1 /*
   2  * Copyright (c) 2000, 2016, 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/objArrayOop.inline.hpp"
  31 #include "oops/oop.inline.hpp"
  32 #include "prims/jni.h"
  33 #include "prims/jvm.h"
  34 #include "prims/unsafe.hpp"
  35 #include "runtime/atomic.inline.hpp"
  36 #include "runtime/globals.hpp"
  37 #include "runtime/interfaceSupport.hpp"
  38 #include "runtime/orderAccess.inline.hpp"
  39 #include "runtime/reflection.hpp"
  40 #include "runtime/vm_version.hpp"
  41 #include "services/threadService.hpp"
  42 #include "trace/tracing.hpp"
  43 #include "utilities/copy.hpp"
  44 #include "utilities/dtrace.hpp"
  45 #include "utilities/macros.hpp"
  46 #if INCLUDE_ALL_GCS
  47 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
  48 #endif // INCLUDE_ALL_GCS
  49 
  50 /**
  51  * Implementation of the jdk.internal.misc.Unsafe class
  52  */
  53 
  54 
  55 #define MAX_OBJECT_SIZE \
  56   ( arrayOopDesc::header_size(T_DOUBLE) * HeapWordSize \
  57     + ((julong)max_jint * sizeof(double)) )
  58 
  59 
  60 #define UNSAFE_ENTRY(result_type, header) \
  61   JVM_ENTRY(static result_type, header)
  62 
  63 #define UNSAFE_LEAF(result_type, header) \
  64   JVM_LEAF(static result_type, header)
  65 
  66 #define UNSAFE_END JVM_END
  67 
  68 
  69 static inline void* addr_from_java(jlong addr) {
  70   // This assert fails in a variety of ways on 32-bit systems.
  71   // It is impossible to predict whether native code that converts
  72   // pointers to longs will sign-extend or zero-extend the addresses.
  73   //assert(addr == (uintptr_t)addr, "must not be odd high bits");
  74   return (void*)(uintptr_t)addr;
  75 }
  76 
  77 static inline jlong addr_to_java(void* p) {
  78   assert(p == (void*)(uintptr_t)p, "must not be odd high bits");
  79   return (uintptr_t)p;
  80 }
  81 
  82 
  83 // Note: The VM's obj_field and related accessors use byte-scaled
  84 // ("unscaled") offsets, just as the unsafe methods do.
  85 
  86 // However, the method Unsafe.fieldOffset explicitly declines to
  87 // guarantee this.  The field offset values manipulated by the Java user
  88 // through the Unsafe API are opaque cookies that just happen to be byte
  89 // offsets.  We represent this state of affairs by passing the cookies
  90 // through conversion functions when going between the VM and the Unsafe API.
  91 // The conversion functions just happen to be no-ops at present.
  92 
  93 static inline jlong field_offset_to_byte_offset(jlong field_offset) {
  94   return field_offset;
  95 }
  96 
  97 static inline jlong field_offset_from_byte_offset(jlong byte_offset) {
  98   return byte_offset;
  99 }
 100 
 101 static inline void* index_oop_from_field_offset_long(oop p, jlong field_offset) {
 102   jlong byte_offset = field_offset_to_byte_offset(field_offset);
 103 
 104 #ifdef ASSERT
 105   if (p != NULL) {
 106     assert(byte_offset >= 0 && byte_offset <= (jlong)MAX_OBJECT_SIZE, "sane offset");
 107     if (byte_offset == (jint)byte_offset) {
 108       void* ptr_plus_disp = (address)p + byte_offset;
 109       assert((void*)p->obj_field_addr<oop>((jint)byte_offset) == ptr_plus_disp,
 110              "raw [ptr+disp] must be consistent with oop::field_base");
 111     }
 112     jlong p_size = HeapWordSize * (jlong)(p->size());
 113     assert(byte_offset < p_size, "Unsafe access: offset " INT64_FORMAT " > object's size " INT64_FORMAT, byte_offset, p_size);
 114   }
 115 #endif
 116 
 117   if (sizeof(char*) == sizeof(jint)) {   // (this constant folds!)
 118     return (address)p + (jint) byte_offset;
 119   } else {
 120     return (address)p +        byte_offset;
 121   }
 122 }
 123 
 124 // Externally callable versions:
 125 // (Use these in compiler intrinsics which emulate unsafe primitives.)
 126 jlong Unsafe_field_offset_to_byte_offset(jlong field_offset) {
 127   return field_offset;
 128 }
 129 jlong Unsafe_field_offset_from_byte_offset(jlong byte_offset) {
 130   return byte_offset;
 131 }
 132 
 133 
 134 ///// Data read/writes on the Java heap and in native (off-heap) memory
 135 
 136 /**
 137  * Helper class for accessing memory.
 138  *
 139  * Normalizes values and wraps accesses in
 140  * JavaThread::doing_unsafe_access() if needed.
 141  */
 142 class MemoryAccess : StackObj {
 143   JavaThread* _thread;
 144   jobject _obj;
 145   jlong _offset;
 146 
 147   // Resolves and returns the address of the memory access
 148   void* addr() {
 149     return index_oop_from_field_offset_long(JNIHandles::resolve(_obj), _offset);
 150   }
 151 
 152   template <typename T>
 153   T normalize_for_write(T x) {
 154     return x;
 155   }
 156 
 157   jboolean normalize_for_write(jboolean x) {
 158     return x & 1;
 159   }
 160 
 161   template <typename T>
 162   T normalize_for_read(T x) {
 163     return x;
 164   }
 165 
 166   jboolean normalize_for_read(jboolean x) {
 167     return x != 0;
 168   }
 169 
 170   /**
 171    * Helper class to wrap memory accesses in JavaThread::doing_unsafe_access()
 172    */
 173   class GuardUnsafeAccess {
 174     JavaThread* _thread;
 175     bool _active;
 176 
 177   public:
 178     GuardUnsafeAccess(JavaThread* thread, jobject _obj) : _thread(thread) {
 179       if (JNIHandles::resolve(_obj) == NULL) {
 180         // native/off-heap access which may raise SIGBUS if accessing
 181         // memory mapped file data in a region of the file which has
 182         // been truncated and is now invalid
 183         _thread->set_doing_unsafe_access(true);
 184         _active = true;
 185       } else {
 186         _active = false;
 187       }
 188     }
 189 
 190     ~GuardUnsafeAccess() {
 191       if (_active) {
 192         _thread->set_doing_unsafe_access(false);
 193       }
 194     }
 195   };
 196 
 197 public:
 198   MemoryAccess(JavaThread* thread, jobject obj, jlong offset)
 199     : _thread(thread), _obj(obj), _offset(offset) {
 200   }
 201 
 202   template <typename T>
 203   T get() {
 204     GuardUnsafeAccess guard(_thread, _obj);
 205 
 206     T* p = (T*)addr();
 207 
 208     T x = normalize_for_read(*p);
 209 
 210     return x;
 211   }
 212 
 213   template <typename T>
 214   void put(T x) {
 215     GuardUnsafeAccess guard(_thread, _obj);
 216 
 217     T* p = (T*)addr();
 218 
 219     *p = normalize_for_write(x);
 220   }
 221 
 222 
 223   template <typename T>
 224   T get_volatile() {
 225     GuardUnsafeAccess guard(_thread, _obj);
 226 
 227     T* p = (T*)addr();
 228 
 229     if (support_IRIW_for_not_multiple_copy_atomic_cpu) {
 230       OrderAccess::fence();
 231     }
 232 
 233     T x = OrderAccess::load_acquire((volatile T*)p);
 234 
 235     return normalize_for_read(x);
 236   }
 237 
 238   template <typename T>
 239   void put_volatile(T x) {
 240     GuardUnsafeAccess guard(_thread, _obj);
 241 
 242     T* p = (T*)addr();
 243 
 244     OrderAccess::release_store_fence((volatile T*)p, normalize_for_write(x));
 245   }
 246 
 247 
 248 #ifndef SUPPORTS_NATIVE_CX8
 249   jlong get_jlong_locked() {
 250     GuardUnsafeAccess guard(_thread, _obj);
 251 
 252     MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
 253 
 254     jlong* p = (jlong*)addr();
 255 
 256     jlong x = Atomic::load(p);
 257 
 258     return x;
 259   }
 260 
 261   void put_jlong_locked(jlong x) {
 262     GuardUnsafeAccess guard(_thread, _obj);
 263 
 264     MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
 265 
 266     jlong* p = (jlong*)addr();
 267 
 268     Atomic::store(normalize_for_write(x),  p);
 269   }
 270 #endif
 271 };
 272 
 273 // Get/PutObject must be special-cased, since it works with handles.
