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
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
/* ----------------------------------------------------------------------- *
*
* Copyright 2000-2008 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.
*
* ----------------------------------------------------------------------- */
/*
* x86 CPUID access device
*
* This device is accessed by lseek() to the appropriate CPUID level
* and then read in chunks of 16 bytes. A larger size means multiple
* reads of consecutive levels.
*
* The lower 32 bits of the file position is used as the incoming %eax,
* and the upper 32 bits of the file position as the incoming %ecx,
* the latter intended for "counting" eax levels like eax=4.
*
* This driver uses /dev/cpu/%d/cpuid 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/major.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/uaccess.h>
#include <linux/gfp.h>
#include <linux/completion.h>
#include <asm/processor.h>
#include <asm/msr.h>
static struct class *cpuid_class;
static enum cpuhp_state cpuhp_cpuid_state;
struct cpuid_regs_done {
struct cpuid_regs regs;
struct completion done;
};
static void cpuid_smp_cpuid(void *cmd_block)
{
struct cpuid_regs_done *cmd = cmd_block;
cpuid_count(cmd->regs.eax, cmd->regs.ecx,
&cmd->regs.eax, &cmd->regs.ebx,
&cmd->regs.ecx, &cmd->regs.edx);
complete(&cmd->done);
}
static ssize_t cpuid_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
char __user *tmp = buf;
struct cpuid_regs_done cmd;
int cpu = iminor(file_inode(file));
u64 pos = *ppos;
ssize_t bytes = 0;
int err = 0;
if (count % 16)
return -EINVAL; /* Invalid chunk size */
init_completion(&cmd.done);
for (; count; count -= 16) {
call_single_data_t csd = {
.func = cpuid_smp_cpuid,
.info = &cmd,
};
cmd.regs.eax = pos;
cmd.regs.ecx = pos >> 32;
err = smp_call_function_single_async(cpu, &csd);
if (err)
break;
wait_for_completion(&cmd.done);
if (copy_to_user(tmp, &cmd.regs, 16)) {
err = -EFAULT;
break;
}
tmp += 16;
bytes += 16;
*ppos = ++pos;
reinit_completion(&cmd.done);
}
return bytes ? bytes : err;
}
static int cpuid_open(struct inode *inode, struct file *file)
{
unsigned int cpu;
struct cpuinfo_x86 *c;
cpu = iminor(file_inode(file));
if (cpu >= nr_cpu_ids || !cpu_online(cpu))
return -ENXIO; /* No such CPU */
c = &cpu_data(cpu);
if (c->cpuid_level < 0)
return -EIO; /* CPUID not supported */
return 0;
}
/*
* File operations we support
*/
static const struct file_operations cpuid_fops = {
.owner = THIS_MODULE,
.llseek = no_seek_end_llseek,
.read = cpuid_read,
.open = cpuid_open,
};
static int cpuid_device_create(unsigned int cpu)
{
struct device *dev;
dev = device_create(cpuid_class, NULL, MKDEV(CPUID_MAJOR, cpu), NULL,
"cpu%d", cpu);
return PTR_ERR_OR_ZERO(dev);
}
static int cpuid_device_destroy(unsigned int cpu)
{
device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
return 0;
}
static char *cpuid_devnode(struct device *dev, umode_t *mode)
{
return kasprintf(GFP_KERNEL, "cpu/%u/cpuid", MINOR(dev->devt));
}
static int __init cpuid_init(void)
{
int err;
if (__register_chrdev(CPUID_MAJOR, 0, NR_CPUS,
"cpu/cpuid", &cpuid_fops)) {
printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",
CPUID_MAJOR);
return -EBUSY;
}
cpuid_class = class_create(THIS_MODULE, "cpuid");
if (IS_ERR(cpuid_class)) {
err = PTR_ERR(cpuid_class);
goto out_chrdev;
}
cpuid_class->devnode = cpuid_devnode;
err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/cpuid:online",
cpuid_device_create, cpuid_device_destroy);
if (err < 0)
goto out_class;
cpuhp_cpuid_state = err;
return 0;
out_class:
class_destroy(cpuid_class);
out_chrdev:
__unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
return err;
}
module_init(cpuid_init);
static void __exit cpuid_exit(void)
{
cpuhp_remove_state(cpuhp_cpuid_state);
class_destroy(cpuid_class);
__unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");
}
module_exit(cpuid_exit);
MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
MODULE_DESCRIPTION("x86 generic CPUID driver");
MODULE_LICENSE("GPL");
|
