linux/amd64/LinuxAMD64CFrame.java

/*
 * Copyright (c) 2003, 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.
 *
 * 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
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 * questions.
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package sun.jvm.hotspot.debugger.linux.amd64;

import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.debugger.amd64.*;
import sun.jvm.hotspot.debugger.linux.*;
import sun.jvm.hotspot.debugger.cdbg.*;
import sun.jvm.hotspot.debugger.cdbg.basic.*;

final public class LinuxAMD64CFrame extends BasicCFrame {

   public static LinuxAMD64CFrame getTopFrame(LinuxDebugger dbg, Address rip, ThreadContext context) {
      Address libptr = dbg.findLibPtrByAddress(rip);
      Address cfa = context.getRegisterAsAddress(AMD64ThreadContext.RBP);
      DwarfParser dwarf = null;

      if (libptr != null) { // Native frame
        dwarf = new DwarfParser(libptr);
        try {
          dwarf.processDwarf(rip);
        } catch (DebuggerException e) {
          // DWARF processing should succeed when the frame is native
          // but it might fail if Common Information Entry (CIE) has language
          // personality routine and/or Language Specific Data Area (LSDA).
          return new LinuxAMD64CFrame(dbg, cfa, rip, dwarf, true);
        }
        cfa = ((dwarf.getCFARegister() == AMD64ThreadContext.RBP) &&
               !dwarf.isBPOffsetAvailable())
                  ? context.getRegisterAsAddress(AMD64ThreadContext.RBP)
                  : context.getRegisterAsAddress(dwarf.getCFARegister())
                           .addOffsetTo(dwarf.getCFAOffset());
      }

      return (cfa == null) ? null
                           : new LinuxAMD64CFrame(dbg, cfa, rip, dwarf);
   }

   private LinuxAMD64CFrame(LinuxDebugger dbg, Address cfa, Address rip, DwarfParser dwarf) {
      this(dbg, cfa, rip, dwarf, false);
   }

   private LinuxAMD64CFrame(LinuxDebugger dbg, Address cfa, Address rip, DwarfParser dwarf, boolean finalFrame) {
      super(dbg.getCDebugger());
      this.cfa = cfa;
      this.rip = rip;
      this.dbg = dbg;
      this.dwarf = dwarf;
      this.finalFrame = finalFrame;
   }

   // override base class impl to avoid ELF parsing
   public ClosestSymbol closestSymbolToPC() {
      // try native lookup in debugger.
      return dbg.lookup(dbg.getAddressValue(pc()));
   }

   public Address pc() {
      return rip;
   }

   public Address localVariableBase() {
      return cfa;
   }

   private Address getNextPC(boolean useDwarf) {
     try {
       long offs = useDwarf ? dwarf.getReturnAddressOffsetFromCFA()
                            : ADDRESS_SIZE;
       return cfa.getAddressAt(offs);
     } catch (UnmappedAddressException | UnalignedAddressException e) {
       return null;
     }
   }

   private boolean isValidFrame(Address nextCFA, ThreadContext context) {
     return (nextCFA != null) &&
             !nextCFA.lessThan(context.getRegisterAsAddress(AMD64ThreadContext.RSP));
   }

   private Address getNextCFA(DwarfParser nextDwarf, ThreadContext context) {
     Address nextCFA;

     if (nextDwarf == null) { // Next frame is Java
       nextCFA = (dwarf == null) ? cfa.getAddressAt(0) // Current frame is Java (Use RBP)
                                 : cfa.getAddressAt(dwarf.getBasePointerOffsetFromCFA()); // Current frame is Native
     } else { // Next frame is Native
       if (dwarf == null) { // Current frame is Java (Use RBP)
         nextCFA = cfa.getAddressAt(0);
       } else { // Current frame is Native
         int nextCFAReg = nextDwarf.getCFARegister();
         if (!dwarf.isBPOffsetAvailable() && // Use RBP as CFA
             (nextCFAReg == AMD64ThreadContext.RBP) &&
             (nextCFAReg != dwarf.getCFARegister())) {
           nextCFA = context.getRegisterAsAddress(AMD64ThreadContext.RBP);
           if (nextCFA == null) {
             return null;
           }
           nextCFA = nextCFA.getAddressAt(0);
         } else {
           nextCFA = cfa.getAddressAt(dwarf.getBasePointerOffsetFromCFA());
         }
       }
       if (nextCFA != null) {
         nextCFA = nextCFA.addOffsetTo(-nextDwarf.getBasePointerOffsetFromCFA());
       }
     }

     return isValidFrame(nextCFA, context) ? nextCFA : null;
   }

   @Override
   public CFrame sender(ThreadProxy thread) {
     if (finalFrame) {
       return null;
     }

     ThreadContext context = thread.getContext();

     Address nextPC = getNextPC(dwarf != null);
     if (nextPC == null) {
       return null;
     }

     DwarfParser nextDwarf = null;

     if ((dwarf != null) && dwarf.isIn(nextPC)) {
       nextDwarf = dwarf;
     } else {
       Address libptr = dbg.findLibPtrByAddress(nextPC);
       if (libptr != null) {
         try {
           nextDwarf = new DwarfParser(libptr);
         } catch (DebuggerException e) {
           // Bail out to Java frame
         }
       }
     }

     if (nextDwarf != null) {
       try {
         nextDwarf.processDwarf(nextPC);
       } catch (DebuggerException e) {
         // DWARF processing should succeed when the frame is native
         // but it might fail if Common Information Entry (CIE) has language
         // personality routine and/or Language Specific Data Area (LSDA).
         return new LinuxAMD64CFrame(dbg, null, nextPC, nextDwarf, true);
       }
     }

     Address nextCFA = getNextCFA(nextDwarf, context);
     return isValidFrame(nextCFA, context) ? new LinuxAMD64CFrame(dbg, nextCFA, nextPC, nextDwarf)
                                           : null;
   }

   // package/class internals only
   private static final int ADDRESS_SIZE = 8;
   private Address rip;
   private Address cfa;
   private LinuxDebugger dbg;
   private DwarfParser dwarf;
   private boolean finalFrame;
}