platform_build_soong/cc/config/toolchain.go
Kalesh Singh f4ffe0a026 soong: Add crt_pad_segment to .so's
crt_pad_segment adds a NOTE to the ELF which is used by the binoic
loader to determine whether it should pad segments when mapping them
into the virtual address space, such that there are no gaps between
mappings of consecutive segments. This avoids an increase in
unreclaimable kernel slab memory usage for VMAs on devices where the
runtime-page-size > elf-segment-p_align.

Since -fandroid-pad-segment [1] respects -nostdlib used in android
platform builds, soong must link in crt_pad_segment to platform shared
libraries.

For simplicity, link crt_pad_segment everywhere that crtend_so is
applicable, ignoring nocrt property, as there is no other reason
to track these separately.

Example:

❯ readelf -WS /system/lib64/libc++.so [Output simplified]

...
Section Headers:
  [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
...
  [ 2] .note.android.pad_segment NOTE            0000000000000288 000288 000018 00   A  0   0  4
...

[1] https://github.com/llvm/llvm-project/pull/77244

Bug: 316403210
Test: readelf -WS <lib>.so
Change-Id: Icc06611376cfd5ee4de7281b4134f9f8ffe7ca60
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
2024-01-31 19:42:31 -08:00

265 lines
6.4 KiB
Go

// Copyright 2015 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 config
import (
"fmt"
"android/soong/android"
)
func init() {
exportedVars.ExportStringListStaticVariable("DarwinAvailableLibraries", darwinAvailableLibraries)
exportedVars.ExportStringListStaticVariable("LinuxAvailableLibraries", linuxAvailableLibraries)
exportedVars.ExportStringListStaticVariable("WindowsAvailableLibraries", windowsAvailableLibraries)
}
type toolchainFactory func(arch android.Arch) Toolchain
var toolchainFactories = make(map[android.OsType]map[android.ArchType]toolchainFactory)
func registerToolchainFactory(os android.OsType, arch android.ArchType, factory toolchainFactory) {
if toolchainFactories[os] == nil {
toolchainFactories[os] = make(map[android.ArchType]toolchainFactory)
}
toolchainFactories[os][arch] = factory
}
type toolchainContext interface {
Os() android.OsType
Arch() android.Arch
}
func FindToolchainWithContext(ctx toolchainContext) Toolchain {
t, err := findToolchain(ctx.Os(), ctx.Arch())
if err != nil {
panic(err)
}
return t
}
func FindToolchain(os android.OsType, arch android.Arch) Toolchain {
t, err := findToolchain(os, arch)
if err != nil {
panic(err)
}
return t
}
func findToolchain(os android.OsType, arch android.Arch) (Toolchain, error) {
factory := toolchainFactories[os][arch.ArchType]
if factory == nil {
return nil, fmt.Errorf("Toolchain not found for %s arch %q", os.String(), arch.String())
}
return factory(arch), nil
}
type Toolchain interface {
Name() string
IncludeFlags() string
ClangTriple() string
ToolchainCflags() string
ToolchainLdflags() string
Asflags() string
Cflags() string
Cppflags() string
Ldflags() string
Lldflags() string
InstructionSetFlags(string) (string, error)
ndkTriple() string
YasmFlags() string
Is64Bit() bool
ShlibSuffix() string
ExecutableSuffix() string
LibclangRuntimeLibraryArch() string
AvailableLibraries() []string
CrtBeginStaticBinary() []string
CrtBeginSharedBinary() []string
CrtBeginSharedLibrary() []string
CrtEndStaticBinary() []string
CrtEndSharedBinary() []string
CrtEndSharedLibrary() []string
CrtPadSegmentSharedLibrary() []string
// DefaultSharedLibraries returns the list of shared libraries that will be added to all
// targets unless they explicitly specify system_shared_libs.
DefaultSharedLibraries() []string
Bionic() bool
Glibc() bool
Musl() bool
}
type toolchainBase struct {
}
func (t *toolchainBase) ndkTriple() string {
return ""
}
func NDKTriple(toolchain Toolchain) string {
triple := toolchain.ndkTriple()
if triple == "" {
// Use the clang triple if there is no explicit NDK triple
triple = toolchain.ClangTriple()
}
return triple
}
func (toolchainBase) InstructionSetFlags(s string) (string, error) {
if s != "" {
return "", fmt.Errorf("instruction_set: %s is not a supported instruction set", s)
}
return "", nil
}
func (toolchainBase) ToolchainCflags() string {
return ""
}
func (toolchainBase) ToolchainLdflags() string {
return ""
}
func (toolchainBase) Asflags() string {
return ""
}
func (toolchainBase) YasmFlags() string {
return ""
}
func (toolchainBase) LibclangRuntimeLibraryArch() string {
return ""
}
type toolchainNoCrt struct{}
func (toolchainNoCrt) CrtBeginStaticBinary() []string { return nil }
func (toolchainNoCrt) CrtBeginSharedBinary() []string { return nil }
func (toolchainNoCrt) CrtBeginSharedLibrary() []string { return nil }
func (toolchainNoCrt) CrtEndStaticBinary() []string { return nil }
func (toolchainNoCrt) CrtEndSharedBinary() []string { return nil }
func (toolchainNoCrt) CrtEndSharedLibrary() []string { return nil }
func (toolchainNoCrt) CrtPadSegmentSharedLibrary() []string { return nil }
func (toolchainBase) DefaultSharedLibraries() []string {
return nil
}
func (toolchainBase) Bionic() bool {
return false
}
func (toolchainBase) Glibc() bool {
return false
}
func (toolchainBase) Musl() bool {
return false
}
type toolchain64Bit struct {
}
func (toolchain64Bit) Is64Bit() bool {
return true
}
type toolchain32Bit struct {
}
func (toolchain32Bit) Is64Bit() bool {
return false
}
func variantOrDefault(variants map[string]string, choice string) string {
if ret, ok := variants[choice]; ok {
return ret
}
return variants[""]
}
func addPrefix(list []string, prefix string) []string {
for i := range list {
list[i] = prefix + list[i]
}
return list
}
func LibclangRuntimeLibrary(t Toolchain, library string) string {
return "libclang_rt." + library
}
func BuiltinsRuntimeLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "builtins")
}
func AddressSanitizerRuntimeLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "asan")
}
func AddressSanitizerStaticRuntimeLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "asan.static")
}
func AddressSanitizerCXXStaticRuntimeLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "asan_cxx.static")
}
func HWAddressSanitizerRuntimeLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "hwasan")
}
func HWAddressSanitizerStaticLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "hwasan_static")
}
func UndefinedBehaviorSanitizerRuntimeLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "ubsan_standalone")
}
func UndefinedBehaviorSanitizerMinimalRuntimeLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "ubsan_minimal")
}
func ThreadSanitizerRuntimeLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "tsan")
}
func ScudoRuntimeLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "scudo")
}
func ScudoMinimalRuntimeLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "scudo_minimal")
}
func LibFuzzerRuntimeLibrary(t Toolchain) string {
return LibclangRuntimeLibrary(t, "fuzzer")
}
func LibFuzzerRuntimeInterceptors(t Toolchain) string {
return LibclangRuntimeLibrary(t, "fuzzer_interceptors")
}