1 /*
   2  * Copyright (c) 1997, 2020, 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 "memory/universe.hpp"
  27 #include "runtime/mutexLocker.hpp"
  28 #include "runtime/os.inline.hpp"
  29 #include "runtime/safepoint.hpp"
  30 #include "runtime/thread.inline.hpp"
  31 #include "runtime/vmThread.hpp"
  32 
  33 // Mutexes used in the VM (see comment in mutexLocker.hpp):
  34 //
  35 // Note that the following pointers are effectively final -- after having been
  36 // set at JVM startup-time, they should never be subsequently mutated.
  37 // Instead of using pointers to malloc()ed monitors and mutexes we should consider
  38 // eliminating the indirection and using instances instead.
  39 // Consider using GCC's __read_mostly.
  40 
  41 Mutex*   Patching_lock                = NULL;
  42 Mutex*   CompiledMethod_lock          = NULL;
  43 Monitor* SystemDictionary_lock        = NULL;
  44 Mutex*   ProtectionDomainSet_lock     = NULL;
  45 Mutex*   SharedDictionary_lock        = NULL;
  46 Mutex*   Module_lock                  = NULL;
  47 Mutex*   CompiledIC_lock              = NULL;
  48 Mutex*   InlineCacheBuffer_lock       = NULL;
  49 Mutex*   VMStatistic_lock             = NULL;
  50 Mutex*   JNIHandleBlockFreeList_lock  = NULL;
  51 Mutex*   JmethodIdCreation_lock       = NULL;
  52 Mutex*   JfieldIdCreation_lock        = NULL;
  53 Monitor* JNICritical_lock             = NULL;
  54 Mutex*   JvmtiThreadState_lock        = NULL;
  55 Monitor* Heap_lock                    = NULL;
  56 Mutex*   ExpandHeap_lock              = NULL;
  57 Mutex*   AdapterHandlerLibrary_lock   = NULL;
  58 Mutex*   SignatureHandlerLibrary_lock = NULL;
  59 Mutex*   VtableStubs_lock             = NULL;
  60 Mutex*   SymbolArena_lock             = NULL;
  61 Monitor* StringDedupQueue_lock        = NULL;
  62 Mutex*   StringDedupTable_lock        = NULL;
  63 Monitor* CodeCache_lock               = NULL;
  64 Mutex*   MethodData_lock              = NULL;
  65 Mutex*   TouchedMethodLog_lock        = NULL;
  66 Mutex*   RetData_lock                 = NULL;
  67 Monitor* VMOperationQueue_lock        = NULL;
  68 Monitor* VMOperationRequest_lock      = NULL;
  69 Monitor* Threads_lock                 = NULL;
  70 Mutex*   NonJavaThreadsList_lock      = NULL;
  71 Mutex*   NonJavaThreadsListSync_lock  = NULL;
  72 Monitor* CGC_lock                     = NULL;
  73 Monitor* STS_lock                     = NULL;
  74 Monitor* FullGCCount_lock             = NULL;
  75 Monitor* G1OldGCCount_lock            = NULL;
  76 Mutex*   Shared_DirtyCardQ_lock       = NULL;
  77 Mutex*   MarkStackFreeList_lock       = NULL;
  78 Mutex*   MarkStackChunkList_lock      = NULL;
  79 Mutex*   MonitoringSupport_lock       = NULL;
  80 Mutex*   ParGCRareEvent_lock          = NULL;
  81 Monitor* ConcurrentGCBreakpoints_lock = NULL;
  82 Mutex*   Compile_lock                 = NULL;
  83 Monitor* MethodCompileQueue_lock      = NULL;
  84 Monitor* CompileThread_lock           = NULL;
  85 Monitor* Compilation_lock             = NULL;
  86 Mutex*   CompileTaskAlloc_lock        = NULL;
  87 Mutex*   CompileStatistics_lock       = NULL;
  88 Mutex*   DirectivesStack_lock         = NULL;
  89 Mutex*   MultiArray_lock              = NULL;
  90 Monitor* Terminator_lock              = NULL;
  91 Monitor* InitCompleted_lock           = NULL;
