1 /*
2 * Copyright (c) 2000, 2026, 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/oopCast.inline.hpp"
49 #include "oops/typeArrayOop.inline.hpp"
50 #include "oops/valuePayload.hpp"
51 #include "prims/jvmtiExport.hpp"
52 #include "prims/unsafe.hpp"
53 #include "runtime/fieldDescriptor.inline.hpp"
54 #include "runtime/globals.hpp"
55 #include "runtime/handles.inline.hpp"
56 #include "runtime/interfaceSupport.inline.hpp"
57 #include "runtime/javaThread.inline.hpp"
58 #include "runtime/jniHandles.inline.hpp"
59 #include "runtime/orderAccess.hpp"
60 #include "runtime/reflection.hpp"
61 #include "runtime/sharedRuntime.hpp"
62 #include "runtime/stubRoutines.hpp"
63 #include "runtime/threadSMR.hpp"
64 #include "runtime/vm_version.hpp"
65 #include "runtime/vmOperations.hpp"
66 #include "sanitizers/ub.hpp"
67 #include "services/threadService.hpp"
68 #include "utilities/align.hpp"
69 #include "utilities/copy.hpp"
70 #include "utilities/dtrace.hpp"
71 #include "utilities/macros.hpp"
72
73 /**
74 * Implementation of the jdk.internal.misc.Unsafe class
75 */
76
77
78 #define MAX_OBJECT_SIZE \
79 ( arrayOopDesc::base_offset_in_bytes(T_DOUBLE) \
80 + ((julong)max_jint * sizeof(double)) )
81
82 #define UNSAFE_ENTRY(result_type, header) \
83 JVM_ENTRY(static result_type, header)
84
85 #define UNSAFE_LEAF(result_type, header) \
86 JVM_LEAF(static result_type, header)
87
88 #define UNSAFE_END JVM_END
89
90
91 static inline void* addr_from_java(jlong addr) {
92 // This assert fails in a variety of ways on 32-bit systems.
93 // It is impossible to predict whether native code that converts
94 // pointers to longs will sign-extend or zero-extend the addresses.
95 //assert(addr == (uintptr_t)addr, "must not be odd high bits");
96 return (void*)(uintptr_t)addr;
97 }
98
99 static inline jlong addr_to_java(void* p) {
100 assert(p == (void*)(uintptr_t)p, "must not be odd high bits");
101 return (uintptr_t)p;
102 }
103
104
105 // Note: The VM's obj_field and related accessors use byte-scaled
106 // ("unscaled") offsets, just as the unsafe methods do.
107
108 // However, the method Unsafe.fieldOffset explicitly declines to
109 // guarantee this. The field offset values manipulated by the Java user
110 // through the Unsafe API are opaque cookies that just happen to be byte
111 // offsets. We represent this state of affairs by passing the cookies
112 // through conversion functions when going between the VM and the Unsafe API.
113 // The conversion functions just happen to be no-ops at present.
114
115 static inline jlong field_offset_to_byte_offset(jlong field_offset) {
116 return field_offset;
117 }
118
119 static inline int field_offset_from_byte_offset(int byte_offset) {
120 return byte_offset;
121 }
122
123 static inline void assert_field_offset_sane(oop p, jlong field_offset) {
124 #ifdef ASSERT
125 jlong byte_offset = field_offset_to_byte_offset(field_offset);
126
127 if (p != nullptr) {
128 assert(byte_offset >= 0 && byte_offset <= (jlong)MAX_OBJECT_SIZE, "sane offset");
129 if (byte_offset == (jint)byte_offset) {
130 void* ptr_plus_disp = cast_from_oop<address>(p) + byte_offset;
131 assert(p->field_addr<void>((jint)byte_offset) == ptr_plus_disp,
132 "raw [ptr+disp] must be consistent with oop::field_addr");
133 }
134 jlong p_size = HeapWordSize * (jlong)(p->size());
135 assert(byte_offset < p_size, "Unsafe access: offset " INT64_FORMAT " > object's size " INT64_FORMAT, (int64_t)byte_offset, (int64_t)p_size);
136 }
137 #endif
138 }
139
140 static inline void* index_oop_from_field_offset_long(oop p, jlong field_offset) {
141 assert_field_offset_sane(p, field_offset);
142 uintptr_t base_address = cast_from_oop<uintptr_t>(p);
143 uintptr_t byte_offset = (uintptr_t)field_offset_to_byte_offset(field_offset);
144 return (void*)(base_address + byte_offset);
145 }
146
147 // Externally callable versions:
148 // (Use these in compiler intrinsics which emulate unsafe primitives.)
149 jlong Unsafe_field_offset_to_byte_offset(jlong field_offset) {
150 return field_offset;
151 }
152 jlong Unsafe_field_offset_from_byte_offset(jlong byte_offset) {
153 return byte_offset;
154 }
155
156
157 ///// Data read/writes on the Java heap and in native (off-heap) memory
158
159 /**
160 * Helper class to wrap memory accesses in JavaThread::doing_unsafe_access()
161 */
162 class GuardUnsafeAccess {
163 JavaThread* _thread;
164
165 public:
166 GuardUnsafeAccess(JavaThread* thread) : _thread(thread) {
167 // native/off-heap access which may raise SIGBUS if accessing
168 // memory mapped file data in a region of the file which has
169 // been truncated and is now invalid.
170 _thread->set_doing_unsafe_access(true);
171 }
172
173 ~GuardUnsafeAccess() {
174 _thread->set_doing_unsafe_access(false);
175 }
176 };
177
178 /**
179 * Helper class for accessing memory.
180 *
181 * Normalizes values and wraps accesses in
182 * JavaThread::doing_unsafe_access() if needed.
183 */
184 template <typename T>
185 class MemoryAccess : StackObj {
186 JavaThread* _thread;
187 oop _obj;
188 ptrdiff_t _offset;
189
190 // Resolves and returns the address of the memory access.
191 // This raw memory access may fault, so we make sure it happens within the
192 // guarded scope by making the access volatile at least. Since the store
193 // of Thread::set_doing_unsafe_access() is also volatile, these accesses
194 // can not be reordered by the compiler. Therefore, if the access triggers
195 // a fault, we will know that Thread::doing_unsafe_access() returns true.
