1 /*
   2  * Copyright (c) 2000, 2017, 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 "classfile/classFileStream.hpp"
  27 #include "classfile/vmSymbols.hpp"
  28 #include "memory/allocation.inline.hpp"
  29 #include "memory/resourceArea.hpp"
  30 #include "oops/fieldStreams.hpp"
  31 #include "oops/objArrayOop.inline.hpp"
  32 #include "oops/oop.inline.hpp"
  33 #include "prims/jni.h"
  34 #include "prims/jvm.h"
  35 #include "prims/unsafe.hpp"
  36 #include "runtime/atomic.hpp"
  37 #include "runtime/globals.hpp"
  38 #include "runtime/interfaceSupport.hpp"
  39 #include "runtime/orderAccess.inline.hpp"
  40 #include "runtime/reflection.hpp"
  41 #include "runtime/vm_version.hpp"
  42 #include "services/threadService.hpp"
  43 #include "trace/tracing.hpp"
  44 #include "utilities/copy.hpp"
  45 #include "utilities/dtrace.hpp"
  46 #include "utilities/macros.hpp"
  47 #if INCLUDE_ALL_GCS
  48 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
  49 #endif // INCLUDE_ALL_GCS
  50 
  51 /**
  52  * Implementation of the jdk.internal.misc.Unsafe class
  53  */
  54 
  55 
  56 #define MAX_OBJECT_SIZE \
  57   ( arrayOopDesc::header_size(T_DOUBLE) * HeapWordSize \
  58     + ((julong)max_jint * sizeof(double)) )
  59 
  60 
  61 #define UNSAFE_ENTRY(result_type, header) \
  62   JVM_ENTRY(static result_type, header)
  63 
  64 #define UNSAFE_LEAF(result_type, header) \
  65   JVM_LEAF(static result_type, header)
  66 
  67 #define UNSAFE_END JVM_END
  68 
  69 
  70 static inline void* addr_from_java(jlong addr) {
  71   // This assert fails in a variety of ways on 32-bit systems.
  72   // It is impossible to predict whether native code that converts
  73   // pointers to longs will sign-extend or zero-extend the addresses.
  74   //assert(addr == (uintptr_t)addr, "must not be odd high bits");
  75   return (void*)(uintptr_t)addr;
  76 }
  77 
  78 static inline jlong addr_to_java(void* p) {
  79   assert(p == (void*)(uintptr_t)p, "must not be odd high bits");
  80   return (uintptr_t)p;
  81 }
  82 
  83 
  84 // Note: The VM's obj_field and related accessors use byte-scaled
  85 // ("unscaled") offsets, just as the unsafe methods do.
  86 
  87 // However, the method Unsafe.fieldOffset explicitly declines to
  88 // guarantee this.  The field offset values manipulated by the Java user
  89 // through the Unsafe API are opaque cookies that just happen to be byte
  90 // offsets.  We represent this state of affairs by passing the cookies
  91 // through conversion functions when going between the VM and the Unsafe API.
  92 // The conversion functions just happen to be no-ops at present.
  93 
  94 static inline jlong field_offset_to_byte_offset(jlong field_offset) {
  95   return field_offset;
  96 }
  97 
  98 static inline jlong field_offset_from_byte_offset(jlong byte_offset) {
  99   return byte_offset;
 100 }
 101 
 102 static inline void* index_oop_from_field_offset_long(oop p, jlong field_offset) {
 103   jlong byte_offset = field_offset_to_byte_offset(field_offset);
 104 
 105 #ifdef ASSERT
 106   if (p != NULL) {
 107     assert(byte_offset >= 0 && byte_offset <= (jlong)MAX_OBJECT_SIZE, "sane offset");
 108     if (byte_offset == (jint)byte_offset) {
 109       void* ptr_plus_disp = (address)p + byte_offset;
 110       assert((void*)p->obj_field_addr<oop>((jint)byte_offset) == ptr_plus_disp,
 111              "raw [ptr+disp] must be consistent with oop::field_base");
 112     }
 113     jlong p_size = HeapWordSize * (jlong)(p->size());
 114     assert(byte_offset < p_size, "Unsafe access: offset " INT64_FORMAT " > object's size " INT64_FORMAT, byte_offset, p_size);
 115   }
 116 #endif
 117 
 118   if (sizeof(char*) == sizeof(jint)) {   // (this constant folds!)
 119     return (address)p + (jint) byte_offset;
 120   } else {
 121     return (address)p +        byte_offset;
 122   }
 123 }
 124 
 125 // Externally callable versions:
 126 // (Use these in compiler intrinsics which emulate unsafe primitives.)
 127 jlong Unsafe_field_offset_to_byte_offset(jlong field_offset) {
 128   return field_offset;
 129 }
 130 jlong Unsafe_field_offset_from_byte_offset(jlong byte_offset) {
 131   return byte_offset;
 132 }
 133 
 134 
 135 ///// Data read/writes on the Java heap and in native (off-heap) memory
 136 
 137 /**
 138  * Helper class for accessing memory.
 139  *
 140  * Normalizes values and wraps accesses in
 141  * JavaThread::doing_unsafe_access() if needed.
 142  */
 143 class MemoryAccess : StackObj {
 144   JavaThread* _thread;
 145   jobject _obj;
 146   jlong _offset;
 147 
 148   // Resolves and returns the address of the memory access
 149   void* addr() {
 150     return index_oop_from_field_offset_long(JNIHandles::resolve(_obj), _offset);
 151   }
 152 
 153   template <typename T>
 154   T normalize_for_write(T x) {
 155     return x;
 156   }
 157 
 158   jboolean normalize_for_write(jboolean x) {
 159     return x & 1;
 160   }
 161 
 162   template <typename T>
 163   T normalize_for_read(T x) {
 164     return x;
 165   }
 166 
 167   jboolean normalize_for_read(jboolean x) {
 168     return x != 0;
 169   }
 170 
 171   /**
 172    * Helper class to wrap memory accesses in JavaThread::doing_unsafe_access()
 173    */
 174   class GuardUnsafeAccess {
 175     JavaThread* _thread;
 176     bool _active;
 177 
 178   public:
 179     GuardUnsafeAccess(JavaThread* thread, jobject _obj) : _thread(thread) {
 180       if (JNIHandles::resolve(_obj) == NULL) {
 181         // native/off-heap access which may raise SIGBUS if accessing
 182         // memory mapped file data in a region of the file which has
 183         // been truncated and is now invalid
 184         _thread->set_doing_unsafe_access(true);
 185         _active = true;
 186       } else {
 187         _active = false;
 188       }
 189     }
 190 
 191     ~GuardUnsafeAccess() {
 192       if (_active) {
 193         _thread->set_doing_unsafe_access(false);
 194       }
 195     }
 196   };
 197 
 198 public:
 199   MemoryAccess(JavaThread* thread, jobject obj, jlong offset)
 200     : _thread(thread), _obj(obj), _offset(offset) {
 201   }
 202 
 203   template <typename T>
 204   T get() {
 205     GuardUnsafeAccess guard(_thread, _obj);
 206 
 207     T* p = (T*)addr();
 208 
 209     T x = normalize_for_read(*p);
 210 
 211     return x;
 212   }
 213 
 214   template <typename T>
 215   void put(T x) {
 216     GuardUnsafeAccess guard(_thread, _obj);
 217 
 218     T* p = (T*)addr();
 219 
 220     *p = normalize_for_write(x);
 221   }
 222 
 223 
 224   template <typename T>
 225   T get_volatile() {
 226     GuardUnsafeAccess guard(_thread, _obj);
 227 
 228     T* p = (T*)addr();
 229 
 230     if (support_IRIW_for_not_multiple_copy_atomic_cpu) {
 231       OrderAccess::fence();
 232     }
 233 
 234     T x = OrderAccess::load_acquire((volatile T*)p);
 235 
 236     return normalize_for_read(x);
 237   }
 238 
 239   template <typename T>
 240   void put_volatile(T x) {
 241     GuardUnsafeAccess guard(_thread, _obj);
 242 
 243     T* p = (T*)addr();
 244 
 245     OrderAccess::release_store_fence((volatile T*)p, normalize_for_write(x));
 246   }
 247 
 248 
 249 #ifndef SUPPORTS_NATIVE_CX8
 250   jlong get_jlong_locked() {
 251     GuardUnsafeAccess guard(_thread, _obj);
 252 
 253     MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
 254 
 255     jlong* p = (jlong*)addr();
 256 
 257     jlong x = Atomic::load(p);
 258 
 259     return x;
 260   }
 261 
 262   void put_jlong_locked(jlong x) {
 263     GuardUnsafeAccess guard(_thread, _obj);
 264 
 265     MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
 266 
 267     jlong* p = (jlong*)addr();
 268 
 269     Atomic::store(normalize_for_write(x),  p);
 270   }
 271 #endif
 272 };
 273 
 274 // Get/PutObject must be special-cased, since it works with handles.
