1 /*
2 * Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classFileStream.hpp"
27 #include "classfile/vmSymbols.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/fieldStreams.hpp"
31 #include "oops/objArrayOop.inline.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "prims/jni.h"
34 #include "prims/jvm.h"
35 #include "prims/unsafe.hpp"
36 #include "runtime/atomic.hpp"
37 #include "runtime/globals.hpp"
38 #include "runtime/interfaceSupport.hpp"
39 #include "runtime/orderAccess.inline.hpp"
40 #include "runtime/reflection.hpp"
41 #include "runtime/vm_version.hpp"
42 #include "services/threadService.hpp"
43 #include "trace/tracing.hpp"
44 #include "utilities/align.hpp"
45 #include "utilities/copy.hpp"
46 #include "utilities/dtrace.hpp"
47 #include "utilities/macros.hpp"
48 #if INCLUDE_ALL_GCS
49 #include "gc/g1/g1SATBCardTableModRefBS.hpp"
50 #endif // INCLUDE_ALL_GCS
51
52 /**
53 * Implementation of the jdk.internal.misc.Unsafe class
54 */
55
56
57 #define MAX_OBJECT_SIZE \
58 ( arrayOopDesc::header_size(T_DOUBLE) * HeapWordSize \
59 + ((julong)max_jint * sizeof(double)) )
60
61
62 #define UNSAFE_ENTRY(result_type, header) \
63 JVM_ENTRY(static result_type, header)
64
65 #define UNSAFE_LEAF(result_type, header) \
66 JVM_LEAF(static result_type, header)
67
68 #define UNSAFE_END JVM_END
69
70
71 static inline void* addr_from_java(jlong addr) {
72 // This assert fails in a variety of ways on 32-bit systems.
73 // It is impossible to predict whether native code that converts
74 // pointers to longs will sign-extend or zero-extend the addresses.
75 //assert(addr == (uintptr_t)addr, "must not be odd high bits");
76 return (void*)(uintptr_t)addr;
77 }
78
79 static inline jlong addr_to_java(void* p) {
80 assert(p == (void*)(uintptr_t)p, "must not be odd high bits");
81 return (uintptr_t)p;
82 }
83
84
85 // Note: The VM's obj_field and related accessors use byte-scaled
86 // ("unscaled") offsets, just as the unsafe methods do.
87
88 // However, the method Unsafe.fieldOffset explicitly declines to
89 // guarantee this. The field offset values manipulated by the Java user
90 // through the Unsafe API are opaque cookies that just happen to be byte
91 // offsets. We represent this state of affairs by passing the cookies
92 // through conversion functions when going between the VM and the Unsafe API.
93 // The conversion functions just happen to be no-ops at present.
94
95 static inline jlong field_offset_to_byte_offset(jlong field_offset) {
96 return field_offset;
97 }
98
99 static inline jlong field_offset_from_byte_offset(jlong byte_offset) {
100 return byte_offset;
101 }
102
103 static inline void* index_oop_from_field_offset_long(oop p, jlong field_offset) {
104 jlong byte_offset = field_offset_to_byte_offset(field_offset);
105
106 #ifdef ASSERT
107 if (p != NULL) {
108 assert(byte_offset >= 0 && byte_offset <= (jlong)MAX_OBJECT_SIZE, "sane offset");
109 if (byte_offset == (jint)byte_offset) {
110 void* ptr_plus_disp = (address)p + byte_offset;
111 assert((void*)p->obj_field_addr<oop>((jint)byte_offset) == ptr_plus_disp,
112 "raw [ptr+disp] must be consistent with oop::field_base");
113 }
114 jlong p_size = HeapWordSize * (jlong)(p->size());
115 assert(byte_offset < p_size, "Unsafe access: offset " INT64_FORMAT " > object's size " INT64_FORMAT, (int64_t)byte_offset, (int64_t)p_size);
116 }
117 #endif
118
119 if (sizeof(char*) == sizeof(jint)) { // (this constant folds!)
120 return (address)p + (jint) byte_offset;
121 } else {
122 return (address)p + byte_offset;
123 }
124 }
125
126 // Externally callable versions:
127 // (Use these in compiler intrinsics which emulate unsafe primitives.)
128 jlong Unsafe_field_offset_to_byte_offset(jlong field_offset) {
129 return field_offset;
130 }
131 jlong Unsafe_field_offset_from_byte_offset(jlong byte_offset) {
132 return byte_offset;
133 }
134
135
136 ///// Data read/writes on the Java heap and in native (off-heap) memory
137
138 /**
139 * Helper class for accessing memory.
140 *
141 * Normalizes values and wraps accesses in
142 * JavaThread::doing_unsafe_access() if needed.
143 */
144 class MemoryAccess : StackObj {
145 JavaThread* _thread;
146 jobject _obj;
147 jlong _offset;
148
149 // Resolves and returns the address of the memory access
150 void* get_addr() {
151 return index_oop_from_field_offset_long(oopDesc::bs()->read_barrier(JNIHandles::resolve(_obj)), _offset);
152 }
153
154 void* put_addr() {
155 return index_oop_from_field_offset_long(oopDesc::bs()->write_barrier(JNIHandles::resolve(_obj)), _offset);
156 }
157
158 template <typename T>
159 T normalize_for_write(T x) {
160 return x;
161 }
162
163 jboolean normalize_for_write(jboolean x) {
164 return x & 1;
165 }
166
167 template <typename T>
168 T normalize_for_read(T x) {
169 return x;
170 }
171
172 jboolean normalize_for_read(jboolean x) {
173 return x != 0;
174 }
175
176 /**
177 * Helper class to wrap memory accesses in JavaThread::doing_unsafe_access()
178 */
179 class GuardUnsafeAccess {
180 JavaThread* _thread;
181 bool _active;
182
183 public:
184 GuardUnsafeAccess(JavaThread* thread, jobject _obj) : _thread(thread) {
185 if (JNIHandles::resolve(_obj) == NULL) {
186 // native/off-heap access which may raise SIGBUS if accessing
187 // memory mapped file data in a region of the file which has
188 // been truncated and is now invalid
189 _thread->set_doing_unsafe_access(true);
190 _active = true;
191 } else {
192 _active = false;
193 }
194 }
195
196 ~GuardUnsafeAccess() {
197 if (_active) {
198 _thread->set_doing_unsafe_access(false);
199 }
200 }
201 };
202
203 public:
204 MemoryAccess(JavaThread* thread, jobject obj, jlong offset)
205 : _thread(thread), _obj(obj), _offset(offset) {
206 }
207
208 template <typename T>
209 T get() {
210 GuardUnsafeAccess guard(_thread, _obj);
211
212 T* p = (T*)get_addr();
213
214 T x = normalize_for_read(*p);
215
216 return x;
217 }
218
219 template <typename T>
220 void put(T x) {
221 GuardUnsafeAccess guard(_thread, _obj);
222
223 T* p = (T*)put_addr();
224
225 *p = normalize_for_write(x);
226 }
227
228
229 template <typename T>
230 T get_volatile() {
231 GuardUnsafeAccess guard(_thread, _obj);
232
233 T* p = (T*)get_addr();
234
235 if (support_IRIW_for_not_multiple_copy_atomic_cpu) {
236 OrderAccess::fence();
237 }
238
239 T x = OrderAccess::load_acquire((volatile T*)p);
240
241 return normalize_for_read(x);
242 }
243
244 template <typename T>
245 void put_volatile(T x) {
246 GuardUnsafeAccess guard(_thread, _obj);
247
248 T* p = (T*)put_addr();
249
250 OrderAccess::release_store_fence((volatile T*)p, normalize_for_write(x));
251 }
252
253
254 #ifndef SUPPORTS_NATIVE_CX8
255 jlong get_jlong_locked() {
256 GuardUnsafeAccess guard(_thread, _obj);
257
258 MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
259
260 jlong* p = (jlong*)get_addr();
261
262 jlong x = Atomic::load(p);
263
264 return x;
265 }
266
267 void put_jlong_locked(jlong x) {
268 GuardUnsafeAccess guard(_thread, _obj);
269
270 MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
271
272 jlong* p = (jlong*)put_addr();
273
274 Atomic::store(normalize_for_write(x), p);
275 }
276 #endif
277 };
278
279 // Get/PutObject must be special-cased, since it works with handles.
