lowlevel-6809: Simplify interrupt_handler after kernel_flag was removed

Rewrite the null vector in the same mapping as where we check for it.

Also simplify comments in the syscall glue.

Signed-off-by: Tormod Volden <debian.tormod@gmail.com>

diff --git a/Kernel/lowlevel-6809.s b/Kernel/lowlevel-6809.s
index 01e6397..21d5e6c 100644 (file)
--- a/Kernel/lowlevel-6809.s
+++ b/Kernel/lowlevel-6809.s
@@ -101,7 +101,6 @@ unix_syscall_entry:
 
         orcc #0x10
        ; let the interrupt logic know we are not in kernel mode any more
-       ; kernel_flag is not in common so write it before we map it away
        clr U_DATA__U_INSYS
 
         ; map process memory back in based on common (common may have
@@ -174,8 +173,7 @@ _doexec:
        ; this is a funny extra path out of syscall so we must also cover
        ; the exit from kernel here
 
-        ; map task into address space (kernel_flag is no longer mapped, don't
-       ; re-order this)
+       ; map task into address space
        ; preserves x
         jsr map_process_always
 
@@ -206,29 +204,22 @@ interrupt_handler:
 
        jsr map_save
 
-       lda 0           ; save address 0 contents for checking
-
-       ; preserves registers
-       jsr map_kernel
-       ;
-       ; kernel_flag is in the kernel map so we need to map early, we
-       ; need to map anyway for trap_signal
-       ;
        ldb U_DATA__U_INSYS     ; In a system call ?
        bne in_kernel
 
         ; we're not in kernel mode, check for signals and fault
+       lda 0           ; save address 0 contents for checking
         cmpa #0x7E             ; JMP at 0
        beq nofault
-       jsr map_process_always ; map the process
        lda #0x7E               ; put it back
        sta 0           ; write
-       jsr map_kernel  ; restore the map
+       jsr map_kernel
        ldx #11         ; SIGSEGV
        jsr trap_signal ; signal the user with a fault
 
 nofault:
 in_kernel:
+        jsr map_kernel
         ; set inint to true
         lda #1
         sta _inint