Remove the last vestigal remains of the simulated software interrupt

register, or "ssir".  The NetBSD kernel long ago adopted a software
interrupt thread model along with a "fast software interrupts" mechanism
that m68k platforms do not (yet) implement, but a few m68k platforms
were still consuling an "ssir" variable in the return from every exception
that nothing ever set.

This cleanup paves the way for futher consolidation of m68k trap handling
code in future commits.

Author: thorpej

sys/arch/atari/atari/intr.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: intr.c,v 1.34 2026/03/13 21:13:45 andvar Exp $	*/
+/*	$NetBSD: intr.c,v 1.35 2026/03/18 04:08:38 thorpej Exp $	*/
 
 /*-
  * Copyright (c) 1996 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: intr.c,v 1.34 2026/03/13 21:13:45 andvar Exp $");
+__KERNEL_RCSID(0, "$NetBSD: intr.c,v 1.35 2026/03/18 04:08:38 thorpej Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -54,7 +54,6 @@ typedef LIST_HEAD(, intrhand) ih_list_t;
 static ih_list_t autovec_list[AVEC_MAX - AVEC_MIN + 1];
 static ih_list_t uservec_list[UVEC_MAX - UVEC_MIN + 1];
 volatile unsigned int intr_depth;
-volatile int ssir;
 
 void
 intr_init(void)

sys/arch/atari/atari/locore.s

@@ -1,4 +1,4 @@
-/*	$NetBSD: locore.s,v 1.129 2026/03/14 21:03:39 thorpej Exp $	*/
+/*	$NetBSD: locore.s,v 1.130 2026/03/18 04:08:38 thorpej Exp $	*/
 
 /*
  * Copyright (c) 1988 University of Utah.
@@ -619,10 +619,10 @@ ASENTRY_NOPROFILE(rei)
 	jne	Ldorte			|  yes, do not make matters worse
 #endif
 	tstl	_C_LABEL(astpending)	|  AST pending?
-	jeq	Lchksir			|  no, go check for SIR
+	jeq	Ldorte			|  Nope. Just return.
 Lrei1:
 	btst	#5,%sp@			|  yes, are we returning to user mode?
-	jne	Lchksir			|  no, go check for SIR
+	jne	Ldorte			|  Nope. Just return.
 	movw	#PSL_LOWIPL,%sr		|  lower SPL
 	clrl	%sp@-			|  stack adjust
 	moveml	#0xFFFF,%sp@-		|  save all registers
@@ -651,38 +651,8 @@ Laststkadj:
 	movl	%a0,%sp@(FR_SP)		|  new SSP
 	moveml	%sp@+,#0x7FFF		|  restore user registers
 	movl	%sp@,%sp		|  and our SP
-	rte				|  and do real RTE
-Lchksir:
-	tstb	_C_LABEL(ssir)		|  SIR pending?
-	jeq	Ldorte			|  no, all done
-	movl	%d0,%sp@-		|  need a scratch register
-	movw	%sp@(4),%d0		|  get SR
-	andw	#PSL_IPL7,%d0		|  mask all but IPL
-	jne	Lnosir			|  came from interrupt, no can do
-	movl	%sp@+,%d0		|  restore scratch register
-Lgotsir:
-	movw	#SPL1,%sr		|  prevent others from servicing int
-	tstb	_C_LABEL(ssir)		|  too late?
-	jeq	Ldorte			|  yes, oh well...
-	clrl	%sp@-			|  stack adjust
-	moveml	#0xFFFF,%sp@-		|  save all registers
-	movl	%usp,%a1		|  including
-	movl	%a1,%sp@(FR_SP)		|     the users SP
-	clrl	%sp@-			|  VA == none
-	clrl	%sp@-			|  code == none
-	movl	#T_SSIR,%sp@-		|  type == software interrupt
-	pea	%sp@(12)		|  fp == address of trap frame
-	jbsr	_C_LABEL(trap)		|  go handle it
-	lea	%sp@(16),%sp		|  pop value args
-	movl	%sp@(FR_SP),%a0		|  restore
-	movl	%a0,%usp		|    user SP
-	moveml	%sp@+,#0x7FFF		|  and all remaining registers
-	addql	#8,%sp			|  pop SP and stack adjust
-	rte
-Lnosir:
-	movl	%sp@+,%d0		|  restore scratch register
 Ldorte:
-	rte				|  real return
+	rte				|  and do real RTE
 
 /*
  * Initialization
@@ -941,26 +911,6 @@ ENTRY(probeva)
 	.word	0x4e7a,0x0805		|  movec  MMUSR,d0
 	rts
 
