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annotate agent/src/share/classes/sun/jvm/hotspot/runtime/amd64/AMD64CurrentFrameGuess.java @ 3908:7588156f5cf9
7051798: SA-JDI: NPE in Frame.addressOfStackSlot(Frame.java:244)
Reviewed-by: kvn
| author | never |
|---|---|
| date | Mon, 05 Sep 2011 17:09:05 -0700 |
| parents | c18cbe5936b8 |
| children |
| rev | line source |
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| 0 | 1 /* |
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2 * Copyright (c) 2003, 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 |
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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.amd64; | |
| 26 | |
| 27 import sun.jvm.hotspot.debugger.*; | |
| 28 import sun.jvm.hotspot.debugger.amd64.*; | |
| 29 import sun.jvm.hotspot.code.*; | |
| 30 import sun.jvm.hotspot.interpreter.*; | |
| 31 import sun.jvm.hotspot.runtime.*; | |
|
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32 import sun.jvm.hotspot.runtime.x86.*; |
| 0 | 33 |
| 34 /** <P> Should be able to be used on all amd64 platforms we support | |
| 35 (Linux/amd64) to implement JavaThread's | |
| 36 "currentFrameGuess()" functionality. Input is an AMD64ThreadContext; | |
| 37 output is SP, FP, and PC for an AMD64Frame. Instantiation of the | |
| 38 AMD64Frame is left to the caller, since we may need to subclass | |
| 39 AMD64Frame to support signal handler frames on Unix platforms. </P> | |
| 40 | |
| 41 <P> Algorithm is to walk up the stack within a given range (say, | |
| 42 512K at most) looking for a plausible PC and SP for a Java frame, | |
| 43 also considering those coming in from the context. If we find a PC | |
| 44 that belongs to the VM (i.e., in generated code like the | |
| 45 interpreter or CodeCache) then we try to find an associated EBP. | |
| 46 We repeat this until we either find a complete frame or run out of | |
| 47 stack to look at. </P> */ | |
| 48 | |
| 49 public class AMD64CurrentFrameGuess { | |
| 50 private AMD64ThreadContext context; | |
| 51 private JavaThread thread; | |
| 52 private Address spFound; | |
| 53 private Address fpFound; | |
| 54 private Address pcFound; | |
| 55 | |
| 56 private static final boolean DEBUG = System.getProperty("sun.jvm.hotspot.runtime.amd64.AMD64Frame.DEBUG") | |
| 57 != null; | |
| 58 | |
| 59 public AMD64CurrentFrameGuess(AMD64ThreadContext context, | |
| 60 JavaThread thread) { | |
| 61 this.context = context; | |
| 62 this.thread = thread; | |
| 63 } | |
| 64 | |
| 65 /** Returns false if not able to find a frame within a reasonable range. */ | |
| 66 public boolean run(long regionInBytesToSearch) { | |
| 67 Address sp = context.getRegisterAsAddress(AMD64ThreadContext.RSP); | |
| 68 Address pc = context.getRegisterAsAddress(AMD64ThreadContext.RIP); | |
| 69 Address fp = context.getRegisterAsAddress(AMD64ThreadContext.RBP); | |
| 70 if (sp == null) { | |
| 71 // Bail out if no last java frame either | |
| 72 if (thread.getLastJavaSP() != null) { | |
| 73 setValues(thread.getLastJavaSP(), thread.getLastJavaFP(), null); | |
| 74 return true; | |
| 75 } | |
| 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); | |
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127 Frame frame = new X86Frame(curSP, null, pc); |
| 0 | 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 AMD64Frame.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 AMD64Frame | |
| 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 AMD64Frame 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 } |