1 /*
2 * Copyright (c) 2000, 2016, 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. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.internal.misc;
27
28 import java.lang.reflect.Field;
29 import java.security.ProtectionDomain;
30
31 import sun.reflect.CallerSensitive;
32 import sun.reflect.Reflection;
33 import jdk.internal.misc.VM;
34
35 import jdk.internal.HotSpotIntrinsicCandidate;
36
37
38 /**
39 * A collection of methods for performing low-level, unsafe operations.
40 * Although the class and all methods are public, use of this class is
41 * limited because only trusted code can obtain instances of it.
42 *
43 * <em>Note:</em> It is the resposibility of the caller to make sure
44 * arguments are checked before methods of this class are
45 * called. While some rudimentary checks are performed on the input,
46 * the checks are best effort and when performance is an overriding
47 * priority, as when methods of this class are optimized by the
48 * runtime compiler, some or all checks (if any) may be elided. Hence,
49 * the caller must not rely on the checks and corresponding
50 * exceptions!
51 *
52 * @author John R. Rose
53 * @see #getUnsafe
54 */
55
56 public final class Unsafe {
57
58 private static native void registerNatives();
59 static {
60 registerNatives();
61 sun.reflect.Reflection.registerMethodsToFilter(Unsafe.class, "getUnsafe");
62 }
63
64 private Unsafe() {}
65
66 private static final Unsafe theUnsafe = new Unsafe();
67
68 /**
69 * Provides the caller with the capability of performing unsafe
70 * operations.
71 *
72 * <p>The returned {@code Unsafe} object should be carefully guarded
73 * by the caller, since it can be used to read and write data at arbitrary
74 * memory addresses. It must never be passed to untrusted code.
75 *
76 * <p>Most methods in this class are very low-level, and correspond to a
77 * small number of hardware instructions (on typical machines). Compilers
78 * are encouraged to optimize these methods accordingly.
79 *
80 * <p>Here is a suggested idiom for using unsafe operations:
81 *
82 * <pre> {@code
83 * class MyTrustedClass {
84 * private static final Unsafe unsafe = Unsafe.getUnsafe();
85 * ...
86 * private long myCountAddress = ...;
87 * public int getCount() { return unsafe.getByte(myCountAddress); }
88 * }}</pre>
89 *
90 * (It may assist compilers to make the local variable {@code final}.)
91 *
92 * @throws SecurityException if a security manager exists and its
93 * {@code checkPropertiesAccess} method doesn't allow
94 * access to the system properties.
95 */
96 @CallerSensitive
97 public static Unsafe getUnsafe() {
98 Class<?> caller = Reflection.getCallerClass();
99 if (!VM.isSystemDomainLoader(caller.getClassLoader()))
100 throw new SecurityException("Unsafe");
101 return theUnsafe;
102 }
103
104 /// peek and poke operations
105 /// (compilers should optimize these to memory ops)
106
107 // These work on object fields in the Java heap.
108 // They will not work on elements of packed arrays.
109
110 /**
111 * Fetches a value from a given Java variable.
112 * More specifically, fetches a field or array element within the given
113 * object {@code o} at the given offset, or (if {@code o} is null)
114 * from the memory address whose numerical value is the given offset.
115 * <p>
116 * The results are undefined unless one of the following cases is true:
117 * <ul>
118 * <li>The offset was obtained from {@link #objectFieldOffset} on
119 * the {@link java.lang.reflect.Field} of some Java field and the object
120 * referred to by {@code o} is of a class compatible with that
121 * field's class.
122 *
123 * <li>The offset and object reference {@code o} (either null or
124 * non-null) were both obtained via {@link #staticFieldOffset}
125 * and {@link #staticFieldBase} (respectively) from the
126 * reflective {@link Field} representation of some Java field.
127 *
128 * <li>The object referred to by {@code o} is an array, and the offset
129 * is an integer of the form {@code B+N*S}, where {@code N} is
130 * a valid index into the array, and {@code B} and {@code S} are
131 * the values obtained by {@link #arrayBaseOffset} and {@link
132 * #arrayIndexScale} (respectively) from the array's class. The value
133 * referred to is the {@code N}<em>th</em> element of the array.
134 *
135 * </ul>
136 * <p>
137 * If one of the above cases is true, the call references a specific Java
138 * variable (field or array element). However, the results are undefined
139 * if that variable is not in fact of the type returned by this method.
140 * <p>
141 * This method refers to a variable by means of two parameters, and so
142 * it provides (in effect) a <em>double-register</em> addressing mode
143 * for Java variables. When the object reference is null, this method
144 * uses its offset as an absolute address. This is similar in operation
145 * to methods such as {@link #getInt(long)}, which provide (in effect) a
146 * <em>single-register</em> addressing mode for non-Java variables.
147 * However, because Java variables may have a different layout in memory
148 * from non-Java variables, programmers should not assume that these
149 * two addressing modes are ever equivalent. Also, programmers should
150 * remember that offsets from the double-register addressing mode cannot
151 * be portably confused with longs used in the single-register addressing
152 * mode.
153 *
154 * @param o Java heap object in which the variable resides, if any, else
155 * null
156 * @param offset indication of where the variable resides in a Java heap
157 * object, if any, else a memory address locating the variable
158 * statically
159 * @return the value fetched from the indicated Java variable
160 * @throws RuntimeException No defined exceptions are thrown, not even
161 * {@link NullPointerException}
162 */
163 @HotSpotIntrinsicCandidate
164 public native int getInt(Object o, long offset);
165
166 /**
167 * Stores a value into a given Java variable.
168 * <p>
169 * The first two parameters are interpreted exactly as with
170 * {@link #getInt(Object, long)} to refer to a specific
171 * Java variable (field or array element). The given value
172 * is stored into that variable.
173 * <p>
174 * The variable must be of the same type as the method
175 * parameter {@code x}.
176 *
177 * @param o Java heap object in which the variable resides, if any, else
178 * null
179 * @param offset indication of where the variable resides in a Java heap
180 * object, if any, else a memory address locating the variable
181 * statically
182 * @param x the value to store into the indicated Java variable
183 * @throws RuntimeException No defined exceptions are thrown, not even
184 * {@link NullPointerException}
185 */
186 @HotSpotIntrinsicCandidate
187 public native void putInt(Object o, long offset, int x);
188
189 /**
190 * Fetches a reference value from a given Java variable.
191 * @see #getInt(Object, long)
192 */
193 @HotSpotIntrinsicCandidate
194 public native Object getObject(Object o, long offset);
195
196 /**
197 * Stores a reference value into a given Java variable.
198 * <p>
199 * Unless the reference {@code x} being stored is either null
200 * or matches the field type, the results are undefined.
201 * If the reference {@code o} is non-null, card marks or
202 * other store barriers for that object (if the VM requires them)
203 * are updated.
204 * @see #putInt(Object, long, int)
205 */
206 @HotSpotIntrinsicCandidate
207 public native void putObject(Object o, long offset, Object x);
208
209 /** @see #getInt(Object, long) */
210 @HotSpotIntrinsicCandidate
211 public native boolean getBoolean(Object o, long offset);
212 /** @see #putInt(Object, long, int) */
213 @HotSpotIntrinsicCandidate
214 public native void putBoolean(Object o, long offset, boolean x);
215 /** @see #getInt(Object, long) */
216 @HotSpotIntrinsicCandidate
217 public native byte getByte(Object o, long offset);
218 /** @see #putInt(Object, long, int) */
219 @HotSpotIntrinsicCandidate
220 public native void putByte(Object o, long offset, byte x);
221 /** @see #getInt(Object, long) */
222 @HotSpotIntrinsicCandidate
223 public native short getShort(Object o, long offset);
224 /** @see #putInt(Object, long, int) */
225 @HotSpotIntrinsicCandidate
226 public native void putShort(Object o, long offset, short x);
227 /** @see #getInt(Object, long) */
228 @HotSpotIntrinsicCandidate
229 public native char getChar(Object o, long offset);
230 /** @see #putInt(Object, long, int) */
231 @HotSpotIntrinsicCandidate
232 public native void putChar(Object o, long offset, char x);
233 /** @see #getInt(Object, long) */
234 @HotSpotIntrinsicCandidate
235 public native long getLong(Object o, long offset);
236 /** @see #putInt(Object, long, int) */
237 @HotSpotIntrinsicCandidate
238 public native void putLong(Object o, long offset, long x);
239 /** @see #getInt(Object, long) */
240 @HotSpotIntrinsicCandidate
241 public native float getFloat(Object o, long offset);
242 /** @see #putInt(Object, long, int) */
243 @HotSpotIntrinsicCandidate
244 public native void putFloat(Object o, long offset, float x);
245 /** @see #getInt(Object, long) */
246 @HotSpotIntrinsicCandidate
247 public native double getDouble(Object o, long offset);
248 /** @see #putInt(Object, long, int) */
249 @HotSpotIntrinsicCandidate
250 public native void putDouble(Object o, long offset, double x);
251
252 // These read VM internal data.
253
254 /**
255 * Fetches an uncompressed reference value from a given native variable
256 * ignoring the VM's compressed references mode.
