ISR/IRQ Exports and Exception Macros

Author: PythonPlumber

src/cpu/isr.s

@@ -2,8 +2,6 @@
 
 extern isr_handler
 extern irq_handler
-global isr_handler
-global irq_handler
 
 %macro ISR_NOERR 1
 global isr%1
@@ -48,7 +46,7 @@ ISR_ERR 13
 ISR_ERR 14
 ISR_NOERR 15
 ISR_NOERR 16
-ISR_NOERR 17
+ISR_ERR 17
 ISR_NOERR 18
 ISR_NOERR 19
 ISR_NOERR 20
@@ -61,7 +59,7 @@ ISR_NOERR 26
 ISR_NOERR 27
 ISR_NOERR 28
 ISR_NOERR 29
-ISR_NOERR 30
+ISR_ERR 30
 ISR_NOERR 31
 ISR_NOERR 128
 
@@ -100,8 +98,7 @@ isr_common_stub:
     mov gs, ax
     push esp
     call isr_handler
-    add esp, 4
-    mov esp, eax
+    mov esp, eax    ; IMPORTANT: use the returned (potentially switched) stack pointer
 
     pop eax
     mov gs, ax
@@ -135,8 +132,7 @@ irq_common_stub:
     mov gs, ax
     push esp
     call irq_handler
-    add esp, 4
-    mov esp, eax
+    mov esp, eax    ; IMPORTANT: use the returned (potentially switched) stack pointer
 
     pop eax
     mov gs, ax

src/task/switch.s

@@ -57,22 +57,30 @@ switch_to:
     ret
 
 %define PROC_ESP 36
+%define PROC_EBP 40
 
 context_switch:
-    mov eax, [esp+4]
-    mov edx, [esp+8]
-    mov ecx, [esp+12]
+    ; [esp+4] = previous process (process_t*)
+    ; [esp+8] = next process (process_t*)
+    ; [esp+12] = registers (registers_t*)
+    
+    mov eax, [esp+4]    ; eax = previous
+    mov edx, [esp+8]    ; edx = next
+    
     test eax, eax
     jz .load_next
-    mov [eax+PROC_ESP], ecx
+    
+    ; Save current ESP and EBP to previous task
+    mov [eax+PROC_ESP], esp
+    mov [eax+PROC_EBP], ebp
+    
 .load_next:
+    ; Switch to next task's ESP and EBP
     mov esp, [edx+PROC_ESP]
-    pop eax
-    mov ds, ax
-    mov es, ax
-    mov fs, ax
-    mov gs, ax
-    popa
-    add esp, 8
-    sti
-    iret
+    mov ebp, [edx+PROC_EBP]
+    
+    ; Note: If this was called from irq0_handler, the 'esp' we just restored
+    ; points to a registers_t struct. The assembly stub in isr.s will 
+    ; then pop these registers and iret.
+    
+    ret