lowlevel-z80: further work on the interrupt changes

Fix up the logic for signals and interrupt paths

diff --git a/Kernel/lowlevel-z80.s b/Kernel/lowlevel-z80.s
index 58cc236..6e438b1 100644 (file)
--- a/Kernel/lowlevel-z80.s
+++ b/Kernel/lowlevel-z80.s
@@ -100,6 +100,9 @@ deliver_signals_2:
        ; Indicate processed
        xor a
        ld (U_DATA__U_CURSIG), a
+       ; and we will handle the signal with interrupts on so clear the
+       ; flag
+       ld (_int_disabled),a
 
        ; Semantics for now: signal delivery clears handler
        ld (hl), a
@@ -118,6 +121,7 @@ deliver_signals_2:
                        ; the return path handler passed in BC
 
 no_pending:
+       ld (_int_disabled),a    ; clear interrupt status
        ei
        .ifne Z80_MMU_HOOKS
        call mmu_user
@@ -129,8 +133,7 @@ no_pending:
 ;
 signal_return:
        pop hl          ; argument
-       di              ; Be careful as our internal irq state flag is
-                       ; kept wrong through this sequence.
+       di
        .ifne Z80_MMU_HOOKS
        call mmu_kernel
        .endif
@@ -141,6 +144,11 @@ signal_return:
        ;
        ld (U_DATA__U_SYSCALL_SP), sp
        ld sp, #kstack_top
+       ;
+       ;       Ensure chksigs and friends see the right status
+       ;
+       ld a,#1
+       ld (_int_disabled),a
        call map_kernel_di
        call _chksigs
        call map_process_always_di
@@ -162,7 +170,7 @@ unix_syscall_entry:
         ex af, af'
         exx
         push bc                ; FIXME we don't I think need to save bc/de/hl
-        push de                ; as they are compiler caller save
+        push de                ; as they are compiler caller save once we fix the API
         push hl
         exx
         push bc
@@ -440,6 +448,9 @@ mmu_irq_ret:
        ld (_inint), a
        ; So we know that this task should resume with IRQs off
        ld (U_DATA__U_ININTERRUPT), a
+       ; Load the interrupt flag properly. It got an implicit di from
+       ; the IRQ being taken
+       ld (_int_disabled),a
 
        call _platform_interrupt
 
@@ -484,6 +495,8 @@ intret:
 
        ; Then unstack and go.
 interrupt_pop:
+       xor a
+       ld (_int_disabled),a
         pop iy
         pop ix
         pop hl