1 /*
   2  * Copyright (c) 1997, 2019, 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 #ifndef SHARE_RUNTIME_INTERFACESUPPORT_INLINE_HPP
  26 #define SHARE_RUNTIME_INTERFACESUPPORT_INLINE_HPP
  27 
  28 #include "runtime/handles.inline.hpp"
  29 #include "runtime/mutexLocker.hpp"
  30 #include "runtime/orderAccess.hpp"
  31 #include "runtime/os.hpp"
  32 #include "runtime/safepointMechanism.inline.hpp"
  33 #include "runtime/safepointVerifiers.hpp"
  34 #include "runtime/thread.hpp"
  35 #include "runtime/vmOperations.hpp"
  36 #include "utilities/globalDefinitions.hpp"
  37 #include "utilities/histogram.hpp"
  38 #include "utilities/macros.hpp"
  39 #include "utilities/preserveException.hpp"
  40 
  41 // Wrapper for all entry points to the virtual machine.
  42 
  43 // InterfaceSupport provides functionality used by the VM_LEAF_BASE and
  44 // VM_ENTRY_BASE macros. These macros are used to guard entry points into
  45 // the VM and perform checks upon leave of the VM.
  46 
  47 
  48 class InterfaceSupport: AllStatic {
  49 # ifdef ASSERT
  50  public:
  51   static long _scavenge_alot_counter;
  52   static long _fullgc_alot_counter;
  53   static long _number_of_calls;
  54   static long _fullgc_alot_invocation;
  55 
  56   // Helper methods used to implement +ScavengeALot and +FullGCALot
  57   static void check_gc_alot() { if (ScavengeALot || FullGCALot) gc_alot(); }
  58   static void gc_alot();
  59 
  60   static void walk_stack_from(vframe* start_vf);
  61   static void walk_stack();
  62 
  63   static void zombieAll();
  64   static void deoptimizeAll();
  65   static void stress_derived_pointers();
  66   static void verify_stack();
  67   static void verify_last_frame();
  68 # endif
  69 };
  70 
  71 
  72 // Basic class for all thread transition classes.
  73 
  74 class ThreadStateTransition : public StackObj {
  75  protected:
  76   JavaThread* _thread;
  77  public:
  78   ThreadStateTransition(JavaThread *thread) {
  79     _thread = thread;
  80     assert(thread != NULL && thread->is_Java_thread(), "must be Java thread");
  81   }
  82 
  83   // Change threadstate in a manner, so safepoint can detect changes.
  84   // Time-critical: called on exit from every runtime routine
  85   static inline void transition(JavaThread *thread, JavaThreadState from, JavaThreadState to) {
  86     assert(from != _thread_in_Java, "use transition_from_java");
  87     assert(from != _thread_in_native, "use transition_from_native");
  88     assert((from & 1) == 0 && (to & 1) == 0, "odd numbers are transitions states");
  89     assert(thread->thread_state() == from, "coming from wrong thread state");
  90     // Change to transition state and ensure it is seen by the VM thread.
  91     thread->set_thread_state_fence((JavaThreadState)(from + 1));
  92 
  93     SafepointMechanism::block_if_requested(thread);
  94     thread->set_thread_state(to);
  95 
  96     CHECK_UNHANDLED_OOPS_ONLY(thread->clear_unhandled_oops();)
  97   }
  98 
  99   // Same as above, but assumes from = _thread_in_Java. This is simpler, since we
 100   // never block on entry to the VM. This will break the code, since e.g. preserve arguments
 101   // have not been setup.
 102   static inline void transition_from_java(JavaThread *thread, JavaThreadState to) {
 103     assert(thread->thread_state() == _thread_in_Java, "coming from wrong thread state");
 104     thread->set_thread_state(to);
 105   }
 106 
 107   static inline void transition_from_native(JavaThread *thread, JavaThreadState to) {
 108     assert((to & 1) == 0, "odd numbers are transitions states");
 109     assert(thread->thread_state() == _thread_in_native, "coming from wrong thread state");
 110     // Change to transition state and ensure it is seen by the VM thread.
