1 files changed, 224 insertions, 0 deletions

diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
new file mode 100644
index 00000000000..0c1069b8d63
--- /dev/null
+++ b/arch/x86/kernel/msr.c
@@ -0,0 +1,224 @@
+/* ----------------------------------------------------------------------- *
+ *   
+ *   Copyright 2000 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.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * msr.c
+ *
+ * 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.
+ */
+
+#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/smp_lock.h>
+#include <linux/major.h>
+#include <linux/fs.h>
+#include <linux/device.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+
+#include <asm/processor.h>
+#include <asm/msr.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+
+static struct class *msr_class;
+
+static loff_t msr_seek(struct file *file, loff_t offset, int orig)
+{
+        loff_t ret = -EINVAL;
+
+        lock_kernel();
+        switch (orig) {
+        case 0:
+                file->f_pos = offset;
+                ret = file->f_pos;
+                break;
+        case 1:
+                file->f_pos += offset;
+                ret = file->f_pos;
+        }
+        unlock_kernel();
+        return ret;
+}
+
+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->f_path.dentry->d_inode);
+        int err;
+
+        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)
+                        return -EIO;
+                if (copy_to_user(tmp, &data, 8))
+                        return -EFAULT;
+                tmp += 2;
+        }
+
+        return ((char __user *)tmp) - buf;
+}
+
+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->f_path.dentry->d_inode);
+        int err;
+
+        if (count % 8)
+                return -EINVAL; /* Invalid chunk size */
+
+        for (; count; count -= 8) {
+                if (copy_from_user(&data, tmp, 8))
+                        return -EFAULT;
+                err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
+                if (err)
+                        return -EIO;
+                tmp += 2;
+        }
+
+        return ((char __user *)tmp) - buf;
+}
+
+static int msr_open(struct inode *inode, struct file *file)
+{
+        unsigned int cpu = iminor(file->f_path.dentry->d_inode);
+        struct cpuinfo_x86 *c = &(cpu_data)[cpu];
+
+        if (cpu >= NR_CPUS || !cpu_online(cpu))
+                return -ENXIO;  /* No such CPU */
+        if (!cpu_has(c, X86_FEATURE_MSR))
+                return -EIO;    /* MSR not supported */
+
+        return 0;
+}
+
+/*
+ * File operations we support
+ */
+static const struct file_operations msr_fops = {
+        .owner = THIS_MODULE,
+        .llseek = msr_seek,
+        .read = msr_read,
+        .write = msr_write,
+        .open = msr_open,
+};
+
+static int msr_device_create(int i)
+{
+        int err = 0;
+        struct device *dev;
+
+        dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, i), "msr%d",i);
+        if (IS_ERR(dev))
+                err = PTR_ERR(dev);
+        return err;
+}
+
+static int msr_class_cpu_callback(struct notifier_block *nfb,
+                                unsigned long action, void *hcpu)
+{
+        unsigned int cpu = (unsigned long)hcpu;
+
+        switch (action) {
+        case CPU_ONLINE:
+        case CPU_ONLINE_FROZEN:
+                msr_device_create(cpu);
+                break;
+        case CPU_DEAD:
+        case CPU_DEAD_FROZEN:
+                device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
+                break;
+        }
+        return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata msr_class_cpu_notifier =
+{
+        .notifier_call = msr_class_cpu_callback,
+};
+
+static int __init msr_init(void)
+{
+        int i, err = 0;
+        i = 0;
+
+        if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
+                printk(KERN_ERR "msr: 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;
+        }
+        for_each_online_cpu(i) {
+                err = msr_device_create(i);
+                if (err != 0)
+                        goto out_class;
+        }
+        register_hotcpu_notifier(&msr_class_cpu_notifier);
+
+        err = 0;
+        goto out;
+
+out_class:
+        i = 0;
+        for_each_online_cpu(i)
+                device_destroy(msr_class, MKDEV(MSR_MAJOR, i));
+        class_destroy(msr_class);
+out_chrdev:
+        unregister_chrdev(MSR_MAJOR, "cpu/msr");
+out:
+        return err;
+}
+
+static void __exit msr_exit(void)
+{
+        int cpu = 0;
+        for_each_online_cpu(cpu)
+                device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
+        class_destroy(msr_class);
+        unregister_chrdev(MSR_MAJOR, "cpu/msr");
+        unregister_hotcpu_notifier(&msr_class_cpu_notifier);
+}
+
+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");