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/*
* Perform stack unwinding by using the _Unwind_Backtrace.
*
* User application that wants to use backtrace needs to be
* compiled with -fasynchronous-unwid-tables option and -rdynamic i
* to get full symbols printed.
*
* Author(s): Khem Raj <raj.khem@gmail.com>
* - ARM specific implementation of backtrace
*
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*
*/
#include <libgcc_s.h>
#include <execinfo.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <unwind.h>
#include <assert.h>
#include <stdio.h>
struct trace_arg
{
void **array;
int cnt, size;
};
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 backtrace_init (void)
{
void *handle = dlopen (LIBGCC_S_SO, RTLD_LAZY);
if (handle == NULL
|| ((unwind_backtrace = dlsym (handle, "_Unwind_Backtrace")) == NULL)
|| ((unwind_vrs_get = dlsym (handle, "_Unwind_VRS_Get")) == NULL)) {
printf(LIBGCC_S_SO " must be installed for backtrace to work\n");
abort();
}
}
/* 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)
static _Unwind_Reason_Code
backtrace_helper (struct _Unwind_Context *ctx, void *a)
{
struct trace_arg *arg = a;
assert (unwind_getip(ctx) != NULL);
/* 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;
}
/*
* Perform stack unwinding by using the _Unwind_Backtrace.
*
*/
int backtrace (void **array, int size)
{
struct trace_arg arg = { .array = array, .size = size, .cnt = -1 };
if (unwind_backtrace == NULL)
backtrace_init();
if (size >= 1)
unwind_backtrace (backtrace_helper, &arg);
return arg.cnt != -1 ? arg.cnt : 0;
}
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