 111     thread->set_thread_state_fence(_thread_in_native_trans);
 112 
 113     // We never install asynchronous exceptions when coming (back) in
 114     // to the runtime from native code because the runtime is not set
 115     // up to handle exceptions floating around at arbitrary points.
 116     if (SafepointMechanism::should_block(thread) || thread->is_suspend_after_native()) {
 117       JavaThread::check_safepoint_and_suspend_for_native_trans(thread);
 118     }
 119 
 120     thread->set_thread_state(to);
 121   }
 122  protected:
 123    void trans(JavaThreadState from, JavaThreadState to)  { transition(_thread, from, to); }
 124    void trans_from_java(JavaThreadState to)              { transition_from_java(_thread, to); }
 125    void trans_from_native(JavaThreadState to)            { transition_from_native(_thread, to); }
 126 };
 127 
 128 class ThreadInVMForHandshake : public ThreadStateTransition {
 129   const JavaThreadState _original_state;
 130 
 131   void transition_back() {
 132     // This can be invoked from transition states and must return to the original state properly
 133     assert(_thread->thread_state() == _thread_in_vm, "should only call when leaving VM after handshake");
 134     // Change to transition state and ensure it is seen by the VM thread.
 135     _thread->set_thread_state_fence(_thread_in_vm_trans);
 136 
 137     SafepointMechanism::block_if_requested(_thread);
 138 
 139     _thread->set_thread_state(_original_state);
 140   }
 141 
 142  public:
 143 
 144   ThreadInVMForHandshake(JavaThread* thread) : ThreadStateTransition(thread),
 145       _original_state(thread->thread_state()) {
 146 
 147     if (thread->has_last_Java_frame()) {
 148       thread->frame_anchor()->make_walkable(thread);
 149     }
 150 
 151     thread->set_thread_state(_thread_in_vm);
 152   }
 153 
 154   ~ThreadInVMForHandshake() {
 155     transition_back();
 156   }
 157 
 158 };
 159 
 160 class ThreadInVMfromJava : public ThreadStateTransition {
 161  public:
 162   ThreadInVMfromJava(JavaThread* thread) : ThreadStateTransition(thread) {
 163     trans_from_java(_thread_in_vm);
 164   }
 165   ~ThreadInVMfromJava()  {
 166     if (_thread->stack_yellow_reserved_zone_disabled()) {
 167       _thread->enable_stack_yellow_reserved_zone();
 168     }
 169     trans(_thread_in_vm, _thread_in_Java);
 170     // Check for pending. async. exceptions or suspends.
 171     if (_thread->has_special_runtime_exit_condition()) _thread->handle_special_runtime_exit_condition();
 172   }
 173 };
 174 
 175 
 176 class ThreadInVMfromUnknown {
 177   JavaThread* _thread;
 178  public:
 179   ThreadInVMfromUnknown() : _thread(NULL) {
 180     Thread* t = Thread::current();
 181     if (t->is_Java_thread()) {
 182       JavaThread* t2 = (JavaThread*) t;
 183       if (t2->thread_state() == _thread_in_native) {
 184         _thread = t2;
 185         ThreadStateTransition::transition_from_native(t2, _thread_in_vm);
 186         // Used to have a HandleMarkCleaner but that is dangerous as
 187         // it could free a handle in our (indirect, nested) caller.
 188         // We expect any handles will be short lived and figure we
 189         // don't need an actual HandleMark.
 190       }
 191     }
 192   }
 193   ~ThreadInVMfromUnknown()  {
 194     if (_thread) {
 195       ThreadStateTransition::transition(_thread, _thread_in_vm, _thread_in_native);
 196     }
 197   }
 198 };
 199 
 200 
 201 class ThreadInVMfromNative : public ThreadStateTransition {
 202  public:
 203   ThreadInVMfromNative(JavaThread* thread) : ThreadStateTransition(thread) {
 204     trans_from_native(_thread_in_vm);
 205   }
 206   ~ThreadInVMfromNative() {
 207     trans(_thread_in_vm, _thread_in_native);
 208   }
 209 };
 210 
 211 
 212 class ThreadToNativeFromVM : public ThreadStateTransition {
 213  public:
 214   ThreadToNativeFromVM(JavaThread *thread) : ThreadStateTransition(thread) {
 215     // We are leaving the VM at this point and going directly to native code.