 275 
 276 // We could be accessing the referent field in a reference
 277 // object. If G1 is enabled then we need to register non-null
 278 // referent with the SATB barrier.
 279 
 280 #if INCLUDE_ALL_GCS
 281 static bool is_java_lang_ref_Reference_access(oop o, jlong offset) {
 282   if (offset == java_lang_ref_Reference::referent_offset && o != NULL) {
 283     Klass* k = o->klass();
 284     if (InstanceKlass::cast(k)->reference_type() != REF_NONE) {
 285       assert(InstanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity");
 286       return true;
 287     }
 288   }
 289   return false;
 290 }
 291 #endif
 292 
 293 static void ensure_satb_referent_alive(oop o, jlong offset, oop v) {
 294 #if INCLUDE_ALL_GCS
 295   if (UseG1GC && v != NULL && is_java_lang_ref_Reference_access(o, offset)) {
 296     G1SATBCardTableModRefBS::enqueue(v);
 297   }
 298 #endif
 299 }
 300 
 301 // These functions allow a null base pointer with an arbitrary address.
 302 // But if the base pointer is non-null, the offset should make some sense.
 303 // That is, it should be in the range [0, MAX_OBJECT_SIZE].
 304 UNSAFE_ENTRY(jobject, Unsafe_GetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
 305   oop p = JNIHandles::resolve(obj);
 306   oop v;
 307 
 308   if (UseCompressedOops) {
 309     narrowOop n = *(narrowOop*)index_oop_from_field_offset_long(p, offset);
 310     v = oopDesc::decode_heap_oop(n);
 311   } else {
 312     v = *(oop*)index_oop_from_field_offset_long(p, offset);
 313   }
 314 
 315   ensure_satb_referent_alive(p, offset, v);
 316 
 317   return JNIHandles::make_local(env, v);
 318 } UNSAFE_END
 319 
 320 UNSAFE_ENTRY(void, Unsafe_PutObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
 321   oop x = JNIHandles::resolve(x_h);
 322   oop p = JNIHandles::resolve(obj);
 323 
 324   if (UseCompressedOops) {
 325     oop_store((narrowOop*)index_oop_from_field_offset_long(p, offset), x);
 326   } else {
 327     oop_store((oop*)index_oop_from_field_offset_long(p, offset), x);
 328   }
 329 } UNSAFE_END
 330 
 331 UNSAFE_ENTRY(jobject, Unsafe_GetObjectVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
 332   oop p = JNIHandles::resolve(obj);
 333   void* addr = index_oop_from_field_offset_long(p, offset);
 334 
 335   volatile oop v;
 336 
 337   if (support_IRIW_for_not_multiple_copy_atomic_cpu) {
 338     OrderAccess::fence();
 339   }
 340 
 341   if (UseCompressedOops) {
 342     volatile narrowOop n = *(volatile narrowOop*) addr;
 343     (void)const_cast<oop&>(v = oopDesc::decode_heap_oop(n));
 344   } else {
 345     (void)const_cast<oop&>(v = *(volatile oop*) addr);
 346   }
 347 
 348   ensure_satb_referent_alive(p, offset, v);
 349 
 350   OrderAccess::acquire();
 351   return JNIHandles::make_local(env, v);
 352 } UNSAFE_END
 353 
 354 UNSAFE_ENTRY(void, Unsafe_PutObjectVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
 355   oop x = JNIHandles::resolve(x_h);
 356   oop p = JNIHandles::resolve(obj);
 357   void* addr = index_oop_from_field_offset_long(p, offset);
 358   OrderAccess::release();
 359 
 360   if (UseCompressedOops) {
 361     oop_store((narrowOop*)addr, x);
 362   } else {
 363     oop_store((oop*)addr, x);
 364   }
 365 
 366   OrderAccess::fence();
 367 } UNSAFE_END
 368 
 369 UNSAFE_ENTRY(jobject, Unsafe_GetUncompressedObject(JNIEnv *env, jobject unsafe, jlong addr)) {
 370   oop v = *(oop*) (address) addr;
 371 
 372   return JNIHandles::make_local(env, v);
 373 } UNSAFE_END
 374 
 375 #ifndef SUPPORTS_NATIVE_CX8
 376 
 377 // VM_Version::supports_cx8() is a surrogate for 'supports atomic long memory ops'.
 378 //
 379 // On platforms which do not support atomic compare-and-swap of jlong (8 byte)
 380 // values we have to use a lock-based scheme to enforce atomicity. This has to be
 381 // applied to all Unsafe operations that set the value of a jlong field. Even so
 382 // the compareAndSetLong operation will not be atomic with respect to direct stores
 383 // to the field from Java code. It is important therefore that any Java code that
 384 // utilizes these Unsafe jlong operations does not perform direct stores. To permit
 385 // direct loads of the field from Java code we must also use Atomic::store within the
 386 // locked regions. And for good measure, in case there are direct stores, we also
 387 // employ Atomic::load within those regions. Note that the field in question must be
 388 // volatile and so must have atomic load/store accesses applied at the Java level.
 389 //
 390 // The locking scheme could utilize a range of strategies for controlling the locking
 391 // granularity: from a lock per-field through to a single global lock. The latter is
 392 // the simplest and is used for the current implementation. Note that the Java object
 393 // that contains the field, can not, in general, be used for locking. To do so can lead
 394 // to deadlocks as we may introduce locking into what appears to the Java code to be a
 395 // lock-free path.
