/* Copyright (C) 2005-2018 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

   <http://www.gnu.org/licenses/>.  */

#include <stdio.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)