#!/bin/sh
# Copyright (c) 2015-2020 Solo5 Contributors
# Copyright (c) 2024 Romain Calascibetta
#
# This file is part of Gilbraltar, a bare-metal OS for Raspberry Pi.
#
# Permission to use, copy, modify, and/or distribute this software
# for any purpose with or without fee is hereby granted, provided
# that the above copyright notice and this permission notice appear
# in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
# WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
# AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
# CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
# OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
# NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
# CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

TARGET_CC="${TARGET_CC:-aarch64-linux-gnu-gcc}"
TARGET_LD="${TARGET_LD:-aarch64-linux-gnu-ld}"
TARGET_AR="${TARGET_AR:-aarch64-linux-gnu-ar}"
TARGET_NM="${TARGET_NM:-aarch64-linux-gnu-nm}"
TARGET_RANLIB="${TARGET_NM:-aarch64-linux-gnu-ranlib}"
TARGET_OBJCOPY="${TARGET_OBJCOPY:-aarch64-linux-gnu-objcopy}"
TARGET_OBJDUMP="${TARGET_OBJDUMP:-aarch64-linux-gnu-objdump}"
TARGET_READELF="${TARGET_OBJDUMP:-aarch64-linux-gnu-readelf}"
TARGET_STRIP="${TARGET_STRIP:-aarch64-linux-gnu-strip}"

prog_NAME="$(basename $0)"

cleanup()
{
    rm -f conftmp.c conftmp.d conftmp*.o
}

err()
{
    echo "${prog_NAME}: ERROR: $@" 1>&2
}

die()
{
    echo "${prog_NAME}: ERROR: $@" 1>&2
    cleanup
    exit 1
}

warn()
{
    echo "${prog_NAME}: WARNING: $@" 1>&2
}

usage()
{
    cat <<EOM 1>&2
usage: ${prog_NAME} [ OPTIONS ]

Configures the Gilbraltar build system.

Options:
    --prefix=DIR
        Installation prefix (default: /usr/local).

Environment variables affecting the build system configuration:
    HOST_CC
        C compiler used for host tools.

    TARGET_CC      (= $TARGET_CC)
    TARGET_LD      (= $TARGET_LD)
    TARGET_OBJCOPY (= $TARGET_OBJCOPY)
        C compiler, linker and objcopy used for target toolchain.
        
        Experimental: If a cross-toolchain is specified here, the resulting
        target toolchain and bindings will be cross-compiled to its
        architecture.
EOM
    exit 1
}

cc_maybe_gcc()
{
    ${CC} -dM -E - </dev/null | \
        grep -Eq '^#define __GNUC__ ([4-9]$|[1-9][0-9]+$)'
}

cc_is_clang()
{
    ${CC} -dM -E - </dev/null | grep -Eq '^#define __clang__ 1$'
}

cc_has_pie()
{
    ${CC} -dM -E - </dev/null | grep -Eq '^#define __PIE__ [1-9]$'
}

cc_is_gcc()
{
    cc_maybe_gcc && ! cc_is_clang
}

cc_check_option()
{
    ${CC} "$@" -x c -c -o /dev/null - <<EOM >/dev/null 2>&1
int main(int argc, char *argv[])
{
    return 0;
}
EOM
}

cc_check_header()
{
    ${CC} ${PKG_CFLAGS} -x c -o /dev/null - <<EOM >/dev/null 2>&1
#include <$@>

int main(int argc, char *argv[])
{
    return 0;
}
EOM
}

cc_check_lib()
{
    ${CC} -x c -o /dev/null - "$@" ${PKG_LIBS} <<EOM >/dev/null 2>&1
int main(int argc, char *argv[])
{
    return 0;
}
EOM
}

ld_is_lld()
{
    ${LD} --version 2>&1 | grep -q '^LLD'
}

# Check that the linker ${LD} is available and suitable for our purposes.
check_ld()
{
    echo -n "${prog_NAME}: Checking if ${LD} is available: "
    if [ -x "$(command -v ${LD})" ]; then
        echo "yes"
    else
        echo "no"
        return 1
    fi
    echo -n "${prog_NAME}: Checking if ${LD} is LLD: "
    if ld_is_lld; then
        echo "yes"
        # LLD < 8 chokes on the Xen ldscript, so refuse to use it.
        echo -n "${prog_NAME}: Checking if LLD ${LD} is LLVM 8 or newer: "
        if ${LD} --version 2>&1 | grep -q '^LLD [1-7]\.'; then
            echo "no"
            return 1
        else
            echo "yes"
        fi
    else
        echo "no"
    fi

    cat >conftmp.c <<EOM
int foo(void)
{
    return 1;
}
EOM
    ${CC} -c conftmp.c -o conftmp.o || return 1

    echo -n "${prog_NAME}: Checking if ${LD} understands ${TARGET_ARCH}: "
    if ! ${LD} -r -o conftmp1.o conftmp.o >/dev/null 2>&1; then
        echo "no"
        return 1
    else
        echo "yes"
    fi
    return 0
}