196 volatile T* addr() {
197 void* addr = index_oop_from_field_offset_long(_obj, _offset);
198 return static_cast<volatile T*>(addr);
199 }
200
201 template <typename U>
202 U normalize(U x) {
203 return x;
204 }
205
206 jboolean normalize(jboolean x) {
207 return (x & 1) != 0;
208 }
209
210 public:
211 MemoryAccess(JavaThread* thread, jobject obj, jlong offset)
212 : _thread(thread), _obj(JNIHandles::resolve(obj)), _offset((ptrdiff_t)offset) {
213 assert_field_offset_sane(_obj, offset);
214 }
215
216 T get() {
217 GuardUnsafeAccess guard(_thread);
218 return normalize(*addr());
219 }
220
221 // we use this method at some places for writing to 0 e.g. to cause a crash;
222 // ubsan does not know that this is the desired behavior
223 ATTRIBUTE_NO_UBSAN
224 void put(T x) {
225 GuardUnsafeAccess guard(_thread);
226 assert(_obj == nullptr || !_obj->is_inline_type(), "receiver cannot be an instance of a value class because they are immutable");
227 *addr() = normalize(x);
228 }
229
230
231 T get_volatile() {
232 GuardUnsafeAccess guard(_thread);
233 volatile T ret = RawAccess<MO_SEQ_CST>::load(addr());
234 return normalize(ret);
235 }
236
237 void put_volatile(T x) {
238 GuardUnsafeAccess guard(_thread);
239 RawAccess<MO_SEQ_CST>::store(addr(), normalize(x));
240 }
241 };
242
243 static void log_unsafe_value_access(oop p, jlong offset, InlineKlass* vk) {
244 Klass* k = p->klass();
245 if (log_is_enabled(Trace, valuetypes)) {
246 ResourceMark rm;
247 if (k->is_flatArray_klass()) {
248 FlatArrayKlass* vak = FlatArrayKlass::cast(k);
249 int index = (offset - vak->array_header_in_bytes()) / vak->element_byte_size();
250 flatArrayOop array = oop_cast<flatArrayOop>(p);
251 if (index >= 0 && index < array->length()) {
252 address dest = (address)((flatArrayOop)p)->value_at_addr(index, vak->layout_helper());
253 log_trace(valuetypes)("%s array type %s index %d element size %d offset " UINT64_FORMAT_X " at " INTPTR_FORMAT,
254 p->klass()->external_name(), vak->external_name(),
255 index, vak->element_byte_size(), (uint64_t)offset, p2i(dest));
256 } else {
257 log_trace(valuetypes)("%s array type %s out-of-bounds index %d element size %d offset " UINT64_FORMAT_X,
258 p->klass()->external_name(), vak->external_name(), index, vak->element_byte_size(), (uint64_t)offset);
259 }
260 } else {
261 log_trace(valuetypes)("%s field type %s at offset " UINT64_FORMAT_X,
262 p->klass()->external_name(), vk->external_name(), (uint64_t)offset);
263 }
264 }
265 }
266
267 // These functions allow a null base pointer with an arbitrary address.
268 // But if the base pointer is non-null, the offset should make some sense.
269 // That is, it should be in the range [0, MAX_OBJECT_SIZE].
270 UNSAFE_ENTRY(jobject, Unsafe_GetReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
271 oop p = JNIHandles::resolve(obj);
272 assert_field_offset_sane(p, offset);
273 oop v = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_load_at(p, offset);
274 return JNIHandles::make_local(THREAD, v);
275 } UNSAFE_END
276
277 UNSAFE_ENTRY(void, Unsafe_PutReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
278 oop x = JNIHandles::resolve(x_h);
279 oop p = JNIHandles::resolve(obj);
280 assert_field_offset_sane(p, offset);
281 assert(!p->is_inline_type(), "receiver cannot be an instance of a value class because they are immutable");
282 HeapAccess<ON_UNKNOWN_OOP_REF>::oop_store_at(p, offset, x);
283 } UNSAFE_END
284
285 UNSAFE_ENTRY(jlong, Unsafe_ValueHeaderSize(JNIEnv *env, jobject unsafe, jclass c)) {
286 Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(c));
287 InlineKlass* vk = InlineKlass::cast(k);
288 return vk->payload_offset();
289 } UNSAFE_END
290
291 UNSAFE_ENTRY(jboolean, Unsafe_IsFlatField(JNIEnv *env, jobject unsafe, jobject o)) {
292 oop f = JNIHandles::resolve_non_null(o);
293 Klass* k = java_lang_Class::as_Klass(java_lang_reflect_Field::clazz(f));
294 int slot = java_lang_reflect_Field::slot(f);
295 return InstanceKlass::cast(k)->field_is_flat(slot);
296 } UNSAFE_END
297
298 UNSAFE_ENTRY(jboolean, Unsafe_HasNullMarker(JNIEnv *env, jobject unsafe, jobject o)) {
299 oop f = JNIHandles::resolve_non_null(o);
300 Klass* k = java_lang_Class::as_Klass(java_lang_reflect_Field::clazz(f));
301 int slot = java_lang_reflect_Field::slot(f);
302 return InstanceKlass::cast(k)->field_has_null_marker(slot);
303 } UNSAFE_END
304
305 UNSAFE_ENTRY(jint, Unsafe_NullMarkerOffset(JNIEnv *env, jobject unsafe, jobject o)) {
306 oop f = JNIHandles::resolve_non_null(o);
307 Klass* k = java_lang_Class::as_Klass(java_lang_reflect_Field::clazz(f));
308 int slot = java_lang_reflect_Field::slot(f);
309 return InstanceKlass::cast(k)->field_null_marker_offset(slot);
310 } UNSAFE_END
311
312 UNSAFE_ENTRY(jint, Unsafe_ArrayLayout(JNIEnv *env, jobject unsafe, jarray array)) {
313 oop ar = JNIHandles::resolve_non_null(array);
314 ArrayKlass* ak = ArrayKlass::cast(ar->klass());
315 if (ak->is_refArray_klass()) {
316 return (jint)LayoutKind::REFERENCE;
317 } else if (ak->is_flatArray_klass()) {
318 return (jint)FlatArrayKlass::cast(ak)->layout_kind();
319 } else {
320 ShouldNotReachHere();
321 return -1;
322 }
323 } UNSAFE_END
324
325 UNSAFE_ENTRY(jint, Unsafe_FieldLayout(JNIEnv *env, jobject unsafe, jobject field)) {
326 assert(field != nullptr, "field must not be null");
327
328 oop reflected = JNIHandles::resolve_non_null(field);
329 oop mirror = java_lang_reflect_Field::clazz(reflected);
330 Klass* k = java_lang_Class::as_Klass(mirror);
331 int slot = java_lang_reflect_Field::slot(reflected);
332 int modifiers = java_lang_reflect_Field::modifiers(reflected);
333
334 if ((modifiers & JVM_ACC_STATIC) != 0) {
