cmd/asm: report an error when trying to do spectre on 386

The compiler refuses to do spectre mitigation on 386, but the assembler doesn't. Fix that. Fixes #49006 Change-Id: I887b6f7ed7523a47f463706f06ca4c2c6e828b6b Reviewed-on: https://go-review.googlesource.com/c/go/+/356190 Trust: Keith Randall <[email protected]> Run-TryBot: Keith Randall <[email protected]> TryBot-Result: Go Bot <[email protected]> Reviewed-by: Bryan C. Mills <[email protected]>
golang · Oct 18, 2021 · c091767 · c091767
1 parent 74acbaf
commit c091767
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/src/cmd/internal/obj/x86/asm6.go b/src/cmd/internal/obj/x86/asm6.go
@@ -2035,6 +2035,11 @@ type nopPad struct {
 }
 
 func span6(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
+	if ctxt.Retpoline && ctxt.Arch.Family == sys.I386 {
+		ctxt.Diag("-spectre=ret not supported on 386")
+		ctxt.Retpoline = false // don't keep printing
+	}
+
 	pjc := makePjcCtx(ctxt)
 
 	if s.P != nil {