1 /*
   2  * Copyright (c) 2000, 2018, 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 "jni.h"
  27 #include "jvm.h"
  28 #include "classfile/classFileStream.hpp"
  29 #include "classfile/vmSymbols.hpp"
  30 #include "jfr/jfrEvents.hpp"
  31 #include "memory/allocation.inline.hpp"
  32 #include "memory/resourceArea.hpp"
  33 #include "logging/log.hpp"
  34 #include "logging/logStream.hpp"
  35 #include "oops/access.inline.hpp"
  36 #include "oops/fieldStreams.hpp"
  37 #include "oops/objArrayOop.inline.hpp"
  38 #include "oops/oop.inline.hpp"
  39 #include "oops/typeArrayOop.inline.hpp"
  40 #include "oops/valueArrayKlass.hpp"
  41 #include "oops/valueArrayOop.hpp"
  42 #include "oops/valueArrayOop.inline.hpp"
  43 #include "prims/unsafe.hpp"
  44 #include "runtime/atomic.hpp"
  45 #include "runtime/fieldDescriptor.inline.hpp"
  46 #include "runtime/globals.hpp"
  47 #include "runtime/interfaceSupport.inline.hpp"
  48 #include "runtime/jniHandles.inline.hpp"
  49 #include "runtime/orderAccess.hpp"
  50 #include "runtime/reflection.hpp"
  51 #include "runtime/thread.hpp"
  52 #include "runtime/threadSMR.hpp"
  53 #include "runtime/vm_version.hpp"
  54 #include "services/threadService.hpp"
  55 #include "utilities/align.hpp"
  56 #include "utilities/copy.hpp"
  57 #include "utilities/dtrace.hpp"
  58 #include "utilities/macros.hpp"
  59 
  60 /**
  61  * Implementation of the jdk.internal.misc.Unsafe class
  62  */
  63 
  64 
  65 #define MAX_OBJECT_SIZE \
  66   ( arrayOopDesc::header_size(T_DOUBLE) * HeapWordSize \
  67     + ((julong)max_jint * sizeof(double)) )
  68 
  69 
  70 #define UNSAFE_ENTRY(result_type, header) \
  71   JVM_ENTRY(static result_type, header)
  72 
  73 #define UNSAFE_LEAF(result_type, header) \
  74   JVM_LEAF(static result_type, header)
  75 
  76 #define UNSAFE_END JVM_END
  77 
  78 
  79 static inline void* addr_from_java(jlong addr) {
  80   // This assert fails in a variety of ways on 32-bit systems.
  81   // It is impossible to predict whether native code that converts
  82   // pointers to longs will sign-extend or zero-extend the addresses.
  83   //assert(addr == (uintptr_t)addr, "must not be odd high bits");
  84   return (void*)(uintptr_t)addr;
  85 }
  86 
  87 static inline jlong addr_to_java(void* p) {
  88   assert(p == (void*)(uintptr_t)p, "must not be odd high bits");
  89   return (uintptr_t)p;
  90 }
  91 
  92 
  93 // Note: The VM's obj_field and related accessors use byte-scaled
  94 // ("unscaled") offsets, just as the unsafe methods do.
  95 
  96 // However, the method Unsafe.fieldOffset explicitly declines to
  97 // guarantee this.  The field offset values manipulated by the Java user
  98 // through the Unsafe API are opaque cookies that just happen to be byte
  99 // offsets.  We represent this state of affairs by passing the cookies
 100 // through conversion functions when going between the VM and the Unsafe API.
 101 // The conversion functions just happen to be no-ops at present.
 102 
 103 static inline jlong field_offset_to_byte_offset(jlong field_offset) {
 104   return field_offset;
 105 }
 106 
 107 static inline jlong field_offset_from_byte_offset(jlong byte_offset) {
 108   return byte_offset;
 109 }
 110 
 111 static inline void assert_field_offset_sane(oop p, jlong field_offset) {
 112 #ifdef ASSERT
 113   jlong byte_offset = field_offset_to_byte_offset(field_offset);
 114 
 115   if (p != NULL) {
 116     assert(byte_offset >= 0 && byte_offset <= (jlong)MAX_OBJECT_SIZE, "sane offset");
 117     if (byte_offset == (jint)byte_offset) {
 118       void* ptr_plus_disp = (address)p + byte_offset;
 119       assert(p->field_addr_raw((jint)byte_offset) == ptr_plus_disp,
 120              "raw [ptr+disp] must be consistent with oop::field_addr_raw");
 121     }
 122     jlong p_size = HeapWordSize * (jlong)(p->size());
 123     assert(byte_offset < p_size, "Unsafe access: offset " INT64_FORMAT " > object's size " INT64_FORMAT, (int64_t)byte_offset, (int64_t)p_size);
 124   }
 125 #endif
 126 }
 127 
 128 static inline void* index_oop_from_field_offset_long(oop p, jlong field_offset) {
 129   assert_field_offset_sane(p, field_offset);
 130   jlong byte_offset = field_offset_to_byte_offset(field_offset);
 131 
 132   if (p != NULL) {
 133     p = Access<>::resolve(p);
 134   }
 135 
 136   if (sizeof(char*) == sizeof(jint)) {   // (this constant folds!)
 137     return (address)p + (jint) byte_offset;
 138   } else {
 139     return (address)p +        byte_offset;
 140   }
 141 }
 142 
 143 // Externally callable versions:
 144 // (Use these in compiler intrinsics which emulate unsafe primitives.)
 145 jlong Unsafe_field_offset_to_byte_offset(jlong field_offset) {
 146   return field_offset;
 147 }
 148 jlong Unsafe_field_offset_from_byte_offset(jlong byte_offset) {
 149   return byte_offset;
 150 }
 151 
 152 ///// Data read/writes on the Java heap and in native (off-heap) memory
 153 
 154 /**
 155  * Helper class for accessing memory.
 156  *
 157  * Normalizes values and wraps accesses in
 158  * JavaThread::doing_unsafe_access() if needed.
 159  */
 160 template <typename T>
 161 class MemoryAccess : StackObj {
 162   JavaThread* _thread;
 163   oop _obj;
 164   ptrdiff_t _offset;
 165 
 166   // Resolves and returns the address of the memory access.
 167   // This raw memory access may fault, so we make sure it happens within the
 168   // guarded scope by making the access volatile at least. Since the store
 169   // of Thread::set_doing_unsafe_access() is also volatile, these accesses
 170   // can not be reordered by the compiler. Therefore, if the access triggers
 171   // a fault, we will know that Thread::doing_unsafe_access() returns true.
