--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/jdk/jfr/javaagent/InstrumentationEventCallback.java	Tue Feb 18 08:14:48 2020 -0800
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package jdk.jfr.javaagent;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public class InstrumentationEventCallback {
+    private static AtomicBoolean wasCalled = new AtomicBoolean(false);
+
+    public static void callback() {
+        wasCalled.set(true);
+    }
+
+    public static void clear() {
+        wasCalled.set(false);
+    }
+
+    public static boolean wasCalled() {
+        return wasCalled.get();
+    }
+}
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/jdk/jfr/javaagent/TestEventInstrumentation.java	Tue Feb 18 08:14:48 2020 -0800
@@ -0,0 +1,172 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package jdk.jfr.javaagent;
+
+import java.lang.instrument.ClassFileTransformer;
+import java.lang.instrument.IllegalClassFormatException;
+import java.lang.instrument.Instrumentation;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.security.ProtectionDomain;
+
+import jdk.internal.org.objectweb.asm.ClassReader;
+import jdk.internal.org.objectweb.asm.ClassVisitor;
+import jdk.internal.org.objectweb.asm.ClassWriter;
+import jdk.internal.org.objectweb.asm.MethodVisitor;
+import jdk.internal.org.objectweb.asm.Opcodes;
+import jdk.internal.org.objectweb.asm.Type;
+
+import jdk.jfr.Event;
+import jdk.jfr.Recording;
+import jdk.jfr.consumer.RecordingFile;
+import jdk.test.lib.Asserts;
+
+/*
+ * @test
+ * @summary Verify that a subclass of the JFR Event class
+ *          can be successfully instrumented.
+ * @key jfr
+ * @library /test/lib
+ * @modules java.base/jdk.internal.org.objectweb.asm
+ *          jdk.jartool/sun.tools.jar
+ * @build jdk.jfr.javaagent.InstrumentationEventCallback
+ *        jdk.jfr.javaagent.TestEventInstrumentation
+ * @run driver jdk.test.lib.util.JavaAgentBuilder
+ *             jdk.jfr.javaagent.TestEventInstrumentation TestEventInstrumentation.jar
+ *             Can-Redefine-Classes:true Can-Retransform-Classes:true
+ * @run main/othervm -javaagent:TestEventInstrumentation.jar
+ *      jdk.jfr.javaagent.TestEventInstrumentation
+ */
+public class TestEventInstrumentation {
+    private static Instrumentation instrumentation = null;
+    private static TestEventInstrumentation testTransformer = null;
+    private static Exception transformException = null;
+
+    public static class TestEvent extends Event {
+    }
+
+    public static void main(String[] args) throws Throwable {
+        // loads test event class, run empty constructor w/o instrumentation
+        TestEvent event = new TestEvent();
+
+        // add instrumentation and test an instrumented constructor
+        instrumentation.addTransformer(new Transformer(), true);
+        instrumentation.retransformClasses(TestEvent.class);
+        event = new TestEvent();
+        Asserts.assertTrue(InstrumentationEventCallback.wasCalled());
+
+        // record test event with instrumented constructor, verify it is recorded
+        InstrumentationEventCallback.clear();
+        try (Recording r = new Recording()) {
+            r.enable(TestEvent.class);
+            r.start();
+            new TestEvent().commit();
+            Asserts.assertTrue(InstrumentationEventCallback.wasCalled());
+            Path rf = Paths.get("", "recording.jfr");
+            r.dump(rf);
+            Asserts.assertFalse(RecordingFile.readAllEvents(rf).isEmpty());
+        }
+    }
+
+    private static void log(String msg) {
+        System.out.println(msg);
+    }
+
+    // ======================== Java agent used to transform classes
+    public static void premain(String args, Instrumentation inst) throws Exception {
+        instrumentation = inst;
+    }
+
+    static class Transformer implements ClassFileTransformer {
+        public byte[] transform(ClassLoader classLoader, String className,
+                                Class<?> classBeingRedefined, ProtectionDomain pd,
+                                byte[] bytes) throws IllegalClassFormatException {
+            byte[] result = null;
+            try {
+                // Check if this class should be instrumented.
+                if (!className.contains("TestEventInstrumentation$TestEvent")) {
+                    return null;
+                }
+
+                ClassReader reader = new ClassReader(bytes);
+                ClassWriter writer = new ClassWriter(reader, ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
+                CallbackClassVisitor classVisitor = new CallbackClassVisitor(writer);
+
+                // visit the reader's class by the classVisitor
+                reader.accept(classVisitor, 0);
+                result = writer.toByteArray();
+            } catch (Exception e) {
+                log("Exception occured in transform(): " + e.getMessage());
+                e.printStackTrace(System.out);
+                transformException = e;
+            }
+            return result;
+        }
+
+        private static class CallbackClassVisitor extends ClassVisitor {
+            private String className;
+
+            public CallbackClassVisitor(ClassVisitor cv) {
+                super(Opcodes.ASM7, cv);
+            }
+
+            @Override
+            public void visit(int version, int access, String name, String signature,
+                              String superName, String[] interfaces) {
+                // visit the header of the class - called per class header visit
+                cv.visit(version, access, name, signature, superName, interfaces);
+                className = name;
+            }
+
+            @Override
+            public MethodVisitor visitMethod(
+                                             int access, String methodName, String desc,
+                                             String signature, String[] exceptions) {
+                // called for each method in a class
+                boolean isInstrumentedMethod = methodName.contains("<init>");
+                MethodVisitor mv = cv.visitMethod(access, methodName, desc, signature, exceptions);
+                if (isInstrumentedMethod) {
+                    mv = new CallbackMethodVisitor(mv);
+                    log("instrumented <init> in class " + className);
+                }
+                return mv;
+            }
+        }
+
+        public static class CallbackMethodVisitor extends MethodVisitor {
+            public CallbackMethodVisitor(MethodVisitor mv) {
+                super(Opcodes.ASM7, mv);
+            }
+
+            @Override
+            public void visitCode() {
+                mv.visitCode();
+                String methodDescr = Type.getMethodDescriptor(Type.VOID_TYPE, Type.VOID_TYPE);
+                String className = InstrumentationEventCallback.class.getName().replace('.', '/');
+                mv.visitMethodInsn(Opcodes.INVOKESTATIC, className, "callback", "()V", false);
+            }
+        }
+    }
+}

