# HG changeset patch
# User Ron Minnich <rminnich@gmail.com>
# Date 1320089335 25200
# Node ID 03c575d34cbb4bbd08337d6f2b5f8af3d861953a
# Parent  8a9762a01ea03157402a65091b6a107273ff41fa
Another go at a portable mwait.

It's 4pm and time for the kernel on top of your television to explode.
But as of 6PM GMT it seems to work.
mwait(void *): spin on the value of the data pointed to until it is non-zero.
sys/src/nix/k10/acore.c: use mwait
sys/src/nix/k10/archk10.c: if MONITOR enabled, use the k10 version
sys/src/nix/k10/fns.h: prototypes
sys/src/nix/k10/l64v.s: Assembly function which combines monitor and mwait
sys/src/nix/port/portfns.h: prototypes
sys/src/nix/port/taslock.c: portable version
Tested for both the portable and k10-specific versions and it works.

R=nixiedev
CC=nix-dev
http://codereview.appspot.com/5314066

diff -r 8a9762a01ea0 -r 03c575d34cbb sys/src/nix/k10/acore.c
--- a/sys/src/nix/k10/acore.c	Thu Oct 27 13:31:14 2011 -0700
+++ b/sys/src/nix/k10/acore.c	Mon Oct 31 12:28:55 2011 -0700
@@ -66,8 +66,7 @@
 		snprint((char*)mp->icc->data, ICCLNSZ, "<%d>", i);
 		mfence();
 		mp->icc->fn = testiccfn;
-		while(mp->icc->fn != nil)
-			;
+		mwait(&mp->icc->fn);
 	}
 }
 
@@ -103,8 +102,7 @@
 	for(;;){
 		acstackok();
 		m->load = 0;
-		while(*m->icc->fn == nil)
-			;
+		mwait(&m->icc->fn);
 		if(m->icc->flushtlb)
 			acmmuswitch();
 		DBG("acsched: cpu%d: fn %#p\n", m->machno, m->icc->fn);
@@ -217,8 +215,8 @@
 	ready(m->proc);
 
 	m->load = 0;
-	while(*m->icc->fn == nil)
-		;
+	mwait(&m->icc->fn);
+
 
 	m->load = 100;
 	if(m->icc->flushtlb)
diff -r 8a9762a01ea0 -r 03c575d34cbb sys/src/nix/k10/archk10.c
--- a/sys/src/nix/k10/archk10.c	Thu Oct 27 13:31:14 2011 -0700
+++ b/sys/src/nix/k10/archk10.c	Mon Oct 31 12:28:55 2011 -0700
@@ -31,7 +31,7 @@
 	/* is mnonitor supported? */
 	if (m->cpuinfo[1][2] & 8) {
 		cpuid(5, 0, &m->monitorsize);
-		iprint("Monitor supported; size %d", m->monitorsize);
+		mwait = k10mwait;
 	}
 
 	return 1;
diff -r 8a9762a01ea0 -r 03c575d34cbb sys/src/nix/k10/fns.h
--- a/sys/src/nix/k10/fns.h	Thu Oct 27 13:31:14 2011 -0700
+++ b/sys/src/nix/k10/fns.h	Mon Oct 31 12:28:55 2011 -0700
@@ -95,9 +95,7 @@
 int	mmukmapsync(uvlong);
 uintmem	mmuphysaddr(uintptr);
 int	mmuwalk(PTE*, uintptr, int, PTE**, PTE (*)(usize));
-void	monitor(void*);
 int	multiboot(u32int, u32int, int);
-void	mwait(u32int);
 void	ndnr(void);
 uchar	nvramread(int);
 void	nvramwrite(int, uchar);
@@ -225,6 +223,7 @@
  * archk10.c
  */
 extern void millidelay(int);
+void k10mwait(void *);
 
 /*
  * i8259.c
diff -r 8a9762a01ea0 -r 03c575d34cbb sys/src/nix/k10/l64v.s
--- a/sys/src/nix/k10/l64v.s	Thu Oct 27 13:31:14 2011 -0700
+++ b/sys/src/nix/k10/l64v.s	Mon Oct 31 12:28:55 2011 -0700
@@ -369,18 +369,38 @@
 	HLT
 	RET
 
-TEXT monitor(SB), 1, $-4			/* void monitor(void*); */
+TEXT _monitor(SB), 1, $-4			/* void monitor(void*); */
 	MOVQ	RARG, AX			/* linear address to monitor */
 	XORQ	CX, CX				/* no optional extensions yet */
 	XORQ	DX, DX				/* no optional hints yet */
 	BYTE $0x0f; BYTE $0x01; BYTE $0xc8	/* MONITOR */
 	RET
 
-TEXT mwait(SB), 1, $-4				/* void mwait(u32int); */
+TEXT _mwait(SB), 1, $-4				/* void mwait(u32int); */
 	MOVLQZX	RARG, CX			/* optional extensions */
 	BYTE $0x0f; BYTE $0x01; BYTE $0xc9	/* MWAIT */
 	RET
 
+TEXT	k10mwait+0(SB),0,$16
+k10mwloop:
+	MOVQ	RARG,CX
+	MOVQ	(CX),AX
+	CMPQ	AX,$0
+	JNE		k10mwdone
+	MOVQ	RARG, AX			/* linear address to monitor */
+	XORQ	CX, CX				/* no optional extensions yet */
+	XORQ	DX, DX				/* no optional hints yet */
+	BYTE $0x0f; BYTE $0x01; BYTE $0xc8	/* MONITOR */
+	MOVQ	RARG,CX
+	MOVQ	(CX),AX
+	CMPQ	AX,$0
+	JNE		k10mwdone
+	XORQ CX, CX			/* optional extensions */
+	BYTE $0x0f; BYTE $0x01; BYTE $0xc9	/* MWAIT */
+	JMP		k10mwloop
+k10mwdone:
+	RET	,
+
 TEXT mul64fract(SB), 1, $-4
 	MOVQ	a+8(FP), AX
 	MULQ	b+16(FP)			/* a*b */
diff -r 8a9762a01ea0 -r 03c575d34cbb sys/src/nix/port/portfns.h
--- a/sys/src/nix/port/portfns.h	Thu Oct 27 13:31:14 2011 -0700
+++ b/sys/src/nix/port/portfns.h	Mon Oct 31 12:28:55 2011 -0700
@@ -191,6 +191,7 @@
 ulong		ms2tk(ulong);
 void		mul64fract(uvlong*, uvlong, uvlong);
 void		muxclose(Mnt*);
+void		(*mwait)(void *);
 Chan*		namec(char*, int, int, int);
 void		nameerror(char*, char*);
 Chan*		newchan(void);
@@ -237,6 +238,7 @@
 void*		phystag(uintmem);
 void		pio(Segment*, uintptr, ulong, Page**);
 #define		poperror()		up->nerrlab--
+void		portmwait(void *);
 int		postnote(Proc*, int, char*, int);
 int		pprint(char*, ...);
 int		preempted(void);
diff -r 8a9762a01ea0 -r 03c575d34cbb sys/src/nix/port/taslock.c
--- a/sys/src/nix/port/taslock.c	Thu Oct 27 13:31:14 2011 -0700
+++ b/sys/src/nix/port/taslock.c	Mon Oct 31 12:28:55 2011 -0700
@@ -237,3 +237,12 @@
 		up->lastilock = nil;
 	splx(pl);
 }
+
+void
+portmwait(void *value)
+{
+	while (*(void**)value == nil)
+		;
+}
+
+void (*mwait)(void *) = portmwait;