 216     // Block, if we are in the middle of a safepoint synchronization.
 217     assert(!thread->owns_locks(), "must release all locks when leaving VM");
 218     thread->frame_anchor()->make_walkable(thread);
 219     trans(_thread_in_vm, _thread_in_native);
 220     // Check for pending. async. exceptions or suspends.
 221     if (_thread->has_special_runtime_exit_condition()) _thread->handle_special_runtime_exit_condition(false);
 222   }
 223 
 224   ~ThreadToNativeFromVM() {
 225     trans_from_native(_thread_in_vm);
 226     assert(!_thread->is_pending_jni_exception_check(), "Pending JNI Exception Check");
 227     // We don't need to clear_walkable because it will happen automagically when we return to java
 228   }
 229 };
 230 
 231 
 232 class ThreadBlockInVM : public ThreadStateTransition {
 233  public:
 234   ThreadBlockInVM(JavaThread *thread)
 235   : ThreadStateTransition(thread) {
 236     // Once we are blocked vm expects stack to be walkable
 237     thread->frame_anchor()->make_walkable(thread);
 238     trans(_thread_in_vm, _thread_blocked);
 239   }
 240   ~ThreadBlockInVM() {
 241     trans(_thread_blocked, _thread_in_vm);
 242     OrderAccess::cross_modify_fence();
 243     // We don't need to clear_walkable because it will happen automagically when we return to java
 244   }
 245 };
 246 
 247 // Unlike ThreadBlockInVM, this class is designed to avoid certain deadlock scenarios while making
 248 // transitions inside class Monitor in cases where we need to block for a safepoint or handshake. It
 249 // receives an extra argument compared to ThreadBlockInVM, the address of a pointer to the monitor we
 250 // are trying to acquire. This will be used to access and release the monitor if needed to avoid
 251 // said deadlocks.
 252 // It works like ThreadBlockInVM but differs from it in two ways:
 253 // - When transitioning in (constructor), it checks for safepoints without blocking, i.e., calls
 254 //   back if needed to allow a pending safepoint to continue but does not block in it.
 255 // - When transitioning back (destructor), if there is a pending safepoint or handshake it releases
 256 //   the monitor that is only partially acquired.
 257 class ThreadBlockInVMWithDeadlockCheck : public ThreadStateTransition {
 258  private:
 259   Monitor** _in_flight_monitor_adr;
 260 
 261   void release_monitor() {
 262     assert(_in_flight_monitor_adr != NULL, "_in_flight_monitor_adr should have been set on constructor");
 263     Monitor* in_flight_monitor = *_in_flight_monitor_adr;
 264     if (in_flight_monitor != NULL) {
 265       in_flight_monitor->release_for_safepoint();
 266       *_in_flight_monitor_adr = NULL;
 267     }
 268   }
 269  public:
 270   ThreadBlockInVMWithDeadlockCheck(JavaThread* thread, Monitor** in_flight_monitor_adr)
 271   : ThreadStateTransition(thread), _in_flight_monitor_adr(in_flight_monitor_adr) {
 272     // Once we are blocked vm expects stack to be walkable
 273     thread->frame_anchor()->make_walkable(thread);
 274 
 275     // All unsafe states are treated the same by the VMThread
 276     // so we can skip the _thread_in_vm_trans state here. Since
 277     // we don't read poll, it's enough to order the stores.
 278     OrderAccess::storestore();
 279 
 280     thread->set_thread_state(_thread_blocked);
 281   }
 282   ~ThreadBlockInVMWithDeadlockCheck() {
 283     // Change to transition state and ensure it is seen by the VM thread.
