--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/prims/forte.cpp	Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,895 @@
+/*
+ * Copyright 2003-2007 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/_forte.cpp.incl"
+
+
+//-------------------------------------------------------
+
+// Native interfaces for use by Forte tools.
+
+
+#ifndef IA64
+
+class vframeStreamForte : public vframeStreamCommon {
+ public:
+  // constructor that starts with sender of frame fr (top_frame)
+  vframeStreamForte(JavaThread *jt, frame fr, bool stop_at_java_call_stub);
+  void forte_next();
+};
+
+
+static void forte_is_walkable_compiled_frame(frame* fr, RegisterMap* map,
+  bool* is_compiled_p, bool* is_walkable_p);
+static bool forte_is_walkable_interpreted_frame(frame* fr,
+  methodOop* method_p, int* bci_p);
+
+
+// A Forte specific version of frame:safe_for_sender().
+static bool forte_safe_for_sender(frame* fr, JavaThread *thread) {
+  bool ret_value = false;  // be pessimistic
+
+#ifdef COMPILER2
+#if defined(IA32) || defined(AMD64)
+  {
+    // This check is the same as the standard safe_for_sender()
+    // on IA32 or AMD64 except that NULL FP values are tolerated
+    // for C2.
+    address   sp = (address)fr->sp();
+    address   fp = (address)fr->fp();
+    ret_value = sp != NULL && sp <= thread->stack_base() &&
+      sp >= thread->stack_base() - thread->stack_size() &&
+      (fp == NULL || (fp <= thread->stack_base() &&
+      fp >= thread->stack_base() - thread->stack_size()));
+
+    // We used to use standard safe_for_sender() when we are supposed
+    // to be executing Java code. However, that prevents us from
+    // walking some intrinsic stacks so now we have to be more refined.
+    // If we passed the above check and we have a NULL frame pointer
+    // and we are supposed to be executing Java code, then we have a
+    // couple of more checks to make.
+    if (ret_value && fp == NULL && (thread->thread_state() == _thread_in_Java
+        || thread->thread_state() == _thread_in_Java_trans)) {
+
+      if (fr->is_interpreted_frame()) {
+        // interpreted frames don't really have a NULL frame pointer
+        return false;
+      } else if (CodeCache::find_blob(fr->pc()) == NULL) {
+        // the NULL frame pointer should be associated with generated code
+        return false;
+      }
+    }
+  }
+
+#else // !(IA32 || AMD64)
+  ret_value = fr->safe_for_sender(thread);
+#endif // IA32 || AMD64
+
+#else // !COMPILER2
+  ret_value = fr->safe_for_sender(thread);
+#endif // COMPILER2
+
+  if (!ret_value) {
+    return ret_value;  // not safe, nothing more to do
+  }
+
+  address sp1;
+
+#ifdef SPARC
+  // On Solaris SPARC, when a compiler frame has an interpreted callee
+  // the _interpreter_sp_adjustment field contains the adjustment to
+  // this frame's SP made by that interpreted callee.
+  // For AsyncGetCallTrace(), we need to verify that the resulting SP
+  // is valid for the specified thread's stack.
+  sp1 = (address)fr->sp();
+  address sp2 = (address)fr->unextended_sp();
+
+  // If the second SP is NULL, then the _interpreter_sp_adjustment
+  // field simply adjusts this frame's SP to NULL and the frame is
+  // not safe. This strange value can be set in the frame constructor
+  // when our peek into the interpreted callee's adjusted value for
+  // this frame's SP finds a NULL. This can happen when SIGPROF
+  // catches us while we are creating the interpreter frame.
+  //
+  if (sp2 == NULL ||
+
+      // If the two SPs are different, then _interpreter_sp_adjustment
+      // is non-zero and we need to validate the second SP. We invert
+      // the range check from frame::safe_for_sender() and bail out
+      // if the second SP is not safe.
+      (sp1 != sp2 && !(sp2 <= thread->stack_base()
+      && sp2 >= (thread->stack_base() - thread->stack_size())))) {
+    return false;
+  }
+#endif // SPARC
+
+  if (fr->is_entry_frame()) {
+    // This frame thinks it is an entry frame; we need to validate
+    // the JavaCallWrapper pointer.