280
281 // We could be accessing the referent field in a reference
282 // object. If G1 is enabled then we need to register non-null
283 // referent with the SATB barrier.
284
285 #if INCLUDE_ALL_GCS
286 static bool is_java_lang_ref_Reference_access(oop o, jlong offset) {
287 if (offset == java_lang_ref_Reference::referent_offset && o != NULL) {
288 Klass* k = o->klass();
289 if (InstanceKlass::cast(k)->reference_type() != REF_NONE) {
290 assert(InstanceKlass::cast(k)->is_subclass_of(SystemDictionary::Reference_klass()), "sanity");
291 return true;
292 }
293 }
294 return false;
295 }
296 #endif
297
298 static void ensure_satb_referent_alive(oop o, jlong offset, oop v) {
299 #if INCLUDE_ALL_GCS
300 if ((UseG1GC || (UseShenandoahGC && ShenandoahSATBBarrier)) && v != NULL && is_java_lang_ref_Reference_access(o, offset)) {
301 G1SATBCardTableModRefBS::enqueue(v);
302 }
303 #endif
304 }
305
306 // These functions allow a null base pointer with an arbitrary address.
307 // But if the base pointer is non-null, the offset should make some sense.
308 // That is, it should be in the range [0, MAX_OBJECT_SIZE].
309 UNSAFE_ENTRY(jobject, Unsafe_GetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
310 oop p = JNIHandles::resolve(obj);
311 p = oopDesc::bs()->read_barrier(p);
312 oop v;
313
314 if (UseCompressedOops) {
315 narrowOop n = *(narrowOop*)index_oop_from_field_offset_long(p, offset);
316 v = oopDesc::decode_heap_oop(n);
317 } else {
318 v = *(oop*)index_oop_from_field_offset_long(p, offset);
319 }
320
321 ensure_satb_referent_alive(p, offset, v);
322
323 return JNIHandles::make_local(env, v);
324 } UNSAFE_END
325
326 UNSAFE_ENTRY(void, Unsafe_PutObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
327 oop x = JNIHandles::resolve(x_h);
328 oop p = JNIHandles::resolve(obj);
329
330 x = oopDesc::bs()->storeval_barrier(x);
331 p = oopDesc::bs()->write_barrier(p);
332
333 if (UseCompressedOops) {
334 oop_store((narrowOop*)index_oop_from_field_offset_long(p, offset), x);
335 } else {
336 oop_store((oop*)index_oop_from_field_offset_long(p, offset), x);
337 }
338 } UNSAFE_END
339
340 UNSAFE_ENTRY(jobject, Unsafe_GetObjectVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
341 oop p = JNIHandles::resolve(obj);
342 p = oopDesc::bs()->read_barrier(p);
343 void* addr = index_oop_from_field_offset_long(p, offset);
344
345 volatile oop v;
346
347 if (support_IRIW_for_not_multiple_copy_atomic_cpu) {
348 OrderAccess::fence();
349 }
350
351 if (UseCompressedOops) {
352 volatile narrowOop n = *(volatile narrowOop*) addr;
353 (void)const_cast<oop&>(v = oopDesc::decode_heap_oop(n));
354 } else {
355 (void)const_cast<oop&>(v = *(volatile oop*) addr);
356 }
357
358 ensure_satb_referent_alive(p, offset, v);
359
360 OrderAccess::acquire();
361 return JNIHandles::make_local(env, v);
362 } UNSAFE_END
363
364 UNSAFE_ENTRY(void, Unsafe_PutObjectVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject x_h)) {
365 oop x = JNIHandles::resolve(x_h);
366 oop p = JNIHandles::resolve(obj);
367 x = oopDesc::bs()->storeval_barrier(x);
368 p = oopDesc::bs()->write_barrier(p);
369 void* addr = index_oop_from_field_offset_long(p, offset);
370 OrderAccess::release();
371
372 if (UseCompressedOops) {
373 oop_store((narrowOop*)addr, x);
374 } else {
375 oop_store((oop*)addr, x);
376 }
377
378 OrderAccess::fence();
379 } UNSAFE_END
380
381 UNSAFE_ENTRY(jobject, Unsafe_GetUncompressedObject(JNIEnv *env, jobject unsafe, jlong addr)) {
382 oop v = *(oop*) (address) addr;
383
384 return JNIHandles::make_local(env, v);
385 } UNSAFE_END
386
387 #ifndef SUPPORTS_NATIVE_CX8
388
389 // VM_Version::supports_cx8() is a surrogate for 'supports atomic long memory ops'.
390 //
391 // On platforms which do not support atomic compare-and-swap of jlong (8 byte)
392 // values we have to use a lock-based scheme to enforce atomicity. This has to be
393 // applied to all Unsafe operations that set the value of a jlong field. Even so
394 // the compareAndSetLong operation will not be atomic with respect to direct stores
395 // to the field from Java code. It is important therefore that any Java code that
396 // utilizes these Unsafe jlong operations does not perform direct stores. To permit
397 // direct loads of the field from Java code we must also use Atomic::store within the
398 // locked regions. And for good measure, in case there are direct stores, we also
399 // employ Atomic::load within those regions. Note that the field in question must be
400 // volatile and so must have atomic load/store accesses applied at the Java level.
401 //
402 // The locking scheme could utilize a range of strategies for controlling the locking
403 // granularity: from a lock per-field through to a single global lock. The latter is
404 // the simplest and is used for the current implementation. Note that the Java object
405 // that contains the field, can not, in general, be used for locking. To do so can lead
406 // to deadlocks as we may introduce locking into what appears to the Java code to be a
407 // lock-free path.
