minimal cpu exception handling

1 files changed, 254 insertions, 0 deletions

diff --git a/kernel/interrupts.asm b/kernel/interrupts.asm
new file mode 100644
index 0000000..c375ee4
--- /dev/null
+++ b/kernel/interrupts.asm
@@ -0,0 +1,254 @@
+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