  92 Monitor* BeforeExit_lock              = NULL;
  93 Monitor* Notify_lock                  = NULL;
  94 Mutex*   ProfilePrint_lock            = NULL;
  95 Mutex*   ExceptionCache_lock          = NULL;
  96 Mutex*   NMethodSweeperStats_lock     = NULL;
  97 #ifndef PRODUCT
  98 Mutex*   FullGCALot_lock              = NULL;
  99 #endif
 100 
 101 Mutex*   Debug1_lock                  = NULL;
 102 Mutex*   Debug2_lock                  = NULL;
 103 Mutex*   Debug3_lock                  = NULL;
 104 
 105 Mutex*   tty_lock                     = NULL;
 106 
 107 Mutex*   RawMonitor_lock              = NULL;
 108 Mutex*   PerfDataMemAlloc_lock        = NULL;
 109 Mutex*   PerfDataManager_lock         = NULL;
 110 Mutex*   OopMapCacheAlloc_lock        = NULL;
 111 
 112 Mutex*   FreeList_lock                = NULL;
 113 Mutex*   OldSets_lock                 = NULL;
 114 Monitor* RootRegionScan_lock          = NULL;
 115 
 116 Mutex*   Management_lock              = NULL;
 117 Monitor* Service_lock                 = NULL;
 118 Monitor* Notification_lock            = NULL;
 119 Monitor* PeriodicTask_lock            = NULL;
 120 Monitor* RedefineClasses_lock         = NULL;
 121 Mutex*   Verify_lock                  = NULL;
 122 
 123 #if INCLUDE_JFR
 124 Mutex*   JfrStacktrace_lock           = NULL;
 125 Monitor* JfrMsg_lock                  = NULL;
 126 Mutex*   JfrBuffer_lock               = NULL;
 127 Mutex*   JfrStream_lock               = NULL;
 128 Monitor* JfrThreadSampler_lock        = NULL;
 129 #endif
 130 
 131 #ifndef SUPPORTS_NATIVE_CX8
 132 Mutex*   UnsafeJlong_lock             = NULL;
 133 #endif
 134 Mutex*   CodeHeapStateAnalytics_lock  = NULL;
 135 
 136 Mutex*   MetaspaceExpand_lock         = NULL;
 137 Mutex*   ClassLoaderDataGraph_lock    = NULL;
 138 Monitor* ThreadsSMRDelete_lock        = NULL;
 139 Mutex*   ThreadIdTableCreate_lock     = NULL;
 140 Mutex*   SharedDecoder_lock           = NULL;
 141 Mutex*   DCmdFactory_lock             = NULL;
 142 #if INCLUDE_NMT
 143 Mutex*   NMTQuery_lock                = NULL;
 144 #endif
 145 #if INCLUDE_CDS
 146 #if INCLUDE_JVMTI
 147 Mutex*   CDSClassFileStream_lock      = NULL;
 148 #endif
 149 Mutex*   DumpTimeTable_lock           = NULL;
 150 #endif // INCLUDE_CDS
 151 
 152 #if INCLUDE_JVMCI
 153 Monitor* JVMCI_lock                   = NULL;
 154 #endif
 155 
 156 
 157 #define MAX_NUM_MUTEX 128
 158 static Mutex* _mutex_array[MAX_NUM_MUTEX];
 159 static int _num_mutex;
 160 
 161 #ifdef ASSERT
 162 void assert_locked_or_safepoint(const Mutex* lock) {
 163   // check if this thread owns the lock (common case)
 164   assert(lock != NULL, "Need non-NULL lock");
 165   if (lock->owned_by_self()) return;
 166   if (SafepointSynchronize::is_at_safepoint()) return;
 167   if (!Universe::is_fully_initialized()) return;
 168   // see if invoker of VM operation owns it
 169   VM_Operation* op = VMThread::vm_operation();
 170   if (op != NULL && op->calling_thread() == lock->owner()) return;
 171   fatal("must own lock %s", lock->name());
 172 }
 173 
 174 // a weaker assertion than the above
 175 void assert_locked_or_safepoint_weak(const Mutex* lock) {
 176   assert(lock != NULL, "Need non-NULL lock");
 177   if (lock->is_locked()) return;
 178   if (SafepointSynchronize::is_at_safepoint()) return;
 179   if (!Universe::is_fully_initialized()) return;