408 //
409 // As all the locked-regions are very short and themselves non-blocking we can treat
410 // them as leaf routines and elide safepoint checks (ie we don't perform any thread
411 // state transitions even when blocking for the lock). Note that if we do choose to
412 // add safepoint checks and thread state transitions, we must ensure that we calculate
413 // the address of the field _after_ we have acquired the lock, else the object may have
414 // been moved by the GC
415
416 UNSAFE_ENTRY(jlong, Unsafe_GetLongVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) {
417 if (VM_Version::supports_cx8()) {
418 return MemoryAccess(thread, obj, offset).get_volatile<jlong>();
419 } else {
420 return MemoryAccess(thread, obj, offset).get_jlong_locked();
421 }
422 } UNSAFE_END
423
424 UNSAFE_ENTRY(void, Unsafe_PutLongVolatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong x)) {
425 if (VM_Version::supports_cx8()) {
426 MemoryAccess(thread, obj, offset).put_volatile<jlong>(x);
427 } else {
428 MemoryAccess(thread, obj, offset).put_jlong_locked(x);
429 }
430 } UNSAFE_END
431
432 #endif // not SUPPORTS_NATIVE_CX8
433
434 UNSAFE_LEAF(jboolean, Unsafe_isBigEndian0(JNIEnv *env, jobject unsafe)) {
435 #ifdef VM_LITTLE_ENDIAN
436 return false;
437 #else
438 return true;
439 #endif
440 } UNSAFE_END
441
442 UNSAFE_LEAF(jint, Unsafe_unalignedAccess0(JNIEnv *env, jobject unsafe)) {
443 return UseUnalignedAccesses;
444 } UNSAFE_END
445
446 #define DEFINE_GETSETOOP(java_type, Type) \
447 \
448 UNSAFE_ENTRY(java_type, Unsafe_Get##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
449 return MemoryAccess(thread, obj, offset).get<java_type>(); \
450 } UNSAFE_END \
451 \
452 UNSAFE_ENTRY(void, Unsafe_Put##Type(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
453 MemoryAccess(thread, obj, offset).put<java_type>(x); \
454 } UNSAFE_END \
455 \
456 // END DEFINE_GETSETOOP.
457
458 DEFINE_GETSETOOP(jboolean, Boolean)
459 DEFINE_GETSETOOP(jbyte, Byte)
460 DEFINE_GETSETOOP(jshort, Short);
461 DEFINE_GETSETOOP(jchar, Char);
462 DEFINE_GETSETOOP(jint, Int);
463 DEFINE_GETSETOOP(jlong, Long);
464 DEFINE_GETSETOOP(jfloat, Float);
465 DEFINE_GETSETOOP(jdouble, Double);
466
467 #undef DEFINE_GETSETOOP
468
469 #define DEFINE_GETSETOOP_VOLATILE(java_type, Type) \
470 \
471 UNSAFE_ENTRY(java_type, Unsafe_Get##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset)) { \
472 return MemoryAccess(thread, obj, offset).get_volatile<java_type>(); \
473 } UNSAFE_END \
474 \
475 UNSAFE_ENTRY(void, Unsafe_Put##Type##Volatile(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, java_type x)) { \
476 MemoryAccess(thread, obj, offset).put_volatile<java_type>(x); \
477 } UNSAFE_END \
478 \
479 // END DEFINE_GETSETOOP_VOLATILE.
480
481 DEFINE_GETSETOOP_VOLATILE(jboolean, Boolean)
482 DEFINE_GETSETOOP_VOLATILE(jbyte, Byte)
483 DEFINE_GETSETOOP_VOLATILE(jshort, Short);
484 DEFINE_GETSETOOP_VOLATILE(jchar, Char);
485 DEFINE_GETSETOOP_VOLATILE(jint, Int);
486 DEFINE_GETSETOOP_VOLATILE(jfloat, Float);
487 DEFINE_GETSETOOP_VOLATILE(jdouble, Double);
488
489 #ifdef SUPPORTS_NATIVE_CX8
490 DEFINE_GETSETOOP_VOLATILE(jlong, Long);
491 #endif
492
493 #undef DEFINE_GETSETOOP_VOLATILE
494
495 UNSAFE_LEAF(void, Unsafe_LoadFence(JNIEnv *env, jobject unsafe)) {
496 OrderAccess::acquire();
497 } UNSAFE_END
498
499 UNSAFE_LEAF(void, Unsafe_StoreFence(JNIEnv *env, jobject unsafe)) {
500 OrderAccess::release();
501 } UNSAFE_END
502
503 UNSAFE_LEAF(void, Unsafe_FullFence(JNIEnv *env, jobject unsafe)) {
504 OrderAccess::fence();
505 } UNSAFE_END
506
507 ////// Allocation requests
508
509 UNSAFE_ENTRY(jobject, Unsafe_AllocateInstance(JNIEnv *env, jobject unsafe, jclass cls)) {
510 ThreadToNativeFromVM ttnfv(thread);
511 return env->AllocObject(cls);
512 } UNSAFE_END
513
514 UNSAFE_ENTRY(jlong, Unsafe_AllocateMemory0(JNIEnv *env, jobject unsafe, jlong size)) {
515 size_t sz = (size_t)size;
516
517 sz = align_up(sz, HeapWordSize);
518 void* x = os::malloc(sz, mtInternal);
519
520 return addr_to_java(x);
521 } UNSAFE_END
522
523 UNSAFE_ENTRY(jlong, Unsafe_ReallocateMemory0(JNIEnv *env, jobject unsafe, jlong addr, jlong size)) {
524 void* p = addr_from_java(addr);
525 size_t sz = (size_t)size;
526 sz = align_up(sz, HeapWordSize);
527
528 void* x = os::realloc(p, sz, mtInternal);
529
530 return addr_to_java(x);
531 } UNSAFE_END
532
533 UNSAFE_ENTRY(void, Unsafe_FreeMemory0(JNIEnv *env, jobject unsafe, jlong addr)) {
534 void* p = addr_from_java(addr);
535
536 os::free(p);
537 } UNSAFE_END
538
539 UNSAFE_ENTRY(void, Unsafe_SetMemory0(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong size, jbyte value)) {
540 size_t sz = (size_t)size;
541
542 oop base = JNIHandles::resolve(obj);
543 base = oopDesc::bs()->write_barrier(base);
544 void* p = index_oop_from_field_offset_long(base, offset);
545
546 Copy::fill_to_memory_atomic(p, sz, value);
547 } UNSAFE_END
548
549 UNSAFE_ENTRY(void, Unsafe_CopyMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size)) {
550 size_t sz = (size_t)size;
551
552 oop srcp = JNIHandles::resolve(srcObj);
553 oop dstp = JNIHandles::resolve(dstObj);
554
555 srcp = oopDesc::bs()->read_barrier(srcp);
556 dstp = oopDesc::bs()->write_barrier(dstp);
557
558 void* src = index_oop_from_field_offset_long(srcp, srcOffset);
559 void* dst = index_oop_from_field_offset_long(dstp, dstOffset);
560
561 Copy::conjoint_memory_atomic(src, dst, sz);
562 } UNSAFE_END
563
564 // This function is a leaf since if the source and destination are both in native memory
565 // the copy may potentially be very large, and we don't want to disable GC if we can avoid it.
