[boot-wrapper PATCH 2/5] aarch32: simplify _switch_monitor

[Mark Rutland]

If we're lucky enough to have been booted into secure PL1, we can switch
to monitor mode with an exception return rather than an SMC call, which
avoids the need for boot-time vectors.

Note that while all Secure PL1 register state is accessible in Secure
SVC mode, we must switch to Monitor mode before we set SCR.NS=1.

Signed-off-by: Mark Rutland <mark.rutland at arm.com>
---
 arch/aarch32/boot.S | 19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/arch/aarch32/boot.S b/arch/aarch32/boot.S
index 82927de..e397cb0 100644
--- a/arch/aarch32/boot.S
+++ b/arch/aarch32/boot.S
@@ -37,9 +37,10 @@ ASM_FUNC(_start)
 	b	start_no_el3
 
 _switch_monitor:
-	ldr	r0, =boot_vectors
-	bl	setup_vector
-	smc	#0
+	adr	lr, _monitor
+	ldr	r0, =(PSR_A | PSR_I | PSR_F | PSR_MON)
+	msr	spsr, r0
+	movs	pc, lr
 
 _monitor:
 	/* Move the stack to Monitor mode*/
@@ -102,18 +103,6 @@ ASM_FUNC(jump_kernel)
 	msr	spsr_cxf, r4
 	movs	pc, lr
 
-	.section .vectors
-	.align 6
-boot_vectors:
-	b	.
-	b	.
-	b	_monitor
-	b	.
-	b	.
-	b	.
-	b	.
-	b	.
-
 	.section .data
 	.align 2
 flag_no_el3:
-- 
2.11.0