1 /*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "locks.h"
18
19 #include <errno.h>
20 #include <sys/time.h>
21
22 #include "android-base/logging.h"
23
24 #include "base/atomic.h"
25 #include "base/logging.h"
26 #include "base/systrace.h"
27 #include "base/time_utils.h"
28 #include "base/value_object.h"
29 #include "mutex-inl.h"
30 #include "scoped_thread_state_change-inl.h"
31 #include "thread-inl.h"
32
33 namespace art {
34
35 static Atomic<Locks::ClientCallback*> safe_to_call_abort_callback(nullptr);
36
37 Mutex* Locks::abort_lock_ = nullptr;
38 Mutex* Locks::alloc_tracker_lock_ = nullptr;
39 Mutex* Locks::allocated_monitor_ids_lock_ = nullptr;
40 Mutex* Locks::allocated_thread_ids_lock_ = nullptr;
41 ReaderWriterMutex* Locks::breakpoint_lock_ = nullptr;
42 ReaderWriterMutex* Locks::classlinker_classes_lock_ = nullptr;
43 Mutex* Locks::custom_tls_lock_ = nullptr;
44 Mutex* Locks::deoptimization_lock_ = nullptr;
45 ReaderWriterMutex* Locks::heap_bitmap_lock_ = nullptr;
46 Mutex* Locks::instrument_entrypoints_lock_ = nullptr;
47 Mutex* Locks::intern_table_lock_ = nullptr;
48 Mutex* Locks::jni_function_table_lock_ = nullptr;
49 Mutex* Locks::jni_libraries_lock_ = nullptr;
50 Mutex* Locks::logging_lock_ = nullptr;
51 Mutex* Locks::modify_ldt_lock_ = nullptr;
52 MutatorMutex* Locks::mutator_lock_ = nullptr;
53 Mutex* Locks::profiler_lock_ = nullptr;
54 ReaderWriterMutex* Locks::verifier_deps_lock_ = nullptr;
55 ReaderWriterMutex* Locks::oat_file_manager_lock_ = nullptr;
56 Mutex* Locks::host_dlopen_handles_lock_ = nullptr;
57 Mutex* Locks::reference_processor_lock_ = nullptr;
58 Mutex* Locks::reference_queue_cleared_references_lock_ = nullptr;
59 Mutex* Locks::reference_queue_finalizer_references_lock_ = nullptr;
60 Mutex* Locks::reference_queue_phantom_references_lock_ = nullptr;
61 Mutex* Locks::reference_queue_soft_references_lock_ = nullptr;
62 Mutex* Locks::reference_queue_weak_references_lock_ = nullptr;
63 Mutex* Locks::runtime_shutdown_lock_ = nullptr;
64 Mutex* Locks::runtime_thread_pool_lock_ = nullptr;
65 Mutex* Locks::cha_lock_ = nullptr;
66 Mutex* Locks::jit_lock_ = nullptr;
67 Mutex* Locks::subtype_check_lock_ = nullptr;
68 Mutex* Locks::thread_list_lock_ = nullptr;
69 ConditionVariable* Locks::thread_exit_cond_ = nullptr;
70 Mutex* Locks::thread_suspend_count_lock_ = nullptr;
71 Mutex* Locks::trace_lock_ = nullptr;
72 Mutex* Locks::unexpected_signal_lock_ = nullptr;
73 Mutex* Locks::user_code_suspension_lock_ = nullptr;
74 Uninterruptible Roles::uninterruptible_;
75 ReaderWriterMutex* Locks::jni_globals_lock_ = nullptr;
76 Mutex* Locks::jni_weak_globals_lock_ = nullptr;
77 ReaderWriterMutex* Locks::dex_lock_ = nullptr;
78 Mutex* Locks::native_debug_interface_lock_ = nullptr;
79 ReaderWriterMutex* Locks::jni_id_lock_ = nullptr;
80 std::vector<BaseMutex*> Locks::expected_mutexes_on_weak_ref_access_;
81 Atomic<const BaseMutex*> Locks::expected_mutexes_on_weak_ref_access_guard_;
82
83 // Wait for an amount of time that roughly increases in the argument i.
