1// SPDX-License-Identifier: GPL-2.0
2/*
3 * CPU subsystem support
4 */
5
6#include <linux/kernel.h>
7#include <linux/module.h>
8#include <linux/init.h>
9#include <linux/sched.h>
10#include <linux/cpu.h>
11#include <linux/topology.h>
12#include <linux/device.h>
13#include <linux/node.h>
14#include <linux/gfp.h>
15#include <linux/slab.h>
16#include <linux/percpu.h>
17#include <linux/acpi.h>
18#include <linux/of.h>
19#include <linux/cpufeature.h>
20#include <linux/tick.h>
21#include <linux/pm_qos.h>
22#include <linux/sched/isolation.h>
23
24#include "base.h"
25
26static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
27
28static int cpu_subsys_match(struct device *dev, struct device_driver *drv)
29{
30 /* ACPI style match is the only one that may succeed. */
31 if (acpi_driver_match_device(dev, drv))
32 return 1;
33
34 return 0;
35}
36
37#ifdef CONFIG_HOTPLUG_CPU
38static void change_cpu_under_node(struct cpu *cpu,
39 unsigned int from_nid, unsigned int to_nid)
40{
41 int cpuid = cpu->dev.id;
42 unregister_cpu_under_node(cpuid, from_nid);
43 register_cpu_under_node(cpuid, to_nid);
44 cpu->node_id = to_nid;
45}
46
47static int cpu_subsys_online(struct device *dev)
48{
49 struct cpu *cpu = container_of(dev, struct cpu, dev);
50 int cpuid = dev->id;
51 int from_nid, to_nid;
52 int ret;
53
54 from_nid = cpu_to_node(cpuid);
55 if (from_nid == NUMA_NO_NODE)
56 return -ENODEV;
57
58 ret = cpu_up(cpuid);
59 /*
60 * When hot adding memory to memoryless node and enabling a cpu
61 * on the node, node number of the cpu may internally change.
62 */
63 to_nid = cpu_to_node(cpuid);
64 if (from_nid != to_nid)
65 change_cpu_under_node(cpu, from_nid, to_nid);
66
67 return ret;
68}
69
70static int cpu_subsys_offline(struct device *dev)
71{
72 return cpu_down(dev->id);
73}
74
75void unregister_cpu(struct cpu *cpu)
76{
77 int logical_cpu = cpu->dev.id;
78
79 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
80
81 device_unregister(&cpu->dev);
82 per_cpu(cpu_sys_devices, logical_cpu) = NULL;
83 return;
84}
85
86#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
87static ssize_t cpu_probe_store(struct device *dev,
88 struct device_attribute *attr,
89 const char *buf,
90 size_t count)
91{
92 ssize_t cnt;
93 int ret;
94
95 ret = lock_device_hotplug_sysfs();
96 if (ret)
97 return ret;
98
99 cnt = arch_cpu_probe(buf, count);
100
101 unlock_device_hotplug();
102 return cnt;
103}
104
105static ssize_t cpu_release_store(struct device *dev,
106 struct device_attribute *attr,
107 const char *buf,
108 size_t count)
109{
110 ssize_t cnt;
111 int ret;
112
113 ret = lock_device_hotplug_sysfs();
114 if (ret)
115 return ret;
116
117 cnt = arch_cpu_release(buf, count);
118
119 unlock_device_hotplug();
120 return cnt;
121}
122
123static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
124static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
125#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
126#endif /* CONFIG_HOTPLUG_CPU */
127
128struct bus_type cpu_subsys = {
129 .name = "cpu",
130 .dev_name = "cpu",
131 .match = cpu_subsys_match,
132#ifdef CONFIG_HOTPLUG_CPU
133 .online = cpu_subsys_online,
134 .offline = cpu_subsys_offline,
135#endif
136};
137EXPORT_SYMBOL_GPL(cpu_subsys);
138
139#ifdef CONFIG_KEXEC
140#include <linux/kexec.h>
141
142static ssize_t show_crash_notes(struct device *dev, struct device_attribute *attr,
143 char *buf)
144{
145 struct cpu *cpu = container_of(dev, struct cpu, dev);
146 ssize_t rc;
147 unsigned long long addr;
148 int cpunum;
149
150 cpunum = cpu->dev.id;
151
152 /*
153 * Might be reading other cpu's data based on which cpu read thread
154 * has been scheduled. But cpu data (memory) is allocated once during
155 * boot up and this data does not change there after. Hence this
156 * operation should be safe. No locking required.
