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Commit ff55df53 authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

x86, msr: Export the register-setting MSR functions via /dev/*/msr 



Make it possible to access the all-register-setting/getting MSR
functions via the MSR driver.  This is implemented as an ioctl() on
the standard MSR device node.

Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <petkovbb@gmail.com>
parent 8b956bf1

Documentation/ioctl/ioctl-number.txt

+1 −0
Original line number Diff line number Diff line
@@ -121,6 +121,7 @@ Code Seq# Include File Comments 
'c'	00-7F	linux/comstats.h	conflict!

'c'	00-7F	linux/coda.h		conflict!

'c'	80-9F	arch/s390/include/asm/chsc.h

'c'	A0-AF   arch/x86/include/asm/msr.h

'd'	00-FF	linux/char/drm/drm/h	conflict!

'd'	F0-FF	linux/digi1.h

'e'	all	linux/digi1.h		conflict!

arch/x86/include/asm/msr.h

+8 −2
Original line number Diff line number Diff line
@@ -3,10 +3,16 @@ 


#include <asm/msr-index.h>



#ifdef __KERNEL__

#ifndef __ASSEMBLY__



#include <linux/types.h>

#include <linux/ioctl.h>



#define X86_IOC_RDMSR_REGS	_IOWR('c', 0xA0, __u32[8])

#define X86_IOC_WRMSR_REGS	_IOWR('c', 0xA1, __u32[8])



#ifdef __KERNEL__



#include <asm/asm.h>

#include <asm/errno.h>

#include <asm/cpumask.h>
@@ -286,6 +292,6 @@ static inline int wrmsr_safe_regs_on_cpu(unsigned int cpu, u32 regs[8]) 
	return wrmsr_safe_regs(regs);

}

#endif  /* CONFIG_SMP */

#endif /* __ASSEMBLY__ */

#endif /* __KERNEL__ */

#endif /* __ASSEMBLY__ */

#endif /* _ASM_X86_MSR_H */

arch/x86/kernel/msr.c

+51 −0
Original line number Diff line number Diff line 
/* ----------------------------------------------------------------------- *

 *

 *   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
@@ -121,6 +122,54 @@ static ssize_t msr_write(struct file *file, const char __user *buf, 
	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->f_path.dentry->d_inode);

	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->f_path.dentry->d_inode);
@@ -151,6 +200,8 @@ static const struct file_operations msr_fops = { 
	.read = msr_read,

	.write = msr_write,

	.open = msr_open,

	.unlocked_ioctl = msr_ioctl,

	.compat_ioctl = msr_ioctl,

};



static int __cpuinit msr_device_create(int cpu)