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