 274 
 275 // These functions allow a null base pointer with an arbitrary address.
 276 // But if the base pointer is non-null, the offset should make some sense.
 277 // That is, it should be in the range [0, MAX_OBJECT_SIZE].
 278 UNSAFE_ENTRY(jobject, Unsafe_GetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
 279   oop p = JNIHandles::resolve(obj);
 280   oop v;
 281 
 282   if (UseCompressedOops) {
 283     narrowOop n = *(narrowOop*)index_oop_from_field_offset_long(p, offset);
 284     v = oopDesc::decode_heap_oop(n);
 285   } else {
 286     v = *(oop*)index_oop_from_field_offset_long(p, offset);
 287   }
 288 
 289   jobject ret = JNIHandles::make_local(env, v);
 290 
 291 #if INCLUDE_ALL_GCS
 292   // We could be accessing the referent field in a reference
 293   // object. If G1 is enabled then we need to register non-null
 294   // referent with the SATB barrier.
 295   if (UseG1GC) {
 296     bool needs_barrier = false;
 297 
 298     if (ret != NULL) {
 299       if (offset == java_lang_ref_Reference::referent_offset && obj != NULL) {
 300         oop o = JNIHandles::resolve(obj);
 301         Klass* k = o->klass();
 302         if (InstanceKlass::cast(k)->reference_type() != REF_NONE) {
 303           assert(InstanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity");
 304           needs_barrier = true;
 305         }
 306       }
 307     }
 308 
 309     if (needs_barrier) {
 310       oop referent = JNIHandles::resolve(ret);
 311       G1SATBCardTableModRefBS::enqueue(referent);
 312     }
 313   }
 314 #endif // INCLUDE_ALL_GCS
 315 
 316   return ret;
 317 } UNSAFE_END
 318 
 319 UNSAFE_ENTRY(void, Unsafe_PutObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
 320   oop x = JNIHandles::resolve(x_h);
 321   oop p = JNIHandles::resolve(obj);
 322 
 323   if (UseCompressedOops) {
 324     oop_store((narrowOop*)index_oop_from_field_offset_long(p, offset), x);
 325   } else {
 326     oop_store((oop*)index_oop_from_field_offset_long(p, offset), x);
 327   }
 328 } UNSAFE_END
 329 
 330 UNSAFE_ENTRY(jobject, Unsafe_GetObjectVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
 331   oop p = JNIHandles::resolve(obj);
 332   void* addr = index_oop_from_field_offset_long(p, offset);
 333 
 334   volatile oop v;
 335 
 336   if (UseCompressedOops) {
 337     volatile narrowOop n = *(volatile narrowOop*) addr;
 338     (void)const_cast<oop&>(v = oopDesc::decode_heap_oop(n));
 339   } else {
 340     (void)const_cast<oop&>(v = *(volatile oop*) addr);
 341   }
 342 
 343   OrderAccess::acquire();
 344   return JNIHandles::make_local(env, v);
 345 } UNSAFE_END
 346 
 347 UNSAFE_ENTRY(void, Unsafe_PutObjectVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
 348   oop x = JNIHandles::resolve(x_h);
 349   oop p = JNIHandles::resolve(obj);
 350   void* addr = index_oop_from_field_offset_long(p, offset);
 351   OrderAccess::release();
 352 
 353   if (UseCompressedOops) {
 354     oop_store((narrowOop*)addr, x);
 355   } else {
 356     oop_store((oop*)addr, x);
 357   }
 358 
 359   OrderAccess::fence();
 360 } UNSAFE_END
 361 
 362 UNSAFE_ENTRY(jobject, Unsafe_GetUncompressedObject(JNIEnv *env, jobject unsafe, jlong addr)) {
 363   oop v = *(oop*) (address) addr;
 364 
 365   return JNIHandles::make_local(env, v);
 366 } UNSAFE_END
 367 
 368 #ifndef SUPPORTS_NATIVE_CX8
 369 
 370 // VM_Version::supports_cx8() is a surrogate for 'supports atomic long memory ops'.
 371 //
 372 // On platforms which do not support atomic compare-and-swap of jlong (8 byte)
 373 // values we have to use a lock-based scheme to enforce atomicity. This has to be
 374 // applied to all Unsafe operations that set the value of a jlong field. Even so
 375 // the compareAndSwapLong operation will not be atomic with respect to direct stores
 376 // to the field from Java code. It is important therefore that any Java code that
 377 // utilizes these Unsafe jlong operations does not perform direct stores. To permit
 378 // direct loads of the field from Java code we must also use Atomic::store within the
 379 // locked regions. And for good measure, in case there are direct stores, we also
 380 // employ Atomic::load within those regions. Note that the field in question must be
 381 // volatile and so must have atomic load/store accesses applied at the Java level.
 382 //
 383 // The locking scheme could utilize a range of strategies for controlling the locking
 384 // granularity: from a lock per-field through to a single global lock. The latter is
 385 // the simplest and is used for the current implementation. Note that the Java object
 386 // that contains the field, can not, in general, be used for locking. To do so can lead
 387 // to deadlocks as we may introduce locking into what appears to the Java code to be a
 388 // lock-free path.
