Line data Source code
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 :
26 : static DEFINE_PER_CPU(struct device *, cpu_sys_devices);
27 :
28 0 : static int cpu_subsys_match(struct device *dev, struct device_driver *drv)
29 : {
30 : /* ACPI style match is the only one that may succeed. */
31 0 : if (acpi_driver_match_device(dev, drv))
32 : return 1;
33 :
34 0 : return 0;
35 : }
36 :
37 : #ifdef CONFIG_HOTPLUG_CPU
38 0 : static void change_cpu_under_node(struct cpu *cpu,
39 : unsigned int from_nid, unsigned int to_nid)
40 : {
41 0 : int cpuid = cpu->dev.id;
42 0 : unregister_cpu_under_node(cpuid, from_nid);
43 0 : register_cpu_under_node(cpuid, to_nid);
44 0 : cpu->node_id = to_nid;
45 0 : }
46 :
47 0 : static int cpu_subsys_online(struct device *dev)
48 : {
49 0 : struct cpu *cpu = container_of(dev, struct cpu, dev);
50 0 : int cpuid = dev->id;
51 0 : int from_nid, to_nid;
52 0 : int ret;
53 :
54 0 : from_nid = cpu_to_node(cpuid);
55 0 : if (from_nid == NUMA_NO_NODE)
56 : return -ENODEV;
57 :
58 0 : 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 0 : to_nid = cpu_to_node(cpuid);
64 0 : if (from_nid != to_nid)
65 0 : change_cpu_under_node(cpu, from_nid, to_nid);
66 :
67 : return ret;
68 : }
69 :
70 0 : static int cpu_subsys_offline(struct device *dev)
71 : {
72 0 : return cpu_device_down(dev);
73 : }
74 :
75 0 : void unregister_cpu(struct cpu *cpu)
76 : {
77 0 : int logical_cpu = cpu->dev.id;
78 :
79 0 : unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
80 :
81 0 : device_unregister(&cpu->dev);
82 0 : per_cpu(cpu_sys_devices, logical_cpu) = NULL;
83 0 : return;
84 : }
85 :
86 : #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
87 : static 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 :
105 : static 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 :
123 : static DEVICE_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
124 : static DEVICE_ATTR(release, S_IWUSR, NULL, cpu_release_store);
125 : #endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
126 : #endif /* CONFIG_HOTPLUG_CPU */
127 :
128 : struct 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 : };
137 : EXPORT_SYMBOL_GPL(cpu_subsys);
138 :
139 : #ifdef CONFIG_KEXEC
140 : #include <linux/kexec.h>
141 :
142 : static ssize_t crash_notes_show(struct device *dev,
143 : struct device_attribute *attr,
144 : char *buf)
145 : {
146 : struct cpu *cpu = container_of(dev, struct cpu, dev);
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 :
160 : return sysfs_emit(buf, "%llx\n", addr);
161 : }
162 : static DEVICE_ATTR_ADMIN_RO(crash_notes);
163 :
164 : static ssize_t crash_notes_size_show(struct device *dev,
165 : struct device_attribute *attr,
166 : char *buf)
167 : {
168 : return sysfs_emit(buf, "%zu\n", sizeof(note_buf_t));
169 : }
170 : static DEVICE_ATTR_ADMIN_RO(crash_notes_size);
171 :
172 : static struct attribute *crash_note_cpu_attrs[] = {
173 : &dev_attr_crash_notes.attr,
174 : &dev_attr_crash_notes_size.attr,
175 : NULL
176 : };
177 :
178 : static struct attribute_group crash_note_cpu_attr_group = {
179 : .attrs = crash_note_cpu_attrs,
180 : };
181 : #endif
182 :
183 : static const struct attribute_group *common_cpu_attr_groups[] = {
184 : #ifdef CONFIG_KEXEC
185 : &crash_note_cpu_attr_group,
186 : #endif
187 : NULL
188 : };
189 :
190 : static 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 :
201 : struct cpu_attr {
202 : struct device_attribute attr;
203 : const struct cpumask *const map;
204 : };
205 :
206 0 : static ssize_t show_cpus_attr(struct device *dev,
207 : struct device_attribute *attr,
208 : char *buf)
209 : {
210 0 : struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
211 :
212 0 : 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 */
219 : static 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 : */
228 0 : static ssize_t print_cpus_kernel_max(struct device *dev,
229 : struct device_attribute *attr, char *buf)
230 : {
231 0 : return sysfs_emit(buf, "%d\n", NR_CPUS - 1);
232 : }
233 : static DEVICE_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
234 :
235 : /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
236 : unsigned int total_cpus;
237 :
238 0 : static ssize_t print_cpus_offline(struct device *dev,
239 : struct device_attribute *attr, char *buf)
240 : {
241 0 : int len = 0;
242 0 : cpumask_var_t offline;
243 :
