/*

 * Copyright 2003-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 *

 */

#include "incls/_precompiled.incl"

#include "incls/_thread_solaris_sparc.cpp.incl"

// For Forte Analyzer AsyncGetCallTrace profiling support - thread is

// currently interrupted by SIGPROF

//

// NOTE: On Solaris, register windows are flushed in the signal handler

// except for possibly the top frame.

//

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::Solaris::fetch_frame_from_ucontext(this, uc,

    &ret_sp, NULL /* ret_fp only used on Solaris X86 */);

  if (addr.pc() == NULL || ret_sp == NULL) {

    // ucontext wasn't useful

    return false;

  }

  frame ret_frame(ret_sp, frame::unpatchable, addr.pc());

  // we were running Java code when SIGPROF came in

  if (isInJava) {

    // If the frame we got is safe then it is most certainly valid

    if (ret_frame.safe_for_sender(jt)) {

      *fr_addr = ret_frame;

      return true;

    }

    // If it isn't safe then we can try several things to try and get

    // a good starting point.

    //

    // On sparc the frames are almost certainly walkable in the sense

    // of sp/fp linkages. However because of recycling of windows if

    // a piece of code does multiple save's where the initial save creates

    // a real frame with a return pc and the succeeding save's are used to

    // simply get free registers and have no real pc then the pc linkage on these

    // "inner" temporary frames will be bogus.

    // Since there is in general only a nesting level like

    // this one deep in general we'll try and unwind such an "inner" frame

    // here ourselves and see if it makes sense

    frame unwind_frame(ret_frame.fp(), frame::unpatchable, addr.pc());

    if (unwind_frame.safe_for_sender(jt)) {

      *fr_addr = unwind_frame;

      return true;

    }

    // Well that didn't work. Most likely we're toast on this tick

    // The previous code would try this. I think it is dubious in light

    // of changes to safe_for_sender and the unwind trick above but

    // if it gets us a safe frame who wants to argue.

    // 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();

      frame ret_frame2(ret_sp, frame::unpatchable, addr.pc());

      if (ret_frame2.safe_for_sender(jt)) {

        *fr_addr = ret_frame2;

        return true;

      }

    }

    // This is the best we can do. We will only be able to decode the top frame

    *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");

    frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());

    *fr_addr = ret_frame;

    return true;

  }

  // nothing else to try but what we found initially

  *fr_addr = ret_frame;

  return true;

}