+    // Note: frame::entry_frame_is_first() assumes that the
+    // JavaCallWrapper has a non-NULL _anchor field. We don't
+    // check that here (yet) since we've never seen a failure
+    // due to a NULL _anchor field.
+    // Update: Originally this check was done only for SPARC. However,
+    // this failure has now been seen on C2 C86. I have no reason to
+    // believe that this is not a general issue so I'm enabling the
+    // check for all compilers on all supported platforms.
+#ifdef COMPILER2
+#if defined(IA32) || defined(AMD64)
+    if (fr->fp() == NULL) {
+      // C2 X86 allows NULL frame pointers, but if we have one then
+      // we cannot call entry_frame_call_wrapper().
+      return false;
+    }
+#endif // IA32 || AMD64
+#endif // COMPILER2
+
+    sp1 = (address)fr->entry_frame_call_wrapper();
+    // We invert the range check from frame::safe_for_sender() and
+    // bail out if the JavaCallWrapper * is not safe.
+    if (!(sp1 <= thread->stack_base()
+        && sp1 >= (thread->stack_base() - thread->stack_size()))) {
+      return false;
+    }
+  }
+
+  return ret_value;
+}
+
+
+// Unknown compiled frames have caused assertion failures on Solaris
+// X86. This code also detects unknown compiled frames on Solaris
+// SPARC, but no assertion failures have been observed. However, I'm
+// paranoid so I'm enabling this code whenever we have a compiler.
+//
+// Returns true if the specified frame is an unknown compiled frame
+// and false otherwise.
+static bool is_unknown_compiled_frame(frame* fr, JavaThread *thread) {
+  bool ret_value = false;  // be optimistic
+
+  // This failure mode only occurs when the thread is in state
+  // _thread_in_Java so we are okay for this check for any other
+  // thread state.
+  //
+  // Note: _thread_in_Java does not always mean that the thread
+  // is executing Java code. AsyncGetCallTrace() has caught
+  // threads executing in JRT_LEAF() routines when the state
+  // will also be _thread_in_Java.
+  if (thread->thread_state() != _thread_in_Java) {
+    return ret_value;
+  }
+
+  // This failure mode only occurs with compiled frames so we are
+  // okay for this check for both entry and interpreted frames.
+  if (fr->is_entry_frame() || fr->is_interpreted_frame()) {
+    return ret_value;
+  }
+
+  // This failure mode only occurs when the compiled frame's PC
+  // is in the code cache so we are okay for this check if the
+  // PC is not in the code cache.
+  CodeBlob* cb = CodeCache::find_blob(fr->pc());
+  if (cb == NULL) {
+    return ret_value;
+  }
+
+  // We have compiled code in the code cache so it is time for
+  // the final check: let's see if any frame type is set
+  ret_value = !(
+    // is_entry_frame() is checked above
+    // testers that are a subset of is_entry_frame():
+    //   is_first_frame()
+    fr->is_java_frame()
+    // testers that are a subset of is_java_frame():
+    //   is_interpreted_frame()
+    //   is_compiled_frame()
+    || fr->is_native_frame()
+    || fr->is_runtime_frame()
+    || fr->is_safepoint_blob_frame()
+    );
+
+  // If there is no frame type set, then we have an unknown compiled
+  // frame and sender() should not be called on it.
+
+  return ret_value;
+}
+
+#define DebugNonSafepoints_IS_CLEARED \
+  (!FLAG_IS_DEFAULT(DebugNonSafepoints) && !DebugNonSafepoints)
+
+// if -XX:-DebugNonSafepoints, then top-frame will be skipped
+vframeStreamForte::vframeStreamForte(JavaThread *jt, frame fr,
+  bool stop_at_java_call_stub) : vframeStreamCommon(jt) {
+  _stop_at_java_call_stub = stop_at_java_call_stub;
+
+  if (!DebugNonSafepoints_IS_CLEARED) {
+    // decode the top frame fully
+    // (usual case, if JVMTI is enabled)
+    _frame = fr;
+  } else {
+    // skip top frame, as it may not be at safepoint
+    // For AsyncGetCallTrace(), we extracted as much info from the top
+    // frame as we could in forte_is_walkable_frame(). We also verified
+    // forte_safe_for_sender() so this sender() call is safe.