 396 //
 397 // As all the locked-regions are very short and themselves non-blocking we can treat
 398 // them as leaf routines and elide safepoint checks (ie we don't perform any thread
 399 // state transitions even when blocking for the lock). Note that if we do choose to
 400 // add safepoint checks and thread state transitions, we must ensure that we calculate
 401 // the address of the field _after_ we have acquired the lock, else the object may have
 402 // been moved by the GC
 403 
 404 UNSAFE_ENTRY(jlong, Unsafe_GetLongVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
 405   if (VM_Version::supports_cx8()) {
 406     return MemoryAccess(thread, obj, offset).get_volatile<jlong>();
 407   } else {
 408     return MemoryAccess(thread, obj, offset).get_jlong_locked();
 409   }
 410 } UNSAFE_END
 411 
 412 UNSAFE_ENTRY(void, Unsafe_PutLongVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong x)) {
 413   if (VM_Version::supports_cx8()) {
 414     MemoryAccess(thread, obj, offset).put_volatile<jlong>(x);
 415   } else {
 416     MemoryAccess(thread, obj, offset).put_jlong_locked(x);
 417   }
 418 } UNSAFE_END
 419 
 420 #endif // not SUPPORTS_NATIVE_CX8
 421 
 422 UNSAFE_LEAF(jboolean, Unsafe_isBigEndian0(JNIEnv *env, jobject unsafe)) {
 423 #ifdef VM_LITTLE_ENDIAN
 424   return false;
 425 #else
 426   return true;
 427 #endif
 428 } UNSAFE_END
 429 
 430 UNSAFE_LEAF(jint, Unsafe_unalignedAccess0(JNIEnv *env, jobject unsafe)) {
 431   return UseUnalignedAccesses;
 432 } UNSAFE_END
 433 
 434 #define DEFINE_GETSETOOP(java_type, Type) \
 435  \
 436 UNSAFE_ENTRY(java_type, Unsafe_Get##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
 437   return MemoryAccess(thread, obj, offset).get<java_type>(); \
 438 } UNSAFE_END \
 439  \
 440 UNSAFE_ENTRY(void, Unsafe_Put##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
 441   MemoryAccess(thread, obj, offset).put<java_type>(x); \
 442 } UNSAFE_END \
 443  \
 444 // END DEFINE_GETSETOOP.
 445 
 446 DEFINE_GETSETOOP(jboolean, Boolean)
 447 DEFINE_GETSETOOP(jbyte, Byte)
 448 DEFINE_GETSETOOP(jshort, Short);
 449 DEFINE_GETSETOOP(jchar, Char);
 450 DEFINE_GETSETOOP(jint, Int);
 451 DEFINE_GETSETOOP(jlong, Long);
 452 DEFINE_GETSETOOP(jfloat, Float);
 453 DEFINE_GETSETOOP(jdouble, Double);
 454 
 455 #undef DEFINE_GETSETOOP
 456 
 457 #define DEFINE_GETSETOOP_VOLATILE(java_type, Type) \
 458  \
 459 UNSAFE_ENTRY(java_type, Unsafe_Get##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
 460   return MemoryAccess(thread, obj, offset).get_volatile<java_type>(); \
 461 } UNSAFE_END \
 462  \
 463 UNSAFE_ENTRY(void, Unsafe_Put##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
 464   MemoryAccess(thread, obj, offset).put_volatile<java_type>(x); \
 465 } UNSAFE_END \
 466  \
 467 // END DEFINE_GETSETOOP_VOLATILE.
 468 
 469 DEFINE_GETSETOOP_VOLATILE(jboolean, Boolean)
 470 DEFINE_GETSETOOP_VOLATILE(jbyte, Byte)
 471 DEFINE_GETSETOOP_VOLATILE(jshort, Short);
 472 DEFINE_GETSETOOP_VOLATILE(jchar, Char);
 473 DEFINE_GETSETOOP_VOLATILE(jint, Int);
 474 DEFINE_GETSETOOP_VOLATILE(jfloat, Float);
 475 DEFINE_GETSETOOP_VOLATILE(jdouble, Double);
 476 
 477 #ifdef SUPPORTS_NATIVE_CX8
 478 DEFINE_GETSETOOP_VOLATILE(jlong, Long);
 479 #endif
 480 
 481 #undef DEFINE_GETSETOOP_VOLATILE
 482 
 483 UNSAFE_LEAF(void, Unsafe_LoadFence(JNIEnv *env, jobject unsafe)) {
 484   OrderAccess::acquire();
 485 } UNSAFE_END
 486 
 487 UNSAFE_LEAF(void, Unsafe_StoreFence(JNIEnv *env, jobject unsafe)) {
 488   OrderAccess::release();
 489 } UNSAFE_END
 490 
 491 UNSAFE_LEAF(void, Unsafe_FullFence(JNIEnv *env, jobject unsafe)) {
 492   OrderAccess::fence();
 493 } UNSAFE_END
 494 
 495 ////// Allocation requests
 496 
 497 UNSAFE_ENTRY(jobject, Unsafe_AllocateInstance(JNIEnv *env, jobject unsafe, jclass cls)) {
 498   ThreadToNativeFromVM ttnfv(thread);
 499   return env->AllocObject(cls);
 500 } UNSAFE_END
 501 
 502 UNSAFE_ENTRY(jlong, Unsafe_AllocateMemory0(JNIEnv *env, jobject unsafe, jlong size)) {
 503   size_t sz = (size_t)size;
 504 
 505   sz = round_to(sz, HeapWordSize);
 506   void* x = os::malloc(sz, mtInternal);
 507 
 508   return addr_to_java(x);
 509 } UNSAFE_END
 510 
 511 UNSAFE_ENTRY(jlong, Unsafe_ReallocateMemory0(JNIEnv *env, jobject unsafe, jlong addr, jlong size)) {
 512   void* p = addr_from_java(addr);
 513   size_t sz = (size_t)size;
 514   sz = round_to(sz, HeapWordSize);
 515 
 516   void* x = os::realloc(p, sz, mtInternal);
 517 
 518   return addr_to_java(x);
 519 } UNSAFE_END
 520 
 521 UNSAFE_ENTRY(void, Unsafe_FreeMemory0(JNIEnv *env, jobject unsafe, jlong addr)) {
 522   void* p = addr_from_java(addr);
 523 
 524   os::free(p);
 525 } UNSAFE_END
 526 
 527 UNSAFE_ENTRY(void, Unsafe_SetMemory0(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong size, jbyte value)) {
 528   size_t sz = (size_t)size;
 529 
 530   oop base = JNIHandles::resolve(obj);
 531   void* p = index_oop_from_field_offset_long(base, offset);
 532 
 533   Copy::fill_to_memory_atomic(p, sz, value);
 534 } UNSAFE_END
 535 
 536 UNSAFE_ENTRY(void, Unsafe_CopyMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size)) {
 537   size_t sz = (size_t)size;
 538 
 539   oop srcp = JNIHandles::resolve(srcObj);
 540   oop dstp = JNIHandles::resolve(dstObj);
 541 
 542   void* src = index_oop_from_field_offset_long(srcp, srcOffset);
 543   void* dst = index_oop_from_field_offset_long(dstp, dstOffset);
 544 
 545   Copy::conjoint_memory_atomic(src, dst, sz);
 546 } UNSAFE_END
 547 
 548 // This function is a leaf since if the source and destination are both in native memory
 549 // the copy may potentially be very large, and we don't want to disable GC if we can avoid it.
