cmd/link: add support for R_AARCH64_LDST128_ABS_LO12_NC relocations

These are encountered when compiling with -linkmode=internal on openbsd/arm64.

Fixes #31940

Change-Id: I851e6a7da0a3fb3e23b4fa2ed8dce3051c680f11
Reviewed-on: https://go-review.googlesource.com/c/go/+/176697
Run-TryBot: Ian Lance Taylor <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: 4a6f656c

src/cmd/internal/objabi/reloctype.go

@@ -149,6 +149,9 @@ const (
 	// R_ARM64_LDST64 sets a LD/ST immediate value to bits [11:3] of a local address.
 	R_ARM64_LDST64
 
+	// R_ARM64_LDST128 sets a LD/ST immediate value to bits [11:4] of a local address.
+	R_ARM64_LDST128
+
 	// PPC64.
 
 	// R_POWER_TLS_LE is used to implement the "local exec" model for tls

src/cmd/internal/objabi/reloctype_string.go

@@ -194,6 +194,13 @@ func adddynrel(ctxt *ld.Link, s *sym.Symbol, r *sym.Reloc) bool {
 		}
 		r.Type = objabi.R_ARM64_LDST64
 		return true
+
+	case objabi.ElfRelocOffset + objabi.RelocType(elf.R_AARCH64_LDST128_ABS_LO12_NC):
+		if targ.Type == sym.SDYNIMPORT {
+			ld.Errorf(s, "unexpected relocation for dynamic symbol %s", targ.Name)
+		}
+		r.Type = objabi.R_ARM64_LDST128
+		return true
 	}
 
 	switch r.Type {
@@ -665,6 +672,14 @@ func archreloc(ctxt *ld.Link, r *sym.Reloc, s *sym.Symbol, val int64) (int64, bo
 		}
 		o0 := (uint32(t&0xfff) >> 3) << 10
 		return val | int64(o0), true
+
+	case objabi.R_ARM64_LDST128:
+		t := ld.Symaddr(r.Sym) + r.Add - ((s.Value + int64(r.Off)) &^ 0xfff)
+		if t&15 != 0 {
+			ld.Errorf(s, "invalid address: %x for relocation type: R_AARCH64_LDST128_ABS_LO12_NC", t)
+		}
+		o0 := (uint32(t&0xfff) >> 4) << 10
+		return val | int64(o0), true
 	}
 
 	return val, false

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

@@ -1179,6 +1179,7 @@ func relSize(arch *sys.Arch, pn string, elftype uint32) (uint8, error) {
 		ARM64 | uint32(elf.R_AARCH64_LDST8_ABS_LO12_NC)<<16,
 		ARM64 | uint32(elf.R_AARCH64_LDST32_ABS_LO12_NC)<<16,
 		ARM64 | uint32(elf.R_AARCH64_LDST64_ABS_LO12_NC)<<16,
+		ARM64 | uint32(elf.R_AARCH64_LDST128_ABS_LO12_NC)<<16,
 		ARM64 | uint32(elf.R_AARCH64_PREL32)<<16,
 		ARM64 | uint32(elf.R_AARCH64_JUMP26)<<16,
 		AMD64 | uint32(elf.R_X86_64_PC32)<<16,