1/*
2 * Copyright (c) 2011, 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.
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 */
23package jdk.vm.ci.hotspot;
24
25import static jdk.vm.ci.hotspot.HotSpotJVMCIRuntimeProvider.getArrayBaseOffset;
26import static jdk.vm.ci.hotspot.HotSpotJVMCIRuntimeProvider.getArrayIndexScale;
27import static jdk.vm.ci.hotspot.UnsafeAccess.UNSAFE;
28
29import java.lang.reflect.Array;
30
31import jdk.vm.ci.common.JVMCIError;
32import jdk.vm.ci.meta.Constant;
33import jdk.vm.ci.meta.JavaConstant;
34import jdk.vm.ci.meta.JavaKind;
35import jdk.vm.ci.meta.MemoryAccessProvider;
36import jdk.vm.ci.meta.MetaAccessProvider;
37import jdk.vm.ci.meta.PrimitiveConstant;
38import jdk.vm.ci.meta.ResolvedJavaField;
39import jdk.vm.ci.meta.ResolvedJavaType;
40
41/**
42 * HotSpot implementation of {@link MemoryAccessProvider}.
43 */
44class HotSpotMemoryAccessProviderImpl implements HotSpotMemoryAccessProvider {
45
46    protected final HotSpotJVMCIRuntimeProvider runtime;
47
48    HotSpotMemoryAccessProviderImpl(HotSpotJVMCIRuntimeProvider runtime) {
49        this.runtime = runtime;
50    }
51
52    /**
53     * Gets the object boxed by {@code base} that is about to have a value of kind {@code kind} read
54     * from it at the offset {@code displacement}.
55     *
56     * @param base constant value containing the base address for a pending read
57     * @return {@code null} if {@code base} does not box an object otherwise the object boxed in
58     *         {@code base}
59     */
60    private Object asObject(Constant base, JavaKind kind, long displacement) {
61        if (base instanceof HotSpotObjectConstantImpl) {
62            HotSpotObjectConstantImpl constant = (HotSpotObjectConstantImpl) base;
63            HotSpotResolvedObjectType type = constant.getType();
64            Object object = constant.object();
65            checkRead(kind, displacement, type, object);
66            return object;
67        }
68        return null;
69    }
70
71    /**
72     * Offset of injected {@code java.lang.Class::oop_size} field. No need to make {@code volatile}
73     * as initialization is idempotent.
74     */
75    private long oopSizeOffset;
76
77    private static int computeOopSizeOffset(HotSpotJVMCIRuntimeProvider runtime) {
78        MetaAccessProvider metaAccess = runtime.getHostJVMCIBackend().getMetaAccess();
79        ResolvedJavaType staticType = metaAccess.lookupJavaType(Class.class);
80        for (ResolvedJavaField f : staticType.getInstanceFields(false)) {
81            if (f.getName().equals("oop_size")) {
82                int offset = ((HotSpotResolvedJavaField) f).offset();
83                assert offset != 0 : "not expecting offset of java.lang.Class::oop_size to be 0";
84                return offset;
85            }
86        }
87        throw new JVMCIError("Could not find injected java.lang.Class::oop_size field");
88    }
89
90    private boolean checkRead(JavaKind kind, long displacement, HotSpotResolvedObjectType type, Object object) {
91        if (type.isArray()) {
92            ResolvedJavaType componentType = type.getComponentType();
93            JavaKind componentKind = componentType.getJavaKind();
94            final int headerSize = getArrayBaseOffset(componentKind);
95            int sizeOfElement = getArrayIndexScale(componentKind);
96            int length = Array.getLength(object);
97            long arrayEnd = headerSize + (sizeOfElement * length);
98            boolean aligned = ((displacement - headerSize) % sizeOfElement) == 0;
99            if (displacement < 0 || displacement > (arrayEnd - sizeOfElement) || (kind == JavaKind.Object && !aligned)) {
100                int index = (int) ((displacement - headerSize) / sizeOfElement);
101                throw new IllegalArgumentException("Unsafe array access: reading element of kind " + kind +
102                                " at offset " + displacement + " (index ~ " + index + ") in " +
103                                type.toJavaName() + " object of length " + length);
104            }
105        } else if (kind != JavaKind.Object) {
106            long size;
107            if (object instanceof Class) {
108                if (oopSizeOffset == 0) {
109                    oopSizeOffset = computeOopSizeOffset(runtime);
110                }
111                int wordSize = runtime.getHostJVMCIBackend().getCodeCache().getTarget().wordSize;
112                size = UNSAFE.getInt(object, oopSizeOffset) * wordSize;
113            } else {
114                size = Math.abs(type.instanceSize());
115            }
116            int bytesToRead = kind.getByteCount();
117            if (displacement + bytesToRead > size || displacement < 0) {
118                throw new IllegalArgumentException("Unsafe access: reading " + bytesToRead + " bytes at offset " + displacement + " in " +
119                                type.toJavaName() + " object of size " + size);
120            }
121        } else {
122            ResolvedJavaField field = type.findInstanceFieldWithOffset(displacement, JavaKind.Object);
123            if (field == null && object instanceof Class) {
124                // Read of a static field
125                MetaAccessProvider metaAccess = runtime.getHostJVMCIBackend().getMetaAccess();
