arch/x86/kernel/msr.c - arm/linux-arm-legacy - Git at Google

 /* ----------------------------------------------------------------------- *
  *
  *   Copyright 2000-2008 H. Peter Anvin - All Rights Reserved
  *   Copyright 2009 Intel Corporation; author: H. Peter Anvin
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
  *   the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
  *   USA; either version 2 of the License, or (at your option) any later
  *   version; incorporated herein by reference.
  *
  * ----------------------------------------------------------------------- */

 /*
  * x86 MSR access device
  *
  * This device is accessed by lseek() to the appropriate register number
  * and then read/write in chunks of 8 bytes.  A larger size means multiple
  * reads or writes of the same register.
  *
  * This driver uses /dev/cpu/%d/msr where %d is the minor number, and on
  * an SMP box will direct the access to CPU %d.
  */

 #include <linux/module.h>

 #include <linux/types.h>
 #include <linux/errno.h>
 #include <linux/fcntl.h>
 #include <linux/init.h>
 #include <linux/poll.h>
 #include <linux/smp.h>
 #include <linux/major.h>
 #include <linux/fs.h>
 #include <linux/device.h>
 #include <linux/cpu.h>
 #include <linux/notifier.h>
 #include <linux/uaccess.h>
 #include <linux/gfp.h>

 #include <asm/processor.h>
 #include <asm/msr.h>

 static struct class *msr_class;

 static loff_t msr_seek(struct file *file, loff_t offset, int orig)
 {
 	loff_t ret;
 	struct inode *inode = file_inode(file);

 	mutex_lock(&inode->i_mutex);
 	switch (orig) {
 	case 0:
 		file->f_pos = offset;
 		ret = file->f_pos;
 		break;
 	case 1:
 		file->f_pos += offset;
 		ret = file->f_pos;
 		break;
 	default:
 		ret = -EINVAL;
 	}
 	mutex_unlock(&inode->i_mutex);
 	return ret;
 }

 static ssize_t msr_read(struct file *file, char __user *buf,
 			size_t count, loff_t *ppos)
 {
 	u32 __user *tmp = (u32 __user *) buf;
 	u32 data[2];
 	u32 reg = *ppos;
 	int cpu = iminor(file_inode(file));
 	int err = 0;
 	ssize_t bytes = 0;

 	if (count % 8)
 		return -EINVAL;	/* Invalid chunk size */

 	for (; count; count -= 8) {
 		err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);
 		if (err)
 			break;
 		if (copy_to_user(tmp, &data, 8)) {
 			err = -EFAULT;
 			break;
 		}
 		tmp += 2;
 		bytes += 8;
 	}

 	return bytes ? bytes : err;
 }

 static ssize_t msr_write(struct file *file, const char __user *buf,
 			 size_t count, loff_t *ppos)
 {
 	const u32 __user *tmp = (const u32 __user *)buf;
 	u32 data[2];
 	u32 reg = *ppos;
 	int cpu = iminor(file_inode(file));
 	int err = 0;
 	ssize_t bytes = 0;

 	if (count % 8)
 		return -EINVAL;	/* Invalid chunk size */

 	for (; count; count -= 8) {
 		if (copy_from_user(&data, tmp, 8)) {
 			err = -EFAULT;
 			break;
 		}
 		err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
 		if (err)
 			break;
 		tmp += 2;
 		bytes += 8;
 	}

 	return bytes ? bytes : err;
 }

 static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
 {
 	u32 __user *uregs = (u32 __user *)arg;
 	u32 regs[8];
 	int cpu = iminor(file_inode(file));
 	int err;

 	switch (ioc) {
 	case X86_IOC_RDMSR_REGS:
 		if (!(file->f_mode & FMODE_READ)) {
 			err = -EBADF;
 			break;
 		}
 		if (copy_from_user(&regs, uregs, sizeof regs)) {
 			err = -EFAULT;
 			break;
 		}
 		err = rdmsr_safe_regs_on_cpu(cpu, regs);
 		if (err)
 			break;
 		if (copy_to_user(uregs, &regs, sizeof regs))
 			err = -EFAULT;
 		break;

