1 /*
2 * Copyright (c) 2000, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classFileStream.hpp"
27 #include "classfile/classLoader.hpp"
28 #include "classfile/classLoadInfo.hpp"
29 #include "classfile/javaClasses.inline.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "jfr/jfrEvents.hpp"
33 #include "jni.h"
34 #include "jvm.h"
35 #include "memory/allocation.inline.hpp"
36 #include "memory/resourceArea.hpp"
37 #include "oops/access.inline.hpp"
38 #include "oops/fieldStreams.inline.hpp"
39 #include "oops/instanceKlass.inline.hpp"
40 #include "oops/klass.inline.hpp"
41 #include "oops/objArrayOop.inline.hpp"
42 #include "oops/oop.inline.hpp"
43 #include "oops/typeArrayOop.inline.hpp"
44 #include "prims/jvmtiExport.hpp"
45 #include "prims/unsafe.hpp"
46 #include "runtime/globals.hpp"
47 #include "runtime/handles.inline.hpp"
48 #include "runtime/interfaceSupport.inline.hpp"
49 #include "runtime/javaThread.inline.hpp"
50 #include "runtime/jniHandles.inline.hpp"
51 #include "runtime/orderAccess.hpp"
52 #include "runtime/reflection.hpp"
53 #include "runtime/sharedRuntime.hpp"
54 #include "runtime/stubRoutines.hpp"
55 #include "runtime/threadSMR.hpp"
56 #include "runtime/vmOperations.hpp"
57 #include "runtime/vm_version.hpp"
58 #include "sanitizers/ub.hpp"
59 #include "services/threadService.hpp"
60 #include "utilities/align.hpp"
61 #include "utilities/copy.hpp"
62 #include "utilities/dtrace.hpp"
63 #include "utilities/macros.hpp"
64
65 /**
66 * Implementation of the jdk.internal.misc.Unsafe class
67 */
68
69
70 #define MAX_OBJECT_SIZE \
71 ( arrayOopDesc::base_offset_in_bytes(T_DOUBLE) \
72 + ((julong)max_jint * sizeof(double)) )
73
74
75 #define UNSAFE_ENTRY(result_type, header) \
76 JVM_ENTRY(static result_type, header)
77
78 #define UNSAFE_LEAF(result_type, header) \
79 JVM_LEAF(static result_type, header)
80
81 #define UNSAFE_END JVM_END
82
83
84 static inline void* addr_from_java(jlong addr) {
85 // This assert fails in a variety of ways on 32-bit systems.
86 // It is impossible to predict whether native code that converts
87 // pointers to longs will sign-extend or zero-extend the addresses.
88 //assert(addr == (uintptr_t)addr, "must not be odd high bits");
89 return (void*)(uintptr_t)addr;
90 }
91
92 static inline jlong addr_to_java(void* p) {
93 assert(p == (void*)(uintptr_t)p, "must not be odd high bits");
94 return (uintptr_t)p;
95 }
96
97
98 // Note: The VM's obj_field and related accessors use byte-scaled
99 // ("unscaled") offsets, just as the unsafe methods do.
100
101 // However, the method Unsafe.fieldOffset explicitly declines to
102 // guarantee this. The field offset values manipulated by the Java user
103 // through the Unsafe API are opaque cookies that just happen to be byte
104 // offsets. We represent this state of affairs by passing the cookies
105 // through conversion functions when going between the VM and the Unsafe API.
106 // The conversion functions just happen to be no-ops at present.
107
108 static inline jlong field_offset_to_byte_offset(jlong field_offset) {
109 return field_offset;
110 }
111
112 static inline jlong field_offset_from_byte_offset(jlong byte_offset) {
113 return byte_offset;
114 }
115
116 static inline void assert_field_offset_sane(oop p, jlong field_offset) {
117 #ifdef ASSERT
118 jlong byte_offset = field_offset_to_byte_offset(field_offset);
119
120 if (p != nullptr) {
121 assert(byte_offset >= 0 && byte_offset <= (jlong)MAX_OBJECT_SIZE, "sane offset");
122 if (byte_offset == (jint)byte_offset) {
123 void* ptr_plus_disp = cast_from_oop<address>(p) + byte_offset;
124 assert(p->field_addr<void>((jint)byte_offset) == ptr_plus_disp,
125 "raw [ptr+disp] must be consistent with oop::field_addr");
126 }
127 jlong p_size = HeapWordSize * (jlong)(p->size());
128 assert(byte_offset < p_size, "Unsafe access: offset " INT64_FORMAT " > object's size " INT64_FORMAT, (int64_t)byte_offset, (int64_t)p_size);
129 }
130 #endif
131 }
132
133 static inline void* index_oop_from_field_offset_long(oop p, jlong field_offset) {
134 assert_field_offset_sane(p, field_offset);
135 uintptr_t base_address = cast_from_oop<uintptr_t>(p);
136 uintptr_t byte_offset = (uintptr_t)field_offset_to_byte_offset(field_offset);
137 return (void*)(base_address + byte_offset);
138 }
139
140 // Externally callable versions:
141 // (Use these in compiler intrinsics which emulate unsafe primitives.)
