mkosi: Add support for building with LLVM

Now you can do mkosi -E LLVM=1 to build with clang+lld. This includes support for building with sanitizers.
2025-02-28 05:57:33 +03:00 · 2024-06-01 12:27:45 +02:00 · 2024-06-01 12:27:45 +02:00 · 02bfe0fa1b
commit 02bfe0fa1b
parent 4548e53ee5
9 changed files with 99 additions and 11 deletions
--- a/mkosi.images/system/mkosi.conf
+++ b/mkosi.images/system/mkosi.conf
@ -26,6 +26,7 @@ Packages=
        attr
        bash-completion
        bpftrace
+        clang
        coreutils
        curl
        diffutils
@ -42,6 +43,8 @@ Packages=
        kmod
        knot
        less
+        lld
+        llvm
        lvm2
        man
        mdadm
--- a/mkosi.images/system/mkosi.conf.d/10-arch/mkosi.build.chroot
+++ b/mkosi.images/system/mkosi.conf.d/10-arch/mkosi.build.chroot
@ -24,12 +24,29 @@ ln --symbolic . "pkg/$ID/src"
 # shellcheck source=/dev/null
 . /etc/makepkg.conf

+CFLAGS="-O${OPTIMIZATION:-0} -Wp,-U_FORTIFY_SOURCE"
+if ((LLVM)); then
+    # TODO: Remove -fno-sanitize-function when https://github.com/systemd/systemd/issues/29972 is fixed.
+    CFLAGS="$CFLAGS -shared-libasan -fno-sanitize=function"
+fi
+
+LDFLAGS=""
+if ((LLVM)) && [[ -n "$SANITIZERS" ]]; then
+    LDFLAGS="$LDFLAGS -Wl,-rpath=$(clang --print-file-name="")lib/linux"
+fi
+
 # Override the default options. Disable FORTIFY_SOURCE because it doesn't work with O0. We specifically
 # disable "strip", "zipman" and "lto" as they slow down builds significantly. OPTIONS= cannot be overridden
 # on the makepkg command line so we append to /etc/makepkg.conf instead. The rootfs is overlaid with a
 # writable tmpfs during the build script so these changes don't end up in the image itself.
 tee --append /etc/makepkg.conf >/dev/null <<EOF
-CFLAGS="$CFLAGS -O${OPTIMIZATION:-0} -Wp,-U_FORTIFY_SOURCE"
+export CC="$( ((LLVM)) && echo clang || echo gcc)"
+export CXX="$( ((LLVM)) && echo clang++ || echo g++)"
+export CC_LD="$( ((LLVM)) && echo lld)"
+export CXX_LD="$( ((LLVM)) && echo lld)"
+export CFLAGS="\$CFLAGS $CFLAGS"
+export CXXFLAGS="\$CXXFLAGS $CFLAGS"
+export LDFLAGS="\$LDFLAGS $LDFLAGS"
 OPTIONS=(
    docs
    !libtool
--- a/mkosi.images/system/mkosi.conf.d/10-arch/mkosi.conf
+++ b/mkosi.images/system/mkosi.conf.d/10-arch/mkosi.conf
@ -21,6 +21,7 @@ Packages=
        bind
        bpf
        btrfs-progs
+        compiler-rt
        compsize
        cryptsetup
        dbus-broker
@ -62,6 +63,7 @@ Packages=

 InitrdPackages=
        btrfs-progs
+        compiler-rt
        tpm2-tools

 InitrdVolatilePackages=
--- a/mkosi.images/system/mkosi.conf.d/10-centos-fedora/mkosi.build.chroot
+++ b/mkosi.images/system/mkosi.conf.d/10-centos-fedora/mkosi.build.chroot
@ -37,11 +37,29 @@ DIST="$(rpm --eval %dist)"
 ARCH="$(rpm --eval %_arch)"
 SRCDEST="/usr/src/debug/systemd-$VERSION-${RELEASE}${DIST}.$ARCH"

+COMMON_MACRO_OVERRIDES=(
+    --define "toolchain $( ((LLVM)) && echo clang || echo gcc)"
+    --define "_fortify_level 0"
+    --undefine _lto_cflags
+    # TODO: Remove once redhat-rpm-config 292 is available everywhere.
+    --define "_hardening_clang_cflags --config=/usr/lib/rpm/redhat/redhat-hardened-clang.cfg"
+    --define "_hardening_clang_ldflags --config=/usr/lib/rpm/redhat/redhat-hardened-clang-ld.cfg"
+)
+
 # TODO: Drop -U_FORTIFY_SOURCE when we switch to CentOS Stream 10.
-CFLAGS="$(rpm --define "_fortify_level 0" --undefine _lto_cflags --eval %build_cflags) -O${OPTIMIZATION:-0} -Wp,-U_FORTIFY_SOURCE"
+CFLAGS="-O${OPTIMIZATION:-0} -Wp,-U_FORTIFY_SOURCE"
 if ((WITH_DEBUG)); then
    CFLAGS="$CFLAGS -fdebug-prefix-map=../src=$SRCDEST"
 fi
+if ((LLVM)); then
+    # TODO: Remove -fno-sanitize-function when https://github.com/systemd/systemd/issues/29972 is fixed.
+    CFLAGS="$CFLAGS -shared-libasan -fno-sanitize=function"
+fi
+
+LDFLAGS=""
+if ((LLVM)) && [[ -n "$SANITIZERS" ]]; then
+    LDFLAGS="$LDFLAGS -Wl,-rpath=$(dirname "$(clang --print-file-name=libclang_rt.asan.so)")"
+fi