257 *
258 * @param address a memory address locating the variable
259 * @return the value fetched from the indicated native variable
260 */
261 public native Object getUncompressedObject(long address);
262
263 /**
264 * Fetches the {@link java.lang.Class} Java mirror for the given native
265 * metaspace {@code Klass} pointer.
266 *
267 * @param metaspaceKlass a native metaspace {@code Klass} pointer
268 * @return the {@link java.lang.Class} Java mirror
269 */
270 public native Class<?> getJavaMirror(long metaspaceKlass);
271
272 /**
273 * Fetches a native metaspace {@code Klass} pointer for the given Java
274 * object.
275 *
276 * @param o Java heap object for which to fetch the class pointer
277 * @return a native metaspace {@code Klass} pointer
278 */
279 public native long getKlassPointer(Object o);
280
281 // These work on values in the C heap.
282
283 /**
284 * Fetches a value from a given memory address. If the address is zero, or
285 * does not point into a block obtained from {@link #allocateMemory}, the
286 * results are undefined.
287 *
288 * @see #allocateMemory
289 */
290 @HotSpotIntrinsicCandidate
291 public native byte getByte(long address);
292
293 /**
294 * Stores a value into a given memory address. If the address is zero, or
295 * does not point into a block obtained from {@link #allocateMemory}, the
296 * results are undefined.
297 *
298 * @see #getByte(long)
299 */
300 @HotSpotIntrinsicCandidate
301 public native void putByte(long address, byte x);
302
303 /** @see #getByte(long) */
304 @HotSpotIntrinsicCandidate
305 public native short getShort(long address);
306 /** @see #putByte(long, byte) */
307 @HotSpotIntrinsicCandidate
308 public native void putShort(long address, short x);
309 /** @see #getByte(long) */
310 @HotSpotIntrinsicCandidate
311 public native char getChar(long address);
312 /** @see #putByte(long, byte) */
313 @HotSpotIntrinsicCandidate
314 public native void putChar(long address, char x);
315 /** @see #getByte(long) */
316 @HotSpotIntrinsicCandidate
317 public native int getInt(long address);
318 /** @see #putByte(long, byte) */
319 @HotSpotIntrinsicCandidate
320 public native void putInt(long address, int x);
321 /** @see #getByte(long) */
322 @HotSpotIntrinsicCandidate
323 public native long getLong(long address);
324 /** @see #putByte(long, byte) */
325 @HotSpotIntrinsicCandidate
326 public native void putLong(long address, long x);
327 /** @see #getByte(long) */
328 @HotSpotIntrinsicCandidate
329 public native float getFloat(long address);
330 /** @see #putByte(long, byte) */
331 @HotSpotIntrinsicCandidate
332 public native void putFloat(long address, float x);
333 /** @see #getByte(long) */
334 @HotSpotIntrinsicCandidate
335 public native double getDouble(long address);
336 /** @see #putByte(long, byte) */
337 @HotSpotIntrinsicCandidate
338 public native void putDouble(long address, double x);
339
340 /**
341 * Fetches a native pointer from a given memory address. If the address is
342 * zero, or does not point into a block obtained from {@link
343 * #allocateMemory}, the results are undefined.
344 *
345 * <p>If the native pointer is less than 64 bits wide, it is extended as
346 * an unsigned number to a Java long. The pointer may be indexed by any
347 * given byte offset, simply by adding that offset (as a simple integer) to
348 * the long representing the pointer. The number of bytes actually read
349 * from the target address may be determined by consulting {@link
350 * #addressSize}.
351 *
352 * @see #allocateMemory
353 */
354 @HotSpotIntrinsicCandidate
355 public native long getAddress(long address);
356
357 /**
358 * Stores a native pointer into a given memory address. If the address is
359 * zero, or does not point into a block obtained from {@link
360 * #allocateMemory}, the results are undefined.
361 *
362 * <p>The number of bytes actually written at the target address may be
363 * determined by consulting {@link #addressSize}.
364 *
365 * @see #getAddress(long)
366 */
367 @HotSpotIntrinsicCandidate
368 public native void putAddress(long address, long x);
369
370
371
372 /// helper methods for validating various types of objects/values
373
374 /**
375 * Create an exception reflecting that some of the input was invalid
376 *
377 * <em>Note:</em> It is the resposibility of the caller to make
378 * sure arguments are checked before the methods are called. While
379 * some rudimentary checks are performed on the input, the checks
380 * are best effort and when performance is an overriding priority,
381 * as when methods of this class are optimized by the runtime
382 * compiler, some or all checks (if any) may be elided. Hence, the
383 * caller must not rely on the checks and corresponding
384 * exceptions!
385 *
386 * @return an exception object
387 */
388 private RuntimeException invalidInput() {
389 return new IllegalArgumentException();
390 }
391
392 /**
393 * Check if a value is 32-bit clean (32 MSB are all zero)
394 *
395 * @param value the 64-bit value to check
396 *
397 * @return true if the value is 32-bit clean
398 */
399 private boolean is32BitClean(long value) {
400 return value >>> 32 == 0;
401 }
402
403 /**
404 * Check the validity of a size (the equivalent of a size_t)
405 *
406 * @throws RuntimeException if the size is invalid
407 * (<em>Note:</em> after optimization, invalid inputs may
408 * go undetected, which will lead to unpredictable
409 * behavior)
410 */
411 private void checkSize(long size) {
412 if (ADDRESS_SIZE == 4) {
413 // Note: this will also check for negative sizes
414 if (!is32BitClean(size)) {
415 throw invalidInput();
416 }
417 } else if (size < 0) {
418 throw invalidInput();
419 }
420 }
421
422 /**
423 * Check the validity of a native address (the equivalent of void*)
424 *
425 * @throws RuntimeException if the address is invalid
426 * (<em>Note:</em> after optimization, invalid inputs may
427 * go undetected, which will lead to unpredictable
428 * behavior)
429 */
430 private void checkNativeAddress(long address) {
431 if (ADDRESS_SIZE == 4) {
432 // Accept both zero and sign extended pointers. A valid
433 // pointer will, after the +1 below, either have produced
434 // the value 0x0 or 0x1. Masking off the low bit allows
435 // for testing against 0.
436 if ((((address >> 32) + 1) & ~1) != 0) {
437 throw invalidInput();
438 }
439 }
440 }
441
442 /**
443 * Check the validity of an offset, relative to a base object
444 *
445 * @param o the base object
446 * @param offset the offset to check
447 *
448 * @throws RuntimeException if the size is invalid
449 * (<em>Note:</em> after optimization, invalid inputs may
450 * go undetected, which will lead to unpredictable
451 * behavior)
452 */
453 private void checkOffset(Object o, long offset) {
454 if (ADDRESS_SIZE == 4) {
455 // Note: this will also check for negative offsets
456 if (!is32BitClean(offset)) {
457 throw invalidInput();
458 }
459 } else if (offset < 0) {
460 throw invalidInput();
461 }
462 }
463
464 /**
465 * Check the validity of a double-register pointer
466 *
467 * Note: This code deliberately does *not* check for NPE for (at
468 * least) three reasons:
469 *
470 * 1) NPE is not just NULL/0 - there is a range of values all
471 * resulting in an NPE, which is not trivial to check for
472 *
473 * 2) It is the responsibility of the callers of Unsafe methods
474 * to verify the input, so throwing an exception here is not really
475 * useful - passing in a NULL pointer is a critical error and the
476 * must not expect an exception to be thrown anyway.
477 *
478 * 3) the actual operations will detect NULL pointers anyway by
479 * means of traps and signals (like SIGSEGV).
480 *
481 * @param o Java heap object, or null
482 * @param offset indication of where the variable resides in a Java heap
483 * object, if any, else a memory address locating the variable
484 * statically
485 *
486 * @throws RuntimeException if the pointer is invalid
487 * (<em>Note:</em> after optimization, invalid inputs may
488 * go undetected, which will lead to unpredictable
489 * behavior)
490 */
491 private void checkPointer(Object o, long offset) {
492 if (o == null) {
493 checkNativeAddress(offset);
494 } else {
495 checkOffset(o, offset);
496 }
497 }
498
499 /**
500 * Check if a type is a primitive array type
501 *
502 * @param c the type to check
503 *
504 * @return true if the type is a primitive array type
505 */
506 private void checkPrimitiveArray(Class<?> c) {
507 Class<?> componentType = c.getComponentType();
508 if (componentType == null || !componentType.isPrimitive()) {
509 throw invalidInput();
510 }
511 }
512
513 /**
514 * Check that a pointer is a valid primitive array type pointer
515 *
516 * Note: pointers off-heap are considered to be primitive arrays
517 *
518 * @throws RuntimeException if the pointer is invalid
519 * (<em>Note:</em> after optimization, invalid inputs may
520 * go undetected, which will lead to unpredictable
521 * behavior)
522 */
523 private void checkPrimitivePointer(Object o, long offset) {
524 checkPointer(o, offset);
525
526 if (o != null) {
527 // If on heap, it it must be a primitive array
528 checkPrimitiveArray(o.getClass());
529 }
530 }
531
532
533 /// wrappers for malloc, realloc, free:
534
535 /**
536 * Allocates a new block of native memory, of the given size in bytes. The
537 * contents of the memory are uninitialized; they will generally be
538 * garbage. The resulting native pointer will never be zero, and will be
539 * aligned for all value types. Dispose of this memory by calling {@link
540 * #freeMemory}, or resize it with {@link #reallocateMemory}.