142 jlong Unsafe_field_offset_to_byte_offset(jlong field_offset) {
143 return field_offset;
144 }
145 jlong Unsafe_field_offset_from_byte_offset(jlong byte_offset) {
146 return byte_offset;
147 }
148
149
150 ///// Data read/writes on the Java heap and in native (off-heap) memory
151
152 /**
153 * Helper class to wrap memory accesses in JavaThread::doing_unsafe_access()
154 */
155 class GuardUnsafeAccess {
156 JavaThread* _thread;
157
158 public:
159 GuardUnsafeAccess(JavaThread* thread) : _thread(thread) {
160 // native/off-heap access which may raise SIGBUS if accessing
161 // memory mapped file data in a region of the file which has
162 // been truncated and is now invalid.
163 _thread->set_doing_unsafe_access(true);
164 }
165
166 ~GuardUnsafeAccess() {
167 _thread->set_doing_unsafe_access(false);
168 }
169 };
170
171 /**
172 * Helper class for accessing memory.
173 *
174 * Normalizes values and wraps accesses in
175 * JavaThread::doing_unsafe_access() if needed.
176 */
177 template <typename T>
178 class MemoryAccess : StackObj {
179 JavaThread* _thread;
180 oop _obj;
181 ptrdiff_t _offset;
182
183 // Resolves and returns the address of the memory access.
184 // This raw memory access may fault, so we make sure it happens within the
185 // guarded scope by making the access volatile at least. Since the store
186 // of Thread::set_doing_unsafe_access() is also volatile, these accesses
187 // can not be reordered by the compiler. Therefore, if the access triggers
188 // a fault, we will know that Thread::doing_unsafe_access() returns true.
189 volatile T* addr() {
190 void* addr = index_oop_from_field_offset_long(_obj, _offset);
191 return static_cast<volatile T*>(addr);
192 }
193
194 template <typename U>
195 U normalize_for_write(U x) {
196 return x;
197 }
198
199 jboolean normalize_for_write(jboolean x) {
200 return x & 1;
201 }
202
203 template <typename U>
204 U normalize_for_read(U x) {
205 return x;
206 }
207
208 jboolean normalize_for_read(jboolean x) {
209 return x != 0;
210 }
211
212 public:
213 MemoryAccess(JavaThread* thread, jobject obj, jlong offset)
214 : _thread(thread), _obj(JNIHandles::resolve(obj)), _offset((ptrdiff_t)offset) {
215 assert_field_offset_sane(_obj, offset);
216 }
217
218 T get() {
219 GuardUnsafeAccess guard(_thread);
220 return normalize_for_read(*addr());
221 }
222
223 // we use this method at some places for writing to 0 e.g. to cause a crash;
224 // ubsan does not know that this is the desired behavior
225 ATTRIBUTE_NO_UBSAN
226 void put(T x) {
227 GuardUnsafeAccess guard(_thread);
228 *addr() = normalize_for_write(x);
229 }
230
231
232 T get_volatile() {
233 GuardUnsafeAccess guard(_thread);
234 volatile T ret = RawAccess<MO_SEQ_CST>::load(addr());
235 return normalize_for_read(ret);
236 }
237
238 void put_volatile(T x) {
239 GuardUnsafeAccess guard(_thread);
240 RawAccess<MO_SEQ_CST>::store(addr(), normalize_for_write(x));
241 }
242 };
243
244 // These functions allow a null base pointer with an arbitrary address.
245 // But if the base pointer is non-null, the offset should make some sense.
246 // That is, it should be in the range [0, MAX_OBJECT_SIZE].
247 UNSAFE_ENTRY(jobject, Unsafe_GetReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
248 oop p = JNIHandles::resolve(obj);
249 assert_field_offset_sane(p, offset);
250 oop v = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_load_at(p, offset);
251 return JNIHandles::make_local(THREAD, v);
252 } UNSAFE_END
253
254 UNSAFE_ENTRY(void, Unsafe_PutReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
255 oop x = JNIHandles::resolve(x_h);
256 oop p = JNIHandles::resolve(obj);
257 assert_field_offset_sane(p, offset);
258 HeapAccess<ON_UNKNOWN_OOP_REF>::oop_store_at(p, offset, x);
259 } UNSAFE_END
260
261 UNSAFE_ENTRY(jobject, Unsafe_GetReferenceVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
262 oop p = JNIHandles::resolve(obj);
263 assert_field_offset_sane(p, offset);
264 oop v = HeapAccess<MO_SEQ_CST | ON_UNKNOWN_OOP_REF>::oop_load_at(p, offset);
265 return JNIHandles::make_local(THREAD, v);
266 } UNSAFE_END
267
268 UNSAFE_ENTRY(void, Unsafe_PutReferenceVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
269 oop x = JNIHandles::resolve(x_h);
270 oop p = JNIHandles::resolve(obj);
271 assert_field_offset_sane(p, offset);
272 HeapAccess<MO_SEQ_CST | ON_UNKNOWN_OOP_REF>::oop_store_at(p, offset, x);
273 } UNSAFE_END
274
275 UNSAFE_ENTRY(jobject, Unsafe_GetUncompressedObject(JNIEnv *env, jobject unsafe, jlong addr)) {
276 oop v = *(oop*) (address) addr;
277 return JNIHandles::make_local(THREAD, v);
278 } UNSAFE_END
279
280 #define DEFINE_GETSETOOP(java_type, Type) \
281 \
282 UNSAFE_ENTRY(java_type, Unsafe_Get##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
283 return MemoryAccess<java_type>(thread, obj, offset).get(); \
284 } UNSAFE_END \
285 \
286 UNSAFE_ENTRY(void, Unsafe_Put##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
287 MemoryAccess<java_type>(thread, obj, offset).put(x); \
288 } UNSAFE_END \
289 \
290 // END DEFINE_GETSETOOP.
