libjava/stacktrace.cc

   1 // stacktrace.cc - Functions for unwinding & inspecting the call stack.
   2
   3 /* Copyright (C) 2005  Free Software Foundation
   4
   5    This file is part of libgcj.
   6
   7 This software is copyrighted work licensed under the terms of the
   8 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
   9 details.  */
  10
  11 #include <config.h>
  12
  13 #include <jvm.h>
  14 #include <gcj/cni.h>
  15 #include <java-interp.h>
  16 #include <java-stack.h>
  17
  18 #ifdef HAVE_DLFCN_H
  19 #include <dlfcn.h>
  20 #endif
  21
  22 #include <stdio.h>
  23
  24 #include <java/lang/Class.h>
  25 #include <java/lang/Long.h>
  26 #include <java/util/ArrayList.h>
  27 #include <java/util/IdentityHashMap.h>
  28 #include <gnu/java/lang/MainThread.h>
  29 #include <gnu/gcj/runtime/NameFinder.h>
  30
  31 #include <sysdep/backtrace.h>
  32 #include <sysdep/descriptor.h>
  33
  34 using namespace java::lang;
  35 using namespace java::lang::reflect;
  36 using namespace java::util;
  37 using namespace gnu::gcj::runtime;
  38
  39 // Maps ncode values to their containing native class.
  40 // NOTE: Currently this Map contradicts class GC for native classes. This map
  41 // (and the "new class stack") will need to use WeakReferences in order to
  42 // enable native class GC.
  43 static java::util::IdentityHashMap *ncodeMap;
  44
  45 // Check the "class stack" for any classes initialized since we were last
  46 // called, and add them to ncodeMap.
  47 void
  48 _Jv_StackTrace::UpdateNCodeMap ()
  49 {
  50   // The Map should be large enough so that a typical Java app doesn't cause
  51   // it to rehash, without using too much memory. ~5000 entries should be
  52   // enough.
  53   if (ncodeMap == NULL)
  54     ncodeMap = new java::util::IdentityHashMap (5087);
  55
  56   jclass klass;
  57   while ((klass = _Jv_PopClass ()))
  58     {
  59       //printf ("got %s\n", klass->name->data);
  60 #ifdef INTERPRETER
  61       JvAssert (! _Jv_IsInterpretedClass (klass));
  62 #endif
  63       for (int i=0; i < klass->method_count; i++)
  64         {
  65           _Jv_Method *method = &klass->methods[i];
  66           void *ncode = method->ncode;
  67           // Add non-abstract methods to ncodeMap.
  68           if (ncode)
  69             {
  70               ncode = UNWRAP_FUNCTION_DESCRIPTOR (ncode);
  71               ncodeMap->put ((java::lang::Object *)ncode, klass);
  72             }
  73         }
  74     }
  75 }
  76
  77 // Given a native frame, return the class which this code belongs
  78 // to. Returns NULL if this IP is not associated with a native Java class.
  79 // If NCODE is supplied, it will be set with the ip for the entry point of the
  80 // enclosing method.
  81 jclass
  82 _Jv_StackTrace::ClassForFrame (_Jv_StackFrame *frame)
  83 {
  84   JvAssert (frame->type == frame_native);
  85   jclass klass = NULL;
  86   // use _Unwind_FindEnclosingFunction to find start of method
  87   //void *entryPoint = _Unwind_FindEnclosingFunction (ip);
  88
  89   // look it up in ncodeMap
  90   if (frame->start_ip)
  91     klass = (jclass) ncodeMap->get ((jobject) frame->start_ip);
  92
  93   return klass;
  94 }
  95
  96 _Unwind_Reason_Code
  97 _Jv_StackTrace::UnwindTraceFn (struct _Unwind_Context *context, void *state_ptr)
  98 {
  99   _Jv_UnwindState *state = (_Jv_UnwindState *) state_ptr;
 100   jint pos = state->pos;
 101
 102   // Check if the trace buffer needs to be extended.