84 // Spin for small arguments and yield/sleep for longer ones.
BackOff(uint32_t i)85 static void BackOff(uint32_t i) {
86 static constexpr uint32_t kSpinMax = 10;
87 static constexpr uint32_t kYieldMax = 20;
88 if (i <= kSpinMax) {
89 // TODO: Esp. in very latency-sensitive cases, consider replacing this with an explicit
90 // test-and-test-and-set loop in the caller. Possibly skip entirely on a uniprocessor.
91 volatile uint32_t x = 0;
92 const uint32_t spin_count = 10 * i;
93 for (uint32_t spin = 0; spin < spin_count; ++spin) {
94 ++x; // Volatile; hence should not be optimized away.
95 }
96 // TODO: Consider adding x86 PAUSE and/or ARM YIELD here.
97 } else if (i <= kYieldMax) {
98 sched_yield();
99 } else {
100 NanoSleep(1000ull * (i - kYieldMax));
101 }
102 }
103
104 class Locks::ScopedExpectedMutexesOnWeakRefAccessLock final {
105 public:
ScopedExpectedMutexesOnWeakRefAccessLock(const BaseMutex * mutex)106 explicit ScopedExpectedMutexesOnWeakRefAccessLock(const BaseMutex* mutex) : mutex_(mutex) {
107 for (uint32_t i = 0;
108 !Locks::expected_mutexes_on_weak_ref_access_guard_.CompareAndSetWeakAcquire(nullptr,
109 mutex);
110 ++i) {
111 BackOff(i);
112 }
113 }
114
~ScopedExpectedMutexesOnWeakRefAccessLock()115 ~ScopedExpectedMutexesOnWeakRefAccessLock() {
116 DCHECK_EQ(Locks::expected_mutexes_on_weak_ref_access_guard_.load(std::memory_order_relaxed),
117 mutex_);
118 Locks::expected_mutexes_on_weak_ref_access_guard_.store(nullptr, std::memory_order_release);
119 }
120
121 private:
122 const BaseMutex* const mutex_;
123 };
124
Init()125 void Locks::Init() {
126 if (logging_lock_ != nullptr) {
127 // Already initialized.
128 if (kRuntimeISA == InstructionSet::kX86 || kRuntimeISA == InstructionSet::kX86_64) {
129 DCHECK(modify_ldt_lock_ != nullptr);
130 } else {
131 DCHECK(modify_ldt_lock_ == nullptr);
132 }
133 DCHECK(abort_lock_ != nullptr);
134 DCHECK(alloc_tracker_lock_ != nullptr);
135 DCHECK(allocated_monitor_ids_lock_ != nullptr);
136 DCHECK(allocated_thread_ids_lock_ != nullptr);
137 DCHECK(breakpoint_lock_ != nullptr);
138 DCHECK(classlinker_classes_lock_ != nullptr);
139 DCHECK(custom_tls_lock_ != nullptr);
140 DCHECK(deoptimization_lock_ != nullptr);
141 DCHECK(heap_bitmap_lock_ != nullptr);
142 DCHECK(oat_file_manager_lock_ != nullptr);
143 DCHECK(verifier_deps_lock_ != nullptr);
144 DCHECK(host_dlopen_handles_lock_ != nullptr);
145 DCHECK(intern_table_lock_ != nullptr);
146 DCHECK(jni_function_table_lock_ != nullptr);
147 DCHECK(jni_libraries_lock_ != nullptr);
148 DCHECK(logging_lock_ != nullptr);
149 DCHECK(mutator_lock_ != nullptr);
150 DCHECK(profiler_lock_ != nullptr);
151 DCHECK(cha_lock_ != nullptr);
152 DCHECK(jit_lock_ != nullptr);
153 DCHECK(subtype_check_lock_ != nullptr);
154 DCHECK(thread_list_lock_ != nullptr);
155 DCHECK(thread_suspend_count_lock_ != nullptr);
156 DCHECK(trace_lock_ != nullptr);
157 DCHECK(unexpected_signal_lock_ != nullptr);
158 DCHECK(user_code_suspension_lock_ != nullptr);
159 DCHECK(dex_lock_ != nullptr);
160 DCHECK(native_debug_interface_lock_ != nullptr);
161 DCHECK(jni_id_lock_ != nullptr);
162 DCHECK(runtime_thread_pool_lock_ != nullptr);
163 } else {
164 // Create global locks in level order from highest lock level to lowest.
