os-k/boot/loader.asm

;=----------------------------------------------------------------------------=;
;                            GNU GPL OS/K                                      ;
;                                                                              ;
;   Authors: spectral`                                                         ;
;            NeoX                                                              ;
;                                                                              ;
;   Desc:   Kernel (second stage) Loader for OS/K                              ;
;                   (x86_64 architecture only)                                 ;
;=----------------------------------------------------------------------------=;

;;VIDEO
%define TRAM 0x0B8000                       ; [T]ext[RAM]
%define VRAM 0x0A0000                       ; [V]ideo[RAM]

;; BPB
%define OEMName           bp+0x03           ; Disk label
%define bytesPerSector    bp+0x0b           ; Bytes per sector
%define sectorsPerCluster bp+0x0d           ; Sectors per cluster
%define reservedSectors   bp+0x0e           ; Reserved sectors
%define fats              bp+0x10           ; Number of fats
%define rootDirEntries    bp+0x11           ; Number of entries in root dir
%define sectors           bp+0x13           ; Logical sectors
%define mediaType         bp+0x15           ; Media descriptor byte
%define fatSectors        bp+0x16           ; Sectors per FAT
%define sectorsPerTrack   bp+0x18           ; Sectors per track
%define heads             bp+0x1a           ; Number of sides/heads
%define hiddenSectors     bp+0x1c           ; Hidden sectors
%define hugeSectors       bp+0x20           ; LBA sectors
%define biosBootdrvNum    bp+0x24           ; Bootdrv number
%define reserved          bp+0x25           ; This is not used
%define bootSignature     bp+0x26           ; Bootdrv signature
%define volumeId          bp+0x27           ; Volume ID
%define volumeLabel       bp+0x2b           ; Volume Label
%define fatTypeLabel      bp+0x36           ; File system type 

[BITS 16]
[ORG 0x1000]

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
jmp 0x0000:main

;; DATA

Bootdrv     db          0
VGA_HEIGHT  dq          0
VIDEO_MODE  dw          0

;; GDT WITH DOC
GDT64:
        NULL_SELECTOR:    ;; null selector within 64 bits        
                        dw     GDT_LENGTH   ; limit of GDT 
                        dw     GDT64        ; linear address of GDT
                        dd     0x0          ;            

        CODE_SELECTOR:    ;; 32-bit code selector (ring 0)
                        dw     0x0FFFF      ; Segment Limit
                        db    0x0, 0x0, 0x0 ; Base Address
                        db  10011010b       ;    |7|6|5|4|3|2|1|0|
                                            ;     | | | | | | | `----- 1 when segment used. 
                                            ;     | | | | | | `------ 1 when writable. 
                                            ;     | | | | | `------- 1 if "conformant". Don't know what is it... spectral ? xD
                                            ;     | | | | `-------- 1 always
                                            ;     | | | `--------- 1 for segment descriptor, 0 for system descriptor
                                            ;     | | `---------- DPL !!! 0 for ring 0 
                                            ;     | `----------- DPL (2/2)
                                            ;     `------------ 1 if in physical memory, 0 if page fault 
                        db    11001111b     ;    |7|6|5|4|3|2|1|0|
                                            ;     | | | | | | | `----- Limit 16
                                            ;     | | | | | | `------ Limit 17
                                            ;     | | | | | `------- Limit 18
                                            ;     | | | | `-------- Limit 19
                                            ;     | | | `--------- available for use
                                            ;     | | `---------- 0 always
                                            ;     | `----------- size of data. 1 for 32bits
                                            ;     `------------ 0 if limit is in Bytes, 1 if it's in pages (4ko)
                        db    0x0           ; Base Address
                        
        DATA_SELECTOR:    ;; flat data selector (ring 0)
                        dw     0x0FFFF      ; Segment Limit
                        db    0x0, 0x0, 0x0 ; Base Address
                        db  10010010b       ;    |7|6|5|4|3|2|1|0| 
                                            ;     | | | | | | | `----- 1 when segment used.  
                                            ;     | | | | | | `------ 1 when writable.
                                            ;     | | | | | `------- expansion direction. 1 for a LIFO
                                            ;     | | | | `-------- 1 always            
                                            ;     | | | `--------- 1 for segment descriptor, 0 for system descriptor
                                            ;     | | `---------- DPL !!! 0 for ring 0 
                                            ;     | `----------- DPL (2/2)
                                            ;     `------------ 1 if in physical memory, 0 if page fault  
                        db    10001111b     ;    |7|6|5|4|3|2|1|0|
                                            ;     | | | | | | | `----- Limit 16
                                            ;     | | | | | | `------ Limit 17
                                            ;     | | | | | `------- Limit 18
                                            ;     | | | | `-------- Limit 19
                                            ;     | | | `--------- available for use
                                            ;     | | `---------- 0 always
                                            ;     | `----------- size of data. 1 for 32bits
                                            ;     `------------ 0 if limit is in Bytes, 1 if it's in pages (4ko)
                        db    0x0           ; Base Address
                        
