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authorAndre Przywara <andre.przywara@linaro.org>2013-09-19 18:06:40 +0200
committerAlbert ARIBAUD <albert.u.boot@aribaud.net>2013-10-03 21:27:11 +0200
commit45b940d6f9a9d4989452ea67480e299bfa51ee19 (patch)
tree636e0c5d2d8b7bfce8b7927e56044e0b95862806
parentd75ba503a972df09784f1a332ba356ef8b42a0a6 (diff)
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ARM: add secure monitor handler to switch to non-secure state
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>
-rw-r--r--arch/arm/cpu/armv7/Makefile4
-rw-r--r--arch/arm/cpu/armv7/nonsec_virt.S53
2 files changed, 57 insertions, 0 deletions
diff --git a/arch/arm/cpu/armv7/Makefile b/arch/arm/cpu/armv7/Makefile
index b723e22..3466c7a 100644
--- a/arch/arm/cpu/armv7/Makefile
+++ b/arch/arm/cpu/armv7/Makefile
@@ -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))
diff --git a/arch/arm/cpu/armv7/nonsec_virt.S b/arch/arm/cpu/armv7/nonsec_virt.S
new file mode 100644
index 0000000..d11eb2d
--- /dev/null
+++ b/arch/arm/cpu/armv7/nonsec_virt.S
@@ -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