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>
16 #include <linux/acpi.h>
18 #include <linux/cpufeature.h>
19 #include <linux/tick.h>
20 #include <linux/pm_qos.h>
21 #include <linux/sched/isolation.h>
25 static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
27 static int cpu_subsys_match(struct device *dev, struct device_driver *drv)
29 /* ACPI style match is the only one that may succeed. */
30 if (acpi_driver_match_device(dev, drv))
36 #ifdef CONFIG_HOTPLUG_CPU
37 static void change_cpu_under_node(struct cpu *cpu,
38 unsigned int from_nid, unsigned int to_nid)
40 int cpuid = cpu->dev.id;
41 unregister_cpu_under_node(cpuid, from_nid);
42 register_cpu_under_node(cpuid, to_nid);
43 cpu->node_id = to_nid;
46 static int cpu_subsys_online(struct device *dev)
48 struct cpu *cpu = container_of(dev, struct cpu, dev);
53 from_nid = cpu_to_node(cpuid);
54 if (from_nid == NUMA_NO_NODE)
59 * When hot adding memory to memoryless node and enabling a cpu
60 * on the node, node number of the cpu may internally change.
62 to_nid = cpu_to_node(cpuid);
63 if (from_nid != to_nid)
64 change_cpu_under_node(cpu, from_nid, to_nid);
69 static int cpu_subsys_offline(struct device *dev)
71 return cpu_down(dev->id);
74 void unregister_cpu(struct cpu *cpu)
76 int logical_cpu = cpu->dev.id;
78 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
80 device_unregister(&cpu->dev);
81 per_cpu(cpu_sys_devices, logical_cpu) = NULL;
85 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
86 static ssize_t cpu_probe_store(struct device *dev,
87 struct device_attribute *attr,
94 ret = lock_device_hotplug_sysfs();
98 cnt = arch_cpu_probe(buf, count);
100 unlock_device_hotplug();
104 static ssize_t cpu_release_store(struct device *dev,
105 struct device_attribute *attr,
112 ret = lock_device_hotplug_sysfs();
116 cnt = arch_cpu_release(buf, count);
118 unlock_device_hotplug();
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 */
125 #endif /* CONFIG_HOTPLUG_CPU */
127 struct bus_type cpu_subsys = {
130 .match = cpu_subsys_match,
131 #ifdef CONFIG_HOTPLUG_CPU
132 .online = cpu_subsys_online,
133 .offline = cpu_subsys_offline,
136 EXPORT_SYMBOL_GPL(cpu_subsys);
139 #include <linux/kexec.h>
141 static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
144 struct cpu *cpu = container_of(dev, struct cpu, dev);
146 unsigned long long addr;
149 cpunum = cpu->dev.id;
152 * Might be reading other cpu's data based on which cpu read thread
153 * has been scheduled. But cpu data (memory) is allocated once during
154 * boot up and this data does not change there after. Hence this
155 * operation should be safe. No locking required.
157 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
158 rc = sprintf(buf, "%Lx\n", addr);
161 static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
163 static ssize_t show_crash_notes_size(struct device *dev,
164 struct device_attribute *attr,
169 rc = sprintf(buf, "%zu\n", sizeof(note_buf_t));
172 static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL);
174 static struct attribute *crash_note_cpu_attrs[] = {
175 &dev_attr_crash_notes.attr,
176 &dev_attr_crash_notes_size.attr,
180 static struct attribute_group crash_note_cpu_attr_group = {
181 .attrs = crash_note_cpu_attrs,
185 static const struct attribute_group *common_cpu_attr_groups[] = {
187 &crash_note_cpu_attr_group,
192 static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
194 &crash_note_cpu_attr_group,
200 * Print cpu online, possible, present, and system maps
204 struct device_attribute attr;
205 const struct cpumask *const map;
208 static ssize_t show_cpus_attr(struct device *dev,
209 struct device_attribute *attr,
212 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
214 return cpumap_print_to_pagebuf(true, buf, ca->map);
217 #define _CPU_ATTR(name, map) \
218 { __ATTR(name, 0444, show_cpus_attr, NULL), map }
220 /* Keep in sync with cpu_subsys_attrs */
221 static struct cpu_attr cpu_attrs[] = {
222 _CPU_ATTR(online, &__cpu_online_mask),
223 _CPU_ATTR(possible, &__cpu_possible_mask),
224 _CPU_ATTR(present, &__cpu_present_mask),
228 * Print values for NR_CPUS and offlined cpus
230 static ssize_t print_cpus_kernel_max(struct device *dev,
231 struct device_attribute *attr, char *buf)
233 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
236 static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
238 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
239 unsigned int total_cpus;
241 static ssize_t print_cpus_offline(struct device *dev,
242 struct device_attribute *attr, char *buf)
244 int n = 0, len = PAGE_SIZE-2;
245 cpumask_var_t offline;
247 /* display offline cpus < nr_cpu_ids */
248 if (!alloc_cpumask_var(&offline, GFP_KERNEL))
250 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
251 n = scnprintf(buf, len, "%*pbl", cpumask_pr_args(offline));
252 free_cpumask_var(offline);
254 /* display offline cpus >= nr_cpu_ids */
255 if (total_cpus && nr_cpu_ids < total_cpus) {
259 if (nr_cpu_ids == total_cpus-1)
260 n += snprintf(&buf[n], len - n, "%u", nr_cpu_ids);
262 n += snprintf(&buf[n], len - n, "%u-%d",
263 nr_cpu_ids, total_cpus-1);
266 n += snprintf(&buf[n], len - n, "\n");
269 static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
271 static ssize_t print_cpus_isolated(struct device *dev,
272 struct device_attribute *attr, char *buf)
274 int n = 0, len = PAGE_SIZE-2;
275 cpumask_var_t isolated;
277 if (!alloc_cpumask_var(&isolated, GFP_KERNEL))
280 cpumask_andnot(isolated, cpu_possible_mask,
281 housekeeping_cpumask(HK_FLAG_DOMAIN));
282 n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(isolated));
284 free_cpumask_var(isolated);
288 static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);
290 #ifdef CONFIG_NO_HZ_FULL
291 static ssize_t print_cpus_nohz_full(struct device *dev,
292 struct device_attribute *attr, char *buf)
294 int n = 0, len = PAGE_SIZE-2;
296 n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(tick_nohz_full_mask));
300 static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL);
303 static void cpu_device_release(struct device *dev)
306 * This is an empty function to prevent the driver core from spitting a
307 * warning at us. Yes, I know this is directly opposite of what the
308 * documentation for the driver core and kobjects say, and the author
309 * of this code has already been publically ridiculed for doing
310 * something as foolish as this. However, at this point in time, it is
311 * the only way to handle the issue of statically allocated cpu
312 * devices. The different architectures will have their cpu device
313 * code reworked to properly handle this in the near future, so this
314 * function will then be changed to correctly free up the memory held
317 * Never copy this way of doing things, or you too will be made fun of
318 * on the linux-kernel list, you have been warned.
