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ARM: add secure monitor handler to switch to non-secure state

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A prerequisite for using virtualization is to be in HYP mode, which
requires the CPU to be in non-secure state first.
Add a new file in arch/arm/cpu/armv7 to hold a monitor handler routine
which switches the CPU to non-secure state by setting the NS and
associated bits.
According to the ARM architecture reference manual this should not be
done in SVC mode, so we have to setup a SMC handler for this.
We create a new vector table to avoid interference with other boards.
The MVBAR register will be programmed later just before the smc call.

Signed-off-by: Andre Przywara <andre.przywara@linaro.org>
This commit is contained in:
Andre Przywara 2013-09-19 18:06:40 +02:00 committed by Albert ARIBAUD
parent d75ba503a9
commit 45b940d6f9
2 changed files with 57 additions and 0 deletions
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4
arch/arm/cpu/armv7/Makefile
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@ -20,6 +20,10 @@ ifneq ($(CONFIG_AM43XX)$(CONFIG_AM33XX)$(CONFIG_OMAP44XX)$(CONFIG_OMAP54XX)$(CON
SOBJS += lowlevel_init.o
endif
ifneq ($(CONFIG_ARMV7_NONSEC),)
SOBJS += nonsec_virt.o
endif
SRCS := $(START:.o=.S) $(COBJS:.o=.c)
OBJS := $(addprefix $(obj),$(COBJS) $(SOBJS))
START := $(addprefix $(obj),$(START))

53
arch/arm/cpu/armv7/nonsec_virt.S Normal file
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@ -0,0 +1,53 @@
/*
* code for switching cores into non-secure state
*
* Copyright (c) 2013 Andre Przywara <andre.przywara@linaro.org>
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <config.h>
/* the vector table for secure state */
_monitor_vectors:
.word 0 /* reset */
.word 0 /* undef */
adr pc, _secure_monitor
.word 0
.word 0
.word 0
.word 0
.word 0
/*
* secure monitor handler
* U-boot calls this "software interrupt" in start.S
* This is executed on a "smc" instruction, we use a "smc #0" to switch
* to non-secure state.
* We use only r0 and r1 here, due to constraints in the caller.
*/
.align 5
_secure_monitor:
mrc p15, 0, r1, c1, c1, 0 @ read SCR
bic r1, r1, #0x4e @ clear IRQ, FIQ, EA, nET bits
orr r1, r1, #0x31 @ enable NS, AW, FW bits
mcr p15, 0, r1, c1, c1, 0 @ write SCR (with NS bit set)
movs pc, lr @ return to non-secure SVC