157 */
158 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
159 rc = sprintf(buf, "%Lx\n", addr);
160 return rc;
161}
162static DEVICE_ATTR(crash_notes, 0400, show_crash_notes, NULL);
163
164static ssize_t show_crash_notes_size(struct device *dev,
165 struct device_attribute *attr,
166 char *buf)
167{
168 ssize_t rc;
169
170 rc = sprintf(buf, "%zu\n", sizeof(note_buf_t));
171 return rc;
172}
173static DEVICE_ATTR(crash_notes_size, 0400, show_crash_notes_size, NULL);
174
175static struct attribute *crash_note_cpu_attrs[] = {
176 &dev_attr_crash_notes.attr,
177 &dev_attr_crash_notes_size.attr,
178 NULL
179};
180
181static struct attribute_group crash_note_cpu_attr_group = {
182 .attrs = crash_note_cpu_attrs,
183};
184#endif
185
186static const struct attribute_group *common_cpu_attr_groups[] = {
187#ifdef CONFIG_KEXEC
188 &crash_note_cpu_attr_group,
189#endif
190 NULL
191};
192
193static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
194#ifdef CONFIG_KEXEC
195 &crash_note_cpu_attr_group,
196#endif
197 NULL
198};
199
200/*
201 * Print cpu online, possible, present, and system maps
202 */
203
204struct cpu_attr {
205 struct device_attribute attr;
206 const struct cpumask *const map;
207};
208
209static ssize_t show_cpus_attr(struct device *dev,
210 struct device_attribute *attr,
211 char *buf)
212{
213 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
214
215 return cpumap_print_to_pagebuf(true, buf, ca->map);
216}
217
218#define _CPU_ATTR(name, map) \
219 { __ATTR(name, 0444, show_cpus_attr, NULL), map }
220
221/* Keep in sync with cpu_subsys_attrs */
222static struct cpu_attr cpu_attrs[] = {
223 _CPU_ATTR(online, &__cpu_online_mask),
224 _CPU_ATTR(possible, &__cpu_possible_mask),
225 _CPU_ATTR(present, &__cpu_present_mask),
226};
227
228/*
229 * Print values for NR_CPUS and offlined cpus
230 */
231static ssize_t print_cpus_kernel_max(struct device *dev,
232 struct device_attribute *attr, char *buf)
233{
234 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
235 return n;
236}
237static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
238
239/* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
240unsigned int total_cpus;
241
242static ssize_t print_cpus_offline(struct device *dev,
243 struct device_attribute *attr, char *buf)
244{
245 int n = 0, len = PAGE_SIZE-2;
246 cpumask_var_t offline;
247
248 /* display offline cpus < nr_cpu_ids */
249 if (!alloc_cpumask_var(&offline, GFP_KERNEL))
250 return -ENOMEM;
251 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
252 n = scnprintf(buf, len, "%*pbl", cpumask_pr_args(offline));
253 free_cpumask_var(offline);
254
255 /* display offline cpus >= nr_cpu_ids */
256 if (total_cpus && nr_cpu_ids < total_cpus) {
257 if (n && n < len)
258 buf[n++] = ',';
259
260 if (nr_cpu_ids == total_cpus-1)
261 n += snprintf(&buf[n], len - n, "%u", nr_cpu_ids);
262 else
263 n += snprintf(&buf[n], len - n, "%u-%d",
264 nr_cpu_ids, total_cpus-1);
265 }
266
267 n += snprintf(&buf[n], len - n, "\n");
268 return n;
269}
270static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
271
272static ssize_t print_cpus_isolated(struct device *dev,
273 struct device_attribute *attr, char *buf)
274{
275 int n = 0, len = PAGE_SIZE-2;
276 cpumask_var_t isolated;
277
278 if (!alloc_cpumask_var(&isolated, GFP_KERNEL))
279 return -ENOMEM;
280
281 cpumask_andnot(isolated, cpu_possible_mask,
282 housekeeping_cpumask(HK_FLAG_DOMAIN));
283 n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(isolated));
284
285 free_cpumask_var(isolated);
286
287 return n;
288}
289static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);
290
291#ifdef CONFIG_NO_HZ_FULL
292static ssize_t print_cpus_nohz_full(struct device *dev,
293 struct device_attribute *attr, char *buf)
294{
295 int n = 0, len = PAGE_SIZE-2;
296
297 n = scnprintf(buf, len, "%*pbl\n", cpumask_pr_args(tick_nohz_full_mask));
298
299 return n;
300}
301static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL);
302#endif
303
304static void cpu_device_release(struct device *dev)
305{
306 /*
307 * This is an empty function to prevent the driver core from spitting a
308 * warning at us. Yes, I know this is directly opposite of what the
309 * documentation for the driver core and kobjects say, and the author
310 * of this code has already been publically ridiculed for doing
311 * something as foolish as this. However, at this point in time, it is
312 * the only way to handle the issue of statically allocated cpu
313 * devices. The different architectures will have their cpu device
314 * code reworked to properly handle this in the near future, so this
315 * function will then be changed to correctly free up the memory held
316 * by the cpu device.
