From fcf1774824c54da91f0bcc86ea07983a1f305fe8 Mon Sep 17 00:00:00 2001
From: kettenis <kettenis@openbsd.org>
Date: Sun, 9 Apr 2023 19:48:37 +0000
Subject: [PATCH] So clang 13 miscompiles dev/usb/umass_scsi.c with the
 combination if -Oz and -mbranch-protection=bti.  So turn off the BTI
 protection in ramdisk kernels for now.

ok deraadt@, miod@, phessler@
---
 sys/arch/arm64/arm64/pmap.c        | 4 +++-
 sys/arch/arm64/conf/Makefile.arm64 | 7 +++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/sys/arch/arm64/arm64/pmap.c b/sys/arch/arm64/arm64/pmap.c
index edda6e8fe9a..beb0bd7f5c0 100644
--- a/sys/arch/arm64/arm64/pmap.c
+++ b/sys/arch/arm64/arm64/pmap.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: pmap.c,v 1.93 2023/03/27 19:02:47 kettenis Exp $ */
+/* $OpenBSD: pmap.c,v 1.94 2023/04/09 19:48:37 kettenis Exp $ */
 /*
  * Copyright (c) 2008-2009,2014-2016 Dale Rahn <drahn@dalerahn.com>
  *
@@ -1688,8 +1688,10 @@ pmap_pte_update(struct pte_desc *pted, uint64_t *pl3)
 	else
 		access_bits = ap_bits_user[pted->pted_pte & PROT_MASK];
 
+#ifndef SMALL_KERNEL
 	if (pm == pmap_kernel())
 		access_bits |= ATTR_GP;
+#endif
 
 	pte = (pted->pted_pte & PTE_RPGN) | attr | access_bits | L3_P;
 	*pl3 = access_bits ? pte : 0;
diff --git a/sys/arch/arm64/conf/Makefile.arm64 b/sys/arch/arm64/conf/Makefile.arm64
index 6bd73a674f6..1719e3d045d 100644
--- a/sys/arch/arm64/conf/Makefile.arm64
+++ b/sys/arch/arm64/conf/Makefile.arm64
@@ -1,4 +1,4 @@
-#	$OpenBSD: Makefile.arm64,v 1.45 2023/03/27 19:02:47 kettenis Exp $
+#	$OpenBSD: Makefile.arm64,v 1.46 2023/04/09 19:48:37 kettenis Exp $
 
 # For instructions on building kernels consult the config(8) and options(4)
 # manual pages.
@@ -61,7 +61,7 @@ CWARNFLAGS+=	-Wno-deprecated-non-prototype -Wno-unknown-warning-option
 
 CMACHFLAGS=	-march=armv8-a+nofp+nosimd \
 		-fno-omit-frame-pointer -mno-omit-leaf-frame-pointer \
-		-ffixed-x18 -mbranch-protection=bti
+		-ffixed-x18
 CMACHFLAGS+=	-ffreestanding ${NOPIE_FLAGS}
 SORTR=		sort -R
 .if ${IDENT:M-DNO_PROPOLICE}
@@ -70,6 +70,9 @@ CMACHFLAGS+=	-fno-stack-protector
 .if ${IDENT:M-DSMALL_KERNEL}
 SORTR=		cat
 COPTIMIZE?=	-Oz
+CMACHFLAGS+=	-mbranch-protection=none
+.else
+CMACHFLAGS+=	-mbranch-protection=bti
 .endif
 
 DEBUG?=		-g
-- 
2.20.1