566 // If either source or destination (or both) are on the heap, the function will enter VM using
567 // JVM_ENTRY_FROM_LEAF
568 UNSAFE_LEAF(void, Unsafe_CopySwapMemory0(JNIEnv *env, jobject unsafe, jobject srcObj, jlong srcOffset, jobject dstObj, jlong dstOffset, jlong size, jlong elemSize)) {
569 size_t sz = (size_t)size;
570 size_t esz = (size_t)elemSize;
571
572 if (srcObj == NULL && dstObj == NULL) {
573 // Both src & dst are in native memory
574 address src = (address)srcOffset;
575 address dst = (address)dstOffset;
576
577 Copy::conjoint_swap(src, dst, sz, esz);
578 } else {
579 // At least one of src/dst are on heap, transition to VM to access raw pointers
580
581 JVM_ENTRY_FROM_LEAF(env, void, Unsafe_CopySwapMemory0) {
582 oop srcp = JNIHandles::resolve(srcObj);
583 oop dstp = JNIHandles::resolve(dstObj);
584
585 address src = (address)index_oop_from_field_offset_long(srcp, srcOffset);
586 address dst = (address)index_oop_from_field_offset_long(dstp, dstOffset);
587
588 Copy::conjoint_swap(src, dst, sz, esz);
589 } JVM_END
590 }
591 } UNSAFE_END
592
593 ////// Random queries
594
595 UNSAFE_LEAF(jint, Unsafe_AddressSize0(JNIEnv *env, jobject unsafe)) {
596 return sizeof(void*);
597 } UNSAFE_END
598
599 UNSAFE_LEAF(jint, Unsafe_PageSize()) {
600 return os::vm_page_size();
601 } UNSAFE_END
602
603 static jlong find_field_offset(jclass clazz, jstring name, TRAPS) {
604 assert(clazz != NULL, "clazz must not be NULL");
605 assert(name != NULL, "name must not be NULL");
606
607 ResourceMark rm(THREAD);
608 char *utf_name = java_lang_String::as_utf8_string(JNIHandles::resolve_non_null(name));
609
610 InstanceKlass* k = InstanceKlass::cast(java_lang_Class::as_Klass(JNIHandles::resolve_non_null(clazz)));
611
612 jint offset = -1;
613 for (JavaFieldStream fs(k); !fs.done(); fs.next()) {
614 Symbol *name = fs.name();
615 if (name->equals(utf_name)) {
616 offset = fs.offset();
617 break;
618 }
619 }
620 if (offset < 0) {
621 THROW_0(vmSymbols::java_lang_InternalError());
622 }
623 return field_offset_from_byte_offset(offset);
624 }
625
626 static jlong find_field_offset(jobject field, int must_be_static, TRAPS) {
627 assert(field != NULL, "field must not be NULL");
628
629 oop reflected = JNIHandles::resolve_non_null(field);
630 oop mirror = java_lang_reflect_Field::clazz(reflected);
631 Klass* k = java_lang_Class::as_Klass(mirror);
632 int slot = java_lang_reflect_Field::slot(reflected);
633 int modifiers = java_lang_reflect_Field::modifiers(reflected);
634
635 if (must_be_static >= 0) {
636 int really_is_static = ((modifiers & JVM_ACC_STATIC) != 0);
637 if (must_be_static != really_is_static) {
638 THROW_0(vmSymbols::java_lang_IllegalArgumentException());
639 }
640 }
641
642 int offset = InstanceKlass::cast(k)->field_offset(slot);
643 return field_offset_from_byte_offset(offset);
644 }
645
646 UNSAFE_ENTRY(jlong, Unsafe_ObjectFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
647 return find_field_offset(field, 0, THREAD);
648 } UNSAFE_END
649
650 UNSAFE_ENTRY(jlong, Unsafe_ObjectFieldOffset1(JNIEnv *env, jobject unsafe, jclass c, jstring name)) {
651 return find_field_offset(c, name, THREAD);
652 } UNSAFE_END
653
654 UNSAFE_ENTRY(jlong, Unsafe_StaticFieldOffset0(JNIEnv *env, jobject unsafe, jobject field)) {
655 return find_field_offset(field, 1, THREAD);
656 } UNSAFE_END
657
658 UNSAFE_ENTRY(jobject, Unsafe_StaticFieldBase0(JNIEnv *env, jobject unsafe, jobject field)) {
659 assert(field != NULL, "field must not be NULL");
660
661 // Note: In this VM implementation, a field address is always a short
662 // offset from the base of a a klass metaobject. Thus, the full dynamic
663 // range of the return type is never used. However, some implementations
664 // might put the static field inside an array shared by many classes,
665 // or even at a fixed address, in which case the address could be quite
666 // large. In that last case, this function would return NULL, since
667 // the address would operate alone, without any base pointer.
668
669 oop reflected = JNIHandles::resolve_non_null(field);
670 oop mirror = java_lang_reflect_Field::clazz(reflected);
671 int modifiers = java_lang_reflect_Field::modifiers(reflected);
672
673 if ((modifiers & JVM_ACC_STATIC) == 0) {
674 THROW_0(vmSymbols::java_lang_IllegalArgumentException());
675 }
676
677 return JNIHandles::make_local(env, mirror);
678 } UNSAFE_END
679
680 UNSAFE_ENTRY(void, Unsafe_EnsureClassInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
681 assert(clazz != NULL, "clazz must not be NULL");
682
683 oop mirror = JNIHandles::resolve_non_null(clazz);
684
685 Klass* klass = java_lang_Class::as_Klass(mirror);
686 if (klass != NULL && klass->should_be_initialized()) {
687 InstanceKlass* k = InstanceKlass::cast(klass);
688 k->initialize(CHECK);
689 }
690 }
691 UNSAFE_END
692
693 UNSAFE_ENTRY(jboolean, Unsafe_ShouldBeInitialized0(JNIEnv *env, jobject unsafe, jobject clazz)) {
694 assert(clazz != NULL, "clazz must not be NULL");
695
696 oop mirror = JNIHandles::resolve_non_null(clazz);
697 Klass* klass = java_lang_Class::as_Klass(mirror);
698
699 if (klass != NULL && klass->should_be_initialized()) {
700 return true;
701 }
702
703 return false;
704 }
705 UNSAFE_END
706
707 static void getBaseAndScale(int& base, int& scale, jclass clazz, TRAPS) {
708 assert(clazz != NULL, "clazz must not be NULL");
709
710 oop mirror = JNIHandles::resolve_non_null(clazz);
711 Klass* k = java_lang_Class::as_Klass(mirror);
712
713 if (k == NULL || !k->is_array_klass()) {
714 THROW(vmSymbols::java_lang_InvalidClassException());
715 } else if (k->is_objArray_klass()) {
716 base = arrayOopDesc::base_offset_in_bytes(T_OBJECT);
717 scale = heapOopSize;
718 } else if (k->is_typeArray_klass()) {
719 TypeArrayKlass* tak = TypeArrayKlass::cast(k);
720 base = tak->array_header_in_bytes();
721 assert(base == arrayOopDesc::base_offset_in_bytes(tak->element_type()), "array_header_size semantics ok");
722 scale = (1 << tak->log2_element_size());
723 } else {
724 ShouldNotReachHere();
725 }
726 }
727
728 UNSAFE_ENTRY(jint, Unsafe_ArrayBaseOffset0(JNIEnv *env, jobject unsafe, jclass clazz)) {
729 int base = 0, scale = 0;
730 getBaseAndScale(base, scale, clazz, CHECK_0);
731
732 return field_offset_from_byte_offset(base);
733 } UNSAFE_END
734
735
736 UNSAFE_ENTRY(jint, Unsafe_ArrayIndexScale0(JNIEnv *env, jobject unsafe, jclass clazz)) {
737 int base = 0, scale = 0;
738 getBaseAndScale(base, scale, clazz, CHECK_0);
739
740 // This VM packs both fields and array elements down to the byte.
