1/* Return backtrace of current program state.
2 Copyright (C) 2008-2024 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library. If not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <execinfo.h>
20#include <stdlib.h>
21#include <unwind-link.h>
22
23struct trace_arg
24{
25 void **array;
26 struct unwind_link *unwind_link;
27 int cnt, size;
28};
29
30#ifdef SHARED
31/* This function is identical to "_Unwind_GetGR", except that it uses
32 "unwind_vrs_get" instead of "_Unwind_VRS_Get". */
33static inline _Unwind_Word
34unwind_getgr (struct unwind_link *unwind_link,
35 _Unwind_Context *context, int regno)
36{
37 _uw val;
38 UNWIND_LINK_PTR (unwind_link, _Unwind_VRS_Get)
39 (context, _UVRSC_CORE, regno, _UVRSD_UINT32, &val);
40 return val;
41}
42
43/* This macro is identical to the _Unwind_GetIP macro, except that it
44 uses "unwind_getgr" instead of "_Unwind_GetGR". */
45#define unwind_getip(context) \
46 (unwind_getgr (arg->unwind_link, context, 15) & ~(_Unwind_Word)1)
47
48#else /* !SHARED */
49# define unwind_getip _Unwind_GetIP
50#endif
51
52static _Unwind_Reason_Code
53backtrace_helper (struct _Unwind_Context *ctx, void *a)
54{
55 struct trace_arg *arg = a;
56
57 /* We are first called with address in the __backtrace function.
58 Skip it. */
59 if (arg->cnt != -1)
60 arg->array[arg->cnt] = (void *) unwind_getip (ctx);
61 if (++arg->cnt == arg->size)
62 return _URC_END_OF_STACK;
63 return _URC_NO_REASON;
64}
65
66int
67__backtrace (void **array, int size)
68{
69 struct trace_arg arg =
70 {
71 .array = array,
72 .unwind_link = __libc_unwind_link_get (),
73 .size = size,
74 .cnt = -1
75 };
76
77 if (size <= 0 || arg.unwind_link == NULL)
78 return 0;
79
80 UNWIND_LINK_PTR (arg.unwind_link, _Unwind_Backtrace)
81 (backtrace_helper, &arg);
82
83 if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
84 --arg.cnt;
85 return arg.cnt != -1 ? arg.cnt : 0;
86}
87weak_alias (__backtrace, backtrace)
88libc_hidden_def (__backtrace)
89

source code of glibc/sysdeps/arm/backtrace.c