cross-compile s390x on x86_64 hosts

.github/actions/veristat_baseline_compare/action.yml

@@ -10,7 +10,7 @@ inputs:
 runs:
   using: "composite"
   steps:
-    - uses: actions/upload-artifact@v3
+    - uses: actions/upload-artifact@v4
       with:
         name: ${{ inputs.baseline_name }}
         if-no-files-found: error
@@ -20,7 +20,7 @@ runs:
     # - get baseline log from cache
     # - compare it to current run
     - if: ${{ github.event_name == 'pull_request' }}
-      uses: actions/cache/restore@v3
+      uses: actions/cache/restore@v4
       with:
         key: ${{ inputs.baseline_name }}
         restore-keys: |
@@ -43,7 +43,7 @@ runs:
            "${{ github.workspace }}/${{ inputs.baseline_name }}"
 
     - if: ${{ github.event_name == 'push' }}
-      uses: actions/cache/save@v3
+      uses: actions/cache/save@v4
       with:
         key: ${{ inputs.baseline_name }}-${{ github.run_id }}
         path: '${{ github.workspace }}/${{ inputs.baseline_name }}'

.github/scripts/matrix.py

@@ -74,6 +74,16 @@ def runs_on(self) -> List[str]:
             return ["self-hosted", self.arch.value]
         return [DEFAULT_RUNNER]
 
+    @property
+    def build_runs_on(self) -> List[str]:
+        if is_managed_repo():
+            # Build s390x on x86_64
+            return [
+                "self-hosted",
+                self.arch.value == "s390x" and Arch.X86_64.value or self.arch.value,
+            ]
+        return [DEFAULT_RUNNER]
+
     @property
     def tests(self) -> Dict[str, Any]:
         tests_list = [
@@ -103,6 +113,7 @@ def to_dict(self) -> Dict[str, Any]:
             "build_release": self.build_release,
             "runs_on": self.runs_on,
             "tests": self.tests,
+            "build_runs_on": self.build_runs_on,
         }
 
 

.github/scripts/tar-artifact.sh

@@ -5,6 +5,28 @@ set -eux
 arch="${1}"
 toolchain="${2}"
 
+# Convert a platform (as returned by uname -m) to the kernel
+# arch (as expected by ARCH= env).
+platform_to_kernel_arch() {
+  case $1 in
+    s390x)
+      echo "s390"
+      ;;
+    aarch64)
+      echo "arm64"
+      ;;
+    riscv64)
+      echo "riscv"
+      ;;
+    x86_64)
+      echo "x86"
+      ;;
+    *)
+      echo "$1"
+      ;;
+  esac
+}
+
 # Remove intermediate object files that we have no use for. Ideally
 # we'd just exclude them from tar below, but it does not provide
 # options to express the precise constraints.
@@ -14,7 +36,7 @@ find selftests/ -name "*.o" -a ! -name "*.bpf.o" -print0 | \
 # Strip debug information, which is excessively large (consuming
 # bandwidth) while not actually being used (the kernel does not use
 # DWARF to symbolize stacktraces).
-strip --strip-debug "${KBUILD_OUTPUT}"/vmlinux
+"${arch}"-linux-gnu-strip --strip-debug "${KBUILD_OUTPUT}"/vmlinux
 
 additional_file_list=()
 if [ "${GITHUB_REPOSITORY}" == "kernel-patches/vmtest" ]; then
@@ -29,7 +51,7 @@ if [ "${GITHUB_REPOSITORY}" == "kernel-patches/vmtest" ]; then
   )
 fi
 
-image_name=$(make -s image_name)
+image_name=$(make ARCH="$(platform_to_kernel_arch "${arch}")" -s image_name)
 
 # zstd is installed by default in the runner images.
 tar -cf - \

.github/workflows/kernel-build-test.yml

@@ -19,6 +19,10 @@ on:
         required: true
         type: string
         description: The runners to run the test on. This is a json string representing an array of labels.
+      build_runs_on:
+        required: true
+        type: string
+        description: The runners to run the builds on. This is a json string representing an array of labels.
       llvm-version:
         required: true
         type: string
@@ -61,7 +65,7 @@ jobs:
       arch: ${{ inputs.arch }}
       toolchain_full: ${{ inputs.toolchain_full }}
       toolchain: ${{ inputs.toolchain }}
-      runs_on: ${{ inputs.runs_on }}
+      runs_on: ${{ inputs.build_runs_on }}
       llvm-version: ${{ inputs.llvm-version }}
       kernel: ${{ inputs.kernel }}
       download_sources: ${{ inputs.download_sources }}