--- a/test/lib/jdk/test/lib/util/JavaAgentBuilder.java	Tue Feb 18 17:20:04 2020 +0100
+++ b/test/lib/jdk/test/lib/util/JavaAgentBuilder.java	Tue Feb 18 08:14:48 2020 -0800
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -28,6 +28,8 @@
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.Arrays;
+import java.util.Map;
+import java.util.HashMap;
 import java.util.jar.Attributes;
 import java.util.jar.Manifest;
 
@@ -53,11 +55,24 @@
      * @param args[1]    file name of the agent jar to be created
      * @throws IOException
      */
-    public static void main(String... args) throws IOException {
+    public static void main(String... args) throws Exception {
         String agentClass = args[0];
         String agentJar = args[1];
         System.out.println("Building " + agentJar + " with agent class " + agentClass);
-        build(agentClass, agentJar);
+
+        build(agentClass, agentJar, parseExtraAttrs(args));
+    }
+
+    private static Map<String,String> parseExtraAttrs(String[] args) throws Exception {
+        Map<String,String> attrs = new HashMap<>();
+        for (int i = 2; i < args.length; i++) {
+            String[] parts = args[i].split(":");
+            if (parts.length != 2) {
+                throw new IllegalArgumentException("Extra attributes should be of format 'key:value'");
+            }
+            attrs.put(parts[0],parts[1]);
+        }
+        return attrs;
     }
 
     /**
@@ -70,6 +85,21 @@
      * @throws IOException
      */
     public static void build(String agentClass, String agentJar) throws IOException {
+        build(agentClass, agentJar, new HashMap<String, String>());
+    }
+
+    /**
+     * Build a java agent jar file with a given agent class.
+     * The agent class will be added as both premain class and agent class.
+     *
+     * @param agentClass fully qualified name of an agent class
+     * @param agentJar   file name of the agent jar to be created
+     *                   the file will be placed in a current work directory
+     * @param extraAttrs additional manifest attributes
+     * @throws IOException
+     */
+    public static void build(String agentClass, String agentJar,
+                             Map<String, String> extraAttrs) throws IOException {
         Manifest mf = new Manifest();
         Attributes attrs = mf.getMainAttributes();
         attrs.put(Attributes.Name.MANIFEST_VERSION, "1.0");
@@ -78,6 +108,8 @@
         attrs.putValue("Premain-Class", agentClass);
         attrs.putValue("Agent-Class", agentClass);
 
+        extraAttrs.forEach( (k,v) -> attrs.putValue(k,v));
+
         Path jarFile = Paths.get(".", agentJar);
         String testClasses = Utils.TEST_CLASSES;
         String agentPath = agentClass.replace(".", File.separator) + ".class";