 172   volatile T* addr() {
 173     void* addr = index_oop_from_field_offset_long(_obj, _offset);
 174     return static_cast<volatile T*>(addr);
 175   }
 176 
 177   template <typename U>
 178   U normalize_for_write(U x) {
 179     return x;
 180   }
 181 
 182   jboolean normalize_for_write(jboolean x) {
 183     return x & 1;
 184   }
 185 
 186   template <typename U>
 187   U normalize_for_read(U x) {
 188     return x;
 189   }
 190 
 191   jboolean normalize_for_read(jboolean x) {
 192     return x != 0;
 193   }
 194 
 195   /**
 196    * Helper class to wrap memory accesses in JavaThread::doing_unsafe_access()
 197    */
 198   class GuardUnsafeAccess {
 199     JavaThread* _thread;
 200 
 201   public:
 202     GuardUnsafeAccess(JavaThread* thread) : _thread(thread) {
 203       // native/off-heap access which may raise SIGBUS if accessing
 204       // memory mapped file data in a region of the file which has
 205       // been truncated and is now invalid
 206       _thread->set_doing_unsafe_access(true);
 207     }
 208 
 209     ~GuardUnsafeAccess() {
 210       _thread->set_doing_unsafe_access(false);
 211     }
 212   };
 213 
 214 public:
 215   MemoryAccess(JavaThread* thread, jobject obj, jlong offset)
 216     : _thread(thread), _obj(JNIHandles::resolve(obj)), _offset((ptrdiff_t)offset) {
 217     assert_field_offset_sane(_obj, offset);
 218   }
 219 
 220   T get() {
 221     if (_obj == NULL) {
 222       GuardUnsafeAccess guard(_thread);
 223       T ret = RawAccess<>::load(addr());
 224       return normalize_for_read(ret);
 225     } else {
 226       T ret = HeapAccess<>::load_at(_obj, _offset);
 227       return normalize_for_read(ret);
 228     }
 229   }
 230 
 231   void put(T x) {
 232     if (_obj == NULL) {
 233       GuardUnsafeAccess guard(_thread);
 234       RawAccess<>::store(addr(), normalize_for_write(x));
 235     } else {
 236       assert(!_obj->is_value() || _obj->mark()->is_larval_state(), "must be an object instance or a larval value");
 237       HeapAccess<>::store_at(_obj, _offset, normalize_for_write(x));
 238     }
 239   }
 240 
 241   T get_volatile() {
 242     if (_obj == NULL) {
 243       GuardUnsafeAccess guard(_thread);
 244       volatile T ret = RawAccess<MO_SEQ_CST>::load(addr());
 245       return normalize_for_read(ret);
 246     } else {
 247       T ret = HeapAccess<MO_SEQ_CST>::load_at(_obj, _offset);
 248       return normalize_for_read(ret);
 249     }
 250   }
 251 
 252   void put_volatile(T x) {
 253     if (_obj == NULL) {
 254       GuardUnsafeAccess guard(_thread);
 255       RawAccess<MO_SEQ_CST>::store(addr(), normalize_for_write(x));
 256     } else {
 257       HeapAccess<MO_SEQ_CST>::store_at(_obj, _offset, normalize_for_write(x));
 258     }
 259   }
 260 };
 261 
 262 #ifdef ASSERT
 263 /*
 264  * Get the field descriptor of the field of the given object at the given offset.
 265  */
 266 static bool get_field_descriptor(oop p, jlong offset, fieldDescriptor* fd) {
 267   bool found = false;
 268   Klass* k = p->klass();
 269   if (k->is_instance_klass()) {
 270     InstanceKlass* ik = InstanceKlass::cast(k);
 271     found = ik->find_field_from_offset((int)offset, false, fd);
 272     if (!found && ik->is_mirror_instance_klass()) {
 273       Klass* k2 = java_lang_Class::as_Klass(p);
 274       if (k2->is_instance_klass()) {
 275         ik = InstanceKlass::cast(k2);
 276         found = ik->find_field_from_offset((int)offset, true, fd);
 277       }
 278     }
 279   }
 280   return found;
 281 }
 282 #endif // ASSERT
 283 
 284 static void assert_and_log_unsafe_value_access(oop p, jlong offset, ValueKlass* vk) {
 285   Klass* k = p->klass();
 286 #ifdef ASSERT
 287   if (k->is_instance_klass()) {
 288     assert_field_offset_sane(p, offset);
 289     fieldDescriptor fd;
 290     bool found = get_field_descriptor(p, offset, &fd);
 291     if (found) {
 292       assert(found, "value field not found");
 293       assert(fd.is_flattened(), "field not flat");
 294     } else {
 295       if (log_is_enabled(Trace, valuetypes)) {
 296         log_trace(valuetypes)("not a field in %s at offset " SIZE_FORMAT_HEX,
 297                               p->klass()->external_name(), offset);
 298       }
 299     }
 300   } else if (k->is_valueArray_klass()) {
 301     ValueArrayKlass* vak = ValueArrayKlass::cast(k);
 302     int index = (offset - vak->array_header_in_bytes()) / vak->element_byte_size();
 303     address dest = (address)((valueArrayOop)p)->value_at_addr(index, vak->layout_helper());
 304     assert(dest == ((address)p) + offset, "invalid offset");
 305   } else {
 306     ShouldNotReachHere();
 307   }
 308 #endif // ASSERT
 309   if (log_is_enabled(Trace, valuetypes)) {
 310     if (k->is_valueArray_klass()) {
 311       ValueArrayKlass* vak = ValueArrayKlass::cast(k);
 312       int index = (offset - vak->array_header_in_bytes()) / vak->element_byte_size();
 313       address dest = (address)((valueArrayOop)p)->value_at_addr(index, vak->layout_helper());
 314       log_trace(valuetypes)("%s array type %s index %d element size %d offset " SIZE_FORMAT_HEX " at " INTPTR_FORMAT,
 315                             p->klass()->external_name(), vak->external_name(),
 316                             index, vak->element_byte_size(), offset, p2i(dest));
 317     } else {
 318       log_trace(valuetypes)("%s field type %s at offset " SIZE_FORMAT_HEX,
 319                             p->klass()->external_name(), vk->external_name(), offset);
 320     }
 321   }
 322 }
 323 
 324 // These functions allow a null base pointer with an arbitrary address.
 325 // But if the base pointer is non-null, the offset should make some sense.
 326 // That is, it should be in the range [0, MAX_OBJECT_SIZE].