335 return (jint)LayoutKind::REFERENCE; // static fields are never flat
336 } else {
337 InstanceKlass* ik = InstanceKlass::cast(k);
338 if (ik->field_is_flat(slot)) {
339 return (jint)ik->inline_layout_info(slot).kind();
340 } else {
341 return (jint)LayoutKind::REFERENCE;
342 }
343 }
344 } UNSAFE_END
345
346 UNSAFE_ENTRY(jarray, Unsafe_NewSpecialArray(JNIEnv *env, jobject unsafe, jclass elmClass, jint len, jint layoutKind)) {
347 oop mirror = JNIHandles::resolve_non_null(elmClass);
348 Klass* klass = java_lang_Class::as_Klass(mirror);
349 klass->initialize(CHECK_NULL);
350 if (len < 0) {
351 THROW_MSG_NULL(vmSymbols::java_lang_IllegalArgumentException(), "Array length is negative");
352 }
353 if (klass->is_array_klass() || klass->is_identity_class()) {
354 THROW_MSG_NULL(vmSymbols::java_lang_IllegalArgumentException(), "Element class is not a value class");
355 }
356 if (klass->is_abstract()) {
357 THROW_MSG_NULL(vmSymbols::java_lang_IllegalArgumentException(), "Element class is abstract");
358 }
359 LayoutKind lk = static_cast<LayoutKind>(layoutKind);
360 if (lk <= LayoutKind::REFERENCE || lk == LayoutKind::NULLABLE_NON_ATOMIC_FLAT || lk >= LayoutKind::UNKNOWN) {
361 THROW_MSG_NULL(vmSymbols::java_lang_IllegalArgumentException(), "Invalid layout kind");
362 }
363 InlineKlass* vk = InlineKlass::cast(klass);
364 // WARNING: test below will need modifications when flat layouts supported for fields
365 // but not for arrays are introduce (NULLABLE_NON_ATOMIC_FLAT for instance)
366 if (!UseArrayFlattening || !vk->is_layout_supported(lk)) {
367 THROW_MSG_NULL(vmSymbols::java_lang_UnsupportedOperationException(), "Layout not supported");
368 }
369 ArrayProperties props = ArrayKlass::array_properties_from_layout(lk);
370 oop array = oopFactory::new_flatArray(vk, len, props, CHECK_NULL);
371 return (jarray) JNIHandles::make_local(THREAD, array);
372 } UNSAFE_END
373
374 UNSAFE_ENTRY(jobject, Unsafe_GetFlatValue(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint layoutKind, jclass vc)) {
375 assert(layoutKind != (int)LayoutKind::UNKNOWN, "Sanity");
376 assert(layoutKind != (int)LayoutKind::REFERENCE, "This method handles only flat layouts");
377 oop base = JNIHandles::resolve(obj);
378 if (base == nullptr) {
379 THROW_NULL(vmSymbols::java_lang_NullPointerException());
380 }
381 Klass* k = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(vc));
382 InlineKlass* vk = InlineKlass::cast(k);
383 log_unsafe_value_access(base, offset, vk);
384 LayoutKind lk = (LayoutKind)layoutKind;
385 FlatValuePayload payload = FlatValuePayload::construct_from_parts(base, offset, vk, lk);
386 oop v = payload.read(CHECK_NULL);
387 return JNIHandles::make_local(THREAD, v);
388 } UNSAFE_END
389
390 UNSAFE_ENTRY(void, Unsafe_PutFlatValue(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint layoutKind, jclass vc, jobject value)) {
391 assert(layoutKind != (int)LayoutKind::UNKNOWN, "Sanity");
392 assert(layoutKind != (int)LayoutKind::REFERENCE, "This method handles only flat layouts");
393 oop base = JNIHandles::resolve(obj);
394 if (base == nullptr) {
395 THROW(vmSymbols::java_lang_NullPointerException());
396 }
397
398 InlineKlass* vk = InlineKlass::cast(java_lang_Class::as_Klass(JNIHandles::resolve_non_null(vc)));
399 log_unsafe_value_access(base, offset, vk);
400 LayoutKind lk = (LayoutKind)layoutKind;
401 FlatValuePayload payload = FlatValuePayload::construct_from_parts(base, offset, vk, lk);
402 payload.write(inlineOop(JNIHandles::resolve(value)), CHECK);
403 } UNSAFE_END
404
405 UNSAFE_ENTRY(jobject, Unsafe_GetReferenceVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
406 oop p = JNIHandles::resolve(obj);
407 assert_field_offset_sane(p, offset);
408 oop v = HeapAccess<MO_SEQ_CST | ON_UNKNOWN_OOP_REF>::oop_load_at(p, offset);
409 return JNIHandles::make_local(THREAD, v);
410 } UNSAFE_END
411
412 UNSAFE_ENTRY(void, Unsafe_PutReferenceVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
413 oop x = JNIHandles::resolve(x_h);
414 oop p = JNIHandles::resolve(obj);
415 assert_field_offset_sane(p, offset);
416 HeapAccess<MO_SEQ_CST | ON_UNKNOWN_OOP_REF>::oop_store_at(p, offset, x);
417 } UNSAFE_END
418
419 UNSAFE_ENTRY(jobject, Unsafe_GetUncompressedObject(JNIEnv *env, jobject unsafe, jlong addr)) {
420 oop v = *(oop*) (address) addr;
421 return JNIHandles::make_local(THREAD, v);
422 } UNSAFE_END
423
424 #define DEFINE_GETSETOOP(java_type, Type) \
425 \
426 UNSAFE_ENTRY(java_type, Unsafe_Get##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
427 return MemoryAccess<java_type>(thread, obj, offset).get(); \
428 } UNSAFE_END \
429 \
430 UNSAFE_ENTRY(void, Unsafe_Put##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
431 MemoryAccess<java_type>(thread, obj, offset).put(x); \
432 } UNSAFE_END \
433 \
434 // END DEFINE_GETSETOOP.
435
436 DEFINE_GETSETOOP(jboolean, Boolean)
437 DEFINE_GETSETOOP(jbyte, Byte)
438 DEFINE_GETSETOOP(jshort, Short);
439 DEFINE_GETSETOOP(jchar, Char);
440 DEFINE_GETSETOOP(jint, Int);
441 DEFINE_GETSETOOP(jlong, Long);
442 DEFINE_GETSETOOP(jfloat, Float);
443 DEFINE_GETSETOOP(jdouble, Double);
444
445 #undef DEFINE_GETSETOOP
446
447 #define DEFINE_GETSETOOP_VOLATILE(java_type, Type) \
448 \
449 UNSAFE_ENTRY(java_type, Unsafe_Get##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
450 return MemoryAccess<java_type>(thread, obj, offset).get_volatile(); \
451 } UNSAFE_END \
452 \
453 UNSAFE_ENTRY(void, Unsafe_Put##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
454 MemoryAccess<java_type>(thread, obj, offset).put_volatile(x); \
455 } UNSAFE_END \
456 \
457 // END DEFINE_GETSETOOP_VOLATILE.
