cmd/go, cmd/link: enable buildmode=pie on darwin/amd64

Change some configurations to enable the feature. Also add the test.
This CL doesn't include internal linking support which is tentatively
disabled due to #18968. We could do that another day.

Fixes #21220

Change-Id: I601d2d78446d36332acc70be0d5b9461ac635208
Reviewed-on: https://go-review.googlesource.com/54790
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/cmd/go/go_test.go b/src/cmd/go/go_test.go
index 7d80d965ae6dc1ffd41a590a537f6fb4b177d75b..2006283ea18485695e991e9baad8ff38348038e8 100644 (file)
--- a/src/cmd/go/go_test.go
+++ b/src/cmd/go/go_test.go
@@ -6,6 +6,8 @@ package main_test
 
 import (
        "bytes"
+       "debug/elf"
+       "debug/macho"
        "fmt"
        "go/format"
        "internal/race"
@@ -4331,3 +4333,59 @@ func TestListTests(t *testing.T) {
        t.Run("Example1", testWith("Example", "ExampleSimple"))
        t.Run("Example2", testWith("Example", "ExampleWithEmptyOutput"))
 }
+
+func TestBuildmodePIE(t *testing.T) {
+       if runtime.Compiler == "gccgo" {
+               t.Skipf("skipping test because buildmode=pie is not supported on gccgo")
+       }
+
+       platform := fmt.Sprintf("%s/%s", runtime.GOOS, runtime.GOARCH)
+       switch platform {
+       case "linux/386", "linux/amd64", "linux/arm", "linux/arm64", "linux/ppc64le", "linux/s390x",
+               "android/amd64", "android/arm", "android/arm64", "android/386":
+       case "darwin/amd64":
+       default:
+               t.Skipf("skipping test because buildmode=pie is not supported on %s", platform)
+       }
+
+       tg := testgo(t)
+       defer tg.cleanup()
+
+       tg.tempFile("main.go", `package main; func main() { print("hello") }`)
+       src := tg.path("main.go")
+       obj := tg.path("main")
+       tg.run("build", "-buildmode=pie", "-o", obj, src)
+
+       switch runtime.GOOS {
+       case "linux", "android":
+               f, err := elf.Open(obj)
+               if err != nil {
+                       t.Fatal(err)
+               }
+               if f.Type != elf.ET_DYN {
+                       t.Errorf("PIE type must be ET_DYN, but %s", f.Type)
+               }
+       case "darwin":
+               f, err := macho.Open(obj)
+               if err != nil {
+                       t.Fatal(err)
+               }
+               if f.Flags&macho.FlagDyldLink == 0 {
+                       t.Error("PIE must have DyldLink flag, but not")
+               }
+               if f.Flags&macho.FlagPIE == 0 {
+                       t.Error("PIE must have PIE flag, but not")
+               }
+       default:
+               panic("unreachable")
+       }
+
+       out, err := exec.Command(obj).CombinedOutput()
+       if err != nil {
+               t.Fatal(err)
+       }
+
+       if string(out) != "hello" {
+               t.Errorf("got %q; want %q", out, "hello")
+       }
+}

diff --git a/src/cmd/go/internal/work/build.go b/src/cmd/go/internal/work/build.go
index 8ac4f75985c81e943ea97f709a0c34c7d4136d11..53afebe8cca919e28a891920ddf057921f1166fd 100644 (file)
--- a/src/cmd/go/internal/work/build.go
+++ b/src/cmd/go/internal/work/build.go
@@ -327,6 +327,8 @@ func BuildModeInit() {
                        case "linux/386", "linux/amd64", "linux/arm", "linux/arm64", "linux/ppc64le", "linux/s390x",
                                "android/amd64", "android/arm", "android/arm64", "android/386":
                                codegenArg = "-shared"
+                       case "darwin/amd64":
+                               codegenArg = "-shared"
                        default:
                                base.Fatalf("-buildmode=pie not supported on %s\n", platform)
                        }

diff --git a/src/cmd/link/internal/ld/config.go b/src/cmd/link/internal/ld/config.go
index aae2a437236c72dfe4fdf5427728053dd586f1b6..f6e7ccf5760e402122cb464a88ec94193c06a711 100644 (file)
--- a/src/cmd/link/internal/ld/config.go
+++ b/src/cmd/link/internal/ld/config.go
@@ -44,6 +44,12 @@ func (mode *BuildMode) Set(s string) error {
        case "pie":
                switch objabi.GOOS {
                case "android", "linux":
+               case "darwin":
+                       switch objabi.GOARCH {
+                       case "amd64":
+                       default:
+                               return badmode()
+                       }
                default:
                        return badmode()
                }

diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index 995562803892d1977ed884fb7a516bdab945636b..d906893218cc60be0da316be3675fa2c66bfb327 100644 (file)
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -1095,7 +1095,7 @@ func (l *Link) hostlink() {
                argv = append(argv, "-Wl,-headerpad,1144")
                if l.DynlinkingGo() {
                        argv = append(argv, "-Wl,-flat_namespace")
-               } else if !SysArch.InFamily(sys.ARM64) {
+               } else if !SysArch.InFamily(sys.ARM64) && Buildmode != BuildmodePIE {
                        argv = append(argv, "-Wl,-no_pie")
                }
        case objabi.Hopenbsd:
@@ -1114,10 +1114,13 @@ func (l *Link) hostlink() {
                        argv = append(argv, "-Wl,-pagezero_size,4000000")
                }
        case BuildmodePIE:
-               if UseRelro() {
-                       argv = append(argv, "-Wl,-z,relro")
+               // ELF.
+               if Headtype != objabi.Hdarwin {
+                       if UseRelro() {
+                               argv = append(argv, "-Wl,-z,relro")
+                       }
+                       argv = append(argv, "-pie")
                }
-               argv = append(argv, "-pie")
        case BuildmodeCShared:
                if Headtype == objabi.Hdarwin {
                        argv = append(argv, "-dynamiclib")

diff --git a/src/cmd/link/internal/ld/macho.go b/src/cmd/link/internal/ld/macho.go
index 2a5227bbb139efb0273a2c7a4ca83b5abd22b870..ef4d1552f6c44a82079edf686b22404a3462516a 100644 (file)
--- a/src/cmd/link/internal/ld/macho.go
+++ b/src/cmd/link/internal/ld/macho.go
@@ -401,8 +401,8 @@ func machoshbits(ctxt *Link, mseg *MachoSeg, sect *Section, segname string) {
 
        var msect *MachoSect
        if sect.Rwx&1 == 0 && segname != "__DWARF" && (SysArch.Family == sys.ARM64 ||
-               (SysArch.Family == sys.AMD64 && (Buildmode == BuildmodeCShared || Buildmode == BuildmodeCArchive || Buildmode == BuildmodePlugin)) ||
-               (SysArch.Family == sys.ARM && (Buildmode == BuildmodeCShared || Buildmode == BuildmodeCArchive || Buildmode == BuildmodePlugin))) {
+               (SysArch.Family == sys.AMD64 && Buildmode != BuildmodeExe) ||
+               (SysArch.Family == sys.ARM && Buildmode != BuildmodeExe)) {
                // Darwin external linker on arm64 and on amd64 and arm in c-shared/c-archive buildmode
                // complains about absolute relocs in __TEXT, so if the section is not
                // executable, put it in __DATA segment.