b6c999753f
2. Linker script for kernel. 2. Updated mkiso script to link C with nasm and build a runable multiboot1 iso.
111 lines
1.6 KiB
NASM
111 lines
1.6 KiB
NASM
global print_str
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global kernel_stack
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extern hk_main
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[SECTION .multiboot]
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[BITS 32]
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GRUB_LOADED_FLAG equ 0x2BADB002
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GRUB_MAGIC_NUMBER equ 0x1BADB002
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GRUB_FLAGS equ 0x10003
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GRUB_CHECK_SUM equ -(GRUB_MAGIC_NUMBER + GRUB_FLAGS)
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GRUB_HEADER_ADDR:
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dd GRUB_MAGIC_NUMBER
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dd GRUB_FLAGS
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dd GRUB_CHECK_SUM
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dd GRUB_HEADER_ADDR
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dd GRUB_HEADER_ADDR
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dd 0
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dd 0
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dd GRUB_ENTRY_ADDR
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%include "pm.inc"
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;GDT to load
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DESC_VOID: Descriptor 0,0,0
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DESC_GRAPH: Descriptor 0b8000h,0xffff,DA_DRW | DA_DPL3
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DESC_FLAT_C: Descriptor 0,0xfffff,DA_CR | DA_32 | DA_LIMIT_4K
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DESC_FLAT_RW: Descriptor 0,0xfffff,DA_DRW | DA_32 | DA_LIMIT_4K
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GDT_END:
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GDT_LENGTH equ GDT_END - DESC_VOID - 1
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GDT_PTR:
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dw GDT_LENGTH
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dd DESC_VOID
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;SELECTORS
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SLCT_CODE_0 equ DESC_FLAT_C - DESC_VOID
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SLCT_GRAPH_0 equ DESC_GRAPH - DESC_VOID
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SLCT_DATA_0 equ DESC_FLAT_RW - DESC_VOID
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;Message
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DUMMY_MSG:
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db 'Loaded by multiboot1!',0
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;stack
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times 1024 db 0
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kernel_stack:
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GRUB_ENTRY_ADDR:
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cli
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cmp eax,GRUB_LOADED_FLAG
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jmp LOADED_BY_GRUB
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hlt
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LOADED_BY_GRUB:
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mov eax,kernel_stack
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mov esp,eax
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push dword 0
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popfd
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lgdt [GDT_PTR]
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jmp SLCT_CODE_0:reload_cs
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reload_cs:
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mov ax,SLCT_DATA_0
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mov ss,ax
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mov ds,ax
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mov es,ax
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mov fs,ax
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mov ax,SLCT_GRAPH_0
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mov gs,ax
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push DUMMY_MSG
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xchg bx,bx
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call print_str
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add esp,4
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call hk_main
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end:
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jmp end
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print_str:
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;void printf(char* str)
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;EAX,ECX,EDX
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push ebp
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mov ebp,esp
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push edi
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push esi
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mov edi,dword [ss:ebp+8]
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xor esi,esi
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xor ecx,ecx
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.begin:
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mov al,byte [ds:edi]
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cmp al,0 ;0 ended
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je .end
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mov byte [gs:esi],al
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inc esi
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mov byte [gs:esi],0x0c
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inc edi
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inc esi
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jmp .begin
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.end:
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pop esi
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pop edi
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mov esp,ebp
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pop ebp
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ret
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