1 /*
   2  * Copyright (c) 2000, 2025, 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 "classfile/classFileStream.hpp"
  26 #include "classfile/classLoader.hpp"
  27 #include "classfile/classLoadInfo.hpp"
  28 #include "classfile/javaClasses.inline.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "classfile/vmSymbols.hpp"
  31 #include "jfr/jfrEvents.hpp"
  32 #include "jni.h"
  33 #include "jvm.h"
  34 #include "logging/log.hpp"
  35 #include "logging/logStream.hpp"
  36 #include "memory/allocation.inline.hpp"
  37 #include "memory/oopFactory.hpp"
  38 #include "memory/resourceArea.hpp"
  39 #include "oops/access.inline.hpp"
  40 #include "oops/fieldStreams.inline.hpp"
  41 #include "oops/flatArrayKlass.hpp"
  42 #include "oops/flatArrayOop.inline.hpp"
  43 #include "oops/inlineKlass.inline.hpp"
  44 #include "oops/instanceKlass.inline.hpp"
  45 #include "oops/klass.inline.hpp"
  46 #include "oops/objArrayOop.inline.hpp"
  47 #include "oops/oop.inline.hpp"
  48 #include "oops/typeArrayOop.inline.hpp"
  49 #include "prims/jvmtiExport.hpp"
  50 #include "prims/unsafe.hpp"
  51 #include "runtime/fieldDescriptor.inline.hpp"
  52 #include "runtime/globals.hpp"
  53 #include "runtime/handles.inline.hpp"
  54 #include "runtime/interfaceSupport.inline.hpp"
  55 #include "runtime/javaThread.inline.hpp"
  56 #include "runtime/jniHandles.inline.hpp"
  57 #include "runtime/orderAccess.hpp"
  58 #include "runtime/reflection.hpp"
  59 #include "runtime/sharedRuntime.hpp"
  60 #include "runtime/stubRoutines.hpp"
  61 #include "runtime/threadSMR.hpp"
  62 #include "runtime/vm_version.hpp"
  63 #include "runtime/vmOperations.hpp"
  64 #include "sanitizers/ub.hpp"
  65 #include "services/threadService.hpp"
  66 #include "utilities/align.hpp"
  67 #include "utilities/copy.hpp"
  68 #include "utilities/dtrace.hpp"
  69 #include "utilities/macros.hpp"
  70 
  71 /**
  72  * Implementation of the jdk.internal.misc.Unsafe class
  73  */
  74 
  75 
  76 #define MAX_OBJECT_SIZE \
  77   ( arrayOopDesc::base_offset_in_bytes(T_DOUBLE) \
  78     + ((julong)max_jint * sizeof(double)) )
  79 
  80 #define UNSAFE_ENTRY(result_type, header) \
  81   JVM_ENTRY(static result_type, header)
  82 
  83 #define UNSAFE_LEAF(result_type, header) \
  84   JVM_LEAF(static result_type, header)
  85 
  86 // All memory access methods (e.g. getInt, copyMemory) must use this macro.
  87 // We call these methods "scoped" methods, as access to these methods is
  88 // typically governed by a "scope" (a MemorySessionImpl object), and no
  89 // access is allowed when the scope is no longer alive.
  90 //
  91 // Closing a scope object (cf. scopedMemoryAccess.cpp) can install
  92 // an async exception during a safepoint. When that happens,
  93 // scoped methods are not allowed to touch the underlying memory (as that
  94 // memory might have been released). Therefore, when entering a scoped method
  95 // we check if an async exception has been installed, and return immediately
  96 // if that is the case.
  97 //
  98 // As a rule, we disallow safepoints in the middle of a scoped method.
  99 // If an async exception handshake were installed in such a safepoint,
 100 // memory access might still occur before the handshake is honored by
 101 // the accessing thread.
 102 //
 103 // Corollary: as threads in native state are considered to be at a safepoint,
 104 // scoped methods must NOT be executed while in the native thread state.
 105 // Because of this, there can be no UNSAFE_LEAF_SCOPED.
 106 #define UNSAFE_ENTRY_SCOPED(result_type, header) \
 107   JVM_ENTRY(static result_type, header) \
 108   if (thread->has_async_exception_condition()) {return (result_type)0;}
 109 
 110 #define UNSAFE_END JVM_END
 111 
 112 
 113 static inline void* addr_from_java(jlong addr) {
 114   // This assert fails in a variety of ways on 32-bit systems.
 115   // It is impossible to predict whether native code that converts
 116   // pointers to longs will sign-extend or zero-extend the addresses.
 117   //assert(addr == (uintptr_t)addr, "must not be odd high bits");
 118   return (void*)(uintptr_t)addr;
 119 }
 120 
 121 static inline jlong addr_to_java(void* p) {
 122   assert(p == (void*)(uintptr_t)p, "must not be odd high bits");
 123   return (uintptr_t)p;
 124 }
 125 
 126 
 127 // Note: The VM's obj_field and related accessors use byte-scaled
 128 // ("unscaled") offsets, just as the unsafe methods do.
 129 
 130 // However, the method Unsafe.fieldOffset explicitly declines to
 131 // guarantee this.  The field offset values manipulated by the Java user
 132 // through the Unsafe API are opaque cookies that just happen to be byte
 133 // offsets.  We represent this state of affairs by passing the cookies
 134 // through conversion functions when going between the VM and the Unsafe API.
 135 // The conversion functions just happen to be no-ops at present.
 136 
 137 static inline jlong field_offset_to_byte_offset(jlong field_offset) {
 138   return field_offset;
 139 }
 140 
 141 static inline int field_offset_from_byte_offset(int byte_offset) {
 142   return byte_offset;
 143 }
 144 
 145 static inline void assert_field_offset_sane(oop p, jlong field_offset) {
 146 #ifdef ASSERT
 147   jlong byte_offset = field_offset_to_byte_offset(field_offset);
 148 
 149   if (p != nullptr) {
 150     assert(byte_offset >= 0 && byte_offset <= (jlong)MAX_OBJECT_SIZE, "sane offset");
 151     if (byte_offset == (jint)byte_offset) {
 152       void* ptr_plus_disp = cast_from_oop<address>(p) + byte_offset;
 153       assert(p->field_addr<void>((jint)byte_offset) == ptr_plus_disp,
 154              "raw [ptr+disp] must be consistent with oop::field_addr");
 155     }
 156     jlong p_size = HeapWordSize * (jlong)(p->size());
 157     assert(byte_offset < p_size, "Unsafe access: offset " INT64_FORMAT " > object's size " INT64_FORMAT, (int64_t)byte_offset, (int64_t)p_size);
 158   }
 159 #endif
 160 }
 161 
 162 static inline void* index_oop_from_field_offset_long(oop p, jlong field_offset) {
 163   assert_field_offset_sane(p, field_offset);
 164   uintptr_t base_address = cast_from_oop<uintptr_t>(p);
 165   uintptr_t byte_offset  = (uintptr_t)field_offset_to_byte_offset(field_offset);
 166   return (void*)(base_address + byte_offset);
 167 }
 168 
 169 // Externally callable versions:
 170 // (Use these in compiler intrinsics which emulate unsafe primitives.)
 171 jlong Unsafe_field_offset_to_byte_offset(jlong field_offset) {
 172   return field_offset;
 173 }
 174 jlong Unsafe_field_offset_from_byte_offset(jlong byte_offset) {
 175   return byte_offset;
 176 }
 177 
 178 ///// Data read/writes on the Java heap and in native (off-heap) memory
 179 
 180 /**
 181  * Helper class to wrap memory accesses in JavaThread::doing_unsafe_access()
 182  */
 183 class GuardUnsafeAccess {
 184   JavaThread* _thread;
 185 
 186 public:
 187   GuardUnsafeAccess(JavaThread* thread) : _thread(thread) {
 188     // native/off-heap access which may raise SIGBUS if accessing
 189     // memory mapped file data in a region of the file which has
 190     // been truncated and is now invalid.
 191     _thread->set_doing_unsafe_access(true);
 192   }
 193 
 194   ~GuardUnsafeAccess() {
 195     _thread->set_doing_unsafe_access(false);
 196   }
 197 };
 198 
 199 /**
 200  * Helper class for accessing memory.
 201  *
 202  * Normalizes values and wraps accesses in
 203  * JavaThread::doing_unsafe_access() if needed.