 IFS=
 # TODO: Replace meson_build and meson_install overrides with "--undefine __meson_verbose" once
@ -49,7 +67,9 @@ IFS=
 # shellcheck disable=SC2046
 env \
 ANNOBIN="no-active-checks" \
-rpmbuild \
+CC_LD="$( ((LLVM)) && echo lld)" \
+CXX_LD="$( ((LLVM)) && echo lld)" \
+    rpmbuild \
    -bb \
    --build-in-place \
    --with upstream \
@ -64,7 +84,10 @@ rpmbuild \
    $( ((WITH_DEBUG)) || echo "--define=debug_package %{nil}") \
    --define "version_override $VERSION" \
    --define "release_override $RELEASE" \
-    --define "build_cflags $CFLAGS" \
+    "${COMMON_MACRO_OVERRIDES[@]}" \
+    --define "build_cflags $(rpm "${COMMON_MACRO_OVERRIDES[@]}" --eval "%{?build_cflags}") $CFLAGS" \
+    --define "build_cxxflags $(rpm "${COMMON_MACRO_OVERRIDES[@]}" --eval "%{?build_cxxflags}") $CFLAGS" \
+    --define "build_ldflags $(rpm "${COMMON_MACRO_OVERRIDES[@]}" --eval "%{?build_ldflags}") $LDFLAGS" \
    --define "meson_build %{shrink:%{__meson} compile -C %{_vpath_builddir} -j %{_smp_build_ncpus} %{nil}}" \
    --define "meson_install %{shrink:DESTDIR=%{buildroot} %{__meson} install -C %{_vpath_builddir} --no-rebuild --quiet %{nil}}" \
    --define "meson_extra_configure_options -D mode=developer -D b_sanitize=${SANITIZERS:-none}" \
@ -77,9 +100,7 @@ rpmbuild \
    --define "__elf_exclude_path ^/usr/lib/systemd/tests/unit-tests/.*$" \
    --define "__script_requires %{nil}" \
    --define "_find_debuginfo_dwz_opts %{nil}" \
-    --define "_fortify_level 0" \
    --define "_fixperms true" \
-    --undefine _lto_cflags \
    --undefine _package_note_flags \
    --noclean \
    "pkg/$ID/systemd.spec"
--- a/mkosi.images/system/mkosi.conf.d/10-centos-fedora/mkosi.conf
+++ b/mkosi.images/system/mkosi.conf.d/10-centos-fedora/mkosi.conf
@ -23,6 +23,7 @@ VolatilePackages=
 Packages=
        bind-utils
        bpftool
+        compiler-rt
        cryptsetup
        device-mapper-event
        device-mapper-multipath
--- a/mkosi.images/system/mkosi.conf.d/10-debian-ubuntu/mkosi.build.chroot
+++ b/mkosi.images/system/mkosi.conf.d/10-debian-ubuntu/mkosi.build.chroot
@ -44,8 +44,24 @@ EOF
 cat debian/changelog >>debian/changelog.new
 mv debian/changelog.new debian/changelog

+CFLAGS="-O${OPTIMIZATION:-0}"
+if ((LLVM)); then
+    # TODO: Remove -fno-sanitize-function when https://github.com/systemd/systemd/issues/29972 is fixed.
+    CFLAGS="$CFLAGS -shared-libasan -fno-sanitize=function"
+fi
+
+LDFLAGS=""
+if ((LLVM)) && [[ -n "$SANITIZERS" ]]; then
+    LDFLAGS="$LDFLAGS -Wl,-rpath=$(clang --print-file-name="")lib/linux"
+fi
+
+# TODO: Drop GENSYMBOLS_LEVEL once https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=986746 is fixed.
 build() {
    env \
+    CC="$( ((LLVM)) && echo clang || echo gcc)" \
+    CXX="$( ((LLVM)) && echo clang++ || echo g++)" \
+    CC_LD="$( ((LLVM)) && echo lld)" \
+    CXX_LD="$( ((LLVM)) && echo lld)" \
    DEB_BUILD_OPTIONS="$(awk '$1=$1' <<<"\
        $( ((WITH_TESTS)) || echo nocheck) \
        $( ((WITH_DOCS)) || echo nodoc) \
@ -59,11 +75,14 @@ build() {
        $( ((WITH_DOCS)) || echo nodoc) \
        pkg.systemd.upstream \
    ")" \
-    DEB_CFLAGS_APPEND="-O${OPTIMIZATION:-0}" \
+    DEB_CFLAGS_APPEND="$CFLAGS" \
+    DEB_CXXFLAGS_APPEND="$CFLAGS" \
+    DEB_LDFLAGS_APPEND="$LDFLAGS" \
    DPKG_FORCE="unsafe-io" \
    DPKG_DEB_COMPRESSOR_TYPE="none" \
    DH_MISSING="--fail-missing" \
    CONFFLAGS_UPSTREAM="-D mode=developer -D b_sanitize=${SANITIZERS:-none}" \
+    GENSYMBOLS_LEVEL="$( ((LLVM)) && echo 0 || echo 1)" \
        dpkg-buildpackage \
        --no-pre-clean \
        --unsigned-changes \
--- a/mkosi.images/system/mkosi.conf.d/10-debian-ubuntu/mkosi.conf
+++ b/mkosi.images/system/mkosi.conf.d/10-debian-ubuntu/mkosi.conf
@ -56,6 +56,7 @@ Packages=
        iputils-ping
        isc-dhcp-server
        libcap-ng-utils
+        libclang-rt-dev
        libtss2-rc0
        libtss2-tcti-device0
        locales
@ -83,6 +84,7 @@ Packages=

