Make context switching much more MI:

 - Move the functionality of choosing a process from cpu_switch into
   a much simpler function: cpu_switchto. Instead of having the locore
   code walk the run queues, let the MI code choose the process we
   want to run and only implement the context switching itself in MD
   code.
 - Let MD context switching run without worrying about spls or locks.
 - Instead of having the idle loop implemented with special contexts
   in MD code, implement one idle proc for each cpu. make the idle
   loop MI with MD hooks.
 - Change the proc lists from the old style vax queues to TAILQs.
 - Change the sleep queue from vax queues to TAILQs. This makes
   wakeup() go from O(n^2) to O(n)

there will be some MD fallout, but it will be fixed shortly.
There's also a few cleanups to be done after this.

deraadt@, kettenis@ ok

2 files changed, 19 insertions, 97 deletions

diff --git a/sys/arch/mvme68k/mvme68k/locore.s b/sys/arch/mvme68k/mvme68k/locore.s
index 38015370541..c92d4fb2978 100644
--- a/sys/arch/mvme68k/mvme68k/locore.s
+++ b/sys/arch/mvme68k/mvme68k/locore.s
@@ -1,4 +1,4 @@
-/*	$OpenBSD: locore.s,v 1.54 2007/05/15 13:46:22 martin Exp $ */
+/*	$OpenBSD: locore.s,v 1.55 2007/10/10 15:53:52 art Exp $ */
 
 /*
  * Copyright (c) 1995 Theo de Raadt
@@ -1165,51 +1165,18 @@ Ldorte:
  */
 #include <m68k/m68k/support.s>
 
-/*
- * Use common m68k process manipulation routines.
- */
-#include <m68k/m68k/proc_subr.s>
-
 	.data
 GLOBAL(curpcb)
 	.long	0
 
 ASBSS(nullpcb,SIZEOF_PCB)
 
-/*
- * At exit of a process, do a switch for the last time.
- * Switch to a safe stack and PCB, and deallocate the process's resources.
- */
-ENTRY(switch_exit)
-	movl	sp@(4),a0
-	| save state into garbage pcb
-	movl	#_ASM_LABEL(nullpcb),_C_LABEL(curpcb)
-	lea	_ASM_LABEL(tmpstk),sp	| goto a tmp stack
-
-        /* Schedule the vmspace and stack to be freed. */
-	movl    a0,sp@-                 | exit2(p)
-	jbsr    _C_LABEL(exit2)
-	lea     sp@(4),sp               | pop args
-
-	jra	_C_LABEL(cpu_switch)
-
-/*
- * When no processes are on the runq, Swtch branches to Idle
- * to wait for something to come ready.
- */
-ASENTRY_NOPROFILE(Idle)
+ENTRY_NOPROFILE(cpu_idle_cycle)
 	stop	#PSL_LOWIPL
-	movw	#PSL_HIGHIPL,sr
-	movl	_C_LABEL(whichqs),d0
-	jeq	_ASM_LABEL(Idle)
-	jra	Lsw1
-
-Lbadsw:
-	PANIC("switch")
-	/*NOTREACHED*/
+	rts
 
 /*
- * cpu_switch()
+ * cpu_switchto(struct proc *oldproc, struct proc *newproc)
  *
  * NOTE: On the mc68851 we attempt to avoid flushing the
  * entire ATC.  The effort involved in selective flushing may not be
@@ -1219,55 +1186,15 @@ Lbadsw:
  * user's PTEs have been changed (formerly denoted by the SPTECHG p_flag
  * bit).  For now, we just always flush the full ATC.
  */
-ENTRY(cpu_switch)
-	movl	_C_LABEL(curpcb),a0	| current pcb
-	movw	sr,a0@(PCB_PS)		| save sr before changing ipl
-#ifdef notyet
-	movl	CURPROC,sp@-		| remember last proc running
-#endif
-	clrl	CURPROC
+ENTRY(cpu_switchto)
+	movl	sp@(4), d0		| oldproc
+	beq	Lswnofpsave		| is NULL, don't save anything
 
