cmd/internal/ld, cmd/7l: external linking support for linux/arm64

Based on Michael Hudson-Doyle's patch:
https://github.com/4ad/go/commit/b735215ee41b4237ec393d4669f6f55d4b27babc

Change-Id: I309e3df7608b9eef9339196fdc50dedf5f9439f0
Reviewed-on: https://go-review.googlesource.com/8437Reviewed-by: Aram Hăvărneanu <aram@mgk.ro>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

src/cmd/7l/asm.go

@@ -66,8 +66,33 @@ func adddynrel(s *ld.LSym, r *ld.Reloc) {
 }
 
 func elfreloc1(r *ld.Reloc, sectoff int64) int {
-	// TODO(minux)
-	return -1
+	ld.Thearch.Vput(uint64(sectoff))
+
+	elfsym := r.Xsym.Elfsym
+	switch r.Type {
+	default:
+		return -1
+
+	case ld.R_ADDR:
+		switch r.Siz {
+		case 4:
+			ld.Thearch.Vput(ld.R_AARCH64_ABS32 | uint64(elfsym)<<32)
+		case 8:
+			ld.Thearch.Vput(ld.R_AARCH64_ABS64 | uint64(elfsym)<<32)
+		default:
+			return -1
+		}
+
+	case ld.R_CALLARM64:
+		if r.Siz != 4 {
+			return -1
+		}
+		ld.Thearch.Vput(ld.R_AARCH64_CALL26 | uint64(elfsym)<<32)
+
+	}
+	ld.Thearch.Vput(uint64(r.Xadd))
+
+	return 0
 }
 
 func elfsetupplt() {
@@ -81,8 +106,18 @@ func machoreloc1(r *ld.Reloc, sectoff int64) int {
 
 func archreloc(r *ld.Reloc, s *ld.LSym, val *int64) int {
 	if ld.Linkmode == ld.LinkExternal {
-		// TODO(minux): translate R_CALLARM64 into standard ELF relocation.
-		return -1
+		switch r.Type {
+		default:
+			return -1
+
+		case ld.R_CALLARM64:
+			r.Done = 0
+			r.Xsym = r.Sym
+			*val = int64(0xfc000000 & uint32(r.Add))
+			r.Xadd = int64((uint32(r.Add) &^ 0xfc000000) * 4)
+			r.Add = 0
+			return 0
+		}
 	}
 
 	switch r.Type {
@@ -108,7 +143,7 @@ func archrelocvariant(r *ld.Reloc, s *ld.LSym, t int64) int64 {
 }
 
 func adddynsym(ctxt *ld.Link, s *ld.LSym) {
-	log.Fatalf("adddynsym not implemented")
+	// TODO(minux): implement when needed.
 }
 
 func adddynlib(lib string) {

src/cmd/7l/obj.go

@@ -96,6 +96,8 @@ func archinit() {
 		if ld.Linkmode == ld.LinkExternal && obj.Getgoextlinkenabled() != "1" {
 			log.Fatalf("cannot use -linkmode=external with -H %s", ld.Headstr(int(ld.HEADTYPE)))
 		}
+	case ld.Hlinux:
+		break
 	}
 
 	switch ld.HEADTYPE {

src/cmd/internal/ld/dwarf.go

@@ -2367,12 +2367,13 @@ func dwarfaddshstrings(shstrtab *LSym) {
 	elfstrdbg[ElfStrDebugStr] = Addstring(shstrtab, ".debug_str")
 	elfstrdbg[ElfStrGDBScripts] = Addstring(shstrtab, ".debug_gdb_scripts")
 	if Linkmode == LinkExternal {
-		if Thearch.Thechar == '6' || Thearch.Thechar == '9' {
+		switch Thearch.Thechar {
+		case '6', '7', '9':
 			elfstrdbg[ElfStrRelDebugInfo] = Addstring(shstrtab, ".rela.debug_info")
 			elfstrdbg[ElfStrRelDebugAranges] = Addstring(shstrtab, ".rela.debug_aranges")
 			elfstrdbg[ElfStrRelDebugLine] = Addstring(shstrtab, ".rela.debug_line")
 			elfstrdbg[ElfStrRelDebugFrame] = Addstring(shstrtab, ".rela.debug_frame")
-		} else {
+		default:
 			elfstrdbg[ElfStrRelDebugInfo] = Addstring(shstrtab, ".rel.debug_info")
 			elfstrdbg[ElfStrRelDebugAranges] = Addstring(shstrtab, ".rel.debug_aranges")
 			elfstrdbg[ElfStrRelDebugLine] = Addstring(shstrtab, ".rel.debug_line")
@@ -2419,9 +2420,10 @@ func dwarfaddelfsectionsyms() {
 