 103   if (pos == state->length)
 104     {
 105       int newLength = state->length *= 2;
 106       void *newFrames = _Jv_AllocBytes (newLength * sizeof(_Jv_StackFrame));
 107       memcpy (newFrames, state->frames, state->length * sizeof(_Jv_StackFrame));
 108       state->frames = (_Jv_StackFrame *) newFrames;
 109       state->length = newLength;
 110     }
 111
 112   _Unwind_Ptr func_addr = _Unwind_GetRegionStart (context);
 113
 114   // If we see the interpreter's main function, "pop" an entry off the
 115   // interpreter stack and use that instead, so that the trace goes through
 116   // the java code and not the interpreter itself. This assumes a 1:1
 117   // correspondance between call frames in the interpreted stack and occurances
 118   // of _Jv_InterpMethod::run() on the native stack.
 119 #ifdef INTERPRETER
 120   if (func_addr == (_Unwind_Ptr) &_Jv_InterpMethod::run)
 121     {
 122       state->frames[pos].type = frame_interpreter;
 123       state->frames[pos].interp.meth = state->interp_frame->self;
 124       state->frames[pos].interp.pc = state->interp_frame->pc;
 125       state->interp_frame = state->interp_frame->next;
 126     }
 127   else
 128 #endif
 129     {
 130       state->frames[pos].type = frame_native;
 131       state->frames[pos].ip = (void *) _Unwind_GetIP (context);
 132       state->frames[pos].start_ip = (void *) func_addr;
 133     }
 134
 135   //printf ("unwind ip: %p\n", _Unwind_GetIP (context));
 136
 137   _Unwind_Reason_Code result = _URC_NO_REASON;
 138   if (state->trace_function != NULL)
 139     result = (state->trace_function) (state);
 140   state->pos++;
 141   return result;
 142 }
 143
 144 // Return a raw stack trace from the current point of execution. The raw
 145 // trace will include all functions that have unwind info.
 146 _Jv_StackTrace *
 147 _Jv_StackTrace::GetStackTrace(void)
 148 {
 149   int trace_size = 100;
 150   _Jv_StackFrame frames[trace_size];
 151   _Jv_UnwindState state (trace_size);
 152   state.frames = (_Jv_StackFrame *) &frames;
 153
 154 #ifdef SJLJ_EXCEPTIONS
 155   // The Unwind interface doesn't work with the SJLJ exception model.
 156   // Fall back to a platform-specific unwinder.
 157   fallback_backtrace (&state);
 158 #else /* SJLJ_EXCEPTIONS */
 159   _Unwind_Backtrace (UnwindTraceFn, &state);
 160 #endif /* SJLJ_EXCEPTIONS */
 161
 162   // Copy the trace and return it.
 163   int traceSize = sizeof (_Jv_StackTrace) +
 164     (sizeof (_Jv_StackFrame) * state.pos);
 165   _Jv_StackTrace *trace = (_Jv_StackTrace *) _Jv_AllocBytes (traceSize);
 166   trace->length = state.pos;
 167   memcpy (trace->frames, state.frames, sizeof (_Jv_StackFrame) * state.pos);
 168   return trace;
 169 }
 170
 171 void
 172 _Jv_StackTrace::getLineNumberForFrame(_Jv_StackFrame *frame, NameFinder *finder,
 173                  jstring *sourceFileName, jint *lineNum)
 174 {
 175 #ifdef INTERPRETER
 176   if (frame->type == frame_interpreter)
 177     {
 178       _Jv_InterpMethod *interp_meth = frame->interp.meth;
 179       _Jv_InterpClass *interp_class =
 180          (_Jv_InterpClass *) interp_meth->defining_class->aux_info;
 181       *sourceFileName = interp_class->source_file_name;
 182       *lineNum = interp_meth->get_source_line(frame->interp.pc);
 183       return;
 184     }
 185 #endif
 186   // Use dladdr() to determine in which binary the address IP resides.
 187 #if defined (HAVE_DLFCN_H) && defined (HAVE_DLADDR)
 188   Dl_info info;
 189   jstring binaryName = NULL;
 190   const char *argv0 = _Jv_GetSafeArg(0);
 191
 192   void *ip = frame->ip;
 193   _Unwind_Ptr offset = 0;
 194
 195   if (dladdr (ip, &info))
 196     {
 197       if (info.dli_fname)
 198         binaryName = JvNewStringUTF (info.dli_fname);
 199       else
 200         return;
 201
 202       // addr2line expects relative addresses for shared libraries.