 389 //
 390 // As all the locked-regions are very short and themselves non-blocking we can treat
 391 // them as leaf routines and elide safepoint checks (ie we don't perform any thread
 392 // state transitions even when blocking for the lock). Note that if we do choose to
 393 // add safepoint checks and thread state transitions, we must ensure that we calculate
 394 // the address of the field _after_ we have acquired the lock, else the object may have
 395 // been moved by the GC
 396 
 397 UNSAFE_ENTRY(jlong, Unsafe_GetLongVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
 398   if (VM_Version::supports_cx8()) {
 399     return MemoryAccess(thread, obj, offset).get_volatile<jlong>();
 400   } else {
 401     return MemoryAccess(thread, obj, offset).get_jlong_locked();
 402   }
 403 } UNSAFE_END
 404 
 405 UNSAFE_ENTRY(void, Unsafe_PutLongVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong x)) {
 406   if (VM_Version::supports_cx8()) {
 407     MemoryAccess(thread, obj, offset).put_volatile<jlong>(x);
 408   } else {
 409     MemoryAccess(thread, obj, offset).put_jlong_locked(x);
 410   }
 411 } UNSAFE_END
 412 
 413 #endif // not SUPPORTS_NATIVE_CX8
 414 
 415 UNSAFE_LEAF(jboolean, Unsafe_isBigEndian0(JNIEnv *env, jobject unsafe)) {
 416 #ifdef VM_LITTLE_ENDIAN
 417   return false;
 418 #else
 419   return true;
 420 #endif
 421 } UNSAFE_END
 422 
 423 UNSAFE_LEAF(jint, Unsafe_unalignedAccess0(JNIEnv *env, jobject unsafe)) {
 424   return UseUnalignedAccesses;
 425 } UNSAFE_END
 426 
 427 #define DEFINE_GETSETOOP(java_type, Type) \
 428  \
 429 UNSAFE_ENTRY(java_type, Unsafe_Get##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
 430   return MemoryAccess(thread, obj, offset).get<java_type>(); \
 431 } UNSAFE_END \
 432  \
 433 UNSAFE_ENTRY(void, Unsafe_Put##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
 434   MemoryAccess(thread, obj, offset).put<java_type>(x); \
 435 } UNSAFE_END \
 436  \
 437 // END DEFINE_GETSETOOP.
 438 
 439 DEFINE_GETSETOOP(jboolean, Boolean)
 440 DEFINE_GETSETOOP(jbyte, Byte)
 441 DEFINE_GETSETOOP(jshort, Short);
 442 DEFINE_GETSETOOP(jchar, Char);
 443 DEFINE_GETSETOOP(jint, Int);
 444 DEFINE_GETSETOOP(jlong, Long);
 445 DEFINE_GETSETOOP(jfloat, Float);
 446 DEFINE_GETSETOOP(jdouble, Double);
 447 
 448 #undef DEFINE_GETSETOOP
 449 
 450 #define DEFINE_GETSETOOP_VOLATILE(java_type, Type) \
 451  \
 452 UNSAFE_ENTRY(java_type, Unsafe_Get##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
 453   return MemoryAccess(thread, obj, offset).get_volatile<java_type>(); \
 454 } UNSAFE_END \
 455  \
 456 UNSAFE_ENTRY(void, Unsafe_Put##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
 457   MemoryAccess(thread, obj, offset).put_volatile<java_type>(x); \
 458 } UNSAFE_END \
 459  \
 460 // END DEFINE_GETSETOOP_VOLATILE.
 461 
 462 DEFINE_GETSETOOP_VOLATILE(jboolean, Boolean)
 463 DEFINE_GETSETOOP_VOLATILE(jbyte, Byte)
 464 DEFINE_GETSETOOP_VOLATILE(jshort, Short);
 465 DEFINE_GETSETOOP_VOLATILE(jchar, Char);
 466 DEFINE_GETSETOOP_VOLATILE(jint, Int);
 467 DEFINE_GETSETOOP_VOLATILE(jfloat, Float);
 468 DEFINE_GETSETOOP_VOLATILE(jdouble, Double);
 469 
 470 #ifdef SUPPORTS_NATIVE_CX8
 471 DEFINE_GETSETOOP_VOLATILE(jlong, Long);
 472 #endif
 473 
 474 #undef DEFINE_GETSETOOP_VOLATILE
 475 
 476 UNSAFE_LEAF(void, Unsafe_LoadFence(JNIEnv *env, jobject unsafe)) {
 477   OrderAccess::acquire();
 478 } UNSAFE_END
 479 
 480 UNSAFE_LEAF(void, Unsafe_StoreFence(JNIEnv *env, jobject unsafe)) {
 481   OrderAccess::release();
 482 } UNSAFE_END
 483 
 484 UNSAFE_LEAF(void, Unsafe_FullFence(JNIEnv *env, jobject unsafe)) {
 485   OrderAccess::fence();
 486 } UNSAFE_END
 487 
 488 ////// Allocation requests
 489 
 490 UNSAFE_ENTRY(jobject, Unsafe_AllocateInstance(JNIEnv *env, jobject unsafe, jclass cls)) {
 491   ThreadToNativeFromVM ttnfv(thread);
 492   return env->AllocObject(cls);
 493 } UNSAFE_END
 494 
 495 UNSAFE_ENTRY(jlong, Unsafe_AllocateMemory0(JNIEnv *env, jobject unsafe, jlong size)) {
 496   size_t sz = (size_t)size;
 497 
 498   sz = round_to(sz, HeapWordSize);
 499   void* x = os::malloc(sz, mtInternal);
 500 
 501   return addr_to_java(x);
 502 } UNSAFE_END
 503 
 504 UNSAFE_ENTRY(jlong, Unsafe_ReallocateMemory0(JNIEnv *env, jobject unsafe, jlong addr, jlong size)) {
 505   void* p = addr_from_java(addr);
 506   size_t sz = (size_t)size;
 507   sz = round_to(sz, HeapWordSize);
 508 
 509   void* x = os::realloc(p, sz, mtInternal);
 510 
 511   return addr_to_java(x);
 512 } UNSAFE_END
 513 
 514 UNSAFE_ENTRY(void, Unsafe_FreeMemory0(JNIEnv *env, jobject unsafe, jlong addr)) {
 515   void* p = addr_from_java(addr);
 516 
 517   os::free(p);
 518 } UNSAFE_END
 519 
 520 UNSAFE_ENTRY(void, Unsafe_SetMemory0(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong size, jbyte value)) {
 521   size_t sz = (size_t)size;
 522 
 523   oop base = JNIHandles::resolve(obj);
 524   void* p = index_oop_from_field_offset_long(base, offset);
 525 
 526   Copy::fill_to_memory_atomic(p, sz, value);
 527 } UNSAFE_END
 528 
 529 UNSAFE_ENTRY(void, Unsafe_CopyMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size)) {
 530   size_t sz = (size_t)size;
 531 
 532   oop srcp = JNIHandles::resolve(srcObj);
 533   oop dstp = JNIHandles::resolve(dstObj);
 534 
 535   void* src = index_oop_from_field_offset_long(srcp, srcOffset);
 536   void* dst = index_oop_from_field_offset_long(dstp, dstOffset);
 537 
 538   Copy::conjoint_memory_atomic(src, dst, sz);
 539 } UNSAFE_END
 540 
 541 // This function is a leaf since if the source and destination are both in native memory
 542 // the copy may potentially be very large, and we don't want to disable GC if we can avoid it.