458
459 DEFINE_GETSETOOP_VOLATILE(jboolean, Boolean)
460 DEFINE_GETSETOOP_VOLATILE(jbyte, Byte)
461 DEFINE_GETSETOOP_VOLATILE(jshort, Short);
462 DEFINE_GETSETOOP_VOLATILE(jchar, Char);
463 DEFINE_GETSETOOP_VOLATILE(jint, Int);
464 DEFINE_GETSETOOP_VOLATILE(jlong, Long);
465 DEFINE_GETSETOOP_VOLATILE(jfloat, Float);
466 DEFINE_GETSETOOP_VOLATILE(jdouble, Double);
467
468 #undef DEFINE_GETSETOOP_VOLATILE
469
470 UNSAFE_LEAF(void, Unsafe_FullFence(JNIEnv *env, jobject unsafe)) {
471 OrderAccess::fence();
472 } UNSAFE_END
473
474 ////// Allocation requests
475
476 UNSAFE_ENTRY(jobject, Unsafe_AllocateInstance(JNIEnv *env, jobject unsafe, jclass cls)) {
477 JvmtiVMObjectAllocEventCollector oam;
478 instanceOop i = InstanceKlass::allocate_instance(JNIHandles::resolve_non_null(cls), CHECK_NULL);
479 return JNIHandles::make_local(THREAD, i);
480 } UNSAFE_END
481
482 UNSAFE_LEAF(jlong, Unsafe_AllocateMemory0(JNIEnv *env, jobject unsafe, jlong size)) {
483 size_t sz = (size_t)size;
484
485 assert(is_aligned(sz, HeapWordSize), "sz not aligned");
486
487 void* x = os::malloc(sz, mtOther);
488
489 return addr_to_java(x);
490 } UNSAFE_END
491
492 UNSAFE_LEAF(jlong, Unsafe_ReallocateMemory0(JNIEnv *env, jobject unsafe, jlong addr, jlong size)) {
493 void* p = addr_from_java(addr);
494 size_t sz = (size_t)size;
495
496 assert(is_aligned(sz, HeapWordSize), "sz not aligned");
497
498 void* x = os::realloc(p, sz, mtOther);
499
500 return addr_to_java(x);
501 } UNSAFE_END
502
503 UNSAFE_LEAF(void, Unsafe_FreeMemory0(JNIEnv *env, jobject unsafe, jlong addr)) {
504 void* p = addr_from_java(addr);
505
506 os::free(p);
507 } UNSAFE_END
508
509 UNSAFE_ENTRY(void, Unsafe_SetMemory0(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong size, jbyte value)) {
510 size_t sz = (size_t)size;
511
512 oop base = JNIHandles::resolve(obj);
513 void* p = index_oop_from_field_offset_long(base, offset);
514
515 {
516 GuardUnsafeAccess guard(thread);
517 if (StubRoutines::unsafe_setmemory() != nullptr) {
518 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXExec, thread));
519 StubRoutines::UnsafeSetMemory_stub()(p, sz, value);
520 } else {
521 Copy::fill_to_memory_atomic(p, sz, value);
522 }
523 }
524 } UNSAFE_END
525
526 UNSAFE_ENTRY(void, Unsafe_CopyMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size)) {
527 size_t sz = (size_t)size;
528
529 oop srcp = JNIHandles::resolve(srcObj);
530 oop dstp = JNIHandles::resolve(dstObj);
531
532 void* src = index_oop_from_field_offset_long(srcp, srcOffset);
533 void* dst = index_oop_from_field_offset_long(dstp, dstOffset);
534 {
535 GuardUnsafeAccess guard(thread);
536 if (StubRoutines::unsafe_arraycopy() != nullptr) {
537 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXExec, thread));
538 StubRoutines::UnsafeArrayCopy_stub()(src, dst, sz);
539 } else {
540 Copy::conjoint_memory_atomic(src, dst, sz);
541 }
542 }
543 } UNSAFE_END
544
545 // This function is a leaf since if the source and destination are both in native memory
546 // the copy may potentially be very large, and we don't want to disable GC if we can avoid it.
547 // If either source or destination (or both) are on the heap, the function will enter VM using
548 // JVM_ENTRY_FROM_LEAF
549 UNSAFE_LEAF(void, Unsafe_CopySwapMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size, jlong elemSize)) {
550 size_t sz = (size_t)size;
551 size_t esz = (size_t)elemSize;
552
553
554 if (srcObj == nullptr && dstObj == nullptr) {
555 // Both src & dst are in native memory
556 address src = (address)srcOffset;
557 address dst = (address)dstOffset;
558
559 {
560 JavaThread* thread = JavaThread::thread_from_jni_environment(env);
561 GuardUnsafeAccess guard(thread);
562 Copy::conjoint_swap(src, dst, sz, esz);
563 }
564 } else {
565 // At least one of src/dst are on heap, transition to VM to access raw pointers
566
567 JVM_ENTRY_FROM_LEAF(env, void, Unsafe_CopySwapMemory0) {
568 oop srcp = JNIHandles::resolve(srcObj);
569 oop dstp = JNIHandles::resolve(dstObj);
570
571 address src = (address)index_oop_from_field_offset_long(srcp, srcOffset);
572 address dst = (address)index_oop_from_field_offset_long(dstp, dstOffset);
573 {
574 GuardUnsafeAccess guard(thread);
575 Copy::conjoint_swap(src, dst, sz, esz);
576 }
577 } JVM_END
578 }
579 } UNSAFE_END
580
581 UNSAFE_LEAF (void, Unsafe_WriteBack0(JNIEnv *env, jobject unsafe, jlong line)) {
582 assert(VM_Version::supports_data_cache_line_flush(), "should not get here");
583 #ifdef ASSERT
584 if (TraceMemoryWriteback) {
585 tty->print_cr("Unsafe: writeback 0x%p", addr_from_java(line));
586 }
587 #endif
588
589 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXExec, Thread::current()));
590 assert(StubRoutines::data_cache_writeback() != nullptr, "sanity");
591 (StubRoutines::DataCacheWriteback_stub())(addr_from_java(line));
592 } UNSAFE_END
593
594 static void doWriteBackSync0(bool is_pre)
595 {
596 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXExec, Thread::current()));
597 assert(StubRoutines::data_cache_writeback_sync() != nullptr, "sanity");
598 (StubRoutines::DataCacheWritebackSync_stub())(is_pre);
599 }
600
601 UNSAFE_LEAF (void, Unsafe_WriteBackPreSync0(JNIEnv *env, jobject unsafe)) {
602 assert(VM_Version::supports_data_cache_line_flush(), "should not get here");
603 #ifdef ASSERT
604 if (TraceMemoryWriteback) {
605 tty->print_cr("Unsafe: writeback pre-sync");
606 }
607 #endif
608
609 doWriteBackSync0(true);
610 } UNSAFE_END
611
612 UNSAFE_LEAF (void, Unsafe_WriteBackPostSync0(JNIEnv *env, jobject unsafe)) {
613 assert(VM_Version::supports_data_cache_line_flush(), "should not get here");
614 #ifdef ASSERT
615 if (TraceMemoryWriteback) {
616 tty->print_cr("Unsafe: writeback pre-sync");
617 }
618 #endif
619
620 doWriteBackSync0(false);
621 } UNSAFE_END
622
623 ////// Random queries
624
625 // Finds the object field offset of a field with the matching name, or an error code
626 // Error code -1 is not found, -2 is static field
627 static jlong find_known_instance_field_offset(jclass clazz, jstring name, TRAPS) {
628 assert(clazz != nullptr, "clazz must not be null");
629 assert(name != nullptr, "name must not be null");
630
631 ResourceMark rm(THREAD);
632 char *utf_name = java_lang_String::as_utf8_string(JNIHandles::resolve_non_null(name));
633
634 InstanceKlass* k = java_lang_Class::as_InstanceKlass(JNIHandles::resolve_non_null(clazz));
635
636 jint offset = -1; // Not found
637 for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
638 Symbol *name = fs.name();
639 if (name->equals(utf_name)) {
640 if (!fs.access_flags().is_static()) {
641 offset = fs.offset();
642 } else {
643 offset = -2; // A static field
644 }
645 break;
646 }
647 }
648 if (offset < 0) {
649 return offset; // Error code
650 }
651 return field_offset_from_byte_offset(offset);
652 }
653
654 static jlong find_field_offset(jobject field, int must_be_static, TRAPS) {
655 assert(field != nullptr, "field must not be null");
656
657 oop reflected = JNIHandles::resolve_non_null(field);
658 oop mirror = java_lang_reflect_Field::clazz(reflected);
659 Klass* k = java_lang_Class::as_Klass(mirror);
660 int slot = java_lang_reflect_Field::slot(reflected);
661 int modifiers = java_lang_reflect_Field::modifiers(reflected);
662
663 if (must_be_static >= 0) {
664 int really_is_static = ((modifiers & JVM_ACC_STATIC) != 0);
665 if (must_be_static != really_is_static) {
666 THROW_0(vmSymbols::java_lang_IllegalArgumentException());
667 }
668 }
669
670 int offset = InstanceKlass::cast(k)->field_offset(slot);
671 return field_offset_from_byte_offset(offset);
672 }
673
674 UNSAFE_ENTRY(jlong, Unsafe_ObjectFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
675 return find_field_offset(field, 0, THREAD);
676 } UNSAFE_END
677
678 UNSAFE_ENTRY(jlong, Unsafe_KnownObjectFieldOffset0(JNIEnv *env, jobject unsafe, jclass c, jstring name)) {
679 return find_known_instance_field_offset(c, name, THREAD);
680 } UNSAFE_END
681
682 UNSAFE_ENTRY(jlong, Unsafe_StaticFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
683 return find_field_offset(field, 1, THREAD);
684 } UNSAFE_END
685
686 UNSAFE_ENTRY(jobject, Unsafe_StaticFieldBase0(JNIEnv *env, jobject unsafe, jobject field)) {
687 assert(field != nullptr, "field must not be null");
688
689 // Note: In this VM implementation, a field address is always a short
690 // offset from the base of a klass metaobject. Thus, the full dynamic
691 // range of the return type is never used. However, some implementations
692 // might put the static field inside an array shared by many classes,
693 // or even at a fixed address, in which case the address could be quite
694 // large. In that last case, this function would return null, since
695 // the address would operate alone, without any base pointer.