+    _frame  = fr.sender(&_reg_map);
+  }
+
+  if (jt->thread_state() == _thread_in_Java && !fr.is_first_frame()) {
+    bool sender_check = false;  // assume sender is not safe
+
+    if (forte_safe_for_sender(&_frame, jt)) {
+      // If the initial sender frame is safe, then continue on with other
+      // checks. The unsafe sender frame has been seen on Solaris X86
+      // with both Compiler1 and Compiler2. It has not been seen on
+      // Solaris SPARC, but seems like a good sanity check to have
+      // anyway.
+
+      // SIGPROF caught us in Java code and the current frame is not the
+      // first frame so we should sanity check the sender frame. It is
+      // possible for SIGPROF to catch us in the middle of making a call.
+      // When that happens the current frame is actually a combination of
+      // the real sender and some of the new call's info. We can't find
+      // the real sender with such a current frame and things can get
+      // confused.
+      //
+      // This sanity check has caught problems with the sender frame on
+      // Solaris SPARC. So far Solaris X86 has not had a failure here.
+      sender_check = _frame.is_entry_frame()
+        // testers that are a subset of is_entry_frame():
+        //   is_first_frame()
+        || _frame.is_java_frame()
+        // testers that are a subset of is_java_frame():
+        //   is_interpreted_frame()
+        //   is_compiled_frame()
+        || _frame.is_native_frame()
+        || _frame.is_runtime_frame()
+        || _frame.is_safepoint_blob_frame()
+        ;
+
+      // We need an additional sanity check on an initial interpreted
+      // sender frame. This interpreted frame needs to be both walkable
+      // and have a valid BCI. This is yet another variant of SIGPROF
+      // catching us in the middle of making a call.
+      if (sender_check && _frame.is_interpreted_frame()) {
+        methodOop method = NULL;
+        int bci = -1;
+
+        if (!forte_is_walkable_interpreted_frame(&_frame, &method, &bci)
+            || bci == -1) {
+          sender_check = false;
+        }
+      }
+
+      // We need an additional sanity check on an initial compiled
+      // sender frame. This compiled frame also needs to be walkable.
+      // This is yet another variant of SIGPROF catching us in the
+      // middle of making a call.
+      if (sender_check && !_frame.is_interpreted_frame()) {
+        bool is_compiled, is_walkable;
+
+        forte_is_walkable_compiled_frame(&_frame, &_reg_map,
+          &is_compiled, &is_walkable);
+        if (is_compiled && !is_walkable) {
+          sender_check = false;
+        }
+      }
+    }
+
+    if (!sender_check) {
+      // nothing else to try if we can't recognize the sender
+      _mode = at_end_mode;
+      return;
+    }
+  }
+
+  int loop_count = 0;
+  int loop_max = MaxJavaStackTraceDepth * 2;
+
+  while (!fill_from_frame()) {
+    _frame = _frame.sender(&_reg_map);
+
+#ifdef COMPILER2
+#if defined(IA32) || defined(AMD64)
+    // Stress testing on C2 X86 has shown a periodic problem with
+    // the sender() call below. The initial _frame that we have on
+    // entry to the loop has already passed forte_safe_for_sender()
+    // so we only check frames after it.
+    if (!forte_safe_for_sender(&_frame, _thread)) {
+      _mode = at_end_mode;
+      return;
+    }
+#endif // IA32 || AMD64
+#endif // COMPILER2
+
+    if (++loop_count >= loop_max) {
+      // We have looped more than twice the number of possible
+      // Java frames. This indicates that we are trying to walk
+      // a stack that is in the middle of being constructed and
+      // it is self referential.
