+ .extern main
+
.section .startup
+ .code 32
+
+ .global startup
+startup:
+ cpsid if
+
+ @ stop all but one of the cores
+ mrc p15, 0, r0, c0, c0, 5
+ ands r0, r0, #0xff
+ bne exit
+
+ @ detect if we're running in hyp mode, and drop to svc
+ mrs r0, cpsr
+ and r1, r0, #0x1f
+ cmp r1, #0x1a
+ bne hypend
+
+ bic r0, #0x1f
+ orr r0, #0x13
+ @msr spsr_cxsf, r0
+ add r0, pc, #4
+ msr elr_hyp, r0
+ @eret
+ mov pc, r0
+hypend:
+
+ @ setup initial stacks, allow 4k stack for IRQs
+ @mov r0, #0x12 @ switch to IRQ mode
+ @msr cpsr, r0
+ @ldr sp, =_stacktop
+ @mov r0, #0x13 @ switch to supervisor mode
+ @msr cpsr, r0
+ ldr sp, =_stacktop - 4096
+
@ clear bss
ldr r0, =_bss_start
ldr r1, =_bss_size
+ cmp r1, #0
+ beq 1f @ 0-sized bss, skip clear
mov r2, #0
0: str r2, [r0], #4
subs r1, #4
bne 0b
+1:
+ blx main
+
+ .global exit
+exit: wfe
+ b exit
+
+@ vi:set filetype=armasm: