Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* ----------------------------------------------------------------------- * |
2 | * | |
3 | * Copyright 2000 H. Peter Anvin - All Rights Reserved | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA 02139, | |
8 | * USA; either version 2 of the License, or (at your option) any later | |
9 | * version; incorporated herein by reference. | |
10 | * | |
11 | * ----------------------------------------------------------------------- */ | |
12 | ||
13 | /* | |
14 | * msr.c | |
15 | * | |
16 | * x86 MSR access device | |
17 | * | |
18 | * This device is accessed by lseek() to the appropriate register number | |
19 | * and then read/write in chunks of 8 bytes. A larger size means multiple | |
20 | * reads or writes of the same register. | |
21 | * | |
22 | * This driver uses /dev/cpu/%d/msr where %d is the minor number, and on | |
23 | * an SMP box will direct the access to CPU %d. | |
24 | */ | |
25 | ||
26 | #include <linux/module.h> | |
27 | #include <linux/config.h> | |
28 | ||
29 | #include <linux/types.h> | |
30 | #include <linux/errno.h> | |
31 | #include <linux/fcntl.h> | |
32 | #include <linux/init.h> | |
33 | #include <linux/poll.h> | |
34 | #include <linux/smp.h> | |
35 | #include <linux/smp_lock.h> | |
36 | #include <linux/major.h> | |
37 | #include <linux/fs.h> | |
38 | #include <linux/device.h> | |
39 | #include <linux/cpu.h> | |
40 | #include <linux/notifier.h> | |
41 | ||
42 | #include <asm/processor.h> | |
43 | #include <asm/msr.h> | |
44 | #include <asm/uaccess.h> | |
45 | #include <asm/system.h> | |
46 | ||
47 | static struct class_simple *msr_class; | |
48 | ||
49 | /* Note: "err" is handled in a funny way below. Otherwise one version | |
50 | of gcc or another breaks. */ | |
51 | ||
52 | static inline int wrmsr_eio(u32 reg, u32 eax, u32 edx) | |
53 | { | |
54 | int err; | |
55 | ||
56 | asm volatile ("1: wrmsr\n" | |
57 | "2:\n" | |
58 | ".section .fixup,\"ax\"\n" | |
59 | "3: movl %4,%0\n" | |
60 | " jmp 2b\n" | |
61 | ".previous\n" | |
62 | ".section __ex_table,\"a\"\n" | |
63 | " .align 4\n" " .long 1b,3b\n" ".previous":"=&bDS" (err) | |
64 | :"a"(eax), "d"(edx), "c"(reg), "i"(-EIO), "0"(0)); | |
65 | ||
66 | return err; | |
67 | } | |
68 | ||
69 | static inline int rdmsr_eio(u32 reg, u32 *eax, u32 *edx) | |
70 | { | |
71 | int err; | |
72 | ||
73 | asm volatile ("1: rdmsr\n" | |
74 | "2:\n" | |
75 | ".section .fixup,\"ax\"\n" | |
76 | "3: movl %4,%0\n" | |
77 | " jmp 2b\n" | |
78 | ".previous\n" | |
79 | ".section __ex_table,\"a\"\n" | |
80 | " .align 4\n" | |
81 | " .long 1b,3b\n" | |
82 | ".previous":"=&bDS" (err), "=a"(*eax), "=d"(*edx) | |
83 | :"c"(reg), "i"(-EIO), "0"(0)); | |
84 | ||
85 | return err; | |
86 | } | |
87 | ||
88 | #ifdef CONFIG_SMP | |
89 | ||
90 | struct msr_command { | |
91 | int cpu; | |
92 | int err; | |
93 | u32 reg; | |
94 | u32 data[2]; | |
95 | }; | |
96 | ||
97 | static void msr_smp_wrmsr(void *cmd_block) | |
98 | { | |
99 | struct msr_command *cmd = (struct msr_command *)cmd_block; | |
100 | ||
101 | if (cmd->cpu == smp_processor_id()) | |
102 | cmd->err = wrmsr_eio(cmd->reg, cmd->data[0], cmd->data[1]); | |
103 | } | |
104 | ||
105 | static void msr_smp_rdmsr(void *cmd_block) | |
106 | { | |
107 | struct msr_command *cmd = (struct msr_command *)cmd_block; | |
108 | ||
109 | if (cmd->cpu == smp_processor_id()) | |
