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Commit acee27cd authored by Yi Kong's avatar Yi Kong
Browse files

Strip libgcc to only keep fallback symbols 

We use libgcc as fallback for symbols not present in libclang_rt
builtins, however we didn't know what exact symbols were being used,
some may not be intended to fallback.

Create libgcc_stripped, which only contains unwind symbols from libgcc.

Bug: 29275768
Test: bionic-unit-tests
Change-Id: I5b349fa6138e51663bf3b67109b880b4356da8e8
parent feef2ef4

Android.bp

+111 −0
Original line number Diff line number Diff line
@@ -482,6 +482,117 @@ toolchain_library { 
    },

}



toolchain_library {

    name: "libgcc_stripped",

    defaults: ["linux_bionic_supported"],

    vendor_available: true,

    recovery_available: true,



    arch: {

        arm: {

            src: "prebuilts/gcc/linux-x86/arm/arm-linux-androideabi-4.9/lib/gcc/arm-linux-androideabi/4.9.x/libgcc.a",

            strip: {

                keep_symbols_list: [

                    // unwind-arm.o

                    "_Unwind_Complete",

                    "_Unwind_DeleteException",

                    "_Unwind_GetCFA",

                    "_Unwind_VRS_Get",

                    "_Unwind_VRS_Pop",

                    "_Unwind_VRS_Set",

                    "__aeabi_unwind_cpp_pr0",

                    "__aeabi_unwind_cpp_pr1",

                    "__aeabi_unwind_cpp_pr2",

                    "__gnu_Unwind_Backtrace",

                    "__gnu_Unwind_ForcedUnwind",

                    "__gnu_Unwind_RaiseException",

                    "__gnu_Unwind_Resume",

                    "__gnu_Unwind_Resume_or_Rethrow",



                    // libunwind.o

                    "_Unwind_Backtrace",

                    "_Unwind_ForcedUnwind",

                    "_Unwind_RaiseException",

                    "_Unwind_Resume",

                    "_Unwind_Resume_or_Rethrow",

                    "___Unwind_Backtrace",

                    "___Unwind_ForcedUnwind",

                    "___Unwind_RaiseException",

                    "___Unwind_Resume",

                    "___Unwind_Resume_or_Rethrow",

                    "__gnu_Unwind_Restore_VFP",

                    "__gnu_Unwind_Restore_VFP_D",

                    "__gnu_Unwind_Restore_VFP_D_16_to_31",

                    "__gnu_Unwind_Restore_WMMXC",

                    "__gnu_Unwind_Restore_WMMXD",

                    "__gnu_Unwind_Save_VFP",

                    "__gnu_Unwind_Save_VFP_D",

                    "__gnu_Unwind_Save_VFP_D_16_to_31",

                    "__gnu_Unwind_Save_WMMXC",

                    "__gnu_Unwind_Save_WMMXD",

                    "__restore_core_regs",

                    "restore_core_regs",



                    // pr-support.o

                    "_Unwind_GetDataRelBase",

                    "_Unwind_GetLanguageSpecificData",

                    "_Unwind_GetRegionStart",

                    "_Unwind_GetTextRelBase",

                    "__gnu_unwind_execute",

                    "__gnu_unwind_frame",

                ],

                use_gnu_strip: true,

            },

        },

        arm64: {

            src: "prebuilts/gcc/linux-x86/aarch64/aarch64-linux-android-4.9/lib/gcc/aarch64-linux-android/4.9.x/libgcc.a",

        },

        x86: {

            src: "prebuilts/gcc/linux-x86/x86/x86_64-linux-android-4.9/lib/gcc/x86_64-linux-android/4.9.x/32/libgcc.a",



        },

        x86_64: {

            src: "prebuilts/gcc/linux-x86/x86/x86_64-linux-android-4.9/lib/gcc/x86_64-linux-android/4.9.x/libgcc.a",