322 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
323 static ssize_t print_cpu_modalias(struct device *dev,
324 struct device_attribute *attr,
330 n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
331 CPU_FEATURE_TYPEVAL);
333 for (i = 0; i < MAX_CPU_FEATURES; i++)
334 if (cpu_have_feature(i)) {
335 if (PAGE_SIZE < n + sizeof(",XXXX\n")) {
336 WARN(1, "CPU features overflow page\n");
339 n += sprintf(&buf[n], ",%04X", i);
345 static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
347 char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
349 print_cpu_modalias(NULL, NULL, buf);
350 add_uevent_var(env, "MODALIAS=%s", buf);
358 * register_cpu - Setup a sysfs device for a CPU.
359 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
360 * sysfs for this CPU.
361 * @num - CPU number to use when creating the device.
363 * Initialize and register the CPU device.
365 int register_cpu(struct cpu *cpu, int num)
369 cpu->node_id = cpu_to_node(num);
370 memset(&cpu->dev, 0x00, sizeof(struct device));
372 cpu->dev.bus = &cpu_subsys;
373 cpu->dev.release = cpu_device_release;
374 cpu->dev.offline_disabled = !cpu->hotpluggable;
375 cpu->dev.offline = !cpu_online(num);
376 cpu->dev.of_node = of_get_cpu_node(num, NULL);
377 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
378 cpu->dev.bus->uevent = cpu_uevent;
380 cpu->dev.groups = common_cpu_attr_groups;
381 if (cpu->hotpluggable)
382 cpu->dev.groups = hotplugable_cpu_attr_groups;
383 error = device_register(&cpu->dev);
387 per_cpu(cpu_sys_devices, num) = &cpu->dev;
388 register_cpu_under_node(num, cpu_to_node(num));
389 dev_pm_qos_expose_latency_limit(&cpu->dev,
390 PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
395 struct device *get_cpu_device(unsigned cpu)
397 if (cpu < nr_cpu_ids && cpu_possible(cpu))
398 return per_cpu(cpu_sys_devices, cpu);
402 EXPORT_SYMBOL_GPL(get_cpu_device);
404 static void device_create_release(struct device *dev)
409 static struct device *
410 __cpu_device_create(struct device *parent, void *drvdata,
411 const struct attribute_group **groups,
412 const char *fmt, va_list args)
414 struct device *dev = NULL;
415 int retval = -ENODEV;
417 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
423 device_initialize(dev);
424 dev->parent = parent;
425 dev->groups = groups;
426 dev->release = device_create_release;
427 dev_set_drvdata(dev, drvdata);
429 retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
433 retval = device_add(dev);
441 return ERR_PTR(retval);
444 struct device *cpu_device_create(struct device *parent, void *drvdata,
445 const struct attribute_group **groups,
446 const char *fmt, ...)
451 va_start(vargs, fmt);
452 dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs);
456 EXPORT_SYMBOL_GPL(cpu_device_create);
458 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
459 static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
462 static struct attribute *cpu_root_attrs[] = {
463 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
464 &dev_attr_probe.attr,
465 &dev_attr_release.attr,
467 &cpu_attrs[0].attr.attr,
468 &cpu_attrs[1].attr.attr,
469 &cpu_attrs[2].attr.attr,
470 &dev_attr_kernel_max.attr,
471 &dev_attr_offline.attr,
472 &dev_attr_isolated.attr,
473 #ifdef CONFIG_NO_HZ_FULL
474 &dev_attr_nohz_full.attr,
476 #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
477 &dev_attr_modalias.attr,
482 static struct attribute_group cpu_root_attr_group = {
483 .attrs = cpu_root_attrs,
486 static const struct attribute_group *cpu_root_attr_groups[] = {
487 &cpu_root_attr_group,
491 bool cpu_is_hotpluggable(unsigned cpu)
493 struct device *dev = get_cpu_device(cpu);
494 return dev && container_of(dev, struct cpu, dev)->hotpluggable;
496 EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
498 #ifdef CONFIG_GENERIC_CPU_DEVICES
499 static DEFINE_PER_CPU(struct cpu, cpu_devices);
502 static void __init cpu_dev_register_generic(void)
504 #ifdef CONFIG_GENERIC_CPU_DEVICES
507 for_each_possible_cpu(i) {
508 if (register_cpu(&per_cpu(cpu_devices, i), i))
509 panic("Failed to register CPU device");
514 void __init cpu_dev_init(void)
516 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
517 panic("Failed to register CPU subsystem");
519 cpu_dev_register_generic();