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Commit dea1d039 authored by Colin Cross's avatar Colin Cross
Browse files

Fix addrsig warnings 

ld -r reorders symbols and invalidates the .llvm_addrsig section, which
then causes warnings if the resulting object is used with ld --icf=safe.
The warning is especially common when building with musl, as the
clang_rt.crt* objects have .llvm_addrsig sections, are linked into
libc_musl_crt* using ld -r, and are then linked into every other binary
and shared library with --icf=safe.

Strip the .llvm_addrsig section after ld -r to prevent the warnings.

Test: m USE_HOST_MUSL=true host-native -k
Change-Id: Ia52a4756b9ebbb62115898d0de9f8641e6fea705
parent 748fd189

cc/builder.go

+23 −0
Original line number Diff line number Diff line
@@ -125,6 +125,14 @@ var ( 
		},

		"objcopyCmd", "prefix")



	// Rule to run objcopy --remove-section=.llvm_addrsig on a partially linked object

	noAddrSig = pctx.AndroidStaticRule("noAddrSig",

		blueprint.RuleParams{

			Command:     "rm -f ${out} && $objcopyCmd --remove-section=.llvm_addrsig ${in} ${out}",

			CommandDeps: []string{"$objcopyCmd"},

		},

		"objcopyCmd")



	_ = pctx.SourcePathVariable("stripPath", "build/soong/scripts/strip.sh")

	_ = pctx.SourcePathVariable("xzCmd", "prebuilts/build-tools/${config.HostPrebuiltTag}/bin/xz")

	_ = pctx.SourcePathVariable("createMiniDebugInfo", "prebuilts/build-tools/${config.HostPrebuiltTag}/bin/create_minidebuginfo")
@@ -1008,6 +1016,21 @@ func transformBinaryPrefixSymbols(ctx android.ModuleContext, prefix string, inpu 
	})

}



// Generate a rule for running objcopy --remove-section=.llvm_addrsig on a partially linked object

func transformObjectNoAddrSig(ctx android.ModuleContext, inputFile android.Path, outputFile android.WritablePath) {

	objcopyCmd := "${config.ClangBin}/llvm-objcopy"



	ctx.Build(pctx, android.BuildParams{

		Rule:        noAddrSig,

		Description: "remove addrsig " + outputFile.Base(),

		Output:      outputFile,

		Input:       inputFile,

		Args: map[string]string{

			"objcopyCmd": objcopyCmd,

		},

	})

}



// Registers a build statement to invoke `strip` (to discard symbols and data from object files).

func transformStrip(ctx android.ModuleContext, inputFile android.Path,

	outputFile android.WritablePath, flags StripFlags) {

cc/object.go

+8 −1
Original line number Diff line number Diff line
@@ -309,6 +309,8 @@ func (object *objectLinker) link(ctx ModuleContext, 
			})

		}

	} else {

		outputAddrSig := android.PathForModuleOut(ctx, "addrsig", outputName)



		if String(object.Properties.Prefix_symbols) != "" {

			input := android.PathForModuleOut(ctx, "unprefixed", outputName)

			transformBinaryPrefixSymbols(ctx, String(object.Properties.Prefix_symbols), input,
@@ -316,7 +318,12 @@ func (object *objectLinker) link(ctx ModuleContext, 
			output = input

		}



		transformObjsToObj(ctx, objs.objFiles, builderFlags, output, flags.LdFlagsDeps)

		transformObjsToObj(ctx, objs.objFiles, builderFlags, outputAddrSig, flags.LdFlagsDeps)



		// ld -r reorders symbols and invalidates the .llvm_addrsig section, which then causes warnings

		// if the resulting object is used with ld --icf=safe.  Strip the .llvm_addrsig section to

		// prevent the warnings.

		transformObjectNoAddrSig(ctx, outputAddrSig, output)

	}



	ctx.CheckbuildFile(outputFile)

java/app_test.go

+2 −2
Original line number Diff line number Diff line
@@ -443,9 +443,9 @@ func TestUpdatableApps_JniLibShouldBeBuiltAgainstMinSdkVersion(t *testing.T) { 
	inputs := ctx.ModuleForTests("libjni", "android_arm64_armv8-a_sdk_shared").Description("link").Implicits

	var crtbeginFound, crtendFound bool

	expectedCrtBegin := ctx.ModuleForTests("crtbegin_so",

		"android_arm64_armv8-a_sdk_29").Rule("partialLd").Output

		"android_arm64_armv8-a_sdk_29").Rule("noAddrSig").Output

	expectedCrtEnd := ctx.ModuleForTests("crtend_so",

		"android_arm64_armv8-a_sdk_29").Rule("partialLd").Output

		"android_arm64_armv8-a_sdk_29").Rule("noAddrSig").Output

	implicits := []string{}

	for _, input := range inputs {

		implicits = append(implicits, input.String())