291
292 DEFINE_GETSETOOP(jboolean, Boolean)
293 DEFINE_GETSETOOP(jbyte, Byte)
294 DEFINE_GETSETOOP(jshort, Short);
295 DEFINE_GETSETOOP(jchar, Char);
296 DEFINE_GETSETOOP(jint, Int);
297 DEFINE_GETSETOOP(jlong, Long);
298 DEFINE_GETSETOOP(jfloat, Float);
299 DEFINE_GETSETOOP(jdouble, Double);
300
301 #undef DEFINE_GETSETOOP
302
303 #define DEFINE_GETSETOOP_VOLATILE(java_type, Type) \
304 \
305 UNSAFE_ENTRY(java_type, Unsafe_Get##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
306 return MemoryAccess<java_type>(thread, obj, offset).get_volatile(); \
307 } UNSAFE_END \
308 \
309 UNSAFE_ENTRY(void, Unsafe_Put##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
310 MemoryAccess<java_type>(thread, obj, offset).put_volatile(x); \
311 } UNSAFE_END \
312 \
313 // END DEFINE_GETSETOOP_VOLATILE.
314
315 DEFINE_GETSETOOP_VOLATILE(jboolean, Boolean)
316 DEFINE_GETSETOOP_VOLATILE(jbyte, Byte)
317 DEFINE_GETSETOOP_VOLATILE(jshort, Short);
318 DEFINE_GETSETOOP_VOLATILE(jchar, Char);
319 DEFINE_GETSETOOP_VOLATILE(jint, Int);
320 DEFINE_GETSETOOP_VOLATILE(jlong, Long);
321 DEFINE_GETSETOOP_VOLATILE(jfloat, Float);
322 DEFINE_GETSETOOP_VOLATILE(jdouble, Double);
323
324 #undef DEFINE_GETSETOOP_VOLATILE
325
326 UNSAFE_LEAF(void, Unsafe_FullFence(JNIEnv *env, jobject unsafe)) {
327 OrderAccess::fence();
328 } UNSAFE_END
329
330 ////// Allocation requests
331
332 UNSAFE_ENTRY(jobject, Unsafe_AllocateInstance(JNIEnv *env, jobject unsafe, jclass cls)) {
333 JvmtiVMObjectAllocEventCollector oam;
334 instanceOop i = InstanceKlass::allocate_instance(JNIHandles::resolve_non_null(cls), CHECK_NULL);
335 return JNIHandles::make_local(THREAD, i);
336 } UNSAFE_END
337
338 UNSAFE_ENTRY(jlong, Unsafe_AllocateMemory0(JNIEnv *env, jobject unsafe, jlong size)) {
339 size_t sz = (size_t)size;
340
341 assert(is_aligned(sz, HeapWordSize), "sz not aligned");
342
343 void* x = os::malloc(sz, mtOther);
344
345 return addr_to_java(x);
346 } UNSAFE_END
347
348 UNSAFE_ENTRY(jlong, Unsafe_ReallocateMemory0(JNIEnv *env, jobject unsafe, jlong addr, jlong size)) {
349 void* p = addr_from_java(addr);
350 size_t sz = (size_t)size;
351
352 assert(is_aligned(sz, HeapWordSize), "sz not aligned");
353
354 void* x = os::realloc(p, sz, mtOther);
355
356 return addr_to_java(x);
357 } UNSAFE_END
358
359 UNSAFE_ENTRY(void, Unsafe_FreeMemory0(JNIEnv *env, jobject unsafe, jlong addr)) {
360 void* p = addr_from_java(addr);
361
362 os::free(p);
363 } UNSAFE_END
364
365 UNSAFE_ENTRY(void, Unsafe_SetMemory0(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong size, jbyte value)) {
366 size_t sz = (size_t)size;
367
368 oop base = JNIHandles::resolve(obj);
369 void* p = index_oop_from_field_offset_long(base, offset);
370
371 Copy::fill_to_memory_atomic(p, sz, value);
372 } UNSAFE_END
373
374 UNSAFE_ENTRY(void, Unsafe_CopyMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size)) {
375 size_t sz = (size_t)size;
376
377 oop srcp = JNIHandles::resolve(srcObj);
378 oop dstp = JNIHandles::resolve(dstObj);
379
380 void* src = index_oop_from_field_offset_long(srcp, srcOffset);
381 void* dst = index_oop_from_field_offset_long(dstp, dstOffset);
382 {
383 GuardUnsafeAccess guard(thread);
384 if (StubRoutines::unsafe_arraycopy() != nullptr) {
385 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXExec, thread));
386 StubRoutines::UnsafeArrayCopy_stub()(src, dst, sz);
387 } else {
388 Copy::conjoint_memory_atomic(src, dst, sz);
389 }
390 }
391 } UNSAFE_END
392
393 // This function is a leaf since if the source and destination are both in native memory
394 // the copy may potentially be very large, and we don't want to disable GC if we can avoid it.
