1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
/* Return backtrace of current program state.
Copyright (C) 2013-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <libc-lock.h>
#include <dlfcn.h>
#include <execinfo.h>
#include <stdlib.h>
#include <unwind.h>
struct trace_arg
{
void **array;
int cnt, size;
void *lastfp, *lastsp;
};
#ifdef SHARED
static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);
static _Unwind_Ptr (*unwind_getcfa) (struct _Unwind_Context *);
static _Unwind_Ptr (*unwind_getgr) (struct _Unwind_Context *, int);
static void *libgcc_handle;
static void
init (void)
{
libgcc_handle = __libc_dlopen ("libgcc_s.so.2");
if (libgcc_handle == NULL)
return;
unwind_backtrace = __libc_dlsym (libgcc_handle, "_Unwind_Backtrace");
unwind_getip = __libc_dlsym (libgcc_handle, "_Unwind_GetIP");
unwind_getcfa = __libc_dlsym (libgcc_handle, "_Unwind_GetCFA");
unwind_getgr = __libc_dlsym (libgcc_handle, "_Unwind_GetGR");
if (unwind_getip == NULL || unwind_getgr == NULL || unwind_getcfa == NULL)
{
unwind_backtrace = NULL;
__libc_dlclose (libgcc_handle);
libgcc_handle = NULL;
}
}
#else
# define unwind_backtrace _Unwind_Backtrace
# define unwind_getip _Unwind_GetIP
# define unwind_getcfa _Unwind_GetCFA
# define unwind_getgr _Unwind_GetGR
#endif
static _Unwind_Reason_Code
backtrace_helper (struct _Unwind_Context *ctx, void *a)
{
struct trace_arg *arg = a;
/* We are first called with address in the __backtrace function.
Skip it. */
if (arg->cnt != -1)
arg->array[arg->cnt] = (void *) unwind_getip (ctx);
if (++arg->cnt == arg->size)
return _URC_END_OF_STACK;
/* %fp is DWARF2 register 14 on M68K. */
arg->lastfp = (void *) unwind_getgr (ctx, 14);
arg->lastsp = (void *) unwind_getcfa (ctx);
return _URC_NO_REASON;
}
/* This is a global variable set at program start time. It marks the
highest used stack address. */
extern void *__libc_stack_end;
/* This is the stack layout we see with every stack frame
if not compiled without frame pointer.
+-----------------+ +-----------------+
%fp -> | %fp last frame--------> | %fp last frame--->...
| | | |
| return address | | return address |
+-----------------+ +-----------------+
First try as far to get as far as possible using
_Unwind_Backtrace which handles -fomit-frame-pointer
as well, but requires .eh_frame info. Then fall back to
walking the stack manually. */
struct layout
{
struct layout *fp;
void *ret;
};
int
__backtrace (void **array, int size)
{
struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
if (size <= 0)
return 0;
#ifdef SHARED
__libc_once_define (static, once);
__libc_once (once, init);
if (unwind_backtrace == NULL)
return 0;
#endif
unwind_backtrace (backtrace_helper, &arg);
if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
--arg.cnt;
else if (arg.cnt < size)
{
struct layout *fp = (struct layout *) arg.lastfp;
while (arg.cnt < size)
{
/* Check for out of range. */
if ((void *) fp < arg.lastsp || (void *) fp > __libc_stack_end
|| ((long) fp & 1))
break;
array[arg.cnt++] = fp->ret;
fp = fp->fp;
}
}
return arg.cnt != -1 ? arg.cnt : 0;
}
weak_alias (__backtrace, backtrace)
libc_hidden_def (__backtrace)
#ifdef SHARED
/* Free all resources if necessary. */
libc_freeres_fn (free_mem)
{
unwind_backtrace = NULL;
if (libgcc_handle != NULL)
{
__libc_dlclose (libgcc_handle);
libgcc_handle = NULL;
}
}
#endif
|