 543 // If either source or destination (or both) are on the heap, the function will enter VM using
 544 // JVM_ENTRY_FROM_LEAF
 545 UNSAFE_LEAF(void, Unsafe_CopySwapMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size, jlong elemSize)) {
 546   size_t sz = (size_t)size;
 547   size_t esz = (size_t)elemSize;
 548 
 549   if (srcObj == NULL && dstObj == NULL) {
 550     // Both src & dst are in native memory
 551     address src = (address)srcOffset;
 552     address dst = (address)dstOffset;
 553 
 554     Copy::conjoint_swap(src, dst, sz, esz);
 555   } else {
 556     // At least one of src/dst are on heap, transition to VM to access raw pointers
 557 
 558     JVM_ENTRY_FROM_LEAF(env, void, Unsafe_CopySwapMemory0) {
 559       oop srcp = JNIHandles::resolve(srcObj);
 560       oop dstp = JNIHandles::resolve(dstObj);
 561 
 562       address src = (address)index_oop_from_field_offset_long(srcp, srcOffset);
 563       address dst = (address)index_oop_from_field_offset_long(dstp, dstOffset);
 564 
 565       Copy::conjoint_swap(src, dst, sz, esz);
 566     } JVM_END
 567   }
 568 } UNSAFE_END
 569 
 570 ////// Random queries
 571 
 572 UNSAFE_LEAF(jint, Unsafe_AddressSize0(JNIEnv *env, jobject unsafe)) {
 573   return sizeof(void*);
 574 } UNSAFE_END
 575 
 576 UNSAFE_LEAF(jint, Unsafe_PageSize()) {
 577   return os::vm_page_size();
 578 } UNSAFE_END
 579 
 580 static jint find_field_offset(jobject field, int must_be_static, TRAPS) {
 581   assert(field != NULL, "field must not be NULL");
 582 
 583   oop reflected   = JNIHandles::resolve_non_null(field);
 584   oop mirror      = java_lang_reflect_Field::clazz(reflected);
 585   Klass* k        = java_lang_Class::as_Klass(mirror);
 586   int slot        = java_lang_reflect_Field::slot(reflected);
 587   int modifiers   = java_lang_reflect_Field::modifiers(reflected);
 588 
 589   if (must_be_static >= 0) {
 590     int really_is_static = ((modifiers & JVM_ACC_STATIC) != 0);
 591     if (must_be_static != really_is_static) {
 592       THROW_0(vmSymbols::java_lang_IllegalArgumentException());
 593     }
 594   }
 595 
 596   int offset = InstanceKlass::cast(k)->field_offset(slot);
 597   return field_offset_from_byte_offset(offset);
 598 }
 599 
 600 UNSAFE_ENTRY(jlong, Unsafe_ObjectFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
 601   return find_field_offset(field, 0, THREAD);
 602 } UNSAFE_END
 603 
 604 UNSAFE_ENTRY(jlong, Unsafe_StaticFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
 605   return find_field_offset(field, 1, THREAD);
 606 } UNSAFE_END
 607 
 608 UNSAFE_ENTRY(jobject, Unsafe_StaticFieldBase0(JNIEnv *env, jobject unsafe, jobject field)) {
 609   assert(field != NULL, "field must not be NULL");
 610 
 611   // Note:  In this VM implementation, a field address is always a short
 612   // offset from the base of a a klass metaobject.  Thus, the full dynamic
 613   // range of the return type is never used.  However, some implementations
 614   // might put the static field inside an array shared by many classes,
 615   // or even at a fixed address, in which case the address could be quite
 616   // large.  In that last case, this function would return NULL, since
 617   // the address would operate alone, without any base pointer.
 618 
 619   oop reflected   = JNIHandles::resolve_non_null(field);
 620   oop mirror      = java_lang_reflect_Field::clazz(reflected);
 621   int modifiers   = java_lang_reflect_Field::modifiers(reflected);
 622 
 623   if ((modifiers & JVM_ACC_STATIC) == 0) {
 624     THROW_0(vmSymbols::java_lang_IllegalArgumentException());
 625   }
 626 
 627   return JNIHandles::make_local(env, mirror);
 628 } UNSAFE_END
 629 
 630 UNSAFE_ENTRY(void, Unsafe_EnsureClassInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
 631   assert(clazz != NULL, "clazz must not be NULL");
 632 
 633   oop mirror = JNIHandles::resolve_non_null(clazz);
 634 
 635   Klass* klass = java_lang_Class::as_Klass(mirror);
 636   if (klass != NULL && klass->should_be_initialized()) {
 637     InstanceKlass* k = InstanceKlass::cast(klass);
 638     k->initialize(CHECK);
 639   }
 640 }
 641 UNSAFE_END
 642 
 643 UNSAFE_ENTRY(jboolean, Unsafe_ShouldBeInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
 644   assert(clazz != NULL, "clazz must not be NULL");
 645 
 646   oop mirror = JNIHandles::resolve_non_null(clazz);
 647   Klass* klass = java_lang_Class::as_Klass(mirror);
 648 
 649   if (klass != NULL && klass->should_be_initialized()) {
 650     return true;
 651   }
 652 
 653   return false;
 654 }
 655 UNSAFE_END
 656 
 657 static void getBaseAndScale(int& base, int& scale, jclass clazz, TRAPS) {
 658   assert(clazz != NULL, "clazz must not be NULL");
 659 
 660   oop mirror = JNIHandles::resolve_non_null(clazz);
 661   Klass* k = java_lang_Class::as_Klass(mirror);
 662 
 663   if (k == NULL || !k->is_array_klass()) {
 664     THROW(vmSymbols::java_lang_InvalidClassException());
 665   } else if (k->is_objArray_klass()) {
 666     base  = arrayOopDesc::base_offset_in_bytes(T_OBJECT);
 667     scale = heapOopSize;
 668   } else if (k->is_typeArray_klass()) {
 669     TypeArrayKlass* tak = TypeArrayKlass::cast(k);
 670     base  = tak->array_header_in_bytes();
 671     assert(base == arrayOopDesc::base_offset_in_bytes(tak->element_type()), "array_header_size semantics ok");
 672     scale = (1 << tak->log2_element_size());
 673   } else {
 674     ShouldNotReachHere();
 675   }
 676 }
 677 
 678 UNSAFE_ENTRY(jint, Unsafe_ArrayBaseOffset0(JNIEnv *env, jobject unsafe, jclass clazz)) {
 679   int base = 0, scale = 0;
 680   getBaseAndScale(base, scale, clazz, CHECK_0);
 681 
 682   return field_offset_from_byte_offset(base);
 683 } UNSAFE_END
 684 
 685 
 686 UNSAFE_ENTRY(jint, Unsafe_ArrayIndexScale0(JNIEnv *env, jobject unsafe, jclass clazz)) {
 687   int base = 0, scale = 0;
 688   getBaseAndScale(base, scale, clazz, CHECK_0);
 689 
 690   // This VM packs both fields and array elements down to the byte.
