1 /*
2 * Copyright (c) 2003, 2026, 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/inlineKlass.inline.hpp"
41 #include "oops/instanceMirrorKlass.hpp"
42 #include "oops/klass.inline.hpp"
43 #include "oops/objArrayKlass.hpp"
44 #include "oops/objArrayOop.inline.hpp"
45 #include "oops/oop.inline.hpp"
46 #include "oops/oopCast.inline.hpp"
47 #include "oops/typeArrayOop.inline.hpp"
48 #include "oops/valuePayload.inline.hpp"
49 #include "prims/jvmtiEventController.inline.hpp"
50 #include "prims/jvmtiExport.hpp"
51 #include "prims/jvmtiImpl.hpp"
52 #include "prims/jvmtiTagMap.hpp"
53 #include "prims/jvmtiTagMapTable.hpp"
54 #include "prims/jvmtiThreadState.hpp"
55 #include "runtime/continuationWrapper.inline.hpp"
56 #include "runtime/deoptimization.hpp"
57 #include "runtime/frame.inline.hpp"
58 #include "runtime/handles.inline.hpp"
59 #include "runtime/interfaceSupport.inline.hpp"
60 #include "runtime/javaCalls.hpp"
61 #include "runtime/javaThread.inline.hpp"
62 #include "runtime/jniHandles.inline.hpp"
63 #include "runtime/mountUnmountDisabler.hpp"
64 #include "runtime/mutex.hpp"
65 #include "runtime/mutexLocker.hpp"
66 #include "runtime/safepoint.hpp"
67 #include "runtime/threadSMR.hpp"
68 #include "runtime/timerTrace.hpp"
69 #include "runtime/vframe.hpp"
70 #include "runtime/vmOperations.hpp"
71 #include "runtime/vmThread.hpp"
72 #include "utilities/macros.hpp"
73 #include "utilities/objectBitSet.inline.hpp"
74
75 typedef ObjectBitSet<mtServiceability> JVMTIBitSet;
76
77
78 // Helper class to store objects to visit.
79 class JvmtiHeapwalkVisitStack {
80 private:
81 enum {
82 initial_visit_stack_size = 4000
83 };
84
85 GrowableArray<JvmtiHeapwalkObject>* _visit_stack;
86 JVMTIBitSet _bitset;
87
88 static GrowableArray<JvmtiHeapwalkObject>* create_visit_stack() {
89 return new (mtServiceability) GrowableArray<JvmtiHeapwalkObject>(initial_visit_stack_size, mtServiceability);
90 }
91
92 public:
93 JvmtiHeapwalkVisitStack(): _visit_stack(create_visit_stack()) {
94 }
95 ~JvmtiHeapwalkVisitStack() {
96 if (_visit_stack != nullptr) {
97 delete _visit_stack;
98 }
99 }
100
101 bool is_empty() const {
102 return _visit_stack->is_empty();
103 }
104
105 void push(const JvmtiHeapwalkObject& obj) {
106 _visit_stack->push(obj);
107 }
108
109 // If the object hasn't been visited then push it onto the visit stack
110 // so that it will be visited later.
111 void check_for_visit(const JvmtiHeapwalkObject& obj) {
112 if (!is_visited(obj)) {
113 _visit_stack->push(obj);
114 }
115 }
116
117 JvmtiHeapwalkObject pop() {
118 return _visit_stack->pop();
119 }
120
121 bool is_visited(const JvmtiHeapwalkObject& obj) /*const*/ { // TODO: _bitset.is_marked() should be const
122 // The method is called only for objects from visit_stack to ensure an object is not visited twice.
123 // Flat objects can be added to visit_stack only when we visit their holder object, so we cannot get duplicate reference to it.
124 if (obj.is_flat()) {
125 return false;
126 }
127 return _bitset.is_marked(obj.obj());
128 }
129
130 void mark_visited(const JvmtiHeapwalkObject& obj) {
131 if (!obj.is_flat()) {
132 _bitset.mark_obj(obj.obj());
133 }
134 }
135 };
136
137
138 bool JvmtiTagMap::_has_object_free_events = false;
139
140 // create a JvmtiTagMap
141 JvmtiTagMap::JvmtiTagMap(JvmtiEnv* env) :
142 _env(env),
143 _lock(Mutex::nosafepoint, "JvmtiTagMap_lock"),
144 _needs_cleaning(false),
145 _posting_events(false),
146 _converting_flat_object(false) {
147
148 assert(JvmtiThreadState_lock->is_locked(), "sanity check");
149 assert(((JvmtiEnvBase *)env)->tag_map() == nullptr, "tag map already exists for environment");
150
151 _hashmap = new JvmtiTagMapTable();
152 _flat_hashmap = new JvmtiFlatTagMapTable();
153
154 // finally add us to the environment
155 ((JvmtiEnvBase *)env)->release_set_tag_map(this);
156 }
157
158 // destroy a JvmtiTagMap
159 JvmtiTagMap::~JvmtiTagMap() {
160
161 // no lock acquired as we assume the enclosing environment is
162 // also being destroyed.
163 ((JvmtiEnvBase *)_env)->set_tag_map(nullptr);
164
165 // finally destroy the hashmap
166 delete _hashmap;
167 _hashmap = nullptr;
168 delete _flat_hashmap;
169 }
170
171 // Called by env_dispose() to reclaim memory before deallocation.
172 // Remove all the entries but keep the empty table intact.
173 // This needs the table lock.
174 void JvmtiTagMap::clear() {
175 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
176 _hashmap->clear();
177 _flat_hashmap->clear();
178 }
179
180 // returns the tag map for the given environments. If the tag map
181 // doesn't exist then it is created.
182 JvmtiTagMap* JvmtiTagMap::tag_map_for(JvmtiEnv* env) {
183 JvmtiTagMap* tag_map = ((JvmtiEnvBase*)env)->tag_map_acquire();
184 if (tag_map == nullptr) {
185 MutexLocker mu(JvmtiThreadState_lock);
186 tag_map = ((JvmtiEnvBase*)env)->tag_map();
187 if (tag_map == nullptr) {
188 tag_map = new JvmtiTagMap(env);
189 }
190 } else {
191 DEBUG_ONLY(JavaThread::current()->check_possible_safepoint());
192 }
193 return tag_map;
194 }
195
196 // returns true if the hashmaps are empty
197 bool JvmtiTagMap::is_empty() const {
198 assert(SafepointSynchronize::is_at_safepoint() || is_locked(), "checking");
199 return _hashmap->is_empty() && _flat_hashmap->is_empty();
200 }
201
202 // This checks for posting before operations that use
203 // this tagmap table.
204 void JvmtiTagMap::check_hashmap(GrowableArray<jlong>* objects) {
205 assert(is_locked(), "checking");
206
207 if (is_empty()) { return; }
208
209 if (_needs_cleaning &&
210 objects != nullptr &&
211 env()->is_enabled(JVMTI_EVENT_OBJECT_FREE)) {
212 remove_dead_entries_locked(objects);
213 }
214 }
215
216 // This checks for posting and is called from the heap walks.
217 void JvmtiTagMap::check_hashmaps_for_heapwalk(GrowableArray<jlong>* objects) {
218 assert(SafepointSynchronize::is_at_safepoint(), "called from safepoints");
219
220 // Verify that the tag map tables are valid and unconditionally post events
221 // that are expected to be posted before gc_notification.
222 JvmtiEnvIterator it;
223 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) {
224 JvmtiTagMap* tag_map = env->tag_map_acquire();
225 if (tag_map != nullptr) {
226 // The ZDriver may be walking the hashmaps concurrently so this lock is needed.
227 MutexLocker ml(tag_map->lock(), Mutex::_no_safepoint_check_flag);
228 tag_map->check_hashmap(objects);
229 }
230 }
231 }
232
233 // Converts entries from JvmtiFlatTagMapTable to JvmtiTagMapTable in batches.
234 // 1. (JvmtiTagMap is locked)
235 // reads entries from JvmtiFlatTagMapTable (describe flat value objects);
236 // 2. (JvmtiTagMap is unlocked)
237 // creates heap-allocated copies of the flat object;
238 // 3. (JvmtiTagMap is locked)
239 // ensures source entry still exists, removes it from JvmtiFlatTagMapTable, adds new entry to JvmtiTagMapTable.
240 // If some error occurs in step 2 (OOM?), the process stops.
241 class JvmtiTagMapFlatEntryConverter: public StackObj {
242 private:
243 struct Entry {
244 // source flat value object
245 Handle holder;
246 int offset;
247 InlineKlass* inline_klass;
248 LayoutKind layout_kind;
249 // converted heap-allocated object
250 Handle dst;
251
252 Entry(): holder(), offset(0), inline_klass(nullptr), dst() {}
253 Entry(Handle holder, int offset, InlineKlass* inline_klass, LayoutKind lk)
254 : holder(holder), offset(offset), inline_klass(inline_klass), layout_kind(lk), dst() {}
255 };
256
257 int _batch_size;
258 GrowableArray<Entry> _entries;
259 bool _has_error;
260
261 public:
262 JvmtiTagMapFlatEntryConverter(int batch_size): _batch_size(batch_size), _entries(batch_size, mtServiceability), _has_error(false) { }
263 ~JvmtiTagMapFlatEntryConverter() {}
264
265 // returns false if there is nothing to convert
266 bool import_entries(JvmtiFlatTagMapTable* table) {
267 if (_has_error) {
268 // stop the process to avoid infinite loop
269 return false;
270 }
271
272 class Importer: public JvmtiFlatTagMapKeyClosure {
273 private:
274 GrowableArray<Entry>& _entries;
275 int _batch_size;
276 public:
277 Importer(GrowableArray<Entry>& entries, int batch_size): _entries(entries), _batch_size(batch_size) {}
278
279 bool do_entry(JvmtiFlatTagMapKey& key, jlong& tag) {
280 Entry entry(Handle(Thread::current(), key.holder()), key.offset(), key.inline_klass(), key.layout_kind());
281 _entries.append(entry);
282
283 return _entries.length() < _batch_size;
284 }
285 } importer(_entries, _batch_size);
286 table->entry_iterate(&importer);
287
288 return !_entries.is_empty();
289 }
290
291 void convert() {
292 for (int i = 0; i < _entries.length(); i++) {
293 EXCEPTION_MARK;
294 Entry& entry = _entries.at(i);
295 FlatValuePayload payload = FlatValuePayload::construct_from_parts(
296 entry.holder(), entry.offset, entry.inline_klass, entry.layout_kind);
297 oop obj = payload.read(JavaThread::current());
298
299 if (HAS_PENDING_EXCEPTION) {
300 tty->print_cr("Exception in JvmtiTagMapFlatEntryConverter: ");
301 java_lang_Throwable::print(PENDING_EXCEPTION, tty);
302 tty->cr();
303 CLEAR_PENDING_EXCEPTION;
304 // stop the conversion
305 _has_error = true;
306 } else {
307 entry.dst = Handle(Thread::current(), obj);
308 }
309 }
310 }
311
312 // returns number of converted entries
313 int move(JvmtiFlatTagMapTable* src_table, JvmtiTagMapTable* dst_table) {
314 int count = 0;
315 for (int i = 0; i < _entries.length(); i++) {
316 Entry& entry = _entries.at(i);
317 if (entry.dst() == nullptr) {
318 // some error during conversion, skip the entry
319 continue;
320 }
321 JvmtiHeapwalkObject obj(entry.holder(), entry.offset, entry.inline_klass, entry.layout_kind);
322 jlong tag = src_table->remove(obj);
323
324 if (tag != 0) { // ensure the entry is still in the src_table
325 dst_table->add(entry.dst(), tag);
326 count++;
327 } else {
328
329 }
330 }
331 // and clean the array
332 _entries.clear();
333 return count;
334 }
335 };
336
337
338 void JvmtiTagMap::convert_flat_object_entries() {
339 Thread* current = Thread::current();
340 assert(current->is_Java_thread(), "must be executed on JavaThread");
341
342 log_debug(jvmti, table)("convert_flat_object_entries, main table size = %d, flat table size = %d",
343 _hashmap->number_of_entries(), _flat_hashmap->number_of_entries());
344
345 {
346 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
347 // If another thread is converting, let it finish.
348 while (_converting_flat_object) {
349 ml.wait();
350 }
351 if (_flat_hashmap->is_empty()) {
352 // nothing to convert
353 return;
354 }
355 _converting_flat_object = true;
356 }
357
358 const int BATCH_SIZE = 1024;
359 JvmtiTagMapFlatEntryConverter converter(BATCH_SIZE);
360
361 int count = 0;
362 while (true) {
363 HandleMark hm(current);
364 {
365 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
366 if (!converter.import_entries(_flat_hashmap)) {
367 break;
368 }
369 }
370 // Convert flat objects to heap-allocated without table lock (so agent callbacks can get/set tags).
371 converter.convert();
372 {
373 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
374 count += converter.move(_flat_hashmap, _hashmap);
375 }
376 }
377
378 log_info(jvmti, table)("%d flat value objects are converted, flat table size = %d",
379 count, _flat_hashmap->number_of_entries());
380 {
381 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
382 _converting_flat_object = false;
383 ml.notify_all();
384 }
385 }
386
387 jlong JvmtiTagMap::find(const JvmtiHeapwalkObject& obj) const {
388 jlong tag = _hashmap->find(obj);
389 if (tag == 0 && obj.is_value()) {
390 tag = _flat_hashmap->find(obj);
391 }
392 return tag;
393 }
394
395 void JvmtiTagMap::add(const JvmtiHeapwalkObject& obj, jlong tag) {
396 if (obj.is_flat()) {
397 // we may have tag for equal (non-flat) object in _hashmap, try to update it 1st
398 if (!_hashmap->update(obj, tag)) {
399 // no entry in _hashmap, add to _flat_hashmap
400 _flat_hashmap->add(obj, tag);
401 }
402 } else {
403 _hashmap->add(obj, tag);
404 }
405 }
406
407 void JvmtiTagMap::remove(const JvmtiHeapwalkObject& obj) {
408 if (!_hashmap->remove(obj)) {
409 if (obj.is_value()) {
410 _flat_hashmap->remove(obj);
411 }
412 }
413 }
414
415
416 // A CallbackWrapper is a support class for querying and tagging an object
417 // around a callback to a profiler. The constructor does pre-callback
418 // work to get the tag value, klass tag value, ... and the destructor
419 // does the post-callback work of tagging or untagging the object.
420 //
421 // {
422 // CallbackWrapper wrapper(tag_map, o);
423 //
424 // (*callback)(wrapper.klass_tag(), wrapper.obj_size(), wrapper.obj_tag_p(), ...)
425 //
426 // }
427 // wrapper goes out of scope here which results in the destructor
428 // checking to see if the object has been tagged, untagged, or the
429 // tag value has changed.
430 //
431 class CallbackWrapper : public StackObj {
432 private:
433 JvmtiTagMap* _tag_map;
434 const JvmtiHeapwalkObject& _o;
435 jlong _obj_size;
436 jlong _obj_tag;
437 jlong _klass_tag;
438
439 protected:
440 JvmtiTagMap* tag_map() const { return _tag_map; }
441
442 // invoked post-callback to tag, untag, or update the tag of an object
443 void inline post_callback_tag_update(const JvmtiHeapwalkObject& o, JvmtiTagMap* tag_map, jlong obj_tag);
444
445 public:
446 CallbackWrapper(JvmtiTagMap* tag_map, const JvmtiHeapwalkObject& o)
447 : _tag_map(tag_map), _o(o)
448 {
449 assert(Thread::current()->is_VM_thread() || tag_map->is_locked(),
450 "MT unsafe or must be VM thread");
451
452 // object size
453 if (!o.is_flat()) {
454 // common case: we have oop
455 _obj_size = (jlong)o.obj()->size() * wordSize;
456 } else {
457 // flat value object, we know its InstanceKlass
458 assert(_o.inline_klass() != nullptr, "must be");
459 _obj_size = _o.inline_klass()->size() * wordSize;;
460 }
461
462 // get object tag
463 _obj_tag = _tag_map->find(_o);
464
465 // get the class and the class's tag value
466 assert(vmClasses::Class_klass()->is_mirror_instance_klass(), "Is not?");
467
468 _klass_tag = _tag_map->find(_o.klass()->java_mirror());
469 }
470
471 ~CallbackWrapper() {
472 post_callback_tag_update(_o, _tag_map, _obj_tag);
473 }
474
475 inline jlong* obj_tag_p() { return &_obj_tag; }
476 inline jlong obj_size() const { return _obj_size; }
477 inline jlong obj_tag() const { return _obj_tag; }
478 inline jlong klass_tag() const { return _klass_tag; }
479 };
480
481 // callback post-callback to tag, untag, or update the tag of an object
482 void inline CallbackWrapper::post_callback_tag_update(const JvmtiHeapwalkObject& o,
483 JvmtiTagMap* tag_map,
484 jlong obj_tag) {
485 if (obj_tag == 0) {
486 // callback has untagged the object, remove the entry if present
487 tag_map->remove(o);
488 } else {
489 // object was previously tagged or not present - the callback may have
490 // changed the tag value
491 assert(Thread::current()->is_VM_thread(), "must be VMThread");
492 tag_map->add(o, obj_tag);
493 }
494 }
495
496 // An extended CallbackWrapper used when reporting an object reference
497 // to the agent.
