qemu/scripts/qemu-binfmt-conf.sh
Andrea Bolognani 1887cf2368 binfmt: Add --ignore-family option
Until now, the script has worked under the assumption that a
host CPU can run binaries targeting any CPU in the same family.
That's a fair enough assumption when it comes to running i386
binaries on x86_64, but it doesn't quite apply in the general
case.

For example, while riscv64 CPUs could theoretically run riscv32
applications natively, in practice there exist few (if any?)
CPUs that implement the necessary silicon; moreover, even if you
had one such CPU, your host OS would most likely not have
enabled the necessary kernel bits.

This new option gives distro packagers the ability to opt out of
the assumption, likely on a per-architecture basis, and make
things work out of the box for a larger fraction of their user
base.

As an interesting side effect, this makes it possible to enable
execution of 64-bit binaries on 32-bit CPUs of the same family,
which is a perfectly valid use case that apparently hadn't been
considered until now.

Link: https://src.fedoraproject.org/rpms/qemu/pull-request/72
Thanks: David Abdurachmanov <davidlt@rivosinc.com>
Thanks: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-ID: <20250127182924.103510-4-abologna@redhat.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2025-03-04 15:42:54 +10:00

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Executable file

#!/bin/sh
# Enable automatic program execution by the kernel.
qemu_target_list="i386 i486 alpha arm armeb sparc sparc32plus sparc64 \
ppc ppc64 ppc64le m68k mips mipsel mipsn32 mipsn32el mips64 mips64el \
sh4 sh4eb s390x aarch64 aarch64_be hppa riscv32 riscv64 xtensa xtensaeb \
microblaze microblazeel or1k x86_64 hexagon loongarch64"
i386_magic='\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x03\x00'
i386_mask='\xff\xff\xff\xff\xff\xfe\xfe\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
i386_family=i386
i486_magic='\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x06\x00'
i486_mask='\xff\xff\xff\xff\xff\xfe\xfe\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
i486_family=i386
x86_64_magic='\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x3e\x00'
x86_64_mask='\xff\xff\xff\xff\xff\xfe\xfe\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
x86_64_family=i386
alpha_magic='\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x26\x90'
alpha_mask='\xff\xff\xff\xff\xff\xfe\xfe\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
alpha_family=alpha
arm_magic='\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00'
arm_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
arm_family=arm
armeb_magic='\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28'
armeb_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
armeb_family=armeb
sparc_magic='\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x02'
sparc_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
sparc_family=sparc
sparc32plus_magic='\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x12'
sparc32plus_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
sparc32plus_family=sparc
sparc64_magic='\x7fELF\x02\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x2b'
sparc64_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
sparc64_family=sparc
ppc_magic='\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x14'
ppc_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
ppc_family=ppc
ppc64_magic='\x7fELF\x02\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x15'
ppc64_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
ppc64_family=ppc
ppc64le_magic='\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x15\x00'
ppc64le_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\x00'
ppc64le_family=ppcle
m68k_magic='\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x04'
m68k_mask='\xff\xff\xff\xff\xff\xff\xfe\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
m68k_family=m68k
# FIXME: We could use the other endianness on a MIPS host.
mips_magic='\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x08\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
mips_mask='\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20'
mips_family=mips
mipsel_magic='\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x08\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
mipsel_mask='\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00\x00\x00'
mipsel_family=mips
mipsn32_magic='\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x08\x00\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20'
mipsn32_mask='\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20'
mipsn32_family=mips