696
697 oop reflected = JNIHandles::resolve_non_null(field);
698 oop mirror = java_lang_reflect_Field::clazz(reflected);
699 int modifiers = java_lang_reflect_Field::modifiers(reflected);
700
701 if ((modifiers & JVM_ACC_STATIC) == 0) {
702 THROW_NULL(vmSymbols::java_lang_IllegalArgumentException());
703 }
704
705 return JNIHandles::make_local(THREAD, mirror);
706 } UNSAFE_END
707
708 UNSAFE_ENTRY(void, Unsafe_EnsureClassInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
709 assert(clazz != nullptr, "clazz must not be null");
710
711 oop mirror = JNIHandles::resolve_non_null(clazz);
712
713 Klass* klass = java_lang_Class::as_Klass(mirror);
714 if (klass != nullptr && klass->should_be_initialized()) {
715 InstanceKlass* k = InstanceKlass::cast(klass);
716 k->initialize(CHECK);
717 }
718 }
719 UNSAFE_END
720
721 UNSAFE_ENTRY(jboolean, Unsafe_ShouldBeInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
722 assert(clazz != nullptr, "clazz must not be null");
723
724 oop mirror = JNIHandles::resolve_non_null(clazz);
725 Klass* klass = java_lang_Class::as_Klass(mirror);
726
727 if (klass != nullptr && klass->should_be_initialized()) {
728 return true;
729 }
730
731 return false;
732 }
733 UNSAFE_END
734
735 UNSAFE_ENTRY(void, Unsafe_NotifyStrictStaticAccess0(JNIEnv *env, jobject unsafe, jobject clazz,
736 jlong sfoffset, jboolean writing)) {
737 assert(clazz != nullptr, "clazz must not be null");
738
739 oop mirror = JNIHandles::resolve_non_null(clazz);
740 Klass* klass = java_lang_Class::as_Klass(mirror);
741
742 if (klass != nullptr && klass->is_instance_klass()) {
743 InstanceKlass* ik = InstanceKlass::cast(klass);
744 fieldDescriptor fd;
745 if (ik->find_local_field_from_offset((int)sfoffset, true, &fd)) {
746 // Note: The Unsafe API takes an OFFSET, but the InstanceKlass wants the INDEX.
747 // We could surface field indexes into Unsafe, but that's too much churn.
748 ik->notify_strict_static_access(fd.index(), writing, CHECK);
749 return;
750 }
751 }
752 THROW(vmSymbols::java_lang_InternalError());
753 }
754 UNSAFE_END
755
756 static void getBaseAndScale(int& base, int& scale, jclass clazz, TRAPS) {
757 assert(clazz != nullptr, "clazz must not be null");
758
759 oop mirror = JNIHandles::resolve_non_null(clazz);
760 Klass* k = java_lang_Class::as_Klass(mirror);
761
762 if (k == nullptr || !k->is_array_klass()) {
763 THROW(vmSymbols::java_lang_InvalidClassException());
764 } else if (k->is_typeArray_klass()) {
765 TypeArrayKlass* tak = TypeArrayKlass::cast(k);
766 base = tak->array_header_in_bytes();
767 assert(base == arrayOopDesc::base_offset_in_bytes(tak->element_type()), "array_header_size semantics ok");
768 scale = (1 << tak->log2_element_size());
769 } else if (k->is_objArray_klass()) {
770 Klass* ek = ObjArrayKlass::cast(k)->element_klass();
771 if (!ek->is_identity_class() && !ek->is_abstract()) {
772 // Arrays of a concrete value class type can have multiple layouts
773 // There's no good value to return, so throwing an exception is the way out
774 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "Arrays of a concrete value class don't have a single base and offset");
775 }
776 base = arrayOopDesc::base_offset_in_bytes(T_OBJECT);
777 scale = heapOopSize;
778 } else {
779 ShouldNotReachHere();
780 }
781 }
782
783 UNSAFE_ENTRY(jint, Unsafe_ArrayInstanceBaseOffset0(JNIEnv *env, jobject unsafe, jarray array)) {
784 assert(array != nullptr, "array must not be null");
785 oop ar = JNIHandles::resolve_non_null(array);
786 assert(ar->is_array(), "Must be an array");
787 ArrayKlass* ak = ArrayKlass::cast(ar->klass());
788 if (ak->is_refArray_klass()) {
789 return arrayOopDesc::base_offset_in_bytes(T_OBJECT);
790 } else if (ak->is_flatArray_klass()) {
791 FlatArrayKlass* fak = FlatArrayKlass::cast(ak);
792 return fak->array_header_in_bytes();
793 } else {
794 ShouldNotReachHere();
795 }
796 } UNSAFE_END
797
798 UNSAFE_ENTRY(jint, Unsafe_ArrayBaseOffset0(JNIEnv *env, jobject unsafe, jclass clazz)) {
799 int base = 0, scale = 0;
800 getBaseAndScale(base, scale, clazz, CHECK_0);
801
802 return field_offset_from_byte_offset(base);
803 } UNSAFE_END
804
805
806 UNSAFE_ENTRY(jint, Unsafe_ArrayIndexScale0(JNIEnv *env, jobject unsafe, jclass clazz)) {
807 int base = 0, scale = 0;
808 getBaseAndScale(base, scale, clazz, CHECK_0);
809
810 // This VM packs both fields and array elements down to the byte.
811 // But watch out: If this changes, so that array references for
812 // a given primitive type (say, T_BOOLEAN) use different memory units
813 // than fields, this method MUST return zero for such arrays.
814 // For example, the VM used to store sub-word sized fields in full
815 // words in the object layout, so that accessors like getByte(Object,int)
816 // did not really do what one might expect for arrays. Therefore,
817 // this function used to report a zero scale factor, so that the user
818 // would know not to attempt to access sub-word array elements.
819 // // Code for unpacked fields:
820 // if (scale < wordSize) return 0;
821
822 // The following allows for a pretty general fieldOffset cookie scheme,
823 // but requires it to be linear in byte offset.
824 return field_offset_from_byte_offset(scale) - field_offset_from_byte_offset(0);
825 } UNSAFE_END
826
827 UNSAFE_ENTRY(jint, Unsafe_ArrayInstanceIndexScale0(JNIEnv *env, jobject unsafe, jarray array)) {
828 assert(array != nullptr, "array must not be null");
829 oop ar = JNIHandles::resolve_non_null(array);
830 assert(ar->is_array(), "Must be an array");
831 ArrayKlass* ak = ArrayKlass::cast(ar->klass());
832 if (ak->is_refArray_klass()) {
833 return heapOopSize;
834 } else if (ak->is_flatArray_klass()) {
835 FlatArrayKlass* fak = FlatArrayKlass::cast(ak);
836 return fak->element_byte_size();
837 } else {
838 ShouldNotReachHere();
839 }
840 } UNSAFE_END
841
842 UNSAFE_ENTRY(jarray, Unsafe_GetFieldMap0(JNIEnv* env, jobject unsafe, jclass clazz)) {
843 oop mirror = JNIHandles::resolve_non_null(clazz);
844 Klass* k = java_lang_Class::as_Klass(mirror);
845
846 if (!k->is_inline_klass()) {
847 THROW_MSG_NULL(vmSymbols::java_lang_IllegalArgumentException(), "Argument is not a concrete value class");
848 }
849 InlineKlass* vk = InlineKlass::cast(k);
850 oop map = mirror->obj_field(vk->acmp_maps_offset());
851 return (jarray) JNIHandles::make_local(THREAD, map);
852 } UNSAFE_END
853
854 UNSAFE_ENTRY(jlong, Unsafe_GetObjectSize0(JNIEnv* env, jobject o, jobject obj))
855 oop p = JNIHandles::resolve(obj);
856 return p->size() * HeapWordSize;
857 UNSAFE_END
858
859 static inline void throw_new(JNIEnv *env, const char *ename) {
860 jclass cls = env->FindClass(ename);
861 if (env->ExceptionCheck()) {
862 env->ExceptionClear();
863 tty->print_cr("Unsafe: cannot throw %s because FindClass has failed", ename);
864 return;
865 }
866
867 env->ThrowNew(cls, nullptr);
868 }
869
870 static jclass Unsafe_DefineClass_impl(JNIEnv *env, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd) {
871 // Code lifted from JDK 1.3 ClassLoader.c
872
873 jbyte *body;
874 char *utfName = nullptr;
875 jclass result = nullptr;
876 char buf[128];
877
878 assert(data != nullptr, "Class bytes must not be null");
879 assert(length >= 0, "length must not be negative: %d", length);
880
881 if (UsePerfData) {
882 ClassLoader::unsafe_defineClassCallCounter()->inc();
883 }
884
885 body = NEW_C_HEAP_ARRAY_RETURN_NULL(jbyte, length, mtInternal);
886 if (body == nullptr) {
887 throw_new(env, "java/lang/OutOfMemoryError");
888 return nullptr;
889 }
890
891 env->GetByteArrayRegion(data, offset, length, body);
892 if (env->ExceptionCheck()) {
893 goto free_body;
894 }
895
896 if (name != nullptr) {
897 uint len = env->GetStringUTFLength(name);
898 int unicode_len = env->GetStringLength(name);
899
900 if (len >= sizeof(buf)) {
901 utfName = NEW_C_HEAP_ARRAY_RETURN_NULL(char, len + 1, mtInternal);
902 if (utfName == nullptr) {
903 throw_new(env, "java/lang/OutOfMemoryError");
904 goto free_body;
905 }
906 } else {
907 utfName = buf;
908 }
909
910 env->GetStringUTFRegion(name, 0, unicode_len, utfName);
911
912 for (uint i = 0; i < len; i++) {
913 if (utfName[i] == '.') utfName[i] = '/';
914 }
915 }
916
917 result = JVM_DefineClass(env, utfName, loader, body, length, pd);
918
919 if (utfName && utfName != buf) {
920 FREE_C_HEAP_ARRAY(utfName);
921 }
922
923 free_body:
924 FREE_C_HEAP_ARRAY(body);
925 return result;
926 }
927
928
929 UNSAFE_ENTRY(jclass, Unsafe_DefineClass0(JNIEnv *env, jobject unsafe, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd)) {
930 ThreadToNativeFromVM ttnfv(thread);
931
932 return Unsafe_DefineClass_impl(env, name, data, offset, length, loader, pd);
933 } UNSAFE_END
934
935
936 UNSAFE_ENTRY(void, Unsafe_ThrowException(JNIEnv *env, jobject unsafe, jthrowable thr)) {
937 ThreadToNativeFromVM ttnfv(thread);
938 env->Throw(thr);
939 } UNSAFE_END
940
941 // JSR166 ------------------------------------------------------------------
942
943 UNSAFE_ENTRY(jobject, Unsafe_CompareAndExchangeReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
944 oop x = JNIHandles::resolve(x_h);
945 oop e = JNIHandles::resolve(e_h);
946 oop p = JNIHandles::resolve(obj);
947 assert_field_offset_sane(p, offset);
948 oop res = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_atomic_cmpxchg_at(p, (ptrdiff_t)offset, e, x);
949 return JNIHandles::make_local(THREAD, res);
950 } UNSAFE_END
951
952 UNSAFE_ENTRY(jint, Unsafe_CompareAndExchangeInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
953 oop p = JNIHandles::resolve(obj);
954 volatile jint* addr = (volatile jint*)index_oop_from_field_offset_long(p, offset);
955 return AtomicAccess::cmpxchg(addr, e, x);
