkOperation();
2805
2806 VMOp_Type type() const { return VMOp_HeapWalkOperation; }
2807 void doit();
2808 };
2809
2810
2811 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2812 Handle initial_object,
2813 BasicHeapWalkContext callbacks,
2814 const void* user_data,
2815 GrowableArray<jlong>* objects) {
2816 _is_advanced_heap_walk = false;
2817 _tag_map = tag_map;
2818 _initial_object = initial_object;
2819 _following_object_refs = (callbacks.object_ref_callback() != nullptr);
2820 _reporting_primitive_fields = false;
2821 _reporting_primitive_array_values = false;
2822 _reporting_string_values = false;
2823 _dead_objects = objects;
2824 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, user_data, callbacks, &_visit_stack);
2825 }
2826
2827 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2828 Handle initial_object,
2829 AdvancedHeapWalkContext callbacks,
2830 const void* user_data,
2831 GrowableArray<jlong>* objects) {
2832 _is_advanced_heap_walk = true;
2833 _tag_map = tag_map;
2834 _initial_object = initial_object;
2835 _following_object_refs = true;
2836 _reporting_primitive_fields = (callbacks.primitive_field_callback() != nullptr);;
2837 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != nullptr);;
2838 _reporting_string_values = (callbacks.string_primitive_value_callback() != nullptr);;
2839 _dead_objects = objects;
2840 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, user_data, callbacks, &_visit_stack);
2841 }
2842
2843 VM_HeapWalkOperation::~VM_HeapWalkOperation() {
2844 }
2845
2846 // an array references its class and has a reference to
2847 // each element in the array
2848 inline bool VM_HeapWalkOperation::iterate_over_array(const JvmtiHeapwalkObject& o) {
2849 assert(!o.is_flat(), "Array object cannot be flattened");
2850 objArrayOop array = objArrayOop(o.obj());
2851
2852 // array reference to its class
2853 oop mirror = ObjArrayKlass::cast(array->klass())->java_mirror();
2854 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2855 return false;
2856 }
2857
2858 // iterate over the array and report each reference to a
2859 // non-null element
2860 for (int index=0; index<array->length(); index++) {
2861 oop elem = array->obj_at(index);
2862 if (elem == nullptr) {
2863 continue;
2864 }
2865
2866 // report the array reference o[index] = elem
2867 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2868 return false;
2869 }
2870 }
2871 return true;
2872 }
2873
2874 // similar to iterate_over_array(), but itrates over flat array
2875 inline bool VM_HeapWalkOperation::iterate_over_flat_array(const JvmtiHeapwalkObject& o) {
2876 assert(!o.is_flat(), "Array object cannot be flattened");
2877 flatArrayOop array = flatArrayOop(o.obj());
2878 FlatArrayKlass* faklass = FlatArrayKlass::cast(array->klass());
2879 InlineKlass* vk = InlineKlass::cast(faklass->element_klass());
2880 bool need_null_check = faklass->layout_kind() == LayoutKind::NULLABLE_ATOMIC_FLAT;
2881
2882 // array reference to its class
2883 oop mirror = faklass->java_mirror();
2884 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2885 return false;
2886 }
2887
2888 // iterate over the array and report each reference to a
2889 // non-null element
2890 for (int index = 0; index < array->length(); index++) {
2891 address addr = (address)array->value_at_addr(index, faklass->layout_helper());
2892
2893 // check for null
2894 if (need_null_check) {
2895 if (vk->is_payload_marked_as_null(addr)) {
2896 continue;
2897 }
2898 }
2899
2900 // offset in the array oop
2901 int offset = (int)(addr - cast_from_oop<address>(array));
2902 JvmtiHeapwalkObject elem(o.obj(), offset, vk, faklass->layout_kind());
2903
2904 // report the array reference
2905 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2906 return false;
2907 }
2908 }
2909 return true;
2910 }
2911
2912 // a type array references its class
2913 inline bool VM_HeapWalkOperation::iterate_over_type_array(const JvmtiHeapwalkObject& o) {
2914 assert(!o.is_flat(), "Array object cannot be flattened");
2915 Klass* k = o.klass();
2916 oop mirror = k->java_mirror();
2917 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2918 return false;
2919 }
2920
2921 // report the array contents if required
2922 if (is_reporting_primitive_array_values()) {
2923 if (!CallbackInvoker::report_primitive_array_values(o)) {
2924 return false;
2925 }
2926 }
2927 return true;
2928 }
2929
2930 #ifdef ASSERT
2931 // verify that a static oop field is in range
2932 static inline bool verify_static_oop(InstanceKlass* ik,
2933 oop mirror, int offset) {
2934 address obj_p = cast_from_oop<address>(mirror) + offset;
2935 address start = (address)InstanceMirrorKlass::start_of_static_fields(mirror);
2936 address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize);
2937 assert(end >= start, "sanity check");
2938
2939 if (obj_p >= start && obj_p < end) {
2940 return true;
2941 } else {
2942 return false;
2943 }
2944 }
2945 #endif // #ifdef ASSERT
2946
2947 // a class references its super class, interfaces, class loader, ...
