1 /*
   2  * Copyright (c) 2016, 2019, 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 package jdk.jfr.internal;
  26 
  27 import java.lang.reflect.Modifier;
  28 
  29 import jdk.jfr.Event;
  30 import jdk.jfr.internal.handlers.EventHandler;
  31 import jdk.jfr.internal.instrument.JDKEvents;
  32 
  33 /**
  34  * All upcalls from the JVM should go through this class.
  35  *
  36  */
  37 // Called by native
  38 final class JVMUpcalls {
  39     /**
  40      * Called by the JVM when a retransform happens on a tagged class
  41      *
  42      * @param traceId
  43      *            Id of the class
  44      * @param dummy
  45      *            (not used but needed since invoke infrastructure in native
  46      *            uses same signature bytesForEagerInstrumentation)
  47      * @param clazz
  48      *            class being retransformed
  49      * @param oldBytes
  50      *            byte code
  51      * @return byte code to use
  52      * @throws Throwable
  53      */
  54     static byte[] onRetransform(long traceId, boolean dummy, Class<?> clazz, byte[] oldBytes) throws Throwable {
  55         try {
  56             if (Event.class.isAssignableFrom(clazz) && !Modifier.isAbstract(clazz.getModifiers())) {
  57                 EventHandler handler = Utils.getHandler(clazz.asSubclass(Event.class));
  58                 if (handler == null) {
  59                     Logger.log(LogTag.JFR_SYSTEM, LogLevel.INFO, "No event handler found for " + clazz.getName() + ". Ignoring instrumentation request.");
  60                     // Probably triggered by some other agent
  61                     return oldBytes;
  62                 }
  63                 Logger.log(LogTag.JFR_SYSTEM, LogLevel.INFO, "Adding instrumentation to event class " + clazz.getName() + " using retransform");
  64                 EventInstrumentation ei = new EventInstrumentation(clazz.getSuperclass(), oldBytes, traceId);
  65                 byte[] bytes = ei.buildInstrumented();
  66                 ASMToolkit.logASM(clazz.getName(), bytes);
  67                 return bytes;
  68             }
  69             return JDKEvents.retransformCallback(clazz, oldBytes);
  70         } catch (Throwable t) {
  71             Logger.log(LogTag.JFR_SYSTEM, LogLevel.WARN, "Unexpected error when adding instrumentation to event class " + clazz.getName());
  72         }
  73         return oldBytes;
  74 
  75     }
  76 
  77     /**
  78      * Called by the JVM when requested to do an "eager" instrumentation. Would
  79      * normally happen when JVMTI retransform capabilities are not available.
  80      *
  81      * @param traceId
  82      *            Id of the class
  83      * @param forceInstrumentation
  84      *            add instrumentation regardless if event is enabled or not.
  85      * @param superClazz
  86      *            the super class of the class being processed
  87      * @param oldBytes
  88      *            byte code
  89      * @return byte code to use
  90      * @throws Throwable
  91      */
  92     static byte[] bytesForEagerInstrumentation(long traceId, boolean forceInstrumentation, Class<?> superClass, byte[] oldBytes) throws Throwable {
  93         if (JVMSupport.isNotAvailable()) {
  94             return oldBytes;
  95         }
  96         String eventName = "<Unknown>";
  97         try {
  98             EventInstrumentation ei = new EventInstrumentation(superClass, oldBytes, traceId);
  99             eventName = ei.getEventName();
 100             if (!forceInstrumentation) {
 101                 // Assume we are recording
 102                 MetadataRepository mr = MetadataRepository.getInstance();
 103                 // No need to generate bytecode if:
 104                 // 1) Event class is disabled, and there is not an external configuration that overrides.
 105                 // 2) Event class has @Registered(false)
 106                 if (!mr.isEnabled(ei.getEventName()) && !ei.isEnabled() || !ei.isRegistered()) {
 107                     Logger.log(LogTag.JFR_SYSTEM, LogLevel.INFO, "Skipping instrumentation for event type " + eventName + " since event was disabled on class load");
 108                     return oldBytes;
 109                 }
 110             }
 111             // Corner case when we are forced to generate bytecode. We can't reference the event
 112             // handler in #isEnabled() before event class has been registered, so we add a
 113             // guard against a null reference.
 114             ei.setGuardHandler(true);
 115             Logger.log(LogTag.JFR_SYSTEM, LogLevel.INFO, "Adding " + (forceInstrumentation ? "forced " : "") + "instrumentation for event type " + eventName + " during initial class load");
 116             EventHandlerCreator eh = new EventHandlerCreator(traceId, ei.getSettingInfos(), ei.getFieldInfos());
 117             // Handler class must be loaded before instrumented event class can
 118             // be used
 119             eh.makeEventHandlerClass();
 120             byte[] bytes = ei.buildInstrumented();
 121             ASMToolkit.logASM(ei.getClassName() + "(" + traceId + ")", bytes);
 122             return bytes;
 123         } catch (Throwable t) {
 124             Logger.log(LogTag.JFR_SYSTEM, LogLevel.WARN, "Unexpected error when adding instrumentation for event type " + eventName);
 125             return oldBytes;
 126         }
 127     }
 128 
 129     /**
 130      * Called by the JVM to create the recorder thread.
 131      *
 132      * @param systemThreadGroup
 133      *            the system thread group
 134      *
 135      * @param contextClassLoader
 136      *            the context class loader.
 137      *
 138      * @return a new thread
 139      */
 140     static Thread createRecorderThread(ThreadGroup systemThreadGroup, ClassLoader contextClassLoader) {
 141         return SecuritySupport.createRecorderThread(systemThreadGroup, contextClassLoader);
 142     }
 143 }