298 lines
6.4 KiB
C
298 lines
6.4 KiB
C
/* ----------------------------------------------------------------------- *
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*
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* Copyright 2000-2008 H. Peter Anvin - All Rights Reserved
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* Copyright 2009 Intel Corporation; author: H. Peter Anvin
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139,
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* USA; either version 2 of the License, or (at your option) any later
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* version; incorporated herein by reference.
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*
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* ----------------------------------------------------------------------- */
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/*
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* x86 MSR access device
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*
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* This device is accessed by lseek() to the appropriate register number
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* and then read/write in chunks of 8 bytes. A larger size means multiple
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* reads or writes of the same register.
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*
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* This driver uses /dev/cpu/%d/msr where %d is the minor number, and on
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* an SMP box will direct the access to CPU %d.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/fcntl.h>
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#include <linux/init.h>
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#include <linux/poll.h>
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#include <linux/smp.h>
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#include <linux/major.h>
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#include <linux/fs.h>
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#include <linux/device.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <linux/uaccess.h>
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#include <linux/gfp.h>
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#include <asm/processor.h>
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#include <asm/msr.h>
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#include <asm/system.h>
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static struct class *msr_class;
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static loff_t msr_seek(struct file *file, loff_t offset, int orig)
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{
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loff_t ret;
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struct inode *inode = file->f_mapping->host;
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mutex_lock(&inode->i_mutex);
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switch (orig) {
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case 0:
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file->f_pos = offset;
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ret = file->f_pos;
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break;
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case 1:
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file->f_pos += offset;
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ret = file->f_pos;
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break;
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default:
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ret = -EINVAL;
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}
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mutex_unlock(&inode->i_mutex);
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return ret;
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}
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static ssize_t msr_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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u32 __user *tmp = (u32 __user *) buf;
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u32 data[2];
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u32 reg = *ppos;
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int cpu = iminor(file->f_path.dentry->d_inode);
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int err = 0;
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ssize_t bytes = 0;
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if (count % 8)
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return -EINVAL; /* Invalid chunk size */
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for (; count; count -= 8) {
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err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);
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if (err)
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break;
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if (copy_to_user(tmp, &data, 8)) {
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err = -EFAULT;
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break;
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}
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tmp += 2;
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bytes += 8;
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}
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return bytes ? bytes : err;
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}
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static ssize_t msr_write(struct file *file, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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const u32 __user *tmp = (const u32 __user *)buf;
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u32 data[2];
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u32 reg = *ppos;
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int cpu = iminor(file->f_path.dentry->d_inode);
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int err = 0;
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ssize_t bytes = 0;
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if (count % 8)
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return -EINVAL; /* Invalid chunk size */
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for (; count; count -= 8) {
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if (copy_from_user(&data, tmp, 8)) {
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err = -EFAULT;
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break;
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}
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err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
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if (err)
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break;
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tmp += 2;
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bytes += 8;
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}
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return bytes ? bytes : err;
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}
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static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
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{
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u32 __user *uregs = (u32 __user *)arg;
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u32 regs[8];
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int cpu = iminor(file->f_path.dentry->d_inode);
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int err;
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switch (ioc) {
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case X86_IOC_RDMSR_REGS:
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if (!(file->f_mode & FMODE_READ)) {
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err = -EBADF;
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break;
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}
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if (copy_from_user(®s, uregs, sizeof regs)) {
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err = -EFAULT;
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break;
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}
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err = rdmsr_safe_regs_on_cpu(cpu, regs);
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if (err)
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break;
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if (copy_to_user(uregs, ®s, sizeof regs))
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err = -EFAULT;
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break;
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case X86_IOC_WRMSR_REGS:
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if (!(file->f_mode & FMODE_WRITE)) {
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err = -EBADF;
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break;
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}
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if (copy_from_user(®s, uregs, sizeof regs)) {
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err = -EFAULT;
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break;
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}
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err = wrmsr_safe_regs_on_cpu(cpu, regs);
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if (err)
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break;
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if (copy_to_user(uregs, ®s, sizeof regs))
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err = -EFAULT;
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break;
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default:
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err = -ENOTTY;
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break;
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}
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return err;
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}
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static int msr_open(struct inode *inode, struct file *file)
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{
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unsigned int cpu;
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struct cpuinfo_x86 *c;
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cpu = iminor(file->f_path.dentry->d_inode);
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if (cpu >= nr_cpu_ids || !cpu_online(cpu))
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return -ENXIO; /* No such CPU */
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c = &cpu_data(cpu);
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if (!cpu_has(c, X86_FEATURE_MSR))
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return -EIO; /* MSR not supported */
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return 0;
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}
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/*
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* File operations we support
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*/
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static const struct file_operations msr_fops = {
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.owner = THIS_MODULE,
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.llseek = msr_seek,
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.read = msr_read,
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.write = msr_write,
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.open = msr_open,
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.unlocked_ioctl = msr_ioctl,
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.compat_ioctl = msr_ioctl,
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};
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static int __cpuinit msr_device_create(int cpu)
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{
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struct device *dev;
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dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL,
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"msr%d", cpu);
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return IS_ERR(dev) ? PTR_ERR(dev) : 0;
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}
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static void msr_device_destroy(int cpu)
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{
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device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
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}
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static int __cpuinit msr_class_cpu_callback(struct notifier_block *nfb,
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unsigned long action, void *hcpu)
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{
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unsigned int cpu = (unsigned long)hcpu;
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int err = 0;
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switch (action) {
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case CPU_UP_PREPARE:
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err = msr_device_create(cpu);
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break;
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case CPU_UP_CANCELED:
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case CPU_UP_CANCELED_FROZEN:
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case CPU_DEAD:
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msr_device_destroy(cpu);
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break;
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}
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return notifier_from_errno(err);
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}
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static struct notifier_block __refdata msr_class_cpu_notifier = {
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.notifier_call = msr_class_cpu_callback,
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};
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static char *msr_devnode(struct device *dev, mode_t *mode)
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{
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return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
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}
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static int __init msr_init(void)
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{
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int i, err = 0;
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i = 0;
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if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
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printk(KERN_ERR "msr: unable to get major %d for msr\n",
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MSR_MAJOR);
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err = -EBUSY;
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goto out;
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}
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msr_class = class_create(THIS_MODULE, "msr");
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if (IS_ERR(msr_class)) {
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err = PTR_ERR(msr_class);
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goto out_chrdev;
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}
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msr_class->devnode = msr_devnode;
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for_each_online_cpu(i) {
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err = msr_device_create(i);
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if (err != 0)
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goto out_class;
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}
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register_hotcpu_notifier(&msr_class_cpu_notifier);
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err = 0;
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goto out;
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out_class:
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i = 0;
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for_each_online_cpu(i)
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msr_device_destroy(i);
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class_destroy(msr_class);
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out_chrdev:
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__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
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out:
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return err;
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}
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static void __exit msr_exit(void)
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{
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int cpu = 0;
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for_each_online_cpu(cpu)
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msr_device_destroy(cpu);
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class_destroy(msr_class);
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__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
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unregister_hotcpu_notifier(&msr_class_cpu_notifier);
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}
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module_init(msr_init);
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module_exit(msr_exit)
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MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
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MODULE_DESCRIPTION("x86 generic MSR driver");
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MODULE_LICENSE("GPL");
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