 180   fatal("must own lock %s", lock->name());
 181 }
 182 
 183 // a stronger assertion than the above
 184 void assert_lock_strong(const Mutex* lock) {
 185   assert(lock != NULL, "Need non-NULL lock");
 186   if (lock->owned_by_self()) return;
 187   fatal("must own lock %s", lock->name());
 188 }
 189 
 190 void assert_locked_or_safepoint_or_handshake(const Mutex* lock, const JavaThread* thread) {
 191   if (Thread::current() == thread->active_handshaker()) return;
 192   assert_locked_or_safepoint(lock);
 193 }
 194 #endif
 195 
 196 #define def(var, type, pri, vm_block, safepoint_check_allowed ) {      \
 197   var = new type(Mutex::pri, #var, vm_block, Mutex::safepoint_check_allowed); \
 198   assert(_num_mutex < MAX_NUM_MUTEX, "increase MAX_NUM_MUTEX");        \
 199   _mutex_array[_num_mutex++] = var;                                      \
 200 }
 201 
 202 // Using Padded subclasses to prevent false sharing of these global monitors and mutexes.
 203 void mutex_init() {
 204   def(tty_lock                     , PaddedMutex  , tty,         true,  _safepoint_check_never);      // allow to lock in VM
 205 
 206   def(CGC_lock                     , PaddedMonitor, special,     true,  _safepoint_check_never);      // coordinate between fore- and background GC
 207   def(STS_lock                     , PaddedMonitor, leaf,        true,  _safepoint_check_never);
 208 
 209   def(FullGCCount_lock             , PaddedMonitor, leaf,        true,  _safepoint_check_never);      // in support of ExplicitGCInvokesConcurrent
 210   if (UseG1GC) {
 211     def(G1OldGCCount_lock          , PaddedMonitor, leaf,        true,  _safepoint_check_always);
 212 
 213     def(Shared_DirtyCardQ_lock     , PaddedMutex  , access + 1,  true,  _safepoint_check_never);
 214 
 215     def(FreeList_lock              , PaddedMutex  , leaf     ,   true,  _safepoint_check_never);
 216     def(OldSets_lock               , PaddedMutex  , leaf     ,   true,  _safepoint_check_never);
 217     def(RootRegionScan_lock        , PaddedMonitor, leaf     ,   true,  _safepoint_check_never);
 218 
 219     def(StringDedupQueue_lock      , PaddedMonitor, leaf,        true,  _safepoint_check_never);
 220     def(StringDedupTable_lock      , PaddedMutex  , leaf,        true,  _safepoint_check_never);
 221 
 222     def(MarkStackFreeList_lock     , PaddedMutex  , leaf     ,   true,  _safepoint_check_never);
 223     def(MarkStackChunkList_lock    , PaddedMutex  , leaf     ,   true,  _safepoint_check_never);
 224 
 225     def(MonitoringSupport_lock     , PaddedMutex  , native   ,   true,  _safepoint_check_never);      // used for serviceability monitoring support
 226   }
 227   if (UseShenandoahGC) {
 228     def(StringDedupQueue_lock      , PaddedMonitor, leaf,        true,  _safepoint_check_never);
 229     def(StringDedupTable_lock      , PaddedMutex  , leaf + 1,    true,  _safepoint_check_never);
 230   }
 231   def(ParGCRareEvent_lock          , PaddedMutex  , leaf     ,   true,  _safepoint_check_always);
 232   def(CodeCache_lock               , PaddedMonitor, special,     true,  _safepoint_check_never);
 233   def(RawMonitor_lock              , PaddedMutex  , special,     true,  _safepoint_check_never);
 234   def(OopMapCacheAlloc_lock        , PaddedMutex  , leaf,        true,  _safepoint_check_always); // used for oop_map_cache allocation.
