[release-branch.go1.21] cmd/link: use symbol-targeted relocation for initializers on Mach-O

Apple's new linker, ld-prime from Xcode 15 beta, when handling
initializers in __mod_init_func, drops the offset in the data,
resolving the relocation to the beginning of the section. The
latest version of ld-prime rejects non-zero addend. We need to use
symbol-targeted "external" relocations, so that it doesn't need
an addend and can be resolved correctly. This also works fine with
ld64.

Fixes #60694.
For #61229.

Change-Id: Ida2be6aa4c91bfcd142b755e2ec63aabfbbd77a6
Reviewed-on: https://go-review.googlesource.com/c/go/+/502616
Run-TryBot: Cherry Mui <[email protected]>
Reviewed-by: Than McIntosh <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
(cherry picked from commit bad9ca8)
Reviewed-on: https://go-review.googlesource.com/c/go/+/514535

Author: cherrymui

src/cmd/link/internal/amd64/asm.go

@@ -446,7 +446,7 @@ func machoreloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sy
 	rs := r.Xsym
 	rt := r.Type
 
-	if ldr.SymType(rs) == sym.SHOSTOBJ || rt == objabi.R_PCREL || rt == objabi.R_GOTPCREL || rt == objabi.R_CALL {
+	if rt == objabi.R_PCREL || rt == objabi.R_GOTPCREL || rt == objabi.R_CALL || ldr.SymType(rs) == sym.SHOSTOBJ || ldr.SymType(s) == sym.SINITARR {
 		if ldr.SymDynid(rs) < 0 {
 			ldr.Errorf(s, "reloc %d (%s) to non-macho symbol %s type=%d (%s)", rt, sym.RelocName(arch, rt), ldr.SymName(rs), ldr.SymType(rs), ldr.SymType(rs))
 			return false

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

@@ -545,10 +545,11 @@ func machoreloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sy
 		}
 	}
 
-	if ldr.SymType(rs) == sym.SHOSTOBJ || rt == objabi.R_CALLARM64 ||
+	if rt == objabi.R_CALLARM64 ||
 		rt == objabi.R_ARM64_PCREL_LDST8 || rt == objabi.R_ARM64_PCREL_LDST16 ||
 		rt == objabi.R_ARM64_PCREL_LDST32 || rt == objabi.R_ARM64_PCREL_LDST64 ||
-		rt == objabi.R_ADDRARM64 || rt == objabi.R_ARM64_GOTPCREL {
+		rt == objabi.R_ADDRARM64 || rt == objabi.R_ARM64_GOTPCREL ||
+		ldr.SymType(rs) == sym.SHOSTOBJ || ldr.SymType(s) == sym.SINITARR {
 		if ldr.SymDynid(rs) < 0 {
 			ldr.Errorf(s, "reloc %d (%s) to non-macho symbol %s type=%d (%s)", rt, sym.RelocName(arch, rt), ldr.SymName(rs), ldr.SymType(rs), ldr.SymType(rs))
 			return false

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

@@ -368,7 +368,9 @@ func (st *relocSymState) relocsym(s loader.Sym, P []byte) {
 						o = 0
 					}
 				} else if target.IsDarwin() {
-					if ldr.SymType(rs) != sym.SHOSTOBJ {
+					if ldr.SymType(rs) != sym.SHOSTOBJ && ldr.SymType(s) != sym.SINITARR {
+						// ld-prime drops the offset in data for SINITARR. We need to use
+						// symbol-targeted relocation. See also machoreloc1.
 						o += ldr.SymValue(rs)
 					}
 				} else if target.IsWindows() {