956 } UNSAFE_END
957
958 UNSAFE_ENTRY(jlong, Unsafe_CompareAndExchangeLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
959 oop p = JNIHandles::resolve(obj);
960 volatile jlong* addr = (volatile jlong*)index_oop_from_field_offset_long(p, offset);
961 return AtomicAccess::cmpxchg(addr, e, x);
962 } UNSAFE_END
963
964 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
965 oop x = JNIHandles::resolve(x_h);
966 oop e = JNIHandles::resolve(e_h);
967 oop p = JNIHandles::resolve(obj);
968 assert_field_offset_sane(p, offset);
969 oop ret = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_atomic_cmpxchg_at(p, (ptrdiff_t)offset, e, x);
970 return ret == e;
971 } UNSAFE_END
972
973 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
974 oop p = JNIHandles::resolve(obj);
975 volatile jint* addr = (volatile jint*)index_oop_from_field_offset_long(p, offset);
976 return AtomicAccess::cmpxchg(addr, e, x) == e;
977 } UNSAFE_END
978
979 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
980 oop p = JNIHandles::resolve(obj);
981 volatile jlong* addr = (volatile jlong*)index_oop_from_field_offset_long(p, offset);
982 return AtomicAccess::cmpxchg(addr, e, x) == e;
983 } UNSAFE_END
984
985 static void post_thread_park_event(EventThreadPark* event, const oop obj, jlong timeout_nanos, jlong until_epoch_millis) {
986 assert(event != nullptr, "invariant");
987 event->set_parkedClass((obj != nullptr) ? obj->klass() : nullptr);
988 event->set_timeout(timeout_nanos);
989 event->set_until(until_epoch_millis);
990 event->set_address((obj != nullptr) ? (u8)cast_from_oop<uintptr_t>(obj) : 0);
991 event->commit();
992 }
993
994 UNSAFE_ENTRY(void, Unsafe_Park(JNIEnv *env, jobject unsafe, jboolean isAbsolute, jlong time)) {
995 HOTSPOT_THREAD_PARK_BEGIN((uintptr_t) thread->parker(), (int) isAbsolute, time);
996 EventThreadPark event;
997
998 JavaThreadParkedState jtps(thread, time != 0);
999 thread->parker()->park(isAbsolute != 0, time);
1000 if (event.should_commit()) {
1001 const oop obj = thread->current_park_blocker();
1002 if (time == 0) {
1003 post_thread_park_event(&event, obj, min_jlong, min_jlong);
1004 } else {
1005 if (isAbsolute != 0) {
1006 post_thread_park_event(&event, obj, min_jlong, time);
1007 } else {
1008 post_thread_park_event(&event, obj, time, min_jlong);
1009 }
1010 }
1011 }
1012 HOTSPOT_THREAD_PARK_END((uintptr_t) thread->parker());
1013 } UNSAFE_END
1014
1015 UNSAFE_ENTRY(void, Unsafe_Unpark(JNIEnv *env, jobject unsafe, jobject jthread)) {
1016 if (jthread != nullptr) {
1017 oop thread_oop = JNIHandles::resolve_non_null(jthread);
1018 // Get the JavaThread* stored in the java.lang.Thread object _before_
1019 // the embedded ThreadsListHandle is constructed so we know if the
1020 // early life stage of the JavaThread* is protected. We use acquire
1021 // here to ensure that if we see a non-nullptr value, then we also
1022 // see the main ThreadsList updates from the JavaThread* being added.
1023 FastThreadsListHandle ftlh(thread_oop, java_lang_Thread::thread_acquire(thread_oop));
1024 JavaThread* thr = ftlh.protected_java_thread();
1025 if (thr != nullptr) {
1026 // The still live JavaThread* is protected by the FastThreadsListHandle
1027 // so it is safe to access.
1028 Parker* p = thr->parker();
1029 HOTSPOT_THREAD_UNPARK((uintptr_t) p);
1030 p->unpark();
1031 }
1032 } // FastThreadsListHandle is destroyed here.
1033 } UNSAFE_END
1034
1035 UNSAFE_ENTRY(jint, Unsafe_GetLoadAverage0(JNIEnv *env, jobject unsafe, jdoubleArray loadavg, jint nelem)) {
1036 const int max_nelem = 3;
1037 double la[max_nelem];
1038 jint ret;
1039
1040 typeArrayOop a = typeArrayOop(JNIHandles::resolve_non_null(loadavg));
1041 assert(a->is_typeArray(), "must be type array");
1042
1043 ret = os::loadavg(la, nelem);
1044 if (ret == -1) {
1045 return -1;
1046 }
1047
1048 // if successful, ret is the number of samples actually retrieved.
1049 assert(ret >= 0 && ret <= max_nelem, "Unexpected loadavg return value");
1050 switch(ret) {
1051 case 3: a->double_at_put(2, (jdouble)la[2]); // fall through
1052 case 2: a->double_at_put(1, (jdouble)la[1]); // fall through
1053 case 1: a->double_at_put(0, (jdouble)la[0]); break;
1054 }
1055
1056 return ret;
1057 } UNSAFE_END
1058
1059
1060 /// JVM_RegisterUnsafeMethods
1061
1062 #define ADR "J"
1063
1064 #define LANG "Ljava/lang/"
1065
1066 #define OBJ LANG "Object;"
1067 #define CLS LANG "Class;"
1068 #define FLD LANG "reflect/Field;"
1069 #define THR LANG "Throwable;"
1070
1071 #define OBJ_ARR "[" OBJ
1072
1073 #define DC_Args LANG "String;[BII" LANG "ClassLoader;" "Ljava/security/ProtectionDomain;"
1074 #define DAC_Args CLS "[B[" OBJ
1075
1076 #define CC (char*) /*cast a literal from (const char*)*/
1077 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
1078
1079 #define DECLARE_GETPUTOOP(Type, Desc) \
1080 {CC "get" #Type, CC "(" OBJ "J)" #Desc, FN_PTR(Unsafe_Get##Type)}, \
1081 {CC "put" #Type, CC "(" OBJ "J" #Desc ")V", FN_PTR(Unsafe_Put##Type)}, \
1082 {CC "get" #Type "Volatile", CC "(" OBJ "J)" #Desc, FN_PTR(Unsafe_Get##Type##Volatile)}, \
1083 {CC "put" #Type "Volatile", CC "(" OBJ "J" #Desc ")V", FN_PTR(Unsafe_Put##Type##Volatile)}
1084
1085
1086 static JNINativeMethod jdk_internal_misc_Unsafe_methods[] = {