 203       if (strcmp (info.dli_fname, argv0) == 0)
 204         offset = (_Unwind_Ptr) ip;
 205       else
 206         offset = (_Unwind_Ptr) ip - (_Unwind_Ptr) info.dli_fbase;
 207
 208       //printf ("linenum ip: %p\n", ip);
 209       //printf ("%s: 0x%x\n", info.dli_fname, offset);
 210       //offset -= sizeof(void *);
 211
 212       // The unwinder gives us the return address. In order to get the right
 213       // line number for the stack trace, roll it back a little.
 214       offset -= 1;
 215
 216       // printf ("%s: 0x%x\n", info.dli_fname, offset);
 217
 218       finder->lookup (binaryName, (jlong) offset);
 219       *sourceFileName = finder->getSourceFile();
 220       *lineNum = finder->getLineNum();
 221     }
 222 #endif
 223 }
 224
 225 // Look up class and method info for the given stack frame, setting
 226 // frame->klass and frame->meth if they are known.
 227 void
 228 _Jv_StackTrace::FillInFrameInfo (_Jv_StackFrame *frame)
 229 {
 230   jclass klass = NULL;
 231   _Jv_Method *meth = NULL;
 232
 233   if (frame->type == frame_native)
 234     {
 235       klass = _Jv_StackTrace::ClassForFrame (frame);
 236
 237       if (klass != NULL)
 238         // Find method in class
 239         for (int j = 0; j < klass->method_count; j++)
 240           {
 241             if (klass->methods[j].ncode == frame->start_ip)
 242               {
 243                 meth = &klass->methods[j];
 244                 break;
 245               }
 246           }
 247     }
 248 #ifdef INTERPRETER
 249   else if (frame->type == frame_interpreter)
 250     {
 251       _Jv_InterpMethod *interp_meth = frame->interp.meth;
 252       klass = interp_meth->defining_class;
 253       meth = interp_meth->self;
 254     }
 255 #endif
 256   else
 257     JvFail ("Unknown frame type");
 258
 259   frame->klass = klass;
 260   frame->meth = meth;
 261 }
 262
 263 // Convert raw stack frames to a Java array of StackTraceElement objects.
 264 JArray< ::java::lang::StackTraceElement *>*
 265 _Jv_StackTrace::GetStackTraceElements (_Jv_StackTrace *trace,
 266   Throwable *throwable __attribute__((unused)))
 267 {
 268   ArrayList *list = new ArrayList ();
 269
 270 #ifdef SJLJ_EXCEPTIONS
 271   // We can't use the nCodeMap without unwinder support. Instead,
 272   // fake the method name by giving the IP in hex - better than nothing.
 273   jstring hex = JvNewStringUTF ("0x");
 274
 275   for (int i = 0; i < trace->length; i++)
 276     {
 277       jstring sourceFileName = NULL;
 278       jint lineNum = -1;
 279       _Jv_StackFrame *frame = &trace->frames[i];
 280
 281       jstring className = NULL;
 282       jstring methodName = hex->concat (Long::toHexString ((jlong) frame->ip));
 283
 284       StackTraceElement *element = new StackTraceElement (sourceFileName,
 285         lineNum, className, methodName, 0);
 286       list->add (element);
 287     }
 288
 289 #else /* SJLJ_EXCEPTIONS */
 290
 291   //JvSynchronized (ncodeMap);
 292   UpdateNCodeMap ();
 293
 294   NameFinder *finder = new NameFinder();
 295   int start_idx = 0;
 296   int end_idx = trace->length - 1;
 297
 298   // First pass: strip superfluous frames from beginning and end of the trace.
 299   for (int i = 0; i < trace->length; i++)
 300     {
 301       _Jv_StackFrame *frame = &trace->frames[i];
 302       FillInFrameInfo (frame);
 303
 304       if (!frame->klass || !frame->meth)
 305         // Not a Java frame.
 306         continue;
 307
 308       // Throw away the top of the stack till we see:
 309       //  - the constructor(s) of this Throwable, or
 310       //  - the Throwable.fillInStackTrace call.
 311       if (frame->klass == throwable->getClass()
 312           && strcmp (frame->meth->name->chars(), "<init>") == 0)
 313         start_idx = i + 1;
 314
 315       if (frame->klass == &Throwable::class$
 316           && strcmp (frame->meth->name->chars(), "fillInStackTrace") == 0)
 317         start_idx = i + 1;
 318
 319       // End the trace at the application's main() method if we see call_main.
 320       if (frame->klass == &gnu::java::lang::MainThread::class$
 321           && strcmp (frame->meth->name->chars(), "call_main") == 0)
 322         end_idx = i - 1;
 323     }
 324
 325   // Second pass: Look up line-number info for remaining frames.
 326   for (int i = start_idx; i <= end_idx; i++)
 327     {
 328       _Jv_StackFrame *frame = &trace->frames[i];
 329
 330       if (frame->klass == NULL)
 331         // Not a Java frame.
 332         continue;
 333
 334       jstring className = frame->klass->getName ();
 335       jstring methodName = NULL;
 336       if (frame->meth)
 337         methodName = JvNewStringUTF (frame->meth->name->chars());
 338
 339       jstring sourceFileName = NULL;
 340       jint lineNum = -1;
 341
 342       getLineNumberForFrame(frame, finder, &sourceFileName, &lineNum);
 343
 344       StackTraceElement *element = new StackTraceElement (sourceFileName, lineNum,
 345         className, methodName, 0);
 346       list->add (element);
 347     }
 348
 349   finder->close();
 350 #endif /* SJLJ_EXCEPTIONS */
 351
 352   JArray<Object *> *array = JvNewObjectArray (list->size (),
 353     &StackTraceElement::class$, NULL);
 354
 355   return (JArray<StackTraceElement *>*) list->toArray (array);
 356 }
 357
 358 struct CallingClassTraceData
 359 {
 360   jclass checkClass;
 361   jclass foundClass;
 362   _Jv_Method *foundMeth;
 363   bool seen_checkClass;
 364 };
 365
 366 _Unwind_Reason_Code
 367 _Jv_StackTrace::calling_class_trace_fn (_Jv_UnwindState *state)
 368 {
 369   CallingClassTraceData *trace_data = (CallingClassTraceData *)
 370     state->trace_data;
 371   _Jv_StackFrame *frame = &state->frames[state->pos];
 372   FillInFrameInfo (frame);
 373
 374   if (trace_data->seen_checkClass
 375       && frame->klass
 376       && frame->klass != trace_data->checkClass)
 377     {
 378       trace_data->foundClass = frame->klass;
 379       trace_data->foundMeth = frame->meth;
 380       return _URC_NORMAL_STOP;
 381     }
 382
 383   if (frame->klass == trace_data->checkClass)
 384     trace_data->seen_checkClass = true;
 385
 386   return _URC_NO_REASON;
 387 }
 388
 389 // Find the class immediately above the given class on the call stack. Any
 390 // intermediate non-Java
 391 // frames are ignored. If the calling class could not be determined (eg because
 392 // the unwinder is not supported on this platform), NULL is returned.
 393 // This function is used to implement calling-classloader checks and reflection
 394 // accessibility checks.
 395 // CHECKCLASS is typically the class calling GetCallingClass. The first class
 396 // above CHECKCLASS on the call stack will be returned.