+      _mode = at_end_mode;
+      return;
+    }
+  }
+}
+
+
+// Solaris SPARC Compiler1 needs an additional check on the grandparent
+// of the top_frame when the parent of the top_frame is interpreted and
+// the grandparent is compiled. However, in this method we do not know
+// the relationship of the current _frame relative to the top_frame so
+// we implement a more broad sanity check. When the previous callee is
+// interpreted and the current sender is compiled, we verify that the
+// current sender is also walkable. If it is not walkable, then we mark
+// the current vframeStream as at the end.
+void vframeStreamForte::forte_next() {
+  // handle frames with inlining
+  if (_mode == compiled_mode &&
+      vframeStreamCommon::fill_in_compiled_inlined_sender()) {
+    return;
+  }
+
+  // handle general case
+
+  int loop_count = 0;
+  int loop_max = MaxJavaStackTraceDepth * 2;
+
+
+  do {
+
+#if defined(COMPILER1) && defined(SPARC)
+  bool prevIsInterpreted =  _frame.is_interpreted_frame();
+#endif // COMPILER1 && SPARC
+
+    _frame = _frame.sender(&_reg_map);
+
+    if (!forte_safe_for_sender(&_frame, _thread)) {
+      _mode = at_end_mode;
+      return;
+    }
+
+#if defined(COMPILER1) && defined(SPARC)
+    if (prevIsInterpreted) {
+      // previous callee was interpreted and may require a special check
+      if (_frame.is_compiled_frame() && _frame.cb()->is_compiled_by_c1()) {
+        // compiled sender called interpreted callee so need one more check
+        bool is_compiled, is_walkable;
+
+        // sanity check the compiled sender frame
+        forte_is_walkable_compiled_frame(&_frame, &_reg_map,
+          &is_compiled, &is_walkable);
+        assert(is_compiled, "sanity check");
+        if (!is_walkable) {
+          // compiled sender frame is not walkable so bail out
+          _mode = at_end_mode;
+          return;
+        }
+      }
+    }
+#endif // COMPILER1 && SPARC
+
+    if (++loop_count >= loop_max) {
+      // We have looped more than twice the number of possible
+      // Java frames. This indicates that we are trying to walk
+      // a stack that is in the middle of being constructed and
+      // it is self referential.
+      _mode = at_end_mode;
+      return;
+    }
+  } while (!fill_from_frame());
+}
+
+// Determine if 'fr' is a walkable, compiled frame.
+// *is_compiled_p is set to true if the frame is compiled and if it
+// is, then *is_walkable_p is set to true if it is also walkable.
+static void forte_is_walkable_compiled_frame(frame* fr, RegisterMap* map,
+  bool* is_compiled_p, bool* is_walkable_p) {
+
+  *is_compiled_p = false;
+  *is_walkable_p = false;
+
+  CodeBlob* cb = CodeCache::find_blob(fr->pc());
+  if (cb != NULL &&
+      cb->is_nmethod() &&
+      ((nmethod*)cb)->is_java_method()) {
+    // frame is compiled and executing a Java method
+    *is_compiled_p = true;
+
+    // Increment PC because the PcDesc we want is associated with
+    // the *end* of the instruction, and pc_desc_near searches
+    // forward to the first matching PC after the probe PC.
+    PcDesc* pc_desc = NULL;
+    if (!DebugNonSafepoints_IS_CLEARED) {
+      // usual case:  look for any safepoint near the sampled PC
+      address probe_pc = fr->pc() + 1;
+      pc_desc = ((nmethod*) cb)->pc_desc_near(probe_pc);
+    } else {
+      // reduced functionality:  only recognize PCs immediately after calls
+      pc_desc = ((nmethod*) cb)->pc_desc_at(fr->pc());
+    }
+    if (pc_desc != NULL && (pc_desc->scope_decode_offset()
+                            == DebugInformationRecorder::serialized_null)) {
+      pc_desc = NULL;
+    }
+    if (pc_desc != NULL) {
+      // it has a PcDesc so the frame is also walkable
+      *is_walkable_p = true;
+      if (!DebugNonSafepoints_IS_CLEARED) {
+        // Normalize the PC to the one associated exactly with
+        // this PcDesc, so that subsequent stack-walking queries
+        // need not be approximate:
+        fr->set_pc(pc_desc->real_pc((nmethod*) cb));
+      }
+    }
+    // Implied else: this compiled frame has no PcDesc, i.e., contains
+    // a frameless stub such as C1 method exit, so it is not walkable.