 204  */
 205 template <typename T>
 206 class MemoryAccess : StackObj {
 207   JavaThread* _thread;
 208   oop _obj;
 209   ptrdiff_t _offset;
 210 
 211   // Resolves and returns the address of the memory access.
 212   // This raw memory access may fault, so we make sure it happens within the
 213   // guarded scope by making the access volatile at least. Since the store
 214   // of Thread::set_doing_unsafe_access() is also volatile, these accesses
 215   // can not be reordered by the compiler. Therefore, if the access triggers
 216   // a fault, we will know that Thread::doing_unsafe_access() returns true.
 217   volatile T* addr() {
 218     void* addr = index_oop_from_field_offset_long(_obj, _offset);
 219     return static_cast<volatile T*>(addr);
 220   }
 221 
 222   template <typename U>
 223   U normalize_for_write(U x) {
 224     return x;
 225   }
 226 
 227   jboolean normalize_for_write(jboolean x) {
 228     return x & 1;
 229   }
 230 
 231   template <typename U>
 232   U normalize_for_read(U x) {
 233     return x;
 234   }
 235 
 236   jboolean normalize_for_read(jboolean x) {
 237     return x != 0;
 238   }
 239 
 240 public:
 241   MemoryAccess(JavaThread* thread, jobject obj, jlong offset)
 242     : _thread(thread), _obj(JNIHandles::resolve(obj)), _offset((ptrdiff_t)offset) {
 243     assert_field_offset_sane(_obj, offset);
 244   }
 245 
 246   T get() {
 247     GuardUnsafeAccess guard(_thread);
 248     return normalize_for_read(*addr());
 249   }
 250 
 251   // we use this method at some places for writing to 0 e.g. to cause a crash;
 252   // ubsan does not know that this is the desired behavior
 253   ATTRIBUTE_NO_UBSAN
 254   void put(T x) {
 255     GuardUnsafeAccess guard(_thread);
 256     assert(_obj == nullptr || !_obj->is_inline_type() || _obj->mark().is_larval_state(), "must be an object instance or a larval inline type");
 257     *addr() = normalize_for_write(x);
 258   }
 259 
 260   T get_volatile() {
 261     GuardUnsafeAccess guard(_thread);
 262     volatile T ret = RawAccess<MO_SEQ_CST>::load(addr());
 263     return normalize_for_read(ret);
 264   }
 265 
 266   void put_volatile(T x) {
 267     GuardUnsafeAccess guard(_thread);
 268     RawAccess<MO_SEQ_CST>::store(addr(), normalize_for_write(x));
 269   }
 270 };
 271 
 272 #ifdef ASSERT
 273 /*
 274  * Get the field descriptor of the field of the given object at the given offset.
 275  */
 276 static bool get_field_descriptor(oop p, jlong offset, fieldDescriptor* fd) {
 277   bool found = false;
 278   Klass* k = p->klass();
 279   if (k->is_instance_klass()) {
 280     InstanceKlass* ik = InstanceKlass::cast(k);
 281     found = ik->find_field_from_offset((int)offset, false, fd);
 282     if (!found && ik->is_mirror_instance_klass()) {
 283       Klass* k2 = java_lang_Class::as_Klass(p);
 284       if (k2->is_instance_klass()) {
 285         ik = InstanceKlass::cast(k2);
 286         found = ik->find_field_from_offset((int)offset, true, fd);
 287       }
 288     }
 289   }
 290   return found;
 291 }
 292 #endif // ASSERT
 293 
 294 static void assert_and_log_unsafe_value_access(oop p, jlong offset, InlineKlass* vk) {
 295   Klass* k = p->klass();
 296 #ifdef ASSERT
 297   if (k->is_instance_klass()) {
 298     assert_field_offset_sane(p, offset);
 299     fieldDescriptor fd;
 300     bool found = get_field_descriptor(p, offset, &fd);
 301     if (found) {
 302       assert(found, "value field not found");
 303       assert(fd.is_flat(), "field not flat");
 304     } else {
 305       if (log_is_enabled(Trace, valuetypes)) {
 306         log_trace(valuetypes)("not a field in %s at offset " UINT64_FORMAT_X,
 307                               p->klass()->external_name(), (uint64_t)offset);
 308       }
 309     }
 310   } else if (k->is_flatArray_klass()) {
 311     FlatArrayKlass* vak = FlatArrayKlass::cast(k);
 312     int index = (offset - vak->array_header_in_bytes()) / vak->element_byte_size();
 313     address dest = (address)((flatArrayOop)p)->value_at_addr(index, vak->layout_helper());
 314     assert(dest == (cast_from_oop<address>(p) + offset), "invalid offset");
 315   } else {
 316     ShouldNotReachHere();
 317   }
 318 #endif // ASSERT
 319   if (log_is_enabled(Trace, valuetypes)) {
 320     if (k->is_flatArray_klass()) {
 321       FlatArrayKlass* vak = FlatArrayKlass::cast(k);
 322       int index = (offset - vak->array_header_in_bytes()) / vak->element_byte_size();
 323       address dest = (address)((flatArrayOop)p)->value_at_addr(index, vak->layout_helper());
 324       log_trace(valuetypes)("%s array type %s index %d element size %d offset " UINT64_FORMAT_X " at " INTPTR_FORMAT,
 325                             p->klass()->external_name(), vak->external_name(),
 326                             index, vak->element_byte_size(), (uint64_t)offset, p2i(dest));
 327     } else {
 328       log_trace(valuetypes)("%s field type %s at offset " UINT64_FORMAT_X,
 329                             p->klass()->external_name(), vk->external_name(), (uint64_t)offset);
 330     }
 331   }
 332 }
 333 
 334 // These functions allow a null base pointer with an arbitrary address.
 335 // But if the base pointer is non-null, the offset should make some sense.
 336 // That is, it should be in the range [0, MAX_OBJECT_SIZE].
 337 UNSAFE_ENTRY(jobject, Unsafe_GetReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
 338   oop p = JNIHandles::resolve(obj);
 339   assert_field_offset_sane(p, offset);
 340   oop v = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_load_at(p, offset);
 341   return JNIHandles::make_local(THREAD, v);
 342 } UNSAFE_END
 343 
 344 UNSAFE_ENTRY(void, Unsafe_PutReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
 345   oop x = JNIHandles::resolve(x_h);
 346   oop p = JNIHandles::resolve(obj);
 347   assert_field_offset_sane(p, offset);
 348   assert(!p->is_inline_type() || p->mark().is_larval_state(), "must be an object instance or a larval inline type");
 349   HeapAccess<ON_UNKNOWN_OOP_REF>::oop_store_at(p, offset, x);
 350 } UNSAFE_END
 351 
 352 UNSAFE_ENTRY(jlong, Unsafe_ValueHeaderSize(JNIEnv *env, jobject unsafe, jclass c)) {
 353   Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(c));
 354   InlineKlass* vk = InlineKlass::cast(k);
 355   return vk->payload_offset();
 356 } UNSAFE_END
 357 
 358 UNSAFE_ENTRY(jboolean, Unsafe_IsFlatField(JNIEnv *env, jobject unsafe, jobject o)) {
 359   oop f = JNIHandles::resolve_non_null(o);
 360   Klass* k = java_lang_Class::as_Klass(java_lang_reflect_Field::clazz(f));
 361   int slot = java_lang_reflect_Field::slot(f);
 362   return InstanceKlass::cast(k)->field_is_flat(slot);
 363 } UNSAFE_END
 364 
 365 UNSAFE_ENTRY(jboolean, Unsafe_HasNullMarker(JNIEnv *env, jobject unsafe, jobject o)) {
 366   oop f = JNIHandles::resolve_non_null(o);
 367   Klass* k = java_lang_Class::as_Klass(java_lang_reflect_Field::clazz(f));
 368   int slot = java_lang_reflect_Field::slot(f);
 369   return InstanceKlass::cast(k)->field_has_null_marker(slot);
 370 } UNSAFE_END
 371 
 372 UNSAFE_ENTRY(jint, Unsafe_NullMarkerOffset(JNIEnv *env, jobject unsafe, jobject o)) {
