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/fieldStreams.inline.hpp"
40 #include "oops/instanceMirrorKlass.hpp"
41 #include "oops/klass.inline.hpp"
42 #include "oops/objArrayKlass.hpp"
43 #include "oops/objArrayOop.inline.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "oops/typeArrayOop.inline.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/mountUnmountDisabler.hpp"
61 #include "runtime/mutex.hpp"
62 #include "runtime/mutexLocker.hpp"
63 #include "runtime/safepoint.hpp"
64 #include "runtime/threadSMR.hpp"
65 #include "runtime/timerTrace.hpp"
66 #include "runtime/vframe.hpp"
67 #include "runtime/vmOperations.hpp"
68 #include "runtime/vmThread.hpp"
69 #include "utilities/macros.hpp"
70 #include "utilities/objectBitSet.inline.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 count += interfaces->at(i)->java_fields_count();
677
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->super(); super_klass != nullptr; super_klass = super_klass->super()) {
699 index += super_klass->java_fields_count();
700 }
701
702 for (JavaFieldStream fld(ik); !fld.done(); fld.next(), index++) {
703 // ignore instance fields
704 if (!fld.access_flags().is_static()) {
705 continue;
706 }
707 field_map->add(index, fld);
708 }
709
710 return field_map;
711 }
712
713 // Returns a heap allocated ClassFieldMap to describe the instance fields
714 // of the given class. All instance fields are included (this means public
715 // and private fields declared in superclasses too).
716 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(Klass* k) {
717 InstanceKlass* ik = InstanceKlass::cast(k);
718
719 // create the field map
720 ClassFieldMap* field_map = new ClassFieldMap();
721
722 // fields of the superclasses are reported first, so need to know total field number to calculate field indices
723 int total_field_number = interfaces_field_count(ik);
724 for (InstanceKlass* klass = ik; klass != nullptr; klass = klass->super()) {
725 total_field_number += klass->java_fields_count();
726 }
727
728 for (InstanceKlass* klass = ik; klass != nullptr; klass = klass->super()) {
729 JavaFieldStream fld(klass);
730 int start_index = total_field_number - klass->java_fields_count();
731 for (int index = 0; !fld.done(); fld.next(), index++) {
732 // ignore static fields
733 if (fld.access_flags().is_static()) {
734 continue;
735 }
736 field_map->add(start_index + index, fld);
737 }
738 // update total_field_number for superclass (decrease by the field count in the current class)
739 total_field_number = start_index;
740 }
741
742 return field_map;
743 }
744
745 // Helper class used to cache a ClassFileMap for the instance fields of
746 // a cache. A JvmtiCachedClassFieldMap can be cached by an InstanceKlass during
747 // heap iteration and avoid creating a field map for each object in the heap
748 // (only need to create the map when the first instance of a class is encountered).
749 //
750 class JvmtiCachedClassFieldMap : public CHeapObj<mtInternal> {
751 private:
752 enum {
753 initial_class_count = 200
754 };
755 ClassFieldMap* _field_map;
756
757 ClassFieldMap* field_map() const { return _field_map; }
758
759 JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
760 ~JvmtiCachedClassFieldMap();
761
762 static GrowableArray<InstanceKlass*>* _class_list;
763 static void add_to_class_list(InstanceKlass* ik);
764
765 public:
766 // returns the field map for a given klass (returning map cached
767 // by InstanceKlass if possible
768 static ClassFieldMap* get_map_of_instance_fields(Klass* k);
769
770 // removes the field map from all instanceKlasses - should be
771 // called before VM operation completes
772 static void clear_cache();
773
774 // returns the number of ClassFieldMap cached by instanceKlasses
775 static int cached_field_map_count();
776 };
777
778 GrowableArray<InstanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
779
780 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
781 _field_map = field_map;
782 }
783
784 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
785 if (_field_map != nullptr) {
786 delete _field_map;
787 }
788 }
789
790 // Marker class to ensure that the class file map cache is only used in a defined
791 // scope.
792 class ClassFieldMapCacheMark : public StackObj {
793 private:
794 static bool _is_active;
795 public:
796 ClassFieldMapCacheMark() {
797 assert(Thread::current()->is_VM_thread(), "must be VMThread");
798 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
799 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
800 _is_active = true;
801 }
802 ~ClassFieldMapCacheMark() {
803 JvmtiCachedClassFieldMap::clear_cache();
804 _is_active = false;
805 }
806 static bool is_active() { return _is_active; }
807 };
808
809 bool ClassFieldMapCacheMark::_is_active;
810
811 // record that the given InstanceKlass is caching a field map
812 void JvmtiCachedClassFieldMap::add_to_class_list(InstanceKlass* ik) {
813 if (_class_list == nullptr) {
814 _class_list = new (mtServiceability)
815 GrowableArray<InstanceKlass*>(initial_class_count, mtServiceability);
816 }
817 _class_list->push(ik);
818 }
819
820 // returns the instance field map for the given klass
821 // (returns field map cached by the InstanceKlass if possible)
822 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(Klass *k) {
823 assert(Thread::current()->is_VM_thread(), "must be VMThread");
824 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
825
826 InstanceKlass* ik = InstanceKlass::cast(k);
827
828 // return cached map if possible
829 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
830 if (cached_map != nullptr) {
831 assert(cached_map->field_map() != nullptr, "missing field list");
832 return cached_map->field_map();
833 } else {
834 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(k);
835 cached_map = new JvmtiCachedClassFieldMap(field_map);
836 ik->set_jvmti_cached_class_field_map(cached_map);
837 add_to_class_list(ik);
838 return field_map;
839 }
840 }
841
842 // remove the fields maps cached from all instanceKlasses
843 void JvmtiCachedClassFieldMap::clear_cache() {
844 assert(Thread::current()->is_VM_thread(), "must be VMThread");
845 if (_class_list != nullptr) {
846 for (int i = 0; i < _class_list->length(); i++) {
847 InstanceKlass* ik = _class_list->at(i);
848 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
849 assert(cached_map != nullptr, "should not be null");
850 ik->set_jvmti_cached_class_field_map(nullptr);
851 delete cached_map; // deletes the encapsulated field map
852 }
853 delete _class_list;
854 _class_list = nullptr;
855 }
856 }
857
858 // returns the number of ClassFieldMap cached by instanceKlasses
859 int JvmtiCachedClassFieldMap::cached_field_map_count() {
860 return (_class_list == nullptr) ? 0 : _class_list->length();
861 }
862
863 // helper function to indicate if an object is filtered by its tag or class tag
864 static inline bool is_filtered_by_heap_filter(jlong obj_tag,
865 jlong klass_tag,
866 int heap_filter) {
867 // apply the heap filter
868 if (obj_tag != 0) {
869 // filter out tagged objects
870 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
871 } else {
872 // filter out untagged objects
873 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
874 }
875 if (klass_tag != 0) {
876 // filter out objects with tagged classes
877 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
878 } else {
879 // filter out objects with untagged classes.
880 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
881 }
882 return false;
883 }
884
885 // helper function to indicate if an object is filtered by a klass filter
886 static inline bool is_filtered_by_klass_filter(const JvmtiHeapwalkObject& obj, Klass* klass_filter) {
887 if (klass_filter != nullptr) {
888 if (obj.klass() != klass_filter) {
889 return true;
890 }
891 }
892 return false;
893 }
894
895 // helper function to tell if a field is a primitive field or not
896 static inline bool is_primitive_field_type(char type) {
897 return (type != JVM_SIGNATURE_CLASS && type != JVM_SIGNATURE_ARRAY);
898 }
899
900 // helper function to copy the value from location addr to jvalue.
901 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
902 switch (value_type) {
903 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
904 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; }
905 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; }
906 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; }
907 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; }
908 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; }
909 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; }
910 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; }
911 default: ShouldNotReachHere();
912 }
913 }
914
915 // helper function to invoke string primitive value callback
916 // returns visit control flags
917 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
918 CallbackWrapper* wrapper,
919 const JvmtiHeapwalkObject& obj,
920 void* user_data)
921 {
922 assert(!obj.is_flat(), "cannot be flat");
923 oop str = obj.obj();
924 assert(str->klass() == vmClasses::String_klass(), "not a string");
925
926 typeArrayOop s_value = java_lang_String::value(str);
927
928 // JDK-6584008: the value field may be null if a String instance is
929 // partially constructed.
930 if (s_value == nullptr) {
931 return 0;
932 }
933 // get the string value and length
934 // (string value may be offset from the base)
935 int s_len = java_lang_String::length(str);
936 bool is_latin1 = java_lang_String::is_latin1(str);
937 jchar* value;
938 if (s_len > 0) {
939 if (!is_latin1) {
940 value = s_value->char_at_addr(0);
941 } else {
942 // Inflate latin1 encoded string to UTF16
943 jchar* buf = NEW_C_HEAP_ARRAY(jchar, s_len, mtInternal);
944 for (int i = 0; i < s_len; i++) {
945 buf[i] = ((jchar) s_value->byte_at(i)) & 0xff;
946 }
947 value = &buf[0];
948 }
949 } else {
950 // Don't use char_at_addr(0) if length is 0
951 value = (jchar*) s_value->base(T_CHAR);
952 }
953
954 // invoke the callback
955 jint res = (*cb)(wrapper->klass_tag(),
956 wrapper->obj_size(),
957 wrapper->obj_tag_p(),
958 value,
959 (jint)s_len,
960 user_data);
961
962 if (is_latin1 && s_len > 0) {
963 FREE_C_HEAP_ARRAY(jchar, value);
964 }
965 return res;
966 }
967
968 // helper function to invoke string primitive value callback
969 // returns visit control flags
970 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
971 CallbackWrapper* wrapper,
972 const JvmtiHeapwalkObject& obj,
973 void* user_data)
974 {
975 assert(!obj.is_flat(), "cannot be flat");
976 assert(obj.obj()->is_typeArray(), "not a primitive array");
977
978 // get base address of first element
979 typeArrayOop array = typeArrayOop(obj.obj());
980 BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
981 void* elements = array->base(type);
982
983 // jvmtiPrimitiveType is defined so this mapping is always correct
984 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
985
986 return (*cb)(wrapper->klass_tag(),
987 wrapper->obj_size(),
988 wrapper->obj_tag_p(),
989 (jint)array->length(),
990 elem_type,
991 elements,
992 user_data);
993 }
994
995 // helper function to invoke the primitive field callback for all static fields
996 // of a given class
997 static jint invoke_primitive_field_callback_for_static_fields
998 (CallbackWrapper* wrapper,
999 oop obj,
1000 jvmtiPrimitiveFieldCallback cb,
1001 void* user_data)
1002 {
1003 // for static fields only the index will be set
1004 static jvmtiHeapReferenceInfo reference_info = { 0 };
1005
1006 assert(obj->klass() == vmClasses::Class_klass(), "not a class");
1007 if (java_lang_Class::is_primitive(obj)) {
1008 return 0;
1009 }
1010 Klass* klass = java_lang_Class::as_Klass(obj);
1011
1012 // ignore classes for object and type arrays
1013 if (!klass->is_instance_klass()) {
1014 return 0;
1015 }
1016
1017 // ignore classes which aren't linked yet
1018 InstanceKlass* ik = InstanceKlass::cast(klass);
1019 if (!ik->is_linked()) {
1020 return 0;
1021 }
1022
1023 // get the field map
1024 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
1025
1026 // invoke the callback for each static primitive field
1027 for (int i=0; i<field_map->field_count(); i++) {
1028 ClassFieldDescriptor* field = field_map->field_at(i);
1029
1030 // ignore non-primitive fields
1031 char type = field->field_type();
1032 if (!is_primitive_field_type(type)) {
1033 continue;
1034 }
1035 // one-to-one mapping
1036 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1037
1038 // get offset and field value
1039 int offset = field->field_offset();
1040 address addr = cast_from_oop<address>(klass->java_mirror()) + offset;
1041 jvalue value;
1042 copy_to_jvalue(&value, addr, value_type);
1043
1044 // field index
1045 reference_info.field.index = field->field_index();
1046
1047 // invoke the callback
1048 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
1049 &reference_info,
1050 wrapper->klass_tag(),
1051 wrapper->obj_tag_p(),
1052 value,
1053 value_type,
1054 user_data);
1055 if (res & JVMTI_VISIT_ABORT) {
1056 delete field_map;
1057 return res;
1058 }
1059 }
1060
1061 delete field_map;
1062 return 0;
1063 }
1064
1065 // helper function to invoke the primitive field callback for all instance fields
1066 // of a given object
1067 static jint invoke_primitive_field_callback_for_instance_fields(
1068 CallbackWrapper* wrapper,
1069 const JvmtiHeapwalkObject& obj,
1070 jvmtiPrimitiveFieldCallback cb,
1071 void* user_data)
1072 {
1073 // for instance fields only the index will be set
1074 static jvmtiHeapReferenceInfo reference_info = { 0 };
1075
1076 // get the map of the instance fields
1077 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj.klass());
1078
1079 // invoke the callback for each instance primitive field
1080 for (int i=0; i<fields->field_count(); i++) {
1081 ClassFieldDescriptor* field = fields->field_at(i);
1082
1083 // ignore non-primitive fields
1084 char type = field->field_type();
1085 if (!is_primitive_field_type(type)) {
1086 continue;
1087 }
1088 // one-to-one mapping
1089 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1090
1091 // get field value
1092 address addr = cast_from_oop<address>(obj.obj()) + obj.offset() + field->field_offset();
1093 jvalue value;
1094 copy_to_jvalue(&value, addr, value_type);
1095
1096 // field index
1097 reference_info.field.index = field->field_index();
1098
1099 // invoke the callback
1100 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
1101 &reference_info,
1102 wrapper->klass_tag(),
1103 wrapper->obj_tag_p(),
1104 value,
1105 value_type,
1106 user_data);
1107 if (res & JVMTI_VISIT_ABORT) {
1108 return res;
1109 }
1110 }
1111 return 0;
1112 }
1113
1114
1115 // VM operation to iterate over all objects in the heap (both reachable
1116 // and unreachable)
1117 class VM_HeapIterateOperation: public VM_Operation {
1118 private:
1119 ObjectClosure* _blk;
1120 GrowableArray<jlong>* const _dead_objects;
1121 public:
1122 VM_HeapIterateOperation(ObjectClosure* blk, GrowableArray<jlong>* objects) :
1123 _blk(blk), _dead_objects(objects) { }
1124
1125 VMOp_Type type() const { return VMOp_HeapIterateOperation; }
1126 void doit() {
1127 // allows class files maps to be cached during iteration
1128 ClassFieldMapCacheMark cm;
1129
1130 JvmtiTagMap::check_hashmaps_for_heapwalk(_dead_objects);
1131
1132 // make sure that heap is parsable (fills TLABs with filler objects)
1133 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1134
1135 // Verify heap before iteration - if the heap gets corrupted then
1136 // JVMTI's IterateOverHeap will crash.
