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/* Return backtrace of current program state.
Copyright (C) 2013-2021 Free Software Foundation, Inc.
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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, see <https://www.gnu.org/licenses/>. */
#include <execinfo.h>
#include <stddef.h>
#include <sysdep.h>
#include <sys/trap.h>
#include <backtrace.h>
#include <unwind-link.h>
struct layout
{
unsigned long locals[8];
unsigned long ins[6];
unsigned long next;
void *return_address;
};
struct trace_arg
{
void **array;
struct unwind_link *unwind_link;
_Unwind_Word cfa;
int cnt;
int size;
};
static _Unwind_Reason_Code
backtrace_helper (struct _Unwind_Context *ctx, void *a)
{
struct trace_arg *arg = a;
_Unwind_Ptr ip;
/* We are first called with address in the __backtrace function.
Skip it. */
if (arg->cnt != -1)
{
ip = UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetIP) (ctx);
arg->array[arg->cnt] = (void *) ip;
/* Check whether we make any progress. */
_Unwind_Word cfa
= UNWIND_LINK_PTR (arg->unwind_link, _Unwind_GetCFA) (ctx);
if (arg->cnt > 0 && arg->array[arg->cnt - 1] == arg->array[arg->cnt]
&& cfa == arg->cfa)
return _URC_END_OF_STACK;
arg->cfa = cfa;
}
if (++arg->cnt == arg->size)
return _URC_END_OF_STACK;
return _URC_NO_REASON;
}
int
__backtrace (void **array, int size)
{
int count;
struct trace_arg arg =
{
.array = array,
.unwind_link = __libc_unwind_link_get (),
.size = size,
.cnt = -1,
};
if (size <= 0)
return 0;
if (arg.unwind_link == NULL)
{
struct layout *current;
unsigned long fp, i7;
asm volatile ("mov %%fp, %0" : "=r"(fp));
asm volatile ("mov %%i7, %0" : "=r"(i7));
current = (struct layout *) (fp + BACKTRACE_STACK_BIAS);
array[0] = (void *) i7;
if (size == 1)
return 1;
backtrace_flush_register_windows();
for (count = 1; count < size; count++)
{
array[count] = current->return_address;
if (!current->next)
break;
current = (struct layout *) (current->next + BACKTRACE_STACK_BIAS);
}
}
else
{
UNWIND_LINK_PTR (arg.unwind_link, _Unwind_Backtrace)
(backtrace_helper, &arg);
/* _Unwind_Backtrace seems to put NULL address above
_start. Fix it up here. */
if (arg.cnt > 1 && arg.array[arg.cnt - 1] == NULL)
--arg.cnt;
count = arg.cnt != -1 ? arg.cnt : 0;
}
return count;
}
weak_alias (__backtrace, backtrace)
libc_hidden_def (__backtrace)
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