 691   // But watch out:  If this changes, so that array references for
 692   // a given primitive type (say, T_BOOLEAN) use different memory units
 693   // than fields, this method MUST return zero for such arrays.
 694   // For example, the VM used to store sub-word sized fields in full
 695   // words in the object layout, so that accessors like getByte(Object,int)
 696   // did not really do what one might expect for arrays.  Therefore,
 697   // this function used to report a zero scale factor, so that the user
 698   // would know not to attempt to access sub-word array elements.
 699   // // Code for unpacked fields:
 700   // if (scale < wordSize)  return 0;
 701 
 702   // The following allows for a pretty general fieldOffset cookie scheme,
 703   // but requires it to be linear in byte offset.
 704   return field_offset_from_byte_offset(scale) - field_offset_from_byte_offset(0);
 705 } UNSAFE_END
 706 
 707 
 708 static inline void throw_new(JNIEnv *env, const char *ename) {
 709   char buf[100];
 710 
 711   jio_snprintf(buf, 100, "%s%s", "java/lang/", ename);
 712 
 713   jclass cls = env->FindClass(buf);
 714   if (env->ExceptionCheck()) {
 715     env->ExceptionClear();
 716     tty->print_cr("Unsafe: cannot throw %s because FindClass has failed", buf);
 717     return;
 718   }
 719 
 720   env->ThrowNew(cls, NULL);
 721 }
 722 
 723 static jclass Unsafe_DefineClass_impl(JNIEnv *env, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd) {
 724   // Code lifted from JDK 1.3 ClassLoader.c
 725 
 726   jbyte *body;
 727   char *utfName = NULL;
 728   jclass result = 0;
 729   char buf[128];
 730 
 731   assert(data != NULL, "Class bytes must not be NULL");
 732   assert(length >= 0, "length must not be negative: %d", length);
 733 
 734   if (UsePerfData) {
 735     ClassLoader::unsafe_defineClassCallCounter()->inc();
 736   }
 737 
 738   body = NEW_C_HEAP_ARRAY(jbyte, length, mtInternal);
 739   if (body == NULL) {
 740     throw_new(env, "OutOfMemoryError");
 741     return 0;
 742   }
 743 
 744   env->GetByteArrayRegion(data, offset, length, body);
 745   if (env->ExceptionOccurred()) {
 746     goto free_body;
 747   }
 748 
 749   if (name != NULL) {
 750     uint len = env->GetStringUTFLength(name);
 751     int unicode_len = env->GetStringLength(name);
 752 
 753     if (len >= sizeof(buf)) {
 754       utfName = NEW_C_HEAP_ARRAY(char, len + 1, mtInternal);
 755       if (utfName == NULL) {
 756         throw_new(env, "OutOfMemoryError");
 757         goto free_body;
 758       }
 759     } else {
 760       utfName = buf;
 761     }
 762 
 763     env->GetStringUTFRegion(name, 0, unicode_len, utfName);
 764 
 765     for (uint i = 0; i < len; i++) {
 766       if (utfName[i] == '.')   utfName[i] = '/';
 767     }
 768   }
 769 
 770   result = JVM_DefineClass(env, utfName, loader, body, length, pd);
 771 
 772   if (utfName && utfName != buf) {
 773     FREE_C_HEAP_ARRAY(char, utfName);
 774   }
 775 
 776  free_body:
 777   FREE_C_HEAP_ARRAY(jbyte, body);
 778   return result;
 779 }
 780 
 781 
 782 UNSAFE_ENTRY(jclass, Unsafe_DefineClass0(JNIEnv *env, jobject unsafe, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd)) {
 783   ThreadToNativeFromVM ttnfv(thread);
 784 
 785   return Unsafe_DefineClass_impl(env, name, data, offset, length, loader, pd);
 786 } UNSAFE_END
 787 
 788 
 789 // define a class but do not make it known to the class loader or system dictionary
 790 // - host_class:  supplies context for linkage, access control, protection domain, and class loader
 791 // - data:  bytes of a class file, a raw memory address (length gives the number of bytes)
 792 // - cp_patches:  where non-null entries exist, they replace corresponding CP entries in data
 793 
 794 // When you load an anonymous class U, it works as if you changed its name just before loading,
 795 // to a name that you will never use again.  Since the name is lost, no other class can directly
 796 // link to any member of U.  Just after U is loaded, the only way to use it is reflectively,
 797 // through java.lang.Class methods like Class.newInstance.
 798 
 799 // Access checks for linkage sites within U continue to follow the same rules as for named classes.
 800 // The package of an anonymous class is given by the package qualifier on the name under which it was loaded.
 801 // An anonymous class also has special privileges to access any member of its host class.
 802 // This is the main reason why this loading operation is unsafe.  The purpose of this is to
 803 // allow language implementations to simulate "open classes"; a host class in effect gets
 804 // new code when an anonymous class is loaded alongside it.  A less convenient but more
 805 // standard way to do this is with reflection, which can also be set to ignore access
 806 // restrictions.
 807 
 808 // Access into an anonymous class is possible only through reflection.  Therefore, there
 809 // are no special access rules for calling into an anonymous class.  The relaxed access
 810 // rule for the host class is applied in the opposite direction:  A host class reflectively
 811 // access one of its anonymous classes.
 812 
 813 // If you load the same bytecodes twice, you get two different classes.  You can reload
 814 // the same bytecodes with or without varying CP patches.
 815 
 816 // By using the CP patching array, you can have a new anonymous class U2 refer to an older one U1.
 817 // The bytecodes for U2 should refer to U1 by a symbolic name (doesn't matter what the name is).
 818 // The CONSTANT_Class entry for that name can be patched to refer directly to U1.
 819 
 820 // This allows, for example, U2 to use U1 as a superclass or super-interface, or as
 821 // an outer class (so that U2 is an anonymous inner class of anonymous U1).
 822 // It is not possible for a named class, or an older anonymous class, to refer by
 823 // name (via its CP) to a newer anonymous class.
 824 
 825 // CP patching may also be used to modify (i.e., hack) the names of methods, classes,
 826 // or type descriptors used in the loaded anonymous class.
 827 
 828 // Finally, CP patching may be used to introduce "live" objects into the constant pool,
 829 // instead of "dead" strings.  A compiled statement like println((Object)"hello") can
 830 // be changed to println(greeting), where greeting is an arbitrary object created before
 831 // the anonymous class is loaded.  This is useful in dynamic languages, in which
 832 // various kinds of metaobjects must be introduced as constants into bytecode.