395 // If either source or destination (or both) are on the heap, the function will enter VM using
396 // JVM_ENTRY_FROM_LEAF
397 UNSAFE_LEAF(void, Unsafe_CopySwapMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size, jlong elemSize)) {
398 size_t sz = (size_t)size;
399 size_t esz = (size_t)elemSize;
400
401 if (srcObj == nullptr && dstObj == nullptr) {
402 // Both src & dst are in native memory
403 address src = (address)srcOffset;
404 address dst = (address)dstOffset;
405
406 {
407 JavaThread* thread = JavaThread::thread_from_jni_environment(env);
408 GuardUnsafeAccess guard(thread);
409 Copy::conjoint_swap(src, dst, sz, esz);
410 }
411 } else {
412 // At least one of src/dst are on heap, transition to VM to access raw pointers
413
414 JVM_ENTRY_FROM_LEAF(env, void, Unsafe_CopySwapMemory0) {
415 oop srcp = JNIHandles::resolve(srcObj);
416 oop dstp = JNIHandles::resolve(dstObj);
417
418 address src = (address)index_oop_from_field_offset_long(srcp, srcOffset);
419 address dst = (address)index_oop_from_field_offset_long(dstp, dstOffset);
420
421 {
422 GuardUnsafeAccess guard(thread);
423 Copy::conjoint_swap(src, dst, sz, esz);
424 }
425 } JVM_END
426 }
427 } UNSAFE_END
428
429 UNSAFE_LEAF (void, Unsafe_WriteBack0(JNIEnv *env, jobject unsafe, jlong line)) {
430 assert(VM_Version::supports_data_cache_line_flush(), "should not get here");
431 #ifdef ASSERT
432 if (TraceMemoryWriteback) {
433 tty->print_cr("Unsafe: writeback 0x%p", addr_from_java(line));
434 }
435 #endif
436
437 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXExec, Thread::current()));
438 assert(StubRoutines::data_cache_writeback() != nullptr, "sanity");
439 (StubRoutines::DataCacheWriteback_stub())(addr_from_java(line));
440 } UNSAFE_END
441
442 static void doWriteBackSync0(bool is_pre)
443 {
444 MACOS_AARCH64_ONLY(ThreadWXEnable wx(WXExec, Thread::current()));
445 assert(StubRoutines::data_cache_writeback_sync() != nullptr, "sanity");
446 (StubRoutines::DataCacheWritebackSync_stub())(is_pre);
447 }
448
449 UNSAFE_LEAF (void, Unsafe_WriteBackPreSync0(JNIEnv *env, jobject unsafe)) {
450 assert(VM_Version::supports_data_cache_line_flush(), "should not get here");
451 #ifdef ASSERT
452 if (TraceMemoryWriteback) {
453 tty->print_cr("Unsafe: writeback pre-sync");
454 }
455 #endif
456
457 doWriteBackSync0(true);
458 } UNSAFE_END
459
460 UNSAFE_LEAF (void, Unsafe_WriteBackPostSync0(JNIEnv *env, jobject unsafe)) {
461 assert(VM_Version::supports_data_cache_line_flush(), "should not get here");
462 #ifdef ASSERT
463 if (TraceMemoryWriteback) {
464 tty->print_cr("Unsafe: writeback pre-sync");
465 }
466 #endif
467
468 doWriteBackSync0(false);
469 } UNSAFE_END
470
471 ////// Random queries
472
473 static jlong find_field_offset(jclass clazz, jstring name, TRAPS) {
474 assert(clazz != nullptr, "clazz must not be null");
475 assert(name != nullptr, "name must not be null");
476
477 ResourceMark rm(THREAD);
478 char *utf_name = java_lang_String::as_utf8_string(JNIHandles::resolve_non_null(name));
479
480 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(JNIHandles::resolve_non_null(clazz)));
481
482 jint offset = -1;
483 for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
484 Symbol *name = fs.name();
485 if (name->equals(utf_name)) {
486 offset = fs.offset();
487 break;
488 }
489 }
490 if (offset < 0) {
491 THROW_0(vmSymbols::java_lang_InternalError());
492 }
493 return field_offset_from_byte_offset(offset);
494 }
495
496 static jlong find_field_offset(jobject field, int must_be_static, TRAPS) {
497 assert(field != nullptr, "field must not be null");
498
499 oop reflected = JNIHandles::resolve_non_null(field);
500 oop mirror = java_lang_reflect_Field::clazz(reflected);
501 Klass* k = java_lang_Class::as_Klass(mirror);
502 int slot = java_lang_reflect_Field::slot(reflected);
503 int modifiers = java_lang_reflect_Field::modifiers(reflected);
504
505 if (must_be_static >= 0) {
506 int really_is_static = ((modifiers & JVM_ACC_STATIC) != 0);
507 if (must_be_static != really_is_static) {
508 THROW_0(vmSymbols::java_lang_IllegalArgumentException());
509 }
510 }
511
512 int offset = InstanceKlass::cast(k)->field_offset(slot);
513 return field_offset_from_byte_offset(offset);
514 }
515
516 UNSAFE_ENTRY(jlong, Unsafe_ObjectFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
517 return find_field_offset(field, 0, THREAD);
518 } UNSAFE_END
519
520 UNSAFE_ENTRY(jlong, Unsafe_ObjectFieldOffset1(JNIEnv *env, jobject unsafe, jclass c, jstring name)) {
521 return find_field_offset(c, name, THREAD);
522 } UNSAFE_END
523
524 UNSAFE_ENTRY(jlong, Unsafe_StaticFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
525 return find_field_offset(field, 1, THREAD);
526 } UNSAFE_END
527
528 UNSAFE_ENTRY(jobject, Unsafe_StaticFieldBase0(JNIEnv *env, jobject unsafe, jobject field)) {
529 assert(field != nullptr, "field must not be null");
530
531 // Note: In this VM implementation, a field address is always a short
532 // offset from the base of a klass metaobject. Thus, the full dynamic
533 // range of the return type is never used. However, some implementations
534 // might put the static field inside an array shared by many classes,
535 // or even at a fixed address, in which case the address could be quite
536 // large. In that last case, this function would return null, since
537 // the address would operate alone, without any base pointer.