2948 // and finally its static fields
2949 inline bool VM_HeapWalkOperation::iterate_over_class(const JvmtiHeapwalkObject& o) {
2950 assert(!o.is_flat(), "Klass object cannot be flattened");
2951 Klass* klass = java_lang_Class::as_Klass(o.obj());
2952 int i;
2953
2954 if (klass->is_instance_klass()) {
2955 InstanceKlass* ik = InstanceKlass::cast(klass);
2956
2957 // Ignore the class if it hasn't been initialized yet
2958 if (!ik->is_linked()) {
2959 return true;
2960 }
2961
2962 // get the java mirror
2963 oop mirror_oop = klass->java_mirror();
2964 JvmtiHeapwalkObject mirror(mirror_oop);
2965
2966 // super (only if something more interesting than java.lang.Object)
2967 InstanceKlass* java_super = ik->java_super();
2968 if (java_super != nullptr && java_super != vmClasses::Object_klass()) {
2969 oop super = java_super->java_mirror();
2970 if (!CallbackInvoker::report_superclass_reference(mirror, super)) {
2971 return false;
2972 }
2973 }
2974
2975 // class loader
2976 oop cl = ik->class_loader();
2977 if (cl != nullptr) {
2978 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
2979 return false;
2980 }
2981 }
2982
2983 // protection domain
2984 oop pd = ik->protection_domain();
2985 if (pd != nullptr) {
2986 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
2987 return false;
2988 }
2989 }
2990
2991 // signers
2992 oop signers = ik->signers();
2993 if (signers != nullptr) {
2994 if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
2995 return false;
2996 }
2997 }
2998
2999 // references from the constant pool
3000 {
3001 ConstantPool* pool = ik->constants();
3002 for (int i = 1; i < pool->length(); i++) {
3003 constantTag tag = pool->tag_at(i).value();
3004 if (tag.is_string() || tag.is_klass() || tag.is_unresolved_klass()) {
3005 oop entry;
3006 if (tag.is_string()) {
3007 entry = pool->resolved_string_at(i);
3008 // If the entry is non-null it is resolved.
3009 if (entry == nullptr) {
3010 continue;
3011 }
3012 } else if (tag.is_klass()) {
3013 entry = pool->resolved_klass_at(i)->java_mirror();
3014 } else {
3015 // Code generated by JIT compilers might not resolve constant
3016 // pool entries. Treat them as resolved if they are loaded.
3017 assert(tag.is_unresolved_klass(), "must be");
3018 constantPoolHandle cp(Thread::current(), pool);
3019 Klass* klass = ConstantPool::klass_at_if_loaded(cp, i);
3020 if (klass == nullptr) {
3021 continue;
3022 }
3023 entry = klass->java_mirror();
3024 }
3025 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
3026 return false;
3027 }
3028 }
3029 }
3030 }
3031
3032 // interfaces
3033 // (These will already have been reported as references from the constant pool
3034 // but are specified by IterateOverReachableObjects and must be reported).
3035 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
3036 for (i = 0; i < interfaces->length(); i++) {
3037 oop interf = interfaces->at(i)->java_mirror();
3038 if (interf == nullptr) {
3039 continue;
3040 }
3041 if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
3042 return false;
3043 }
3044 }
3045
3046 // iterate over the static fields
3047
3048 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
3049 for (i=0; i<field_map->field_count(); i++) {
3050 ClassFieldDescriptor* field = field_map->field_at(i);
3051 char type = field->field_type();
3052 if (!is_primitive_field_type(type)) {
3053 oop fld_o = mirror_oop->obj_field(field->field_offset());
3054 assert(verify_static_oop(ik, mirror_oop, field->field_offset()), "sanity check");
3055 if (fld_o != nullptr) {
3056 int slot = field->field_index();
3057 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
3058 delete field_map;
3059 return false;
3060 }
3061 }
3062 } else {
3063 if (is_reporting_primitive_fields()) {
3064 address addr = cast_from_oop<address>(mirror_oop) + field->field_offset();
3065 int slot = field->field_index();
3066 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
3067 delete field_map;
3068 return false;
3069 }
3070 }
3071 }
3072 }
3073 delete field_map;
3074
3075 return true;
3076 }
3077
3078 return true;
3079 }
3080
3081 // an object references a class and its instance fields
3082 // (static fields are ignored here as we report these as
3083 // references from the class).
