1 /*
   2  * Copyright (c) 2003, 2013, 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 "runtime/frame.inline.hpp"
  27 #include "runtime/thread.inline.hpp"
  28 
  29 // For Forte Analyzer AsyncGetCallTrace profiling support - thread is
  30 // currently interrupted by SIGPROF
  31 //
  32 // NOTE: On Solaris, register windows are flushed in the signal handler
  33 // except for possibly the top frame.
  34 //
  35 bool JavaThread::pd_get_top_frame_for_signal_handler(frame* fr_addr,
  36   void* ucontext, bool isInJava) {
  37 
  38   assert(Thread::current() == this, "caller must be current thread");
  39   return pd_get_top_frame(fr_addr, ucontext, isInJava, true);
  40 }
  41 
  42 bool JavaThread::pd_get_top_frame_for_profiling(frame* fr_addr, void* ucontext, bool isInJava) {
  43   // get ucontext somehow
  44   return pd_get_top_frame(fr_addr, ucontext, isInJava, false);
  45 }
  46 
  47 bool JavaThread::pd_get_top_frame(frame* fr_addr,
  48   void* ucontext, bool isInJava, bool makeWalkable) {
  49   assert(this->is_Java_thread(), "must be JavaThread");
  50 
  51   JavaThread* jt = (JavaThread *)this;
  52 
  53   if (!isInJava && makeWalkable) {
  54     // make_walkable flushes register windows and grabs last_Java_pc
  55     // which can not be done if the ucontext sp matches last_Java_sp
  56     // stack walking utilities assume last_Java_pc set if marked flushed
  57     jt->frame_anchor()->make_walkable(jt);
  58   }
  59 
  60   // If we have a walkable last_Java_frame, then we should use it
  61   // even if isInJava == true. It should be more reliable than
  62   // ucontext info.
  63   if (jt->has_last_Java_frame() && jt->frame_anchor()->walkable()) {
  64     *fr_addr = jt->pd_last_frame();
  65     return true;
  66   }
  67 
  68   ucontext_t* uc = (ucontext_t*) ucontext;
  69 
  70   // At this point, we don't have a walkable last_Java_frame, so
  71   // we try to glean some information out of the ucontext.
  72   intptr_t* ret_sp;
  73   ExtendedPC addr = os::Solaris::fetch_frame_from_ucontext(this, uc,
  74     &ret_sp, NULL /* ret_fp only used on Solaris X86 */);
  75   if (addr.pc() == NULL || ret_sp == NULL) {
  76     // ucontext wasn't useful
  77     return false;
  78   }
  79 
  80   frame ret_frame(ret_sp, frame::unpatchable, addr.pc());
  81 
  82   // we were running Java code when SIGPROF came in
  83   if (isInJava) {
  84 
  85 
  86     // If the frame we got is safe then it is most certainly valid
  87     if (ret_frame.safe_for_sender(jt)) {
  88       *fr_addr = ret_frame;
  89       return true;
  90     }
  91 
  92     // If it isn't safe then we can try several things to try and get
  93     // a good starting point.
  94     //
  95     // On sparc the frames are almost certainly walkable in the sense
  96     // of sp/fp linkages. However because of recycling of windows if
  97     // a piece of code does multiple save's where the initial save creates
  98     // a real frame with a return pc and the succeeding save's are used to
  99     // simply get free registers and have no real pc then the pc linkage on these
 100     // "inner" temporary frames will be bogus.
 101     // Since there is in general only a nesting level like
 102     // this one deep in general we'll try and unwind such an "inner" frame
 103     // here ourselves and see if it makes sense
 104 
 105     frame unwind_frame(ret_frame.fp(), frame::unpatchable, addr.pc());
 106 
 107     if (unwind_frame.safe_for_sender(jt)) {
 108       *fr_addr = unwind_frame;
 109       return true;
 110     }
 111 
 112     // Well that didn't work. Most likely we're toast on this tick
 113     // The previous code would try this. I think it is dubious in light
 114     // of changes to safe_for_sender and the unwind trick above but
 115     // if it gets us a safe frame who wants to argue.
 116 
 117     // If we have a last_Java_sp, then the SIGPROF signal caught us
 118     // right when we were transitioning from _thread_in_Java to a new
 119     // JavaThreadState. We use last_Java_sp instead of the sp from
 120     // the ucontext since it should be more reliable.
 121 
 122     if (jt->has_last_Java_frame()) {
 123       ret_sp = jt->last_Java_sp();
 124       frame ret_frame2(ret_sp, frame::unpatchable, addr.pc());
 125       if (ret_frame2.safe_for_sender(jt)) {
 126         *fr_addr = ret_frame2;
 127         return true;
 128       }
 129     }
 130 
 131     // This is the best we can do. We will only be able to decode the top frame
 132 
 133     *fr_addr = ret_frame;
 134     return true;
 135   }
 136 
 137   // At this point, we know we weren't running Java code. We might
 138   // have a last_Java_sp, but we don't have a walkable frame.
 139   // However, we might still be able to construct something useful
 140   // if the thread was running native code.
 141   if (jt->has_last_Java_frame()) {
 142     assert(!jt->frame_anchor()->walkable(), "case covered above");
 143 
 144     frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());
 145     *fr_addr = ret_frame;
 146     return true;
 147   }
 148 
 149   // nothing else to try but what we found initially
 150 
 151   *fr_addr = ret_frame;
 152   return true;
 153 }
 154 
 155 void JavaThread::cache_global_variables() { }
 156