linux/scripts/decodecode
Ivan Delalande e08df079b2 scripts/decodecode: fix trapping instruction formatting
If the trapping instruction contains a ':', for a memory access through
segment registers for example, the sed substitution will insert the '*'
marker in the middle of the instruction instead of the line address:

	2b:   65 48 0f c7 0f          cmpxchg16b %gs:*(%rdi)          <-- trapping instruction

I started to think I had forgotten some quirk of the assembly syntax
before noticing that it was actually coming from the script.  Fix it to
add the address marker at the right place for these instructions:

	28:   49 8b 06                mov    (%r14),%rax
	2b:*  65 48 0f c7 0f          cmpxchg16b %gs:(%rdi)           <-- trapping instruction
	30:   0f 94 c0                sete   %al

Fixes: 18ff44b189 ("scripts/decodecode: make faulting insn ptr more robust")
Signed-off-by: Ivan Delalande <colona@arista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: http://lkml.kernel.org/r/20200419223653.GA31248@visor
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-05-07 19:27:20 -07:00

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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=
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
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