        },

    },

    strip: {

        keep_symbols_list: [

            // unwind-dw2.o

            "_Unwind_Backtrace",

            "_Unwind_DeleteException",

            "_Unwind_FindEnclosingFunction",

            "_Unwind_ForcedUnwind",

            "_Unwind_GetCFA",

            "_Unwind_GetDataRelBase",

            "_Unwind_GetGR",

            "_Unwind_GetIP",

            "_Unwind_GetIPInfo",

            "_Unwind_GetLanguageSpecificData",

            "_Unwind_GetRegionStart",

            "_Unwind_GetTextRelBase",

            "_Unwind_RaiseException",

            "_Unwind_Resume",

            "_Unwind_Resume_or_Rethrow",

            "_Unwind_SetGR",

            "_Unwind_SetIP",

            "__frame_state_for",



            // unwind-dw2-fde-dip.o

            "_Unwind_Find_FDE",

            "__deregister_frame",

            "__deregister_frame_info",

            "__deregister_frame_info_bases",

            "__register_frame",

            "__register_frame_info",

            "__register_frame_info_bases",

            "__register_frame_info_table",

            "__register_frame_info_table_bases",

            "__register_frame_table",

        ],

        use_gnu_strip: true,

    },

}



toolchain_library {

    name: "libwinpthread",

    host_supported: true,

apex/apex_test.go

+7 −0
Original line number Diff line number Diff line
@@ -92,6 +92,13 @@ func testApex(t *testing.T, bp string) *android.TestContext { 
			recovery_available: true,

		}



		toolchain_library {

			name: "libgcc_stripped",

			src: "",

			vendor_available: true,

			recovery_available: true,

		}



		toolchain_library {

			name: "libclang_rt.builtins-aarch64-android",

			src: "",

cc/builder.go

+4 −0
Original line number Diff line number Diff line
@@ -255,6 +255,7 @@ type builderFlags struct { 
	groupStaticLibs bool



	stripKeepSymbols       bool

	stripKeepSymbolsList   string

	stripKeepMiniDebugInfo bool

	stripAddGnuDebuglink   bool

	stripUseGnuStrip       bool
@@ -835,6 +836,9 @@ func TransformStrip(ctx android.ModuleContext, inputFile android.Path, 
	if flags.stripKeepSymbols {

		args += " --keep-symbols"

	}

	if flags.stripKeepSymbolsList != "" {

		args += " -k" + flags.stripKeepSymbolsList

	}

	if flags.stripUseGnuStrip {

		args += " --use-gnu-strip"

	}

cc/cc_test.go

+2 −2
Original line number Diff line number Diff line
@@ -1833,13 +1833,13 @@ func TestStaticLibDepExport(t *testing.T) { 
	// Check the shared version of lib2.

	variant := "android_arm64_armv8-a_core_shared"

	module := ctx.ModuleForTests("lib2", variant).Module().(*Module)

	checkStaticLibs(t, []string{"lib1", "libclang_rt.builtins-aarch64-android", "libatomic", "libgcc"}, module)

	checkStaticLibs(t, []string{"lib1", "libclang_rt.builtins-aarch64-android", "libatomic", "libgcc_stripped"}, module)



	// Check the static version of lib2.

	variant = "android_arm64_armv8-a_core_static"

	module = ctx.ModuleForTests("lib2", variant).Module().(*Module)

	// libc++_static is linked additionally.

	checkStaticLibs(t, []string{"lib1", "libc++_static", "libclang_rt.builtins-aarch64-android", "libatomic", "libgcc"}, module)

	checkStaticLibs(t, []string{"lib1", "libc++_static", "libclang_rt.builtins-aarch64-android", "libatomic", "libgcc_stripped"}, module)

}



var compilerFlagsTestCases = []struct {

cc/linker.go

+4 −4
Original line number Diff line number Diff line
@@ -228,10 +228,10 @@ func (linker *baseLinker) linkerDeps(ctx DepsContext, deps Deps) Deps { 
		// libclang_rt.builtins, libgcc and libatomic have to be last on the command line

		if !Bool(linker.Properties.No_libcrt) {

			deps.LateStaticLibs = append(deps.LateStaticLibs, config.BuiltinsRuntimeLibrary(ctx.toolchain()))

		}



			deps.LateStaticLibs = append(deps.LateStaticLibs, "libatomic")

		if !Bool(linker.Properties.No_libgcc) {

			deps.LateStaticLibs = append(deps.LateStaticLibs, "libgcc_stripped")

		} else if !Bool(linker.Properties.No_libgcc) {

			deps.LateStaticLibs = append(deps.LateStaticLibs, "libatomic")

			deps.LateStaticLibs = append(deps.LateStaticLibs, "libgcc")

		}