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// To keep this in the first portion of the binary.
.section ".text.boot"
// Make _start global.
.globl _start
_start:
reset:
cpsid if
// disable core0,1,2.
mrc p15, #0, r1, c0, c0, #5
and r1, r1, #3
cmp r1, #1
beq core1run
cmp r1, #2
beq core2run
cmp r1, #3
bge core3run
// set vector address.
ldr r0, =vector
mcr p15, 0, r0, c12, c0, 0
// Setup sp in IRQ mode.
cps #0x12
mov sp,#0x4000
// Setup sp in FIQ mode.
cps #0x11
mov sp,#0x2000
// Setup sp in UNDEF mode.
cps #0x1B
mov sp,#0x1000
// Setup sp in ABORT mode.
cps #0x17
mov sp,#0x0800
// Setup sp in USR/SYS mode.
cps #0x1f
mov sp,#0x6000
// Setup sp in SVC mode.
cps #0x13
mov sp, #0x8000
// Clear out bss.
ldr r4, =__bss_start
ldr r9, =__bss_end
mov r5, #0
mov r6, #0
mov r7, #0
mov r8, #0
b 2f
1:
// store multiple at r4.
stmia r4!, {r5-r8}
// If we are still below bss_end, loop.
2:
cmp r4, r9
blo 1b
// Call kernel_main
ldr r3, =kernel_main
blx r3
irq:
push {r0,r1,r2,r3,r4,r5,r6,r7,r8,r9,r10,r11,r12,lr}
bl c_irq_handler
pop {r0,r1,r2,r3,r4,r5,r6,r7,r8,r9,r10,r11,r12,lr}
subs pc, lr, #4
// TODO: Each core needs to set up their stacks
core1run:
core2run:
core3run:
.globl io_halt
io_halt:
wfi
b io_halt
undefined:
stmfd sp!, {r0-r12,lr}
ldr r4, [lr, #-4]
mov r0, #0
mov r1, #17
ldr r2, =undefined_msg
bl draw_string
mov r0, #18
mov r1, #17
mov r2, r4
bl draw_hex32
mov r0, #27
mov r1, #17
ldr r2, =undefined_at
bl draw_string
// Output lr
mov r1, #0x1000
ldr r0, [r1, #-4]
sub r2, r0, #4
mov r0, #31
mov r1, #17
bl draw_hex32
// Skip instruction for now
// In future,
// ldmfd sp!, {r0-r12,lr} // Note the lack of ^ since subs will handle it
// subs pc, lr, #4
ldmfd sp!, {r0-r12,pc}^
svc:
cpsid f
stmfd sp!, {r0-r12,lr}
ldr r0, [lr, #-4]
bic r0, #0xFF000000
// SVC #0 returns to supervisor mode
// TODO: Make supervisor mode return to a specific location
// (rather than to a user location) such as the kernel loop
cmp r0, #3
bgt svc_exit
beq svc_000003
cmp r0, #2
beq svc_000002
cmp r0, #1
beq svc_000001
cmp r0, #1
beq svc_000000
svc_000000:
cps #0x13
b svc_exit
svc_000001:
b svc_exit
svc_000002:
ldmfd sp!, {r0-r12,lr}
b schedule
svc_000003:
ldr r3, =scheduler
ldr r2, [r3, #0]
ldr r1, [r2, #8] // sp_base
cmp r1, #-1
beq svc_exit
ldr r3, =stacks_table
mov r0, #0
strb r0, [r3, r1]
// Free the thread after freeing the stack
mov r0, r2
bl free
b svc_exit
svc_exit:
ldmfd sp!, {r0-r12,pc}^
prefetch:
stmfd sp!, {r0-r12,lr}
mov r4, lr
mov r0, #0
mov r1, #16
ldr r2, =prefetch_msg
bl draw_string
// Output return address
mov r0, #17
mov r1, #16
mov r2, r4
bl draw_hex32
ldmfd sp!, {r0-r12,lr}
subs pc, lr, #4
data:
stmfd sp!, {r0-r12,lr}
mov r4, lr
mov r0, #0
mov r1, #15
ldr r2, =data_msg
bl draw_string
// Output return address
mov r0, #13
mov r1, #15
mov r2, r4
sub r2, #8
bl draw_hex32
mov r0, #22
mov r1, #15
ldr r2, [r4, #-8]
bl draw_hex32
ldmfd sp!, {r0-r12,lr}
subs pc, lr, #4 // Should be 8 once I can actually handle the abort
fiq:
stmfd sp!, {r0-r12,lr}
bl c_fiq_handler
cmp r0, #1
bne 1f
ldmfd sp!, {r0-r12,lr}
sub lr, #4
push {r3}
ldr r3, =irqlr
str lr, [r3, #0]
pop {r3}
cps #0x13
b schedule
1:
ldmfd sp!, {r0-r12,lr}
subs pc, lr, #4
.align 5
vector:
ldr pc, reset_handler
ldr pc, undefined_handler
ldr pc, svc_handler
ldr pc, prefetch_handler
ldr pc, data_handler
ldr pc, unused_handler
ldr pc, irq_handler
ldr pc, fiq_handler
reset_handler: .word reset
undefined_handler: .word undefined
svc_handler: .word svc
prefetch_handler: .word prefetch
data_handler: .word data
unused_handler: .word io_halt
irq_handler: .word irq
fiq_handler: .word fiq
.section .data
undefined_msg: .asciz "Undefined Handler"
undefined_at: .asciz "@ 0x"
svc_msg: .asciz "SVC Handler #"
prefetch_msg: .asciz "Prefetch Handler"
data_msg: .asciz "Data Handler"
fiq_msg: .asciz "FIQ\n"
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