toaruos/kernel/start.s
2011-02-27 21:19:54 -06:00

203 lines
2.9 KiB
ArmAsm

; ToAruOS Start Up / Entry Point
; vim:syntax=nasm
;
; Copyright 2011 ToAruOS Kernel Development Group
; See main.c for licensing terms (NCSA)
;
[BITS 32]
ALIGN 4
; Kernel Multiboot Headers
mboot:
MULTIBOOT_PAGE_ALIGN equ 1<<0
MULTIBOOT_MEMORY_INFO equ 1<<1
MULTIBOOT_HEADER_MAGIC equ 0x1BADB002
MULTIBOOT_HEADER_FLAGS equ MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO
MULTIBOOT_CHECKSUM equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
EXTERN code, bss, end
; GRUB Multiboot header, boot signature
dd MULTIBOOT_HEADER_MAGIC
dd MULTIBOOT_HEADER_FLAGS
dd MULTIBOOT_CHECKSUM
; Main entrypoint
global start
start:
; Set up stack pointer.
mov esp, 0x7FFFF
; Push the incoming mulitboot headers
push eax ; Header magic
push ebx ; Header pointer
; Disable interrupts
cli
; Call the C entry
extern main
call main
jmp $
; Global Descriptor Table
global gdt_flush
extern gp
gdt_flush:
; Load the GDT
lgdt [gp]
; Flush the values to 0x10
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
jmp 0x08:flush2
flush2:
ret
; Interrupt Descriptor Table
global idt_load
extern idtp
idt_load:
lidt [idtp]
ret
; Interrupt Service Routines
%macro ISR_NOERR 1
global _isr%1
_isr%1:
cli
push byte 0
push byte %1
jmp isr_common_stub
%endmacro
%macro ISR_ERR 1
global _isr%1
_isr%1:
cli
push byte %1
jmp isr_common_stub
%endmacro
%macro IRQ_ENTRY 2
global _irq%1
_irq%1:
cli
push byte 0
push byte %2
jmp irq_common_stub
%endmacro
; Standard X86 interrupt service routines
ISR_NOERR 0
ISR_NOERR 1
ISR_NOERR 2
ISR_NOERR 3
ISR_NOERR 4
ISR_NOERR 5
ISR_NOERR 6
ISR_NOERR 7
ISR_ERR 8
ISR_NOERR 9
ISR_ERR 10
ISR_ERR 11
ISR_ERR 12
ISR_ERR 13
ISR_ERR 14
ISR_NOERR 15
ISR_NOERR 16
ISR_NOERR 17
ISR_NOERR 18
ISR_NOERR 19
ISR_NOERR 20
ISR_NOERR 21
ISR_NOERR 22
ISR_NOERR 23
ISR_NOERR 24
ISR_NOERR 25
ISR_NOERR 26
ISR_NOERR 27
ISR_NOERR 28
ISR_NOERR 29
ISR_NOERR 30
ISR_NOERR 31
; Interrupt Requests
IRQ_ENTRY 0, 32
IRQ_ENTRY 1, 33
IRQ_ENTRY 2, 34
IRQ_ENTRY 3, 35
IRQ_ENTRY 4, 36
IRQ_ENTRY 5, 37
IRQ_ENTRY 6, 38
IRQ_ENTRY 7, 39
IRQ_ENTRY 8, 40
IRQ_ENTRY 9, 41
IRQ_ENTRY 10, 42
IRQ_ENTRY 11, 43
IRQ_ENTRY 12, 44
IRQ_ENTRY 13, 45
IRQ_ENTRY 14, 46
IRQ_ENTRY 15, 47
; Interrupt handlers
extern fault_handler
isr_common_stub:
pusha
push ds
push es
push fs
push gs
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov eax, esp
push eax
; Call the C kernel fault handler
mov eax, fault_handler
call eax
pop eax
pop gs
pop fs
pop es
pop ds
popa
add esp, 8
iret
extern irq_handler
irq_common_stub:
pusha
push ds
push es
push fs
push gs
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov eax, esp
push eax
; Call the C kernel hardware interrupt handler
mov eax, irq_handler
call eax
pop eax
pop gs
pop fs
pop es
pop ds
popa
add esp, 8
iret
; BSS Section
SECTION .bss
resb 8192 ; 8KB of memory reserved