+  }
+  // Implied else: this isn't a compiled frame so it isn't a
+  // walkable, compiled frame.
+}
+
+// Determine if 'fr' is a walkable interpreted frame. Returns false
+// if it is not. *method_p, and *bci_p are not set when false is
+// returned. *method_p is non-NULL if frame was executing a Java
+// method. *bci_p is != -1 if a valid BCI in the Java method could
+// be found.
+// Note: this method returns true when a valid Java method is found
+// even if a valid BCI cannot be found.
+
+static bool forte_is_walkable_interpreted_frame(frame* fr,
+  methodOop* method_p, int* bci_p) {
+  assert(fr->is_interpreted_frame(), "just checking");
+
+  // top frame is an interpreted frame
+  // check if it is walkable (i.e. valid methodOop and valid bci)
+  if (fr->is_interpreted_frame_valid()) {
+    if (fr->fp() != NULL) {
+      // access address in order not to trigger asserts that
+      // are built in interpreter_frame_method function
+      methodOop method = *fr->interpreter_frame_method_addr();
+      if (Universe::heap()->is_valid_method(method)) {
+        intptr_t bcx = fr->interpreter_frame_bcx();
+        int      bci = method->validate_bci_from_bcx(bcx);
+        // note: bci is set to -1 if not a valid bci
+        *method_p = method;
+        *bci_p = bci;
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+
+// Determine if 'fr' can be used to find a walkable frame. Returns
+// false if a walkable frame cannot be found. *walkframe_p, *method_p,
+// and *bci_p are not set when false is returned. Returns true if a
+// walkable frame is returned via *walkframe_p. *method_p is non-NULL
+// if the returned frame was executing a Java method. *bci_p is != -1
+// if a valid BCI in the Java method could be found.
+//
+// *walkframe_p will be used by vframeStreamForte as the initial
+// frame for walking the stack. Currently the initial frame is
+// skipped by vframeStreamForte because we inherited the logic from
+// the vframeStream class. This needs to be revisited in the future.
+static bool forte_is_walkable_frame(JavaThread* thread, frame* fr,
+  frame* walkframe_p, methodOop* method_p, int* bci_p) {
+
+  if (!forte_safe_for_sender(fr, thread)
+      || is_unknown_compiled_frame(fr, thread)
+     ) {
+    // If the initial frame is not safe, then bail out. So far this
+    // has only been seen on Solaris X86 with Compiler2, but it seems
+    // like a great initial sanity check.
+    return false;
+  }
+
+  if (fr->is_first_frame()) {
+    // If initial frame is frame from StubGenerator and there is no
+    // previous anchor, there are no java frames yet
+    return false;
+  }
+
+  if (fr->is_interpreted_frame()) {
+    if (forte_is_walkable_interpreted_frame(fr, method_p, bci_p)) {
+      *walkframe_p = *fr;
+      return true;
+    }
+    return false;
+  }
+
+  // At this point we have something other than a first frame or an
+  // interpreted frame.
+
+  methodOop method = NULL;
+  frame candidate = *fr;
+
+  // If we loop more than twice the number of possible Java
+  // frames, then this indicates that we are trying to walk
+  // a stack that is in the middle of being constructed and
+  // it is self referential. So far this problem has only
+  // been seen on Solaris X86 Compiler2, but it seems like
+  // a good robustness fix for all platforms.
