ReKernel/isr.asm at main · HFerrahoglu/ReKernel · GitHub

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; isr.asm — Interrupt / IRQ stubs
bits 32
section .text

extern interrupt_handler

; ── Common path ──────────────────────────────────────────────────────────────
; Stack on entry (built bottom-up by CPU + stubs):
;   [cpu]   ss, useresp (only on priv-change), eflags, cs, eip
;   [stub]  err_code, int_no
;   [below] saved by us: eax..edi (pusha), ds, es, fs, gs
;
; We pass &gs as the registers_t* argument.
; ─────────────────────────────────────────────────────────────────────────────
isr_common_stub:
    pusha                   ; saves eax,ecx,edx,ebx,esp,ebp,esi,edi
    push ds
    push es
    push fs
    push gs

    ; Load kernel data segments
    mov ax, 0x10
    mov ds, ax
    mov es, ax
    mov fs, ax
    mov gs, ax

    ; esp now points at saved gs = start of registers_t on the stack
    mov eax, esp            ; take the pointer BEFORE push so it's stable
    push eax                ; argument: registers_t *regs
    call interrupt_handler
    add esp, 4              ; clean up argument

    pop gs
    pop fs
    pop es
    pop ds
    popa
    add esp, 8              ; discard int_no + err_code
    iret

; ── Macros ───────────────────────────────────────────────────────────────────
%macro ISR_NOERR 1
global isr%1
isr%1:
    push dword 0            ; dummy error code
    push dword %1           ; interrupt number
    jmp isr_common_stub
%endmacro

%macro ISR_ERR 1
global isr%1
isr%1:                      ; CPU already pushed error code
    push dword %1
    jmp isr_common_stub
%endmacro

%macro IRQ 2                ; (irq_num, mapped_int_num)
global irq%1
irq%1:
    push dword 0
    push dword %2
    jmp isr_common_stub
%endmacro

; ── CPU exceptions 0–31 ──────────────────────────────────────────────────────
ISR_NOERR  0    ; Divide by zero
ISR_NOERR  1    ; Debug
ISR_NOERR  2    ; NMI
ISR_NOERR  3    ; Breakpoint
ISR_NOERR  4    ; Overflow
ISR_NOERR  5    ; Bound range exceeded
ISR_NOERR  6    ; Invalid opcode
ISR_NOERR  7    ; Device not available
ISR_ERR    8    ; Double fault
ISR_NOERR  9    ; Coprocessor segment overrun
ISR_ERR   10    ; Invalid TSS
ISR_ERR   11    ; Segment not present
ISR_ERR   12    ; Stack-segment fault
ISR_ERR   13    ; General protection fault
ISR_ERR   14    ; Page fault
ISR_NOERR 15
ISR_NOERR 16    ; x87 FPU
ISR_ERR   17    ; Alignment check
ISR_NOERR 18    ; Machine check
ISR_NOERR 19    ; SIMD FPU
ISR_NOERR 20    ; Virtualisation
ISR_ERR   21    ; Control protection
ISR_NOERR 22
ISR_NOERR 23
ISR_NOERR 24
ISR_NOERR 25
ISR_NOERR 26
ISR_NOERR 27
ISR_NOERR 28
ISR_NOERR 29
ISR_NOERR 30
ISR_NOERR 31

; ── Hardware IRQs (remapped to ints 32–47) ────────────────────────────────────
IRQ  0, 32      ; PIT
IRQ  1, 33      ; PS/2 keyboard
IRQ  2, 34      ; PIC cascade
IRQ  3, 35
IRQ  4, 36
IRQ  5, 37
IRQ  6, 38
IRQ  7, 39      ; spurious
IRQ  8, 40      ; RTC
IRQ  9, 41
IRQ 10, 42
IRQ 11, 43
IRQ 12, 44
IRQ 13, 45
IRQ 14, 46
IRQ 15, 47      ; spurious slave

section .note.GNU-stack noalloc noexec nowrite progbits