 373   oop f = JNIHandles::resolve_non_null(o);
 374   Klass* k = java_lang_Class::as_Klass(java_lang_reflect_Field::clazz(f));
 375   int slot = java_lang_reflect_Field::slot(f);
 376   return InstanceKlass::cast(k)->null_marker_offset(slot);
 377 } UNSAFE_END
 378 
 379 UNSAFE_ENTRY(jint, Unsafe_ArrayLayout(JNIEnv *env, jobject unsafe, jarray array)) {
 380   oop ar = JNIHandles::resolve_non_null(array);
 381   ArrayKlass* ak = ArrayKlass::cast(ar->klass());
 382   if (ak->is_refArray_klass()) {
 383     return (jint)LayoutKind::REFERENCE;
 384   } else if (ak->is_flatArray_klass()) {
 385     return (jint)FlatArrayKlass::cast(ak)->layout_kind();
 386   } else {
 387     ShouldNotReachHere();
 388     return -1;
 389   }
 390 } UNSAFE_END
 391 
 392 UNSAFE_ENTRY(jint, Unsafe_FieldLayout(JNIEnv *env, jobject unsafe, jobject field)) {
 393   assert(field != nullptr, "field must not be null");
 394 
 395   oop reflected   = JNIHandles::resolve_non_null(field);
 396   oop mirror      = java_lang_reflect_Field::clazz(reflected);
 397   Klass* k        = java_lang_Class::as_Klass(mirror);
 398   int slot        = java_lang_reflect_Field::slot(reflected);
 399   int modifiers   = java_lang_reflect_Field::modifiers(reflected);
 400 
 401   if ((modifiers & JVM_ACC_STATIC) != 0) {
 402     return (jint)LayoutKind::REFERENCE; // static fields are never flat
 403   } else {
 404     InstanceKlass* ik = InstanceKlass::cast(k);
 405     if (ik->field_is_flat(slot)) {
 406       return (jint)ik->inline_layout_info(slot).kind();
 407     } else {
 408       return (jint)LayoutKind::REFERENCE;
 409     }
 410   }
 411 } UNSAFE_END
 412 
 413 UNSAFE_ENTRY(jarray, Unsafe_NewSpecialArray(JNIEnv *env, jobject unsafe, jclass elmClass, jint len, jint layoutKind)) {
 414   oop mirror = JNIHandles::resolve_non_null(elmClass);
 415   Klass* klass = java_lang_Class::as_Klass(mirror);
 416   klass->initialize(CHECK_NULL);
 417   if (len < 0) {
 418     THROW_MSG_NULL(vmSymbols::java_lang_IllegalArgumentException(), "Array length is negative");
 419   }
 420   if (klass->is_array_klass() || klass->is_identity_class()) {
 421     THROW_MSG_NULL(vmSymbols::java_lang_IllegalArgumentException(), "Element class is not a value class");
 422   }
 423   if (klass->is_abstract()) {
 424     THROW_MSG_NULL(vmSymbols::java_lang_IllegalArgumentException(), "Element class is abstract");
 425   }
 426   LayoutKind lk = static_cast<LayoutKind>(layoutKind);
 427   if (lk <= LayoutKind::REFERENCE || lk >= LayoutKind::UNKNOWN) {
 428     THROW_MSG_NULL(vmSymbols::java_lang_IllegalArgumentException(), "Invalid layout kind");
 429   }
 430   InlineKlass* vk = InlineKlass::cast(klass);
 431   // WARNING: test below will need modifications when flat layouts supported for fields
 432   // but not for arrays are introduce (NULLABLE_NON_ATOMIC_FLAT for instance)
 433   if (!UseArrayFlattening || !vk->is_layout_supported(lk)) {
 434     THROW_MSG_NULL(vmSymbols::java_lang_UnsupportedOperationException(), "Layout not supported");
 435   }
 436   ArrayKlass::ArrayProperties props = ArrayKlass::ArrayProperties::DEFAULT;
 437   switch(lk) {
 438     case LayoutKind::ATOMIC_FLAT:
 439       props = ArrayKlass::ArrayProperties::NULL_RESTRICTED;
 440     break;
 441     case LayoutKind::NON_ATOMIC_FLAT:
 442       props = (ArrayKlass::ArrayProperties)(ArrayKlass::ArrayProperties::NULL_RESTRICTED | ArrayKlass::ArrayProperties::NON_ATOMIC);
 443     break;
 444     case LayoutKind::NULLABLE_ATOMIC_FLAT:
 445     props = ArrayKlass::ArrayProperties::NON_ATOMIC;
 446     break;
 447     default:
 448       ShouldNotReachHere();
 449   }
 450   oop array = oopFactory::new_flatArray(vk, len, props, lk, CHECK_NULL);
 451   return (jarray) JNIHandles::make_local(THREAD, array);
 452 } UNSAFE_END
 453 
 454 UNSAFE_ENTRY(jobject, Unsafe_GetValue(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jclass vc)) {
 455   oop base = JNIHandles::resolve(obj);
 456   if (base == nullptr) {
 457     THROW_NULL(vmSymbols::java_lang_NullPointerException());
 458   }
 459   Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(vc));
 460   InlineKlass* vk = InlineKlass::cast(k);
 461   assert_and_log_unsafe_value_access(base, offset, vk);
 462   LayoutKind lk = LayoutKind::UNKNOWN;
 463   if (base->is_array()) {
 464     FlatArrayKlass* fak = FlatArrayKlass::cast(base->klass());
 465     lk = fak->layout_kind();
 466   } else {
 467     fieldDescriptor fd;
 468     InstanceKlass::cast(base->klass())->find_field_from_offset(offset, false, &fd);
 469     lk = fd.field_holder()->inline_layout_info(fd.index()).kind();
 470   }
 471   Handle base_h(THREAD, base);
 472   oop v = vk->read_payload_from_addr(base_h(), offset, lk, CHECK_NULL);
 473   return JNIHandles::make_local(THREAD, v);
 474 } UNSAFE_END
 475 
 476 UNSAFE_ENTRY(jobject, Unsafe_GetFlatValue(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint layoutKind, jclass vc)) {
 477   assert(layoutKind != (int)LayoutKind::REFERENCE, "This method handles only flat layouts");
 478   oop base = JNIHandles::resolve(obj);
 479   if (base == nullptr) {
 480     THROW_NULL(vmSymbols::java_lang_NullPointerException());
 481   }
 482   Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(vc));
 483   InlineKlass* vk = InlineKlass::cast(k);
 484   assert_and_log_unsafe_value_access(base, offset, vk);
 485   LayoutKind lk = (LayoutKind)layoutKind;
 486   Handle base_h(THREAD, base);
 487   oop v = vk->read_payload_from_addr(base_h(), offset, lk, CHECK_NULL);
 488   return JNIHandles::make_local(THREAD, v);
 489 } UNSAFE_END
 490 
 491 UNSAFE_ENTRY(void, Unsafe_PutValue(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jclass vc, jobject value)) {
 492   oop base = JNIHandles::resolve(obj);
 493   if (base == nullptr) {
 494     THROW(vmSymbols::java_lang_NullPointerException());
 495   }
 496   Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(vc));
 497   InlineKlass* vk = InlineKlass::cast(k);
 498   assert(!base->is_inline_type() || base->mark().is_larval_state(), "must be an object instance or a larval inline type");
 499   assert_and_log_unsafe_value_access(base, offset, vk);
 500   LayoutKind lk = LayoutKind::UNKNOWN;
 501   if (base->is_array()) {
 502     FlatArrayKlass* fak = FlatArrayKlass::cast(base->klass());
 503     lk = fak->layout_kind();
 504   } else {
 505     fieldDescriptor fd;
 506     InstanceKlass::cast(base->klass())->find_field_from_offset(offset, false, &fd);
 507     lk = fd.field_holder()->inline_layout_info(fd.index()).kind();
 508   }
 509   oop v = JNIHandles::resolve(value);
 510   vk->write_value_to_addr(v, ((char*)(oopDesc*)base) + offset, lk, true, CHECK);
 511 } UNSAFE_END
 512 
 513 UNSAFE_ENTRY(void, Unsafe_PutFlatValue(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint layoutKind, jclass vc, jobject value)) {
 514   assert(layoutKind != (int)LayoutKind::REFERENCE, "This method handles only flat layouts");
 515   oop base = JNIHandles::resolve(obj);
 516   if (base == nullptr) {
 517     THROW(vmSymbols::java_lang_NullPointerException());
 518   }
 519   Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(vc));