+
+  int loop_count;
+  int loop_max = MaxJavaStackTraceDepth * 2;
+
+  for (loop_count = 0; loop_count < loop_max; loop_count++) {
+    // determine if the candidate frame is executing a Java method
+    if (CodeCache::contains(candidate.pc())) {
+      // candidate is a compiled frame or stub routine
+      CodeBlob* cb = CodeCache::find_blob(candidate.pc());
+
+      if (cb->is_nmethod()) {
+        method = ((nmethod *)cb)->method();
+      }
+    } // end if CodeCache has our PC
+
+    RegisterMap map(thread, false);
+
+    // we have a Java frame that seems reasonable
+    if (method != NULL && candidate.is_java_frame()
+        && candidate.sp() != NULL && candidate.pc() != NULL) {
+      // we need to sanity check the candidate further
+      bool is_compiled, is_walkable;
+
+      forte_is_walkable_compiled_frame(&candidate, &map, &is_compiled,
+        &is_walkable);
+      if (is_compiled) {
+        // At this point, we know we have a compiled Java frame with
+        // method information that we want to return. We don't check
+        // the is_walkable flag here because that flag pertains to
+        // vframeStreamForte work that is done after we are done here.
+        break;
+      }
+    }
+
+    // At this point, the candidate doesn't work so try the sender.
+
+    // For AsyncGetCallTrace() we cannot assume there is a sender
+    // for the initial frame. The initial forte_safe_for_sender() call
+    // and check for is_first_frame() is done on entry to this method.
+    candidate = candidate.sender(&map);
+    if (!forte_safe_for_sender(&candidate, thread)) {
+
+#ifdef COMPILER2
+#if defined(IA32) || defined(AMD64)
+      // C2 on X86 can use the ebp register as a general purpose register
+      // which can cause the candidate to fail theforte_safe_for_sender()
+      // above. We try one more time using a NULL frame pointer (fp).
+
+      candidate = frame(candidate.sp(), NULL, candidate.pc());
+      if (!forte_safe_for_sender(&candidate, thread)) {
+#endif // IA32 || AMD64
+#endif // COMPILER2
+
+        return false;
+
+#ifdef COMPILER2
+#if defined(IA32) || defined(AMD64)
+      } // end forte_safe_for_sender retry with NULL fp
+#endif // IA32 || AMD64
+#endif // COMPILER2
+
+    } // end first forte_safe_for_sender check
+
+    if (candidate.is_first_frame()
+        || is_unknown_compiled_frame(&candidate, thread)) {
+      return false;
+    }
+  } // end for loop_count
+
+  if (method == NULL) {
+    // If we didn't get any method info from the candidate, then
+    // we have nothing to return so bail out.
+    return false;
+  }
+
+  *walkframe_p = candidate;
+  *method_p = method;
+  *bci_p = -1;
+  return true;
+}
+
+
+// call frame copied from old .h file and renamed
+typedef struct {
+    jint lineno;                      // line number in the source file
+    jmethodID method_id;              // method executed in this frame
+} ASGCT_CallFrame;
+
+// call trace copied from old .h file and renamed
+typedef struct {
+    JNIEnv *env_id;                   // Env where trace was recorded
+    jint num_frames;                  // number of frames in this trace
+    ASGCT_CallFrame *frames;          // frames
+} ASGCT_CallTrace;
+
+static void forte_fill_call_trace_given_top(JavaThread* thd,
+  ASGCT_CallTrace* trace, int depth, frame top_frame) {
+  NoHandleMark nhm;
+
+  frame walkframe;
+  methodOop method;
+  int bci;
+  int count;
+
+  count = 0;
+  assert(trace->frames != NULL, "trace->frames must be non-NULL");
+
+  if (!forte_is_walkable_frame(thd, &top_frame, &walkframe, &method, &bci)) {
+    // return if no walkable frame is found
+    return;
+  }
+
+  CollectedHeap* ch = Universe::heap();
+
+  if (method != NULL) {
+    // The method is not stored GC safe so see if GC became active
+    // after we entered AsyncGetCallTrace() and before we try to
+    // use the methodOop.
+    // Yes, there is still a window after this check and before
+    // we use methodOop below, but we can't lock out GC so that
+    // has to be an acceptable risk.
+    if (!ch->is_valid_method(method)) {
+      trace->num_frames = -2;
+      return;
+    }
+
+    if (DebugNonSafepoints_IS_CLEARED) {
+      // Take whatever method the top-frame decoder managed to scrape up.
+      // We look further at the top frame only if non-safepoint
+      // debugging information is available.