-/*
- * Set processor priority level calls.  Most are implemented with
- * inline asm expansions.  However, spl0 requires special handling
- * as we need to check for our emulated software interrupts.
- */
-
-ENTRY(spl0)
-	moveq	#0,%d0
-	movw	%sr,%d0			|  get old SR for return
-	movw	#PSL_LOWIPL,%sr		|  restore new SR
-	tstb	_C_LABEL(ssir)		|  software interrupt pending?
-	jeq	Lspldone		|  no, all done
-	subql	#4,%sp			|  make room for RTE frame
-	movl	%sp@(4),%sp@(2)		|  position return address
-	clrw	%sp@(6)			|  set frame type 0
-	movw	#PSL_LOWIPL,%sp@	|  and new SR
-	jra	Lgotsir			|  go handle it
-Lspldone:
-	rts
-
 /*
  * Handle the nitty-gritty of rebooting the machine.
  *

sys/arch/atari/include/intr.h

@@ -1,4 +1,4 @@
-/*	$NetBSD: intr.h,v 1.25 2024/01/19 20:55:42 thorpej Exp $	*/
+/*	$NetBSD: intr.h,v 1.26 2026/03/18 04:08:38 thorpej Exp $	*/
 
 /*-
  * Copyright (c) 1996, 1997, 2007 The NetBSD Foundation, Inc.
@@ -59,20 +59,17 @@ typedef struct {
  */
 #include <machine/psl.h>
 
-/* spl0 requires checking for software interrupts */
-
 #define splsoftclock()		splraise1()
 #define splsoftbio()		splraise1()
 #define splsoftnet()		splraise1()
 #define splsoftserial()		splraise1()
 #define splvm()			splraise4()
 #define splsched()		splraise6()
 #define splhigh()		spl7()
-#define splx(s)			((s) & PSL_IPL ? _spl(s) : spl0())
+#define	spl0()			_spl0()
+#define	splx(s)			_splx(s)
 
 #ifdef _KERNEL
-int spl0(void);
-
 extern const uint16_t ipl2psl_table[NIPL];
 extern volatile unsigned int intr_depth;
 

sys/arch/cesfic/cesfic/locore.s

@@ -1,4 +1,4 @@
-/*	$NetBSD: locore.s,v 1.53 2026/03/14 21:03:39 thorpej Exp $	*/
+/*	$NetBSD: locore.s,v 1.54 2026/03/18 04:08:38 thorpej Exp $	*/
 
 /*
  * Copyright (c) 1980, 1990, 1993
@@ -371,7 +371,7 @@ Lmainreturned:
 
 /*
  * Trap/interrupt vector routines
- */ 
+ */
 #include <m68k/m68k/trap_subr.s>
 
 /*
@@ -467,21 +467,15 @@ ENTRY_NOPROFILE(badtrap)
 ENTRY_NOPROFILE(trap0)
 	clrl	%sp@-			| stack adjust count
 	moveml	#0xFFFF,%sp@-		| save user registers
-	movl	%usp,%a0			| save the user SP
+	movl	%usp,%a0		| save the user SP
 	movl	%a0,%sp@(FR_SP)		|   in the savearea
-	movl	%d0,%sp@-			| push syscall number
+	movl	%d0,%sp@-		| push syscall number
 	jbsr	_C_LABEL(syscall)	| handle it
 	addql	#4,%sp			| pop syscall arg
 	tstl	_C_LABEL(astpending)
 	jne	Lrei2
-	tstb	_C_LABEL(ssir)
-	jeq	Ltrap1
-	movw	#SPL1,%sr
-	tstb	_C_LABEL(ssir)
-	jne	Lsir1
-Ltrap1:	
 	movl	%sp@(FR_SP),%a0		| grab and restore
-	movl	%a0,%usp			|   user SP
+	movl	%a0,%usp		|   user SP
 	moveml	%sp@+,#0x7FFF		| restore most registers
 	addql	#8,%sp			| pop SP and stack adjust
 	rte
@@ -635,18 +629,16 @@ ENTRY_NOPROFILE(lev7intr)	/* level 7: parity errors, reset key */
  * This code is complicated by the fact that sendsig may have been called
  * necessitating a stack cleanup.
  */
-BSS(ssir,1)
-
 ASENTRY_NOPROFILE(rei)
 	tstl	_C_LABEL(astpending)	| AST pending?
-	jeq	Lchksir			| no, go check for SIR
+	jeq	Ldorte			| Nope. Just return.
 Lrei1:
-	btst	#5,%sp@			| yes, are we returning to user mode?
-	jne	Lchksir			| no, go check for SIR
+	btst	#5,%sp@			| Are we returning to user mode?
+	jne	Ldorte			| Nope. Just return.
 	movw	#PSL_LOWIPL,%sr		| lower SPL
 	clrl	%sp@-			| stack adjust
 	moveml	#0xFFFF,%sp@-		| save all registers
-	movl	%usp,%a1			| including
+	movl	%usp,%a1		| including
 	movl	%a1,%sp@(FR_SP)		|    the users SP
 Lrei2:
 	clrl	%sp@-			| VA == none
@@ -672,39 +664,8 @@ Laststkadj:
 	movl	%a0,%sp@(FR_SP)		| new SSP
 	moveml	%sp@+,#0x7FFF		| restore user registers
 	movl	%sp@,%sp			| and our SP
-	rte				| and do real RTE
-Lchksir:
-	tstb	_C_LABEL(ssir)		| SIR pending?
-	jeq	Ldorte			| no, all done
-	movl	%d0,%sp@-			| need a scratch register
-	movw	%sp@(4),%d0		| get SR
-	andw	#PSL_IPL7,%d0		| mask all but IPL
-	jne	Lnosir			| came from interrupt, no can do
-	movl	%sp@+,%d0			| restore scratch register
-Lgotsir:
-	movw	#SPL1,%sr		| prevent others from servicing int
-	tstb	_C_LABEL(ssir)		| too late?
-	jeq	Ldorte			| yes, oh well...
-	clrl	%sp@-			| stack adjust
-	moveml	#0xFFFF,%sp@-		| save all registers
-	movl	%usp,%a1			| including
-	movl	%a1,%sp@(FR_SP)		|    the users SP
-Lsir1:	
-	clrl	%sp@-			| VA == none
-	clrl	%sp@-			| code == none
-	movl	#T_SSIR,%sp@-		| type == software interrupt
-	pea	%sp@(12)		| fp == address of trap frame
-	jbsr	_C_LABEL(trap)		| go handle it
-	lea	%sp@(16),%sp		| pop value args
-	movl	%sp@(FR_SP),%a0		| restore
-	movl	%a0,%usp			|   user SP
-	moveml	%sp@+,#0x7FFF		| and all remaining registers
-	addql	#8,%sp			| pop SP and stack adjust
-	rte
-Lnosir:
-	movl	%sp@+,%d0			| restore scratch register
 Ldorte:
-	rte				| real return
+	rte				| and do real RTE
 
