tequilaOS/platform_build_soong
2
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

soong: Add crt_pad_segment to .so's

Browse source 
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>
This commit is contained in:
Kalesh Singh 2024-01-29 13:01:51 -08:00
parent f166df7efd
commit f4ffe0a026
10 changed files with 61 additions and 18 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
apex/apex_test.go
View file

@ -1455,6 +1455,7 @@ func TestRuntimeApexShouldInstallHwasanIfLibcDependsOnIt(t *testing.T) {
name: "libc",
no_libcrt: true,
nocrt: true,
no_crt_pad_segment: true,
stl: "none",
system_shared_libs: [],
stubs: { versions: ["1"] },
@ -1469,6 +1470,7 @@ func TestRuntimeApexShouldInstallHwasanIfLibcDependsOnIt(t *testing.T) {
name: "libclang_rt.hwasan",
no_libcrt: true,
nocrt: true,
no_crt_pad_segment: true,
stl: "none",
system_shared_libs: [],
srcs: [""],
@ -1511,6 +1513,7 @@ func TestRuntimeApexShouldInstallHwasanIfHwaddressSanitized(t *testing.T) {
name: "libc",
no_libcrt: true,
nocrt: true,
no_crt_pad_segment: true,
stl: "none",
system_shared_libs: [],
stubs: { versions: ["1"] },
@ -1521,6 +1524,7 @@ func TestRuntimeApexShouldInstallHwasanIfHwaddressSanitized(t *testing.T) {
name: "libclang_rt.hwasan",
no_libcrt: true,
nocrt: true,
no_crt_pad_segment: true,
stl: "none",
system_shared_libs: [],
srcs: [""],

14
cc/config/bionic.go
View file

@ -24,6 +24,7 @@ var (
bionicCrtBeginStaticBinary, bionicCrtEndStaticBinary = []string{"crtbegin_static"}, []string{"crtend_android"}
bionicCrtBeginSharedBinary, bionicCrtEndSharedBinary = []string{"crtbegin_dynamic"}, []string{"crtend_android"}
bionicCrtBeginSharedLibrary, bionicCrtEndSharedLibrary = []string{"crtbegin_so"}, []string{"crtend_so"}
bionicCrtPadSegmentSharedLibrary = []string{"crt_pad_segment"}
)
func (toolchainBionic) Bionic() bool { return true }
@ -36,9 +37,10 @@ func (toolchainBionic) ExecutableSuffix() string { return "" }
func (toolchainBionic) AvailableLibraries() []string { return nil }
func (toolchainBionic) CrtBeginStaticBinary() []string { return bionicCrtBeginStaticBinary }
func (toolchainBionic) CrtBeginSharedBinary() []string { return bionicCrtBeginSharedBinary }
func (toolchainBionic) CrtBeginSharedLibrary() []string { return bionicCrtBeginSharedLibrary }
func (toolchainBionic) CrtEndStaticBinary() []string { return bionicCrtEndStaticBinary }
func (toolchainBionic) CrtEndSharedBinary() []string { return bionicCrtEndSharedBinary }
func (toolchainBionic) CrtEndSharedLibrary() []string { return bionicCrtEndSharedLibrary }
func (toolchainBionic) CrtBeginStaticBinary() []string { return bionicCrtBeginStaticBinary }
func (toolchainBionic) CrtBeginSharedBinary() []string { return bionicCrtBeginSharedBinary }
func (toolchainBionic) CrtBeginSharedLibrary() []string { return bionicCrtBeginSharedLibrary }
func (toolchainBionic) CrtEndStaticBinary() []string { return bionicCrtEndStaticBinary }
func (toolchainBionic) CrtEndSharedBinary() []string { return bionicCrtEndSharedBinary }
func (toolchainBionic) CrtEndSharedLibrary() []string { return bionicCrtEndSharedLibrary }
func (toolchainBionic) CrtPadSegmentSharedLibrary() []string { return bionicCrtPadSegmentSharedLibrary }

14
cc/config/toolchain.go
View file

@ -100,6 +100,7 @@ type Toolchain interface {
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.
@ -155,12 +156,13 @@ func (toolchainBase) LibclangRuntimeLibraryArch() string {
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) 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