 520   InlineKlass* vk = InlineKlass::cast(k);
 521   assert(!base->is_inline_type() || base->mark().is_larval_state(), "must be an object instance or a larval inline type");
 522   assert_and_log_unsafe_value_access(base, offset, vk);
 523   LayoutKind lk = (LayoutKind)layoutKind;
 524   oop v = JNIHandles::resolve(value);
 525   vk->write_value_to_addr(v, ((char*)(oopDesc*)base) + offset, lk, true, CHECK);
 526 } UNSAFE_END
 527 
 528 UNSAFE_ENTRY(jobject, Unsafe_MakePrivateBuffer(JNIEnv *env, jobject unsafe, jobject value)) {
 529   oop v = JNIHandles::resolve_non_null(value);
 530   assert(v->is_inline_type(), "must be an inline type instance");
 531   Handle vh(THREAD, v);
 532   InlineKlass* vk = InlineKlass::cast(v->klass());
 533   instanceOop new_value = vk->allocate_instance_buffer(CHECK_NULL);
 534   vk->copy_payload_to_addr(vk->payload_addr(vh()), vk->payload_addr(new_value), LayoutKind::BUFFERED, false);
 535   markWord mark = new_value->mark();
 536   new_value->set_mark(mark.enter_larval_state());
 537   return JNIHandles::make_local(THREAD, new_value);
 538 } UNSAFE_END
 539 
 540 UNSAFE_ENTRY(jobject, Unsafe_FinishPrivateBuffer(JNIEnv *env, jobject unsafe, jobject value)) {
 541   oop v = JNIHandles::resolve(value);
 542   assert(v->mark().is_larval_state(), "must be a larval value");
 543   markWord mark = v->mark();
 544   v->set_mark(mark.exit_larval_state());
 545   return JNIHandles::make_local(THREAD, v);
 546 } UNSAFE_END
 547 
 548 UNSAFE_ENTRY(jobject, Unsafe_GetReferenceVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
 549   oop p = JNIHandles::resolve(obj);
 550   assert_field_offset_sane(p, offset);
 551   oop v = HeapAccess<MO_SEQ_CST | ON_UNKNOWN_OOP_REF>::oop_load_at(p, offset);
 552   return JNIHandles::make_local(THREAD, v);
 553 } UNSAFE_END
 554 
 555 UNSAFE_ENTRY(void, Unsafe_PutReferenceVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
 556   oop x = JNIHandles::resolve(x_h);
 557   oop p = JNIHandles::resolve(obj);
 558   assert_field_offset_sane(p, offset);
 559   HeapAccess<MO_SEQ_CST | ON_UNKNOWN_OOP_REF>::oop_store_at(p, offset, x);
 560 } UNSAFE_END
 561 
 562 UNSAFE_ENTRY(jobject, Unsafe_GetUncompressedObject(JNIEnv *env, jobject unsafe, jlong addr)) {
 563   oop v = *(oop*) (address) addr;
 564   return JNIHandles::make_local(THREAD, v);
 565 } UNSAFE_END
 566 
 567 #define DEFINE_GETSETOOP(java_type, Type) \
 568  \
 569 UNSAFE_ENTRY_SCOPED(java_type, Unsafe_Get##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
 570   return MemoryAccess<java_type>(thread, obj, offset).get(); \
 571 } UNSAFE_END \
 572  \
 573 UNSAFE_ENTRY_SCOPED(void, Unsafe_Put##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
 574   MemoryAccess<java_type>(thread, obj, offset).put(x); \
 575 } UNSAFE_END \
 576  \
 577 // END DEFINE_GETSETOOP.
 578 
 579 DEFINE_GETSETOOP(jboolean, Boolean)
 580 DEFINE_GETSETOOP(jbyte, Byte)
 581 DEFINE_GETSETOOP(jshort, Short);
 582 DEFINE_GETSETOOP(jchar, Char);
 583 DEFINE_GETSETOOP(jint, Int);
 584 DEFINE_GETSETOOP(jlong, Long);
 585 DEFINE_GETSETOOP(jfloat, Float);
 586 DEFINE_GETSETOOP(jdouble, Double);
 587 
 588 #undef DEFINE_GETSETOOP
 589 
 590 #define DEFINE_GETSETOOP_VOLATILE(java_type, Type) \
 591  \
 592 UNSAFE_ENTRY_SCOPED(java_type, Unsafe_Get##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
 593   return MemoryAccess<java_type>(thread, obj, offset).get_volatile(); \
 594 } UNSAFE_END \
 595  \
 596 UNSAFE_ENTRY_SCOPED(void, Unsafe_Put##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
 597   MemoryAccess<java_type>(thread, obj, offset).put_volatile(x); \
 598 } UNSAFE_END \
 599  \
 600 // END DEFINE_GETSETOOP_VOLATILE.
 601 
 602 DEFINE_GETSETOOP_VOLATILE(jboolean, Boolean)
 603 DEFINE_GETSETOOP_VOLATILE(jbyte, Byte)
 604 DEFINE_GETSETOOP_VOLATILE(jshort, Short);
 605 DEFINE_GETSETOOP_VOLATILE(jchar, Char);
 606 DEFINE_GETSETOOP_VOLATILE(jint, Int);
 607 DEFINE_GETSETOOP_VOLATILE(jlong, Long);
 608 DEFINE_GETSETOOP_VOLATILE(jfloat, Float);
 609 DEFINE_GETSETOOP_VOLATILE(jdouble, Double);
 610 
 611 #undef DEFINE_GETSETOOP_VOLATILE
 612 
 613 UNSAFE_LEAF(void, Unsafe_FullFence(JNIEnv *env, jobject unsafe)) {
 614   OrderAccess::fence();
 615 } UNSAFE_END
 616 
 617 ////// Allocation requests
 618 
 619 UNSAFE_ENTRY(jobject, Unsafe_AllocateInstance(JNIEnv *env, jobject unsafe, jclass cls)) {
 620   JvmtiVMObjectAllocEventCollector oam;
 621   instanceOop i = InstanceKlass::allocate_instance(JNIHandles::resolve_non_null(cls), CHECK_NULL);
 622   return JNIHandles::make_local(THREAD, i);
 623 } UNSAFE_END
 624 
 625 UNSAFE_LEAF(jlong, Unsafe_AllocateMemory0(JNIEnv *env, jobject unsafe, jlong size)) {
 626   size_t sz = (size_t)size;
 627 
 628   assert(is_aligned(sz, HeapWordSize), "sz not aligned");
 629 
 630   void* x = os::malloc(sz, mtOther);
 631 
 632   return addr_to_java(x);
 633 } UNSAFE_END
 634 
 635 UNSAFE_LEAF(jlong, Unsafe_ReallocateMemory0(JNIEnv *env, jobject unsafe, jlong addr, jlong size)) {
 636   void* p = addr_from_java(addr);
 637   size_t sz = (size_t)size;
 638 
 639   assert(is_aligned(sz, HeapWordSize), "sz not aligned");
 640 
 641   void* x = os::realloc(p, sz, mtOther);
 642 
 643   return addr_to_java(x);
 644 } UNSAFE_END
 645 
 646 UNSAFE_LEAF(void, Unsafe_FreeMemory0(JNIEnv *env, jobject unsafe, jlong addr)) {
 647   void* p = addr_from_java(addr);
 648 
 649   os::free(p);
 650 } UNSAFE_END
 651 
 652 UNSAFE_ENTRY_SCOPED(void, Unsafe_SetMemory0(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong size, jbyte value)) {
 653   size_t sz = (size_t)size;
 654 
 655   oop base = JNIHandles::resolve(obj);
 656   void* p = index_oop_from_field_offset_long(base, offset);
 657 
 658   {
 659     GuardUnsafeAccess guard(thread);
 660     if (StubRoutines::unsafe_setmemory() != nullptr) {
 661       MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXExec, thread));
 662       StubRoutines::UnsafeSetMemory_stub()(p, sz, value);
 663     } else {
 664       Copy::fill_to_memory_atomic(p, sz, value);
 665     }
 666   }
 667 } UNSAFE_END
 668 
 669 UNSAFE_ENTRY_SCOPED(void, Unsafe_CopyMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size)) {
 670   size_t sz = (size_t)size;
 671 
 672   oop srcp = JNIHandles::resolve(srcObj);
 673   oop dstp = JNIHandles::resolve(dstObj);
 674 
 675   void* src = index_oop_from_field_offset_long(srcp, srcOffset);
 676   void* dst = index_oop_from_field_offset_long(dstp, dstOffset);
 677   {
 678     GuardUnsafeAccess guard(thread);
 679     if (StubRoutines::unsafe_arraycopy() != nullptr) {
 680       MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXExec, thread));
 681       StubRoutines::UnsafeArrayCopy_stub()(src, dst, sz);
 682     } else {
 683       Copy::conjoint_memory_atomic(src, dst, sz);
 684     }
 685   }
 686 } UNSAFE_END
 687 
 688 UNSAFE_ENTRY_SCOPED(void, Unsafe_CopySwapMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size, jlong elemSize)) {
 689   size_t sz = (size_t)size;
 690   size_t esz = (size_t)elemSize;
 691 
 692   oop srcp = JNIHandles::resolve(srcObj);
 693   oop dstp = JNIHandles::resolve(dstObj);
 694 