538
539 oop reflected = JNIHandles::resolve_non_null(field);
540 oop mirror = java_lang_reflect_Field::clazz(reflected);
541 int modifiers = java_lang_reflect_Field::modifiers(reflected);
542
543 if ((modifiers & JVM_ACC_STATIC) == 0) {
544 THROW_0(vmSymbols::java_lang_IllegalArgumentException());
545 }
546
547 return JNIHandles::make_local(THREAD, mirror);
548 } UNSAFE_END
549
550 UNSAFE_ENTRY(void, Unsafe_EnsureClassInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
551 assert(clazz != nullptr, "clazz must not be null");
552
553 oop mirror = JNIHandles::resolve_non_null(clazz);
554
555 Klass* klass = java_lang_Class::as_Klass(mirror);
556 if (klass != nullptr && klass->should_be_initialized()) {
557 InstanceKlass* k = InstanceKlass::cast(klass);
558 k->initialize(CHECK);
559 }
560 }
561 UNSAFE_END
562
563 UNSAFE_ENTRY(jboolean, Unsafe_ShouldBeInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
564 assert(clazz != nullptr, "clazz must not be null");
565
566 oop mirror = JNIHandles::resolve_non_null(clazz);
567 Klass* klass = java_lang_Class::as_Klass(mirror);
568
569 if (klass != nullptr && klass->should_be_initialized()) {
570 return true;
571 }
572
573 return false;
574 }
575 UNSAFE_END
576
577 static void getBaseAndScale(int& base, int& scale, jclass clazz, TRAPS) {
578 assert(clazz != nullptr, "clazz must not be null");
579
580 oop mirror = JNIHandles::resolve_non_null(clazz);
581 Klass* k = java_lang_Class::as_Klass(mirror);
582
583 if (k == nullptr || !k->is_array_klass()) {
584 THROW(vmSymbols::java_lang_InvalidClassException());
585 } else if (k->is_objArray_klass()) {
586 base = arrayOopDesc::base_offset_in_bytes(T_OBJECT);
587 scale = heapOopSize;
588 } else if (k->is_typeArray_klass()) {
589 TypeArrayKlass* tak = TypeArrayKlass::cast(k);
590 base = tak->array_header_in_bytes();
591 assert(base == arrayOopDesc::base_offset_in_bytes(tak->element_type()), "array_header_size semantics ok");
592 scale = (1 << tak->log2_element_size());
593 } else {
594 ShouldNotReachHere();
595 }
596 }
597
598 UNSAFE_ENTRY(jint, Unsafe_ArrayBaseOffset0(JNIEnv *env, jobject unsafe, jclass clazz)) {
599 int base = 0, scale = 0;
600 getBaseAndScale(base, scale, clazz, CHECK_0);
601
602 return field_offset_from_byte_offset(base);
603 } UNSAFE_END
604
605
606 UNSAFE_ENTRY(jint, Unsafe_ArrayIndexScale0(JNIEnv *env, jobject unsafe, jclass clazz)) {
607 int base = 0, scale = 0;
608 getBaseAndScale(base, scale, clazz, CHECK_0);
609
610 // This VM packs both fields and array elements down to the byte.
611 // But watch out: If this changes, so that array references for
612 // a given primitive type (say, T_BOOLEAN) use different memory units
613 // than fields, this method MUST return zero for such arrays.
614 // For example, the VM used to store sub-word sized fields in full
615 // words in the object layout, so that accessors like getByte(Object,int)
616 // did not really do what one might expect for arrays. Therefore,
617 // this function used to report a zero scale factor, so that the user
618 // would know not to attempt to access sub-word array elements.
619 // // Code for unpacked fields:
620 // if (scale < wordSize) return 0;
621
622 // The following allows for a pretty general fieldOffset cookie scheme,
623 // but requires it to be linear in byte offset.