1137 if (VerifyBeforeIteration) {
1138 Universe::verify();
1139 }
1140
1141 // do the iteration
1142 Universe::heap()->object_iterate(_blk);
1143 }
1144 };
1145
1146
1147 // An ObjectClosure used to support the deprecated IterateOverHeap and
1148 // IterateOverInstancesOfClass functions
1149 class IterateOverHeapObjectClosure: public ObjectClosure {
1150 private:
1151 JvmtiTagMap* _tag_map;
1152 Klass* _klass;
1153 jvmtiHeapObjectFilter _object_filter;
1154 jvmtiHeapObjectCallback _heap_object_callback;
1155 const void* _user_data;
1156
1157 // accessors
1158 JvmtiTagMap* tag_map() const { return _tag_map; }
1159 jvmtiHeapObjectFilter object_filter() const { return _object_filter; }
1160 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
1161 Klass* klass() const { return _klass; }
1162 const void* user_data() const { return _user_data; }
1163
1164 // indicates if iteration has been aborted
1165 bool _iteration_aborted;
1166 bool is_iteration_aborted() const { return _iteration_aborted; }
1167 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; }
1168
1169 public:
1170 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
1171 Klass* klass,
1172 jvmtiHeapObjectFilter object_filter,
1173 jvmtiHeapObjectCallback heap_object_callback,
1174 const void* user_data) :
1175 _tag_map(tag_map),
1176 _klass(klass),
1177 _object_filter(object_filter),
1178 _heap_object_callback(heap_object_callback),
1179 _user_data(user_data),
1180 _iteration_aborted(false)
1181 {
1182 }
1183
1184 void do_object(oop o);
1185 };
1186
1187 // invoked for each object in the heap
1188 void IterateOverHeapObjectClosure::do_object(oop o) {
1189 assert(o != nullptr, "Heap iteration should never produce null!");
1190 // check if iteration has been halted
1191 if (is_iteration_aborted()) return;
1192
1193 // instanceof check when filtering by klass
1194 if (klass() != nullptr && !o->is_a(klass())) {
1195 return;
1196 }
1197
1198 // skip if object is a dormant shared object whose mirror hasn't been loaded
1199 if (o->klass()->java_mirror() == nullptr) {
1200 log_debug(aot, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s)", p2i(o),
1201 o->klass()->external_name());
1202 return;
1203 }
1204
1205 // prepare for the calllback
1206 JvmtiHeapwalkObject wrapper_obj(o);
1207 CallbackWrapper wrapper(tag_map(), wrapper_obj);
1208
1209 // if the object is tagged and we're only interested in untagged objects
1210 // then don't invoke the callback. Similarly, if the object is untagged
1211 // and we're only interested in tagged objects we skip the callback.
1212 if (wrapper.obj_tag() != 0) {
1213 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
1214 } else {
1215 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
1216 }
1217
1218 // invoke the agent's callback
1219 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
1220 wrapper.obj_size(),
1221 wrapper.obj_tag_p(),
1222 (void*)user_data());
1223 if (control == JVMTI_ITERATION_ABORT) {
1224 set_iteration_aborted(true);
1225 }
1226 }
1227
1228 // An ObjectClosure used to support the IterateThroughHeap function
1229 class IterateThroughHeapObjectClosure: public ObjectClosure {
1230 private:
1231 JvmtiTagMap* _tag_map;
1232 Klass* _klass;
1233 int _heap_filter;
1234 const jvmtiHeapCallbacks* _callbacks;
1235 const void* _user_data;
1236
1237 // accessor functions
1238 JvmtiTagMap* tag_map() const { return _tag_map; }
1239 int heap_filter() const { return _heap_filter; }
1240 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; }
1241 Klass* klass() const { return _klass; }
1242 const void* user_data() const { return _user_data; }
1243
1244 // indicates if the iteration has been aborted
1245 bool _iteration_aborted;
1246 bool is_iteration_aborted() const { return _iteration_aborted; }
1247
1248 // used to check the visit control flags. If the abort flag is set
1249 // then we set the iteration aborted flag so that the iteration completes
1250 // without processing any further objects
1251 bool check_flags_for_abort(jint flags) {
1252 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
1253 if (is_abort) {
1254 _iteration_aborted = true;
1255 }
1256 return is_abort;
1257 }
1258
1259 void visit_object(const JvmtiHeapwalkObject& obj);
1260 void visit_flat_fields(const JvmtiHeapwalkObject& obj);
1261 void visit_flat_array_elements(const JvmtiHeapwalkObject& obj);
1262
1263 public:
1264 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
1265 Klass* klass,
1266 int heap_filter,
1267 const jvmtiHeapCallbacks* heap_callbacks,
1268 const void* user_data) :
1269 _tag_map(tag_map),
1270 _klass(klass),
1271 _heap_filter(heap_filter),
1272 _callbacks(heap_callbacks),
1273 _user_data(user_data),
1274 _iteration_aborted(false)
1275 {
1276 }
1277
1278 void do_object(oop obj);
1279 };
1280
1281 // invoked for each object in the heap
1282 void IterateThroughHeapObjectClosure::do_object(oop obj) {
1283 assert(obj != nullptr, "Heap iteration should never produce null!");
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 if (LayoutKindHelper::is_nullable_flat(field->layout_kind())) {
1403 address payload = cast_from_oop<address>(obj.obj()) + field_offset;
1404 if (field->inline_klass()->is_payload_marked_as_null(payload)) {
1405 continue;
1406 }
1407 }
1408 JvmtiHeapwalkObject field_obj(obj.obj(), field_offset, field->inline_klass(), field->layout_kind());
1409
1410 visit_object(field_obj);
1411
1412 // check if iteration has been halted
1413 if (is_iteration_aborted()) {
1414 return;
1415 }
1416 }
1417 }
1418
1419 void IterateThroughHeapObjectClosure::visit_flat_array_elements(const JvmtiHeapwalkObject& obj) {
1420 assert(!obj.is_flat() && obj.obj()->is_flatArray() , "sanity check");
1421 flatArrayOop array = flatArrayOop(obj.obj());
1422 FlatArrayKlass* faklass = FlatArrayKlass::cast(array->klass());
1423 InlineKlass* vk = InlineKlass::cast(faklass->element_klass());
1424 bool need_null_check = LayoutKindHelper::is_nullable_flat(faklass->layout_kind());
1425
1426 for (int index = 0; index < array->length(); index++) {
1427 address addr = (address)array->value_at_addr(index, faklass->layout_helper());
1428 // check for null
1429 if (need_null_check) {
1430 if (vk->is_payload_marked_as_null(addr)) {
1431 continue;
1432 }
1433 }
1434
1435 // offset in the array oop
1436 int offset = (int)(addr - cast_from_oop<address>(array));
1437 JvmtiHeapwalkObject elem(obj.obj(), offset, vk, faklass->layout_kind());
1438
1439 visit_object(elem);
1440
1441 // check if iteration has been halted
1442 if (is_iteration_aborted()) {
1443 return;
1444 }
1445 }
1446 }
1447
1448 // Deprecated function to iterate over all objects in the heap
1449 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
1450 Klass* klass,
1451 jvmtiHeapObjectCallback heap_object_callback,
1452 const void* user_data)
1453 {
1454 // EA based optimizations on tagged objects are already reverted.
1455 EscapeBarrier eb(object_filter == JVMTI_HEAP_OBJECT_UNTAGGED ||
1456 object_filter == JVMTI_HEAP_OBJECT_EITHER,
1457 JavaThread::current());
1458 eb.deoptimize_objects_all_threads();
1459 Arena dead_object_arena(mtServiceability);
1460 GrowableArray <jlong> dead_objects(&dead_object_arena, 10, 0, 0);
1461 {
1462 MutexLocker ml(Heap_lock);
1463 IterateOverHeapObjectClosure blk(this,
1464 klass,
1465 object_filter,
1466 heap_object_callback,
1467 user_data);
1468 VM_HeapIterateOperation op(&blk, &dead_objects);
1469 VMThread::execute(&op);
1470 }
1471 convert_flat_object_entries();
1472
1473 // Post events outside of Heap_lock
1474 post_dead_objects(&dead_objects);
1475 }
1476
1477
1478 // Iterates over all objects in the heap
1479 void JvmtiTagMap::iterate_through_heap(jint heap_filter,
1480 Klass* klass,
1481 const jvmtiHeapCallbacks* callbacks,
1482 const void* user_data)
1483 {
1484 // EA based optimizations on tagged objects are already reverted.
