build-selftests: v2 of the action inputs

Changes in action inputs:
  * kernel-root is now a required input
  * kernel, kbuild-output and max-make-jobs are removed

kernel-root input is required, because to build selftests
one must to clone a kernel source tree first.

The build script behavior can be directed more granularly with env
variables:
  * KBUILD_OUTPUT now defaults to the kernel-root
  * VMLINUX_BTF now can be set externally
  * MAX_MAKE_JOBS can be set as env variable if desired

Preparation script logic is removed: the rationale is that the caller
is responsible for setting up required environment before building.

Signed-off-by: Ihor Solodrai <ihor.solodrai@pm.me>

build-selftests/action.yml

@@ -1,34 +1,27 @@
 name: 'build selftests'
 description: 'Build BPF selftests'
 inputs:
-  kernel:
-    description: 'kernel version'
-    default: 'LATEST'
-  toolchain:
-    description: 'what toolchain to use'
-    default: 'gcc'
-  kbuild-output:
-    description: 'relative or absolute path to use for storing build artifacts'
+  arch:
+    description: 'arch'
+    required: true
+  kernel-root:
+    description: 'Path to the root of the kernel source tree'
     required: true
-  max-make-jobs:
-    description: 'Maximum number of jobs to use when running make (e.g argument to -j). Default: 4*nproc'
-    default: ''
   llvm-version:
     description: 'llvm version'
     required: false
-    default: '16'
-  arch:
-    description: 'arch'
-    required: true
+    default: '18'
+  toolchain:
+    description: 'gcc or llvm'
+    default: 'gcc'
 
 runs:
   using: "composite"
   steps:
     - name: build selftests
       shell: bash
-      run: |
-        kbuild_output="$(realpath ${{ inputs.kbuild-output }})"
-        export LLVM_VERSION=${{ inputs.llvm-version }}
-        ${GITHUB_ACTION_PATH}/build_selftests.sh "${{ inputs.arch }}" "${{ inputs.kernel }}" "${{ inputs.toolchain }}" "${kbuild_output}"
       env:
-        MAX_MAKE_JOBS: ${{ inputs.max-make-jobs }}
+        LLVM_VERSION: ${{ inputs.llvm-version }}
+      run: |
+        ${GITHUB_ACTION_PATH}/build_selftests.sh "${{ inputs.arch }}" "${{ inputs.toolchain }}" "${{ inputs.kernel-root }}"
+

build-selftests/build_selftests.sh

@@ -5,10 +5,12 @@ set -euo pipefail
 source "${GITHUB_ACTION_PATH}/../helpers.sh"
 
 TARGET_ARCH="$1"
-KERNEL="$2"
-TOOLCHAIN="$3"
-export KBUILD_OUTPUT="$4"
-VMLINUX_H=${VMLINUX_H:-}
+TOOLCHAIN="$2"
+KERNEL_ROOT="$(realpath $3)"
+
+export KBUILD_OUTPUT="${KBUILD_OUTPUT:-${KERNEL_ROOT}}"
+export VMLINUX_BTF="${VMLINUX_BTF:-${KBUILD_OUTPUT}/vmlinux}"
+export VMLINUX_H="${VMLINUX_H:-}"
 
 ARCH="$(platform_to_kernel_arch ${TARGET_ARCH})"
 CROSS_COMPILE=""
@@ -25,18 +27,13 @@ fi
 
 foldable start build_selftests "Building selftests with $TOOLCHAIN"
 
-PREPARE_SELFTESTS_SCRIPT=$(find $GITHUB_WORKSPACE -name prepare_selftests-${KERNEL}.sh)
-if [ -f "${PREPARE_SELFTESTS_SCRIPT}" ]; then
-	(cd "${KERNEL_ROOT}/tools/testing/selftests/bpf" && ${PREPARE_SELFTESTS_SCRIPT})
-fi
-
 MAKE_OPTS=$(cat <<EOF
 	ARCH=${ARCH}
 	CROSS_COMPILE=${CROSS_COMPILE}
 	CLANG=clang-${LLVM_VERSION}
 	LLC=llc-${LLVM_VERSION}
 	LLVM_STRIP=llvm-strip-${LLVM_VERSION}
-	VMLINUX_BTF=${KBUILD_OUTPUT}/vmlinux
+	VMLINUX_BTF=${VMLINUX_BTF}
 	VMLINUX_H=${VMLINUX_H}
 EOF
 )