ci: add build/unit-test coverage for armv7 (#42386)

arm64 hosts support running armv7 (armhf) binaries, so we can
cross compile and run the unit tests without performance issues.

armv7 (armhf) is a primary architecture on Ubuntu, so build
regressions block new version updates, and adding coverage
helps to avoid introducing regressions.

.github/workflows/armhf-clang.cross

@@ -0,0 +1,21 @@
+[binaries]
+c = ['clang', '--target=arm-linux-gnueabihf']
+cpp = ['clang++', '--target=arm-linux-gnueabihf']
+ar = 'arm-linux-gnueabihf-ar'
+nm = 'arm-linux-gnueabihf-nm'
+strip = 'arm-linux-gnueabihf-strip'
+pkgconfig = 'pkg-config'
+
+[properties]
+needs_exe_wrapper = false
+pkg_config_libdir = '/usr/lib/arm-linux-gnueabihf/pkgconfig:/usr/share/pkgconfig'
+c_args = ['-O2', '-pipe', '-g', '-feliminate-unused-debug-types']
+c_link_args = ['-fuse-ld=bfd', '-Wl,-O1', '-Wl,--hash-style=gnu', '-Wl,--as-needed', '-Wl,-z,relro,-z,now,-z,noexecstack']
+cpp_args = []
+cpp_link_args = ['-fuse-ld=bfd', '-Wl,-O1', '-Wl,--hash-style=gnu', '-Wl,--as-needed', '-Wl,-z,relro,-z,now,-z,noexecstack']
+
+[host_machine]
+system = 'linux'
+cpu_family = 'arm'
+cpu = 'armv7'
+endian = 'little'

.github/workflows/armhf-gcc.cross

@@ -0,0 +1,21 @@
+[binaries]
+c = 'arm-linux-gnueabihf-gcc'
+cpp = 'arm-linux-gnueabihf-g++'
+ar = 'arm-linux-gnueabihf-gcc-ar'
+nm = 'arm-linux-gnueabihf-gcc-nm'
+strip = 'arm-linux-gnueabihf-strip'
+pkgconfig = 'pkg-config'
+
+[properties]
+needs_exe_wrapper = false
+pkg_config_libdir = '/usr/lib/arm-linux-gnueabihf/pkgconfig:/usr/share/pkgconfig'
+c_args = ['-O2', '-pipe', '-g', '-feliminate-unused-debug-types']
+c_link_args = ['-fuse-ld=bfd', '-Wl,-O1', '-Wl,--hash-style=gnu', '-Wl,--as-needed', '-Wl,-z,relro,-z,now,-z,noexecstack']
+cpp_args = []
+cpp_link_args = ['-fuse-ld=bfd', '-Wl,-O1', '-Wl,--hash-style=gnu', '-Wl,--as-needed', '-Wl,-z,relro,-z,now,-z,noexecstack']
+
+[host_machine]
+system = 'linux'
+cpu_family = 'arm'
+cpu = 'armv7'
+endian = 'little'

.github/workflows/build-test.sh

@@ -19,6 +19,7 @@ ARGS=(
     "-Db_ndebug=true"
     "--auto-features=disabled -Dcompat-mutable-uid-boundaries=true"
 )
+# Packages that are always native (i.e.: tools that run on the host) go in this list
 PACKAGES=(
     cryptsetup-bin
     expect
@@ -28,6 +29,26 @@ PACKAGES=(
     isc-dhcp-client
     itstool
     kbd
+    linux-tools-generic
+    mold
+    mount
+    net-tools
+    python3-evdev
+    python3-jinja2
+    python3-lxml
+    python3-pefile
+    python3-pip
+    python3-pyelftools
+    python3-pyparsing
+    python3-setuptools
+    quota
+    strace
+    unifont
+    util-linux
+    zstd
+)
+# Packages that are needed for the target architecture (i.e.: libraries) go in this list
+DEVEL_PACKAGES=(
     libarchive-dev
     libblkid-dev
     libbpf-dev
@@ -47,38 +68,48 @@ PACKAGES=(
     libxkbcommon-dev
     libxtables-dev
     libzstd-dev
-    linux-tools-generic
-    mold
-    mount
-    net-tools
-    python3-evdev
-    python3-jinja2
-    python3-lxml
-    python3-pefile
-    python3-pip
-    python3-pyelftools
-    python3-pyparsing
-    python3-setuptools
-    quota
-    strace
-    unifont
-    util-linux
-    zstd
 )
 FEATURES=()
 COMPILER="${COMPILER:?}"
 COMPILER_VERSION="${COMPILER_VERSION:?}"
 LINKER="${LINKER:?}"
 RELEASE="$(lsb_release -cs)"
+CROSS_ARCH="${CROSS_ARCH:-}"
+CROSS_FILE=()
 
