os-k/boot/loader/loader.asm

;=----------------------------------------------------------------------------=;
;                            GNU GPL OS/K                                      ;
;                                                                              ;
;   Desc:   Kernel (second stage) Loader for OS/K                              ;
;                   (x86_64 architecture only)                                 ;
;                                                                              ;
;                                                                              ;
;   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/>.             ;
;=----------------------------------------------------------------------------=;

%define DEBUG

[BITS 32]
[global _start]
[ORG 0x100000]                                  ; Where GRUB loads us.

%include "boot/loader/multiboot.inc"

_start:
    mov ax, cs                                  ; correcting cs after the horrible far jump
    mov ds, ax                                  ; hm... And ds too
    mov es, ax                                  ; And es because it is jealous

    mov [Bootdrv], dl
    xor dl, dl
    jmp 0x0000:main ; pas sûr

[align 4]
dd MULTIBOOT_HEADER_MAGIC
dd MULTIBOOT_HEADER_FLAGS
dd CHECKSUM
dd multiboot_header                             ; Header address
dd _start                                       ; Address of code entry point
dd 00                                           ; (end of code) not necessary
dd 00                                           ; (bss) not necessary
dd MB_start                                     ; entry address GRUB will start at

MB_start:
    mov esp, KERNEL_STACK                       ; Setup the stack
    push 0                                      ; Reset EFLAGS
    popf
    push eax                                    ; 2nd argument is magic number
    push ebx                                    ; 1st argument multiboot info pointer
    call main
    add esp, 8                                  ; Cleanup 8 bytes pushed as arguments
    jmp Die

%include "boot/loader/cpu/cpuid.asm"
%include "boot/loader/io/rmterm.asm"
%include "boot/loader/io/rmmem.asm"

main:

    ;;GO GDT64
    cli                                     ; disable interrupts
    lgdt [GDT64]
    ;; ACTIVATE PROTECTED MODE
    mov eax, cr0
    or al, 1b                               ; PE = 1
    mov cr0, eax
    ;; DISABLE PAGING
    mov eax, cr0
    and eax, 0x7FFFFFFF                     ; PG = 0
                                            ;   |0|111111111111111111111111111111
                                            ;    |
                                            ;    `------ Paging bit
    mov cr0, eax

    push dword [VIDEO_MODE]
    push dword [VGA_HEIGHT]
    jmp (CODE_SELECTOR-GDT64):main32

Die:
    cli
    hlt                                     ; die nooooow
    jmp 0xF000:0xFFF0
;; END OF THE HOLE ---------------------------------------------------------- ;;

[BITS 32]
main32:
    pop dword [VGA_HEIGHT32]
    pop dword [VIDEO_MODE32]

    ;; VERIFY A20
    pushad
    mov edi,0x112345                        ;odd megabyte address.
    mov esi,0x012345                        ;even megabyte address.
    mov [esi],esi                           ;making sure that both addresses contain diffrent values.
    mov [edi],edi                           ;(if A20 line is cleared the two pointers would point to the address 0x012345 that would contain 0x112345 (edi))
    cmpsd                                   ;compare addresses to see if the're equivalent.
    popad
    jne .A20_on                             ;if not equivalent , A20 line is set.
    mov WORD [A20_OK], 0
    jmp .A20_end
.A20_on:
    mov BYTE [A20_OK], 1
.A20_end:

    ;; INITIALIZE PROTECTED MODE SEGMENT REGISTERS
    mov ax, DATA_SELECTOR-GDT64
    mov ds, ax
    mov es, ax
    mov fs, ax
    mov gs, ax
    mov ss, ax

    ;; ACTIVATE PHYSICAL ADRESS EXTENSION
    mov eax, cr4
    or eax, 100000b                         ; PAE = 1 = 4 Mo / page.  0 = 4 Ko
    mov cr4, eax

