--- /dev/null	2021-01-19 17:38:25.908523431 +0000
+++ new/agent/src/share/classes/sun/jvm/hotspot/runtime/linux_aarch64/LinuxAARCH64JavaThreadPDAccess.java	2021-01-25 19:31:22.047322084 +0000
@@ -0,0 +1,132 @@
+/*
+ * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, Red Hat Inc.
+ * 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
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+package sun.jvm.hotspot.runtime.linux_aarch64;
+
+import java.io.*;
+import java.util.*;
+import sun.jvm.hotspot.debugger.*;
+import sun.jvm.hotspot.debugger.aarch64.*;
+import sun.jvm.hotspot.runtime.*;
+import sun.jvm.hotspot.runtime.aarch64.*;
+import sun.jvm.hotspot.types.*;
+import sun.jvm.hotspot.utilities.*;
+
+public class LinuxAARCH64JavaThreadPDAccess implements JavaThreadPDAccess {
+  private static AddressField  lastJavaFPField;
+  private static AddressField  osThreadField;
+
+  // Field from OSThread
+  private static CIntegerField osThreadThreadIDField;
+
+  // This is currently unneeded but is being kept in case we change
+  // the currentFrameGuess algorithm
+  private static final long GUESS_SCAN_RANGE = 128 * 1024;
+
+  static {
+    VM.registerVMInitializedObserver(new Observer() {
+        public void update(Observable o, Object data) {
+          initialize(VM.getVM().getTypeDataBase());
+        }
+      });
+  }
+
+  private static synchronized void initialize(TypeDataBase db) {
+    Type type = db.lookupType("JavaThread");
+    osThreadField           = type.getAddressField("_osthread");
+
+    Type anchorType = db.lookupType("JavaFrameAnchor");
+    lastJavaFPField         = anchorType.getAddressField("_last_Java_fp");
+
+    Type osThreadType = db.lookupType("OSThread");
+    osThreadThreadIDField   = osThreadType.getCIntegerField("_thread_id");
+  }
+
+  public Address getLastJavaFP(Address addr) {
+    return lastJavaFPField.getValue(addr.addOffsetTo(sun.jvm.hotspot.runtime.JavaThread.getAnchorField().getOffset()));
+  }
+
+  public Address getLastJavaPC(Address addr) {
+    return null;
+  }
+
+  public Address getBaseOfStackPointer(Address addr) {
+    return null;
+  }
+
+  public Frame getLastFramePD(JavaThread thread, Address addr) {
+    Address fp = thread.getLastJavaFP();
+    if (fp == null) {
+      return null; // no information
+    }
+    return new AARCH64Frame(thread.getLastJavaSP(), fp);
+  }
+
+  public RegisterMap newRegisterMap(JavaThread thread, boolean updateMap) {
+    return new AARCH64RegisterMap(thread, updateMap);
+  }
+
+  public Frame getCurrentFrameGuess(JavaThread thread, Address addr) {
+    ThreadProxy t = getThreadProxy(addr);
+    AARCH64ThreadContext context = (AARCH64ThreadContext) t.getContext();
+    AARCH64CurrentFrameGuess guesser = new AARCH64CurrentFrameGuess(context, thread);
+    if (!guesser.run(GUESS_SCAN_RANGE)) {
+      return null;
+    }
+    if (guesser.getPC() == null) {
+      return new AARCH64Frame(guesser.getSP(), guesser.getFP());
+    } else {
+      return new AARCH64Frame(guesser.getSP(), guesser.getFP(), guesser.getPC());
+    }
+  }
+
+  public void printThreadIDOn(Address addr, PrintStream tty) {
+    tty.print(getThreadProxy(addr));
+  }
+
+  public void printInfoOn(Address threadAddr, PrintStream tty) {
+    tty.print("Thread id: ");
+    printThreadIDOn(threadAddr, tty);
+//    tty.println("\nPostJavaState: " + getPostJavaState(threadAddr));
+  }
+
+  public Address getLastSP(Address addr) {
+    ThreadProxy t = getThreadProxy(addr);
+    AARCH64ThreadContext context = (AARCH64ThreadContext) t.getContext();
+    return context.getRegisterAsAddress(AARCH64ThreadContext.SP);
+  }
+
+  public ThreadProxy getThreadProxy(Address addr) {
+    // Addr is the address of the JavaThread.
+    // Fetch the OSThread (for now and for simplicity, not making a
+    // separate "OSThread" class in this package)
+    Address osThreadAddr = osThreadField.getValue(addr);
+    // Get the address of the _thread_id from the OSThread
+    Address threadIdAddr = osThreadAddr.addOffsetTo(osThreadThreadIDField.getOffset());
+
+    JVMDebugger debugger = VM.getVM().getDebugger();
+    return debugger.getThreadForIdentifierAddress(threadIdAddr);
+  }
+}