133
134 ///// Data read/writes on the Java heap and in native (off-heap) memory
135
136 /**
137 * Helper class for accessing memory.
138 *
139 * Normalizes values and wraps accesses in
140 * JavaThread::doing_unsafe_access() if needed.
141 */
142 class MemoryAccess : StackObj {
143 JavaThread* _thread;
144 jobject _obj;
145 jlong _offset;
146
147 // Resolves and returns the address of the memory access
148 void* addr() {
149 return index_oop_from_field_offset_long(JNIHandles::resolve(_obj), _offset);
150 }
151
152 template <typename T>
153 T normalize(T x) {
154 return x;
155 }
156
157 jboolean normalize(jboolean x) {
158 return x & 1;
159 }
160
161 /**
162 * Helper class to wrap memory accesses in JavaThread::doing_unsafe_access()
163 */
164 class GuardUnsafeAccess {
165 JavaThread* _thread;
166 bool _active;
167
168 public:
169 GuardUnsafeAccess(JavaThread* thread, jobject _obj) : _thread(thread) {
170 if (JNIHandles::resolve(_obj) == NULL) {
171 // native/off-heap access which may raise SIGBUS if accessing
172 // memory mapped file data in a region of the file which has
173 // been truncated and is now invalid
174 _thread->set_doing_unsafe_access(true);
175 _active = true;
176 } else {
177 _active = false;
178 }
179 }
180
181 ~GuardUnsafeAccess() {
182 if (_active) {
183 _thread->set_doing_unsafe_access(false);
184 }
185 }
186 };
187
188 public:
189 MemoryAccess(JavaThread* thread, jobject obj, jlong offset)
190 : _thread(thread), _obj(obj), _offset(offset) {
191 }
192
193 template <typename T>
194 T get() {
195 GuardUnsafeAccess guard(_thread, _obj);
196
197 T* p = (T*)addr();
198
199 T x = *p;
200
201 return x;
202 }
203
204 template <typename T>
205 void put(T x) {
206 GuardUnsafeAccess guard(_thread, _obj);
207
208 T* p = (T*)addr();
209
210 *p = normalize(x);
211 }
212
213
214 template <typename T>
215 T get_volatile() {
216 GuardUnsafeAccess guard(_thread, _obj);
217
218 T* p = (T*)addr();
219
220 if (support_IRIW_for_not_multiple_copy_atomic_cpu) {
221 OrderAccess::fence();
222 }
223
224 T x = OrderAccess::load_acquire((volatile T*)p);
225
226 return x;
227 }
228
229 template <typename T>
230 void put_volatile(T x) {
231 GuardUnsafeAccess guard(_thread, _obj);
232
233 T* p = (T*)addr();
234
235 OrderAccess::release_store_fence((volatile T*)p, normalize(x));
236 }
237
238
239 #ifndef SUPPORTS_NATIVE_CX8
240 jlong get_jlong_locked() {
241 GuardUnsafeAccess guard(_thread, _obj);
242
243 MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
244
245 jlong* p = (jlong*)addr();
246
247 jlong x = Atomic::load(p);
248
249 return x;
250 }
251
252 void put_jlong_locked(jlong x) {
253 GuardUnsafeAccess guard(_thread, _obj);
254
255 MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
256
257 jlong* p = (jlong*)addr();
258
259 Atomic::store(normalize(x), p);
260 }
261 #endif
262 };
263
264 // Get/PutObject must be special-cased, since it works with handles.
265
266 // These functions allow a null base pointer with an arbitrary address.
267 // But if the base pointer is non-null, the offset should make some sense.
268 // That is, it should be in the range [0, MAX_OBJECT_SIZE].
269 UNSAFE_ENTRY(jobject, Unsafe_GetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
270 oop p = JNIHandles::resolve(obj);
271 oop v;
272
273 if (UseCompressedOops) {
274 narrowOop n = *(narrowOop*)index_oop_from_field_offset_long(p, offset);
275 v = oopDesc::decode_heap_oop(n);
276 } else {
277 v = *(oop*)index_oop_from_field_offset_long(p, offset);
278 }
279
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133
134 ///// Data read/writes on the Java heap and in native (off-heap) memory
135
136 /**
137 * Helper class for accessing memory.
