1. recover correctly from invalid sys call number
2. don't rely on host order for vlong
3. initialise stack with area for Tos so libc will work

Reference: /n/sources/patch/applied/5i-various
Date: Wed Jul  4 18:13:13 CES 2007
Signed-off-by: forsyth@terzarima.net

--- /sys/src/cmd/5i/5i.c	Wed Jul  4 18:10:31 2007
+++ /sys/src/cmd/5i/5i.c	Wed Jul  4 18:10:29 2007
@@ -4,6 +4,8 @@
 #include <mach.h>
 #include "arm.h"
 
+#include <tos.h>
+
 char*	file = "5.out";
 int	datasize;
 ulong	textbase;
@@ -138,12 +140,13 @@
 initstk(int argc, char *argv[])
 {
 	ulong size;
-	ulong sp, ap;
+	ulong sp, ap, tos;
 	int i;
 	char *p;
 
 	initmap();
-	sp = STACKTOP - 4;
+	tos = STACKTOP - sizeof(Tos)*2;	/* we'll assume twice the host's is big enough */
+	sp = tos;
 
 	/* Build exec stack */
 	size = strlen(file)+1+BY2WD+BY2WD+BY2WD;	
@@ -151,7 +154,8 @@
 		size += strlen(argv[i])+BY2WD+1;
 
 	sp -= size;
-	sp &= ~3;
+	sp &= ~7;
+	reg.r[0] = tos;
 	reg.r[13] = sp;
 	reg.r[1] = STACKTOP-4;	/* Plan 9 profiling clock */
 
--- /sys/src/cmd/5i/arm.h	Wed Jul  4 18:10:45 2007
+++ /sys/src/cmd/5i/arm.h	Wed Jul  4 18:10:42 2007
@@ -160,6 +160,7 @@
 ulong		getmem_4(ulong);
 uchar		getmem_b(ulong);
 ushort		getmem_h(ulong);
+uvlong		getmem_v(ulong);
 ulong		getmem_w(ulong);
 ulong		ifetch(ulong);
 void		inithdr(int);
@@ -181,8 +182,8 @@
 void		procinit(int);
 void		putmem_b(ulong, uchar);
 void		putmem_h(ulong, ushort);
+void		putmem_v(ulong, uvlong);
 void		putmem_w(ulong, ulong);
-void		randseed(long, long);
 void		reset(void);
 void		run(void);
 void		segsum(void);
--- /sys/src/cmd/5i/mem.c	Wed Jul  4 18:11:01 2007
+++ /sys/src/cmd/5i/mem.c	Wed Jul  4 18:10:59 2007
@@ -109,6 +109,12 @@
 	return va[0];
 }
 
+uvlong
+getmem_v(ulong addr)
+{
+	return ((uvlong)getmem_w(addr+4) << 32) | getmem_w(addr);
+}
+
 void
 putmem_h(ulong addr, ushort data)
 {
@@ -159,6 +165,13 @@
 	va[0] = data;
 	if(membpt)
 		brkchk(addr, Write);
+}
+
+void
+putmem_v(ulong addr, uvlong data)
+{
+	putmem_w(addr, data);	/* two stages, to catch brkchk */
+	putmem_w(addr+4, data>>32);
 }
 
 char *
--- /sys/src/cmd/5i/syscall.c	Wed Jul  4 18:11:21 2007
+++ /sys/src/cmd/5i/syscall.c	Wed Jul  4 18:11:18 2007
@@ -300,14 +300,7 @@
 void
 syspread(void)
 {
-	union {
-		vlong v;
-		ulong u[2];
-	} o;
-
-	o.u[0] = getmem_w(reg.r[13]+16);
-	o.u[1] = getmem_w(reg.r[13]+20);
-	sysread(o.v);
+	sysread(getmem_v(reg.r[13]+16));
 }
 
 void
@@ -316,24 +309,20 @@
 	int fd;
 	ulong mode;
 	ulong retp;
-	union {
-		vlong v;
-		ulong u[2];
-	} o;
+	vlong v;
 
 	retp = getmem_w(reg.r[13]+4);
 	fd = getmem_w(reg.r[13]+8);
-	o.u[0] = getmem_w(reg.r[13]+12);
-	o.u[1] = getmem_w(reg.r[13]+16);
+	v = getmem_v(reg.r[13]+16);
 	mode = getmem_w(reg.r[13]+20);
 	if(sysdbg)
-		itrace("seek(%d, %lld, %d)", fd, o.v, mode);
+		itrace("seek(%d, %lld, %d)", fd, v, mode);
 
-	o.v = seek(fd, o.v, mode);
-	if(o.v < 0)
+	v = seek(fd, v, mode);
+	if(v < 0)
 		errstr(errbuf, sizeof errbuf);	
 
-	memio((char*)o.u, retp, sizeof(vlong), MemWrite);
+	putmem_v(retp, v);
 }
 
 void
@@ -505,14 +494,7 @@
 void
 syspwrite(void)
 {
-	union {
-		vlong v;
-		ulong u[2];
-	} o;
-
-	o.u[0] = getmem_w(reg.r[13]+16);
-	o.u[1] = getmem_w(reg.r[13]+20);
-	syswrite(o.v);
+	syswrite(getmem_v(reg.r[13]+16));
 }
 
 void
@@ -811,9 +793,11 @@
 	int call;
 
 	call = reg.r[REGARG];
-	if(call < 0 || call > PWRITE || systab[call] == nil) {
-		Bprint(bioout, "bad system call\n");
+	if(call < 0 || call >= nelem(systab) || systab[call] == nil) {
+		Bprint(bioout, "bad system call %d (%#ux)\n", call, call);
 		dumpreg();
+		Bflush(bioout);
+		return;
 	}
 
 	if(trace)