3084 inline bool VM_HeapWalkOperation::iterate_over_object(const JvmtiHeapwalkObject& o) {
3085 // reference to the class
3086 if (!CallbackInvoker::report_class_reference(o, o.klass()->java_mirror())) {
3087 return false;
3088 }
3089
3090 // iterate over instance fields
3091 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o.klass());
3092 for (int i=0; i<field_map->field_count(); i++) {
3093 ClassFieldDescriptor* field = field_map->field_at(i);
3094 char type = field->field_type();
3095 int slot = field->field_index();
3096 int field_offset = field->field_offset();
3097 if (o.is_flat()) {
3098 // the object is inlined, its fields are stored without the header
3099 field_offset += o.offset() - o.inline_klass()->payload_offset();
3100 }
3101 if (!is_primitive_field_type(type)) {
3102 if (field->is_flat()) {
3103 // check for possible nulls
3104 bool can_be_null = field->layout_kind() == LayoutKind::NULLABLE_ATOMIC_FLAT;
3105 if (can_be_null) {
3106 address payload = cast_from_oop<address>(o.obj()) + field_offset;
3107 if (field->inline_klass()->is_payload_marked_as_null(payload)) {
3108 continue;
3109 }
3110 }
3111 JvmtiHeapwalkObject field_obj(o.obj(), field_offset, field->inline_klass(), field->layout_kind());
3112 if (!CallbackInvoker::report_field_reference(o, field_obj, slot)) {
3113 return false;
3114 }
3115 } else {
3116 oop fld_o = o.obj()->obj_field_access<AS_NO_KEEPALIVE | ON_UNKNOWN_OOP_REF>(field_offset);
3117 // ignore any objects that aren't visible to profiler
3118 if (fld_o != nullptr) {
3119 assert(Universe::heap()->is_in(fld_o), "unsafe code should not have references to Klass* anymore");
3120 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
3121 return false;
3122 }
3123 }
3124 }
3125 } else {
3126 if (is_reporting_primitive_fields()) {
3127 // primitive instance field
3128 address addr = cast_from_oop<address>(o.obj()) + field_offset;
3129 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
3130 return false;
3131 }
3132 }
3133 }
3134 }
3135
3136 // if the object is a java.lang.String
3137 if (is_reporting_string_values() &&
3138 o.klass() == vmClasses::String_klass()) {
3139 if (!CallbackInvoker::report_string_value(o)) {
3140 return false;
3141 }
3142 }
3143 return true;
3144 }
3145
3146
3147 // Collects all simple (non-stack) roots except for threads;
3148 // threads are handled in collect_stack_roots() as an optimization.
3149 // if there's a heap root callback provided then the callback is
3150 // invoked for each simple root.
3151 // if an object reference callback is provided then all simple
3152 // roots are pushed onto the marking stack so that they can be
3153 // processed later
3154 //
3155 inline bool VM_HeapWalkOperation::collect_simple_roots() {
3156 SimpleRootsClosure blk;
3157
3158 // JNI globals
3159 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
3160 JNIHandles::oops_do(&blk);
3161 if (blk.stopped()) {
3162 return false;
3163 }
3164
3165 // Preloaded classes and loader from the system dictionary
3166 blk.set_kind(JVMTI_HEAP_REFERENCE_SYSTEM_CLASS);
3167 CLDToOopClosure cld_closure(&blk, false);
3168 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
3169 if (blk.stopped()) {
3170 return false;
3171 }
3172
3173 // threads are now handled in collect_stack_roots()
3174
3175 // Other kinds of roots maintained by HotSpot
3176 // Many of these won't be visible but others (such as instances of important
3177 // exceptions) will be visible.
3178 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3179 Universe::vm_global()->oops_do(&blk);
3180 if (blk.stopped()) {
3181 return false;
3182 }
3183
3184 return true;
3185 }
3186
3187 // Reports the thread as JVMTI_HEAP_REFERENCE_THREAD,
3188 // walks the stack of the thread, finds all references (locals
3189 // and JNI calls) and reports these as stack references.