741 // But watch out: If this changes, so that array references for
742 // a given primitive type (say, T_BOOLEAN) use different memory units
743 // than fields, this method MUST return zero for such arrays.
744 // For example, the VM used to store sub-word sized fields in full
745 // words in the object layout, so that accessors like getByte(Object,int)
746 // did not really do what one might expect for arrays. Therefore,
747 // this function used to report a zero scale factor, so that the user
748 // would know not to attempt to access sub-word array elements.
749 // // Code for unpacked fields:
750 // if (scale < wordSize) return 0;
751
752 // The following allows for a pretty general fieldOffset cookie scheme,
753 // but requires it to be linear in byte offset.
754 return field_offset_from_byte_offset(scale) - field_offset_from_byte_offset(0);
755 } UNSAFE_END
756
757
758 static inline void throw_new(JNIEnv *env, const char *ename) {
759 jclass cls = env->FindClass(ename);
760 if (env->ExceptionCheck()) {
761 env->ExceptionClear();
762 tty->print_cr("Unsafe: cannot throw %s because FindClass has failed", ename);
763 return;
764 }
765
766 env->ThrowNew(cls, NULL);
767 }
768
769 static jclass Unsafe_DefineClass_impl(JNIEnv *env, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd) {
770 // Code lifted from JDK 1.3 ClassLoader.c
771
772 jbyte *body;
773 char *utfName = NULL;
774 jclass result = 0;
775 char buf[128];
776
777 assert(data != NULL, "Class bytes must not be NULL");
778 assert(length >= 0, "length must not be negative: %d", length);
779
780 if (UsePerfData) {
781 ClassLoader::unsafe_defineClassCallCounter()->inc();
782 }
783
784 body = NEW_C_HEAP_ARRAY(jbyte, length, mtInternal);
785 if (body == NULL) {
786 throw_new(env, "java/lang/OutOfMemoryError");
787 return 0;
788 }
789
790 env->GetByteArrayRegion(data, offset, length, body);
791 if (env->ExceptionOccurred()) {
792 goto free_body;
793 }
794
795 if (name != NULL) {
796 uint len = env->GetStringUTFLength(name);
797 int unicode_len = env->GetStringLength(name);
798
799 if (len >= sizeof(buf)) {
800 utfName = NEW_C_HEAP_ARRAY(char, len + 1, mtInternal);
801 if (utfName == NULL) {
802 throw_new(env, "java/lang/OutOfMemoryError");
803 goto free_body;
804 }
805 } else {
806 utfName = buf;
807 }
808
809 env->GetStringUTFRegion(name, 0, unicode_len, utfName);
810
811 for (uint i = 0; i < len; i++) {
812 if (utfName[i] == '.') utfName[i] = '/';
813 }
814 }
815
816 result = JVM_DefineClass(env, utfName, loader, body, length, pd);
817
818 if (utfName && utfName != buf) {
819 FREE_C_HEAP_ARRAY(char, utfName);
820 }
821
822 free_body:
823 FREE_C_HEAP_ARRAY(jbyte, body);
824 return result;
825 }
826
827
828 UNSAFE_ENTRY(jclass, Unsafe_DefineClass0(JNIEnv *env, jobject unsafe, jstring name, jbyteArray data, int offset, int length, jobject loader, jobject pd)) {
829 ThreadToNativeFromVM ttnfv(thread);
830
831 return Unsafe_DefineClass_impl(env, name, data, offset, length, loader, pd);
832 } UNSAFE_END
833
834
835 // define a class but do not make it known to the class loader or system dictionary
836 // - host_class: supplies context for linkage, access control, protection domain, and class loader
837 // if host_class is itself anonymous then it is replaced with its host class.
838 // - data: bytes of a class file, a raw memory address (length gives the number of bytes)
839 // - cp_patches: where non-null entries exist, they replace corresponding CP entries in data
840
841 // When you load an anonymous class U, it works as if you changed its name just before loading,
842 // to a name that you will never use again. Since the name is lost, no other class can directly
843 // link to any member of U. Just after U is loaded, the only way to use it is reflectively,
844 // through java.lang.Class methods like Class.newInstance.
845
846 // The package of an anonymous class must either match its host's class's package or be in the
847 // unnamed package. If it is in the unnamed package then it will be put in its host class's
848 // package.
849 //
850
851 // Access checks for linkage sites within U continue to follow the same rules as for named classes.
852 // An anonymous class also has special privileges to access any member of its host class.
853 // This is the main reason why this loading operation is unsafe. The purpose of this is to
854 // allow language implementations to simulate "open classes"; a host class in effect gets
855 // new code when an anonymous class is loaded alongside it. A less convenient but more
856 // standard way to do this is with reflection, which can also be set to ignore access
857 // restrictions.
858
859 // Access into an anonymous class is possible only through reflection. Therefore, there
860 // are no special access rules for calling into an anonymous class. The relaxed access
861 // rule for the host class is applied in the opposite direction: A host class reflectively
862 // access one of its anonymous classes.
863
864 // If you load the same bytecodes twice, you get two different classes. You can reload
865 // the same bytecodes with or without varying CP patches.
866
867 // By using the CP patching array, you can have a new anonymous class U2 refer to an older one U1.
868 // The bytecodes for U2 should refer to U1 by a symbolic name (doesn't matter what the name is).
869 // The CONSTANT_Class entry for that name can be patched to refer directly to U1.
870
871 // This allows, for example, U2 to use U1 as a superclass or super-interface, or as
872 // an outer class (so that U2 is an anonymous inner class of anonymous U1).
873 // It is not possible for a named class, or an older anonymous class, to refer by
874 // name (via its CP) to a newer anonymous class.
875
876 // CP patching may also be used to modify (i.e., hack) the names of methods, classes,
877 // or type descriptors used in the loaded anonymous class.
878
879 // Finally, CP patching may be used to introduce "live" objects into the constant pool,
880 // instead of "dead" strings. A compiled statement like println((Object)"hello") can
881 // be changed to println(greeting), where greeting is an arbitrary object created before
882 // the anonymous class is loaded. This is useful in dynamic languages, in which
883 // various kinds of metaobjects must be introduced as constants into bytecode.
884 // Note the cast (Object), which tells the verifier to expect an arbitrary object,
885 // not just a literal string. For such ldc instructions, the verifier uses the
886 // type Object instead of String, if the loaded constant is not in fact a String.
