From b51092c7ec2db8b52c50bafce4fd51e15e090560 Mon Sep 17 00:00:00 2001
From: Ruslan Bukin
Date: Fri, 27 Jul 2018 16:13:06 +0000
Subject: [PATCH] Use SPP (Supervisor Previous Privilege) bit in the sstatus
register to determine if trap is from userspace.
Otherwise if we jump to kernel address from userspace, then
TRAPF_USERMODE failed to detect usermode and then do_ast
triggers a panic "ast in kernel mode".
Reviewed by: markj@
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D16469
---
sys/riscv/include/cpu.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sys/riscv/include/cpu.h b/sys/riscv/include/cpu.h
index 9b488ac9ecb..92c5c67ef59 100644
--- a/sys/riscv/include/cpu.h
+++ b/sys/riscv/include/cpu.h
@@ -1,5 +1,5 @@
/*-
- * Copyright (c) 2015-2016 Ruslan Bukin
+ * Copyright (c) 2015-2018 Ruslan Bukin
* All rights reserved.
*
* Portions of this software were developed by SRI International and the
@@ -41,7 +41,7 @@
#include
#define TRAPF_PC(tfp) ((tfp)->tf_ra)
-#define TRAPF_USERMODE(tfp) (((tfp)->tf_sepc & (1ul << 63)) == 0)
+#define TRAPF_USERMODE(tfp) (((tfp)->tf_sstatus & SSTATUS_SPP) == 0)
#define cpu_getstack(td) ((td)->td_frame->tf_sp)
#define cpu_setstack(td, sp) ((td)->td_frame->tf_sp = (sp))