13
cc/config/x86_linux_host.go
View file

@ -328,12 +328,13 @@ type toolchainMusl struct {
func (toolchainMusl) Musl() bool { return true }
func (toolchainMusl) CrtBeginStaticBinary() []string { return muslCrtBeginStaticBinary }
func (toolchainMusl) CrtBeginSharedBinary() []string { return muslCrtBeginSharedBinary }
func (toolchainMusl) CrtBeginSharedLibrary() []string { return muslCrtBeginSharedLibrary }
func (toolchainMusl) CrtEndStaticBinary() []string { return muslCrtEndStaticBinary }
func (toolchainMusl) CrtEndSharedBinary() []string { return muslCrtEndSharedBinary }
func (toolchainMusl) CrtEndSharedLibrary() []string { return muslCrtEndSharedLibrary }
func (toolchainMusl) CrtBeginStaticBinary() []string { return muslCrtBeginStaticBinary }
func (toolchainMusl) CrtBeginSharedBinary() []string { return muslCrtBeginSharedBinary }
func (toolchainMusl) CrtBeginSharedLibrary() []string { return muslCrtBeginSharedLibrary }
func (toolchainMusl) CrtEndStaticBinary() []string { return muslCrtEndStaticBinary }
func (toolchainMusl) CrtEndSharedBinary() []string { return muslCrtEndSharedBinary }
func (toolchainMusl) CrtEndSharedLibrary() []string { return muslCrtEndSharedLibrary }
func (toolchainMusl) CrtPadSegmentSharedLibrary() []string { return nil }
func (toolchainMusl) DefaultSharedLibraries() []string { return MuslDefaultSharedLibraries }

4
cc/library.go
View file

@ -974,6 +974,10 @@ func (library *libraryDecorator) linkerDeps(ctx DepsContext, deps Deps) Deps {
if library.baseLinker.Properties.crt() {
deps.CrtBegin = append(deps.CrtBegin, ctx.toolchain().CrtBeginSharedLibrary()...)
deps.CrtEnd = append(deps.CrtEnd, ctx.toolchain().CrtEndSharedLibrary()...)
}
if library.baseLinker.Properties.crtPadSegment() {
deps.CrtEnd = append(deps.CrtEnd, ctx.toolchain().CrtPadSegmentSharedLibrary()...)
}
deps.WholeStaticLibs = append(deps.WholeStaticLibs, library.SharedProperties.Shared.Whole_static_libs...)
deps.StaticLibs = append(deps.StaticLibs, library.SharedProperties.Shared.Static_libs...)

8
cc/linker.go
View file

@ -91,6 +91,10 @@ type BaseLinkerProperties struct {
// compiling crt or libc.
Nocrt *bool `android:"arch_variant"`
// don't link in crt_pad_segment. This flag is currently only used internal to
// soong for testing and for vndk prebuilt shared libraries.
No_crt_pad_segment *bool `android:"arch_variant"`
// deprecated and ignored because lld makes it unnecessary. See b/189475744.
Group_static_libs *bool `android:"arch_variant"`
@ -253,6 +257,10 @@ func (blp *BaseLinkerProperties) libCrt() bool {
return blp.No_libcrt == nil || !*blp.No_libcrt
}
func (blp *BaseLinkerProperties) crtPadSegment() bool {
return blp.No_crt_pad_segment == nil || !*blp.No_crt_pad_segment
}
func NewBaseLinker(sanitize *sanitize) *baseLinker {
return &baseLinker{sanitize: sanitize}
}

6
cc/testing.go
View file

@ -77,6 +77,7 @@ func commonDefaultModules() string {
no_libcrt: true,
sdk_version: "minimum",
nocrt: true,
no_crt_pad_segment: true,
system_shared_libs: [],
stl: "none",
check_elf_files: false,
@ -384,6 +385,11 @@ func commonDefaultModules() string {
objs: ["crtbrand"],
}
cc_object {
name: "crt_pad_segment",
defaults: ["crt_defaults"],
}
cc_object {
name: "crtbrand",
defaults: ["crt_defaults"],

