#!/bin/sh

  # SPDX-License-Identifier: GPL-2.0

  # Disassemble the Code: line in Linux oopses
  # usage: decodecode < oops.file
  #
  # options: set env. variable AFLAGS=options to pass options to "as";
  # e.g., to decode an i386 oops on an x86_64 system, use:
  # AFLAGS=--32 decodecode < 386.oops

  # PC=hex - the PC (program counter) the oops points to

  cleanup() {

  	rm -f $T $T.s $T.o $T.oo $T.aa $T.dis

  	exit 1
  }
  
  die() {
  	echo "$@"
  	exit 1
  }
  
  trap cleanup EXIT
  
  T=`mktemp` || die "cannot create temp file"

  code=

  cont=

  
  while read i ; do
  
  case "$i" in
  *Code:*)
  	code=$i

  	cont=yes
  	;;
  *)
  	[ -n "$cont" ] && {
  		xdump="$(echo $i | grep '^[[:xdigit:]<>[:space:]]\+$')"
  		if [ -n "$xdump" ]; then
  			code="$code $xdump"
  		else
  			cont=
  		fi
  	}

  	;;
  esac
  
  done
  
  if [ -z "$code" ]; then

  	rm $T

  	exit
  fi
  
  echo $code
  code=`echo $code | sed -e 's/.*Code: //'`

  width=`expr index "$code" ' '`

  width=$((($width-1)/2))

  case $width in
  1) type=byte ;;
  2) type=2byte ;;
  4) type=4byte ;;
  esac

  if [ -z "$ARCH" ]; then
      case `uname -m` in
  	aarch64*) ARCH=arm64 ;;
  	arm*) ARCH=arm ;;
      esac
  fi

  # Params: (tmp_file, pc_sub)

  disas() {

  	t=$1
  	pc_sub=$2
  
  	${CROSS_COMPILE}as $AFLAGS -o $t.o $t.s > /dev/null 2>&1

  	if [ "$ARCH" = "arm" ]; then
  		if [ $width -eq 2 ]; then

  			OBJDUMPFLAGS="-M force-thumb"
  		fi

  		${CROSS_COMPILE}strip $t.o

  	fi

  	if [ "$ARCH" = "arm64" ]; then
  		if [ $width -eq 4 ]; then
  			type=inst
  		fi

  		${CROSS_COMPILE}strip $t.o

  	fi

  	if [ $pc_sub -ne 0 ]; then
  		if [ $PC ]; then
  			adj_vma=$(( $PC - $pc_sub ))
  			OBJDUMPFLAGS="$OBJDUMPFLAGS --adjust-vma=$adj_vma"
  		fi
  	fi
  
  	${CROSS_COMPILE}objdump $OBJDUMPFLAGS -S $t.o | \
  		grep -v "/tmp\|Disassembly\|\.text\|^$" > $t.dis 2>&1

  }

  marker=`expr index "$code" "\<"`
  if [ $marker -eq 0 ]; then
  	marker=`expr index "$code" "\("`
  fi

  touch $T.oo

  if [ $marker -ne 0 ]; then

  	# 2 opcode bytes and a single space
  	pc_sub=$(( $marker / 3 ))

  	echo All code >> $T.oo
  	echo ======== >> $T.oo
  	beforemark=`echo "$code"`

  	echo -n "	.$type 0x" > $T.s
  	echo $beforemark | sed -e 's/ /,0x/g; s/[<>()]//g' >> $T.s

  	disas $T $pc_sub

  	cat $T.dis >> $T.oo
  	rm -f $T.o $T.s $T.dis

  
  # and fix code at-and-after marker
  	code=`echo "$code" | cut -c$((${marker} + 1))-`
  fi

  echo Code starting with the faulting instruction  > $T.aa
  echo =========================================== >> $T.aa

  code=`echo $code | sed -e 's/ [<(]/ /;s/[>)] / /;s/ /,0x/g; s/[>)]$//'`
  echo -n "	.$type 0x" > $T.s

  echo $code >> $T.s

  disas $T 0

  cat $T.dis >> $T.aa

  # (lines of whole $T.oo) - (lines of $T.aa, i.e. "Code starting") + 3,
  # i.e. the title + the "===..=" line (sed is counting from 1, 0 address is
  # special)
  faultlinenum=$(( $(wc -l $T.oo  | cut -d" " -f1) - \
  		 $(wc -l $T.aa  | cut -d" " -f1) + 3))

  faultline=`cat $T.dis | head -1 | cut -d":" -f2-`

  faultline=`echo "$faultline" | sed -e 's/\[/\\\[/g; s/\]/\\\]/g'`

  cat $T.oo | sed -e "${faultlinenum}s/^\([^:]*:\)\(.*\)/\1\*\2\t\t<-- trapping instruction/"

  echo
  cat $T.aa
  cleanup