From 3dc4b63048cdc4a84aa83bfb9b09fd751fb9d077 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Mon, 27 Jul 1992 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1992-07-27

---
 ss/dat.h  |  1 +
 ss/l.s    | 17 +++++------------
 ss/main.c | 14 +++++++++++---
 ss/trap.c | 30 ++++++++++++++++++++++++++++--
 4 files changed, 45 insertions(+), 17 deletions(-)

diff --git a/ss/dat.h b/ss/dat.h
index 50fca1904f541186212b2e3bf57c5340dbe48434..8d5d9f94897747dee07bb12fc1c979c46c08f3de 100644
--- a/ss/dat.h
+++ b/ss/dat.h
@@ -193,6 +193,7 @@ extern register Mach	*m;		/* R6 */
 extern register User	*u;		/* R5 */
 
 extern	uchar	*intrreg;
+extern	FPsave	*initfpp;
 
 struct
 {
diff --git a/ss/l.s b/ss/l.s
index e83ecbe0d67e1c41d62e9dc77f209baccf36371a..7b4e534b89c57e48dff47615326bbef27391cf3e 100644
--- a/ss/l.s
+++ b/ss/l.s
@@ -468,15 +468,10 @@ TEXT	putsegm(SB), $0
 	MOVW	R8, (R7, 3)
 	RETURN
 
-/*
- * in savefpregs and restfpregs, incoming R7 points to doubleword
- * below where F0 will go; doubleword align in and backfill FSR
- */
 TEXT	savefpregs(SB), $0
 
-	ADD	$8, R7
-	ANDN	$7, R7		/* now MOVD-aligned */
-	MOVW	FSR, -4(R7)
+	MOVW	FSR, 0(R7)
+	ADD	$4, R7
 
 	MOVD	F0, (0*4)(R7)
 	MOVD	F2, (2*4)(R7)
@@ -520,11 +515,9 @@ TEXT	restfpregs(SB), $0
 	OR	$PSREF, R8
 	MOVW	R8, PSR
 
-	ADD	$8, R7
-	ANDN	$7, R7		/* now MOVD-aligned */
-	OR	R0, R0
-
-	MOVW	-4(R7), FSR
+	NOOP			/* wait for PSR to quiesce */
+	MOVW	0(R7), FSR
+	ADD	$4, R7
 
 	MOVD	(0*4)(R7), F0
 	MOVD	(2*4)(R7), F2
diff --git a/ss/main.c b/ss/main.c
index 6bac384bb62023e8989e844f999c0652dc58c33b..c1881f40d5a13b973cd910f090e10c093c22325e 100644
--- a/ss/main.c
+++ b/ss/main.c
@@ -35,6 +35,7 @@ main(void)
 	initseg();
 	chandevreset();
 	streaminit();
+	swapinit();
 	userinit();
 	clockinit();
 	schedinit();
@@ -112,7 +113,8 @@ init0(void)
 	touser(USTKTOP-(1+MAXSYSARG)*BY2WD);
 }
 
-FPsave	initfp;
+FPsave	*initfpp;
+uchar	initfpa[sizeof(FPsave)+7];
 
 void
 userinit(void)
@@ -121,6 +123,7 @@ userinit(void)
 	Segment *s;
 	User *up;
 	KMap *k;
+	ulong l;
 
 	p = newproc();
 	p->pgrp = newpgrp();
@@ -132,8 +135,13 @@ userinit(void)
 
 	strcpy(p->text, "*init*");
 	strcpy(p->user, eve);
-	savefpregs(&initfp);
-/*	initfp.fsr |= 0x1E << 23;	/* trap on all but INEXACT */
+	/* must align initfpp to an ODD word boundary */
+	l = (ulong)initfpa;
+	l += 3;
+	l &= ~7;
+	l += 4;
+	initfpp = (FPsave*)l;
+	savefpregs(initfpp);
 	p->fpstate = FPinit;
 
 	/*
diff --git a/ss/trap.c b/ss/trap.c
index 44752d328f22718411cb350218ed2d1fe6f9708b..7dcac7818a1f537921d7fb4b0134e07e65f019a0 100644
--- a/ss/trap.c
+++ b/ss/trap.c
@@ -95,6 +95,29 @@ excname(ulong tbr)
 	return excbuf;
 }
 
+/*
+ * This routine is frightening.  See comment in fptrap.c
+ */
+void
+fpquiet(void)
+{
+	int i;
+	ulong fsr;
+
+	i = 0;
+	fsr = getfsr();
+	while(fsr & (1<<13)){
+		if(fsr & 0x1F){
+			print("trap in fpquiet\n");
+			break;
+		}
+		if(++i > 1000){
+			print("fp not quiescent\n");
+			break;
+		}
+	}
+}
+
 void
 trap(Ureg *ur)
 {
@@ -111,7 +134,8 @@ trap(Ureg *ur)
 	tbr = (ur->tbr&0xFFF)>>4;
 	if(tbr > 16){			/* interrupt */
 		if(u && u->p->state==Running){
-			if(u->p->fpstate == FPactive) {
+			if(u->p->fpstate == FPactive){
+				fpquiet();
 				savefpregs(&u->fpsave);
 				u->p->fpstate = FPinactive;
 				ur->psr &= ~PSREF;
@@ -138,6 +162,7 @@ trap(Ureg *ur)
 		case 1:				/* instr. access */
 		case 9:				/* data access */
 			if(u && u->p->fpstate==FPactive) {
+				fpquiet();
 				savefpregs(&u->fpsave);
 				u->p->fpstate = FPinactive;
 				ur->psr &= ~PSREF;
@@ -161,7 +186,7 @@ trap(Ureg *ur)
 		case 4:				/* floating point disabled */
 			if(u && u->p){
 				if(u->p->fpstate == FPinit)
-					restfpregs(&initfp);
+					restfpregs(initfpp);
 				else if(u->p->fpstate == FPinactive)
 					restfpregs(&u->fpsave);
 				else
@@ -514,6 +539,7 @@ syscall(Ureg *aur)
 	 * guarantee anything about registers,
 	 */
 	if(u->p->fpstate == FPactive) {
+		fpquiet();
 		u->p->fpstate = FPinit;
 		ur->psr &= ~PSREF;
 	}