linux-yocto/scripts/decodecode

#!/bin/bash

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

faultlinenum=1

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 ;;
3. 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

}

Match the maximum number of opcode bytes from @op_bytes contained within

@opline

Params:

@op_bytes: The string of bytes from the Code: line

@opline: The disassembled line coming from objdump

Returns:

The max number of opcode bytes from the beginning of @op_bytes which match

the opcode bytes in the objdump line.

get_substr_opcode_bytes_num() { local op_bytes=$1 local opline=$2

local retval=0
substr=""

for opc in $op_bytes;
do
	substr+="$opc"

	# return if opcode bytes do not match @opline anymore
	if ! echo $opline | grep -q "$substr";
	then
		break
	fi

	# add trailing space
	substr+=" "
	retval=$((retval+1))
done

return $retval

}

Return the line number in objdump output to where the IP marker in the Code:

line points to

Params:

@all_code: code in bytes without the marker

@dis_file: disassembled file

@ip_byte: The byte to which the IP points to

get_faultlinenum() { local all_code="$1" local dis_file="$2"

# num bytes including IP byte
local num_bytes_ip=$(( $3 + 1 * $width ))

# Add the two header lines (we're counting from 1).
local retval=3

# remove marker
all_code=$(echo $all_code | sed -e 's/[<>()]//g')

while read line
do
	get_substr_opcode_bytes_num "$all_code" "$line"
	ate_opcodes=$?

	if ! (( $ate_opcodes )); then
		continue
	fi

	num_bytes_ip=$((num_bytes_ip - ($ate_opcodes * $width) ))
	if (( $num_bytes_ip <= 0 )); then
		break
	fi

	# Delete matched opcode bytes from all_code. For that, compute
	# how many chars those opcodes are represented by and include
	# trailing space.
	#
	# a byte is 2 chars, ate_opcodes is also the number of trailing
	# spaces
	del_chars=$(( ($ate_opcodes * $width * 2) + $ate_opcodes ))

	all_code=$(echo $all_code | sed -e "s!^.\{$del_chars\}!!")

	let "retval+=1"

done < $dis_file

return $retval

}

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

touch $T.oo if [ $marker -ne 0 ]; then # How many bytes to subtract from the program counter # in order to get to the beginning virtual address of the # Code: pc_sub=$(( (($marker - 1) / (2 * $width + 1)) * $width )) 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

get_faultlinenum "$code" "$T.dis" $pc_sub
faultlinenum=$?

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

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

fi

echo Code starting with the faulting instruction > $T.aa echo =========================================== >> $T.aa code=echo $code | sed -e 's/\r//;s/ [<(]/ /;s/[>)] / /;s/ /,0x/g; s/[>)]$//' echo -n " .$type 0x" > $T.s echo $code >> $T.s disas $T 0 cat $T.dis >> $T.aa

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