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Java example source code file (thread_linux_sparc.cpp)

This example Java source code file (thread_linux_sparc.cpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

extendedpc, javathread, javathread::cache_global_variables, javathread::pd_get_top_frame_for_signal_handler, null, x86

The thread_linux_sparc.cpp Java example source code

/*
 * Copyright (c) 2003, 2010, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "runtime/frame.inline.hpp"
#include "runtime/thread.inline.hpp"

// For Forte Analyzer AsyncGetCallTrace profiling support - thread is
// currently interrupted by SIGPROF
bool JavaThread::pd_get_top_frame_for_signal_handler(frame* fr_addr,
                                                     void* ucontext,
                                                     bool isInJava) {
  assert(Thread::current() == this, "caller must be current thread");
  assert(this->is_Java_thread(), "must be JavaThread");

  JavaThread* jt = (JavaThread *)this;

  if (!isInJava) {
    // make_walkable flushes register windows and grabs last_Java_pc
    // which can not be done if the ucontext sp matches last_Java_sp
    // stack walking utilities assume last_Java_pc set if marked flushed
    jt->frame_anchor()->make_walkable(jt);
  }

  // If we have a walkable last_Java_frame, then we should use it
  // even if isInJava == true. It should be more reliable than
  // ucontext info.
  if (jt->has_last_Java_frame() && jt->frame_anchor()->walkable()) {
    *fr_addr = jt->pd_last_frame();
    return true;
  }

  ucontext_t* uc = (ucontext_t*) ucontext;

  // At this point, we don't have a walkable last_Java_frame, so
  // we try to glean some information out of the ucontext.
  intptr_t* ret_sp;
  ExtendedPC addr =
    os::fetch_frame_from_context(uc, &ret_sp,
                                 NULL /* ret_fp only used on X86 */);
  if (addr.pc() == NULL || ret_sp == NULL) {
    // ucontext wasn't useful
    return false;
  }

  // we were running Java code when SIGPROF came in
  if (isInJava) {
    // If we have a last_Java_sp, then the SIGPROF signal caught us
    // right when we were transitioning from _thread_in_Java to a new
    // JavaThreadState. We use last_Java_sp instead of the sp from
    // the ucontext since it should be more reliable.
    if (jt->has_last_Java_frame()) {
      ret_sp = jt->last_Java_sp();
    }
    // Implied else: we don't have a last_Java_sp so we use what we
    // got from the ucontext.

    frame ret_frame(ret_sp, frame::unpatchable, addr.pc());
    if (!ret_frame.safe_for_sender(jt)) {
      // nothing else to try if the frame isn't good
      return false;
    }
    *fr_addr = ret_frame;
    return true;
  }

  // At this point, we know we weren't running Java code. We might
  // have a last_Java_sp, but we don't have a walkable frame.
  // However, we might still be able to construct something useful
  // if the thread was running native code.
  if (jt->has_last_Java_frame()) {
    assert(!jt->frame_anchor()->walkable(), "case covered above");

    if (jt->thread_state() == _thread_in_native) {
      frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());
      if (!ret_frame.safe_for_sender(jt)) {
        // nothing else to try if the frame isn't good
        return false;
      }
      *fr_addr = ret_frame;
      return true;
    }
  }

  // nothing else to try
  return false;
}

void JavaThread::cache_global_variables() { }

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