 695   address src = (address)index_oop_from_field_offset_long(srcp, srcOffset);
 696   address dst = (address)index_oop_from_field_offset_long(dstp, dstOffset);
 697 
 698   {
 699     GuardUnsafeAccess guard(thread);
 700     Copy::conjoint_swap(src, dst, sz, esz);
 701   }
 702 } UNSAFE_END
 703 
 704 UNSAFE_LEAF (void, Unsafe_WriteBack0(JNIEnv *env, jobject unsafe, jlong line)) {
 705   assert(VM_Version::supports_data_cache_line_flush(), "should not get here");
 706 #ifdef ASSERT
 707   if (TraceMemoryWriteback) {
 708     tty->print_cr("Unsafe: writeback 0x%p", addr_from_java(line));
 709   }
 710 #endif
 711 
 712   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXExec, Thread::current()));
 713   assert(StubRoutines::data_cache_writeback() != nullptr, "sanity");
 714   (StubRoutines::DataCacheWriteback_stub())(addr_from_java(line));
 715 } UNSAFE_END
 716 
 717 static void doWriteBackSync0(bool is_pre)
 718 {
 719   MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXExec, Thread::current()));
 720   assert(StubRoutines::data_cache_writeback_sync() != nullptr, "sanity");
 721   (StubRoutines::DataCacheWritebackSync_stub())(is_pre);
 722 }
 723 
 724 UNSAFE_LEAF (void, Unsafe_WriteBackPreSync0(JNIEnv *env, jobject unsafe)) {
 725   assert(VM_Version::supports_data_cache_line_flush(), "should not get here");
 726 #ifdef ASSERT
 727   if (TraceMemoryWriteback) {
 728       tty->print_cr("Unsafe: writeback pre-sync");
 729   }
 730 #endif
 731 
 732   doWriteBackSync0(true);
 733 } UNSAFE_END
 734 
 735 UNSAFE_LEAF (void, Unsafe_WriteBackPostSync0(JNIEnv *env, jobject unsafe)) {
 736   assert(VM_Version::supports_data_cache_line_flush(), "should not get here");
 737 #ifdef ASSERT
 738   if (TraceMemoryWriteback) {
 739     tty->print_cr("Unsafe: writeback pre-sync");
 740   }
 741 #endif
 742 
 743   doWriteBackSync0(false);
 744 } UNSAFE_END
 745 
 746 ////// Random queries
 747 
 748 // Finds the object field offset of a field with the matching name, or an error code
 749 // Error code -1 is not found, -2 is static field
 750 static jlong find_known_instance_field_offset(jclass clazz, jstring name, TRAPS) {
 751   assert(clazz != nullptr, "clazz must not be null");
 752   assert(name != nullptr, "name must not be null");
 753 
 754   ResourceMark rm(THREAD);
 755   char *utf_name = java_lang_String::as_utf8_string(JNIHandles::resolve_non_null(name));
 756 
 757   InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(JNIHandles::resolve_non_null(clazz)));
 758 
 759   jint offset = -1; // Not found
 760   for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
 761     Symbol *name = fs.name();
 762     if (name->equals(utf_name)) {
 763       if (!fs.access_flags().is_static()) {
 764         offset = fs.offset();
 765       } else {
 766         offset = -2; // A static field
 767       }
 768       break;
 769     }
 770   }
 771   if (offset < 0) {
 772     return offset; // Error code
 773   }
 774   return field_offset_from_byte_offset(offset);
 775 }
 776 
 777 static jlong find_field_offset(jobject field, int must_be_static, TRAPS) {
 778   assert(field != nullptr, "field must not be null");
 779 
 780   oop reflected   = JNIHandles::resolve_non_null(field);
 781   oop mirror      = java_lang_reflect_Field::clazz(reflected);
 782   Klass* k        = java_lang_Class::as_Klass(mirror);
 783   int slot        = java_lang_reflect_Field::slot(reflected);
 784   int modifiers   = java_lang_reflect_Field::modifiers(reflected);
 785 
 786   if (must_be_static >= 0) {
 787     int really_is_static = ((modifiers & JVM_ACC_STATIC) != 0);
 788     if (must_be_static != really_is_static) {
 789       THROW_0(vmSymbols::java_lang_IllegalArgumentException());
 790     }
 791   }
 792 
 793   int offset = InstanceKlass::cast(k)->field_offset(slot);
 794   return field_offset_from_byte_offset(offset);
 795 }
 796 
 797 UNSAFE_ENTRY(jlong, Unsafe_ObjectFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
 798   return find_field_offset(field, 0, THREAD);
 799 } UNSAFE_END
 800 
 801 UNSAFE_ENTRY(jlong, Unsafe_KnownObjectFieldOffset0(JNIEnv *env, jobject unsafe, jclass c, jstring name)) {
 802   return find_known_instance_field_offset(c, name, THREAD);
 803 } UNSAFE_END
 804 
 805 UNSAFE_ENTRY(jlong, Unsafe_StaticFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
 806   return find_field_offset(field, 1, THREAD);
 807 } UNSAFE_END
 808 
 809 UNSAFE_ENTRY(jobject, Unsafe_StaticFieldBase0(JNIEnv *env, jobject unsafe, jobject field)) {
 810   assert(field != nullptr, "field must not be null");
 811 
 812   // Note:  In this VM implementation, a field address is always a short
 813   // offset from the base of a klass metaobject.  Thus, the full dynamic
 814   // range of the return type is never used.  However, some implementations
 815   // might put the static field inside an array shared by many classes,
 816   // or even at a fixed address, in which case the address could be quite
 817   // large.  In that last case, this function would return null, since
 818   // the address would operate alone, without any base pointer.
 819 
 820   oop reflected   = JNIHandles::resolve_non_null(field);
 821   oop mirror      = java_lang_reflect_Field::clazz(reflected);
 822   int modifiers   = java_lang_reflect_Field::modifiers(reflected);
 823 
 824   if ((modifiers & JVM_ACC_STATIC) == 0) {
 825     THROW_NULL(vmSymbols::java_lang_IllegalArgumentException());
 826   }
 827 
 828   return JNIHandles::make_local(THREAD, mirror);
 829 } UNSAFE_END
 830 
 831 UNSAFE_ENTRY(void, Unsafe_EnsureClassInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
 832   assert(clazz != nullptr, "clazz must not be null");
 833 
 834   oop mirror = JNIHandles::resolve_non_null(clazz);
 835 
 836   Klass* klass = java_lang_Class::as_Klass(mirror);
 837   if (klass != nullptr && klass->should_be_initialized()) {
 838     InstanceKlass* k = InstanceKlass::cast(klass);
 839     k->initialize(CHECK);
 840   }
 841 }
 842 UNSAFE_END
 843 
 844 UNSAFE_ENTRY(jboolean, Unsafe_ShouldBeInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
 845   assert(clazz != nullptr, "clazz must not be null");
 846 
 847   oop mirror = JNIHandles::resolve_non_null(clazz);
 848   Klass* klass = java_lang_Class::as_Klass(mirror);
 849 
 850   if (klass != nullptr && klass->should_be_initialized()) {
 851     return true;
 852   }
 853 
 854   return false;
 855 }
 856 UNSAFE_END
 857 
 858 UNSAFE_ENTRY(void, Unsafe_NotifyStrictStaticAccess0(JNIEnv *env, jobject unsafe, jobject clazz,
 859                                                     jlong sfoffset, jboolean writing)) {
 860   assert(clazz != nullptr, "clazz must not be null");
 861 
 862   oop mirror = JNIHandles::resolve_non_null(clazz);
 863   Klass* klass = java_lang_Class::as_Klass(mirror);
 864 
 865   if (klass != nullptr && klass->is_instance_klass()) {
 866     InstanceKlass* ik = InstanceKlass::cast(klass);
 867     fieldDescriptor fd;
 868     if (ik->find_local_field_from_offset((int)sfoffset, true, &fd)) {
 869       // Note: The Unsafe API takes an OFFSET, but the InstanceKlass wants the INDEX.
