1 /* Return backtrace of current program state.
2 Copyright (C) 2008-2019 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Kazu Hirata <kazu@codesourcery.com>, 2008.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library. If not, see
18 <https://www.gnu.org/licenses/>. */
20 #include <libc-lock.h>
33 static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
34 static _Unwind_VRS_Result (*unwind_vrs_get) (_Unwind_Context *,
37 _Unwind_VRS_DataRepresentation,
40 static void *libgcc_handle;
45 libgcc_handle = __libc_dlopen ("libgcc_s.so.1");
47 if (libgcc_handle == NULL)
50 unwind_backtrace = __libc_dlsym (libgcc_handle, "_Unwind_Backtrace");
51 unwind_vrs_get = __libc_dlsym (libgcc_handle, "_Unwind_VRS_Get");
52 if (unwind_vrs_get == NULL)
53 unwind_backtrace = NULL;
56 /* This function is identical to "_Unwind_GetGR", except that it uses
57 "unwind_vrs_get" instead of "_Unwind_VRS_Get". */
58 static inline _Unwind_Word
59 unwind_getgr (_Unwind_Context *context, int regno)
62 unwind_vrs_get (context, _UVRSC_CORE, regno, _UVRSD_UINT32, &val);
66 /* This macro is identical to the _Unwind_GetIP macro, except that it
67 uses "unwind_getgr" instead of "_Unwind_GetGR". */
68 # define unwind_getip(context) \
69 (unwind_getgr (context, 15) & ~(_Unwind_Word)1)
71 # define unwind_backtrace _Unwind_Backtrace
72 # define unwind_getip _Unwind_GetIP
75 static _Unwind_Reason_Code
76 backtrace_helper (struct _Unwind_Context *ctx, void *a)
78 struct trace_arg *arg = a;
80 /* We are first called with address in the __backtrace function.
83 arg->array[arg->cnt] = (void *) unwind_getip (ctx);
84 if (++arg->cnt == arg->size)
85 return _URC_END_OF_STACK;
86 return _URC_NO_REASON;
90 __backtrace (void **array, int size)
92 struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
98 __libc_once_define (static, once);
100 __libc_once (once, init);
101 if (unwind_backtrace == NULL)
105 unwind_backtrace (backtrace_helper, &arg);
107 if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
109 return arg.cnt != -1 ? arg.cnt : 0;
111 weak_alias (__backtrace, backtrace)
112 libc_hidden_def (__backtrace)
116 /* Free all resources if necessary. */
117 libc_freeres_fn (free_mem)
119 unwind_backtrace = NULL;
120 if (libgcc_handle != NULL)
122 __libc_dlclose (libgcc_handle);
123 libgcc_handle = NULL;