 /*
  * Primitives
@@ -745,26 +706,6 @@ Lsldone:
 	rts
 #endif
 
-/*
- * Set processor priority level calls.  Most are implemented with
- * inline asm expansions.  However, spl0 requires special handling
- * as we need to check for our emulated software interrupts.
- */
-
-ENTRY(spl0)
-	moveq	#0,%d0
-	movw	%sr,%d0			| get old SR for return
-	movw	#PSL_LOWIPL,%sr		| restore new SR
-	tstb	_C_LABEL(ssir)		| software interrupt pending?
-	jeq	Lspldone		| no, all done
-	subql	#4,%sp			| make room for RTE frame
-	movl	%sp@(4),%sp@(2)		| position return address
-	clrw	%sp@(6)			| set frame type 0
-	movw	#PSL_LOWIPL,%sp@		| and new SR
-	jra	Lgotsir			| go handle it
-Lspldone:
-	rts
-
 /*
  * _delay(u_int N)
  *

sys/arch/mac68k/include/intr.h

@@ -1,4 +1,4 @@
-/*	$NetBSD: intr.h,v 1.33 2024/02/28 13:05:40 thorpej Exp $	*/
+/*	$NetBSD: intr.h,v 1.34 2026/03/18 04:08:38 thorpej Exp $	*/
 
 /*
  * Copyright (C) 1997 Scott Reynolds
@@ -40,8 +40,6 @@ typedef struct {
 
 #ifdef _KERNEL
 
-/* spl0 requires checking for software interrupts */
-
 #define	IPL_NONE	0
 #define	IPL_SOFTCLOCK	1
 #define	IPL_SOFTBIO	2
@@ -68,8 +66,8 @@ extern uint16_t ipl2psl_table[NIPL];
  */
 
 /* watch out for side effects */
-#define splx(s)         ((s) & PSL_IPL ? _spl(s) : spl0())
-
+#define	spl0()		_spl0()
+#define	splx(s)		_splx(s)
 
 typedef int ipl_t;
 
@@ -95,9 +93,6 @@ void	intr_init(void);
 void	intr_establish(int (*)(void *), void *, int);
 void	intr_disestablish(int);
 void	intr_dispatch(struct clockframe);
-
-/* locore.s */
-int	spl0(void);
 #endif /* _KERNEL */
 
 #endif /* _MAC68K_INTR_H_ */

sys/arch/mac68k/mac68k/intr.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: intr.c,v 1.36 2024/02/28 13:05:40 thorpej Exp $	*/
+/*	$NetBSD: intr.c,v 1.37 2026/03/18 04:08:38 thorpej Exp $	*/
 
 /*-
  * Copyright (c) 1996, 1997 The NetBSD Foundation, Inc.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: intr.c,v 1.36 2024/02/28 13:05:40 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: intr.c,v 1.37 2026/03/18 04:08:38 thorpej Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -84,7 +84,6 @@ int	intr_debug = 0;
  */
 uint16_t ipl2psl_table[NIPL];
 volatile unsigned int intr_depth;
-volatile int ssir;
 
 extern	u_int intrcnt[];	/* from locore.s */