 550 // If either source or destination (or both) are on the heap, the function will enter VM using
 551 // JVM_ENTRY_FROM_LEAF
 552 UNSAFE_LEAF(void, Unsafe_CopySwapMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size, jlong elemSize)) {
 553   size_t sz = (size_t)size;
 554   size_t esz = (size_t)elemSize;
 555 
 556   if (srcObj == NULL && dstObj == NULL) {
 557     // Both src & dst are in native memory
 558     address src = (address)srcOffset;
 559     address dst = (address)dstOffset;
 560 
 561     Copy::conjoint_swap(src, dst, sz, esz);
 562   } else {
 563     // At least one of src/dst are on heap, transition to VM to access raw pointers
 564 
 565     JVM_ENTRY_FROM_LEAF(env, void, Unsafe_CopySwapMemory0) {
 566       oop srcp = JNIHandles::resolve(srcObj);
 567       oop dstp = JNIHandles::resolve(dstObj);
 568 
 569       address src = (address)index_oop_from_field_offset_long(srcp, srcOffset);
 570       address dst = (address)index_oop_from_field_offset_long(dstp, dstOffset);
 571 
 572       Copy::conjoint_swap(src, dst, sz, esz);
 573     } JVM_END
 574   }
 575 } UNSAFE_END
 576 
 577 ////// Random queries
 578 
 579 UNSAFE_LEAF(jint, Unsafe_AddressSize0(JNIEnv *env, jobject unsafe)) {
 580   return sizeof(void*);
 581 } UNSAFE_END
 582 
 583 UNSAFE_LEAF(jint, Unsafe_PageSize()) {
 584   return os::vm_page_size();
 585 } UNSAFE_END
 586 
 587 static jint find_field_offset(jclass clazz, jstring name, TRAPS) {
 588   assert(clazz != NULL, "clazz must not be NULL");
 589   assert(name != NULL, "name must not be NULL");
 590 
 591   ResourceMark rm(THREAD);
 592   char *utf_name = java_lang_String::as_utf8_string(JNIHandles::resolve_non_null(name));
 593 
 594   InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(JNIHandles::resolve_non_null(clazz)));
 595 
 596   jint offset = -1;
 597   for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
 598     Symbol *name = fs.name();
 599     if (name->equals(utf_name)) {
 600       offset = fs.offset();
 601       break;
 602     }
 603   }
 604   if (offset < 0) {
 605     THROW_0(vmSymbols::java_lang_InternalError());
 606   }
 607   return field_offset_from_byte_offset(offset);
 608 }
 609 
 610 static jint find_field_offset(jobject field, int must_be_static, TRAPS) {
 611   assert(field != NULL, "field must not be NULL");
 612 
 613   oop reflected   = JNIHandles::resolve_non_null(field);
 614   oop mirror      = java_lang_reflect_Field::clazz(reflected);
 615   Klass* k        = java_lang_Class::as_Klass(mirror);
 616   int slot        = java_lang_reflect_Field::slot(reflected);
 617   int modifiers   = java_lang_reflect_Field::modifiers(reflected);
 618 
 619   if (must_be_static >= 0) {
 620     int really_is_static = ((modifiers & JVM_ACC_STATIC) != 0);
 621     if (must_be_static != really_is_static) {
 622       THROW_0(vmSymbols::java_lang_IllegalArgumentException());
 623     }
 624   }
 625 
 626   int offset = InstanceKlass::cast(k)->field_offset(slot);
 627   return field_offset_from_byte_offset(offset);
 628 }
 629 
 630 UNSAFE_ENTRY(jlong, Unsafe_ObjectFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
 631   return find_field_offset(field, 0, THREAD);
 632 } UNSAFE_END
 633 
 634 UNSAFE_ENTRY(jlong, Unsafe_ObjectFieldOffset1(JNIEnv *env, jobject unsafe, jclass c, jstring name)) {
 635   return find_field_offset(c, name, THREAD);
 636 } UNSAFE_END
 637 
 638 UNSAFE_ENTRY(jlong, Unsafe_StaticFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
 639   return find_field_offset(field, 1, THREAD);
 640 } UNSAFE_END
 641 
 642 UNSAFE_ENTRY(jobject, Unsafe_StaticFieldBase0(JNIEnv *env, jobject unsafe, jobject field)) {
 643   assert(field != NULL, "field must not be NULL");
 644 
 645   // Note:  In this VM implementation, a field address is always a short
 646   // offset from the base of a a klass metaobject.  Thus, the full dynamic
 647   // range of the return type is never used.  However, some implementations
 648   // might put the static field inside an array shared by many classes,
 649   // or even at a fixed address, in which case the address could be quite
 650   // large.  In that last case, this function would return NULL, since
 651   // the address would operate alone, without any base pointer.
 652 
 653   oop reflected   = JNIHandles::resolve_non_null(field);
 654   oop mirror      = java_lang_reflect_Field::clazz(reflected);
 655   int modifiers   = java_lang_reflect_Field::modifiers(reflected);
 656 
 657   if ((modifiers & JVM_ACC_STATIC) == 0) {
 658     THROW_0(vmSymbols::java_lang_IllegalArgumentException());
 659   }
 660 
 661   return JNIHandles::make_local(env, mirror);
 662 } UNSAFE_END
 663 
 664 UNSAFE_ENTRY(void, Unsafe_EnsureClassInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
 665   assert(clazz != NULL, "clazz must not be NULL");
 666 
 667   oop mirror = JNIHandles::resolve_non_null(clazz);
 668 
 669   Klass* klass = java_lang_Class::as_Klass(mirror);
 670   if (klass != NULL && klass->should_be_initialized()) {
 671     InstanceKlass* k = InstanceKlass::cast(klass);
 672     k->initialize(CHECK);
 673   }
 674 }
 675 UNSAFE_END
 676 
 677 UNSAFE_ENTRY(jboolean, Unsafe_ShouldBeInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
 678   assert(clazz != NULL, "clazz must not be NULL");
 679 
 680   oop mirror = JNIHandles::resolve_non_null(clazz);
 681   Klass* klass = java_lang_Class::as_Klass(mirror);
 682 
 683   if (klass != NULL && klass->should_be_initialized()) {
 684     return true;
 685   }
 686 
 687   return false;
 688 }
 689 UNSAFE_END
 690 
 691 static void getBaseAndScale(int& base, int& scale, jclass clazz, TRAPS) {
 692   assert(clazz != NULL, "clazz must not be NULL");
 693 
 694   oop mirror = JNIHandles::resolve_non_null(clazz);
 695   Klass* k = java_lang_Class::as_Klass(mirror);
 696 
 697   if (k == NULL || !k->is_array_klass()) {
 698     THROW(vmSymbols::java_lang_InvalidClassException());
 699   } else if (k->is_objArray_klass()) {
 700     base  = arrayOopDesc::base_offset_in_bytes(T_OBJECT);
 701     scale = heapOopSize;
 702   } else if (k->is_typeArray_klass()) {
 703     TypeArrayKlass* tak = TypeArrayKlass::cast(k);
 704     base  = tak->array_header_in_bytes();
 705     assert(base == arrayOopDesc::base_offset_in_bytes(tak->element_type()), "array_header_size semantics ok");
 706     scale = (1 << tak->log2_element_size());
 707   } else {
 708     ShouldNotReachHere();
 709   }
 710 }
 711 
 712 UNSAFE_ENTRY(jint, Unsafe_ArrayBaseOffset0(JNIEnv *env, jobject unsafe, jclass clazz)) {
 713   int base = 0, scale = 0;
 714   getBaseAndScale(base, scale, clazz, CHECK_0);
 715 
 716   return field_offset_from_byte_offset(base);
 717 } UNSAFE_END
 718 
 719 
 720 UNSAFE_ENTRY(jint, Unsafe_ArrayIndexScale0(JNIEnv *env, jobject unsafe, jclass clazz)) {
 721   int base = 0, scale = 0;
 722   getBaseAndScale(base, scale, clazz, CHECK_0);
 723 
 724   // This VM packs both fields and array elements down to the byte.