887
888 static InstanceKlass*
889 Unsafe_DefineAnonymousClass_impl(JNIEnv *env,
890 jclass host_class, jbyteArray data, jobjectArray cp_patches_jh,
891 u1** temp_alloc,
892 TRAPS) {
893 assert(host_class != NULL, "host_class must not be NULL");
894 assert(data != NULL, "data must not be NULL");
895
896 if (UsePerfData) {
897 ClassLoader::unsafe_defineClassCallCounter()->inc();
898 }
899
900 jint length = typeArrayOop(JNIHandles::resolve_non_null(data))->length();
901 assert(length >= 0, "class_bytes_length must not be negative: %d", length);
902
903 int class_bytes_length = (int) length;
904
905 u1* class_bytes = NEW_C_HEAP_ARRAY(u1, length, mtInternal);
906 if (class_bytes == NULL) {
907 THROW_0(vmSymbols::java_lang_OutOfMemoryError());
908 }
909
910 // caller responsible to free it:
911 *temp_alloc = class_bytes;
912
913 jbyte* array_base = typeArrayOop(oopDesc::bs()->read_barrier(JNIHandles::resolve_non_null(data)))->byte_at_addr(0);
914 Copy::conjoint_jbytes(array_base, class_bytes, length);
915
916 objArrayHandle cp_patches_h;
917 if (cp_patches_jh != NULL) {
918 oop p = JNIHandles::resolve_non_null(cp_patches_jh);
919 assert(p->is_objArray(), "cp_patches must be an object[]");
920 cp_patches_h = objArrayHandle(THREAD, (objArrayOop)p);
921 }
922
923 const Klass* host_klass = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(host_class));
924
925 // Make sure it's the real host class, not another anonymous class.
926 while (host_klass != NULL && host_klass->is_instance_klass() &&
927 InstanceKlass::cast(host_klass)->is_anonymous()) {
928 host_klass = InstanceKlass::cast(host_klass)->host_klass();
929 }
930
931 // Primitive types have NULL Klass* fields in their java.lang.Class instances.
932 if (host_klass == NULL) {
933 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), "Host class is null");
934 }
935
936 assert(host_klass->is_instance_klass(), "Host class must be an instance class");
937
938 const char* host_source = host_klass->external_name();
939 Handle host_loader(THREAD, host_klass->class_loader());
940 Handle host_domain(THREAD, host_klass->protection_domain());
941
942 GrowableArray<Handle>* cp_patches = NULL;
943
944 if (cp_patches_h.not_null()) {
945 int alen = cp_patches_h->length();
946
947 for (int i = alen-1; i >= 0; i--) {
948 oop p = cp_patches_h->obj_at(i);
949 if (p != NULL) {
950 Handle patch(THREAD, p);
951
952 if (cp_patches == NULL) {
953 cp_patches = new GrowableArray<Handle>(i+1, i+1, Handle());
954 }
955
956 cp_patches->at_put(i, patch);
957 }
958 }
959 }
960
961 ClassFileStream st(class_bytes, class_bytes_length, host_source, ClassFileStream::verify);
962
963 Symbol* no_class_name = NULL;
964 Klass* anonk = SystemDictionary::parse_stream(no_class_name,
965 host_loader,
966 host_domain,
967 &st,
968 InstanceKlass::cast(host_klass),
969 cp_patches,
970 CHECK_NULL);
971 if (anonk == NULL) {
972 return NULL;
973 }
974
975 return InstanceKlass::cast(anonk);
976 }
977
978 UNSAFE_ENTRY(jclass, Unsafe_DefineAnonymousClass0(JNIEnv *env, jobject unsafe, jclass host_class, jbyteArray data, jobjectArray cp_patches_jh)) {
979 ResourceMark rm(THREAD);
980
981 jobject res_jh = NULL;
982 u1* temp_alloc = NULL;
983
984 InstanceKlass* anon_klass = Unsafe_DefineAnonymousClass_impl(env, host_class, data, cp_patches_jh, &temp_alloc, THREAD);
985 if (anon_klass != NULL) {
986 res_jh = JNIHandles::make_local(env, anon_klass->java_mirror());
987 }
988
989 // try/finally clause:
990 if (temp_alloc != NULL) {
991 FREE_C_HEAP_ARRAY(u1, temp_alloc);
992 }
993
994 // The anonymous class loader data has been artificially been kept alive to
995 // this point. The mirror and any instances of this class have to keep
996 // it alive afterwards.
997 if (anon_klass != NULL) {
998 anon_klass->class_loader_data()->dec_keep_alive();
999 }
1000
1001 // let caller initialize it as needed...
1002
1003 return (jclass) res_jh;
1004 } UNSAFE_END
1005
1006
1007
1008 UNSAFE_ENTRY(void, Unsafe_ThrowException(JNIEnv *env, jobject unsafe, jthrowable thr)) {
1009 ThreadToNativeFromVM ttnfv(thread);
1010 env->Throw(thr);
1011 } UNSAFE_END
1012
1013 // JSR166 ------------------------------------------------------------------
1014
1015 UNSAFE_ENTRY(jobject, Unsafe_CompareAndExchangeObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
1016 oop x = JNIHandles::resolve(x_h);
1017 oop e = JNIHandles::resolve(e_h);
1018 oop p = JNIHandles::resolve(obj);
1019
1020 p = oopDesc::bs()->write_barrier(p);
1021 x = oopDesc::bs()->storeval_barrier(x);
1022
1023 HeapWord* addr = (HeapWord *)index_oop_from_field_offset_long(p, offset);
1024
1025 oop res;
1026 if (UseShenandoahGC && ShenandoahCASBarrier) {
1027 oop expected = e;
1028 do {
1029 e = expected;
1030 res = oopDesc::atomic_compare_exchange_oop(x, addr, e, true);
1031 expected = res;
1032 } while ((! oopDesc::unsafe_equals(e, expected)) && oopDesc::unsafe_equals(oopDesc::bs()->read_barrier(e), oopDesc::bs()->read_barrier(expected)));
1033 } else {
1034 res = oopDesc::atomic_compare_exchange_oop(x, addr, e, true);
1035 }
1036 if (oopDesc::unsafe_equals(res, e)) {
1037 update_barrier_set((void*)addr, x);
1038 }
1039 return JNIHandles::make_local(env, res);
1040 } UNSAFE_END
1041
1042 UNSAFE_ENTRY(jint, Unsafe_CompareAndExchangeInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
1043 oop p = JNIHandles::resolve(obj);
1044 p = oopDesc::bs()->write_barrier(p);