165 LockLevel current_lock_level = kUserCodeSuspensionLock;
166 DCHECK(user_code_suspension_lock_ == nullptr);
167 user_code_suspension_lock_ = new Mutex("user code suspension lock", current_lock_level);
168
169 #define UPDATE_CURRENT_LOCK_LEVEL(new_level) \
170 if ((new_level) >= current_lock_level) { \
171 /* Do not use CHECKs or FATAL here, abort_lock_ is not setup yet. */ \
172 fprintf(stderr, "New local level %d is not less than current level %d\n", \
173 new_level, current_lock_level); \
174 exit(1); \
175 } \
176 current_lock_level = new_level;
177
178 UPDATE_CURRENT_LOCK_LEVEL(kInstrumentEntrypointsLock);
179 DCHECK(instrument_entrypoints_lock_ == nullptr);
180 instrument_entrypoints_lock_ = new Mutex("instrument entrypoint lock", current_lock_level);
181
182 UPDATE_CURRENT_LOCK_LEVEL(kMutatorLock);
183 DCHECK(mutator_lock_ == nullptr);
184 mutator_lock_ = new MutatorMutex("mutator lock", current_lock_level);
185
186 UPDATE_CURRENT_LOCK_LEVEL(kHeapBitmapLock);
187 DCHECK(heap_bitmap_lock_ == nullptr);
188 heap_bitmap_lock_ = new ReaderWriterMutex("heap bitmap lock", current_lock_level);
189
190 UPDATE_CURRENT_LOCK_LEVEL(kTraceLock);
191 DCHECK(trace_lock_ == nullptr);
192 trace_lock_ = new Mutex("trace lock", current_lock_level);
193
194 UPDATE_CURRENT_LOCK_LEVEL(kRuntimeShutdownLock);
195 DCHECK(runtime_shutdown_lock_ == nullptr);
196 runtime_shutdown_lock_ = new Mutex("runtime shutdown lock", current_lock_level);
197
198 UPDATE_CURRENT_LOCK_LEVEL(kRuntimeThreadPoolLock);
199 DCHECK(runtime_thread_pool_lock_ == nullptr);
200 runtime_thread_pool_lock_ = new Mutex("runtime thread pool lock", current_lock_level);
201
202 UPDATE_CURRENT_LOCK_LEVEL(kProfilerLock);
203 DCHECK(profiler_lock_ == nullptr);
204 profiler_lock_ = new Mutex("profiler lock", current_lock_level);
205
206 UPDATE_CURRENT_LOCK_LEVEL(kDeoptimizationLock);
207 DCHECK(deoptimization_lock_ == nullptr);
208 deoptimization_lock_ = new Mutex("Deoptimization lock", current_lock_level);
209
210 UPDATE_CURRENT_LOCK_LEVEL(kAllocTrackerLock);
211 DCHECK(alloc_tracker_lock_ == nullptr);
212 alloc_tracker_lock_ = new Mutex("AllocTracker lock", current_lock_level);
213
214 UPDATE_CURRENT_LOCK_LEVEL(kThreadListLock);
215 DCHECK(thread_list_lock_ == nullptr);
216 thread_list_lock_ = new Mutex("thread list lock", current_lock_level);
217
218 UPDATE_CURRENT_LOCK_LEVEL(kJniLoadLibraryLock);
219 DCHECK(jni_libraries_lock_ == nullptr);
220 jni_libraries_lock_ = new Mutex("JNI shared libraries map lock", current_lock_level);
221
222 UPDATE_CURRENT_LOCK_LEVEL(kBreakpointLock);
223 DCHECK(breakpoint_lock_ == nullptr);
224 breakpoint_lock_ = new ReaderWriterMutex("breakpoint lock", current_lock_level);
225
226 UPDATE_CURRENT_LOCK_LEVEL(kSubtypeCheckLock);
227 DCHECK(subtype_check_lock_ == nullptr);