 	case X86_IOC_WRMSR_REGS:
 		if (!(file->f_mode & FMODE_WRITE)) {
 			err = -EBADF;
 			break;
 		}
 		if (copy_from_user(&regs, uregs, sizeof regs)) {
 			err = -EFAULT;
 			break;
 		}
 		err = wrmsr_safe_regs_on_cpu(cpu, regs);
 		if (err)
 			break;
 		if (copy_to_user(uregs, &regs, sizeof regs))
 			err = -EFAULT;
 		break;

 	default:
 		err = -ENOTTY;
 		break;
 	}

 	return err;
 }

 static int msr_open(struct inode *inode, struct file *file)
 {
 	unsigned int cpu = iminor(file_inode(file));
 	struct cpuinfo_x86 *c;

 	if (!capable(CAP_SYS_RAWIO))
 		return -EPERM;

 	if (cpu >= nr_cpu_ids || !cpu_online(cpu))
 		return -ENXIO;	/* No such CPU */

 	c = &cpu_data(cpu);
 	if (!cpu_has(c, X86_FEATURE_MSR))
 		return -EIO;	/* MSR not supported */

 	return 0;
 }

 /*
  * File operations we support
  */
 static const struct file_operations msr_fops = {
 	.owner = THIS_MODULE,
 	.llseek = msr_seek,
 	.read = msr_read,
 	.write = msr_write,
 	.open = msr_open,
 	.unlocked_ioctl = msr_ioctl,
 	.compat_ioctl = msr_ioctl,
 };

 static int msr_device_create(int cpu)
 {
 	struct device *dev;

 	dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL,
 			    "msr%d", cpu);
 	return IS_ERR(dev) ? PTR_ERR(dev) : 0;
 }

 static void msr_device_destroy(int cpu)
 {
 	device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
 }

 static int msr_class_cpu_callback(struct notifier_block *nfb,
 				  unsigned long action, void *hcpu)
 {
 	unsigned int cpu = (unsigned long)hcpu;
 	int err = 0;

 	switch (action) {
 	case CPU_UP_PREPARE:
 		err = msr_device_create(cpu);
 		break;
 	case CPU_UP_CANCELED:
 	case CPU_UP_CANCELED_FROZEN:
 	case CPU_DEAD:
 		msr_device_destroy(cpu);
 		break;
 	}
 	return notifier_from_errno(err);
 }

 static struct notifier_block __refdata msr_class_cpu_notifier = {
 	.notifier_call = msr_class_cpu_callback,
 };

 static char *msr_devnode(struct device *dev, umode_t *mode)
 {
 	return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
 }

 static int __init msr_init(void)
 {
 	int i, err = 0;
 	i = 0;

 	if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
 		printk(KERN_ERR "msr: unable to get major %d for msr\n",
 		       MSR_MAJOR);
 		err = -EBUSY;
 		goto out;
 	}
 	msr_class = class_create(THIS_MODULE, "msr");
 	if (IS_ERR(msr_class)) {
 		err = PTR_ERR(msr_class);
 		goto out_chrdev;
 	}
 	msr_class->devnode = msr_devnode;
 	get_online_cpus();
 	for_each_online_cpu(i) {
 		err = msr_device_create(i);
 		if (err != 0)
 			goto out_class;
 	}
 	register_hotcpu_notifier(&msr_class_cpu_notifier);
 	put_online_cpus();

 	err = 0;
 	goto out;

 out_class:
 	i = 0;
 	for_each_online_cpu(i)
 		msr_device_destroy(i);
 	put_online_cpus();
 	class_destroy(msr_class);
 out_chrdev:
 	__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
 out:
 	return err;
 }

 static void __exit msr_exit(void)
 {
 	int cpu = 0;
 	get_online_cpus();
 	for_each_online_cpu(cpu)
 		msr_device_destroy(cpu);
 	class_destroy(msr_class);
 	__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
 	unregister_hotcpu_notifier(&msr_class_cpu_notifier);
 	put_online_cpus();
 }

 module_init(msr_init);
 module_exit(msr_exit)

 MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
 MODULE_DESCRIPTION("x86 generic MSR driver");
 MODULE_LICENSE("GPL");
	/* ----------------------------------------------------------------------- *
	*
	* Copyright 2000-2008 H. Peter Anvin - All Rights Reserved
	* Copyright 2009 Intel Corporation; author: H. Peter Anvin
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
	* USA; either version 2 of the License, or (at your option) any later
	* version; incorporated herein by reference.
	*
	* ----------------------------------------------------------------------- */

	/*
	* x86 MSR access device
	*
	* This device is accessed by lseek() to the appropriate register number
	* and then read/write in chunks of 8 bytes. A larger size means multiple
	* reads or writes of the same register.
	*
	* This driver uses /dev/cpu/%d/msr where %d is the minor number, and on
	* an SMP box will direct the access to CPU %d.
	*/

	#include <linux/module.h>

	#include <linux/types.h>
	#include <linux/errno.h>
	#include <linux/fcntl.h>
	#include <linux/init.h>
	#include <linux/poll.h>
	#include <linux/smp.h>
	#include <linux/major.h>
	#include <linux/fs.h>
	#include <linux/device.h>
	#include <linux/cpu.h>
	#include <linux/notifier.h>
	#include <linux/uaccess.h>
	#include <linux/gfp.h>

	#include <asm/processor.h>
	#include <asm/msr.h>

	static struct class *msr_class;

	static loff_t msr_seek(struct file *file, loff_t offset, int orig)
	{
	loff_t ret;
	struct inode *inode = file_inode(file);

	mutex_lock(&inode->i_mutex);
	switch (orig) {
	case 0:
	file->f_pos = offset;
	ret = file->f_pos;
	break;
	case 1:
	file->f_pos += offset;
	ret = file->f_pos;
	break;
	default:
	ret = -EINVAL;
	}
	mutex_unlock(&inode->i_mutex);
	return ret;
	}

	static ssize_t msr_read(struct file file, char __user buf,
	size_t count, loff_t *ppos)
	{
	u32 __user tmp = (u32 __user ) buf;
	u32 data[2];
	u32 reg = *ppos;
	int cpu = iminor(file_inode(file));
	int err = 0;
	ssize_t bytes = 0;

	if (count % 8)
	return -EINVAL; /* Invalid chunk size */

	for (; count; count -= 8) {
	err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);
	if (err)
	break;
	if (copy_to_user(tmp, &data, 8)) {
	err = -EFAULT;
	break;
	}
	tmp += 2;
	bytes += 8;
	}

	return bytes ? bytes : err;
	}

	static ssize_t msr_write(struct file file, const char __user buf,
	size_t count, loff_t *ppos)
	{
	const u32 __user tmp = (const u32 __user )buf;
	u32 data[2];
	u32 reg = *ppos;
	int cpu = iminor(file_inode(file));
	int err = 0;
	ssize_t bytes = 0;

	if (count % 8)
	return -EINVAL; /* Invalid chunk size */

	for (; count; count -= 8) {
	if (copy_from_user(&data, tmp, 8)) {
	err = -EFAULT;
	break;
	}
	err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
	if (err)
	break;
	tmp += 2;
	bytes += 8;
	}

	return bytes ? bytes : err;
	}

	static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
	{
	u32 __user uregs = (u32 __user )arg;
	u32 regs[8];
	int cpu = iminor(file_inode(file));
	int err;

	switch (ioc) {
	case X86_IOC_RDMSR_REGS:
	if (!(file->f_mode & FMODE_READ)) {
	err = -EBADF;
	break;
	}
	if (copy_from_user(&regs, uregs, sizeof regs)) {
	err = -EFAULT;
	break;
	}
	err = rdmsr_safe_regs_on_cpu(cpu, regs);
	if (err)
	break;
	if (copy_to_user(uregs, &regs, sizeof regs))
	err = -EFAULT;
	break;

