1/****************************************************************************
2 *                                                                          *
3 *                         GNAT RUN-TIME COMPONENTS                         *
4 *                                                                          *
5 *                   T R A C E B A C K - G C C t a b l e s                  *
6 *                                                                          *
7 *                          C Implementation File                           *
8 *                                                                          *
9 *          Copyright (C) 2004-2012, Free Software Foundation, Inc.         *
10 *                                                                          *
11 * GNAT is free software;  you can  redistribute it  and/or modify it under *
12 * terms of the  GNU General Public License as published  by the Free Soft- *
13 * ware  Foundation;  either version 3,  or (at your option) any later ver- *
14 * sion.  GNAT is distributed in the hope that it will be useful, but WITH- *
15 * OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY *
16 * or FITNESS FOR A PARTICULAR PURPOSE.                                     *
17 *                                                                          *
18 * As a special exception under Section 7 of GPL version 3, you are granted *
19 * additional permissions described in the GCC Runtime Library Exception,   *
20 * version 3.1, as published by the Free Software Foundation.               *
21 *                                                                          *
22 * You should have received a copy of the GNU General Public License and    *
23 * a copy of the GCC Runtime Library Exception along with this program;     *
24 * see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    *
25 * <http://www.gnu.org/licenses/>.                                          *
26 *                                                                          *
27 * GNAT was originally developed  by the GNAT team at  New York University. *
28 * Extensive contributions were provided by Ada Core Technologies Inc.      *
29 *                                                                          *
30 ****************************************************************************/
31
32/* This is an implementation of the __gnat_backtrace routine using the
33   underlying GCC unwinding support associated with the exception handling
34   infrastructure.  This will only work for ZCX based applications.  */
35
36#include <unwind.h>
37
38/* The implementation boils down to a call to _Unwind_Backtrace with a
39   tailored callback and carried-on data structure to keep track of the
40   input parameters we got as well as of the basic processing state.  */
41
42/******************
43 * trace_callback *
44 ******************/
45
46#if !defined (__USING_SJLJ_EXCEPTIONS__)
47
48typedef struct {
49  void ** traceback;
50  int max_len;
51  void * exclude_min;
52  void * exclude_max;
53  int  n_frames_to_skip;
54  int  n_frames_skipped;
55  int  n_entries_filled;
56} uw_data_t;
57
58#if defined (__ia64__) && defined (__hpux__)
59#include <uwx.h>
60#endif
61
62static _Unwind_Reason_Code
63trace_callback (struct _Unwind_Context * uw_context, uw_data_t * uw_data)
64{
65  char * pc;
66
67#if defined (__ia64__) && defined (__hpux__) && defined (USE_LIBUNWIND_EXCEPTIONS)
68  /* Work around problem with _Unwind_GetIP on ia64 HP-UX. */
69  uwx_get_reg ((struct uwx_env *) uw_context, UWX_REG_IP, (uint64_t *) &pc);
70#else
71  pc = (char *) _Unwind_GetIP (uw_context);
72#endif
73
74  if (uw_data->n_frames_skipped < uw_data->n_frames_to_skip)
75    {
76      uw_data->n_frames_skipped ++;
77      return _URC_NO_REASON;
78    }
79
80  if (uw_data->n_entries_filled >= uw_data->max_len)
81    return _URC_NORMAL_STOP;
82
83  if (pc < (char *)uw_data->exclude_min || pc > (char *)uw_data->exclude_max)
84    uw_data->traceback [uw_data->n_entries_filled ++] = pc + PC_ADJUST;
85
86  return _URC_NO_REASON;
87}
88
89#endif
90
91/********************
92 * __gnat_backtrace *
93 ********************/
94
95int
96__gnat_backtrace (void ** traceback __attribute__((unused)),
97		  int max_len __attribute__((unused)),
98		  void * exclude_min __attribute__((unused)),
99		  void * exclude_max __attribute__((unused)),
100		  int skip_frames __attribute__((unused)))
101{
102#if defined (__USING_SJLJ_EXCEPTIONS__)
103  /* We have no unwind material (tables) at hand with sjlj eh, and no
104     way to retrieve complete and accurate call chain information from
105     the context stack we maintain.  */
106  return 0;
107#else
108  uw_data_t uw_data;
109  /* State carried over during the whole unwinding process.  */
110
111  uw_data.traceback   = traceback;
112  uw_data.max_len     = max_len;
113  uw_data.exclude_min = exclude_min;
114  uw_data.exclude_max = exclude_max;
115
116  uw_data.n_frames_to_skip = skip_frames;
117
118  uw_data.n_frames_skipped = 0;
119  uw_data.n_entries_filled = 0;
120
121  _Unwind_Backtrace ((_Unwind_Trace_Fn)trace_callback, &uw_data);
122
123  return uw_data.n_entries_filled;
124#endif
125}
126