ci: Build and add kernels to cache

Ease maintenance of landlock-test-tools and avoid adding new built
artifacts for each major kernel release.

We now use the latest versions according to landlock-lsm/linux branches
for each meaningful kernel.

To simplify the new ubuntu_22_rust_stable, don't run tests against the
local kernel, which is already done with ubuntu_22_rust_msrv.

Reorder install, clone and build steps in ubuntu_22_rust_stable to clean
up the working directory.

Signed-off-by: Mickaël Salaün <[email protected]>

.github/workflows/rust.yml

@@ -45,6 +45,68 @@ jobs:
     outputs:
       commits: ${{ toJSON(steps.*.outputs.*) }}
 
+  kernel_list:
+    runs-on: ubuntu-22.04
+    outputs:
+      kernels: ${{ toJSON(steps.id.outputs.*) }}
+    steps:
+
+    - name: Identify latest Linux versions
+      id: id
+      run: |
+        echo "List of tested kernels:" > $GITHUB_STEP_SUMMARY
+        abi=0
+        for version in 5.10 5.15 6.1 6.4 6.7; do
+          commit="$(git ls-remote https://github.com/landlock-lsm/linux refs/heads/linux-${version}.y | awk 'NR == 1 { print $1 }')"
+          if [[ -z "${commit}" ]]; then
+            echo "ERROR: Failed to fetch Linux ${version}" >&2
+            exit 1
+          fi
+          echo "kernel_${abi}={ \"version\":\"${version}\",  \"abi\":\"${abi}\",  \"commit\":\"${commit}\" }" >> $GITHUB_OUTPUT
+          echo "- [Linux ${version}.y](https://github.com/landlock-lsm/linux/commit/${commit}) with Landlock ABI ${abi}" >> $GITHUB_STEP_SUMMARY
+          let abi++ || :
+        done
+
+  get_kernels:
+    runs-on: ubuntu-22.04
+    needs: kernel_list
+    strategy:
+      fail-fast: false
+      matrix:
+        kernel: ${{ fromJSON(needs.kernel_list.outputs.kernels) }}
+    steps:
+
+    - name: Cache Linux ${{ fromJSON(matrix.kernel).version}}.y
+      id: cache_linux
+      uses: actions/cache@v4
+      with:
+        path: linux-${{ fromJSON(matrix.kernel).version }}
+        key: linux-${{ fromJSON(matrix.kernel).commit }}
+
+    - name: Clone Landlock test tools
+      if: steps.cache_linux.outputs.cache-hit != 'true'
+      uses: actions/checkout@v4
+      with:
+        repository: landlock-lsm/landlock-test-tools
+        ref: ${{ env.LANDLOCK_TEST_TOOLS_COMMIT }}
+        path: landlock-test-tools
+
+    - name: Clone Linux ${{ fromJSON(matrix.kernel).version}}.y
+      if: steps.cache_linux.outputs.cache-hit != 'true'
+      uses: actions/checkout@v4
+      with:
+        repository: landlock-lsm/linux
+        ref: ${{ fromJSON(matrix.kernel).commit }}
+        path: linux
+
+    - name: Build Linux ${{ fromJSON(matrix.kernel).version}}.y
+      if: steps.cache_linux.outputs.cache-hit != 'true'
+      run: |
+        cp landlock-test-tools/kernels/config-${{ fromJSON(matrix.kernel).version}} linux/.config
+        cd linux
+        ../landlock-test-tools/kernels/make-uml.sh
+        mv linux ../linux-${{ fromJSON(matrix.kernel).version}}
+
   ubuntu_22_rust_msrv:
     runs-on: ubuntu-22.04
     needs: commit_list
@@ -130,20 +192,23 @@ jobs:
 
   ubuntu_22_rust_stable:
     runs-on: ubuntu-22.04
-    needs: commit_list
+    needs: [commit_list, kernel_list, get_kernels]
     strategy:
       fail-fast: false
       matrix:
         commit: ${{ fromJSON(needs.commit_list.outputs.commits) }}
+        kernel: ${{ fromJSON(needs.kernel_list.outputs.kernels) }}
     env:
       LANDLOCK_CRATE_TEST_ABI: 3
       # $CARGO is used by landlock-test-tools/test-rust.sh
       CARGO: rustup run stable cargo
     steps:
 
-    - uses: actions/checkout@v4
-      with:
-        ref: ${{ matrix.commit }}
+    - name: Install Rust stable
+      run: |
+        rm ~/.cargo/bin/{cargo-fmt,rustfmt} || :
+        rustup default stable
+        rustup update
 
     - name: Clone Landlock test tools
       uses: actions/checkout@v4
@@ -152,26 +217,20 @@ jobs:
         ref: ${{ env.LANDLOCK_TEST_TOOLS_COMMIT }}
         path: landlock-test-tools
 
-    - name: Install Rust stable
-      run: |
-        rm ~/.cargo/bin/{cargo-fmt,rustfmt} || :
-        rustup default stable
-        rustup update
-
-    - name: Run tests against the local kernel (Landlock ABI ${{ env.LANDLOCK_CRATE_TEST_ABI }})
-      run: $CARGO test --verbose
-
-    - name: Run tests against Linux 5.10
-      run: ./landlock-test-tools/test-rust.sh linux-5.10 0
-
-    - name: Run tests against Linux 5.15
-      run: ./landlock-test-tools/test-rust.sh linux-5.15 1
-
-    - name: Run tests against Linux 6.1
-      run: ./landlock-test-tools/test-rust.sh linux-6.1 2
+    - name: Clone rust-landlock
+      uses: actions/checkout@v4
+      with:
+        ref: ${{ matrix.commit }}
+        path: rust-landlock
 
-    - name: Run tests against Linux 6.4
-      run: ./landlock-test-tools/test-rust.sh linux-6.4 3
+    - name: Get Linux ${{ fromJSON(matrix.kernel).version}}.y
+      uses: actions/cache/restore@v4
+      with:
+        path: linux-${{ fromJSON(matrix.kernel).version }}
+        key: linux-${{ fromJSON(matrix.kernel).commit }}
+        fail-on-cache-miss: true
 
-    - name: Run tests against Linux 6.7
-      run: ./landlock-test-tools/test-rust.sh linux-6.7 4
+    - name: Run tests against Linux ${{ fromJSON(matrix.kernel).version }}.y
+      run: |
+        cd rust-landlock
+        ../landlock-test-tools/test-rust.sh ../linux-${{ fromJSON(matrix.kernel).version }} ${{ fromJSON(matrix.kernel).abi }}