3190 inline bool VM_HeapWalkOperation::collect_stack_refs(JavaThread* java_thread,
3191 JNILocalRootsClosure* blk)
3192 {
3193 oop threadObj = java_thread->threadObj();
3194 oop mounted_vt = java_thread->is_vthread_mounted() ? java_thread->vthread() : nullptr;
3195 if (mounted_vt != nullptr && !JvmtiEnvBase::is_vthread_alive(mounted_vt)) {
3196 mounted_vt = nullptr;
3197 }
3198 assert(threadObj != nullptr, "sanity check");
3199
3200 StackRefCollector stack_collector(tag_map(), blk, java_thread);
3201
3202 if (!java_thread->has_last_Java_frame()) {
3203 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_THREAD, threadObj)) {
3204 return false;
3205 }
3206 // no last java frame but there may be JNI locals
3207 blk->set_context(_tag_map->find(threadObj), java_lang_Thread::thread_id(threadObj), 0, (jmethodID)nullptr);
3208 java_thread->active_handles()->oops_do(blk);
3209 return !blk->stopped();
3210 }
3211 // vframes are resource allocated
3212 Thread* current_thread = Thread::current();
3213 ResourceMark rm(current_thread);
3214 HandleMark hm(current_thread);
3215
3216 RegisterMap reg_map(java_thread,
3217 RegisterMap::UpdateMap::include,
3218 RegisterMap::ProcessFrames::include,
3219 RegisterMap::WalkContinuation::include);
3220
3221 // first handle mounted vthread (if any)
3222 if (mounted_vt != nullptr) {
3223 frame f = java_thread->last_frame();
3224 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread);
3225 // report virtual thread as JVMTI_HEAP_REFERENCE_OTHER
3226 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_OTHER, mounted_vt)) {
3227 return false;
3228 }
3229 // split virtual thread and carrier thread stacks by vthread entry ("enterSpecial") frame,
3230 // consider vthread entry frame as the last vthread stack frame
3231 while (vf != nullptr) {
3232 if (!stack_collector.do_frame(vf)) {
3233 return false;
3234 }
3235 if (vf->is_vthread_entry()) {
3236 break;
3237 }
3238 vf = vf->sender();
3239 }
3240 }
3241 // Platform or carrier thread.
3242 vframe* vf = JvmtiEnvBase::get_cthread_last_java_vframe(java_thread, ®_map);
3243 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_THREAD, threadObj)) {
3244 return false;
3245 }
3246 return stack_collector.process_frames(vf);
3247 }
3248
3249
3250 // Collects the simple roots for all threads and collects all
3251 // stack roots - for each thread it walks the execution
3252 // stack to find all references and local JNI refs.
3253 inline bool VM_HeapWalkOperation::collect_stack_roots() {
3254 JNILocalRootsClosure blk;
3255 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
3256 oop threadObj = thread->threadObj();
3257 if (threadObj != nullptr && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3258 if (!collect_stack_refs(thread, &blk)) {
3259 return false;
3260 }
3261 }
3262 }
3263 return true;
3264 }
3265
3266 // Reports stack references for the unmounted virtual thread.
3267 inline bool VM_HeapWalkOperation::collect_vthread_stack_refs(oop vt) {
3268 if (!JvmtiEnvBase::is_vthread_alive(vt)) {
3269 return true;
3270 }
3271 ContinuationWrapper cont(java_lang_VirtualThread::continuation(vt));
3272 if (cont.is_empty()) {
3273 return true;
3274 }
3275 assert(!cont.is_mounted(), "sanity check");
3276
3277 stackChunkOop chunk = cont.last_nonempty_chunk();
3278 if (chunk == nullptr || chunk->is_empty()) {
3279 return true;
3280 }
3281
3282 // vframes are resource allocated
3283 Thread* current_thread = Thread::current();
3284 ResourceMark rm(current_thread);
3285 HandleMark hm(current_thread);
3286
3287 RegisterMap reg_map(cont.continuation(), RegisterMap::UpdateMap::include);
3288
3289 JNILocalRootsClosure blk;
3290 // JavaThread is not required for unmounted virtual threads
3291 StackRefCollector stack_collector(tag_map(), &blk, nullptr);
3292 // reference to the vthread is already reported
3293 if (!stack_collector.set_thread(vt)) {
3294 return false;
3295 }
3296
3297 frame fr = chunk->top_frame(®_map);
3298 vframe* vf = vframe::new_vframe(&fr, ®_map, nullptr);
3299 return stack_collector.process_frames(vf);
3300 }
3301
3302 // visit an object
3303 // first mark the object as visited
3304 // second get all the outbound references from this object (in other words, all
3305 // the objects referenced by this object).