 284     _thread->set_thread_state_fence((JavaThreadState)(_thread_blocked_trans));
 285 
 286     if (SafepointMechanism::should_block(_thread)) {
 287       release_monitor();
 288       SafepointMechanism::block_if_requested(_thread);
 289     }
 290 
 291     _thread->set_thread_state(_thread_in_vm);
 292     OrderAccess::cross_modify_fence();
 293   }
 294 };
 295 
 296 
 297 // This special transition class is only used to prevent asynchronous exceptions
 298 // from being installed on vm exit in situations where we can't tolerate them.
 299 // See bugs: 4324348, 4854693, 4998314, 5040492, 5050705.
 300 class ThreadInVMfromJavaNoAsyncException : public ThreadStateTransition {
 301  public:
 302   ThreadInVMfromJavaNoAsyncException(JavaThread* thread) : ThreadStateTransition(thread) {
 303     trans_from_java(_thread_in_vm);
 304   }
 305   ~ThreadInVMfromJavaNoAsyncException()  {
 306     if (_thread->stack_yellow_reserved_zone_disabled()) {
 307       _thread->enable_stack_yellow_reserved_zone();
 308     }
 309     trans(_thread_in_vm, _thread_in_Java);
 310     // NOTE: We do not check for pending. async. exceptions.
 311     // If we did and moved the pending async exception over into the
 312     // pending exception field, we would need to deopt (currently C2
 313     // only). However, to do so would require that we transition back
 314     // to the _thread_in_vm state. Instead we postpone the handling of
 315     // the async exception.
 316 
 317 
 318     // Check for pending. suspends only.
 319     if (_thread->has_special_runtime_exit_condition())
 320       _thread->handle_special_runtime_exit_condition(false);
 321   }
 322 };
 323 
 324 // Debug class instantiated in JRT_ENTRY and ITR_ENTRY macro.
 325 // Can be used to verify properties on enter/exit of the VM.
 326 
 327 #ifdef ASSERT
 328 class VMEntryWrapper {
 329  public:
 330   VMEntryWrapper();
 331   ~VMEntryWrapper();
 332 };
 333 
 334 
 335 class VMNativeEntryWrapper {
 336  public:
 337   VMNativeEntryWrapper() {
 338     if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();
 339   }
 340 
 341   ~VMNativeEntryWrapper() {
 342     if (GCALotAtAllSafepoints) InterfaceSupport::check_gc_alot();
 343   }
 344 };
 345 
 346 #endif
 347 
 348 
 349 // VM-internal runtime interface support
 350 
 351 // Definitions for JRT (Java (Compiler/Shared) Runtime)
 352 
 353 // JRT_LEAF currently can be called from either _thread_in_Java or
 354 // _thread_in_native mode. In _thread_in_native, it is ok
 355 // for another thread to trigger GC. The rest of the JRT_LEAF
 356 // rules apply.
 357 class JRTLeafVerifier : public NoSafepointVerifier {
 358   static bool should_verify_GC();
 359  public:
 360 #ifdef ASSERT
 361   JRTLeafVerifier();
 362   ~JRTLeafVerifier();
 363 #else
 364   JRTLeafVerifier() {}
 365   ~JRTLeafVerifier() {}
 366 #endif
 367 };
 368 
 369 #ifdef ASSERT
 370 
 371 class RuntimeHistogramElement : public HistogramElement {
 372   public:
 373    RuntimeHistogramElement(const char* name);
 374 };
 375 
 376 #define TRACE_CALL(result_type, header)                            \
 377   InterfaceSupport::_number_of_calls++;                            \
 378   if (CountRuntimeCalls) {                                         \
 379     static RuntimeHistogramElement* e = new RuntimeHistogramElement(#header); \
 380     if (e != NULL) e->increment_count();                           \
 381   }
 382 #else
 383 #define TRACE_CALL(result_type, header)                            \
 384   /* do nothing */
 385 #endif
 386 
 387 
 388 // LEAF routines do not lock, GC or throw exceptions
 389 
 390 #define VM_LEAF_BASE(result_type, header)                            \
 391   TRACE_CALL(result_type, header)                                    \
 392   debug_only(NoHandleMark __hm;)                                     \
 393   os::verify_stack_alignment();                                      \
 394   /* begin of body */
 395 
 396 #define VM_ENTRY_BASE_FROM_LEAF(result_type, header, thread)         \
 397   TRACE_CALL(result_type, header)                                    \
 398   debug_only(ResetNoHandleMark __rnhm;)                              \
 399   HandleMarkCleaner __hm(thread);                                    \
 400   Thread* THREAD = thread;                                           \
 401   os::verify_stack_alignment();                                      \
 402   /* begin of body */
 403 
 404 
 405 // ENTRY routines may lock, GC and throw exceptions
 406 
 407 #define VM_ENTRY_BASE(result_type, header, thread)                   \
 408   TRACE_CALL(result_type, header)                                    \
 409   HandleMarkCleaner __hm(thread);                                    \
 410   Thread* THREAD = thread;                                           \
 411   os::verify_stack_alignment();                                      \
 412   /* begin of body */
 413 
 414 
 415 // QUICK_ENTRY routines behave like ENTRY but without a handle mark
 416 
 417 #define VM_QUICK_ENTRY_BASE(result_type, header, thread)             \
 418   TRACE_CALL(result_type, header)                                    \
 419   debug_only(NoHandleMark __hm;)                                     \
 420   Thread* THREAD = thread;                                           \
 421   os::verify_stack_alignment();                                      \
 422   /* begin of body */
 423 
 424 
 425 #define JRT_ENTRY(result_type, header)                               \
 426   result_type header {                                               \
 427     ThreadInVMfromJava __tiv(thread);                                \
 428     VM_ENTRY_BASE(result_type, header, thread)                       \
 429     debug_only(VMEntryWrapper __vew;)
 430 
 431 
 432 #define JRT_LEAF(result_type, header)                                \
 433   result_type header {                                               \
 434   VM_LEAF_BASE(result_type, header)                                  \
 435   debug_only(JRTLeafVerifier __jlv;)
 436 
 437 
 438 #define JRT_ENTRY_NO_ASYNC(result_type, header)                      \
 439   result_type header {                                               \
 440     ThreadInVMfromJavaNoAsyncException __tiv(thread);                \
 441     VM_ENTRY_BASE(result_type, header, thread)                       \
 442     debug_only(VMEntryWrapper __vew;)
 443 
 444 // Same as JRT Entry but allows for return value after the safepoint
 445 // to get back into Java from the VM
 446 #define JRT_BLOCK_ENTRY(result_type, header)                         \
 447   result_type header {                                               \
 448     TRACE_CALL(result_type, header)                                  \
 449     HandleMarkCleaner __hm(thread);
 450 
 451 #define JRT_BLOCK                                                    \
 452     {                                                                \
 453     ThreadInVMfromJava __tiv(thread);                                \
 454     Thread* THREAD = thread;                                         \
 455     debug_only(VMEntryWrapper __vew;)
 456 
 457 #define JRT_BLOCK_NO_ASYNC                                           \
 458     {                                                                \
 459     ThreadInVMfromJavaNoAsyncException __tiv(thread);                \
 460     Thread* THREAD = thread;                                         \
 461     debug_only(VMEntryWrapper __vew;)
 462 
 463 #define JRT_BLOCK_END }
 464 
 465 #define JRT_END }
 466 
 467 // Definitions for JNI
 468 
 469 #define JNI_ENTRY(result_type, header)                               \
 470     JNI_ENTRY_NO_PRESERVE(result_type, header)                       \
 471     WeakPreserveExceptionMark __wem(thread);
 472 
 473 #define JNI_ENTRY_NO_PRESERVE(result_type, header)                   \
 474 extern "C" {                                                         \
 475   result_type JNICALL header {                                       \
 476     JavaThread* thread=JavaThread::thread_from_jni_environment(env); \
 477     assert( !VerifyJNIEnvThread || (thread == Thread::current()), "JNIEnv is only valid in same thread"); \
 478     ThreadInVMfromNative __tiv(thread);                              \
 479     debug_only(VMNativeEntryWrapper __vew;)                          \
 480     VM_ENTRY_BASE(result_type, header, thread)
 481 
 482 
 483 // Ensure that the VMNativeEntryWrapper constructor, which can cause
 484 // a GC, is called outside the NoHandleMark (set via VM_QUICK_ENTRY_BASE).
