commit c3459537577cb76e83a16e40f47c5e66f6277a22
Author: Russ Cox <rsc@golang.org>
Date:   Tue Mar 11 11:41:24 2025 -0400

    sys/src/9k: add monotonic time support
    
    Same as previous change in sys/src/9.

diff --git a/sys/src/9k/k10/syscall.c b/sys/src/9k/k10/syscall.c
index 519ad7f6..329906b8 100755
--- a/sys/src/9k/k10/syscall.c
+++ b/sys/src/9k/k10/syscall.c
@@ -226,7 +226,7 @@ syscall(int scallnr, Ureg* ureg)
 	startns = 0;
 
 	if(up->trace && (pt = proctrace) != nil)
-		pt(up, STrap, todget(nil), STrapSC|scallnr);
+		pt(up, STrap, todget(nil, nil), STrapSC|scallnr);
 
 	if(up->procctl == Proc_tracesyscall){
 		/*
@@ -245,7 +245,7 @@ syscall(int scallnr, Ureg* ureg)
 		if(up->syscalltrace)
 			free(up->syscalltrace);
 		up->syscalltrace = nil;
-		startns = todget(nil);
+		startns = todget(nil, nil);
 	}
 
 	if(scallnr == RFORK)
@@ -297,7 +297,7 @@ syscall(int scallnr, Ureg* ureg)
 	ureg->ax = ar0.p;
 
 	if(up->procctl == Proc_tracesyscall){
-		stopns = todget(nil);
+		stopns = todget(nil, nil);
 		up->procctl = Proc_stopme;
 		sysretfmt(scallnr, (va_list)(sp+BY2V), &ar0, startns, stopns);
 		s = splhi();
diff --git a/sys/src/9k/port/devcons.c b/sys/src/9k/port/devcons.c
index e6162d68..103e632f 100755
--- a/sys/src/9k/port/devcons.c
+++ b/sys/src/9k/port/devcons.c
@@ -1228,7 +1228,7 @@ rand(void)
 static uvlong uvorder = 0x0001020304050607ULL;
 
 static uchar*
-le2vlong(vlong *to, uchar *f)
+be2vlong(vlong *to, uchar *f)
 {
 	uchar *t, *o;
 	int i;
@@ -1241,7 +1241,7 @@ le2vlong(vlong *to, uchar *f)
 }
 
 static uchar*
-vlong2le(uchar *t, vlong from)
+vlong2be(uchar *t, vlong from)
 {
 	uchar *f, *o;
 	int i;
@@ -1256,7 +1256,7 @@ vlong2le(uchar *t, vlong from)
 static long order = 0x00010203;
 
 static uchar*
-le2long(long *to, uchar *f)
+be2long(long *to, uchar *f)
 {
 	uchar *t, *o;
 	int i;
@@ -1268,19 +1268,6 @@ le2long(long *to, uchar *f)
 	return f+sizeof(long);
 }
 
-static uchar*
-long2le(uchar *t, long from)
-{
-	uchar *f, *o;
-	int i;
-
-	f = (uchar*)&from;
-	o = (uchar*)&order;
-	for(i = 0; i < sizeof(long); i++)
-		t[i] = f[o[i]];
-	return t+sizeof(long);
-}
-
 char *Ebadtimectl = "bad time control";
 
 /*
@@ -1291,19 +1278,20 @@ char *Ebadtimectl = "bad time control";
 static int
 readtime(ulong off, char *buf, int n)
 {
-	vlong nsec, ticks;
+	vlong nsec, ticks, mono;
 	long sec;
-	char str[7*NUMSIZE];
+	char str[9*NUMSIZE];
 
-	nsec = todget(&ticks);
+	nsec = todget(&ticks, &mono);
 	if(fasthz == 0LL)
 		fastticks((uvlong*)&fasthz);
 	sec = nsec/1000000000ULL;
-	snprint(str, sizeof(str), "%*lud %*llud %*llud %*llud ",
+	snprint(str, sizeof(str), "%*lud %*llud %*llud %*llud %*llud ",
 		NUMSIZE-1, sec,
 		VLNUMSIZE-1, nsec,
 		VLNUMSIZE-1, ticks,
-		VLNUMSIZE-1, fasthz);
+		VLNUMSIZE-1, fasthz,
+		VLNUMSIZE-1, mono);
 	return readstr(off, buf, n, str);
 }
 
