1 /*
   2  * Copyright (c) 2016, 2018, 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 
  26 package jdk.tools.jaotc;
  27 
  28 import jdk.tools.jaotc.binformat.BinaryContainer;
  29 import jdk.tools.jaotc.binformat.Symbol;
  30 
  31 import jdk.vm.ci.code.site.Call;
  32 
  33 final class ForeignGotCallSiteRelocationSymbol extends CallSiteRelocationSymbol {
  34 
  35     ForeignGotCallSiteRelocationSymbol(CompiledMethodInfo mi, Call call, CallSiteRelocationInfo callSiteRelocation, DataBuilder dataBuilder) {
  36         super(createPltSymbol(dataBuilder, mi, call, callSiteRelocation));
  37     }
  38 
  39     private static Symbol createPltSymbol(DataBuilder dataBuilder, CompiledMethodInfo mi, Call call, CallSiteRelocationInfo callSiteRelocation) {
  40         BinaryContainer binaryContainer = dataBuilder.getBinaryContainer();
  41         String vmSymbolName = callSiteRelocation.targetSymbol;
  42 
  43         // Add relocation to GOT cell for call resolution jump.
  44         String pltSymbolName = "plt." + vmSymbolName;
  45         Symbol pltSymbol = binaryContainer.getSymbol(pltSymbolName);
  46 
  47         if (pltSymbol == null) {
  48             String gotSymbolName = "got." + vmSymbolName;
  49             Symbol gotSymbol = binaryContainer.getGotSymbol(gotSymbolName);
  50             assert gotSymbol != null : "undefined VM got symbol '" + gotSymbolName + "' for call at " + call.pcOffset + " in " + mi.getMethodInfo().getSymbolName();
  51 
  52             // Generate PLT jump (do it only once).
  53             final int pltStartOffset = binaryContainer.getCodeContainer().getByteStreamSize();
  54             final int pltEndOffset = pltStartOffset + addPltJump(dataBuilder);
  55 
  56             // Link GOT cell to PLT jump.
  57             pltSymbol = createCodeContainerSymbol(binaryContainer, pltSymbolName, pltStartOffset);
  58             addExternalPltToGotRelocation(binaryContainer, gotSymbol, pltEndOffset);
  59         }
  60 
  61         return pltSymbol;
  62     }
  63 
  64     private static int addPltJump(DataBuilder dataBuilder) {
  65         ELFMacroAssembler masm = ELFMacroAssembler.getELFMacroAssembler(dataBuilder.getBackend().getTarget());
  66         byte[] code = masm.getPLTJumpCode(); // It includes alignment nops.
  67         int size = masm.currentEndOfInstruction();
  68         dataBuilder.getBinaryContainer().appendCodeBytes(code, 0, code.length);
  69         return size;
  70     }
  71 
  72 }