maybe i'm close to fixing multitasking

2025-05-16 14:55:19 +03:00
parent 4fbaed321c
commit 2e372ae9c4
3 changed files with 209 additions and 195 deletions
@@ -1,117 +1,64 @@
-extern current
-global switchProcess
-
 struc PCB
-     .PID                resd 1 ; Offset: 0
-     .STATE              resd 1 ; Offset: 4
-     .PROGRAM_COUNTER    resd 1 ; Offset: 8
-     .STACK_BASE         resd 1 ; Offset: 12
-     .STACK_POINTER      resd 1 ; Offset: 16
-     .FLAGS              resd 1 ; Offset: 20
-     .NEXT               resd 1 ; Offset: 24
+    .PID            resd 1  ; Offset: 0
+    .STATE          resd 1  ; Offset: 4
+    .KSTACK         resd 1  ; Offset: 8
+    .CONTEXT        resd 1  ; Offset: 12
+    .TF             resd 1  ; Offset: 16
+    .FLAGS          resd 1  ; Offset: 20
+    .NEXT           resd 1  ; Offset: 24
+    .PAGE_DIRECTORY resd 1  ; Offset: 28
 endstruc

-section .text
-
-
 ; void switchProcess(Process* next)
+section .text
+global switchProcess
+extern current
+extern trapret
+
 switchProcess:
-     ; __________Stack___________
-     ; |------------------------|
-     ; |  Return Address (EIP)  | +0
-     ; |------------------------|
-     ; |       Process* next    | +4
-     ; |------------------------|
+    ; Сохраняем регистры текущего процесса
+    push ebx
+    push esi
+    push edi
+    push ebp

-     ; Push volatile registers (per the 32-bit System V ABI)
-     push ebx
-     push esi
-     push edi
-     push ebp
+    ; Сохраняем указатель стека в current->context
+    mov edi, [current]
+    mov [edi + 12], esp  ; PCB.CONTEXT находится по смещению 12

-     ; __________Stack___________
-     ; |------------------------|
-     ; |          EBP           | +0
-     ; |------------------------| 
-     ; |          EDI           | +4
-     ; |------------------------| 
-     ; |          ESI           | +8
-     ; |------------------------| 
-     ; |          EBX           | +12
-     ; |-------- ---------------| 
-     ; |   Return Address (EIP) | +16
-     ; |------------------------| 
-     ; |       Process* next    | +20
-     ; |------------------------| 
+    ; Загружаем следующий процесс
+    mov esi, [esp + 20]  ; next (первый аргумент)
+    mov [current], esi
+    mov esp, [esi + 12]  ; Загружаем esp из next->context

-     ; Save current process' state
-     mov edi, [current]
-     ; EDI now contains the pointer to [Process* current]
-     ; |-----|
-     ; | EDI | <== [Process* current]
-     ; |-----|
+    ; Восстанавливаем регистры
+    pop ebp
+    pop edi
+    pop esi
+    pop ebx

-     ; Set [current->PCB.STACK_POINTER] to the value in ESP
-     ; Process* current->PCB.STACK_POINTER <== ESP
-     mov [edi + PCB.STACK_POINTER], esp
+    ; Проверяем ring процесса
+    mov eax, [esi + 20]  ; PCB.RING находится по смещению 20
+    cmp eax, 3
+    je .ring3
+    ret                  ; Для ring 0 просто возвращаемся
+.ring3:
+    jmp trapret          ; Для ring 3 переходим через trapret
+
+trapret:
+    ; Восстанавливаем общие регистры из trap frame
+    popal           ; edi, esi, ebp, oesp, ebx, edx, ecx, eax
+    add esp, 4      ; Пропускаем oesp (не используется)
+
+    ; Восстанавливаем сегментные регистры
+    pop gs
+    pop fs
+    pop es
+    pop ds
+
+    ; Пропускаем trapno и err
+    add esp, 8      ; trapno (4 байта) + err (4 байта)


-     ; Load next process' state
-     ; ESP has been decremented by 16, so instead of +4,
-     ; we need to do +20. 4 pushes, 1 return address, 4
-     ; bytes each.
-     mov esi, [esp + 20]
-     ; ESI now contains the pointer to [Process* next]
-     ;             __________Stack___________
-     ;             |------------------------| 
-     ;             |   Return Address (EIP) | +16
-     ; |-----|     |------------------------|
-     ; | ESI | <== |       Process* next    | +20
-     ; |-----|     |------------------------|
-
-
-     ; Set [EXTERN Process* current] to the value in ESI
-     ; Process* current <== ESI (Process* next)
-     mov [current], esi
-
-     mov esp, [esi + PCB.STACK_POINTER]
-     ; |-----|     |-----|
-     ; | ESP | <== | ESI |
-     ; |-----|     |-----|
-
-     ; Restore non-volatile registers (per the 32-bit System V ABI)
-     pop ebp
-     pop edi
-     pop esi
-     pop ebx
-
-     ; The stack is now restored to its original state.
-     ; __________Stack___________
-     ; |------------------------|
-     ; |  Return Address (EIP)  | +0
-     ; |------------------------|
-     ; |       Process* next    | +4
-     ; |------------------------|
-
-     ret
-
-global jump_usermode
-extern test_user_function
-jump_usermode:
-	mov ax, (4 * 8) | 3 ; ring 3 data with bottom 2 bits set for ring 3
-	mov ds, ax
-	mov es, ax 
-	mov fs, ax 
-	mov gs, ax ; SS is handled by iret
-
-	; and eax, ~0x80000000
-	; mov cr0, eax
-
-	; set up the stack frame iret expects
-	mov eax, esp
-	push (4 * 8) | 3 ; data selector
-	push eax ; current esp
-	pushf ; eflags
-	push (3 * 8) | 3 ; code selector (ring 3 code with bottom 2 bits set for ring 3)
-	push test_user_function ; instruction address to return to
-	iret
+    ; Теперь ESP указывает на eip, cs, eflags, esp, ss
+    iret