	case X86_IOC_WRMSR_REGS:
	if (!(file->f_mode & FMODE_WRITE)) {
	err = -EBADF;
	break;
	}
	if (copy_from_user(&regs, uregs, sizeof regs)) {
	err = -EFAULT;
	break;
	}
	err = wrmsr_safe_regs_on_cpu(cpu, regs);
	if (err)
	break;
	if (copy_to_user(uregs, &regs, sizeof regs))
	err = -EFAULT;
	break;

	default:
	err = -ENOTTY;
	break;
	}

	return err;
	}

	static int msr_open(struct inode inode, struct file file)
	{
	unsigned int cpu = iminor(file_inode(file));
	struct cpuinfo_x86 *c;

	if (!capable(CAP_SYS_RAWIO))
	return -EPERM;

	if (cpu >= nr_cpu_ids \|\| !cpu_online(cpu))
	return -ENXIO; /* No such CPU */

	c = &cpu_data(cpu);
	if (!cpu_has(c, X86_FEATURE_MSR))
	return -EIO; /* MSR not supported */

	return 0;
	}

	/*
	* File operations we support
	*/
	static const struct file_operations msr_fops = {
	.owner = THIS_MODULE,
	.llseek = msr_seek,
	.read = msr_read,
	.write = msr_write,
	.open = msr_open,
	.unlocked_ioctl = msr_ioctl,
	.compat_ioctl = msr_ioctl,
	};

	static int msr_device_create(int cpu)
	{
	struct device *dev;

	dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL,
	"msr%d", cpu);
	return IS_ERR(dev) ? PTR_ERR(dev) : 0;
	}

	static void msr_device_destroy(int cpu)
	{
	device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
	}

	static int msr_class_cpu_callback(struct notifier_block *nfb,
	unsigned long action, void *hcpu)
	{
	unsigned int cpu = (unsigned long)hcpu;
	int err = 0;

	switch (action) {
	case CPU_UP_PREPARE:
	err = msr_device_create(cpu);
	break;
	case CPU_UP_CANCELED:
	case CPU_UP_CANCELED_FROZEN:
	case CPU_DEAD:
	msr_device_destroy(cpu);
	break;
	}
	return notifier_from_errno(err);
	}

	static struct notifier_block __refdata msr_class_cpu_notifier = {
	.notifier_call = msr_class_cpu_callback,
	};

	static char msr_devnode(struct device dev, umode_t *mode)
	{
	return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
	}

	static int __init msr_init(void)
	{
	int i, err = 0;
	i = 0;

	if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
	printk(KERN_ERR "msr: unable to get major %d for msr\n",
	MSR_MAJOR);
	err = -EBUSY;
	goto out;
	}
	msr_class = class_create(THIS_MODULE, "msr");
	if (IS_ERR(msr_class)) {
	err = PTR_ERR(msr_class);
	goto out_chrdev;
	}
	msr_class->devnode = msr_devnode;
	get_online_cpus();
	for_each_online_cpu(i) {
	err = msr_device_create(i);
	if (err != 0)
	goto out_class;
	}
	register_hotcpu_notifier(&msr_class_cpu_notifier);
	put_online_cpus();

	err = 0;
	goto out;

	out_class:
	i = 0;
	for_each_online_cpu(i)
	msr_device_destroy(i);
	put_online_cpus();
	class_destroy(msr_class);
	out_chrdev:
	__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
	out:
	return err;
	}

	static void __exit msr_exit(void)
	{
	int cpu = 0;
	get_online_cpus();
	for_each_online_cpu(cpu)
	msr_device_destroy(cpu);
	class_destroy(msr_class);
	__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
	unregister_hotcpu_notifier(&msr_class_cpu_notifier);
	put_online_cpus();
	}

	module_init(msr_init);
	module_exit(msr_exit)

	MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
	MODULE_DESCRIPTION("x86 generic MSR driver");
	MODULE_LICENSE("GPL");