228 subtype_check_lock_ = new Mutex("SubtypeCheck lock", current_lock_level);
229
230 UPDATE_CURRENT_LOCK_LEVEL(kClassLinkerClassesLock);
231 DCHECK(classlinker_classes_lock_ == nullptr);
232 classlinker_classes_lock_ = new ReaderWriterMutex("ClassLinker classes lock",
233 current_lock_level);
234
235 UPDATE_CURRENT_LOCK_LEVEL(kMonitorPoolLock);
236 DCHECK(allocated_monitor_ids_lock_ == nullptr);
237 allocated_monitor_ids_lock_ = new Mutex("allocated monitor ids lock", current_lock_level);
238
239 UPDATE_CURRENT_LOCK_LEVEL(kAllocatedThreadIdsLock);
240 DCHECK(allocated_thread_ids_lock_ == nullptr);
241 allocated_thread_ids_lock_ = new Mutex("allocated thread ids lock", current_lock_level);
242
243 if (kRuntimeISA == InstructionSet::kX86 || kRuntimeISA == InstructionSet::kX86_64) {
244 UPDATE_CURRENT_LOCK_LEVEL(kModifyLdtLock);
245 DCHECK(modify_ldt_lock_ == nullptr);
246 modify_ldt_lock_ = new Mutex("modify_ldt lock", current_lock_level);
247 }
248
249 UPDATE_CURRENT_LOCK_LEVEL(kDexLock);
250 DCHECK(dex_lock_ == nullptr);
251 dex_lock_ = new ReaderWriterMutex("ClassLinker dex lock", current_lock_level);
252
253 UPDATE_CURRENT_LOCK_LEVEL(kOatFileManagerLock);
254 DCHECK(oat_file_manager_lock_ == nullptr);
255 oat_file_manager_lock_ = new ReaderWriterMutex("OatFile manager lock", current_lock_level);
256
257 UPDATE_CURRENT_LOCK_LEVEL(kVerifierDepsLock);
258 DCHECK(verifier_deps_lock_ == nullptr);
259 verifier_deps_lock_ = new ReaderWriterMutex("verifier deps lock", current_lock_level);
260
261 UPDATE_CURRENT_LOCK_LEVEL(kHostDlOpenHandlesLock);
262 DCHECK(host_dlopen_handles_lock_ == nullptr);
263 host_dlopen_handles_lock_ = new Mutex("host dlopen handles lock", current_lock_level);
264
265 UPDATE_CURRENT_LOCK_LEVEL(kInternTableLock);
266 DCHECK(intern_table_lock_ == nullptr);
267 intern_table_lock_ = new Mutex("InternTable lock", current_lock_level);
268
269 UPDATE_CURRENT_LOCK_LEVEL(kReferenceProcessorLock);
270 DCHECK(reference_processor_lock_ == nullptr);
271 reference_processor_lock_ = new Mutex("ReferenceProcessor lock", current_lock_level);
272
273 UPDATE_CURRENT_LOCK_LEVEL(kReferenceQueueClearedReferencesLock);
274 DCHECK(reference_queue_cleared_references_lock_ == nullptr);
275 reference_queue_cleared_references_lock_ = new Mutex("ReferenceQueue cleared references lock", current_lock_level);
276
277 UPDATE_CURRENT_LOCK_LEVEL(kReferenceQueueWeakReferencesLock);
278 DCHECK(reference_queue_weak_references_lock_ == nullptr);
279 reference_queue_weak_references_lock_ = new Mutex("ReferenceQueue cleared references lock", current_lock_level);
280
281 UPDATE_CURRENT_LOCK_LEVEL(kReferenceQueueFinalizerReferencesLock);
282 DCHECK(reference_queue_finalizer_references_lock_ == nullptr);
283 reference_queue_finalizer_references_lock_ = new Mutex("ReferenceQueue finalizer references lock", current_lock_level);