541 *
542 * <em>Note:</em> It is the resposibility of the caller to make
543 * sure arguments are checked before the methods are called. While
544 * some rudimentary checks are performed on the input, the checks
545 * are best effort and when performance is an overriding priority,
546 * as when methods of this class are optimized by the runtime
547 * compiler, some or all checks (if any) may be elided. Hence, the
548 * caller must not rely on the checks and corresponding
549 * exceptions!
550 *
551 * @throws RuntimeException if the size is negative or too large
552 * for the native size_t type
553 *
554 * @throws OutOfMemoryError if the allocation is refused by the system
555 *
556 * @see #getByte(long)
557 * @see #putByte(long, byte)
558 */
559 public long allocateMemory(long bytes) {
560 allocateMemoryChecks(bytes);
561
562 if (bytes == 0) {
563 return 0;
564 }
565
566 long p = allocateMemory0(bytes);
567 if (p == 0) {
568 throw new OutOfMemoryError();
569 }
570
571 return p;
572 }
573
574 /**
575 * Validate the arguments to allocateMemory
576 *
577 * @throws RuntimeException if the arguments are invalid
578 * (<em>Note:</em> after optimization, invalid inputs may
579 * go undetected, which will lead to unpredictable
580 * behavior)
581 */
582 private void allocateMemoryChecks(long bytes) {
583 checkSize(bytes);
584 }
585
586 /**
587 * Resizes a new block of native memory, to the given size in bytes. The
588 * contents of the new block past the size of the old block are
589 * uninitialized; they will generally be garbage. The resulting native
590 * pointer will be zero if and only if the requested size is zero. The
591 * resulting native pointer will be aligned for all value types. Dispose
592 * of this memory by calling {@link #freeMemory}, or resize it with {@link
593 * #reallocateMemory}. The address passed to this method may be null, in
594 * which case an allocation will be performed.
595 *
596 * <em>Note:</em> It is the resposibility of the caller to make
597 * sure arguments are checked before the methods are called. While
598 * some rudimentary checks are performed on the input, the checks
599 * are best effort and when performance is an overriding priority,
600 * as when methods of this class are optimized by the runtime
601 * compiler, some or all checks (if any) may be elided. Hence, the
602 * caller must not rely on the checks and corresponding
603 * exceptions!
604 *
605 * @throws RuntimeException if the size is negative or too large
606 * for the native size_t type
607 *
608 * @throws OutOfMemoryError if the allocation is refused by the system
609 *
610 * @see #allocateMemory
611 */
612 public long reallocateMemory(long address, long bytes) {
613 reallocateMemoryChecks(address, bytes);
614
615 if (bytes == 0) {
616 freeMemory(address);
617 return 0;
618 }
619
620 long p = (address == 0) ? allocateMemory0(bytes) : reallocateMemory0(address, bytes);
621 if (p == 0) {
622 throw new OutOfMemoryError();
623 }
624
625 return p;
626 }
627
628 /**
629 * Validate the arguments to reallocateMemory
630 *
631 * @throws RuntimeException if the arguments are invalid
632 * (<em>Note:</em> after optimization, invalid inputs may
633 * go undetected, which will lead to unpredictable
634 * behavior)
635 */
636 private void reallocateMemoryChecks(long address, long bytes) {
637 checkPointer(null, address);
638 checkSize(bytes);
639 }
640
641 /**
642 * Sets all bytes in a given block of memory to a fixed value
643 * (usually zero).
644 *
645 * <p>This method determines a block's base address by means of two parameters,
646 * and so it provides (in effect) a <em>double-register</em> addressing mode,
647 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
648 * the offset supplies an absolute base address.
649 *
650 * <p>The stores are in coherent (atomic) units of a size determined
651 * by the address and length parameters. If the effective address and
652 * length are all even modulo 8, the stores take place in 'long' units.
653 * If the effective address and length are (resp.) even modulo 4 or 2,
654 * the stores take place in units of 'int' or 'short'.
655 *
656 * <em>Note:</em> It is the resposibility of the caller to make
657 * sure arguments are checked before the methods are called. While
658 * some rudimentary checks are performed on the input, the checks
659 * are best effort and when performance is an overriding priority,
660 * as when methods of this class are optimized by the runtime
661 * compiler, some or all checks (if any) may be elided. Hence, the
662 * caller must not rely on the checks and corresponding
663 * exceptions!
664 *
665 * @throws RuntimeException if any of the arguments is invalid
666 *
667 * @since 1.7
668 */
669 public void setMemory(Object o, long offset, long bytes, byte value) {
670 setMemoryChecks(o, offset, bytes, value);
671
672 if (bytes == 0) {
673 return;
674 }
675
676 setMemory0(o, offset, bytes, value);
677 }
678
679 /**
680 * Sets all bytes in a given block of memory to a fixed value
681 * (usually zero). This provides a <em>single-register</em> addressing mode,
682 * as discussed in {@link #getInt(Object,long)}.
683 *
684 * <p>Equivalent to {@code setMemory(null, address, bytes, value)}.
685 */
686 public void setMemory(long address, long bytes, byte value) {
687 setMemory(null, address, bytes, value);
688 }
689
690 /**
691 * Validate the arguments to setMemory
692 *
693 * @throws RuntimeException if the arguments are invalid
694 * (<em>Note:</em> after optimization, invalid inputs may
695 * go undetected, which will lead to unpredictable
696 * behavior)
697 */
698 private void setMemoryChecks(Object o, long offset, long bytes, byte value) {
699 checkPrimitivePointer(o, offset);
700 checkSize(bytes);
701 }
702
703 /**
704 * Sets all bytes in a given block of memory to a copy of another
705 * block.
706 *
707 * <p>This method determines each block's base address by means of two parameters,
708 * and so it provides (in effect) a <em>double-register</em> addressing mode,
709 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
710 * the offset supplies an absolute base address.
711 *
712 * <p>The transfers are in coherent (atomic) units of a size determined
713 * by the address and length parameters. If the effective addresses and
714 * length are all even modulo 8, the transfer takes place in 'long' units.
715 * If the effective addresses and length are (resp.) even modulo 4 or 2,
716 * the transfer takes place in units of 'int' or 'short'.
717 *
718 * <em>Note:</em> It is the resposibility of the caller to make
719 * sure arguments are checked before the methods are called. While
720 * some rudimentary checks are performed on the input, the checks
721 * are best effort and when performance is an overriding priority,
722 * as when methods of this class are optimized by the runtime
723 * compiler, some or all checks (if any) may be elided. Hence, the
724 * caller must not rely on the checks and corresponding
725 * exceptions!
726 *
727 * @throws RuntimeException if any of the arguments is invalid
728 *
729 * @since 1.7
730 */
731 public void copyMemory(Object srcBase, long srcOffset,
732 Object destBase, long destOffset,
733 long bytes) {
734 copyMemoryChecks(srcBase, srcOffset, destBase, destOffset, bytes);
735
736 if (bytes == 0) {
737 return;
738 }
739
740 copyMemory0(srcBase, srcOffset, destBase, destOffset, bytes);
741 }
742
743 /**
744 * Sets all bytes in a given block of memory to a copy of another
745 * block. This provides a <em>single-register</em> addressing mode,
746 * as discussed in {@link #getInt(Object,long)}.
747 *
748 * Equivalent to {@code copyMemory(null, srcAddress, null, destAddress, bytes)}.
749 */
750 public void copyMemory(long srcAddress, long destAddress, long bytes) {
751 copyMemory(null, srcAddress, null, destAddress, bytes);
752 }
753
754 /**
755 * Validate the arguments to copyMemory
756 *
757 * @throws RuntimeException if any of the arguments is invalid
758 * (<em>Note:</em> after optimization, invalid inputs may
759 * go undetected, which will lead to unpredictable
760 * behavior)
761 */
762 private void copyMemoryChecks(Object srcBase, long srcOffset,
763 Object destBase, long destOffset,
764 long bytes) {
765 checkSize(bytes);
766 checkPrimitivePointer(srcBase, srcOffset);
767 checkPrimitivePointer(destBase, destOffset);
768 }
769
770 /**
771 * Copies all elements from one block of memory to another block,
772 * *unconditionally* byte swapping the elements on the fly.
773 *
774 * <p>This method determines each block's base address by means of two parameters,
775 * and so it provides (in effect) a <em>double-register</em> addressing mode,
776 * as discussed in {@link #getInt(Object,long)}. When the object reference is null,
777 * the offset supplies an absolute base address.
778 *
779 * <em>Note:</em> It is the resposibility of the caller to make
780 * sure arguments are checked before the methods are called. While
781 * some rudimentary checks are performed on the input, the checks
782 * are best effort and when performance is an overriding priority,
783 * as when methods of this class are optimized by the runtime
784 * compiler, some or all checks (if any) may be elided. Hence, the
785 * caller must not rely on the checks and corresponding
786 * exceptions!
