thread_solaris_sparc.cpp revision 1472:c18cbe5936b8 
1/*
2 * Copyright (c) 2003, 2008, 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.
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23 */
24
25#include "incls/_precompiled.incl"
26#include "incls/_thread_solaris_sparc.cpp.incl"
27
28// For Forte Analyzer AsyncGetCallTrace profiling support - thread is
29// currently interrupted by SIGPROF
30//
31// NOTE: On Solaris, register windows are flushed in the signal handler
32// except for possibly the top frame.
33//
34bool JavaThread::pd_get_top_frame_for_signal_handler(frame* fr_addr,
35  void* ucontext, bool isInJava) {
36
37  assert(Thread::current() == this, "caller must be current thread");
38  assert(this->is_Java_thread(), "must be JavaThread");
39
40  JavaThread* jt = (JavaThread *)this;
41
42  if (!isInJava) {
43    // make_walkable flushes register windows and grabs last_Java_pc
44    // which can not be done if the ucontext sp matches last_Java_sp
45    // stack walking utilities assume last_Java_pc set if marked flushed
46    jt->frame_anchor()->make_walkable(jt);
47  }
48
49  // If we have a walkable last_Java_frame, then we should use it
50  // even if isInJava == true. It should be more reliable than
51  // ucontext info.
52  if (jt->has_last_Java_frame() && jt->frame_anchor()->walkable()) {
53    *fr_addr = jt->pd_last_frame();
54    return true;
55  }
56
57  ucontext_t* uc = (ucontext_t*) ucontext;
58
59  // At this point, we don't have a walkable last_Java_frame, so
60  // we try to glean some information out of the ucontext.
61  intptr_t* ret_sp;
62  ExtendedPC addr = os::Solaris::fetch_frame_from_ucontext(this, uc,
63    &ret_sp, NULL /* ret_fp only used on Solaris X86 */);
64  if (addr.pc() == NULL || ret_sp == NULL) {
65    // ucontext wasn't useful
66    return false;
67  }
68
69  frame ret_frame(ret_sp, frame::unpatchable, addr.pc());
70
71  // we were running Java code when SIGPROF came in
72  if (isInJava) {
73
74
75    // If the frame we got is safe then it is most certainly valid
76    if (ret_frame.safe_for_sender(jt)) {
77      *fr_addr = ret_frame;
78      return true;
79    }
80
81    // If it isn't safe then we can try several things to try and get
82    // a good starting point.
83    //
84    // On sparc the frames are almost certainly walkable in the sense
85    // of sp/fp linkages. However because of recycling of windows if
86    // a piece of code does multiple save's where the initial save creates
87    // a real frame with a return pc and the succeeding save's are used to
88    // simply get free registers and have no real pc then the pc linkage on these
89    // "inner" temporary frames will be bogus.
90    // Since there is in general only a nesting level like
91    // this one deep in general we'll try and unwind such an "inner" frame
92    // here ourselves and see if it makes sense
93
94    frame unwind_frame(ret_frame.fp(), frame::unpatchable, addr.pc());
95
96    if (unwind_frame.safe_for_sender(jt)) {
97      *fr_addr = unwind_frame;
98      return true;
99    }
100
101    // Well that didn't work. Most likely we're toast on this tick
102    // The previous code would try this. I think it is dubious in light
103    // of changes to safe_for_sender and the unwind trick above but
104    // if it gets us a safe frame who wants to argue.
105
106    // If we have a last_Java_sp, then the SIGPROF signal caught us
107    // right when we were transitioning from _thread_in_Java to a new
108    // JavaThreadState. We use last_Java_sp instead of the sp from
109    // the ucontext since it should be more reliable.
110
111    if (jt->has_last_Java_frame()) {
112      ret_sp = jt->last_Java_sp();
113      frame ret_frame2(ret_sp, frame::unpatchable, addr.pc());
114      if (ret_frame2.safe_for_sender(jt)) {
115        *fr_addr = ret_frame2;
116        return true;
117      }
118    }
119
120    // This is the best we can do. We will only be able to decode the top frame
121
122    *fr_addr = ret_frame;
123    return true;
124  }
125
126  // At this point, we know we weren't running Java code. We might
127  // have a last_Java_sp, but we don't have a walkable frame.
128  // However, we might still be able to construct something useful
129  // if the thread was running native code.
130  if (jt->has_last_Java_frame()) {
131    assert(!jt->frame_anchor()->walkable(), "case covered above");
132
133    frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());
134    *fr_addr = ret_frame;
135    return true;
136  }
137
138  // nothing else to try but what we found initially
139
140  *fr_addr = ret_frame;
141  return true;
142}
143