498 //
499 // {
500 // TwoOopCallbackWrapper wrapper(tag_map, referrer, o);
501 //
502 // (*callback)(wrapper.klass_tag(),
503 // wrapper.obj_size(),
504 // wrapper.obj_tag_p()
505 // wrapper.referrer_tag_p(), ...)
506 //
507 // }
508 // wrapper goes out of scope here which results in the destructor
509 // checking to see if the referrer object has been tagged, untagged,
510 // or the tag value has changed.
511 //
512 class TwoOopCallbackWrapper : public CallbackWrapper {
513 private:
514 const JvmtiHeapwalkObject& _referrer;
515 bool _is_reference_to_self;
516 jlong _referrer_obj_tag;
517 jlong _referrer_klass_tag;
518 jlong* _referrer_tag_p;
519
520 bool is_reference_to_self() const { return _is_reference_to_self; }
521
522 public:
523 TwoOopCallbackWrapper(JvmtiTagMap* tag_map, const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& o) :
524 CallbackWrapper(tag_map, o), _referrer(referrer)
525 {
526 // self reference needs to be handled in a special way
527 _is_reference_to_self = (referrer == o);
528
529 if (_is_reference_to_self) {
530 _referrer_klass_tag = klass_tag();
531 _referrer_tag_p = obj_tag_p();
532 } else {
533 // get object tag
534 _referrer_obj_tag = tag_map->find(_referrer);
535
536 _referrer_tag_p = &_referrer_obj_tag;
537
538 // get referrer class tag.
539 _referrer_klass_tag = tag_map->find(_referrer.klass()->java_mirror());
540 }
541 }
542
543 ~TwoOopCallbackWrapper() {
544 if (!is_reference_to_self()) {
545 post_callback_tag_update(_referrer,
546 tag_map(),
547 _referrer_obj_tag);
548 }
549 }
550
551 // address of referrer tag
552 // (for a self reference this will return the same thing as obj_tag_p())
553 inline jlong* referrer_tag_p() { return _referrer_tag_p; }
554
555 // referrer's class tag
556 inline jlong referrer_klass_tag() { return _referrer_klass_tag; }
557 };
558
559 // tag an object
560 //
561 // This function is performance critical. If many threads attempt to tag objects
562 // around the same time then it's possible that the Mutex associated with the
563 // tag map will be a hot lock.
564 void JvmtiTagMap::set_tag(jobject object, jlong tag) {
565 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
566
567 // SetTag should not post events because the JavaThread has to
568 // transition to native for the callback and this cannot stop for
569 // safepoints with the hashmap lock held.
570 check_hashmap(nullptr); /* don't collect dead objects */
571
572 // resolve the object
573 oop o = JNIHandles::resolve_non_null(object);
574 // see if the object is already tagged
575 JvmtiHeapwalkObject obj(o);
576 if (tag == 0) {
577 // remove the entry if present
578 _hashmap->remove(obj);
579 } else {
580 // if the object is already tagged or not present then we add/update
581 // the tag
582 add(obj, tag);
583 }
584 }
585
586 // get the tag for an object
587 jlong JvmtiTagMap::get_tag(jobject object) {
588 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
589
590 // GetTag should not post events because the JavaThread has to
591 // transition to native for the callback and this cannot stop for
592 // safepoints with the hashmap lock held.
593 check_hashmap(nullptr); /* don't collect dead objects */
594
595 // resolve the object
596 oop o = JNIHandles::resolve_non_null(object);
597
598 return find(o);
599 }
600
601
602 // Helper class used to describe the static or instance fields of a class.
603 // For each field it holds the field index (as defined by the JVMTI specification),
604 // the field type, and the offset.
605
606 class ClassFieldDescriptor: public CHeapObj<mtInternal> {
607 private:
608 int _field_index;
609 int _field_offset;
610 char _field_type;
611 InlineKlass* _inline_klass; // nullptr for heap object
612 LayoutKind _layout_kind;
613 public:
614 ClassFieldDescriptor(int index, const FieldStreamBase& fld) :
615 _field_index(index), _field_offset(fld.offset()), _field_type(fld.signature()->char_at(0)) {
616 if (fld.is_flat()) {
617 const fieldDescriptor& fd = fld.field_descriptor();
618 InstanceKlass* holder_klass = fd.field_holder();
619 InlineLayoutInfo* layout_info = holder_klass->inline_layout_info_adr(fd.index());
620 _inline_klass = layout_info->klass();
621 _layout_kind = layout_info->kind();
622 } else {
623 _inline_klass = nullptr;
624 _layout_kind = LayoutKind::REFERENCE;
625 }
626 }
627 int field_index() const { return _field_index; }
628 char field_type() const { return _field_type; }
629 int field_offset() const { return _field_offset; }
630 bool is_flat() const { return _inline_klass != nullptr; }
631 InlineKlass* inline_klass() const { return _inline_klass; }
632 LayoutKind layout_kind() const { return _layout_kind; }
633 };
634
635 class ClassFieldMap: public CHeapObj<mtInternal> {
636 private:
637 enum {
638 initial_field_count = 5
639 };
640
641 // list of field descriptors
642 GrowableArray<ClassFieldDescriptor*>* _fields;
643
644 // constructor
645 ClassFieldMap();
646
647 // calculates number of fields in all interfaces
648 static int interfaces_field_count(InstanceKlass* ik);
649
650 // add a field
651 void add(int index, const FieldStreamBase& fld);
652
653 public:
654 ~ClassFieldMap();
655
656 // access
657 int field_count() { return _fields->length(); }
658 ClassFieldDescriptor* field_at(int i) { return _fields->at(i); }
659
660 // functions to create maps of static or instance fields
661 static ClassFieldMap* create_map_of_static_fields(Klass* k);
662 static ClassFieldMap* create_map_of_instance_fields(Klass* k);
663 };
664
665 ClassFieldMap::ClassFieldMap() {
666 _fields = new (mtServiceability)
667 GrowableArray<ClassFieldDescriptor*>(initial_field_count, mtServiceability);
668 }
669
670 ClassFieldMap::~ClassFieldMap() {
671 for (int i=0; i<_fields->length(); i++) {
672 delete _fields->at(i);
673 }
674 delete _fields;
675 }
676
677 int ClassFieldMap::interfaces_field_count(InstanceKlass* ik) {
678 const Array<InstanceKlass*>* interfaces = ik->transitive_interfaces();
679 int count = 0;
680 for (int i = 0; i < interfaces->length(); i++) {
681 count += interfaces->at(i)->java_fields_count();
682
683 }
684 return count;
685 }
686
687 void ClassFieldMap::add(int index, const FieldStreamBase& fld) {
688 ClassFieldDescriptor* field = new ClassFieldDescriptor(index, fld);
689 _fields->append(field);
690 }
691
692 // Returns a heap allocated ClassFieldMap to describe the static fields
693 // of the given class.
694 ClassFieldMap* ClassFieldMap::create_map_of_static_fields(Klass* k) {
695 InstanceKlass* ik = InstanceKlass::cast(k);
696
697 // create the field map
698 ClassFieldMap* field_map = new ClassFieldMap();
699
700 // Static fields of interfaces and superclasses are reported as references from the interfaces/superclasses.
701 // Need to calculate start index of this class fields: number of fields in all interfaces and superclasses.
702 int index = interfaces_field_count(ik);
703 for (InstanceKlass* super_klass = ik->super(); super_klass != nullptr; super_klass = super_klass->super()) {
704 index += super_klass->java_fields_count();
705 }
706
707 for (JavaFieldStream fld(ik); !fld.done(); fld.next(), index++) {
708 // ignore instance fields
709 if (!fld.access_flags().is_static()) {
710 continue;
711 }
712 field_map->add(index, fld);
713 }
714
715 return field_map;
716 }
717
718 // Returns a heap allocated ClassFieldMap to describe the instance fields
719 // of the given class. All instance fields are included (this means public
720 // and private fields declared in superclasses too).
721 ClassFieldMap* ClassFieldMap::create_map_of_instance_fields(Klass* k) {
722 InstanceKlass* ik = InstanceKlass::cast(k);
723
724 // create the field map
725 ClassFieldMap* field_map = new ClassFieldMap();
726
727 // fields of the superclasses are reported first, so need to know total field number to calculate field indices
728 int total_field_number = interfaces_field_count(ik);
729 for (InstanceKlass* klass = ik; klass != nullptr; klass = klass->super()) {
730 total_field_number += klass->java_fields_count();
731 }
732
733 for (InstanceKlass* klass = ik; klass != nullptr; klass = klass->super()) {
734 JavaFieldStream fld(klass);
735 int start_index = total_field_number - klass->java_fields_count();
736 for (int index = 0; !fld.done(); fld.next(), index++) {
737 // ignore static fields
738 if (fld.access_flags().is_static()) {
739 continue;
740 }
741 field_map->add(start_index + index, fld);
742 }
743 // update total_field_number for superclass (decrease by the field count in the current class)
744 total_field_number = start_index;
745 }
746
747 return field_map;
748 }
749
750 // Helper class used to cache a ClassFileMap for the instance fields of
751 // a cache. A JvmtiCachedClassFieldMap can be cached by an InstanceKlass during
752 // heap iteration and avoid creating a field map for each object in the heap
753 // (only need to create the map when the first instance of a class is encountered).
754 //
755 class JvmtiCachedClassFieldMap : public CHeapObj<mtInternal> {
756 private:
757 enum {
758 initial_class_count = 200
759 };
760 ClassFieldMap* _field_map;
761
762 ClassFieldMap* field_map() const { return _field_map; }
763
764 JvmtiCachedClassFieldMap(ClassFieldMap* field_map);
765 ~JvmtiCachedClassFieldMap();
766
767 static GrowableArray<InstanceKlass*>* _class_list;
768 static void add_to_class_list(InstanceKlass* ik);
769
770 public:
771 // returns the field map for a given klass (returning map cached
772 // by InstanceKlass if possible
773 static ClassFieldMap* get_map_of_instance_fields(Klass* k);
774
775 // removes the field map from all instanceKlasses - should be
776 // called before VM operation completes
777 static void clear_cache();
778
779 // returns the number of ClassFieldMap cached by instanceKlasses
780 static int cached_field_map_count();
781 };
782
783 GrowableArray<InstanceKlass*>* JvmtiCachedClassFieldMap::_class_list;
784
785 JvmtiCachedClassFieldMap::JvmtiCachedClassFieldMap(ClassFieldMap* field_map) {
786 _field_map = field_map;
787 }
788
789 JvmtiCachedClassFieldMap::~JvmtiCachedClassFieldMap() {
790 if (_field_map != nullptr) {
791 delete _field_map;
792 }
793 }
794
795 // Marker class to ensure that the class file map cache is only used in a defined
796 // scope.
797 class ClassFieldMapCacheMark : public StackObj {
798 private:
799 static bool _is_active;
800 public:
801 ClassFieldMapCacheMark() {
802 assert(Thread::current()->is_VM_thread(), "must be VMThread");
803 assert(JvmtiCachedClassFieldMap::cached_field_map_count() == 0, "cache not empty");
804 assert(!_is_active, "ClassFieldMapCacheMark cannot be nested");
805 _is_active = true;
806 }
807 ~ClassFieldMapCacheMark() {
808 JvmtiCachedClassFieldMap::clear_cache();
809 _is_active = false;
810 }
811 static bool is_active() { return _is_active; }
812 };
813
814 bool ClassFieldMapCacheMark::_is_active;
815
816 // record that the given InstanceKlass is caching a field map
817 void JvmtiCachedClassFieldMap::add_to_class_list(InstanceKlass* ik) {
818 if (_class_list == nullptr) {
819 _class_list = new (mtServiceability)
820 GrowableArray<InstanceKlass*>(initial_class_count, mtServiceability);
821 }
822 _class_list->push(ik);
823 }
824
825 // returns the instance field map for the given klass
826 // (returns field map cached by the InstanceKlass if possible)
827 ClassFieldMap* JvmtiCachedClassFieldMap::get_map_of_instance_fields(Klass *k) {
828 assert(Thread::current()->is_VM_thread(), "must be VMThread");
829 assert(ClassFieldMapCacheMark::is_active(), "ClassFieldMapCacheMark not active");
830
831 InstanceKlass* ik = InstanceKlass::cast(k);
832
833 // return cached map if possible
834 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
835 if (cached_map != nullptr) {
836 assert(cached_map->field_map() != nullptr, "missing field list");
837 return cached_map->field_map();
838 } else {
839 ClassFieldMap* field_map = ClassFieldMap::create_map_of_instance_fields(k);
840 cached_map = new JvmtiCachedClassFieldMap(field_map);
841 ik->set_jvmti_cached_class_field_map(cached_map);
842 add_to_class_list(ik);
843 return field_map;
844 }
845 }
846
847 // remove the fields maps cached from all instanceKlasses
848 void JvmtiCachedClassFieldMap::clear_cache() {
849 assert(Thread::current()->is_VM_thread(), "must be VMThread");
850 if (_class_list != nullptr) {
851 for (int i = 0; i < _class_list->length(); i++) {
852 InstanceKlass* ik = _class_list->at(i);
853 JvmtiCachedClassFieldMap* cached_map = ik->jvmti_cached_class_field_map();
854 assert(cached_map != nullptr, "should not be null");
855 ik->set_jvmti_cached_class_field_map(nullptr);
856 delete cached_map; // deletes the encapsulated field map
857 }
858 delete _class_list;
859 _class_list = nullptr;
860 }
861 }
862
863 // returns the number of ClassFieldMap cached by instanceKlasses
864 int JvmtiCachedClassFieldMap::cached_field_map_count() {
865 return (_class_list == nullptr) ? 0 : _class_list->length();
866 }
867
868 // helper function to indicate if an object is filtered by its tag or class tag
869 static inline bool is_filtered_by_heap_filter(jlong obj_tag,
870 jlong klass_tag,
871 int heap_filter) {
872 // apply the heap filter
873 if (obj_tag != 0) {
874 // filter out tagged objects
875 if (heap_filter & JVMTI_HEAP_FILTER_TAGGED) return true;
876 } else {
877 // filter out untagged objects
878 if (heap_filter & JVMTI_HEAP_FILTER_UNTAGGED) return true;
879 }
880 if (klass_tag != 0) {
881 // filter out objects with tagged classes
882 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_TAGGED) return true;
883 } else {
884 // filter out objects with untagged classes.
885 if (heap_filter & JVMTI_HEAP_FILTER_CLASS_UNTAGGED) return true;
886 }
887 return false;
888 }
889
890 // helper function to indicate if an object is filtered by a klass filter
891 static inline bool is_filtered_by_klass_filter(const JvmtiHeapwalkObject& obj, Klass* klass_filter) {
892 if (klass_filter != nullptr) {
893 if (obj.klass() != klass_filter) {
894 return true;
895 }
896 }
897 return false;
898 }
899
900 // helper function to tell if a field is a primitive field or not
901 static inline bool is_primitive_field_type(char type) {
902 return (type != JVM_SIGNATURE_CLASS && type != JVM_SIGNATURE_ARRAY);
903 }
904
905 // helper function to copy the value from location addr to jvalue.
906 static inline void copy_to_jvalue(jvalue *v, address addr, jvmtiPrimitiveType value_type) {
907 switch (value_type) {
908 case JVMTI_PRIMITIVE_TYPE_BOOLEAN : { v->z = *(jboolean*)addr; break; }
909 case JVMTI_PRIMITIVE_TYPE_BYTE : { v->b = *(jbyte*)addr; break; }
910 case JVMTI_PRIMITIVE_TYPE_CHAR : { v->c = *(jchar*)addr; break; }
911 case JVMTI_PRIMITIVE_TYPE_SHORT : { v->s = *(jshort*)addr; break; }
912 case JVMTI_PRIMITIVE_TYPE_INT : { v->i = *(jint*)addr; break; }
913 case JVMTI_PRIMITIVE_TYPE_LONG : { v->j = *(jlong*)addr; break; }
914 case JVMTI_PRIMITIVE_TYPE_FLOAT : { v->f = *(jfloat*)addr; break; }
915 case JVMTI_PRIMITIVE_TYPE_DOUBLE : { v->d = *(jdouble*)addr; break; }
916 default: ShouldNotReachHere();
917 }
918 }
919
920 // helper function to invoke string primitive value callback
921 // returns visit control flags
922 static jint invoke_string_value_callback(jvmtiStringPrimitiveValueCallback cb,
923 CallbackWrapper* wrapper,
924 const JvmtiHeapwalkObject& obj,
925 void* user_data)
926 {
927 assert(!obj.is_flat(), "cannot be flat");
928 oop str = obj.obj();
929 assert(str->klass() == vmClasses::String_klass(), "not a string");
930
931 typeArrayOop s_value = java_lang_String::value(str);
932
933 // JDK-6584008: the value field may be null if a String instance is
934 // partially constructed.