.github/workflows/kernel-build.yml

@@ -50,7 +50,7 @@ jobs:
         REPO_PATH: ""
         KBUILD_OUTPUT: kbuild-output/
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         # We fetch an actual bit of history here to facilitate incremental
         # builds (which may check out some earlier upstream change).
         with:
@@ -72,7 +72,7 @@ jobs:
         run: |
           bash .github/scripts/get-commit-metadata.sh
       - name: Pull recent KBUILD_OUTPUT contents
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
           path: ${{ env.KBUILD_OUTPUT }}
           key: kbuild-output-${{ inputs.arch }}-${{ inputs.toolchain_full }}-${{ steps.get-commit-metadata.outputs.branch }}-${{ steps.get-commit-metadata.outputs.timestamp }}-${{ steps.get-commit-metadata.outputs.commit }}
@@ -134,7 +134,7 @@ jobs:
           # Only on pushed changes are build artifacts actually cached, because
           # of github.com/actions/cache's cache isolation logic.
           rm -rf "${KBUILD_OUTPUT}"
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         with:
           name: vmlinux-${{ inputs.arch }}-${{ inputs.toolchain_full }}${{ inputs.release && '-release' || '' }}
           if-no-files-found: error

.github/workflows/kernel-test.yml

@@ -46,8 +46,8 @@ jobs:
       # booleans are weird in GH.
       CONTINUE_ON_ERROR: ${{ inputs.continue_on_error }}
     steps:
-      - uses: actions/checkout@v3
-      - uses: actions/download-artifact@v3
+      - uses: actions/checkout@v4
+      - uses: actions/download-artifact@v4
         with:
           name: vmlinux-${{ inputs.arch }}-${{ inputs.toolchain_full }}
           path: .

.github/workflows/kernel-veristat.yml

@@ -39,8 +39,8 @@ jobs:
       KBUILD_OUTPUT: kbuild-output/
       ARCH_AND_TOOL: ${{ inputs.arch }}-${{ inputs.toolchain }}
     steps:
-      - uses: actions/checkout@v3
-      - uses: actions/download-artifact@v3
+      - uses: actions/checkout@v4
+      - uses: actions/download-artifact@v4
         with:
           name: vmlinux-${{ env.ARCH_AND_TOOL }}
           path: .

.github/workflows/lint.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Run ShellCheck
         uses: ludeeus/action-shellcheck@master
         env:
@@ -28,7 +28,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Run black
         uses: psf/black@stable
         with:
@@ -48,7 +48,7 @@ jobs:
         repository: ['bpf', 'vmtest', 'bar']
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: run script
         run: |
           python3 .github/scripts/matrix.py
@@ -59,7 +59,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Run unittests
         run: python3 -m unittest scripts/tests/*.py
         working-directory: .github

.github/workflows/test.yml

@@ -22,7 +22,7 @@ jobs:
     outputs:
       build-matrix: ${{ steps.set-matrix-impl.outputs.build_matrix }}
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - id: set-matrix-impl
         run: |
           python3 .github/scripts/matrix.py
@@ -44,6 +44,7 @@ jobs:
       toolchain_full: ${{ matrix.toolchain.fullname }}
       toolchain: ${{ matrix.toolchain.name }}
       runs_on: ${{ toJSON(matrix.runs_on) }}
+      build_runs_on: ${{ toJSON(matrix.build_runs_on) }}
       llvm-version: ${{ matrix.toolchain.version }}
       kernel: ${{ matrix.kernel }}
       tests: ${{ toJSON(matrix.tests) }}

ci/diffs/0099-selftest-cross-compile.diff

@@ -0,0 +1,14 @@
+diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
+index a38a3001527c..a403a9d5c529 100644
+--- a/tools/testing/selftests/bpf/Makefile
++++ b/tools/testing/selftests/bpf/Makefile
+@@ -171,7 +171,8 @@ INCLUDE_DIR := $(SCRATCH_DIR)/include
+ BPFOBJ := $(BUILD_DIR)/libbpf/libbpf.a
+ ifneq ($(CROSS_COMPILE),)
+ HOST_BUILD_DIR		:= $(BUILD_DIR)/host
+-HOST_SCRATCH_DIR	:= $(OUTPUT)/host-tools
++#HOST_SCRATCH_DIR	:= $(OUTPUT)/host-tools
++HOST_SCRATCH_DIR	:= $(SCRATCH_DIR)
+ HOST_INCLUDE_DIR	:= $(HOST_SCRATCH_DIR)/include
+ else
+ HOST_BUILD_DIR		:= $(BUILD_DIR)