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