z80thunked: Fix some more bugs

- Interrupt return to kernel must restore the saved low page or an interrupt
  during a user copy explodes
- System call and interrupt entry routines must be high

diff --git a/Kernel/lowlevel-z80-thunked.s b/Kernel/lowlevel-z80-thunked.s
index 9f8097c..b131703 100644 (file)
--- a/Kernel/lowlevel-z80-thunked.s
+++ b/Kernel/lowlevel-z80-thunked.s
@@ -85,9 +85,9 @@ _doexec:
        ld sp,hl
        ex de,hl
        ld iy,#PROGLOAD
+       ld a,(U_DATA__U_PAGE+1) ; pass high page to trampoline
        jp _platform_doexec     ; jump into the low memory stub
 
-       .area _CODE
 ;
 ;      This is the entry point from the platform wrapper. When we hit this
 ;      our stack is above 32K and the upper 32K of kernel space is mapped
@@ -193,6 +193,7 @@ traphl:
         call outstring
         call _platform_monitor
 
+       .area _HIGH
 ;
 ;      The stub caller has already saved AF DE HL, mapped the kernel high
 ;      and switched to the istack as well as saving the old sp in
@@ -255,6 +256,7 @@ intret:
        ret
 
 interrupt_kernel:
+       call map_restore_low
        xor a
        ld e,a
        jr intret