 725   // But watch out:  If this changes, so that array references for
 726   // a given primitive type (say, T_BOOLEAN) use different memory units
 727   // than fields, this method MUST return zero for such arrays.
 728   // For example, the VM used to store sub-word sized fields in full
 729   // words in the object layout, so that accessors like getByte(Object,int)
 730   // did not really do what one might expect for arrays.  Therefore,
 731   // this function used to report a zero scale factor, so that the user
 732   // would know not to attempt to access sub-word array elements.
 733   // // Code for unpacked fields:
 734   // if (scale < wordSize)  return 0;
 735 
 736   // The following allows for a pretty general fieldOffset cookie scheme,
 737   // but requires it to be linear in byte offset.
 738   return field_offset_from_byte_offset(scale) - field_offset_from_byte_offset(0);
 739 } UNSAFE_END
 740 
 741 
 742 static inline void throw_new(JNIEnv *env, const char *ename) {
 743   jclass cls = env->FindClass(ename);
 744   if (env->ExceptionCheck()) {
 745     env->ExceptionClear();
 746     tty->print_cr("Unsafe: cannot throw %s because FindClass has failed", ename);
 747     return;
 748   }
 749 
 750   env->ThrowNew(cls, NULL);
 751 }
 752 
 753 static jclass Unsafe_DefineClass_impl(JNIEnv *env, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd) {
 754   // Code lifted from JDK 1.3 ClassLoader.c
 755 
 756   jbyte *body;
 757   char *utfName = NULL;
 758   jclass result = 0;
 759   char buf[128];
 760 
 761   assert(data != NULL, "Class bytes must not be NULL");
 762   assert(length >= 0, "length must not be negative: %d", length);
 763 
 764   if (UsePerfData) {
 765     ClassLoader::unsafe_defineClassCallCounter()->inc();
 766   }
 767 
 768   body = NEW_C_HEAP_ARRAY(jbyte, length, mtInternal);
 769   if (body == NULL) {
 770     throw_new(env, "java/lang/OutOfMemoryError");
 771     return 0;
 772   }
 773 
 774   env->GetByteArrayRegion(data, offset, length, body);
 775   if (env->ExceptionOccurred()) {
 776     goto free_body;
 777   }
 778 
 779   if (name != NULL) {
 780     uint len = env->GetStringUTFLength(name);
 781     int unicode_len = env->GetStringLength(name);
 782 
 783     if (len >= sizeof(buf)) {
 784       utfName = NEW_C_HEAP_ARRAY(char, len + 1, mtInternal);
 785       if (utfName == NULL) {
 786         throw_new(env, "java/lang/OutOfMemoryError");
 787         goto free_body;
 788       }
 789     } else {
 790       utfName = buf;
 791     }
 792 
 793     env->GetStringUTFRegion(name, 0, unicode_len, utfName);
 794 
 795     for (uint i = 0; i < len; i++) {
 796       if (utfName[i] == '.')   utfName[i] = '/';
 797     }
 798   }
 799 
 800   result = JVM_DefineClass(env, utfName, loader, body, length, pd);
 801 
 802   if (utfName && utfName != buf) {
 803     FREE_C_HEAP_ARRAY(char, utfName);
 804   }
 805 
 806  free_body:
 807   FREE_C_HEAP_ARRAY(jbyte, body);
 808   return result;
 809 }
 810 
 811 
 812 UNSAFE_ENTRY(jclass, Unsafe_DefineClass0(JNIEnv *env, jobject unsafe, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd)) {
 813   ThreadToNativeFromVM ttnfv(thread);
 814 
 815   return Unsafe_DefineClass_impl(env, name, data, offset, length, loader, pd);
 816 } UNSAFE_END
 817 
 818 
 819 // define a class but do not make it known to the class loader or system dictionary
 820 // - host_class:  supplies context for linkage, access control, protection domain, and class loader
 821 //                if host_class is itself anonymous then it is replaced with its host class.
 822 // - data:  bytes of a class file, a raw memory address (length gives the number of bytes)
 823 // - cp_patches:  where non-null entries exist, they replace corresponding CP entries in data
 824 
 825 // When you load an anonymous class U, it works as if you changed its name just before loading,
 826 // to a name that you will never use again.  Since the name is lost, no other class can directly
 827 // link to any member of U.  Just after U is loaded, the only way to use it is reflectively,
 828 // through java.lang.Class methods like Class.newInstance.
 829 
 830 // The package of an anonymous class must either match its host's class's package or be in the
 831 // unnamed package.  If it is in the unnamed package then it will be put in its host class's
 832 // package.
 833 //
 834 
 835 // Access checks for linkage sites within U continue to follow the same rules as for named classes.
 836 // An anonymous class also has special privileges to access any member of its host class.
 837 // This is the main reason why this loading operation is unsafe.  The purpose of this is to
 838 // allow language implementations to simulate "open classes"; a host class in effect gets
 839 // new code when an anonymous class is loaded alongside it.  A less convenient but more
 840 // standard way to do this is with reflection, which can also be set to ignore access
 841 // restrictions.
 842 
 843 // Access into an anonymous class is possible only through reflection.  Therefore, there
 844 // are no special access rules for calling into an anonymous class.  The relaxed access
 845 // rule for the host class is applied in the opposite direction:  A host class reflectively
 846 // access one of its anonymous classes.
 847 
 848 // If you load the same bytecodes twice, you get two different classes.  You can reload
 849 // the same bytecodes with or without varying CP patches.
 850 
 851 // By using the CP patching array, you can have a new anonymous class U2 refer to an older one U1.
 852 // The bytecodes for U2 should refer to U1 by a symbolic name (doesn't matter what the name is).
 853 // The CONSTANT_Class entry for that name can be patched to refer directly to U1.
 854 
 855 // This allows, for example, U2 to use U1 as a superclass or super-interface, or as
 856 // an outer class (so that U2 is an anonymous inner class of anonymous U1).
 857 // It is not possible for a named class, or an older anonymous class, to refer by
 858 // name (via its CP) to a newer anonymous class.
