mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
synced 2024-11-30 12:43:41 +01:00
134 lines
3.6 KiB
NASM
134 lines
3.6 KiB
NASM
;------------------------------------------------------------------------------
|
|
; @file
|
|
; Transition from 16 bit real mode into 32 bit flat protected mode
|
|
;
|
|
; Copyright (c) 2008 - 2010, Intel Corporation. All rights reserved.<BR>
|
|
; This program and the accompanying materials
|
|
; are licensed and made available under the terms and conditions of the BSD License
|
|
; which accompanies this distribution. The full text of the license may be found at
|
|
; http://opensource.org/licenses/bsd-license.php
|
|
;
|
|
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
|
|
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
|
|
;
|
|
;------------------------------------------------------------------------------
|
|
|
|
%define SEC_DEFAULT_CR0 0x40000023
|
|
%define SEC_DEFAULT_CR4 0x640
|
|
|
|
BITS 16
|
|
|
|
;
|
|
; Modified: EAX, EBX
|
|
;
|
|
TransitionFromReal16To32BitFlat:
|
|
|
|
debugShowPostCode POSTCODE_16BIT_MODE
|
|
|
|
cli
|
|
|
|
mov bx, 0xf000
|
|
mov ds, bx
|
|
|
|
mov bx, ADDR16_OF(gdtr)
|
|
|
|
o32 lgdt [cs:bx]
|
|
|
|
mov eax, SEC_DEFAULT_CR0
|
|
mov cr0, eax
|
|
|
|
jmp LINEAR_CODE_SEL:dword ADDR_OF(jumpTo32BitAndLandHere)
|
|
BITS 32
|
|
jumpTo32BitAndLandHere:
|
|
|
|
mov eax, SEC_DEFAULT_CR4
|
|
mov cr4, eax
|
|
|
|
debugShowPostCode POSTCODE_32BIT_MODE
|
|
|
|
mov ax, LINEAR_SEL
|
|
mov ds, ax
|
|
mov es, ax
|
|
mov fs, ax
|
|
mov gs, ax
|
|
mov ss, ax
|
|
|
|
OneTimeCallRet TransitionFromReal16To32BitFlat
|
|
|
|
ALIGN 2
|
|
|
|
gdtr:
|
|
dw GDT_END - GDT_BASE - 1 ; GDT limit
|
|
dd ADDR_OF(GDT_BASE)
|
|
|
|
ALIGN 16
|
|
|
|
;
|
|
; Macros for GDT entries
|
|
;
|
|
|
|
%define PRESENT_FLAG(p) (p << 7)
|
|
%define DPL(dpl) (dpl << 5)
|
|
%define SYSTEM_FLAG(s) (s << 4)
|
|
%define DESC_TYPE(t) (t)
|
|
|
|
; Type: data, expand-up, writable, accessed
|
|
%define DATA32_TYPE 3
|
|
|
|
; Type: execute, readable, expand-up, accessed
|
|
%define CODE32_TYPE 0xb
|
|
|
|
; Type: execute, readable, expand-up, accessed
|
|
%define CODE64_TYPE 0xb
|
|
|
|
%define GRANULARITY_FLAG(g) (g << 7)
|
|
%define DEFAULT_SIZE32(d) (d << 6)
|
|
%define CODE64_FLAG(l) (l << 5)
|
|
%define UPPER_LIMIT(l) (l)
|
|
|
|
;
|
|
; The Global Descriptor Table (GDT)
|
|
;
|
|
|
|
GDT_BASE:
|
|
; null descriptor
|
|
NULL_SEL equ $-GDT_BASE
|
|
DW 0 ; limit 15:0
|
|
DW 0 ; base 15:0
|
|
DB 0 ; base 23:16
|
|
DB 0 ; sys flag, dpl, type
|
|
DB 0 ; limit 19:16, flags
|
|
DB 0 ; base 31:24
|
|
|
|
; linear data segment descriptor
|
|
LINEAR_SEL equ $-GDT_BASE
|
|
DW 0xffff ; limit 15:0
|
|
DW 0 ; base 15:0
|
|
DB 0 ; base 23:16
|
|
DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(DATA32_TYPE)
|
|
DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(1)|CODE64_FLAG(0)|UPPER_LIMIT(0xf)
|
|
DB 0 ; base 31:24
|
|
|
|
; linear code segment descriptor
|
|
LINEAR_CODE_SEL equ $-GDT_BASE
|
|
DW 0xffff ; limit 15:0
|
|
DW 0 ; base 15:0
|
|
DB 0 ; base 23:16
|
|
DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(CODE32_TYPE)
|
|
DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(1)|CODE64_FLAG(0)|UPPER_LIMIT(0xf)
|
|
DB 0 ; base 31:24
|
|
|
|
%ifdef ARCH_X64
|
|
; linear code (64-bit) segment descriptor
|
|
LINEAR_CODE64_SEL equ $-GDT_BASE
|
|
DW 0xffff ; limit 15:0
|
|
DW 0 ; base 15:0
|
|
DB 0 ; base 23:16
|
|
DB PRESENT_FLAG(1)|DPL(0)|SYSTEM_FLAG(1)|DESC_TYPE(CODE64_TYPE)
|
|
DB GRANULARITY_FLAG(1)|DEFAULT_SIZE32(0)|CODE64_FLAG(1)|UPPER_LIMIT(0xf)
|
|
DB 0 ; base 31:24
|
|
%endif
|
|
|
|
GDT_END:
|
|
|