935 if (s_value == nullptr) {
936 return 0;
937 }
938 // get the string value and length
939 // (string value may be offset from the base)
940 int s_len = java_lang_String::length(str);
941 bool is_latin1 = java_lang_String::is_latin1(str);
942 jchar* value;
943 if (s_len > 0) {
944 if (!is_latin1) {
945 value = s_value->char_at_addr(0);
946 } else {
947 // Inflate latin1 encoded string to UTF16
948 jchar* buf = NEW_C_HEAP_ARRAY(jchar, s_len, mtInternal);
949 for (int i = 0; i < s_len; i++) {
950 buf[i] = ((jchar) s_value->byte_at(i)) & 0xff;
951 }
952 value = &buf[0];
953 }
954 } else {
955 // Don't use char_at_addr(0) if length is 0
956 value = (jchar*) s_value->base(T_CHAR);
957 }
958
959 // invoke the callback
960 jint res = (*cb)(wrapper->klass_tag(),
961 wrapper->obj_size(),
962 wrapper->obj_tag_p(),
963 value,
964 (jint)s_len,
965 user_data);
966
967 if (is_latin1 && s_len > 0) {
968 FREE_C_HEAP_ARRAY(jchar, value);
969 }
970 return res;
971 }
972
973 // helper function to invoke string primitive value callback
974 // returns visit control flags
975 static jint invoke_array_primitive_value_callback(jvmtiArrayPrimitiveValueCallback cb,
976 CallbackWrapper* wrapper,
977 const JvmtiHeapwalkObject& obj,
978 void* user_data)
979 {
980 assert(!obj.is_flat(), "cannot be flat");
981 assert(obj.obj()->is_typeArray(), "not a primitive array");
982
983 // get base address of first element
984 typeArrayOop array = typeArrayOop(obj.obj());
985 BasicType type = TypeArrayKlass::cast(array->klass())->element_type();
986 void* elements = array->base(type);
987
988 // jvmtiPrimitiveType is defined so this mapping is always correct
989 jvmtiPrimitiveType elem_type = (jvmtiPrimitiveType)type2char(type);
990
991 return (*cb)(wrapper->klass_tag(),
992 wrapper->obj_size(),
993 wrapper->obj_tag_p(),
994 (jint)array->length(),
995 elem_type,
996 elements,
997 user_data);
998 }
999
1000 // helper function to invoke the primitive field callback for all static fields
1001 // of a given class
1002 static jint invoke_primitive_field_callback_for_static_fields
1003 (CallbackWrapper* wrapper,
1004 oop obj,
1005 jvmtiPrimitiveFieldCallback cb,
1006 void* user_data)
1007 {
1008 // for static fields only the index will be set
1009 static jvmtiHeapReferenceInfo reference_info = { 0 };
1010
1011 assert(obj->klass() == vmClasses::Class_klass(), "not a class");
1012 if (java_lang_Class::is_primitive(obj)) {
1013 return 0;
1014 }
1015 Klass* klass = java_lang_Class::as_Klass(obj);
1016
1017 // ignore classes for object and type arrays
1018 if (!klass->is_instance_klass()) {
1019 return 0;
1020 }
1021
1022 // ignore classes which aren't linked yet
1023 InstanceKlass* ik = InstanceKlass::cast(klass);
1024 if (!ik->is_linked()) {
1025 return 0;
1026 }
1027
1028 // get the field map
1029 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
1030
1031 // invoke the callback for each static primitive field
1032 for (int i=0; i<field_map->field_count(); i++) {
1033 ClassFieldDescriptor* field = field_map->field_at(i);
1034
1035 // ignore non-primitive fields
1036 char type = field->field_type();
1037 if (!is_primitive_field_type(type)) {
1038 continue;
1039 }
1040 // one-to-one mapping
1041 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1042
1043 // get offset and field value
1044 int offset = field->field_offset();
1045 address addr = cast_from_oop<address>(klass->java_mirror()) + offset;
1046 jvalue value;
1047 copy_to_jvalue(&value, addr, value_type);
1048
1049 // field index
1050 reference_info.field.index = field->field_index();
1051
1052 // invoke the callback
1053 jint res = (*cb)(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
1054 &reference_info,
1055 wrapper->klass_tag(),
1056 wrapper->obj_tag_p(),
1057 value,
1058 value_type,
1059 user_data);
1060 if (res & JVMTI_VISIT_ABORT) {
1061 delete field_map;
1062 return res;
1063 }
1064 }
1065
1066 delete field_map;
1067 return 0;
1068 }
1069
1070 // helper function to invoke the primitive field callback for all instance fields
1071 // of a given object
1072 static jint invoke_primitive_field_callback_for_instance_fields(
1073 CallbackWrapper* wrapper,
1074 const JvmtiHeapwalkObject& obj,
1075 jvmtiPrimitiveFieldCallback cb,
1076 void* user_data)
1077 {
1078 // for instance fields only the index will be set
1079 static jvmtiHeapReferenceInfo reference_info = { 0 };
1080
1081 // get the map of the instance fields
1082 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj.klass());
1083
1084 // invoke the callback for each instance primitive field
1085 for (int i=0; i<fields->field_count(); i++) {
1086 ClassFieldDescriptor* field = fields->field_at(i);
1087
1088 // ignore non-primitive fields
1089 char type = field->field_type();
1090 if (!is_primitive_field_type(type)) {
1091 continue;
1092 }
1093 // one-to-one mapping
1094 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
1095
1096 // get field value
1097 address addr = cast_from_oop<address>(obj.obj()) + obj.offset() + field->field_offset();
1098 jvalue value;
1099 copy_to_jvalue(&value, addr, value_type);
1100
1101 // field index
1102 reference_info.field.index = field->field_index();
1103
1104 // invoke the callback
1105 jint res = (*cb)(JVMTI_HEAP_REFERENCE_FIELD,
1106 &reference_info,
1107 wrapper->klass_tag(),
1108 wrapper->obj_tag_p(),
1109 value,
1110 value_type,
1111 user_data);
1112 if (res & JVMTI_VISIT_ABORT) {
1113 return res;
1114 }
1115 }
1116 return 0;
1117 }
1118
1119
1120 // VM operation to iterate over all objects in the heap (both reachable
1121 // and unreachable)
1122 class VM_HeapIterateOperation: public VM_Operation {
1123 private:
1124 ObjectClosure* _blk;
1125 GrowableArray<jlong>* const _dead_objects;
1126 public:
1127 VM_HeapIterateOperation(ObjectClosure* blk, GrowableArray<jlong>* objects) :
1128 _blk(blk), _dead_objects(objects) { }
1129
1130 VMOp_Type type() const { return VMOp_HeapIterateOperation; }
1131 void doit() {
1132 // allows class files maps to be cached during iteration
1133 ClassFieldMapCacheMark cm;
1134
1135 JvmtiTagMap::check_hashmaps_for_heapwalk(_dead_objects);
1136
1137 // make sure that heap is parsable (fills TLABs with filler objects)
1138 Universe::heap()->ensure_parsability(false); // no need to retire TLABs
1139
1140 // Verify heap before iteration - if the heap gets corrupted then
1141 // JVMTI's IterateOverHeap will crash.
1142 if (VerifyBeforeIteration) {
1143 Universe::verify();
1144 }
1145
1146 // do the iteration
1147 Universe::heap()->object_iterate(_blk);
1148 }
1149 };
1150
1151
1152 // An ObjectClosure used to support the deprecated IterateOverHeap and
1153 // IterateOverInstancesOfClass functions
1154 class IterateOverHeapObjectClosure: public ObjectClosure {
1155 private:
1156 JvmtiTagMap* _tag_map;
1157 Klass* _klass;
1158 jvmtiHeapObjectFilter _object_filter;
1159 jvmtiHeapObjectCallback _heap_object_callback;
1160 const void* _user_data;
1161
1162 // accessors
1163 JvmtiTagMap* tag_map() const { return _tag_map; }
1164 jvmtiHeapObjectFilter object_filter() const { return _object_filter; }
1165 jvmtiHeapObjectCallback object_callback() const { return _heap_object_callback; }
1166 Klass* klass() const { return _klass; }
1167 const void* user_data() const { return _user_data; }
1168
1169 // indicates if iteration has been aborted
1170 bool _iteration_aborted;
1171 bool is_iteration_aborted() const { return _iteration_aborted; }
1172 void set_iteration_aborted(bool aborted) { _iteration_aborted = aborted; }
1173
1174 public:
1175 IterateOverHeapObjectClosure(JvmtiTagMap* tag_map,
1176 Klass* klass,
1177 jvmtiHeapObjectFilter object_filter,
1178 jvmtiHeapObjectCallback heap_object_callback,
1179 const void* user_data) :
1180 _tag_map(tag_map),
1181 _klass(klass),
1182 _object_filter(object_filter),
1183 _heap_object_callback(heap_object_callback),
1184 _user_data(user_data),
1185 _iteration_aborted(false)
1186 {
1187 }
1188
1189 void do_object(oop o);
1190 };
1191
1192 // invoked for each object in the heap
1193 void IterateOverHeapObjectClosure::do_object(oop o) {
1194 assert(o != nullptr, "Heap iteration should never produce null!");
1195 // check if iteration has been halted
1196 if (is_iteration_aborted()) return;
1197
1198 // instanceof check when filtering by klass
1199 if (klass() != nullptr && !o->is_a(klass())) {
1200 return;
1201 }
1202
1203 // skip if object is a dormant shared object whose mirror hasn't been loaded
1204 if (o->klass()->java_mirror() == nullptr) {
1205 log_debug(aot, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s)", p2i(o),
1206 o->klass()->external_name());
1207 return;
1208 }
1209
1210 // prepare for the calllback
1211 JvmtiHeapwalkObject wrapper_obj(o);
1212 CallbackWrapper wrapper(tag_map(), wrapper_obj);
1213
1214 // if the object is tagged and we're only interested in untagged objects
1215 // then don't invoke the callback. Similarly, if the object is untagged
1216 // and we're only interested in tagged objects we skip the callback.
1217 if (wrapper.obj_tag() != 0) {
1218 if (object_filter() == JVMTI_HEAP_OBJECT_UNTAGGED) return;
1219 } else {
1220 if (object_filter() == JVMTI_HEAP_OBJECT_TAGGED) return;
1221 }
1222
1223 // invoke the agent's callback
1224 jvmtiIterationControl control = (*object_callback())(wrapper.klass_tag(),
1225 wrapper.obj_size(),
1226 wrapper.obj_tag_p(),
1227 (void*)user_data());
1228 if (control == JVMTI_ITERATION_ABORT) {
1229 set_iteration_aborted(true);
1230 }
1231 }
1232
1233 // An ObjectClosure used to support the IterateThroughHeap function
1234 class IterateThroughHeapObjectClosure: public ObjectClosure {
1235 private:
1236 JvmtiTagMap* _tag_map;
1237 Klass* _klass;
1238 int _heap_filter;
1239 const jvmtiHeapCallbacks* _callbacks;
1240 const void* _user_data;
1241
1242 // accessor functions
1243 JvmtiTagMap* tag_map() const { return _tag_map; }
1244 int heap_filter() const { return _heap_filter; }
1245 const jvmtiHeapCallbacks* callbacks() const { return _callbacks; }
1246 Klass* klass() const { return _klass; }
1247 const void* user_data() const { return _user_data; }
1248
1249 // indicates if the iteration has been aborted
1250 bool _iteration_aborted;
1251 bool is_iteration_aborted() const { return _iteration_aborted; }
1252
1253 // used to check the visit control flags. If the abort flag is set
1254 // then we set the iteration aborted flag so that the iteration completes
1255 // without processing any further objects
1256 bool check_flags_for_abort(jint flags) {
1257 bool is_abort = (flags & JVMTI_VISIT_ABORT) != 0;
1258 if (is_abort) {
1259 _iteration_aborted = true;
1260 }
1261 return is_abort;
1262 }
1263
1264 void visit_object(const JvmtiHeapwalkObject& obj);
1265 void visit_flat_fields(const JvmtiHeapwalkObject& obj);
1266 void visit_flat_array_elements(const JvmtiHeapwalkObject& obj);
1267
1268 public:
1269 IterateThroughHeapObjectClosure(JvmtiTagMap* tag_map,
1270 Klass* klass,
1271 int heap_filter,
1272 const jvmtiHeapCallbacks* heap_callbacks,
1273 const void* user_data) :
1274 _tag_map(tag_map),
1275 _klass(klass),
1276 _heap_filter(heap_filter),
1277 _callbacks(heap_callbacks),
1278 _user_data(user_data),
1279 _iteration_aborted(false)
1280 {
1281 }
1282
1283 void do_object(oop obj);
1284 };
1285
1286 // invoked for each object in the heap
1287 void IterateThroughHeapObjectClosure::do_object(oop obj) {
1288 assert(obj != nullptr, "Heap iteration should never produce null!");
1289 // check if iteration has been halted
1290 if (is_iteration_aborted()) return;
1291
1292 // skip if object is a dormant shared object whose mirror hasn't been loaded
1293 if (obj != nullptr && obj->klass()->java_mirror() == nullptr) {
1294 log_debug(aot, heap)("skipped dormant archived object " INTPTR_FORMAT " (%s)", p2i(obj),
1295 obj->klass()->external_name());
1296 return;
1297 }
1298
1299 visit_object(obj);
1300 }
1301
1302 void IterateThroughHeapObjectClosure::visit_object(const JvmtiHeapwalkObject& obj) {
1303 // apply class filter
1304 if (is_filtered_by_klass_filter(obj, klass())) return;
1305
1306 // prepare for callback
1307 CallbackWrapper wrapper(tag_map(), obj);
1308
1309 // check if filtered by the heap filter
1310 if (is_filtered_by_heap_filter(wrapper.obj_tag(), wrapper.klass_tag(), heap_filter())) {
1311 return;
1312 }
1313
1314 // for arrays we need the length, otherwise -1
1315 bool is_array = obj.klass()->is_array_klass();
1316 int len = is_array ? arrayOop(obj.obj())->length() : -1;
1317
1318 // invoke the object callback (if callback is provided)
1319 if (callbacks()->heap_iteration_callback != nullptr) {
1320 jvmtiHeapIterationCallback cb = callbacks()->heap_iteration_callback;
1321 jint res = (*cb)(wrapper.klass_tag(),
1322 wrapper.obj_size(),
1323 wrapper.obj_tag_p(),
1324 (jint)len,
1325 (void*)user_data());
1326 if (check_flags_for_abort(res)) return;
1327 }
1328
1329 // for objects and classes we report primitive fields if callback provided
1330 if (callbacks()->primitive_field_callback != nullptr && obj.klass()->is_instance_klass()) {
1331 jint res;
1332 jvmtiPrimitiveFieldCallback cb = callbacks()->primitive_field_callback;
1333 if (obj.klass() == vmClasses::Class_klass()) {
1334 assert(!obj.is_flat(), "Class object cannot be flattened");
1335 res = invoke_primitive_field_callback_for_static_fields(&wrapper,
1336 obj.obj(),
1337 cb,
1338 (void*)user_data());
1339 } else {
1340 res = invoke_primitive_field_callback_for_instance_fields(&wrapper,
1341 obj,
1342 cb,
1343 (void*)user_data());
1344 }
1345 if (check_flags_for_abort(res)) return;
1346 }
1347
1348 // string callback
1349 if (!is_array &&
1350 callbacks()->string_primitive_value_callback != nullptr &&
1351 obj.klass() == vmClasses::String_klass()) {
1352 jint res = invoke_string_value_callback(
1353 callbacks()->string_primitive_value_callback,
1354 &wrapper,
1355 obj,
1356 (void*)user_data());
1357 if (check_flags_for_abort(res)) return;
1358 }
1359
1360 // array callback
1361 if (is_array &&
1362 callbacks()->array_primitive_value_callback != nullptr &&
1363 obj.klass()->is_typeArray_klass()) {
1364 jint res = invoke_array_primitive_value_callback(
1365 callbacks()->array_primitive_value_callback,
1366 &wrapper,
1367 obj,
1368 (void*)user_data());
1369 if (check_flags_for_abort(res)) return;
1370 }
1371
1372 // All info for the object is reported.
1373
1374 // If the object has flat fields, report them as heap objects.
1375 if (obj.klass()->is_instance_klass()) {
1376 if (InstanceKlass::cast(obj.klass())->has_inlined_fields()) {
1377 visit_flat_fields(obj);
1378 // check if iteration has been halted
1379 if (is_iteration_aborted()) {
1380 return;
1381 }
1382 }
1383 }
1384 // If the object is flat array, report all elements as heap objects.
