lowlevel-z80: add hooking points for Z80 systems with memory protect bits

diff --git a/Kernel/lowlevel-z80.s b/Kernel/lowlevel-z80.s
index 5825da7..44dfc14 100644 (file)
--- a/Kernel/lowlevel-z80.s
+++ b/Kernel/lowlevel-z80.s
@@ -48,6 +48,8 @@
        .globl _out
        .globl _in
 
+       .globl mmu_irq_ret
+
         ; imported symbols
         .globl _trap_monitor
         .globl _unix_syscall
@@ -108,6 +110,9 @@ deliver_signals_2:
 
        ex de, hl
        ei
+       .ifne Z80_MMU_HOOKS
+       call mmu_user           ; must preserve HL
+       .endif
        jp (hl)         ; return to user space. This will then return via
                        ; the return path handler passed in BC
 
@@ -117,6 +122,9 @@ deliver_signals_2:
 signal_return:
        pop hl          ; argument
        di
+       .ifne Z80_MMU_HOOKS
+       call mmu_kernel
+       .endif
        ;
        ;       We must keep IRQ disabled in the kernel mapped
        ;       element of this processing, as we don't want to
@@ -141,8 +149,8 @@ unix_syscall_entry:
         push af
         ex af, af'
         exx
-        push bc
-        push de
+        push bc                ; FIXME we don't I tihnk need to save bc/de/hl
+        push de                ; as they are compiler caller save
         push hl
         exx
         push bc
@@ -150,10 +158,13 @@ unix_syscall_entry:
         push ix
         push iy
        ; We don't save AF or HL
-
         ; locate function call arguments on the userspace stack
         ld hl, #18     ; 16 bytes machine state, plus 2 bytes return address
         add hl, sp
+
+       .ifne Z80_MMU_HOOKS
+       call mmu_kernel         ; must preserve HL
+       .endif
         ; save system call number
         ld a, (hl)
         ld (U_DATA__U_CALLNO), a
@@ -163,7 +174,7 @@ unix_syscall_entry:
         ; copy arguments to common memory
         ld bc, #8      ; four 16-bit values
         ld de, #U_DATA__U_ARGN
-        ldir           ; copy
+        ldir           ; copy  FIXME use LDI x 8
 
        ld a, #1
        ld (U_DATA__U_INSYS), a
@@ -227,13 +238,14 @@ not_error:
        ; Undo the stacking and go back to user space
        ;
 unix_pop:
+       .ifne Z80_MMU_HOOKS
+       call mmu_user           ; must preserve HL
+       .endif
         ; restore machine state
         pop iy
         pop ix
-        ; pop hl ;; WRS: skip this!
         pop de
         pop bc
-        ; pop af ;; WRS: skip this!
         exx
         pop hl
         pop de
@@ -286,6 +298,9 @@ _doexec:
 
        ; for the relocation engine - tell it where it is
        ld iy, #PROGLOAD
+       .ifne Z80_MMU_HOOKS
+       call mmu_user           ; must preserve HL
+       .endif
         ei
         jp (hl)
 
@@ -299,6 +314,8 @@ null_handler:
        ld a, (U_DATA__U_INSYS)
        or a
        jp nz, trap_illegal
+       ld a, (_inint)
+       jp nz, trap_illegal
        ; user is merely not good
        ld hl, #7
        push hl
@@ -308,12 +325,12 @@ null_handler:
        push hl
        ld hl, #39              ; signal (getpid(), SIGBUS)
        push hl
-       rst #0x30               ; syscall
+       call unix_syscall_entry         ; syscall
        ld hl, #0xFFFF
        push hl
        dec hl                  ; #0
        push hl
-       rst #0x30               ; exit
+       call unix_syscall_entry
 
 
 
@@ -333,6 +350,9 @@ nmimsg: .ascii "[NMI]"
         .db 13,10,0
 
 nmi_handler:
+       .ifne Z80_MMU_HOOKS
+       call mmu_kernel
+       .endif
        call map_kernel
         ld hl, #nmimsg
         call outstring
@@ -359,6 +379,15 @@ interrupt_handler:
         push hl
         push ix
         push iy
+       ;
+       ; This is a bit exciting - if our MMU enforces r/o then the entire
+       ; stack state might be bogus!
+       ;
+       .ifne Z80_MMU_HOOKS
+       ld hl, #mmu_irq_ret
+       jp mmu_kernel_irq
+       .endif
+mmu_irq_ret:
 
        ; Some platforms (MSX for example) have devices we *must*
        ; service irrespective of kernel state in order to shut them
@@ -441,6 +470,9 @@ intret:
        ; of the handler so ensure everything is fixed before this !
 
        call deliver_signals
+       .ifne Z80_MMU_HOOKS
+       call mmu_restore_irq
+       .endif
 
        ; Then unstack and go.
 interrupt_pop:
@@ -471,6 +503,7 @@ null_pointer_trap:
 trap_signal:
        push hl
        ld hl, (U_DATA__U_PTAB);
+       push hl
         call _ssig
         pop hl
         pop hl
@@ -548,6 +581,9 @@ intret2:call map_kernel
        ;
        ; pop the stack and go
        ;
+       .ifne Z80_MMU_HOOKS
+       call mmu_user
+       .endif
        jr interrupt_pop
 
 ;