 833 // Note the cast (Object), which tells the verifier to expect an arbitrary object,
 834 // not just a literal string.  For such ldc instructions, the verifier uses the
 835 // type Object instead of String, if the loaded constant is not in fact a String.
 836 
 837 static instanceKlassHandle
 838 Unsafe_DefineAnonymousClass_impl(JNIEnv *env,
 839                                  jclass host_class, jbyteArray data, jobjectArray cp_patches_jh,
 840                                  u1** temp_alloc,
 841                                  TRAPS) {
 842   assert(host_class != NULL, "host_class must not be NULL");
 843   assert(data != NULL, "data must not be NULL");
 844 
 845   if (UsePerfData) {
 846     ClassLoader::unsafe_defineClassCallCounter()->inc();
 847   }
 848 
 849   jint length = typeArrayOop(JNIHandles::resolve_non_null(data))->length();
 850   assert(length >= 0, "class_bytes_length must not be negative: %d", length);
 851 
 852   int class_bytes_length = (int) length;
 853 
 854   u1* class_bytes = NEW_C_HEAP_ARRAY(u1, length, mtInternal);
 855   if (class_bytes == NULL) {
 856     THROW_0(vmSymbols::java_lang_OutOfMemoryError());
 857   }
 858 
 859   // caller responsible to free it:
 860   *temp_alloc = class_bytes;
 861 
 862   jbyte* array_base = typeArrayOop(JNIHandles::resolve_non_null(data))->byte_at_addr(0);
 863   Copy::conjoint_jbytes(array_base, class_bytes, length);
 864 
 865   objArrayHandle cp_patches_h;
 866   if (cp_patches_jh != NULL) {
 867     oop p = JNIHandles::resolve_non_null(cp_patches_jh);
 868     assert(p->is_objArray(), "cp_patches must be an object[]");
 869     cp_patches_h = objArrayHandle(THREAD, (objArrayOop)p);
 870   }
 871 
 872   const Klass* host_klass = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(host_class));
 873 
 874   // Make sure it's the real host class, not another anonymous class.
 875   while (host_klass != NULL && host_klass->is_instance_klass() &&
 876          InstanceKlass::cast(host_klass)->is_anonymous()) {
 877     host_klass = InstanceKlass::cast(host_klass)->host_klass();
 878   }
 879 
 880   // Primitive types have NULL Klass* fields in their java.lang.Class instances.
 881   if (host_klass == NULL) {
 882     THROW_0(vmSymbols::java_lang_IllegalArgumentException());
 883   }
 884 
 885   const char* host_source = host_klass->external_name();
 886   Handle      host_loader(THREAD, host_klass->class_loader());
 887   Handle      host_domain(THREAD, host_klass->protection_domain());
 888 
 889   GrowableArray<Handle>* cp_patches = NULL;
 890 
 891   if (cp_patches_h.not_null()) {
 892     int alen = cp_patches_h->length();
 893 
 894     for (int i = alen-1; i >= 0; i--) {
 895       oop p = cp_patches_h->obj_at(i);
 896       if (p != NULL) {
 897         Handle patch(THREAD, p);
 898 
 899         if (cp_patches == NULL) {
 900           cp_patches = new GrowableArray<Handle>(i+1, i+1, Handle());
 901         }
 902 
 903         cp_patches->at_put(i, patch);
 904       }
 905     }
 906   }
 907 
 908   ClassFileStream st(class_bytes, class_bytes_length, host_source, ClassFileStream::verify);
 909 
 910   Symbol* no_class_name = NULL;
 911   Klass* anonk = SystemDictionary::parse_stream(no_class_name,
 912                                                 host_loader,
 913                                                 host_domain,
 914                                                 &st,
 915                                                 host_klass,
 916                                                 cp_patches,
 917                                                 CHECK_NULL);
 918   if (anonk == NULL) {
 919     return NULL;
 920   }
 921 
 922   return instanceKlassHandle(THREAD, anonk);
 923 }
 924 
 925 UNSAFE_ENTRY(jclass, Unsafe_DefineAnonymousClass0(JNIEnv *env, jobject unsafe, jclass host_class, jbyteArray data, jobjectArray cp_patches_jh)) {
 926   ResourceMark rm(THREAD);
 927 
 928   instanceKlassHandle anon_klass;
 929   jobject res_jh = NULL;
 930   u1* temp_alloc = NULL;
 931 
 932   anon_klass = Unsafe_DefineAnonymousClass_impl(env, host_class, data, cp_patches_jh, &temp_alloc, THREAD);
 933   if (anon_klass() != NULL) {
 934     res_jh = JNIHandles::make_local(env, anon_klass->java_mirror());
 935   }
 936 
 937   // try/finally clause:
 938   if (temp_alloc != NULL) {
 939     FREE_C_HEAP_ARRAY(u1, temp_alloc);
 940   }
 941 
 942   // The anonymous class loader data has been artificially been kept alive to
 943   // this point.   The mirror and any instances of this class have to keep
 944   // it alive afterwards.
 945   if (anon_klass() != NULL) {
 946     anon_klass->class_loader_data()->dec_keep_alive();
 947   }
 948 
 949   // let caller initialize it as needed...