1385 if (is_array && obj.obj()->is_flatArray()) {
1386 assert(!obj.is_flat(), "Array object cannot be flattened");
1387 visit_flat_array_elements(obj);
1388 }
1389 }
1390
1391 void IterateThroughHeapObjectClosure::visit_flat_fields(const JvmtiHeapwalkObject& obj) {
1392 // iterate over instance fields
1393 ClassFieldMap* fields = JvmtiCachedClassFieldMap::get_map_of_instance_fields(obj.klass());
1394 for (int i = 0; i < fields->field_count(); i++) {
1395 ClassFieldDescriptor* field = fields->field_at(i);
1396 // skip non-flat and (for safety) primitive fields
1397 if (!field->is_flat() || is_primitive_field_type(field->field_type())) {
1398 continue;
1399 }
1400
1401 int field_offset = field->field_offset();
1402 if (obj.is_flat()) {
1403 // the object is inlined, its fields are stored without the header
1404 field_offset += obj.offset() - obj.inline_klass()->payload_offset();
1405 }
1406 // check for possible nulls
1407 if (LayoutKindHelper::is_nullable_flat(field->layout_kind())) {
1408 address payload = cast_from_oop<address>(obj.obj()) + field_offset;
1409 if (field->inline_klass()->is_payload_marked_as_null(payload)) {
1410 continue;
1411 }
1412 }
1413 JvmtiHeapwalkObject field_obj(obj.obj(), field_offset, field->inline_klass(), field->layout_kind());
1414
1415 visit_object(field_obj);
1416
1417 // check if iteration has been halted
1418 if (is_iteration_aborted()) {
1419 return;
1420 }
1421 }
1422 }
1423
1424 void IterateThroughHeapObjectClosure::visit_flat_array_elements(const JvmtiHeapwalkObject& obj) {
1425 assert(!obj.is_flat() && obj.obj()->is_flatArray() , "sanity check");
1426 flatArrayOop array = flatArrayOop(obj.obj());
1427 FlatArrayKlass* faklass = FlatArrayKlass::cast(array->klass());
1428 InlineKlass* vk = InlineKlass::cast(faklass->element_klass());
1429 bool need_null_check = LayoutKindHelper::is_nullable_flat(faklass->layout_kind());
1430
1431 for (int index = 0; index < array->length(); index++) {
1432 address addr = (address)array->value_at_addr(index, faklass->layout_helper());
1433 // check for null
1434 if (need_null_check) {
1435 if (vk->is_payload_marked_as_null(addr)) {
1436 continue;
1437 }
1438 }
1439
1440 // offset in the array oop
1441 int offset = (int)(addr - cast_from_oop<address>(array));
1442 JvmtiHeapwalkObject elem(obj.obj(), offset, vk, faklass->layout_kind());
1443
1444 visit_object(elem);
1445
1446 // check if iteration has been halted
1447 if (is_iteration_aborted()) {
1448 return;
1449 }
1450 }
1451 }
1452
1453 // Deprecated function to iterate over all objects in the heap
1454 void JvmtiTagMap::iterate_over_heap(jvmtiHeapObjectFilter object_filter,
1455 Klass* klass,
1456 jvmtiHeapObjectCallback heap_object_callback,
1457 const void* user_data)
1458 {
1459 // EA based optimizations on tagged objects are already reverted.
1460 EscapeBarrier eb(object_filter == JVMTI_HEAP_OBJECT_UNTAGGED ||
1461 object_filter == JVMTI_HEAP_OBJECT_EITHER,
1462 JavaThread::current());
1463 eb.deoptimize_objects_all_threads();
1464 Arena dead_object_arena(mtServiceability);
1465 GrowableArray <jlong> dead_objects(&dead_object_arena, 10, 0, 0);
1466 {
1467 MutexLocker ml(Heap_lock);
1468 IterateOverHeapObjectClosure blk(this,
1469 klass,
1470 object_filter,
1471 heap_object_callback,
1472 user_data);
1473 VM_HeapIterateOperation op(&blk, &dead_objects);
1474 VMThread::execute(&op);
1475 }
1476 convert_flat_object_entries();
1477
1478 // Post events outside of Heap_lock
1479 post_dead_objects(&dead_objects);
1480 }
1481
1482
1483 // Iterates over all objects in the heap
1484 void JvmtiTagMap::iterate_through_heap(jint heap_filter,
1485 Klass* klass,
1486 const jvmtiHeapCallbacks* callbacks,
1487 const void* user_data)
1488 {
1489 // EA based optimizations on tagged objects are already reverted.
1490 EscapeBarrier eb(!(heap_filter & JVMTI_HEAP_FILTER_UNTAGGED), JavaThread::current());
1491 eb.deoptimize_objects_all_threads();
1492
1493 Arena dead_object_arena(mtServiceability);
1494 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
1495 {
1496 MutexLocker ml(Heap_lock);
1497 IterateThroughHeapObjectClosure blk(this,
1498 klass,
1499 heap_filter,
1500 callbacks,
1501 user_data);
1502 VM_HeapIterateOperation op(&blk, &dead_objects);
1503 VMThread::execute(&op);
1504 }
1505 convert_flat_object_entries();
1506
1507 // Post events outside of Heap_lock
1508 post_dead_objects(&dead_objects);
1509 }
1510
1511 void JvmtiTagMap::remove_dead_entries_locked(GrowableArray<jlong>* objects) {
1512 assert(is_locked(), "precondition");
1513 if (_needs_cleaning) {
1514 // Recheck whether to post object free events under the lock.
1515 if (!env()->is_enabled(JVMTI_EVENT_OBJECT_FREE)) {
1516 objects = nullptr;
1517 }
1518 log_info(jvmti, table)("TagMap table needs cleaning%s",
1519 ((objects != nullptr) ? " and posting" : ""));
1520 _hashmap->remove_dead_entries(objects);
1521 _needs_cleaning = false;
1522 }
1523 }
1524
1525 void JvmtiTagMap::remove_dead_entries(GrowableArray<jlong>* objects) {
1526 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1527 remove_dead_entries_locked(objects);
1528 }
1529
1530 void JvmtiTagMap::post_dead_objects(GrowableArray<jlong>* const objects) {
1531 assert(Thread::current()->is_Java_thread(), "Must post from JavaThread");
1532 if (objects != nullptr && objects->length() > 0) {
1533 JvmtiExport::post_object_free(env(), objects);
1534 log_info(jvmti, table)("%d free object posted", objects->length());
1535 }
1536 }
1537
1538 void JvmtiTagMap::remove_and_post_dead_objects() {
1539 ResourceMark rm;
1540 GrowableArray<jlong> objects;
1541 remove_dead_entries(&objects);
1542 post_dead_objects(&objects);
1543 }
1544
1545 void JvmtiTagMap::flush_object_free_events() {
1546 assert_not_at_safepoint();
1547 if (env()->is_enabled(JVMTI_EVENT_OBJECT_FREE)) {
1548 {
1549 // The other thread can block for safepoints during event callbacks, so ensure we
1550 // are safepoint-safe while waiting.
1551 ThreadBlockInVM tbivm(JavaThread::current());
1552 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1553 while (_posting_events) {
1554 ml.wait();
1555 }
1556
1557 if (!_needs_cleaning || is_empty()) {
1558 _needs_cleaning = false;
1559 return;
1560 }
1561 _posting_events = true;
1562 } // Drop the lock so we can do the cleaning on the VM thread.
1563 // Needs both cleaning and event posting (up to some other thread
1564 // getting there first after we dropped the lock).
1565 remove_and_post_dead_objects();
1566 {
1567 MonitorLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1568 _posting_events = false;
1569 ml.notify_all();
1570 }
1571 } else {
1572 remove_dead_entries(nullptr);
1573 }
1574 }
1575
1576 // support class for get_objects_with_tags
1577
1578 class TagObjectCollector : public JvmtiTagMapKeyClosure {
1579 private:
1580 JvmtiEnv* _env;
1581 JavaThread* _thread;
1582 jlong* _tags;
1583 jint _tag_count;
1584 bool _some_dead_found;
1585
1586 GrowableArray<jobject>* _object_results; // collected objects (JNI weak refs)
1587 GrowableArray<uint64_t>* _tag_results; // collected tags
1588
1589 public:
1590 TagObjectCollector(JvmtiEnv* env, const jlong* tags, jint tag_count) :
1591 _env(env),
1592 _thread(JavaThread::current()),
1593 _tags((jlong*)tags),
1594 _tag_count(tag_count),
1595 _some_dead_found(false),
1596 _object_results(new (mtServiceability) GrowableArray<jobject>(1, mtServiceability)),
1597 _tag_results(new (mtServiceability) GrowableArray<uint64_t>(1, mtServiceability)) { }
1598
1599 ~TagObjectCollector() {
1600 delete _object_results;
1601 delete _tag_results;
1602 }
1603
1604 bool some_dead_found() const { return _some_dead_found; }
1605
1606 // for each tagged object check if the tag value matches
1607 // - if it matches then we create a JNI local reference to the object
1608 // and record the reference and tag value.
1609 // Always return true so the iteration continues.
1610 bool do_entry(JvmtiTagMapKey& key, jlong& value) {
1611 for (int i = 0; i < _tag_count; i++) {
1612 if (_tags[i] == value) {
1613 // The reference in this tag map could be the only (implicitly weak)
1614 // reference to that object. If we hand it out, we need to keep it live wrt
1615 // SATB marking similar to other j.l.ref.Reference referents. This is
1616 // achieved by using a phantom load in the object() accessor.
1617 oop o = key.object();
1618 if (o == nullptr) {
1619 _some_dead_found = true;
1620 // skip this whole entry
1621 return true;
1622 }
1623 assert(o != nullptr && Universe::heap()->is_in(o), "sanity check");
1624 jobject ref = JNIHandles::make_local(_thread, o);
1625 _object_results->append(ref);
1626 _tag_results->append(value);
1627 }
1628 }
1629 return true;
1630 }
1631
1632 // return the results from the collection
1633 //
1634 jvmtiError result(jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1635 jvmtiError error;
1636 int count = _object_results->length();
1637 assert(count >= 0, "sanity check");
1638
1639 // if object_result_ptr is not null then allocate the result and copy
1640 // in the object references.
1641 if (object_result_ptr != nullptr) {
1642 error = _env->Allocate(count * sizeof(jobject), (unsigned char**)object_result_ptr);
1643 if (error != JVMTI_ERROR_NONE) {
1644 return error;
1645 }
1646 for (int i=0; i<count; i++) {
1647 (*object_result_ptr)[i] = _object_results->at(i);
1648 }
1649 }
1650
1651 // if tag_result_ptr is not null then allocate the result and copy
1652 // in the tag values.
1653 if (tag_result_ptr != nullptr) {
1654 error = _env->Allocate(count * sizeof(jlong), (unsigned char**)tag_result_ptr);
1655 if (error != JVMTI_ERROR_NONE) {
1656 if (object_result_ptr != nullptr) {
1657 _env->Deallocate((unsigned char*)object_result_ptr);
1658 }
1659 return error;
1660 }
1661 for (int i=0; i<count; i++) {
1662 (*tag_result_ptr)[i] = (jlong)_tag_results->at(i);
1663 }
1664 }
1665
1666 *count_ptr = count;
1667 return JVMTI_ERROR_NONE;
1668 }
1669 };
1670
1671 // return the list of objects with the specified tags
1672 jvmtiError JvmtiTagMap::get_objects_with_tags(const jlong* tags,
1673 jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr) {
1674
1675 // ensure flat object conversion is completed
1676 convert_flat_object_entries();
1677
1678 TagObjectCollector collector(env(), tags, count);
1679 {
1680 // iterate over all tagged objects
1681 MutexLocker ml(lock(), Mutex::_no_safepoint_check_flag);
1682 // Can't post ObjectFree events here from a JavaThread, so this
1683 // will race with the gc_notification thread in the tiny
1684 // window where the object is not marked but hasn't been notified that
1685 // it is collected yet.
1686 _hashmap->entry_iterate(&collector);
1687 }
1688 return collector.result(count_ptr, object_result_ptr, tag_result_ptr);
1689 }
1690
1691 // helper to map a jvmtiHeapReferenceKind to an old style jvmtiHeapRootKind
1692 // (not performance critical as only used for roots)
1693 static jvmtiHeapRootKind toJvmtiHeapRootKind(jvmtiHeapReferenceKind kind) {
1694 switch (kind) {
1695 case JVMTI_HEAP_REFERENCE_JNI_GLOBAL: return JVMTI_HEAP_ROOT_JNI_GLOBAL;
1696 case JVMTI_HEAP_REFERENCE_SYSTEM_CLASS: return JVMTI_HEAP_ROOT_SYSTEM_CLASS;
1697 case JVMTI_HEAP_REFERENCE_STACK_LOCAL: return JVMTI_HEAP_ROOT_STACK_LOCAL;
1698 case JVMTI_HEAP_REFERENCE_JNI_LOCAL: return JVMTI_HEAP_ROOT_JNI_LOCAL;
1699 case JVMTI_HEAP_REFERENCE_THREAD: return JVMTI_HEAP_ROOT_THREAD;
1700 case JVMTI_HEAP_REFERENCE_OTHER: return JVMTI_HEAP_ROOT_OTHER;
1701 default: ShouldNotReachHere(); return JVMTI_HEAP_ROOT_OTHER;
1702 }
1703 }
1704
1705 // Base class for all heap walk contexts. The base class maintains a flag
1706 // to indicate if the context is valid or not.
1707 class HeapWalkContext {
1708 private:
1709 bool _valid;
1710 public:
1711 HeapWalkContext(bool valid) { _valid = valid; }
1712 void invalidate() { _valid = false; }
1713 bool is_valid() const { return _valid; }
1714 };
1715
1716 // A basic heap walk context for the deprecated heap walking functions.
1717 // The context for a basic heap walk are the callbacks and fields used by
1718 // the referrer caching scheme.
1719 class BasicHeapWalkContext: public HeapWalkContext {
1720 private:
1721 jvmtiHeapRootCallback _heap_root_callback;
1722 jvmtiStackReferenceCallback _stack_ref_callback;
1723 jvmtiObjectReferenceCallback _object_ref_callback;
1724
1725 // used for caching
1726 JvmtiHeapwalkObject _last_referrer;
1727 jlong _last_referrer_tag;
1728
1729 public:
1730 BasicHeapWalkContext() : HeapWalkContext(false) { }
1731
1732 BasicHeapWalkContext(jvmtiHeapRootCallback heap_root_callback,
1733 jvmtiStackReferenceCallback stack_ref_callback,
1734 jvmtiObjectReferenceCallback object_ref_callback) :
1735 HeapWalkContext(true),
1736 _heap_root_callback(heap_root_callback),
1737 _stack_ref_callback(stack_ref_callback),
1738 _object_ref_callback(object_ref_callback),
1739 _last_referrer(),
1740 _last_referrer_tag(0) {
1741 }
1742
1743 // accessors
1744 jvmtiHeapRootCallback heap_root_callback() const { return _heap_root_callback; }
1745 jvmtiStackReferenceCallback stack_ref_callback() const { return _stack_ref_callback; }
1746 jvmtiObjectReferenceCallback object_ref_callback() const { return _object_ref_callback; }
1747
1748 JvmtiHeapwalkObject last_referrer() const { return _last_referrer; }
1749 void set_last_referrer(const JvmtiHeapwalkObject& referrer) { _last_referrer = referrer; }
1750 jlong last_referrer_tag() const { return _last_referrer_tag; }
1751 void set_last_referrer_tag(jlong value) { _last_referrer_tag = value; }
1752 };
1753
1754 // The advanced heap walk context for the FollowReferences functions.
1755 // The context is the callbacks, and the fields used for filtering.
1756 class AdvancedHeapWalkContext: public HeapWalkContext {
1757 private:
1758 jint _heap_filter;
1759 Klass* _klass_filter;
1760 const jvmtiHeapCallbacks* _heap_callbacks;
1761
1762 public:
1763 AdvancedHeapWalkContext() : HeapWalkContext(false) { }
1764
1765 AdvancedHeapWalkContext(jint heap_filter,
1766 Klass* klass_filter,
1767 const jvmtiHeapCallbacks* heap_callbacks) :
1768 HeapWalkContext(true),
1769 _heap_filter(heap_filter),
1770 _klass_filter(klass_filter),
1771 _heap_callbacks(heap_callbacks) {
1772 }
1773
1774 // accessors
1775 jint heap_filter() const { return _heap_filter; }
1776 Klass* klass_filter() const { return _klass_filter; }
1777
1778 jvmtiHeapReferenceCallback heap_reference_callback() const {
1779 return _heap_callbacks->heap_reference_callback;
1780 };
1781 jvmtiPrimitiveFieldCallback primitive_field_callback() const {
1782 return _heap_callbacks->primitive_field_callback;
1783 }
1784 jvmtiArrayPrimitiveValueCallback array_primitive_value_callback() const {
1785 return _heap_callbacks->array_primitive_value_callback;
1786 }
1787 jvmtiStringPrimitiveValueCallback string_primitive_value_callback() const {
1788 return _heap_callbacks->string_primitive_value_callback;
1789 }
1790 };
1791
1792 // The CallbackInvoker is a class with static functions that the heap walk can call
1793 // into to invoke callbacks. It works in one of two modes. The "basic" mode is
1794 // used for the deprecated IterateOverReachableObjects functions. The "advanced"
1795 // mode is for the newer FollowReferences function which supports a lot of
1796 // additional callbacks.
