From 4f1e26187e39b39f020e52e9d5a75e95ac937cc8 Mon Sep 17 00:00:00 2001
From: jsg <jsg@openbsd.org>
Date: Wed, 5 May 2021 01:24:57 +0000
Subject: [PATCH] riscv: Clear SUM in SSTATUS for supervisor mode exceptions.

From John Baldwin
753bcca440a4d2c95f48536b586131b84c0bb87e in FreeBSD

ok kettenis@ mlarkin@
---
 sys/arch/riscv64/riscv64/exception.S | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sys/arch/riscv64/riscv64/exception.S b/sys/arch/riscv64/riscv64/exception.S
index 7d461ff06e2..d8a7e3cc32e 100644
--- a/sys/arch/riscv64/riscv64/exception.S
+++ b/sys/arch/riscv64/riscv64/exception.S
@@ -83,6 +83,11 @@
 	sd	t0, (TF_SEPC)(sp)
 	csrr	t0, sstatus
 	sd	t0, (TF_SSTATUS)(sp)
+.if \el == 1
+	/* Disable user address access for supervisor mode exceptions. */
+	li	t0, SSTATUS_SUM
+	csrc	sstatus, t0
+.endif
 	csrr	t0, stval
 	sd	t0, (TF_STVAL)(sp)
 	csrr	t0, scause
-- 
2.20.1