787 *
788 * @throws RuntimeException if any of the arguments is invalid
789 *
790 * @since 9
791 */
792 public void copySwapMemory(Object srcBase, long srcOffset,
793 Object destBase, long destOffset,
794 long bytes, long elemSize) {
795 copySwapMemoryChecks(srcBase, srcOffset, destBase, destOffset, bytes, elemSize);
796
797 if (bytes == 0) {
798 return;
799 }
800
801 copySwapMemory0(srcBase, srcOffset, destBase, destOffset, bytes, elemSize);
802 }
803
804 private void copySwapMemoryChecks(Object srcBase, long srcOffset,
805 Object destBase, long destOffset,
806 long bytes, long elemSize) {
807 checkSize(bytes);
808
809 if (elemSize != 2 && elemSize != 4 && elemSize != 8) {
810 throw invalidInput();
811 }
812 if (bytes % elemSize != 0) {
813 throw invalidInput();
814 }
815
816 checkPrimitivePointer(srcBase, srcOffset);
817 checkPrimitivePointer(destBase, destOffset);
818 }
819
820 /**
821 * Copies all elements from one block of memory to another block, byte swapping the
822 * elements on the fly.
823 *
824 * This provides a <em>single-register</em> addressing mode, as
825 * discussed in {@link #getInt(Object,long)}.
826 *
827 * Equivalent to {@code copySwapMemory(null, srcAddress, null, destAddress, bytes, elemSize)}.
828 */
829 public void copySwapMemory(long srcAddress, long destAddress, long bytes, long elemSize) {
830 copySwapMemory(null, srcAddress, null, destAddress, bytes, elemSize);
831 }
832
833 /**
834 * Disposes of a block of native memory, as obtained from {@link
835 * #allocateMemory} or {@link #reallocateMemory}. The address passed to
836 * this method may be null, in which case no action is taken.
837 *
838 * <em>Note:</em> It is the resposibility of the caller to make
839 * sure arguments are checked before the methods are called. While
840 * some rudimentary checks are performed on the input, the checks
841 * are best effort and when performance is an overriding priority,
842 * as when methods of this class are optimized by the runtime
843 * compiler, some or all checks (if any) may be elided. Hence, the
844 * caller must not rely on the checks and corresponding
845 * exceptions!
846 *
847 * @throws RuntimeException if any of the arguments is invalid
848 *
849 * @see #allocateMemory
850 */
851 public void freeMemory(long address) {
852 freeMemoryChecks(address);
853
854 if (address == 0) {
855 return;
856 }
857
858 freeMemory0(address);
859 }
860
861 /**
862 * Validate the arguments to freeMemory
863 *
864 * @throws RuntimeException if the arguments are invalid
865 * (<em>Note:</em> after optimization, invalid inputs may
866 * go undetected, which will lead to unpredictable
867 * behavior)
868 */
869 private void freeMemoryChecks(long address) {
870 checkPointer(null, address);
871 }
872
873 /// random queries
874
875 /**
876 * This constant differs from all results that will ever be returned from
877 * {@link #staticFieldOffset}, {@link #objectFieldOffset},
878 * or {@link #arrayBaseOffset}.
879 */
880 public static final int INVALID_FIELD_OFFSET = -1;
881
882 /**
883 * Reports the location of a given field in the storage allocation of its
884 * class. Do not expect to perform any sort of arithmetic on this offset;
885 * it is just a cookie which is passed to the unsafe heap memory accessors.
886 *
887 * <p>Any given field will always have the same offset and base, and no
888 * two distinct fields of the same class will ever have the same offset
889 * and base.
890 *
891 * <p>As of 1.4.1, offsets for fields are represented as long values,
892 * although the Sun JVM does not use the most significant 32 bits.
893 * However, JVM implementations which store static fields at absolute
894 * addresses can use long offsets and null base pointers to express
895 * the field locations in a form usable by {@link #getInt(Object,long)}.
896 * Therefore, code which will be ported to such JVMs on 64-bit platforms
897 * must preserve all bits of static field offsets.
898 * @see #getInt(Object, long)
899 */
900 public long objectFieldOffset(Field f) {
901 if (f == null) {
902 throw new NullPointerException();
903 }
904
905 return objectFieldOffset0(f);
906 }
907
908 /**
909 * Reports the location of a given static field, in conjunction with {@link
910 * #staticFieldBase}.
911 * <p>Do not expect to perform any sort of arithmetic on this offset;
912 * it is just a cookie which is passed to the unsafe heap memory accessors.
913 *
914 * <p>Any given field will always have the same offset, and no two distinct
915 * fields of the same class will ever have the same offset.
916 *
917 * <p>As of 1.4.1, offsets for fields are represented as long values,
918 * although the Sun JVM does not use the most significant 32 bits.
919 * It is hard to imagine a JVM technology which needs more than
920 * a few bits to encode an offset within a non-array object,
921 * However, for consistency with other methods in this class,
922 * this method reports its result as a long value.
923 * @see #getInt(Object, long)
924 */
925 public long staticFieldOffset(Field f) {
926 if (f == null) {
927 throw new NullPointerException();
928 }
929
930 return staticFieldOffset0(f);
931 }
932
933 /**
934 * Reports the location of a given static field, in conjunction with {@link
935 * #staticFieldOffset}.
936 * <p>Fetch the base "Object", if any, with which static fields of the
937 * given class can be accessed via methods like {@link #getInt(Object,
938 * long)}. This value may be null. This value may refer to an object
939 * which is a "cookie", not guaranteed to be a real Object, and it should
940 * not be used in any way except as argument to the get and put routines in
941 * this class.
942 */
943 public Object staticFieldBase(Field f) {
944 if (f == null) {
945 throw new NullPointerException();
946 }
947
948 return staticFieldBase0(f);
949 }
950
951 /**
952 * Detects if the given class may need to be initialized. This is often
953 * needed in conjunction with obtaining the static field base of a
954 * class.
955 * @return false only if a call to {@code ensureClassInitialized} would have no effect
956 */
957 public boolean shouldBeInitialized(Class<?> c) {
958 if (c == null) {
959 throw new NullPointerException();
960 }
961
962 return shouldBeInitialized0(c);
963 }
964
965 /**
966 * Ensures the given class has been initialized. This is often
967 * needed in conjunction with obtaining the static field base of a
968 * class.
969 */
970 public void ensureClassInitialized(Class<?> c) {
971 if (c == null) {
972 throw new NullPointerException();
973 }
974
975 ensureClassInitialized0(c);
976 }
977
978 /**
979 * Reports the offset of the first element in the storage allocation of a
980 * given array class. If {@link #arrayIndexScale} returns a non-zero value
981 * for the same class, you may use that scale factor, together with this
982 * base offset, to form new offsets to access elements of arrays of the
983 * given class.
984 *
985 * @see #getInt(Object, long)
986 * @see #putInt(Object, long, int)
987 */
988 public int arrayBaseOffset(Class<?> arrayClass) {
989 if (arrayClass == null) {
990 throw new NullPointerException();
991 }
992
993 return arrayBaseOffset0(arrayClass);
994 }
995
996
997 /** The value of {@code arrayBaseOffset(boolean[].class)} */
998 public static final int ARRAY_BOOLEAN_BASE_OFFSET
999 = theUnsafe.arrayBaseOffset(boolean[].class);
1000
1001 /** The value of {@code arrayBaseOffset(byte[].class)} */
1002 public static final int ARRAY_BYTE_BASE_OFFSET
1003 = theUnsafe.arrayBaseOffset(byte[].class);
1004
1005 /** The value of {@code arrayBaseOffset(short[].class)} */
1006 public static final int ARRAY_SHORT_BASE_OFFSET
1007 = theUnsafe.arrayBaseOffset(short[].class);
1008
1009 /** The value of {@code arrayBaseOffset(char[].class)} */
1010 public static final int ARRAY_CHAR_BASE_OFFSET
1011 = theUnsafe.arrayBaseOffset(char[].class);
1012
1013 /** The value of {@code arrayBaseOffset(int[].class)} */
1014 public static final int ARRAY_INT_BASE_OFFSET
1015 = theUnsafe.arrayBaseOffset(int[].class);
1016
1017 /** The value of {@code arrayBaseOffset(long[].class)} */
1018 public static final int ARRAY_LONG_BASE_OFFSET
1019 = theUnsafe.arrayBaseOffset(long[].class);
1020
1021 /** The value of {@code arrayBaseOffset(float[].class)} */
1022 public static final int ARRAY_FLOAT_BASE_OFFSET
1023 = theUnsafe.arrayBaseOffset(float[].class);
1024
1025 /** The value of {@code arrayBaseOffset(double[].class)} */
1026 public static final int ARRAY_DOUBLE_BASE_OFFSET
1027 = theUnsafe.arrayBaseOffset(double[].class);
1028
1029 /** The value of {@code arrayBaseOffset(Object[].class)} */
1030 public static final int ARRAY_OBJECT_BASE_OFFSET
1031 = theUnsafe.arrayBaseOffset(Object[].class);
1032
1033 /**
1034 * Reports the scale factor for addressing elements in the storage
1035 * allocation of a given array class. However, arrays of "narrow" types
1036 * will generally not work properly with accessors like {@link
1037 * #getByte(Object, long)}, so the scale factor for such classes is reported
1038 * as zero.