284
285 UPDATE_CURRENT_LOCK_LEVEL(kReferenceQueuePhantomReferencesLock);
286 DCHECK(reference_queue_phantom_references_lock_ == nullptr);
287 reference_queue_phantom_references_lock_ = new Mutex("ReferenceQueue phantom references lock", current_lock_level);
288
289 UPDATE_CURRENT_LOCK_LEVEL(kReferenceQueueSoftReferencesLock);
290 DCHECK(reference_queue_soft_references_lock_ == nullptr);
291 reference_queue_soft_references_lock_ = new Mutex("ReferenceQueue soft references lock", current_lock_level);
292
293 UPDATE_CURRENT_LOCK_LEVEL(kJniGlobalsLock);
294 DCHECK(jni_globals_lock_ == nullptr);
295 jni_globals_lock_ =
296 new ReaderWriterMutex("JNI global reference table lock", current_lock_level);
297
298 UPDATE_CURRENT_LOCK_LEVEL(kJniWeakGlobalsLock);
299 DCHECK(jni_weak_globals_lock_ == nullptr);
300 jni_weak_globals_lock_ = new Mutex("JNI weak global reference table lock", current_lock_level);
301
302 UPDATE_CURRENT_LOCK_LEVEL(kJniFunctionTableLock);
303 DCHECK(jni_function_table_lock_ == nullptr);
304 jni_function_table_lock_ = new Mutex("JNI function table lock", current_lock_level);
305
306 UPDATE_CURRENT_LOCK_LEVEL(kCustomTlsLock);
307 DCHECK(custom_tls_lock_ == nullptr);
308 custom_tls_lock_ = new Mutex("Thread::custom_tls_ lock", current_lock_level);
309
310 UPDATE_CURRENT_LOCK_LEVEL(kJitCodeCacheLock);
311 DCHECK(jit_lock_ == nullptr);
312 jit_lock_ = new Mutex("Jit code cache", current_lock_level);
313
314 UPDATE_CURRENT_LOCK_LEVEL(kCHALock);
315 DCHECK(cha_lock_ == nullptr);
316 cha_lock_ = new Mutex("CHA lock", current_lock_level);
317
318 UPDATE_CURRENT_LOCK_LEVEL(kNativeDebugInterfaceLock);
319 DCHECK(native_debug_interface_lock_ == nullptr);
320 native_debug_interface_lock_ = new Mutex("Native debug interface lock", current_lock_level);
321
322 UPDATE_CURRENT_LOCK_LEVEL(kJniIdLock);
323 DCHECK(jni_id_lock_ == nullptr);
324 jni_id_lock_ = new ReaderWriterMutex("JNI id map lock", current_lock_level);
325
326 UPDATE_CURRENT_LOCK_LEVEL(kAbortLock);
327 DCHECK(abort_lock_ == nullptr);
328 abort_lock_ = new Mutex("abort lock", current_lock_level, true);
329
330 UPDATE_CURRENT_LOCK_LEVEL(kThreadSuspendCountLock);
331 DCHECK(thread_suspend_count_lock_ == nullptr);
332 thread_suspend_count_lock_ = new Mutex("thread suspend count lock", current_lock_level);
333
334 UPDATE_CURRENT_LOCK_LEVEL(kUnexpectedSignalLock);
335 DCHECK(unexpected_signal_lock_ == nullptr);
336 unexpected_signal_lock_ = new Mutex("unexpected signal lock", current_lock_level, true);
337
338 UPDATE_CURRENT_LOCK_LEVEL(kLoggingLock);
339 DCHECK(logging_lock_ == nullptr);
340 logging_lock_ = new Mutex("logging lock", current_lock_level, true);
341
342 #undef UPDATE_CURRENT_LOCK_LEVEL
343
344 // List of mutexes that we may hold when accessing a weak ref.
