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[mirror_ubuntu-bionic-kernel.git] / arch / x86 / kernel / cpuid.c
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1da177e4 1/* ----------------------------------------------------------------------- *
2347d933
PA
2 *
3 * Copyright 2000-2008 H. Peter Anvin - All Rights Reserved
1da177e4
LT
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/*
1da177e4
LT
14 * x86 CPUID access device
15 *
16 * This device is accessed by lseek() to the appropriate CPUID level
17 * and then read in chunks of 16 bytes. A larger size means multiple
18 * reads of consecutive levels.
19 *
2347d933
PA
20 * The lower 32 bits of the file position is used as the incoming %eax,
21 * and the upper 32 bits of the file position as the incoming %ecx,
22 * the latter intended for "counting" eax levels like eax=4.
23 *
1da177e4
LT
24 * This driver uses /dev/cpu/%d/cpuid where %d is the minor number, and on
25 * an SMP box will direct the access to CPU %d.
26 */
27
28#include <linux/module.h>
1da177e4
LT
29
30#include <linux/types.h>
31#include <linux/errno.h>
32#include <linux/fcntl.h>
33#include <linux/init.h>
34#include <linux/poll.h>
35#include <linux/smp.h>
36#include <linux/major.h>
37#include <linux/fs.h>
1da177e4
LT
38#include <linux/device.h>
39#include <linux/cpu.h>
40#include <linux/notifier.h>
f634fa94 41#include <linux/uaccess.h>
5a0e3ad6 42#include <linux/gfp.h>
1da177e4
LT
43
44#include <asm/processor.h>
45#include <asm/msr.h>
1da177e4 46
8874b414 47static struct class *cpuid_class;
1da177e4 48
2347d933
PA
49struct cpuid_regs {
50 u32 eax, ebx, ecx, edx;
1da177e4
LT
51};
52
53static void cpuid_smp_cpuid(void *cmd_block)
54{
2347d933 55 struct cpuid_regs *cmd = (struct cpuid_regs *)cmd_block;
1da177e4 56
2347d933
PA
57 cpuid_count(cmd->eax, cmd->ecx,
58 &cmd->eax, &cmd->ebx, &cmd->ecx, &cmd->edx);
1da177e4
LT
59}
60
1da177e4
LT
61static loff_t cpuid_seek(struct file *file, loff_t offset, int orig)
62{
63 loff_t ret;
2b06ac86 64 struct inode *inode = file->f_mapping->host;
1da177e4 65
2b06ac86 66 mutex_lock(&inode->i_mutex);
1da177e4
LT
67 switch (orig) {
68 case 0:
69 file->f_pos = offset;
70 ret = file->f_pos;
71 break;
72 case 1:
73 file->f_pos += offset;
74 ret = file->f_pos;
75 break;
76 default:
77 ret = -EINVAL;
78 }
2b06ac86 79 mutex_unlock(&inode->i_mutex);
1da177e4
LT
80 return ret;
81}
82
83static ssize_t cpuid_read(struct file *file, char __user *buf,
f634fa94 84 size_t count, loff_t *ppos)
1da177e4
LT
85{
86 char __user *tmp = buf;
2347d933 87 struct cpuid_regs cmd;
496ad9aa 88 int cpu = iminor(file_inode(file));
2347d933 89 u64 pos = *ppos;
9ea2b82e
PA
90 ssize_t bytes = 0;
91 int err = 0;
1da177e4
LT
92
93 if (count % 16)
94 return -EINVAL; /* Invalid chunk size */
95
6b7f430e 96 for (; count; count -= 16) {
2347d933
PA
97 cmd.eax = pos;
98 cmd.ecx = pos >> 32;
4b46ca70
PA
99 err = smp_call_function_single(cpu, cpuid_smp_cpuid, &cmd, 1);
100 if (err)
9ea2b82e
PA
101 break;
102 if (copy_to_user(tmp, &cmd, 16)) {
103 err = -EFAULT;
104 break;
105 }
1da177e4 106 tmp += 16;
9ea2b82e 107 bytes += 16;
2347d933 108 *ppos = ++pos;
1da177e4
LT
109 }
110
9ea2b82e 111 return bytes ? bytes : err;
1da177e4
LT
112}
113
114static int cpuid_open(struct inode *inode, struct file *file)
115{
5119e92e
JC
116 unsigned int cpu;
117 struct cpuinfo_x86 *c;
5119e92e 118
496ad9aa 119 cpu = iminor(file_inode(file));
5a943617
JK
120 if (cpu >= nr_cpu_ids || !cpu_online(cpu))
121 return -ENXIO; /* No such CPU */
122
5119e92e 123 c = &cpu_data(cpu);