@@ -1337,23 +1325,27 @@ static int
 readbintime(char *buf, int n)
 {
 	int i;
-	vlong nsec, ticks;
+	vlong nsec, ticks, mono;
 	uchar *b = (uchar*)buf;
 
 	i = 0;
 	if(fasthz == 0LL)
 		fastticks((uvlong*)&fasthz);
-	nsec = todget(&ticks);
+	nsec = todget(&ticks, &mono);
+	if(n >= 4*sizeof(uvlong)){
+		vlong2be(b+3*sizeof(uvlong), mono);
+		i += sizeof(uvlong);
+	}
 	if(n >= 3*sizeof(uvlong)){
-		vlong2le(b+2*sizeof(uvlong), fasthz);
+		vlong2be(b+2*sizeof(uvlong), fasthz);
 		i += sizeof(uvlong);
 	}
 	if(n >= 2*sizeof(uvlong)){
-		vlong2le(b+sizeof(uvlong), ticks);
+		vlong2be(b+sizeof(uvlong), ticks);
 		i += sizeof(uvlong);
 	}
 	if(n >= 8){
-		vlong2le(b, nsec);
+		vlong2be(b, nsec);
 		i += sizeof(vlong);
 	}
 	return i;
@@ -1378,20 +1370,20 @@ writebintime(char *buf, int n)
 	case 'n':
 		if(n < sizeof(vlong))
 			error(Ebadtimectl);
-		le2vlong(&delta, p);
+		be2vlong(&delta, p);
 		todset(delta, 0, 0);
 		break;
 	case 'd':
 		if(n < sizeof(vlong)+sizeof(long))
 			error(Ebadtimectl);
-		p = le2vlong(&delta, p);
-		le2long(&period, p);
+		p = be2vlong(&delta, p);
+		be2long(&period, p);
 		todset(-1, delta, period);
 		break;
 	case 'f':
 		if(n < sizeof(uvlong))
 			error(Ebadtimectl);
-		le2vlong(&fasthz, p);
+		be2vlong(&fasthz, p);
 		todsetfreq(fasthz);
 		break;
 	}
diff --git a/sys/src/9k/port/devproc.c b/sys/src/9k/port/devproc.c
index c64e8eb2..46d02926 100755
--- a/sys/src/9k/port/devproc.c
+++ b/sys/src/9k/port/devproc.c
@@ -280,7 +280,7 @@ _proctrace(Proc* p, Tevent etype, vlong ts, vlong)
 	te->pid = p->pid;
 	te->etype = etype;
 	if (ts == 0)
-		te->time = todget(nil);
+		te->time = todget(nil, nil);
 	else
 		te->time = ts;
 	tproduced++;
diff --git a/sys/src/9k/port/devptrace.c b/sys/src/9k/port/devptrace.c
index ebfd5e0f..ccfd1cc1 100755
--- a/sys/src/9k/port/devptrace.c
+++ b/sys/src/9k/port/devptrace.c
@@ -65,7 +65,7 @@ _ptrace(Proc *p, int etype, vlong ts, vlong arg)
 		return;
 	}
 	if(ts == 0)
-		ts = todget(nil);
+		ts = todget(nil, nil);
 	i = (tproduced&ntmask) * PTsize;
 	te = &tevents[i];
 	PBIT32(te, (int)p->pid);
diff --git a/sys/src/9k/port/edf.c b/sys/src/9k/port/edf.c
index 7e785ba2..b6587b4c 100755
--- a/sys/src/9k/port/edf.c
+++ b/sys/src/9k/port/edf.c
@@ -198,7 +198,7 @@ release(Proc *p)
 		DPRINT("%lud release %d[%s], r=%lud, d=%lud, t=%lud, S=%lud\n",
 			now, p->pid, statename[p->state], e->r, e->d, e->t, e->S);
 		if(pt = proctrace){
-			nowns = todget(nil);
+			nowns = todget(nil, nil);
 			pt(p, SRelease, nowns, 0);
 			pt(p, SDeadline, nowns + 1000LL*e->D, 0);
 		}
@@ -327,7 +327,7 @@ edfrun(Proc *p, int edfpri)
 			DPRINT("v");
 		}
 		if(p->trace && (pt = proctrace))
-			pt(p, SInte, todget(nil) + e->tns, 0);
+			pt(p, SInte, todget(nil, nil) + e->tns, 0);
 		e->tmode = Trelative;
 		e->tf = deadlineintr;
 		e->ta = p;
diff --git a/sys/src/9k/port/portfns.h b/sys/src/9k/port/portfns.h
index 470edba5..8ae59771 100755
--- a/sys/src/9k/port/portfns.h
+++ b/sys/src/9k/port/portfns.h
@@ -329,7 +329,7 @@ void		timerset(uvlong);
 ulong		tk2ms(ulong);
 #define		TK2MS(x) ((x)*(1000/HZ))
 uvlong		tod2fastticks(vlong);
-vlong		todget(vlong*);
+vlong		todget(vlong*, vlong*);
 void		todsetfreq(vlong);
 void		todinit(void);
 void		todset(vlong, vlong, int);
diff --git a/sys/src/9k/port/sysproc.c b/sys/src/9k/port/sysproc.c
index 31cee7d5..5366fc81 100755
--- a/sys/src/9k/port/sysproc.c
+++ b/sys/src/9k/port/sysproc.c
@@ -1215,5 +1215,5 @@ syssemrelease(Ar0* ar0, va_list list)
 void
 sysnsec(Ar0* ar0, va_list)
 {
-	ar0->vl = todget(nil);
+	ar0->vl = todget(nil, nil);
 }
diff --git a/sys/src/9k/port/taslock.c b/sys/src/9k/port/taslock.c
index b59036d0..f65ef099 100755
--- a/sys/src/9k/port/taslock.c
+++ b/sys/src/9k/port/taslock.c
@@ -82,7 +82,7 @@ lock(Lock *l)
 				 */
 				print("inversion %#p pc %#p proc %d held by pc %#p proc %d\n",
 					l, pc, up ? up->pid : 0, l->pc, l->p ? l->p->pid : 0);
-				up->edf->d = todget(nil);	/* yield to process with lock */
+				up->edf->d = todget(nil, nil);	/* yield to process with lock */
 			}
 			if(i++ > 100000000){
 				i = 0;
diff --git a/sys/src/9k/port/tod.c b/sys/src/9k/port/tod.c
index 247d5a25..df639485 100755
--- a/sys/src/9k/port/tod.c
+++ b/sys/src/9k/port/tod.c
@@ -3,6 +3,7 @@
 #include	"mem.h"
 #include	"dat.h"
 #include	"fns.h"
+#include	"../port/error.h"
 
