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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/major.h>
34#include <linux/fs.h>
35#include <linux/device.h>
36#include <linux/cpu.h>
37#include <linux/notifier.h>
38#include <linux/uaccess.h>
39#include <linux/gfp.h>
40
41#include <asm/processor.h>
42#include <asm/msr.h>
43
44static struct class *msr_class;
45
46static loff_t msr_seek(struct file *file, loff_t offset, int orig)
47{
48 loff_t ret;
49 struct inode *inode = file->f_mapping->host;
50
51 mutex_lock(&inode->i_mutex);
52 switch (orig) {
53 case 0:
54 file->f_pos = offset;
55 ret = file->f_pos;
56 break;
57 case 1:
58 file->f_pos += offset;
59 ret = file->f_pos;
60 break;
61 default:
62 ret = -EINVAL;
63 }
64 mutex_unlock(&inode->i_mutex);
65 return ret;
66}
67
68static ssize_t msr_read(struct file *file, char __user *buf,
69 size_t count, loff_t *ppos)
70{
71 u32 __user *tmp = (u32 __user *) buf;
72 u32 data[2];
73 u32 reg = *ppos;
74 int cpu = iminor(file->f_path.dentry->d_inode);
75 int err = 0;
76 ssize_t bytes = 0;
77
78 if (count % 8)
79 return -EINVAL;
80
81 for (; count; count -= 8) {
82 err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);
83 if (err)
84 break;
85 if (copy_to_user(tmp, &data, 8)) {
86 err = -EFAULT;
87 break;
88 }
89 tmp += 2;
90 bytes += 8;
91 }
92
93 return bytes ? bytes : err;
94}
95
96static ssize_t msr_write(struct file *file, const char __user *buf,
97 size_t count, loff_t *ppos)
98{
99 const u32 __user *tmp = (const u32 __user *)buf;
100 u32 data[2];
101 u32 reg = *ppos;
102 int cpu = iminor(file->f_path.dentry->d_inode);
103 int err = 0;
104 ssize_t bytes = 0;
105
106 if (count % 8)
107 return -EINVAL;
108
109 for (; count; count -= 8) {
110 if (copy_from_user(&data, tmp, 8)) {
111 err = -EFAULT;
112 break;
113 }
114 err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
115 if (err)
116 break;
117 tmp += 2;
118 bytes += 8;
119 }
120
121 return bytes ? bytes : err;
122}
123
124static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
125{
126 u32 __user *uregs = (u32 __user *)arg;
127 u32 regs[8];
128 int cpu = iminor(file->f_path.dentry->d_inode);
129 int err;
130
131 switch (ioc) {
132 case X86_IOC_RDMSR_REGS:
133 if (!(file->f_mode & FMODE_READ)) {
134 err = -EBADF;
135 break;
136 }
137 if (copy_from_user(®s, uregs, sizeof regs)) {
138 err = -EFAULT;
139 break;
140 }
141 err = rdmsr_safe_regs_on_cpu(cpu, regs);
142 if (err)
143 break;
144 if (copy_to_user(uregs, ®s, sizeof regs))
145 err = -EFAULT;
146 break;
147
148 case X86_IOC_WRMSR_REGS:
149 if (!(file->f_mode & FMODE_WRITE)) {
150 err = -EBADF;
151 break;
152 }
153 if (copy_from_user(®s, uregs, sizeof regs)) {
154 err = -EFAULT;
155 break;
156 }
157 err = wrmsr_safe_regs_on_cpu(cpu, regs);
158 if (err)
159 break;
160 if (copy_to_user(uregs, ®s, sizeof regs))
161 err = -EFAULT;
162 break;
163
164 default:
165 err = -ENOTTY;
166 break;
167 }
168
169 return err;
170}
171
172static int msr_open(struct inode *inode, struct file *file)
173{
174 unsigned int cpu;
175 struct cpuinfo_x86 *c;
176
177 if (!capable(CAP_SYS_RAWIO))
178 return -EPERM;
179
180 cpu = iminor(file->f_path.dentry->d_inode);
181 if (cpu >= nr_cpu_ids || !cpu_online(cpu))
182 return -ENXIO;
183
184 c = &cpu_data(cpu);
185 if (!cpu_has(c, X86_FEATURE_MSR))
186 return -EIO;
187
188 return 0;
189}
190
191
192
193
194static const struct file_operations msr_fops = {
195 .owner = THIS_MODULE,
196 .llseek = msr_seek,
197 .read = msr_read,
198 .write = msr_write,
199 .open = msr_open,
200 .unlocked_ioctl = msr_ioctl,
201 .compat_ioctl = msr_ioctl,
202};
203
204static int __cpuinit msr_device_create(int cpu)
205{
206 struct device *dev;
207
208 dev = device_create(msr_class, NULL, MKDEV(MSR_MAJOR, cpu), NULL,
209 "msr%d", cpu);
210 return IS_ERR(dev) ? PTR_ERR(dev) : 0;
211}
212
213static void msr_device_destroy(int cpu)
214{
215 device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
216}
217
218static int __cpuinit msr_class_cpu_callback(struct notifier_block *nfb,
219 unsigned long action, void *hcpu)
220{
221 unsigned int cpu = (unsigned long)hcpu;
222 int err = 0;
223
224 switch (action) {
225 case CPU_UP_PREPARE:
226 err = msr_device_create(cpu);
227 break;
228 case CPU_UP_CANCELED:
229 case CPU_UP_CANCELED_FROZEN:
230 case CPU_DEAD:
231 msr_device_destroy(cpu);
232 break;
233 }
234 return notifier_from_errno(err);
235}
236
237static struct notifier_block __refdata msr_class_cpu_notifier = {
238 .notifier_call = msr_class_cpu_callback,
239};
240
241static char *msr_devnode(struct device *dev, umode_t *mode)
242{
243 return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
244}
245
246static int __init msr_init(void)
247{
248 int i, err = 0;
249 i = 0;
250
251 if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
252 printk(KERN_ERR "msr: unable to get major %d for msr\n",
253 MSR_MAJOR);
254 err = -EBUSY;
255 goto out;
256 }
257 msr_class = class_create(THIS_MODULE, "msr");
258 if (IS_ERR(msr_class)) {
259 err = PTR_ERR(msr_class);
260 goto out_chrdev;
261 }
262 msr_class->devnode = msr_devnode;
263 get_online_cpus();
264 for_each_online_cpu(i) {
265 err = msr_device_create(i);
266 if (err != 0)
267 goto out_class;
268 }
269 register_hotcpu_notifier(&msr_class_cpu_notifier);
270 put_online_cpus();
271
272 err = 0;
273 goto out;
274
275out_class:
276 i = 0;
277 for_each_online_cpu(i)
278 msr_device_destroy(i);
279 put_online_cpus();
280 class_destroy(msr_class);
281out_chrdev:
282 __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
283out:
284 return err;
285}
286
287static void __exit msr_exit(void)
288{
289 int cpu = 0;
290 get_online_cpus();
291 for_each_online_cpu(cpu)
292 msr_device_destroy(cpu);
293 class_destroy(msr_class);
294 __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
295 unregister_hotcpu_notifier(&msr_class_cpu_notifier);
296 put_online_cpus();
297}
298
299module_init(msr_init);
300module_exit(msr_exit)
301
302MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
303MODULE_DESCRIPTION("x86 generic MSR driver");
304MODULE_LICENSE("GPL");
305