10
cc/vendor_snapshot_test.go
View file

@ -341,6 +341,7 @@ func TestVendorSnapshotUse(t *testing.T) {
vendor: true,
nocrt: true,
no_libcrt: true,
no_crt_pad_segment: true,
stl: "none",
system_shared_libs: [],
compile_multilib: "64",
@ -458,6 +459,7 @@ func TestVendorSnapshotUse(t *testing.T) {
vendor: true,
nocrt: true,
no_libcrt: true,
no_crt_pad_segment: true,
stl: "none",
system_shared_libs: [],
}
@ -467,6 +469,7 @@ func TestVendorSnapshotUse(t *testing.T) {
vendor: true,
nocrt: true,
no_libcrt: true,
no_crt_pad_segment: true,
stl: "none",
system_shared_libs: [],
shared_libs: ["libvndk", "libvendor_available", "libllndk"],
@ -487,6 +490,7 @@ func TestVendorSnapshotUse(t *testing.T) {
vendor: true,
nocrt: true,
no_libcrt: true,
no_crt_pad_segment: true,
stl: "none",
system_shared_libs: [],
static_libs: ["libvendor"],
@ -501,6 +505,7 @@ func TestVendorSnapshotUse(t *testing.T) {
vendor: true,
nocrt: true,
no_libcrt: true,
no_crt_pad_segment: true,
stl: "none",
system_shared_libs: [],
vndk: {
@ -597,6 +602,7 @@ func TestVendorSnapshotUse(t *testing.T) {
target_arch: "arm64",
compile_multilib: "both",
vendor: true,
no_crt_pad_segment: true,
shared_libs: [
"libvendor_without_snapshot",
"libvendor_available",
@ -620,6 +626,7 @@ func TestVendorSnapshotUse(t *testing.T) {
target_arch: "arm64",
compile_multilib: "both",
vendor: true,
no_crt_pad_segment: true,
overrides: ["libvendor"],
shared_libs: [
"libvendor_without_snapshot",
@ -657,6 +664,7 @@ func TestVendorSnapshotUse(t *testing.T) {
target_arch: "arm64",
compile_multilib: "32",
vendor: true,
no_crt_pad_segment: true,
arch: {
arm: {
src: "lib32.so",
@ -683,6 +691,7 @@ func TestVendorSnapshotUse(t *testing.T) {
target_arch: "arm64",
compile_multilib: "64",
vendor: true,
no_crt_pad_segment: true,
arch: {
arm64: {
src: "lib64.so",
@ -722,6 +731,7 @@ func TestVendorSnapshotUse(t *testing.T) {
target_arch: "arm64",
compile_multilib: "both",
vendor: true,
no_crt_pad_segment: true,
arch: {
arm64: {
src: "libvendor_available.so",

1
cc/vndk_prebuilt.go
View file

@ -232,6 +232,7 @@ func vndkPrebuiltSharedLibrary() *Module {
prebuilt.properties.Check_elf_files = BoolPtr(false)
prebuilt.baseLinker.Properties.No_libcrt = BoolPtr(true)
prebuilt.baseLinker.Properties.Nocrt = BoolPtr(true)
prebuilt.baseLinker.Properties.No_crt_pad_segment = BoolPtr(true)
// Prevent default system libs (libc, libm, and libdl) from being linked
if prebuilt.baseLinker.Properties.System_shared_libs == nil {

5
rust/vendor_snapshot_test.go
View file

@ -553,6 +553,7 @@ func TestVendorSnapshotUse(t *testing.T) {
vendor: true,
nocrt: true,
no_libcrt: true,
no_crt_pad_segment: true,
stl: "none",
system_shared_libs: [],
}
@ -857,6 +858,7 @@ func TestVendorSnapshotUse(t *testing.T) {
target_arch: "arm64",
compile_multilib: "32",
vendor: true,
no_crt_pad_segment: true,
arch: {
arm: {
src: "lib32.so",
@ -870,6 +872,7 @@ func TestVendorSnapshotUse(t *testing.T) {
target_arch: "arm64",
compile_multilib: "64",
vendor: true,
no_crt_pad_segment: true,
arch: {
arm64: {
src: "lib64.so",
@ -882,6 +885,7 @@ func TestVendorSnapshotUse(t *testing.T) {
target_arch: "arm64",
compile_multilib: "64",
vendor: true,
no_crt_pad_segment: true,
arch: {
arm64: {
src: "liblog.so",
@ -913,6 +917,7 @@ func TestVendorSnapshotUse(t *testing.T) {
target_arch: "arm64",
compile_multilib: "both",
vendor: true,
no_crt_pad_segment: true,
arch: {
arm64: {
src: "libvendor_available.so",