 	/*
-	 * Find the highest-priority queue that isn't empty,
-	 * then take the first proc from that queue.
-	 */
-	movw	#PSL_HIGHIPL,sr		| lock out interrupts
-	movl	_C_LABEL(whichqs),d0
-	jeq	_ASM_LABEL(Idle)
-Lsw1:
-	movl	d0,d1
-	negl	d0
-	andl	d1,d0
-	bfffo	d0{#0:#32},d1
-	eorib	#31,d1
-
-	movl	d1,d0
-	lslb	#3,d1			| convert queue number to index
-	addl	#_C_LABEL(qs),d1	| locate queue (q)
-	movl	d1,a1
-	movl	a1@(P_FORW),a0		| p = q->p_forw
-	cmpal	d1,a0			| anyone on queue?
-	jeq	Lbadsw			| no, panic
-	movl	a0@(P_FORW),a1@(P_FORW)	| q->p_forw = p->p_forw
-	movl	a0@(P_FORW),a1		| n = p->p_forw
-	movl	d1,a1@(P_BACK)		| n->p_back = q
-	cmpal	d1,a1			| anyone left on queue?
-	jne	Lsw2			| yes, skip
-	movl	_C_LABEL(whichqs),d1
-	bclr	d0,d1			| no, clear bit
-	movl	d1,_C_LABEL(whichqs)
-Lsw2:
-	movl	a0,CURPROC
-	clrl	_C_LABEL(want_resched)
-#ifdef notyet
-	movl	sp@+,a1
-	cmpl	a0,a1			| switching to same proc?
-	jeq	Lswdone			| yes, skip save and restore
-#endif
-	/*
 	 * Save state of previous process in its pcb.
 	 */
         movl	_C_LABEL(curpcb),a1
+	movw	sr, a1@(PCB_PS)		| save sr before switching context
 	moveml	#0xFCFC,a1@(PCB_REGS)	| save non-scratch registers
 	movl	usp,a2			| grab USP (a2 has been saved)
 	movl	a2,a1@(PCB_USP)		| and save it
@@ -1295,15 +1222,12 @@ Lsavfp60:
 	fmovem	fpsr,a2@(FPF_FPSR)
 	fmovem	fpi,a2@(FPF_FPI)
 #endif /* M68060 */
+
 Lswnofpsave:
-#ifdef DIAGNOSTIC
-	tstl	a0@(P_WCHAN)
-	jne	Lbadsw
-	cmpb	#SRUN,a0@(P_STAT)
-	jne	Lbadsw
-#endif
+	movl	sp@(8), a0		| newproc
+
+	movl	a0, CURPROC
 	movb	#SONPROC,a0@(P_STAT)
-	clrl	a0@(P_BACK)		| clear back link
 	movl	a0@(P_ADDR),a1		| get p_addr
 	movl	a1,_C_LABEL(curpcb)
 
diff --git a/sys/arch/mvme68k/mvme68k/vm_machdep.c b/sys/arch/mvme68k/mvme68k/vm_machdep.c
index e8ac2262a05..df44535cfda 100644
--- a/sys/arch/mvme68k/mvme68k/vm_machdep.c
+++ b/sys/arch/mvme68k/mvme68k/vm_machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vm_machdep.c,v 1.45 2007/06/20 17:29:36 miod Exp $ */
+/*	$OpenBSD: vm_machdep.c,v 1.46 2007/10/10 15:53:52 art Exp $ */
 
 /*
  * Copyright (c) 1988 University of Utah.
@@ -117,20 +117,18 @@ cpu_fork(p1, p2, stack, stacksize, func, arg)
 
 /*
  * cpu_exit is called as the last action during exit.
- * We release the address space and machine-dependent resources,
- * including the memory for the user structure and kernel stack.
- * Once finished, we call switch_exit, which switches to a temporary
- * pcb and stack and never returns.  We block memory allocation
- * until switch_exit has made things safe again.
+ *
+ * Block context switches and then call switch_exit() which will
+ * switch to another process thus we never return.
  */
 void
 cpu_exit(p)
 	struct proc *p;
 {
+	(void)splhigh();
 
-	splhigh();
-	switch_exit(p);
-	/* NOTREACHED */
+	pmap_deactivate(p);
+	sched_exit(p);
 }
 
 /*