1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25#include <linux/module.h>
26
27#include <linux/types.h>
28#include <linux/errno.h>
29#include <linux/fcntl.h>
30#include <linux/init.h>
31#include <linux/poll.h>
32#include <linux/smp.h>
33#include <linux/smp_lock.h>
34#include <linux/major.h>
35#include <linux/fs.h>
36#include <linux/device.h>
37#include <linux/cpu.h>
38#include <linux/notifier.h>
39#include <linux/uaccess.h>
40
41#include <asm/processor.h>
42#include <asm/msr.h>
43#include <asm/system.h>
44
45static struct class *msr_class;
46
47static loff_t msr_seek(struct file *file, loff_t offset, int orig)
48{
49 loff_t ret;
50 struct inode *inode = file->f_mapping->host;
51
52 mutex_lock(&inode->i_mutex);
53 switch (orig) {
54 case 0:
55 file->f_pos = offset;
56 ret = file->f_pos;
57 break;
58 case 1:
59 file->f_pos += offset;
60 ret = file->f_pos;
61 break;
62 default:
63 ret = -EINVAL;
64 }
65 mutex_unlock(&inode->i_mutex);
66 return ret;
67}
68
69static ssize_t msr_read(struct file *file, char __user *buf,
70 size_t count, loff_t *ppos)
71{
72 u32 __user *tmp = (u32 __user *) buf;
73 u32 data[2];
74 u32 reg = *ppos;
75 int cpu = iminor(file->f_path.dentry->d_inode);
76 int err = 0;
77 ssize_t bytes = 0;
78
79 if (count % 8)
80 return -EINVAL;
81
82 for (; count; count -= 8) {
83 err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);
84 if (err)
85 break;
86 if (copy_to_user(tmp, &data, 8)) {
87 err = -EFAULT;
88 break;
89 }
90 tmp += 2;
91 bytes += 8;
92 }
93
94 return bytes ? bytes : err;
95}
96
97static ssize_t msr_write(struct file *file, const char __user *buf,
98 size_t count, loff_t *ppos)
99{
100 const u32 __user *tmp = (const u32 __user *)buf;
101 u32 data[2];
102 u32 reg = *ppos;
103 int cpu = iminor(file->f_path.dentry->d_inode);
104 int err = 0;
105 ssize_t bytes = 0;
106
107 if (count % 8)
108 return -EINVAL;
109
110 for (; count; count -= 8) {
111 if (copy_from_user(&data, tmp, 8)) {
112 err = -EFAULT;
113 break;
114 }
115 err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
116 if (err)
117 break;
118 tmp += 2;
119 bytes += 8;
120 }
121
122 return bytes ? bytes : err;
123}
124
125static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
126{
127 u32 __user *uregs = (u32 __user *)arg;
128 u32 regs[8];
129 int cpu = iminor(file->f_path.dentry->d_inode);
130 int err;
131
132 switch (ioc) {
133 case X86_IOC_RDMSR_REGS:
134 if (!(file->f_mode & FMODE_READ)) {
135 err = -EBADF;
136 break;
137 }
138 if (copy_from_user(®s, uregs, sizeof regs)) {
139 err = -EFAULT;
140 break;
141 }
142 err = rdmsr_safe_regs_on_cpu(cpu, regs);
143 if (err)
144 break;
145 if (copy_to_user(uregs, ®s, sizeof regs))
146 err = -EFAULT;
147 break;
148
149 case X86_IOC_WRMSR_REGS:
150 if (!(file->f_mode & FMODE_WRITE)) {
151 err = -EBADF;
152 break;
153 }
154 if (copy_from_user(®s, uregs, sizeof regs)) {
155 err = -EFAULT;
156 break;
157 }
158 err = wrmsr_safe_regs_on_cpu(cpu, regs);
159 if (err)
160 break;
161 if (copy_to_user(uregs, ®s, sizeof regs))
162 err = -EFAULT;
163 break;
164
165 default:
166 err = -ENOTTY;
167 break;
168 }