 327 UNSAFE_ENTRY(jobject, Unsafe_GetReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
 328   oop p = JNIHandles::resolve(obj);
 329   assert_field_offset_sane(p, offset);
 330   oop v = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_load_at(p, offset);
 331   return JNIHandles::make_local(env, v);
 332 } UNSAFE_END
 333 
 334 UNSAFE_ENTRY(void, Unsafe_PutReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
 335   oop x = JNIHandles::resolve(x_h);
 336   oop p = JNIHandles::resolve(obj);
 337   assert_field_offset_sane(p, offset);
 338   assert(!p->is_value() || p->mark()->is_larval_state(), "must be an object instance or a larval value");
 339   HeapAccess<ON_UNKNOWN_OOP_REF>::oop_store_at(p, offset, x);
 340 } UNSAFE_END
 341 
 342 UNSAFE_ENTRY(jlong, Unsafe_ValueHeaderSize(JNIEnv *env, jobject unsafe, jclass c)) {
 343   Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(c));
 344   ValueKlass* vk = ValueKlass::cast(k);
 345   return vk->first_field_offset();
 346 } UNSAFE_END
 347 
 348 UNSAFE_ENTRY(jboolean, Unsafe_IsFlattenedArray(JNIEnv *env, jobject unsafe, jclass c)) {
 349   Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(c));
 350   return k->is_valueArray_klass();
 351 } UNSAFE_END
 352 
 353 UNSAFE_ENTRY(jobject, Unsafe_GetValue(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jclass vc)) {
 354   oop base = JNIHandles::resolve(obj);
 355   Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(vc));
 356   ValueKlass* vk = ValueKlass::cast(k);
 357   assert_and_log_unsafe_value_access(base, offset, vk);
 358   Handle base_h(THREAD, base);
 359   oop v = vk->allocate_instance(CHECK_NULL); // allocate instance
 360   vk->initialize(CHECK_NULL); // If field is a default value, value class might not be initialized yet
 361   vk->value_store(((address)(oopDesc*)base_h()) + offset,
 362                   vk->data_for_oop(v),
 363                   true, true);
 364   return JNIHandles::make_local(env, v);
 365 } UNSAFE_END
 366 
 367 UNSAFE_ENTRY(void, Unsafe_PutValue(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jclass vc, jobject value)) {
 368   oop base = JNIHandles::resolve(obj);
 369   Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(vc));
 370   ValueKlass* vk = ValueKlass::cast(k);
 371   assert(!base->is_value() || base->mark()->is_larval_state(), "must be an object instance or a larval value");
 372   assert_and_log_unsafe_value_access(base, offset, vk);
 373   oop v = JNIHandles::resolve(value);
 374   vk->value_store(vk->data_for_oop(v),
 375                  ((address)(oopDesc*)base) + offset, true, true);
 376 } UNSAFE_END
 377 
 378 UNSAFE_ENTRY(jobject, Unsafe_MakePrivateBuffer(JNIEnv *env, jobject unsafe, jobject value)) {
 379   oop v = JNIHandles::resolve_non_null(value);
 380   assert(v->is_value(), "must be a value instance");
 381   Handle vh(THREAD, v);
 382   ValueKlass* vk = ValueKlass::cast(v->klass());
 383   instanceOop new_value = vk->allocate_instance(CHECK_NULL);
 384   vk->value_store(vk->data_for_oop(vh()), vk->data_for_oop(new_value), true, false);
 385   markOop mark = new_value->mark();
 386   new_value->set_mark(mark->enter_larval_state());
 387   return JNIHandles::make_local(env, new_value);
 388 } UNSAFE_END
 389 
 390 UNSAFE_ENTRY(jobject, Unsafe_FinishPrivateBuffer(JNIEnv *env, jobject unsafe, jobject value)) {
 391   oop v = JNIHandles::resolve(value);
 392   assert(v->mark()->is_larval_state(), "must be a larval value");
 393   markOop mark = v->mark();
 394   v->set_mark(mark->exit_larval_state());
 395   return JNIHandles::make_local(env, v);
 396 } UNSAFE_END
 397 
 398 UNSAFE_ENTRY(jobject, Unsafe_GetReferenceVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
 399   oop p = JNIHandles::resolve(obj);
 400   assert_field_offset_sane(p, offset);
 401   oop v = HeapAccess<MO_SEQ_CST | ON_UNKNOWN_OOP_REF>::oop_load_at(p, offset);
 402   return JNIHandles::make_local(env, v);
 403 } UNSAFE_END
 404 
 405 UNSAFE_ENTRY(void, Unsafe_PutReferenceVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
 406   oop x = JNIHandles::resolve(x_h);
 407   oop p = JNIHandles::resolve(obj);
 408   assert_field_offset_sane(p, offset);
 409   HeapAccess<MO_SEQ_CST | ON_UNKNOWN_OOP_REF>::oop_store_at(p, offset, x);
 410 } UNSAFE_END
 411 
 412 UNSAFE_ENTRY(jobject, Unsafe_GetUncompressedObject(JNIEnv *env, jobject unsafe, jlong addr)) {
 413   oop v = *(oop*) (address) addr;
 414   return JNIHandles::make_local(env, v);
 415 } UNSAFE_END
 416 
 417 UNSAFE_LEAF(jboolean, Unsafe_isBigEndian0(JNIEnv *env, jobject unsafe)) {
 418 #ifdef VM_LITTLE_ENDIAN
 419   return false;
 420 #else
 421   return true;
 422 #endif
 423 } UNSAFE_END
 424 
 425 UNSAFE_LEAF(jint, Unsafe_unalignedAccess0(JNIEnv *env, jobject unsafe)) {
 426   return UseUnalignedAccesses;
 427 } UNSAFE_END
 428 
 429 #define DEFINE_GETSETOOP(java_type, Type) \
 430  \
 431 UNSAFE_ENTRY(java_type, Unsafe_Get##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
 432   return MemoryAccess<java_type>(thread, obj, offset).get(); \
 433 } UNSAFE_END \
 434  \
 435 UNSAFE_ENTRY(void, Unsafe_Put##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
 436   MemoryAccess<java_type>(thread, obj, offset).put(x); \
 437 } UNSAFE_END \
 438  \
 439 // END DEFINE_GETSETOOP.
 440 
 441 DEFINE_GETSETOOP(jboolean, Boolean)
 442 DEFINE_GETSETOOP(jbyte, Byte)
 443 DEFINE_GETSETOOP(jshort, Short);
 444 DEFINE_GETSETOOP(jchar, Char);
 445 DEFINE_GETSETOOP(jint, Int);
 446 DEFINE_GETSETOOP(jlong, Long);
 447 DEFINE_GETSETOOP(jfloat, Float);
 448 DEFINE_GETSETOOP(jdouble, Double);
 449 
 450 #undef DEFINE_GETSETOOP
 451 
 452 #define DEFINE_GETSETOOP_VOLATILE(java_type, Type) \
 453  \
 454 UNSAFE_ENTRY(java_type, Unsafe_Get##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
 455   return MemoryAccess<java_type>(thread, obj, offset).get_volatile(); \
 456 } UNSAFE_END \
 457  \
 458 UNSAFE_ENTRY(void, Unsafe_Put##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
 459   MemoryAccess<java_type>(thread, obj, offset).put_volatile(x); \
 460 } UNSAFE_END \
 461  \
 462 // END DEFINE_GETSETOOP_VOLATILE.
 463 
 464 DEFINE_GETSETOOP_VOLATILE(jboolean, Boolean)
 465 DEFINE_GETSETOOP_VOLATILE(jbyte, Byte)
 466 DEFINE_GETSETOOP_VOLATILE(jshort, Short);
 467 DEFINE_GETSETOOP_VOLATILE(jchar, Char);
 468 DEFINE_GETSETOOP_VOLATILE(jint, Int);
 469 DEFINE_GETSETOOP_VOLATILE(jlong, Long);
 470 DEFINE_GETSETOOP_VOLATILE(jfloat, Float);
 471 DEFINE_GETSETOOP_VOLATILE(jdouble, Double);
 472 
 473 #undef DEFINE_GETSETOOP_VOLATILE
 474 
 475 UNSAFE_LEAF(void, Unsafe_LoadFence(JNIEnv *env, jobject unsafe)) {
 476   OrderAccess::acquire();
 477 } UNSAFE_END
 478 
 479 UNSAFE_LEAF(void, Unsafe_StoreFence(JNIEnv *env, jobject unsafe)) {
 480   OrderAccess::release();
 481 } UNSAFE_END
 482 
 483 UNSAFE_LEAF(void, Unsafe_FullFence(JNIEnv *env, jobject unsafe)) {
 484   OrderAccess::fence();
 485 } UNSAFE_END
 486 
 487 ////// Allocation requests
 488 
 489 UNSAFE_ENTRY(jobject, Unsafe_AllocateInstance(JNIEnv *env, jobject unsafe, jclass cls)) {
 490   ThreadToNativeFromVM ttnfv(thread);
 491   return env->AllocObject(cls);
 492 } UNSAFE_END
 493 
 494 UNSAFE_ENTRY(jlong, Unsafe_AllocateMemory0(JNIEnv *env, jobject unsafe, jlong size)) {
 495   size_t sz = (size_t)size;
 496 
 497   sz = align_up(sz, HeapWordSize);
 498   void* x = os::malloc(sz, mtOther);
 499 
 500   return addr_to_java(x);
 501 } UNSAFE_END
 502 
 503 UNSAFE_ENTRY(jlong, Unsafe_ReallocateMemory0(JNIEnv *env, jobject unsafe, jlong addr, jlong size)) {
 504   void* p = addr_from_java(addr);
 505   size_t sz = (size_t)size;
 506   sz = align_up(sz, HeapWordSize);
 507 
 508   void* x = os::realloc(p, sz, mtOther);
 509 
 510   return addr_to_java(x);
 511 } UNSAFE_END
 512 
 513 UNSAFE_ENTRY(void, Unsafe_FreeMemory0(JNIEnv *env, jobject unsafe, jlong addr)) {
 514   void* p = addr_from_java(addr);
 515 
 516   os::free(p);
 517 } UNSAFE_END
 518 
 519 UNSAFE_ENTRY(void, Unsafe_SetMemory0(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong size, jbyte value)) {
 520   size_t sz = (size_t)size;
 521 
 522   oop base = JNIHandles::resolve(obj);
 523   void* p = index_oop_from_field_offset_long(base, offset);
 524 
 525   Copy::fill_to_memory_atomic(p, sz, value);
 526 } UNSAFE_END
 527 
 528 UNSAFE_ENTRY(void, Unsafe_CopyMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size)) {
 529   size_t sz = (size_t)size;
 530 
 531   oop srcp = JNIHandles::resolve(srcObj);
 532   oop dstp = JNIHandles::resolve(dstObj);
 533 
 534   void* src = index_oop_from_field_offset_long(srcp, srcOffset);
 535   void* dst = index_oop_from_field_offset_long(dstp, dstOffset);
 536 
 537   Copy::conjoint_memory_atomic(src, dst, sz);
 538 } UNSAFE_END
 539 
 540 // This function is a leaf since if the source and destination are both in native memory
 541 // the copy may potentially be very large, and we don't want to disable GC if we can avoid it.
