2 * CPU subsystem support
5 #include <linux/kernel.h>
6 #include <linux/module.h>
7 #include <linux/init.h>
8 #include <linux/sched.h>
10 #include <linux/topology.h>
11 #include <linux/device.h>
12 #include <linux/node.h>
13 #include <linux/gfp.h>
14 #include <linux/slab.h>
15 #include <linux/percpu.h>
19 struct bus_type cpu_subsys
= {
23 EXPORT_SYMBOL_GPL(cpu_subsys
);
25 static DEFINE_PER_CPU(struct device
*, cpu_sys_devices
);
27 #ifdef CONFIG_HOTPLUG_CPU
28 static void change_cpu_under_node(struct cpu
*cpu
,
29 unsigned int from_nid
, unsigned int to_nid
)
31 int cpuid
= cpu
->dev
.id
;
32 unregister_cpu_under_node(cpuid
, from_nid
);
33 register_cpu_under_node(cpuid
, to_nid
);
34 cpu
->node_id
= to_nid
;
37 static ssize_t
show_online(struct device
*dev
,
38 struct device_attribute
*attr
,
41 struct cpu
*cpu
= container_of(dev
, struct cpu
, dev
);
43 return sprintf(buf
, "%u\n", !!cpu_online(cpu
->dev
.id
));
46 static ssize_t __ref
store_online(struct device
*dev
,
47 struct device_attribute
*attr
,
48 const char *buf
, size_t count
)
50 struct cpu
*cpu
= container_of(dev
, struct cpu
, dev
);
51 int cpuid
= cpu
->dev
.id
;
55 cpu_hotplug_driver_lock();
58 ret
= cpu_down(cpuid
);
60 kobject_uevent(&dev
->kobj
, KOBJ_OFFLINE
);
63 from_nid
= cpu_to_node(cpuid
);
67 * When hot adding memory to memoryless node and enabling a cpu
68 * on the node, node number of the cpu may internally change.
70 to_nid
= cpu_to_node(cpuid
);
71 if (from_nid
!= to_nid
)
72 change_cpu_under_node(cpu
, from_nid
, to_nid
);
75 kobject_uevent(&dev
->kobj
, KOBJ_ONLINE
);
80 cpu_hotplug_driver_unlock();
86 static DEVICE_ATTR(online
, 0644, show_online
, store_online
);
88 static void __cpuinit
register_cpu_control(struct cpu
*cpu
)
90 device_create_file(&cpu
->dev
, &dev_attr_online
);
92 void unregister_cpu(struct cpu
*cpu
)
94 int logical_cpu
= cpu
->dev
.id
;
96 unregister_cpu_under_node(logical_cpu
, cpu_to_node(logical_cpu
));
98 device_remove_file(&cpu
->dev
, &dev_attr_online
);
100 device_unregister(&cpu
->dev
);
101 per_cpu(cpu_sys_devices
, logical_cpu
) = NULL
;
105 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
106 static ssize_t
cpu_probe_store(struct device
*dev
,
107 struct device_attribute
*attr
,
111 return arch_cpu_probe(buf
, count
);
114 static ssize_t
cpu_release_store(struct device
*dev
,
115 struct device_attribute
*attr
,
119 return arch_cpu_release(buf
, count
);
122 static DEVICE_ATTR(probe
, S_IWUSR
, NULL
, cpu_probe_store
);
123 static DEVICE_ATTR(release
, S_IWUSR
, NULL
, cpu_release_store
);
124 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
126 #else /* ... !CONFIG_HOTPLUG_CPU */
127 static inline void register_cpu_control(struct cpu
*cpu
)
130 #endif /* CONFIG_HOTPLUG_CPU */
133 #include <linux/kexec.h>
135 static ssize_t
show_crash_notes(struct device
*dev
, struct device_attribute
*attr
,
138 struct cpu
*cpu
= container_of(dev
, struct cpu
, dev
);
140 unsigned long long addr
;
143 cpunum
= cpu
->dev
.id
;
146 * Might be reading other cpu's data based on which cpu read thread
147 * has been scheduled. But cpu data (memory) is allocated once during
148 * boot up and this data does not change there after. Hence this
149 * operation should be safe. No locking required.
