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/* Return backtrace of current program state.
Copyright (C) 2008-2021 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Kazu Hirata <kazu@codesourcery.com>, 2008.
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
<https://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;
};
#ifdef SHARED
static _Unwind_Reason_Code (*unwind_backtrace) (_Unwind_Trace_Fn, void *);
static _Unwind_VRS_Result (*unwind_vrs_get) (_Unwind_Context *,
_Unwind_VRS_RegClass,
_uw,
_Unwind_VRS_DataRepresentation,
void *);
static void *libgcc_handle;
static void
init (void)
{
libgcc_handle = __libc_dlopen ("libgcc_s.so.1");
if (libgcc_handle == NULL)
return;
unwind_backtrace = __libc_dlsym (libgcc_handle, "_Unwind_Backtrace");
unwind_vrs_get = __libc_dlsym (libgcc_handle, "_Unwind_VRS_Get");
if (unwind_vrs_get == NULL)
unwind_backtrace = NULL;
}
/* This function is identical to "_Unwind_GetGR", except that it uses
"unwind_vrs_get" instead of "_Unwind_VRS_Get". */
static inline _Unwind_Word
unwind_getgr (_Unwind_Context *context, int regno)
{
_uw val;
unwind_vrs_get (context, _UVRSC_CORE, regno, _UVRSD_UINT32, &val);
return val;
}
/* This macro is identical to the _Unwind_GetIP macro, except that it
uses "unwind_getgr" instead of "_Unwind_GetGR". */
# define unwind_getip(context) \
(unwind_getgr (context, 15) & ~(_Unwind_Word)1)
#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 };
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;
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
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