kernel.asm - Forrest Yu, 2005

/orange/chapter6/c/kernel/kernel.asm

https://github.com/lingod01/lingod · Assembly · 359 lines · 233 code · 64 blank · 62 comment · 0 complexity · 4f8d0847ca05414880e7803a03815971 MD5 · raw file

; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
;                               kernel.asm
; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
;                                                     Forrest Yu, 2005
; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++


%include "sconst.inc"

; 导入函数
extern	cstart
extern	kernel_main
extern	exception_handler
extern	spurious_irq
extern	disp_str
extern	delay

; 导入全局变量
extern	gdt_ptr
extern	idt_ptr
extern	p_proc_ready
extern	tss
extern	disp_pos
extern	k_reenter

bits 32

[SECTION .data]
clock_int_msg		db	"^", 0

[SECTION .bss]
StackSpace		resb	2 * 1024
StackTop:		; 栈顶

[section .text]	; 代码在此

global _start	; 导出 _start

global restart

global	divide_error
global	single_step_exception
global	nmi
global	breakpoint_exception
global	overflow
global	bounds_check
global	inval_opcode
global	copr_not_available
global	double_fault
global	copr_seg_overrun
global	inval_tss
global	segment_not_present
global	stack_exception
global	general_protection
global	page_fault
global	copr_error
global	hwint00
global	hwint01
global	hwint02
global	hwint03
global	hwint04
global	hwint05
global	hwint06
global	hwint07
global	hwint08
global	hwint09
global	hwint10
global	hwint11
global	hwint12
global	hwint13
global	hwint14
global	hwint15


_start:
	; 此时内存看上去是这样的（更详细的内存情况在 LOADER.ASM 中有说明）：
	;              ┃                                    ┃
	;              ┃                 ...                ┃
	;              ┣━━━━━━━━━━━━━━━━━━┫
	;              ┃■■■■■■Page  Tables■■■■■■┃
	;              ┃■■■■■(大小由LOADER决定)■■■■┃ PageTblBase
	;    00101000h ┣━━━━━━━━━━━━━━━━━━┫
	;              ┃■■■■Page Directory Table■■■■┃ PageDirBase = 1M
	;    00100000h ┣━━━━━━━━━━━━━━━━━━┫
	;              ┃□□□□ Hardware  Reserved □□□□┃ B8000h ← gs
	;       9FC00h ┣━━━━━━━━━━━━━━━━━━┫
	;              ┃■■■■■■■LOADER.BIN■■■■■■┃ somewhere in LOADER ← esp
	;       90000h ┣━━━━━━━━━━━━━━━━━━┫
	;              ┃■■■■■■■KERNEL.BIN■■■■■■┃
	;       80000h ┣━━━━━━━━━━━━━━━━━━┫
	;              ┃■■■■■■■■KERNEL■■■■■■■┃ 30400h ← KERNEL 入口 (KernelEntryPointPhyAddr)
	;       30000h ┣━━━━━━━━━━━━━━━━━━┫
	;              ┋                 ...                ┋
	;              ┋                                    ┋
	;           0h ┗━━━━━━━━━━━━━━━━━━┛ ← cs, ds, es, fs, ss
	;
	;
	; GDT 以及相应的描述符是这样的：
	;
	;		              Descriptors               Selectors
	;              ┏━━━━━━━━━━━━━━━━━━┓
	;              ┃         Dummy Descriptor           ┃
	;              ┣━━━━━━━━━━━━━━━━━━┫
	;              ┃         DESC_FLAT_C    (0～4G)     ┃   8h = cs
	;              ┣━━━━━━━━━━━━━━━━━━┫
	;              ┃         DESC_FLAT_RW   (0～4G)     ┃  10h = ds, es, fs, ss
	;              ┣━━━━━━━━━━━━━━━━━━┫
	;              ┃         DESC_VIDEO                 ┃  1Bh = gs
	;              ┗━━━━━━━━━━━━━━━━━━┛
	;
	; 注意! 在使用 C 代码的时候一定要保证 ds, es, ss 这几个段寄存器的值是一样的
	; 因为编译器有可能编译出使用它们的代码, 而编译器默认它们是一样的. 比如串拷贝操作会用到 ds 和 es.
	;
	;


	; 把 esp 从 LOADER 挪到 KERNEL
	mov	esp, StackTop	; 堆栈在 bss 段中

	mov	dword [disp_pos], 0

	sgdt	[gdt_ptr]	; cstart() 中将会用到 gdt_ptr
	call	cstart		; 在此函数中改变了gdt_ptr，让它指向新的GDT
	lgdt	[gdt_ptr]	; 使用新的GDT

	lidt	[idt_ptr]

	jmp	SELECTOR_KERNEL_CS:csinit
csinit:		; “这个跳转指令强制使用刚刚初始化的结构”——<<OS:D&I 2nd>> P90.

