svn commit: r336766 - head/sys/riscv/include

[Ruslan Bukin]

Author: br
Date: Fri Jul 27 16:13:06 2018
New Revision: 336766
URL: https://svnweb.freebsd.org/changeset/base/336766

Log:
  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

Modified:
  head/sys/riscv/include/cpu.h

Modified: head/sys/riscv/include/cpu.h
==============================================================================
--- head/sys/riscv/include/cpu.h	Fri Jul 27 15:49:12 2018	(r336765)
+++ head/sys/riscv/include/cpu.h	Fri Jul 27 16:13:06 2018	(r336766)
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2015-2016 Ruslan Bukin <br at bsdpad.com>
+ * Copyright (c) 2015-2018 Ruslan Bukin <br at bsdpad.com>
  * All rights reserved.
  *
  * Portions of this software were developed by SRI International and the
@@ -41,7 +41,7 @@
 #include <machine/frame.h>
 
 #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))