1797 class CallbackInvoker : AllStatic {
1798 private:
1799 // heap walk styles
1800 enum { basic, advanced };
1801 static int _heap_walk_type;
1802 static bool is_basic_heap_walk() { return _heap_walk_type == basic; }
1803 static bool is_advanced_heap_walk() { return _heap_walk_type == advanced; }
1804
1805 // context for basic style heap walk
1806 static BasicHeapWalkContext _basic_context;
1807 static BasicHeapWalkContext* basic_context() {
1808 assert(_basic_context.is_valid(), "invalid");
1809 return &_basic_context;
1810 }
1811
1812 // context for advanced style heap walk
1813 static AdvancedHeapWalkContext _advanced_context;
1814 static AdvancedHeapWalkContext* advanced_context() {
1815 assert(_advanced_context.is_valid(), "invalid");
1816 return &_advanced_context;
1817 }
1818
1819 // context needed for all heap walks
1820 static JvmtiTagMap* _tag_map;
1821 static const void* _user_data;
1822 static JvmtiHeapwalkVisitStack* _visit_stack;
1823
1824 // accessors
1825 static JvmtiTagMap* tag_map() { return _tag_map; }
1826 static const void* user_data() { return _user_data; }
1827 static JvmtiHeapwalkVisitStack* visit_stack() { return _visit_stack; }
1828
1829 // if the object hasn't been visited then push it onto the visit stack
1830 // so that it will be visited later
1831 static inline bool check_for_visit(const JvmtiHeapwalkObject&obj) {
1832 visit_stack()->check_for_visit(obj);
1833 return true;
1834 }
1835
1836 // return element count if the obj is array, -1 otherwise
1837 static jint get_array_length(const JvmtiHeapwalkObject& obj) {
1838 if (!obj.klass()->is_array_klass()) {
1839 return -1;
1840 }
1841 assert(!obj.is_flat(), "array cannot be flat");
1842 return (jint)arrayOop(obj.obj())->length();
1843 }
1844
1845
1846 // invoke basic style callbacks
1847 static inline bool invoke_basic_heap_root_callback
1848 (jvmtiHeapRootKind root_kind, const JvmtiHeapwalkObject& obj);
1849 static inline bool invoke_basic_stack_ref_callback
1850 (jvmtiHeapRootKind root_kind, jlong thread_tag, jint depth, jmethodID method,
1851 int slot, const JvmtiHeapwalkObject& obj);
1852 static inline bool invoke_basic_object_reference_callback
1853 (jvmtiObjectReferenceKind ref_kind, const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1854
1855 // invoke advanced style callbacks
1856 static inline bool invoke_advanced_heap_root_callback
1857 (jvmtiHeapReferenceKind ref_kind, const JvmtiHeapwalkObject& obj);
1858 static inline bool invoke_advanced_stack_ref_callback
1859 (jvmtiHeapReferenceKind ref_kind, jlong thread_tag, jlong tid, int depth,
1860 jmethodID method, jlocation bci, jint slot, const JvmtiHeapwalkObject& obj);
1861 static inline bool invoke_advanced_object_reference_callback
1862 (jvmtiHeapReferenceKind ref_kind, const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1863
1864 // used to report the value of primitive fields
1865 static inline bool report_primitive_field
1866 (jvmtiHeapReferenceKind ref_kind, const JvmtiHeapwalkObject& obj, jint index, address addr, char type);
1867
1868 public:
1869 // initialize for basic mode
1870 static void initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1871 const void* user_data,
1872 BasicHeapWalkContext context,
1873 JvmtiHeapwalkVisitStack* visit_stack);
1874
1875 // initialize for advanced mode
1876 static void initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1877 const void* user_data,
1878 AdvancedHeapWalkContext context,
1879 JvmtiHeapwalkVisitStack* visit_stack);
1880
1881 // functions to report roots
1882 static inline bool report_simple_root(jvmtiHeapReferenceKind kind, const JvmtiHeapwalkObject& o);
1883 static inline bool report_jni_local_root(jlong thread_tag, jlong tid, jint depth,
1884 jmethodID m, const JvmtiHeapwalkObject& o);
1885 static inline bool report_stack_ref_root(jlong thread_tag, jlong tid, jint depth,
1886 jmethodID method, jlocation bci, jint slot, const JvmtiHeapwalkObject& o);
1887
1888 // functions to report references
1889 static inline bool report_array_element_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1890 static inline bool report_class_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1891 static inline bool report_class_loader_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1892 static inline bool report_signers_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1893 static inline bool report_protection_domain_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1894 static inline bool report_superclass_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1895 static inline bool report_interface_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree);
1896 static inline bool report_static_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot);
1897 static inline bool report_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot);
1898 static inline bool report_constant_pool_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index);
1899 static inline bool report_primitive_array_values(const JvmtiHeapwalkObject& array);
1900 static inline bool report_string_value(const JvmtiHeapwalkObject& str);
1901 static inline bool report_primitive_instance_field(const JvmtiHeapwalkObject& o, jint index, address value, char type);
1902 static inline bool report_primitive_static_field(const JvmtiHeapwalkObject& o, jint index, address value, char type);
1903 };
1904
1905 // statics
1906 int CallbackInvoker::_heap_walk_type;
1907 BasicHeapWalkContext CallbackInvoker::_basic_context;
1908 AdvancedHeapWalkContext CallbackInvoker::_advanced_context;
1909 JvmtiTagMap* CallbackInvoker::_tag_map;
1910 const void* CallbackInvoker::_user_data;
1911 JvmtiHeapwalkVisitStack* CallbackInvoker::_visit_stack;
1912
1913 // initialize for basic heap walk (IterateOverReachableObjects et al)
1914 void CallbackInvoker::initialize_for_basic_heap_walk(JvmtiTagMap* tag_map,
1915 const void* user_data,
1916 BasicHeapWalkContext context,
1917 JvmtiHeapwalkVisitStack* visit_stack) {
1918 _tag_map = tag_map;
1919 _user_data = user_data;
1920 _basic_context = context;
1921 _advanced_context.invalidate(); // will trigger assertion if used
1922 _heap_walk_type = basic;
1923 _visit_stack = visit_stack;
1924 }
1925
1926 // initialize for advanced heap walk (FollowReferences)
1927 void CallbackInvoker::initialize_for_advanced_heap_walk(JvmtiTagMap* tag_map,
1928 const void* user_data,
1929 AdvancedHeapWalkContext context,
1930 JvmtiHeapwalkVisitStack* visit_stack) {
1931 _tag_map = tag_map;
1932 _user_data = user_data;
1933 _advanced_context = context;
1934 _basic_context.invalidate(); // will trigger assertion if used
1935 _heap_walk_type = advanced;
1936 _visit_stack = visit_stack;
1937 }
1938
1939
1940 // invoke basic style heap root callback
1941 inline bool CallbackInvoker::invoke_basic_heap_root_callback(jvmtiHeapRootKind root_kind, const JvmtiHeapwalkObject& obj) {
1942 // if we heap roots should be reported
1943 jvmtiHeapRootCallback cb = basic_context()->heap_root_callback();
1944 if (cb == nullptr) {
1945 return check_for_visit(obj);
1946 }
1947
1948 CallbackWrapper wrapper(tag_map(), obj);
1949 jvmtiIterationControl control = (*cb)(root_kind,
1950 wrapper.klass_tag(),
1951 wrapper.obj_size(),
1952 wrapper.obj_tag_p(),
1953 (void*)user_data());
1954 // push root to visit stack when following references
1955 if (control == JVMTI_ITERATION_CONTINUE &&
1956 basic_context()->object_ref_callback() != nullptr) {
1957 visit_stack()->push(obj);
1958 }
1959 return control != JVMTI_ITERATION_ABORT;
1960 }
1961
1962 // invoke basic style stack ref callback
1963 inline bool CallbackInvoker::invoke_basic_stack_ref_callback(jvmtiHeapRootKind root_kind,
1964 jlong thread_tag,
1965 jint depth,
1966 jmethodID method,
1967 int slot,
1968 const JvmtiHeapwalkObject& obj) {
1969 // if we stack refs should be reported
1970 jvmtiStackReferenceCallback cb = basic_context()->stack_ref_callback();
1971 if (cb == nullptr) {
1972 return check_for_visit(obj);
1973 }
1974
1975 CallbackWrapper wrapper(tag_map(), obj);
1976 jvmtiIterationControl control = (*cb)(root_kind,
1977 wrapper.klass_tag(),
1978 wrapper.obj_size(),
1979 wrapper.obj_tag_p(),
1980 thread_tag,
1981 depth,
1982 method,
1983 slot,
1984 (void*)user_data());
1985 // push root to visit stack when following references
1986 if (control == JVMTI_ITERATION_CONTINUE &&
1987 basic_context()->object_ref_callback() != nullptr) {
1988 visit_stack()->push(obj);
1989 }
1990 return control != JVMTI_ITERATION_ABORT;
1991 }
1992
1993 // invoke basic style object reference callback
1994 inline bool CallbackInvoker::invoke_basic_object_reference_callback(jvmtiObjectReferenceKind ref_kind,
1995 const JvmtiHeapwalkObject& referrer,
1996 const JvmtiHeapwalkObject& referree,
1997 jint index) {
1998
1999 BasicHeapWalkContext* context = basic_context();
2000
2001 // callback requires the referrer's tag. If it's the same referrer
2002 // as the last call then we use the cached value.
2003 jlong referrer_tag;
2004 if (referrer == context->last_referrer()) {
2005 referrer_tag = context->last_referrer_tag();
2006 } else {
2007 referrer_tag = tag_map()->find(referrer);
2008 }
2009
2010 // do the callback
2011 CallbackWrapper wrapper(tag_map(), referree);
2012 jvmtiObjectReferenceCallback cb = context->object_ref_callback();
2013 jvmtiIterationControl control = (*cb)(ref_kind,
2014 wrapper.klass_tag(),
2015 wrapper.obj_size(),
2016 wrapper.obj_tag_p(),
2017 referrer_tag,
2018 index,
2019 (void*)user_data());
2020
2021 // record referrer and referrer tag. For self-references record the
2022 // tag value from the callback as this might differ from referrer_tag.
2023 context->set_last_referrer(referrer);
2024 if (referrer == referree) {
2025 context->set_last_referrer_tag(*wrapper.obj_tag_p());
2026 } else {
2027 context->set_last_referrer_tag(referrer_tag);
2028 }
2029
2030 if (control == JVMTI_ITERATION_CONTINUE) {
2031 return check_for_visit(referree);
2032 } else {
2033 return control != JVMTI_ITERATION_ABORT;
2034 }
2035 }
2036
2037 // invoke advanced style heap root callback
2038 inline bool CallbackInvoker::invoke_advanced_heap_root_callback(jvmtiHeapReferenceKind ref_kind,
2039 const JvmtiHeapwalkObject& obj) {
2040 AdvancedHeapWalkContext* context = advanced_context();
2041
2042 // check that callback is provided
2043 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2044 if (cb == nullptr) {
2045 return check_for_visit(obj);
2046 }
2047
2048 // apply class filter
2049 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2050 return check_for_visit(obj);
2051 }
2052
2053 // setup the callback wrapper
2054 CallbackWrapper wrapper(tag_map(), obj);
2055
2056 // apply tag filter
2057 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2058 wrapper.klass_tag(),
2059 context->heap_filter())) {
2060 return check_for_visit(obj);
2061 }
2062
2063 // for arrays we need the length, otherwise -1
2064 jint len = get_array_length(obj);
2065
2066 // invoke the callback
2067 jint res = (*cb)(ref_kind,
2068 nullptr, // referrer info
2069 wrapper.klass_tag(),
2070 0, // referrer_class_tag is 0 for heap root
2071 wrapper.obj_size(),
2072 wrapper.obj_tag_p(),
2073 nullptr, // referrer_tag_p
2074 len,
2075 (void*)user_data());
2076 if (res & JVMTI_VISIT_ABORT) {
2077 return false;// referrer class tag
2078 }
2079 if (res & JVMTI_VISIT_OBJECTS) {
2080 check_for_visit(obj);
2081 }
2082 return true;
2083 }
2084
2085 // report a reference from a thread stack to an object
2086 inline bool CallbackInvoker::invoke_advanced_stack_ref_callback(jvmtiHeapReferenceKind ref_kind,
2087 jlong thread_tag,
2088 jlong tid,
2089 int depth,
2090 jmethodID method,
2091 jlocation bci,
2092 jint slot,
2093 const JvmtiHeapwalkObject& obj) {
2094 AdvancedHeapWalkContext* context = advanced_context();
2095
2096 // check that callback is provider
2097 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2098 if (cb == nullptr) {
2099 return check_for_visit(obj);
2100 }
2101
2102 // apply class filter
2103 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2104 return check_for_visit(obj);
2105 }
2106
2107 // setup the callback wrapper
2108 CallbackWrapper wrapper(tag_map(), obj);
2109
2110 // apply tag filter
2111 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2112 wrapper.klass_tag(),
2113 context->heap_filter())) {
2114 return check_for_visit(obj);
2115 }
2116
2117 // setup the referrer info
2118 jvmtiHeapReferenceInfo reference_info;
2119 reference_info.stack_local.thread_tag = thread_tag;
2120 reference_info.stack_local.thread_id = tid;
2121 reference_info.stack_local.depth = depth;
2122 reference_info.stack_local.method = method;
2123 reference_info.stack_local.location = bci;
2124 reference_info.stack_local.slot = slot;
2125
2126 // for arrays we need the length, otherwise -1
2127 jint len = get_array_length(obj);
2128
2129 // call into the agent
2130 int res = (*cb)(ref_kind,
2131 &reference_info,
2132 wrapper.klass_tag(),
2133 0, // referrer_class_tag is 0 for heap root (stack)
2134 wrapper.obj_size(),
2135 wrapper.obj_tag_p(),
2136 nullptr, // referrer_tag is 0 for root
2137 len,
2138 (void*)user_data());
2139
2140 if (res & JVMTI_VISIT_ABORT) {
2141 return false;
2142 }
2143 if (res & JVMTI_VISIT_OBJECTS) {
2144 check_for_visit(obj);
2145 }
2146 return true;
2147 }
2148
2149 // This mask is used to pass reference_info to a jvmtiHeapReferenceCallback
2150 // only for ref_kinds defined by the JVM TI spec. Otherwise, null is passed.
