1/*
2 * CPU subsystem support
3 */
4
5#include <linux/kernel.h>
6#include <linux/module.h>
7#include <linux/init.h>
8#include <linux/sched.h>
9#include <linux/cpu.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>
17#include <linux/of.h>
18#include <linux/cpufeature.h>
19#include <linux/tick.h>
20
21#include "base.h"
22
23static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
24
25static int cpu_subsys_match(struct device *dev, struct device_driver *drv)
26{
27	/* ACPI style match is the only one that may succeed. */
28	if (acpi_driver_match_device(dev, drv))
29		return 1;
30
31	return 0;
32}
33
34#ifdef CONFIG_HOTPLUG_CPU
35static void change_cpu_under_node(struct cpu *cpu,
36			unsigned int from_nid, unsigned int to_nid)
37{
38	int cpuid = cpu->dev.id;
39	unregister_cpu_under_node(cpuid, from_nid);
40	register_cpu_under_node(cpuid, to_nid);
41	cpu->node_id = to_nid;
42}
43
44static int cpu_subsys_online(struct device *dev)
45{
46	struct cpu *cpu = container_of(dev, struct cpu, dev);
47	int cpuid = dev->id;
48	int from_nid, to_nid;
49	int ret;
50
51	from_nid = cpu_to_node(cpuid);
52	if (from_nid == NUMA_NO_NODE)
53		return -ENODEV;
54
55	ret = cpu_up(cpuid);
56	/*
57	 * When hot adding memory to memoryless node and enabling a cpu
58	 * on the node, node number of the cpu may internally change.
59	 */
60	to_nid = cpu_to_node(cpuid);
61	if (from_nid != to_nid)
62		change_cpu_under_node(cpu, from_nid, to_nid);
63
64	return ret;
65}
66
67static int cpu_subsys_offline(struct device *dev)
68{
69	return cpu_down(dev->id);
70}
71
72void unregister_cpu(struct cpu *cpu)
73{
74	int logical_cpu = cpu->dev.id;
75
76	unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
77
78	device_unregister(&cpu->dev);
79	per_cpu(cpu_sys_devices, logical_cpu) = NULL;
80	return;
81}
82
83#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
84static ssize_t cpu_probe_store(struct device *dev,
85			       struct device_attribute *attr,
86			       const char *buf,
87			       size_t count)
88{
89	ssize_t cnt;
90	int ret;
91
92	ret = lock_device_hotplug_sysfs();
93	if (ret)
94		return ret;
95
96	cnt = arch_cpu_probe(buf, count);
97
98	unlock_device_hotplug();
99	return cnt;
100}
101
102static ssize_t cpu_release_store(struct device *dev,
103				 struct device_attribute *attr,
104				 const char *buf,
105				 size_t count)
106{
107	ssize_t cnt;
108	int ret;
109
110	ret = lock_device_hotplug_sysfs();
111	if (ret)
112		return ret;
113
114	cnt = arch_cpu_release(buf, count);
115
116	unlock_device_hotplug();
117	return cnt;
118}
119
120static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
121static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
122#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
123#endif /* CONFIG_HOTPLUG_CPU */
124
125struct bus_type cpu_subsys = {
126	.name = "cpu",
127	.dev_name = "cpu",
128	.match = cpu_subsys_match,
129#ifdef CONFIG_HOTPLUG_CPU
130	.online = cpu_subsys_online,
131	.offline = cpu_subsys_offline,
132#endif
133};
134EXPORT_SYMBOL_GPL(cpu_subsys);
135
136#ifdef CONFIG_KEXEC
137#include <linux/kexec.h>
138
139static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
140				char *buf)
141{
142	struct cpu *cpu = container_of(dev, struct cpu, dev);
143	ssize_t rc;
144	unsigned long long addr;
145	int cpunum;
146
147	cpunum = cpu->dev.id;
148
149	/*
150	 * Might be reading other cpu's data based on which cpu read thread
151	 * has been scheduled. But cpu data (memory) is allocated once during
152	 * boot up and this data does not change there after. Hence this
153	 * operation should be safe. No locking required.