	;jmp 0x40:0
	;ud2


	xor	eax, eax
	mov	ax, SELECTOR_TSS
	ltr	ax

	;sti
	jmp	kernel_main

	;hlt


; 中断和异常 -- 硬件中断
; ---------------------------------
%macro	hwint_master	1
	push	%1
	call	spurious_irq
	add	esp, 4
	hlt
%endmacro


ALIGN	16
hwint00:		; Interrupt routine for irq 0 (the clock).
	sub	esp, 4
	pushad		; `.
	push	ds	;  |
	push	es	;  | 保存原寄存器值
	push	fs	;  |
	push	gs	; /
	mov	dx, ss
	mov	ds, dx
	mov	es, dx

	inc	byte [gs:0]		; 改变屏幕第 0 行, 第 0 列的字符

	mov	al, EOI			; `. reenable
	out	INT_M_CTL, al		; /  master 8259

	inc	dword [k_reenter]
	cmp	dword [k_reenter], 0
	jne	.re_enter
	
	mov	esp, StackTop		; 切到内核栈

	sti
	
	push	clock_int_msg
	call	disp_str
	add	esp, 4

;;; 	push	1
;;; 	call	delay
;;; 	add	esp, 4
	
	cli
	
	mov	esp, [p_proc_ready]	; 离开内核栈

	lea	eax, [esp + P_STACKTOP]
	mov	dword [tss + TSS3_S_SP0], eax

.re_enter:	; 如果(k_reenter != 0)，会跳转到这里
	dec	dword [k_reenter]
	pop	gs	; `.
	pop	fs	;  |
	pop	es	;  | 恢复原寄存器值
	pop	ds	;  |
	popad		; /
	add	esp, 4

	iretd

ALIGN	16
hwint01:		; Interrupt routine for irq 1 (keyboard)
	hwint_master	1

ALIGN	16
hwint02:		; Interrupt routine for irq 2 (cascade!)
	hwint_master	2

ALIGN	16
hwint03:		; Interrupt routine for irq 3 (second serial)
	hwint_master	3

ALIGN	16
hwint04:		; Interrupt routine for irq 4 (first serial)
	hwint_master	4

ALIGN	16
hwint05:		; Interrupt routine for irq 5 (XT winchester)
	hwint_master	5

ALIGN	16
hwint06:		; Interrupt routine for irq 6 (floppy)
	hwint_master	6

ALIGN	16
hwint07:		; Interrupt routine for irq 7 (printer)
	hwint_master	7

; ---------------------------------
%macro	hwint_slave	1
	push	%1
	call	spurious_irq
	add	esp, 4
	hlt
%endmacro
; ---------------------------------

ALIGN	16
hwint08:		; Interrupt routine for irq 8 (realtime clock).
	hwint_slave	8

ALIGN	16
hwint09:		; Interrupt routine for irq 9 (irq 2 redirected)
	hwint_slave	9

ALIGN	16
hwint10:		; Interrupt routine for irq 10
	hwint_slave	10

ALIGN	16
hwint11:		; Interrupt routine for irq 11
	hwint_slave	11

ALIGN	16
hwint12:		; Interrupt routine for irq 12
	hwint_slave	12

ALIGN	16
hwint13:		; Interrupt routine for irq 13 (FPU exception)
	hwint_slave	13

ALIGN	16
hwint14:		; Interrupt routine for irq 14 (AT winchester)
	hwint_slave	14

ALIGN	16
hwint15:		; Interrupt routine for irq 15
	hwint_slave	15



; 中断和异常 -- 异常
divide_error:
	push	0xFFFFFFFF	; no err code
	push	0		; vector_no	= 0
	jmp	exception
single_step_exception:
	push	0xFFFFFFFF	; no err code
	push	1		; vector_no	= 1
	jmp	exception
nmi:
	push	0xFFFFFFFF	; no err code
	push	2		; vector_no	= 2
	jmp	exception
breakpoint_exception:
	push	0xFFFFFFFF	; no err code
	push	3		; vector_no	= 3
	jmp	exception
overflow:
	push	0xFFFFFFFF	; no err code
	push	4		; vector_no	= 4
	jmp	exception
bounds_check:
	push	0xFFFFFFFF	; no err code
	push	5		; vector_no	= 5
	jmp	exception
inval_opcode:
	push	0xFFFFFFFF	; no err code
	push	6		; vector_no	= 6
	jmp	exception
copr_not_available:
	push	0xFFFFFFFF	; no err code
	push	7		; vector_no	= 7
	jmp	exception
double_fault:
	push	8		; vector_no	= 8
	jmp	exception
copr_seg_overrun:
	push	0xFFFFFFFF	; no err code
	push	9		; vector_no	= 9
	jmp	exception
inval_tss:
	push	10		; vector_no	= A
	jmp	exception
segment_not_present:
	push	11		; vector_no	= B
	jmp	exception
stack_exception:
	push	12		; vector_no	= C
	jmp	exception
general_protection:
	push	13		; vector_no	= D
	jmp	exception
page_fault:
	push	14		; vector_no	= E
	jmp	exception
copr_error:
	push	0xFFFFFFFF	; no err code
	push	16		; vector_no	= 10h
	jmp	exception

exception:
	call	exception_handler
	add	esp, 4*2	; 让栈顶指向 EIP，堆栈中从顶向下依次是：EIP、CS、EFLAGS
	hlt


; ====================================================================================
;                                   restart
; ====================================================================================
restart:
	mov	esp, [p_proc_ready]
	lldt	[esp + P_LDT_SEL] 
	lea	eax, [esp + P_STACKTOP]
	mov	dword [tss + TSS3_S_SP0], eax
	pop	gs
	pop	fs
	pop	es
	pop	ds
	popad
	add	esp, 4
	iretd