projects/linux·blob v6.5 · refs

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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_device_up(dev);
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_device_down(dev);
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
128#ifdef CONFIG_KEXEC
129#include <linux/kexec.h>
130
131static ssize_t crash_notes_show(struct device *dev,
132 struct device_attribute *attr,
133 char *buf)
134{
135 struct cpu *cpu = container_of(dev, struct cpu, dev);
136 unsigned long long addr;
137 int cpunum;
138
139 cpunum = cpu->dev.id;
140
141 /*
142 * Might be reading other cpu's data based on which cpu read thread
143 * has been scheduled. But cpu data (memory) is allocated once during
144 * boot up and this data does not change there after. Hence this
145 * operation should be safe. No locking required.
146 */
147 addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
148
149 return sysfs_emit(buf, "%llx\n", addr);
150}
151static DEVICE_ATTR_ADMIN_RO(crash_notes);
152
153static ssize_t crash_notes_size_show(struct device *dev,
154 struct device_attribute *attr,
155 char *buf)
156{
157 return sysfs_emit(buf, "%zu\n", sizeof(note_buf_t));
158}
159static DEVICE_ATTR_ADMIN_RO(crash_notes_size);
160
161static struct attribute *crash_note_cpu_attrs[] = {
162 &dev_attr_crash_notes.attr,
163 &dev_attr_crash_notes_size.attr,
164 NULL
165};
166
167static const struct attribute_group crash_note_cpu_attr_group = {
168 .attrs = crash_note_cpu_attrs,
169};
170#endif
171
172static const struct attribute_group *common_cpu_attr_groups[] = {
173#ifdef CONFIG_KEXEC
174 &crash_note_cpu_attr_group,
175#endif
176 NULL
177};
178
179static const struct attribute_group *hotplugable_cpu_attr_groups[] = {
180#ifdef CONFIG_KEXEC
181 &crash_note_cpu_attr_group,
182#endif
183 NULL
184};
185
186/*
187 * Print cpu online, possible, present, and system maps
188 */
189
190struct cpu_attr {
191 struct device_attribute attr;
192 const struct cpumask *const map;
193};
194
195static ssize_t show_cpus_attr(struct device *dev,
196 struct device_attribute *attr,
197 char *buf)
198{
199 struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
200
201 return cpumap_print_to_pagebuf(true, buf, ca->map);
202}
203
204#define _CPU_ATTR(name, map) \
205 { __ATTR(name, 0444, show_cpus_attr, NULL), map }
206
207/* Keep in sync with cpu_subsys_attrs */
208static struct cpu_attr cpu_attrs[] = {
209 _CPU_ATTR(online, &__cpu_online_mask),
210 _CPU_ATTR(possible, &__cpu_possible_mask),
211 _CPU_ATTR(present, &__cpu_present_mask),
212};
213
214/*
215 * Print values for NR_CPUS and offlined cpus
216 */
217static ssize_t print_cpus_kernel_max(struct device *dev,
218 struct device_attribute *attr, char *buf)
219{
220 return sysfs_emit(buf, "%d\n", NR_CPUS - 1);
221}
222static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
223
224/* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
225unsigned int total_cpus;
226
227static ssize_t print_cpus_offline(struct device *dev,
228 struct device_attribute *attr, char *buf)
229{
230 int len = 0;
231 cpumask_var_t offline;
232
233 /* display offline cpus < nr_cpu_ids */
234 if (!alloc_cpumask_var(&offline, GFP_KERNEL))
235 return -ENOMEM;
236 cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
237 len += sysfs_emit_at(buf, len, "%*pbl", cpumask_pr_args(offline));
238 free_cpumask_var(offline);
239
240 /* display offline cpus >= nr_cpu_ids */
241 if (total_cpus && nr_cpu_ids < total_cpus) {
242 len += sysfs_emit_at(buf, len, ",");
243
244 if (nr_cpu_ids == total_cpus-1)