mipsn32el_magic='\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x08\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00\x00\x00'
mipsn32el_mask='\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x20\x00\x00\x00'
mipsn32el_family=mips
mips64_magic='\x7fELF\x02\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x08'
mips64_mask='\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
mips64_family=mips
mips64el_magic='\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x08\x00'
mips64el_mask='\xff\xff\xff\xff\xff\xff\xff\x00\x00\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
mips64el_family=mips
sh4_magic='\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x2a\x00'
sh4_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
sh4_family=sh4
sh4eb_magic='\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x2a'
sh4eb_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
sh4eb_family=sh4
s390x_magic='\x7fELF\x02\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x16'
s390x_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
s390x_family=s390x
aarch64_magic='\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7\x00'
aarch64_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
aarch64_family=arm
aarch64_be_magic='\x7fELF\x02\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7'
aarch64_be_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
aarch64_be_family=armeb
hppa_magic='\x7f\x45\x4c\x46\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x0f'
hppa_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
hppa_family=hppa
riscv32_magic='\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xf3\x00'
riscv32_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
riscv32_family=riscv
riscv64_magic='\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xf3\x00'
riscv64_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
riscv64_family=riscv
xtensa_magic='\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x5e\x00'
xtensa_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
xtensa_family=xtensa
xtensaeb_magic='\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x5e'
xtensaeb_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
xtensaeb_family=xtensaeb
microblaze_magic='\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xba\xab'
microblaze_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
microblaze_family=microblaze
microblazeel_magic='\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xab\xba'
microblazeel_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
microblazeel_family=microblazeel
or1k_magic='\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x5c'
or1k_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
or1k_family=or1k
hexagon_magic='\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xa4\x00'
hexagon_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
hexagon_family=hexagon
loongarch64_magic='\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x02\x01'
loongarch64_mask='\xff\xff\xff\xff\xff\xff\xff\xfc\x00\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff'
loongarch64_family=loongarch
# Converts the name of a host CPU architecture to the corresponding QEMU
# target.
#
# FIXME: This can probably be simplified a lot by dropping most entries.
# Remember that the script is only used on Linux, so we only need to
# handle the strings Linux uses to report the host CPU architecture.
qemu_normalize() {
cpu="$1"
case "$cpu" in
i[3-6]86)
echo "i386"
;;
amd64)
echo "x86_64"
;;
powerpc)
echo "ppc"
;;
ppc64el)
echo "ppc64le"
;;
armel|armhf|armv[4-9]*l)
echo "arm"
;;
armv[4-9]*b)
echo "armeb"
;;
arm64)
echo "aarch64"
;;
*)
echo "$cpu"
;;
esac
}
usage() {
cat <<EOF
Usage: qemu-binfmt-conf.sh [--qemu-path PATH][--debian][--systemd CPU]
[--help][--credential yes|no][--exportdir PATH]
[--persistent yes|no][--qemu-suffix SUFFIX]
[--preserve-argv0 yes|no]
Configure binfmt_misc to use qemu interpreter
--help: display this usage
--qemu-path: set path to qemu interpreter ($QEMU_PATH)
--qemu-suffix: add a suffix to the default interpreter name
--debian: don't write into /proc,
instead generate update-binfmts templates
--systemd: don't write into /proc,
instead generate file for systemd-binfmt.service
for the given CPU. If CPU is "ALL", generate a
file for all known cpus
--exportdir: define where to write configuration files
(default: $SYSTEMDDIR or $DEBIANDIR)
--credential: if yes, credential and security tokens are
calculated according to the binary to interpret
--persistent: if yes, the interpreter is loaded when binfmt is
configured and remains in memory. All future uses
are cloned from the open file.
--ignore-family: if yes, it is assumed that the host CPU (e.g. riscv64)