 950 
 951   return (jclass) res_jh;
 952 } UNSAFE_END
 953 
 954 
 955 
 956 UNSAFE_ENTRY(void, Unsafe_ThrowException(JNIEnv *env, jobject unsafe, jthrowable thr)) {
 957   ThreadToNativeFromVM ttnfv(thread);
 958   env->Throw(thr);
 959 } UNSAFE_END
 960 
 961 // JSR166 ------------------------------------------------------------------
 962 
 963 UNSAFE_ENTRY(jobject, Unsafe_CompareAndExchangeObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
 964   oop x = JNIHandles::resolve(x_h);
 965   oop e = JNIHandles::resolve(e_h);
 966   oop p = JNIHandles::resolve(obj);
 967   HeapWord* addr = (HeapWord *)index_oop_from_field_offset_long(p, offset);
 968   oop res = oopDesc::atomic_compare_exchange_oop(x, addr, e, true);
 969   if (res == e) {
 970     update_barrier_set((void*)addr, x);
 971   }
 972   return JNIHandles::make_local(env, res);
 973 } UNSAFE_END
 974 
 975 UNSAFE_ENTRY(jint, Unsafe_CompareAndExchangeInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
 976   oop p = JNIHandles::resolve(obj);
 977   jint* addr = (jint *) index_oop_from_field_offset_long(p, offset);
 978 
 979   return (jint)(Atomic::cmpxchg(x, addr, e));
 980 } UNSAFE_END
 981 
 982 UNSAFE_ENTRY(jlong, Unsafe_CompareAndExchangeLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
 983   Handle p(THREAD, JNIHandles::resolve(obj));
 984   jlong* addr = (jlong*)index_oop_from_field_offset_long(p(), offset);
 985 
 986 #ifdef SUPPORTS_NATIVE_CX8
 987   return (jlong)(Atomic::cmpxchg(x, addr, e));
 988 #else
 989   if (VM_Version::supports_cx8()) {
 990     return (jlong)(Atomic::cmpxchg(x, addr, e));
 991   } else {
 992     MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
 993 
 994     jlong val = Atomic::load(addr);
 995     if (val == e) {
 996       Atomic::store(x, addr);
 997     }
 998     return val;
 999   }
1000 #endif
1001 } UNSAFE_END
1002 
1003 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSwapObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
1004   oop x = JNIHandles::resolve(x_h);
1005   oop e = JNIHandles::resolve(e_h);
1006   oop p = JNIHandles::resolve(obj);
1007   HeapWord* addr = (HeapWord *)index_oop_from_field_offset_long(p, offset);
1008   oop res = oopDesc::atomic_compare_exchange_oop(x, addr, e, true);
1009   if (res != e) {
1010     return false;
1011   }
1012 
1013   update_barrier_set((void*)addr, x);
1014 
1015   return true;
1016 } UNSAFE_END
1017 
1018 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSwapInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
1019   oop p = JNIHandles::resolve(obj);
1020   jint* addr = (jint *)index_oop_from_field_offset_long(p, offset);
1021 
1022   return (jint)(Atomic::cmpxchg(x, addr, e)) == e;
1023 } UNSAFE_END
1024 
1025 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSwapLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
1026   Handle p(THREAD, JNIHandles::resolve(obj));
1027   jlong* addr = (jlong*)index_oop_from_field_offset_long(p(), offset);
1028 
1029 #ifdef SUPPORTS_NATIVE_CX8
1030   return (jlong)(Atomic::cmpxchg(x, addr, e)) == e;
1031 #else
1032   if (VM_Version::supports_cx8()) {
1033     return (jlong)(Atomic::cmpxchg(x, addr, e)) == e;
1034   } else {
1035     MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
1036 
1037     jlong val = Atomic::load(addr);
1038     if (val != e) {
1039       return false;
1040     }
1041 
1042     Atomic::store(x, addr);
1043     return true;
1044   }
1045 #endif
1046 } UNSAFE_END
1047 
1048 UNSAFE_ENTRY(void, Unsafe_Park(JNIEnv *env, jobject unsafe, jboolean isAbsolute, jlong time)) {
1049   EventThreadPark event;
1050   HOTSPOT_THREAD_PARK_BEGIN((uintptr_t) thread->parker(), (int) isAbsolute, time);
1051 
1052   JavaThreadParkedState jtps(thread, time != 0);
1053   thread->parker()->park(isAbsolute != 0, time);
1054 
1055   HOTSPOT_THREAD_PARK_END((uintptr_t) thread->parker());
1056 
1057   if (event.should_commit()) {
1058     oop obj = thread->current_park_blocker();
1059     event.set_klass((obj != NULL) ? obj->klass() : NULL);
1060     event.set_timeout(time);
1061     event.set_address((obj != NULL) ? (TYPE_ADDRESS) cast_from_oop<uintptr_t>(obj) : 0);
1062     event.commit();
1063   }
1064 } UNSAFE_END
1065 
1066 UNSAFE_ENTRY(void, Unsafe_Unpark(JNIEnv *env, jobject unsafe, jobject jthread)) {
1067   Parker* p = NULL;
1068 
1069   if (jthread != NULL) {
1070     oop java_thread = JNIHandles::resolve_non_null(jthread);
1071     if (java_thread != NULL) {
1072       jlong lp = java_lang_Thread::park_event(java_thread);
1073       if (lp != 0) {
1074         // This cast is OK even though the jlong might have been read
1075         // non-atomically on 32bit systems, since there, one word will
1076         // always be zero anyway and the value set is always the same
1077         p = (Parker*)addr_from_java(lp);
1078       } else {
1079         // Grab lock if apparently null or using older version of library
1080         MutexLocker mu(Threads_lock);
1081         java_thread = JNIHandles::resolve_non_null(jthread);
1082 
1083         if (java_thread != NULL) {
1084           JavaThread* thr = java_lang_Thread::thread(java_thread);
1085           if (thr != NULL) {
1086             p = thr->parker();
1087             if (p != NULL) { // Bind to Java thread for next time.
1088               java_lang_Thread::set_park_event(java_thread, addr_to_java(p));
1089             }
1090           }
1091         }
1092       }
1093     }
1094   }
1095 
1096   if (p != NULL) {
1097     HOTSPOT_THREAD_UNPARK((uintptr_t) p);
1098     p->unpark();
1099   }
1100 } UNSAFE_END
1101 
1102 UNSAFE_ENTRY(jint, Unsafe_GetLoadAverage0(JNIEnv *env, jobject unsafe, jdoubleArray loadavg, jint nelem)) {
1103   const int max_nelem = 3;
1104   double la[max_nelem];
1105   jint ret;
1106 
1107   typeArrayOop a = typeArrayOop(JNIHandles::resolve_non_null(loadavg));
1108   assert(a->is_typeArray(), "must be type array");
1109 
1110   ret = os::loadavg(la, nelem);
1111   if (ret == -1) {
1112     return -1;
1113   }
1114 
1115   // if successful, ret is the number of samples actually retrieved.
