1 /*
   2  * Copyright (c) 2003, 2010, 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   assert(this->is_Java_thread(), "must be JavaThread");
  40 
  41   JavaThread* jt = (JavaThread *)this;
  42 
  43   if (!isInJava) {
  44     // make_walkable flushes register windows and grabs last_Java_pc
  45     // which can not be done if the ucontext sp matches last_Java_sp
  46     // stack walking utilities assume last_Java_pc set if marked flushed
  47     jt->frame_anchor()->make_walkable(jt);
  48   }
  49 
  50   // If we have a walkable last_Java_frame, then we should use it
  51   // even if isInJava == true. It should be more reliable than
  52   // ucontext info.
  53   if (jt->has_last_Java_frame() && jt->frame_anchor()->walkable()) {
  54     *fr_addr = jt->pd_last_frame();
  55     return true;
  56   }
  57 
  58   ucontext_t* uc = (ucontext_t*) ucontext;
  59 
  60   // At this point, we don't have a walkable last_Java_frame, so
  61   // we try to glean some information out of the ucontext.
  62   intptr_t* ret_sp;
  63   ExtendedPC addr = os::Solaris::fetch_frame_from_ucontext(this, uc,
  64     &ret_sp, NULL /* ret_fp only used on Solaris X86 */);
  65   if (addr.pc() == NULL || ret_sp == NULL) {
  66     // ucontext wasn't useful
  67     return false;
  68   }
  69 
  70   frame ret_frame(ret_sp, frame::unpatchable, addr.pc());
  71 
  72   // we were running Java code when SIGPROF came in
  73   if (isInJava) {
  74 
  75 
  76     // If the frame we got is safe then it is most certainly valid
  77     if (ret_frame.safe_for_sender(jt)) {
  78       *fr_addr = ret_frame;
  79       return true;
  80     }
  81 
  82     // If it isn't safe then we can try several things to try and get
  83     // a good starting point.
  84     //
  85     // On sparc the frames are almost certainly walkable in the sense
  86     // of sp/fp linkages. However because of recycling of windows if
  87     // a piece of code does multiple save's where the initial save creates
  88     // a real frame with a return pc and the succeeding save's are used to
  89     // simply get free registers and have no real pc then the pc linkage on these
  90     // "inner" temporary frames will be bogus.
  91     // Since there is in general only a nesting level like
  92     // this one deep in general we'll try and unwind such an "inner" frame
  93     // here ourselves and see if it makes sense
  94 
  95     frame unwind_frame(ret_frame.fp(), frame::unpatchable, addr.pc());
  96 
  97     if (unwind_frame.safe_for_sender(jt)) {
  98       *fr_addr = unwind_frame;
  99       return true;
 100     }
 101 
 102     // Well that didn't work. Most likely we're toast on this tick
 103     // The previous code would try this. I think it is dubious in light
 104     // of changes to safe_for_sender and the unwind trick above but
 105     // if it gets us a safe frame who wants to argue.
 106 
 107     // If we have a last_Java_sp, then the SIGPROF signal caught us
 108     // right when we were transitioning from _thread_in_Java to a new
 109     // JavaThreadState. We use last_Java_sp instead of the sp from
 110     // the ucontext since it should be more reliable.
 111 
 112     if (jt->has_last_Java_frame()) {
 113       ret_sp = jt->last_Java_sp();
 114       frame ret_frame2(ret_sp, frame::unpatchable, addr.pc());
 115       if (ret_frame2.safe_for_sender(jt)) {
 116         *fr_addr = ret_frame2;
 117         return true;
 118       }
 119     }
 120 
 121     // This is the best we can do. We will only be able to decode the top frame
 122 
 123     *fr_addr = ret_frame;
 124     return true;
 125   }
 126 
 127   // At this point, we know we weren't running Java code. We might
 128   // have a last_Java_sp, but we don't have a walkable frame.
 129   // However, we might still be able to construct something useful
 130   // if the thread was running native code.
 131   if (jt->has_last_Java_frame()) {
 132     assert(!jt->frame_anchor()->walkable(), "case covered above");
 133 
 134     frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());
 135     *fr_addr = ret_frame;
 136     return true;
 137   }
 138 
 139   // nothing else to try but what we found initially
 140 
 141   *fr_addr = ret_frame;
 142   return true;
 143 }
 144 
 145 void JavaThread::cache_global_variables() { }
 146