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/*
* Copyright The OpenTelemetry Authors
* SPDX-License-Identifier: Apache-2.0
*/
package io.opentelemetry.javaagent.tooling;
import static org.objectweb.asm.Opcodes.ACC_FINAL;
import static org.objectweb.asm.Opcodes.ACC_PRIVATE;
import static org.objectweb.asm.Opcodes.ACC_PUBLIC;
import static org.objectweb.asm.Opcodes.ACC_STATIC;
import static org.objectweb.asm.Opcodes.ACC_SUPER;
import static org.objectweb.asm.Opcodes.ALOAD;
import static org.objectweb.asm.Opcodes.DUP;
import static org.objectweb.asm.Opcodes.GETSTATIC;
import static org.objectweb.asm.Opcodes.ILOAD;
import static org.objectweb.asm.Opcodes.INVOKESPECIAL;
import static org.objectweb.asm.Opcodes.INVOKESTATIC;
import static org.objectweb.asm.Opcodes.INVOKEVIRTUAL;
import static org.objectweb.asm.Opcodes.IRETURN;
import static org.objectweb.asm.Opcodes.NEW;
import static org.objectweb.asm.Opcodes.PUTSTATIC;
import static org.objectweb.asm.Opcodes.RETURN;
import static org.objectweb.asm.Opcodes.V1_5;
import io.opentelemetry.javaagent.bootstrap.AgentClassLoader;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.FieldVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Type;
/**
* Helper class for generating our own copy of sun.misc.Unsafe that delegates to
* jdk.internal.misc.Unsafe. Used when jdk provided sun.misc.Unsafe is not available which can
* happen when running modular application without jdk.unsupported module.
*/
class SunMiscUnsafeGenerator {
private static final String UNSAFE_NAME = "sun/misc/Unsafe";
private static final String UNSAFE_DESC = "L" + UNSAFE_NAME + ";";
private final Class internalUnsafeClass;
private final List fields = new ArrayList<>();
private final List methods = new ArrayList<>();
public SunMiscUnsafeGenerator(Class internalUnsafeClass) {
this.internalUnsafeClass = internalUnsafeClass;
addFields();
addMethods();
}
private void addFields() {
// fields that our unsafe class will contain
addField("INVALID_FIELD_OFFSET", int.class);
addField("ARRAY_BOOLEAN_BASE_OFFSET", int.class);
addField("ARRAY_BYTE_BASE_OFFSET", int.class);
addField("ARRAY_SHORT_BASE_OFFSET", int.class);
addField("ARRAY_CHAR_BASE_OFFSET", int.class);
addField("ARRAY_INT_BASE_OFFSET", int.class);
addField("ARRAY_LONG_BASE_OFFSET", int.class);
addField("ARRAY_FLOAT_BASE_OFFSET", int.class);
addField("ARRAY_DOUBLE_BASE_OFFSET", int.class);
addField("ARRAY_OBJECT_BASE_OFFSET", int.class);
addField("ARRAY_BOOLEAN_INDEX_SCALE", int.class);
addField("ARRAY_BYTE_INDEX_SCALE", int.class);
addField("ARRAY_SHORT_INDEX_SCALE", int.class);
addField("ARRAY_CHAR_INDEX_SCALE", int.class);
addField("ARRAY_INT_INDEX_SCALE", int.class);
addField("ARRAY_LONG_INDEX_SCALE", int.class);
addField("ARRAY_FLOAT_INDEX_SCALE", int.class);
addField("ARRAY_DOUBLE_INDEX_SCALE", int.class);
addField("ARRAY_OBJECT_INDEX_SCALE", int.class);
addField("ADDRESS_SIZE", int.class);
}
private boolean hasSuitableField(String name, Class type) {
try {
Field field = internalUnsafeClass.getDeclaredField(name);
return Modifier.isPublic(field.getModifiers()) && field.getType() == type;
} catch (NoSuchFieldException exception) {
return false;
}
}
private void addField(String name, Class type) {
if (!hasSuitableField(name, type)) {
throw new IllegalStateException(
"Could not find suitable field for " + name + " " + Type.getDescriptor(type));
}
fields.add(new FieldDescriptor(name, type));
}
private void addMethods() {
// methods that our unsafe class will contain
addMethod(
"compareAndSwapObject",
boolean.class,
Object.class,
long.class,
Object.class,
Object.class);
addMethod("compareAndSwapInt", boolean.class, Object.class, long.class, int.class, int.class);
addMethod(