 func dwarfaddelfrelocheader(elfstr int, shdata *ElfShdr, off int64, size int64) {
 	sh := newElfShdr(elfstrdbg[elfstr])
-	if Thearch.Thechar == '6' || Thearch.Thechar == '9' {
+	switch Thearch.Thechar {
+	case '6', '7', '9':
 		sh.type_ = SHT_RELA
-	} else {
+	default:
 		sh.type_ = SHT_REL
 	}
 

src/cmd/internal/ld/elf.go

@@ -1489,10 +1489,11 @@ func elfshreloc(sect *Section) *ElfShdr {
 
 	var prefix string
 	var typ int
-	if Thearch.Thechar == '6' || Thearch.Thechar == '9' {
+	switch Thearch.Thechar {
+	case '6', '7', '9':
 		prefix = ".rela"
 		typ = SHT_RELA
-	} else {
+	default:
 		prefix = ".rel"
 		typ = SHT_REL
 	}
@@ -1657,9 +1658,10 @@ func doelf() {
 
 	if Flag_shared != 0 {
 		Addstring(shstrtab, ".init_array")
-		if Thearch.Thechar == '6' || Thearch.Thechar == '9' {
+		switch Thearch.Thechar {
+		case '6', '7', '9':
 			Addstring(shstrtab, ".rela.init_array")
-		} else {
+		default:
 			Addstring(shstrtab, ".rel.init_array")
 		}
 	}
@@ -1683,10 +1685,11 @@ func doelf() {
 		Addstring(shstrtab, ".dynamic")
 		Addstring(shstrtab, ".dynsym")
 		Addstring(shstrtab, ".dynstr")
-		if Thearch.Thechar == '6' || Thearch.Thechar == '9' {
+		switch Thearch.Thechar {
+		case '6', '7', '9':
 			Addstring(shstrtab, ".rela")
 			Addstring(shstrtab, ".rela.plt")
-		} else {
+		default:
 			Addstring(shstrtab, ".rel")
 			Addstring(shstrtab, ".rel.plt")
 		}
@@ -1700,9 +1703,10 @@ func doelf() {
 
 		s.Type = SELFROSECT
 		s.Reachable = true
-		if Thearch.Thechar == '6' || Thearch.Thechar == '9' {
+		switch Thearch.Thechar {
+		case '6', '7', '9':
 			s.Size += ELF64SYMSIZE
-		} else {
+		default:
 			s.Size += ELF32SYMSIZE
 		}
 
@@ -1791,9 +1795,10 @@ func doelf() {
 		elfwritedynentsym(s, DT_HASH, Linklookup(Ctxt, ".hash", 0))
 
 		elfwritedynentsym(s, DT_SYMTAB, Linklookup(Ctxt, ".dynsym", 0))
-		if Thearch.Thechar == '6' || Thearch.Thechar == '9' {
+		switch Thearch.Thechar {
+		case '6', '7', '9':
 			Elfwritedynent(s, DT_SYMENT, ELF64SYMSIZE)
-		} else {
+		default:
 			Elfwritedynent(s, DT_SYMENT, ELF32SYMSIZE)
 		}
 		elfwritedynentsym(s, DT_STRTAB, Linklookup(Ctxt, ".dynstr", 0))

src/cmd/internal/ld/lib.go

@@ -711,6 +711,9 @@ func hostlink() {
 
 	case '5':
 		argv = append(argv, "-marm")
+
+	case '7':
+		// nothing needed
 	}
 
 	if Debug['s'] == 0 && debug_s == 0 {

src/cmd/internal/ld/symtab.go

@@ -167,11 +167,9 @@ func putelfsectionsym(s *LSym, shndx int) {
 
 func putelfsymshndx(sympos int64, shndx int) {
 	here := Cpos()
-	switch Thearch.Thechar {
-	case '6':
+	if elf64 != 0 {
 		Cseek(sympos + 6)
-
-	default:
+	} else {
 		Cseek(sympos + 14)
 	}