1045 jint* addr = (jint *) index_oop_from_field_offset_long(p, offset);
1046
1047 return (jint)(Atomic::cmpxchg(x, addr, e));
1048 } UNSAFE_END
1049
1050 UNSAFE_ENTRY(jlong, Unsafe_CompareAndExchangeLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
1051 Handle p (THREAD, oopDesc::bs()->write_barrier(JNIHandles::resolve(obj)));
1052 jlong* addr = (jlong*)index_oop_from_field_offset_long(p(), offset);
1053
1054 #ifdef SUPPORTS_NATIVE_CX8
1055 return (jlong)(Atomic::cmpxchg(x, addr, e));
1056 #else
1057 if (VM_Version::supports_cx8()) {
1058 return (jlong)(Atomic::cmpxchg(x, addr, e));
1059 } else {
1060 MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
1061
1062 jlong val = Atomic::load(addr);
1063 if (val == e) {
1064 Atomic::store(x, addr);
1065 }
1066 return val;
1067 }
1068 #endif
1069 } UNSAFE_END
1070
1071 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetObject(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jobject e_h, jobject x_h)) {
1072 oop x = JNIHandles::resolve(x_h);
1073 oop e = JNIHandles::resolve(e_h);
1074 oop p = JNIHandles::resolve(obj);
1075
1076 p = oopDesc::bs()->write_barrier(p);
1077 x = oopDesc::bs()->storeval_barrier(x);
1078
1079 HeapWord* addr = (HeapWord *)index_oop_from_field_offset_long(p, offset);
1080 jboolean success;
1081 if (UseShenandoahGC && ShenandoahCASBarrier) {
1082 oop expected;
1083 do {
1084 expected = e;
1085 e = oopDesc::atomic_compare_exchange_oop(x, addr, expected, true);
1086 success = oopDesc::unsafe_equals(e, expected);
1087 } while ((! success) && oopDesc::unsafe_equals(oopDesc::bs()->read_barrier(e), oopDesc::bs()->read_barrier(expected)));
1088 } else {
1089 success = oopDesc::unsafe_equals(e, oopDesc::atomic_compare_exchange_oop(x, addr, e, true));
1090 }
1091 if (! success) {
1092 return false;
1093 }
1094
1095 update_barrier_set((void*)addr, x);
1096
1097 return true;
1098 } UNSAFE_END
1099
1100 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetInt(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jint e, jint x)) {
1101 oop p = JNIHandles::resolve(obj);
1102 p = oopDesc::bs()->write_barrier(p);
1103 jint* addr = (jint *)index_oop_from_field_offset_long(p, offset);
1104
1105 return (jint)(Atomic::cmpxchg(x, addr, e)) == e;
1106 } UNSAFE_END
1107
1108 UNSAFE_ENTRY(jboolean, Unsafe_CompareAndSetLong(JNIEnv *env, jobject unsafe, jobject obj, jlong offset, jlong e, jlong x)) {
1109 Handle p (THREAD, oopDesc::bs()->write_barrier(JNIHandles::resolve(obj)));
1110 jlong* addr = (jlong*)index_oop_from_field_offset_long(p(), offset);
1111
1112 #ifdef SUPPORTS_NATIVE_CX8
1113 return (jlong)(Atomic::cmpxchg(x, addr, e)) == e;
1114 #else
1115 if (VM_Version::supports_cx8()) {
1116 return (jlong)(Atomic::cmpxchg(x, addr, e)) == e;
1117 } else {
1118 MutexLockerEx mu(UnsafeJlong_lock, Mutex::_no_safepoint_check_flag);
1119
1120 jlong val = Atomic::load(addr);
1121 if (val != e) {
1122 return false;
1123 }
1124
1125 Atomic::store(x, addr);
1126 return true;
1127 }
1128 #endif
1129 } UNSAFE_END
1130
1131 UNSAFE_ENTRY(void, Unsafe_Park(JNIEnv *env, jobject unsafe, jboolean isAbsolute, jlong time)) {
1132 EventThreadPark event;
1133 HOTSPOT_THREAD_PARK_BEGIN((uintptr_t) thread->parker(), (int) isAbsolute, time);
1134
1135 JavaThreadParkedState jtps(thread, time != 0);
1136 thread->parker()->park(isAbsolute != 0, time);
1137
1138 HOTSPOT_THREAD_PARK_END((uintptr_t) thread->parker());
1139
1140 if (event.should_commit()) {
1141 oop obj = thread->current_park_blocker();
1142 event.set_parkedClass((obj != NULL) ? obj->klass() : NULL);
1143 event.set_timeout(time);
1144 event.set_address((obj != NULL) ? (TYPE_ADDRESS) cast_from_oop<uintptr_t>(obj) : 0);
1145 event.commit();
1146 }
1147 } UNSAFE_END
1148
1149 UNSAFE_ENTRY(void, Unsafe_Unpark(JNIEnv *env, jobject unsafe, jobject jthread)) {
1150 Parker* p = NULL;
1151
1152 if (jthread != NULL) {
1153 oop java_thread = JNIHandles::resolve_non_null(jthread);
1154 if (java_thread != NULL) {
1155 jlong lp = java_lang_Thread::park_event(java_thread);
1156 if (lp != 0) {
1157 // This cast is OK even though the jlong might have been read
1158 // non-atomically on 32bit systems, since there, one word will
1159 // always be zero anyway and the value set is always the same
1160 p = (Parker*)addr_from_java(lp);
1161 } else {
1162 // Grab lock if apparently null or using older version of library
1163 MutexLocker mu(Threads_lock);
1164 java_thread = JNIHandles::resolve_non_null(jthread);
1165
1166 if (java_thread != NULL) {
1167 JavaThread* thr = java_lang_Thread::thread(java_thread);
1168 if (thr != NULL) {
1169 p = thr->parker();
1170 if (p != NULL) { // Bind to Java thread for next time.
1171 java_lang_Thread::set_park_event(java_thread, addr_to_java(p));
1172 }
1173 }
1174 }
1175 }
1176 }
1177 }
1178
1179 if (p != NULL) {
1180 HOTSPOT_THREAD_UNPARK((uintptr_t) p);
1181 p->unpark();
1182 }
1183 } UNSAFE_END
1184
1185 UNSAFE_ENTRY(jint, Unsafe_GetLoadAverage0(JNIEnv *env, jobject unsafe, jdoubleArray loadavg, jint nelem)) {
1186 const int max_nelem = 3;
1187 double la[max_nelem];
1188 jint ret;
1189
1190 typeArrayOop a = typeArrayOop(JNIHandles::resolve_non_null(loadavg));
1191 assert(a->is_typeArray(), "must be type array");
1192
1193 ret = os::loadavg(la, nelem);
1194 if (ret == -1) {
1195 return -1;
1196 }
1197
1198 // if successful, ret is the number of samples actually retrieved.
