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Kernel: x86_64 boot script now makes GDT with null, kernel code and data

This commit is contained in:
Bananymous 2023-03-01 20:17:03 +02:00
parent ba8c4dbc7f
commit 7f8cad83b1
1 changed files with 12 additions and 20 deletions
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32
kernel/arch/x86_64/boot.S
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@ -10,19 +10,6 @@
.set PG_READ_WRITE, 1<<1
.set PG_PAGE_SIZE, 1<<7
# GDT access byte
.set GDT_A_A, 1<<40
.set GDT_A_RW, 1<<41
.set GDT_A_DC, 1<<42
.set GDT_A_E, 1<<43
.set GDT_A_S, 1<<44
.set GDT_A_DPL, 1<<45
.set GDT_A_P, 1<<47
# GDT flags
.set GDT_F_L, 1<<53
.set GDT_F_DB, 1<<54
.set GDT_F_G, 1<<55
.code32
# Multiboot header
@ -40,9 +27,11 @@
.section .bss, "aw", @nobits
# Create stack
stack_bottom:
.global g_boot_stack_bottom
g_boot_stack_bottom:
.skip 16384
stack_top:
.global g_boot_stack_top
g_boot_stack_top:
.global g_kernel_cmdline
g_kernel_cmdline:
@ -73,8 +62,9 @@ g_multiboot_magic:
.skip 8
boot_gdt:
.quad 0 # null descriptor
.quad (GDT_F_G | GDT_F_L ) | (GDT_A_P | (0 * GDT_A_DPL) | GDT_A_S | GDT_A_E | GDT_A_RW) | (0xF << 48 | 0xFFFF) # kernel code
.quad 0x0000000000000000 # null descriptor
.quad 0x00AF9A000000FFFF # kernel code
.quad 0x00AF92000000FFFF # kernel data
boot_gdtr:
.short . - boot_gdt - 1
.quad boot_gdt
@ -171,7 +161,7 @@ initialize_paging:
.type _start, @function
_start:
# Initialize stack and multiboot info
movl $stack_top, %esp
movl $g_boot_stack_top, %esp
movl %eax, g_multiboot_magic
movl %ebx, g_multiboot_info
@ -187,9 +177,11 @@ _start:
.code64
long_mode:
# clear segment registers
movw $0x00, %ax
movw $0x10, %ax
movw %ax, %ss
# clear segment registers (unused in x86_64?)
movw $0x00, %ax
movw %ax, %ds
movw %ax, %es
movw %ax, %fs