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|
;
; traps.s provides entry points to the exception handlers
; as well as the system call interface.
;
global syscall_init
global traps_init
extern call_table
extern idt
extern panic
extern printf
extern register_isr
%macro SAVE 0
pusha
; save the data segment selectors
mov ax, ds
push ax
; switch to kernel data segments
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
; restore EAX (needed for syscalls)
mov eax, [esp+30]
%endmacro
%macro SAVE_ERR 0
pusha
; fetch the error code that was pushed
mov ebx, [esp+32]
; save the data segment selectors
mov ax, ds
push ax
; switch to kernel data segments
mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
%endmacro
%macro RESTORE 0
; restore the data segment selectors
pop ax
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
popa
iret
%endmacro
%macro RESTORE_ERR 0
; restore the data segment selectors
pop ax
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
popa
add esp, 4
iret
%endmacro
%macro RESTORE_SYS 0
; preserve our modified EAX (return value for syscalls)
mov [esp+30], eax
; restore the data segment selectors
pop ax
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
popa
iret
%endmacro
traps:
dd exc_div
dd exc_debug
dd exc_nmi
dd exc_brk
dd exc_ovf
dd exc_bounds
dd exc_invop
dd exc_nomath
dd exc_dbf
dd exc_coseg
dd exc_invtss
dd exc_segnotpres
dd exc_stackf
dd exc_gprot
dd exc_pagef
dd exc_reserved
dd exc_mathf
dd exc_alignchk
dd exc_machinechk
dd exc_simdfp
dd exc_virt
dd exc_reserved
dd exc_reserved
dd exc_reserved
dd exc_reserved
dd exc_reserved
dd exc_reserved
dd exc_reserved
dd exc_reserved
dd exc_reserved
dd exc_reserved
dd exc_reserved
traps_init:
push ebp
mov ebp, esp
mov ecx, 0
mov edx, idt
.loop:
mov eax, ecx
shl eax, 2
add eax, traps
mov eax, [eax]
mov [edx], ax
shr eax, 16
mov [edx+6], ax
mov word [edx+2], 0x08
mov byte [edx+4], 0x00
mov byte [edx+5], 0x8E
inc ecx
cmp ecx, 32
je .end
add edx, 8
jmp .loop
.end:
pop ebp
ret
exc_div:
SAVE
RESTORE
exc_debug:
SAVE
RESTORE
exc_nmi:
SAVE
RESTORE
exc_brk:
SAVE
RESTORE
exc_ovf:
SAVE
RESTORE
exc_bounds:
SAVE
RESTORE
exc_invop:
SAVE
RESTORE
exc_nomath:
SAVE
RESTORE
exc_dbf:
SAVE_ERR
RESTORE_ERR
exc_coseg:
SAVE
RESTORE
exc_invtss:
SAVE_ERR
RESTORE_ERR
exc_segnotpres:
SAVE_ERR
RESTORE_ERR
exc_stackf:
SAVE_ERR
RESTORE_ERR
exc_gprot:
SAVE_ERR
RESTORE_ERR
exc_pagef:
SAVE_ERR
push ebx
mov ebx, cr2
push ebx
push .fmt
call printf
add esp, 8
call panic
RESTORE_ERR
.fmt:
db "Page Fault (illegal memory access: 0x%08x:0x%02x)", 10, 0
exc_mathf:
SAVE
RESTORE
exc_alignchk:
SAVE
RESTORE
exc_machinechk:
SAVE
RESTORE
exc_simdfp:
SAVE
RESTORE
exc_virt:
SAVE
RESTORE
exc_reserved:
SAVE
RESTORE
syscall_handler:
SAVE
push edx
push ecx
push ebx
and eax, 0xFF
shl eax, 2
add eax, call_table
call [eax]
add esp, 12
RESTORE_SYS
syscall_init:
push ebp
mov ebp, esp
push syscall_handler
push dword 3
push dword 0x80
call register_isr
add esp, 12
pop ebp
ret
|
