Release 4.14 arch/x86/kernel/msr.c

/* ----------------------------------------------------------------------- *
 *
 *   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.
 */


#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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


static struct class *msr_class;

static enum cpuhp_state cpuhp_msr_state;



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;
}

Contributors
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CommitProp
Linus Torvalds (pre-git)
120
79.47%
1
14.29%
H. Peter Anvin
23
15.23%
1
14.29%
Al Viro
6
3.97%
3
42.86%
Dave Jones
1
0.66%
1
14.29%
Nicolas Boichat
1
0.66%
1
14.29%
Total
151
100.00%
7
100.00%



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;
}

Contributors
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Tokens
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CommitProp
Linus Torvalds (pre-git)
121
79.61%
1
14.29%
H. Peter Anvin
23
15.13%
1
14.29%
Al Viro
6
3.95%
3
42.86%
Dave Jones
1
0.66%
1
14.29%
Nicolas Boichat
1
0.66%
1
14.29%
Total
152
100.00%
7
100.00%



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;
}

Contributors
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CommitProp
H. Peter Anvin
216
98.63%
1
50.00%
Al Viro
3
1.37%
1
50.00%
Total
219
100.00%
2
100.00%



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;
}

Contributors
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Linus Torvalds (pre-git)
44
50.00%
3
27.27%
Alan Cox
12
13.64%
1
9.09%
Al Viro
8
9.09%
1
9.09%
Jonathan Corbet
8
9.09%
1
9.09%
Andrew Morton
7
7.95%
2
18.18%
Frédéric Weisbecker
5
5.68%
1
9.09%
Brian Gerst
3
3.41%
1
9.09%
Mike Travis
1
1.14%
1
9.09%
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88
100.00%
11
100.00%

/*
 * File operations we support
 */

static const struct file_operations msr_fops = {
	.owner = THIS_MODULE,
	.llseek = no_seek_end_llseek,
	.read = msr_read,
	.write = msr_write,
	.open = msr_open,
	.unlocked_ioctl = msr_ioctl,
	.compat_ioctl = msr_ioctl,
};



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

	dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL,
			    "msr%d", cpu);
	return PTR_ERR_OR_ZERO(dev);
}

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Hanna V. Linder
27
62.79%
1
12.50%
Greg Kroah-Hartman
10
23.26%
4
50.00%
Akinobu Mita
4
9.30%
1
12.50%
Sebastian Andrzej Siewior
1
2.33%
1
12.50%
Fabian Frederick
1
2.33%
1
12.50%
Total
43
100.00%
8
100.00%



static int msr_device_destroy(unsigned int cpu)
{
	device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
	return 0;
}

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Akinobu Mita
19
76.00%
1
33.33%
Sebastian Andrzej Siewior
3
12.00%
1
33.33%
Hanna V. Linder
3
12.00%
1
33.33%
Total
25
100.00%
3
100.00%



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

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Kay Sievers
30
96.77%
2
66.67%
Al Viro
1
3.23%
1
33.33%
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31
100.00%
3
100.00%



static int __init msr_init(void)
{
	int err;

	if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
		pr_err("unable to get major %d for msr\n", MSR_MAJOR);
		return -EBUSY;
	}
	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;

	err  = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/msr:online",
				 msr_device_create, msr_device_destroy);
	if (err < 0)
		goto out_class;
	cpuhp_msr_state = err;
	return 0;

out_class:
	class_destroy(msr_class);
out_chrdev:
	__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
	return err;
}
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Hanna V. Linder
60
47.24%
1
11.11%
Linus Torvalds (pre-git)
30
23.62%
1
11.11%
Sebastian Andrzej Siewior
16
12.60%
1
11.11%
H. Peter Anvin
10
7.87%
1
11.11%
Kay Sievers
6
4.72%
2
22.22%
Fabian Frederick
2
1.57%
1
11.11%
Greg Kroah-Hartman
2
1.57%
1
11.11%
Adrian Bunk
1
0.79%
1
11.11%
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127
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9
100.00%


module_init(msr_init);



static void __exit msr_exit(void)
{
	cpuhp_remove_state(cpuhp_msr_state);
	class_destroy(msr_class);
	__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
}
Contributors
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Linus Torvalds (pre-git)
14
46.67%
2
28.57%
Hanna V. Linder
7
23.33%
1
14.29%
Russ Anderson
5
16.67%
1
14.29%
Sebastian Andrzej Siewior
2
6.67%
1
14.29%
Adrian Bunk
1
3.33%
1
14.29%
Greg Kroah-Hartman
1
3.33%
1
14.29%
Total
30
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7
100.00%

module_exit(msr_exit)

MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
MODULE_DESCRIPTION("x86 generic MSR driver");
MODULE_LICENSE("GPL");
Overall Contributors
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Linus Torvalds (pre-git)
395
39.42%
4
9.30%
H. Peter Anvin
283
28.24%
3
6.98%
Hanna V. Linder
111
11.08%
1
2.33%
Kay Sievers
36
3.59%
2
4.65%
Sebastian Andrzej Siewior
32
3.19%
1
2.33%
Al Viro
25
2.50%
5
11.63%
Akinobu Mita
23
2.30%
1
2.33%
Greg Kroah-Hartman
14
1.40%
5
11.63%
Alan Cox
12
1.20%
1
2.33%
Fabian Frederick
10
1.00%
2
4.65%
Rusty Russell
10
1.00%
1
2.33%
Jonathan Corbet
8
0.80%
1
2.33%
Andrew Morton
7
0.70%
2
4.65%
Dave Jones
6
0.60%
3
6.98%
Russ Anderson
5
0.50%
1
2.33%
Frédéric Weisbecker
5
0.50%
1
2.33%
Linus Torvalds
5
0.50%
1
2.33%
Tejun Heo
3
0.30%
1
2.33%
Brian Gerst
3
0.30%
1
2.33%
Adrian Bunk
2
0.20%
1
2.33%
Jaswinder Singh Rajput
2
0.20%
1
2.33%
Nicolas Boichat
2
0.20%
1
2.33%
Borislav Petkov
1
0.10%
1
2.33%
Mike Travis
1
0.10%
1
2.33%
Arjan van de Ven
1
0.10%
1
2.33%
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Directory: arch/x86/kernel

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