os-k/kaleid/kernel/mm/gdt.asm

66 lines
2.4 KiB
NASM

;=----------------------------------------------------------------------------=;
; GNU GPL OS/K ;
; ;
; Desc: Interrupt Descriptor Table related functions ;
; ;
; ;
; Copyright © 2018-2019 The OS/K Team ;
; ;
; This file is part of OS/K. ;
; ;
; OS/K is free software: you can redistribute it and/or modify ;
; it under the terms of the GNU General Public License as published by ;
; the Free Software Foundation, either version 3 of the License, or ;
; (at your option) any later version. ;
; ;
; OS/K is distributed in the hope that it will be useful, ;
; but WITHOUT ANY WARRANTY; without even the implied warranty of ;
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;
; GNU General Public License for more details. ;
; ;
; You should have received a copy of the GNU General Public License ;
; along with OS/K. If not, see <https://www.gnu.org/licenses/>. ;
;=----------------------------------------------------------------------------=;
[BITS 64]
extern gdtPtr
global MmLoadGdt
global MmStoreGdt
;;
;; Loads the GDT
;;
MmLoadGdt:
;; Loading the gdt via the gdtPtr pointer
lgdt [rel gdtPtr]
;; Reloading the segment registers
mov ax, si ; data segment
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
mov cs, di ; code segment
;; We must far jump because we changed the GDT
lea rax, [rel .next]
push rax
ret
.next:
;ltr dx ; the TSS
ret
;;
;; Stores the GDT
;;
MmStoreGdt:
;; Loading the gdt via the gdtPtr pointer
sgdt [rel gdtPtr]
ret