245 len += sysfs_emit_at(buf, len, "%u", nr_cpu_ids);
246 else
247 len += sysfs_emit_at(buf, len, "%u-%d",
248 nr_cpu_ids, total_cpus - 1);
249 }
250
251 len += sysfs_emit_at(buf, len, "\n");
252
253 return len;
254}
255static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
256
257static ssize_t print_cpus_isolated(struct device *dev,
258 struct device_attribute *attr, char *buf)
259{
260 int len;
261 cpumask_var_t isolated;
262
263 if (!alloc_cpumask_var(&isolated, GFP_KERNEL))
264 return -ENOMEM;
265
266 cpumask_andnot(isolated, cpu_possible_mask,
267 housekeeping_cpumask(HK_TYPE_DOMAIN));
268 len = sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(isolated));
269
270 free_cpumask_var(isolated);
271
272 return len;
273}
274static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);
275
276#ifdef CONFIG_NO_HZ_FULL
277static ssize_t print_cpus_nohz_full(struct device *dev,
278 struct device_attribute *attr, char *buf)
279{
280 return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(tick_nohz_full_mask));
281}
282static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL);
283#endif
284
285static void cpu_device_release(struct device *dev)
286{
287 /*
288 * This is an empty function to prevent the driver core from spitting a
289 * warning at us. Yes, I know this is directly opposite of what the
290 * documentation for the driver core and kobjects say, and the author
291 * of this code has already been publically ridiculed for doing
292 * something as foolish as this. However, at this point in time, it is
293 * the only way to handle the issue of statically allocated cpu
294 * devices. The different architectures will have their cpu device
295 * code reworked to properly handle this in the near future, so this
296 * function will then be changed to correctly free up the memory held
297 * by the cpu device.
298 *
299 * Never copy this way of doing things, or you too will be made fun of
300 * on the linux-kernel list, you have been warned.
301 */
302}
303
304#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
305static ssize_t print_cpu_modalias(struct device *dev,
306 struct device_attribute *attr,
307 char *buf)
308{
309 int len = 0;
310 u32 i;
311
312 len += sysfs_emit_at(buf, len,
313 "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
314 CPU_FEATURE_TYPEVAL);
315
316 for (i = 0; i < MAX_CPU_FEATURES; i++)
317 if (cpu_have_feature(i)) {
318 if (len + sizeof(",XXXX\n") >= PAGE_SIZE) {
319 WARN(1, "CPU features overflow page\n");
320 break;
321 }
322 len += sysfs_emit_at(buf, len, ",%04X", i);
323 }
324 len += sysfs_emit_at(buf, len, "\n");
325 return len;
326}
327
328static int cpu_uevent(const struct device *dev, struct kobj_uevent_env *env)
329{
330 char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
331 if (buf) {
332 print_cpu_modalias(NULL, NULL, buf);
333 add_uevent_var(env, "MODALIAS=%s", buf);
334 kfree(buf);
335 }
336 return 0;
337}
338#endif
339
340struct bus_type cpu_subsys = {
341 .name = "cpu",
342 .dev_name = "cpu",
343 .match = cpu_subsys_match,
344#ifdef CONFIG_HOTPLUG_CPU
345 .online = cpu_subsys_online,
346 .offline = cpu_subsys_offline,
347#endif
348#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
349 .uevent = cpu_uevent,
350#endif
351};
352EXPORT_SYMBOL_GPL(cpu_subsys);
353
354/*
355 * register_cpu - Setup a sysfs device for a CPU.
356 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
357 * sysfs for this CPU.
358 * @num - CPU number to use when creating the device.
359 *
360 * Initialize and register the CPU device.