 859 
 860 // CP patching may also be used to modify (i.e., hack) the names of methods, classes,
 861 // or type descriptors used in the loaded anonymous class.
 862 
 863 // Finally, CP patching may be used to introduce "live" objects into the constant pool,
 864 // instead of "dead" strings.  A compiled statement like println((Object)"hello") can
 865 // be changed to println(greeting), where greeting is an arbitrary object created before
 866 // the anonymous class is loaded.  This is useful in dynamic languages, in which
 867 // various kinds of metaobjects must be introduced as constants into bytecode.
 868 // Note the cast (Object), which tells the verifier to expect an arbitrary object,
 869 // not just a literal string.  For such ldc instructions, the verifier uses the
 870 // type Object instead of String, if the loaded constant is not in fact a String.
 871 
 872 static InstanceKlass*
 873 Unsafe_DefineAnonymousClass_impl(JNIEnv *env,
 874                                  jclass host_class, jbyteArray data, jobjectArray cp_patches_jh,
 875                                  u1** temp_alloc,
 876                                  TRAPS) {
 877   assert(host_class != NULL, "host_class must not be NULL");
 878   assert(data != NULL, "data must not be NULL");
 879 
 880   if (UsePerfData) {
 881     ClassLoader::unsafe_defineClassCallCounter()->inc();
 882   }
 883 
 884   jint length = typeArrayOop(JNIHandles::resolve_non_null(data))->length();
 885   assert(length >= 0, "class_bytes_length must not be negative: %d", length);
 886 
 887   int class_bytes_length = (int) length;
 888 
 889   u1* class_bytes = NEW_C_HEAP_ARRAY(u1, length, mtInternal);
 890   if (class_bytes == NULL) {
 891     THROW_0(vmSymbols::java_lang_OutOfMemoryError());
 892   }
 893 
 894   // caller responsible to free it:
 895   *temp_alloc = class_bytes;
 896 
 897   jbyte* array_base = typeArrayOop(JNIHandles::resolve_non_null(data))->byte_at_addr(0);
 898   Copy::conjoint_jbytes(array_base, class_bytes, length);
 899 
 900   objArrayHandle cp_patches_h;
 901   if (cp_patches_jh != NULL) {
 902     oop p = JNIHandles::resolve_non_null(cp_patches_jh);
 903     assert(p->is_objArray(), "cp_patches must be an object[]");
 904     cp_patches_h = objArrayHandle(THREAD, (objArrayOop)p);
 905   }
 906 
 907   const Klass* host_klass = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(host_class));
 908 
 909   // Make sure it's the real host class, not another anonymous class.
 910   while (host_klass != NULL && host_klass->is_instance_klass() &&
 911          InstanceKlass::cast(host_klass)->is_anonymous()) {
 912     host_klass = InstanceKlass::cast(host_klass)->host_klass();
 913   }
 914 
 915   // Primitive types have NULL Klass* fields in their java.lang.Class instances.
 916   if (host_klass == NULL) {
 917     THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), "Host class is null");
 918   }
 919 
 920   assert(host_klass->is_instance_klass(), "Host class must be an instance class");
 921 
 922   const char* host_source = host_klass->external_name();
 923   Handle      host_loader(THREAD, host_klass->class_loader());
 924   Handle      host_domain(THREAD, host_klass->protection_domain());
 925 
 926   GrowableArray<Handle>* cp_patches = NULL;
 927 
 928   if (cp_patches_h.not_null()) {
 929     int alen = cp_patches_h->length();
 930 
 931     for (int i = alen-1; i >= 0; i--) {
 932       oop p = cp_patches_h->obj_at(i);
 933       if (p != NULL) {
 934         Handle patch(THREAD, p);
 935 
 936         if (cp_patches == NULL) {
 937           cp_patches = new GrowableArray<Handle>(i+1, i+1, Handle());
 938         }
 939 
 940         cp_patches->at_put(i, patch);
 941       }
 942     }
 943   }
 944 
 945   ClassFileStream st(class_bytes, class_bytes_length, host_source, ClassFileStream::verify);
 946 
 947   Symbol* no_class_name = NULL;
 948   Klass* anonk = SystemDictionary::parse_stream(no_class_name,
 949                                                 host_loader,
 950                                                 host_domain,
 951                                                 &st,
 952                                                 InstanceKlass::cast(host_klass),
 953                                                 cp_patches,
 954                                                 CHECK_NULL);
 955   if (anonk == NULL) {
 956     return NULL;
 957   }
 958 
 959   return InstanceKlass::cast(anonk);
 960 }
 961 
 962 UNSAFE_ENTRY(jclass, Unsafe_DefineAnonymousClass0(JNIEnv *env, jobject unsafe, jclass host_class, jbyteArray data, jobjectArray cp_patches_jh)) {
 963   ResourceMark rm(THREAD);
 964 
 965   jobject res_jh = NULL;
 966   u1* temp_alloc = NULL;
 967 
 968   InstanceKlass* anon_klass = Unsafe_DefineAnonymousClass_impl(env, host_class, data, cp_patches_jh, &temp_alloc, THREAD);
 969   if (anon_klass != NULL) {
 970     res_jh = JNIHandles::make_local(env, anon_klass->java_mirror());
 971   }
 972 
 973   // try/finally clause:
 974   if (temp_alloc != NULL) {
 975     FREE_C_HEAP_ARRAY(u1, temp_alloc);
 976   }
 977 
 978   // The anonymous class loader data has been artificially been kept alive to
 979   // this point.   The mirror and any instances of this class have to keep
 980   // it alive afterwards.
 981   if (anon_klass != NULL) {
 982     anon_klass->class_loader_data()->dec_keep_alive();
 983   }
 984 
 985   // let caller initialize it as needed...
