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Will Deacon be9fa663d3 scripts/decodecode: fix decoding for AArch64 (arm64) instructions

There are a couple of problems with the decodecode script and arm64:

1. AArch64 objdump refuses to disassemble .4byte directives as instructions,
   insisting that they are data values and displaying them as:

	a94153f3	.word	0xa94153f3		<-- trapping instruction

   This is resolved by using the .inst directive instead.

2. Disassembly of branch instructions attempts to provide the target as
   an offset from a symbol, e.g.:

   0:	34000082	cbz	w2, 10 <.text+0x10>

  however this falls foul of the grep -v, which matches lines containing
  ".text" and ends up removing all branch instructions from the dump.

This patch resolves both issues by using the .inst directive for 4-byte
quantities on arm64 and stripping the resulting binaries (as is done on
arm already) to remove the mapping symbols.

Link: http://lkml.kernel.org/r/1506596147-23630-1-git-send-email-will.deacon@arm.com
Signed-off-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2018-01-19 10:09:41 -08:00

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#!/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

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=

while read i ; do

case "$i" in Code:) code=$i ;; 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

type=byte ;;
type=2byte ;;
type=4byte ;; esac

disas() { ${CROSS_COMPILE}as $AFLAGS -o $1.o $1.s > /dev/null 2>&1

if [ "$ARCH" = "arm" ]; then
	if [ $width -eq 2 ]; then
		OBJDUMPFLAGS="-M force-thumb"
	fi

	${CROSS_COMPILE}strip $1.o
fi

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

	${CROSS_COMPILE}strip $1.o
fi

${CROSS_COMPILE}objdump $OBJDUMPFLAGS -S $1.o | \
	grep -v "/tmp\|Disassembly\|\.text\|^$" > $1.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 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 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 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

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