2151 #define REF_INFO_MASK ((1 << JVMTI_HEAP_REFERENCE_FIELD) \
2152 | (1 << JVMTI_HEAP_REFERENCE_STATIC_FIELD) \
2153 | (1 << JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT) \
2154 | (1 << JVMTI_HEAP_REFERENCE_CONSTANT_POOL) \
2155 | (1 << JVMTI_HEAP_REFERENCE_STACK_LOCAL) \
2156 | (1 << JVMTI_HEAP_REFERENCE_JNI_LOCAL))
2157
2158 // invoke the object reference callback to report a reference
2159 inline bool CallbackInvoker::invoke_advanced_object_reference_callback(jvmtiHeapReferenceKind ref_kind,
2160 const JvmtiHeapwalkObject& referrer,
2161 const JvmtiHeapwalkObject& obj,
2162 jint index)
2163 {
2164 // field index is only valid field in reference_info
2165 static jvmtiHeapReferenceInfo reference_info = { 0 };
2166
2167 AdvancedHeapWalkContext* context = advanced_context();
2168
2169 // check that callback is provider
2170 jvmtiHeapReferenceCallback cb = context->heap_reference_callback();
2171 if (cb == nullptr) {
2172 return check_for_visit(obj);
2173 }
2174
2175 // apply class filter
2176 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2177 return check_for_visit(obj);
2178 }
2179
2180 // setup the callback wrapper
2181 TwoOopCallbackWrapper wrapper(tag_map(), referrer, obj);
2182
2183 // apply tag filter
2184 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2185 wrapper.klass_tag(),
2186 context->heap_filter())) {
2187 return check_for_visit(obj);
2188 }
2189
2190 // field index is only valid field in reference_info
2191 reference_info.field.index = index;
2192
2193 // for arrays we need the length, otherwise -1
2194 jint len = get_array_length(obj);
2195
2196 // invoke the callback
2197 int res = (*cb)(ref_kind,
2198 (REF_INFO_MASK & (1 << ref_kind)) ? &reference_info : nullptr,
2199 wrapper.klass_tag(),
2200 wrapper.referrer_klass_tag(),
2201 wrapper.obj_size(),
2202 wrapper.obj_tag_p(),
2203 wrapper.referrer_tag_p(),
2204 len,
2205 (void*)user_data());
2206
2207 if (res & JVMTI_VISIT_ABORT) {
2208 return false;
2209 }
2210 if (res & JVMTI_VISIT_OBJECTS) {
2211 check_for_visit(obj);
2212 }
2213 return true;
2214 }
2215
2216 // report a "simple root"
2217 inline bool CallbackInvoker::report_simple_root(jvmtiHeapReferenceKind kind, const JvmtiHeapwalkObject& obj) {
2218 assert(kind != JVMTI_HEAP_REFERENCE_STACK_LOCAL &&
2219 kind != JVMTI_HEAP_REFERENCE_JNI_LOCAL, "not a simple root");
2220
2221 if (is_basic_heap_walk()) {
2222 // map to old style root kind
2223 jvmtiHeapRootKind root_kind = toJvmtiHeapRootKind(kind);
2224 return invoke_basic_heap_root_callback(root_kind, obj);
2225 } else {
2226 assert(is_advanced_heap_walk(), "wrong heap walk type");
2227 return invoke_advanced_heap_root_callback(kind, obj);
2228 }
2229 }
2230
2231
2232 // invoke the primitive array values
2233 inline bool CallbackInvoker::report_primitive_array_values(const JvmtiHeapwalkObject& obj) {
2234 assert(obj.klass()->is_typeArray_klass(), "not a primitive array");
2235
2236 AdvancedHeapWalkContext* context = advanced_context();
2237 assert(context->array_primitive_value_callback() != nullptr, "no callback");
2238
2239 // apply class filter
2240 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2241 return true;
2242 }
2243
2244 CallbackWrapper wrapper(tag_map(), obj);
2245
2246 // apply tag filter
2247 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2248 wrapper.klass_tag(),
2249 context->heap_filter())) {
2250 return true;
2251 }
2252
2253 // invoke the callback
2254 int res = invoke_array_primitive_value_callback(context->array_primitive_value_callback(),
2255 &wrapper,
2256 obj,
2257 (void*)user_data());
2258 return (!(res & JVMTI_VISIT_ABORT));
2259 }
2260
2261 // invoke the string value callback
2262 inline bool CallbackInvoker::report_string_value(const JvmtiHeapwalkObject& str) {
2263 assert(str.klass() == vmClasses::String_klass(), "not a string");
2264
2265 AdvancedHeapWalkContext* context = advanced_context();
2266 assert(context->string_primitive_value_callback() != nullptr, "no callback");
2267
2268 // apply class filter
2269 if (is_filtered_by_klass_filter(str, context->klass_filter())) {
2270 return true;
2271 }
2272
2273 CallbackWrapper wrapper(tag_map(), str);
2274
2275 // apply tag filter
2276 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2277 wrapper.klass_tag(),
2278 context->heap_filter())) {
2279 return true;
2280 }
2281
2282 // invoke the callback
2283 int res = invoke_string_value_callback(context->string_primitive_value_callback(),
2284 &wrapper,
2285 str,
2286 (void*)user_data());
2287 return (!(res & JVMTI_VISIT_ABORT));
2288 }
2289
2290 // invoke the primitive field callback
2291 inline bool CallbackInvoker::report_primitive_field(jvmtiHeapReferenceKind ref_kind,
2292 const JvmtiHeapwalkObject& obj,
2293 jint index,
2294 address addr,
2295 char type)
2296 {
2297 // for primitive fields only the index will be set
2298 static jvmtiHeapReferenceInfo reference_info = { 0 };
2299
2300 AdvancedHeapWalkContext* context = advanced_context();
2301 assert(context->primitive_field_callback() != nullptr, "no callback");
2302
2303 // apply class filter
2304 if (is_filtered_by_klass_filter(obj, context->klass_filter())) {
2305 return true;
2306 }
2307
2308 CallbackWrapper wrapper(tag_map(), obj);
2309
2310 // apply tag filter
2311 if (is_filtered_by_heap_filter(wrapper.obj_tag(),
2312 wrapper.klass_tag(),
2313 context->heap_filter())) {
2314 return true;
2315 }
2316
2317 // the field index in the referrer
2318 reference_info.field.index = index;
2319
2320 // map the type
2321 jvmtiPrimitiveType value_type = (jvmtiPrimitiveType)type;
2322
2323 // setup the jvalue
2324 jvalue value;
2325 copy_to_jvalue(&value, addr, value_type);
2326
2327 jvmtiPrimitiveFieldCallback cb = context->primitive_field_callback();
2328 int res = (*cb)(ref_kind,
2329 &reference_info,
2330 wrapper.klass_tag(),
2331 wrapper.obj_tag_p(),
2332 value,
2333 value_type,
2334 (void*)user_data());
2335 return (!(res & JVMTI_VISIT_ABORT));
2336 }
2337
2338
2339 // instance field
2340 inline bool CallbackInvoker::report_primitive_instance_field(const JvmtiHeapwalkObject& obj,
2341 jint index,
2342 address value,
2343 char type) {
2344 return report_primitive_field(JVMTI_HEAP_REFERENCE_FIELD,
2345 obj,
2346 index,
2347 value,
2348 type);
2349 }
2350
2351 // static field
2352 inline bool CallbackInvoker::report_primitive_static_field(const JvmtiHeapwalkObject& obj,
2353 jint index,
2354 address value,
2355 char type) {
2356 return report_primitive_field(JVMTI_HEAP_REFERENCE_STATIC_FIELD,
2357 obj,
2358 index,
2359 value,
2360 type);
2361 }
2362
2363 // report a JNI local (root object) to the profiler
2364 inline bool CallbackInvoker::report_jni_local_root(jlong thread_tag, jlong tid, jint depth, jmethodID m, const JvmtiHeapwalkObject& obj) {
2365 if (is_basic_heap_walk()) {
2366 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_JNI_LOCAL,
2367 thread_tag,
2368 depth,
2369 m,
2370 -1,
2371 obj);
2372 } else {
2373 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_JNI_LOCAL,
2374 thread_tag, tid,
2375 depth,
2376 m,
2377 (jlocation)-1,
2378 -1,
2379 obj);
2380 }
2381 }
2382
2383
2384 // report a local (stack reference, root object)
2385 inline bool CallbackInvoker::report_stack_ref_root(jlong thread_tag,
2386 jlong tid,
2387 jint depth,
2388 jmethodID method,
2389 jlocation bci,
2390 jint slot,
2391 const JvmtiHeapwalkObject& obj) {
2392 if (is_basic_heap_walk()) {
2393 return invoke_basic_stack_ref_callback(JVMTI_HEAP_ROOT_STACK_LOCAL,
2394 thread_tag,
2395 depth,
2396 method,
2397 slot,
2398 obj);
2399 } else {
2400 return invoke_advanced_stack_ref_callback(JVMTI_HEAP_REFERENCE_STACK_LOCAL,
2401 thread_tag,
2402 tid,
2403 depth,
2404 method,
2405 bci,
2406 slot,
2407 obj);
2408 }
2409 }
2410
2411 // report an object referencing a class.
2412 inline bool CallbackInvoker::report_class_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2413 if (is_basic_heap_walk()) {
2414 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2415 } else {
2416 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS, referrer, referree, -1);
2417 }
2418 }
2419
2420 // report a class referencing its class loader.
2421 inline bool CallbackInvoker::report_class_loader_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2422 if (is_basic_heap_walk()) {
2423 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2424 } else {
2425 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CLASS_LOADER, referrer, referree, -1);
2426 }
2427 }
2428
2429 // report a class referencing its signers.
2430 inline bool CallbackInvoker::report_signers_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2431 if (is_basic_heap_walk()) {
2432 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_SIGNERS, referrer, referree, -1);
2433 } else {
2434 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SIGNERS, referrer, referree, -1);
2435 }
2436 }
2437
2438 // report a class referencing its protection domain..
2439 inline bool CallbackInvoker::report_protection_domain_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2440 if (is_basic_heap_walk()) {
2441 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2442 } else {
2443 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN, referrer, referree, -1);
2444 }
2445 }
2446
2447 // report a class referencing its superclass.
2448 inline bool CallbackInvoker::report_superclass_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2449 if (is_basic_heap_walk()) {
2450 // Send this to be consistent with past implementation
2451 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CLASS, referrer, referree, -1);
2452 } else {
2453 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_SUPERCLASS, referrer, referree, -1);
2454 }
2455 }
2456
2457 // report a class referencing one of its interfaces.
2458 inline bool CallbackInvoker::report_interface_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree) {
2459 if (is_basic_heap_walk()) {
2460 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_INTERFACE, referrer, referree, -1);
2461 } else {
2462 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_INTERFACE, referrer, referree, -1);
2463 }
2464 }
2465
2466 // report a class referencing one of its static fields.
2467 inline bool CallbackInvoker::report_static_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot) {
2468 if (is_basic_heap_walk()) {
2469 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2470 } else {
2471 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_STATIC_FIELD, referrer, referree, slot);
2472 }
2473 }
2474
2475 // report an array referencing an element object
2476 inline bool CallbackInvoker::report_array_element_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index) {
2477 if (is_basic_heap_walk()) {
2478 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2479 } else {
2480 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, referrer, referree, index);
2481 }
2482 }
2483
2484 // report an object referencing an instance field object
2485 inline bool CallbackInvoker::report_field_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint slot) {
2486 if (is_basic_heap_walk()) {
2487 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_FIELD, referrer, referree, slot);
2488 } else {
2489 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_FIELD, referrer, referree, slot);
2490 }
2491 }
2492
2493 // report an array referencing an element object
2494 inline bool CallbackInvoker::report_constant_pool_reference(const JvmtiHeapwalkObject& referrer, const JvmtiHeapwalkObject& referree, jint index) {
2495 if (is_basic_heap_walk()) {
2496 return invoke_basic_object_reference_callback(JVMTI_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2497 } else {
2498 return invoke_advanced_object_reference_callback(JVMTI_HEAP_REFERENCE_CONSTANT_POOL, referrer, referree, index);
2499 }
2500 }
2501
2502 // A supporting closure used to process simple roots
2503 class SimpleRootsClosure : public OopClosure {
2504 private:
2505 jvmtiHeapReferenceKind _kind;
2506 bool _continue;
2507
2508 jvmtiHeapReferenceKind root_kind() { return _kind; }
2509
2510 public:
2511 void set_kind(jvmtiHeapReferenceKind kind) {
2512 _kind = kind;
2513 _continue = true;
2514 }
2515
2516 inline bool stopped() {
2517 return !_continue;
2518 }
2519
2520 void do_oop(oop* obj_p) {
2521 // iteration has terminated
2522 if (stopped()) {
2523 return;
2524 }
2525
2526 oop o = NativeAccess<AS_NO_KEEPALIVE>::oop_load(obj_p);
2527 // ignore null
2528 if (o == nullptr) {
2529 return;
2530 }
2531
2532 assert(Universe::heap()->is_in(o), "should be impossible");
2533
2534 jvmtiHeapReferenceKind kind = root_kind();
2535
2536 // invoke the callback
2537 _continue = CallbackInvoker::report_simple_root(kind, o);
2538
2539 }
2540 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2541 };
2542
2543 // A supporting closure used to process ClassLoaderData roots.
2544 class CLDRootsClosure: public OopClosure {
2545 private:
2546 bool _continue;
2547 public:
2548 CLDRootsClosure(): _continue(true) {}
2549
2550 inline bool stopped() {
2551 return !_continue;
2552 }
2553
2554 void do_oop(oop* obj_p) {
2555 if (stopped()) {
2556 return;
2557 }
2558
2559 oop o = NativeAccess<AS_NO_KEEPALIVE>::oop_load(obj_p);
2560 // ignore null
2561 if (o == nullptr) {
2562 return;
2563 }
2564
2565 jvmtiHeapReferenceKind kind = JVMTI_HEAP_REFERENCE_OTHER;
2566 if (o->klass() == vmClasses::Class_klass()) {
2567 kind = JVMTI_HEAP_REFERENCE_SYSTEM_CLASS;
2568 }
2569
2570 // invoke the callback
2571 _continue = CallbackInvoker::report_simple_root(kind, o);
2572 }
2573 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2574 };
2575
2576 // A supporting closure used to process JNI locals
2577 class JNILocalRootsClosure : public OopClosure {
2578 private:
2579 jlong _thread_tag;
2580 jlong _tid;
2581 jint _depth;
2582 jmethodID _method;
2583 bool _continue;
2584 public:
2585 void set_context(jlong thread_tag, jlong tid, jint depth, jmethodID method) {
2586 _thread_tag = thread_tag;
2587 _tid = tid;
2588 _depth = depth;
2589 _method = method;
2590 _continue = true;
2591 }
2592
2593 inline bool stopped() {
2594 return !_continue;
2595 }
2596
2597 void do_oop(oop* obj_p) {
2598 // iteration has terminated
2599 if (stopped()) {
2600 return;
2601 }
2602
2603 oop o = *obj_p;
2604 // ignore null
2605 if (o == nullptr) {
2606 return;
2607 }
2608
2609 // invoke the callback
2610 _continue = CallbackInvoker::report_jni_local_root(_thread_tag, _tid, _depth, _method, o);
2611 }
2612 virtual void do_oop(narrowOop* obj_p) { ShouldNotReachHere(); }
2613 };
2614
2615 // Helper class to collect/report stack references.
2616 class StackRefCollector {
2617 private:
2618 JvmtiTagMap* _tag_map;
2619 JNILocalRootsClosure* _blk;
2620 // java_thread is needed only to report JNI local on top native frame;
2621 // I.e. it's required only for platform/carrier threads or mounted virtual threads.
2622 JavaThread* _java_thread;
2623
2624 oop _threadObj;
2625 jlong _thread_tag;
2626 jlong _tid;
2627
2628 bool _is_top_frame;
2629 int _depth;
2630 frame* _last_entry_frame;
2631
2632 bool report_java_stack_refs(StackValueCollection* values, jmethodID method, jlocation bci, jint slot_offset);
2633 bool report_native_stack_refs(jmethodID method);
2634
2635 public:
2636 StackRefCollector(JvmtiTagMap* tag_map, JNILocalRootsClosure* blk, JavaThread* java_thread)
2637 : _tag_map(tag_map), _blk(blk), _java_thread(java_thread),
2638 _threadObj(nullptr), _thread_tag(0), _tid(0),
2639 _is_top_frame(true), _depth(0), _last_entry_frame(nullptr)
2640 {
2641 }
2642
2643 bool set_thread(oop o);
2644 // Sets the thread and reports the reference to it with the specified kind.
2645 bool set_thread(jvmtiHeapReferenceKind kind, oop o);
2646
2647 bool do_frame(vframe* vf);
2648 // Handles frames until vf->sender() is null.
2649 bool process_frames(vframe* vf);
2650 };
2651
2652 bool StackRefCollector::set_thread(oop o) {
2653 _threadObj = o;
2654 _thread_tag = _tag_map->find(_threadObj);
2655 _tid = java_lang_Thread::thread_id(_threadObj);
2656
2657 _is_top_frame = true;
2658 _depth = 0;
2659 _last_entry_frame = nullptr;
2660
2661 return true;
2662 }
2663
2664 bool StackRefCollector::set_thread(jvmtiHeapReferenceKind kind, oop o) {
2665 return set_thread(o)
2666 && CallbackInvoker::report_simple_root(kind, _threadObj);
2667 }
2668
2669 bool StackRefCollector::report_java_stack_refs(StackValueCollection* values, jmethodID method, jlocation bci, jint slot_offset) {
2670 for (int index = 0; index < values->size(); index++) {
2671 if (values->at(index)->type() == T_OBJECT) {
2672 oop obj = values->obj_at(index)();
2673 if (obj == nullptr) {
2674 continue;
2675 }
2676 // stack reference
2677 if (!CallbackInvoker::report_stack_ref_root(_thread_tag, _tid, _depth, method,
2678 bci, slot_offset + index, obj)) {
2679 return false;
2680 }
2681 }
2682 }
2683 return true;
2684 }
2685
2686 bool StackRefCollector::report_native_stack_refs(jmethodID method) {
2687 _blk->set_context(_thread_tag, _tid, _depth, method);
2688 if (_is_top_frame) {
2689 // JNI locals for the top frame.
2690 if (_java_thread != nullptr) {
2691 _java_thread->active_handles()->oops_do(_blk);
2692 if (_blk->stopped()) {
2693 return false;
2694 }
2695 }
2696 } else {
2697 if (_last_entry_frame != nullptr) {
2698 // JNI locals for the entry frame.
