cmd/internal/objabi, internal/runtime: increase nosplit limit on OpenBSD

OpenBSD is bumping up against the nosplit limit, and openbsd/ppc64
is over it. Increase StackGuardMultiplier on OpenBSD, matching AIX.

Change-Id: I61e17c99ce77e1fd3f368159dc4615aeae99e913
Reviewed-on: https://go-review.googlesource.com/c/go/+/632996
Reviewed-by: Keith Randall <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Auto-Submit: Damien Neil <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>

Author: neild

src/cmd/internal/objabi/stack.go

@@ -20,8 +20,8 @@ func StackNosplit(race bool) int {
 func stackGuardMultiplier(race bool) int {
 	// This arithmetic must match that in internal/runtime/sys/consts.go:StackGuardMultiplier.
 	n := 1
-	// On AIX, a larger stack is needed for syscalls.
-	if buildcfg.GOOS == "aix" {
+	// On AIX and OpenBSD, a larger stack is needed for syscalls.
+	if buildcfg.GOOS == "aix" || buildcfg.GOOS == "openbsd" {
 		n += 1
 	}
 	// The race build also needs more stack.

src/internal/runtime/sys/consts.go

@@ -9,10 +9,10 @@ import (
 	"internal/goos"
 )
 
-// AIX requires a larger stack for syscalls.
+// AIX and OpenBSD require a larger stack for syscalls.
 // The race build also needs more stack. See issue 54291.
 // This arithmetic must match that in cmd/internal/objabi/stack.go:stackGuardMultiplier.
-const StackGuardMultiplier = 1 + goos.IsAix + isRace
+const StackGuardMultiplier = 1 + goos.IsAix + goos.IsOpenbsd + isRace
 
 // DefaultPhysPageSize is the default physical page size.
 const DefaultPhysPageSize = goarch.DefaultPhysPageSize

test/nosplit.go

@@ -1,6 +1,6 @@
 // run
 
-//go:build !nacl && !js && !aix && !wasip1 && !gcflags_noopt && gc
+//go:build !nacl && !js && !aix && !openbsd && !wasip1 && !gcflags_noopt && gc
 
 // Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style