1039 *
1040 * @see #arrayBaseOffset
1041 * @see #getInt(Object, long)
1042 * @see #putInt(Object, long, int)
1043 */
1044 public int arrayIndexScale(Class<?> arrayClass) {
1045 if (arrayClass == null) {
1046 throw new NullPointerException();
1047 }
1048
1049 return arrayIndexScale0(arrayClass);
1050 }
1051
1052
1053 /** The value of {@code arrayIndexScale(boolean[].class)} */
1054 public static final int ARRAY_BOOLEAN_INDEX_SCALE
1055 = theUnsafe.arrayIndexScale(boolean[].class);
1056
1057 /** The value of {@code arrayIndexScale(byte[].class)} */
1058 public static final int ARRAY_BYTE_INDEX_SCALE
1059 = theUnsafe.arrayIndexScale(byte[].class);
1060
1061 /** The value of {@code arrayIndexScale(short[].class)} */
1062 public static final int ARRAY_SHORT_INDEX_SCALE
1063 = theUnsafe.arrayIndexScale(short[].class);
1064
1065 /** The value of {@code arrayIndexScale(char[].class)} */
1066 public static final int ARRAY_CHAR_INDEX_SCALE
1067 = theUnsafe.arrayIndexScale(char[].class);
1068
1069 /** The value of {@code arrayIndexScale(int[].class)} */
1070 public static final int ARRAY_INT_INDEX_SCALE
1071 = theUnsafe.arrayIndexScale(int[].class);
1072
1073 /** The value of {@code arrayIndexScale(long[].class)} */
1074 public static final int ARRAY_LONG_INDEX_SCALE
1075 = theUnsafe.arrayIndexScale(long[].class);
1076
1077 /** The value of {@code arrayIndexScale(float[].class)} */
1078 public static final int ARRAY_FLOAT_INDEX_SCALE
1079 = theUnsafe.arrayIndexScale(float[].class);
1080
1081 /** The value of {@code arrayIndexScale(double[].class)} */
1082 public static final int ARRAY_DOUBLE_INDEX_SCALE
1083 = theUnsafe.arrayIndexScale(double[].class);
1084
1085 /** The value of {@code arrayIndexScale(Object[].class)} */
1086 public static final int ARRAY_OBJECT_INDEX_SCALE
1087 = theUnsafe.arrayIndexScale(Object[].class);
1088
1089 /**
1090 * Reports the size in bytes of a native pointer, as stored via {@link
1091 * #putAddress}. This value will be either 4 or 8. Note that the sizes of
1092 * other primitive types (as stored in native memory blocks) is determined
1093 * fully by their information content.
1094 */
1095 public int addressSize() {
1096 return ADDRESS_SIZE;
1097 }
1098
1099 /** The value of {@code addressSize()} */
1100 public static final int ADDRESS_SIZE = theUnsafe.addressSize0();
1101
1102 /**
1103 * Reports the size in bytes of a native memory page (whatever that is).
1104 * This value will always be a power of two.
1105 */
1106 public native int pageSize();
1107
1108
1109 /// random trusted operations from JNI:
1110
1111 /**
1112 * Tells the VM to define a class, without security checks. By default, the
1113 * class loader and protection domain come from the caller's class.
1114 */
1115 public Class<?> defineClass(String name, byte[] b, int off, int len,
1116 ClassLoader loader,
1117 ProtectionDomain protectionDomain) {
1118 if (b == null) {
1119 throw new NullPointerException();
1120 }
1121 if (len < 0) {
1122 throw new ArrayIndexOutOfBoundsException();
1123 }
1124
1125 return defineClass0(name, b, off, len, loader, protectionDomain);
1126 }
1127
1128 public native Class<?> defineClass0(String name, byte[] b, int off, int len,
1129 ClassLoader loader,
1130 ProtectionDomain protectionDomain);
1131
1132 /**
1133 * Defines a class but does not make it known to the class loader or system dictionary.
1134 * <p>
1135 * For each CP entry, the corresponding CP patch must either be null or have
1136 * the a format that matches its tag:
1137 * <ul>
1138 * <li>Integer, Long, Float, Double: the corresponding wrapper object type from java.lang
1139 * <li>Utf8: a string (must have suitable syntax if used as signature or name)
1140 * <li>Class: any java.lang.Class object
1141 * <li>String: any object (not just a java.lang.String)
1142 * <li>InterfaceMethodRef: (NYI) a method handle to invoke on that call site's arguments
1143 * </ul>
1144 * @param hostClass context for linkage, access control, protection domain, and class loader
1145 * @param data bytes of a class file
1146 * @param cpPatches where non-null entries exist, they replace corresponding CP entries in data
1147 */
1148 public Class<?> defineAnonymousClass(Class<?> hostClass, byte[] data, Object[] cpPatches) {
1149 if (hostClass == null || data == null) {
1150 throw new NullPointerException();
1151 }
1152
1153 return defineAnonymousClass0(hostClass, data, cpPatches);
1154 }
1155
1156 /**
1157 * Allocates an instance but does not run any constructor.
1158 * Initializes the class if it has not yet been.
1159 */
1160 @HotSpotIntrinsicCandidate
1161 public native Object allocateInstance(Class<?> cls)
1162 throws InstantiationException;
1163
1164 /** Throws the exception without telling the verifier. */
1165 public native void throwException(Throwable ee);
1166
1167 /**
1168 * Atomically updates Java variable to {@code x} if it is currently
1169 * holding {@code expected}.
1170 *
1171 * <p>This operation has memory semantics of a {@code volatile} read
1172 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1173 *
1174 * @return {@code true} if successful
1175 */
1176 @HotSpotIntrinsicCandidate
1177 public final native boolean compareAndSwapObject(Object o, long offset,
1178 Object expected,
1179 Object x);
1180
1181 /**
1182 * Atomically updates Java variable to {@code x} if it is currently
1183 * holding {@code expected}.
1184 *
1185 * <p>This operation has memory semantics of a {@code volatile} read
1186 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1187 *
1188 * @return {@code true} if successful
1189 */
1190 @HotSpotIntrinsicCandidate
1191 public final native boolean compareAndSwapInt(Object o, long offset,
1192 int expected,
1193 int x);
1194
1195 /**
1196 * Atomically updates Java variable to {@code x} if it is currently
1197 * holding {@code expected}.
1198 *
1199 * <p>This operation has memory semantics of a {@code volatile} read
1200 * and write. Corresponds to C11 atomic_compare_exchange_strong.
1201 *
1202 * @return {@code true} if successful
1203 */
1204 @HotSpotIntrinsicCandidate
1205 public final native boolean compareAndSwapLong(Object o, long offset,
1206 long expected,
1207 long x);
1208
1209 /**
1210 * Fetches a reference value from a given Java variable, with volatile
1211 * load semantics. Otherwise identical to {@link #getObject(Object, long)}
1212 */
1213 @HotSpotIntrinsicCandidate
1214 public native Object getObjectVolatile(Object o, long offset);
1215
1216 /**
1217 * Stores a reference value into a given Java variable, with
1218 * volatile store semantics. Otherwise identical to {@link #putObject(Object, long, Object)}
1219 */
1220 @HotSpotIntrinsicCandidate
1221 public native void putObjectVolatile(Object o, long offset, Object x);
1222
1223 /** Volatile version of {@link #getInt(Object, long)} */
1224 @HotSpotIntrinsicCandidate
1225 public native int getIntVolatile(Object o, long offset);
1226
1227 /** Volatile version of {@link #putInt(Object, long, int)} */
1228 @HotSpotIntrinsicCandidate
1229 public native void putIntVolatile(Object o, long offset, int x);
1230
1231 /** Volatile version of {@link #getBoolean(Object, long)} */
1232 @HotSpotIntrinsicCandidate
1233 public native boolean getBooleanVolatile(Object o, long offset);
1234
1235 /** Volatile version of {@link #putBoolean(Object, long, boolean)} */
1236 @HotSpotIntrinsicCandidate
1237 public native void putBooleanVolatile(Object o, long offset, boolean x);
1238
1239 /** Volatile version of {@link #getByte(Object, long)} */
1240 @HotSpotIntrinsicCandidate
1241 public native byte getByteVolatile(Object o, long offset);
1242
1243 /** Volatile version of {@link #putByte(Object, long, byte)} */
1244 @HotSpotIntrinsicCandidate
1245 public native void putByteVolatile(Object o, long offset, byte x);
1246
1247 /** Volatile version of {@link #getShort(Object, long)} */
1248 @HotSpotIntrinsicCandidate
1249 public native short getShortVolatile(Object o, long offset);
1250
1251 /** Volatile version of {@link #putShort(Object, long, short)} */
1252 @HotSpotIntrinsicCandidate
1253 public native void putShortVolatile(Object o, long offset, short x);
1254
1255 /** Volatile version of {@link #getChar(Object, long)} */
1256 @HotSpotIntrinsicCandidate
1257 public native char getCharVolatile(Object o, long offset);
1258
1259 /** Volatile version of {@link #putChar(Object, long, char)} */
1260 @HotSpotIntrinsicCandidate
1261 public native void putCharVolatile(Object o, long offset, char x);
1262
1263 /** Volatile version of {@link #getLong(Object, long)} */
1264 @HotSpotIntrinsicCandidate
1265 public native long getLongVolatile(Object o, long offset);
1266
1267 /** Volatile version of {@link #putLong(Object, long, long)} */
1268 @HotSpotIntrinsicCandidate
1269 public native void putLongVolatile(Object o, long offset, long x);
1270
1271 /** Volatile version of {@link #getFloat(Object, long)} */
1272 @HotSpotIntrinsicCandidate
1273 public native float getFloatVolatile(Object o, long offset);
1274
1275 /** Volatile version of {@link #putFloat(Object, long, float)} */
1276 @HotSpotIntrinsicCandidate
1277 public native void putFloatVolatile(Object o, long offset, float x);
1278
1279 /** Volatile version of {@link #getDouble(Object, long)} */
1280 @HotSpotIntrinsicCandidate
1281 public native double getDoubleVolatile(Object o, long offset);
1282
1283 /** Volatile version of {@link #putDouble(Object, long, double)} */
1284 @HotSpotIntrinsicCandidate
1285 public native void putDoubleVolatile(Object o, long offset, double x);
1286
1287 /**
1288 * Version of {@link #putObjectVolatile(Object, long, Object)}
1289 * that does not guarantee immediate visibility of the store to
1290 * other threads. This method is generally only useful if the
1291 * underlying field is a Java volatile (or if an array cell, one
1292 * that is otherwise only accessed using volatile accesses).