 542 // If either source or destination (or both) are on the heap, the function will enter VM using
 543 // JVM_ENTRY_FROM_LEAF
 544 UNSAFE_LEAF(void, Unsafe_CopySwapMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size, jlong elemSize)) {
 545   size_t sz = (size_t)size;
 546   size_t esz = (size_t)elemSize;
 547 
 548   if (srcObj == NULL && dstObj == NULL) {
 549     // Both src & dst are in native memory
 550     address src = (address)srcOffset;
 551     address dst = (address)dstOffset;
 552 
 553     Copy::conjoint_swap(src, dst, sz, esz);
 554   } else {
 555     // At least one of src/dst are on heap, transition to VM to access raw pointers
 556 
 557     JVM_ENTRY_FROM_LEAF(env, void, Unsafe_CopySwapMemory0) {
 558       oop srcp = JNIHandles::resolve(srcObj);
 559       oop dstp = JNIHandles::resolve(dstObj);
 560 
 561       address src = (address)index_oop_from_field_offset_long(srcp, srcOffset);
 562       address dst = (address)index_oop_from_field_offset_long(dstp, dstOffset);
 563 
 564       Copy::conjoint_swap(src, dst, sz, esz);
 565     } JVM_END
 566   }
 567 } UNSAFE_END
 568 
 569 ////// Random queries
 570 
 571 UNSAFE_LEAF(jint, Unsafe_AddressSize0(JNIEnv *env, jobject unsafe)) {
 572   return sizeof(void*);
 573 } UNSAFE_END
 574 
 575 UNSAFE_LEAF(jint, Unsafe_PageSize()) {
 576   return os::vm_page_size();
 577 } UNSAFE_END
 578 
 579 static jlong find_field_offset(jclass clazz, jstring name, TRAPS) {
 580   assert(clazz != NULL, "clazz must not be NULL");
 581   assert(name != NULL, "name must not be NULL");
 582 
 583   ResourceMark rm(THREAD);
 584   char *utf_name = java_lang_String::as_utf8_string(JNIHandles::resolve_non_null(name));
 585 
 586   InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(JNIHandles::resolve_non_null(clazz)));
 587 
 588   jint offset = -1;
 589   for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
 590     Symbol *name = fs.name();
 591     if (name->equals(utf_name)) {
 592       offset = fs.offset();
 593       break;
 594     }
 595   }
 596   if (offset < 0) {
 597     THROW_0(vmSymbols::java_lang_InternalError());
 598   }
 599   return field_offset_from_byte_offset(offset);
 600 }
 601 
 602 static jlong find_field_offset(jobject field, int must_be_static, TRAPS) {
 603   assert(field != NULL, "field must not be NULL");
 604 
 605   oop reflected   = JNIHandles::resolve_non_null(field);
 606   oop mirror      = java_lang_reflect_Field::clazz(reflected);
 607   Klass* k        = java_lang_Class::as_Klass(mirror);
 608   int slot        = java_lang_reflect_Field::slot(reflected);
 609   int modifiers   = java_lang_reflect_Field::modifiers(reflected);
 610 
 611   if (must_be_static >= 0) {
 612     int really_is_static = ((modifiers & JVM_ACC_STATIC) != 0);
 613     if (must_be_static != really_is_static) {
 614       THROW_0(vmSymbols::java_lang_IllegalArgumentException());
 615     }
 616   }
 617 
 618   int offset = InstanceKlass::cast(k)->field_offset(slot);
 619   return field_offset_from_byte_offset(offset);
 620 }
 621 
 622 UNSAFE_ENTRY(jlong, Unsafe_ObjectFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
 623   return find_field_offset(field, 0, THREAD);
 624 } UNSAFE_END
 625 
 626 UNSAFE_ENTRY(jlong, Unsafe_ObjectFieldOffset1(JNIEnv *env, jobject unsafe, jclass c, jstring name)) {
 627   return find_field_offset(c, name, THREAD);
 628 } UNSAFE_END
 629 
 630 UNSAFE_ENTRY(jlong, Unsafe_StaticFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
 631   return find_field_offset(field, 1, THREAD);
 632 } UNSAFE_END
 633 
 634 UNSAFE_ENTRY(jobject, Unsafe_StaticFieldBase0(JNIEnv *env, jobject unsafe, jobject field)) {
 635   assert(field != NULL, "field must not be NULL");
 636 
 637   // Note:  In this VM implementation, a field address is always a short
 638   // offset from the base of a a klass metaobject.  Thus, the full dynamic
 639   // range of the return type is never used.  However, some implementations
 640   // might put the static field inside an array shared by many classes,
 641   // or even at a fixed address, in which case the address could be quite
 642   // large.  In that last case, this function would return NULL, since
 643   // the address would operate alone, without any base pointer.
