From: Keith Randall <khr@golang.org>
Date: Fri, 15 Oct 2021 20:52:05 +0000 (-0700)
Subject: cmd/asm: report an error when trying to do spectre on 386
X-Git-Tag: go1.18beta1~871
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=c091767d87b7a6ef6016286bc0fae8add59b92de;p=gostls13.git

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 <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
---

diff --git a/src/cmd/internal/obj/x86/asm6.go b/src/cmd/internal/obj/x86/asm6.go
index 43ce832b17..6555756fd3 100644
--- 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 {