 397 jclass
 398 _Jv_StackTrace::GetCallingClass (jclass checkClass)
 399 {
 400   jclass result = NULL;
 401   GetCallerInfo (checkClass, &result, NULL);
 402   return result;
 403 }
 404
 405 void
 406 _Jv_StackTrace::GetCallerInfo (jclass checkClass, jclass *caller_class,
 407   _Jv_Method **caller_meth)
 408 {
 409 #ifndef SJLJ_EXCEPTIONS
 410   int trace_size = 20;
 411   _Jv_StackFrame frames[trace_size];
 412   _Jv_UnwindState state (trace_size);
 413   state.frames = (_Jv_StackFrame *) &frames;
 414
 415   CallingClassTraceData trace_data;
 416   trace_data.checkClass = checkClass;
 417   trace_data.seen_checkClass = false;
 418   trace_data.foundClass = NULL;
 419   trace_data.foundMeth = NULL;
 420
 421   state.trace_function = calling_class_trace_fn;
 422   state.trace_data = (void *) &trace_data;
 423
 424   //JvSynchronized (ncodeMap);
 425   UpdateNCodeMap ();
 426
 427   _Unwind_Backtrace (UnwindTraceFn, &state);
 428
 429   if (caller_class)
 430     *caller_class = trace_data.foundClass;
 431   if (caller_meth)
 432     *caller_meth = trace_data.foundMeth;
 433 #else
 434   return;
 435 #endif
 436 }
 437
 438 // Return a java array containing the Java classes on the stack above CHECKCLASS.
 439 JArray<jclass> *
 440 _Jv_StackTrace::GetClassContext (jclass checkClass)
 441 {
 442   JArray<jclass> *result = NULL;
 443
 444   int trace_size = 100;
 445   _Jv_StackFrame frames[trace_size];
 446   _Jv_UnwindState state (trace_size);
 447   state.frames = (_Jv_StackFrame *) &frames;
 448
 449   //JvSynchronized (ncodeMap);
 450   UpdateNCodeMap ();
 451
 452   _Unwind_Backtrace (UnwindTraceFn, &state);
 453
 454   // Count the number of Java frames on the stack.
 455   int jframe_count = 0;
 456   bool seen_checkClass = false;
 457   int start_pos = -1;
 458   for (int i = 0; i < state.pos; i++)
 459     {
 460       _Jv_StackFrame *frame = &state.frames[i];
 461       FillInFrameInfo (frame);
 462
 463       if (seen_checkClass)
 464         {
 465           if (frame->klass)
 466             {
 467               jframe_count++;
 468               if (start_pos == -1)
 469                 start_pos = i;
 470             }
 471         }
 472       else
 473         seen_checkClass = frame->klass == checkClass;
 474     }
 475   result = (JArray<jclass> *) _Jv_NewObjectArray (jframe_count, &Class::class$, NULL);
 476   int pos = 0;
 477
 478   for (int i = start_pos; i < state.pos; i++)
 479     {
 480       _Jv_StackFrame *frame = &state.frames[i];
 481       if (frame->klass)
 482         elements(result)[pos++] = frame->klass;
 483     }
 484   return result;
 485 }
 486
 487 _Unwind_Reason_Code
 488 _Jv_StackTrace::non_system_trace_fn (_Jv_UnwindState *state)
 489 {
 490   _Jv_StackFrame *frame = &state->frames[state->pos];
 491   FillInFrameInfo (frame);
 492
 493   ClassLoader *classLoader = NULL;
 494
 495   if (frame->klass)
 496     {
 497       classLoader = frame->klass->getClassLoaderInternal();
 498 #ifdef INTERPRETER
 499       if (classLoader != NULL)
 500         {
 501           state->trace_data = (void *) classLoader;
 502           return _URC_NORMAL_STOP;
 503         }
 504 #endif
 505     }
 506
 507   return _URC_NO_REASON;
 508 }
 509
 510 ClassLoader *
 511 _Jv_StackTrace::GetFirstNonSystemClassLoader ()
 512 {
 513   int trace_size = 32;
 514   _Jv_StackFrame frames[trace_size];
 515   _Jv_UnwindState state (trace_size);
 516   state.frames = (_Jv_StackFrame *) &frames;
 517   state.trace_function = non_system_trace_fn;
 518   state.trace_data = NULL;
 519
 520   //JvSynchronized (ncodeMap);
 521   UpdateNCodeMap ();
 522
 523   _Unwind_Backtrace (UnwindTraceFn, &state);
 524
 525   if (state.trace_data)
 526     return (ClassLoader *) state.trace_data;
 527
 528   return NULL;
 529 }