        LONG_SELECTOR:    ;; 64-bit code selector (ring 0)
                        dw     0x0FFFF      ;  Segment Limit
                        db    0x0, 0x0, 0x0 ; Base Address
                        db  10011010b       ;    |7|6|5|4|3|2|1|0|
                                            ;     | | | | | | | `----- 1 when segment used. 
                                            ;     | | | | | | `------ 1 when writable. 
                                            ;     | | | | | `------- 1 if "conformant". Don't know what is it... spectral ? xD
                                            ;     | | | | `-------- 1 always
                                            ;     | | | `--------- 1 for segment descriptor, 0 for system descriptor
                                            ;     | | `---------- DPL !!! 0 for ring 0 
                                            ;     | `----------- DPL (2/2)
                                            ;     `------------ 1 if in physical memory, 0 if page fault 
                        db    10101111b     ;    |7|6|5|4|3|2|1|0|
                                            ;     | | | | | | | `----- Limit 16
                                            ;     | | | | | | `------ Limit 17
                                            ;     | | | | | `------- Limit 18
                                            ;     | | | | `-------- Limit 19
                                            ;     | | | `--------- available for use
                                            ;     | | `---------- 0 always
                                            ;     | `----------- size of data. 1 for 32bits
                                            ;     `------------ 0 if limit is in Bytes, 1 if it's in pages (4ko)
                        db    0x0           ; Base Address
    GDT_LENGTH:

%include "boot/loader16.inc"

main:    
    ;; compatibility check
    mov si, Init
    call PrintB
    pop si
    call Is64bits
    jc ErrorNo64
    push si 
    mov si, Pass
    call PrintB
    
    ;; Enabling A20
    mov si, EnA20
    call PrintB
    pop si     
    in al, 0x92
    or al, 2
    out 0x92, al
    push si 
    mov si, Pass
    call PrintB
    
    ;; DISABLING CURSOR BLINKING AND GETTING INFOS
    call get_dimensions
    call disable_cursor

    ;;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

[BITS 32]
VIDEO_MODE32 dw 0
VGA_HEIGHT32 dw 0

main32:
    pop dword [VGA_HEIGHT32]
    pop dword [VIDEO_MODE32]
    
    ;; 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]

%include "boot/loader64.inc"

;; DATA    
txt             db  0x09, " Switching to Long Mode... ", 0
Init            db  "Booting OS/K !", 0x0D, 0x0A, 0x0D, 0x0A, 0x09, " Checking CPUID...",0
Reinit          db  "Booting OS/K !", 0x0D, 0x0A, 0x0D, 0x0A, 0
CPUIDD          db  0x09, " Checking CPUID...", 0
EnA20           db  0x09, " Enabling A20 line...", 0
NoLongMode      db  0x0A, 0x0D, "ERROR : Your computer is not designed for x64 OS", 0
Pass            db  " OK", 0x0A, 0x0D, 0
NextTRAM        dq  0x0B8000                ; Last position of cursor
VIDEO_MODE64    dq  0
VGA_HEIGHT64    dq  0
VGA_X           dq  0x0
msg             db  "The system is now in x64 mode. Is this not beautiful ?", 0x0A, 0x0D, 0

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

    mov bl, 0x0A
    mov esi, Pass
    call write

    mov bl, 0x0F
    mov esi, txt
    call write
    
    mov bl, 0x0A
    mov esi, Pass
    call write
    
    mov bl, 0x0D
    mov esi, msg
    call write

    jmp Die

[BITS 16]
ErrorNo64:
    mov si, NoLongMode
    call PrintB
Die:
    cli
    hlt                                     ; die nooooow
    jmp 0xF000:0xFFF0