add prebuilt_kernel_modules module

prebuilt_kernel_modules is a build rule for processing and installing
kernel module files. The module files are processed by depmod to build
modules.{load|alias|deps|softdeps} files. Debug symbols are stripped
from the module files and then all the files are installed to
./lib/modules/<kernel_version> directory.

This is the Soong-equivalent of the 'build-image-kernel-modules-dir`
macro and is expected to replace it in the future.

Bug: 178980227
Test: m

Change-Id: I772ac816824921d275869e35b93a083d239a2450

android/packaging.go

@@ -49,6 +49,11 @@ func (p *PackagingSpec) FileName() string {
 	return ""
 }
 
+// Path relative to the root of the package
+func (p *PackagingSpec) RelPathInPackage() string {
+	return p.relPathInPackage
+}
+
 type PackageModule interface {
 	Module
 	packagingBase() *PackagingBase

kernel/Android.bp

@@ -0,0 +1,18 @@
+bootstrap_go_package {
+    name: "soong-kernel",
+    pkgPath: "android/soong/kernel",
+    deps: [
+        "blueprint",
+        "soong",
+        "soong-android",
+        "soong-cc",
+        "soong-cc-config",
+    ],
+    srcs: [
+        "prebuilt_kernel_modules.go",
+    ],
+    testSrcs: [
+        "prebuilt_kernel_modules_test.go",
+    ],
+    pluginFor: ["soong_build"],
+}

kernel/prebuilt_kernel_modules.go

@@ -0,0 +1,166 @@
+// Copyright (C) 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kernel
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+
+	"android/soong/android"
+	_ "android/soong/cc/config"
+
+	"github.com/google/blueprint"
+	"github.com/google/blueprint/proptools"
+)
+
+func init() {
+	android.RegisterModuleType("prebuilt_kernel_modules", prebuiltKernelModulesFactory)
+	pctx.Import("android/soong/cc/config")
+}
+
+type prebuiltKernelModules struct {
+	android.ModuleBase
+
+	properties prebuiltKernelModulesProperties
+
+	installDir android.InstallPath
+}
+
+type prebuiltKernelModulesProperties struct {
+	// List or filegroup of prebuilt kernel module files. Should have .ko suffix.
+	Srcs []string `android:"path,arch_variant"`
+
+	// Kernel version that these modules are for. Kernel modules are installed to
+	// /lib/modules/<kernel_version> directory in the corresponding partition. Default is "".
+	Kernel_version *string
+}
+
+// prebuilt_kernel_modules installs a set of prebuilt kernel module files to the correct directory.
+// In addition, this module builds modules.load, modules.dep, modules.softdep and modules.alias
+// using depmod and installs them as well.
+func prebuiltKernelModulesFactory() android.Module {
+	module := &prebuiltKernelModules{}
+	module.AddProperties(&module.properties)
+	android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibFirst)
+	return module
+}
+
+func (pkm *prebuiltKernelModules) KernelVersion() string {
+	return proptools.StringDefault(pkm.properties.Kernel_version, "")
+}
+
+func (pkm *prebuiltKernelModules) DepsMutator(ctx android.BottomUpMutatorContext) {
+	// do nothing
+}
+
+func (pkm *prebuiltKernelModules) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	modules := android.PathsForModuleSrc(ctx, pkm.properties.Srcs)
+
+	depmodOut := runDepmod(ctx, modules)
+	strippedModules := stripDebugSymbols(ctx, modules)
+
+	installDir := android.PathForModuleInstall(ctx, "lib", "module")
+	if pkm.KernelVersion() != "" {
+		installDir = installDir.Join(ctx, pkm.KernelVersion())
+	}
+
+	for _, m := range strippedModules {
+		ctx.InstallFile(installDir, filepath.Base(m.String()), m)
+	}
+	ctx.InstallFile(installDir, "modules.load", depmodOut.modulesLoad)
+	ctx.InstallFile(installDir, "modules.dep", depmodOut.modulesDep)
+	ctx.InstallFile(installDir, "modules.softdep", depmodOut.modulesSoftdep)
+	ctx.InstallFile(installDir, "modules.alias", depmodOut.modulesAlias)
+}
+
+var (
+	pctx = android.NewPackageContext("android/soong/kernel")
+
+	stripRule = pctx.AndroidStaticRule("strip",
+		blueprint.RuleParams{
+			Command:     "$stripCmd -o $out --strip-debug $in",
+			CommandDeps: []string{"$stripCmd"},
+		}, "stripCmd")
+)
+
+func stripDebugSymbols(ctx android.ModuleContext, modules android.Paths) android.OutputPaths {
+	dir := android.PathForModuleOut(ctx, "stripped").OutputPath
+	var outputs android.OutputPaths
+
+	for _, m := range modules {
+		stripped := dir.Join(ctx, filepath.Base(m.String()))
+		ctx.Build(pctx, android.BuildParams{
+			Rule:   stripRule,
+			Input:  m,
+			Output: stripped,
+			Args: map[string]string{
+				"stripCmd": "${config.ClangBin}/llvm-strip",
+			},
+		})
+		outputs = append(outputs, stripped)
+	}
+
+	return outputs
+}
+
+type depmodOutputs struct {
+	modulesLoad    android.OutputPath
+	modulesDep     android.OutputPath
+	modulesSoftdep android.OutputPath
+	modulesAlias   android.OutputPath
+}
+
+func runDepmod(ctx android.ModuleContext, modules android.Paths) depmodOutputs {
+	baseDir := android.PathForModuleOut(ctx, "depmod").OutputPath
+	fakeVer := "0.0" // depmod demands this anyway
+	modulesDir := baseDir.Join(ctx, "lib", "modules", fakeVer)
+
+	builder := android.NewRuleBuilder(pctx, ctx)
+
+	// Copy the module files to a temporary dir
+	builder.Command().Text("rm").Flag("-rf").Text(modulesDir.String())
+	builder.Command().Text("mkdir").Flag("-p").Text(modulesDir.String())
+	for _, m := range modules {
+		builder.Command().Text("cp").Input(m).Text(modulesDir.String())
+	}
+
+	// Enumerate modules to load
+	modulesLoad := modulesDir.Join(ctx, "modules.load")
+	var basenames []string
+	for _, m := range modules {
+		basenames = append(basenames, filepath.Base(m.String()))
+	}
+	builder.Command().
+		Text("echo").Flag("\"" + strings.Join(basenames, " ") + "\"").
+		Text("|").Text("tr").Flag("\" \"").Flag("\"\\n\"").
+		Text(">").Output(modulesLoad)
+
+	// Run depmod to build modules.dep/softdep/alias files
+	modulesDep := modulesDir.Join(ctx, "modules.dep")
+	modulesSoftdep := modulesDir.Join(ctx, "modules.softdep")
+	modulesAlias := modulesDir.Join(ctx, "modules.alias")
+	builder.Command().
+		BuiltTool("depmod").
+		FlagWithArg("-b ", baseDir.String()).
+		Text(fakeVer).
+		ImplicitOutput(modulesDep).
+		ImplicitOutput(modulesSoftdep).
+		ImplicitOutput(modulesAlias)
+
+	builder.Build("depmod", fmt.Sprintf("depmod %s", ctx.ModuleName()))
+
+	return depmodOutputs{modulesLoad, modulesDep, modulesSoftdep, modulesAlias}
+}