 986 
 987   return (jclass) res_jh;
 988 } UNSAFE_END
 989 
 990 
 991 
 992 UNSAFE_ENTRY(void, Unsafe_ThrowException(JNIEnv *env, jobject unsafe, jthrowable thr)) {
 993   ThreadToNativeFromVM ttnfv(thread);
 994   env->Throw(thr);
 995 } UNSAFE_END
 996 
 997 // JSR166 ------------------------------------------------------------------
 998 
 999 UNSAFE_ENTRY(jobject, Unsafe_CompareAndExchangeObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
1000   oop x = JNIHandles::resolve(x_h);
1001   oop e = JNIHandles::resolve(e_h);
1002   oop p = JNIHandles::resolve(obj);
1003   HeapWord* addr = (HeapWord *)index_oop_from_field_offset_long(p, offset);
1004   oop res = oopDesc::atomic_compare_exchange_oop(x, addr, e, true);
1005   if (res == e) {
1006     update_barrier_set((void*)addr, x);
1007   }
1008   return JNIHandles::make_local(env, res);
1009 } UNSAFE_END
1010 
1011 UNSAFE_ENTRY(jint, Unsafe_CompareAndExchangeInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
1012   oop p = JNIHandles::resolve(obj);
1013   jint* addr = (jint *) index_oop_from_field_offset_long(p, offset);
1014 
1015   return (jint)(Atomic::cmpxchg(x, addr, e));
1016 } UNSAFE_END
1017 
1018 UNSAFE_ENTRY(jlong, Unsafe_CompareAndExchangeLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
1019   Handle p(THREAD, JNIHandles::resolve(obj));
1020   jlong* addr = (jlong*)index_oop_from_field_offset_long(p(), offset);
1021 
1022 #ifdef SUPPORTS_NATIVE_CX8
1023   return (jlong)(Atomic::cmpxchg(x, addr, e));
1024 #else
1025   if (VM_Version::supports_cx8()) {
1026     return (jlong)(Atomic::cmpxchg(x, addr, e));
1027   } else {
1028     MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
1029 
1030     jlong val = Atomic::load(addr);
1031     if (val == e) {
1032       Atomic::store(x, addr);
1033     }
1034     return val;
1035   }
1036 #endif
1037 } UNSAFE_END
1038 
1039 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
1040   oop x = JNIHandles::resolve(x_h);
1041   oop e = JNIHandles::resolve(e_h);
1042   oop p = JNIHandles::resolve(obj);
1043   HeapWord* addr = (HeapWord *)index_oop_from_field_offset_long(p, offset);
1044   oop res = oopDesc::atomic_compare_exchange_oop(x, addr, e, true);
1045   if (res != e) {
1046     return false;
1047   }
1048 
1049   update_barrier_set((void*)addr, x);
1050 
1051   return true;
1052 } UNSAFE_END
1053 
1054 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
1055   oop p = JNIHandles::resolve(obj);
1056   jint* addr = (jint *)index_oop_from_field_offset_long(p, offset);
1057 
1058   return (jint)(Atomic::cmpxchg(x, addr, e)) == e;
1059 } UNSAFE_END
1060 
1061 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
1062   Handle p(THREAD, JNIHandles::resolve(obj));
1063   jlong* addr = (jlong*)index_oop_from_field_offset_long(p(), offset);
1064 
1065 #ifdef SUPPORTS_NATIVE_CX8
1066   return (jlong)(Atomic::cmpxchg(x, addr, e)) == e;
1067 #else
1068   if (VM_Version::supports_cx8()) {
1069     return (jlong)(Atomic::cmpxchg(x, addr, e)) == e;
1070   } else {
1071     MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
1072 
1073     jlong val = Atomic::load(addr);
1074     if (val != e) {
1075       return false;
1076     }
1077 
1078     Atomic::store(x, addr);
1079     return true;
1080   }
1081 #endif
1082 } UNSAFE_END
1083 
1084 UNSAFE_ENTRY(void, Unsafe_Park(JNIEnv *env, jobject unsafe, jboolean isAbsolute, jlong time)) {
1085   EventThreadPark event;
1086   HOTSPOT_THREAD_PARK_BEGIN((uintptr_t) thread->parker(), (int) isAbsolute, time);
1087 
1088   JavaThreadParkedState jtps(thread, time != 0);
1089   thread->parker()->park(isAbsolute != 0, time);
1090 
1091   HOTSPOT_THREAD_PARK_END((uintptr_t) thread->parker());
1092 
1093   if (event.should_commit()) {
1094     oop obj = thread->current_park_blocker();
1095     event.set_parkedClass((obj != NULL) ? obj->klass() : NULL);
1096     event.set_timeout(time);
1097     event.set_address((obj != NULL) ? (TYPE_ADDRESS) cast_from_oop<uintptr_t>(obj) : 0);
1098     event.commit();
1099   }
1100 } UNSAFE_END
1101 
1102 UNSAFE_ENTRY(void, Unsafe_Unpark(JNIEnv *env, jobject unsafe, jobject jthread)) {
1103   Parker* p = NULL;
1104 
1105   if (jthread != NULL) {
1106     oop java_thread = JNIHandles::resolve_non_null(jthread);
1107     if (java_thread != NULL) {
1108       jlong lp = java_lang_Thread::park_event(java_thread);
1109       if (lp != 0) {
1110         // This cast is OK even though the jlong might have been read
1111         // non-atomically on 32bit systems, since there, one word will
1112         // always be zero anyway and the value set is always the same
1113         p = (Parker*)addr_from_java(lp);
1114       } else {
1115         // Grab lock if apparently null or using older version of library
1116         MutexLocker mu(Threads_lock);
1117         java_thread = JNIHandles::resolve_non_null(jthread);
1118 
1119         if (java_thread != NULL) {
1120           JavaThread* thr = java_lang_Thread::thread(java_thread);
1121           if (thr != NULL) {
1122             p = thr->parker();
1123             if (p != NULL) { // Bind to Java thread for next time.
1124               java_lang_Thread::set_park_event(java_thread, addr_to_java(p));
1125             }
1126           }
1127         }
1128       }
1129     }
1130   }
1131 
1132   if (p != NULL) {
1133     HOTSPOT_THREAD_UNPARK((uintptr_t) p);
1134     p->unpark();
1135   }
1136 } UNSAFE_END
1137 
1138 UNSAFE_ENTRY(jint, Unsafe_GetLoadAverage0(JNIEnv *env, jobject unsafe, jdoubleArray loadavg, jint nelem)) {
1139   const int max_nelem = 3;
1140   double la[max_nelem];
1141   jint ret;
1142 
1143   typeArrayOop a = typeArrayOop(JNIHandles::resolve_non_null(loadavg));
1144   assert(a->is_typeArray(), "must be type array");
1145 
1146   ret = os::loadavg(la, nelem);
1147   if (ret == -1) {
1148     return -1;
1149   }
1150 
1151   // if successful, ret is the number of samples actually retrieved.
