1 /*
   2  * Copyright (c) 2012, 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.
   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  */
  23 
  24 
  25 package org.graalvm.compiler.hotspot.stubs;
  26 
  27 import static org.graalvm.compiler.hotspot.GraalHotSpotVMConfig.INJECTED_VMCONFIG;
  28 import static org.graalvm.compiler.hotspot.nodes.JumpToExceptionHandlerNode.jumpToExceptionHandler;
  29 import static org.graalvm.compiler.hotspot.nodes.PatchReturnAddressNode.patchReturnAddress;
  30 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.readExceptionOop;
  31 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.readExceptionPc;
  32 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.registerAsWord;
  33 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.writeExceptionOop;
  34 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.writeExceptionPc;
  35 import static org.graalvm.compiler.hotspot.stubs.StubUtil.cAssertionsEnabled;
  36 import static org.graalvm.compiler.hotspot.stubs.StubUtil.decipher;
  37 import static org.graalvm.compiler.hotspot.stubs.StubUtil.fatal;
  38 import static org.graalvm.compiler.hotspot.stubs.StubUtil.newDescriptor;
  39 import static org.graalvm.compiler.hotspot.stubs.StubUtil.printf;
  40 
  41 import org.graalvm.compiler.api.replacements.Fold;
  42 import org.graalvm.compiler.api.replacements.Fold.InjectedParameter;
  43 import org.graalvm.compiler.api.replacements.Snippet;
  44 import org.graalvm.compiler.api.replacements.Snippet.ConstantParameter;
  45 import org.graalvm.compiler.core.common.spi.ForeignCallDescriptor;
  46 import org.graalvm.compiler.debug.Assertions;
  47 import org.graalvm.compiler.graph.Node.ConstantNodeParameter;
  48 import org.graalvm.compiler.graph.Node.NodeIntrinsic;
  49 import org.graalvm.compiler.hotspot.GraalHotSpotVMConfig;
  50 import org.graalvm.compiler.hotspot.HotSpotBackend;
  51 import org.graalvm.compiler.hotspot.HotSpotForeignCallLinkage;
  52 import org.graalvm.compiler.hotspot.meta.HotSpotProviders;
  53 import org.graalvm.compiler.hotspot.nodes.StubForeignCallNode;
  54 import org.graalvm.compiler.options.OptionValues;
  55 import org.graalvm.compiler.word.Word;
  56 import jdk.internal.vm.compiler.word.WordFactory;
  57 
  58 import jdk.vm.ci.code.Register;
  59 
  60 /**
  61  * Stub called by the {@linkplain GraalHotSpotVMConfig#MARKID_EXCEPTION_HANDLER_ENTRY exception
  62  * handler entry point} in a compiled method. This entry point is used when returning to a method to
  63  * handle an exception thrown by a callee. It is not used for routing implicit exceptions.
  64  * Therefore, it does not need to save any registers as HotSpot uses a caller save convention.
  65  * <p>
  66  * The descriptor for a call to this stub is {@link HotSpotBackend#EXCEPTION_HANDLER}.
  67  */
  68 public class ExceptionHandlerStub extends SnippetStub {
  69 
  70     public ExceptionHandlerStub(OptionValues options, HotSpotProviders providers, HotSpotForeignCallLinkage linkage) {
  71         super("exceptionHandler", options, providers, linkage);
  72     }
  73 
  74     @Override
  75     protected Object getConstantParameterValue(int index, String name) {
  76         if (index == 2) {
  77             return providers.getRegisters().getThreadRegister();
  78         }
  79         assert index == 3;
  80         return StubOptions.TraceExceptionHandlerStub.getValue(options);
  81     }
  82 
  83     @Snippet
  84     private static void exceptionHandler(Object exception, Word exceptionPc, @ConstantParameter Register threadRegister, @ConstantParameter boolean logging) {
  85         Word thread = registerAsWord(threadRegister);
  86         checkNoExceptionInThread(thread, assertionsEnabled(INJECTED_VMCONFIG));
  87         checkExceptionNotNull(assertionsEnabled(INJECTED_VMCONFIG), exception);
  88         writeExceptionOop(thread, exception);
  89         writeExceptionPc(thread, exceptionPc);
  90         if (logging) {
  91             printf("handling exception %p (", Word.objectToTrackedPointer(exception).rawValue());
  92             decipher(Word.objectToTrackedPointer(exception).rawValue());
  93             printf(") at %p (", exceptionPc.rawValue());
  94             decipher(exceptionPc.rawValue());
  95             printf(")\n");
  96         }
  97 
  98         // patch throwing pc into return address so that deoptimization finds the right debug info
  99         patchReturnAddress(exceptionPc);
 100 
 101         Word handlerPc = exceptionHandlerForPc(EXCEPTION_HANDLER_FOR_PC, thread);
 102 
 103         if (logging) {
 104             printf("handler for exception %p at %p is at %p (", Word.objectToTrackedPointer(exception).rawValue(), exceptionPc.rawValue(), handlerPc.rawValue());
 105             decipher(handlerPc.rawValue());
 106             printf(")\n");
 107         }
 108 
 109         // patch the return address so that this stub returns to the exception handler
 110         jumpToExceptionHandler(handlerPc);
 111     }
 112 
 113     static void checkNoExceptionInThread(Word thread, boolean enabled) {
 114         if (enabled) {
 115             Object currentException = readExceptionOop(thread);
 116             if (currentException != null) {
 117                 fatal("exception object in thread must be null, not %p", Word.objectToTrackedPointer(currentException).rawValue());
 118             }
 119             if (cAssertionsEnabled(INJECTED_VMCONFIG)) {
 120                 // This thread-local is only cleared in DEBUG builds of the VM
 121                 // (see OptoRuntime::generate_exception_blob)
 122                 Word currentExceptionPc = readExceptionPc(thread);
 123                 if (currentExceptionPc.notEqual(WordFactory.zero())) {
 124                     fatal("exception PC in thread must be zero, not %p", currentExceptionPc.rawValue());
 125                 }
 126             }
 127         }
 128     }
 129 
 130     static void checkExceptionNotNull(boolean enabled, Object exception) {
 131         if (enabled && exception == null) {
 132             fatal("exception must not be null");
 133         }
 134     }
 135 
 136     /**
 137      * Determines if either Java assertions are enabled for Graal or if this is a HotSpot build
 138      * where the ASSERT mechanism is enabled.
 139      */
 140     @Fold
 141     @SuppressWarnings("all")
 142     static boolean assertionsEnabled(@InjectedParameter GraalHotSpotVMConfig config) {
 143         return Assertions.assertionsEnabled() || cAssertionsEnabled(config);
 144     }
 145 
 146     public static final ForeignCallDescriptor EXCEPTION_HANDLER_FOR_PC = newDescriptor(ExceptionHandlerStub.class, "exceptionHandlerForPc", Word.class, Word.class);
 147 
 148     @NodeIntrinsic(value = StubForeignCallNode.class)
 149     public static native Word exceptionHandlerForPc(@ConstantNodeParameter ForeignCallDescriptor exceptionHandlerForPc, Word thread);
 150 }