+      count++;
+      trace->num_frames = count;
+      trace->frames[0].method_id = method->find_jmethod_id_or_null();
+      if (!method->is_native()) {
+        trace->frames[0].lineno = bci;
+      } else {
+        trace->frames[0].lineno = -3;
+      }
+    }
+  }
+
+  // check has_last_Java_frame() after looking at the top frame
+  // which may be an interpreted Java frame.
+  if (!thd->has_last_Java_frame() && method == NULL) {
+    trace->num_frames = 0;
+    return;
+  }
+
+  vframeStreamForte st(thd, walkframe, false);
+  for (; !st.at_end() && count < depth; st.forte_next(), count++) {
+    bci = st.bci();
+    method = st.method();
+
+    // The method is not stored GC safe so see if GC became active
+    // after we entered AsyncGetCallTrace() and before we try to
+    // use the methodOop.
+    // Yes, there is still a window after this check and before
+    // we use methodOop below, but we can't lock out GC so that
+    // has to be an acceptable risk.
+    if (!ch->is_valid_method(method)) {
+      // we throw away everything we've gathered in this sample since
+      // none of it is safe
+      trace->num_frames = -2;
+      return;
+    }
+
+    trace->frames[count].method_id = method->find_jmethod_id_or_null();
+    if (!method->is_native()) {
+      trace->frames[count].lineno = bci;
+    } else {
+      trace->frames[count].lineno = -3;
+    }
+  }
+  trace->num_frames = count;
+  return;
+}
+
+
+// Forte Analyzer AsyncGetCallTrace() entry point. Currently supported
+// on Linux X86, Solaris SPARC and Solaris X86.
+//
+// Async-safe version of GetCallTrace being called from a signal handler
+// when a LWP gets interrupted by SIGPROF but the stack traces are filled
+// with different content (see below).
+//
+// This function must only be called when JVM/TI
+// CLASS_LOAD events have been enabled since agent startup. The enabled
+// event will cause the jmethodIDs to be allocated at class load time.
+// The jmethodIDs cannot be allocated in a signal handler because locks
+// cannot be grabbed in a signal handler safely.
+//
+// void (*AsyncGetCallTrace)(ASGCT_CallTrace *trace, jint depth, void* ucontext)
+//
+// Called by the profiler to obtain the current method call stack trace for
+// a given thread. The thread is identified by the env_id field in the
+// ASGCT_CallTrace structure. The profiler agent should allocate a ASGCT_CallTrace
+// structure with enough memory for the requested stack depth. The VM fills in
+// the frames buffer and the num_frames field.
+//
+// Arguments:
+//
+//   trace    - trace data structure to be filled by the VM.
+//   depth    - depth of the call stack trace.
+//   ucontext - ucontext_t of the LWP
+//
+// ASGCT_CallTrace:
+//   typedef struct {
+//       JNIEnv *env_id;
+//       jint num_frames;
+//       ASGCT_CallFrame *frames;
+//   } ASGCT_CallTrace;
+//
+// Fields:
+//   env_id     - ID of thread which executed this trace.
+//   num_frames - number of frames in the trace.
+//                (< 0 indicates the frame is not walkable).
+//   frames     - the ASGCT_CallFrames that make up this trace. Callee followed by callers.
+//
+//  ASGCT_CallFrame:
+//    typedef struct {
+//        jint lineno;
+//        jmethodID method_id;
+//    } ASGCT_CallFrame;
+//
+//  Fields:
+//    1) For Java frame (interpreted and compiled),
+//       lineno    - bci of the method being executed or -1 if bci is not available
+//       method_id - jmethodID of the method being executed
+//    2) For native method
+//       lineno    - (-3)
+//       method_id - jmethodID of the method being executed
+
+extern "C" {
+void AsyncGetCallTrace(ASGCT_CallTrace *trace, jint depth, void* ucontext) {
+  if (SafepointSynchronize::is_synchronizing()) {
+    // The safepoint mechanism is trying to synchronize all the threads.
+    // Since this can involve thread suspension, it is not safe for us
+    // to be here. We can reduce the deadlock risk window by quickly
+    // returning to the SIGPROF handler. However, it is still possible
+    // for VMThread to catch us here or in the SIGPROF handler. If we
+    // are suspended while holding a resource and another thread blocks
+    // on that resource in the SIGPROF handler, then we will have a
+    // three-thread deadlock (VMThread, this thread, the other thread).
