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 struct attribute *hotplug_cpu_attrs[] = {
89 &dev_attr_online.attr,
93 static struct attribute_group hotplug_cpu_attr_group = {
94 .attrs = hotplug_cpu_attrs,
97 void unregister_cpu(struct cpu *cpu)
99 int logical_cpu = cpu->dev.id;
101 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
103 device_unregister(&cpu->dev);
104 per_cpu(cpu_sys_devices, logical_cpu) = NULL;
108 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
109 static ssize_t cpu_probe_store(struct device *dev,
110 struct device_attribute *attr,
114 return arch_cpu_probe(buf, count);
117 static ssize_t cpu_release_store(struct device *dev,
118 struct device_attribute *attr,
122 return arch_cpu_release(buf, count);
125 static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
126 static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
127 #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
128 #endif /* CONFIG_HOTPLUG_CPU */
131 #include <linux/kexec.h>
133 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
136 struct cpu *cpu = container_of(dev, struct cpu, dev);
138 unsigned long long addr;
141 cpunum = cpu->dev.id;
144 * Might be reading other cpu's data based on which cpu read thread
145 * has been scheduled. But cpu data (memory) is allocated once during
146 * boot up and this data does not change there after. Hence this
147 * operation should be safe. No locking required.
149 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
150 rc = sprintf(buf, "%Lx\n", addr);
153 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
155 static ssize_t show_crash_notes_size(struct device *dev,
156 struct device_attribute *attr,
161 rc = sprintf(buf, "%zu\n", sizeof(note_buf_t));
164 static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL);
166 static struct attribute *crash_note_cpu_attrs[] = {
167 &dev_attr_crash_notes.attr,
168 &dev_attr_crash_notes_size.attr,
172 static struct attribute_group crash_note_cpu_attr_group = {
173 .attrs = crash_note_cpu_attrs,
177 static const struct attribute_group *common_cpu_attr_groups[] = {
179 &crash_note_cpu_attr_group,
184 static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
186 &crash_note_cpu_attr_group,
188 #ifdef CONFIG_HOTPLUG_CPU
189 &hotplug_cpu_attr_group,
195 * Print cpu online, possible, present, and system maps
199 struct device_attribute attr;
200 const struct cpumask *const * const map;
203 static ssize_t show_cpus_attr(struct device *dev,
204 struct device_attribute *attr,
207 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
208 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map));
215 #define _CPU_ATTR(name, map) \
216 { __ATTR(name, 0444, show_cpus_attr, NULL), map }
218 /* Keep in sync with cpu_subsys_attrs */
219 static struct cpu_attr cpu_attrs[] = {
220 _CPU_ATTR(online, &cpu_online_mask),
221 _CPU_ATTR(possible, &cpu_possible_mask),
222 _CPU_ATTR(present, &cpu_present_mask),
226 * Print values for NR_CPUS and offlined cpus
228 static ssize_t print_cpus_kernel_max(struct device *dev,
229 struct device_attribute *attr, char *buf)
231 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
234 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
236 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
237 unsigned int total_cpus;
239 static ssize_t print_cpus_offline(struct device *dev,
240 struct device_attribute *attr, char *buf)
242 int n = 0, len = PAGE_SIZE-2;
243 cpumask_var_t offline;
245 /* display offline cpus < nr_cpu_ids */
246 if (!alloc_cpumask_var(&offline, GFP_KERNEL))
248 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
249 n = cpulist_scnprintf(buf, len, offline);
250 free_cpumask_var(offline);
252 /* display offline cpus >= nr_cpu_ids */
253 if (total_cpus && nr_cpu_ids < total_cpus) {
257 if (nr_cpu_ids == total_cpus-1)
258 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
260 n += snprintf(&buf[n], len - n, "%d-%d",
261 nr_cpu_ids, total_cpus-1);
264 n += snprintf(&buf[n], len - n, "\n");
267 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
269 static void cpu_device_release(struct device *dev)
272 * This is an empty function to prevent the driver core from spitting a
273 * warning at us. Yes, I know this is directly opposite of what the
274 * documentation for the driver core and kobjects say, and the author
275 * of this code has already been publically ridiculed for doing
276 * something as foolish as this. However, at this point in time, it is
277 * the only way to handle the issue of statically allocated cpu
278 * devices. The different architectures will have their cpu device
279 * code reworked to properly handle this in the near future, so this
280 * function will then be changed to correctly free up the memory held
283 * Never copy this way of doing things, or you too will be made fun of
284 * on the linux-kernel list, you have been warned.
289 * register_cpu - Setup a sysfs device for a CPU.
290 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
291 * sysfs for this CPU.
292 * @num - CPU number to use when creating the device.
294 * Initialize and register the CPU device.
296 int __cpuinit register_cpu(struct cpu *cpu, int num)
300 cpu->node_id = cpu_to_node(num);
301 memset(&cpu->dev, 0x00, sizeof(struct device));
303 cpu->dev.bus = &cpu_subsys;
304 cpu->dev.release = cpu_device_release;
305 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
306 cpu->dev.bus->uevent = arch_cpu_uevent;
308 cpu->dev.groups = common_cpu_attr_groups;
309 if (cpu->hotpluggable)
310 cpu->dev.groups = hotplugable_cpu_attr_groups;
311 error = device_register(&cpu->dev);
313 per_cpu(cpu_sys_devices, num) = &cpu->dev;
315 register_cpu_under_node(num, cpu_to_node(num));
320 struct device *get_cpu_device(unsigned cpu)
322 if (cpu < nr_cpu_ids && cpu_possible(cpu))
323 return per_cpu(cpu_sys_devices, cpu);
327 EXPORT_SYMBOL_GPL(get_cpu_device);
329 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
330 static DEVICE_ATTR(modalias, 0444, arch_print_cpu_modalias, NULL);
333 static struct attribute *cpu_root_attrs[] = {
334 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
335 &dev_attr_probe.attr,
336 &dev_attr_release.attr,
338 &cpu_attrs[0].attr.attr,
339 &cpu_attrs[1].attr.attr,
340 &cpu_attrs[2].attr.attr,
341 &dev_attr_kernel_max.attr,
342 &dev_attr_offline.attr,
343 #ifdef CONFIG_ARCH_HAS_CPU_AUTOPROBE
344 &dev_attr_modalias.attr,
349 static struct attribute_group cpu_root_attr_group = {
350 .attrs = cpu_root_attrs,
353 static const struct attribute_group *cpu_root_attr_groups[] = {
354 &cpu_root_attr_group,
358 bool cpu_is_hotpluggable(unsigned cpu)
360 struct device *dev = get_cpu_device(cpu);
361 return dev && container_of(dev, struct cpu, dev)->hotpluggable;
363 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
365 #ifdef CONFIG_GENERIC_CPU_DEVICES
366 static DEFINE_PER_CPU(struct cpu, cpu_devices);
369 static void __init cpu_dev_register_generic(void)
371 #ifdef CONFIG_GENERIC_CPU_DEVICES
374 for_each_possible_cpu(i) {
375 if (register_cpu(&per_cpu(cpu_devices, i), i))
376 panic("Failed to register CPU device");
381 void __init cpu_dev_init(void)
383 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
384 panic("Failed to register CPU subsystem");
386 cpu_dev_register_generic();