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Use SPP (Supervisor Previous Privilege) bit in the sstatus

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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
This commit is contained in:
br 2018-07-27 16:13:06 +00:00
parent 21c018b44b
commit 2bf756aae9
1 changed files with 2 additions and 2 deletions
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4
sys/riscv/include/cpu.h
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@ -1,5 +1,5 @@
/*-
* Copyright (c) 2015-2016 Ruslan Bukin <br@bsdpad.com>
* Copyright (c) 2015-2018 Ruslan Bukin <br@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))