-if [ "$(uname -m)" = "aarch64" ] || [ "$(uname -m)" = "x86_64" ]; then
-    PACKAGES+=(libxen-dev)
+if [[ -z "$CROSS_ARCH" ]] && [[ "$(uname -m)" =~ ^(aarch64|x86_64)$ ]]; then
+    DEVEL_PACKAGES+=(libxen-dev)
 fi
 
+# If CROSS_ARCH is set, append :<arch> to the packages so they get installed for the target
+PACKAGES+=("${DEVEL_PACKAGES[@]/%/${CROSS_ARCH:+:$CROSS_ARCH}}")
+
 # Note: As we use postfixed clang/gcc binaries, we need to override $AR
 #       as well, otherwise meson falls back to ar from binutils which
 #       doesn't work with LTO
-if [[ "$COMPILER" == clang ]]; then
+if [[ -n "$CROSS_ARCH" ]]; then
+    if [[ "$COMPILER" != gcc ]]; then
+        fatal "$CROSS_ARCH cross builds are only supported with gcc"
+    fi
+
+    case "$CROSS_ARCH" in
+        armhf)
+            triplet=arm-linux-gnueabihf
+            ;;
+        *)
+            fatal "Unsupported cross architecture: $CROSS_ARCH"
+            ;;
+    esac
+
+    CC="$triplet-gcc"
+    CXX="$triplet-g++"
+    AR="$triplet-gcc-ar"
+    CFLAGS="-Wno-maybe-uninitialized"
+    CXXFLAGS=""
+    CROSS_FILE=(--cross-file ".github/workflows/$CROSS_ARCH-gcc.cross")
+    FEATURES+=(-Ddbus-interfaces-dir=no -Dsbat-distro=)
+    PACKAGES+=("crossbuild-essential-$CROSS_ARCH")
+elif [[ "$COMPILER" == clang ]]; then
     CC="clang-$COMPILER_VERSION"
     CXX="clang++-$COMPILER_VERSION"
     AR="llvm-ar-$COMPILER_VERSION"
@@ -142,8 +173,11 @@ else
         sudo sed -i "s/Types: deb/Types: deb deb-src/g" "$f"
     done
 fi
+if [[ -n "$CROSS_ARCH" ]]; then
+    sudo dpkg --add-architecture "$CROSS_ARCH"
+fi
 sudo apt-get -y update
-sudo apt-get -y build-dep systemd
+sudo apt-get -y build-dep systemd ${CROSS_ARCH:+--host-architecture=$CROSS_ARCH}
 sudo apt-get -y install "${PACKAGES[@]}"
 # Install more or less recent meson and ninja with pip, since the distro versions don't
 # always support all the features we need (like --optimization=). Since the build-dep
@@ -179,6 +213,7 @@ for args in "${ARGS[@]}"; do
                -Dtests=unsafe -Dslow-tests=true -Dfuzz-tests=true --werror \
                -Dnobody-group=nogroup -Ddebug=false \
                "${FEATURES[@]}" \
+               "${CROSS_FILE[@]}" \
                $args build; then
 
         cat build/meson-logs/meson-log.txt

.github/workflows/build-test.yml

@@ -39,6 +39,9 @@ jobs:
           - env: { COMPILER: "gcc",   COMPILER_VERSION: "13", LINKER: "mold"  }
             runner: [ ubuntu-24.04-arm ]
             python-version: ''
+          - env: { COMPILER: "gcc",   COMPILER_VERSION: "13", LINKER: "bfd", CROSS_ARCH: "armhf"  }
+            runner: [ ubuntu-24.04-arm ]
+            python-version: ''
           - env: { COMPILER: "clang", COMPILER_VERSION: "18", LINKER: "lld"  }
             runner: [ ubuntu-24.04-s390x ]
             python-version: ''

.github/workflows/unit-tests.sh

@@ -3,11 +3,23 @@
 
 # shellcheck disable=SC2206
 PHASES=(${@:-SETUP RUN RUN_ASAN_UBSAN CLEANUP})
+# Packages that are always native (i.e.: tools that run on the host) go in this list
 ADDITIONAL_DEPS=(
     clang
     expect
     fdisk
     jekyll
+    linux-tools-generic
+    python3-libevdev
+    python3-pip
+    python3-pyelftools
+    python3-pyparsing
+    python3-pytest
+    rpm
+    zstd
+)
+# Packages that are needed for the target architecture (i.e.: libraries) go in this list
+ADDITIONAL_TARGET_DEPS=(
     libbpf-dev
     libfdisk-dev
     libfido2-dev
@@ -18,15 +30,8 @@ ADDITIONAL_DEPS=(
     libtss2-dev
     libxkbcommon-dev
     libzstd-dev
-    linux-tools-generic
-    python3-libevdev
-    python3-pip
-    python3-pyelftools
-    python3-pyparsing
-    python3-pytest
-    rpm
-    zstd
 )
+CROSS_ARCH="${CROSS_ARCH:-}"
 
 function info() {
     echo -e "\033[33;1m$1\033[0m"
@@ -48,6 +53,12 @@ if [ "$(uname -m)" = "aarch64" ] || [ "$(uname -m)" = "x86_64" ]; then
     ADDITIONAL_DEPS+=(systemd-boot-efi)
 fi
 