1199 assert(ret >= 0 && ret <= max_nelem, "Unexpected loadavg return value");
1200 switch(ret) {
1201 case 3: a->double_at_put(2, (jdouble)la[2]); // fall through
1202 case 2: a->double_at_put(1, (jdouble)la[1]); // fall through
1203 case 1: a->double_at_put(0, (jdouble)la[0]); break;
1204 }
1205
1206 return ret;
1207 } UNSAFE_END
1208
1209
1210 /// JVM_RegisterUnsafeMethods
1211
1212 #define ADR "J"
1213
1214 #define LANG "Ljava/lang/"
1215
1216 #define OBJ LANG "Object;"
1217 #define CLS LANG "Class;"
1218 #define FLD LANG "reflect/Field;"
1219 #define THR LANG "Throwable;"
1220
1221 #define DC_Args LANG "String;[BII" LANG "ClassLoader;" "Ljava/security/ProtectionDomain;"
1222 #define DAC_Args CLS "[B[" OBJ
1223
1224 #define CC (char*) /*cast a literal from (const char*)*/
1225 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
1226
1227 #define DECLARE_GETPUTOOP(Type, Desc) \
1228 {CC "get" #Type, CC "(" OBJ "J)" #Desc, FN_PTR(Unsafe_Get##Type)}, \
1229 {CC "put" #Type, CC "(" OBJ "J" #Desc ")V", FN_PTR(Unsafe_Put##Type)}, \
1230 {CC "get" #Type "Volatile", CC "(" OBJ "J)" #Desc, FN_PTR(Unsafe_Get##Type##Volatile)}, \
1231 {CC "put" #Type "Volatile", CC "(" OBJ "J" #Desc ")V", FN_PTR(Unsafe_Put##Type##Volatile)}
1232
1233
1234 static JNINativeMethod jdk_internal_misc_Unsafe_methods[] = {
1235 {CC "getObject", CC "(" OBJ "J)" OBJ "", FN_PTR(Unsafe_GetObject)},
1236 {CC "putObject", CC "(" OBJ "J" OBJ ")V", FN_PTR(Unsafe_PutObject)},
1237 {CC "getObjectVolatile",CC "(" OBJ "J)" OBJ "", FN_PTR(Unsafe_GetObjectVolatile)},
1238 {CC "putObjectVolatile",CC "(" OBJ "J" OBJ ")V", FN_PTR(Unsafe_PutObjectVolatile)},
1239
1240 {CC "getUncompressedObject", CC "(" ADR ")" OBJ, FN_PTR(Unsafe_GetUncompressedObject)},
1241
1242 DECLARE_GETPUTOOP(Boolean, Z),
1243 DECLARE_GETPUTOOP(Byte, B),
1244 DECLARE_GETPUTOOP(Short, S),
1245 DECLARE_GETPUTOOP(Char, C),
1246 DECLARE_GETPUTOOP(Int, I),
1247 DECLARE_GETPUTOOP(Long, J),
1248 DECLARE_GETPUTOOP(Float, F),
1249 DECLARE_GETPUTOOP(Double, D),
1250
1251 {CC "allocateMemory0", CC "(J)" ADR, FN_PTR(Unsafe_AllocateMemory0)},
1252 {CC "reallocateMemory0", CC "(" ADR "J)" ADR, FN_PTR(Unsafe_ReallocateMemory0)},
1253 {CC "freeMemory0", CC "(" ADR ")V", FN_PTR(Unsafe_FreeMemory0)},
1254
1255 {CC "objectFieldOffset0", CC "(" FLD ")J", FN_PTR(Unsafe_ObjectFieldOffset0)},
1256 {CC "objectFieldOffset1", CC "(" CLS LANG "String;)J", FN_PTR(Unsafe_ObjectFieldOffset1)},
1257 {CC "staticFieldOffset0", CC "(" FLD ")J", FN_PTR(Unsafe_StaticFieldOffset0)},
1258 {CC "staticFieldBase0", CC "(" FLD ")" OBJ, FN_PTR(Unsafe_StaticFieldBase0)},
1259 {CC "ensureClassInitialized0", CC "(" CLS ")V", FN_PTR(Unsafe_EnsureClassInitialized0)},
1260 {CC "arrayBaseOffset0", CC "(" CLS ")I", FN_PTR(Unsafe_ArrayBaseOffset0)},
1261 {CC "arrayIndexScale0", CC "(" CLS ")I", FN_PTR(Unsafe_ArrayIndexScale0)},
1262 {CC "addressSize0", CC "()I", FN_PTR(Unsafe_AddressSize0)},
1263 {CC "pageSize", CC "()I", FN_PTR(Unsafe_PageSize)},
1264
1265 {CC "defineClass0", CC "(" DC_Args ")" CLS, FN_PTR(Unsafe_DefineClass0)},
1266 {CC "allocateInstance", CC "(" CLS ")" OBJ, FN_PTR(Unsafe_AllocateInstance)},
1267 {CC "throwException", CC "(" THR ")V", FN_PTR(Unsafe_ThrowException)},
1268 {CC "compareAndSetObject",CC "(" OBJ "J" OBJ "" OBJ ")Z", FN_PTR(Unsafe_CompareAndSetObject)},
1269 {CC "compareAndSetInt", CC "(" OBJ "J""I""I"")Z", FN_PTR(Unsafe_CompareAndSetInt)},
1270 {CC "compareAndSetLong", CC "(" OBJ "J""J""J"")Z", FN_PTR(Unsafe_CompareAndSetLong)},
1271 {CC "compareAndExchangeObject", CC "(" OBJ "J" OBJ "" OBJ ")" OBJ, FN_PTR(Unsafe_CompareAndExchangeObject)},
1272 {CC "compareAndExchangeInt", CC "(" OBJ "J""I""I"")I", FN_PTR(Unsafe_CompareAndExchangeInt)},
1273 {CC "compareAndExchangeLong", CC "(" OBJ "J""J""J"")J", FN_PTR(Unsafe_CompareAndExchangeLong)},
1274
1275 {CC "park", CC "(ZJ)V", FN_PTR(Unsafe_Park)},
1276 {CC "unpark", CC "(" OBJ ")V", FN_PTR(Unsafe_Unpark)},
1277
1278 {CC "getLoadAverage0", CC "([DI)I", FN_PTR(Unsafe_GetLoadAverage0)},
1279
1280 {CC "copyMemory0", CC "(" OBJ "J" OBJ "JJ)V", FN_PTR(Unsafe_CopyMemory0)},
1281 {CC "copySwapMemory0", CC "(" OBJ "J" OBJ "JJJ)V", FN_PTR(Unsafe_CopySwapMemory0)},
1282 {CC "setMemory0", CC "(" OBJ "JJB)V", FN_PTR(Unsafe_SetMemory0)},
1283
1284 {CC "defineAnonymousClass0", CC "(" DAC_Args ")" CLS, FN_PTR(Unsafe_DefineAnonymousClass0)},
1285
1286 {CC "shouldBeInitialized0", CC "(" CLS ")Z", FN_PTR(Unsafe_ShouldBeInitialized0)},
1287
1288 {CC "loadFence", CC "()V", FN_PTR(Unsafe_LoadFence)},
1289 {CC "storeFence", CC "()V", FN_PTR(Unsafe_StoreFence)},
1290 {CC "fullFence", CC "()V", FN_PTR(Unsafe_FullFence)},
1291
1292 {CC "isBigEndian0", CC "()Z", FN_PTR(Unsafe_isBigEndian0)},
1293 {CC "unalignedAccess0", CC "()Z", FN_PTR(Unsafe_unalignedAccess0)}
1294 };
1295
1296 #undef CC
1297 #undef FN_PTR
1298
1299 #undef ADR
1300 #undef LANG
1301 #undef OBJ
1302 #undef CLS
1303 #undef FLD
1304 #undef THR
1305 #undef DC_Args
1306 #undef DAC_Args
1307
1308 #undef DECLARE_GETPUTOOP
1309
1310
1311 // This function is exported, used by NativeLookup.
1312 // The Unsafe_xxx functions above are called only from the interpreter.
1313 // The optimizer looks at names and signatures to recognize
1314 // individual functions.
1315
1316 JVM_ENTRY(void, JVM_RegisterJDKInternalMiscUnsafeMethods(JNIEnv *env, jclass unsafeclass)) {
1317 ThreadToNativeFromVM ttnfv(thread);
1318
1319 int ok = env->RegisterNatives(unsafeclass, jdk_internal_misc_Unsafe_methods, sizeof(jdk_internal_misc_Unsafe_methods)/sizeof(JNINativeMethod));
1320 guarantee(ok == 0, "register jdk.internal.misc.Unsafe natives");
1321 } JVM_END