1 /*
2 * Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "gc/shared/collectedHeap.hpp"
28 #include "memory/universe.hpp"
29 #include "prims/jvmtiGetLoadedClasses.hpp"
30 #include "runtime/jniHandles.inline.hpp"
31 #include "runtime/thread.hpp"
32 #include "utilities/stack.inline.hpp"
33 #if INCLUDE_ALL_GCS
34 #include "gc/g1/g1BarrierSet.hpp"
35 #endif
36
37
38 // The closure for GetLoadedClasses
39 class LoadedClassesClosure : public KlassClosure {
40 private:
41 Stack<jclass, mtInternal> _classStack;
42 JvmtiEnv* _env;
43 Thread* _cur_thread;
44
45 // Tell the GC to keep this klass alive
46 static void ensure_klass_alive(oop o) {
47 // A klass that was previously considered dead can be looked up in the
48 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
49 // or a reachable object making it alive again. The SATB part of G1 needs
50 // to get notified about this potential resurrection, otherwise the marking
51 // might not find the object.
52 #if INCLUDE_ALL_GCS
53 if (UseG1GC && o != NULL) {
54 G1BarrierSet::enqueue(o);
55 }
56 #endif
57 }
58
59 public:
60 LoadedClassesClosure(Thread* thread, JvmtiEnv* env) : _cur_thread(thread), _env(env) {
61 assert(_cur_thread == Thread::current(), "must be current thread");
62 }
63
64 void do_klass(Klass* k) {
65 // Collect all jclasses
66 _classStack.push((jclass) _env->jni_reference(Handle(_cur_thread, k->java_mirror())));
67 ensure_klass_alive(k->java_mirror());
68 }
69
70 int extract(jclass* result_list) {
71 // The size of the Stack will be 0 after extract, so get it here
72 int count = (int)_classStack.size();
73 int i = count;
74
75 // Pop all jclasses, fill backwards
76 while (!_classStack.is_empty()) {
77 result_list[--i] = _classStack.pop();
78 }
79
80 // Return the number of elements written
81 return count;
82 }
83
84 // Return current size of the Stack
85 int get_count() {
86 return (int)_classStack.size();
87 }
88 };
89
90 // The closure for GetClassLoaderClasses
91 class JvmtiGetLoadedClassesClosure : public StackObj {
92 // Since the ClassLoaderDataGraph::dictionary_all_entries_do callback
93 // doesn't pass a closureData pointer,
94 // we use a thread-local slot to hold a pointer to
95 // a stack allocated instance of this structure.
96 private:
97 jobject _initiatingLoader;
98 int _count;
99 Handle* _list;
100 int _index;
101
102 private:
103 // Getting and setting the thread local pointer
104 static JvmtiGetLoadedClassesClosure* get_this() {
105 JvmtiGetLoadedClassesClosure* result = NULL;
106 JavaThread* thread = JavaThread::current();
107 result = thread->get_jvmti_get_loaded_classes_closure();
108 return result;
109 }
110 static void set_this(JvmtiGetLoadedClassesClosure* that) {
111 JavaThread* thread = JavaThread::current();
112 thread->set_jvmti_get_loaded_classes_closure(that);
113 }
114
115 public:
116 // Constructor/Destructor
117 JvmtiGetLoadedClassesClosure() {
118 JvmtiGetLoadedClassesClosure* that = get_this();
119 assert(that == NULL, "JvmtiGetLoadedClassesClosure in use");
120 _initiatingLoader = NULL;
121 _count = 0;
122 _list = NULL;
123 _index = 0;
124 set_this(this);
125 }
126
127 JvmtiGetLoadedClassesClosure(jobject initiatingLoader) {
128 JvmtiGetLoadedClassesClosure* that = get_this();
129 assert(that == NULL, "JvmtiGetLoadedClassesClosure in use");
130 _initiatingLoader = initiatingLoader;
131 _count = 0;
132 _list = NULL;
133 _index = 0;
134 set_this(this);
135 }
136
137 ~JvmtiGetLoadedClassesClosure() {
138 JvmtiGetLoadedClassesClosure* that = get_this();
139 assert(that != NULL, "JvmtiGetLoadedClassesClosure not found");
140 set_this(NULL);
141 _initiatingLoader = NULL;
142 _count = 0;
143 if (_list != NULL) {
144 FreeHeap(_list);
145 _list = NULL;
146 }
147 _index = 0;
148 }
149
150 // Accessors.
151 jobject get_initiatingLoader() {
152 return _initiatingLoader;
153 }
154
155 int get_count() {
156 return _count;
157 }
158
159 void set_count(int value) {
160 _count = value;
161 }
162
163 Handle* get_list() {
164 return _list;
165 }
166
167 void set_list(Handle* value) {
168 _list = value;
169 }
170
171 int get_index() {
172 return _index;
173 }
174
175 void set_index(int value) {
176 _index = value;
177 }
178
179 Handle get_element(int index) {
180 if ((_list != NULL) && (index < _count)) {
181 return _list[index];
182 } else {
183 assert(false, "empty get_element");
184 return Handle();
185 }
186 }
187
188 void set_element(int index, Handle value) {
189 if ((_list != NULL) && (index < _count)) {
190 _list[index] = value;
191 } else {
192 assert(false, "bad set_element");
193 }
194 }
195
196 // Other predicates
197 bool available() {
198 return (_list != NULL);
199 }
200
201 #ifdef ASSERT
202 // For debugging.
