?? kernel.asm
字號(hào):
; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; kernel.asm
; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
; Forrest Yu, 2005
; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%include "sconst.inc"
; 導(dǎo)入函數(shù)
extern cstart
extern tinix_main
extern exception_handler
extern spurious_irq
extern clock_handler
extern disp_str
extern delay
; 導(dǎo)入全局變量
extern gdt_ptr
extern idt_ptr
extern p_proc_ready
extern tss
extern disp_pos
extern k_reenter
extern irq_table
bits 32
[SECTION .data]
clock_int_msg db "^", 0
[SECTION .bss]
StackSpace resb 2 * 1024
StackTop: ; 棧頂
[section .text] ; 代碼在此
global _start ; 導(dǎo)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:
; 此時(shí)內(nèi)存看上去是這樣的（更詳細(xì)的內(nèi)存情況在 LOADER.ASM 中有說(shuō)明）：
; ┃ ┃
; ┃ ... ┃
; ┣━━━━━━━━━━━━━━━━━━┫
; ┃■■■■■■Page Tables■■■■■■┃
; ┃■■■■■(大小由LOADER決定)■■■■┃ 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 以及相應(yīng)的描述符是這樣的：
;
; 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 代碼的時(shí)候一定要保證 ds, es, ss 這幾個(gè)段寄存器的值是一樣的
; 因?yàn)榫幾g器有可能編譯出使用它們的代碼, 而編譯器默認(rèn)它們是一樣的. 比如串拷貝操作會(huì)用到 ds 和 es.
;
;
; 把 esp 從 LOADER 挪到 KERNEL
mov esp, StackTop ; 堆棧在 bss 段中
mov dword [disp_pos], 0
sgdt [gdt_ptr] ; cstart() 中將會(huì)用到 gdt_ptr
call cstart ; 在此函數(shù)中改變了gdt_ptr，讓它指向新的GDT
lgdt [gdt_ptr] ; 使用新的GDT
lidt [idt_ptr]
jmp SELECTOR_KERNEL_CS:csinit
csinit: ; “這個(gè)跳轉(zhuǎn)指令強(qiáng)制使用剛剛初始化的結(jié)構(gòu)”——<<OS:D&I 2nd>> P90.
;jmp 0x40:0
;ud2
;sti
xor eax, eax
mov ax, SELECTOR_TSS
ltr ax
jmp tinix_main
;hlt
; 中斷和異常 -- 硬件中斷
; ---------------------------------
%macro hwint_master 1
call save
in al, INT_M_CTLMASK ; ┓
or al, (1 << %1) ; ┣ 屏蔽當(dāng)前中斷
out INT_M_CTLMASK, al ; ┛
mov al, EOI ; ┓置EOI位
out INT_M_CTL, al ; ┛
sti ; CPU在響應(yīng)中斷的過(guò)程中會(huì)自動(dòng)關(guān)中斷，這句之后就允許響應(yīng)新的中斷
push %1 ; ┓
call [irq_table + 4 * %1] ; ┣ 中斷處理程序
pop ecx ; ┛
cli
in al, INT_M_CTLMASK ; ┓
and al, ~(1 << %1) ; ┣ 恢復(fù)接受當(dāng)前中斷
out INT_M_CTLMASK, al ; ┛
ret
%endmacro
ALIGN 16
hwint00: ; Interrupt routine for irq 0 (the clock).
hwint_master 0
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
; 中斷和異常 -- 異常
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 ; 讓棧頂指向 EIP，堆棧中從頂向下依次是：EIP、CS、EFLAGS
hlt
; ====================================================================================
; save
; ====================================================================================
save:
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
mov eax, esp ; eax = 進(jìn)程表起始地址
inc dword [k_reenter] ; k_reenter++;
cmp dword [k_reenter], 0 ; if(k_reenter ==0)
jne .1 ; {
mov esp, StackTop ; mov esp, StackTop <-- 切換到內(nèi)核棧
push restart ; push restart
jmp [eax + RETADR - P_STACKBASE] ; return;
.1: ; } else { 已經(jīng)在內(nèi)核棧，不需要再切換
push restart_reenter ; push restart_reenter
jmp [eax + RETADR - P_STACKBASE] ; return;
; }
; ====================================================================================
; restart
; ====================================================================================
restart:
mov esp, [p_proc_ready]
lldt [esp + P_LDT_SEL]
lea eax, [esp + P_STACKTOP]
mov dword [tss + TSS3_S_SP0], eax
restart_reenter:
dec dword [k_reenter]
pop gs
pop fs
pop es
pop ds
popad
add esp, 4
iretd
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