169
170 return err;
171}
172
173static int msr_open(struct inode *inode, struct file *file)
174{
175 unsigned int cpu = iminor(file->f_path.dentry->d_inode);
176 struct cpuinfo_x86 *c = &cpu_data(cpu);
177 int ret = 0;
178
179 lock_kernel();
180 cpu = iminor(file->f_path.dentry->d_inode);
181
182 if (cpu >= nr_cpu_ids || !cpu_online(cpu)) {
183 ret = -ENXIO;
184 goto out;
185 }
186 c = &cpu_data(cpu);
187 if (!cpu_has(c, X86_FEATURE_MSR))
188 ret = -EIO;
189out:
190 unlock_kernel();
191 return ret;
192}
193
194
195
196
197static const struct file_operations msr_fops = {
198 .owner = THIS_MODULE,
199 .llseek = msr_seek,
200 .read = msr_read,
201 .write = msr_write,
202 .open = msr_open,
203 .unlocked_ioctl = msr_ioctl,
204 .compat_ioctl = msr_ioctl,
205};
206
207static int __cpuinit msr_device_create(int cpu)
208{
209 struct device *dev;
210
211 dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL,
212 "msr%d", cpu);
213 return IS_ERR(dev) ? PTR_ERR(dev) : 0;
214}
215
216static void msr_device_destroy(int cpu)
217{
218 device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
219}
220
221static int __cpuinit msr_class_cpu_callback(struct notifier_block *nfb,
222 unsigned long action, void *hcpu)
223{
224 unsigned int cpu = (unsigned long)hcpu;
225 int err = 0;
226
227 switch (action) {
228 case CPU_UP_PREPARE:
229 err = msr_device_create(cpu);
230 break;
231 case CPU_UP_CANCELED:
232 case CPU_UP_CANCELED_FROZEN:
233 case CPU_DEAD:
234 msr_device_destroy(cpu);
235 break;
236 }
237 return err ? NOTIFY_BAD : NOTIFY_OK;
238}
239
240static struct notifier_block __refdata msr_class_cpu_notifier = {
241 .notifier_call = msr_class_cpu_callback,
242};
243
244static char *msr_devnode(struct device *dev, mode_t *mode)
245{
246 return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
247}
248
249static int __init msr_init(void)
250{
251 int i, err = 0;
252 i = 0;
253
254 if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) {
255 printk(KERN_ERR "msr: unable to get major %d for msr\n",
256 MSR_MAJOR);
257 err = -EBUSY;
258 goto out;
259 }
260 msr_class = class_create(THIS_MODULE, "msr");
261 if (IS_ERR(msr_class)) {
262 err = PTR_ERR(msr_class);
263 goto out_chrdev;
264 }
265 msr_class->devnode = msr_devnode;
266 for_each_online_cpu(i) {
267 err = msr_device_create(i);
268 if (err != 0)
269 goto out_class;
270 }
271 register_hotcpu_notifier(&msr_class_cpu_notifier);
272
273 err = 0;
274 goto out;
275
276out_class:
277 i = 0;
278 for_each_online_cpu(i)
279 msr_device_destroy(i);
280 class_destroy(msr_class);
281out_chrdev:
282 unregister_chrdev(MSR_MAJOR, "cpu/msr");
283out:
284 return err;
285}
286
287static void __exit msr_exit(void)
288{
289 int cpu = 0;
290 for_each_online_cpu(cpu)
291 msr_device_destroy(cpu);
292 class_destroy(msr_class);
293 unregister_chrdev(MSR_MAJOR, "cpu/msr");
294 unregister_hotcpu_notifier(&msr_class_cpu_notifier);
295}
296
297module_init(msr_init);
298module_exit(msr_exit)
299
300MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
301MODULE_DESCRIPTION("x86 generic MSR driver");
302MODULE_LICENSE("GPL");
303
