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annotate agent/src/share/classes/sun/jvm/hotspot/runtime/x86/X86CurrentFrameGuess.java @ 6073:78d2ae5ab35b
7163117: Agent can't connect to process on Mac OSX
Reviewed-by: dholmes, coleenp, sla, minqi, kvn
author | nloodin |
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date | Wed, 09 May 2012 16:24:07 +0200 |
parents | c18cbe5936b8 |
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rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 2001, 2006, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
c18cbe5936b8
6941466: Oracle rebranding changes for Hotspot repositories
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
25 package sun.jvm.hotspot.runtime.x86; | |
26 | |
27 import sun.jvm.hotspot.debugger.*; | |
28 import sun.jvm.hotspot.debugger.x86.*; | |
29 import sun.jvm.hotspot.code.*; | |
30 import sun.jvm.hotspot.interpreter.*; | |
31 import sun.jvm.hotspot.runtime.*; | |
32 | |
33 /** <P> Should be able to be used on all x86 platforms we support | |
34 (Win32, Solaris/x86, and soon Linux) to implement JavaThread's | |
35 "currentFrameGuess()" functionality. Input is an X86ThreadContext; | |
36 output is SP, FP, and PC for an X86Frame. Instantiation of the | |
37 X86Frame is left to the caller, since we may need to subclass | |
38 X86Frame to support signal handler frames on Unix platforms. </P> | |
39 | |
40 <P> Algorithm is to walk up the stack within a given range (say, | |
41 512K at most) looking for a plausible PC and SP for a Java frame, | |
42 also considering those coming in from the context. If we find a PC | |
43 that belongs to the VM (i.e., in generated code like the | |
44 interpreter or CodeCache) then we try to find an associated EBP. | |
45 We repeat this until we either find a complete frame or run out of | |
46 stack to look at. </P> */ | |
47 | |
48 public class X86CurrentFrameGuess { | |
49 private X86ThreadContext context; | |
50 private JavaThread thread; | |
51 private Address spFound; | |
52 private Address fpFound; | |
53 private Address pcFound; | |
54 | |
55 private static final boolean DEBUG = System.getProperty("sun.jvm.hotspot.runtime.x86.X86Frame.DEBUG") | |
56 != null; | |
57 | |
58 public X86CurrentFrameGuess(X86ThreadContext context, | |
59 JavaThread thread) { | |
60 this.context = context; | |
61 this.thread = thread; | |
62 } | |
63 | |
64 /** Returns false if not able to find a frame within a reasonable range. */ | |
65 public boolean run(long regionInBytesToSearch) { | |
66 Address sp = context.getRegisterAsAddress(X86ThreadContext.SP); | |
67 Address pc = context.getRegisterAsAddress(X86ThreadContext.PC); | |
68 Address fp = context.getRegisterAsAddress(X86ThreadContext.FP); | |
69 if (sp == null) { | |
70 // Bail out if no last java frame eithe | |
71 if (thread.getLastJavaSP() != null) { | |
72 setValues(thread.getLastJavaSP(), thread.getLastJavaFP(), null); | |
73 return true; | |
74 } | |
75 // Bail out | |
76 return false; | |
77 } | |
78 Address end = sp.addOffsetTo(regionInBytesToSearch); | |
79 VM vm = VM.getVM(); | |
80 | |
81 setValues(null, null, null); // Assume we're not going to find anything | |
82 | |
83 if (vm.isJavaPCDbg(pc)) { | |
84 if (vm.isClientCompiler()) { | |
85 // If the topmost frame is a Java frame, we are (pretty much) | |
86 // guaranteed to have a viable EBP. We should be more robust | |
87 // than this (we have the potential for losing entire threads' | |
88 // stack traces) but need to see how much work we really have | |
89 // to do here. Searching the stack for an (SP, FP) pair is | |
90 // hard since it's easy to misinterpret inter-frame stack | |
91 // pointers as base-of-frame pointers; we also don't know the | |
92 // sizes of C1 frames (not registered in the nmethod) so can't | |
93 // derive them from ESP. | |
94 | |
95 setValues(sp, fp, pc); | |
96 return true; | |
97 } else { | |
98 if (vm.getInterpreter().contains(pc)) { | |
99 if (DEBUG) { | |
100 System.out.println("CurrentFrameGuess: choosing interpreter frame: sp = " + | |
101 sp + ", fp = " + fp + ", pc = " + pc); | |
102 } | |
103 setValues(sp, fp, pc); | |
104 return true; | |
105 } | |
106 | |
107 // For the server compiler, EBP is not guaranteed to be valid | |
108 // for compiled code. In addition, an earlier attempt at a | |
