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();