    ;;cleanup
    mov edi, 0x70000
    mov ecx, 0x10000
    xor eax, eax
    rep stosd
    ;;formatting
    mov dword [0x70000], 0x71000 + 7        ; first PDP table
    mov dword [0x71000], 0x72000 + 7        ; first page directory
    mov dword [0x72000], 0x73000 + 7        ; first page table
    mov edi, 0x73000                        ; address of first page table
    mov eax, 7
    mov ecx, 256                            ; number of pages to map (1 MB)
.make_page_entries:
    stosd
    add edi, 4
    add    eax, 0x1000
    loop .make_page_entries
    ;; pointing pml4
    mov eax, 0x70000                        ; Bass address of PML4
    mov    cr3, eax                            ; load page-map level-4 base

    ;; ACTIVATE LONG MODE
    mov ecx, 0xC0000080                     ; address of MSR
    rdmsr                                   ; read MSR
    or eax, 100000000b                      ; LME = 1. (Long Mode Enable)
    wrmsr                                   ; write MSR

    ;; ACTIVATE PAGING
    mov    eax, cr0
    or eax, 0x80000000                      ; make bit 31 (PG = Paging) to 1 :
                                            ;    |1|000000000000000000000000000000
                                            ;     |
                                            ;     `------ Paging bit
    mov cr0, eax
    push dword 0
    push dword [VIDEO_MODE]
    push dword 0
    push dword [VGA_HEIGHT]
    jmp (LONG_SELECTOR-GDT64):main64

[BITS 64]

;; DATA
    Init            db  "Booting OS/K !", 0x0D, 0x0A, 0x0D, 0x0A, 0x09, " Checking CPUID...",0
    CPUIDD          db  0x09, " Checking CPUID...", 0
    EnA20           db  0x09, " Enabling A20 line...", 0
%ifdef DEBUG
    ReadAttempt     db  0x09, " Attempt to read a sector with ATA commands...", 0x0A, 0x0D, 0x0A, 0x0D, 0
%else
    ReadAttempt     db  0x09, " Attempt to read a sector with ATA commands...", 0
%endif
    txt             db  0x09, " Switching to Long Mode... ", 0
    EndOfLoader     db  "End of loader.bin. System will halt !", 0x0A, 0x0D, 0
    Reinit          db  "Booting OS/K !", 0x0D, 0x0A, 0x0D, 0x0A, 0
    Pass            db  " OK", 0x0A, 0x0D, 0
    Fail            db  " FAIL!", 0x0A, 0x0D, 0
    msg             db  "The system is now in x64 mode. Is this not beautiful ?", 0x0A, 0x0D, 0
    FileNotFound    db  "Second Stage Error : The Kernel was not found.", 0x0A, 0x0D, 0
    DiskError       db  "Second Stage Error : The Disk has crashed.", 0x0A, 0x0D, 0
    filename        db  "KERNEL  BIN"

%include "boot/loader/io/lmmem.asm"
%include "boot/loader/io/lmterm.asm"
%include "boot/loader/io/ata.asm"
%include "boot/loader/cpu/cpu.asm"
%include "boot/loader/fs/fat.asm"

main64:
    pop qword [VGA_HEIGHT64]
    pop qword [VIDEO_MODE64]
    ;; INITIALIZE STACK
    mov rsp, 0x9F000

    call clear

    ;; Printing
    mov bl, 0x0B
    mov esi, Reinit
    call write

    mov bl, 0x0F
    mov esi, CPUIDD
    call write

    mov bl, 0x0A
    mov esi, Pass
    call write

    mov bl, 0x0F
    mov esi, EnA20
    call write

    call check_a20

    mov bl, 0x0F
    mov esi, txt
    call write

    mov bl, 0x0A
    mov esi, Pass
    call write

    mov bl, 0x0D
    mov esi, msg
    call write

    mov bl, 0x0F
    mov esi, ReadAttempt
    call write

    call temporize                           ; Temporized because the ATA drive must be ready

    mov bl, 1
    mov bh, 1
    call ata_read

    mov bl, 0x0D
    mov esi, EndOfLoader
    call write

    jmp Die