"compareAndSwapLong", boolean.class, Object.class, long.class, long.class, long.class);
addMethod("putOrderedObject", void.class, Object.class, long.class, Object.class);
addMethod("putOrderedInt", void.class, Object.class, long.class, int.class);
addMethod("putOrderedLong", void.class, Object.class, long.class, long.class);
addMethod("allocateInstance", Object.class, Class.class);
addMethod("loadFence", void.class);
addMethod("storeFence", void.class);
addMethod("fullFence", void.class);
addMethod("getObject", Object.class, Object.class, long.class);
addMethod("putObject", void.class, Object.class, long.class, Object.class);
addMethod("getBoolean", boolean.class, Object.class, long.class);
addMethod("putBoolean", void.class, Object.class, long.class, boolean.class);
addMethod("getByte", byte.class, long.class);
addMethod("getByte", byte.class, Object.class, long.class);
addMethod("putByte", void.class, long.class, byte.class);
addMethod("putByte", void.class, Object.class, long.class, byte.class);
addMethod("getShort", short.class, long.class);
addMethod("getShort", short.class, Object.class, long.class);
addMethod("putShort", void.class, long.class, short.class);
addMethod("putShort", void.class, Object.class, long.class, short.class);
addMethod("getChar", char.class, long.class);
addMethod("getChar", char.class, Object.class, long.class);
addMethod("putChar", void.class, Object.class, long.class, char.class);
addMethod("putChar", void.class, long.class, char.class);
addMethod("getInt", int.class, Object.class, long.class);
addMethod("getInt", int.class, long.class);
addMethod("putInt", void.class, long.class, int.class);
addMethod("putInt", void.class, Object.class, long.class, int.class);
addMethod("getLong", long.class, long.class);
addMethod("getLong", long.class, Object.class, long.class);
addMethod("putLong", void.class, long.class, long.class);
addMethod("putLong", void.class, Object.class, long.class, long.class);
addMethod("getFloat", float.class, long.class);
addMethod("getFloat", float.class, Object.class, long.class);
addMethod("putFloat", void.class, Object.class, long.class, float.class);
addMethod("putFloat", void.class, long.class, float.class);
addMethod("getDouble", double.class, Object.class, long.class);
addMethod("getDouble", double.class, long.class);
addMethod("putDouble", void.class, Object.class, long.class, double.class);
addMethod("putDouble", void.class, long.class, double.class);
addMethod("getObjectVolatile", Object.class, Object.class, long.class);
addMethod("putObjectVolatile", void.class, Object.class, long.class, Object.class);
addMethod("getBooleanVolatile", boolean.class, Object.class, long.class);
addMethod("putBooleanVolatile", void.class, Object.class, long.class, boolean.class);
addMethod("getByteVolatile", byte.class, Object.class, long.class);
addMethod("putByteVolatile", void.class, Object.class, long.class, byte.class);
addMethod("getShortVolatile", short.class, Object.class, long.class);
addMethod("putShortVolatile", void.class, Object.class, long.class, short.class);
addMethod("getCharVolatile", char.class, Object.class, long.class);
addMethod("putCharVolatile", void.class, Object.class, long.class, char.class);
addMethod("getIntVolatile", int.class, Object.class, long.class);
addMethod("putIntVolatile", void.class, Object.class, long.class, int.class);
addMethod("getLongVolatile", long.class, Object.class, long.class);
addMethod("putLongVolatile", void.class, Object.class, long.class, long.class);
addMethod("getFloatVolatile", float.class, Object.class, long.class);
addMethod("putFloatVolatile", void.class, Object.class, long.class, float.class);
addMethod("getDoubleVolatile", double.class, Object.class, long.class);
