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