cmd/link: PIE executables for android/arm

For #10807

Change-Id: Ied826d06cb622edf6413b6f2cdcc46987ab0b05a
Reviewed-on: https://go-review.googlesource.com/16054
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/cmd/link/internal/ld/elf.go b/src/cmd/link/internal/ld/elf.go
index a2084dae2607642e4f68792b9d952651347b429a..94b475398466147ff8016f57c7a160bbf0f8e9b5 100644 (file)
--- a/src/cmd/link/internal/ld/elf.go
+++ b/src/cmd/link/internal/ld/elf.go
@@ -1697,13 +1697,10 @@ func doelf() {
        }
        Addstring(shstrtab, ".elfdata")
        Addstring(shstrtab, ".rodata")
-       if Buildmode == BuildmodeShared || Buildmode == BuildmodeCShared {
-               Addstring(shstrtab, ".data.rel.ro")
-       }
        // See the comment about data.rel.ro.FOO section names in data.go.
        relro_prefix := ""
-
        if UseRelro() {
+               Addstring(shstrtab, ".data.rel.ro")
                relro_prefix = ".data.rel.ro"
        }
        Addstring(shstrtab, relro_prefix+".typelink")

diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index 8784e9d38f14e263eadd77f210a69d84d4e63ed9..764f610bcd33263f511538403c8749cb6ba3605c 100644 (file)
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -177,7 +177,12 @@ func DynlinkingGo() bool {
 // UseRelro returns whether to make use of "read only relocations" aka
 // relro.
 func UseRelro() bool {
-       return (Buildmode == BuildmodeCShared || Buildmode == BuildmodeShared) && Iself
+       switch Buildmode {
+       case BuildmodeCShared, BuildmodeShared, BuildmodePIE:
+               return Iself
+       default:
+               return false
+       }
 }
 
 var (
@@ -278,6 +283,7 @@ type BuildMode uint8
 const (
        BuildmodeUnset BuildMode = iota
        BuildmodeExe
+       BuildmodePIE
        BuildmodeCArchive
        BuildmodeCShared
        BuildmodeShared
@@ -294,6 +300,13 @@ func (mode *BuildMode) Set(s string) error {
                return fmt.Errorf("invalid buildmode: %q", s)
        case "exe":
                *mode = BuildmodeExe
+       case "pie":
+               switch goos {
+               case "android":
+               default:
+                       return badmode()
+               }
+               *mode = BuildmodePIE
        case "c-archive":
                switch goos {
                case "darwin", "linux":
@@ -321,6 +334,8 @@ func (mode *BuildMode) String() string {
                return "" // avoid showing a default in usage message
        case BuildmodeExe:
                return "exe"
+       case BuildmodePIE:
+               return "pie"
        case BuildmodeCArchive:
                return "c-archive"
        case BuildmodeCShared:
@@ -375,7 +390,7 @@ func libinit() {
                switch Buildmode {
                case BuildmodeCShared, BuildmodeCArchive:
                        INITENTRY = fmt.Sprintf("_rt0_%s_%s_lib", goarch, goos)
-               case BuildmodeExe:
+               case BuildmodeExe, BuildmodePIE:
                        INITENTRY = fmt.Sprintf("_rt0_%s_%s", goarch, goos)
                case BuildmodeShared:
                        // No INITENTRY for -buildmode=shared
@@ -623,8 +638,11 @@ func loadlib() {
        // binaries, so leave it enabled on OS X (Mach-O) binaries.
        // Also leave it enabled on Solaris which doesn't support
        // statically linked binaries.
-       if Buildmode == BuildmodeExe && havedynamic == 0 && HEADTYPE != obj.Hdarwin && HEADTYPE != obj.Hsolaris {
-               Debug['d'] = 1
+       switch Buildmode {
+       case BuildmodeExe, BuildmodePIE:
+               if havedynamic == 0 && HEADTYPE != obj.Hdarwin && HEADTYPE != obj.Hsolaris {
+                       Debug['d'] = 1
+               }
        }
 
        importcycles()
@@ -978,6 +996,8 @@ func hostlink() {
                if HEADTYPE == obj.Hdarwin {
                        argv = append(argv, "-Wl,-pagezero_size,4000000")
                }
+       case BuildmodePIE:
+               argv = append(argv, "-pie")
        case BuildmodeCShared:
                if HEADTYPE == obj.Hdarwin {
                        argv = append(argv, "-dynamiclib")

diff --git a/src/cmd/link/internal/ld/symtab.go b/src/cmd/link/internal/ld/symtab.go
index 918ca8ac136ff145d7c71f23fc61ec530353df40..f71158663c7abcd22df3e322de1a1350cbefc017 100644 (file)
--- a/src/cmd/link/internal/ld/symtab.go
+++ b/src/cmd/link/internal/ld/symtab.go
@@ -351,7 +351,7 @@ func symtab() {
        // pseudo-symbols to mark locations of type, string, and go string data.
        var symtype *LSym
        var symtyperel *LSym
-       if UseRelro() && Buildmode == BuildmodeCShared {
+       if UseRelro() && (Buildmode == BuildmodeCShared || Buildmode == BuildmodePIE) {
                s = Linklookup(Ctxt, "type.*", 0)
 
                s.Type = obj.STYPE
@@ -512,7 +512,8 @@ func symtab() {
        adduint(Ctxt, moduledata, uint64(ntypelinks))
        if len(Ctxt.Shlibs) > 0 {
                thismodulename := filepath.Base(outfile)
-               if Buildmode == BuildmodeExe {
+               switch Buildmode {
+               case BuildmodeExe, BuildmodePIE:
                        // When linking an executable, outfile is just "a.out". Make
                        // it something slightly more comprehensible.
                        thismodulename = "the executable"