624 return field_offset_from_byte_offset(scale) - field_offset_from_byte_offset(0);
625 } UNSAFE_END
626
627
628 static inline void throw_new(JNIEnv *env, const char *ename) {
629 jclass cls = env->FindClass(ename);
630 if (env->ExceptionCheck()) {
631 env->ExceptionClear();
632 tty->print_cr("Unsafe: cannot throw %s because FindClass has failed", ename);
633 return;
634 }
635
636 env->ThrowNew(cls, nullptr);
637 }
638
639 static jclass Unsafe_DefineClass_impl(JNIEnv *env, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd) {
640 // Code lifted from JDK 1.3 ClassLoader.c
641
642 jbyte *body;
643 char *utfName = nullptr;
644 jclass result = 0;
645 char buf[128];
646
647 assert(data != nullptr, "Class bytes must not be null");
648 assert(length >= 0, "length must not be negative: %d", length);
649
650 if (UsePerfData) {
651 ClassLoader::unsafe_defineClassCallCounter()->inc();
652 }
653
654 body = NEW_C_HEAP_ARRAY_RETURN_NULL(jbyte, length, mtInternal);
655 if (body == nullptr) {
656 throw_new(env, "java/lang/OutOfMemoryError");
657 return 0;
658 }
659
660 env->GetByteArrayRegion(data, offset, length, body);
661 if (env->ExceptionOccurred()) {
662 goto free_body;
663 }
664
665 if (name != nullptr) {
666 uint len = env->GetStringUTFLength(name);
667 int unicode_len = env->GetStringLength(name);
668
669 if (len >= sizeof(buf)) {
670 utfName = NEW_C_HEAP_ARRAY_RETURN_NULL(char, len + 1, mtInternal);
671 if (utfName == nullptr) {
672 throw_new(env, "java/lang/OutOfMemoryError");
673 goto free_body;
674 }
675 } else {
676 utfName = buf;
677 }
678
679 env->GetStringUTFRegion(name, 0, unicode_len, utfName);
680
681 for (uint i = 0; i < len; i++) {
682 if (utfName[i] == '.') utfName[i] = '/';
683 }
684 }
685
686 result = JVM_DefineClass(env, utfName, loader, body, length, pd);
687
688 if (utfName && utfName != buf) {
689 FREE_C_HEAP_ARRAY(char, utfName);
690 }
691
692 free_body:
693 FREE_C_HEAP_ARRAY(jbyte, body);
694 return result;
695 }
696
697
698 UNSAFE_ENTRY(jclass, Unsafe_DefineClass0(JNIEnv *env, jobject unsafe, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd)) {
699 ThreadToNativeFromVM ttnfv(thread);
700
701 return Unsafe_DefineClass_impl(env, name, data, offset, length, loader, pd);
702 } UNSAFE_END
703
704
705 UNSAFE_ENTRY(void, Unsafe_ThrowException(JNIEnv *env, jobject unsafe, jthrowable thr)) {
706 ThreadToNativeFromVM ttnfv(thread);
707 env->Throw(thr);
708 } UNSAFE_END
709
710 // JSR166 ------------------------------------------------------------------
711
712 UNSAFE_ENTRY(jobject, Unsafe_CompareAndExchangeReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
713 oop x = JNIHandles::resolve(x_h);
714 oop e = JNIHandles::resolve(e_h);
715 oop p = JNIHandles::resolve(obj);
716 assert_field_offset_sane(p, offset);
717 oop res = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_atomic_cmpxchg_at(p, (ptrdiff_t)offset, e, x);
718 return JNIHandles::make_local(THREAD, res);
719 } UNSAFE_END
720
721 UNSAFE_ENTRY(jint, Unsafe_CompareAndExchangeInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
722 oop p = JNIHandles::resolve(obj);
723 volatile jint* addr = (volatile jint*)index_oop_from_field_offset_long(p, offset);
724 return Atomic::cmpxchg(addr, e, x);
725 } UNSAFE_END
726
727 UNSAFE_ENTRY(jlong, Unsafe_CompareAndExchangeLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
728 oop p = JNIHandles::resolve(obj);
729 volatile jlong* addr = (volatile jlong*)index_oop_from_field_offset_long(p, offset);
730 return Atomic::cmpxchg(addr, e, x);
731 } UNSAFE_END
732
733 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetReference(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
734 oop x = JNIHandles::resolve(x_h);
735 oop e = JNIHandles::resolve(e_h);
736 oop p = JNIHandles::resolve(obj);
737 assert_field_offset_sane(p, offset);
738 oop ret = HeapAccess<ON_UNKNOWN_OOP_REF>::oop_atomic_cmpxchg_at(p, (ptrdiff_t)offset, e, x);
739 return ret == e;
740 } UNSAFE_END
741
742 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
743 oop p = JNIHandles::resolve(obj);
744 volatile jint* addr = (volatile jint*)index_oop_from_field_offset_long(p, offset);
745 return Atomic::cmpxchg(addr, e, x) == e;
746 } UNSAFE_END
747
748 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
749 oop p = JNIHandles::resolve(obj);
750 volatile jlong* addr = (volatile jlong*)index_oop_from_field_offset_long(p, offset);
751 return Atomic::cmpxchg(addr, e, x) == e;
752 } UNSAFE_END
753
754 static void post_thread_park_event(EventThreadPark* event, const oop obj, jlong timeout_nanos, jlong until_epoch_millis) {
755 assert(event != nullptr, "invariant");
756 event->set_parkedClass((obj != nullptr) ? obj->klass() : nullptr);
757 event->set_timeout(timeout_nanos);
758 event->set_until(until_epoch_millis);
759 event->set_address((obj != nullptr) ? (u8)cast_from_oop<uintptr_t>(obj) : 0);
760 event->commit();
761 }
762
763 UNSAFE_ENTRY(void, Unsafe_Park(JNIEnv *env, jobject unsafe, jboolean isAbsolute, jlong time)) {
764 HOTSPOT_THREAD_PARK_BEGIN((uintptr_t) thread->parker(), (int) isAbsolute, time);
765 EventThreadPark event;
766
767 JavaThreadParkedState jtps(thread, time != 0);
768 thread->parker()->park(isAbsolute != 0, time);
769 if (event.should_commit()) {
770 const oop obj = thread->current_park_blocker();
771 if (time == 0) {
772 post_thread_park_event(&event, obj, min_jlong, min_jlong);
773 } else {
774 if (isAbsolute != 0) {
775 post_thread_park_event(&event, obj, min_jlong, time);
776 } else {
777 post_thread_park_event(&event, obj, time, min_jlong);
778 }
779 }
780 }
781 HOTSPOT_THREAD_PARK_END((uintptr_t) thread->parker());
782 } UNSAFE_END
783
784 UNSAFE_ENTRY(void, Unsafe_Unpark(JNIEnv *env, jobject unsafe, jobject jthread)) {
785 if (jthread != nullptr) {
786 oop thread_oop = JNIHandles::resolve_non_null(jthread);
787 // Get the JavaThread* stored in the java.lang.Thread object _before_
788 // the embedded ThreadsListHandle is constructed so we know if the
789 // early life stage of the JavaThread* is protected. We use acquire
790 // here to ensure that if we see a non-nullptr value, then we also
791 // see the main ThreadsList updates from the JavaThread* being added.
