[PATCH v4 08/11] ARM: install HYP vectors at PBL and Barebox entry

[Lucas Stach <l.stach@pengutronix.de>]

If the CPU was already in HYP mode when entering the PBL, install a
simple trap handler to allow to get back from SVC to HYP before
switching to HYP mode.

As the vectors are part of the currently running binary, we need to
do the same setup when starting the real Barebox binary, as the PBL
setup vectors might get overwritten. To do this we trap into HYP mode
just before jumping to Barebox and then re-do the vector setup and
SVC switch as the first thing in Barebox proper.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Tested-by: Roland Hieber <r.hieber@pengutronix.de>
---
 arch/arm/cpu/lowlevel.S   | 3 +++
 arch/arm/cpu/start-pbl.c  | 4 ++++
 arch/arm/cpu/start.c      | 5 +++++
 arch/arm/cpu/uncompress.c | 4 ++++
 4 files changed, 16 insertions(+)

diff --git a/arch/arm/cpu/lowlevel.S b/arch/arm/cpu/lowlevel.S
index 43665981e48b..13dfe496ad17 100644
--- a/arch/arm/cpu/lowlevel.S
+++ b/arch/arm/cpu/lowlevel.S
@@ -8,6 +8,9 @@ ENTRY(arm_cpu_lowlevel_init)
 	/* save lr, since it may be banked away with a processor mode change */
 	mov	r2, lr
 
+	/* careful: the hyp install corrupts r0 and r1 */
+	bl	__hyp_install
+
 	/* set the cpu to SVC32 mode, mask irq and fiq */
 	mrs	r12, cpsr
 	eor	r12, r12, #HYP_MODE
diff --git a/arch/arm/cpu/start-pbl.c b/arch/arm/cpu/start-pbl.c
index 16159d7f9d51..48a808645671 100644
--- a/arch/arm/cpu/start-pbl.c
+++ b/arch/arm/cpu/start-pbl.c
@@ -26,6 +26,7 @@
 #include <asm/barebox-arm-head.h>
 #include <asm-generic/memory_layout.h>
 #include <asm/sections.h>
+#include <asm/secure.h>
 #include <asm/cache.h>
 #include <asm/mmu.h>
 #include <asm/unaligned.h>
@@ -98,5 +99,8 @@ __noreturn void barebox_single_pbl_start(unsigned long membase,
 	else
 		barebox = (void *)barebox_base;
 
+	if (IS_ENABLED(CONFIG_CPU_V7) && __boot_cpu_mode == HYP_MODE)
+		armv7_switch_to_hyp();
+
 	barebox(membase, memsize, boarddata);
 }
diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
index 64bd942ad764..a79d64eaa6e6 100644
--- a/arch/arm/cpu/start.c
+++ b/arch/arm/cpu/start.c
@@ -24,6 +24,7 @@
 #include <asm/barebox-arm-head.h>
 #include <asm-generic/memory_layout.h>
 #include <asm/sections.h>
+#include <asm/secure.h>
 #include <asm/unaligned.h>
 #include <asm/cache.h>
 #include <asm/mmu.h>
@@ -147,6 +148,10 @@ __noreturn void barebox_non_pbl_start(unsigned long membase,
 	unsigned long barebox_base = arm_mem_barebox_image(membase,
 							   endmem,
 							   barebox_size);
+
+	if (IS_ENABLED(CONFIG_CPU_V7))
+		armv7_hyp_install();
+
 	if (IS_ENABLED(CONFIG_RELOCATABLE))
 		relocate_to_adr(barebox_base);
 
diff --git a/arch/arm/cpu/uncompress.c b/arch/arm/cpu/uncompress.c
index 43b49b42120b..048bca0c9599 100644
--- a/arch/arm/cpu/uncompress.c
+++ b/arch/arm/cpu/uncompress.c
@@ -27,6 +27,7 @@
 #include <asm/barebox-arm-head.h>
 #include <asm-generic/memory_layout.h>
 #include <asm/sections.h>
+#include <asm/secure.h>
 #include <asm/cache.h>
 #include <asm/mmu.h>
 #include <asm/unaligned.h>
@@ -105,5 +106,8 @@ void __noreturn barebox_multi_pbl_start(unsigned long membase,
 
 	pr_debug("jumping to uncompressed image at 0x%p\n", barebox);
 
+	if (IS_ENABLED(CONFIG_CPU_V7) && __boot_cpu_mode == HYP_MODE)
+		armv7_switch_to_hyp();
+
 	barebox(membase, memsize, boarddata);
 }
-- 
2.19.1


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