151 addr
= per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes
, cpunum
));
152 rc
= sprintf(buf
, "%Lx\n", addr
);
155 static DEVICE_ATTR(crash_notes
, 0400, show_crash_notes
, NULL
);
157 static ssize_t
show_crash_notes_size(struct device
*dev
,
158 struct device_attribute
*attr
,
163 rc
= sprintf(buf
, "%zu\n", sizeof(note_buf_t
));
166 static DEVICE_ATTR(crash_notes_size
, 0400, show_crash_notes_size
, NULL
);
170 * Print cpu online, possible, present, and system maps
174 struct device_attribute attr
;
175 const struct cpumask
*const * const map
;
178 static ssize_t
show_cpus_attr(struct device
*dev
,
179 struct device_attribute
*attr
,
182 struct cpu_attr
*ca
= container_of(attr
, struct cpu_attr
, attr
);
183 int n
= cpulist_scnprintf(buf
, PAGE_SIZE
-2, *(ca
->map
));
190 #define _CPU_ATTR(name, map) \
191 { __ATTR(name, 0444, show_cpus_attr, NULL), map }
193 /* Keep in sync with cpu_subsys_attrs */
194 static struct cpu_attr cpu_attrs
[] = {
195 _CPU_ATTR(online
, &cpu_online_mask
),
196 _CPU_ATTR(possible
, &cpu_possible_mask
),
197 _CPU_ATTR(present
, &cpu_present_mask
),
201 * Print values for NR_CPUS and offlined cpus
203 static ssize_t
print_cpus_kernel_max(struct device
*dev
,
204 struct device_attribute
*attr
, char *buf
)
206 int n
= snprintf(buf
, PAGE_SIZE
-2, "%d\n", NR_CPUS
- 1);
209 static DEVICE_ATTR(kernel_max
, 0444, print_cpus_kernel_max
, NULL
);
211 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
212 unsigned int total_cpus
;
214 static ssize_t
print_cpus_offline(struct device
*dev
,
215 struct device_attribute
*attr
, char *buf
)
217 int n
= 0, len
= PAGE_SIZE
-2;
218 cpumask_var_t offline
;
220 /* display offline cpus < nr_cpu_ids */
221 if (!alloc_cpumask_var(&offline
, GFP_KERNEL
))
223 cpumask_andnot(offline
, cpu_possible_mask
, cpu_online_mask
);
224 n
= cpulist_scnprintf(buf
, len
, offline
);
225 free_cpumask_var(offline
);
227 /* display offline cpus >= nr_cpu_ids */
228 if (total_cpus
&& nr_cpu_ids
< total_cpus
) {
232 if (nr_cpu_ids
== total_cpus
-1)
233 n
+= snprintf(&buf
[n
], len
- n
, "%d", nr_cpu_ids
);
235 n
+= snprintf(&buf
[n
], len
- n
, "%d-%d",
236 nr_cpu_ids
, total_cpus
-1);
239 n
+= snprintf(&buf
[n
], len
- n
, "\n");
242 static DEVICE_ATTR(offline
, 0444, print_cpus_offline
, NULL
);
244 static void cpu_device_release(struct device
*dev
)
247 * This is an empty function to prevent the driver core from spitting a
248 * warning at us. Yes, I know this is directly opposite of what the
249 * documentation for the driver core and kobjects say, and the author
250 * of this code has already been publically ridiculed for doing
251 * something as foolish as this. However, at this point in time, it is
252 * the only way to handle the issue of statically allocated cpu
253 * devices. The different architectures will have their cpu device
254 * code reworked to properly handle this in the near future, so this
255 * function will then be changed to correctly free up the memory held
258 * Never copy this way of doing things, or you too will be made fun of
259 * on the linux-kernel list, you have been warned.
264 * register_cpu - Setup a sysfs device for a CPU.
265 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
266 * sysfs for this CPU.
267 * @num - CPU number to use when creating the device.
269 * Initialize and register the CPU device.
271 int __cpuinit
register_cpu(struct cpu
*cpu
, int num
)
275 cpu
->node_id
= cpu_to_node(num
);
276 memset(&cpu
->dev
, 0x00, sizeof(struct device
));
278 cpu
->dev
.bus
= &cpu_subsys
;
279 cpu
->dev
.release
= cpu_device_release
;
280 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
281 cpu
->dev
.bus
->uevent
= arch_cpu_uevent
;
283 error
= device_register(&cpu
->dev
);
284 if (!error
&& cpu
->hotpluggable
)
285 register_cpu_control(cpu
);
287 per_cpu(cpu_sys_devices
, num
) = &cpu
->dev
;
289 register_cpu_under_node(num
, cpu_to_node(num
));
293 error
= device_create_file(&cpu
->dev
, &dev_attr_crash_notes
);
295 error
= device_create_file(&cpu
->dev
,
296 &dev_attr_crash_notes_size
);
301 struct device
*get_cpu_device(unsigned cpu
)
303 if (cpu
< nr_cpu_ids
&& cpu_possible(cpu
))
304 return per_cpu(cpu_sys_devices
, cpu
);
308 EXPORT_SYMBOL_GPL(get_cpu_device
);
310 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
311 static DEVICE_ATTR(modalias
, 0444, arch_print_cpu_modalias
, NULL
);
314 static struct attribute
*cpu_root_attrs
[] = {
315 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
316 &dev_attr_probe
.attr
,
317 &dev_attr_release
.attr
,
319 &cpu_attrs
[0].attr
.attr
,
320 &cpu_attrs
[1].attr
.attr
,
321 &cpu_attrs
[2].attr
.attr
,
322 &dev_attr_kernel_max
.attr
,
323 &dev_attr_offline
.attr
,
324 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
325 &dev_attr_modalias
.attr
,
330 static struct attribute_group cpu_root_attr_group
= {
331 .attrs
= cpu_root_attrs
,
334 static const struct attribute_group
*cpu_root_attr_groups
[] = {
335 &cpu_root_attr_group
,
339 bool cpu_is_hotpluggable(unsigned cpu
)
341 struct device
*dev
= get_cpu_device(cpu
);
342 return dev
&& container_of(dev
, struct cpu
, dev
)->hotpluggable
;
344 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable
);
346 #ifdef CONFIG_GENERIC_CPU_DEVICES
347 static DEFINE_PER_CPU(struct cpu
, cpu_devices
);
350 static void __init
cpu_dev_register_generic(void)
352 #ifdef CONFIG_GENERIC_CPU_DEVICES
355 for_each_possible_cpu(i
) {
356 if (register_cpu(&per_cpu(cpu_devices
, i
), i
))
357 panic("Failed to register CPU device");
362 void __init
cpu_dev_init(void)
364 if (subsys_system_register(&cpu_subsys
, cpu_root_attr_groups
))
365 panic("Failed to register CPU subsystem");
367 cpu_dev_register_generic();