addMethod("putDoubleVolatile", void.class, Object.class, long.class, double.class);
addMethod("getAndAddInt", int.class, Object.class, long.class, int.class);
addMethod("getAndAddLong", long.class, Object.class, long.class, long.class);
addMethod("getAndSetInt", int.class, Object.class, long.class, int.class);
addMethod("getAndSetLong", long.class, Object.class, long.class, long.class);
addMethod("getAndSetObject", Object.class, Object.class, long.class, Object.class);
addMethod("park", void.class, boolean.class, long.class);
addMethod("unpark", void.class, Object.class);
addMethod("throwException", void.class, Throwable.class);
addMethod("objectFieldOffset", long.class, Field.class);
addMethod("staticFieldBase", Object.class, Field.class);
addMethod("staticFieldOffset", long.class, Field.class);
addMethod("shouldBeInitialized", boolean.class, Class.class);
addMethod("ensureClassInitialized", void.class, Class.class);
addMethod("getAddress", long.class, long.class);
addMethod("putAddress", void.class, long.class, long.class);
addMethod("allocateMemory", long.class, long.class);
addMethod("reallocateMemory", long.class, long.class, long.class);
addMethod("setMemory", void.class, long.class, long.class, byte.class);
addMethod("setMemory", void.class, Object.class, long.class, long.class, byte.class);
addMethod("copyMemory", void.class, long.class, long.class, long.class);
addMethod(
"copyMemory", void.class, Object.class, long.class, Object.class, long.class, long.class);
addMethod("freeMemory", void.class, long.class);
addMethod("arrayBaseOffset", int.class, Class.class);
addMethod("arrayIndexScale", int.class, Class.class);
addMethod("addressSize", int.class);
addMethod("pageSize", int.class);
addMethod("getLoadAverage", int.class, double[].class, int.class);
// defineAnonymousClass was removed in jdk17
addOptionalMethod(
"defineAnonymousClass", Class.class, Class.class, byte[].class, Object[].class);
// this method is missing from internal unsafe in some jdk11 versions
addOptionalMethod("invokeCleaner", void.class, ByteBuffer.class);
}
private static List getNameCandidates(String name) {
if (name.startsWith("compareAndSwap")) {
name = name.replace("compareAndSwap", "compareAndSet");
} else if (name.startsWith("putOrdered")) {
name = name.replace("putOrdered", "put") + "Release";
}
if (name.contains("Object")) {
String alternativeName = name.replace("Object", "Reference");
return Arrays.asList(name, alternativeName);
}
return Collections.singletonList(name);
}
private void addOptionalMethod(String name, Class returnType, Class... parameterTypes) {
addMethod(name, true, getNameCandidates(name), returnType, parameterTypes);
}
private void addMethod(String name, Class returnType, Class... parameterTypes) {
addMethod(name, false, getNameCandidates(name), returnType, parameterTypes);
}
private void addMethod(
String name,
boolean optional,
List targetNameCandidates,
Class returnType,
Class... parameterTypes) {
String targetName = null;
for (String candidate : targetNameCandidates) {
if (hasSuitableMethod(candidate, returnType, parameterTypes)) {
targetName = candidate;
break;
}
}
if (targetName == null) {
if (optional) {
return;
}
throw new IllegalStateException(
"Could not find suitable method for "
+ name
+ " "
+ Type.getMethodDescriptor(Type.getType(returnType), toTypes(parameterTypes)));
}
methods.add(new MethodDescriptor(name, targetName, returnType, parameterTypes));
}
private boolean hasSuitableMethod(String name, Class returnType, Class... parameterTypes) {
try {
Method method = internalUnsafeClass.getDeclaredMethod(name, parameterTypes);
return Modifier.isPublic(method.getModifiers()) && method.getReturnType() == returnType;
} catch (NoSuchMethodException e) {
return false;
}
}
private static Type[] toTypes(Class... classes) {