1485 EscapeBarrier eb(!(heap_filter & JVMTI_HEAP_FILTER_UNTAGGED), JavaThread::current());
1486 eb.deoptimize_objects_all_threads();
1487
1488 Arena dead_object_arena(mtServiceability);
1489 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
1490 {
1491 MutexLocker ml(Heap_lock);
1492 IterateThroughHeapObjectClosure blk(this,
1493 klass,
1494 heap_filter,
1495 callbacks,
1496 user_data);
1497 VM_HeapIterateOperation op(&blk, &dead_objects);
1498 VMThread::execute(&op);
1499 }
1500 convert_flat_object_entries();
1501
1502 // Post events outside of Heap_lock
1503 post_dead_objects(&dead_objects);
1504 }
1505
1506 void JvmtiTagMap::remove_dead_entries_locked(GrowableArray<jlong>* objects) {
1507 assert(is_locked(), "precondition");
1508 if (_needs_cleaning) {
1509 // Recheck whether to post object free events under the lock.
1510 if (!env()->is_enabled(JVMTI_EVENT_OBJECT_FREE)) {
1511 objects = nullptr;
1512 }
1513 log_info(jvmti, table)("TagMap table needs cleaning%s",
1514 ((objects != nullptr) ? " and posting" : ""));
1515 _hashmap->remove_dead_entries(objects);
1516 _needs_cleaning = false;
1517 }
1518 }
1519
1520 void JvmtiTagMap::remove_dead_entries(GrowableArray<jlong>* objects) {
1521 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1522 remove_dead_entries_locked(objects);
1523 }
1524
1525 void JvmtiTagMap::post_dead_objects(GrowableArray<jlong>* const objects) {
1526 assert(Thread::current()->is_Java_thread(), "Must post from JavaThread");
1527 if (objects != nullptr && objects->length() > 0) {
1528 JvmtiExport::post_object_free(env(), objects);
1529 log_info(jvmti, table)("%d free object posted", objects->length());
1530 }
1531 }
1532
1533 void JvmtiTagMap::remove_and_post_dead_objects() {
1534 ResourceMark rm;
1535 GrowableArray<jlong> objects;
1536 remove_dead_entries(&objects);
1537 post_dead_objects(&objects);
1538 }
1539
1540 void JvmtiTagMap::flush_object_free_events() {
1541 assert_not_at_safepoint();
1542 if (env()->is_enabled(JVMTI_EVENT_OBJECT_FREE)) {
1543 {
1544 // The other thread can block for safepoints during event callbacks, so ensure we
1545 // are safepoint-safe while waiting.
1546 ThreadBlockInVM tbivm(JavaThread::current());
1547 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1548 while (_posting_events) {
1549 ml.wait();
1550 }
1551
1552 if (!_needs_cleaning || is_empty()) {
1553 _needs_cleaning = false;
1554 return;
1555 }
1556 _posting_events = true;
1557 } // Drop the lock so we can do the cleaning on the VM thread.
1558 // Needs both cleaning and event posting (up to some other thread
1559 // getting there first after we dropped the lock).
1560 remove_and_post_dead_objects();
1561 {
1562 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1563 _posting_events = false;
1564 ml.notify_all();
1565 }
1566 } else {
1567 remove_dead_entries(nullptr);
1568 }
1569 }
1570
1571 // support class for get_objects_with_tags
1572
1573 class TagObjectCollector : public JvmtiTagMapKeyClosure {
1574 private:
1575 JvmtiEnv* _env;
1576 JavaThread* _thread;
1577 jlong* _tags;
1578 jint _tag_count;
1579 bool _some_dead_found;
1580
1581 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs)
1582 GrowableArray<uint64_t>* _tag_results; // collected tags
1583
1584 public:
1585 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) :
1586 _env(env),
1587 _thread(JavaThread::current()),
1588 _tags((jlong*)tags),
1589 _tag_count(tag_count),
1590 _some_dead_found(false),
1591 _object_results(new (mtServiceability) GrowableArray<jobject>(1, mtServiceability)),
1592 _tag_results(new (mtServiceability) GrowableArray<uint64_t>(1, mtServiceability)) { }
1593
1594 ~TagObjectCollector() {
1595 delete _object_results;
1596 delete _tag_results;
1597 }
1598
1599 bool some_dead_found() const { return _some_dead_found; }
1600
1601 // for each tagged object check if the tag value matches
1602 // - if it matches then we create a JNI local reference to the object
1603 // and record the reference and tag value.
1604 // Always return true so the iteration continues.
1605 bool do_entry(JvmtiTagMapKey& key, jlong& value) {
1606 for (int i = 0; i < _tag_count; i++) {
1607 if (_tags[i] == value) {
1608 // The reference in this tag map could be the only (implicitly weak)
1609 // reference to that object. If we hand it out, we need to keep it live wrt
1610 // SATB marking similar to other j.l.ref.Reference referents. This is
1611 // achieved by using a phantom load in the object() accessor.
1612 oop o = key.object();
1613 if (o == nullptr) {
1614 _some_dead_found = true;
1615 // skip this whole entry
1616 return true;
1617 }
1618 assert(o != nullptr && Universe::heap()->is_in(o), "sanity check");
1619 jobject ref = JNIHandles::make_local(_thread, o);
1620 _object_results->append(ref);
1621 _tag_results->append(value);
1622 }
1623 }
1624 return true;
1625 }
1626
1627 // return the results from the collection
1628 //
1629 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1630 jvmtiError error;
1631 int count = _object_results->length();
1632 assert(count >= 0, "sanity check");
1633
1634 // if object_result_ptr is not null then allocate the result and copy
1635 // in the object references.
1636 if (object_result_ptr != nullptr) {
1637 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
1638 if (error != JVMTI_ERROR_NONE) {
1639 return error;
1640 }
1641 for (int i=0; i<count; i++) {
1642 (*object_result_ptr)[i] = _object_results->at(i);
1643 }
1644 }
1645
1646 // if tag_result_ptr is not null then allocate the result and copy
1647 // in the tag values.
1648 if (tag_result_ptr != nullptr) {
1649 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
1650 if (error != JVMTI_ERROR_NONE) {
1651 if (object_result_ptr != nullptr) {
1652 _env->Deallocate((unsigned char*)object_result_ptr);
1653 }
1654 return error;
1655 }
1656 for (int i=0; i<count; i++) {
1657 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
1658 }
1659 }
1660
1661 *count_ptr = count;
1662 return JVMTI_ERROR_NONE;
1663 }
1664 };
1665
1666 // return the list of objects with the specified tags
1667 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
1668 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1669
1670 // ensure flat object conversion is completed
1671 convert_flat_object_entries();
1672
1673 TagObjectCollector collector(env(), tags, count);
1674 {
1675 // iterate over all tagged objects
1676 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1677 // Can't post ObjectFree events here from a JavaThread, so this
1678 // will race with the gc_notification thread in the tiny
1679 // window where the object is not marked but hasn't been notified that
1680 // it is collected yet.
1681 _hashmap->entry_iterate(&collector);
1682 }
1683 return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
1684 }
1685
1686 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
1687 // (not performance critical as only used for roots)
1688 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
1689 switch (kind) {
1690 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL;
1691 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
1692 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL;
1693 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL;
1694 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD;
1695 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER;
1696 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER;
1697 }
1698 }
1699
1700 // Base class for all heap walk contexts. The base class maintains a flag
1701 // to indicate if the context is valid or not.
1702 class HeapWalkContext {
1703 private:
1704 bool _valid;
1705 public:
1706 HeapWalkContext(bool valid) { _valid = valid; }
1707 void invalidate() { _valid = false; }
1708 bool is_valid() const { return _valid; }
1709 };
1710
1711 // A basic heap walk context for the deprecated heap walking functions.
1712 // The context for a basic heap walk are the callbacks and fields used by
1713 // the referrer caching scheme.
1714 class BasicHeapWalkContext: public HeapWalkContext {
1715 private:
1716 jvmtiHeapRootCallback _heap_root_callback;
1717 jvmtiStackReferenceCallback _stack_ref_callback;
1718 jvmtiObjectReferenceCallback _object_ref_callback;
1719
1720 // used for caching
1721 JvmtiHeapwalkObject _last_referrer;
1722 jlong _last_referrer_tag;
1723
1724 public:
1725 BasicHeapWalkContext() : HeapWalkContext(false) { }
1726
1727 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
1728 jvmtiStackReferenceCallback stack_ref_callback,
1729 jvmtiObjectReferenceCallback object_ref_callback) :
1730 HeapWalkContext(true),
1731 _heap_root_callback(heap_root_callback),
1732 _stack_ref_callback(stack_ref_callback),
1733 _object_ref_callback(object_ref_callback),
1734 _last_referrer(),
1735 _last_referrer_tag(0) {
1736 }
1737
1738 // accessors
1739 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; }
1740 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; }
1741 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; }
1742
1743 JvmtiHeapwalkObject last_referrer() const { return _last_referrer; }
1744 void set_last_referrer(const JvmtiHeapwalkObject& referrer) { _last_referrer = referrer; }
1745 jlong last_referrer_tag() const { return _last_referrer_tag; }
1746 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
1747 };
1748
1749 // The advanced heap walk context for the FollowReferences functions.
1750 // The context is the callbacks, and the fields used for filtering.
1751 class AdvancedHeapWalkContext: public HeapWalkContext {
1752 private:
1753 jint _heap_filter;
1754 Klass* _klass_filter;
1755 const jvmtiHeapCallbacks* _heap_callbacks;
1756
1757 public:
1758 AdvancedHeapWalkContext() : HeapWalkContext(false) { }
1759
1760 AdvancedHeapWalkContext(jint heap_filter,
1761 Klass* klass_filter,
1762 const jvmtiHeapCallbacks* heap_callbacks) :
1763 HeapWalkContext(true),
1764 _heap_filter(heap_filter),
1765 _klass_filter(klass_filter),
1766 _heap_callbacks(heap_callbacks) {
1767 }
1768
1769 // accessors
1770 jint heap_filter() const { return _heap_filter; }
1771 Klass* klass_filter() const { return _klass_filter; }
1772
1773 jvmtiHeapReferenceCallback heap_reference_callback() const {
1774 return _heap_callbacks->heap_reference_callback;
1775 };
1776 jvmtiPrimitiveFieldCallback primitive_field_callback() const {
1777 return _heap_callbacks->primitive_field_callback;
1778 }
1779 jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
1780 return _heap_callbacks->array_primitive_value_callback;
1781 }
1782 jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
1783 return _heap_callbacks->string_primitive_value_callback;
1784 }
1785 };
1786
1787 // The CallbackInvoker is a class with static functions that the heap walk can call
1788 // into to invoke callbacks. It works in one of two modes. The "basic" mode is
1789 // used for the deprecated IterateOverReachableObjects functions. The "advanced"
1790 // mode is for the newer FollowReferences function which supports a lot of
1791 // additional callbacks.
1792 class CallbackInvoker : AllStatic {
1793 private:
1794 // heap walk styles
1795 enum { basic, advanced };
1796 static int _heap_walk_type;
1797 static bool is_basic_heap_walk() { return _heap_walk_type == basic; }
1798 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; }
1799
1800 // context for basic style heap walk
1801 static BasicHeapWalkContext _basic_context;
1802 static BasicHeapWalkContext* basic_context() {
1803 assert(_basic_context.is_valid(), "invalid");
1804 return &_basic_context;
1805 }
1806
1807 // context for advanced style heap walk
1808 static AdvancedHeapWalkContext _advanced_context;
1809 static AdvancedHeapWalkContext* advanced_context() {
1810 assert(_advanced_context.is_valid(), "invalid");
1811 return &_advanced_context;
1812 }
1813
1814 // context needed for all heap walks
1815 static JvmtiTagMap* _tag_map;
1816 static const void* _user_data;
1817 static JvmtiHeapwalkVisitStack* _visit_stack;
1818
1819 // accessors
1820 static JvmtiTagMap* tag_map() { return _tag_map; }
1821 static const void* user_data() { return _user_data; }
1822 static JvmtiHeapwalkVisitStack* visit_stack() { return _visit_stack; }
1823
1824 // if the object hasn't been visited then push it onto the visit stack
1825 // so that it will be visited later
1826 static inline bool check_for_visit(const JvmtiHeapwalkObject&obj) {
1827 visit_stack()->check_for_visit(obj);
1828 return true;
1829 }
1830
1831 // return element count if the obj is array, -1 otherwise
1832 static jint get_array_length(const JvmtiHeapwalkObject& obj) {
1833 if (!obj.klass()->is_array_klass()) {
1834 return -1;
1835 }
1836 assert(!obj.is_flat(), "array cannot be flat");
1837 return (jint)arrayOop(obj.obj())->length();
1838 }
1839
1840
1841 // invoke basic style callbacks
1842 static inline bool invoke_basic_heap_root_callback
1843 (jvmtiHeapRootKind root_kind, const JvmtiHeapwalkObject& obj);
1844 static inline bool invoke_basic_stack_ref_callback
1845 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
1846 int slot, const JvmtiHeapwalkObject& obj);
1847 static inline bool invoke_basic_object_reference_callback
1848 (jvmtiObjectReferenceKind ref_kind, const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1849
1850 // invoke advanced style callbacks
1851 static inline bool invoke_advanced_heap_root_callback
1852 (jvmtiHeapReferenceKind ref_kind, const JvmtiHeapwalkObject& obj);
1853 static inline bool invoke_advanced_stack_ref_callback
1854 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
1855 jmethodID method, jlocation bci, jint slot, const JvmtiHeapwalkObject& obj);
1856 static inline bool invoke_advanced_object_reference_callback
1857 (jvmtiHeapReferenceKind ref_kind, const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1858
1859 // used to report the value of primitive fields
1860 static inline bool report_primitive_field
1861 (jvmtiHeapReferenceKind ref_kind, const JvmtiHeapwalkObject& obj, jint index, address addr, char type);
1862
1863 public:
1864 // initialize for basic mode
1865 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1866 const void* user_data,
1867 BasicHeapWalkContext context,
1868 JvmtiHeapwalkVisitStack* visit_stack);
1869
1870 // initialize for advanced mode
1871 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1872 const void* user_data,
1873 AdvancedHeapWalkContext context,
1874 JvmtiHeapwalkVisitStack* visit_stack);
1875
1876 // functions to report roots
1877 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, const JvmtiHeapwalkObject& o);
1878 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
1879 jmethodID m, const JvmtiHeapwalkObject& o);
1880 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
1881 jmethodID method, jlocation bci, jint slot, const JvmtiHeapwalkObject& o);
1882
1883 // functions to report references
1884 static inline bool report_array_element_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1885 static inline bool report_class_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1886 static inline bool report_class_loader_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1887 static inline bool report_signers_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1888 static inline bool report_protection_domain_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1889 static inline bool report_superclass_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1890 static inline bool report_interface_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1891 static inline bool report_static_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot);
1892 static inline bool report_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot);
1893 static inline bool report_constant_pool_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1894 static inline bool report_primitive_array_values(const JvmtiHeapwalkObject& array);
1895 static inline bool report_string_value(const JvmtiHeapwalkObject& str);
1896 static inline bool report_primitive_instance_field(const JvmtiHeapwalkObject& o, jint index, address value, char type);
1897 static inline bool report_primitive_static_field(const JvmtiHeapwalkObject& o, jint index, address value, char type);
1898 };
1899
1900 // statics
1901 int CallbackInvoker::_heap_walk_type;
1902 BasicHeapWalkContext CallbackInvoker::_basic_context;
1903 AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
1904 JvmtiTagMap* CallbackInvoker::_tag_map;
1905 const void* CallbackInvoker::_user_data;
1906 JvmtiHeapwalkVisitStack* CallbackInvoker::_visit_stack;
1907
1908 // initialize for basic heap walk (IterateOverReachableObjects et al)
1909 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1910 const void* user_data,
1911 BasicHeapWalkContext context,
1912 JvmtiHeapwalkVisitStack* visit_stack) {
1913 _tag_map = tag_map;
1914 _user_data = user_data;
1915 _basic_context = context;
1916 _advanced_context.invalidate(); // will trigger assertion if used
1917 _heap_walk_type = basic;
1918 _visit_stack = visit_stack;
1919 }
1920
1921 // initialize for advanced heap walk (FollowReferences)
1922 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1923 const void* user_data,
1924 AdvancedHeapWalkContext context,
1925 JvmtiHeapwalkVisitStack* visit_stack) {
1926 _tag_map = tag_map;
1927 _user_data = user_data;
1928 _advanced_context = context;
1929 _basic_context.invalidate(); // will trigger assertion if used
1930 _heap_walk_type = advanced;
1931 _visit_stack = visit_stack;
1932 }
1933
1934
1935 // invoke basic style heap root callback
1936 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, const JvmtiHeapwalkObject& obj) {
1937 // if we heap roots should be reported
1938 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
1939 if (cb == nullptr) {
1940 return check_for_visit(obj);
1941 }
1942
1943 CallbackWrapper wrapper(tag_map(), obj);
1944 jvmtiIterationControl control = (*cb)(root_kind,
1945 wrapper.klass_tag(),
1946 wrapper.obj_size(),
1947 wrapper.obj_tag_p(),
1948 (void*)user_data());
1949 // push root to visit stack when following references
1950 if (control == JVMTI_ITERATION_CONTINUE &&
1951 basic_context()->object_ref_callback() != nullptr) {
1952 visit_stack()->push(obj);
1953 }
1954 return control != JVMTI_ITERATION_ABORT;
1955 }
1956
1957 // invoke basic style stack ref callback
1958 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
1959 jlong thread_tag,
1960 jint depth,
1961 jmethodID method,
1962 int slot,
1963 const JvmtiHeapwalkObject& obj) {
1964 // if we stack refs should be reported
1965 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
1966 if (cb == nullptr) {
1967 return check_for_visit(obj);
1968 }
1969
1970 CallbackWrapper wrapper(tag_map(), obj);
1971 jvmtiIterationControl control = (*cb)(root_kind,
1972 wrapper.klass_tag(),
1973 wrapper.obj_size(),
1974 wrapper.obj_tag_p(),
1975 thread_tag,
1976 depth,
1977 method,
1978 slot,
1979 (void*)user_data());
1980 // push root to visit stack when following references
1981 if (control == JVMTI_ITERATION_CONTINUE &&
1982 basic_context()->object_ref_callback() != nullptr) {
1983 visit_stack()->push(obj);
1984 }
1985 return control != JVMTI_ITERATION_ABORT;
1986 }
1987
1988 // invoke basic style object reference callback
1989 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
1990 const JvmtiHeapwalkObject& referrer,
1991 const JvmtiHeapwalkObject& referree,
1992 jint index) {
1993
1994 BasicHeapWalkContext* context = basic_context();
1995
1996 // callback requires the referrer's tag. If it's the same referrer
1997 // as the last call then we use the cached value.
1998 jlong referrer_tag;
1999 if (referrer == context->last_referrer()) {
2000 referrer_tag = context->last_referrer_tag();
2001 } else {
2002 referrer_tag = tag_map()->find(referrer);
2003 }
2004
2005 // do the callback
2006 CallbackWrapper wrapper(tag_map(), referree);
2007 jvmtiObjectReferenceCallback cb = context->object_ref_callback();
2008 jvmtiIterationControl control = (*cb)(ref_kind,
2009 wrapper.klass_tag(),
2010 wrapper.obj_size(),
2011 wrapper.obj_tag_p(),
2012 referrer_tag,
2013 index,
2014 (void*)user_data());
2015
2016 // record referrer and referrer tag. For self-references record the
2017 // tag value from the callback as this might differ from referrer_tag.
2018 context->set_last_referrer(referrer);
2019 if (referrer == referree) {
2020 context->set_last_referrer_tag(*wrapper.obj_tag_p());
2021 } else {
2022 context->set_last_referrer_tag(referrer_tag);
2023 }
2024
2025 if (control == JVMTI_ITERATION_CONTINUE) {
2026 return check_for_visit(referree);
2027 } else {
2028 return control != JVMTI_ITERATION_ABORT;
2029 }
2030 }
2031
2032 // invoke advanced style heap root callback
2033 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
2034 const JvmtiHeapwalkObject& obj) {
2035 AdvancedHeapWalkContext* context = advanced_context();
2036
2037 // check that callback is provided
2038 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2039 if (cb == nullptr) {
2040 return check_for_visit(obj);
2041 }
2042
2043 // apply class filter
2044 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2045 return check_for_visit(obj);
2046 }
2047
2048 // setup the callback wrapper
2049 CallbackWrapper wrapper(tag_map(), obj);
2050
2051 // apply tag filter
2052 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2053 wrapper.klass_tag(),
2054 context->heap_filter())) {
2055 return check_for_visit(obj);
2056 }
2057
2058 // for arrays we need the length, otherwise -1
2059 jint len = get_array_length(obj);
2060
2061 // invoke the callback
2062 jint res = (*cb)(ref_kind,
2063 nullptr, // referrer info
2064 wrapper.klass_tag(),
2065 0, // referrer_class_tag is 0 for heap root
2066 wrapper.obj_size(),
2067 wrapper.obj_tag_p(),
2068 nullptr, // referrer_tag_p
2069 len,
2070 (void*)user_data());
2071 if (res & JVMTI_VISIT_ABORT) {
2072 return false;// referrer class tag
2073 }
2074 if (res & JVMTI_VISIT_OBJECTS) {
2075 check_for_visit(obj);
2076 }
2077 return true;
2078 }
2079
2080 // report a reference from a thread stack to an object
2081 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
2082 jlong thread_tag,
2083 jlong tid,
2084 int depth,
2085 jmethodID method,
2086 jlocation bci,
2087 jint slot,
2088 const JvmtiHeapwalkObject& obj) {
2089 AdvancedHeapWalkContext* context = advanced_context();
2090
2091 // check that callback is provider
2092 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2093 if (cb == nullptr) {
2094 return check_for_visit(obj);
2095 }
2096
2097 // apply class filter
2098 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2099 return check_for_visit(obj);
2100 }
2101
2102 // setup the callback wrapper
2103 CallbackWrapper wrapper(tag_map(), obj);
2104
2105 // apply tag filter
2106 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2107 wrapper.klass_tag(),
2108 context->heap_filter())) {
2109 return check_for_visit(obj);
2110 }
2111
2112 // setup the referrer info
2113 jvmtiHeapReferenceInfo reference_info;
2114 reference_info.stack_local.thread_tag = thread_tag;
2115 reference_info.stack_local.thread_id = tid;
2116 reference_info.stack_local.depth = depth;
2117 reference_info.stack_local.method = method;
2118 reference_info.stack_local.location = bci;
2119 reference_info.stack_local.slot = slot;
2120
2121 // for arrays we need the length, otherwise -1
2122 jint len = get_array_length(obj);
2123
2124 // call into the agent
2125 int res = (*cb)(ref_kind,
2126 &reference_info,
2127 wrapper.klass_tag(),
2128 0, // referrer_class_tag is 0 for heap root (stack)
2129 wrapper.obj_size(),
2130 wrapper.obj_tag_p(),
2131 nullptr, // referrer_tag is 0 for root
2132 len,
2133 (void*)user_data());
2134
2135 if (res & JVMTI_VISIT_ABORT) {
2136 return false;
2137 }
2138 if (res & JVMTI_VISIT_OBJECTS) {
2139 check_for_visit(obj);
2140 }
2141 return true;
2142 }
2143
2144 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
2145 // only for ref_kinds defined by the JVM TI spec. Otherwise, null is passed.
