cmd/link: hide funcsym symbols

As far as I can tell, this check has been
non-functional since it was introduced.

This cuts 57k off cmd/go and 70k off cmd/compile.

Based on golang.org/cl/24710 by Josh Bleecher Snyder.

Change-Id: I1162a066971df1a067b50afa1cfa0819a6913574
Reviewed-on: https://go-review.googlesource.com/27830Reviewed-by: David Crawshaw <crawshaw@golang.org>

src/cmd/link/internal/ld/data.go

@@ -1225,7 +1225,7 @@ func (ctxt *Link) dodata() {
 			for _, s := range data[symnro] {
 				isRelro := len(s.R) > 0
 				switch s.Type {
-				case obj.STYPE, obj.SGOSTRINGHDR, obj.STYPERELRO, obj.SGOSTRINGHDRRELRO:
+				case obj.STYPE, obj.SGOSTRINGHDR, obj.STYPERELRO, obj.SGOSTRINGHDRRELRO, obj.SGOFUNCRELRO:
 					// Symbols are not sorted yet, so it is possible
 					// that an Outer symbol has been changed to a
 					// relro Type before it reaches here.
@@ -1567,7 +1567,7 @@ func (ctxt *Link) dodata() {
 			for _, s := range data[symn] {
 				datsize = aligndatsize(datsize, s)
 				if s.Outer != nil && s.Outer.Sect != nil && s.Outer.Sect != sect {
-					ctxt.Diag("s.Outer (%s) in different section from s (%s)", s.Outer.Name, s.Name)
+					ctxt.Diag("s.Outer (%s) in different section from s (%s), %s != %s", s.Outer.Name, s.Name, s.Outer.Sect.Name, sect.Name)
 				}
 				s.Sect = sect
 				s.Type = obj.SRODATA

src/cmd/link/internal/ld/symtab.go

@@ -400,6 +400,15 @@ func (ctxt *Link) symtab() {
 		symgcbits      = groupSym("runtime.gcbits.*", obj.SGCBITS)
 	)
 
+	var symgofuncrel *Symbol
+	if !DynlinkingGo() {
+		if UseRelro() {
+			symgofuncrel = groupSym("go.funcrel.*", obj.SGOFUNCRELRO)
+		} else {
+			symgofuncrel = symgofunc
+		}
+	}
+
 	symtypelink := Linklookup(ctxt, "runtime.typelink", 0)
 	symtypelink.Type = obj.STYPELINK
 
@@ -468,10 +477,17 @@ func (ctxt *Link) symtab() {
 			s.Attr |= AttrHidden
 			s.Outer = symgcbits
 
-		case strings.HasPrefix(s.Name, "go.func."):
-			s.Type = obj.SGOFUNC
-			s.Attr |= AttrHidden
-			s.Outer = symgofunc
+		case strings.HasSuffix(s.Name, "·f"):
+			if !DynlinkingGo() {
+				s.Attr |= AttrHidden
+			}
+			if UseRelro() {
+				s.Type = obj.SGOFUNCRELRO
+				s.Outer = symgofuncrel
+			} else {
+				s.Type = obj.SGOFUNC
+				s.Outer = symgofunc
+			}
 
 		case strings.HasPrefix(s.Name, "gcargs."), strings.HasPrefix(s.Name, "gclocals."), strings.HasPrefix(s.Name, "gclocals·"):
 			s.Type = obj.SGOFUNC