fix a few oversights.

Reference: /n/atom/patch/applied/execregs
Date: Fri Nov  6 06:33:10 CET 2015
Signed-off-by: quanstro@quanstro.net

--- /sys/src/9/port/sysproc.c	Fri Nov  6 06:33:02 2015
+++ /sys/src/9/port/sysproc.c	Fri Nov  6 06:33:02 2015
@@ -329,7 +329,7 @@
 
 	/*
 	 * 8-byte align SP for those (e.g. sparc) that need it.
-	 * execregs() will subtract another 4 bytes for argc.
+	 * execregs() will subtract another sizeof(uintptr) bytes for argc.
 	 */
 	if((ssize+4) & 7)
 		ssize += 4;
@@ -338,7 +338,7 @@
 	/*
 	 * Build the stack segment, putting it in kernel virtual for the moment
 	 */
-	if(spage > TSTKSIZ)
+	if(spage > USTKSIZE/BY2PG/2)
 		error(Enovmem);
 
 	qlock(&up->seglock);
@@ -376,6 +376,8 @@
 		charp += n;
 	}
 	free(file0);
+	file0 = nil;
+	USED(file0);
 
 	free(up->text);
 	up->text = elem;
@@ -487,7 +489,8 @@
 	if(up->hang)
 		up->procctl = Proc_stopme;
 
-	return execregs(entry, ssize, nargs);
+	/* should return void* */
+	return (long)execregs(entry, ssize, nargs);
 }
 
 int
--- /sys/src/9/pcpae/trap.c	Fri Nov  6 06:33:02 2015
+++ /sys/src/9/pcpae/trap.c	Fri Nov  6 06:33:02 2015
@@ -441,7 +441,7 @@
 			 */
 			iprint("cpu%d: NMI PC %#p\n", m->machno, ureg->pc);
 			while(m->machno != 0)
-				;
+				halt();
 		}
 		dumpregs(ureg);
 		if(!user){
@@ -478,14 +478,14 @@
 			m->machno, up->text, up->pid);
 	else
 		iprint("cpu%d: registers for kernel\n", m->machno);
-	iprint("FLAGS=%luX TRAP=%luX ECODE=%luX PC=%luX",
+	iprint("FLAGS=%#p TRAP=%#p ECODE=%#p PC=%#p",
 		ureg->flags, ureg->trap, ureg->ecode, ureg->pc);
-	iprint(" SS=%4.4luX USP=%luX\n", ureg->ss & 0xFFFF, ureg->sp);
-	iprint("  AX %8.8luX  BX %8.8luX  CX %8.8luX  DX %8.8luX\n",
+	iprint(" SS=%.4lux USP=%lux\n", ureg->ss & 0xFFFF, ureg->sp);
+	iprint("  AX %.8lux  BX %.8lux  CX %.8lux  DX %.8lux\n",
 		ureg->ax, ureg->bx, ureg->cx, ureg->dx);
-	iprint("  SI %8.8luX  DI %8.8luX  BP %8.8luX\n",
+	iprint("  SI %.8lux  DI %.8lux  BP %.8lux\n",
 		ureg->si, ureg->di, ureg->bp);
-	iprint("  CS %4.4luX  DS %4.4luX  ES %4.4luX  FS %4.4luX  GS %4.4luX\n",
+	iprint("  CS %.4lux  DS %.4lux  ES %.4lux  FS %.4lux  GS %.4lux\n",
 		ureg->cs & 0xFFFF, ureg->ds & 0xFFFF, ureg->es & 0xFFFF,
 		ureg->fs & 0xFFFF, ureg->gs & 0xFFFF);
 }
@@ -980,22 +980,22 @@
 	}
 }
 
-long
-execregs(ulong entry, ulong ssize, ulong nargs)
+void*
+execregs(uintptr entry, uint ssize, uint nargs)
 {
-	ulong *sp;
+	uintptr *sp;
 	Ureg *ureg;
 
 	up->fpstate = FPinit;
 	fpoff();
 
-	sp = (ulong*)(USTKTOP - ssize);
+	sp = (uintptr*)(USTKTOP - ssize);
 	*--sp = nargs;
 
 	ureg = up->dbgreg;
 	ureg->sp = PTR2UINT(sp);
 	ureg->pc = entry;
-	return USTKTOP-sizeof(Tos);		/* address of kernel/user shared data */
+	return UINT2PTR(USTKTOP-sizeof(Tos));		/* address of kernel/user shared data */
 }
 
 /*