1293 *
1294 * Corresponds to C11 atomic_store_explicit(..., memory_order_release).
1295 */
1296 @HotSpotIntrinsicCandidate
1297 public native void putOrderedObject(Object o, long offset, Object x);
1298
1299 /** Ordered/Lazy version of {@link #putIntVolatile(Object, long, int)} */
1300 @HotSpotIntrinsicCandidate
1301 public native void putOrderedInt(Object o, long offset, int x);
1302
1303 /** Ordered/Lazy version of {@link #putLongVolatile(Object, long, long)} */
1304 @HotSpotIntrinsicCandidate
1305 public native void putOrderedLong(Object o, long offset, long x);
1306
1307 /**
1308 * Unblocks the given thread blocked on {@code park}, or, if it is
1309 * not blocked, causes the subsequent call to {@code park} not to
1310 * block. Note: this operation is "unsafe" solely because the
1311 * caller must somehow ensure that the thread has not been
1312 * destroyed. Nothing special is usually required to ensure this
1313 * when called from Java (in which there will ordinarily be a live
1314 * reference to the thread) but this is not nearly-automatically
1315 * so when calling from native code.
1316 *
1317 * @param thread the thread to unpark.
1318 */
1319 @HotSpotIntrinsicCandidate
1320 public native void unpark(Object thread);
1321
1322 /**
1323 * Blocks current thread, returning when a balancing
1324 * {@code unpark} occurs, or a balancing {@code unpark} has
1325 * already occurred, or the thread is interrupted, or, if not
1326 * absolute and time is not zero, the given time nanoseconds have
1327 * elapsed, or if absolute, the given deadline in milliseconds
1328 * since Epoch has passed, or spuriously (i.e., returning for no
1329 * "reason"). Note: This operation is in the Unsafe class only
1330 * because {@code unpark} is, so it would be strange to place it
1331 * elsewhere.
1332 */
1333 @HotSpotIntrinsicCandidate
1334 public native void park(boolean isAbsolute, long time);
1335
1336 /**
1337 * Gets the load average in the system run queue assigned
1338 * to the available processors averaged over various periods of time.
1339 * This method retrieves the given {@code nelem} samples and
1340 * assigns to the elements of the given {@code loadavg} array.
1341 * The system imposes a maximum of 3 samples, representing
1342 * averages over the last 1, 5, and 15 minutes, respectively.
1343 *
1344 * @param loadavg an array of double of size nelems
1345 * @param nelems the number of samples to be retrieved and
1346 * must be 1 to 3.
1347 *
1348 * @return the number of samples actually retrieved; or -1
1349 * if the load average is unobtainable.
1350 */
1351 public int getLoadAverage(double[] loadavg, int nelems) {
1352 if (nelems < 0 || nelems > 3 || nelems > loadavg.length) {
1353 throw new ArrayIndexOutOfBoundsException();
1354 }
1355
1356 return getLoadAverage0(loadavg, nelems);
1357 }
1358
1359 // The following contain CAS-based Java implementations used on
1360 // platforms not supporting native instructions
1361
1362 /**
1363 * Atomically adds the given value to the current value of a field
1364 * or array element within the given object {@code o}
1365 * at the given {@code offset}.
1366 *
1367 * @param o object/array to update the field/element in
1368 * @param offset field/element offset
1369 * @param delta the value to add
1370 * @return the previous value
1371 * @since 1.8
1372 */
1373 @HotSpotIntrinsicCandidate
1374 public final int getAndAddInt(Object o, long offset, int delta) {
1375 int v;
1376 do {
1377 v = getIntVolatile(o, offset);
1378 } while (!compareAndSwapInt(o, offset, v, v + delta));
1379 return v;
1380 }
1381
1382 /**
1383 * Atomically adds the given value to the current value of a field
1384 * or array element within the given object {@code o}
1385 * at the given {@code offset}.
1386 *
1387 * @param o object/array to update the field/element in
1388 * @param offset field/element offset
1389 * @param delta the value to add
1390 * @return the previous value
1391 * @since 1.8
1392 */
1393 @HotSpotIntrinsicCandidate
1394 public final long getAndAddLong(Object o, long offset, long delta) {
1395 long v;
1396 do {
1397 v = getLongVolatile(o, offset);
1398 } while (!compareAndSwapLong(o, offset, v, v + delta));
1399 return v;
1400 }
1401
1402 /**
1403 * Atomically exchanges the given value with the current value of
1404 * a field or array element within the given object {@code o}
1405 * at the given {@code offset}.
1406 *
1407 * @param o object/array to update the field/element in
1408 * @param offset field/element offset
1409 * @param newValue new value
1410 * @return the previous value
1411 * @since 1.8
1412 */
1413 @HotSpotIntrinsicCandidate
1414 public final int getAndSetInt(Object o, long offset, int newValue) {
1415 int v;
1416 do {
1417 v = getIntVolatile(o, offset);
1418 } while (!compareAndSwapInt(o, offset, v, newValue));
1419 return v;
1420 }
1421
1422 /**
1423 * Atomically exchanges the given value with the current value of
1424 * a field or array element within the given object {@code o}
1425 * at the given {@code offset}.
1426 *
1427 * @param o object/array to update the field/element in
1428 * @param offset field/element offset
1429 * @param newValue new value
1430 * @return the previous value
1431 * @since 1.8
1432 */
1433 @HotSpotIntrinsicCandidate
1434 public final long getAndSetLong(Object o, long offset, long newValue) {
1435 long v;
1436 do {
1437 v = getLongVolatile(o, offset);
1438 } while (!compareAndSwapLong(o, offset, v, newValue));
1439 return v;
1440 }
1441
1442 /**
1443 * Atomically exchanges the given reference value with the current
1444 * reference value of a field or array element within the given
1445 * object {@code o} at the given {@code offset}.
1446 *
1447 * @param o object/array to update the field/element in
1448 * @param offset field/element offset
1449 * @param newValue new value
1450 * @return the previous value
1451 * @since 1.8
1452 */
1453 @HotSpotIntrinsicCandidate
1454 public final Object getAndSetObject(Object o, long offset, Object newValue) {
1455 Object v;
1456 do {
1457 v = getObjectVolatile(o, offset);
1458 } while (!compareAndSwapObject(o, offset, v, newValue));
1459 return v;
1460 }
1461
1462
1463 /**
1464 * Ensures that loads before the fence will not be reordered with loads and
1465 * stores after the fence; a "LoadLoad plus LoadStore barrier".
1466 *
1467 * Corresponds to C11 atomic_thread_fence(memory_order_acquire)
1468 * (an "acquire fence").
1469 *
1470 * A pure LoadLoad fence is not provided, since the addition of LoadStore
1471 * is almost always desired, and most current hardware instructions that
1472 * provide a LoadLoad barrier also provide a LoadStore barrier for free.
1473 * @since 1.8
1474 */
1475 @HotSpotIntrinsicCandidate
1476 public native void loadFence();
1477
1478 /**
1479 * Ensures that loads and stores before the fence will not be reordered with
1480 * stores after the fence; a "StoreStore plus LoadStore barrier".
1481 *
1482 * Corresponds to C11 atomic_thread_fence(memory_order_release)
1483 * (a "release fence").
1484 *
1485 * A pure StoreStore fence is not provided, since the addition of LoadStore
1486 * is almost always desired, and most current hardware instructions that
1487 * provide a StoreStore barrier also provide a LoadStore barrier for free.
