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 "memory/universe.inline.hpp"
28 #include "prims/jvmtiGetLoadedClasses.hpp"
29 #include "runtime/thread.hpp"
30 #if INCLUDE_ALL_GCS
31 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
32 #endif
33
34
35 // The closure for GetLoadedClasses
36 class LoadedClassesClosure : public KlassClosure {
37 private:
38 Stack<jclass, mtInternal> _classStack;
39 JvmtiEnv* _env;
40
41 // Tell the GC to keep this klass alive
42 static void ensure_klass_alive(oop o) {
43 // A klass that was previously considered dead can be looked up in the
44 // CLD/SD, and its _java_mirror or _class_loader can be stored in a root
45 // or a reachable object making it alive again. The SATB part of G1 needs
46 // to get notified about this potential resurrection, otherwise the marking
47 // might not find the object.
48 #if INCLUDE_ALL_GCS
49 if ((o != NULL) && (UseG1GC || (UseShenandoahGC && ShenandoahSATBBarrier))) {
50 G1SATBCardTableModRefBS::enqueue(o);
51 }
52 #endif
53 }
54
55 public:
56 LoadedClassesClosure(JvmtiEnv* env) {
57 _env = env;
58 }
59
60 void do_klass(Klass* k) {
61 // Collect all jclasses
62 _classStack.push((jclass) _env->jni_reference(k->java_mirror()));
63 }
64
65 int extract(jclass* result_list) {
66 // The size of the Stack will be 0 after extract, so get it here
67 int count = (int)_classStack.size();
68 int i = count;
69
70 // Pop all jclasses, fill backwards
71 while (!_classStack.is_empty()) {
72 jclass klass_handle = _classStack.pop();
73 oop klass_mirror = JNIHandles::resolve(klass_handle);
74 ensure_klass_alive(klass_mirror);
75 result_list[--i] = klass_handle;
76 }
77
78 // Return the number of elements written
79 return count;
80 }
81
82 // Return current size of the Stack
83 int get_count() {
84 return (int)_classStack.size();
85 }
86 };
87
88 // The closure for GetClassLoaderClasses
89 class JvmtiGetLoadedClassesClosure : public StackObj {
90 // Since the SystemDictionary::classes_do callback
91 // doesn't pass a closureData pointer,
92 // we use a thread-local slot to hold a pointer to
93 // a stack allocated instance of this structure.
94 private:
95 jobject _initiatingLoader;
96 int _count;
97 Handle* _list;
98 int _index;
99
100 private:
101 // Getting and setting the thread local pointer
102 static JvmtiGetLoadedClassesClosure* get_this() {
103 JvmtiGetLoadedClassesClosure* result = NULL;
104 JavaThread* thread = JavaThread::current();
105 result = thread->get_jvmti_get_loaded_classes_closure();
106 return result;
107 }
108 static void set_this(JvmtiGetLoadedClassesClosure* that) {
109 JavaThread* thread = JavaThread::current();
110 thread->set_jvmti_get_loaded_classes_closure(that);
111 }
112
113 public:
114 // Constructor/Destructor
115 JvmtiGetLoadedClassesClosure() {
116 JvmtiGetLoadedClassesClosure* that = get_this();
117 assert(that == NULL, "JvmtiGetLoadedClassesClosure in use");
118 _initiatingLoader = NULL;
119 _count = 0;
120 _list = NULL;
121 _index = 0;
122 set_this(this);
123 }
124
125 JvmtiGetLoadedClassesClosure(jobject initiatingLoader) {
126 JvmtiGetLoadedClassesClosure* that = get_this();
127 assert(that == NULL, "JvmtiGetLoadedClassesClosure in use");
128 _initiatingLoader = initiatingLoader;
129 _count = 0;
130 _list = NULL;
131 _index = 0;
132 set_this(this);
133 }
134
135 ~JvmtiGetLoadedClassesClosure() {
136 JvmtiGetLoadedClassesClosure* that = get_this();
137 assert(that != NULL, "JvmtiGetLoadedClassesClosure not found");
138 set_this(NULL);
139 _initiatingLoader = NULL;
140 _count = 0;
141 if (_list != NULL) {
142 FreeHeap(_list);
143 _list = NULL;
144 }
145 _index = 0;
146 }
147
148 // Accessors.
149 jobject get_initiatingLoader() {
150 return _initiatingLoader;
151 }
152
153 int get_count() {
154 return _count;
155 }
156
157 void set_count(int value) {
158 _count = value;
159 }
160
161 Handle* get_list() {
162 return _list;
163 }
164
165 void set_list(Handle* value) {
166 _list = value;
167 }
168
169 int get_index() {
170 return _index;
171 }
172
173 void set_index(int value) {
174 _index = value;
175 }
176
177 Handle get_element(int index) {
178 if ((_list != NULL) && (index < _count)) {
179 return _list[index];
180 } else {
181 assert(false, "empty get_element");
182 return Handle();
183 }
184 }
185
186 void set_element(int index, Handle value) {
187 if ((_list != NULL) && (index < _count)) {
188 _list[index] = value;
189 } else {
190 assert(false, "bad set_element");
191 }
192 }
193
194 // Other predicates
195 bool available() {
196 return (_list != NULL);
197 }
198
199 #ifdef ASSERT
200 // For debugging.