Type[] result = new Type[classes.length];
for (int i = 0; i < classes.length; i++) {
result[i] = Type.getType(classes[i]);
}
return result;
}
private static class FieldDescriptor {
final String name;
final Class type;
FieldDescriptor(String name, Class type) {
this.name = name;
this.type = type;
}
}
private static class MethodDescriptor {
final String name;
final String targetName;
final Class returnType;
final Class[] parameterTypes;
MethodDescriptor(
String name, String targetName, Class returnType, Class[] parameterTypes) {
this.name = name;
this.targetName = targetName;
this.returnType = returnType;
this.parameterTypes = parameterTypes;
}
}
private byte[] getBytes() {
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS);
ClassVisitor cv = cw;
cv.visit(V1_5, ACC_PUBLIC | ACC_FINAL | ACC_SUPER, UNSAFE_NAME, null, "java/lang/Object", null);
{
FieldVisitor fv =
cv.visitField(ACC_PRIVATE | ACC_STATIC | ACC_FINAL, "theUnsafe", UNSAFE_DESC, null, null);
fv.visitEnd();
}
{
FieldVisitor fv =
cv.visitField(
ACC_PRIVATE | ACC_STATIC | ACC_FINAL,
"theInternalUnsafe",
Type.getDescriptor(internalUnsafeClass),
null,
null);
fv.visitEnd();
}
{
MethodVisitor mv = cv.visitMethod(ACC_PRIVATE, "", "()V", null, null);
mv.visitCode();
mv.visitVarInsn(ALOAD, 0);
mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "", "()V", false);
mv.visitInsn(RETURN);
mv.visitMaxs(0, 0);
mv.visitEnd();
}
for (FieldDescriptor field : fields) {
FieldVisitor fv =
cv.visitField(
ACC_PUBLIC | ACC_STATIC | ACC_FINAL,
field.name,
Type.getDescriptor(field.type),
null,
null);
fv.visitEnd();
}
for (MethodDescriptor method : methods) {
Type[] parameters = toTypes(method.parameterTypes);
Type returnType = Type.getType(method.returnType);
String descriptor = Type.getMethodDescriptor(returnType, parameters);
MethodVisitor mv = cv.visitMethod(ACC_PUBLIC, method.name, descriptor, null, null);
mv.visitCode();
mv.visitFieldInsn(
GETSTATIC, UNSAFE_NAME, "theInternalUnsafe", Type.getDescriptor(internalUnsafeClass));
int slot = 1;
for (Type parameter : parameters) {
mv.visitVarInsn(parameter.getOpcode(ILOAD), slot);
slot += parameter.getSize();
}
mv.visitMethodInsn(
INVOKEVIRTUAL,
Type.getInternalName(internalUnsafeClass),
method.targetName,
descriptor,
false);
mv.visitInsn(returnType.getOpcode(IRETURN));
mv.visitMaxs(0, 0);
mv.visitEnd();
}
{
MethodVisitor mv = cv.visitMethod(ACC_STATIC, "", "()V", null, null);
mv.visitCode();
// private static final sun.misc.Unsafe theUnsafe = new Unsafe();
mv.visitTypeInsn(NEW, UNSAFE_NAME);
mv.visitInsn(DUP);
mv.visitMethodInsn(INVOKESPECIAL, UNSAFE_NAME, "", "()V", false);
mv.visitFieldInsn(PUTSTATIC, UNSAFE_NAME, "theUnsafe", UNSAFE_DESC);
// private static final jdk.internal.misc.Unsafe theInternalUnsafe =
// jdk.internal.misc.Unsafe.getUnsafe();
mv.visitMethodInsn(
INVOKESTATIC,
Type.getInternalName(internalUnsafeClass),
"getUnsafe",
"()" + Type.getDescriptor(internalUnsafeClass),
false);
mv.visitFieldInsn(
PUTSTATIC, UNSAFE_NAME, "theInternalUnsafe", Type.getDescriptor(internalUnsafeClass));
// initialize field value from corresponding field in internal unsafe class
for (FieldDescriptor field : fields) {
mv.visitFieldInsn(
GETSTATIC,
Type.getInternalName(internalUnsafeClass),
field.name,
Type.getDescriptor(field.type));
mv.visitFieldInsn(PUTSTATIC, UNSAFE_NAME, field.name, Type.getDescriptor(field.type));
}
mv.visitInsn(RETURN);
mv.visitMaxs(0, 0);
mv.visitEnd();
}
cv.visitEnd();
return cw.toByteArray();
}
public static void generateUnsafe(
Class internalUnsafeClass, AgentClassLoader agentClassLoader) {
SunMiscUnsafeGenerator generator = new SunMiscUnsafeGenerator(internalUnsafeClass);
agentClassLoader.defineClass("sun.misc.Unsafe", generator.getBytes());
}
}