154	 */
155	addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
156	rc = sprintf(buf, "%Lx\n", addr);
157	return rc;
158}
159static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
160
161static ssize_t show_crash_notes_size(struct device *dev,
162				     struct device_attribute *attr,
163				     char *buf)
164{
165	ssize_t rc;
166
167	rc = sprintf(buf, "%zu\n", sizeof(note_buf_t));
168	return rc;
169}
170static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL);
171
172static struct attribute *crash_note_cpu_attrs[] = {
173	&dev_attr_crash_notes.attr,
174	&dev_attr_crash_notes_size.attr,
175	NULL
176};
177
178static struct attribute_group crash_note_cpu_attr_group = {
179	.attrs = crash_note_cpu_attrs,
180};
181#endif
182
183static const struct attribute_group *common_cpu_attr_groups[] = {
184#ifdef CONFIG_KEXEC
185	&crash_note_cpu_attr_group,
186#endif
187	NULL
188};
189
190static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
191#ifdef CONFIG_KEXEC
192	&crash_note_cpu_attr_group,
193#endif
194	NULL
195};
196
197/*
198 * Print cpu online, possible, present, and system maps
199 */
200
201struct cpu_attr {
202	struct device_attribute attr;
203	const struct cpumask *const * const map;
204};
205
206static ssize_t show_cpus_attr(struct device *dev,
207			      struct device_attribute *attr,
208			      char *buf)
209{
210	struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
211
212	return cpumap_print_to_pagebuf(true, buf, *ca->map);
213}
214
215#define _CPU_ATTR(name, map) \
216	{ __ATTR(name, 0444, show_cpus_attr, NULL), map }
217
218/* Keep in sync with cpu_subsys_attrs */
219static 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),
223};
224
225/*
226 * Print values for NR_CPUS and offlined cpus
227 */
228static ssize_t print_cpus_kernel_max(struct device *dev,
229				     struct device_attribute *attr, char *buf)
230{
231	int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
232	return n;
233}
234static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
235
236/* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
237unsigned int total_cpus;
238
239static ssize_t print_cpus_offline(struct device *dev,
240				  struct device_attribute *attr, char *buf)
241{
242	int n = 0, len = PAGE_SIZE-2;
243	cpumask_var_t offline;
244
245	/* display offline cpus < nr_cpu_ids */
246	if (!alloc_cpumask_var(&offline, GFP_KERNEL))
247		return -ENOMEM;
248	cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
249	n = scnprintf(buf, len, "%*pbl", cpumask_pr_args(offline));
250	free_cpumask_var(offline);
251
252	/* display offline cpus >= nr_cpu_ids */
253	if (total_cpus && nr_cpu_ids < total_cpus) {
254		if (n && n < len)
255			buf[n++] = ',';
256
257		if (nr_cpu_ids == total_cpus-1)
258			n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
259		else
260			n += snprintf(&buf[n], len - n, "%d-%d",
261						      nr_cpu_ids, total_cpus-1);
262	}
263
264	n += snprintf(&buf[n], len - n, "\n");
265	return n;
266}
267static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
268
269static ssize_t print_cpus_isolated(struct device *dev,
270				  struct device_attribute *attr, char *buf)
271{
272	int n = 0, len = PAGE_SIZE-2;
273
274	n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(cpu_isolated_map));
275
276	return n;
277}
278static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);
279
280#ifdef CONFIG_NO_HZ_FULL
281static ssize_t print_cpus_nohz_full(struct device *dev,
282				  struct device_attribute *attr, char *buf)
283{
284	int n = 0, len = PAGE_SIZE-2;
285
286	n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(tick_nohz_full_mask));
287
288	return n;
289}
290static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL);
291#endif
292
293static void cpu_device_release(struct device *dev)
294{
295	/*
296	 * This is an empty function to prevent the driver core from spitting a
297	 * warning at us.  Yes, I know this is directly opposite of what the
298	 * documentation for the driver core and kobjects say, and the author
299	 * of this code has already been publically ridiculed for doing
300	 * something as foolish as this.  However, at this point in time, it is
301	 * the only way to handle the issue of statically allocated cpu
302	 * devices.  The different architectures will have their cpu device
303	 * code reworked to properly handle this in the near future, so this
304	 * function will then be changed to correctly free up the memory held
305	 * by the cpu device.
306	 *
307	 * Never copy this way of doing things, or you too will be made fun of
308	 * on the linux-kernel list, you have been warned.
309	 */
310}
311
312#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
313static ssize_t print_cpu_modalias(struct device *dev,
314				  struct device_attribute *attr,
315				  char *buf)
316{
317	ssize_t n;
318	u32 i;
319
320	n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
321		    CPU_FEATURE_TYPEVAL);
322
323	for (i = 0; i < MAX_CPU_FEATURES; i++)
324		if (cpu_have_feature(i)) {
325			if (PAGE_SIZE < n + sizeof(",XXXX\n")) {
326				WARN(1, "CPU features overflow page\n");
327				break;
328			}
329			n += sprintf(&buf[n], ",%04X", i);
330		}
331	buf[n++] = '\n';
332	return n;
333}
334
335static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
336{
337	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
338	if (buf) {
339		print_cpu_modalias(NULL, NULL, buf);
340		add_uevent_var(env, "MODALIAS=%s", buf);
341		kfree(buf);
342	}
343	return 0;
344}
345#endif
346
347/*
348 * register_cpu - Setup a sysfs device for a CPU.
