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 //
  33 // NOTE: On Solaris, register windows are flushed in the signal handler
  34 // except for possibly the top frame.
  35 //
  36 bool JavaThread::pd_get_top_frame_for_signal_handler(frame* fr_addr,
  37   void* ucontext, bool isInJava) {
  38 
  39   assert(Thread::current() == this, "caller must be current thread");
  40   return pd_get_top_frame(fr_addr, ucontext, isInJava, true);
  41 }
  42 
  43 bool JavaThread::pd_get_top_frame_for_profiling(frame* fr_addr, void* ucontext, bool isInJava) {
  44   // get ucontext somehow
  45   return pd_get_top_frame(fr_addr, ucontext, isInJava, false);
  46 }
  47 
  48 bool JavaThread::pd_get_top_frame(frame* fr_addr,
  49   void* ucontext, bool isInJava, bool makeWalkable) {
  50   assert(this->is_Java_thread(), "must be JavaThread");
  51 
  52   JavaThread* jt = (JavaThread *)this;
  53 
  54   if (!isInJava && makeWalkable) {
  55     // make_walkable flushes register windows and grabs last_Java_pc
  56     // which can not be done if the ucontext sp matches last_Java_sp
  57     // stack walking utilities assume last_Java_pc set if marked flushed
  58     jt->frame_anchor()->make_walkable(jt);
  59   }
  60 
  61   // If we have a walkable last_Java_frame, then we should use it
  62   // even if isInJava == true. It should be more reliable than
  63   // ucontext info.
  64   if (jt->has_last_Java_frame() && jt->frame_anchor()->walkable()) {
  65     *fr_addr = jt->pd_last_frame();
  66     return true;
  67   }
  68 
  69   ucontext_t* uc = (ucontext_t*) ucontext;
  70 
  71   // At this point, we don't have a walkable last_Java_frame, so
  72   // we try to glean some information out of the ucontext.
  73   intptr_t* ret_sp;
  74   ExtendedPC addr = os::Solaris::fetch_frame_from_ucontext(this, uc,
  75     &ret_sp, NULL /* ret_fp only used on Solaris X86 */);
  76   if (addr.pc() == NULL || ret_sp == NULL) {
  77     // ucontext wasn't useful
  78     return false;
  79   }
  80 
  81   if (MetaspaceShared::is_in_trampoline_frame(addr.pc())) {
  82     // In the middle of a trampoline call. Bail out for safety.
  83     // This happens rarely so shouldn't affect profiling.
  84     return false;
  85   }
  86 
  87   frame ret_frame(ret_sp, frame::unpatchable, addr.pc());
  88 
  89   // we were running Java code when SIGPROF came in
  90   if (isInJava) {
  91 
  92 
  93     // If the frame we got is safe then it is most certainly valid
  94     if (ret_frame.safe_for_sender(jt)) {
  95       *fr_addr = ret_frame;
  96       return true;
  97     }
  98 
  99     // If it isn't safe then we can try several things to try and get
 100     // a good starting point.
 101     //
 102     // On sparc the frames are almost certainly walkable in the sense
 103     // of sp/fp linkages. However because of recycling of windows if
 104     // a piece of code does multiple save's where the initial save creates
 105     // a real frame with a return pc and the succeeding save's are used to
 106     // simply get free registers and have no real pc then the pc linkage on these
 107     // "inner" temporary frames will be bogus.
 108     // Since there is in general only a nesting level like
 109     // this one deep in general we'll try and unwind such an "inner" frame
 110     // here ourselves and see if it makes sense
 111 
 112     frame unwind_frame(ret_frame.fp(), frame::unpatchable, addr.pc());
 113 
 114     if (unwind_frame.safe_for_sender(jt)) {
 115       *fr_addr = unwind_frame;
 116       return true;
 117     }
 118 
 119     // Well that didn't work. Most likely we're toast on this tick
 120     // The previous code would try this. I think it is dubious in light
 121     // of changes to safe_for_sender and the unwind trick above but
 122     // if it gets us a safe frame who wants to argue.
 123 
 124     // If we have a last_Java_sp, then the SIGPROF signal caught us
 125     // right when we were transitioning from _thread_in_Java to a new
 126     // JavaThreadState. We use last_Java_sp instead of the sp from
 127     // the ucontext since it should be more reliable.
 128 
 129     if (jt->has_last_Java_frame()) {
 130       ret_sp = jt->last_Java_sp();
 131       frame ret_frame2(ret_sp, frame::unpatchable, addr.pc());
 132       if (ret_frame2.safe_for_sender(jt)) {
 133         *fr_addr = ret_frame2;
 134         return true;
 135       }
 136     }
 137 
 138     // This is the best we can do. We will only be able to decode the top frame
 139 
 140     *fr_addr = ret_frame;
 141     return true;
 142   }
 143 
 144   // At this point, we know we weren't running Java code. We might
 145   // have a last_Java_sp, but we don't have a walkable frame.
 146   // However, we might still be able to construct something useful
 147   // if the thread was running native code.
 148   if (jt->has_last_Java_frame()) {
 149     assert(!jt->frame_anchor()->walkable(), "case covered above");
 150 
 151     frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());
 152     *fr_addr = ret_frame;
 153     return true;
 154   }
 155 
 156   // nothing else to try but what we found initially
 157 
 158   *fr_addr = ret_frame;
 159   return true;
 160 }
 161 
 162 void JavaThread::cache_global_variables() { }
 163