 644 
 645   oop reflected   = JNIHandles::resolve_non_null(field);
 646   oop mirror      = java_lang_reflect_Field::clazz(reflected);
 647   int modifiers   = java_lang_reflect_Field::modifiers(reflected);
 648 
 649   if ((modifiers & JVM_ACC_STATIC) == 0) {
 650     THROW_0(vmSymbols::java_lang_IllegalArgumentException());
 651   }
 652 
 653   return JNIHandles::make_local(env, mirror);
 654 } UNSAFE_END
 655 
 656 UNSAFE_ENTRY(void, Unsafe_EnsureClassInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
 657   assert(clazz != NULL, "clazz must not be NULL");
 658 
 659   oop mirror = JNIHandles::resolve_non_null(clazz);
 660 
 661   Klass* klass = java_lang_Class::as_Klass(mirror);
 662   if (klass != NULL && klass->should_be_initialized()) {
 663     InstanceKlass* k = InstanceKlass::cast(klass);
 664     k->initialize(CHECK);
 665   }
 666 }
 667 UNSAFE_END
 668 
 669 UNSAFE_ENTRY(jboolean, Unsafe_ShouldBeInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
 670   assert(clazz != NULL, "clazz must not be NULL");
 671 
 672   oop mirror = JNIHandles::resolve_non_null(clazz);
 673   Klass* klass = java_lang_Class::as_Klass(mirror);
 674 
 675   if (klass != NULL && klass->should_be_initialized()) {
 676     return true;
 677   }
 678 
 679   return false;
 680 }
 681 UNSAFE_END
 682 
 683 static void getBaseAndScale(int& base, int& scale, jclass clazz, TRAPS) {
 684   assert(clazz != NULL, "clazz must not be NULL");
 685 
 686   oop mirror = JNIHandles::resolve_non_null(clazz);
 687   Klass* k = java_lang_Class::as_Klass(mirror);
 688 
 689   if (k == NULL || !k->is_array_klass()) {
 690     THROW(vmSymbols::java_lang_InvalidClassException());
 691   } else if (k->is_objArray_klass()) {
 692     base  = arrayOopDesc::base_offset_in_bytes(T_OBJECT);
 693     scale = heapOopSize;
 694   } else if (k->is_typeArray_klass()) {
 695     TypeArrayKlass* tak = TypeArrayKlass::cast(k);
 696     base  = tak->array_header_in_bytes();
 697     assert(base == arrayOopDesc::base_offset_in_bytes(tak->element_type()), "array_header_size semantics ok");
 698     scale = (1 << tak->log2_element_size());
 699   } else if (k->is_valueArray_klass()) {
 700     ValueArrayKlass* vak = ValueArrayKlass::cast(k);
 701     ValueKlass* vklass = vak->element_klass();
 702     base = vak->array_header_in_bytes();
 703     scale = vak->element_byte_size();
 704   } else {
 705     ShouldNotReachHere();
 706   }
 707 }
 708 
 709 UNSAFE_ENTRY(jint, Unsafe_ArrayBaseOffset0(JNIEnv *env, jobject unsafe, jclass clazz)) {
 710   int base = 0, scale = 0;
 711   getBaseAndScale(base, scale, clazz, CHECK_0);
 712 
 713   return field_offset_from_byte_offset(base);
 714 } UNSAFE_END
 715 
 716 
 717 UNSAFE_ENTRY(jint, Unsafe_ArrayIndexScale0(JNIEnv *env, jobject unsafe, jclass clazz)) {
 718   int base = 0, scale = 0;
 719   getBaseAndScale(base, scale, clazz, CHECK_0);
 720 
 721   // This VM packs both fields and array elements down to the byte.
 722   // But watch out:  If this changes, so that array references for
 723   // a given primitive type (say, T_BOOLEAN) use different memory units
 724   // than fields, this method MUST return zero for such arrays.
 725   // For example, the VM used to store sub-word sized fields in full
 726   // words in the object layout, so that accessors like getByte(Object,int)
 727   // did not really do what one might expect for arrays.  Therefore,
 728   // this function used to report a zero scale factor, so that the user
 729   // would know not to attempt to access sub-word array elements.
 730   // // Code for unpacked fields:
 731   // if (scale < wordSize)  return 0;
 732 
 733   // The following allows for a pretty general fieldOffset cookie scheme,
 734   // but requires it to be linear in byte offset.
 735   return field_offset_from_byte_offset(scale) - field_offset_from_byte_offset(0);
 736 } UNSAFE_END
 737 
 738 
 739 static inline void throw_new(JNIEnv *env, const char *ename) {
 740   jclass cls = env->FindClass(ename);
 741   if (env->ExceptionCheck()) {
 742     env->ExceptionClear();
 743     tty->print_cr("Unsafe: cannot throw %s because FindClass has failed", ename);
 744     return;
 745   }
 746 
 747   env->ThrowNew(cls, NULL);
 748 }
 749 
 750 static jclass Unsafe_DefineClass_impl(JNIEnv *env, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd) {
 751   // Code lifted from JDK 1.3 ClassLoader.c
 752 
 753   jbyte *body;
 754   char *utfName = NULL;
 755   jclass result = 0;
 756   char buf[128];
 757 
 758   assert(data != NULL, "Class bytes must not be NULL");
 759   assert(length >= 0, "length must not be negative: %d", length);
 760 
 761   if (UsePerfData) {
 762     ClassLoader::unsafe_defineClassCallCounter()->inc();
 763   }
 764 
 765   body = NEW_C_HEAP_ARRAY(jbyte, length, mtInternal);
 766   if (body == NULL) {
 767     throw_new(env, "java/lang/OutOfMemoryError");
 768     return 0;
 769   }
 770 
 771   env->GetByteArrayRegion(data, offset, length, body);
 772   if (env->ExceptionOccurred()) {
 773     goto free_body;
 774   }
 775 
 776   if (name != NULL) {
 777     uint len = env->GetStringUTFLength(name);
 778     int unicode_len = env->GetStringLength(name);
 779 
 780     if (len >= sizeof(buf)) {
 781       utfName = NEW_C_HEAP_ARRAY(char, len + 1, mtInternal);
 782       if (utfName == NULL) {
 783         throw_new(env, "java/lang/OutOfMemoryError");
 784         goto free_body;
 785       }
 786     } else {
 787       utfName = buf;
 788     }
 789 
 790     env->GetStringUTFRegion(name, 0, unicode_len, utfName);
 791 
 792     for (uint i = 0; i < len; i++) {
 793       if (utfName[i] == '.')   utfName[i] = '/';
 794     }
 795   }
 796 
 797   result = JVM_DefineClass(env, utfName, loader, body, length, pd);
 798 
 799   if (utfName && utfName != buf) {
 800     FREE_C_HEAP_ARRAY(char, utfName);
 801   }
 802 
 803  free_body:
 804   FREE_C_HEAP_ARRAY(jbyte, body);
 805   return result;
 806 }
 807 
 808 
 809 UNSAFE_ENTRY(jclass, Unsafe_DefineClass0(JNIEnv *env, jobject unsafe, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd)) {
 810   ThreadToNativeFromVM ttnfv(thread);
 811 
 812   return Unsafe_DefineClass_impl(env, name, data, offset, length, loader, pd);
 813 } UNSAFE_END
 814 
 815 
 816 // define a class but do not make it known to the class loader or system dictionary
 817 // - host_class:  supplies context for linkage, access control, protection domain, and class loader
 818 //                if host_class is itself anonymous then it is replaced with its host class.
 819 // - data:  bytes of a class file, a raw memory address (length gives the number of bytes)
 820 // - cp_patches:  where non-null entries exist, they replace corresponding CP entries in data
 821 
 822 // When you load an anonymous class U, it works as if you changed its name just before loading,
 823 // to a name that you will never use again.  Since the name is lost, no other class can directly
 824 // link to any member of U.  Just after U is loaded, the only way to use it is reflectively,
 825 // through java.lang.Class methods like Class.newInstance.
 826 
 827 // The package of an anonymous class must either match its host's class's package or be in the
 828 // unnamed package.  If it is in the unnamed package then it will be put in its host class's
 829 // package.
 830 //
 831 
 832 // Access checks for linkage sites within U continue to follow the same rules as for named classes.
 833 // An anonymous class also has special privileges to access any member of its host class.
 834 // This is the main reason why this loading operation is unsafe.  The purpose of this is to
 835 // allow language implementations to simulate "open classes"; a host class in effect gets
 836 // new code when an anonymous class is loaded alongside it.  A less convenient but more
 837 // standard way to do this is with reflection, which can also be set to ignore access
 838 // restrictions.
 839 
 840 // Access into an anonymous class is possible only through reflection.  Therefore, there
 841 // are no special access rules for calling into an anonymous class.  The relaxed access
 842 // rule for the host class is applied in the opposite direction:  A host class reflectively
 843 // access one of its anonymous classes.
 844 
 845 // If you load the same bytecodes twice, you get two different classes.  You can reload
 846 // the same bytecodes with or without varying CP patches.