# Check that the objcopy ${OBJCOPY} is available and suitable for our purposes.
check_objcopy()
{
    echo -n "${prog_NAME}: Checking if ${OBJCOPY} is available: "
    if [ -x "$(command -v ${OBJCOPY})" ]; then
        echo "yes"
    else
        echo "no"
        return 1
    fi

    cat >conftmp.c <<EOM
int KEEP_ME(void)
{
    return 1;
}
int local(void)
{
    return 1;
}
EOM
    ${CC} -c conftmp.c -o conftmp.o || return 1

    # [Clang] A LLVM objcopy will understand any LLVM-supported architecture.
    # [GCC] A GNU objcopy will only understand the architecture it was
    # targetted for.
    echo -n "${prog_NAME}: Checking if ${OBJCOPY} understands ${TARGET_ARCH}: "
    if ! ${OBJCOPY} conftmp.o conftmp.o >/dev/null 2>&1; then
        echo "no"
        return 1
    else
        echo "yes"
    fi
    # [Clang] For LLVM objcopy, -w was introduced in
    # https://reviews.llvm.org/D66613 (release/12.x) and -G was introduced in
    # https://reviews.llvm.org/D50589 (release/8.x).
    echo -n "${prog_NAME}: Checking if ${OBJCOPY} understands -w -G: "
    if ! ${OBJCOPY} -w -G KEEP\* conftmp.o conftmp.o >/dev/null 2>&1; then
        echo "no"
        return 1
    else
        echo "yes"
    fi
    return 0
}

OPT_PREFIX=/usr/local
while [ $# -gt 0 ]; do
    OPT="$1"

    case "${OPT}" in
        --prefix=*)
            OPT_PREFIX="${OPT##*=}"
            ;;
        --help)
            usage
            ;;
        *)
            err "Unknown option: '${OPT}'"
            usage
            ;;
    esac

    shift
done

#
# Configure host tools based on HOST_CC.
#
HOST_CC=${HOST_CC:-cc}
HOST_CC_MACHINE=$(${HOST_CC} -dumpmachine)
[ $? -ne 0 ] &&
    die "Could not run '${HOST_CC} -dumpmachine', is your compiler working?"
echo "${prog_NAME}: Using ${HOST_CC} for host compiler (${HOST_CC_MACHINE})"

case ${HOST_CC_MACHINE} in
    x86_64-*linux*)
        CONFIG_HOST_ARCH=x86_64 CONFIG_HOST=Linux
        ;;
    aarch64-*linux*)
        CONFIG_HOST_ARCH=aarch64 CONFIG_HOST=Linux
        ;;
    powerpc64le-*linux*|ppc64le-*linux*)
        CONFIG_HOST_ARCH=ppc64le CONFIG_HOST=Linux
        ;;
    x86_64-*freebsd*)
        CONFIG_HOST_ARCH=x86_64 CONFIG_HOST=FreeBSD
        ;;
    amd64-*openbsd*)
        CONFIG_HOST_ARCH=x86_64 CONFIG_HOST=OpenBSD
        ;;
    *)
        die "Unsupported host toolchain: ${HOST_CC_MACHINE}"
        ;;
esac

# If no toolchain was requested, stop here.
# XXX De-duplicate the generation of Makeconf*?
if [ -n "${OPT_DISABLE_TOOLCHAIN}" ]; then
    cat <<EOM >Makeconf
# Generated by configure.sh
CONFIG_PREFIX=${OPT_PREFIX}
CONFIG_HOST_ARCH=${CONFIG_HOST_ARCH}
CONFIG_HOST=${CONFIG_HOST}
CONFIG_HOST_CC=${HOST_CC}
EOM
    sed -Ee 's/^([A-Z_]+)=(.*)$/\1="\2"/' Makeconf >Makeconf.sh
    cleanup
    exit 0
fi