317 *
318 * Never copy this way of doing things, or you too will be made fun of
319 * on the linux-kernel list, you have been warned.
320 */
321}
322
323#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
324static ssize_t print_cpu_modalias(struct device *dev,
325 struct device_attribute *attr,
326 char *buf)
327{
328 ssize_t n;
329 u32 i;
330
331 n = sprintf(buf, "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
332 CPU_FEATURE_TYPEVAL);
333
334 for (i = 0; i < MAX_CPU_FEATURES; i++)
335 if (cpu_have_feature(i)) {
336 if (PAGE_SIZE < n + sizeof(",XXXX\n")) {
337 WARN(1, "CPU features overflow page\n");
338 break;
339 }
340 n += sprintf(&buf[n], ",%04X", i);
341 }
342 buf[n++] = '\n';
343 return n;
344}
345
346static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
347{
348 char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
349 if (buf) {
350 print_cpu_modalias(NULL, NULL, buf);
351 add_uevent_var(env, "MODALIAS=%s", buf);
352 kfree(buf);
353 }
354 return 0;
355}
356#endif
357
358/*
359 * register_cpu - Setup a sysfs device for a CPU.
360 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
361 * sysfs for this CPU.
362 * @num - CPU number to use when creating the device.
363 *
364 * Initialize and register the CPU device.
365 */
366int register_cpu(struct cpu *cpu, int num)
367{
368 int error;
369
370 cpu->node_id = cpu_to_node(num);
371 memset(&cpu->dev, 0x00, sizeof(struct device));
372 cpu->dev.id = num;
373 cpu->dev.bus = &cpu_subsys;
374 cpu->dev.release = cpu_device_release;
375 cpu->dev.offline_disabled = !cpu->hotpluggable;
376 cpu->dev.offline = !cpu_online(num);
377 cpu->dev.of_node = of_get_cpu_node(num, NULL);
378#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
379 cpu->dev.bus->uevent = cpu_uevent;
380#endif
381 cpu->dev.groups = common_cpu_attr_groups;
382 if (cpu->hotpluggable)
383 cpu->dev.groups = hotplugable_cpu_attr_groups;
384 error = device_register(&cpu->dev);
385 if (error) {
386 put_device(&cpu->dev);
387 return error;
388 }
389
390 per_cpu(cpu_sys_devices, num) = &cpu->dev;
391 register_cpu_under_node(num, cpu_to_node(num));
392 dev_pm_qos_expose_latency_limit(&cpu->dev,
393 PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
394
395 return 0;
396}
397
398struct device *get_cpu_device(unsigned cpu)
399{
400 if (cpu < nr_cpu_ids && cpu_possible(cpu))
401 return per_cpu(cpu_sys_devices, cpu);
402 else
403 return NULL;
404}
405EXPORT_SYMBOL_GPL(get_cpu_device);
406
407static void device_create_release(struct device *dev)
408{
409 kfree(dev);
410}
411
412__printf(4, 0)
413static struct device *
414__cpu_device_create(struct device *parent, void *drvdata,
415 const struct attribute_group **groups,
416 const char *fmt, va_list args)
417{
418 struct device *dev = NULL;
419 int retval = -ENODEV;
420
421 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
422 if (!dev) {
423 retval = -ENOMEM;
424 goto error;
425 }
426
427 device_initialize(dev);
428 dev->parent = parent;
429 dev->groups = groups;
430 dev->release = device_create_release;
431 device_set_pm_not_required(dev);
432 dev_set_drvdata(dev, drvdata);
433
434 retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
435 if (retval)
436 goto error;
437
438 retval = device_add(dev);
439 if (retval)
440 goto error;
441
442 return dev;
443
444error:
445 put_device(dev);
446 return ERR_PTR(retval);
447}
448
449struct device *cpu_device_create(struct device *parent, void *drvdata,
450 const struct attribute_group **groups,
451 const char *fmt, ...)
