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start.asm
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start.asm
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MBALIGN equ 1 << 0
MEMINFO equ 1 << 1
FLAGS equ MBALIGN | MEMINFO
MAGIC equ 0x1BADB002
CHECKSUM equ -(MAGIC + FLAGS)
section .multiboot
align 4
dd MAGIC
dd FLAGS
dd CHECKSUM
section .bss
align 16
stack_bottom:
resb 16384 ; 16 KiB
stack_top:
section .text
global _start:function (_start.end - _start)
_start:
cli
mov esp, stack_top
push 0
popf
push ebx
push eax
extern kmain
call kmain
cli
.hang: hlt
jmp .hang
.end:
; This will set up our new segment registers. We need to do
; something special in order to set CS. We do what is called a
; far jump. A jump that includes a segment as well as an offset.
; This is declared in C as 'extern void gdt_flush();'
global gdt_flush
extern gp
gdt_flush:
lgdt [gp]
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
jmp 0x08:flush2
flush2:
ret
; Loads the IDT defined in 'idtp' into the processor.
; This is declared in C as 'extern void idt_load();'
global idt_load
extern idtp
idt_load:
lidt [idtp]
ret
; In just a few pages in this tutorial, we will add our Interrupt
; Service Routines (ISRs) right here!
global isr0
global isr1
global isr2
global isr3
global isr4
global isr5
global isr6
global isr7
global isr8
global isr9
global isr10
global isr11
global isr12
global isr13
global isr14
global isr15
global isr16
global isr17
global isr18
global isr19
global isr20
global isr21
global isr22
global isr23
global isr24
global isr25
global isr26
global isr27
global isr28
global isr29
global isr30
global isr31
; 0: Divide By Zero Exception
isr0:
cli
push byte 0
push byte 0
jmp isr_common_stub
; 1: Debug Exception
isr1:
cli
push byte 0
push byte 1
jmp isr_common_stub
; 2: Non Maskable Interrupt Exception
isr2:
cli
push byte 0
push byte 2
jmp isr_common_stub
; 3: Int 3 Exception
isr3:
cli
push byte 0
push byte 3
jmp isr_common_stub
; 4: INTO Exception
isr4:
cli
push byte 0
push byte 4
jmp isr_common_stub
; 5: Out of Bounds Exception
isr5:
cli
push byte 0
push byte 5
jmp isr_common_stub
; 6: Invalid Opcode Exception
isr6:
cli
push byte 0
push byte 6
jmp isr_common_stub
; 7: Coprocessor Not Available Exception
isr7:
cli
push byte 0
push byte 7
jmp isr_common_stub
; 8: Double Fault Exception (With Error Code!)
isr8:
cli
push byte 8
jmp isr_common_stub
; 9: Coprocessor Segment Overrun Exception
isr9:
cli
push byte 0
push byte 9
jmp isr_common_stub
; 10: Bad TSS Exception (With Error Code!)
isr10:
cli
push byte 10
jmp isr_common_stub
; 11: Segment Not Present Exception (With Error Code!)
isr11:
cli
push byte 11
jmp isr_common_stub
; 12: Stack Fault Exception (With Error Code!)
isr12:
cli
push byte 12
jmp isr_common_stub
; 13: General Protection Fault Exception (With Error Code!)
isr13:
cli
push byte 13
jmp isr_common_stub
; 14: Page Fault Exception (With Error Code!)
isr14:
cli
push byte 14
jmp isr_common_stub
; 15: Reserved Exception
isr15:
cli
push byte 0
push byte 15
jmp isr_common_stub
; 16: Floating Point Exception
isr16:
cli
push byte 0
push byte 16
jmp isr_common_stub
; 17: Alignment Check Exception
isr17:
cli
push byte 0
push byte 17
jmp isr_common_stub
; 18: Machine Check Exception
isr18:
cli
push byte 0
push byte 18
jmp isr_common_stub
; 19: Reserved
isr19:
cli
push byte 0
push byte 19
jmp isr_common_stub
; 20: Reserved
isr20:
cli
push byte 0
push byte 20
jmp isr_common_stub
; 21: Reserved
isr21:
cli
push byte 0
push byte 21
jmp isr_common_stub
; 22: Reserved
isr22:
cli
push byte 0
push byte 22
jmp isr_common_stub
; 23: Reserved
isr23:
cli
push byte 0
push byte 23
jmp isr_common_stub
; 24: Reserved
isr24:
cli
push byte 0
push byte 24
jmp isr_common_stub
; 25: Reserved
isr25:
cli
push byte 0
push byte 25
jmp isr_common_stub
; 26: Reserved
isr26:
cli
push byte 0
push byte 26
jmp isr_common_stub
; 27: Reserved
isr27:
cli
push byte 0
push byte 27
jmp isr_common_stub
; 28: Reserved
isr28:
cli
push byte 0
push byte 28
jmp isr_common_stub
; 29: Reserved
isr29:
cli
push byte 0
push byte 29
jmp isr_common_stub
; 30: Reserved
isr30:
cli
push byte 0
push byte 30
jmp isr_common_stub
; 31: Reserved
isr31:
cli
push byte 0
push byte 31
jmp isr_common_stub
; We call a C function in here. We need to let the assembler know
; that 'fault_handler' exists in another file
extern fault_handler
; This is our common ISR stub. It saves the processor state, sets
; up for kernel mode segments, calls the C-level fault handler,
; and finally restores the stack frame.
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
mov eax, fault_handler
call eax
pop eax
pop gs
pop fs
pop es
pop ds
popa
add esp, 8
iret
global irq0
global irq1
global irq2
global irq3
global irq4
global irq5
global irq6
global irq7
global irq8
global irq9
global irq10
global irq11
global irq12
global irq13
global irq14
global irq15
; 32: IRQ0
irq0:
cli
push byte 0
push byte 32
jmp irq_common_stub
; 33: IRQ1
irq1:
cli
push byte 0
push byte 33
jmp irq_common_stub
; 34: IRQ2
irq2:
cli
push byte 0
push byte 34
jmp irq_common_stub
; 35: IRQ3
irq3:
cli
push byte 0
push byte 35
jmp irq_common_stub
; 36: IRQ4
irq4:
cli
push byte 0
push byte 36
jmp irq_common_stub
; 37: IRQ5
irq5:
cli
push byte 0
push byte 37
jmp irq_common_stub
; 38: IRQ6
irq6:
cli
push byte 0
push byte 38
jmp irq_common_stub
; 39: IRQ7
irq7:
cli
push byte 0
push byte 39
jmp irq_common_stub
; 40: IRQ8
irq8:
cli
push byte 0
push byte 40
jmp irq_common_stub
; 41: IRQ9
irq9:
cli
push byte 0
push byte 41
jmp irq_common_stub
; 42: IRQ10
irq10:
cli
push byte 0
push byte 42
jmp irq_common_stub
; 43: IRQ11
irq11:
cli
push byte 0
push byte 43
jmp irq_common_stub
; 44: IRQ12
irq12:
cli
push byte 0
push byte 44
jmp irq_common_stub
; 45: IRQ13
irq13:
cli
push byte 0
push byte 45
jmp irq_common_stub
; 46: IRQ14
irq14:
cli
push byte 0
push byte 46
jmp irq_common_stub
; 47: IRQ15
irq15:
cli
push byte 0
push byte 47
jmp irq_common_stub
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
mov eax, irq_handler
call eax
pop eax
pop gs
pop fs
pop es
pop ds
popa
add esp, 8
iret