2146 #define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \
2147 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \
2148 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
2149 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
2150 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \
2151 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
2152
2153 // invoke the object reference callback to report a reference
2154 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
2155 const JvmtiHeapwalkObject& referrer,
2156 const JvmtiHeapwalkObject& obj,
2157 jint index)
2158 {
2159 // field index is only valid field in reference_info
2160 static jvmtiHeapReferenceInfo reference_info = { 0 };
2161
2162 AdvancedHeapWalkContext* context = advanced_context();
2163
2164 // check that callback is provider
2165 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2166 if (cb == nullptr) {
2167 return check_for_visit(obj);
2168 }
2169
2170 // apply class filter
2171 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2172 return check_for_visit(obj);
2173 }
2174
2175 // setup the callback wrapper
2176 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
2177
2178 // apply tag filter
2179 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2180 wrapper.klass_tag(),
2181 context->heap_filter())) {
2182 return check_for_visit(obj);
2183 }
2184
2185 // field index is only valid field in reference_info
2186 reference_info.field.index = index;
2187
2188 // for arrays we need the length, otherwise -1
2189 jint len = get_array_length(obj);
2190
2191 // invoke the callback
2192 int res = (*cb)(ref_kind,
2193 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : nullptr,
2194 wrapper.klass_tag(),
2195 wrapper.referrer_klass_tag(),
2196 wrapper.obj_size(),
2197 wrapper.obj_tag_p(),
2198 wrapper.referrer_tag_p(),
2199 len,
2200 (void*)user_data());
2201
2202 if (res & JVMTI_VISIT_ABORT) {
2203 return false;
2204 }
2205 if (res & JVMTI_VISIT_OBJECTS) {
2206 check_for_visit(obj);
2207 }
2208 return true;
2209 }
2210
2211 // report a "simple root"
2212 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, const JvmtiHeapwalkObject& obj) {
2213 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
2214 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
2215
2216 if (is_basic_heap_walk()) {
2217 // map to old style root kind
2218 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
2219 return invoke_basic_heap_root_callback(root_kind, obj);
2220 } else {
2221 assert(is_advanced_heap_walk(), "wrong heap walk type");
2222 return invoke_advanced_heap_root_callback(kind, obj);
2223 }
2224 }
2225
2226
2227 // invoke the primitive array values
2228 inline bool CallbackInvoker::report_primitive_array_values(const JvmtiHeapwalkObject& obj) {
2229 assert(obj.klass()->is_typeArray_klass(), "not a primitive array");
2230
2231 AdvancedHeapWalkContext* context = advanced_context();
2232 assert(context->array_primitive_value_callback() != nullptr, "no callback");
2233
2234 // apply class filter
2235 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2236 return true;
2237 }
2238
2239 CallbackWrapper wrapper(tag_map(), obj);
2240
2241 // apply tag filter
2242 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2243 wrapper.klass_tag(),
2244 context->heap_filter())) {
2245 return true;
2246 }
2247
2248 // invoke the callback
2249 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
2250 &wrapper,
2251 obj,
2252 (void*)user_data());
2253 return (!(res & JVMTI_VISIT_ABORT));
2254 }
2255
2256 // invoke the string value callback
2257 inline bool CallbackInvoker::report_string_value(const JvmtiHeapwalkObject& str) {
2258 assert(str.klass() == vmClasses::String_klass(), "not a string");
2259
2260 AdvancedHeapWalkContext* context = advanced_context();
2261 assert(context->string_primitive_value_callback() != nullptr, "no callback");
2262
2263 // apply class filter
2264 if (is_filtered_by_klass_filter(str, context->klass_filter())) {
2265 return true;
2266 }
2267
2268 CallbackWrapper wrapper(tag_map(), str);
2269
2270 // apply tag filter
2271 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2272 wrapper.klass_tag(),
2273 context->heap_filter())) {
2274 return true;
2275 }
2276
2277 // invoke the callback
2278 int res = invoke_string_value_callback(context->string_primitive_value_callback(),
2279 &wrapper,
2280 str,
2281 (void*)user_data());
2282 return (!(res & JVMTI_VISIT_ABORT));
2283 }
2284
2285 // invoke the primitive field callback
2286 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
2287 const JvmtiHeapwalkObject& obj,
2288 jint index,
2289 address addr,
2290 char type)
2291 {
2292 // for primitive fields only the index will be set
2293 static jvmtiHeapReferenceInfo reference_info = { 0 };
2294
2295 AdvancedHeapWalkContext* context = advanced_context();
2296 assert(context->primitive_field_callback() != nullptr, "no callback");
2297
2298 // apply class filter
2299 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2300 return true;
2301 }
2302
2303 CallbackWrapper wrapper(tag_map(), obj);
2304
2305 // apply tag filter
2306 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2307 wrapper.klass_tag(),
2308 context->heap_filter())) {
2309 return true;
2310 }
2311
2312 // the field index in the referrer
2313 reference_info.field.index = index;
2314
2315 // map the type
2316 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
2317
2318 // setup the jvalue
2319 jvalue value;
2320 copy_to_jvalue(&value, addr, value_type);
2321
2322 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
2323 int res = (*cb)(ref_kind,
2324 &reference_info,
2325 wrapper.klass_tag(),
2326 wrapper.obj_tag_p(),
2327 value,
2328 value_type,
2329 (void*)user_data());
2330 return (!(res & JVMTI_VISIT_ABORT));
2331 }
2332
2333
2334 // instance field
2335 inline bool CallbackInvoker::report_primitive_instance_field(const JvmtiHeapwalkObject& obj,
2336 jint index,
2337 address value,
2338 char type) {
2339 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
2340 obj,
2341 index,
2342 value,
2343 type);
2344 }
2345
2346 // static field
2347 inline bool CallbackInvoker::report_primitive_static_field(const JvmtiHeapwalkObject& obj,
2348 jint index,
2349 address value,
2350 char type) {
2351 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
2352 obj,
2353 index,
2354 value,
2355 type);
2356 }
2357
2358 // report a JNI local (root object) to the profiler
2359 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, const JvmtiHeapwalkObject& obj) {
2360 if (is_basic_heap_walk()) {
2361 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
2362 thread_tag,
2363 depth,
2364 m,
2365 -1,
2366 obj);
2367 } else {
2368 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
2369 thread_tag, tid,
2370 depth,
2371 m,
2372 (jlocation)-1,
2373 -1,
2374 obj);
2375 }
2376 }
2377
2378
2379 // report a local (stack reference, root object)
2380 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
2381 jlong tid,
2382 jint depth,
2383 jmethodID method,
2384 jlocation bci,
2385 jint slot,
2386 const JvmtiHeapwalkObject& obj) {
2387 if (is_basic_heap_walk()) {
2388 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
2389 thread_tag,
2390 depth,
2391 method,
2392 slot,
2393 obj);
2394 } else {
2395 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
2396 thread_tag,
2397 tid,
2398 depth,
2399 method,
2400 bci,
2401 slot,
2402 obj);
2403 }
2404 }
2405
2406 // report an object referencing a class.
2407 inline bool CallbackInvoker::report_class_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2408 if (is_basic_heap_walk()) {
2409 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2410 } else {
2411 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
2412 }
2413 }
2414
2415 // report a class referencing its class loader.
2416 inline bool CallbackInvoker::report_class_loader_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2417 if (is_basic_heap_walk()) {
2418 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2419 } else {
2420 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2421 }
2422 }
2423
2424 // report a class referencing its signers.
2425 inline bool CallbackInvoker::report_signers_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2426 if (is_basic_heap_walk()) {
2427 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
2428 } else {
2429 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
2430 }
2431 }
2432
2433 // report a class referencing its protection domain..
2434 inline bool CallbackInvoker::report_protection_domain_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2435 if (is_basic_heap_walk()) {
2436 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2437 } else {
2438 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2439 }
2440 }
2441
2442 // report a class referencing its superclass.
2443 inline bool CallbackInvoker::report_superclass_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2444 if (is_basic_heap_walk()) {
2445 // Send this to be consistent with past implementation
2446 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2447 } else {
2448 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
2449 }
2450 }
2451
2452 // report a class referencing one of its interfaces.
2453 inline bool CallbackInvoker::report_interface_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2454 if (is_basic_heap_walk()) {
2455 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
2456 } else {
2457 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
2458 }
2459 }
2460
2461 // report a class referencing one of its static fields.
2462 inline bool CallbackInvoker::report_static_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot) {
2463 if (is_basic_heap_walk()) {
2464 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2465 } else {
2466 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2467 }
2468 }
2469
2470 // report an array referencing an element object
2471 inline bool CallbackInvoker::report_array_element_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index) {
2472 if (is_basic_heap_walk()) {
2473 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2474 } else {
2475 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2476 }
2477 }
2478
2479 // report an object referencing an instance field object
2480 inline bool CallbackInvoker::report_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot) {
2481 if (is_basic_heap_walk()) {
2482 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
2483 } else {
2484 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
2485 }
2486 }
2487
2488 // report an array referencing an element object
2489 inline bool CallbackInvoker::report_constant_pool_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index) {
2490 if (is_basic_heap_walk()) {
2491 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2492 } else {
2493 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2494 }
2495 }
2496
2497 // A supporting closure used to process simple roots
2498 class SimpleRootsClosure : public OopClosure {
2499 private:
2500 jvmtiHeapReferenceKind _kind;
2501 bool _continue;
2502
2503 jvmtiHeapReferenceKind root_kind() { return _kind; }
2504
2505 public:
2506 void set_kind(jvmtiHeapReferenceKind kind) {
2507 _kind = kind;
2508 _continue = true;
2509 }
2510
2511 inline bool stopped() {
2512 return !_continue;
2513 }
2514
2515 void do_oop(oop* obj_p) {
2516 // iteration has terminated
2517 if (stopped()) {
2518 return;
2519 }
2520
2521 oop o = NativeAccess<AS_NO_KEEPALIVE>::oop_load(obj_p);
2522 // ignore null
2523 if (o == nullptr) {
2524 return;
2525 }
2526
2527 assert(Universe::heap()->is_in(o), "should be impossible");
2528
2529 jvmtiHeapReferenceKind kind = root_kind();
2530
2531 // invoke the callback
2532 _continue = CallbackInvoker::report_simple_root(kind, o);
2533
2534 }
2535 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2536 };
2537
2538 // A supporting closure used to process ClassLoaderData roots.
2539 class CLDRootsClosure: public OopClosure {
2540 private:
2541 bool _continue;
2542 public:
2543 CLDRootsClosure(): _continue(true) {}
2544
2545 inline bool stopped() {
2546 return !_continue;
2547 }
2548
2549 void do_oop(oop* obj_p) {
2550 if (stopped()) {
2551 return;
2552 }
2553
2554 oop o = NativeAccess<AS_NO_KEEPALIVE>::oop_load(obj_p);
2555 // ignore null
2556 if (o == nullptr) {
2557 return;
2558 }
2559
2560 jvmtiHeapReferenceKind kind = JVMTI_HEAP_REFERENCE_OTHER;
2561 if (o->klass() == vmClasses::Class_klass()) {
2562 kind = JVMTI_HEAP_REFERENCE_SYSTEM_CLASS;
2563 }
2564
2565 // invoke the callback
2566 _continue = CallbackInvoker::report_simple_root(kind, o);
2567 }
2568 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2569 };
2570
2571 // A supporting closure used to process JNI locals
2572 class JNILocalRootsClosure : public OopClosure {
2573 private:
2574 jlong _thread_tag;
2575 jlong _tid;
2576 jint _depth;
2577 jmethodID _method;
2578 bool _continue;
2579 public:
2580 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
2581 _thread_tag = thread_tag;
2582 _tid = tid;
2583 _depth = depth;
2584 _method = method;
2585 _continue = true;
2586 }
2587
2588 inline bool stopped() {
2589 return !_continue;
2590 }
2591
2592 void do_oop(oop* obj_p) {
2593 // iteration has terminated
2594 if (stopped()) {
2595 return;
2596 }
2597
2598 oop o = *obj_p;
2599 // ignore null
2600 if (o == nullptr) {
2601 return;
2602 }
2603
2604 // invoke the callback
2605 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
2606 }
2607 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2608 };
2609
2610 // Helper class to collect/report stack references.
