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
|
/* Return backtrace of current program state.
Copyright (C) 2000-2015 Free Software Foundation, Inc.
Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>.
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 <bits/libc-lock.h>
#include <dlfcn.h>
#include <execinfo.h>
#include <stddef.h>
#include <stdlib.h>
#include <unwind.h>
/* 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 for every non-leaf function.
size offset
%r15 -> +------------------+
4 | back chain | 0
4 | end of stack | 4
8 | glue | 8
8 | scratch | 16
40 | save area r6-r15 | 24
16 | save area f4,f6 | 64
16 | empty | 80
+------------------+
r14 in the save area holds the return address.
*/
struct layout
{
int back_chain;
int end_of_stack;
int glue[2];
int scratch[2];
int save_grps[10];
int save_fp[4];
int empty[2];
};
struct trace_arg
{
void **array;
int cnt, size;
};
#ifdef SHARED
static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
static _Unwind_Ptr (*unwind_getip) (struct _Unwind_Context *);
static void
init (void)
{
void *handle = __libc_dlopen ("libgcc_s.so.1");
if (handle == NULL)
return;
unwind_backtrace = __libc_dlsym (handle, "_Unwind_Backtrace");
unwind_getip = __libc_dlsym (handle, "_Unwind_GetIP");
if (unwind_getip == NULL)
unwind_backtrace = NULL;
}
static int
__backchain_backtrace (void **array, int size)
{
/* We assume that all the code is generated with frame pointers set. */
struct layout *stack;
int cnt = 0;
asm ("LR %0,%%r15" : "=d" (stack) );
/* We skip the call to this function, it makes no sense to record it. */
stack = (struct layout *) stack->back_chain;
while (cnt < size)
{
if (stack == NULL || (void *) stack > __libc_stack_end)
/* This means the address is out of range. Note that for the
toplevel we see a frame pointer with value NULL which clearly is
out of range. */
break;
array[cnt++] = (void *) (stack->save_grps[8] & 0x7fffffff);
stack = (struct layout *) stack->back_chain;
}
return cnt;
}
#else
# define unwind_backtrace _Unwind_Backtrace
# define unwind_getip _Unwind_GetIP
#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;
return _URC_NO_REASON;
}
int
__backtrace (void **array, int size)
{
struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
#ifdef SHARED
__libc_once_define (static, once);
__libc_once (once, init);
if (unwind_backtrace == NULL)
return __backchain_backtrace (array, size);
#endif
if (size >= 1)
unwind_backtrace (backtrace_helper, &arg);
return arg.cnt != -1 ? arg.cnt : 0;
}
weak_alias (__backtrace, backtrace)
libc_hidden_def (__backtrace)
|