1488 * @since 1.8
1489 */
1490 @HotSpotIntrinsicCandidate
1491 public native void storeFence();
1492
1493 /**
1494 * Ensures that loads and stores before the fence will not be reordered
1495 * with loads and stores after the fence. Implies the effects of both
1496 * loadFence() and storeFence(), and in addition, the effect of a StoreLoad
1497 * barrier.
1498 *
1499 * Corresponds to C11 atomic_thread_fence(memory_order_seq_cst).
1500 * @since 1.8
1501 */
1502 @HotSpotIntrinsicCandidate
1503 public native void fullFence();
1504
1505 /**
1506 * Throws IllegalAccessError; for use by the VM for access control
1507 * error support.
1508 * @since 1.8
1509 */
1510 private static void throwIllegalAccessError() {
1511 throw new IllegalAccessError();
1512 }
1513
1514 /**
1515 * @return Returns true if the native byte ordering of this
1516 * platform is big-endian, false if it is little-endian.
1517 */
1518 public final boolean isBigEndian() { return BE; }
1519
1520 /**
1521 * @return Returns true if this platform is capable of performing
1522 * accesses at addresses which are not aligned for the type of the
1523 * primitive type being accessed, false otherwise.
1524 */
1525 public final boolean unalignedAccess() { return unalignedAccess; }
1526
1527 /**
1528 * Fetches a value at some byte offset into a given Java object.
1529 * More specifically, fetches a value within the given object
1530 * <code>o</code> at the given offset, or (if <code>o</code> is
1531 * null) from the memory address whose numerical value is the
1532 * given offset. <p>
1533 *
1534 * The specification of this method is the same as {@link
1535 * #getLong(Object, long)} except that the offset does not need to
1536 * have been obtained from {@link #objectFieldOffset} on the
1537 * {@link java.lang.reflect.Field} of some Java field. The value
1538 * in memory is raw data, and need not correspond to any Java
1539 * variable. Unless <code>o</code> is null, the value accessed
1540 * must be entirely within the allocated object. The endianness
1541 * of the value in memory is the endianness of the native platform.
1542 *
1543 * <p> The read will be atomic with respect to the largest power
1544 * of two that divides the GCD of the offset and the storage size.
1545 * For example, getLongUnaligned will make atomic reads of 2-, 4-,
1546 * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
1547 * respectively. There are no other guarantees of atomicity.
1548 * <p>
1549 * 8-byte atomicity is only guaranteed on platforms on which
1550 * support atomic accesses to longs.
1551 *
1552 * @param o Java heap object in which the value resides, if any, else
1553 * null
1554 * @param offset The offset in bytes from the start of the object
1555 * @return the value fetched from the indicated object
1556 * @throws RuntimeException No defined exceptions are thrown, not even
1557 * {@link NullPointerException}
1558 * @since 9
1559 */
1560 @HotSpotIntrinsicCandidate
1561 public final long getLongUnaligned(Object o, long offset) {
1562 if ((offset & 7) == 0) {
1563 return getLong(o, offset);
1564 } else if ((offset & 3) == 0) {
1565 return makeLong(getInt(o, offset),
1566 getInt(o, offset + 4));
1567 } else if ((offset & 1) == 0) {
1568 return makeLong(getShort(o, offset),
1569 getShort(o, offset + 2),
1570 getShort(o, offset + 4),
1571 getShort(o, offset + 6));
1572 } else {
1573 return makeLong(getByte(o, offset),
1574 getByte(o, offset + 1),
1575 getByte(o, offset + 2),
1576 getByte(o, offset + 3),
1577 getByte(o, offset + 4),
1578 getByte(o, offset + 5),
1579 getByte(o, offset + 6),
1580 getByte(o, offset + 7));
1581 }
1582 }
1583 /**
1584 * As {@link #getLongUnaligned(Object, long)} but with an
1585 * additional argument which specifies the endianness of the value
1586 * as stored in memory.
1587 *
1588 * @param o Java heap object in which the variable resides
1589 * @param offset The offset in bytes from the start of the object
1590 * @param bigEndian The endianness of the value
1591 * @return the value fetched from the indicated object
1592 * @since 9
1593 */
1594 public final long getLongUnaligned(Object o, long offset, boolean bigEndian) {
1595 return convEndian(bigEndian, getLongUnaligned(o, offset));
1596 }
1597
1598 /** @see #getLongUnaligned(Object, long) */
1599 @HotSpotIntrinsicCandidate
1600 public final int getIntUnaligned(Object o, long offset) {
1601 if ((offset & 3) == 0) {
1602 return getInt(o, offset);
1603 } else if ((offset & 1) == 0) {
1604 return makeInt(getShort(o, offset),
1605 getShort(o, offset + 2));
1606 } else {
1607 return makeInt(getByte(o, offset),
1608 getByte(o, offset + 1),
1609 getByte(o, offset + 2),
1610 getByte(o, offset + 3));
1611 }
1612 }
1613 /** @see #getLongUnaligned(Object, long, boolean) */
1614 public final int getIntUnaligned(Object o, long offset, boolean bigEndian) {
1615 return convEndian(bigEndian, getIntUnaligned(o, offset));
1616 }
1617
1618 /** @see #getLongUnaligned(Object, long) */
1619 @HotSpotIntrinsicCandidate
1620 public final short getShortUnaligned(Object o, long offset) {
1621 if ((offset & 1) == 0) {
1622 return getShort(o, offset);
1623 } else {
1624 return makeShort(getByte(o, offset),
1625 getByte(o, offset + 1));
1626 }
1627 }
1628 /** @see #getLongUnaligned(Object, long, boolean) */
1629 public final short getShortUnaligned(Object o, long offset, boolean bigEndian) {
1630 return convEndian(bigEndian, getShortUnaligned(o, offset));
1631 }
1632
1633 /** @see #getLongUnaligned(Object, long) */
1634 @HotSpotIntrinsicCandidate
1635 public final char getCharUnaligned(Object o, long offset) {
1636 return (char)getShortUnaligned(o, offset);
1637 }
1638
1639 /** @see #getLongUnaligned(Object, long, boolean) */
1640 public final char getCharUnaligned(Object o, long offset, boolean bigEndian) {
1641 return convEndian(bigEndian, getCharUnaligned(o, offset));
1642 }
1643
1644 /**
1645 * Stores a value at some byte offset into a given Java object.
1646 * <p>
1647 * The specification of this method is the same as {@link
1648 * #getLong(Object, long)} except that the offset does not need to
1649 * have been obtained from {@link #objectFieldOffset} on the
1650 * {@link java.lang.reflect.Field} of some Java field. The value
1651 * in memory is raw data, and need not correspond to any Java
1652 * variable. The endianness of the value in memory is the
1653 * endianness of the native platform.
1654 * <p>
1655 * The write will be atomic with respect to the largest power of
1656 * two that divides the GCD of the offset and the storage size.
1657 * For example, putLongUnaligned will make atomic writes of 2-, 4-,
1658 * or 8-byte storage units if the offset is zero mod 2, 4, or 8,
1659 * respectively. There are no other guarantees of atomicity.
1660 * <p>
1661 * 8-byte atomicity is only guaranteed on platforms on which
1662 * support atomic accesses to longs.
1663 *
1664 * @param o Java heap object in which the value resides, if any, else
1665 * null
1666 * @param offset The offset in bytes from the start of the object
1667 * @param x the value to store
1668 * @throws RuntimeException No defined exceptions are thrown, not even
1669 * {@link NullPointerException}
1670 * @since 9
1671 */
1672 @HotSpotIntrinsicCandidate
1673 public final void putLongUnaligned(Object o, long offset, long x) {
1674 if ((offset & 7) == 0) {
1675 putLong(o, offset, x);
1676 } else if ((offset & 3) == 0) {
1677 putLongParts(o, offset,
1678 (int)(x >> 0),
1679 (int)(x >>> 32));
1680 } else if ((offset & 1) == 0) {
1681 putLongParts(o, offset,
1682 (short)(x >>> 0),
1683 (short)(x >>> 16),
1684 (short)(x >>> 32),
1685 (short)(x >>> 48));
1686 } else {
1687 putLongParts(o, offset,
1688 (byte)(x >>> 0),
1689 (byte)(x >>> 8),
1690 (byte)(x >>> 16),
1691 (byte)(x >>> 24),
1692 (byte)(x >>> 32),
1693 (byte)(x >>> 40),
1694 (byte)(x >>> 48),
1695 (byte)(x >>> 56));
1696 }
1697 }
1698
1699 /**
1700 * As {@link #putLongUnaligned(Object, long, long)} but with an additional
1701 * argument which specifies the endianness of the value as stored in memory.