110 | cmd->err = rdmsr_eio(cmd->reg, &cmd->data[0], &cmd->data[1]); | |
111 | } | |
112 | ||
113 | static inline int do_wrmsr(int cpu, u32 reg, u32 eax, u32 edx) | |
114 | { | |
115 | struct msr_command cmd; | |
116 | int ret; | |
117 | ||
118 | preempt_disable(); | |
119 | if (cpu == smp_processor_id()) { | |
120 | ret = wrmsr_eio(reg, eax, edx); | |
121 | } else { | |
122 | cmd.cpu = cpu; | |
123 | cmd.reg = reg; | |
124 | cmd.data[0] = eax; | |
125 | cmd.data[1] = edx; | |
126 | ||
127 | smp_call_function(msr_smp_wrmsr, &cmd, 1, 1); | |
128 | ret = cmd.err; | |
129 | } | |
130 | preempt_enable(); | |
131 | return ret; | |
132 | } | |
133 | ||
134 | static inline int do_rdmsr(int cpu, u32 reg, u32 * eax, u32 * edx) | |
135 | { | |
136 | struct msr_command cmd; | |
137 | int ret; | |
138 | ||
139 | preempt_disable(); | |
140 | if (cpu == smp_processor_id()) { | |
141 | ret = rdmsr_eio(reg, eax, edx); | |
142 | } else { | |
143 | cmd.cpu = cpu; | |
144 | cmd.reg = reg; | |
145 | ||
146 | smp_call_function(msr_smp_rdmsr, &cmd, 1, 1); | |
147 | ||
148 | *eax = cmd.data[0]; | |
149 | *edx = cmd.data[1]; | |
150 | ||
151 | ret = cmd.err; | |
152 | } | |
153 | preempt_enable(); | |
154 | return ret; | |
155 | } | |
156 | ||
157 | #else /* ! CONFIG_SMP */ | |
158 | ||
159 | static inline int do_wrmsr(int cpu, u32 reg, u32 eax, u32 edx) | |
160 | { | |
161 | return wrmsr_eio(reg, eax, edx); | |
162 | } | |
163 | ||
164 | static inline int do_rdmsr(int cpu, u32 reg, u32 *eax, u32 *edx) | |
165 | { | |
166 | return rdmsr_eio(reg, eax, edx); | |
167 | } | |
168 | ||
169 | #endif /* ! CONFIG_SMP */ | |
170 | ||
171 | static loff_t msr_seek(struct file *file, loff_t offset, int orig) | |
172 | { | |
173 | loff_t ret = -EINVAL; | |
174 | ||
175 | lock_kernel(); | |
176 | switch (orig) { | |
177 | case 0: | |
178 | file->f_pos = offset; | |
179 | ret = file->f_pos; | |
180 | break; | |
181 | case 1: | |
182 | file->f_pos += offset; | |
183 | ret = file->f_pos; | |
184 | } | |
185 | unlock_kernel(); | |
186 | return ret; | |
187 | } | |
188 | ||
189 | static ssize_t msr_read(struct file *file, char __user * buf, | |
190 | size_t count, loff_t * ppos) | |
191 | { | |
192 | u32 __user *tmp = (u32 __user *) buf; | |
193 | u32 data[2]; | |
194 | size_t rv; | |
195 | u32 reg = *ppos; | |
196 | int cpu = iminor(file->f_dentry->d_inode); | |
197 | int err; | |
198 | ||
199 | if (count % 8) | |
200 | return -EINVAL; /* Invalid chunk size */ | |
201 | ||
202 | for (rv = 0; count; count -= 8) { | |
203 | err = do_rdmsr(cpu, reg, &data[0], &data[1]); | |
204 | if (err) | |
205 | return err; | |
206 | if (copy_to_user(tmp, &data, 8)) | |
207 | return -EFAULT; | |
208 | tmp += 2; | |
209 | } | |
210 | ||
211 | return ((char __user *)tmp) - buf; | |
212 | } | |
213 | ||
214 | static ssize_t msr_write(struct file *file, const char __user *buf, | |
215 | size_t count, loff_t *ppos) | |
216 | { | |
217 | const u32 __user *tmp = (const u32 __user *)buf; | |
218 | u32 data[2]; | |
219 | size_t rv; | |
220 | u32 reg = *ppos; | |
221 | int cpu = iminor(file->f_dentry->d_inode); | |
222 | int err; | |
223 | ||
224 | if (count % 8) | |
225 | return -EINVAL; /* Invalid chunk size */ | |
226 | ||
227 | for (rv = 0; count; count -= 8) { | |
228 | if (copy_from_user(&data, tmp, 8)) | |
229 | return -EFAULT; | |
230 | err = do_wrmsr(cpu, reg, data[0], data[1]); | |
231 | if (err) | |
232 | return err; | |