2611 class StackRefCollector {
2612 private:
2613 JvmtiTagMap* _tag_map;
2614 JNILocalRootsClosure* _blk;
2615 // java_thread is needed only to report JNI local on top native frame;
2616 // I.e. it's required only for platform/carrier threads or mounted virtual threads.
2617 JavaThread* _java_thread;
2618
2619 oop _threadObj;
2620 jlong _thread_tag;
2621 jlong _tid;
2622
2623 bool _is_top_frame;
2624 int _depth;
2625 frame* _last_entry_frame;
2626
2627 bool report_java_stack_refs(StackValueCollection* values, jmethodID method, jlocation bci, jint slot_offset);
2628 bool report_native_stack_refs(jmethodID method);
2629
2630 public:
2631 StackRefCollector(JvmtiTagMap* tag_map, JNILocalRootsClosure* blk, JavaThread* java_thread)
2632 : _tag_map(tag_map), _blk(blk), _java_thread(java_thread),
2633 _threadObj(nullptr), _thread_tag(0), _tid(0),
2634 _is_top_frame(true), _depth(0), _last_entry_frame(nullptr)
2635 {
2636 }
2637
2638 bool set_thread(oop o);
2639 // Sets the thread and reports the reference to it with the specified kind.
2640 bool set_thread(jvmtiHeapReferenceKind kind, oop o);
2641
2642 bool do_frame(vframe* vf);
2643 // Handles frames until vf->sender() is null.
2644 bool process_frames(vframe* vf);
2645 };
2646
2647 bool StackRefCollector::set_thread(oop o) {
2648 _threadObj = o;
2649 _thread_tag = _tag_map->find(_threadObj);
2650 _tid = java_lang_Thread::thread_id(_threadObj);
2651
2652 _is_top_frame = true;
2653 _depth = 0;
2654 _last_entry_frame = nullptr;
2655
2656 return true;
2657 }
2658
2659 bool StackRefCollector::set_thread(jvmtiHeapReferenceKind kind, oop o) {
2660 return set_thread(o)
2661 && CallbackInvoker::report_simple_root(kind, _threadObj);
2662 }
2663
2664 bool StackRefCollector::report_java_stack_refs(StackValueCollection* values, jmethodID method, jlocation bci, jint slot_offset) {
2665 for (int index = 0; index < values->size(); index++) {
2666 if (values->at(index)->type() == T_OBJECT) {
2667 oop obj = values->obj_at(index)();
2668 if (obj == nullptr) {
2669 continue;
2670 }
2671 // stack reference
2672 if (!CallbackInvoker::report_stack_ref_root(_thread_tag, _tid, _depth, method,
2673 bci, slot_offset + index, obj)) {
2674 return false;
2675 }
2676 }
2677 }
2678 return true;
2679 }
2680
2681 bool StackRefCollector::report_native_stack_refs(jmethodID method) {
2682 _blk->set_context(_thread_tag, _tid, _depth, method);
2683 if (_is_top_frame) {
2684 // JNI locals for the top frame.
2685 if (_java_thread != nullptr) {
2686 _java_thread->active_handles()->oops_do(_blk);
2687 if (_blk->stopped()) {
2688 return false;
2689 }
2690 }
2691 } else {
2692 if (_last_entry_frame != nullptr) {
2693 // JNI locals for the entry frame.
2694 assert(_last_entry_frame->is_entry_frame(), "checking");
2695 _last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(_blk);
2696 if (_blk->stopped()) {
2697 return false;
2698 }
2699 }
2700 }
2701 return true;
2702 }
2703
2704 bool StackRefCollector::do_frame(vframe* vf) {
2705 if (vf->is_java_frame()) {
2706 // java frame (interpreted, compiled, ...)
2707 javaVFrame* jvf = javaVFrame::cast(vf);
2708
2709 jmethodID method = jvf->method()->jmethod_id();
2710
2711 if (!(jvf->method()->is_native())) {
2712 jlocation bci = (jlocation)jvf->bci();
2713 StackValueCollection* locals = jvf->locals();
2714 if (!report_java_stack_refs(locals, method, bci, 0)) {
2715 return false;
2716 }
2717 if (!report_java_stack_refs(jvf->expressions(), method, bci, locals->size())) {
2718 return false;
2719 }
2720
2721 // Follow oops from compiled nmethod.
2722 if (jvf->cb() != nullptr && jvf->cb()->is_nmethod()) {
2723 _blk->set_context(_thread_tag, _tid, _depth, method);
2724 // Need to apply load barriers for unmounted vthreads.
2725 nmethod* nm = jvf->cb()->as_nmethod();
2726 nm->run_nmethod_entry_barrier();
2727 nm->oops_do(_blk);
2728 if (_blk->stopped()) {
2729 return false;
2730 }
2731 }
2732 } else {
2733 // native frame
2734 if (!report_native_stack_refs(method)) {
2735 return false;
2736 }
2737 }
2738 _last_entry_frame = nullptr;
2739 _depth++;
2740 } else {
2741 // externalVFrame - for an entry frame then we report the JNI locals
2742 // when we find the corresponding javaVFrame
2743 frame* fr = vf->frame_pointer();
2744 assert(fr != nullptr, "sanity check");
2745 if (fr->is_entry_frame()) {
2746 _last_entry_frame = fr;
2747 }
2748 }
2749
2750 _is_top_frame = false;
2751
2752 return true;
2753 }
2754
2755 bool StackRefCollector::process_frames(vframe* vf) {
2756 while (vf != nullptr) {
2757 if (!do_frame(vf)) {
2758 return false;
2759 }
2760 vf = vf->sender();
2761 }
2762 return true;
2763 }
2764
2765
2766 // A VM operation to iterate over objects that are reachable from
2767 // a set of roots or an initial object.
2768 //
2769 // For VM_HeapWalkOperation the set of roots used is :-
2770 //
2771 // - All JNI global references
2772 // - All inflated monitors
2773 // - All classes loaded by the boot class loader (or all classes
2774 // in the event that class unloading is disabled)
2775 // - All java threads
2776 // - For each java thread then all locals and JNI local references
2777 // on the thread's execution stack
2778 // - All visible/explainable objects from Universes::oops_do
2779 //
2780 class VM_HeapWalkOperation: public VM_Operation {
2781 private:
2782 bool _is_advanced_heap_walk; // indicates FollowReferences
2783 JvmtiTagMap* _tag_map;
2784 Handle _initial_object;
2785 JvmtiHeapwalkVisitStack _visit_stack;
2786
2787 // Dead object tags in JvmtiTagMap
2788 GrowableArray<jlong>* _dead_objects;
2789
2790 bool _following_object_refs; // are we following object references
2791
2792 bool _reporting_primitive_fields; // optional reporting
2793 bool _reporting_primitive_array_values;
2794 bool _reporting_string_values;
2795
2796 // accessors
2797 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; }
2798 JvmtiTagMap* tag_map() const { return _tag_map; }
2799 Handle initial_object() const { return _initial_object; }
2800
2801 bool is_following_references() const { return _following_object_refs; }
2802
2803 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; }
2804 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
2805 bool is_reporting_string_values() const { return _reporting_string_values; }
2806
2807 JvmtiHeapwalkVisitStack* visit_stack() { return &_visit_stack; }
2808
2809 // iterate over the various object types
2810 inline bool iterate_over_array(const JvmtiHeapwalkObject& o);
2811 inline bool iterate_over_flat_array(const JvmtiHeapwalkObject& o);
2812 inline bool iterate_over_type_array(const JvmtiHeapwalkObject& o);
2813 inline bool iterate_over_class(const JvmtiHeapwalkObject& o);
2814 inline bool iterate_over_object(const JvmtiHeapwalkObject& o);
2815
2816 // root collection
2817 inline bool collect_simple_roots();
2818 inline bool collect_stack_roots();
2819 inline bool collect_stack_refs(JavaThread* java_thread, JNILocalRootsClosure* blk);
2820 inline bool collect_vthread_stack_refs(oop vt);
2821
2822 // visit an object
2823 inline bool visit(const JvmtiHeapwalkObject& o);
2824
2825 public:
2826 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2827 Handle initial_object,
2828 BasicHeapWalkContext callbacks,
2829 const void* user_data,
2830 GrowableArray<jlong>* objects);
2831
2832 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2833 Handle initial_object,
2834 AdvancedHeapWalkContext callbacks,
2835 const void* user_data,
2836 GrowableArray<jlong>* objects);
2837
2838 ~VM_HeapWalkOperation();
2839
2840 VMOp_Type type() const { return VMOp_HeapWalkOperation; }
2841 void doit();
2842 };
2843
2844
2845 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2846 Handle initial_object,
2847 BasicHeapWalkContext callbacks,
2848 const void* user_data,
2849 GrowableArray<jlong>* objects) {
2850 _is_advanced_heap_walk = false;
2851 _tag_map = tag_map;
2852 _initial_object = initial_object;
2853 _following_object_refs = (callbacks.object_ref_callback() != nullptr);
2854 _reporting_primitive_fields = false;
2855 _reporting_primitive_array_values = false;
2856 _reporting_string_values = false;
2857 _dead_objects = objects;
2858 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, user_data, callbacks, &_visit_stack);
2859 }
2860
2861 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2862 Handle initial_object,
2863 AdvancedHeapWalkContext callbacks,
2864 const void* user_data,
2865 GrowableArray<jlong>* objects) {
2866 _is_advanced_heap_walk = true;
2867 _tag_map = tag_map;
2868 _initial_object = initial_object;
2869 _following_object_refs = true;
2870 _reporting_primitive_fields = (callbacks.primitive_field_callback() != nullptr);;
2871 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != nullptr);;
2872 _reporting_string_values = (callbacks.string_primitive_value_callback() != nullptr);;
2873 _dead_objects = objects;
2874 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, user_data, callbacks, &_visit_stack);
2875 }
2876
2877 VM_HeapWalkOperation::~VM_HeapWalkOperation() {
2878 }
2879
2880 // an array references its class and has a reference to
2881 // each element in the array
2882 inline bool VM_HeapWalkOperation::iterate_over_array(const JvmtiHeapwalkObject& o) {
2883 assert(!o.is_flat(), "Array object cannot be flattened");
2884 objArrayOop array = objArrayOop(o.obj());
2885
2886 // array reference to its class
2887 oop mirror = ObjArrayKlass::cast(array->klass())->java_mirror();
2888 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2889 return false;
2890 }
2891
2892 // iterate over the array and report each reference to a
2893 // non-null element
2894 for (int index=0; index<array->length(); index++) {
2895 oop elem = array->obj_at(index);
2896 if (elem == nullptr) {
2897 continue;
2898 }
2899
2900 // report the array reference o[index] = elem
2901 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2902 return false;
2903 }
2904 }
2905 return true;
2906 }
2907
2908 // similar to iterate_over_array(), but itrates over flat array
2909 inline bool VM_HeapWalkOperation::iterate_over_flat_array(const JvmtiHeapwalkObject& o) {
2910 assert(!o.is_flat(), "Array object cannot be flattened");
2911 flatArrayOop array = flatArrayOop(o.obj());
2912 FlatArrayKlass* faklass = FlatArrayKlass::cast(array->klass());
2913 InlineKlass* vk = InlineKlass::cast(faklass->element_klass());
2914 bool need_null_check = LayoutKindHelper::is_nullable_flat(faklass->layout_kind());
2915
2916 // array reference to its class
2917 oop mirror = faklass->java_mirror();
2918 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2919 return false;
2920 }
2921
2922 // iterate over the array and report each reference to a
2923 // non-null element
2924 for (int index = 0; index < array->length(); index++) {
2925 address addr = (address)array->value_at_addr(index, faklass->layout_helper());
2926
2927 // check for null
2928 if (need_null_check) {
2929 if (vk->is_payload_marked_as_null(addr)) {
2930 continue;
2931 }
2932 }
2933
2934 // offset in the array oop
2935 int offset = (int)(addr - cast_from_oop<address>(array));
2936 JvmtiHeapwalkObject elem(o.obj(), offset, vk, faklass->layout_kind());
2937
2938 // report the array reference
2939 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2940 return false;
2941 }
2942 }
2943 return true;
2944 }
2945
2946 // a type array references its class
2947 inline bool VM_HeapWalkOperation::iterate_over_type_array(const JvmtiHeapwalkObject& o) {
2948 assert(!o.is_flat(), "Array object cannot be flattened");
2949 Klass* k = o.klass();
2950 oop mirror = k->java_mirror();
2951 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2952 return false;
2953 }
2954
2955 // report the array contents if required
2956 if (is_reporting_primitive_array_values()) {
2957 if (!CallbackInvoker::report_primitive_array_values(o)) {
2958 return false;
2959 }
2960 }
2961 return true;
2962 }
2963
2964 #ifdef ASSERT
2965 // verify that a static oop field is in range
2966 static inline bool verify_static_oop(InstanceKlass* ik,
2967 oop mirror, int offset) {
2968 address obj_p = cast_from_oop<address>(mirror) + offset;
2969 address start = (address)InstanceMirrorKlass::start_of_static_fields(mirror);
2970 address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize);
2971 assert(end >= start, "sanity check");
2972
2973 if (obj_p >= start && obj_p < end) {
2974 return true;
2975 } else {
2976 return false;
2977 }
2978 }
2979 #endif // #ifdef ASSERT
2980
2981 // a class references its super class, interfaces, class loader, ...