 485 #define JNI_QUICK_ENTRY(result_type, header)                         \
 486 extern "C" {                                                         \
 487   result_type JNICALL header {                                       \
 488     JavaThread* thread=JavaThread::thread_from_jni_environment(env); \
 489     assert( !VerifyJNIEnvThread || (thread == Thread::current()), "JNIEnv is only valid in same thread"); \
 490     ThreadInVMfromNative __tiv(thread);                              \
 491     debug_only(VMNativeEntryWrapper __vew;)                          \
 492     VM_QUICK_ENTRY_BASE(result_type, header, thread)
 493 
 494 
 495 #define JNI_LEAF(result_type, header)                                \
 496 extern "C" {                                                         \
 497   result_type JNICALL header {                                       \
 498     JavaThread* thread=JavaThread::thread_from_jni_environment(env); \
 499     assert( !VerifyJNIEnvThread || (thread == Thread::current()), "JNIEnv is only valid in same thread"); \
 500     VM_LEAF_BASE(result_type, header)
 501 
 502 
 503 // Close the routine and the extern "C"
 504 #define JNI_END } }
 505 
 506 
 507 
 508 // Definitions for JVM
 509 
 510 #define JVM_ENTRY(result_type, header)                               \
 511 extern "C" {                                                         \
 512   result_type JNICALL header {                                       \
 513     JavaThread* thread=JavaThread::thread_from_jni_environment(env); \
 514     ThreadInVMfromNative __tiv(thread);                              \
 515     debug_only(VMNativeEntryWrapper __vew;)                          \
 516     VM_ENTRY_BASE(result_type, header, thread)
 517 
 518 
 519 #define JVM_ENTRY_NO_ENV(result_type, header)                        \
 520 extern "C" {                                                         \
 521   result_type JNICALL header {                                       \
 522     JavaThread* thread = JavaThread::current();                      \
 523     ThreadInVMfromNative __tiv(thread);                              \
 524     debug_only(VMNativeEntryWrapper __vew;)                          \
 525     VM_ENTRY_BASE(result_type, header, thread)
 526 
 527 
 528 #define JVM_QUICK_ENTRY(result_type, header)                         \
 529 extern "C" {                                                         \
 530   result_type JNICALL header {                                       \
 531     JavaThread* thread=JavaThread::thread_from_jni_environment(env); \
 532     ThreadInVMfromNative __tiv(thread);                              \
 533     debug_only(VMNativeEntryWrapper __vew;)                          \
 534     VM_QUICK_ENTRY_BASE(result_type, header, thread)
 535 
 536 
 537 #define JVM_LEAF(result_type, header)                                \
 538 extern "C" {                                                         \
 539   result_type JNICALL header {                                       \
 540     VM_Exit::block_if_vm_exited();                                   \
 541     VM_LEAF_BASE(result_type, header)
 542 
 543 
 544 #define JVM_ENTRY_FROM_LEAF(env, result_type, header)                \
 545   { {                                                                \
 546     JavaThread* thread=JavaThread::thread_from_jni_environment(env); \
 547     ThreadInVMfromNative __tiv(thread);                              \
 548     debug_only(VMNativeEntryWrapper __vew;)                          \
 549     VM_ENTRY_BASE_FROM_LEAF(result_type, header, thread)
 550 
 551 
 552 #define JVM_END } }
 553 
 554 #endif // SHARE_RUNTIME_INTERFACESUPPORT_INLINE_HPP