 235 
 236   def(MetaspaceExpand_lock         , PaddedMutex  , leaf-1,      true,  _safepoint_check_never);
 237   def(ClassLoaderDataGraph_lock    , PaddedMutex  , nonleaf,     false, _safepoint_check_always);
 238 
 239   def(Patching_lock                , PaddedMutex  , special,     true,  _safepoint_check_never);      // used for safepointing and code patching.
 240   def(CompiledMethod_lock          , PaddedMutex  , special-1,   true,  _safepoint_check_never);
 241   def(Service_lock                 , PaddedMonitor, special,     true,  _safepoint_check_never);      // used for service thread operations
 242 
 243   if (UseNotificationThread) {
 244     def(Notification_lock            , PaddedMonitor, special,     true,  _safepoint_check_never);  // used for notification thread operations
 245   } else {
 246     Notification_lock = Service_lock;
 247   }
 248 
 249   def(JmethodIdCreation_lock       , PaddedMutex  , leaf,        true,  _safepoint_check_never); // used for creating jmethodIDs.
 250 
 251   def(SystemDictionary_lock        , PaddedMonitor, leaf,        true,  _safepoint_check_always);
 252   def(ProtectionDomainSet_lock     , PaddedMutex  , leaf-1,      true,  _safepoint_check_never);
 253   def(SharedDictionary_lock        , PaddedMutex  , leaf,        true,  _safepoint_check_always);
 254   def(Module_lock                  , PaddedMutex  , leaf+2,      false, _safepoint_check_always);
 255   def(InlineCacheBuffer_lock       , PaddedMutex  , leaf,        true,  _safepoint_check_never);
 256   def(VMStatistic_lock             , PaddedMutex  , leaf,        false, _safepoint_check_always);
 257   def(ExpandHeap_lock              , PaddedMutex  , leaf,        true,  _safepoint_check_always); // Used during compilation by VM thread
 258   def(JNIHandleBlockFreeList_lock  , PaddedMutex  , leaf-1,      true,  _safepoint_check_never);      // handles are used by VM thread
 259   def(SignatureHandlerLibrary_lock , PaddedMutex  , leaf,        false, _safepoint_check_always);
 260   def(SymbolArena_lock             , PaddedMutex  , leaf+2,      true,  _safepoint_check_never);
 261   def(ProfilePrint_lock            , PaddedMutex  , leaf,        false, _safepoint_check_always); // serial profile printing
 262   def(ExceptionCache_lock          , PaddedMutex  , leaf,        false, _safepoint_check_always); // serial profile printing
 263   def(Debug1_lock                  , PaddedMutex  , leaf,        true,  _safepoint_check_never);
 264 #ifndef PRODUCT
 265   def(FullGCALot_lock              , PaddedMutex  , leaf,        false, _safepoint_check_always); // a lock to make FullGCALot MT safe
 266 #endif
 267   def(BeforeExit_lock              , PaddedMonitor, leaf,        true,  _safepoint_check_always);
 268   def(PerfDataMemAlloc_lock        , PaddedMutex  , leaf,        true,  _safepoint_check_always); // used for allocating PerfData memory for performance data
 269   def(PerfDataManager_lock         , PaddedMutex  , leaf,        true,  _safepoint_check_always); // used for synchronized access to PerfDataManager resources
 270 
 271   def(Threads_lock                 , PaddedMonitor, barrier,     true,  _safepoint_check_always);  // Used for safepoint protocol.