 /*
  * Compute nanosecond epoch time from the fastest ticking clock
@@ -43,7 +44,9 @@ struct {
 	uvlong	udivider;	/* ticks = (µdivider*µs)>>31 */
 	vlong	hz;		/* frequency of fast clock */
 	vlong	last;		/* last reading of fast clock */
-	vlong	off;		/* offset from epoch to last */
+	vlong	off;		/* offset from epoch to last (ns) */
+	vlong	monolast;	/* last reading of fast clocks for monotonic time */
+	vlong	monooff;	/* offset from 0 to monolast (ns) */
 	vlong	lasttime;	/* last return value from todget */
 	vlong	delta;	/* add 'delta' each slow clock tick from sstart to send */
 	ulong	sstart;		/* ... */
@@ -60,20 +63,43 @@ todinit(void)
 	ilock(&tod);
 	tod.init = 1;			/* prevent reentry via fastticks */
 	tod.last = fastticks((uvlong *)&tod.hz);
+	tod.monolast = tod.last;
 	iunlock(&tod);
 	todsetfreq(tod.hz);
 	addclock0link(todfix, 100);
 }
 
+/*
+ *  return monotonic ns; tod must be locked
+ */
+static vlong
+todmono(vlong ticks)
+{
+	uvlong x;
+	vlong diff;
+
+	if(tod.hz == 0) /* called from first todsetfreq */
+		return 0;
+	diff = ticks - tod.monolast;
+	mul64fract(&x, diff, tod.multiplier);
+	x += tod.monooff;
+	return x;
+}
+
 /*
  *  calculate multiplier
  */
 void
 todsetfreq(vlong f)
 {
+	vlong ticks;
+
 	if (f <= 0)
 		panic("todsetfreq: freq %lld <= 0", f);
 	ilock(&tod);
+	ticks = fastticks(nil);
+	tod.monooff = todmono(ticks);
+	tod.monolast = ticks;
 	tod.hz = f;
 
 	/* calculate multiplier for time conversion */
@@ -124,10 +150,10 @@ todset(vlong t, vlong delta, int n)
  *  get time of day
  */
 vlong
-todget(vlong *ticksp)
+todget(vlong *ticksp, vlong *monop)
 {
 	uvlong x;
-	vlong ticks, diff;
+	vlong ticks, diff, mono;
 	ulong t;
 
 	if(!tod.init)
@@ -158,16 +184,21 @@ todget(vlong *ticksp)
 	mul64fract(&x, diff, tod.multiplier);
 	x += tod.off;
 
-	/* time can't go backwards */
+	/* time can't go backwards (except when /dev/[bin]time is written) */
 	if(x < tod.lasttime)
 		x = tod.lasttime;
 	else
 		tod.lasttime = x;
 
+	mono = 0;
+	if(monop != nil)
+		mono = todmono(ticks);
 	iunlock(&tod);
 
 	if(ticksp != nil)
 		*ticksp = ticks;
+	if(monop != nil)
+		*monop = mono;
 
 	return x;
 }
@@ -218,7 +249,7 @@ if(x > 30000000000ULL) iprint("todfix %llud\n", x);
 long
 seconds(void)
 {
-	return (vlong)todget(nil) / TODFREQ;
+	return (vlong)todget(nil, nil) / TODFREQ;
 }
 
 uvlong