kernel/prebuilt_kernel_modules_test.go

@@ -0,0 +1,129 @@
+// Copyright 2021 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package kernel
+
+import (
+	"io/ioutil"
+	"os"
+	"reflect"
+	"strings"
+	"testing"
+
+	"android/soong/android"
+	"android/soong/cc"
+)
+
+func testKernelModules(t *testing.T, bp string, fs map[string][]byte) (*android.TestContext, android.Config) {
+	bp = bp + `
+		cc_binary_host {
+			name: "depmod",
+			srcs: ["depmod.cpp"],
+			stl: "none",
+			static_executable: true,
+			system_shared_libs: [],
+		}
+	`
+	bp = bp + cc.GatherRequiredDepsForTest(android.Android)
+
+	fs["depmod.cpp"] = nil
+	cc.GatherRequiredFilesForTest(fs)
+
+	config := android.TestArchConfig(buildDir, nil, bp, fs)
+
+	ctx := android.NewTestArchContext(config)
+	ctx.RegisterModuleType("prebuilt_kernel_modules", prebuiltKernelModulesFactory)
+	ctx.PreArchMutators(android.RegisterDefaultsPreArchMutators)
+	cc.RegisterRequiredBuildComponentsForTest(ctx)
+
+	ctx.Register()
+	_, errs := ctx.ParseFileList(".", []string{"Android.bp"})
+	android.FailIfErrored(t, errs)
+	_, errs = ctx.PrepareBuildActions(config)
+	android.FailIfErrored(t, errs)
+
+	return ctx, config
+}
+
+func ensureListContains(t *testing.T, result []string, expected string) {
+	t.Helper()
+	if !android.InList(expected, result) {
+		t.Errorf("%q is not found in %v", expected, result)
+	}
+}
+
+func ensureContains(t *testing.T, result string, expected string) {
+	t.Helper()
+	if !strings.Contains(result, expected) {
+		t.Errorf("%q is not found in %q", expected, result)
+	}
+}
+
+func TestKernelModulesFilelist(t *testing.T) {
+	ctx, _ := testKernelModules(t, `
+		prebuilt_kernel_modules {
+			name: "foo",
+			srcs: ["*.ko"],
+			kernel_version: "5.10",
+		}
+	`,
+		map[string][]byte{
+			"mod1.ko": nil,
+			"mod2.ko": nil,
+		})
+
+	expected := []string{
+		"lib/module/5.10/mod1.ko",
+		"lib/module/5.10/mod2.ko",
+		"lib/module/5.10/modules.load",
+		"lib/module/5.10/modules.dep",
+		"lib/module/5.10/modules.softdep",
+		"lib/module/5.10/modules.alias",
+	}
+
+	var actual []string
+	for _, ps := range ctx.ModuleForTests("foo", "android_arm64_armv8-a").Module().PackagingSpecs() {
+		actual = append(actual, ps.RelPathInPackage())
+	}
+	actual = android.SortedUniqueStrings(actual)
+	expected = android.SortedUniqueStrings(expected)
+	if !reflect.DeepEqual(actual, expected) {
+		t.Errorf("\ngot: %v\nexpected: %v\n", actual, expected)
+	}
+}
+
+var buildDir string
+
+func setUp() {
+	var err error
+	buildDir, err = ioutil.TempDir("", "soong_kernel_test")
+	if err != nil {
+		panic(err)
+	}
+}
+
+func tearDown() {
+	os.RemoveAll(buildDir)
+}
+
+func TestMain(m *testing.M) {
+	run := func() int {
+		setUp()
+		defer tearDown()
+
+		return m.Run()
+	}
+
+	os.Exit(run())
+}