2699 assert(_last_entry_frame->is_entry_frame(), "checking");
2700 _last_entry_frame->entry_frame_call_wrapper()->handles()->oops_do(_blk);
2701 if (_blk->stopped()) {
2702 return false;
2703 }
2704 }
2705 }
2706 return true;
2707 }
2708
2709 bool StackRefCollector::do_frame(vframe* vf) {
2710 if (vf->is_java_frame()) {
2711 // java frame (interpreted, compiled, ...)
2712 javaVFrame* jvf = javaVFrame::cast(vf);
2713
2714 jmethodID method = jvf->method()->jmethod_id();
2715
2716 if (!(jvf->method()->is_native())) {
2717 jlocation bci = (jlocation)jvf->bci();
2718 StackValueCollection* locals = jvf->locals();
2719 if (!report_java_stack_refs(locals, method, bci, 0)) {
2720 return false;
2721 }
2722 if (!report_java_stack_refs(jvf->expressions(), method, bci, locals->size())) {
2723 return false;
2724 }
2725
2726 // Follow oops from compiled nmethod.
2727 if (jvf->cb() != nullptr && jvf->cb()->is_nmethod()) {
2728 _blk->set_context(_thread_tag, _tid, _depth, method);
2729 // Need to apply load barriers for unmounted vthreads.
2730 nmethod* nm = jvf->cb()->as_nmethod();
2731 nm->run_nmethod_entry_barrier();
2732 nm->oops_do(_blk);
2733 if (_blk->stopped()) {
2734 return false;
2735 }
2736 }
2737 } else {
2738 // native frame
2739 if (!report_native_stack_refs(method)) {
2740 return false;
2741 }
2742 }
2743 _last_entry_frame = nullptr;
2744 _depth++;
2745 } else {
2746 // externalVFrame - for an entry frame then we report the JNI locals
2747 // when we find the corresponding javaVFrame
2748 frame* fr = vf->frame_pointer();
2749 assert(fr != nullptr, "sanity check");
2750 if (fr->is_entry_frame()) {
2751 _last_entry_frame = fr;
2752 }
2753 }
2754
2755 _is_top_frame = false;
2756
2757 return true;
2758 }
2759
2760 bool StackRefCollector::process_frames(vframe* vf) {
2761 while (vf != nullptr) {
2762 if (!do_frame(vf)) {
2763 return false;
2764 }
2765 vf = vf->sender();
2766 }
2767 return true;
2768 }
2769
2770
2771 // A VM operation to iterate over objects that are reachable from
2772 // a set of roots or an initial object.
2773 //
2774 // For VM_HeapWalkOperation the set of roots used is :-
2775 //
2776 // - All JNI global references
2777 // - All inflated monitors
2778 // - All classes loaded by the boot class loader (or all classes
2779 // in the event that class unloading is disabled)
2780 // - All java threads
2781 // - For each java thread then all locals and JNI local references
2782 // on the thread's execution stack
2783 // - All visible/explainable objects from Universes::oops_do
2784 //
2785 class VM_HeapWalkOperation: public VM_Operation {
2786 private:
2787 bool _is_advanced_heap_walk; // indicates FollowReferences
2788 JvmtiTagMap* _tag_map;
2789 Handle _initial_object;
2790 JvmtiHeapwalkVisitStack _visit_stack;
2791
2792 // Dead object tags in JvmtiTagMap
2793 GrowableArray<jlong>* _dead_objects;
2794
2795 bool _following_object_refs; // are we following object references
2796
2797 bool _reporting_primitive_fields; // optional reporting
2798 bool _reporting_primitive_array_values;
2799 bool _reporting_string_values;
2800
2801 // accessors
2802 bool is_advanced_heap_walk() const { return _is_advanced_heap_walk; }
2803 JvmtiTagMap* tag_map() const { return _tag_map; }
2804 Handle initial_object() const { return _initial_object; }
2805
2806 bool is_following_references() const { return _following_object_refs; }
2807
2808 bool is_reporting_primitive_fields() const { return _reporting_primitive_fields; }
2809 bool is_reporting_primitive_array_values() const { return _reporting_primitive_array_values; }
2810 bool is_reporting_string_values() const { return _reporting_string_values; }
2811
2812 JvmtiHeapwalkVisitStack* visit_stack() { return &_visit_stack; }
2813
2814 // iterate over the various object types
2815 inline bool iterate_over_array(const JvmtiHeapwalkObject& o);
2816 inline bool iterate_over_flat_array(const JvmtiHeapwalkObject& o);
2817 inline bool iterate_over_type_array(const JvmtiHeapwalkObject& o);
2818 inline bool iterate_over_class(const JvmtiHeapwalkObject& o);
2819 inline bool iterate_over_object(const JvmtiHeapwalkObject& o);
2820
2821 // root collection
2822 inline bool collect_simple_roots();
2823 inline bool collect_stack_roots();
2824 inline bool collect_stack_refs(JavaThread* java_thread, JNILocalRootsClosure* blk);
2825 inline bool collect_vthread_stack_refs(oop vt);
2826
2827 // visit an object
2828 inline bool visit(const JvmtiHeapwalkObject& o);
2829
2830 public:
2831 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2832 Handle initial_object,
2833 BasicHeapWalkContext callbacks,
2834 const void* user_data,
2835 GrowableArray<jlong>* objects);
2836
2837 VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2838 Handle initial_object,
2839 AdvancedHeapWalkContext callbacks,
2840 const void* user_data,
2841 GrowableArray<jlong>* objects);
2842
2843 ~VM_HeapWalkOperation();
2844
2845 VMOp_Type type() const { return VMOp_HeapWalkOperation; }
2846 void doit();
2847 };
2848
2849
2850 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2851 Handle initial_object,
2852 BasicHeapWalkContext callbacks,
2853 const void* user_data,
2854 GrowableArray<jlong>* objects) {
2855 _is_advanced_heap_walk = false;
2856 _tag_map = tag_map;
2857 _initial_object = initial_object;
2858 _following_object_refs = (callbacks.object_ref_callback() != nullptr);
2859 _reporting_primitive_fields = false;
2860 _reporting_primitive_array_values = false;
2861 _reporting_string_values = false;
2862 _dead_objects = objects;
2863 CallbackInvoker::initialize_for_basic_heap_walk(tag_map, user_data, callbacks, &_visit_stack);
2864 }
2865
2866 VM_HeapWalkOperation::VM_HeapWalkOperation(JvmtiTagMap* tag_map,
2867 Handle initial_object,
2868 AdvancedHeapWalkContext callbacks,
2869 const void* user_data,
2870 GrowableArray<jlong>* objects) {
2871 _is_advanced_heap_walk = true;
2872 _tag_map = tag_map;
2873 _initial_object = initial_object;
2874 _following_object_refs = true;
2875 _reporting_primitive_fields = (callbacks.primitive_field_callback() != nullptr);;
2876 _reporting_primitive_array_values = (callbacks.array_primitive_value_callback() != nullptr);;
2877 _reporting_string_values = (callbacks.string_primitive_value_callback() != nullptr);;
2878 _dead_objects = objects;
2879 CallbackInvoker::initialize_for_advanced_heap_walk(tag_map, user_data, callbacks, &_visit_stack);
2880 }
2881
2882 VM_HeapWalkOperation::~VM_HeapWalkOperation() {
2883 }
2884
2885 // an array references its class and has a reference to
2886 // each element in the array
2887 inline bool VM_HeapWalkOperation::iterate_over_array(const JvmtiHeapwalkObject& o) {
2888 assert(!o.is_flat(), "Array object cannot be flattened");
2889 refArrayOop array = oop_cast<refArrayOop>(o.obj());
2890
2891 // array reference to its class
2892 oop mirror = RefArrayKlass::cast(array->klass())->java_mirror();
2893 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2894 return false;
2895 }
2896
2897 // iterate over the array and report each reference to a
2898 // non-null element
2899 for (int index=0; index<array->length(); index++) {
2900 oop elem = array->obj_at(index);
2901 if (elem == nullptr) {
2902 continue;
2903 }
2904
2905 // report the array reference o[index] = elem
2906 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2907 return false;
2908 }
2909 }
2910 return true;
2911 }
2912
2913 // similar to iterate_over_array(), but itrates over flat array
2914 inline bool VM_HeapWalkOperation::iterate_over_flat_array(const JvmtiHeapwalkObject& o) {
2915 assert(!o.is_flat(), "Array object cannot be flattened");
2916 flatArrayOop array = flatArrayOop(o.obj());
2917 FlatArrayKlass* faklass = FlatArrayKlass::cast(array->klass());
2918 InlineKlass* vk = InlineKlass::cast(faklass->element_klass());
2919 bool need_null_check = LayoutKindHelper::is_nullable_flat(faklass->layout_kind());
2920
2921 // array reference to its class
2922 oop mirror = faklass->java_mirror();
2923 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2924 return false;
2925 }
2926
2927 // iterate over the array and report each reference to a
2928 // non-null element
2929 for (int index = 0; index < array->length(); index++) {
2930 address addr = (address)array->value_at_addr(index, faklass->layout_helper());
2931
2932 // check for null
2933 if (need_null_check) {
2934 if (vk->is_payload_marked_as_null(addr)) {
2935 continue;
2936 }
2937 }
2938
2939 // offset in the array oop
2940 int offset = (int)(addr - cast_from_oop<address>(array));
2941 JvmtiHeapwalkObject elem(o.obj(), offset, vk, faklass->layout_kind());
2942
2943 // report the array reference
2944 if (!CallbackInvoker::report_array_element_reference(o, elem, index)) {
2945 return false;
2946 }
2947 }
2948 return true;
2949 }
2950
2951 // a type array references its class
2952 inline bool VM_HeapWalkOperation::iterate_over_type_array(const JvmtiHeapwalkObject& o) {
2953 assert(!o.is_flat(), "Array object cannot be flattened");
2954 Klass* k = o.klass();
2955 oop mirror = k->java_mirror();
2956 if (!CallbackInvoker::report_class_reference(o, mirror)) {
2957 return false;
2958 }
2959
2960 // report the array contents if required
2961 if (is_reporting_primitive_array_values()) {
2962 if (!CallbackInvoker::report_primitive_array_values(o)) {
2963 return false;
2964 }
2965 }
2966 return true;
2967 }
2968
2969 #ifdef ASSERT
2970 // verify that a static oop field is in range
2971 static inline bool verify_static_oop(InstanceKlass* ik,
2972 oop mirror, int offset) {
2973 address obj_p = cast_from_oop<address>(mirror) + offset;
2974 address start = (address)InstanceMirrorKlass::start_of_static_fields(mirror);
2975 address end = start + (java_lang_Class::static_oop_field_count(mirror) * heapOopSize);
2976 assert(end >= start, "sanity check");
2977
2978 if (obj_p >= start && obj_p < end) {
2979 return true;
2980 } else {
2981 return false;
2982 }
2983 }
2984 #endif // #ifdef ASSERT
2985
2986 // a class references its super class, interfaces, class loader, ...
2987 // and finally its static fields
2988 inline bool VM_HeapWalkOperation::iterate_over_class(const JvmtiHeapwalkObject& o) {
2989 assert(!o.is_flat(), "Klass object cannot be flattened");
2990 Klass* klass = java_lang_Class::as_Klass(o.obj());
2991 int i;
2992
2993 if (klass->is_instance_klass()) {
2994 InstanceKlass* ik = InstanceKlass::cast(klass);
2995
2996 // Ignore the class if it hasn't been initialized yet
2997 if (!ik->is_linked()) {
2998 return true;
2999 }
3000
3001 // get the java mirror
3002 oop mirror_oop = klass->java_mirror();
3003 JvmtiHeapwalkObject mirror(mirror_oop);
3004
3005 // super (only if something more interesting than java.lang.Object)
3006 InstanceKlass* super_klass = ik->super();
3007 if (super_klass != nullptr && super_klass != vmClasses::Object_klass()) {
3008 oop super_oop = super_klass->java_mirror();
3009 if (!CallbackInvoker::report_superclass_reference(mirror, super_oop)) {
3010 return false;
3011 }
3012 }
3013
3014 // class loader
3015 oop cl = ik->class_loader();
3016 if (cl != nullptr) {
3017 if (!CallbackInvoker::report_class_loader_reference(mirror, cl)) {
3018 return false;
3019 }
3020 }
3021
3022 // protection domain
3023 oop pd = ik->protection_domain();
3024 if (pd != nullptr) {
3025 if (!CallbackInvoker::report_protection_domain_reference(mirror, pd)) {
3026 return false;
3027 }
3028 }
3029
3030 // signers
3031 oop signers = ik->signers();
3032 if (signers != nullptr) {
3033 if (!CallbackInvoker::report_signers_reference(mirror, signers)) {
3034 return false;
3035 }
3036 }
3037
3038 // references from the constant pool
3039 {
3040 ConstantPool* pool = ik->constants();
3041 for (int i = 1; i < pool->length(); i++) {
3042 constantTag tag = pool->tag_at(i).value();
3043 if (tag.is_string() || tag.is_klass() || tag.is_unresolved_klass()) {
3044 oop entry;
3045 if (tag.is_string()) {
3046 entry = pool->resolved_string_at(i);
3047 // If the entry is non-null it is resolved.
3048 if (entry == nullptr) {
3049 continue;
3050 }
3051 } else if (tag.is_klass()) {
3052 entry = pool->resolved_klass_at(i)->java_mirror();
3053 } else {
3054 // Code generated by JIT compilers might not resolve constant
3055 // pool entries. Treat them as resolved if they are loaded.
3056 assert(tag.is_unresolved_klass(), "must be");
3057 constantPoolHandle cp(Thread::current(), pool);
3058 Klass* klass = ConstantPool::klass_at_if_loaded(cp, i);
3059 if (klass == nullptr) {
3060 continue;
3061 }
3062 entry = klass->java_mirror();
3063 }
3064 if (!CallbackInvoker::report_constant_pool_reference(mirror, entry, (jint)i)) {
3065 return false;
3066 }
3067 }
3068 }
3069 }
3070
3071 // interfaces
3072 // (These will already have been reported as references from the constant pool
3073 // but are specified by IterateOverReachableObjects and must be reported).
3074 Array<InstanceKlass*>* interfaces = ik->local_interfaces();
3075 for (i = 0; i < interfaces->length(); i++) {
3076 oop interf = interfaces->at(i)->java_mirror();
3077 if (interf == nullptr) {
3078 continue;
3079 }
3080 if (!CallbackInvoker::report_interface_reference(mirror, interf)) {
3081 return false;
3082 }
3083 }
3084
3085 // iterate over the static fields
3086
3087 ClassFieldMap* field_map = ClassFieldMap::create_map_of_static_fields(klass);
3088 for (i=0; i<field_map->field_count(); i++) {
3089 ClassFieldDescriptor* field = field_map->field_at(i);
3090 char type = field->field_type();
3091 if (!is_primitive_field_type(type)) {
3092 oop fld_o = mirror_oop->obj_field(field->field_offset());
3093 assert(verify_static_oop(ik, mirror_oop, field->field_offset()), "sanity check");
3094 if (fld_o != nullptr) {
3095 int slot = field->field_index();
3096 if (!CallbackInvoker::report_static_field_reference(mirror, fld_o, slot)) {
3097 delete field_map;
3098 return false;
3099 }
3100 }
3101 } else {
3102 if (is_reporting_primitive_fields()) {
3103 address addr = cast_from_oop<address>(mirror_oop) + field->field_offset();
3104 int slot = field->field_index();
3105 if (!CallbackInvoker::report_primitive_static_field(mirror, slot, addr, type)) {
3106 delete field_map;
3107 return false;
3108 }
3109 }
3110 }
3111 }
3112 delete field_map;
3113
3114 return true;
3115 }
3116
3117 return true;
3118 }
3119
3120 // an object references a class and its instance fields
3121 // (static fields are ignored here as we report these as
3122 // references from the class).