 847 
 848 // By using the CP patching array, you can have a new anonymous class U2 refer to an older one U1.
 849 // The bytecodes for U2 should refer to U1 by a symbolic name (doesn't matter what the name is).
 850 // The CONSTANT_Class entry for that name can be patched to refer directly to U1.
 851 
 852 // This allows, for example, U2 to use U1 as a superclass or super-interface, or as
 853 // an outer class (so that U2 is an anonymous inner class of anonymous U1).
 854 // It is not possible for a named class, or an older anonymous class, to refer by
 855 // name (via its CP) to a newer anonymous class.
 856 
 857 // CP patching may also be used to modify (i.e., hack) the names of methods, classes,
 858 // or type descriptors used in the loaded anonymous class.
 859 
 860 // Finally, CP patching may be used to introduce "live" objects into the constant pool,
 861 // instead of "dead" strings.  A compiled statement like println((Object)"hello") can
 862 // be changed to println(greeting), where greeting is an arbitrary object created before
 863 // the anonymous class is loaded.  This is useful in dynamic languages, in which
 864 // various kinds of metaobjects must be introduced as constants into bytecode.
 865 // Note the cast (Object), which tells the verifier to expect an arbitrary object,
 866 // not just a literal string.  For such ldc instructions, the verifier uses the
 867 // type Object instead of String, if the loaded constant is not in fact a String.
 868 
 869 static InstanceKlass*
 870 Unsafe_DefineAnonymousClass_impl(JNIEnv *env,
 871                                  jclass host_class, jbyteArray data, jobjectArray cp_patches_jh,
 872                                  u1** temp_alloc,
 873                                  TRAPS) {
 874   assert(host_class != NULL, "host_class must not be NULL");
 875   assert(data != NULL, "data must not be NULL");
 876 
 877   if (UsePerfData) {
 878     ClassLoader::unsafe_defineClassCallCounter()->inc();
 879   }
 880 
 881   jint length = typeArrayOop(JNIHandles::resolve_non_null(data))->length();
 882   assert(length >= 0, "class_bytes_length must not be negative: %d", length);
 883 
 884   int class_bytes_length = (int) length;
 885 
 886   u1* class_bytes = NEW_C_HEAP_ARRAY(u1, length, mtInternal);
 887   if (class_bytes == NULL) {
 888     THROW_0(vmSymbols::java_lang_OutOfMemoryError());
 889   }
 890 
 891   // caller responsible to free it:
 892   *temp_alloc = class_bytes;
 893 
 894   ArrayAccess<>::arraycopy_to_native(arrayOop(JNIHandles::resolve_non_null(data)), typeArrayOopDesc::element_offset<jbyte>(0),
 895                                      reinterpret_cast<jbyte*>(class_bytes), length);
 896 
 897   objArrayHandle cp_patches_h;
 898   if (cp_patches_jh != NULL) {
 899     oop p = JNIHandles::resolve_non_null(cp_patches_jh);
 900     assert(p->is_objArray(), "cp_patches must be an object[]");
 901     cp_patches_h = objArrayHandle(THREAD, (objArrayOop)p);
 902   }
 903 
 904   const Klass* host_klass = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(host_class));
 905 
 906   // Make sure it's the real host class, not another anonymous class.
 907   while (host_klass != NULL && host_klass->is_instance_klass() &&
 908          InstanceKlass::cast(host_klass)->is_unsafe_anonymous()) {
 909     host_klass = InstanceKlass::cast(host_klass)->unsafe_anonymous_host();
 910   }
 911 
 912   // Primitive types have NULL Klass* fields in their java.lang.Class instances.
 913   if (host_klass == NULL) {
 914     THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), "Host class is null");
 915   }
 916 
 917   assert(host_klass->is_instance_klass(), "Host class must be an instance class");
 918 
 919   const char* host_source = host_klass->external_name();
 920   Handle      host_loader(THREAD, host_klass->class_loader());
 921   Handle      host_domain(THREAD, host_klass->protection_domain());
 922 
 923   GrowableArray<Handle>* cp_patches = NULL;
 924 
 925   if (cp_patches_h.not_null()) {
 926     int alen = cp_patches_h->length();
 927 
 928     for (int i = alen-1; i >= 0; i--) {
 929       oop p = cp_patches_h->obj_at(i);
 930       if (p != NULL) {
 931         Handle patch(THREAD, p);
 932 
 933         if (cp_patches == NULL) {
 934           cp_patches = new GrowableArray<Handle>(i+1, i+1, Handle());
 935         }
 936 
 937         cp_patches->at_put(i, patch);
 938       }
 939     }
 940   }
 941 
 942   ClassFileStream st(class_bytes, class_bytes_length, host_source, ClassFileStream::verify);
 943 
 944   Symbol* no_class_name = NULL;
 945   Klass* anonk = SystemDictionary::parse_stream(no_class_name,
 946                                                 host_loader,
 947                                                 host_domain,
 948                                                 &st,
 949                                                 InstanceKlass::cast(host_klass),
 950                                                 cp_patches,
 951                                                 CHECK_NULL);
 952   if (anonk == NULL) {
 953     return NULL;
 954   }
 955 
 956   return InstanceKlass::cast(anonk);
 957 }
 958 
 959 UNSAFE_ENTRY(jclass, Unsafe_DefineAnonymousClass0(JNIEnv *env, jobject unsafe, jclass host_class, jbyteArray data, jobjectArray cp_patches_jh)) {
 960   ResourceMark rm(THREAD);
 961 
 962   jobject res_jh = NULL;
 963   u1* temp_alloc = NULL;
 964 
 965   InstanceKlass* anon_klass = Unsafe_DefineAnonymousClass_impl(env, host_class, data, cp_patches_jh, &temp_alloc, THREAD);
 966   if (anon_klass != NULL) {
 967     res_jh = JNIHandles::make_local(env, anon_klass->java_mirror());
 968   }
 969 
 970   // try/finally clause:
 971   if (temp_alloc != NULL) {
 972     FREE_C_HEAP_ARRAY(u1, temp_alloc);
 973   }
 974 
 975   // The anonymous class loader data has been artificially been kept alive to
 976   // this point.   The mirror and any instances of this class have to keep
 977   // it alive afterwards.
 978   if (anon_klass != NULL) {
 979     anon_klass->class_loader_data()->dec_keep_alive();
 980   }
 981 
 982   // let caller initialize it as needed...
