cregit-Linux how code gets into the kernel

Release 4.7 arch/x86/kernel/msr.c

Directory: arch/x86/kernel
/* ----------------------------------------------------------------------- *
 *
 *   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 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
PersonTokensPropCommitsCommitProp
pre-gitpre-git12079.47%114.29%


h. peter anvinh. peter anvin2315.23%114.29%


al viroal viro63.97%342.86%


dave jonesdave jones10.66%114.29%


nicolas boichatnicolas boichat10.66%114.29%


Total151100.00%7100.00%






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
PersonTokensPropCommitsCommitProp
pre-gitpre-git12179.61%114.29%


h. peter anvinh. peter anvin2315.13%114.29%


al viroal viro63.95%342.86%


nicolas boichatnicolas boichat10.66%114.29%


dave jonesdave jones10.66%114.29%


Total152100.00%7100.00%






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
PersonTokensPropCommitsCommitProp
h. peter anvinh. peter anvin21698.63%150.00%


al viroal viro31.37%150.00%


Total219100.00%2100.00%






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
PersonTokensPropCommitsCommitProp
pre-gitpre-git4450.00%327.27%


alan coxalan cox1213.64%19.09%


jonathan corbetjonathan corbet89.09%19.09%


al viroal viro89.09%19.09%


andrew mortonandrew morton77.95%218.18%


frederic weisbeckerfrederic weisbecker55.68%19.09%


brian gerstbrian gerst33.41%19.09%


mike travismike travis11.14%19.09%


Total88100.00%11100.00%



/*
 * 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(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);
}


Contributors
PersonTokensPropCommitsCommitProp
hanna linderhanna linder2764.29%114.29%


greg kroah-hartmangreg kroah-hartman1023.81%457.14%


akinobu mitaakinobu mita49.52%114.29%


fabian frederickfabian frederick12.38%114.29%


Total42100.00%7100.00%






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


Contributors
PersonTokensPropCommitsCommitProp
akinobu mitaakinobu mita21100.00%1100.00%


Total21100.00%1100.00%






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);
}


Contributors
PersonTokensPropCommitsCommitProp
hanna linderhanna linder5170.83%116.67%


akinobu mitaakinobu mita1520.83%233.33%


rafael j. wysockirafael j. wysocki56.94%233.33%


greg kroah-hartmangreg kroah-hartman11.39%116.67%


Total72100.00%6100.00%




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));
}


Contributors
PersonTokensPropCommitsCommitProp
kay sieverskay sievers3096.77%266.67%


al viroal viro13.23%133.33%


Total31100.00%3100.00%






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

	if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
		pr_err("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;

	cpu_notifier_register_begin();
	for_each_online_cpu(i) {
		err = msr_device_create(i);
		if (err != 0)
			goto out_class;
	}
	__register_hotcpu_notifier(&msr_class_cpu_notifier);
	cpu_notifier_register_done();

	err = 0;
	goto out;

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


Contributors
PersonTokensPropCommitsCommitProp
hanna linderhanna linder10662.72%18.33%


pre-gitpre-git3017.75%18.33%


h. peter anvinh. peter anvin105.92%18.33%


kay sieverskay sievers63.55%216.67%


silas boyd-wickizersilas boyd-wickizer63.55%18.33%


srivatsa s. bhatsrivatsa s. bhat42.37%18.33%


greg kroah-hartmangreg kroah-hartman31.78%216.67%


fabian frederickfabian frederick21.18%18.33%


akinobu mitaakinobu mita10.59%18.33%


adrian bunkadrian bunk10.59%18.33%


Total169100.00%12100.00%






static void __exit msr_exit(void)
{
	int cpu = 0;

	cpu_notifier_register_begin();
	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);
	cpu_notifier_register_done();
}


Contributors
PersonTokensPropCommitsCommitProp
hanna linderhanna linder2243.14%111.11%


pre-gitpre-git1427.45%222.22%


russ andersonruss anderson59.80%111.11%


silas boyd-wickizersilas boyd-wickizer47.84%111.11%


srivatsa s. bhatsrivatsa s. bhat35.88%111.11%


greg kroah-hartmangreg kroah-hartman11.96%111.11%


akinobu mitaakinobu mita11.96%111.11%


adrian bunkadrian bunk11.96%111.11%


Total51100.00%9100.00%




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");

Overall Contributors
PersonTokensPropCommitsCommitProp
pre-gitpre-git40035.09%48.33%


h. peter anvinh. peter anvin28324.82%36.25%


hanna linderhanna linder23220.35%12.08%


akinobu mitaakinobu mita423.68%24.17%


kay sieverskay sievers363.16%24.17%


al viroal viro252.19%510.42%


greg kroah-hartmangreg kroah-hartman161.40%510.42%


alan coxalan cox121.05%12.08%


rusty russellrusty russell100.88%12.08%


silas boyd-wickizersilas boyd-wickizer100.88%12.08%


fabian frederickfabian frederick100.88%24.17%


jonathan corbetjonathan corbet80.70%12.08%


andrew mortonandrew morton70.61%24.17%


srivatsa s. bhatsrivatsa s. bhat70.61%12.08%


dave jonesdave jones60.53%36.25%


linus torvaldslinus torvalds50.44%12.08%


frederic weisbeckerfrederic weisbecker50.44%12.08%


russ andersonruss anderson50.44%12.08%


rafael j. wysockirafael j. wysocki50.44%24.17%


tejun heotejun heo30.26%12.08%


brian gerstbrian gerst30.26%12.08%


jaswinder singh rajputjaswinder singh rajput20.18%12.08%


nicolas boichatnicolas boichat20.18%12.08%


adrian bunkadrian bunk20.18%12.08%


mike travismike travis10.09%12.08%


arjan van de venarjan van de ven10.09%12.08%


sam ravnborgsam ravnborg10.09%12.08%


borislav petkovborislav petkov10.09%12.08%


Total1140100.00%48100.00%

  
Directory: arch/x86/kernel



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