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; vectors.s - idt for x86_64
[GLOBAL idt]
[GLOBAL idt_descr]
[GLOBAL vectors_start]
[EXTERN interrupt_gate]
[SECTION .data.idt]
;
; Interrupt descriptor table with 256 entries
; TODO: use a interrupt stack instead of the current stack.
;
idt:
%macro idt_entry 1
dw (wrapper_%1 - wrapper_0) & 0xffff ; offset 0 .. 15
dw 0x0000 | 0x8 * 2 ; selector points to 64-bit code segment selector (GDT)
dw 0x8e00 ; 8 -> interrupt is present, e -> 80386 32-bit interrupt gate
dw ((wrapper_%1 - wrapper_0) & 0xffff0000) >> 16 ; offset 16 .. 31
dd ((wrapper_%1 - wrapper_0) & 0xffffffff00000000) >> 32 ; offset 32..63
dd 0x00000000 ; reserved
%endmacro
%assign i 0
%rep 256
idt_entry i
%assign i i+1
%endrep
idt_descr:
dw 256*8 - 1 ; 256 entries
dq idt
; template for header for each interrupt-handling routine
%macro wrapper 1
wrapper_%1:
push rbp
mov rbp, rsp
push rax
mov al, %1
jmp wrapper_body
%endmacro
; automatic generation of 256 interrupt-handling routines, based on above macro
[SECTION .data.vectors]
vectors_start:
%assign i 0
%rep 256
wrapper i
%assign i i+1
%endrep
; common handler body
wrapper_body:
; GCC expects the direction flag to be 0
cld
; save volatile registers
push rcx
push rdx
push rdi
push rsi
push r8
push r9
push r10
push r11
; the generated wrapper only gives us 8 bits, mask the rest
and rax, 0xff
; call the interrupt handling code with interrupt number as parameter
mov rdi, rax
call interrupt_gate
; restore volatile registers
pop r11
pop r10
pop r9
pop r8
pop rsi
pop rdi
pop rdx
pop rcx
; ... also those from the wrapper
pop rax
pop rbp
; done
iretq
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