3306 //
3307 bool VM_HeapWalkOperation::visit(const JvmtiHeapwalkObject& o) {
3308 // mark object as visited
3309 assert(!visit_stack()->is_visited(o), "can't visit same object more than once");
3310 visit_stack()->mark_visited(o);
3311
3312 Klass* klass = o.klass();
3313 // instance
3314 if (klass->is_instance_klass()) {
3315 if (klass == vmClasses::Class_klass()) {
3316 assert(!o.is_flat(), "Class object cannot be flattened");
3317 if (!java_lang_Class::is_primitive(o.obj())) {
3318 // a java.lang.Class
3319 return iterate_over_class(o);
3320 }
3321 } else {
3322 // we report stack references only when initial object is not specified
3323 // (in the case we start from heap roots which include platform thread stack references)
3324 if (initial_object().is_null() && java_lang_VirtualThread::is_subclass(klass)) {
3325 assert(!o.is_flat(), "VirtualThread object cannot be flattened");
3326 if (!collect_vthread_stack_refs(o.obj())) {
3327 return false;
3328 }
3329 }
3330 return iterate_over_object(o);
3331 }
3332 }
3333
3334 // flat object array
3335 if (klass->is_flatArray_klass()) {
3336 return iterate_over_flat_array(o);
3337 }
3338
3339 // object array
3340 if (klass->is_objArray_klass()) {
3341 return iterate_over_array(o);
3342 }
3343
3344 // type array
3345 if (klass->is_typeArray_klass()) {
3346 return iterate_over_type_array(o);
3347 }
3348
3349 return true;
3350 }
3351
3352 void VM_HeapWalkOperation::doit() {
3353 ResourceMark rm;
3354 ClassFieldMapCacheMark cm;
3355
3356 JvmtiTagMap::check_hashmaps_for_heapwalk(_dead_objects);
3357
3358 assert(visit_stack()->is_empty(), "visit stack must be empty");
3359
3360 // the heap walk starts with an initial object or the heap roots
3361 if (initial_object().is_null()) {
3362 // can result in a big performance boost for an agent that is
3363 // focused on analyzing references in the thread stacks.
3364 if (!collect_stack_roots()) return;
3365
3366 if (!collect_simple_roots()) return;
3367 } else {
3368 visit_stack()->push(initial_object()());
3369 }
3370
3371 // object references required
3372 if (is_following_references()) {
3373
3374 // visit each object until all reachable objects have been
3375 // visited or the callback asked to terminate the iteration.
3376 while (!visit_stack()->is_empty()) {
3377 const JvmtiHeapwalkObject o = visit_stack()->pop();
3378 if (!visit_stack()->is_visited(o)) {
3379 if (!visit(o)) {
3380 break;
3381 }
3382 }
3383 }
3384 }
3385 }
3386
3387 // iterate over all objects that are reachable from a set of roots
3388 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
3389 jvmtiStackReferenceCallback stack_ref_callback,
3390 jvmtiObjectReferenceCallback object_ref_callback,
3391 const void* user_data) {
3392 // VTMS transitions must be disabled before the EscapeBarrier.
3393 JvmtiVTMSTransitionDisabler disabler;
3394
3395 JavaThread* jt = JavaThread::current();
3396 EscapeBarrier eb(true, jt);
3397 eb.deoptimize_objects_all_threads();
3398 Arena dead_object_arena(mtServiceability);
3399 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
3400
3401 {
3402 MutexLocker ml(Heap_lock);
3403 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
3404 VM_HeapWalkOperation op(this, Handle(), context, user_data, &dead_objects);
3405 VMThread::execute(&op);
3406 }
3407 convert_flat_object_entries();
3408
3409 // Post events outside of Heap_lock
3410 post_dead_objects(&dead_objects);
3411 }
3412
3413 // iterate over all objects that are reachable from a given object
3414 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
3415 jvmtiObjectReferenceCallback object_ref_callback,
3416 const void* user_data) {
3417 oop obj = JNIHandles::resolve(object);
3418 Handle initial_object(Thread::current(), obj);
3419
3420 Arena dead_object_arena(mtServiceability);
3421 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
3422
3423 JvmtiVTMSTransitionDisabler disabler;
3424
3425 {
3426 MutexLocker ml(Heap_lock);
3427 BasicHeapWalkContext context(nullptr, nullptr, object_ref_callback);
3428 VM_HeapWalkOperation op(this, initial_object, context, user_data, &dead_objects);
3429 VMThread::execute(&op);
3430 }
3431 convert_flat_object_entries();
3432
3433 // Post events outside of Heap_lock
3434 post_dead_objects(&dead_objects);
3435 }
3436
3437 // follow references from an initial object or the GC roots
3438 void JvmtiTagMap::follow_references(jint heap_filter,
3439 Klass* klass,
3440 jobject object,
3441 const jvmtiHeapCallbacks* callbacks,
3442 const void* user_data)
3443 {
3444 // VTMS transitions must be disabled before the EscapeBarrier.