 983 
 984   return (jclass) res_jh;
 985 } UNSAFE_END
 986 
 987 
 988 
 989 UNSAFE_ENTRY(void, Unsafe_ThrowException(JNIEnv *env, jobject unsafe, jthrowable thr)) {
 990   ThreadToNativeFromVM ttnfv(thread);
 991   env->Throw(thr);
 992 } UNSAFE_END
 993 
 994 // JSR166 ------------------------------------------------------------------
 995 
 996 UNSAFE_ENTRY(jobject, Unsafe_CompareAndExchangeReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
 997   oop x = JNIHandles::resolve(x_h);
 998   oop e = JNIHandles::resolve(e_h);
 999   oop p = JNIHandles::resolve(obj);
1000   assert_field_offset_sane(p, offset);
1001   oop res = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e);
1002   return JNIHandles::make_local(env, res);
1003 } UNSAFE_END
1004 
1005 UNSAFE_ENTRY(jint, Unsafe_CompareAndExchangeInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
1006   oop p = JNIHandles::resolve(obj);
1007   if (p == NULL) {
1008     volatile jint* addr = (volatile jint*)index_oop_from_field_offset_long(p, offset);
1009     return RawAccess<>::atomic_cmpxchg(x, addr, e);
1010   } else {
1011     assert_field_offset_sane(p, offset);
1012     return HeapAccess<>::atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e);
1013   }
1014 } UNSAFE_END
1015 
1016 UNSAFE_ENTRY(jlong, Unsafe_CompareAndExchangeLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
1017   oop p = JNIHandles::resolve(obj);
1018   if (p == NULL) {
1019     volatile jlong* addr = (volatile jlong*)index_oop_from_field_offset_long(p, offset);
1020     return RawAccess<>::atomic_cmpxchg(x, addr, e);
1021   } else {
1022     assert_field_offset_sane(p, offset);
1023     return HeapAccess<>::atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e);
1024   }
1025 } UNSAFE_END
1026 
1027 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
1028   oop x = JNIHandles::resolve(x_h);
1029   oop e = JNIHandles::resolve(e_h);
1030   oop p = JNIHandles::resolve(obj);
1031   assert_field_offset_sane(p, offset);
1032   oop ret = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e);
1033   return oopDesc::equals(ret, e);
1034 } UNSAFE_END
1035 
1036 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
1037   oop p = JNIHandles::resolve(obj);
1038   if (p == NULL) {
1039     volatile jint* addr = (volatile jint*)index_oop_from_field_offset_long(p, offset);
1040     return RawAccess<>::atomic_cmpxchg(x, addr, e) == e;
1041   } else {
1042     assert_field_offset_sane(p, offset);
1043     return HeapAccess<>::atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e) == e;
1044   }
1045 } UNSAFE_END
1046 
1047 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
1048   oop p = JNIHandles::resolve(obj);
1049   if (p == NULL) {
1050     volatile jlong* addr = (volatile jlong*)index_oop_from_field_offset_long(p, offset);
1051     return RawAccess<>::atomic_cmpxchg(x, addr, e) == e;
1052   } else {
1053     assert_field_offset_sane(p, offset);
1054     return HeapAccess<>::atomic_cmpxchg_at(x, p, (ptrdiff_t)offset, e) == e;
1055   }
1056 } UNSAFE_END
1057 
1058 static void post_thread_park_event(EventThreadPark* event, const oop obj, jlong timeout) {
1059   assert(event != NULL, "invariant");
1060   assert(event->should_commit(), "invariant");
1061   event->set_parkedClass((obj != NULL) ? obj->klass() : NULL);
1062   event->set_timeout(timeout);
1063   event->set_address((obj != NULL) ? (u8)cast_from_oop<uintptr_t>(obj) : 0);
1064   event->commit();
1065 }
1066 
1067 UNSAFE_ENTRY(void, Unsafe_Park(JNIEnv *env, jobject unsafe, jboolean isAbsolute, jlong time)) {
1068   HOTSPOT_THREAD_PARK_BEGIN((uintptr_t) thread->parker(), (int) isAbsolute, time);
1069   EventThreadPark event;
1070 
1071   JavaThreadParkedState jtps(thread, time != 0);
1072   thread->parker()->park(isAbsolute != 0, time);
1073   if (event.should_commit()) {
1074     post_thread_park_event(&event, thread->current_park_blocker(), time);
1075   }
1076   HOTSPOT_THREAD_PARK_END((uintptr_t) thread->parker());
1077 } UNSAFE_END
1078 
1079 UNSAFE_ENTRY(void, Unsafe_Unpark(JNIEnv *env, jobject unsafe, jobject jthread)) {
1080   Parker* p = NULL;
1081 
1082   if (jthread != NULL) {
1083     ThreadsListHandle tlh;
1084     JavaThread* thr = NULL;
1085     oop java_thread = NULL;
1086     (void) tlh.cv_internal_thread_to_JavaThread(jthread, &thr, &java_thread);
1087     if (java_thread != NULL) {
1088       // This is a valid oop.
1089       jlong lp = java_lang_Thread::park_event(java_thread);
1090       if (lp != 0) {
1091         // This cast is OK even though the jlong might have been read
1092         // non-atomically on 32bit systems, since there, one word will
1093         // always be zero anyway and the value set is always the same
1094         p = (Parker*)addr_from_java(lp);
1095       } else {
1096         // Not cached in the java.lang.Thread oop yet (could be an
1097         // older version of library).
1098         if (thr != NULL) {
1099           // The JavaThread is alive.
1100           p = thr->parker();
1101           if (p != NULL) {
1102             // Cache the Parker in the java.lang.Thread oop for next time.
1103             java_lang_Thread::set_park_event(java_thread, addr_to_java(p));
1104           }
1105         }
1106       }
1107     }
1108   } // ThreadsListHandle is destroyed here.
1109 
1110   if (p != NULL) {
1111     HOTSPOT_THREAD_UNPARK((uintptr_t) p);
1112     p->unpark();
1113   }
1114 } UNSAFE_END
1115 
1116 UNSAFE_ENTRY(jint, Unsafe_GetLoadAverage0(JNIEnv *env, jobject unsafe, jdoubleArray loadavg, jint nelem)) {
1117   const int max_nelem = 3;
1118   double la[max_nelem];
1119   jint ret;
1120 
1121   typeArrayOop a = typeArrayOop(JNIHandles::resolve_non_null(loadavg));
1122   assert(a->is_typeArray(), "must be type array");
1123 
1124   ret = os::loadavg(la, nelem);
1125   if (ret == -1) {
1126     return -1;
1127   }
1128 
1129   // if successful, ret is the number of samples actually retrieved.