361 */
362int register_cpu(struct cpu *cpu, int num)
363{
364 int error;
365
366 cpu->node_id = cpu_to_node(num);
367 memset(&cpu->dev, 0x00, sizeof(struct device));
368 cpu->dev.id = num;
369 cpu->dev.bus = &cpu_subsys;
370 cpu->dev.release = cpu_device_release;
371 cpu->dev.offline_disabled = !cpu->hotpluggable;
372 cpu->dev.offline = !cpu_online(num);
373 cpu->dev.of_node = of_get_cpu_node(num, NULL);
374 cpu->dev.groups = common_cpu_attr_groups;
375 if (cpu->hotpluggable)
376 cpu->dev.groups = hotplugable_cpu_attr_groups;
377 error = device_register(&cpu->dev);
378 if (error) {
379 put_device(&cpu->dev);
380 return error;
381 }
382
383 per_cpu(cpu_sys_devices, num) = &cpu->dev;
384 register_cpu_under_node(num, cpu_to_node(num));
385 dev_pm_qos_expose_latency_limit(&cpu->dev,
386 PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
387
388 return 0;
389}
390
391struct device *get_cpu_device(unsigned int cpu)
392{
393 if (cpu < nr_cpu_ids && cpu_possible(cpu))
394 return per_cpu(cpu_sys_devices, cpu);
395 else
396 return NULL;
397}
398EXPORT_SYMBOL_GPL(get_cpu_device);
399
400static void device_create_release(struct device *dev)
401{
402 kfree(dev);
403}
404
405__printf(4, 0)
406static struct device *
407__cpu_device_create(struct device *parent, void *drvdata,
408 const struct attribute_group **groups,
409 const char *fmt, va_list args)
410{
411 struct device *dev = NULL;
412 int retval = -ENOMEM;
413
414 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
415 if (!dev)
416 goto error;
417
418 device_initialize(dev);
419 dev->parent = parent;
420 dev->groups = groups;
421 dev->release = device_create_release;
422 device_set_pm_not_required(dev);
423 dev_set_drvdata(dev, drvdata);
424
425 retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
426 if (retval)
427 goto error;
428
429 retval = device_add(dev);
430 if (retval)
431 goto error;
432
433 return dev;
434
435error:
436 put_device(dev);
437 return ERR_PTR(retval);
438}
439
440struct device *cpu_device_create(struct device *parent, void *drvdata,
441 const struct attribute_group **groups,
442 const char *fmt, ...)
443{
444 va_list vargs;
445 struct device *dev;
446
447 va_start(vargs, fmt);
448 dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs);
449 va_end(vargs);
450 return dev;
451}
452EXPORT_SYMBOL_GPL(cpu_device_create);
453
454#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
455static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
456#endif
457
458static struct attribute *cpu_root_attrs[] = {
459#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
460 &dev_attr_probe.attr,
461 &dev_attr_release.attr,
462#endif
463 &cpu_attrs[0].attr.attr,
464 &cpu_attrs[1].attr.attr,
465 &cpu_attrs[2].attr.attr,
466 &dev_attr_kernel_max.attr,
467 &dev_attr_offline.attr,
468 &dev_attr_isolated.attr,
469#ifdef CONFIG_NO_HZ_FULL
470 &dev_attr_nohz_full.attr,
471#endif
472#ifdef CONFIG_GENERIC_CPU_AUTOPROBE
473 &dev_attr_modalias.attr,
474#endif
475 NULL
476};
477
478static const struct attribute_group cpu_root_attr_group = {
479 .attrs = cpu_root_attrs,
480};
481
482static const struct attribute_group *cpu_root_attr_groups[] = {
483 &cpu_root_attr_group,
484 NULL,
485};
486
487bool cpu_is_hotpluggable(unsigned int cpu)
488{
489 struct device *dev = get_cpu_device(cpu);
490 return dev && container_of(dev, struct cpu, dev)->hotpluggable
491 && tick_nohz_cpu_hotpluggable(cpu);
492}
493EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