1087 {CC "getReference", CC "(" OBJ "J)" OBJ "", FN_PTR(Unsafe_GetReference)},
1088 {CC "putReference", CC "(" OBJ "J" OBJ ")V", FN_PTR(Unsafe_PutReference)},
1089 {CC "getReferenceVolatile", CC "(" OBJ "J)" OBJ, FN_PTR(Unsafe_GetReferenceVolatile)},
1090 {CC "putReferenceVolatile", CC "(" OBJ "J" OBJ ")V", FN_PTR(Unsafe_PutReferenceVolatile)},
1091
1092 {CC "isFlatField0", CC "(" OBJ ")Z", FN_PTR(Unsafe_IsFlatField)},
1093 {CC "hasNullMarker0", CC "(" OBJ ")Z", FN_PTR(Unsafe_HasNullMarker)},
1094 {CC "nullMarkerOffset0", CC "(" OBJ ")I", FN_PTR(Unsafe_NullMarkerOffset)},
1095 {CC "arrayLayout0", CC "(" OBJ_ARR ")I", FN_PTR(Unsafe_ArrayLayout)},
1096 {CC "fieldLayout0", CC "(" OBJ ")I", FN_PTR(Unsafe_FieldLayout)},
1097 {CC "newSpecialArray", CC "(" CLS "II)[" OBJ, FN_PTR(Unsafe_NewSpecialArray)},
1098 {CC "getFlatValue", CC "(" OBJ "JI" CLS ")" OBJ, FN_PTR(Unsafe_GetFlatValue)},
1099 {CC "putFlatValue", CC "(" OBJ "JI" CLS OBJ ")V", FN_PTR(Unsafe_PutFlatValue)},
1100 {CC "valueHeaderSize", CC "(" CLS ")J", FN_PTR(Unsafe_ValueHeaderSize)},
1101 {CC "getUncompressedObject", CC "(" ADR ")" OBJ, FN_PTR(Unsafe_GetUncompressedObject)},
1102
1103 DECLARE_GETPUTOOP(Boolean, Z),
1104 DECLARE_GETPUTOOP(Byte, B),
1105 DECLARE_GETPUTOOP(Short, S),
1106 DECLARE_GETPUTOOP(Char, C),
1107 DECLARE_GETPUTOOP(Int, I),
1108 DECLARE_GETPUTOOP(Long, J),
1109 DECLARE_GETPUTOOP(Float, F),
1110 DECLARE_GETPUTOOP(Double, D),
1111
1112 {CC "allocateMemory0", CC "(J)" ADR, FN_PTR(Unsafe_AllocateMemory0)},
1113 {CC "reallocateMemory0", CC "(" ADR "J)" ADR, FN_PTR(Unsafe_ReallocateMemory0)},
1114 {CC "freeMemory0", CC "(" ADR ")V", FN_PTR(Unsafe_FreeMemory0)},
1115
1116 {CC "objectFieldOffset0", CC "(" FLD ")J", FN_PTR(Unsafe_ObjectFieldOffset0)},
1117 {CC "knownObjectFieldOffset0", CC "(" CLS LANG "String;)J", FN_PTR(Unsafe_KnownObjectFieldOffset0)},
1118 {CC "staticFieldOffset0", CC "(" FLD ")J", FN_PTR(Unsafe_StaticFieldOffset0)},
1119 {CC "staticFieldBase0", CC "(" FLD ")" OBJ, FN_PTR(Unsafe_StaticFieldBase0)},
1120 {CC "ensureClassInitialized0", CC "(" CLS ")V", FN_PTR(Unsafe_EnsureClassInitialized0)},
1121 {CC "arrayBaseOffset0", CC "(" CLS ")I", FN_PTR(Unsafe_ArrayBaseOffset0)},
1122 {CC "arrayInstanceBaseOffset0", CC "(" OBJ_ARR ")I", FN_PTR(Unsafe_ArrayInstanceBaseOffset0)},
1123 {CC "arrayIndexScale0", CC "(" CLS ")I", FN_PTR(Unsafe_ArrayIndexScale0)},
1124 {CC "arrayInstanceIndexScale0", CC "(" OBJ_ARR ")I", FN_PTR(Unsafe_ArrayInstanceIndexScale0)},
1125 {CC "getFieldMap0", CC "(Ljava/lang/Class;)[I", FN_PTR(Unsafe_GetFieldMap0)},
1126 {CC "getObjectSize0", CC "(Ljava/lang/Object;)J", FN_PTR(Unsafe_GetObjectSize0)},
1127
1128 {CC "defineClass0", CC "(" DC_Args ")" CLS, FN_PTR(Unsafe_DefineClass0)},
1129 {CC "allocateInstance", CC "(" CLS ")" OBJ, FN_PTR(Unsafe_AllocateInstance)},
1130 {CC "throwException", CC "(" THR ")V", FN_PTR(Unsafe_ThrowException)},
1131 {CC "compareAndSetReference",CC "(" OBJ "J" OBJ "" OBJ ")Z", FN_PTR(Unsafe_CompareAndSetReference)},
1132 {CC "compareAndSetInt", CC "(" OBJ "J""I""I"")Z", FN_PTR(Unsafe_CompareAndSetInt)},
1133 {CC "compareAndSetLong", CC "(" OBJ "J""J""J"")Z", FN_PTR(Unsafe_CompareAndSetLong)},
1134 {CC "compareAndExchangeReference", CC "(" OBJ "J" OBJ "" OBJ ")" OBJ, FN_PTR(Unsafe_CompareAndExchangeReference)},
1135 {CC "compareAndExchangeInt", CC "(" OBJ "J""I""I"")I", FN_PTR(Unsafe_CompareAndExchangeInt)},
1136 {CC "compareAndExchangeLong", CC "(" OBJ "J""J""J"")J", FN_PTR(Unsafe_CompareAndExchangeLong)},
1137
1138 {CC "park", CC "(ZJ)V", FN_PTR(Unsafe_Park)},
1139 {CC "unpark", CC "(" OBJ ")V", FN_PTR(Unsafe_Unpark)},
1140
1141 {CC "getLoadAverage0", CC "([DI)I", FN_PTR(Unsafe_GetLoadAverage0)},
1142
1143 {CC "copyMemory0", CC "(" OBJ "J" OBJ "JJ)V", FN_PTR(Unsafe_CopyMemory0)},
1144 {CC "copySwapMemory0", CC "(" OBJ "J" OBJ "JJJ)V", FN_PTR(Unsafe_CopySwapMemory0)},
1145 {CC "writeback0", CC "(" "J" ")V", FN_PTR(Unsafe_WriteBack0)},
1146 {CC "writebackPreSync0", CC "()V", FN_PTR(Unsafe_WriteBackPreSync0)},
1147 {CC "writebackPostSync0", CC "()V", FN_PTR(Unsafe_WriteBackPostSync0)},
1148 {CC "setMemory0", CC "(" OBJ "JJB)V", FN_PTR(Unsafe_SetMemory0)},
1149
1150 {CC "shouldBeInitialized0", CC "(" CLS ")Z", FN_PTR(Unsafe_ShouldBeInitialized0)},
1151 {CC "notifyStrictStaticAccess0", CC "(" CLS "JZ)V", FN_PTR(Unsafe_NotifyStrictStaticAccess0)},
1152
1153 {CC "fullFence", CC "()V", FN_PTR(Unsafe_FullFence)},
1154 };
1155
1156 #undef CC
1157 #undef FN_PTR
1158
1159 #undef ADR
1160 #undef LANG
1161 #undef OBJ
1162 #undef CLS
1163 #undef FLD
1164 #undef THR
1165 #undef DC_Args
1166 #undef DAC_Args
1167
1168 #undef DECLARE_GETPUTOOP
1169
1170
1171 // This function is exported, used by NativeLookup.
1172 // The Unsafe_xxx functions above are called only from the interpreter.
1173 // The optimizer looks at names and signatures to recognize
1174 // individual functions.
1175
1176 JVM_ENTRY(void, JVM_RegisterJDKInternalMiscUnsafeMethods(JNIEnv *env, jclass unsafeclass)) {
1177 ThreadToNativeFromVM ttnfv(thread);
1178
1179 int ok = env->RegisterNatives(unsafeclass, jdk_internal_misc_Unsafe_methods, sizeof(jdk_internal_misc_Unsafe_methods)/sizeof(JNINativeMethod));
1180 guarantee(ok == 0, "register jdk.internal.misc.Unsafe natives");
1181 } JVM_END