 272   def(NonJavaThreadsList_lock      , PaddedMutex,   leaf,        true,  _safepoint_check_never);
 273   def(NonJavaThreadsListSync_lock  , PaddedMutex,   leaf,        true,  _safepoint_check_never);
 274 
 275   def(VMOperationQueue_lock        , PaddedMonitor, nonleaf,     true,  _safepoint_check_never);  // VM_thread allowed to block on these
 276   def(VMOperationRequest_lock      , PaddedMonitor, nonleaf,     true,  _safepoint_check_always);
 277   def(RetData_lock                 , PaddedMutex  , nonleaf,     false, _safepoint_check_always);
 278   def(Terminator_lock              , PaddedMonitor, nonleaf,     true,  _safepoint_check_always);
 279   def(InitCompleted_lock           , PaddedMonitor, leaf,        true,  _safepoint_check_never);
 280   def(VtableStubs_lock             , PaddedMutex  , nonleaf,     true,  _safepoint_check_never);
 281   def(Notify_lock                  , PaddedMonitor, nonleaf,     true,  _safepoint_check_always);
 282   def(JNICritical_lock             , PaddedMonitor, nonleaf,     true,  _safepoint_check_always); // used for JNI critical regions
 283   def(AdapterHandlerLibrary_lock   , PaddedMutex  , nonleaf,     true,  _safepoint_check_always);
 284 
 285   def(Heap_lock                    , PaddedMonitor, nonleaf+1,   false, _safepoint_check_sometimes);  // Doesn't safepoint check during termination.
 286   def(JfieldIdCreation_lock        , PaddedMutex  , nonleaf+1,   true,  _safepoint_check_always); // jfieldID, Used in VM_Operation
 287 
 288   def(CompiledIC_lock              , PaddedMutex  , nonleaf+2,   false, _safepoint_check_never);      // locks VtableStubs_lock, InlineCacheBuffer_lock
 289   def(CompileTaskAlloc_lock        , PaddedMutex  , nonleaf+2,   true,  _safepoint_check_always);
 290   def(CompileStatistics_lock       , PaddedMutex  , nonleaf+2,   false, _safepoint_check_always);
 291   def(DirectivesStack_lock         , PaddedMutex  , special,     true,  _safepoint_check_never);
 292   def(MultiArray_lock              , PaddedMutex  , nonleaf+2,   false, _safepoint_check_always);
 293 
 294   def(JvmtiThreadState_lock        , PaddedMutex  , nonleaf+2,   false, _safepoint_check_always); // Used by JvmtiThreadState/JvmtiEventController
 295   def(Management_lock              , PaddedMutex  , nonleaf+2,   false, _safepoint_check_always); // used for JVM management
 296 
 297   def(ConcurrentGCBreakpoints_lock , PaddedMonitor, nonleaf,     true,  _safepoint_check_always);
 298   def(Compile_lock                 , PaddedMutex  , nonleaf+3,   false, _safepoint_check_always);
 299   def(MethodData_lock              , PaddedMutex  , nonleaf+3,   false, _safepoint_check_always);
 300   def(TouchedMethodLog_lock        , PaddedMutex  , nonleaf+3,   false, _safepoint_check_always);
 301 
 302   def(MethodCompileQueue_lock      , PaddedMonitor, nonleaf+4,   false, _safepoint_check_always);
 303   def(Debug2_lock                  , PaddedMutex  , nonleaf+4,   true,  _safepoint_check_never);
 304   def(Debug3_lock                  , PaddedMutex  , nonleaf+4,   true,  _safepoint_check_never);
 305   def(CompileThread_lock           , PaddedMonitor, nonleaf+5,   false, _safepoint_check_always);
 306   def(PeriodicTask_lock            , PaddedMonitor, nonleaf+5,   true,  _safepoint_check_always);