138 *
139 * Normalizes values and wraps accesses in
140 * JavaThread::doing_unsafe_access() if needed.
141 */
142 class MemoryAccess : StackObj {
143 JavaThread* _thread;
144 jobject _obj;
145 jlong _offset;
146
147 // Resolves and returns the address of the memory access
148 void* addr() {
149 return index_oop_from_field_offset_long(JNIHandles::resolve(_obj), _offset);
150 }
151
152 template <typename T>
153 T normalize_for_write(T x) {
154 return x;
155 }
156
157 jboolean normalize_for_write(jboolean x) {
158 return x & 1;
159 }
160
161 template <typename T>
162 T normalize_for_read(T x) {
163 return x;
164 }
165
166 jboolean normalize_for_read(jboolean x) {
167 return x != 0;
168 }
169
170 /**
171 * Helper class to wrap memory accesses in JavaThread::doing_unsafe_access()
172 */
173 class GuardUnsafeAccess {
174 JavaThread* _thread;
175 bool _active;
176
177 public:
178 GuardUnsafeAccess(JavaThread* thread, jobject _obj) : _thread(thread) {
179 if (JNIHandles::resolve(_obj) == NULL) {
180 // native/off-heap access which may raise SIGBUS if accessing
181 // memory mapped file data in a region of the file which has
182 // been truncated and is now invalid
183 _thread->set_doing_unsafe_access(true);
184 _active = true;
185 } else {
186 _active = false;
187 }
188 }
189
190 ~GuardUnsafeAccess() {
191 if (_active) {
192 _thread->set_doing_unsafe_access(false);
193 }
194 }
195 };
196
197 public:
198 MemoryAccess(JavaThread* thread, jobject obj, jlong offset)
199 : _thread(thread), _obj(obj), _offset(offset) {
200 }
201
202 template <typename T>
203 T get() {
204 GuardUnsafeAccess guard(_thread, _obj);
205
206 T* p = (T*)addr();
207
208 T x = normalize_for_read(*p);
209
210 return x;
211 }
212
213 template <typename T>
214 void put(T x) {
215 GuardUnsafeAccess guard(_thread, _obj);
216
217 T* p = (T*)addr();
218
219 *p = normalize_for_write(x);
220 }
221
222
223 template <typename T>
224 T get_volatile() {
225 GuardUnsafeAccess guard(_thread, _obj);
226
227 T* p = (T*)addr();
228
229 if (support_IRIW_for_not_multiple_copy_atomic_cpu) {
230 OrderAccess::fence();
231 }
232
233 T x = OrderAccess::load_acquire((volatile T*)p);
234
235 return normalize_for_read(x);
236 }
237
238 template <typename T>
239 void put_volatile(T x) {
240 GuardUnsafeAccess guard(_thread, _obj);
241
242 T* p = (T*)addr();
243
244 OrderAccess::release_store_fence((volatile T*)p, normalize_for_write(x));
245 }
246
247
248 #ifndef SUPPORTS_NATIVE_CX8
249 jlong get_jlong_locked() {
250 GuardUnsafeAccess guard(_thread, _obj);
251
252 MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
253
254 jlong* p = (jlong*)addr();
255
256 jlong x = Atomic::load(p);
257
258 return x;
259 }
260
261 void put_jlong_locked(jlong x) {
262 GuardUnsafeAccess guard(_thread, _obj);
263
264 MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
265
266 jlong* p = (jlong*)addr();
267
268 Atomic::store(normalize_for_write(x), p);
269 }
270 #endif
271 };
272
273 // Get/PutObject must be special-cased, since it works with handles.
274
275 // These functions allow a null base pointer with an arbitrary address.
276 // But if the base pointer is non-null, the offset should make some sense.
277 // That is, it should be in the range [0, MAX_OBJECT_SIZE].
278 UNSAFE_ENTRY(jobject, Unsafe_GetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
279 oop p = JNIHandles::resolve(obj);
280 oop v;
281
282 if (UseCompressedOops) {
283 narrowOop n = *(narrowOop*)index_oop_from_field_offset_long(p, offset);
284 v = oopDesc::decode_heap_oop(n);
285 } else {
286 v = *(oop*)index_oop_from_field_offset_long(p, offset);
287 }
288
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