3123 inline bool VM_HeapWalkOperation::iterate_over_object(const JvmtiHeapwalkObject& o) {
3124 // reference to the class
3125 if (!CallbackInvoker::report_class_reference(o, o.klass()->java_mirror())) {
3126 return false;
3127 }
3128
3129 // iterate over instance fields
3130 ClassFieldMap* field_map = JvmtiCachedClassFieldMap::get_map_of_instance_fields(o.klass());
3131 for (int i=0; i<field_map->field_count(); i++) {
3132 ClassFieldDescriptor* field = field_map->field_at(i);
3133 char type = field->field_type();
3134 int slot = field->field_index();
3135 int field_offset = field->field_offset();
3136 if (o.is_flat()) {
3137 // the object is inlined, its fields are stored without the header
3138 field_offset += o.offset() - o.inline_klass()->payload_offset();
3139 }
3140 if (!is_primitive_field_type(type)) {
3141 if (field->is_flat()) {
3142 // check for possible nulls
3143 if (LayoutKindHelper::is_nullable_flat(field->layout_kind())) {
3144 address payload = cast_from_oop<address>(o.obj()) + field_offset;
3145 if (field->inline_klass()->is_payload_marked_as_null(payload)) {
3146 continue;
3147 }
3148 }
3149 JvmtiHeapwalkObject field_obj(o.obj(), field_offset, field->inline_klass(), field->layout_kind());
3150 if (!CallbackInvoker::report_field_reference(o, field_obj, slot)) {
3151 return false;
3152 }
3153 } else {
3154 oop fld_o = o.obj()->obj_field_access<AS_NO_KEEPALIVE | ON_UNKNOWN_OOP_REF>(field_offset);
3155 // ignore any objects that aren't visible to profiler
3156 if (fld_o != nullptr) {
3157 assert(Universe::heap()->is_in(fld_o), "unsafe code should not have references to Klass* anymore");
3158 if (!CallbackInvoker::report_field_reference(o, fld_o, slot)) {
3159 return false;
3160 }
3161 }
3162 }
3163 } else {
3164 if (is_reporting_primitive_fields()) {
3165 // primitive instance field
3166 address addr = cast_from_oop<address>(o.obj()) + field_offset;
3167 if (!CallbackInvoker::report_primitive_instance_field(o, slot, addr, type)) {
3168 return false;
3169 }
3170 }
3171 }
3172 }
3173
3174 // if the object is a java.lang.String
3175 if (is_reporting_string_values() &&
3176 o.klass() == vmClasses::String_klass()) {
3177 if (!CallbackInvoker::report_string_value(o)) {
3178 return false;
3179 }
3180 }
3181 return true;
3182 }
3183
3184
3185 // Collects all simple (non-stack) roots except for threads;
3186 // threads are handled in collect_stack_roots() as an optimization.
3187 // if there's a heap root callback provided then the callback is
3188 // invoked for each simple root.
3189 // if an object reference callback is provided then all simple
3190 // roots are pushed onto the marking stack so that they can be
3191 // processed later
3192 //
3193 inline bool VM_HeapWalkOperation::collect_simple_roots() {
3194 SimpleRootsClosure blk;
3195
3196 // JNI globals
3197 blk.set_kind(JVMTI_HEAP_REFERENCE_JNI_GLOBAL);
3198 JNIHandles::oops_do(&blk);
3199 if (blk.stopped()) {
3200 return false;
3201 }
3202
3203 // Preloaded classes and loader from the system dictionary
3204 CLDRootsClosure cld_roots_closure;
3205 CLDToOopClosure cld_closure(&cld_roots_closure, ClassLoaderData::_claim_none);
3206 ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
3207 if (cld_roots_closure.stopped()) {
3208 return false;
3209 }
3210
3211 // threads are now handled in collect_stack_roots()
3212
3213 // Other kinds of roots maintained by HotSpot
3214 // Many of these won't be visible but others (such as instances of important
3215 // exceptions) will be visible.
3216 blk.set_kind(JVMTI_HEAP_REFERENCE_OTHER);
3217 Universe::vm_global()->oops_do(&blk);
3218 if (blk.stopped()) {
3219 return false;
3220 }
3221
3222 return true;
3223 }
3224
3225 // Reports the thread as JVMTI_HEAP_REFERENCE_THREAD,
3226 // walks the stack of the thread, finds all references (locals
3227 // and JNI calls) and reports these as stack references.
3228 inline bool VM_HeapWalkOperation::collect_stack_refs(JavaThread* java_thread,
3229 JNILocalRootsClosure* blk)
3230 {
3231 oop threadObj = java_thread->threadObj();
3232 oop mounted_vt = java_thread->is_vthread_mounted() ? java_thread->vthread() : nullptr;
3233 if (mounted_vt != nullptr && !JvmtiEnvBase::is_vthread_alive(mounted_vt)) {
3234 mounted_vt = nullptr;
3235 }
3236 assert(threadObj != nullptr, "sanity check");
3237
3238 StackRefCollector stack_collector(tag_map(), blk, java_thread);
3239
3240 if (!java_thread->has_last_Java_frame()) {
3241 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_THREAD, threadObj)) {
3242 return false;
3243 }
3244 // no last java frame but there may be JNI locals
3245 blk->set_context(_tag_map->find(threadObj), java_lang_Thread::thread_id(threadObj), 0, (jmethodID)nullptr);
3246 java_thread->active_handles()->oops_do(blk);
3247 return !blk->stopped();
3248 }
3249 // vframes are resource allocated
3250 Thread* current_thread = Thread::current();
3251 ResourceMark rm(current_thread);
3252 HandleMark hm(current_thread);
3253
3254 RegisterMap reg_map(java_thread,
3255 RegisterMap::UpdateMap::include,
3256 RegisterMap::ProcessFrames::include,
3257 RegisterMap::WalkContinuation::include);
3258
3259 // first handle mounted vthread (if any)
3260 if (mounted_vt != nullptr) {
3261 frame f = java_thread->last_frame();
3262 vframe* vf = vframe::new_vframe(&f, ®_map, java_thread);
3263 // report virtual thread as JVMTI_HEAP_REFERENCE_OTHER
3264 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_OTHER, mounted_vt)) {
3265 return false;
3266 }
3267 // split virtual thread and carrier thread stacks by vthread entry ("enterSpecial") frame,
3268 // consider vthread entry frame as the last vthread stack frame
3269 while (vf != nullptr) {
3270 if (!stack_collector.do_frame(vf)) {
3271 return false;
3272 }
3273 if (vf->is_vthread_entry()) {
3274 break;
3275 }
3276 vf = vf->sender();
3277 }
3278 }
3279 // Platform or carrier thread.
3280 vframe* vf = JvmtiEnvBase::get_cthread_last_java_vframe(java_thread, ®_map);
3281 if (!stack_collector.set_thread(JVMTI_HEAP_REFERENCE_THREAD, threadObj)) {
3282 return false;
3283 }
3284 return stack_collector.process_frames(vf);
3285 }
3286
3287
3288 // Collects the simple roots for all threads and collects all
3289 // stack roots - for each thread it walks the execution
3290 // stack to find all references and local JNI refs.
3291 inline bool VM_HeapWalkOperation::collect_stack_roots() {
3292 JNILocalRootsClosure blk;
3293 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
3294 oop threadObj = thread->threadObj();
3295 if (threadObj != nullptr && !thread->is_exiting() && !thread->is_hidden_from_external_view()) {
3296 if (!collect_stack_refs(thread, &blk)) {
3297 return false;
3298 }
3299 }
3300 }
3301 return true;
3302 }
3303
3304 // Reports stack references for the unmounted virtual thread.
3305 inline bool VM_HeapWalkOperation::collect_vthread_stack_refs(oop vt) {
3306 if (!JvmtiEnvBase::is_vthread_alive(vt)) {
3307 return true;
3308 }
3309 ContinuationWrapper cont(java_lang_VirtualThread::continuation(vt));
3310 if (cont.is_empty()) {
3311 return true;
3312 }
3313 assert(!cont.is_mounted(), "sanity check");
3314
3315 stackChunkOop chunk = cont.last_nonempty_chunk();
3316 if (chunk == nullptr || chunk->is_empty()) {
3317 return true;
3318 }
3319
3320 // vframes are resource allocated
3321 Thread* current_thread = Thread::current();
3322 ResourceMark rm(current_thread);
3323 HandleMark hm(current_thread);
3324
3325 RegisterMap reg_map(cont.continuation(), RegisterMap::UpdateMap::include);
3326
3327 JNILocalRootsClosure blk;
3328 // JavaThread is not required for unmounted virtual threads
3329 StackRefCollector stack_collector(tag_map(), &blk, nullptr);
3330 // reference to the vthread is already reported
3331 if (!stack_collector.set_thread(vt)) {
3332 return false;
3333 }
3334
3335 frame fr = chunk->top_frame(®_map);
3336 vframe* vf = vframe::new_vframe(&fr, ®_map, nullptr);
3337 return stack_collector.process_frames(vf);
3338 }
3339
3340 // visit an object
3341 // first mark the object as visited
3342 // second get all the outbound references from this object (in other words, all
3343 // the objects referenced by this object).
3344 //
3345 bool VM_HeapWalkOperation::visit(const JvmtiHeapwalkObject& o) {
3346 // mark object as visited
3347 assert(!visit_stack()->is_visited(o), "can't visit same object more than once");
3348 visit_stack()->mark_visited(o);
3349
3350 Klass* klass = o.klass();
3351 // instance
3352 if (klass->is_instance_klass()) {
3353 if (klass == vmClasses::Class_klass()) {
3354 assert(!o.is_flat(), "Class object cannot be flattened");
3355 if (!java_lang_Class::is_primitive(o.obj())) {
3356 // a java.lang.Class
3357 return iterate_over_class(o);
3358 }
3359 } else {
3360 // we report stack references only when initial object is not specified
3361 // (in the case we start from heap roots which include platform thread stack references)
3362 if (initial_object().is_null() && java_lang_VirtualThread::is_subclass(klass)) {
3363 assert(!o.is_flat(), "VirtualThread object cannot be flattened");
3364 if (!collect_vthread_stack_refs(o.obj())) {
3365 return false;
3366 }
3367 }
3368 return iterate_over_object(o);
3369 }
3370 }
3371
3372 // flat object array
3373 if (klass->is_flatArray_klass()) {
3374 return iterate_over_flat_array(o);
3375 }
3376
3377 // object array
3378 if (klass->is_objArray_klass()) {
3379 return iterate_over_array(o);
3380 }
3381
3382 // type array
3383 if (klass->is_typeArray_klass()) {
3384 return iterate_over_type_array(o);
3385 }
3386
3387 return true;
3388 }
3389
3390 void VM_HeapWalkOperation::doit() {
3391 ResourceMark rm;
3392 ClassFieldMapCacheMark cm;
3393
3394 JvmtiTagMap::check_hashmaps_for_heapwalk(_dead_objects);
3395
3396 assert(visit_stack()->is_empty(), "visit stack must be empty");
3397
3398 // the heap walk starts with an initial object or the heap roots
3399 if (initial_object().is_null()) {
3400 // can result in a big performance boost for an agent that is
3401 // focused on analyzing references in the thread stacks.
3402 if (!collect_stack_roots()) return;
3403
3404 if (!collect_simple_roots()) return;
3405 } else {
3406 visit_stack()->push(initial_object()());
3407 }
3408
3409 // object references required
3410 if (is_following_references()) {
3411
3412 // visit each object until all reachable objects have been
3413 // visited or the callback asked to terminate the iteration.
3414 while (!visit_stack()->is_empty()) {
3415 const JvmtiHeapwalkObject o = visit_stack()->pop();
3416 if (!visit_stack()->is_visited(o)) {
3417 if (!visit(o)) {
3418 break;
3419 }
3420 }
3421 }
3422 }
3423 }
3424
3425 // iterate over all objects that are reachable from a set of roots
3426 void JvmtiTagMap::iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback,
3427 jvmtiStackReferenceCallback stack_ref_callback,
3428 jvmtiObjectReferenceCallback object_ref_callback,
3429 const void* user_data) {
3430 // VTMS transitions must be disabled before the EscapeBarrier.
3431 MountUnmountDisabler disabler;
3432
3433 JavaThread* jt = JavaThread::current();
3434 EscapeBarrier eb(true, jt);
3435 eb.deoptimize_objects_all_threads();
3436 Arena dead_object_arena(mtServiceability);
3437 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
3438
3439 {
3440 MutexLocker ml(Heap_lock);
3441 BasicHeapWalkContext context(heap_root_callback, stack_ref_callback, object_ref_callback);
3442 VM_HeapWalkOperation op(this, Handle(), context, user_data, &dead_objects);
3443 VMThread::execute(&op);
3444 }
3445 convert_flat_object_entries();
3446
3447 // Post events outside of Heap_lock
3448 post_dead_objects(&dead_objects);
3449 }
3450
3451 // iterate over all objects that are reachable from a given object
3452 void JvmtiTagMap::iterate_over_objects_reachable_from_object(jobject object,
3453 jvmtiObjectReferenceCallback object_ref_callback,
3454 const void* user_data) {
3455 oop obj = JNIHandles::resolve(object);
3456 Handle initial_object(Thread::current(), obj);
3457
3458 Arena dead_object_arena(mtServiceability);
3459 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
3460
3461 MountUnmountDisabler disabler;
3462
3463 {
3464 MutexLocker ml(Heap_lock);
3465 BasicHeapWalkContext context(nullptr, nullptr, object_ref_callback);
3466 VM_HeapWalkOperation op(this, initial_object, context, user_data, &dead_objects);
3467 VMThread::execute(&op);
3468 }
3469 convert_flat_object_entries();
3470
3471 // Post events outside of Heap_lock
3472 post_dead_objects(&dead_objects);
3473 }
3474
3475 // follow references from an initial object or the GC roots
3476 void JvmtiTagMap::follow_references(jint heap_filter,
3477 Klass* klass,
3478 jobject object,
3479 const jvmtiHeapCallbacks* callbacks,
3480 const void* user_data)
3481 {
3482 // VTMS transitions must be disabled before the EscapeBarrier.
3483 MountUnmountDisabler disabler;
3484
3485 oop obj = JNIHandles::resolve(object);
3486 JavaThread* jt = JavaThread::current();
3487 Handle initial_object(jt, obj);
3488 // EA based optimizations that are tagged or reachable from initial_object are already reverted.
3489 EscapeBarrier eb(initial_object.is_null() &&
3490 !(heap_filter & JVMTI_HEAP_FILTER_UNTAGGED),
3491 jt);
3492 eb.deoptimize_objects_all_threads();
3493
3494 Arena dead_object_arena(mtServiceability);
3495 GrowableArray<jlong> dead_objects(&dead_object_arena, 10, 0, 0);
3496
3497 {
3498 MutexLocker ml(Heap_lock);
3499 AdvancedHeapWalkContext context(heap_filter, klass, callbacks);
3500 VM_HeapWalkOperation op(this, initial_object, context, user_data, &dead_objects);
3501 VMThread::execute(&op);
3502 }
3503 convert_flat_object_entries();
3504
3505 // Post events outside of Heap_lock
3506 post_dead_objects(&dead_objects);
3507 }
3508
3509 // Verify gc_notification follows set_needs_cleaning.
3510 DEBUG_ONLY(static bool notified_needs_cleaning = false;)
3511
3512 void JvmtiTagMap::set_needs_cleaning() {
3513 assert(SafepointSynchronize::is_at_safepoint(), "called in gc pause");
3514 assert(Thread::current()->is_VM_thread(), "should be the VM thread");
3515 // Can't assert !notified_needs_cleaning; a partial GC might be upgraded
3516 // to a full GC and do this twice without intervening gc_notification.
3517 DEBUG_ONLY(notified_needs_cleaning = true;)
3518
3519 JvmtiEnvIterator it;
3520 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) {
3521 JvmtiTagMap* tag_map = env->tag_map_acquire();
3522 if (tag_map != nullptr) {
3523 tag_map->_needs_cleaning = !tag_map->is_empty();
3524 }
3525 }
3526 }
3527
3528 void JvmtiTagMap::gc_notification(size_t num_dead_entries) {
3529 assert(notified_needs_cleaning, "missing GC notification");
3530 DEBUG_ONLY(notified_needs_cleaning = false;)
3531
3532 // Notify ServiceThread if there's work to do.
3533 {
3534 MonitorLocker ml(Service_lock, Mutex::_no_safepoint_check_flag);
3535 _has_object_free_events = (num_dead_entries != 0);
3536 if (_has_object_free_events) ml.notify_all();
3537 }
3538
3539 // If no dead entries then cancel cleaning requests.
3540 if (num_dead_entries == 0) {
3541 JvmtiEnvIterator it;
3542 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) {
3543 JvmtiTagMap* tag_map = env->tag_map_acquire();
3544 if (tag_map != nullptr) {
3545 MutexLocker ml (tag_map->lock(), Mutex::_no_safepoint_check_flag);
3546 tag_map->_needs_cleaning = false;
3547 }
3548 }
3549 }
3550 }
3551
3552 // Used by ServiceThread to discover there is work to do.
3553 bool JvmtiTagMap::has_object_free_events_and_reset() {
3554 assert_lock_strong(Service_lock);
3555 bool result = _has_object_free_events;
3556 _has_object_free_events = false;
3557 return result;
3558 }
3559
3560 // Used by ServiceThread to clean up tagmaps.
3561 void JvmtiTagMap::flush_all_object_free_events() {
3562 JavaThread* thread = JavaThread::current();
3563 JvmtiEnvIterator it;
3564 for (JvmtiEnv* env = it.first(); env != nullptr; env = it.next(env)) {
3565 JvmtiTagMap* tag_map = env->tag_map_acquire();
3566 if (tag_map != nullptr) {
3567 tag_map->flush_object_free_events();
3568 ThreadBlockInVM tbiv(thread); // Be safepoint-polite while looping.
3569 }
3570 }
3571 }