1 /*
   2  * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "memory/metaspaceShared.hpp"
  27 #include "runtime/frame.inline.hpp"
  28 #include "runtime/thread.inline.hpp"
  29 
  30 // For Forte Analyzer AsyncGetCallTrace profiling support - thread is
  31 // currently interrupted by SIGPROF
  32 bool JavaThread::pd_get_top_frame_for_signal_handler(frame* fr_addr,
  33                                                      void* ucontext,
  34                                                      bool isInJava) {
  35   assert(Thread::current() == this, "caller must be current thread");
  36   assert(this->is_Java_thread(), "must be JavaThread");
  37 
  38   JavaThread* jt = (JavaThread *)this;
  39 
  40   if (!isInJava) {
  41     // make_walkable flushes register windows and grabs last_Java_pc
  42     // which can not be done if the ucontext sp matches last_Java_sp
  43     // stack walking utilities assume last_Java_pc set if marked flushed
  44     jt->frame_anchor()->make_walkable(jt);
  45   }
  46 
  47   // If we have a walkable last_Java_frame, then we should use it
  48   // even if isInJava == true. It should be more reliable than
  49   // ucontext info.
  50   if (jt->has_last_Java_frame() && jt->frame_anchor()->walkable()) {
  51     *fr_addr = jt->pd_last_frame();
  52     return true;
  53   }
  54 
  55   ucontext_t* uc = (ucontext_t*) ucontext;
  56 
  57   // At this point, we don't have a walkable last_Java_frame, so
  58   // we try to glean some information out of the ucontext.
  59   intptr_t* ret_sp;
  60   ExtendedPC addr =
  61     os::fetch_frame_from_context(uc, &ret_sp,
  62                                  NULL /* ret_fp only used on X86 */);
  63   if (addr.pc() == NULL || ret_sp == NULL) {
  64     // ucontext wasn't useful
  65     return false;
  66   }
  67 
  68   if (MetaspaceShared::is_in_trampoline_frame(addr.pc())) {
  69     // In the middle of a trampoline call. Bail out for safety.
  70     // This happens rarely so shouldn't affect profiling.
  71     return false;
  72   }
  73 
  74   // we were running Java code when SIGPROF came in
  75   if (isInJava) {
  76     // If we have a last_Java_sp, then the SIGPROF signal caught us
  77     // right when we were transitioning from _thread_in_Java to a new
  78     // JavaThreadState. We use last_Java_sp instead of the sp from
  79     // the ucontext since it should be more reliable.
  80     if (jt->has_last_Java_frame()) {
  81       ret_sp = jt->last_Java_sp();
  82     }
  83     // Implied else: we don't have a last_Java_sp so we use what we
  84     // got from the ucontext.
  85 
  86     frame ret_frame(ret_sp, frame::unpatchable, addr.pc());
  87     if (!ret_frame.safe_for_sender(jt)) {
  88       // nothing else to try if the frame isn't good
  89       return false;
  90     }
  91     *fr_addr = ret_frame;
  92     return true;
  93   }
  94 
  95   // At this point, we know we weren't running Java code. We might
  96   // have a last_Java_sp, but we don't have a walkable frame.
  97   // However, we might still be able to construct something useful
  98   // if the thread was running native code.
  99   if (jt->has_last_Java_frame()) {
 100     assert(!jt->frame_anchor()->walkable(), "case covered above");
 101 
 102     if (jt->thread_state() == _thread_in_native) {
 103       frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());
 104       if (!ret_frame.safe_for_sender(jt)) {
 105         // nothing else to try if the frame isn't good
 106         return false;
 107       }
 108       *fr_addr = ret_frame;
 109       return true;
 110     }
 111   }
 112 
 113   // nothing else to try
 114   return false;
 115 }
 116 
 117 void JavaThread::cache_global_variables() { }
 118