494
495#ifdef CONFIG_GENERIC_CPU_DEVICES
496static DEFINE_PER_CPU(struct cpu, cpu_devices);
497#endif
498
499static void __init cpu_dev_register_generic(void)
500{
501#ifdef CONFIG_GENERIC_CPU_DEVICES
502 int i;
503
504 for_each_possible_cpu(i) {
505 if (register_cpu(&per_cpu(cpu_devices, i), i))
506 panic("Failed to register CPU device");
507 }
508#endif
509}
510
511#ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
512static ssize_t cpu_show_not_affected(struct device *dev,
513 struct device_attribute *attr, char *buf)
514{
515 return sysfs_emit(buf, "Not affected\n");
516}
517
518#define CPU_SHOW_VULN_FALLBACK(func) \
519 ssize_t cpu_show_##func(struct device *, \
520 struct device_attribute *, char *) \
521 __attribute__((weak, alias("cpu_show_not_affected")))
522
523CPU_SHOW_VULN_FALLBACK(meltdown);
524CPU_SHOW_VULN_FALLBACK(spectre_v1);
525CPU_SHOW_VULN_FALLBACK(spectre_v2);
526CPU_SHOW_VULN_FALLBACK(spec_store_bypass);
527CPU_SHOW_VULN_FALLBACK(l1tf);
528CPU_SHOW_VULN_FALLBACK(mds);
529CPU_SHOW_VULN_FALLBACK(tsx_async_abort);
530CPU_SHOW_VULN_FALLBACK(itlb_multihit);
531CPU_SHOW_VULN_FALLBACK(srbds);
532CPU_SHOW_VULN_FALLBACK(mmio_stale_data);
533CPU_SHOW_VULN_FALLBACK(retbleed);
534CPU_SHOW_VULN_FALLBACK(spec_rstack_overflow);
535CPU_SHOW_VULN_FALLBACK(gds);
536
537static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
538static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
539static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
540static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL);
541static DEVICE_ATTR(l1tf, 0444, cpu_show_l1tf, NULL);
542static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL);
543static DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL);
544static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL);
545static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL);
546static DEVICE_ATTR(mmio_stale_data, 0444, cpu_show_mmio_stale_data, NULL);
547static DEVICE_ATTR(retbleed, 0444, cpu_show_retbleed, NULL);
548static DEVICE_ATTR(spec_rstack_overflow, 0444, cpu_show_spec_rstack_overflow, NULL);
549static DEVICE_ATTR(gather_data_sampling, 0444, cpu_show_gds, NULL);
550
551static struct attribute *cpu_root_vulnerabilities_attrs[] = {
552 &dev_attr_meltdown.attr,
553 &dev_attr_spectre_v1.attr,
554 &dev_attr_spectre_v2.attr,
555 &dev_attr_spec_store_bypass.attr,
556 &dev_attr_l1tf.attr,
557 &dev_attr_mds.attr,
558 &dev_attr_tsx_async_abort.attr,
559 &dev_attr_itlb_multihit.attr,
560 &dev_attr_srbds.attr,
561 &dev_attr_mmio_stale_data.attr,
562 &dev_attr_retbleed.attr,
563 &dev_attr_spec_rstack_overflow.attr,
564 &dev_attr_gather_data_sampling.attr,
565 NULL
566};
567
568static const struct attribute_group cpu_root_vulnerabilities_group = {
569 .name = "vulnerabilities",
570 .attrs = cpu_root_vulnerabilities_attrs,
571};
572
573static void __init cpu_register_vulnerabilities(void)
574{
575 struct device *dev = bus_get_dev_root(&cpu_subsys);
576
577 if (dev) {
578 if (sysfs_create_group(&dev->kobj, &cpu_root_vulnerabilities_group))
579 pr_err("Unable to register CPU vulnerabilities\n");
580 put_device(dev);
581 }
582}
583
584#else
585static inline void cpu_register_vulnerabilities(void) { }
586#endif
587
588void __init cpu_dev_init(void)
589{
590 if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
591 panic("Failed to register CPU subsystem");
592
593 cpu_dev_register_generic();
594 cpu_register_vulnerabilities();
595}