1130   assert(ret >= 0 && ret <= max_nelem, "Unexpected loadavg return value");
1131   switch(ret) {
1132     case 3: a->double_at_put(2, (jdouble)la[2]); // fall through
1133     case 2: a->double_at_put(1, (jdouble)la[1]); // fall through
1134     case 1: a->double_at_put(0, (jdouble)la[0]); break;
1135   }
1136 
1137   return ret;
1138 } UNSAFE_END
1139 
1140 
1141 /// JVM_RegisterUnsafeMethods
1142 
1143 #define ADR "J"
1144 
1145 #define LANG "Ljava/lang/"
1146 
1147 #define OBJ LANG "Object;"
1148 #define CLS LANG "Class;"
1149 #define FLD LANG "reflect/Field;"
1150 #define THR LANG "Throwable;"
1151 
1152 #define DC_Args  LANG "String;[BII" LANG "ClassLoader;" "Ljava/security/ProtectionDomain;"
1153 #define DAC_Args CLS "[B[" OBJ
1154 
1155 #define CC (char*)  /*cast a literal from (const char*)*/
1156 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
1157 
1158 #define DECLARE_GETPUTOOP(Type, Desc) \
1159     {CC "get"  #Type,      CC "(" OBJ "J)" #Desc,                 FN_PTR(Unsafe_Get##Type)}, \
1160     {CC "put"  #Type,      CC "(" OBJ "J" #Desc ")V",             FN_PTR(Unsafe_Put##Type)}, \
1161     {CC "get"  #Type "Volatile",      CC "(" OBJ "J)" #Desc,      FN_PTR(Unsafe_Get##Type##Volatile)}, \
1162     {CC "put"  #Type "Volatile",      CC "(" OBJ "J" #Desc ")V",  FN_PTR(Unsafe_Put##Type##Volatile)}
1163 
1164 
1165 static JNINativeMethod jdk_internal_misc_Unsafe_methods[] = {
1166     {CC "getReference",         CC "(" OBJ "J)" OBJ "",   FN_PTR(Unsafe_GetReference)},
1167     {CC "putReference",         CC "(" OBJ "J" OBJ ")V",  FN_PTR(Unsafe_PutReference)},
1168     {CC "getReferenceVolatile", CC "(" OBJ "J)" OBJ,      FN_PTR(Unsafe_GetReferenceVolatile)},
1169     {CC "putReferenceVolatile", CC "(" OBJ "J" OBJ ")V",  FN_PTR(Unsafe_PutReferenceVolatile)},
1170 
1171     {CC "isFlattenedArray", CC "(" CLS ")Z",                     FN_PTR(Unsafe_IsFlattenedArray)},
1172     {CC "getValue",         CC "(" OBJ "J" CLS ")" OBJ,          FN_PTR(Unsafe_GetValue)},
1173     {CC "putValue",         CC "(" OBJ "J" CLS OBJ ")V",         FN_PTR(Unsafe_PutValue)},
1174     {CC "makePrivateBuffer",     CC "(" OBJ ")" OBJ,             FN_PTR(Unsafe_MakePrivateBuffer)},
1175     {CC "finishPrivateBuffer",   CC "(" OBJ ")" OBJ,             FN_PTR(Unsafe_FinishPrivateBuffer)},
1176     {CC "valueHeaderSize",       CC "(" CLS ")J",                FN_PTR(Unsafe_ValueHeaderSize)},
1177 
1178     {CC "getUncompressedObject", CC "(" ADR ")" OBJ,  FN_PTR(Unsafe_GetUncompressedObject)},
1179 
1180     DECLARE_GETPUTOOP(Boolean, Z),
1181     DECLARE_GETPUTOOP(Byte, B),
1182     DECLARE_GETPUTOOP(Short, S),
1183     DECLARE_GETPUTOOP(Char, C),
1184     DECLARE_GETPUTOOP(Int, I),
1185     DECLARE_GETPUTOOP(Long, J),
1186     DECLARE_GETPUTOOP(Float, F),
1187     DECLARE_GETPUTOOP(Double, D),
1188 
1189     {CC "allocateMemory0",    CC "(J)" ADR,              FN_PTR(Unsafe_AllocateMemory0)},
1190     {CC "reallocateMemory0",  CC "(" ADR "J)" ADR,       FN_PTR(Unsafe_ReallocateMemory0)},
1191     {CC "freeMemory0",        CC "(" ADR ")V",           FN_PTR(Unsafe_FreeMemory0)},
1192 
1193     {CC "objectFieldOffset0", CC "(" FLD ")J",           FN_PTR(Unsafe_ObjectFieldOffset0)},
1194     {CC "objectFieldOffset1", CC "(" CLS LANG "String;)J", FN_PTR(Unsafe_ObjectFieldOffset1)},
1195     {CC "staticFieldOffset0", CC "(" FLD ")J",           FN_PTR(Unsafe_StaticFieldOffset0)},
1196     {CC "staticFieldBase0",   CC "(" FLD ")" OBJ,        FN_PTR(Unsafe_StaticFieldBase0)},
1197     {CC "ensureClassInitialized0", CC "(" CLS ")V",      FN_PTR(Unsafe_EnsureClassInitialized0)},
1198     {CC "arrayBaseOffset0",   CC "(" CLS ")I",           FN_PTR(Unsafe_ArrayBaseOffset0)},
1199     {CC "arrayIndexScale0",   CC "(" CLS ")I",           FN_PTR(Unsafe_ArrayIndexScale0)},
1200     {CC "addressSize0",       CC "()I",                  FN_PTR(Unsafe_AddressSize0)},
1201     {CC "pageSize",           CC "()I",                  FN_PTR(Unsafe_PageSize)},
1202 
1203     {CC "defineClass0",       CC "(" DC_Args ")" CLS,    FN_PTR(Unsafe_DefineClass0)},
1204     {CC "allocateInstance",   CC "(" CLS ")" OBJ,        FN_PTR(Unsafe_AllocateInstance)},
1205     {CC "throwException",     CC "(" THR ")V",           FN_PTR(Unsafe_ThrowException)},
1206     {CC "compareAndSetReference",CC "(" OBJ "J" OBJ "" OBJ ")Z", FN_PTR(Unsafe_CompareAndSetReference)},
1207     {CC "compareAndSetInt",   CC "(" OBJ "J""I""I"")Z",  FN_PTR(Unsafe_CompareAndSetInt)},
1208     {CC "compareAndSetLong",  CC "(" OBJ "J""J""J"")Z",  FN_PTR(Unsafe_CompareAndSetLong)},
1209     {CC "compareAndExchangeReference", CC "(" OBJ "J" OBJ "" OBJ ")" OBJ, FN_PTR(Unsafe_CompareAndExchangeReference)},
1210     {CC "compareAndExchangeInt",  CC "(" OBJ "J""I""I"")I", FN_PTR(Unsafe_CompareAndExchangeInt)},
1211     {CC "compareAndExchangeLong", CC "(" OBJ "J""J""J"")J", FN_PTR(Unsafe_CompareAndExchangeLong)},
1212 
1213     {CC "park",               CC "(ZJ)V",                FN_PTR(Unsafe_Park)},
1214     {CC "unpark",             CC "(" OBJ ")V",           FN_PTR(Unsafe_Unpark)},
1215 
1216     {CC "getLoadAverage0",    CC "([DI)I",               FN_PTR(Unsafe_GetLoadAverage0)},
1217 
1218     {CC "copyMemory0",        CC "(" OBJ "J" OBJ "JJ)V", FN_PTR(Unsafe_CopyMemory0)},
1219     {CC "copySwapMemory0",    CC "(" OBJ "J" OBJ "JJJ)V", FN_PTR(Unsafe_CopySwapMemory0)},
1220     {CC "setMemory0",         CC "(" OBJ "JJB)V",        FN_PTR(Unsafe_SetMemory0)},
1221 
1222     {CC "defineAnonymousClass0", CC "(" DAC_Args ")" CLS, FN_PTR(Unsafe_DefineAnonymousClass0)},
1223 
1224     {CC "shouldBeInitialized0", CC "(" CLS ")Z",         FN_PTR(Unsafe_ShouldBeInitialized0)},
1225 
1226     {CC "loadFence",          CC "()V",                  FN_PTR(Unsafe_LoadFence)},
1227     {CC "storeFence",         CC "()V",                  FN_PTR(Unsafe_StoreFence)},
1228     {CC "fullFence",          CC "()V",                  FN_PTR(Unsafe_FullFence)},
1229 
1230     {CC "isBigEndian0",       CC "()Z",                  FN_PTR(Unsafe_isBigEndian0)},
1231     {CC "unalignedAccess0",   CC "()Z",                  FN_PTR(Unsafe_unalignedAccess0)}
1232 };
1233 
1234 #undef CC
1235 #undef FN_PTR
1236 
1237 #undef ADR
1238 #undef LANG
1239 #undef OBJ
1240 #undef CLS
1241 #undef FLD
1242 #undef THR
1243 #undef DC_Args
1244 #undef DAC_Args
1245 
1246 #undef DECLARE_GETPUTOOP
1247 
1248 
1249 // This function is exported, used by NativeLookup.
1250 // The Unsafe_xxx functions above are called only from the interpreter.
1251 // The optimizer looks at names and signatures to recognize
1252 // individual functions.
1253 
1254 JVM_ENTRY(void, JVM_RegisterJDKInternalMiscUnsafeMethods(JNIEnv *env, jclass unsafeclass)) {
1255   ThreadToNativeFromVM ttnfv(thread);
1256 
1257   int ok = env->RegisterNatives(unsafeclass, jdk_internal_misc_Unsafe_methods, sizeof(jdk_internal_misc_Unsafe_methods)/sizeof(JNINativeMethod));
1258   guarantee(ok == 0, "register jdk.internal.misc.Unsafe natives");
1259 } JVM_END