 307   def(RedefineClasses_lock         , PaddedMonitor, nonleaf+5,   true,  _safepoint_check_always);
 308   def(Verify_lock                  , PaddedMutex,   nonleaf+5,   true,  _safepoint_check_always);
 309 
 310   if (WhiteBoxAPI) {
 311     def(Compilation_lock           , PaddedMonitor, leaf,        false, _safepoint_check_never);
 312   }
 313 
 314 #if INCLUDE_JFR
 315   def(JfrMsg_lock                  , PaddedMonitor, leaf,        true,  _safepoint_check_always);
 316   def(JfrBuffer_lock               , PaddedMutex  , leaf,        true,  _safepoint_check_never);
 317   def(JfrStream_lock               , PaddedMutex  , nonleaf + 1, false, _safepoint_check_never);
 318   def(JfrStacktrace_lock           , PaddedMutex  , special,     true,  _safepoint_check_never);
 319   def(JfrThreadSampler_lock        , PaddedMonitor, leaf,        true,  _safepoint_check_never);
 320 #endif
 321 
 322 #ifndef SUPPORTS_NATIVE_CX8
 323   def(UnsafeJlong_lock             , PaddedMutex  , special,     false, _safepoint_check_never);
 324 #endif
 325 
 326   def(CodeHeapStateAnalytics_lock  , PaddedMutex  , leaf,        true,  _safepoint_check_never);
 327   def(NMethodSweeperStats_lock     , PaddedMutex  , special,     true,  _safepoint_check_never);
 328   def(ThreadsSMRDelete_lock        , PaddedMonitor, special,     true,  _safepoint_check_never);
 329   def(ThreadIdTableCreate_lock     , PaddedMutex  , leaf,        false, _safepoint_check_always);
 330   def(SharedDecoder_lock           , PaddedMutex  , native,      true,  _safepoint_check_never);
 331   def(DCmdFactory_lock             , PaddedMutex  , leaf,        true,  _safepoint_check_never);
 332 #if INCLUDE_NMT
 333   def(NMTQuery_lock                , PaddedMutex  , max_nonleaf, false, _safepoint_check_always);
 334 #endif
 335 #if INCLUDE_CDS
 336 #if INCLUDE_JVMTI
 337   def(CDSClassFileStream_lock      , PaddedMutex  , max_nonleaf, false, _safepoint_check_always);
 338 #endif
 339   def(DumpTimeTable_lock           , PaddedMutex  , leaf,        true,  _safepoint_check_never);
 340 #endif // INCLUDE_CDS
 341 
 342 #if INCLUDE_JVMCI
 343   def(JVMCI_lock                   , PaddedMonitor, nonleaf+2,   true,  _safepoint_check_always);
 344 #endif
 345 }
 346 
 347 GCMutexLocker::GCMutexLocker(Mutex* mutex) {
 348   if (SafepointSynchronize::is_at_safepoint()) {
 349     _locked = false;
 350   } else {
 351     _mutex = mutex;
 352     _locked = true;
 353     _mutex->lock();
 354   }
 355 }
 356 
 357 // Print all mutexes/monitors that are currently owned by a thread; called
 358 // by fatal error handler.
 359 void print_owned_locks_on_error(outputStream* st) {
 360   st->print("VM Mutex/Monitor currently owned by a thread: ");
 361   bool none = true;
 362   for (int i = 0; i < _num_mutex; i++) {
 363      // see if it has an owner
 364      if (_mutex_array[i]->owner() != NULL) {
 365        if (none) {
 366           // print format used by Mutex::print_on_error()
 367           st->print_cr(" ([mutex/lock_event])");
 368           none = false;
 369        }
 370        _mutex_array[i]->print_on_error(st);
 371        st->cr();
 372      }
 373   }
 374   if (none) st->print_cr("None");
 375 }