1da177e4 124 if (c->cpuid_level < 0)
5a943617
JK
125 return -EIO; /* CPUID not supported */
126
127 return 0;
1da177e4
LT
128}
129
130/*
131 * File operations we support
132 */
5dfe4c96 133static const struct file_operations cpuid_fops = {
1da177e4
LT
134 .owner = THIS_MODULE,
135 .llseek = cpuid_seek,
136 .read = cpuid_read,
137 .open = cpuid_open,
138};
139
148f9bb8 140static int cpuid_device_create(int cpu)
1da177e4 141{
07accdc1 142 struct device *dev;
1da177e4 143
a9b12619
GKH
144 dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu), NULL,
145 "cpu%d", cpu);
cbda45a2 146 return PTR_ERR_OR_ZERO(dev);
1f503e77
AM
147}
148
149static void cpuid_device_destroy(int cpu)
150{
151 device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
1da177e4
LT
152}
153
148f9bb8
PG
154static int cpuid_class_cpu_callback(struct notifier_block *nfb,
155 unsigned long action, void *hcpu)
1da177e4
LT
156{
157 unsigned int cpu = (unsigned long)hcpu;
1f503e77 158 int err = 0;
1da177e4
LT
159
160 switch (action) {
1f503e77 161 case CPU_UP_PREPARE:
1f503e77 162 err = cpuid_device_create(cpu);
1da177e4 163 break;
1f503e77 164 case CPU_UP_CANCELED:
b844eba2 165 case CPU_UP_CANCELED_FROZEN:
1da177e4 166 case CPU_DEAD:
1f503e77 167 cpuid_device_destroy(cpu);
1da177e4
LT
168 break;
169 }
a94247e7 170 return notifier_from_errno(err);
1da177e4
LT
171}
172
c72258c7 173static struct notifier_block __refdata cpuid_class_cpu_notifier =
1da177e4
LT
174{
175 .notifier_call = cpuid_class_cpu_callback,
176};
177
2c9ede55 178static char *cpuid_devnode(struct device *dev, umode_t *mode)
07e9bb8e
KS
179{
180 return kasprintf(GFP_KERNEL, "cpu/%u/cpuid", MINOR(dev->devt));
181}
182
1da177e4
LT
183static int __init cpuid_init(void)
184{
185 int i, err = 0;
186 i = 0;
187
0b962d47
PA
188 if (__register_chrdev(CPUID_MAJOR, 0, NR_CPUS,
189 "cpu/cpuid", &cpuid_fops)) {
1da177e4
LT
190 printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
191 CPUID_MAJOR);
192 err = -EBUSY;
193 goto out;
194 }
8874b414 195 cpuid_class = class_create(THIS_MODULE, "cpuid");
1da177e4
LT
196 if (IS_ERR(cpuid_class)) {
197 err = PTR_ERR(cpuid_class);
198 goto out_chrdev;
199 }
e454cea2 200 cpuid_class->devnode = cpuid_devnode;
4b660b38
SB
201
202 cpu_notifier_register_begin();
1da177e4 203 for_each_online_cpu(i) {
07accdc1 204 err = cpuid_device_create(i);
2347d933 205 if (err != 0)
1da177e4
LT
206 goto out_class;
207 }
4b660b38
SB
208 __register_hotcpu_notifier(&cpuid_class_cpu_notifier);
209 cpu_notifier_register_done();
1da177e4
LT
210
211 err = 0;
212 goto out;
213
214out_class:
215 i = 0;
216 for_each_online_cpu(i) {
1f503e77 217 cpuid_device_destroy(i);
1da177e4 218 }
4b660b38 219 cpu_notifier_register_done();
8874b414 220 class_destroy(cpuid_class);
1da177e4 221out_chrdev:
0b962d47 222 __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
1da177e4
LT
223out:
224 return err;
225}
226
227static void __exit cpuid_exit(void)
228{
229 int cpu = 0;
230
4b660b38 231 cpu_notifier_register_begin();
1da177e4 232 for_each_online_cpu(cpu)
1f503e77 233 cpuid_device_destroy(cpu);
8874b414 234 class_destroy(cpuid_class);
da482474 235 __unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
4b660b38
SB
236 __unregister_hotcpu_notifier(&cpuid_class_cpu_notifier);
237 cpu_notifier_register_done();
1da177e4
LT
238}
239
240module_init(cpuid_init);
241module_exit(cpuid_exit);
242
243MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
244MODULE_DESCRIPTION("x86 generic CPUID driver");
245MODULE_LICENSE("GPL");