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8221477: Inject os/cpu-specific constants into Unsafe from JVM
Initialize Unsafe os/cpu-specific constants using injection instead of native callouts Reviewed-by: stuefe, coleenp, dholmes, plevart
This commit is contained in:
Andrew Dinn
parent
7a093bcf50
commit
71164a973b
9 changed files with 190 additions and 52 deletions
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@ -33,6 +33,7 @@ import sun.nio.ch.DirectBuffer;
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import java.lang.reflect.Field;
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import java.security.ProtectionDomain;
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import static jdk.internal.misc.UnsafeConstants.*;
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/**
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* A collection of methods for performing low-level, unsafe operations.
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@ -1166,14 +1167,13 @@ public final class Unsafe {
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}
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/** The value of {@code addressSize()} */
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public static final int ADDRESS_SIZE = theUnsafe.addressSize0();
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public static final int ADDRESS_SIZE = ADDRESS_SIZE0;
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/**
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* Reports the size in bytes of a native memory page (whatever that is).
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* This value will always be a power of two.
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*/
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public native int pageSize();
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public int pageSize() { return PAGE_SIZE; }
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/// random trusted operations from JNI:
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@ -1417,7 +1417,7 @@ public final class Unsafe {
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byte x) {
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long wordOffset = offset & ~3;
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int shift = (int) (offset & 3) << 3;
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if (BE) {
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if (BIG_ENDIAN) {
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shift = 24 - shift;
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}
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int mask = 0xFF << shift;
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@ -1491,7 +1491,7 @@ public final class Unsafe {
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}
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long wordOffset = offset & ~3;
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int shift = (int) (offset & 3) << 3;
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if (BE) {
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if (BIG_ENDIAN) {
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shift = 16 - shift;
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}
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int mask = 0xFFFF << shift;
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@ -3354,14 +3354,14 @@ public final class Unsafe {
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* @return Returns true if the native byte ordering of this
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* platform is big-endian, false if it is little-endian.
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*/
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public final boolean isBigEndian() { return BE; }
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public final boolean isBigEndian() { return BIG_ENDIAN; }
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/**
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* @return Returns true if this platform is capable of performing
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* accesses at addresses which are not aligned for the type of the
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* primitive type being accessed, false otherwise.
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*/
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public final boolean unalignedAccess() { return unalignedAccess; }
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public final boolean unalignedAccess() { return UNALIGNED_ACCESS; }
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/**
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* Fetches a value at some byte offset into a given Java object.
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@ -3603,14 +3603,7 @@ public final class Unsafe {
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putCharUnaligned(o, offset, convEndian(bigEndian, x));
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}
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// JVM interface methods
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// BE is true iff the native endianness of this platform is big.
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private static final boolean BE = theUnsafe.isBigEndian0();
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// unalignedAccess is true iff this platform can perform unaligned accesses.
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private static final boolean unalignedAccess = theUnsafe.unalignedAccess0();
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private static int pickPos(int top, int pos) { return BE ? top - pos : pos; }
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private static int pickPos(int top, int pos) { return BIG_ENDIAN ? top - pos : pos; }
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// These methods construct integers from bytes. The byte ordering
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// is the native endianness of this platform.
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@ -3649,9 +3642,9 @@ public final class Unsafe {
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| (toUnsignedInt(i1) << pickPos(8, 8)));
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}
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private static byte pick(byte le, byte be) { return BE ? be : le; }
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private static short pick(short le, short be) { return BE ? be : le; }
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private static int pick(int le, int be) { return BE ? be : le; }
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private static byte pick(byte le, byte be) { return BIG_ENDIAN ? be : le; }
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private static short pick(short le, short be) { return BIG_ENDIAN ? be : le; }
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private static int pick(int le, int be) { return BIG_ENDIAN ? be : le; }
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// These methods write integers to memory from smaller parts
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// provided by their caller. The ordering in which these parts
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@ -3699,10 +3692,10 @@ public final class Unsafe {
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private static long toUnsignedLong(int n) { return n & 0xffffffffl; }
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// Maybe byte-reverse an integer
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private static char convEndian(boolean big, char n) { return big == BE ? n : Character.reverseBytes(n); }
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private static short convEndian(boolean big, short n) { return big == BE ? n : Short.reverseBytes(n) ; }
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private static int convEndian(boolean big, int n) { return big == BE ? n : Integer.reverseBytes(n) ; }
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private static long convEndian(boolean big, long n) { return big == BE ? n : Long.reverseBytes(n) ; }
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private static char convEndian(boolean big, char n) { return big == BIG_ENDIAN ? n : Character.reverseBytes(n); }
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private static short convEndian(boolean big, short n) { return big == BIG_ENDIAN ? n : Short.reverseBytes(n) ; }
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private static int convEndian(boolean big, int n) { return big == BIG_ENDIAN ? n : Integer.reverseBytes(n) ; }
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private static long convEndian(boolean big, long n) { return big == BIG_ENDIAN ? n : Long.reverseBytes(n) ; }
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@ -3721,11 +3714,8 @@ public final class Unsafe {
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private native void ensureClassInitialized0(Class<?> c);
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private native int arrayBaseOffset0(Class<?> arrayClass);
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private native int arrayIndexScale0(Class<?> arrayClass);
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private native int addressSize0();
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private native Class<?> defineAnonymousClass0(Class<?> hostClass, byte[] data, Object[] cpPatches);
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private native int getLoadAverage0(double[] loadavg, int nelems);
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private native boolean unalignedAccess0();
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private native boolean isBigEndian0();
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/**
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@ -0,0 +1,103 @@
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/*
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* Copyright (c) 2019, Red Hat Inc. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package jdk.internal.misc;
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/**
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* A class used to expose details of the underlying hardware that
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* configure the operation of class Unsafe. This class is
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* package-private as the only intended client is class Unsafe.
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* All fields in this class must be static final constants.
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*
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* @since 13
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*
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* @implNote
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*
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* The JVM injects hardware-specific values into all the static fields
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* of this class during JVM initialization. The static initialization
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* block is executed when the class is initialized then JVM injection
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* updates the fields with the correct constants. The static block
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* is required to prevent the fields from being considered constant
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* variables, so the field values will be not be compiled directly into
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* any class that uses them.
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*/
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final class UnsafeConstants {
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/**
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* This constructor is private because the class is not meant to
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* be instantiated.
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*/
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private UnsafeConstants() {}
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/**
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* The size in bytes of a native pointer, as stored via {@link
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* #putAddress}. This value will be either 4 or 8. Note that the
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* sizes of other primitive types (as stored in native memory
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* blocks) is determined fully by their information content.
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*
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* @implNote
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* The actual value for this field is injected by the JVM.
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*/
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static final int ADDRESS_SIZE0;
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/**
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* The size in bytes of a native memory page (whatever that is).
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* This value will always be a power of two.
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*
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* @implNote
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* The actual value for this field is injected by the JVM.
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*/
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static final int PAGE_SIZE;
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/**
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* Flag whose value is true if and only if the native endianness
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* of this platform is big.
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*
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* @implNote
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* The actual value for this field is injected by the JVM.
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*/
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static final boolean BIG_ENDIAN;
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/**
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* Flag whose value is true if and only if the platform can
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* perform unaligned accesses
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*
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* @implNote
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* The actual value for this field is injected by the JVM.
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*/
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static final boolean UNALIGNED_ACCESS;
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static {
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ADDRESS_SIZE0 = 0;
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PAGE_SIZE = 0;
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BIG_ENDIAN = false;
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UNALIGNED_ACCESS = false;
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}
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}
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