3445 JvmtiVTMSTransitionDisabler disabler;
3446
3447 oop obj = JNIHandles::resolve(object);
3448 JavaThread* jt = JavaThread::current();
3449 Handle initial_object(jt, obj);
3450 // EA based optimizations that are tagged or reachable from initial_object are already reverted.
3451 EscapeBarrier eb(initial_object.is_null() &&
3452 !(heap_filter & JVMTI_HEAP_FILTER_UNTAGGED),
3453 jt);
3454 eb.deoptimize_objects_all_threads();
3455
3456 Arena dead_object_arena(mtServiceability);
3457 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
3458
3459 {
3460 MutexLocker ml(Heap_lock);
3461 AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
3462 VM_HeapWalkOperation op(this, initial_object, context, user_data, &dead_objects);
3463 VMThread::execute(&op);
3464 }
3465 convert_flat_object_entries();
3466
3467 // Post events outside of Heap_lock
3468 post_dead_objects(&dead_objects);
3469 }
3470
3471 // Verify gc_notification follows set_needs_cleaning.
3472 DEBUG_ONLY(static bool notified_needs_cleaning = false;)
3473
3474 void JvmtiTagMap::set_needs_cleaning() {
3475 assert(SafepointSynchronize::is_at_safepoint(), "called in gc pause");
3476 assert(Thread::current()->is_VM_thread(), "should be the VM thread");
3477 // Can't assert !notified_needs_cleaning; a partial GC might be upgraded
3478 // to a full GC and do this twice without intervening gc_notification.
3479 DEBUG_ONLY(notified_needs_cleaning = true;)
3480
3481 JvmtiEnvIterator it;
3482 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) {
3483 JvmtiTagMap* tag_map = env->tag_map_acquire();
3484 if (tag_map != nullptr) {
3485 tag_map->_needs_cleaning = !tag_map->is_empty();
3486 }
3487 }
3488 }
3489
3490 void JvmtiTagMap::gc_notification(size_t num_dead_entries) {
3491 assert(notified_needs_cleaning, "missing GC notification");
3492 DEBUG_ONLY(notified_needs_cleaning = false;)
3493
3494 // Notify ServiceThread if there's work to do.
3495 {
3496 MonitorLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
3497 _has_object_free_events = (num_dead_entries != 0);
3498 if (_has_object_free_events) ml.notify_all();
3499 }
3500
3501 // If no dead entries then cancel cleaning requests.
3502 if (num_dead_entries == 0) {
3503 JvmtiEnvIterator it;
3504 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) {
3505 JvmtiTagMap* tag_map = env->tag_map_acquire();
3506 if (tag_map != nullptr) {
3507 MutexLocker ml (tag_map->lock(), Mutex::_no_safepoint_check_flag);
3508 tag_map->_needs_cleaning = false;
3509 }
3510 }
3511 }
3512 }
3513
3514 // Used by ServiceThread to discover there is work to do.
3515 bool JvmtiTagMap::has_object_free_events_and_reset() {
3516 assert_lock_strong(Service_lock);
3517 bool result = _has_object_free_events;
3518 _has_object_free_events = false;
3519 return result;
3520 }
3521
3522 // Used by ServiceThread to clean up tagmaps.
3523 void JvmtiTagMap::flush_all_object_free_events() {
3524 JavaThread* thread = JavaThread::current();
3525 JvmtiEnvIterator it;
3526 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) {
3527 JvmtiTagMap* tag_map = env->tag_map_acquire();
3528 if (tag_map != nullptr) {
3529 tag_map->flush_object_free_events();
3530 ThreadBlockInVM tbiv(thread); // Be safepoint-polite while looping.
3531 }
3532 }
3533 }