452{
453 va_list vargs;
454 struct device *dev;
455
456 va_start(vargs, fmt);
457 dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs);
458 va_end(vargs);
459 return dev;
460}
461EXPORT_SYMBOL_GPL(cpu_device_create);
462
463#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
464static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
465#endif
466
467static struct attribute *cpu_root_attrs[] = {
468#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
469 &dev_attr_probe.attr,
470 &dev_attr_release.attr,
471#endif
472 &cpu_attrs[0].attr.attr,
473 &cpu_attrs[1].attr.attr,
474 &cpu_attrs[2].attr.attr,
475 &dev_attr_kernel_max.attr,
476 &dev_attr_offline.attr,
477 &dev_attr_isolated.attr,
478#ifdef CONFIG_NO_HZ_FULL
479 &dev_attr_nohz_full.attr,
480#endif
481#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
482 &dev_attr_modalias.attr,
483#endif
484 NULL
485};
486
487static struct attribute_group cpu_root_attr_group = {
488 .attrs = cpu_root_attrs,
489};
490
491static const struct attribute_group *cpu_root_attr_groups[] = {
492 &cpu_root_attr_group,
493 NULL,
494};
495
496bool cpu_is_hotpluggable(unsigned cpu)
497{
498 struct device *dev = get_cpu_device(cpu);
499 return dev && container_of(dev, struct cpu, dev)->hotpluggable;
500}
501EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
502
503#ifdef CONFIG_GENERIC_CPU_DEVICES
504static DEFINE_PER_CPU(struct cpu, cpu_devices);
505#endif
506
507static void __init cpu_dev_register_generic(void)
508{
509#ifdef CONFIG_GENERIC_CPU_DEVICES
510 int i;
511
512 for_each_possible_cpu(i) {
513 if (register_cpu(&per_cpu(cpu_devices, i), i))
514 panic("Failed to register CPU device");
515 }
516#endif
517}
518
519#ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
520
521ssize_t __weak cpu_show_meltdown(struct device *dev,
522 struct device_attribute *attr, char *buf)
523{
524 return sprintf(buf, "Not affected\n");
525}
526
527ssize_t __weak cpu_show_spectre_v1(struct device *dev,
528 struct device_attribute *attr, char *buf)
529{
530 return sprintf(buf, "Not affected\n");
531}
532
533ssize_t __weak cpu_show_spectre_v2(struct device *dev,
534 struct device_attribute *attr, char *buf)
535{
536 return sprintf(buf, "Not affected\n");
537}
538
539ssize_t __weak cpu_show_spec_store_bypass(struct device *dev,
540 struct device_attribute *attr, char *buf)
541{
542 return sprintf(buf, "Not affected\n");
543}
544
545ssize_t __weak cpu_show_l1tf(struct device *dev,
546 struct device_attribute *attr, char *buf)
547{
548 return sprintf(buf, "Not affected\n");
549}
550
551static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
552static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
553static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
554static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL);
555static DEVICE_ATTR(l1tf, 0444, cpu_show_l1tf, NULL);
556
557static struct attribute *cpu_root_vulnerabilities_attrs[] = {
558 &dev_attr_meltdown.attr,
559 &dev_attr_spectre_v1.attr,
560 &dev_attr_spectre_v2.attr,
561 &dev_attr_spec_store_bypass.attr,
562 &dev_attr_l1tf.attr,
563 NULL
564};
565
566static const struct attribute_group cpu_root_vulnerabilities_group = {
567 .name = "vulnerabilities",
568 .attrs = cpu_root_vulnerabilities_attrs,
569};
570
571static void __init cpu_register_vulnerabilities(void)
572{
573 if (sysfs_create_group(&cpu_subsys.dev_root->kobj,
574 &cpu_root_vulnerabilities_group))
575 pr_err("Unable to register CPU vulnerabilities\n");
576}
577
578#else
579static inline void cpu_register_vulnerabilities(void) { }
580#endif
581
582void __init cpu_dev_init(void)
583{
584 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
585 panic("Failed to register CPU subsystem");
586
587 cpu_dev_register_generic();
588 cpu_register_vulnerabilities();
589}
590