- Add cpuctl(4) pseudo-device driver to provide access to some low-level

  features of CPUs like reading/writing machine-specific registers,
  retrieving cpuid data, and updating microcode.
- Add cpucontrol(8) utility, that provides userland access to
  the features of cpuctl(4).
- Add subsequent manpages.

The cpuctl(4) device operates as follows. The pseudo-device node cpuctlX
is created for each cpu present in the systems. The pseudo-device minor
number corresponds to the cpu number in the system. The cpuctl(4) pseudo-
device allows a number of ioctl to be preformed, namely RDMSR/WRMSR/CPUID
and UPDATE. The first pair alows the caller to read/write machine-specific
registers from the correspondent CPU. cpuid data could be retrieved using
the CPUID call, and microcode updates are applied via UPDATE.

The permissions are inforced based on the pseudo-device file permissions.
RDMSR/CPUID will be allowed when the caller has read access to the device
node, while WRMSR/UPDATE will be granted only when the node is opened
for writing. There're also a number of priv(9) checks.

The cpucontrol(8) utility is intened to provide userland access to
the cpuctl(4) device features. The utility also allows one to apply
cpu microcode updates.

Currently only Intel and AMD cpus are supported and were tested.

Approved by:	kib
Reviewed by:	rpaulo, cokane, Peter Jeremy
MFC after:	1 month

2 files changed, 148 insertions, 0 deletions

diff --git a/share/man/man4/Makefile b/share/man/man4/Makefile
index 69d9dc8..544a542 100644
--- a/share/man/man4/Makefile
+++ b/share/man/man4/Makefile
@@ -52,6 +52,7 @@ MAN=	aac.4 \
 	cmx.4 \
 	coda.4 \
 	${_coretemp.4} \
+	${_cpuctl.4} \
 	cpufreq.4 \
 	crypto.4 \
 	cue.4 \
@@ -551,6 +552,7 @@ _acpi_dock.4=	acpi_dock.4
 _amdsmb.4=	amdsmb.4
 _asmc.4=	asmc.4
 _coretemp.4=	coretemp.4
+_cpuctl.4=	cpuctl.4
 _hptiop.4=	hptiop.4
 _hptmv.4=	hptmv.4
 _hptrr.4=	hptrr.4
diff --git a/share/man/man4/cpuctl.4 b/share/man/man4/cpuctl.4
new file mode 100644
index 0000000..0e60801
--- /dev/null
+++ b/share/man/man4/cpuctl.4
@@ -0,0 +1,146 @@
+.\" Copyright (c) 2006-2008 Stanislav Sedov <stas@FreeBSD.org>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd May 31, 2008
+.Dt CPUCTL 4
+.Os
+.Sh NAME
+.Nm cpuctl
+.Nd cpuctl pseudo device
+.Sh SYNOPSIS
+To compile this driver into the kernel,
+place the following lines in your kernel
+configuration file:
+.Bd -ragged -offset indent
+.Cd "device cpuctl"
+.Ed
+.Pp
+Alternatively, to load the driver as a module
+at boot time, place the following in
+.Xr loader.conf 5 :
+.Bd -literal -offset indent
+cpuctl_load="YES"
+.Ed
+.Sh DESCRIPTION
+The special file
+.Pa /dev/cpuctl
+presents interace to the system CPU. It provides functionality to retrieve
+CPUID information, read/write machine specific registers (MSR) and perform
+cpu firmware updates.
+.Pp
+For each cpu present in the system, special file
+.Pa /dev/cpuctl%d
+with the appropriate index will be created. For multicore cpus the
+special file will be created for each core.
+.Pp
+Currently, only i386 and amd64 processors are
+supported.
+.Sh IOCTL INTERFACE
+All of the supported operations are invoked using the
+.Fr ioctl 2
+system call. Refer to that manpage for further information about
+this interface. Currently, the following ioctls are defined:
+.Bl -tag -width CPUCTL_UPDATE
+.It Dv CPUCTL_RDMSR Fa cpuctl_msr_args_t *args
+.It Dv CPUCTL_WRMSR Fa cpuctl_msr_args_t *args
+Read/write cpu machine specific register. The
+.Vt cpuctl_msr_args_t
+structure defined in
+.In sys/cpuctl.h
+as:
+.Pp
+.Bd -literal
+typedef struct {
+	int		msr;	/* MSR to read */
+	uint64_t	data;
+} cpuctl_msr_args_t;
+.Ed
+.It Dv CPUCTL_CPUID Fa cpuctl_cpuid_args_t *args
+Retrieve CPUID information. Arguments are supplied in
+the following struct:
+.Pp
+.Bd -literal
+typedef struct {
+	int		level;	/* CPUID level */
+	uint32_t	data[4];
+} cpuctl_cpuid_args_t;
+.Ed
+.Pp
+The
+.Va level
+field indicates the CPUID level to retrieve information for, while the
+.Va data
+used to store CPUID data received.
+.It Dv CPUCTL_UPDATE cpuctl_update_args_t *args
+Update cpu firmware (microcode). The structure defined in
+.In sys/cpuctl.h
+as:
+.Pp
+.Bd -literal
+typedef struct {
+	void	*data;
+	size_t	size;
+} cpuctl_update_args_t;
+.Ed
+.Pp
+The
+.Va data
+field should point to the firmware image of size
+.Va size .
+.El
+.Pp
+For additional information refer to
+.Pa cpuctl.h .
+.Sh RETURN VALUES
+.Bl -tag -width Er
+.It Bq Er ENXIO
+The operation requested is not supported by device (e.g. unsupported
+architecture or cpu was disabled)
+.It Bq Er EINVAL
+Incorrect request was supplied, or microcode image is not correct.
+.It Bq Er ENOMEM
+No physical memory was available to complete the request.
+.It Bq Er EFAULT
+The firmware image address points outside process address space.
+.El
+.Sh FILES
+.Bl -tag -width /dev/cpuctl -compact
+.It Pa /dev/cpuctl
+.El
+.Sh SEE ALSO
+.Xr hwpmc 4
+.Sh HISTORY
+The
+.Nm
+driver first appeared in
+.Fx 8.0
+.Sh BUGS
+Yes, probably, report if any.
+.Sh AUTHORS
+The
+.Nm
+module and this manual page was written by
+.An Stanislav Sedov Aq stas@FreeBSD.org .