+if [[ -n "$CROSS_ARCH" ]]; then
+    ADDITIONAL_DEPS+=(crossbuild-essential-$CROSS_ARCH)
+fi
+# Append :<arch> to the packages so they get installed for the target
+ADDITIONAL_DEPS+=("${ADDITIONAL_TARGET_DEPS[@]/%/${CROSS_ARCH:+:$CROSS_ARCH}}")
+
 # (Re)set the current oom-{score-}adj. For some reason root on GH actions is able to _decrease_
 # its oom-score even after dropping all capabilities (including CAP_SYS_RESOURCE), until the
 # score is explicitly changed after sudo. No idea what's going on, but it breaks
@@ -64,8 +75,11 @@ for phase in "${PHASES[@]}"; do
             for f in /etc/apt/sources.list.d/*.sources; do
                 sed -i "s/Types: deb/Types: deb deb-src/g" "$f"
             done
+            if [[ -n "$CROSS_ARCH" ]]; then
+                dpkg --add-architecture "$CROSS_ARCH"
+            fi
             apt-get -y update
-            apt-get -y build-dep systemd
+            apt-get -y build-dep systemd ${CROSS_ARCH:+--host-architecture=$CROSS_ARCH}
             apt-get -y install "${ADDITIONAL_DEPS[@]}"
             pip3 install -r .github/workflows/requirements.txt --require-hashes --break-system-packages
 
@@ -99,6 +113,14 @@ for phase in "${PHASES[@]}"; do
                 fi
             fi
 
+            if [[ -n "$CROSS_ARCH" ]]; then
+                if [[ "$phase" =~ ^RUN_GCC ]]; then
+                    MESON_ARGS+=(-Ddbus-interfaces-dir=no -Dsbat-distro= --cross-file ".github/workflows/$CROSS_ARCH-gcc.cross")
+                elif [[ "$phase" =~ ^RUN_CLANG ]]; then
+                    MESON_ARGS+=(-Dbpf-framework=disabled -Dbootloader=disabled -Defi=false -Ddbus-interfaces-dir=no -Dsbat-distro= --cross-file ".github/workflows/$CROSS_ARCH-clang.cross")
+                fi
+            fi
+
             # On ppc64le the workers are slower and some slow tests time out
             MESON_TEST_ARGS=()
             if [[ "$(uname -m)" != "x86_64" ]] && [[ "$(uname -m)" != "aarch64" ]]; then

.github/workflows/unit-tests.yml

@@ -16,7 +16,7 @@ jobs:
   build:
     runs-on: ${{ matrix.runner }}
     concurrency:
-      group: ${{ github.workflow }}-${{ matrix.run_phase }}-${{ github.ref }}-${{ matrix.runner }}
+      group: ${{ github.workflow }}-${{ matrix.run_phase }}-${{ matrix.cross_arch || 'native' }}-${{ github.ref }}-${{ matrix.runner }}
       cancel-in-progress: true
     strategy:
       fail-fast: false
@@ -27,6 +27,9 @@ jobs:
           - run_phase: GCC
           - run_phase: GCC
             runner: ubuntu-24.04-arm
+          - run_phase: GCC
+            runner: ubuntu-24.04-arm
+            cross_arch: armhf
           - run_phase: GCC
             runner: ubuntu-24.04-ppc64le
           - run_phase: GCC
@@ -34,10 +37,15 @@ jobs:
           - run_phase: CLANG
           - run_phase: CLANG
             runner: ubuntu-24.04-arm
+          - run_phase: CLANG
+            runner: ubuntu-24.04-arm
+            cross_arch: armhf
           - run_phase: CLANG
             runner: ubuntu-24.04-ppc64le
           - run_phase: CLANG
             runner: ubuntu-24.04-s390x
+    env:
+      CROSS_ARCH: ${{ matrix.cross_arch || '' }}
     steps:
       - name: Repository checkout
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd
@@ -50,9 +58,9 @@ jobs:
           sudo sed -i '/^XDG_/d' /etc/environment
           # Pass only specific env variables through sudo, to avoid having
           # the already existing XDG_* stuff on the "other side"
-          sudo --preserve-env=GITHUB_ACTIONS,CI .github/workflows/unit-tests.sh SETUP
+          sudo --preserve-env=GITHUB_ACTIONS,CI,CROSS_ARCH .github/workflows/unit-tests.sh SETUP
       - name: Build & test
-        run: sudo --preserve-env=GITHUB_ACTIONS,CI .github/workflows/unit-tests.sh RUN_${{ matrix.run_phase }}
+        run: sudo --preserve-env=GITHUB_ACTIONS,CI,CROSS_ARCH .github/workflows/unit-tests.sh RUN_${{ matrix.run_phase }}
 
   build-musl:
     name: Build & test (musl, postmarketOS)