summaryrefslogtreecommitdiffstats
path: root/drivers/base/cpu.c
blob: fb456b72980360ec85cc2264d8637f8e5aeafa0c (plain)
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
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
/*
 * drivers/base/cpu.c - basic CPU class support
 */

#include <linux/sysdev.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/cpu.h>
#include <linux/topology.h>
#include <linux/device.h>
#include <linux/node.h>

#include "base.h"

static struct sysdev_class_attribute *cpu_sysdev_class_attrs[];

struct sysdev_class cpu_sysdev_class = {
	.name = "cpu",
	.attrs = cpu_sysdev_class_attrs,
};
EXPORT_SYMBOL(cpu_sysdev_class);

static DEFINE_PER_CPU(struct sys_device *, cpu_sys_devices);

#ifdef CONFIG_HOTPLUG_CPU
static ssize_t show_online(struct sys_device *dev, struct sysdev_attribute *attr,
			   char *buf)
{
	struct cpu *cpu = container_of(dev, struct cpu, sysdev);

	return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
}

static ssize_t __ref store_online(struct sys_device *dev, struct sysdev_attribute *attr,
				 const char *buf, size_t count)
{
	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
	ssize_t ret;

	cpu_hotplug_driver_lock();
	switch (buf[0]) {
	case '0':
		ret = cpu_down(cpu->sysdev.id);
		if (!ret)
			kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
		break;
	case '1':
		ret = cpu_up(cpu->sysdev.id);
		if (!ret)
			kobject_uevent(&dev->kobj, KOBJ_ONLINE);
		break;
	default:
		ret = -EINVAL;
	}
	cpu_hotplug_driver_unlock();

	if (ret >= 0)
		ret = count;
	return ret;
}
static SYSDEV_ATTR(online, 0644, show_online, store_online);

static void __cpuinit register_cpu_control(struct cpu *cpu)
{
	sysdev_create_file(&cpu->sysdev, &attr_online);
}
void unregister_cpu(struct cpu *cpu)
{
	int logical_cpu = cpu->sysdev.id;

	unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));

	sysdev_remove_file(&cpu->sysdev, &attr_online);

	sysdev_unregister(&cpu->sysdev);
	per_cpu(cpu_sys_devices, logical_cpu) = NULL;
	return;
}

#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
static ssize_t cpu_probe_store(struct class *class, const char *buf,
			       size_t count)
{
	return arch_cpu_probe(buf, count);
}

static ssize_t cpu_release_store(struct class *class, const char *buf,
				 size_t count)
{
	return arch_cpu_release(buf, count);
}

static CLASS_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
static CLASS_ATTR(release, S_IWUSR, NULL, cpu_release_store);
#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */

#else /* ... !CONFIG_HOTPLUG_CPU */
static inline void register_cpu_control(struct cpu *cpu)
{
}
#endif /* CONFIG_HOTPLUG_CPU */

#ifdef CONFIG_KEXEC
#include <linux/kexec.h>

static ssize_t show_crash_notes(struct sys_device *dev, struct sysdev_attribute *attr,
				char *buf)
{
	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
	ssize_t rc;
	unsigned long long addr;
	int cpunum;

	cpunum = cpu->sysdev.id;

	/*
	 * Might be reading other cpu's data based on which cpu read thread
	 * has been scheduled. But cpu data (memory) is allocated once during
	 * boot up and this data does not change there after. Hence this
	 * operation should be safe. No locking required.
	 */
	addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
	rc = sprintf(buf, "%Lx\n", addr);
	return rc;
}
static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
#endif

/*
 * Print cpu online, possible, present, and system maps
 */

struct cpu_attr {
	struct sysdev_class_attribute attr;
	const struct cpumask *const * const map;
};

static ssize_t show_cpus_attr(struct sysdev_class *class,
			      struct sysdev_class_attribute *attr,
			      char *buf)
{
	struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
	int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map));

	buf[n++] = '\n';
	buf[n] = '\0';
	return n;
}

#define _CPU_ATTR(name, map)						\
	{ _SYSDEV_CLASS_ATTR(name, 0444, show_cpus_attr, NULL), map }

/* Keep in sync with cpu_sysdev_class_attrs */
static struct cpu_attr cpu_attrs[] = {
	_CPU_ATTR(online, &cpu_online_mask),
	_CPU_ATTR(possible, &cpu_possible_mask),
	_CPU_ATTR(present, &cpu_present_mask),
};

/*
 * Print values for NR_CPUS and offlined cpus
 */
static ssize_t print_cpus_kernel_max(struct sysdev_class *class,
				     struct sysdev_class_attribute *attr, char *buf)
{
	int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
	return n;
}
static SYSDEV_CLASS_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);

/* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
unsigned int total_cpus;

static ssize_t print_cpus_offline(struct sysdev_class *class,
				  struct sysdev_class_attribute *attr, char *buf)
{
	int n = 0, len = PAGE_SIZE-2;
	cpumask_var_t offline;

	/* display offline cpus < nr_cpu_ids */
	if (!alloc_cpumask_var(&offline, GFP_KERNEL))
		return -ENOMEM;
	cpumask_complement(offline, cpu_online_mask);
	n = cpulist_scnprintf(buf, len, offline);
	free_cpumask_var(offline);

	/* display offline cpus >= nr_cpu_ids */
	if (total_cpus && nr_cpu_ids < total_cpus) {
		if (n && n < len)
			buf[n++] = ',';

		if (nr_cpu_ids == total_cpus-1)
			n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
		else
			n += snprintf(&buf[n], len - n, "%d-%d",
						      nr_cpu_ids, total_cpus-1);
	}

	n += snprintf(&buf[n], len - n, "\n");
	return n;
}
static SYSDEV_CLASS_ATTR(offline, 0444, print_cpus_offline, NULL);

/*
 * register_cpu - Setup a sysfs device for a CPU.
 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
 *	  sysfs for this CPU.
 * @num - CPU number to use when creating the device.
 *
 * Initialize and register the CPU device.
 */
int __cpuinit register_cpu(struct cpu *cpu, int num)
{
	int error;
	cpu->node_id = cpu_to_node(num);
	cpu->sysdev.id = num;
	cpu->sysdev.cls = &cpu_sysdev_class;

	error = sysdev_register(&cpu->sysdev);

	if (!error && cpu->hotpluggable)
		register_cpu_control(cpu);
	if (!error)
		per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
	if (!error)
		register_cpu_under_node(num, cpu_to_node(num));

#ifdef CONFIG_KEXEC
	if (!error)
		error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
#endif
	return error;
}

struct sys_device *get_cpu_sysdev(unsigned cpu)
{
	if (cpu < nr_cpu_ids && cpu_possible(cpu))
		return per_cpu(cpu_sys_devices, cpu);
	else
		return NULL;
}
EXPORT_SYMBOL_GPL(get_cpu_sysdev);

int __init cpu_dev_init(void)
{
	int err;

	err = sysdev_class_register(&cpu_sysdev_class);
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
	if (!err)
		err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
#endif

	return err;
}

static struct sysdev_class_attribute *cpu_sysdev_class_attrs[] = {
#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
	&class_attr_probe.attr,
	&class_attr_release.attr,
#endif
	&cpu_attrs[0].attr,
	&cpu_attrs[1].attr,
	&cpu_attrs[2].attr,
	&attr_kernel_max,
	&attr_offline,
	NULL
};