cmd/link: add support for openbsd/ppc64

Add linker support for the openbsd/ppc64 port.

Updates #56001

Change-Id: I18bc19b4086599996aebfbe68f2e85e1200589ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/475619
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Joel Sing <joel@sing.id.au>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Paul Murphy <murp@ibm.com>
Reviewed-by: Eric Grosse <grosse@gmail.com>

src/cmd/dist/build.go

@@ -589,7 +589,9 @@ func mustLinkExternal(goos, goarch string, cgoEnabled bool) bool {
 			}
 		case "ppc64":
 			// Big Endian PPC64 cgo internal linking is not implemented for aix or linux.
-			return true
+			if goos == "aix" || goos == "linux" {
+				return true
+			}
 		}
 
 		switch goos {

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

@@ -217,7 +217,7 @@ func determineLinkMode(ctxt *Link) {
 		}
 	case LinkExternal:
 		switch {
-		case buildcfg.GOARCH == "ppc64" && buildcfg.GOOS != "aix":
+		case buildcfg.GOARCH == "ppc64" && buildcfg.GOOS == "linux":
 			Exitf("external linking not supported for %s/ppc64", buildcfg.GOOS)
 		}
 	}

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

@@ -243,7 +243,7 @@ func Elfinit(ctxt *Link) {
 	switch ctxt.Arch.Family {
 	// 64-bit architectures
 	case sys.PPC64, sys.S390X:
-		if ctxt.Arch.ByteOrder == binary.BigEndian {
+		if ctxt.Arch.ByteOrder == binary.BigEndian && ctxt.HeadType != objabi.Hopenbsd {
 			ehdr.Flags = 1 /* Version 1 ABI */
 		} else {
 			ehdr.Flags = 2 /* Version 2 ABI */

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

@@ -270,9 +270,8 @@ func genstubs(ctxt *ld.Link, ldr *loader.Loader) {
 	for _, s := range ctxt.Textp {
 		relocs := ldr.Relocs(s)
 		for i := 0; i < relocs.Count(); i++ {
-			r := relocs.At(i)
-			switch r.Type() {
-			case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_REL24):
+			switch r := relocs.At(i); r.Type() {
+			case objabi.ElfRelocOffset + objabi.RelocType(elf.R_PPC64_REL24), objabi.R_CALLPOWER:
 				switch ldr.SymType(r.Sym()) {
 				case sym.SDYNIMPORT:
 					// This call goes through the PLT, generate and call through a PLT stub.
@@ -633,7 +632,7 @@ func addelfdynrel(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s lo
 		su.SetRelocAdd(rIdx, r.Add()+localEoffset)
 
 		if targType == sym.SDYNIMPORT {
-			// Should have been handled in elfsetupplt
+			// Should have been handled in genstubs
 			ldr.Errorf(s, "unexpected R_PPC64_REL24 for dyn import")
 		}
 
@@ -1575,7 +1574,6 @@ func archrelocvariant(target *ld.Target, ldr *loader.Loader, r loader.Reloc, rv
 			var o1 uint32
 			if target.IsBigEndian() {
 				o1 = binary.BigEndian.Uint32(p[r.Off()-2:])
-
 			} else {
 				o1 = binary.LittleEndian.Uint32(p[r.Off():])
 			}

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

@@ -71,7 +71,7 @@ func Init() (*sys.Arch, ld.Arch) {
 			LinuxdynldMusl: musl,
 
 			Freebsddynld:   "XXX",
-			Openbsddynld:   "XXX",
+			Openbsddynld:   "/usr/libexec/ld.so",
 			Netbsddynld:    "XXX",
 			Dragonflydynld: "XXX",
 			Solarisdynld:   "XXX",
@@ -100,7 +100,8 @@ func archinit(ctxt *ld.Link) {
 			*ld.FlagRound = 4096
 		}
 
-	case objabi.Hlinux: /* ppc64 elf */
+	case objabi.Hlinux, /* ppc64 elf */
+		objabi.Hopenbsd:
 		ld.Elfinit(ctxt)
 		ld.HEADR = ld.ELFRESERVE
 		if *ld.FlagTextAddr == -1 {

src/internal/platform/supported.go

@@ -99,7 +99,9 @@ func MustLinkExternal(goos, goarch string, withCgo bool) bool {
 		case "ppc64":
 			// Big Endian PPC64 cgo internal linking is not implemented for aix or linux.
 			// https://go.dev/issue/8912
-			return true
+			if goos == "aix" || goos == "linux" {
+				return true
+			}
 		}
 
 		switch goos {