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Using LLVM and NASM now.

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I need to reimplement the GDT, although hopefully now I can get it to
work in C.
This commit is contained in:
Nicolás A. Ortega Froysa
2018-03-14 15:08:02 +01:00
parent 2ca0402fba
commit ea6b0f69d2
2 changed files with 47 additions and 135 deletions
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169
src/kernel/arch/x86/boot.s
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@@ -1,139 +1,50 @@
/*
* Copyright (C) 2018 Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
* Author: Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
*
* This program 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.
*
* This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
; Copyright (C) 2018 Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
; Author: Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
;
; This program 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.
;
; This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
# declare constants for the multiboot header
.set ALIGN, 1 << 0 # align loaded modules on page boundaries
.set MEMINFO, 1 << 1 # provide memory map
.set FLAGS, ALIGN | MEMINFO # the multiboot `FLAG' field
.set MAGIC, 0x1BADB002 # 'magic number' letting the boot loader know we're here
.set CHECKSUM , -(MAGIC + FLAGS) # checksum of the above to prove we're multiboot
MBALIGN equ 1<<0 ; align loaded modules on page boundaries
MEMINFO equ 1<<1 ; provide memory map
FLAGS equ MBALIGN | MEMINFO ; multiboot flag field
MAGIC equ 0x1BADB002 ; magic number to help bootloader find the header
CHECKSUM equ -(MAGIC + FLAGS) ; checksum of the above data
/*
* Declare the multiboot header marking this program as a kernel. The bootloader
* will search for these values in the first 8 KiB of the kernel file aligned at
* 32-bit boundaries (4 bytes). We put the signature in its own section to force
* it within the first 8 KiB of the kernel file.
*/
.section .multiboot
.align 4
.long MAGIC
.long FLAGS
.long CHECKSUM
section .multiboot
align 4
dd MAGIC
dd FLAGS
dd CHECKSUM
/*
* Create a 16 byte aligned stack with 16 KiB of size. We create labels at the
* bottom and top of the stack.
*/
.section .bss
.align 16
section .bss
align 16
stack_bottom:
.skip 16384 # 16 KiB
resb 16384 ; 16KiB
stack_top:
/*
* Create the GDT
*/
.section .data
gdt_start:
gdt_null:
.long 0x0
.long 0x0
gdt_kcode:
.word 0xFFFF # limit
.word 0x0 # base
.byte 0x0 # base
.byte 0b10011010 # 1st flags | type flags
.byte 0b11001111 # 2nd flags | limit
.byte 0x0 # base
gdt_kdata:
.word 0xFFFF # limit
.word 0x0 # base
.byte 0x0 # base
.byte 0b10010010 # 1st flags | type flags
.byte 0b11001111 # 2nd flags | limit
.byte 0x0 # base
gdt_ucode:
.word 0xFFFF # limit
.word 0x0 # base
.byte 0x0 # base
.byte 0b11111010 # 1st flags | type flags
.byte 0b11001111 # 2nd flags | limit
.byte 0x0 # base
gdt_udata:
.word 0xFFFF # limit
.word 0x0 # base
.byte 0x0 # base
.byte 0b11110010 # 1st flags | type flags
.byte 0b11001111 # 2nd flags | limit
.byte 0x0 # base
# TODO: setup the TSS
gdt_tss:
.word 0x0 # size of TSS (set later)
.word 0x0 # address of TSS (set later)
.byte 0x0 # address of TSS (set later)
.byte 0b10010001 # 1st flags | type flags
.byte 0b01000000 # 2nd flags | size of TSS (set later
.byte 0x0 # address of TSS (set later)
gdt_end:
gdtr:
.word (gdt_end - gdt_start - 1)
.long gdt_start
/*
* The linker script specifies the `_start' label as the entry point to the kernel
* and the bootloader will jump to this position. That is, this is where the kernel
* starts.
*/
.section .text
.global _start
.type _start, @function
section .text
global _start:function (_start.end - _start)
_start:
# set the position of `%esp' to the top of the stack
mov $stack_top, %esp
; setup the stack
mov esp, stack_top
# GDT, paging, and other features
flush_gdt:
cli
lgdt (gdtr)
movw $0x10, %ax
movw %ax, %ds
movw %ax, %es
movw %ax, %fs
movw %ax, %gs
movw %ax, %ss
ljmp $0x08, $flush_end
flush_end:
boot_kernel:
# enter high-level kernel (C)
; call the kernel
extern kernel_main
call kernel_main
# put computer into infinite loop
cli # disable interrupts by clearing the interrupt flag in `eflags'
end_loop:
hlt # wait for next interrupt
jmp end_loop # jump to the `hlt' instruction if it ever leaves it
.size _start, . - _start
; hang
cli
.hang:
hlt
jmp .hang
.end: