inching closer to nix.

the base page size isn't necessarly the alignment for executables.
introduce the UTROUND() macro from nix.

additionally, fix the stack calcuations in pc and pcpae/main.c
to account for the size of the Tos structure.  without this fix
the tos changes for rb make the pc kernel unbootable.

Reference: /n/atom/patch/applied2013/utround
Date: Sat Aug  3 21:30:15 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/9/port/sysproc.c	Sat Aug  3 21:29:45 2013
+++ /sys/src/9/port/sysproc.c	Sat Aug  3 21:29:46 2013
@@ -294,7 +294,7 @@
 
 	data = l2be(exec.data);
 	bss = l2be(exec.bss);
-	t = (UTZERO+sizeof(Exec)+text+(BY2PG-1)) & ~(BY2PG-1);
+	t = UTROUND(UTZERO+sizeof(Exec)+text);
 	d = (t + data + (BY2PG-1)) & ~(BY2PG-1);
 	bssend = t + data + bss;
 	b = (bssend + (BY2PG-1)) & ~(BY2PG-1);
--- /sys/src/9/pc/main.c	Sat Aug  3 21:29:47 2013
+++ /sys/src/9/pc/main.c	Sat Aug  3 21:29:48 2013
@@ -8,6 +8,7 @@
 #include	"init.h"
 #include	"pool.h"
 #include	"reboot.h"
+#include	<tos.h>
 
 Mach *m;
 
@@ -23,6 +24,11 @@
 #define	BOOTARGSLEN	(4096-0x200-BOOTLINELEN)
 #define	MAXCONF		64
 
+enum {
+	/* space for syscall args, return PC, top-of-stack struct */
+	Ustkheadroom	= sizeof(Sargs) + sizeof(uintptr) + sizeof(Tos),
+};
+
 usize	segpgsizes = (1<<PGSHIFT);	/* only page size available */
 Conf conf;
 char *confname[MAXCONF];
@@ -291,7 +297,7 @@
 	char *cp = BOOTLINE;
 	char buf[64];
 
-	sp = (uchar*)base + BY2PG - MAXSYSARG*BY2WD;
+	sp = (uchar*)base + BY2PG - Ustkheadroom;
 
 	ac = 0;
 	av[ac++] = pusharg("/386/9dos");
--- /sys/src/9/pc/mem.h	Sat Aug  3 21:29:49 2013
+++ /sys/src/9/pc/mem.h	Sat Aug  3 21:29:49 2013
@@ -18,7 +18,8 @@
 #define	BY2PG		4096			/* bytes per page */
 #define	PGSHIFT		12			/* log(BY2PG) */
 #define	ROUND(s, sz)	(((s)+((sz)-1))&~((sz)-1))
-#define	PGROUND(s)	ROUND(s, BY2PG)
+#define	PGROUND(s)	ROUNDUP(s, BY2PG)
+#define	UTROUND(s)	ROUNDUP(s, BY2PG)
 #define	BLOCKALIGN	8
 
 #define	BY2XPG		(4096*1024)	/* bytes per big page */
--- /sys/src/9/pcpae/main.c	Sat Aug  3 21:29:50 2013
+++ /sys/src/9/pcpae/main.c	Sat Aug  3 21:29:51 2013
@@ -8,6 +8,7 @@
 #include	"init.h"
 #include	"pool.h"
 #include	"reboot.h"
+#include	<tos.h>
 
 Mach *m;
 
@@ -23,6 +24,11 @@
 #define	BOOTARGSLEN	(4096-0x200-BOOTLINELEN)
 #define	MAXCONF		64
 
+enum {
+	/* space for syscall args, return PC, top-of-stack struct */
+	Ustkheadroom	= sizeof(Sargs) + sizeof(uintptr) + sizeof(Tos),
+};
+
 usize	segpgsizes = (1<<PGSHIFT)|(1<<XPGSHIFT);	/* only page sizes available by default */
 Conf conf;
 char *confname[MAXCONF];
@@ -294,7 +300,7 @@
 	char *cp = BOOTLINE;
 	char buf[64];
 
-	sp = (uchar*)base + BY2PG - MAXSYSARG*BY2WD;
+	sp = (uchar*)base + BY2PG - Ustkheadroom;
 
 	ac = 0;
 	av[ac++] = pusharg("/386/9dos");
--- /sys/src/9/pcpae/mem.h	Sat Aug  3 21:29:52 2013
+++ /sys/src/9/pcpae/mem.h	Sat Aug  3 21:29:53 2013
@@ -18,7 +18,8 @@
 #define	BY2PG		4096			/* bytes per page */
 #define	PGSHIFT		12			/* log(BY2PG) */
 #define	ROUND(s, sz)	(((s)+((sz)-1))&~((sz)-1))
-#define	PGROUND(s)	ROUND(s, BY2PG)
+#define	PGROUND(s)	ROUNDUP(s, BY2PG)
+#define	UTROUND(s)	ROUNDUP(s, BY2PG)
 #define	BLOCKALIGN	8
 
 #define	BY2XPG		(2048*1024)
--- /sys/src/9/alphapc/mem.h	Sat Aug  3 21:29:53 2013
+++ /sys/src/9/alphapc/mem.h	Sat Aug  3 21:29:54 2013
@@ -18,7 +18,8 @@
 #define	BY2PG		8192			/* bytes per page */
 #define	PGSHIFT		13			/* log(BY2PG) */
 #define ROUND(s, sz)	(((s)+((sz)-1))&~((sz)-1))
-#define PGROUND(s)	ROUND(s, BY2PG)
+#define PGROUND(s)	ROUNDUP(s, BY2PG)
+#define	UTROUND(s)	ROUNDUP(s, BY2PG)
 #define BLOCKALIGN	8
 
 #define	BY2PTE		8			/* bytes per pte entry */
--- /sys/src/9/bcm/mem.h	Sat Aug  3 21:29:55 2013
+++ /sys/src/9/bcm/mem.h	Sat Aug  3 21:29:55 2013
@@ -17,6 +17,7 @@
 #define	BY2PG		(4*KiB)			/* bytes per page */
 #define	PGSHIFT		12			/* log(BY2PG) */
 #define	PGROUND(s)	ROUNDUP(s, BY2PG)
+#define	UTROUND(s)	ROUNDUP(s, BY2PG)
 #define	ROUND(s, sz)	(((s)+(sz-1))&~(sz-1))
 
 #define	MAXMACH		1			/* max # cpus system can run */
--- /sys/src/9/bitsy/mem.h	Sat Aug  3 21:29:56 2013
+++ /sys/src/9/bitsy/mem.h	Sat Aug  3 21:29:57 2013
@@ -18,7 +18,8 @@
 #define	BY2PG		4096			/* bytes per page */
 #define	PGSHIFT		12			/* log(BY2PG) */
 #define	ROUND(s, sz)	(((s)+(sz-1))&~(sz-1))
-#define	PGROUND(s)	ROUND(s, BY2PG)
+#define	PGROUND(s)	ROUNDUP(s, BY2PG)
+#define	UTROUND(s)	ROUNDUP(s, BY2PG)
 #define	BLOCKALIGN	8
 
 #define	MAXMACH	1			/* max # cpus system can run */
--- /sys/src/9/kw/mem.h	Sat Aug  3 21:29:57 2013
+++ /sys/src/9/kw/mem.h	Sat Aug  3 21:29:58 2013
@@ -37,6 +37,7 @@
 #define	BY2PG		(4*KiB)			/* bytes per page */
 #define	PGSHIFT		12			/* log(BY2PG) */
 #define	PGROUND(s)	ROUNDUP(s, BY2PG)
+#define	UTROUND(s)	ROUNDUP(s, BY2PG)
 #define	ROUND(s, sz)	(((s)+(sz-1))&~(sz-1))
 
 #define	MAXMACH		1			/* max # cpus system can run */
--- /sys/src/9/mtx/mem.h	Sat Aug  3 21:29:59 2013
+++ /sys/src/9/mtx/mem.h	Sat Aug  3 21:29:59 2013
@@ -19,7 +19,8 @@
 #define	BY2PG		4096		/* bytes per page */
 #define	PGSHIFT		12			/* log(BY2PG) */
 #define 	ROUND(s, sz)	(((s)+(sz-1))&~(sz-1))
-#define 	PGROUND(s)	ROUND(s, BY2PG)
+#define	PGROUND(s)	ROUNDUP(s, BY2PG)
+#define	UTROUND(s)	ROUNDUP(s, BY2PG)
 #define	CACHELINELOG	4
 #define	CACHELINESZ	(1<<CACHELINELOG)
 #define	BLOCKALIGN	CACHELINESZ
--- /sys/src/9/ppc/mem.h	Sat Aug  3 21:30:00 2013
+++ /sys/src/9/ppc/mem.h	Sat Aug  3 21:30:01 2013
@@ -25,7 +25,8 @@
 #define	BY2PG		4096			/* bytes per page */
 #define	PGSHIFT		12			/* log(BY2PG) */
 #define ROUND(s, sz)	(((s)+(sz-1))&~(sz-1))
-#define PGROUND(s)	ROUND(s, BY2PG)
+#define	PGROUND(s)	ROUNDUP(s, BY2PG)
+#define	UTROUND(s)	ROUNDUP(s, BY2PG)
 #define	CACHELINELOG	5
 #define	CACHELINESZ	(1<<CACHELINELOG)
 #define	BLOCKALIGN	CACHELINESZ
--- /sys/src/9/rb/mem.h	Sat Aug  3 21:30:02 2013
+++ /sys/src/9/rb/mem.h	Sat Aug  3 21:30:02 2013
@@ -38,7 +38,6 @@
 #endif
 
 #define	KSTACK		8192			/* Size of kernel stack */
-#define	WD2PG		(BY2PG/BY2WD)		/* words per page */
 
 #define	MAXMACH		1   /* max # cpus system can run; see active.machs */
 #define STACKALIGN(sp)	((sp) & ~7)		/* bug: assure with alloc */