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