345 AddToExpectedMutexesOnWeakRefAccess(dex_lock_, /*need_lock=*/ false);
346 AddToExpectedMutexesOnWeakRefAccess(classlinker_classes_lock_, /*need_lock=*/ false);
347 AddToExpectedMutexesOnWeakRefAccess(jni_libraries_lock_, /*need_lock=*/ false);
348
349 InitConditions();
350 }
351 }
352
InitConditions()353 void Locks::InitConditions() {
354 thread_exit_cond_ = new ConditionVariable("thread exit condition variable", *thread_list_lock_);
355 }
356
SetClientCallback(ClientCallback * safe_to_call_abort_cb)357 void Locks::SetClientCallback(ClientCallback* safe_to_call_abort_cb) {
358 safe_to_call_abort_callback.store(safe_to_call_abort_cb, std::memory_order_release);
359 }
360
361 // Helper to allow checking shutdown while ignoring locking requirements.
IsSafeToCallAbortRacy()362 bool Locks::IsSafeToCallAbortRacy() {
363 Locks::ClientCallback* safe_to_call_abort_cb =
364 safe_to_call_abort_callback.load(std::memory_order_acquire);
365 return safe_to_call_abort_cb != nullptr && safe_to_call_abort_cb();
366 }
367
AddToExpectedMutexesOnWeakRefAccess(BaseMutex * mutex,bool need_lock)368 void Locks::AddToExpectedMutexesOnWeakRefAccess(BaseMutex* mutex, bool need_lock) {
369 if (need_lock) {
370 ScopedExpectedMutexesOnWeakRefAccessLock mu(mutex);
371 mutex->SetShouldRespondToEmptyCheckpointRequest(true);
372 expected_mutexes_on_weak_ref_access_.push_back(mutex);
373 } else {
374 mutex->SetShouldRespondToEmptyCheckpointRequest(true);
375 expected_mutexes_on_weak_ref_access_.push_back(mutex);
376 }
377 }
378
RemoveFromExpectedMutexesOnWeakRefAccess(BaseMutex * mutex,bool need_lock)379 void Locks::RemoveFromExpectedMutexesOnWeakRefAccess(BaseMutex* mutex, bool need_lock) {
380 if (need_lock) {
381 ScopedExpectedMutexesOnWeakRefAccessLock mu(mutex);
382 mutex->SetShouldRespondToEmptyCheckpointRequest(false);
383 std::vector<BaseMutex*>& list = expected_mutexes_on_weak_ref_access_;
384 auto it = std::find(list.begin(), list.end(), mutex);
385 DCHECK(it != list.end());
386 list.erase(it);
387 } else {
388 mutex->SetShouldRespondToEmptyCheckpointRequest(false);
389 std::vector<BaseMutex*>& list = expected_mutexes_on_weak_ref_access_;
390 auto it = std::find(list.begin(), list.end(), mutex);
391 DCHECK(it != list.end());
392 list.erase(it);
393 }
394 }
395
IsExpectedOnWeakRefAccess(BaseMutex * mutex)396 bool Locks::IsExpectedOnWeakRefAccess(BaseMutex* mutex) {
397 ScopedExpectedMutexesOnWeakRefAccessLock mu(mutex);
398 std::vector<BaseMutex*>& list = expected_mutexes_on_weak_ref_access_;
399 return std::find(list.begin(), list.end(), mutex) != list.end();
400 }
401
402 } // namespace art
403