201 void check(int limit) {
202 for (int i = 0; i < limit; i += 1) {
203 assert(Universe::heap()->is_in(get_element(i)()), "check fails");
204 }
205 }
206 #endif
207
208 // Public methods that get called within the scope of the closure
209 void allocate() {
210 _list = NEW_C_HEAP_ARRAY(Handle, _count, mtInternal);
211 assert(_list != NULL, "Out of memory");
212 if (_list == NULL) {
213 _count = 0;
214 }
215 }
216
217 void extract(JvmtiEnv *env, jclass* result) {
218 for (int index = 0; index < _count; index += 1) {
219 result[index] = (jclass) env->jni_reference(get_element(index));
220 }
221 }
222
223 static void increment_with_loader(Klass* k, ClassLoaderData* loader_data) {
224 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
225 oop class_loader = loader_data->class_loader();
226 if (class_loader == JNIHandles::resolve(that->get_initiatingLoader())) {
227 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
228 that->set_count(that->get_count() + 1);
229 }
230 }
231 }
232
233 static void prim_array_increment_with_loader(Klass* array, ClassLoaderData* loader_data) {
234 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
235 oop class_loader = loader_data->class_loader();
236 if (class_loader == JNIHandles::resolve(that->get_initiatingLoader())) {
237 that->set_count(that->get_count() + 1);
238 }
239 }
240
241 static void add_with_loader(Klass* k, ClassLoaderData* loader_data) {
242 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
243 if (that->available()) {
244 oop class_loader = loader_data->class_loader();
245 if (class_loader == JNIHandles::resolve(that->get_initiatingLoader())) {
246 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
247 oop mirror = l->java_mirror();
248 that->set_element(that->get_index(), mirror);
249 that->set_index(that->get_index() + 1);
250 }
251 }
252 }
253 }
254
255 // increment the count for the given basic type array class (and any
256 // multi-dimensional arrays). For example, for [B we check for
257 // [[B, [[[B, .. and the count is incremented for each one that exists.
258 static void increment_for_basic_type_arrays(Klass* k) {
259 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
260 assert(that != NULL, "no JvmtiGetLoadedClassesClosure");
261 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
262 that->set_count(that->get_count() + 1);
263 }
264 }
265
266 // add the basic type array class and its multi-dimensional array classes to the list
267 static void add_for_basic_type_arrays(Klass* k) {
268 JvmtiGetLoadedClassesClosure* that = JvmtiGetLoadedClassesClosure::get_this();
269 assert(that != NULL, "no JvmtiGetLoadedClassesClosure");
270 assert(that->available(), "no list");
271 for (Klass* l = k; l != NULL; l = l->array_klass_or_null()) {
272 oop mirror = l->java_mirror();
273 that->set_element(that->get_index(), mirror);
274 that->set_index(that->get_index() + 1);
275 }
276 }
277 };
278
279
280 jvmtiError
281 JvmtiGetLoadedClasses::getLoadedClasses(JvmtiEnv *env, jint* classCountPtr, jclass** classesPtr) {
282
283 LoadedClassesClosure closure(env);
284 {
285 // To get a consistent list of classes we need MultiArray_lock to ensure
286 // array classes aren't created.
287 MutexLocker ma(MultiArray_lock);
288
289 // Iterate through all classes in ClassLoaderDataGraph
290 // and collect them using the LoadedClassesClosure
291 ClassLoaderDataGraph::loaded_classes_do(&closure);
292 }
293
294 // Return results by extracting the collected contents into a list
295 // allocated via JvmtiEnv
296 jclass* result_list;
297 jvmtiError error = env->Allocate(closure.get_count() * sizeof(jclass),
298 (unsigned char**)&result_list);
299
300 if (error == JVMTI_ERROR_NONE) {
301 int count = closure.extract(result_list);
302 *classCountPtr = count;
303 *classesPtr = result_list;
304 }
305 return error;
306 }
307
308 jvmtiError
309 JvmtiGetLoadedClasses::getClassLoaderClasses(JvmtiEnv *env, jobject initiatingLoader,
310 jint* classCountPtr, jclass** classesPtr) {
311 // Since SystemDictionary::classes_do only takes a function pointer
312 // and doesn't call back with a closure data pointer,
313 // we can only pass static methods.
314 JvmtiGetLoadedClassesClosure closure(initiatingLoader);
315 {
316 // To get a consistent list of classes we need MultiArray_lock to ensure
317 // array classes aren't created, and SystemDictionary_lock to ensure that
318 // classes aren't added to the system dictionary,
319 MutexLocker ma(MultiArray_lock);
320 MutexLocker sd(SystemDictionary_lock);
321 // First, count the classes in the system dictionary which have this loader recorded
322 // as an initiating loader. For basic type arrays this information is not recorded
323 // so GetClassLoaderClasses will return all of the basic type arrays. This is okay
324 // because the defining loader for basic type arrays is always the boot class loader
325 // and these classes are "visible" to all loaders.
326 SystemDictionary::classes_do(&JvmtiGetLoadedClassesClosure::increment_with_loader);
327 Universe::basic_type_classes_do(&JvmtiGetLoadedClassesClosure::increment_for_basic_type_arrays);
328 // Next, fill in the classes
329 closure.allocate();
330 SystemDictionary::classes_do(&JvmtiGetLoadedClassesClosure::add_with_loader);
331 Universe::basic_type_classes_do(&JvmtiGetLoadedClassesClosure::add_for_basic_type_arrays);
332 // Drop the SystemDictionary_lock, so the results could be wrong from here,
333 // but we still have a snapshot.
334 }
335 // Post results
336 jclass* result_list;
337 jvmtiError err = env->Allocate(closure.get_count() * sizeof(jclass),
338 (unsigned char**)&result_list);
339 if (err != JVMTI_ERROR_NONE) {
340 return err;
341 }
342 closure.extract(env, result_list);
343 *classCountPtr = closure.get_count();
344 *classesPtr = result_list;
345 return JVMTI_ERROR_NONE;
346 }