 870       // We could surface field indexes into Unsafe, but that's too much churn.
 871       ik->notify_strict_static_access(fd.index(), writing, CHECK);
 872       return;
 873     }
 874   }
 875   THROW(vmSymbols::java_lang_InternalError());
 876 }
 877 UNSAFE_END
 878 
 879 static void getBaseAndScale(int& base, int& scale, jclass clazz, TRAPS) {
 880   assert(clazz != nullptr, "clazz must not be null");
 881 
 882   oop mirror = JNIHandles::resolve_non_null(clazz);
 883   Klass* k = java_lang_Class::as_Klass(mirror);
 884 
 885   if (k == nullptr || !k->is_array_klass()) {
 886     THROW(vmSymbols::java_lang_InvalidClassException());
 887   } else if (k->is_typeArray_klass()) {
 888     TypeArrayKlass* tak = TypeArrayKlass::cast(k);
 889     base  = tak->array_header_in_bytes();
 890     assert(base == arrayOopDesc::base_offset_in_bytes(tak->element_type()), "array_header_size semantics ok");
 891     scale = (1 << tak->log2_element_size());
 892   } else if (k->is_objArray_klass()) {
 893     Klass* ek = ObjArrayKlass::cast(k)->element_klass();
 894     if (!ek->is_identity_class() && !ek->is_abstract()) {
 895       // Arrays of a concrete value class type can have multiple layouts
 896       // There's no good value to return, so throwing an exception is the way out
 897       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "Arrays of a concrete value class don't have a single base and offset");
 898     }
 899     base  = arrayOopDesc::base_offset_in_bytes(T_OBJECT);
 900     scale = heapOopSize;
 901   } else {
 902     ShouldNotReachHere();
 903   }
 904 }
 905 
 906 UNSAFE_ENTRY(jint, Unsafe_ArrayBaseOffset1(JNIEnv *env, jobject unsafe, jarray array)) {
 907   assert(array != nullptr, "array must not be null");
 908   oop ar = JNIHandles::resolve_non_null(array);
 909   assert(ar->is_array(), "Must be an array");
 910   ArrayKlass* ak = ArrayKlass::cast(ar->klass());
 911   if (ak->is_refArray_klass()) {
 912     return arrayOopDesc::base_offset_in_bytes(T_OBJECT);
 913   } else if (ak->is_flatArray_klass()) {
 914     FlatArrayKlass* fak = FlatArrayKlass::cast(ak);
 915     return fak->array_header_in_bytes();
 916   } else {
 917     ShouldNotReachHere();
 918   }
 919 } UNSAFE_END
 920 
 921 UNSAFE_ENTRY(jint, Unsafe_ArrayBaseOffset0(JNIEnv *env, jobject unsafe, jclass clazz)) {
 922   int base = 0, scale = 0;
 923   getBaseAndScale(base, scale, clazz, CHECK_0);
 924 
 925   return field_offset_from_byte_offset(base);
 926 } UNSAFE_END
 927 
 928 
 929 UNSAFE_ENTRY(jint, Unsafe_ArrayIndexScale0(JNIEnv *env, jobject unsafe, jclass clazz)) {
 930   int base = 0, scale = 0;
 931   getBaseAndScale(base, scale, clazz, CHECK_0);
 932 
 933   // This VM packs both fields and array elements down to the byte.
 934   // But watch out:  If this changes, so that array references for
 935   // a given primitive type (say, T_BOOLEAN) use different memory units
 936   // than fields, this method MUST return zero for such arrays.
 937   // For example, the VM used to store sub-word sized fields in full
 938   // words in the object layout, so that accessors like getByte(Object,int)
 939   // did not really do what one might expect for arrays.  Therefore,
 940   // this function used to report a zero scale factor, so that the user
 941   // would know not to attempt to access sub-word array elements.
 942   // // Code for unpacked fields:
 943   // if (scale < wordSize)  return 0;
 944 
 945   // The following allows for a pretty general fieldOffset cookie scheme,
 946   // but requires it to be linear in byte offset.
 947   return field_offset_from_byte_offset(scale) - field_offset_from_byte_offset(0);
 948 } UNSAFE_END
 949 
 950 UNSAFE_ENTRY(jint, Unsafe_ArrayIndexScale1(JNIEnv *env, jobject unsafe, jarray array)) {
 951   assert(array != nullptr, "array must not be null");
 952   oop ar = JNIHandles::resolve_non_null(array);
 953   assert(ar->is_array(), "Must be an array");
 954   ArrayKlass* ak = ArrayKlass::cast(ar->klass());
 955   if (ak->is_refArray_klass()) {
 956     return heapOopSize;
 957   } else if (ak->is_flatArray_klass()) {
 958     FlatArrayKlass* fak = FlatArrayKlass::cast(ak);
 959     return fak->element_byte_size();
 960   } else {
 961     ShouldNotReachHere();
 962   }
 963 } UNSAFE_END
 964 
 965 UNSAFE_ENTRY(jlong, Unsafe_GetObjectSize0(JNIEnv* env, jobject o, jobject obj))
 966   oop p = JNIHandles::resolve(obj);
 967   return p->size() * HeapWordSize;
 968 UNSAFE_END
 969 
 970 
 971 static inline void throw_new(JNIEnv *env, const char *ename) {
 972   jclass cls = env->FindClass(ename);
 973   if (env->ExceptionCheck()) {
 974     env->ExceptionClear();
 975     tty->print_cr("Unsafe: cannot throw %s because FindClass has failed", ename);
 976     return;
 977   }
 978 
 979   env->ThrowNew(cls, nullptr);
 980 }
 981 
 982 static jclass Unsafe_DefineClass_impl(JNIEnv *env, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd) {
 983   // Code lifted from JDK 1.3 ClassLoader.c
 984 
 985   jbyte *body;
 986   char *utfName = nullptr;
 987   jclass result = nullptr;
 988   char buf[128];
 989 
 990   assert(data != nullptr, "Class bytes must not be null");
 991   assert(length >= 0, "length must not be negative: %d", length);
 992 
 993   if (UsePerfData) {
 994     ClassLoader::unsafe_defineClassCallCounter()->inc();
 995   }
 996 
 997   body = NEW_C_HEAP_ARRAY_RETURN_NULL(jbyte, length, mtInternal);
 998   if (body == nullptr) {
 999     throw_new(env, "java/lang/OutOfMemoryError");
1000     return nullptr;
1001   }
1002 
1003   env->GetByteArrayRegion(data, offset, length, body);
1004   if (env->ExceptionCheck()) {
1005     goto free_body;
1006   }
1007 
1008   if (name != nullptr) {
1009     uint len = env->GetStringUTFLength(name);
1010     int unicode_len = env->GetStringLength(name);
1011 
1012     if (len >= sizeof(buf)) {
1013       utfName = NEW_C_HEAP_ARRAY_RETURN_NULL(char, len + 1, mtInternal);
1014       if (utfName == nullptr) {
1015         throw_new(env, "java/lang/OutOfMemoryError");
1016         goto free_body;
1017       }
1018     } else {
1019       utfName = buf;
1020     }
1021 
1022     env->GetStringUTFRegion(name, 0, unicode_len, utfName);
1023 
1024     for (uint i = 0; i < len; i++) {
1025       if (utfName[i] == '.')   utfName[i] = '/';
1026     }
1027   }
1028 
1029   result = JVM_DefineClass(env, utfName, loader, body, length, pd);
1030 
1031   if (utfName && utfName != buf) {
1032     FREE_C_HEAP_ARRAY(char, utfName);
1033   }
1034 
1035  free_body:
1036   FREE_C_HEAP_ARRAY(jbyte, body);
1037   return result;
1038 }
1039 
1040 
