.\"	$OpenBSD: amd64_get_ioperm.2,v 1.2 2004/03/12 17:40:28 jmc Exp $
.\"	$NetBSD: amd64_get_ioperm.2,v 1.3 1996/02/27 22:57:17 jtc Exp $
.\"
.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by John T. Kohl and Charles M. Hannum.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
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.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	   This product includes software developed by the NetBSD
.\"	   Foundation, Inc. and its contributors.
.\" 4. Neither the name of The NetBSD Foundation nor the names of its
.\"    contributors may be used to endorse or promote products derived
.\"    from this software without specific prior written permission.
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.\"
.Dd October 14, 1995
.Dt AMD64_GET_IOPERM 2 amd64
.Os
.Sh NAME
.Nm amd64_get_ioperm ,
.Nm amd64_set_ioperm
.Nd manage amd64 per-process I/O permission bitmap
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <machine/sysarch.h>
.Ft int
.Fn amd64_get_ioperm "u_long *iomap"
.Ft int
.Fn amd64_set_ioperm "u_long *iomap"
.Sh DESCRIPTION
.Fn amd64_get_ioperm
copies the current I/O permission bitmap into the memory referenced by
.Fa iomap .
.Pp
.Fn amd64_set_ioperm
sets the I/O permission bitmap from the data pointed to by
.Fa iomap .
This call is restricted to the superuser.
.Pp
The permission bitmap contains 1024 bits in 32 longwords.
If bit
.Va n
is clear in the bitmap, then access is granted to I/O port
.Va n .
If bit
.Va n
is set in the bitmap, then an attempt to access I/O port
.Va n
results in delivery of a
.Dv SIGBUS
signal unless the process's I/O permission level would grant I/O access.
.Pp
.Sy Note:
Code using the
.Fn amd64_get_ioperm
and
.Fn amd64_set_ioperm
functions must be compiled using
.Cm -lamd64 .
.Sh RETURN VALUES
Upon successful completion,
.Fn amd64_get_ioperm
and
.Fn amd64_set_ioperm
return 0.
Otherwise, a value of \-1 is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn amd64_get_ioperm
and
.Fn amd64_set_ioperm
will fail if:
.Bl -tag -width [EINVAL]
.It Bq Er EFAULT
.Fa iomap
points outside the process's allocated address space.
.It Bq Er EPERM
The caller was not the superuser.
.El
.Sh SEE ALSO
.Xr amd64_iopl 2
.Rs
.%A Intel
.%T AMD64 Microprocessor Programmer's Reference Manual
.Re
.Sh WARNING
You can really hose your machine if you enable user-level I/O and
write to hardware ports without care.
.Sh BUGS
The bitmap should really cover 65536 bits, but that's just too big for
allocation in a kernel structure.
If you need access to ports beyond 1024, use
.Xr amd64_iopl 2 .