#
# Configure target toolchain and bindings based on TARGET_{CC,LD,OBJCOPY}.
#
TARGET_CC="${TARGET_CC:-cc}"

echo -n "${prog_NAME}: Checking that ${TARGET_CC} works: "
cat >conftmp.c <<EOM
int foo(void)
{
    return 1;
}
EOM
if ! ${TARGET_CC} -c conftmp.c -o conftmp.o >/dev/null 2>&1; then
    echo "no"
    die "Could not find a working compiler for target toolchain"
else
    echo "yes"
fi
TARGET_CC_MACHINE=$(${TARGET_CC} -dumpmachine)

CONFIG_HVT= CONFIG_SPT= CONFIG_VIRTIO= CONFIG_MUEN= CONFIG_XEN=
case ${TARGET_CC_MACHINE} in
    x86_64-*|amd64-*)
        TARGET_ARCH=x86_64
        TARGET_LD_MAX_PAGE_SIZE=0x1000
        ;;
    aarch64-*)
        TARGET_ARCH=aarch64
        TARGET_LD_MAX_PAGE_SIZE=0x1000
        ;;
    powerpc64le-*|ppc64le-*)
        TARGET_ARCH=ppc64le
        TARGET_LD_MAX_PAGE_SIZE=0x10000
        ;;
    *)
        die "Unsupported target toolchain: ${TARGET_CC_MACHINE}"
        ;;
esac

TARGET_CC_CFLAGS=
TARGET_CC_IS_OPENBSD=
if CC="${TARGET_CC}" cc_is_clang; then
    TARGET_CC_CFLAGS=-nostdlibinc
    # XXX Clang warns for no good reason if -nostdlibinc is used and no
    # compliation is performed. We could work around this by using --config
    # which "claims" all command line arguments as "used", but this is easier
    # for now.
    TARGET_CC_CFLAGS="${TARGET_CC_CFLAGS} -Wno-unused-command-line-argument"
else
    TARGET_CC_CFLAGS=-nostdinc
fi
case ${TARGET_CC_MACHINE} in
    x86_64-*linux*|powerpc64le-*linux*|ppc64le-*linux*)
        # On x86_64 and PPC we need to ensure that TLS is not used for the
        # stack protector:
        # [GCC] -mstack-protector-guard=global is available from GCC 4.9.0.
        # [Clang] -mstack-protector-guard=global was introduced in
        # https://reviews.llvm.org/D88631 (release/12.x).
        CC="${TARGET_CC}" cc_check_option -mstack-protector-guard=global || \
            die "${TARGET_CC} does not support -mstack-protector-guard="
        TARGET_CC_CFLAGS="${TARGET_CC_CFLAGS} -mstack-protector-guard=global"
        ;;
    *openbsd*)
        # [Clang] OpenBSD's Clang needs to be told to switch off mitigations.
        TARGET_CC_CFLAGS="${TARGET_CC_CFLAGS} -mno-retpoline -fno-ret-protector"
        # [Clang] OpenBSD's LLVM/Clang uses a global stack protector guard, but
        # different symbols; see bindings/GNUmakefile.
        TARGET_CC_IS_OPENBSD=1
        ;;
esac

echo "${prog_NAME}:" \
    "Using ${TARGET_CC} for target compiler (${TARGET_CC_MACHINE})"