1041 UNSAFE_ENTRY(jclass, Unsafe_DefineClass0(JNIEnv *env, jobject unsafe, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd)) {
1042   ThreadToNativeFromVM ttnfv(thread);
1043 
1044   return Unsafe_DefineClass_impl(env, name, data, offset, length, loader, pd);
1045 } UNSAFE_END
1046 
1047 
1048 UNSAFE_ENTRY(void, Unsafe_ThrowException(JNIEnv *env, jobject unsafe, jthrowable thr)) {
1049   ThreadToNativeFromVM ttnfv(thread);
1050   env->Throw(thr);
1051 } UNSAFE_END
1052 
1053 // JSR166 ------------------------------------------------------------------
1054 
1055 UNSAFE_ENTRY(jobject, Unsafe_CompareAndExchangeReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
1056   oop x = JNIHandles::resolve(x_h);
1057   oop e = JNIHandles::resolve(e_h);
1058   oop p = JNIHandles::resolve(obj);
1059   assert_field_offset_sane(p, offset);
1060   oop res = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_atomic_cmpxchg_at(p, (ptrdiff_t)offset, e, x);
1061   return JNIHandles::make_local(THREAD, res);
1062 } UNSAFE_END
1063 
1064 UNSAFE_ENTRY_SCOPED(jint, Unsafe_CompareAndExchangeInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
1065   oop p = JNIHandles::resolve(obj);
1066   volatile jint* addr = (volatile jint*)index_oop_from_field_offset_long(p, offset);
1067   return Atomic::cmpxchg(addr, e, x);
1068 } UNSAFE_END
1069 
1070 UNSAFE_ENTRY_SCOPED(jlong, Unsafe_CompareAndExchangeLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
1071   oop p = JNIHandles::resolve(obj);
1072   volatile jlong* addr = (volatile jlong*)index_oop_from_field_offset_long(p, offset);
1073   return Atomic::cmpxchg(addr, e, x);
1074 } UNSAFE_END
1075 
1076 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
1077   oop x = JNIHandles::resolve(x_h);
1078   oop e = JNIHandles::resolve(e_h);
1079   oop p = JNIHandles::resolve(obj);
1080   assert_field_offset_sane(p, offset);
1081   oop ret = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_atomic_cmpxchg_at(p, (ptrdiff_t)offset, e, x);
1082   return ret == e;
1083 } UNSAFE_END
1084 
1085 UNSAFE_ENTRY_SCOPED(jboolean, Unsafe_CompareAndSetInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
1086   oop p = JNIHandles::resolve(obj);
1087   volatile jint* addr = (volatile jint*)index_oop_from_field_offset_long(p, offset);
1088   return Atomic::cmpxchg(addr, e, x) == e;
1089 } UNSAFE_END
1090 
1091 UNSAFE_ENTRY_SCOPED(jboolean, Unsafe_CompareAndSetLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
1092   oop p = JNIHandles::resolve(obj);
1093   volatile jlong* addr = (volatile jlong*)index_oop_from_field_offset_long(p, offset);
1094   return Atomic::cmpxchg(addr, e, x) == e;
1095 } UNSAFE_END
1096 
1097 static void post_thread_park_event(EventThreadPark* event, const oop obj, jlong timeout_nanos, jlong until_epoch_millis) {
1098   assert(event != nullptr, "invariant");
1099   event->set_parkedClass((obj != nullptr) ? obj->klass() : nullptr);
1100   event->set_timeout(timeout_nanos);
1101   event->set_until(until_epoch_millis);
1102   event->set_address((obj != nullptr) ? (u8)cast_from_oop<uintptr_t>(obj) : 0);
1103   event->commit();
1104 }
1105 
1106 UNSAFE_ENTRY(void, Unsafe_Park(JNIEnv *env, jobject unsafe, jboolean isAbsolute, jlong time)) {
1107   HOTSPOT_THREAD_PARK_BEGIN((uintptr_t) thread->parker(), (int) isAbsolute, time);
1108   EventThreadPark event;
1109 
1110   JavaThreadParkedState jtps(thread, time != 0);
1111   thread->parker()->park(isAbsolute != 0, time);
1112   if (event.should_commit()) {
1113     const oop obj = thread->current_park_blocker();
1114     if (time == 0) {
1115       post_thread_park_event(&event, obj, min_jlong, min_jlong);
1116     } else {
1117       if (isAbsolute != 0) {
1118         post_thread_park_event(&event, obj, min_jlong, time);
1119       } else {
1120         post_thread_park_event(&event, obj, time, min_jlong);
1121       }
1122     }
1123   }
1124   HOTSPOT_THREAD_PARK_END((uintptr_t) thread->parker());
1125 } UNSAFE_END
1126 
1127 UNSAFE_ENTRY(void, Unsafe_Unpark(JNIEnv *env, jobject unsafe, jobject jthread)) {
1128   if (jthread != nullptr) {
1129     oop thread_oop = JNIHandles::resolve_non_null(jthread);
1130     // Get the JavaThread* stored in the java.lang.Thread object _before_
1131     // the embedded ThreadsListHandle is constructed so we know if the
1132     // early life stage of the JavaThread* is protected. We use acquire
1133     // here to ensure that if we see a non-nullptr value, then we also
1134     // see the main ThreadsList updates from the JavaThread* being added.
1135     FastThreadsListHandle ftlh(thread_oop, java_lang_Thread::thread_acquire(thread_oop));
1136     JavaThread* thr = ftlh.protected_java_thread();
1137     if (thr != nullptr) {
1138       // The still live JavaThread* is protected by the FastThreadsListHandle
1139       // so it is safe to access.
1140       Parker* p = thr->parker();
1141       HOTSPOT_THREAD_UNPARK((uintptr_t) p);
1142       p->unpark();
1143     }
1144   } // FastThreadsListHandle is destroyed here.
1145 } UNSAFE_END
1146 
1147 UNSAFE_ENTRY(jint, Unsafe_GetLoadAverage0(JNIEnv *env, jobject unsafe, jdoubleArray loadavg, jint nelem)) {
1148   const int max_nelem = 3;
1149   double la[max_nelem];
1150   jint ret;
1151 
1152   typeArrayOop a = typeArrayOop(JNIHandles::resolve_non_null(loadavg));
1153   assert(a->is_typeArray(), "must be type array");
1154 
1155   ret = os::loadavg(la, nelem);
1156   if (ret == -1) {
1157     return -1;
1158   }
1159 
1160   // if successful, ret is the number of samples actually retrieved.
1161   assert(ret >= 0 && ret <= max_nelem, "Unexpected loadavg return value");
1162   switch(ret) {
1163     case 3: a->double_at_put(2, (jdouble)la[2]); // fall through
1164     case 2: a->double_at_put(1, (jdouble)la[1]); // fall through
1165     case 1: a->double_at_put(0, (jdouble)la[0]); break;
1166   }
1167 
1168   return ret;
1169 } UNSAFE_END
1170 
1171 
1172 /// JVM_RegisterUnsafeMethods
1173 
1174 #define ADR "J"
1175 
1176 #define LANG "Ljava/lang/"
1177 
1178 #define OBJ LANG "Object;"
1179 #define CLS LANG "Class;"
1180 #define FLD LANG "reflect/Field;"
1181 #define THR LANG "Throwable;"
1182 
1183 #define OBJ_ARR "[" OBJ
1184 
1185 #define DC_Args  LANG "String;[BII" LANG "ClassLoader;" "Ljava/security/ProtectionDomain;"
1186 #define DAC_Args CLS "[B[" OBJ
1187 
1188 #define CC (char*)  /*cast a literal from (const char*)*/
1189 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
1190 
1191 #define DECLARE_GETPUTOOP(Type, Desc) \
1192     {CC "get"  #Type,      CC "(" OBJ "J)" #Desc,                 FN_PTR(Unsafe_Get##Type)}, \