109 // non-searching algorithm (see below) failed because the | |
110 // stack pointer from the thread context was pointing | |
111 // (considerably) beyond the ostensible end of the stack, into | |
112 // garbage; walking from the topmost frame back caused a crash. | |
113 // | |
114 // This algorithm takes the current PC as a given and tries to | |
115 // find the correct corresponding SP by walking up the stack | |
116 // and repeatedly performing stackwalks (very inefficient). | |
117 // | |
118 // FIXME: there is something wrong with stackwalking across | |
119 // adapter frames...this is likely to be the root cause of the | |
120 // failure with the simpler algorithm below. | |
121 | |
122 for (long offset = 0; | |
123 offset < regionInBytesToSearch; | |
124 offset += vm.getAddressSize()) { | |
125 try { | |
126 Address curSP = sp.addOffsetTo(offset); | |
127 Frame frame = new X86Frame(curSP, null, pc); | |
128 RegisterMap map = thread.newRegisterMap(false); | |
129 while (frame != null) { | |
130 if (frame.isEntryFrame() && frame.entryFrameIsFirst()) { | |
131 // We were able to traverse all the way to the | |
132 // bottommost Java frame. | |
133 // This sp looks good. Keep it. | |
134 if (DEBUG) { | |
135 System.out.println("CurrentFrameGuess: Choosing sp = " + curSP + ", pc = " + pc); | |
136 } | |
137 setValues(curSP, null, pc); | |
138 return true; | |
139 } | |
140 frame = frame.sender(map); | |
141 } | |
142 } catch (Exception e) { | |
143 if (DEBUG) { | |
144 System.out.println("CurrentFrameGuess: Exception " + e + " at offset " + offset); | |
145 } | |
146 // Bad SP. Try another. | |
147 } | |
148 } | |
149 | |
150 // Were not able to find a plausible SP to go with this PC. | |
151 // Bail out. | |
152 return false; | |
153 | |
154 /* | |
155 // Original algorithm which does not work because SP was | |
156 // pointing beyond where it should have: | |
157 | |
158 // For the server compiler, EBP is not guaranteed to be valid | |
159 // for compiled code. We see whether the PC is in the | |
160 // interpreter and take care of that, otherwise we run code | |
161 // (unfortunately) duplicated from X86Frame.senderForCompiledFrame. | |
162 | |
163 CodeCache cc = vm.getCodeCache(); | |
164 if (cc.contains(pc)) { | |
165 CodeBlob cb = cc.findBlob(pc); | |
166 | |
167 // See if we can derive a frame pointer from SP and PC | |
168 // NOTE: This is the code duplicated from X86Frame | |
169 Address saved_fp = null; | |
170 int llink_offset = cb.getLinkOffset(); | |
171 if (llink_offset >= 0) { | |
172 // Restore base-pointer, since next frame might be an interpreter frame. | |
173 Address fp_addr = sp.addOffsetTo(VM.getVM().getAddressSize() * llink_offset); | |
174 saved_fp = fp_addr.getAddressAt(0); | |
175 } | |
176 | |
177 setValues(sp, saved_fp, pc); | |
178 return true; | |
179 } | |
180 */ | |
181 } | |
182 } else { | |
183 // If the current program counter was not known to us as a Java | |
184 // PC, we currently assume that we are in the run-time system | |
185 // and attempt to look to thread-local storage for saved ESP and | |
186 // EBP. Note that if these are null (because we were, in fact, | |
187 // in Java code, i.e., vtable stubs or similar, and the SA | |
188 // didn't have enough insight into the target VM to understand | |
189 // that) then we are going to lose the entire stack trace for | |
190 // the thread, which is sub-optimal. FIXME. | |
191 | |
192 if (DEBUG) { | |
193 System.out.println("CurrentFrameGuess: choosing last Java frame: sp = " + | |
194 thread.getLastJavaSP() + ", fp = " + thread.getLastJavaFP()); | |
195 } | |
196 if (thread.getLastJavaSP() == null) { | |
197 return false; // No known Java frames on stack | |
198 } | |
199 setValues(thread.getLastJavaSP(), thread.getLastJavaFP(), null); | |
200 return true; | |
201 } | |
202 } | |
203 | |
204 public Address getSP() { return spFound; } | |
205 public Address getFP() { return fpFound; } | |
206 /** May be null if getting values from thread-local storage; take | |
207 care to call the correct X86Frame constructor to recover this if | |
208 necessary */ | |
209 public Address getPC() { return pcFound; } | |
210 | |
211 private void setValues(Address sp, Address fp, Address pc) { | |
212 spFound = sp; | |
213 fpFound = fp; | |
214 pcFound = pc; | |
215 } | |
216 } |