1116   assert(ret >= 0 && ret <= max_nelem, "Unexpected loadavg return value");
1117   switch(ret) {
1118     case 3: a->double_at_put(2, (jdouble)la[2]); // fall through
1119     case 2: a->double_at_put(1, (jdouble)la[1]); // fall through
1120     case 1: a->double_at_put(0, (jdouble)la[0]); break;
1121   }
1122 
1123   return ret;
1124 } UNSAFE_END
1125 
1126 
1127 /// JVM_RegisterUnsafeMethods
1128 
1129 #define ADR "J"
1130 
1131 #define LANG "Ljava/lang/"
1132 
1133 #define OBJ LANG "Object;"
1134 #define CLS LANG "Class;"
1135 #define FLD LANG "reflect/Field;"
1136 #define THR LANG "Throwable;"
1137 
1138 #define DC_Args  LANG "String;[BII" LANG "ClassLoader;" "Ljava/security/ProtectionDomain;"
1139 #define DAC_Args CLS "[B[" OBJ
1140 
1141 #define CC (char*)  /*cast a literal from (const char*)*/
1142 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
1143 
1144 #define DECLARE_GETPUTOOP(Type, Desc) \
1145     {CC "get" #Type,      CC "(" OBJ "J)" #Desc,       FN_PTR(Unsafe_Get##Type)}, \
1146     {CC "put" #Type,      CC "(" OBJ "J" #Desc ")V",   FN_PTR(Unsafe_Put##Type)}, \
1147     {CC "get" #Type "Volatile",      CC "(" OBJ "J)" #Desc,       FN_PTR(Unsafe_Get##Type##Volatile)}, \
1148     {CC "put" #Type "Volatile",      CC "(" OBJ "J" #Desc ")V",   FN_PTR(Unsafe_Put##Type##Volatile)}
1149 
1150 
1151 static JNINativeMethod jdk_internal_misc_Unsafe_methods[] = {
1152     {CC "getObject",        CC "(" OBJ "J)" OBJ "",   FN_PTR(Unsafe_GetObject)},
1153     {CC "putObject",        CC "(" OBJ "J" OBJ ")V",  FN_PTR(Unsafe_PutObject)},
1154     {CC "getObjectVolatile",CC "(" OBJ "J)" OBJ "",   FN_PTR(Unsafe_GetObjectVolatile)},
1155     {CC "putObjectVolatile",CC "(" OBJ "J" OBJ ")V",  FN_PTR(Unsafe_PutObjectVolatile)},
1156 
1157     {CC "getUncompressedObject", CC "(" ADR ")" OBJ,  FN_PTR(Unsafe_GetUncompressedObject)},
1158 
1159     DECLARE_GETPUTOOP(Boolean, Z),
1160     DECLARE_GETPUTOOP(Byte, B),
1161     DECLARE_GETPUTOOP(Short, S),
1162     DECLARE_GETPUTOOP(Char, C),
1163     DECLARE_GETPUTOOP(Int, I),
1164     DECLARE_GETPUTOOP(Long, J),
1165     DECLARE_GETPUTOOP(Float, F),
1166     DECLARE_GETPUTOOP(Double, D),
1167 
1168     {CC "allocateMemory0",    CC "(J)" ADR,              FN_PTR(Unsafe_AllocateMemory0)},
1169     {CC "reallocateMemory0",  CC "(" ADR "J)" ADR,       FN_PTR(Unsafe_ReallocateMemory0)},
1170     {CC "freeMemory0",        CC "(" ADR ")V",           FN_PTR(Unsafe_FreeMemory0)},
1171 
1172     {CC "objectFieldOffset0", CC "(" FLD ")J",           FN_PTR(Unsafe_ObjectFieldOffset0)},
1173     {CC "staticFieldOffset0", CC "(" FLD ")J",           FN_PTR(Unsafe_StaticFieldOffset0)},
1174     {CC "staticFieldBase0",   CC "(" FLD ")" OBJ,        FN_PTR(Unsafe_StaticFieldBase0)},
1175     {CC "ensureClassInitialized0", CC "(" CLS ")V",      FN_PTR(Unsafe_EnsureClassInitialized0)},
1176     {CC "arrayBaseOffset0",   CC "(" CLS ")I",           FN_PTR(Unsafe_ArrayBaseOffset0)},
1177     {CC "arrayIndexScale0",   CC "(" CLS ")I",           FN_PTR(Unsafe_ArrayIndexScale0)},
1178     {CC "addressSize0",       CC "()I",                  FN_PTR(Unsafe_AddressSize0)},
1179     {CC "pageSize",           CC "()I",                  FN_PTR(Unsafe_PageSize)},
1180 
1181     {CC "defineClass0",       CC "(" DC_Args ")" CLS,    FN_PTR(Unsafe_DefineClass0)},
1182     {CC "allocateInstance",   CC "(" CLS ")" OBJ,        FN_PTR(Unsafe_AllocateInstance)},
1183     {CC "throwException",     CC "(" THR ")V",           FN_PTR(Unsafe_ThrowException)},
1184     {CC "compareAndSwapObject", CC "(" OBJ "J" OBJ "" OBJ ")Z", FN_PTR(Unsafe_CompareAndSwapObject)},
1185     {CC "compareAndSwapInt",  CC "(" OBJ "J""I""I"")Z",  FN_PTR(Unsafe_CompareAndSwapInt)},
1186     {CC "compareAndSwapLong", CC "(" OBJ "J""J""J"")Z",  FN_PTR(Unsafe_CompareAndSwapLong)},
1187     {CC "compareAndExchangeObjectVolatile", CC "(" OBJ "J" OBJ "" OBJ ")" OBJ, FN_PTR(Unsafe_CompareAndExchangeObject)},
1188     {CC "compareAndExchangeIntVolatile",  CC "(" OBJ "J""I""I"")I", FN_PTR(Unsafe_CompareAndExchangeInt)},
1189     {CC "compareAndExchangeLongVolatile", CC "(" OBJ "J""J""J"")J", FN_PTR(Unsafe_CompareAndExchangeLong)},
1190 
1191     {CC "park",               CC "(ZJ)V",                FN_PTR(Unsafe_Park)},
1192     {CC "unpark",             CC "(" OBJ ")V",           FN_PTR(Unsafe_Unpark)},
1193 
1194     {CC "getLoadAverage0",    CC "([DI)I",               FN_PTR(Unsafe_GetLoadAverage0)},
1195 
1196     {CC "copyMemory0",        CC "(" OBJ "J" OBJ "JJ)V", FN_PTR(Unsafe_CopyMemory0)},
1197     {CC "copySwapMemory0",    CC "(" OBJ "J" OBJ "JJJ)V", FN_PTR(Unsafe_CopySwapMemory0)},
1198     {CC "setMemory0",         CC "(" OBJ "JJB)V",        FN_PTR(Unsafe_SetMemory0)},
1199 
1200     {CC "defineAnonymousClass0", CC "(" DAC_Args ")" CLS, FN_PTR(Unsafe_DefineAnonymousClass0)},
1201 
1202     {CC "shouldBeInitialized0", CC "(" CLS ")Z",         FN_PTR(Unsafe_ShouldBeInitialized0)},
1203 
1204     {CC "loadFence",          CC "()V",                  FN_PTR(Unsafe_LoadFence)},
1205     {CC "storeFence",         CC "()V",                  FN_PTR(Unsafe_StoreFence)},
1206     {CC "fullFence",          CC "()V",                  FN_PTR(Unsafe_FullFence)},
1207 
1208     {CC "isBigEndian0",       CC "()Z",                  FN_PTR(Unsafe_isBigEndian0)},
1209     {CC "unalignedAccess0",   CC "()Z",                  FN_PTR(Unsafe_unalignedAccess0)}
1210 };
1211 
1212 #undef CC
1213 #undef FN_PTR
1214 
1215 #undef ADR
1216 #undef LANG
1217 #undef OBJ
1218 #undef CLS
1219 #undef FLD
1220 #undef THR
1221 #undef DC_Args
1222 #undef DAC_Args
1223 
1224 #undef DECLARE_GETPUTOOP
1225 
1226 
1227 // This function is exported, used by NativeLookup.
1228 // The Unsafe_xxx functions above are called only from the interpreter.
1229 // The optimizer looks at names and signatures to recognize
1230 // individual functions.
1231 
1232 JVM_ENTRY(void, JVM_RegisterJDKInternalMiscUnsafeMethods(JNIEnv *env, jclass unsafeclass)) {
1233   ThreadToNativeFromVM ttnfv(thread);
1234 
1235   int ok = env->RegisterNatives(unsafeclass, jdk_internal_misc_Unsafe_methods, sizeof(jdk_internal_misc_Unsafe_methods)/sizeof(JNINativeMethod));
1236   guarantee(ok == 0, "register jdk.internal.misc.Unsafe natives");
1237 } JVM_END