can't natively run programs targeting a CPU that is
part of the same family (e.g. riscv32).
--preserve-argv0 preserve argv[0]
To import templates with update-binfmts, use :
sudo update-binfmts --importdir ${EXPORTDIR:-$DEBIANDIR} --import qemu-CPU
To remove interpreter, use :
sudo update-binfmts --package qemu-CPU --remove qemu-CPU $QEMU_PATH
With systemd, binfmt files are loaded by systemd-binfmt.service
The environment variable HOST_ARCH allows to override 'uname' to generate
configuration files for a different architecture than the current one.
where CPU is one of:
$qemu_target_list
EOF
}
qemu_check_access() {
if [ ! -w "$1" ] ; then
echo "ERROR: cannot write to $1" 1>&2
exit 1
fi
}
qemu_check_bintfmt_misc() {
# load the binfmt_misc module
if [ ! -d /proc/sys/fs/binfmt_misc ]; then
if ! /sbin/modprobe binfmt_misc ; then
exit 1
fi
fi
if [ ! -f /proc/sys/fs/binfmt_misc/register ]; then
if ! mount binfmt_misc -t binfmt_misc /proc/sys/fs/binfmt_misc ; then
exit 1
fi
fi
qemu_check_access /proc/sys/fs/binfmt_misc/register
}
installed_dpkg() {
dpkg --status "$1" > /dev/null 2>&1
}
qemu_check_debian() {
if [ ! -e /etc/debian_version ] ; then
echo "WARNING: your system is not a Debian based distro" 1>&2
elif ! installed_dpkg binfmt-support ; then
echo "WARNING: package binfmt-support is needed" 1>&2
fi
qemu_check_access "$EXPORTDIR"
}
qemu_check_systemd() {
if ! systemctl -q is-enabled systemd-binfmt.service ; then
echo "WARNING: systemd-binfmt.service is missing or disabled" 1>&2
fi
qemu_check_access "$EXPORTDIR"
}
qemu_generate_register() {
flags=""
if [ "$CREDENTIAL" = "yes" ] ; then
flags="OC"
fi
if [ "$PERSISTENT" = "yes" ] ; then
flags="${flags}F"
fi
if [ "$PRESERVE_ARG0" = "yes" ] ; then
flags="${flags}P"
fi
echo ":qemu-$cpu:M::$magic:$mask:$qemu:$flags"
}
qemu_register_interpreter() {
echo "Setting $qemu as binfmt interpreter for $cpu"
qemu_generate_register > /proc/sys/fs/binfmt_misc/register
}
qemu_generate_systemd() {
echo "Setting $qemu as binfmt interpreter for $cpu for systemd-binfmt.service"
qemu_generate_register > "$EXPORTDIR/qemu-$cpu.conf"
}
qemu_generate_debian() {
cat > "$EXPORTDIR/qemu-$cpu" <<EOF
package qemu-$cpu
interpreter $qemu
magic $magic
mask $mask
credentials $CREDENTIAL
preserve $PRESERVE_ARG0
fix_binary $PERSISTENT
EOF
}
qemu_set_binfmts() {
# probe cpu type
host_cpu=$(qemu_normalize ${HOST_ARCH:-$(uname -m)})
host_family=$(eval echo \$${host_cpu}_family)
if [ "$host_family" = "" ] ; then
echo "INTERNAL ERROR: unknown host cpu $host_cpu" 1>&2
exit 1
fi
# register the interpreter for each cpu except for the native one
for cpu in ${qemu_target_list} ; do
magic=$(eval echo \$${cpu}_magic)
mask=$(eval echo \$${cpu}_mask)
family=$(eval echo \$${cpu}_family)
target="$cpu"
if [ "$cpu" = "i486" ] ; then
target="i386"
fi
qemu="$QEMU_PATH/qemu-$target$QEMU_SUFFIX"
if [ "$magic" = "" ] || [ "$mask" = "" ] || [ "$family" = "" ] ; then
echo "INTERNAL ERROR: unknown cpu $cpu" 1>&2
continue
fi
if [ "$host_family" = "$family" ] ; then
# When --ignore-family is used, we have to generate rules even
# for targets that are in the same family as the host CPU. The
# only exception is of course when the CPU types exactly match
if [ "$target" = "$host_cpu" ] || [ "$IGNORE_FAMILY" = "no" ] ; then
continue
fi
fi
$BINFMT_SET
done
}
CHECK=qemu_check_bintfmt_misc
BINFMT_SET=qemu_register_interpreter
SYSTEMDDIR="/etc/binfmt.d"
DEBIANDIR="/usr/share/binfmts"
QEMU_PATH=/usr/local/bin
CREDENTIAL=no
PERSISTENT=no
PRESERVE_ARG0=no
QEMU_SUFFIX=""
IGNORE_FAMILY=no
_longopts="debian,systemd:,qemu-path:,qemu-suffix:,exportdir:,help,credential:,\
persistent:,preserve-argv0:,ignore-family:"
options=$(getopt -o ds:Q:S:e:hc:p:g:F:i: -l ${_longopts} -- "$@")
eval set -- "$options"
while true ; do
case "$1" in
-d|--debian)
CHECK=qemu_check_debian
BINFMT_SET=qemu_generate_debian
EXPORTDIR=${EXPORTDIR:-$DEBIANDIR}
;;
-s|--systemd)
CHECK=qemu_check_systemd
BINFMT_SET=qemu_generate_systemd
EXPORTDIR=${EXPORTDIR:-$SYSTEMDDIR}
shift
# check given cpu is in the supported CPU list
if [ "$1" != "ALL" ] ; then
for cpu in ${qemu_target_list} ; do
if [ "$cpu" = "$1" ] ; then
break
fi
done
if [ "$cpu" = "$1" ] ; then
qemu_target_list="$1"
else
echo "ERROR: unknown CPU \"$1\"" 1>&2
usage
exit 1
fi
fi
;;
-Q|--qemu-path)
shift
QEMU_PATH="$1"
;;
-F|--qemu-suffix)
shift
QEMU_SUFFIX="$1"
;;
-e|--exportdir)
shift
EXPORTDIR="$1"
;;
-h|--help)
usage
exit 1
;;
-c|--credential)
shift
CREDENTIAL="$1"
;;
-p|--persistent)
shift
PERSISTENT="$1"
;;
-g|--preserve-argv0)
shift
PRESERVE_ARG0="$1"
;;
-i|--ignore-family)
shift
IGNORE_FAMILY="$1"
;;
*)
break
;;
esac
shift
done
$CHECK
qemu_set_binfmts