1 /*
2 * Copyright (c) 2003, 2018, 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 frame JavaThread::pd_last_frame() {
31 assert(has_last_Java_frame(), "must have last_Java_sp() when suspended");
32 assert(_anchor.walkable(), "thread has not dumped its register windows yet");
33
34 assert(_anchor.last_Java_pc() != NULL, "Ack no pc!");
35 return frame(last_Java_sp(), frame::unpatchable, _anchor.last_Java_pc());
36 }
37
38 // For Forte Analyzer AsyncGetCallTrace profiling support - thread is
39 // currently interrupted by SIGPROF
40 //
41 // NOTE: On Solaris, register windows are flushed in the signal handler
42 // except for possibly the top frame.
43 //
44 bool JavaThread::pd_get_top_frame_for_signal_handler(frame* fr_addr,
45 void* ucontext, bool isInJava) {
46
47 assert(Thread::current() == this, "caller must be current thread");
48 return pd_get_top_frame(fr_addr, ucontext, isInJava, true);
49 }
50
51 bool JavaThread::pd_get_top_frame_for_profiling(frame* fr_addr, void* ucontext, bool isInJava) {
52 // get ucontext somehow
53 return pd_get_top_frame(fr_addr, ucontext, isInJava, false);
54 }
55
56 bool JavaThread::pd_get_top_frame(frame* fr_addr,
57 void* ucontext, bool isInJava, bool makeWalkable) {
58 assert(this->is_Java_thread(), "must be JavaThread");
59
60 JavaThread* jt = (JavaThread *)this;
61
62 if (!isInJava && makeWalkable) {
63 // make_walkable flushes register windows and grabs last_Java_pc
64 // which can not be done if the ucontext sp matches last_Java_sp
65 // stack walking utilities assume last_Java_pc set if marked flushed
66 jt->frame_anchor()->make_walkable(jt);
67 }
68
69 // If we have a walkable last_Java_frame, then we should use it
70 // even if isInJava == true. It should be more reliable than
71 // ucontext info.
72 if (jt->has_last_Java_frame() && jt->frame_anchor()->walkable()) {
73 *fr_addr = jt->pd_last_frame();
74 return true;
75 }
76
77 ucontext_t* uc = (ucontext_t*) ucontext;
78
79 // At this point, we don't have a walkable last_Java_frame, so
80 // we try to glean some information out of the ucontext.
81 intptr_t* ret_sp;
82 ExtendedPC addr = os::Solaris::fetch_frame_from_ucontext(this, uc,
83 &ret_sp, NULL /* ret_fp only used on Solaris X86 */);
84 if (addr.pc() == NULL || ret_sp == NULL) {
85 // ucontext wasn't useful
86 return false;
87 }
88
89 if (MetaspaceShared::is_in_trampoline_frame(addr.pc())) {
90 // In the middle of a trampoline call. Bail out for safety.
91 // This happens rarely so shouldn't affect profiling.
92 return false;
93 }
94
95 frame ret_frame(ret_sp, frame::unpatchable, addr.pc());
96
97 // we were running Java code when SIGPROF came in
98 if (isInJava) {
99
100
101 // If the frame we got is safe then it is most certainly valid
102 if (ret_frame.safe_for_sender(jt)) {
103 *fr_addr = ret_frame;
104 return true;
105 }
106
107 // If it isn't safe then we can try several things to try and get
108 // a good starting point.
109 //
110 // On sparc the frames are almost certainly walkable in the sense
111 // of sp/fp linkages. However because of recycling of windows if
112 // a piece of code does multiple save's where the initial save creates
113 // a real frame with a return pc and the succeeding save's are used to
114 // simply get free registers and have no real pc then the pc linkage on these
115 // "inner" temporary frames will be bogus.
116 // Since there is in general only a nesting level like
117 // this one deep in general we'll try and unwind such an "inner" frame
118 // here ourselves and see if it makes sense
119
120 frame unwind_frame(ret_frame.fp(), frame::unpatchable, addr.pc());
121
122 if (unwind_frame.safe_for_sender(jt)) {
123 *fr_addr = unwind_frame;
124 return true;
125 }
126
127 // Well that didn't work. Most likely we're toast on this tick
128 // The previous code would try this. I think it is dubious in light
129 // of changes to safe_for_sender and the unwind trick above but
130 // if it gets us a safe frame who wants to argue.
131
132 // If we have a last_Java_sp, then the SIGPROF signal caught us
133 // right when we were transitioning from _thread_in_Java to a new
134 // JavaThreadState. We use last_Java_sp instead of the sp from
135 // the ucontext since it should be more reliable.
136
137 if (jt->has_last_Java_frame()) {
138 ret_sp = jt->last_Java_sp();
139 frame ret_frame2(ret_sp, frame::unpatchable, addr.pc());
140 if (ret_frame2.safe_for_sender(jt)) {
141 *fr_addr = ret_frame2;
142 return true;
143 }
144 }
145
146 // This is the best we can do. We will only be able to decode the top frame
147
148 *fr_addr = ret_frame;
149 return true;
150 }
151
152 // At this point, we know we weren't running Java code. We might
153 // have a last_Java_sp, but we don't have a walkable frame.
154 // However, we might still be able to construct something useful
155 // if the thread was running native code.
156 if (jt->has_last_Java_frame()) {
157 assert(!jt->frame_anchor()->walkable(), "case covered above");
158
159 frame ret_frame(jt->last_Java_sp(), frame::unpatchable, addr.pc());
160 *fr_addr = ret_frame;
161 return true;
162 }
163
164 // nothing else to try but what we found initially
165
166 *fr_addr = ret_frame;
167 return true;
168 }
169
170 void JavaThread::cache_global_variables() { }
171