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bits 64
global load_gdt_and_idt
section .rodata
;0x28 picked to align with limine choice
;0x18 - tss
;0x28 - kernel code
;0x30 - kernel data
;0x38 - user data
;0x40 - user code
tss:
times 9 dd 0
dq 0xffffffffffeff000
times 15 dd 0
gdtr:
dw 0x47
dq gdt
idtr:
dw 4095
dq idt
section .bss
idt:
resq 512
global exception_info
exception_info:
.rax:
resq 1
.rbx:
resq 1
.rcx:
resq 1
.rdx:
resq 1
.rdi:
resq 1
.rsi:
resq 1
.rbp:
resq 1
.rsp:
resq 1
.r8:
resq 1
.r9:
resq 1
.r10:
resq 1
.r11:
resq 1
.r12:
resq 1
.r13:
resq 1
.r14:
resq 1
.r15:
resq 1
.cr3:
resq 1
.rip:
resq 1
.rflags:
resq 1
.error:
resq 1
.has_error:
resb 1
.exception_number:
resb 1
section .rodata
has_error_code:
db 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0
exception_isrs:
dq exception_00, exception_01, exception_02, exception_03
dq exception_04, exception_05, exception_06, exception_07
dq exception_08, exception_09, exception_0a, exception_0b
dq exception_0c, exception_0d, exception_0e, exception_0f
section .text
extern print_exception
exception_00:
mov byte [exception_info.exception_number], 0x00
jmp exception_common
exception_01:
mov byte [exception_info.exception_number], 0x01
jmp exception_common
exception_02:
mov byte [exception_info.exception_number], 0x02
jmp exception_common
exception_03:
mov byte [exception_info.exception_number], 0x03
jmp exception_common
exception_04:
mov byte [exception_info.exception_number], 0x04
jmp exception_common
exception_05:
mov byte [exception_info.exception_number], 0x05
jmp exception_common
exception_06:
mov byte [exception_info.exception_number], 0x06
jmp exception_common
exception_07:
mov byte [exception_info.exception_number], 0x07
jmp exception_common
exception_08:
mov byte [exception_info.exception_number], 0x08
jmp exception_common
exception_09:
mov byte [exception_info.exception_number], 0x09
jmp exception_common
exception_0a:
mov byte [exception_info.exception_number], 0x0a
jmp exception_common
exception_0b:
mov byte [exception_info.exception_number], 0x0b
jmp exception_common
exception_0c:
mov byte [exception_info.exception_number], 0x0c
jmp exception_common
exception_0d:
mov byte [exception_info.exception_number], 0x0d
jmp exception_common
exception_0e:
mov byte [exception_info.exception_number], 0x0e
jmp exception_common
exception_0f:
mov byte [exception_info.exception_number], 0x0f
jmp exception_common
exception_common:
mov qword [exception_info.rax], rax
movzx rax, byte [exception_info.exception_number]
mov al, byte [has_error_code + rax]
test al, al
jz .no_error_code
mov byte [exception_info.has_error], 1
pop rax
mov qword [exception_info.error], rax
jmp .post_error_code
.no_error_code:
mov byte [exception_info.has_error], 0
.post_error_code:
mov qword [exception_info.rbx], rbx
mov qword [exception_info.rcx], rcx
mov qword [exception_info.rdx], rdx
mov qword [exception_info.rdi], rdi
mov qword [exception_info.rsi], rsi
mov qword [exception_info.rbp], rbp
mov qword [exception_info.r8], r8
mov qword [exception_info.r9], r9
mov qword [exception_info.r10], r10
mov qword [exception_info.r11], r11
mov qword [exception_info.r12], r12
mov qword [exception_info.r13], r13
mov qword [exception_info.r14], r14
mov qword [exception_info.r15], r15
pop rax
mov qword [exception_info.rip], rax
pop rax
pop rax
mov qword [exception_info.rflags], rax
pop rax
mov qword [exception_info.rsp], rax
mov rax, cr3
mov qword [exception_info.cr3], rax
jmp print_exception
set_isr:
;rdi - index
;sil - 1 if this is a trap, 0 if it is an interrupt
;rdx - isr pointer
shl rdi, 4
add rdi, idt
mov word [rdi], dx
shr rdx, 16
mov word [rdi + 6], dx
shr rdx, 16
mov dword [rdi + 8], edx
or sil, 0xef
mov byte [rdi + 5], sil
mov word [rdi + 2], 0x28
mov byte [rdi + 4], 1
ret
section .data
gdt:
dq 0
dq 0
dq 0
.tss:
dq 0x0000e90000000067
dq 0;tss is 2 qwords wide
dq 0x00209b0000000000
dq 0x00009b0000000000
dq 0x0000fb0000000000
dq 0x0020fb0000000000
section .text
load_gdt_and_idt:
mov rcx, 8
.loop:
mov rdi, rcx
dec rdi
mov sil, 1
mov rdx, qword [exception_isrs + rdi * 8]
call set_isr
loop .loop
mov rax, tss
mov word [gdt.tss + 2], ax
shr rax, 16
mov byte [gdt.tss + 4], al
mov byte [gdt.tss + 7], ah
shr rax, 16
mov dword [gdt.tss + 8], eax
lgdt [gdtr]
lidt [idtr]
mov ax, 0x18
ltr ax
ret
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