Plan 9 from Bell Labs 2014-05-15

Author: 0intro

sys/doc/backup.ms

@@ -32,9 +32,9 @@ as the term is used by everyone but disk manufacturers.
 In the case of BDs,
 even that is an exaggeration, with the actual capacity being
 closer to $48.44 times 10 sup 9$ bytes,
-so the claimed capacity should be read as `50 VAX-gigabytes',
+so the claimed capacity should be read as `50 BD-gigabytes',
 where a
-.I VAX-gigabyte
+.I BD-gigabyte
 is 968,800,338 bytes.
 The default
 .I venti

sys/doc/backup.pdf

@@ -33,18 +33,27 @@ should be stored in and treated as
 .BR ulong s;
 this extends the range of valid times into the year 2106.
 .PP
-These functions work by reading
+.I Time
+simply calls
+.I nsec
+and returns the value divided by 1000000000.
+.PP
+.I Nsec
+is a system call.
+Previous implementations read
 .BR /dev/bintime ,
-opening that file when they are first called.
+opening that file when first called,
+and maintaining a static file descriptor;
+however,
+the maintenance of file descriptors in the face
+of process forks is overly complex and prone to error.
 .SH SOURCE
 .B /sys/src/libc/9sys/time.c
 .br
-.B /sys/src/libc/9sys/nsec.c
+.B /sys/src/libc/9syscall
 .SH SEE ALSO
 .IR cputime (2),
 .IR cons (3)
 .SH DIAGNOSTICS
 Sets
 .IR errstr .
-.SH BUGS
-These routines maintain a static file descriptor.

sys/doc/backup.ps

@@ -95,11 +95,11 @@ extern int fpuemu(Ureg*);
 extern void delay(int);				/* only scheddump() */
 extern int islo(void);
 extern void microdelay(int);			/* only edf.c */
-extern void evenaddr(uintptr);
 extern void idlehands(void);
 extern void setkernur(Ureg*, Proc*);		/* only devproc.c */
 extern void* sysexecregs(uintptr, ulong, int);
 extern void sysprocsetup(Proc*);
+extern void validalign(uintptr, unsigned);
 
 extern void kexit(Ureg*);
 

sys/man/2/time

@@ -28,15 +28,32 @@ setkernur(Ureg* ureg, Proc* p)
 }
 
 /*
- * called in sysfile.c
+ * called in syscallfmt.c, sysfile.c, sysproc.c
  */
 void
-evenaddr(uintptr addr)
-{
-	if(addr & 3){
-		postnote(up, 1, "sys: odd address", NDebug);
-		error(Ebadarg);
-	}
+validalign(uintptr addr, unsigned align)
+{
+	/*
+	 * Plan 9 is a 32-bit O/S, and the hardware it runs on
+	 * does not usually have instructions which move 64-bit
+	 * quantities directly, synthesizing the operations
+	 * with 32-bit move instructions. Therefore, the compiler
+	 * (and hardware) usually only enforce 32-bit alignment,
+	 * if at all.
+	 *
+	 * Take this out if the architecture warrants it.
+	 */
+	if(align == sizeof(vlong))
+		align = sizeof(long);
+
+	/*
+	 * Check align is a power of 2, then addr alignment.
+	 */
+	if((align != 0 && !(align & (align-1))) && !(addr & (align-1)))
+		return;
+	postnote(up, 1, "sys: odd address", NDebug);
+	error(Ebadarg);
+	/*NOTREACHED*/
 }
 
 /* go to user space */

sys/src/9/bcm/fns.h

@@ -128,13 +128,13 @@ extern Block* uciallocb(int);
 extern void delay(int);				/* only scheddump() */
 extern int islo(void);
 extern void microdelay(int);			/* only edf.c */
-extern void evenaddr(uintptr);
 extern void idlehands(void);
 extern void setkernur(Ureg*, Proc*);		/* only devproc.c */
 extern void spldone(void);
 extern int splfhi(void);
 extern int splflo(void);
 extern void sysprocsetup(Proc*);
+extern void validalign(uintptr, unsigned);
 
 /*
  * PCI

sys/src/9/kw/arch.c

@@ -15,7 +15,6 @@ void	delay(int);
 void	dumpregs(Ureg*);
 void	delayloopinit(void);
 void	eieio(void);
-void	evenaddr(ulong);
 void	faultpower(Ureg*, ulong addr, int read);
 void	fprestore(FPsave*);
 void	fpsave(FPsave*);
@@ -103,6 +102,7 @@ void	trapvec(void);
 void	tlbflush(ulong);
 void	tlbflushall(void);
 #define	userureg(ur) (((ur)->status & MSR_PR) != 0)
+void	validalign(uintptr, unsigned);
 void	watchreset(void);
 
 #define	waserror()	(up->nerrlab++, setlabel(&up->errlab[up->nerrlab-1]))

sys/src/9/kw/fns.h

@@ -522,15 +522,32 @@ kprocchild(Proc *p, void (*func)(void*), void *arg)
 }
 
 /*
- * called in sysfile.c
+ * called in syscallfmt.c, sysfile.c, sysproc.c
  */
 void
-evenaddr(ulong addr)
+validalign(uintptr addr, unsigned align)
 {
-	if(addr & 3){
-		postnote(up, 1, "sys: odd address", NDebug);
-		error(Ebadarg);
-	}
+	/*
+	 * Plan 9 is a 32-bit O/S, and the hardware it runs on
+	 * does not usually have instructions which move 64-bit
+	 * quantities directly, synthesizing the operations
+	 * with 32-bit move instructions. Therefore, the compiler
+	 * (and hardware) usually only enforce 32-bit alignment,
+	 * if at all.
+	 *
+	 * Take this out if the architecture warrants it.
+	 */
+	if(align == sizeof(vlong))
+		align = sizeof(long);
+
+	/*
+	 * Check align is a power of 2, then addr alignment.
+	 */
+	if((align != 0 && !(align & (align-1))) && !(addr & (align-1)))
+		return;
+	postnote(up, 1, "sys: odd address", NDebug);
+	error(Ebadarg);
+	/*NOTREACHED*/
 }
 
 long

sys/src/9/mtx/fns.h

@@ -28,15 +28,32 @@ setkernur(Ureg* ureg, Proc* p)
 }
 
 /*
- * called in sysfile.c
+ * called in syscallfmt.c, sysfile.c, sysproc.c
  */
 void
-evenaddr(uintptr addr)
-{
-	if(addr & 3){
-		postnote(up, 1, "sys: odd address", NDebug);
-		error(Ebadarg);
-	}
+validalign(uintptr addr, unsigned align)
+{
+	/*
+	 * Plan 9 is a 32-bit O/S, and the hardware it runs on
+	 * does not usually have instructions which move 64-bit
+	 * quantities directly, synthesizing the operations
+	 * with 32-bit move instructions. Therefore, the compiler
+	 * (and hardware) usually only enforce 32-bit alignment,
+	 * if at all.
+	 *
+	 * Take this out if the architecture warrants it.
+	 */
+	if(align == sizeof(vlong))
+		align = sizeof(long);
+
+	/*
+	 * Check align is a power of 2, then addr alignment.
+	 */
+	if((align != 0 && !(align & (align-1))) && !(addr & (align-1)))
+		return;
+	postnote(up, 1, "sys: odd address", NDebug);
+	error(Ebadarg);
+	/*NOTREACHED*/
 }
 
 /* go to user space */