126                HotSpotResolvedObjectTypeImpl staticFieldsHolder = (HotSpotResolvedObjectTypeImpl) metaAccess.lookupJavaType((Class<?>) object);
127                field = staticFieldsHolder.findStaticFieldWithOffset(displacement, JavaKind.Object);
128            }
129            if (field == null) {
130                throw new IllegalArgumentException("Unsafe object access: field not found for read of kind Object" +
131                                " at offset " + displacement + " in " + type.toJavaName() + " object");
132            }
133            if (field.getJavaKind() != JavaKind.Object) {
134                throw new IllegalArgumentException("Unsafe object access: field " + field.format("%H.%n:%T") + " not of expected kind Object" +
135                                " at offset " + displacement + " in " + type.toJavaName() + " object");
136            }
137        }
138        return true;
139    }
140
141    private boolean isValidObjectFieldDisplacement(Constant base, long displacement) {
142        if (base instanceof HotSpotMetaspaceConstant) {
143            MetaspaceWrapperObject metaspaceObject = HotSpotMetaspaceConstantImpl.getMetaspaceObject(base);
144            if (metaspaceObject instanceof HotSpotResolvedObjectTypeImpl) {
145                if (displacement == runtime.getConfig().classMirrorOffset) {
146                    // Klass::_java_mirror is valid for all Klass* values
147                    return true;
148                }
149            } else {
150                throw new IllegalArgumentException(String.valueOf(metaspaceObject));
151            }
152        }
153        return false;
154    }
155
156    private static long asRawPointer(Constant base) {
157        if (base instanceof HotSpotMetaspaceConstantImpl) {
158            MetaspaceWrapperObject meta = HotSpotMetaspaceConstantImpl.getMetaspaceObject(base);
159            return meta.getMetaspacePointer();
160        } else if (base instanceof PrimitiveConstant) {
161            PrimitiveConstant prim = (PrimitiveConstant) base;
162            if (prim.getJavaKind().isNumericInteger()) {
163                return prim.asLong();
164            }
165        }
166        throw new IllegalArgumentException(String.valueOf(base));
167    }
168
169    private long readRawValue(Constant baseConstant, long displacement, JavaKind kind, int bits) {
170        Object base = asObject(baseConstant, kind, displacement);
171        if (base != null) {
172            switch (bits) {
173                case Byte.SIZE:
174                    return UNSAFE.getByte(base, displacement);
175                case Short.SIZE:
176                    return UNSAFE.getShort(base, displacement);
177                case Integer.SIZE:
178                    return UNSAFE.getInt(base, displacement);
179                case Long.SIZE:
180                    return UNSAFE.getLong(base, displacement);
181                default:
182                    throw new IllegalArgumentException(String.valueOf(bits));
183            }
184        } else {
185            long pointer = asRawPointer(baseConstant);
186            switch (bits) {
187                case Byte.SIZE:
188                    return UNSAFE.getByte(pointer + displacement);
189                case Short.SIZE:
190                    return UNSAFE.getShort(pointer + displacement);
191                case Integer.SIZE:
192                    return UNSAFE.getInt(pointer + displacement);
193                case Long.SIZE:
194                    return UNSAFE.getLong(pointer + displacement);
195                default:
196                    throw new IllegalArgumentException(String.valueOf(bits));
197            }
198        }
199    }
200
201    private boolean verifyReadRawObject(Object expected, Constant base, long displacement) {
202        if (base instanceof HotSpotMetaspaceConstant) {
203            MetaspaceWrapperObject metaspaceObject = HotSpotMetaspaceConstantImpl.getMetaspaceObject(base);
204            if (metaspaceObject instanceof HotSpotResolvedObjectTypeImpl) {
205                if (displacement == runtime.getConfig().classMirrorOffset) {
206                    assert expected == ((HotSpotResolvedObjectTypeImpl) metaspaceObject).mirror();
207                }
208            }
209        }
210        return true;
211    }
212
213    private Object readRawObject(Constant baseConstant, long initialDisplacement, boolean compressed) {
214        long displacement = initialDisplacement;
215        Object ret;
216        Object base = asObject(baseConstant, JavaKind.Object, displacement);
217        if (base == null) {
218            assert !compressed;
219            displacement += asRawPointer(baseConstant);
220            ret = UNSAFE.getUncompressedObject(displacement);
221            assert verifyReadRawObject(ret, baseConstant, initialDisplacement);
222        } else {
223            assert runtime.getConfig().useCompressedOops == compressed;
224            ret = UNSAFE.getObject(base, displacement);
225        }
226        return ret;
227    }
228
229    JavaConstant readFieldValue(HotSpotResolvedJavaField field, Object obj) {
230        assert obj != null;
231        assert !field.isStatic() || obj instanceof Class;
232        long displacement = field.offset();
233        assert checkRead(field.getJavaKind(), displacement, (HotSpotResolvedObjectType) runtime.getHostJVMCIBackend().getMetaAccess().lookupJavaType(obj.getClass()), obj);
