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full GDT, 64bt rewrite finished

This commit is contained in:
c0repwn3r 2022-05-13 23:53:59 -04:00
parent 6c243376ad
commit 2039495d5a
Signed by: core
GPG Key ID: FDBF740DADDCEECF
3 changed files with 51 additions and 11 deletions
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2
Makefile
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@ -60,7 +60,7 @@ obj/%.o: src/%.asm
# Other
run: clean bin/shade.iso
qemu-system-x86_64 -drive file=bin/shade.iso,index=0,media=disk,format=raw
qemu-system-x86_64 -drive file=bin/shade.iso,index=0,media=disk,format=raw -d int -no-reboot
clean:
rm -rf bin/*

58
src/boot/entry.asm
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@ -16,7 +16,7 @@ entry_x86:
call enable_paging
lgdt [gdt64.pointer]
jmp gdt64.code_segment:entry_x64 ; Jump into 64 bit entry
jmp gdt64.kernel_code_segment:entry_x64 ; Jump into 64 bit entry
hlt
@ -48,10 +48,10 @@ check_cpuid:
jmp error
check_x64_supported:
mov eax, 0x80000000 ; Magic code that i dont understand
cpuid ; Magic code that i dont understand
cmp eax, 0x80000001 ; Magic code that i dont undetstand
jb .x64_unsupported ; Something went wrong so x64 isnt supported
mov eax, 0x80000000
cpuid
cmp eax, 0x80000001
jb .x64_unsupported ; CPUID extended feature set isnt even supported, def no x64
mov eax, 0x80000001 ; Set magic value 0x80000001 into EAX for cpuid
cpuid ; Get "extended features list" from CPU info
@ -131,11 +131,51 @@ stack_bottom:
stack_top:
section .rodata
; Access bits
PRESENT equ 1 << 7
NOT_SYS equ 1 << 4
EXEC equ 1 << 3
DC equ 1 << 2
RW equ 1 << 1
ACCESSED equ 1 << 0
; Access bits: ring
RING0 equ 0b00000000
RING1 equ 0b00100000
RING2 equ 0b01000000
RING3 equ 0b01100000
; Flags bits
GRAN_4K equ 1 << 7
SZ_32 equ 1 << 6
LONG_MODE equ 1 << 5
gdt64:
dd 0 ; zero entry
dd 0
.code_segment: equ $ - gdt64
dq (1 << 43) | (1 << 44) | (1 << 47) | (1 << 53) ; code segment
.null: equ $ - gdt64
dq 0 ; zero entry
.kernel_code_segment: equ $ - gdt64
dd 0xffff ; limit and base (low, bits 0-15)
db 0 ; base (mid, bits 16-23)
db PRESENT | RING0 | NOT_SYS | EXEC | RW ; access: 0b10011010
db GRAN_4K | LONG_MODE | 0xf ; flags and limit (high, bits 16-19)
db 0 ; base (high, bits 24-31)
.kernel_data_segment: equ $ - gdt64
dd 0xffff ; limit and base (low, bits 0-15)
db 0 ; base (mid, bits 16-23)
db PRESENT | RING0 | NOT_SYS | RW ; access: 0b10010010
db GRAN_4K | SZ_32 | 0xf ; flags and limit (high, bits 16-19)
db 0 ; base (high, bits 24-31)
.userland_code_segment: equ $ - gdt64
dd 0xffff ; limit and base (low, bits 0-15)
db 0 ; base (mid, bits 16-23)
db PRESENT | RING3 | NOT_SYS | EXEC | RW ; access: 0b11111010
db GRAN_4K | LONG_MODE | 0xf ; flags and limit (high, bits 16-19)
db 0 ; base (high, bits 24-31)
.userland_data_segment: equ $ - gdt64
dd 0xffff ; limit and base (low, bits 0-15)
db 0 ; base (mid, bits 16-23)
db PRESENT | RING3 | NOT_SYS | RW ; access: 0b11110010
db GRAN_4K | SZ_32 | 0xf ; flags and limit (high, bits 16-19)
db 0 ; base (high, bits 24-31)
.pointer:
dw $ - gdt64 - 1 ; length
dq gdt64 ; address

2
src/iso/boot/grub/grub.cfg
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@ -1,4 +1,4 @@
set timeout=5
set timeout=0
set default=0
menuentry "shadeOS Development Build" {