tools/libnacl/stacktrace.c

   1 /*
   2  * Copyright 2008, Google Inc.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met:
   8  *
   9  *     * Redistributions of source code must retain the above copyright
  10  * notice, this list of conditions and the following disclaimer.
  11  *     * Redistributions in binary form must reproduce the above
  12  * copyright notice, this list of conditions and the following disclaimer
  13  * in the documentation and/or other materials provided with the
  14  * distribution.
  15  *     * Neither the name of Google Inc. nor the names of its
  16  * contributors may be used to endorse or promote products derived from
  17  * this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  20  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  22  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  23  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32
  33 /*
  34  * Used to provide stack traceback support in NaCl modules in the debugger.
  35  * When the application is compiled with -finstrument functions, stack tracing
  36  * is turned on.  This module maintains a stack of function entry addresses.
  37  * The state of the stack trace can be printed at any point by calling
  38  * __nacl_dump_stack_trace.
  39  */
  40
  41 #include <stdio.h>
  42
  43 #define STACK_MAX_DEPTH 1024
  44 static void* stack[STACK_MAX_DEPTH];
  45
  46 static int top_loc = 0;
  47
  48 static void push(void* function_address) {
  49   if (top_loc < STACK_MAX_DEPTH) {
  50     stack[top_loc] = function_address;
  51   }
  52   /*
  53    * Although we have a static limit on the number of function addresses that
  54    * may be pushed, we keep track of the depth even beyond that.  Deeply
  55    * recursive chains will look confused, and may make top_loc wrap around
  56    * (to a negative number) in unusual cases, but we can improve this later.
  57    */
  58   ++top_loc;
  59 }
  60
  61 static void pop() {
  62   /*
  63    * It's possible the calls and returns won't match.  Don't decrement past the
  64    * bottom of the stack.
  65    */
  66   if (top_loc > 0) {
  67     --top_loc;
  68   }
  69 }
  70
  71 void __cyg_profile_func_enter(void* this_fn, void* call_site) {
  72   push(this_fn);
  73 }
  74
  75 void __cyg_profile_func_exit(void* this_fn, void* call_site) {
  76   pop();
  77 }
  78
  79 void __nacl_dump_stack_trace() {
  80   int i;
  81   if (top_loc > STACK_MAX_DEPTH) {
  82     printf("Overflow: %d calls were not recorded.\n",
  83            top_loc - STACK_MAX_DEPTH);
  84   }
  85   for (i = top_loc - 1; i >= 0; i--) {
  86     printf("%d: %p\n", top_loc - 1 - i, stack[i]);
  87   }
  88 }