2982 // and finally its static fields
2983 inline bool VM_HeapWalkOperation::iterate_over_class(const JvmtiHeapwalkObject& o) {
2984 assert(!o.is_flat(), "Klass object cannot be flattened");
2985 Klass* klass = java_lang_Class::as_Klass(o.obj());
2986 int i;
2987
2988 if (klass->is_instance_klass()) {
2989 InstanceKlass* ik = InstanceKlass::cast(klass);
2990
2991 // Ignore the class if it hasn't been initialized yet
2992 if (!ik->is_linked()) {
2993 return true;
2994 }
2995
2996 // get the java mirror
2997 oop mirror_oop = klass->java_mirror();
2998 JvmtiHeapwalkObject mirror(mirror_oop);
2999
3000 // super (only if something more interesting than java.lang.Object)
3001 InstanceKlass* super_klass = ik->super();
3002 if (super_klass != nullptr && super_klass != vmClasses::Object_klass()) {
3003 oop super_oop = super_klass->java_mirror();
3004 if (!CallbackInvoker::report_superclass_reference(mirror, super_oop)) {
3005 return false;
3006 }
3007 }
3008
3009 // class loader
3010 oop cl = ik->class_loader();
3011 if (cl != nullptr) {
3012 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
3013 return false;
3014 }
3015 }
3016
3017 // protection domain
3018 oop pd = ik->protection_domain();
3019 if (pd != nullptr) {
3020 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
3021 return false;
3022 }
3023 }
3024
3025 // signers
3026 oop signers = ik->signers();
3027 if (signers != nullptr) {
3028 if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
3029 return false;
3030 }
3031 }
3032
3033 // references from the constant pool
3034 {
3035 ConstantPool* pool = ik->constants();
3036 for (int i = 1; i < pool->length(); i++) {
3037 constantTag tag = pool->tag_at(i).value();
3038 if (tag.is_string() || tag.is_klass() || tag.is_unresolved_klass()) {
3039 oop entry;
3040 if (tag.is_string()) {
3041 entry = pool->resolved_string_at(i);
3042 // If the entry is non-null it is resolved.
3043 if (entry == nullptr) {
3044 continue;
3045 }
3046 } else if (tag.is_klass()) {
3047 entry = pool->resolved_klass_at(i)->java_mirror();
3048 } else {
3049 // Code generated by JIT compilers might not resolve constant
3050 // pool entries. Treat them as resolved if they are loaded.
3051 assert(tag.is_unresolved_klass(), "must be");
3052 constantPoolHandle cp(Thread::current(), pool);
3053 Klass* klass = ConstantPool::klass_at_if_loaded(cp, i);
3054 if (klass == nullptr) {
3055 continue;
3056 }
3057 entry = klass->java_mirror();
3058 }
3059 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
3060 return false;
3061 }
3062 }
3063 }
3064 }
3065
3066 // interfaces
3067 // (These will already have been reported as references from the constant pool
3068 // but are specified by IterateOverReachableObjects and must be reported).
3069 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
3070 for (i = 0; i < interfaces->length(); i++) {
3071 oop interf = interfaces->at(i)->java_mirror();
3072 if (interf == nullptr) {
3073 continue;
3074 }
3075 if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
3076 return false;
3077 }
3078 }
3079
3080 // iterate over the static fields
3081
3082 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
3083 for (i=0; i<field_map->field_count(); i++) {
3084 ClassFieldDescriptor* field = field_map->field_at(i);
3085 char type = field->field_type();
3086 if (!is_primitive_field_type(type)) {
3087 oop fld_o = mirror_oop->obj_field(field->field_offset());
3088 assert(verify_static_oop(ik, mirror_oop, field->field_offset()), "sanity check");
3089 if (fld_o != nullptr) {
3090 int slot = field->field_index();
3091 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
3092 delete field_map;
3093 return false;
3094 }
3095 }
3096 } else {
3097 if (is_reporting_primitive_fields()) {
3098 address addr = cast_from_oop<address>(mirror_oop) + field->field_offset();
3099 int slot = field->field_index();
3100 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
3101 delete field_map;
3102 return false;
3103 }
3104 }
3105 }
3106 }
3107 delete field_map;
3108
3109 return true;
3110 }
3111
3112 return true;
3113 }
3114
3115 // an object references a class and its instance fields
3116 // (static fields are ignored here as we report these as
3117 // references from the class).
3118 inline bool VM_HeapWalkOperation::iterate_over_object(const JvmtiHeapwalkObject& o) {
3119 // reference to the class
3120 if (!CallbackInvoker::report_class_reference(o, o.klass()->java_mirror())) {
3121 return false;
3122 }
3123
3124 // iterate over instance fields
3125 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o.klass());
3126 for (int i=0; i<field_map->field_count(); i++) {
3127 ClassFieldDescriptor* field = field_map->field_at(i);
3128 char type = field->field_type();
3129 int slot = field->field_index();
3130 int field_offset = field->field_offset();
3131 if (o.is_flat()) {
3132 // the object is inlined, its fields are stored without the header
3133 field_offset += o.offset() - o.inline_klass()->payload_offset();
3134 }
3135 if (!is_primitive_field_type(type)) {
3136 if (field->is_flat()) {
3137 // check for possible nulls
3138 if (LayoutKindHelper::is_nullable_flat(field->layout_kind())) {
3139 address payload = cast_from_oop<address>(o.obj()) + field_offset;
3140 if (field->inline_klass()->is_payload_marked_as_null(payload)) {
3141 continue;
3142 }
3143 }
3144 JvmtiHeapwalkObject field_obj(o.obj(), field_offset, field->inline_klass(), field->layout_kind());
3145 if (!CallbackInvoker::report_field_reference(o, field_obj, slot)) {
3146 return false;
3147 }
3148 } else {
3149 oop fld_o = o.obj()->obj_field_access<AS_NO_KEEPALIVE | ON_UNKNOWN_OOP_REF>(field_offset);
3150 // ignore any objects that aren't visible to profiler
3151 if (fld_o != nullptr) {
3152 assert(Universe::heap()->is_in(fld_o), "unsafe code should not have references to Klass* anymore");
3153 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
3154 return false;
3155 }
3156 }
3157 }
3158 } else {
3159 if (is_reporting_primitive_fields()) {
3160 // primitive instance field
3161 address addr = cast_from_oop<address>(o.obj()) + field_offset;
3162 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
3163 return false;
3164 }
3165 }
3166 }
3167 }
3168
3169 // if the object is a java.lang.String
3170 if (is_reporting_string_values() &&
3171 o.klass() == vmClasses::String_klass()) {
3172 if (!CallbackInvoker::report_string_value(o)) {
3173 return false;
3174 }
3175 }
3176 return true;
3177 }
3178
3179
3180 // Collects all simple (non-stack) roots except for threads;
3181 // threads are handled in collect_stack_roots() as an optimization.
3182 // if there's a heap root callback provided then the callback is
3183 // invoked for each simple root.
3184 // if an object reference callback is provided then all simple
3185 // roots are pushed onto the marking stack so that they can be
3186 // processed later
3187 //
3188 inline bool VM_HeapWalkOperation::collect_simple_roots() {
3189 SimpleRootsClosure blk;
3190
3191 // JNI globals
3192 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
3193 JNIHandles::oops_do(&blk);
3194 if (blk.stopped()) {
3195 return false;
3196 }
3197
3198 // Preloaded classes and loader from the system dictionary
3199 CLDRootsClosure cld_roots_closure;
3200 CLDToOopClosure cld_closure(&cld_roots_closure, ClassLoaderData::_claim_none);
3201 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
3202 if (cld_roots_closure.stopped()) {
3203 return false;
3204 }
3205
3206 // threads are now handled in collect_stack_roots()
3207
3208 // Other kinds of roots maintained by HotSpot
3209 // Many of these won't be visible but others (such as instances of important
3210 // exceptions) will be visible.
3211 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3212 Universe::vm_global()->oops_do(&blk);
3213 if (blk.stopped()) {
3214 return false;
3215 }
3216
3217 return true;
3218 }
3219
3220 // Reports the thread as JVMTI_HEAP_REFERENCE_THREAD,
3221 // walks the stack of the thread, finds all references (locals
3222 // and JNI calls) and reports these as stack references.
3223 inline bool VM_HeapWalkOperation::collect_stack_refs(JavaThread* java_thread,
3224 JNILocalRootsClosure* blk)
3225 {
3226 oop threadObj = java_thread->threadObj();
3227 oop mounted_vt = java_thread->is_vthread_mounted() ? java_thread->vthread() : nullptr;
3228 if (mounted_vt != nullptr && !JvmtiEnvBase::is_vthread_alive(mounted_vt)) {
3229 mounted_vt = nullptr;
3230 }
3231 assert(threadObj != nullptr, "sanity check");
3232
3233 StackRefCollector stack_collector(tag_map(), blk, java_thread);
3234
3235 if (!java_thread->has_last_Java_frame()) {
3236 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_THREAD, threadObj)) {
3237 return false;
3238 }
3239 // no last java frame but there may be JNI locals
3240 blk->set_context(_tag_map->find(threadObj), java_lang_Thread::thread_id(threadObj), 0, (jmethodID)nullptr);
3241 java_thread->active_handles()->oops_do(blk);
3242 return !blk->stopped();
3243 }
3244 // vframes are resource allocated
3245 Thread* current_thread = Thread::current();
3246 ResourceMark rm(current_thread);
3247 HandleMark hm(current_thread);
3248
3249 RegisterMap reg_map(java_thread,
3250 RegisterMap::UpdateMap::include,
3251 RegisterMap::ProcessFrames::include,
3252 RegisterMap::WalkContinuation::include);
3253
3254 // first handle mounted vthread (if any)
3255 if (mounted_vt != nullptr) {
3256 frame f = java_thread->last_frame();
3257 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread);
3258 // report virtual thread as JVMTI_HEAP_REFERENCE_OTHER
3259 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_OTHER, mounted_vt)) {
3260 return false;
3261 }
3262 // split virtual thread and carrier thread stacks by vthread entry ("enterSpecial") frame,
3263 // consider vthread entry frame as the last vthread stack frame
3264 while (vf != nullptr) {
3265 if (!stack_collector.do_frame(vf)) {
3266 return false;
3267 }
3268 if (vf->is_vthread_entry()) {
3269 break;
3270 }
3271 vf = vf->sender();
3272 }
3273 }
3274 // Platform or carrier thread.
