cmd/internal/obj, cmd/link: support inital-exec TLS on arm64

Change-Id: Iaf9159a68fa395245bc20ccb4a2a377f89371a7e
Reviewed-on: https://go-review.googlesource.com/13996
Reviewed-by: David Crawshaw <crawshaw@golang.org>

src/cmd/internal/obj/arm64/a.out.go

@@ -321,7 +321,16 @@ const (
 	C_LOREG
 
 	C_ADDR // TODO(aram): explain difference from C_VCONADDR
-	C_TLS  // TLS var, i.e. memory address containing offset for the var
+
+	// TLS "var" in local exec mode: will become a constant offset from
+	// thread local base that is ultimately chosen by the program linker.
+	C_TLS_LE
+
+	// TLS "var" in initial exec mode: will become a memory address (chosen
+	// by the program linker) that the dynamic linker will fill with the
+	// offset from the thread local base.
+	C_TLS_IE
+
 	C_ROFF // register offset (including register extended)
 
 	C_GOK

src/cmd/internal/obj/arm64/anames7.go

@@ -55,7 +55,8 @@ var cnames7 = []string{
 	"UOREG64K",
 	"LOREG",
 	"ADDR",
-	"TLS",
+	"TLS_LE",
+	"TLS_IE",
 	"ROFF",
 	"GOK",
 	"TEXTSIZE",

src/cmd/internal/obj/arm64/asm7.go

@@ -270,7 +270,8 @@ var optab = []Optab{
 	{AMOVH, C_ADDR, C_NONE, C_REG, 65, 12, 0, 0, 0},
 	{AMOVW, C_ADDR, C_NONE, C_REG, 65, 12, 0, 0, 0},
 	{AMOVD, C_ADDR, C_NONE, C_REG, 65, 12, 0, 0, 0},
-	{AMOVD, C_TLS, C_NONE, C_REG, 69, 4, 0, 0, 0},
+	{AMOVD, C_TLS_LE, C_NONE, C_REG, 69, 4, 0, 0, 0},
+	{AMOVD, C_TLS_IE, C_NONE, C_REG, 70, 8, 0, 0, 0},
 	{AMUL, C_REG, C_REG, C_REG, 15, 4, 0, 0, 0},
 	{AMUL, C_REG, C_NONE, C_REG, 15, 4, 0, 0, 0},
 	{AMADD, C_REG, C_REG, C_REG, 15, 4, 0, 0, 0},
@@ -970,7 +971,11 @@ func aclass(ctxt *obj.Link, a *obj.Addr) int {
 			ctxt.Instoffset = a.Offset
 			if a.Sym != nil { // use relocation
 				if a.Sym.Type == obj.STLSBSS {
-					return C_TLS
+					if ctxt.Flag_shared != 0 {
+						return C_TLS_IE
+					} else {
+						return C_TLS_LE
+					}
 				}
 				return C_ADDR
 			}
@@ -1045,10 +1050,12 @@ func aclass(ctxt *obj.Link, a *obj.Addr) int {
 
 		case obj.NAME_EXTERN,
 			obj.NAME_STATIC:
-			s := a.Sym
+			if a.Sym == nil {
-			if s == nil {
 				break
 			}
+			if a.Sym.Type == obj.STLSBSS {
+				ctxt.Diag("taking address of TLS variable is not supported")
+			}
 			ctxt.Instoffset = a.Offset
 			return C_VCONADDR
 
@@ -2757,7 +2764,7 @@ func asmout(ctxt *obj.Link, p *obj.Prog, o *Optab, out []uint32) {
 		rel.Add = p.From.Offset
 		rel.Type = obj.R_ADDRARM64
 
-	case 69: /* movd $tlsvar, reg -> movz reg, 0 + reloc */
+	case 69: /* LE model movd $tlsvar, reg -> movz reg, 0 + reloc */
 		o1 = opirr(ctxt, AMOVZ)
 		o1 |= uint32(p.To.Reg & 31)
 		rel := obj.Addrel(ctxt.Cursym)
@@ -2769,6 +2776,19 @@ func asmout(ctxt *obj.Link, p *obj.Prog, o *Optab, out []uint32) {
 			ctxt.Diag("invalid offset on MOVW $tlsvar")
 		}
 
+	case 70: /* IE model movd $tlsvar, reg -> adrp REGTMP, 0; ldr reg, [REGTMP, #0] + relocs */
+		o1 = ADR(1, 0, REGTMP)
+		o2 = olsr12u(ctxt, int32(opldr12(ctxt, AMOVD)), 0, REGTMP, int(p.To.Reg))
+		rel := obj.Addrel(ctxt.Cursym)
+		rel.Off = int32(ctxt.Pc)
+		rel.Siz = 8
+		rel.Sym = p.From.Sym
+		rel.Add = 0
+		rel.Type = obj.R_ARM64_TLS_IE
+		if p.From.Offset != 0 {
+			ctxt.Diag("invalid offset on MOVW $tlsvar")
+		}
+
 	// This is supposed to be something that stops execution.
 	// It's not supposed to be reached, ever, but if it is, we'd
 	// like to be able to tell how we got there.  Assemble as

src/cmd/internal/obj/link.go

@@ -446,6 +446,11 @@ const (
 	// local base to the thread local variable defined by the referenced (thread
 	// local) symbol. Error if the offset does not fit into 16 bits.
 	R_ARM64_TLS_LE
+
+	// Relocates an ADRP; LD64 instruction sequence to load the offset between
+	// the thread local base and the thread local variable defined by the
+	// referenced (thread local) symbol from the GOT.
+	R_ARM64_TLS_IE
 )
 
 type Auto struct {

src/cmd/link/internal/arm64/asm.go

@@ -76,6 +76,12 @@ func elfreloc1(r *ld.Reloc, sectoff int64) int {
 	case obj.R_ARM64_TLS_LE:
 		ld.Thearch.Vput(ld.R_AARCH64_TLSLE_MOVW_TPREL_G0 | uint64(elfsym)<<32)
 
+	case obj.R_ARM64_TLS_IE:
+		ld.Thearch.Vput(ld.R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21 | uint64(elfsym)<<32)
+		ld.Thearch.Vput(uint64(r.Xadd))
+		ld.Thearch.Vput(uint64(sectoff + 4))
+		ld.Thearch.Vput(ld.R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC | uint64(elfsym)<<32)
+
 	case obj.R_CALLARM64:
 		if r.Siz != 4 {
 			return -1
@@ -229,7 +235,8 @@ func archreloc(r *ld.Reloc, s *ld.LSym, val *int64) int {
 			return 0
 
 		case obj.R_CALLARM64,
-			obj.R_ARM64_TLS_LE:
+			obj.R_ARM64_TLS_LE,
+			obj.R_ARM64_TLS_IE:
 			r.Done = 0
 			r.Xsym = r.Sym
 			r.Xadd = r.Add

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

@@ -356,6 +356,8 @@ const (
 	R_AARCH64_CALL26                      = 283
 	R_AARCH64_ADR_PREL_PG_HI21            = 275
 	R_AARCH64_ADD_ABS_LO12_NC             = 277
+	R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21   = 541
+	R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC = 542
 	R_AARCH64_TLSLE_MOVW_TPREL_G0         = 547
 
 	R_ALPHA_NONE           = 0