cmd/link: emit LC_BUILD_VERSION on Mach-O

LC_VERSION_MIN_MACOSX seems deprecated. Emit LC_BUILD_VERSION
instead. Also emit it on darwin/arm64, where it was not emitted
before.

Fixes #45091.

Change-Id: I18fb80d571f681da3bd258e53beb520e68f354bd
Reviewed-on: https://go-review.googlesource.com/c/go/+/312550
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

2 files changed, 21 insertions, 25 deletions

diff --git a/src/cmd/link/internal/ld/macho.go b/src/cmd/link/internal/ld/macho.go
index 1c88c05dd4..85269b30d0 100644
--- a/src/cmd/link/internal/ld/macho.go
+++ b/src/cmd/link/internal/ld/macho.go
@@ -472,24 +472,20 @@ func (ctxt *Link) domacho() {
 		if buildcfg.GOOS == "ios" {
 			machoPlatform = PLATFORM_IOS
 		}
-		switch ctxt.Arch.Family {
-		default:
-			if ctxt.LinkMode == LinkInternal {
-				// For lldb, must say LC_VERSION_MIN_MACOSX or else
-				// it won't know that this Mach-O binary is from OS X
-				// (could be iOS or WatchOS instead).
-				// Go on iOS uses linkmode=external, and linkmode=external
-				// adds this itself. So we only need this code for linkmode=internal
-				// and we can assume OS X.
-				//
-				// See golang.org/issues/12941.
-				//
+		if ctxt.LinkMode == LinkInternal && machoPlatform == PLATFORM_MACOS {
+			var version uint32
+			switch ctxt.Arch.Family {
+			case sys.AMD64:
 				// The version must be at least 10.9; see golang.org/issues/30488.
-				ml := newMachoLoad(ctxt.Arch, LC_VERSION_MIN_MACOSX, 2)
-				ml.data[0] = 10<<16 | 9<<8 | 0<<0 // OS X version 10.9.0
-				ml.data[1] = 10<<16 | 9<<8 | 0<<0 // SDK 10.9.0
+				version = 10<<16 | 9<<8 | 0<<0 // 10.9.0
+			case sys.ARM64:
+				version = 11<<16 | 0<<8 | 0<<0 // 11.0.0
 			}
-		case sys.ARM64:
+			ml := newMachoLoad(ctxt.Arch, LC_BUILD_VERSION, 4)
+			ml.data[0] = uint32(machoPlatform)
+			ml.data[1] = version // OS version
+			ml.data[2] = version // SDK version
+			ml.data[3] = 0       // ntools
 		}
 	}
 
diff --git a/src/cmd/link/link_test.go b/src/cmd/link/link_test.go
index 9369e550f4..985aed49e2 100644
--- a/src/cmd/link/link_test.go
+++ b/src/cmd/link/link_test.go
@@ -333,12 +333,12 @@ func TestXFlag(t *testing.T) {
 	}
 }
 
-var testMacOSVersionSrc = `
+var testMachOBuildVersionSrc = `
 package main
 func main() { }
 `
 
-func TestMacOSVersion(t *testing.T) {
+func TestMachOBuildVersion(t *testing.T) {
 	testenv.MustHaveGoBuild(t)
 
 	t.Parallel()
@@ -346,7 +346,7 @@ func TestMacOSVersion(t *testing.T) {
 	tmpdir := t.TempDir()
 
 	src := filepath.Join(tmpdir, "main.go")
-	err := ioutil.WriteFile(src, []byte(testMacOSVersionSrc), 0666)
+	err := ioutil.WriteFile(src, []byte(testMachOBuildVersionSrc), 0666)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -371,28 +371,28 @@ func TestMacOSVersion(t *testing.T) {
 		t.Fatal(err)
 	}
 	found := false
-	const LC_VERSION_MIN_MACOSX = 0x24
+	const LC_BUILD_VERSION = 0x32
 	checkMin := func(ver uint32) {
 		major, minor := (ver>>16)&0xff, (ver>>8)&0xff
 		if major != 10 || minor < 9 {
-			t.Errorf("LC_VERSION_MIN_MACOSX version %d.%d < 10.9", major, minor)
+			t.Errorf("LC_BUILD_VERSION version %d.%d < 10.9", major, minor)
 		}
 	}
 	for _, cmd := range exem.Loads {
 		raw := cmd.Raw()
 		type_ := exem.ByteOrder.Uint32(raw)
-		if type_ != LC_VERSION_MIN_MACOSX {
+		if type_ != LC_BUILD_VERSION {
 			continue
 		}
-		osVer := exem.ByteOrder.Uint32(raw[8:])
+		osVer := exem.ByteOrder.Uint32(raw[12:])
 		checkMin(osVer)
-		sdkVer := exem.ByteOrder.Uint32(raw[12:])
+		sdkVer := exem.ByteOrder.Uint32(raw[16:])
 		checkMin(sdkVer)
 		found = true
 		break
 	}
 	if !found {
-		t.Errorf("no LC_VERSION_MIN_MACOSX load command found")
+		t.Errorf("no LC_BUILD_VERSION load command found")
 	}
 }