1// Copyright (C) 2021 The Android Open Source Project
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package kernel
16
17import (
18	"fmt"
19	"path/filepath"
20	"strings"
21
22	"android/soong/android"
23	_ "android/soong/cc/config"
24
25	"github.com/google/blueprint"
26	"github.com/google/blueprint/proptools"
27)
28
29func init() {
30	pctx.Import("android/soong/cc/config")
31	registerKernelBuildComponents(android.InitRegistrationContext)
32}
33
34func registerKernelBuildComponents(ctx android.RegistrationContext) {
35	ctx.RegisterModuleType("prebuilt_kernel_modules", prebuiltKernelModulesFactory)
36}
37
38type prebuiltKernelModules struct {
39	android.ModuleBase
40
41	properties prebuiltKernelModulesProperties
42
43	installDir android.InstallPath
44}
45
46type prebuiltKernelModulesProperties struct {
47	// List or filegroup of prebuilt kernel module files. Should have .ko suffix.
48	Srcs []string `android:"path,arch_variant"`
49
50	// Kernel version that these modules are for. Kernel modules are installed to
51	// /lib/modules/<kernel_version> directory in the corresponding partition. Default is "".
52	Kernel_version *string
53}
54
55// prebuilt_kernel_modules installs a set of prebuilt kernel module files to the correct directory.
56// In addition, this module builds modules.load, modules.dep, modules.softdep and modules.alias
57// using depmod and installs them as well.
58func prebuiltKernelModulesFactory() android.Module {
59	module := &prebuiltKernelModules{}
60	module.AddProperties(&module.properties)
61	android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibFirst)
62	return module
63}
64
65func (pkm *prebuiltKernelModules) KernelVersion() string {
66	return proptools.StringDefault(pkm.properties.Kernel_version, "")
67}
68
69func (pkm *prebuiltKernelModules) DepsMutator(ctx android.BottomUpMutatorContext) {
70	// do nothing
71}
72
73func (pkm *prebuiltKernelModules) GenerateAndroidBuildActions(ctx android.ModuleContext) {
74	modules := android.PathsForModuleSrc(ctx, pkm.properties.Srcs)
75
76	depmodOut := runDepmod(ctx, modules)
77	strippedModules := stripDebugSymbols(ctx, modules)
78
79	installDir := android.PathForModuleInstall(ctx, "lib", "modules")
80	if pkm.KernelVersion() != "" {
81		installDir = installDir.Join(ctx, pkm.KernelVersion())
82	}
83
84	for _, m := range strippedModules {
85		ctx.InstallFile(installDir, filepath.Base(m.String()), m)
86	}
87	ctx.InstallFile(installDir, "modules.load", depmodOut.modulesLoad)
88	ctx.InstallFile(installDir, "modules.dep", depmodOut.modulesDep)
89	ctx.InstallFile(installDir, "modules.softdep", depmodOut.modulesSoftdep)
90	ctx.InstallFile(installDir, "modules.alias", depmodOut.modulesAlias)
91}
92
93var (
94	pctx = android.NewPackageContext("android/soong/kernel")
95
96	stripRule = pctx.AndroidStaticRule("strip",
97		blueprint.RuleParams{
98			Command:     "$stripCmd -o $out --strip-debug $in",
99			CommandDeps: []string{"$stripCmd"},
100		}, "stripCmd")
101)
102
103func stripDebugSymbols(ctx android.ModuleContext, modules android.Paths) android.OutputPaths {
104	dir := android.PathForModuleOut(ctx, "stripped").OutputPath
105	var outputs android.OutputPaths
106
107	for _, m := range modules {
108		stripped := dir.Join(ctx, filepath.Base(m.String()))
109		ctx.Build(pctx, android.BuildParams{
110			Rule:   stripRule,
111			Input:  m,
112			Output: stripped,
113			Args: map[string]string{
114				"stripCmd": "${config.ClangBin}/llvm-strip",
115			},
116		})
117		outputs = append(outputs, stripped)
118	}
119
120	return outputs
121}
122
123type depmodOutputs struct {
124	modulesLoad    android.OutputPath
125	modulesDep     android.OutputPath
126	modulesSoftdep android.OutputPath
127	modulesAlias   android.OutputPath
128}
129
130func runDepmod(ctx android.ModuleContext, modules android.Paths) depmodOutputs {
131	baseDir := android.PathForModuleOut(ctx, "depmod").OutputPath
132	fakeVer := "0.0" // depmod demands this anyway
133	modulesDir := baseDir.Join(ctx, "lib", "modules", fakeVer)
134
135	builder := android.NewRuleBuilder(pctx, ctx)
136
137	// Copy the module files to a temporary dir
138	builder.Command().Text("rm").Flag("-rf").Text(modulesDir.String())
139	builder.Command().Text("mkdir").Flag("-p").Text(modulesDir.String())
140	for _, m := range modules {
141		builder.Command().Text("cp").Input(m).Text(modulesDir.String())
142	}
143
144	// Enumerate modules to load
145	modulesLoad := modulesDir.Join(ctx, "modules.load")
146	var basenames []string
147	for _, m := range modules {
148		basenames = append(basenames, filepath.Base(m.String()))
149	}
150	builder.Command().
151		Text("echo").Flag("\"" + strings.Join(basenames, " ") + "\"").
152		Text("|").Text("tr").Flag("\" \"").Flag("\"\\n\"").
153		Text(">").Output(modulesLoad)
154
155	// Run depmod to build modules.dep/softdep/alias files
156	modulesDep := modulesDir.Join(ctx, "modules.dep")
157	modulesSoftdep := modulesDir.Join(ctx, "modules.softdep")
158	modulesAlias := modulesDir.Join(ctx, "modules.alias")
159	builder.Command().
160		BuiltTool("depmod").
161		FlagWithArg("-b ", baseDir.String()).
162		Text(fakeVer).
163		ImplicitOutput(modulesDep).
164		ImplicitOutput(modulesSoftdep).
165		ImplicitOutput(modulesAlias)
166
167	builder.Build("depmod", fmt.Sprintf("depmod %s", ctx.ModuleName()))
168
169	return depmodOutputs{modulesLoad, modulesDep, modulesSoftdep, modulesAlias}
170}
171