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/* Copyright (C) 2005-2020 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 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sysdep.h>
#include <signal.h>
#include <execinfo.h>
extern int
_identify_sighandler (unsigned long fp, unsigned long pc,
unsigned long *pprev_fp, unsigned long *pprev_pc,
unsigned long *retaddr);
static inline long
get_frame_size (unsigned long instr)
{
return abs ((short signed) (instr & 0xFFFF));
}
static unsigned long *
find_frame_creation (unsigned long *pc)
{
int i;
/* NOTE: Distance to search is arbitrary.
250 works well for most things,
750 picks up things like tcp_recvmsg,
1000 needed for fat_fill_super. */
for (i = 0; i < 1000; i++, pc--)
{
unsigned long instr;
unsigned long frame_size;
instr = *pc;
/* Is the instruction of the form
addik r1, r1, foo ? */
if ((instr & 0xFFFF0000) != 0x30210000)
continue;
frame_size = get_frame_size (instr);
if ((frame_size < 8) || (frame_size & 3))
return NULL;
return pc;
}
return NULL;
}
static int
lookup_prev_stack_frame (unsigned long fp, unsigned long pc,
unsigned long *pprev_fp, unsigned long *pprev_pc,
unsigned long *retaddr)
{
unsigned long *prologue = NULL;
int is_signalhandler = _identify_sighandler (fp, pc, pprev_fp,
pprev_pc, retaddr);
if (!is_signalhandler)
{
prologue = find_frame_creation ((unsigned long *) pc);
if (prologue)
{
long frame_size = get_frame_size (*prologue);
*pprev_fp = fp + frame_size;
if (*retaddr != 0)
*pprev_pc = *retaddr;
else
*pprev_pc = *(unsigned long *) fp;
*retaddr = 0;
if (!*pprev_pc || (*pprev_pc & 3))
prologue=0;
}
else
{
*pprev_pc = 0;
*pprev_fp = fp;
*retaddr = 0;
}
}
return (!*pprev_pc || (*pprev_pc & 3)) ? -1 : 0;
}
int
__backtrace (void **array, int size)
{
unsigned long pc, fp;
unsigned long ppc, pfp;
/* Return address(r15) is required in the signal handler case, since the
return address of the function which causes the signal may not be
recorded in the stack. */
unsigned long retaddr;
int count;
int rc = 0;
if (size <= 0)
return 0;
__asm__ __volatile__ ("mfs %0, rpc"
: "=r"(pc));
__asm__ __volatile__ ("add %0, r1, r0"
: "=r"(fp));
array[0] = (void *) pc;
retaddr = 0;
for (count = 1; count < size; count++)
{
rc = lookup_prev_stack_frame (fp, pc, &pfp, &ppc, &retaddr);
fp = pfp;
pc = ppc;
array[count] = (void *) pc;
if (rc)
return count;
}
return count;
}
weak_alias (__backtrace, backtrace)
libc_hidden_def (__backtrace)
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