792 FastThreadsListHandle ftlh(thread_oop, java_lang_Thread::thread_acquire(thread_oop));
793 JavaThread* thr = ftlh.protected_java_thread();
794 if (thr != nullptr) {
795 // The still live JavaThread* is protected by the FastThreadsListHandle
796 // so it is safe to access.
797 Parker* p = thr->parker();
798 HOTSPOT_THREAD_UNPARK((uintptr_t) p);
799 p->unpark();
800 }
801 } // FastThreadsListHandle is destroyed here.
802 } UNSAFE_END
803
804 UNSAFE_ENTRY(jint, Unsafe_GetLoadAverage0(JNIEnv *env, jobject unsafe, jdoubleArray loadavg, jint nelem)) {
805 const int max_nelem = 3;
806 double la[max_nelem];
807 jint ret;
808
809 typeArrayOop a = typeArrayOop(JNIHandles::resolve_non_null(loadavg));
810 assert(a->is_typeArray(), "must be type array");
811
812 ret = os::loadavg(la, nelem);
813 if (ret == -1) {
814 return -1;
815 }
816
817 // if successful, ret is the number of samples actually retrieved.
818 assert(ret >= 0 && ret <= max_nelem, "Unexpected loadavg return value");
819 switch(ret) {
820 case 3: a->double_at_put(2, (jdouble)la[2]); // fall through
821 case 2: a->double_at_put(1, (jdouble)la[1]); // fall through
822 case 1: a->double_at_put(0, (jdouble)la[0]); break;
823 }
824
825 return ret;
826 } UNSAFE_END
827
828
829 /// JVM_RegisterUnsafeMethods
830
831 #define ADR "J"
832
833 #define LANG "Ljava/lang/"
834
835 #define OBJ LANG "Object;"
836 #define CLS LANG "Class;"
837 #define FLD LANG "reflect/Field;"
838 #define THR LANG "Throwable;"
839
840 #define DC_Args LANG "String;[BII" LANG "ClassLoader;" "Ljava/security/ProtectionDomain;"
841 #define DAC_Args CLS "[B[" OBJ
842
843 #define CC (char*) /*cast a literal from (const char*)*/
844 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
845
846 #define DECLARE_GETPUTOOP(Type, Desc) \
847 {CC "get" #Type, CC "(" OBJ "J)" #Desc, FN_PTR(Unsafe_Get##Type)}, \
848 {CC "put" #Type, CC "(" OBJ "J" #Desc ")V", FN_PTR(Unsafe_Put##Type)}, \
849 {CC "get" #Type "Volatile", CC "(" OBJ "J)" #Desc, FN_PTR(Unsafe_Get##Type##Volatile)}, \
850 {CC "put" #Type "Volatile", CC "(" OBJ "J" #Desc ")V", FN_PTR(Unsafe_Put##Type##Volatile)}
851
852
853 static JNINativeMethod jdk_internal_misc_Unsafe_methods[] = {
854 {CC "getReference", CC "(" OBJ "J)" OBJ "", FN_PTR(Unsafe_GetReference)},
855 {CC "putReference", CC "(" OBJ "J" OBJ ")V", FN_PTR(Unsafe_PutReference)},
856 {CC "getReferenceVolatile", CC "(" OBJ "J)" OBJ, FN_PTR(Unsafe_GetReferenceVolatile)},
857 {CC "putReferenceVolatile", CC "(" OBJ "J" OBJ ")V", FN_PTR(Unsafe_PutReferenceVolatile)},
858
859 {CC "getUncompressedObject", CC "(" ADR ")" OBJ, FN_PTR(Unsafe_GetUncompressedObject)},
860
861 DECLARE_GETPUTOOP(Boolean, Z),
862 DECLARE_GETPUTOOP(Byte, B),
863 DECLARE_GETPUTOOP(Short, S),
864 DECLARE_GETPUTOOP(Char, C),
865 DECLARE_GETPUTOOP(Int, I),
866 DECLARE_GETPUTOOP(Long, J),
867 DECLARE_GETPUTOOP(Float, F),
868 DECLARE_GETPUTOOP(Double, D),
869
870 {CC "allocateMemory0", CC "(J)" ADR, FN_PTR(Unsafe_AllocateMemory0)},
871 {CC "reallocateMemory0", CC "(" ADR "J)" ADR, FN_PTR(Unsafe_ReallocateMemory0)},