# TARGET_CC_LDFLAGS are used by "cc as linker"; TARGET_LD_LDFLAGS are used by
# the plain "ld" wrapper.
# TODO: Are there Linux distributions with toolchains configured to force PIE
# even if -static is used? If yes, these will need treatment similar to OpenBSD
# below, and/or disabling PIE in "cc".
TARGET_CC_LDFLAGS=
TARGET_LD_LDFLAGS=
case ${CONFIG_HOST} in
    Linux)
        # The "--build-id=none" nonsense is needed for "cc as a linker" to suppress any
        # generation of a .note.gnu.build-id, since our linker scripts don't
        # support it and Linux "cc" toolchains insist on adding it by default
        # which leads to linkers warning if it is enabled but the input section
        # is subsequently discarded.
        TARGET_LD="${TARGET_LD:-ld}"
        TARGET_OBJCOPY="${TARGET_OBJCOPY:-objcopy}"
        TARGET_CC_LDFLAGS="--build-id=none"
        ;;
    FreeBSD)
        TARGET_LD="${TARGET_LD:-ld.lld}"
        TARGET_OBJCOPY="${TARGET_OBJCOPY:-objcopy}"
        # FreeBSD's GNU ld is old and broken, refuse to use it.
        if ! LD="${TARGET_LD}" ld_is_lld; then
            err "${TARGET_LD} is not LLVM LLD"
            die "Using GNU LD is not supported on FreeBSD"
        fi
        ;;
    OpenBSD)
        TARGET_LD="${TARGET_LD:-ld.lld}"
        TARGET_OBJCOPY="${TARGET_OBJCOPY:-objcopy}"
        # OpenBSD's GNU ld is old and broken, refuse to use it.
        if ! LD="${TARGET_LD}" ld_is_lld; then
            err "${TARGET_LD} is not LLVM LLD"
            die "Using GNU LD is not supported on OpenBSD"
        fi
        # [LLD] OpenBSD's LLD needs to be explicitly told not to produce PIE
        # executables.
        TARGET_CC_LDFLAGS="-nopie"
        TARGET_LD_LDFLAGS="-nopie"
        ;;
    *)
        die "Unsupported host system: ${CONFIG_HOST}"
        ;;
esac
# [Clang] Force Clang to use the right TARGET_LD when run as "cc as linker".
# -fuse-ld= is braindead and accepts either a "flavour" (e.g. "lld") or an
# absolute path; we try with the latter.
# TODO XXX: This is fragile, but works for the default cases for now.
# TODO document: This won't work with clang "bare metal" targets.
if CC="${TARGET_CC}" cc_is_clang; then
    REAL_TARGET_LD="$(command -v ${TARGET_LD})"
    [ ! -x "${REAL_TARGET_LD}" ] && \
        die "Cannot determine absolute path for ${TARGET_LD}"
    TARGET_CC_LDFLAGS="${TARGET_CC_LDFLAGS} -fuse-ld=${REAL_TARGET_LD}"
fi
if ! CC="${TARGET_CC}" LD="${TARGET_LD}" check_ld; then
    die "Could not find a working target linker"
fi
if ! CC="${TARGET_CC}" OBJCOPY="${TARGET_OBJCOPY}" check_objcopy; then
    die "Could not find a working target objcopy"
fi

if CC="${TARGET_CC}" cc_is_gcc; then
    LIBGCC=$(${TARGET_CC} -print-libgcc-file-name)
    TARGET_CC_LDFLAGS="${TARGET_CC_LDFLAGS} -L $(dirname ${LIBGCC})"
fi

echo "${prog_NAME}: Using ${TARGET_LD} for target linker"
echo "${prog_NAME}: Using ${TARGET_OBJCOPY} for target objcopy"

TARGET_TRIPLE="${TARGET_ARCH}-gilbraltar-ocaml"
echo "${prog_NAME}: Target toolchain triple is ${TARGET_TRIPLE}"

#
# Generate Makeconf, to be included by Makefiles.
#
cat <<EOM >Makeconf
# Generated by configure.sh
CONFIG_PREFIX=${OPT_PREFIX}
CONFIG_HOST_ARCH=${CONFIG_HOST_ARCH}
CONFIG_HOST=${CONFIG_HOST}
CONFIG_HOST_CC=${HOST_CC}
CONFIG_TARGET_ARCH=${TARGET_ARCH}
CONFIG_TARGET_TRIPLE=${TARGET_TRIPLE}
CONFIG_TARGET_CC=${TARGET_CC}
CONFIG_TARGET_CC_CFLAGS=${TARGET_CC_CFLAGS}
CONFIG_TARGET_CC_LDFLAGS=${TARGET_CC_LDFLAGS}
CONFIG_TARGET_CC_IS_OPENBSD=${TARGET_CC_IS_OPENBSD}
CONFIG_TARGET_LD=${TARGET_LD}
CONFIG_TARGET_LD_LDFLAGS=${TARGET_LD_LDFLAGS}
CONFIG_TARGET_LD_MAX_PAGE_SIZE=${TARGET_LD_MAX_PAGE_SIZE}
CONFIG_TARGET_NM=${TARGET_NM}
CONFIG_TARGET_AR=${TARGET_AR}
CONFIG_TARGET_RANLIB=${TARGET_RANLIB}
CONFIG_TARGET_OBJCOPY=${TARGET_OBJCOPY}
CONFIG_TARGET_OBJDUMP=${TARGET_OBJDUMP}
CONFIG_TARGET_READELF=${TARGET_READELF}
CONFIG_TARGET_STRIP=${TARGET_STRIP}
EOM

#
# Generate Makeconf.sh, to be included by shell scripts.
#
sed -Ee 's/^([A-Z_]+)=(.*)$/\1="\2"/' Makeconf >Makeconf.sh

cleanup