cmd/link: enable external linking on ppc64

Change-Id: Iffe8ccb55b2c555b2cb8c168cebfbfd5892212df
Reviewed-on: https://go-review.googlesource.com/14236Reviewed-by: Russ Cox <rsc@golang.org>

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

@@ -564,13 +564,18 @@ const (
 	R_PPC_EMB_BIT_FLD     = 115
 	R_PPC_EMB_RELSDA      = 116
 
+	R_PPC64_ADDR32       = R_PPC_ADDR32
+	R_PPC64_ADDR16_LO    = R_PPC_ADDR16_LO
+	R_PPC64_ADDR16_HA    = R_PPC_ADDR16_HA
 	R_PPC64_REL24        = R_PPC_REL24
 	R_PPC64_JMP_SLOT     = R_PPC_JMP_SLOT
+	R_PPC64_TPREL16      = R_PPC_TPREL16
 	R_PPC64_ADDR64       = 38
 	R_PPC64_TOC16        = 47
 	R_PPC64_TOC16_LO     = 48
 	R_PPC64_TOC16_HI     = 49
 	R_PPC64_TOC16_HA     = 50
+	R_PPC64_ADDR16_LO_DS = 57
 	R_PPC64_TOC16_DS     = 63
 	R_PPC64_TOC16_LO_DS  = 64
 	R_PPC64_REL16_LO     = 250

src/cmd/link/internal/ppc64/asm.go

@@ -293,8 +293,48 @@ func adddynrel(s *ld.LSym, r *ld.Reloc) {
 }
 
 func elfreloc1(r *ld.Reloc, sectoff int64) int {
-	// TODO(minux)
+	ld.Thearch.Vput(uint64(sectoff))
+
+	elfsym := r.Xsym.ElfsymForReloc()
+	switch r.Type {
+	default:
+		return -1
+
+	case obj.R_ADDR:
+		switch r.Siz {
+		case 4:
+			ld.Thearch.Vput(ld.R_PPC64_ADDR32 | uint64(elfsym)<<32)
+		case 8:
+			ld.Thearch.Vput(ld.R_PPC64_ADDR64 | uint64(elfsym)<<32)
+		default:
 			return -1
+		}
+
+	case obj.R_POWER_TLS_LE:
+		ld.Thearch.Vput(ld.R_PPC64_TPREL16 | uint64(elfsym)<<32)
+
+	case obj.R_ADDRPOWER:
+		ld.Thearch.Vput(ld.R_PPC64_ADDR16_HA | uint64(elfsym)<<32)
+		ld.Thearch.Vput(uint64(r.Xadd))
+		ld.Thearch.Vput(uint64(sectoff + 4))
+		ld.Thearch.Vput(ld.R_PPC64_ADDR16_LO | uint64(elfsym)<<32)
+
+	case obj.R_ADDRPOWER_DS:
+		ld.Thearch.Vput(ld.R_PPC64_ADDR16_HA | uint64(elfsym)<<32)
+		ld.Thearch.Vput(uint64(r.Xadd))
+		ld.Thearch.Vput(uint64(sectoff + 4))
+		ld.Thearch.Vput(ld.R_PPC64_ADDR16_LO_DS | uint64(elfsym)<<32)
+
+	case obj.R_CALLPOWER:
+		if r.Siz != 4 {
+			return -1
+		}
+		ld.Thearch.Vput(ld.R_PPC64_REL24 | uint64(elfsym)<<32)
+
+	}
+	ld.Thearch.Vput(uint64(r.Xadd))
+
+	return 0
 }
 
 func elfsetupplt() {
@@ -381,10 +421,42 @@ func archrelocaddr(r *ld.Reloc, s *ld.LSym, val *int64) int {
 
 func archreloc(r *ld.Reloc, s *ld.LSym, val *int64) int {
 	if ld.Linkmode == ld.LinkExternal {
-		// TODO(minux): translate R_ADDRPOWER and R_CALLPOWER into standard ELF relocations.
-		// R_ADDRPOWER corresponds to R_PPC_ADDR16_HA and R_PPC_ADDR16_LO.
-		// R_CALLPOWER corresponds to R_PPC_REL24.
+		switch r.Type {
+		default:
 			return -1
+
+		case obj.R_POWER_TLS_LE:
+			r.Done = 0
+			// check Outer is nil, Type is TLSBSS?
+			r.Xadd = r.Add
+			r.Xsym = r.Sym
+			return 0
+
+		case obj.R_ADDRPOWER,
+			obj.R_ADDRPOWER_DS:
+			r.Done = 0
+
+			// set up addend for eventual relocation via outer symbol.
+			rs := r.Sym
+			r.Xadd = r.Add
+			for rs.Outer != nil {
+				r.Xadd += ld.Symaddr(rs) - ld.Symaddr(rs.Outer)
+				rs = rs.Outer
+			}
+
+			if rs.Type != obj.SHOSTOBJ && rs.Type != obj.SDYNIMPORT && rs.Sect == nil {
+				ld.Diag("missing section for %s", rs.Name)
+			}
+			r.Xsym = rs
+
+			return 0
+
+		case obj.R_CALLPOWER:
+			r.Done = 0
+			r.Xsym = r.Sym
+			r.Xadd = r.Add
+			return 0
+		}
 	}
 
 	switch r.Type {

src/cmd/link/internal/ppc64/obj.go

@@ -111,6 +111,9 @@ 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 obj.Hlinux:
+		break
 	}
 
 	switch ld.HEADTYPE {