+    trace->num_frames = -10;
+    return;
+  }
+
+  JavaThread* thread;
+
+  if (trace->env_id == NULL ||
+    (thread = JavaThread::thread_from_jni_environment(trace->env_id)) == NULL ||
+    thread->is_exiting()) {
+
+    // bad env_id, thread has exited or thread is exiting
+    trace->num_frames = -8;
+    return;
+  }
+
+  if (thread->in_deopt_handler()) {
+    // thread is in the deoptimization handler so return no frames
+    trace->num_frames = -9;
+    return;
+  }
+
+  assert(JavaThread::current() == thread,
+         "AsyncGetCallTrace must be called by the current interrupted thread");
+
+  if (!JvmtiExport::should_post_class_load()) {
+    trace->num_frames = -1;
+    return;
+  }
+
+  if (Universe::heap()->is_gc_active()) {
+    trace->num_frames = -2;
+    return;
+  }
+
+  switch (thread->thread_state()) {
+  case _thread_new:
+  case _thread_uninitialized:
+  case _thread_new_trans:
+    // We found the thread on the threads list above, but it is too
+    // young to be useful so return that there are no Java frames.
+    trace->num_frames = 0;
+    break;
+  case _thread_in_native:
+  case _thread_in_native_trans:
+  case _thread_blocked:
+  case _thread_blocked_trans:
+  case _thread_in_vm:
+  case _thread_in_vm_trans:
+    {
+      frame fr;
+
+      // param isInJava == false - indicate we aren't in Java code
+      if (!thread->pd_get_top_frame_for_signal_handler(&fr, ucontext, false)) {
+        if (!thread->has_last_Java_frame()) {
+          trace->num_frames = 0;   // no Java frames
+        } else {
+          trace->num_frames = -3;  // unknown frame
+        }
+      } else {
+        trace->num_frames = -4;    // non walkable frame by default
+        forte_fill_call_trace_given_top(thread, trace, depth, fr);
+      }
+    }
+    break;
+  case _thread_in_Java:
+  case _thread_in_Java_trans:
+    {
+      frame fr;
+
+      // param isInJava == true - indicate we are in Java code
+      if (!thread->pd_get_top_frame_for_signal_handler(&fr, ucontext, true)) {
+        trace->num_frames = -5;  // unknown frame
+      } else {
+        trace->num_frames = -6;  // non walkable frame by default
+        forte_fill_call_trace_given_top(thread, trace, depth, fr);
+      }
+    }
+    break;
+  default:
+    // Unknown thread state
+    trace->num_frames = -7;
+    break;
+  }
+}
+
+
+#ifndef _WINDOWS
+// Support for the Forte(TM) Peformance Tools collector.
+//
+// The method prototype is derived from libcollector.h. For more
+// information, please see the libcollect man page.
+
+// Method to let libcollector know about a dynamically loaded function.
+// Because it is weakly bound, the calls become NOP's when the library
+// isn't present.
+void    collector_func_load(char* name,
+                            void* null_argument_1,
+                            void* null_argument_2,
+                            void *vaddr,
+                            int size,
+                            int zero_argument,
+                            void* null_argument_3);
+#pragma weak collector_func_load
+#define collector_func_load(x0,x1,x2,x3,x4,x5,x6) \
+        ( collector_func_load ? collector_func_load(x0,x1,x2,x3,x4,x5,x6),0 : 0 )
+#endif // !_WINDOWS
+
+} // end extern "C"
+#endif // !IA64
+
+void Forte::register_stub(const char* name, address start, address end) {
+#if !defined(_WINDOWS) && !defined(IA64)
+  assert(pointer_delta(end, start, sizeof(jbyte)) < INT_MAX,
+    "Code size exceeds maximum range")
+
+  collector_func_load((char*)name, NULL, NULL, start,
+    pointer_delta(end, start, sizeof(jbyte)), 0, NULL);
+#endif // !_WINDOWS && !IA64
+}