872 {CC "freeMemory0", CC "(" ADR ")V", FN_PTR(Unsafe_FreeMemory0)},
873
874 {CC "objectFieldOffset0", CC "(" FLD ")J", FN_PTR(Unsafe_ObjectFieldOffset0)},
875 {CC "objectFieldOffset1", CC "(" CLS LANG "String;)J", FN_PTR(Unsafe_ObjectFieldOffset1)},
876 {CC "staticFieldOffset0", CC "(" FLD ")J", FN_PTR(Unsafe_StaticFieldOffset0)},
877 {CC "staticFieldBase0", CC "(" FLD ")" OBJ, FN_PTR(Unsafe_StaticFieldBase0)},
878 {CC "ensureClassInitialized0", CC "(" CLS ")V", FN_PTR(Unsafe_EnsureClassInitialized0)},
879 {CC "arrayBaseOffset0", CC "(" CLS ")I", FN_PTR(Unsafe_ArrayBaseOffset0)},
880 {CC "arrayIndexScale0", CC "(" CLS ")I", FN_PTR(Unsafe_ArrayIndexScale0)},
881
882 {CC "defineClass0", CC "(" DC_Args ")" CLS, FN_PTR(Unsafe_DefineClass0)},
883 {CC "allocateInstance", CC "(" CLS ")" OBJ, FN_PTR(Unsafe_AllocateInstance)},
884 {CC "throwException", CC "(" THR ")V", FN_PTR(Unsafe_ThrowException)},
885 {CC "compareAndSetReference",CC "(" OBJ "J" OBJ "" OBJ ")Z", FN_PTR(Unsafe_CompareAndSetReference)},
886 {CC "compareAndSetInt", CC "(" OBJ "J""I""I"")Z", FN_PTR(Unsafe_CompareAndSetInt)},
887 {CC "compareAndSetLong", CC "(" OBJ "J""J""J"")Z", FN_PTR(Unsafe_CompareAndSetLong)},
888 {CC "compareAndExchangeReference", CC "(" OBJ "J" OBJ "" OBJ ")" OBJ, FN_PTR(Unsafe_CompareAndExchangeReference)},
889 {CC "compareAndExchangeInt", CC "(" OBJ "J""I""I"")I", FN_PTR(Unsafe_CompareAndExchangeInt)},
890 {CC "compareAndExchangeLong", CC "(" OBJ "J""J""J"")J", FN_PTR(Unsafe_CompareAndExchangeLong)},
891
892 {CC "park", CC "(ZJ)V", FN_PTR(Unsafe_Park)},
893 {CC "unpark", CC "(" OBJ ")V", FN_PTR(Unsafe_Unpark)},
894
895 {CC "getLoadAverage0", CC "([DI)I", FN_PTR(Unsafe_GetLoadAverage0)},
896
897 {CC "copyMemory0", CC "(" OBJ "J" OBJ "JJ)V", FN_PTR(Unsafe_CopyMemory0)},
898 {CC "copySwapMemory0", CC "(" OBJ "J" OBJ "JJJ)V", FN_PTR(Unsafe_CopySwapMemory0)},
899 {CC "writeback0", CC "(" "J" ")V", FN_PTR(Unsafe_WriteBack0)},
900 {CC "writebackPreSync0", CC "()V", FN_PTR(Unsafe_WriteBackPreSync0)},
901 {CC "writebackPostSync0", CC "()V", FN_PTR(Unsafe_WriteBackPostSync0)},
902 {CC "setMemory0", CC "(" OBJ "JJB)V", FN_PTR(Unsafe_SetMemory0)},
903
904 {CC "shouldBeInitialized0", CC "(" CLS ")Z", FN_PTR(Unsafe_ShouldBeInitialized0)},
905
906 {CC "fullFence", CC "()V", FN_PTR(Unsafe_FullFence)},
907 };
908
909 #undef CC
910 #undef FN_PTR
911
912 #undef ADR
913 #undef LANG
914 #undef OBJ
915 #undef CLS
916 #undef FLD
917 #undef THR
918 #undef DC_Args
919 #undef DAC_Args
920
921 #undef DECLARE_GETPUTOOP
922
923
924 // This function is exported, used by NativeLookup.
925 // The Unsafe_xxx functions above are called only from the interpreter.
926 // The optimizer looks at names and signatures to recognize
927 // individual functions.
928
929 JVM_ENTRY(void, JVM_RegisterJDKInternalMiscUnsafeMethods(JNIEnv *env, jclass unsafeclass)) {
930 ThreadToNativeFromVM ttnfv(thread);
931
932 int ok = env->RegisterNatives(unsafeclass, jdk_internal_misc_Unsafe_methods, sizeof(jdk_internal_misc_Unsafe_methods)/sizeof(JNINativeMethod));
933 guarantee(ok == 0, "register jdk.internal.misc.Unsafe natives");
934 } JVM_END