Release 4.14 arch/x86/kernel/cpuid.c

/* ----------------------------------------------------------------------- *
 *
 *   Copyright 2000-2008 H. Peter Anvin - All Rights Reserved
 *
 *   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 CPUID access device
 *
 * This device is accessed by lseek() to the appropriate CPUID level
 * and then read in chunks of 16 bytes.  A larger size means multiple
 * reads of consecutive levels.
 *
 * The lower 32 bits of the file position is used as the incoming %eax,
 * and the upper 32 bits of the file position as the incoming %ecx,
 * the latter intended for "counting" eax levels like eax=4.
 *
 * This driver uses /dev/cpu/%d/cpuid 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 *cpuid_class;

static enum cpuhp_state cpuhp_cpuid_state;



static void cpuid_smp_cpuid(void *cmd_block)
{
	struct cpuid_regs *cmd = (struct cpuid_regs *)cmd_block;

	cpuid_count(cmd->eax, cmd->ecx,
		    &cmd->eax, &cmd->ebx, &cmd->ecx, &cmd->edx);
}

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39
73.58%
2
66.67%
H. Peter Anvin
14
26.42%
1
33.33%
Total
53
100.00%
3
100.00%



static ssize_t cpuid_read(struct file *file, char __user *buf,
			  size_t count, loff_t *ppos)
{
	char __user *tmp = buf;
	struct cpuid_regs cmd;
	int cpu = iminor(file_inode(file));
	u64 pos = *ppos;
	ssize_t bytes = 0;
	int err = 0;

	if (count % 16)
		return -EINVAL;	/* Invalid chunk size */

	for (; count; count -= 16) {
		cmd.eax = pos;
		cmd.ecx = pos >> 32;
		err = smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1);
		if (err)
			break;
		if (copy_to_user(tmp, &cmd, 16)) {
			err = -EFAULT;
			break;
		}
		tmp += 16;
		bytes += 16;
		*ppos = ++pos;
	}

	return bytes ? bytes : err;
}

Contributors
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Linus Torvalds (pre-git)
86
54.78%
1
14.29%
H. Peter Anvin
63
40.13%
3
42.86%
Al Viro
8
5.10%
3
42.86%
Total
157
100.00%
7
100.00%



static int cpuid_open(struct inode *inode, struct file *file)
{
	unsigned int cpu;
	struct cpuinfo_x86 *c;

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

	c = &cpu_data(cpu);
	if (c->cpuid_level < 0)
		return -EIO;	/* CPUID not supported */

	return 0;
}

Contributors
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Linus Torvalds (pre-git)
42
55.26%
2
22.22%
Jonathan Corbet
17
22.37%
1
11.11%
Andrew Morton
7
9.21%
2
22.22%
John Kacur
5
6.58%
1
11.11%
Al Viro
4
5.26%
2
22.22%
Mike Travis
1
1.32%
1
11.11%
Total
76
100.00%
9
100.00%

/*
 * File operations we support
 */

static const struct file_operations cpuid_fops = {
	.owner = THIS_MODULE,
	.llseek = no_seek_end_llseek,
	.read = cpuid_read,
	.open = cpuid_open,
};



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

	dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu), NULL,
			    "cpu%d", cpu);
	return PTR_ERR_OR_ZERO(dev);
}

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Hanna V. Linder
26
60.47%
2
22.22%
Greg Kroah-Hartman
10
23.26%
4
44.44%
Akinobu Mita
5
11.63%
1
11.11%
Fabian Frederick
1
2.33%
1
11.11%
Sebastian Andrzej Siewior
1
2.33%
1
11.11%
Total
43
100.00%
9
100.00%



static int cpuid_device_destroy(unsigned int cpu)
{
	device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
	return 0;
}

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



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

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



static int __init cpuid_init(void)
{
	int err;

	if (__register_chrdev(CPUID_MAJOR, 0, NR_CPUS,
			      "cpu/cpuid", &cpuid_fops)) {
		printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
		       CPUID_MAJOR);
		return -EBUSY;
	}
	cpuid_class = class_create(THIS_MODULE, "cpuid");
	if (IS_ERR(cpuid_class)) {
		err = PTR_ERR(cpuid_class);
		goto out_chrdev;
	}
	cpuid_class->devnode = cpuid_devnode;

	err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/cpuid:online",
				cpuid_device_create, cpuid_device_destroy);
	if (err < 0)
		goto out_class;

	cpuhp_cpuid_state = err;
	return 0;

out_class:
	class_destroy(cpuid_class);
out_chrdev:
	__unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
	return err;
}
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Hanna V. Linder
68
53.12%
2
20.00%
Linus Torvalds (pre-git)
26
20.31%
1
10.00%
Sebastian Andrzej Siewior
10
7.81%
1
10.00%
H. Peter Anvin
10
7.81%
1
10.00%
Kay Sievers
6
4.69%
2
20.00%
Thomas Gleixner
5
3.91%
1
10.00%
Greg Kroah-Hartman
2
1.56%
1
10.00%
Adrian Bunk
1
0.78%
1
10.00%
Total
128
100.00%
10
100.00%


module_init(cpuid_init);



static void __exit cpuid_exit(void)
{
	cpuhp_remove_state(cpuhp_cpuid_state);
	class_destroy(cpuid_class);
	__unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
}
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Linus Torvalds (pre-git)
14
46.67%
2
22.22%
Russ Anderson
5
16.67%
1
11.11%
Hanna V. Linder
5
16.67%
1
11.11%
Greg Kroah-Hartman
3
10.00%
2
22.22%
Thomas Gleixner
1
3.33%
1
11.11%
Adrian Bunk
1
3.33%
1
11.11%
Sebastian Andrzej Siewior
1
3.33%
1
11.11%
Total
30
100.00%
9
100.00%


module_exit(cpuid_exit);

MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
MODULE_DESCRIPTION("x86 generic CPUID driver");
MODULE_LICENSE("GPL");
Overall Contributors
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Linus Torvalds (pre-git)
269
40.88%
3
7.50%
Hanna V. Linder
116
17.63%
2
5.00%
H. Peter Anvin
89
13.53%
4
10.00%
Kay Sievers
36
5.47%
2
5.00%
Akinobu Mita
24
3.65%
1
2.50%
Jonathan Corbet
17
2.58%
1
2.50%
Greg Kroah-Hartman
16
2.43%
6
15.00%
Thomas Gleixner
16
2.43%
1
2.50%
Sebastian Andrzej Siewior
15
2.28%
1
2.50%
Al Viro
14
2.13%
5
12.50%
Andrew Morton
9
1.37%
3
7.50%
Rusty Russell
8
1.22%
1
2.50%
Linus Torvalds
5
0.76%
1
2.50%
John Kacur
5
0.76%
1
2.50%
Russ Anderson
5
0.76%
1
2.50%
Tejun Heo
3
0.46%
1
2.50%
Dave Jones
3
0.46%
1
2.50%
Jaswinder Singh Rajput
3
0.46%
1
2.50%
Adrian Bunk
2
0.30%
1
2.50%
Arjan van de Ven
1
0.15%
1
2.50%
Mike Travis
1
0.15%
1
2.50%
Fabian Frederick
1
0.15%
1
2.50%
Total
658
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40
100.00%
Directory: arch/x86/kernel

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