mozglue/misc/StackWalk.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* APIs for getting a stack trace of the current thread */
   8
   9 #ifndef mozilla_StackWalk_h
  10 #define mozilla_StackWalk_h
  11
  12 #include "mozilla/Types.h"
  13 #include <stdint.h>
  14 #include <stdio.h>
  15
  16 MOZ_BEGIN_EXTERN_C
  17
  18 /**
  19  * Returns the position of the Program Counter for the caller of the current
  20  * function. This is meant to be used to feed the aFirstFramePC argument to
  21  * MozStackWalk or MozWalkTheStack*, and should be used in the last function
  22  * that should be skipped in the trace, and passed down to MozStackWalk or
  23  * MozWalkTheStack*, through any intermediaries.
  24  *
  25  * THIS DOES NOT 100% RELIABLY GIVE THE CALLER PC, but marking functions
  26  * calling this macro with MOZ_NEVER_INLINE gets us close. In cases it doesn't
  27  * give the caller's PC, it may give the caller of the caller, or its caller,
  28  * etc. depending on tail call optimization.
  29  *
  30  * Past versions of stackwalking relied on passing a constant number of frames
  31  * to skip to MozStackWalk or MozWalkTheStack, which fell short in more cases
  32  * (inlining of intermediaries, tail call optimization).
  33  */
  34 #define CallerPC() __builtin_extract_return_addr(__builtin_return_address(0))
  35
  36 /**
  37  * The callback for MozStackWalk and MozStackWalkThread.
  38  *
  39  * @param aFrameNumber  The frame number (starts at 1, not 0).
  40  * @param aPC           The program counter value.
  41  * @param aSP           The best approximation possible of what the stack
  42  *                      pointer will be pointing to when the execution returns
  43  *                      to executing that at aPC. If no approximation can
  44  *                      be made it will be nullptr.
  45  * @param aClosure      Extra data passed in from MozStackWalk() or
  46  *                      MozStackWalkThread().
  47  */
  48 typedef void (*MozWalkStackCallback)(uint32_t aFrameNumber, void* aPC,
  49                                      void* aSP, void* aClosure);
  50
  51 /**
  52  * Call aCallback for each stack frame on the current thread, from
  53  * the caller of MozStackWalk to main (or above).
  54  *
  55  * @param aCallback     Callback function, called once per frame.
  56  * @param aFirstFramePC Position of the Program Counter where the trace
  57  *                      starts from. All frames seen before reaching that
  58  *                      address are skipped. Nullptr means that the first
  59  *                      callback will be for the caller of MozStackWalk.
  60  * @param aMaxFrames    Maximum number of frames to trace.  0 means no limit.
  61  * @param aClosure      Caller-supplied data passed through to aCallback.
  62  *
  63  * May skip some stack frames due to compiler optimizations or code
  64  * generation.
  65  */
  66 MFBT_API void MozStackWalk(MozWalkStackCallback aCallback,
  67                            const void* aFirstFramePC, uint32_t aMaxFrames,
  68                            void* aClosure);
  69
  70 typedef struct {
  71   /*
  72    * The name of the shared library or executable containing an
  73    * address and the address's offset within that library, or empty
  74    * string and zero if unknown.
  75    */
  76   char library[256];
  77   ptrdiff_t loffset;
  78   /*
  79    * The name of the file name and line number of the code
  80    * corresponding to the address, or empty string and zero if
  81    * unknown.
  82    */
  83   char filename[256];
  84   unsigned long lineno;
  85   /*
  86    * The name of the function containing an address and the address's
  87    * offset within that function, or empty string and zero if unknown.
  88    */
  89   char function[256];
  90   ptrdiff_t foffset;
  91 } MozCodeAddressDetails;
  92
  93 /**
  94  * For a given pointer to code, fill in the pieces of information used
  95  * when printing a stack trace.
  96  *
  97  * @param aPC         The code address.
  98  * @param aDetails    A structure to be filled in with the result.
  99  */
 100 MFBT_API bool MozDescribeCodeAddress(void* aPC,
 101                                      MozCodeAddressDetails* aDetails);
 102
 103 /**
 104  * Format the information about a code address in a format suitable for
 105  * stack traces on the current platform.  When available, this string
 106  * should contain the function name, source file, and line number.  When
 107  * these are not available, library and offset should be reported, if
 108  * possible.
 109  *
 110  * Note that this output is parsed by several scripts including the fix*.py and
 111  * make-tree.pl scripts in tools/rb/. It should only be change with care, and
 112  * in conjunction with those scripts.
 113  *
 114  * @param aBuffer      A string to be filled in with the description.
 115  *                     The string will always be null-terminated.