1193     {CC "put"  #Type,      CC "(" OBJ "J" #Desc ")V",             FN_PTR(Unsafe_Put##Type)}, \
1194     {CC "get"  #Type "Volatile",      CC "(" OBJ "J)" #Desc,      FN_PTR(Unsafe_Get##Type##Volatile)}, \
1195     {CC "put"  #Type "Volatile",      CC "(" OBJ "J" #Desc ")V",  FN_PTR(Unsafe_Put##Type##Volatile)}
1196 
1197 
1198 static JNINativeMethod jdk_internal_misc_Unsafe_methods[] = {
1199     {CC "getReference",         CC "(" OBJ "J)" OBJ "",   FN_PTR(Unsafe_GetReference)},
1200     {CC "putReference",         CC "(" OBJ "J" OBJ ")V",  FN_PTR(Unsafe_PutReference)},
1201     {CC "getReferenceVolatile", CC "(" OBJ "J)" OBJ,      FN_PTR(Unsafe_GetReferenceVolatile)},
1202     {CC "putReferenceVolatile", CC "(" OBJ "J" OBJ ")V",  FN_PTR(Unsafe_PutReferenceVolatile)},
1203 
1204     {CC "isFlatField0",         CC "(" OBJ ")Z",          FN_PTR(Unsafe_IsFlatField)},
1205     {CC "hasNullMarker0",       CC "(" OBJ ")Z",          FN_PTR(Unsafe_HasNullMarker)},
1206     {CC "nullMarkerOffset0",    CC "(" OBJ ")I",          FN_PTR(Unsafe_NullMarkerOffset)},
1207     {CC "arrayLayout0",         CC "(" OBJ_ARR ")I",      FN_PTR(Unsafe_ArrayLayout)},
1208     {CC "fieldLayout0",         CC "(" OBJ ")I",          FN_PTR(Unsafe_FieldLayout)},
1209     {CC "newSpecialArray",      CC "(" CLS "II)[" OBJ,    FN_PTR(Unsafe_NewSpecialArray)},
1210     {CC "getValue",             CC "(" OBJ "J" CLS ")" OBJ, FN_PTR(Unsafe_GetValue)},
1211     {CC "getFlatValue",         CC "(" OBJ "JI" CLS ")" OBJ, FN_PTR(Unsafe_GetFlatValue)},
1212     {CC "putValue",             CC "(" OBJ "J" CLS OBJ ")V", FN_PTR(Unsafe_PutValue)},
1213     {CC "putFlatValue",         CC "(" OBJ "JI" CLS OBJ ")V", FN_PTR(Unsafe_PutFlatValue)},
1214     {CC "makePrivateBuffer",     CC "(" OBJ ")" OBJ,      FN_PTR(Unsafe_MakePrivateBuffer)},
1215     {CC "finishPrivateBuffer",   CC "(" OBJ ")" OBJ,      FN_PTR(Unsafe_FinishPrivateBuffer)},
1216     {CC "valueHeaderSize",       CC "(" CLS ")J",         FN_PTR(Unsafe_ValueHeaderSize)},
1217 
1218     {CC "getUncompressedObject", CC "(" ADR ")" OBJ,  FN_PTR(Unsafe_GetUncompressedObject)},
1219 
1220     DECLARE_GETPUTOOP(Boolean, Z),
1221     DECLARE_GETPUTOOP(Byte, B),
1222     DECLARE_GETPUTOOP(Short, S),
1223     DECLARE_GETPUTOOP(Char, C),
1224     DECLARE_GETPUTOOP(Int, I),
1225     DECLARE_GETPUTOOP(Long, J),
1226     DECLARE_GETPUTOOP(Float, F),
1227     DECLARE_GETPUTOOP(Double, D),
1228 
1229     {CC "allocateMemory0",    CC "(J)" ADR,              FN_PTR(Unsafe_AllocateMemory0)},
1230     {CC "reallocateMemory0",  CC "(" ADR "J)" ADR,       FN_PTR(Unsafe_ReallocateMemory0)},
1231     {CC "freeMemory0",        CC "(" ADR ")V",           FN_PTR(Unsafe_FreeMemory0)},
1232 
1233     {CC "objectFieldOffset0", CC "(" FLD ")J",           FN_PTR(Unsafe_ObjectFieldOffset0)},
1234     {CC "knownObjectFieldOffset0", CC "(" CLS LANG "String;)J", FN_PTR(Unsafe_KnownObjectFieldOffset0)},
1235     {CC "staticFieldOffset0", CC "(" FLD ")J",           FN_PTR(Unsafe_StaticFieldOffset0)},
1236     {CC "staticFieldBase0",   CC "(" FLD ")" OBJ,        FN_PTR(Unsafe_StaticFieldBase0)},
1237     {CC "ensureClassInitialized0", CC "(" CLS ")V",      FN_PTR(Unsafe_EnsureClassInitialized0)},
1238     {CC "arrayBaseOffset0",   CC "(" CLS ")I",           FN_PTR(Unsafe_ArrayBaseOffset0)},
1239     {CC "arrayBaseOffset1",   CC "(" OBJ_ARR ")I",       FN_PTR(Unsafe_ArrayBaseOffset1)},
1240     {CC "arrayIndexScale0",   CC "(" CLS ")I",           FN_PTR(Unsafe_ArrayIndexScale0)},
1241     {CC "arrayIndexScale1",   CC "(" OBJ_ARR ")I",       FN_PTR(Unsafe_ArrayIndexScale1)},
1242     {CC "getObjectSize0",     CC "(Ljava/lang/Object;)J", FN_PTR(Unsafe_GetObjectSize0)},
1243 
1244     {CC "defineClass0",       CC "(" DC_Args ")" CLS,    FN_PTR(Unsafe_DefineClass0)},
1245     {CC "allocateInstance",   CC "(" CLS ")" OBJ,        FN_PTR(Unsafe_AllocateInstance)},
1246     {CC "throwException",     CC "(" THR ")V",           FN_PTR(Unsafe_ThrowException)},
1247     {CC "compareAndSetReference",CC "(" OBJ "J" OBJ "" OBJ ")Z", FN_PTR(Unsafe_CompareAndSetReference)},
1248     {CC "compareAndSetInt",   CC "(" OBJ "J""I""I"")Z",  FN_PTR(Unsafe_CompareAndSetInt)},
1249     {CC "compareAndSetLong",  CC "(" OBJ "J""J""J"")Z",  FN_PTR(Unsafe_CompareAndSetLong)},
1250     {CC "compareAndExchangeReference", CC "(" OBJ "J" OBJ "" OBJ ")" OBJ, FN_PTR(Unsafe_CompareAndExchangeReference)},
1251     {CC "compareAndExchangeInt",  CC "(" OBJ "J""I""I"")I", FN_PTR(Unsafe_CompareAndExchangeInt)},
1252     {CC "compareAndExchangeLong", CC "(" OBJ "J""J""J"")J", FN_PTR(Unsafe_CompareAndExchangeLong)},
1253 
1254     {CC "park",               CC "(ZJ)V",                FN_PTR(Unsafe_Park)},
1255     {CC "unpark",             CC "(" OBJ ")V",           FN_PTR(Unsafe_Unpark)},
1256 
1257     {CC "getLoadAverage0",    CC "([DI)I",               FN_PTR(Unsafe_GetLoadAverage0)},
1258 
1259     {CC "copyMemory0",        CC "(" OBJ "J" OBJ "JJ)V", FN_PTR(Unsafe_CopyMemory0)},
1260     {CC "copySwapMemory0",    CC "(" OBJ "J" OBJ "JJJ)V", FN_PTR(Unsafe_CopySwapMemory0)},
1261     {CC "writeback0",         CC "(" "J" ")V",           FN_PTR(Unsafe_WriteBack0)},
1262     {CC "writebackPreSync0",  CC "()V",                  FN_PTR(Unsafe_WriteBackPreSync0)},
1263     {CC "writebackPostSync0", CC "()V",                  FN_PTR(Unsafe_WriteBackPostSync0)},
1264     {CC "setMemory0",         CC "(" OBJ "JJB)V",        FN_PTR(Unsafe_SetMemory0)},
1265 
1266     {CC "shouldBeInitialized0", CC "(" CLS ")Z",         FN_PTR(Unsafe_ShouldBeInitialized0)},
1267     {CC "notifyStrictStaticAccess0", CC "(" CLS "JZ)V",  FN_PTR(Unsafe_NotifyStrictStaticAccess0)},
1268 
1269     {CC "fullFence",          CC "()V",                  FN_PTR(Unsafe_FullFence)},
1270 };
1271 
1272 #undef CC
1273 #undef FN_PTR
1274 
1275 #undef ADR
1276 #undef LANG
1277 #undef OBJ
1278 #undef CLS
1279 #undef FLD
1280 #undef THR
1281 #undef DC_Args
1282 #undef DAC_Args
1283 
1284 #undef DECLARE_GETPUTOOP
1285 
1286 
1287 // This function is exported, used by NativeLookup.
1288 // The Unsafe_xxx functions above are called only from the interpreter.
1289 // The optimizer looks at names and signatures to recognize
1290 // individual functions.
1291 
1292 JVM_ENTRY(void, JVM_RegisterJDKInternalMiscUnsafeMethods(JNIEnv *env, jclass unsafeclass)) {
1293   ThreadToNativeFromVM ttnfv(thread);
1294 
1295   int ok = env->RegisterNatives(unsafeclass, jdk_internal_misc_Unsafe_methods, sizeof(jdk_internal_misc_Unsafe_methods)/sizeof(JNINativeMethod));
1296   guarantee(ok == 0, "register jdk.internal.misc.Unsafe natives");
1297 } JVM_END