349 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
350 *	  sysfs for this CPU.
351 * @num - CPU number to use when creating the device.
352 *
353 * Initialize and register the CPU device.
354 */
355int register_cpu(struct cpu *cpu, int num)
356{
357	int error;
358
359	cpu->node_id = cpu_to_node(num);
360	memset(&cpu->dev, 0x00, sizeof(struct device));
361	cpu->dev.id = num;
362	cpu->dev.bus = &cpu_subsys;
363	cpu->dev.release = cpu_device_release;
364	cpu->dev.offline_disabled = !cpu->hotpluggable;
365	cpu->dev.offline = !cpu_online(num);
366	cpu->dev.of_node = of_get_cpu_node(num, NULL);
367#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
368	cpu->dev.bus->uevent = cpu_uevent;
369#endif
370	cpu->dev.groups = common_cpu_attr_groups;
371	if (cpu->hotpluggable)
372		cpu->dev.groups = hotplugable_cpu_attr_groups;
373	error = device_register(&cpu->dev);
374	if (!error)
375		per_cpu(cpu_sys_devices, num) = &cpu->dev;
376	if (!error)
377		register_cpu_under_node(num, cpu_to_node(num));
378
379	return error;
380}
381
382struct device *get_cpu_device(unsigned cpu)
383{
384	if (cpu < nr_cpu_ids && cpu_possible(cpu))
385		return per_cpu(cpu_sys_devices, cpu);
386	else
387		return NULL;
388}
389EXPORT_SYMBOL_GPL(get_cpu_device);
390
391static void device_create_release(struct device *dev)
392{
393	kfree(dev);
394}
395
396static struct device *
397__cpu_device_create(struct device *parent, void *drvdata,
398		    const struct attribute_group **groups,
399		    const char *fmt, va_list args)
400{
401	struct device *dev = NULL;
402	int retval = -ENODEV;
403
404	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
405	if (!dev) {
406		retval = -ENOMEM;
407		goto error;
408	}
409
410	device_initialize(dev);
411	dev->parent = parent;
412	dev->groups = groups;
413	dev->release = device_create_release;
414	dev_set_drvdata(dev, drvdata);
415
416	retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
417	if (retval)
418		goto error;
419
420	retval = device_add(dev);
421	if (retval)
422		goto error;
423
424	return dev;
425
426error:
427	put_device(dev);
428	return ERR_PTR(retval);
429}
430
431struct device *cpu_device_create(struct device *parent, void *drvdata,
432				 const struct attribute_group **groups,
433				 const char *fmt, ...)
434{
435	va_list vargs;
436	struct device *dev;
437
438	va_start(vargs, fmt);
439	dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs);
440	va_end(vargs);
441	return dev;
442}
443EXPORT_SYMBOL_GPL(cpu_device_create);
444
445#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
446static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
447#endif
448
449static struct attribute *cpu_root_attrs[] = {
450#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
451	&dev_attr_probe.attr,
452	&dev_attr_release.attr,
453#endif
454	&cpu_attrs[0].attr.attr,
455	&cpu_attrs[1].attr.attr,
456	&cpu_attrs[2].attr.attr,
457	&dev_attr_kernel_max.attr,
458	&dev_attr_offline.attr,
459	&dev_attr_isolated.attr,
460#ifdef CONFIG_NO_HZ_FULL
461	&dev_attr_nohz_full.attr,
462#endif
463#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
464	&dev_attr_modalias.attr,
465#endif
466	NULL
467};
468
469static struct attribute_group cpu_root_attr_group = {
470	.attrs = cpu_root_attrs,
471};
472
473static const struct attribute_group *cpu_root_attr_groups[] = {
474	&cpu_root_attr_group,
475	NULL,
476};
477
478bool cpu_is_hotpluggable(unsigned cpu)
479{
480	struct device *dev = get_cpu_device(cpu);
481	return dev && container_of(dev, struct cpu, dev)->hotpluggable;
482}
483EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
484
485#ifdef CONFIG_GENERIC_CPU_DEVICES
486static DEFINE_PER_CPU(struct cpu, cpu_devices);
487#endif
488
489static void __init cpu_dev_register_generic(void)
490{
491#ifdef CONFIG_GENERIC_CPU_DEVICES
492	int i;
493
494	for_each_possible_cpu(i) {
495		if (register_cpu(&per_cpu(cpu_devices, i), i))
496			panic("Failed to register CPU device");
497	}
498#endif
499}
500
501void __init cpu_dev_init(void)
502{
503	if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
504		panic("Failed to register CPU subsystem");
505
506	cpu_dev_register_generic();
507}
508