234        if (field.getJavaKind() == JavaKind.Object) {
235            Object o = UNSAFE.getObject(obj, displacement);
236            return HotSpotObjectConstantImpl.forObject(o);
237        } else {
238            JavaKind kind = field.getJavaKind();
239            switch (kind) {
240                case Boolean:
241                    return JavaConstant.forBoolean(UNSAFE.getBoolean(obj, displacement));
242                case Byte:
243                    return JavaConstant.forByte(UNSAFE.getByte(obj, displacement));
244                case Char:
245                    return JavaConstant.forChar(UNSAFE.getChar(obj, displacement));
246                case Short:
247                    return JavaConstant.forShort(UNSAFE.getShort(obj, displacement));
248                case Int:
249                    return JavaConstant.forInt(UNSAFE.getInt(obj, displacement));
250                case Long:
251                    return JavaConstant.forLong(UNSAFE.getLong(obj, displacement));
252                case Float:
253                    return JavaConstant.forFloat(UNSAFE.getFloat(obj, displacement));
254                case Double:
255                    return JavaConstant.forDouble(UNSAFE.getDouble(obj, displacement));
256                default:
257                    throw new IllegalArgumentException("Unsupported kind: " + kind);
258            }
259        }
260    }
261
262    @Override
263    public JavaConstant readPrimitiveConstant(JavaKind kind, Constant baseConstant, long initialDisplacement, int bits) {
264        try {
265            long rawValue = readRawValue(baseConstant, initialDisplacement, kind, bits);
266            switch (kind) {
267                case Boolean:
268                    return JavaConstant.forBoolean(rawValue != 0);
269                case Byte:
270                    return JavaConstant.forByte((byte) rawValue);
271                case Char:
272                    return JavaConstant.forChar((char) rawValue);
273                case Short:
274                    return JavaConstant.forShort((short) rawValue);
275                case Int:
276                    return JavaConstant.forInt((int) rawValue);
277                case Long:
278                    return JavaConstant.forLong(rawValue);
279                case Float:
280                    return JavaConstant.forFloat(Float.intBitsToFloat((int) rawValue));
281                case Double:
282                    return JavaConstant.forDouble(Double.longBitsToDouble(rawValue));
283                default:
284                    throw new IllegalArgumentException("Unsupported kind: " + kind);
285            }
286        } catch (NullPointerException e) {
287            return null;
288        }
289    }
290
291    @Override
292    public JavaConstant readObjectConstant(Constant base, long displacement) {
293        if (base instanceof HotSpotObjectConstantImpl) {
294            Object o = readRawObject(base, displacement, runtime.getConfig().useCompressedOops);
295            return HotSpotObjectConstantImpl.forObject(o);
296        }
297        if (!isValidObjectFieldDisplacement(base, displacement)) {
298            return null;
299        }
300        return HotSpotObjectConstantImpl.forObject(readRawObject(base, displacement, false));
301    }
302
303    @Override
304    public JavaConstant readNarrowOopConstant(Constant base, long displacement) {
305        return HotSpotObjectConstantImpl.forObject(readRawObject(base, displacement, true), true);
306    }
307
308    private HotSpotResolvedObjectTypeImpl readKlass(Constant base, long displacement, boolean compressed) {
309        assert (base instanceof HotSpotMetaspaceConstantImpl) || (base instanceof HotSpotObjectConstantImpl) : base.getClass();
310        Object baseObject = (base instanceof HotSpotMetaspaceConstantImpl) ? ((HotSpotMetaspaceConstantImpl) base).asResolvedJavaType() : ((HotSpotObjectConstantImpl) base).object();
311        return runtime.getCompilerToVM().getResolvedJavaType(baseObject, displacement, compressed);
312    }
313
314    @Override
315    public Constant readKlassPointerConstant(Constant base, long displacement) {
316        HotSpotResolvedObjectTypeImpl klass = readKlass(base, displacement, false);
317        if (klass == null) {
318            return JavaConstant.NULL_POINTER;
319        }
320        return HotSpotMetaspaceConstantImpl.forMetaspaceObject(klass, false);
321    }
322
323    @Override
324    public Constant readNarrowKlassPointerConstant(Constant base, long displacement) {
325        HotSpotResolvedObjectTypeImpl klass = readKlass(base, displacement, true);
326        if (klass == null) {
327            return HotSpotCompressedNullConstant.COMPRESSED_NULL;
328        }
329        return HotSpotMetaspaceConstantImpl.forMetaspaceObject(klass, true);
330    }
331
332    @Override
333    public Constant readMethodPointerConstant(Constant base, long displacement) {
334        assert (base instanceof HotSpotObjectConstantImpl);
335        Object baseObject = ((HotSpotObjectConstantImpl) base).object();
336        HotSpotResolvedJavaMethodImpl method = runtime.getCompilerToVM().getResolvedJavaMethod(baseObject, displacement);
337        return HotSpotMetaspaceConstantImpl.forMetaspaceObject(method, false);
338    }
339}
340