projects/linux·blob v4.2 · refs

507 lines · 11.9 KiB

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 __ref 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}