3275 vframe* vf = JvmtiEnvBase::get_cthread_last_java_vframe(java_thread, ®_map);
3276 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_THREAD, threadObj)) {
3277 return false;
3278 }
3279 return stack_collector.process_frames(vf);
3280 }
3281
3282
3283 // Collects the simple roots for all threads and collects all
3284 // stack roots - for each thread it walks the execution
3285 // stack to find all references and local JNI refs.
3286 inline bool VM_HeapWalkOperation::collect_stack_roots() {
3287 JNILocalRootsClosure blk;
3288 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
3289 oop threadObj = thread->threadObj();
3290 if (threadObj != nullptr && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3291 if (!collect_stack_refs(thread, &blk)) {
3292 return false;
3293 }
3294 }
3295 }
3296 return true;
3297 }
3298
3299 // Reports stack references for the unmounted virtual thread.
3300 inline bool VM_HeapWalkOperation::collect_vthread_stack_refs(oop vt) {
3301 if (!JvmtiEnvBase::is_vthread_alive(vt)) {
3302 return true;
3303 }
3304 ContinuationWrapper cont(java_lang_VirtualThread::continuation(vt));
3305 if (cont.is_empty()) {
3306 return true;
3307 }
3308 assert(!cont.is_mounted(), "sanity check");
3309
3310 stackChunkOop chunk = cont.last_nonempty_chunk();
3311 if (chunk == nullptr || chunk->is_empty()) {
3312 return true;
3313 }
3314
3315 // vframes are resource allocated
3316 Thread* current_thread = Thread::current();
3317 ResourceMark rm(current_thread);
3318 HandleMark hm(current_thread);
3319
3320 RegisterMap reg_map(cont.continuation(), RegisterMap::UpdateMap::include);
3321
3322 JNILocalRootsClosure blk;
3323 // JavaThread is not required for unmounted virtual threads
3324 StackRefCollector stack_collector(tag_map(), &blk, nullptr);
3325 // reference to the vthread is already reported
3326 if (!stack_collector.set_thread(vt)) {
3327 return false;
3328 }
3329
3330 frame fr = chunk->top_frame(®_map);
3331 vframe* vf = vframe::new_vframe(&fr, ®_map, nullptr);
3332 return stack_collector.process_frames(vf);
3333 }
3334
3335 // visit an object
3336 // first mark the object as visited
3337 // second get all the outbound references from this object (in other words, all
3338 // the objects referenced by this object).
3339 //
3340 bool VM_HeapWalkOperation::visit(const JvmtiHeapwalkObject& o) {
3341 // mark object as visited
3342 assert(!visit_stack()->is_visited(o), "can't visit same object more than once");
3343 visit_stack()->mark_visited(o);
3344
3345 Klass* klass = o.klass();
3346 // instance
3347 if (klass->is_instance_klass()) {
3348 if (klass == vmClasses::Class_klass()) {
3349 assert(!o.is_flat(), "Class object cannot be flattened");
3350 if (!java_lang_Class::is_primitive(o.obj())) {
3351 // a java.lang.Class
3352 return iterate_over_class(o);
3353 }
3354 } else {
3355 // we report stack references only when initial object is not specified
3356 // (in the case we start from heap roots which include platform thread stack references)
3357 if (initial_object().is_null() && java_lang_VirtualThread::is_subclass(klass)) {
3358 assert(!o.is_flat(), "VirtualThread object cannot be flattened");
3359 if (!collect_vthread_stack_refs(o.obj())) {
3360 return false;
3361 }
3362 }
3363 return iterate_over_object(o);
3364 }
3365 }
3366
3367 // flat object array
3368 if (klass->is_flatArray_klass()) {
3369 return iterate_over_flat_array(o);
3370 }
3371
3372 // object array
3373 if (klass->is_objArray_klass()) {
3374 return iterate_over_array(o);
3375 }
3376
3377 // type array
3378 if (klass->is_typeArray_klass()) {
3379 return iterate_over_type_array(o);
3380 }
3381
3382 return true;
3383 }
3384
3385 void VM_HeapWalkOperation::doit() {
3386 ResourceMark rm;
3387 ClassFieldMapCacheMark cm;
3388
3389 JvmtiTagMap::check_hashmaps_for_heapwalk(_dead_objects);
3390
3391 assert(visit_stack()->is_empty(), "visit stack must be empty");
3392
3393 // the heap walk starts with an initial object or the heap roots
3394 if (initial_object().is_null()) {
3395 // can result in a big performance boost for an agent that is
3396 // focused on analyzing references in the thread stacks.
3397 if (!collect_stack_roots()) return;
3398
3399 if (!collect_simple_roots()) return;
3400 } else {
3401 visit_stack()->push(initial_object()());
3402 }
3403
3404 // object references required
3405 if (is_following_references()) {
3406
3407 // visit each object until all reachable objects have been
3408 // visited or the callback asked to terminate the iteration.
3409 while (!visit_stack()->is_empty()) {
3410 const JvmtiHeapwalkObject o = visit_stack()->pop();
3411 if (!visit_stack()->is_visited(o)) {
3412 if (!visit(o)) {
3413 break;
3414 }
3415 }
3416 }
3417 }
3418 }
3419
3420 // iterate over all objects that are reachable from a set of roots
3421 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
3422 jvmtiStackReferenceCallback stack_ref_callback,
3423 jvmtiObjectReferenceCallback object_ref_callback,
3424 const void* user_data) {
3425 // VTMS transitions must be disabled before the EscapeBarrier.
3426 MountUnmountDisabler disabler;
3427
3428 JavaThread* jt = JavaThread::current();
3429 EscapeBarrier eb(true, jt);
3430 eb.deoptimize_objects_all_threads();
3431 Arena dead_object_arena(mtServiceability);
3432 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
3433
3434 {
3435 MutexLocker ml(Heap_lock);
3436 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
3437 VM_HeapWalkOperation op(this, Handle(), context, user_data, &dead_objects);
3438 VMThread::execute(&op);
3439 }
3440 convert_flat_object_entries();
3441
3442 // Post events outside of Heap_lock
3443 post_dead_objects(&dead_objects);
3444 }
3445
3446 // iterate over all objects that are reachable from a given object
3447 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
3448 jvmtiObjectReferenceCallback object_ref_callback,
3449 const void* user_data) {
3450 oop obj = JNIHandles::resolve(object);
3451 Handle initial_object(Thread::current(), obj);
3452
3453 Arena dead_object_arena(mtServiceability);
3454 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
3455
3456 MountUnmountDisabler disabler;
3457
3458 {
3459 MutexLocker ml(Heap_lock);
3460 BasicHeapWalkContext context(nullptr, nullptr, object_ref_callback);
3461 VM_HeapWalkOperation op(this, initial_object, context, user_data, &dead_objects);
3462 VMThread::execute(&op);
3463 }
3464 convert_flat_object_entries();
3465
3466 // Post events outside of Heap_lock
3467 post_dead_objects(&dead_objects);
3468 }
3469
3470 // follow references from an initial object or the GC roots
3471 void JvmtiTagMap::follow_references(jint heap_filter,
3472 Klass* klass,
3473 jobject object,
3474 const jvmtiHeapCallbacks* callbacks,
3475 const void* user_data)
3476 {
3477 // VTMS transitions must be disabled before the EscapeBarrier.
3478 MountUnmountDisabler disabler;
3479
3480 oop obj = JNIHandles::resolve(object);
3481 JavaThread* jt = JavaThread::current();
3482 Handle initial_object(jt, obj);
3483 // EA based optimizations that are tagged or reachable from initial_object are already reverted.
3484 EscapeBarrier eb(initial_object.is_null() &&
3485 !(heap_filter & JVMTI_HEAP_FILTER_UNTAGGED),
3486 jt);
3487 eb.deoptimize_objects_all_threads();
3488
3489 Arena dead_object_arena(mtServiceability);
3490 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
3491
3492 {
3493 MutexLocker ml(Heap_lock);
3494 AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
3495 VM_HeapWalkOperation op(this, initial_object, context, user_data, &dead_objects);
3496 VMThread::execute(&op);
3497 }
3498 convert_flat_object_entries();
3499
3500 // Post events outside of Heap_lock
3501 post_dead_objects(&dead_objects);
3502 }
3503
3504 // Verify gc_notification follows set_needs_cleaning.
3505 DEBUG_ONLY(static bool notified_needs_cleaning = false;)
3506
3507 void JvmtiTagMap::set_needs_cleaning() {
3508 assert(SafepointSynchronize::is_at_safepoint(), "called in gc pause");
3509 assert(Thread::current()->is_VM_thread(), "should be the VM thread");
3510 // Can't assert !notified_needs_cleaning; a partial GC might be upgraded
3511 // to a full GC and do this twice without intervening gc_notification.
3512 DEBUG_ONLY(notified_needs_cleaning = true;)
3513
3514 JvmtiEnvIterator it;
3515 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) {
3516 JvmtiTagMap* tag_map = env->tag_map_acquire();
3517 if (tag_map != nullptr) {
3518 tag_map->_needs_cleaning = !tag_map->is_empty();
3519 }
3520 }
3521 }
3522
3523 void JvmtiTagMap::gc_notification(size_t num_dead_entries) {
3524 assert(notified_needs_cleaning, "missing GC notification");
3525 DEBUG_ONLY(notified_needs_cleaning = false;)
3526
3527 // Notify ServiceThread if there's work to do.
3528 {
3529 MonitorLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
3530 _has_object_free_events = (num_dead_entries != 0);
3531 if (_has_object_free_events) ml.notify_all();
3532 }
3533
3534 // If no dead entries then cancel cleaning requests.
3535 if (num_dead_entries == 0) {
3536 JvmtiEnvIterator it;
3537 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) {
3538 JvmtiTagMap* tag_map = env->tag_map_acquire();
3539 if (tag_map != nullptr) {
3540 MutexLocker ml (tag_map->lock(), Mutex::_no_safepoint_check_flag);
3541 tag_map->_needs_cleaning = false;
3542 }
3543 }
3544 }
3545 }
3546
3547 // Used by ServiceThread to discover there is work to do.
3548 bool JvmtiTagMap::has_object_free_events_and_reset() {
3549 assert_lock_strong(Service_lock);
3550 bool result = _has_object_free_events;
3551 _has_object_free_events = false;
3552 return result;
3553 }
3554
3555 // Used by ServiceThread to clean up tagmaps.
3556 void JvmtiTagMap::flush_all_object_free_events() {
3557 JavaThread* thread = JavaThread::current();
3558 JvmtiEnvIterator it;
3559 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) {
3560 JvmtiTagMap* tag_map = env->tag_map_acquire();
3561 if (tag_map != nullptr) {
3562 tag_map->flush_object_free_events();
3563 ThreadBlockInVM tbiv(thread); // Be safepoint-polite while looping.
3564 }
3565 }
3566 }