1152   assert(ret >= 0 && ret <= max_nelem, "Unexpected loadavg return value");
1153   switch(ret) {
1154     case 3: a->double_at_put(2, (jdouble)la[2]); // fall through
1155     case 2: a->double_at_put(1, (jdouble)la[1]); // fall through
1156     case 1: a->double_at_put(0, (jdouble)la[0]); break;
1157   }
1158 
1159   return ret;
1160 } UNSAFE_END
1161 
1162 
1163 /// JVM_RegisterUnsafeMethods
1164 
1165 #define ADR "J"
1166 
1167 #define LANG "Ljava/lang/"
1168 
1169 #define OBJ LANG "Object;"
1170 #define CLS LANG "Class;"
1171 #define FLD LANG "reflect/Field;"
1172 #define THR LANG "Throwable;"
1173 
1174 #define DC_Args  LANG "String;[BII" LANG "ClassLoader;" "Ljava/security/ProtectionDomain;"
1175 #define DAC_Args CLS "[B[" OBJ
1176 
1177 #define CC (char*)  /*cast a literal from (const char*)*/
1178 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
1179 
1180 #define DECLARE_GETPUTOOP(Type, Desc) \
1181     {CC "get" #Type,      CC "(" OBJ "J)" #Desc,       FN_PTR(Unsafe_Get##Type)}, \
1182     {CC "put" #Type,      CC "(" OBJ "J" #Desc ")V",   FN_PTR(Unsafe_Put##Type)}, \
1183     {CC "get" #Type "Volatile",      CC "(" OBJ "J)" #Desc,       FN_PTR(Unsafe_Get##Type##Volatile)}, \
1184     {CC "put" #Type "Volatile",      CC "(" OBJ "J" #Desc ")V",   FN_PTR(Unsafe_Put##Type##Volatile)}
1185 
1186 
1187 static JNINativeMethod jdk_internal_misc_Unsafe_methods[] = {
1188     {CC "getObject",        CC "(" OBJ "J)" OBJ "",   FN_PTR(Unsafe_GetObject)},
1189     {CC "putObject",        CC "(" OBJ "J" OBJ ")V",  FN_PTR(Unsafe_PutObject)},
1190     {CC "getObjectVolatile",CC "(" OBJ "J)" OBJ "",   FN_PTR(Unsafe_GetObjectVolatile)},
1191     {CC "putObjectVolatile",CC "(" OBJ "J" OBJ ")V",  FN_PTR(Unsafe_PutObjectVolatile)},
1192 
1193     {CC "getUncompressedObject", CC "(" ADR ")" OBJ,  FN_PTR(Unsafe_GetUncompressedObject)},
1194 
1195     DECLARE_GETPUTOOP(Boolean, Z),
1196     DECLARE_GETPUTOOP(Byte, B),
1197     DECLARE_GETPUTOOP(Short, S),
1198     DECLARE_GETPUTOOP(Char, C),
1199     DECLARE_GETPUTOOP(Int, I),
1200     DECLARE_GETPUTOOP(Long, J),
1201     DECLARE_GETPUTOOP(Float, F),
1202     DECLARE_GETPUTOOP(Double, D),
1203 
1204     {CC "allocateMemory0",    CC "(J)" ADR,              FN_PTR(Unsafe_AllocateMemory0)},
1205     {CC "reallocateMemory0",  CC "(" ADR "J)" ADR,       FN_PTR(Unsafe_ReallocateMemory0)},
1206     {CC "freeMemory0",        CC "(" ADR ")V",           FN_PTR(Unsafe_FreeMemory0)},
1207 
1208     {CC "objectFieldOffset0", CC "(" FLD ")J",           FN_PTR(Unsafe_ObjectFieldOffset0)},
1209     {CC "objectFieldOffset1", CC "(" CLS LANG "String;)J", FN_PTR(Unsafe_ObjectFieldOffset1)},
1210     {CC "staticFieldOffset0", CC "(" FLD ")J",           FN_PTR(Unsafe_StaticFieldOffset0)},
1211     {CC "staticFieldBase0",   CC "(" FLD ")" OBJ,        FN_PTR(Unsafe_StaticFieldBase0)},
1212     {CC "ensureClassInitialized0", CC "(" CLS ")V",      FN_PTR(Unsafe_EnsureClassInitialized0)},
1213     {CC "arrayBaseOffset0",   CC "(" CLS ")I",           FN_PTR(Unsafe_ArrayBaseOffset0)},
1214     {CC "arrayIndexScale0",   CC "(" CLS ")I",           FN_PTR(Unsafe_ArrayIndexScale0)},
1215     {CC "addressSize0",       CC "()I",                  FN_PTR(Unsafe_AddressSize0)},
1216     {CC "pageSize",           CC "()I",                  FN_PTR(Unsafe_PageSize)},
1217 
1218     {CC "defineClass0",       CC "(" DC_Args ")" CLS,    FN_PTR(Unsafe_DefineClass0)},
1219     {CC "allocateInstance",   CC "(" CLS ")" OBJ,        FN_PTR(Unsafe_AllocateInstance)},
1220     {CC "throwException",     CC "(" THR ")V",           FN_PTR(Unsafe_ThrowException)},
1221     {CC "compareAndSetObject",CC "(" OBJ "J" OBJ "" OBJ ")Z", FN_PTR(Unsafe_CompareAndSetObject)},
1222     {CC "compareAndSetInt",   CC "(" OBJ "J""I""I"")Z",  FN_PTR(Unsafe_CompareAndSetInt)},
1223     {CC "compareAndSetLong",  CC "(" OBJ "J""J""J"")Z",  FN_PTR(Unsafe_CompareAndSetLong)},
1224     {CC "compareAndExchangeObject", CC "(" OBJ "J" OBJ "" OBJ ")" OBJ, FN_PTR(Unsafe_CompareAndExchangeObject)},
1225     {CC "compareAndExchangeInt",  CC "(" OBJ "J""I""I"")I", FN_PTR(Unsafe_CompareAndExchangeInt)},
1226     {CC "compareAndExchangeLong", CC "(" OBJ "J""J""J"")J", FN_PTR(Unsafe_CompareAndExchangeLong)},
1227 
1228     {CC "park",               CC "(ZJ)V",                FN_PTR(Unsafe_Park)},
1229     {CC "unpark",             CC "(" OBJ ")V",           FN_PTR(Unsafe_Unpark)},
1230 
1231     {CC "getLoadAverage0",    CC "([DI)I",               FN_PTR(Unsafe_GetLoadAverage0)},
1232 
1233     {CC "copyMemory0",        CC "(" OBJ "J" OBJ "JJ)V", FN_PTR(Unsafe_CopyMemory0)},
1234     {CC "copySwapMemory0",    CC "(" OBJ "J" OBJ "JJJ)V", FN_PTR(Unsafe_CopySwapMemory0)},
1235     {CC "setMemory0",         CC "(" OBJ "JJB)V",        FN_PTR(Unsafe_SetMemory0)},
1236 
1237     {CC "defineAnonymousClass0", CC "(" DAC_Args ")" CLS, FN_PTR(Unsafe_DefineAnonymousClass0)},
1238 
1239     {CC "shouldBeInitialized0", CC "(" CLS ")Z",         FN_PTR(Unsafe_ShouldBeInitialized0)},
1240 
1241     {CC "loadFence",          CC "()V",                  FN_PTR(Unsafe_LoadFence)},
1242     {CC "storeFence",         CC "()V",                  FN_PTR(Unsafe_StoreFence)},
1243     {CC "fullFence",          CC "()V",                  FN_PTR(Unsafe_FullFence)},
1244 
1245     {CC "isBigEndian0",       CC "()Z",                  FN_PTR(Unsafe_isBigEndian0)},
1246     {CC "unalignedAccess0",   CC "()Z",                  FN_PTR(Unsafe_unalignedAccess0)}
1247 };
1248 
1249 #undef CC
1250 #undef FN_PTR
1251 
1252 #undef ADR
1253 #undef LANG
1254 #undef OBJ
1255 #undef CLS
1256 #undef FLD
1257 #undef THR
1258 #undef DC_Args
1259 #undef DAC_Args
1260 
1261 #undef DECLARE_GETPUTOOP
1262 
1263 
1264 // This function is exported, used by NativeLookup.
1265 // The Unsafe_xxx functions above are called only from the interpreter.
1266 // The optimizer looks at names and signatures to recognize
1267 // individual functions.
1268 
1269 JVM_ENTRY(void, JVM_RegisterJDKInternalMiscUnsafeMethods(JNIEnv *env, jclass unsafeclass)) {
1270   ThreadToNativeFromVM ttnfv(thread);
1271 
1272   int ok = env->RegisterNatives(unsafeclass, jdk_internal_misc_Unsafe_methods, sizeof(jdk_internal_misc_Unsafe_methods)/sizeof(JNINativeMethod));
1273   guarantee(ok == 0, "register jdk.internal.misc.Unsafe natives");
1274 } JVM_END