1702 * @param o Java heap object in which the value resides
1703 * @param offset The offset in bytes from the start of the object
1704 * @param x the value to store
1705 * @param bigEndian The endianness of the value
1706 * @throws RuntimeException No defined exceptions are thrown, not even
1707 * {@link NullPointerException}
1708 * @since 9
1709 */
1710 public final void putLongUnaligned(Object o, long offset, long x, boolean bigEndian) {
1711 putLongUnaligned(o, offset, convEndian(bigEndian, x));
1712 }
1713
1714 /** @see #putLongUnaligned(Object, long, long) */
1715 @HotSpotIntrinsicCandidate
1716 public final void putIntUnaligned(Object o, long offset, int x) {
1717 if ((offset & 3) == 0) {
1718 putInt(o, offset, x);
1719 } else if ((offset & 1) == 0) {
1720 putIntParts(o, offset,
1721 (short)(x >> 0),
1722 (short)(x >>> 16));
1723 } else {
1724 putIntParts(o, offset,
1725 (byte)(x >>> 0),
1726 (byte)(x >>> 8),
1727 (byte)(x >>> 16),
1728 (byte)(x >>> 24));
1729 }
1730 }
1731 /** @see #putLongUnaligned(Object, long, long, boolean) */
1732 public final void putIntUnaligned(Object o, long offset, int x, boolean bigEndian) {
1733 putIntUnaligned(o, offset, convEndian(bigEndian, x));
1734 }
1735
1736 /** @see #putLongUnaligned(Object, long, long) */
1737 @HotSpotIntrinsicCandidate
1738 public final void putShortUnaligned(Object o, long offset, short x) {
1739 if ((offset & 1) == 0) {
1740 putShort(o, offset, x);
1741 } else {
1742 putShortParts(o, offset,
1743 (byte)(x >>> 0),
1744 (byte)(x >>> 8));
1745 }
1746 }
1747 /** @see #putLongUnaligned(Object, long, long, boolean) */
1748 public final void putShortUnaligned(Object o, long offset, short x, boolean bigEndian) {
1749 putShortUnaligned(o, offset, convEndian(bigEndian, x));
1750 }
1751
1752 /** @see #putLongUnaligned(Object, long, long) */
1753 @HotSpotIntrinsicCandidate
1754 public final void putCharUnaligned(Object o, long offset, char x) {
1755 putShortUnaligned(o, offset, (short)x);
1756 }
1757 /** @see #putLongUnaligned(Object, long, long, boolean) */
1758 public final void putCharUnaligned(Object o, long offset, char x, boolean bigEndian) {
1759 putCharUnaligned(o, offset, convEndian(bigEndian, x));
1760 }
1761
1762 // JVM interface methods
1763 // BE is true iff the native endianness of this platform is big.
1764 private static final boolean BE = theUnsafe.isBigEndian0();
1765
1766 // unalignedAccess is true iff this platform can perform unaligned accesses.
1767 private static final boolean unalignedAccess = theUnsafe.unalignedAccess0();
1768
1769 private static int pickPos(int top, int pos) { return BE ? top - pos : pos; }
1770
1771 // These methods construct integers from bytes. The byte ordering
1772 // is the native endianness of this platform.
1773 private static long makeLong(byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
1774 return ((toUnsignedLong(i0) << pickPos(56, 0))
1775 | (toUnsignedLong(i1) << pickPos(56, 8))
1776 | (toUnsignedLong(i2) << pickPos(56, 16))
1777 | (toUnsignedLong(i3) << pickPos(56, 24))
1778 | (toUnsignedLong(i4) << pickPos(56, 32))
1779 | (toUnsignedLong(i5) << pickPos(56, 40))
1780 | (toUnsignedLong(i6) << pickPos(56, 48))
1781 | (toUnsignedLong(i7) << pickPos(56, 56)));
1782 }
1783 private static long makeLong(short i0, short i1, short i2, short i3) {
1784 return ((toUnsignedLong(i0) << pickPos(48, 0))
1785 | (toUnsignedLong(i1) << pickPos(48, 16))
1786 | (toUnsignedLong(i2) << pickPos(48, 32))
1787 | (toUnsignedLong(i3) << pickPos(48, 48)));
1788 }
1789 private static long makeLong(int i0, int i1) {
1790 return (toUnsignedLong(i0) << pickPos(32, 0))
1791 | (toUnsignedLong(i1) << pickPos(32, 32));
1792 }
1793 private static int makeInt(short i0, short i1) {
1794 return (toUnsignedInt(i0) << pickPos(16, 0))
1795 | (toUnsignedInt(i1) << pickPos(16, 16));
1796 }
1797 private static int makeInt(byte i0, byte i1, byte i2, byte i3) {
1798 return ((toUnsignedInt(i0) << pickPos(24, 0))
1799 | (toUnsignedInt(i1) << pickPos(24, 8))
1800 | (toUnsignedInt(i2) << pickPos(24, 16))
1801 | (toUnsignedInt(i3) << pickPos(24, 24)));
1802 }
1803 private static short makeShort(byte i0, byte i1) {
1804 return (short)((toUnsignedInt(i0) << pickPos(8, 0))
1805 | (toUnsignedInt(i1) << pickPos(8, 8)));
1806 }
1807
1808 private static byte pick(byte le, byte be) { return BE ? be : le; }
1809 private static short pick(short le, short be) { return BE ? be : le; }
1810 private static int pick(int le, int be) { return BE ? be : le; }
1811
1812 // These methods write integers to memory from smaller parts
1813 // provided by their caller. The ordering in which these parts
1814 // are written is the native endianness of this platform.
1815 private void putLongParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3, byte i4, byte i5, byte i6, byte i7) {
1816 putByte(o, offset + 0, pick(i0, i7));
1817 putByte(o, offset + 1, pick(i1, i6));
1818 putByte(o, offset + 2, pick(i2, i5));
1819 putByte(o, offset + 3, pick(i3, i4));
1820 putByte(o, offset + 4, pick(i4, i3));
1821 putByte(o, offset + 5, pick(i5, i2));
1822 putByte(o, offset + 6, pick(i6, i1));
1823 putByte(o, offset + 7, pick(i7, i0));
1824 }
1825 private void putLongParts(Object o, long offset, short i0, short i1, short i2, short i3) {
1826 putShort(o, offset + 0, pick(i0, i3));
1827 putShort(o, offset + 2, pick(i1, i2));
1828 putShort(o, offset + 4, pick(i2, i1));
1829 putShort(o, offset + 6, pick(i3, i0));
1830 }
1831 private void putLongParts(Object o, long offset, int i0, int i1) {
1832 putInt(o, offset + 0, pick(i0, i1));
1833 putInt(o, offset + 4, pick(i1, i0));
1834 }
1835 private void putIntParts(Object o, long offset, short i0, short i1) {
1836 putShort(o, offset + 0, pick(i0, i1));
1837 putShort(o, offset + 2, pick(i1, i0));
1838 }
1839 private void putIntParts(Object o, long offset, byte i0, byte i1, byte i2, byte i3) {
1840 putByte(o, offset + 0, pick(i0, i3));
1841 putByte(o, offset + 1, pick(i1, i2));
1842 putByte(o, offset + 2, pick(i2, i1));
1843 putByte(o, offset + 3, pick(i3, i0));
1844 }
1845 private void putShortParts(Object o, long offset, byte i0, byte i1) {
1846 putByte(o, offset + 0, pick(i0, i1));
1847 putByte(o, offset + 1, pick(i1, i0));
1848 }
1849
1850 // Zero-extend an integer
1851 private static int toUnsignedInt(byte n) { return n & 0xff; }
1852 private static int toUnsignedInt(short n) { return n & 0xffff; }
1853 private static long toUnsignedLong(byte n) { return n & 0xffl; }
1854 private static long toUnsignedLong(short n) { return n & 0xffffl; }
1855 private static long toUnsignedLong(int n) { return n & 0xffffffffl; }
1856
1857 // Maybe byte-reverse an integer
1858 private static char convEndian(boolean big, char n) { return big == BE ? n : Character.reverseBytes(n); }
1859 private static short convEndian(boolean big, short n) { return big == BE ? n : Short.reverseBytes(n) ; }
1860 private static int convEndian(boolean big, int n) { return big == BE ? n : Integer.reverseBytes(n) ; }
1861 private static long convEndian(boolean big, long n) { return big == BE ? n : Long.reverseBytes(n) ; }
1862
1863
1864
1865 private native long allocateMemory0(long bytes);
1866 private native long reallocateMemory0(long address, long bytes);
1867 private native void freeMemory0(long address);
1868 private native void setMemory0(Object o, long offset, long bytes, byte value);
1869 @HotSpotIntrinsicCandidate
1870 private native void copyMemory0(Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes);
1871 private native void copySwapMemory0(Object srcBase, long srcOffset, Object destBase, long destOffset, long bytes, long elemSize);
1872 private native long objectFieldOffset0(Field f);
1873 private native long staticFieldOffset0(Field f);
1874 private native Object staticFieldBase0(Field f);
1875 private native boolean shouldBeInitialized0(Class<?> c);
1876 private native void ensureClassInitialized0(Class<?> c);
1877 private native int arrayBaseOffset0(Class<?> arrayClass);
1878 private native int arrayIndexScale0(Class<?> arrayClass);
1879 private native int addressSize0();
1880 private native Class<?> defineAnonymousClass0(Class<?> hostClass, byte[] data, Object[] cpPatches);
1881 private native int getLoadAverage0(double[] loadavg, int nelems);
1882 private native boolean unalignedAccess0();
1883 private native boolean isBigEndian0();
1884 }