 116  * @param aBufferSize  The size, in bytes, of aBuffer, including
 117  *                     room for the terminating null.  If the information
 118  *                     to be printed would be larger than aBuffer, it
 119  *                     will be truncated so that aBuffer[aBufferSize-1]
 120  *                     is the terminating null.
 121  * @param aFrameNumber The frame number.
 122  * @param aPC          The code address.
 123  * @param aFunction    The function name. Possibly null or the empty string.
 124  * @param aLibrary     The library name. Possibly null or the empty string.
 125  * @param aLOffset     The library offset.
 126  * @param aFileName    The filename. Possibly null or the empty string.
 127  * @param aLineNo      The line number. Possibly zero.
 128  * @return             The minimum number of characters necessary to format
 129  *                     the frame information, without the terminating null.
 130  *                     The buffer will have been truncated if the returned
 131  *                     value is greater than aBufferSize-1.
 132  */
 133 MFBT_API int MozFormatCodeAddress(char* aBuffer, uint32_t aBufferSize,
 134                                   uint32_t aFrameNumber, const void* aPC,
 135                                   const char* aFunction, const char* aLibrary,
 136                                   ptrdiff_t aLOffset, const char* aFileName,
 137                                   uint32_t aLineNo);
 138
 139 /**
 140  * Format the information about a code address in the same fashion as
 141  * MozFormatCodeAddress.
 142  *
 143  * @param aBuffer      A string to be filled in with the description.
 144  *                     The string will always be null-terminated.
 145  * @param aBufferSize  The size, in bytes, of aBuffer, including
 146  *                     room for the terminating null.  If the information
 147  *                     to be printed would be larger than aBuffer, it
 148  *                     will be truncated so that aBuffer[aBufferSize-1]
 149  *                     is the terminating null.
 150  * @param aFrameNumber The frame number.
 151  * @param aPC          The code address.
 152  * @param aDetails     The value filled in by MozDescribeCodeAddress(aPC).
 153  * @return             The minimum number of characters necessary to format
 154  *                     the frame information, without the terminating null.
 155  *                     The buffer will have been truncated if the returned
 156  *                     value is greater than aBufferSize-1.
 157  */
 158 MFBT_API int MozFormatCodeAddressDetails(char* aBuffer, uint32_t aBufferSize,
 159                                          uint32_t aFrameNumber, void* aPC,
 160                                          const MozCodeAddressDetails* aDetails);
 161
 162 #ifdef __cplusplus
 163 #  define FRAMES_DEFAULT = 0
 164 #else
 165 #  define FRAMES_DEFAULT
 166 #endif
 167 /**
 168  * Walk the stack and print the stack trace to the given stream.
 169  *
 170  * @param aStream       A stdio stream.
 171  * @param aFirstFramePC Position of the Program Counter where the trace
 172  *                      starts from. All frames seen before reaching that
 173  *                      address are skipped. Nullptr means that the first
 174  *                      callback will be for the caller of MozWalkTheStack.
 175  * @param aMaxFrames    Maximum number of frames to trace.  0 means no limit.
 176  */
 177 MFBT_API void MozWalkTheStack(FILE* aStream,
 178                               const void* aFirstFramePC FRAMES_DEFAULT,
 179                               uint32_t aMaxFrames FRAMES_DEFAULT);
 180
 181 /**
 182  * Walk the stack and send each stack trace line to a callback writer.
 183  * Each line string is null terminated but doesn't contain a '\n' character.
 184  *
 185  * @param aWriter       The callback.
 186  * @param aFirstFramePC Position of the Program Counter where the trace
 187  *                      starts from. All frames seen before reaching that
 188  *                      address are skipped. Nullptr means that the first
 189  *                      callback will be for the caller of
 190  * MozWalkTheStackWithWriter.
 191  * @param aMaxFrames    Maximum number of frames to trace.  0 means no limit.
 192  */
 193 MFBT_API void MozWalkTheStackWithWriter(
 194     void (*aWriter)(const char*), const void* aFirstFramePC FRAMES_DEFAULT,
 195     uint32_t aMaxFrames FRAMES_DEFAULT);
 196
 197 #undef FRAMES_DEFAULT
 198
 199 MOZ_END_EXTERN_C
 200
 201 #ifdef __cplusplus
 202 namespace mozilla {
 203
 204 MFBT_API void FramePointerStackWalk(MozWalkStackCallback aCallback,
 205                                     uint32_t aMaxFrames, void* aClosure,
 206                                     void** aBp, void* aStackEnd);
 207
 208 #  if defined(XP_LINUX) || defined(XP_FREEBSD)
 209 MFBT_API void DemangleSymbol(const char* aSymbol, char* aBuffer, int aBufLen);
 210 #  endif
 211
 212 }  // namespace mozilla
 213 #endif
 214
 215 #endif