 InitrdPackages=
        btrfs-progs
+        libclang-rt-dev
        tpm2-tools

 InitrdVolatilePackages=
--- a/mkosi.images/system/mkosi.conf.d/10-opensuse/mkosi.build.chroot
+++ b/mkosi.images/system/mkosi.conf.d/10-opensuse/mkosi.build.chroot
@ -42,9 +42,24 @@ DIST="$(rpm --eval %dist)"
 ARCH="$(rpm --eval %_arch)"
 SRCDEST="/usr/src/debug/systemd-$VERSION-${RELEASE}${DIST}.$ARCH"

-EXTRA_CFLAGS="-O${OPTIMIZATION:-0} -Wp,-U_FORTIFY_SOURCE"
+CFLAGS="-O${OPTIMIZATION:-0} -Wp,-U_FORTIFY_SOURCE"
 if ((WITH_DEBUG)); then
-    EXTRA_CFLAGS="$EXTRA_CFLAGS -fdebug-prefix-map=../src=$SRCDEST"
+    CFLAGS="$CFLAGS -fdebug-prefix-map=../src=$SRCDEST"
+fi
+if ((LLVM)); then
+    # TODO: Remove -fno-sanitize-function when https://github.com/systemd/systemd/issues/29972 is fixed.
+    CFLAGS="$CFLAGS -shared-libasan -fno-sanitize=function"
+fi
+
+LDFLAGS="$(rpm --eval "%{?build_ldflags}") $LDFLAGS"
+if ((LLVM)) && [[ -n "$SANITIZERS" ]]; then
+    LDFLAGS="$LDFLAGS -Wl,-rpath=$(clang --print-file-name="")lib/linux"
+fi
+
+# A macro can't have an empty body and currently opensuse does not specify any of its own linker flags so
+# set LDFLAGS to %{nil} if there are no linker flags.
+if [[ -z "${LDFLAGS// }" ]]; then
+    LDFLAGS="%{nil}"
 fi

 build() {
@ -54,6 +69,11 @@ build() {
    # TODO: Replace __meson_auto_features override with meson_extra_configure_options once the suse spec
    # starts to use it.
    # shellcheck disable=SC2046
+    env \
+    CC="$( ((LLVM)) && echo clang || echo gcc)" \
+    CXX="$( ((LLVM)) && echo clang++ || echo g++)" \
+    CC_LD="$( ((LLVM)) && echo lld)" \
+    CXX_LD="$( ((LLVM)) && echo lld)" \
    rpmbuild \
        -bb \
        --build-in-place \
@ -70,7 +90,9 @@ build() {
        --define "version_override $VERSION" \
        --define "release_override $RELEASE" \
        --define "__check_files sh -c '$(rpm --define "_topdir /var/tmp" --eval %__check_files) | tee /tmp/unpackaged-files'" \
-        --define "build_cflags $(rpm --eval %build_cflags) $EXTRA_CFLAGS" \
+        --define "build_cflags $(rpm --eval "%{?build_cflags}") $CFLAGS" \
+        --define "build_cxxflags $(rpm --eval "%{?build_cxxflags}") $CFLAGS" \
+        --define "build_ldflags $LDFLAGS" \
        --define "meson_build %{shrink:%{__meson} compile -C %{_vpath_builddir} -j %{_smp_build_ncpus} %{nil}}" \
        --define "meson_install %{shrink:DESTDIR=%{buildroot} %{__meson} install -C %{_vpath_builddir} --no-rebuild --quiet %{nil}}" \
        --define "__meson_auto_features auto -D mode=developer -D b_sanitize=${SANITIZERS:-none}" \
--- a/mkosi.images/system/mkosi.conf.d/10-opensuse/mkosi.conf
+++ b/mkosi.images/system/mkosi.conf.d/10-opensuse/mkosi.conf
@ -39,8 +39,8 @@ Packages=
        docbook-xsl-stylesheets
        f2fs-tools
        gawk
-        git-core
        gcc-c++
+        git-core
        glibc-locale-base
        gnutls
        grep
@ -90,6 +90,7 @@ Packages=

 InitrdPackages=
        btrfs-progs
+        clang
        kmod
        libkmod2
        tpm2.0-tools