203 void check(int limit) {
204 for (int i = 0; i < limit; i += 1) {
205 assert(Universe::heap()->is_in(get_element(i)()), "check fails");
206 }
207 }
208 #endif
209
210 // Public methods that get called within the scope of the closure
211 void allocate() {
212 _list = NEW_C_HEAP_ARRAY(Handle, _count, mtInternal);
213 assert(_list != NULL, "Out of memory");
214 if (_list == NULL) {
215 _count = 0;
216 }
217 }
218
219 void extract(JvmtiEnv *env, jclass* result) {
220 for (int index = 0; index < _count; index += 1) {
221 result[index] = (jclass) env->jni_reference(get_element(index));
222 }
223 }
224
225 static void increment_with_loader(InstanceKlass* k, ClassLoaderData* loader_data) {
226 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
227 oop class_loader = loader_data->class_loader();
228 if (class_loader == JNIHandles::resolve(that->get_initiatingLoader())) {
229 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
230 that->set_count(that->get_count() + 1);
231 }
232 }
233 }
234
235 static void add_with_loader(InstanceKlass* k, ClassLoaderData* loader_data) {
236 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
237 if (that->available()) {
238 oop class_loader = loader_data->class_loader();
239 if (class_loader == JNIHandles::resolve(that->get_initiatingLoader())) {
240 Thread *thread = Thread::current();
241 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
242 Handle mirror(thread, l->java_mirror());
243 that->set_element(that->get_index(), mirror);
244 that->set_index(that->get_index() + 1);
245 }
246 }
247 }
248 }
249
250 // increment the count for the given basic type array class (and any
251 // multi-dimensional arrays). For example, for [B we check for
252 // [[B, [[[B, .. and the count is incremented for each one that exists.
253 static void increment_for_basic_type_arrays(Klass* k) {
254 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
255 assert(that != NULL, "no JvmtiGetLoadedClassesClosure");
256 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
257 that->set_count(that->get_count() + 1);
258 }
259 }
260
261 // add the basic type array class and its multi-dimensional array classes to the list
262 static void add_for_basic_type_arrays(Klass* k) {
263 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
264 assert(that != NULL, "no JvmtiGetLoadedClassesClosure");
265 assert(that->available(), "no list");
266 Thread *thread = Thread::current();
267 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
268 Handle mirror(thread, l->java_mirror());
269 that->set_element(that->get_index(), mirror);
270 that->set_index(that->get_index() + 1);
271 }
272 }
273 };
274
275
276 jvmtiError
277 JvmtiGetLoadedClasses::getLoadedClasses(JvmtiEnv *env, jint* classCountPtr, jclass** classesPtr) {
278
279 LoadedClassesClosure closure(Thread::current(), env);
280 {
281 // To get a consistent list of classes we need MultiArray_lock to ensure
282 // array classes aren't created.
283 MutexLocker ma(MultiArray_lock);
284
285 // Iterate through all classes in ClassLoaderDataGraph
286 // and collect them using the LoadedClassesClosure
287 ClassLoaderDataGraph::loaded_classes_do(&closure);
288 }
289
290 // Return results by extracting the collected contents into a list
291 // allocated via JvmtiEnv
292 jclass* result_list;
293 jvmtiError error = env->Allocate(closure.get_count() * sizeof(jclass),
294 (unsigned char**)&result_list);
295
296 if (error == JVMTI_ERROR_NONE) {
297 int count = closure.extract(result_list);
298 *classCountPtr = count;
299 *classesPtr = result_list;
300 }
301 return error;
302 }
303
304 jvmtiError
305 JvmtiGetLoadedClasses::getClassLoaderClasses(JvmtiEnv *env, jobject initiatingLoader,
306 jint* classCountPtr, jclass** classesPtr) {
307 // Since ClassLoaderDataGraph::dictionary_all_entries_do only takes a function pointer
308 // and doesn't call back with a closure data pointer,
309 // we can only pass static methods.
310 JvmtiGetLoadedClassesClosure closure(initiatingLoader);
311 {
312 // To get a consistent list of classes we need MultiArray_lock to ensure
313 // array classes aren't created, and SystemDictionary_lock to ensure that
314 // classes aren't added to the class loader data dictionaries.
315 MutexLocker ma(MultiArray_lock);
316 MutexLocker sd(SystemDictionary_lock);
317 // First, count the classes in the class loader data dictionaries which have this loader recorded
318 // as an initiating loader. For basic type arrays this information is not recorded
319 // so GetClassLoaderClasses will return all of the basic type arrays. This is okay
320 // because the defining loader for basic type arrays is always the boot class loader
321 // and these classes are "visible" to all loaders.
322 ClassLoaderDataGraph::dictionary_all_entries_do(&JvmtiGetLoadedClassesClosure::increment_with_loader);
323 Universe::basic_type_classes_do(&JvmtiGetLoadedClassesClosure::increment_for_basic_type_arrays);
324 // Next, fill in the classes
325 closure.allocate();
326 ClassLoaderDataGraph::dictionary_all_entries_do(&JvmtiGetLoadedClassesClosure::add_with_loader);
327 Universe::basic_type_classes_do(&JvmtiGetLoadedClassesClosure::add_for_basic_type_arrays);
328 // Drop the SystemDictionary_lock, so the results could be wrong from here,
329 // but we still have a snapshot.
330 }
331 // Post results
332 jclass* result_list;
333 jvmtiError err = env->Allocate(closure.get_count() * sizeof(jclass),
334 (unsigned char**)&result_list);
335 if (err != JVMTI_ERROR_NONE) {
336 return err;
337 }
338 closure.extract(env, result_list);
339 *classCountPtr = closure.get_count();
340 *classesPtr = result_list;
341 return JVMTI_ERROR_NONE;
342 }