233 | tmp += 2; | |
234 | } | |
235 | ||
236 | return ((char __user *)tmp) - buf; | |
237 | } | |
238 | ||
239 | static int msr_open(struct inode *inode, struct file *file) | |
240 | { | |
241 | unsigned int cpu = iminor(file->f_dentry->d_inode); | |
242 | struct cpuinfo_x86 *c = &(cpu_data)[cpu]; | |
243 | ||
244 | if (cpu >= NR_CPUS || !cpu_online(cpu)) | |
245 | return -ENXIO; /* No such CPU */ | |
246 | if (!cpu_has(c, X86_FEATURE_MSR)) | |
247 | return -EIO; /* MSR not supported */ | |
248 | ||
249 | return 0; | |
250 | } | |
251 | ||
252 | /* | |
253 | * File operations we support | |
254 | */ | |
255 | static struct file_operations msr_fops = { | |
256 | .owner = THIS_MODULE, | |
257 | .llseek = msr_seek, | |
258 | .read = msr_read, | |
259 | .write = msr_write, | |
260 | .open = msr_open, | |
261 | }; | |
262 | ||
263 | static int msr_class_simple_device_add(int i) | |
264 | { | |
265 | int err = 0; | |
266 | struct class_device *class_err; | |
267 | ||
268 | class_err = class_simple_device_add(msr_class, MKDEV(MSR_MAJOR, i), NULL, "msr%d",i); | |
269 | if (IS_ERR(class_err)) | |
270 | err = PTR_ERR(class_err); | |
271 | return err; | |
272 | } | |
273 | ||
274 | static int __devinit msr_class_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) | |
275 | { | |
276 | unsigned int cpu = (unsigned long)hcpu; | |
277 | ||
278 | switch (action) { | |
279 | case CPU_ONLINE: | |
280 | msr_class_simple_device_add(cpu); | |
281 | break; | |
282 | case CPU_DEAD: | |
283 | class_simple_device_remove(MKDEV(MSR_MAJOR, cpu)); | |
284 | break; | |
285 | } | |
286 | return NOTIFY_OK; | |
287 | } | |
288 | ||
289 | static struct notifier_block msr_class_cpu_notifier = | |
290 | { | |
291 | .notifier_call = msr_class_cpu_callback, | |
292 | }; | |
293 | ||
294 | static int __init msr_init(void) | |
295 | { | |
296 | int i, err = 0; | |
297 | i = 0; | |
298 | ||
299 | if (register_chrdev(MSR_MAJOR, "cpu/msr", &msr_fops)) { | |
300 | printk(KERN_ERR "msr: unable to get major %d for msr\n", | |
301 | MSR_MAJOR); | |
302 | err = -EBUSY; | |
303 | goto out; | |
304 | } | |
305 | msr_class = class_simple_create(THIS_MODULE, "msr"); | |
306 | if (IS_ERR(msr_class)) { | |
307 | err = PTR_ERR(msr_class); | |
308 | goto out_chrdev; | |
309 | } | |
310 | for_each_online_cpu(i) { | |
311 | err = msr_class_simple_device_add(i); | |
312 | if (err != 0) | |
313 | goto out_class; | |
314 | } | |
315 | register_cpu_notifier(&msr_class_cpu_notifier); | |
316 | ||
317 | err = 0; | |
318 | goto out; | |
319 | ||
320 | out_class: | |
321 | i = 0; | |
322 | for_each_online_cpu(i) | |
323 | class_simple_device_remove(MKDEV(MSR_MAJOR, i)); | |
324 | class_simple_destroy(msr_class); | |
325 | out_chrdev: | |
326 | unregister_chrdev(MSR_MAJOR, "cpu/msr"); | |
327 | out: | |
328 | return err; | |
329 | } | |
330 | ||
331 | static void __exit msr_exit(void) | |
332 | { | |
333 | int cpu = 0; | |
334 | for_each_online_cpu(cpu) | |
335 | class_simple_device_remove(MKDEV(MSR_MAJOR, cpu)); | |
336 | class_simple_destroy(msr_class); | |
337 | unregister_chrdev(MSR_MAJOR, "cpu/msr"); | |
338 | unregister_cpu_notifier(&msr_class_cpu_notifier); | |
339 | } | |
340 | ||
341 | module_init(msr_init); | |
342 | module_exit(msr_exit) | |
343 | ||
344 | MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>"); | |
345 | MODULE_DESCRIPTION("x86 generic MSR driver"); | |
346 | MODULE_LICENSE("GPL"); |