244 : /* display offline cpus < nr_cpu_ids */
245 0 : if (!alloc_cpumask_var(&offline, GFP_KERNEL))
246 : return -ENOMEM;
247 0 : cpumask_andnot(offline, cpu_possible_mask, cpu_online_mask);
248 0 : len += sysfs_emit_at(buf, len, "%*pbl", cpumask_pr_args(offline));
249 0 : free_cpumask_var(offline);
250 :
251 : /* display offline cpus >= nr_cpu_ids */
252 0 : if (total_cpus && nr_cpu_ids < total_cpus) {
253 0 : len += sysfs_emit_at(buf, len, ",");
254 :
255 0 : if (nr_cpu_ids == total_cpus-1)
256 0 : len += sysfs_emit_at(buf, len, "%u", nr_cpu_ids);
257 : else
258 0 : len += sysfs_emit_at(buf, len, "%u-%d",
259 : nr_cpu_ids, total_cpus - 1);
260 : }
261 :
262 0 : len += sysfs_emit_at(buf, len, "\n");
263 :
264 0 : return len;
265 : }
266 : static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL);
267 :
268 0 : static ssize_t print_cpus_isolated(struct device *dev,
269 : struct device_attribute *attr, char *buf)
270 : {
271 0 : int len;
272 0 : cpumask_var_t isolated;
273 :
274 0 : if (!alloc_cpumask_var(&isolated, GFP_KERNEL))
275 : return -ENOMEM;
276 :
277 0 : cpumask_andnot(isolated, cpu_possible_mask,
278 : housekeeping_cpumask(HK_FLAG_DOMAIN));
279 0 : len = sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(isolated));
280 :
281 0 : free_cpumask_var(isolated);
282 :
283 0 : return len;
284 : }
285 : static DEVICE_ATTR(isolated, 0444, print_cpus_isolated, NULL);
286 :
287 : #ifdef CONFIG_NO_HZ_FULL
288 : static ssize_t print_cpus_nohz_full(struct device *dev,
289 : struct device_attribute *attr, char *buf)
290 : {
291 : return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(tick_nohz_full_mask));
292 : }
293 : static DEVICE_ATTR(nohz_full, 0444, print_cpus_nohz_full, NULL);
294 : #endif
295 :
296 0 : static void cpu_device_release(struct device *dev)
297 : {
298 : /*
299 : * This is an empty function to prevent the driver core from spitting a
300 : * warning at us. Yes, I know this is directly opposite of what the
301 : * documentation for the driver core and kobjects say, and the author
302 : * of this code has already been publically ridiculed for doing
303 : * something as foolish as this. However, at this point in time, it is
304 : * the only way to handle the issue of statically allocated cpu
305 : * devices. The different architectures will have their cpu device
306 : * code reworked to properly handle this in the near future, so this
307 : * function will then be changed to correctly free up the memory held
308 : * by the cpu device.
309 : *
310 : * Never copy this way of doing things, or you too will be made fun of
311 : * on the linux-kernel list, you have been warned.
312 : */
313 0 : }
314 :
315 : #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
316 16 : static ssize_t print_cpu_modalias(struct device *dev,
317 : struct device_attribute *attr,
318 : char *buf)
319 : {
320 16 : int len = 0;
321 16 : u32 i;
322 :
323 16 : len += sysfs_emit_at(buf, len,
324 : "cpu:type:" CPU_FEATURE_TYPEFMT ":feature:",
325 16 : CPU_FEATURE_TYPEVAL);
326 :
327 10272 : for (i = 0; i < MAX_CPU_FEATURES; i++)
328 10240 : if (cpu_have_feature(i)) {
329 1424 : if (len + sizeof(",XXXX\n") >= PAGE_SIZE) {
330 0 : WARN(1, "CPU features overflow page\n");
331 0 : break;
332 : }
333 1424 : len += sysfs_emit_at(buf, len, ",%04X", i);
334 : }
335 16 : len += sysfs_emit_at(buf, len, "\n");
336 16 : return len;
337 : }
338 :
339 16 : static int cpu_uevent(struct device *dev, struct kobj_uevent_env *env)
340 : {
341 16 : char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
342 16 : if (buf) {
343 16 : print_cpu_modalias(NULL, NULL, buf);
344 16 : add_uevent_var(env, "MODALIAS=%s", buf);
345 16 : kfree(buf);
346 : }
347 16 : return 0;
348 : }
349 : #endif
350 :
351 : /*
352 : * register_cpu - Setup a sysfs device for a CPU.
353 : * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
354 : * sysfs for this CPU.
355 : * @num - CPU number to use when creating the device.
356 : *
357 : * Initialize and register the CPU device.
358 : */
359 4 : int register_cpu(struct cpu *cpu, int num)
360 : {
361 4 : int error;
362 :
363 4 : cpu->node_id = cpu_to_node(num);
364 4 : memset(&cpu->dev, 0x00, sizeof(struct device));
365 4 : cpu->dev.id = num;
366 4 : cpu->dev.bus = &cpu_subsys;
367 4 : cpu->dev.release = cpu_device_release;
368 4 : cpu->dev.offline_disabled = !cpu->hotpluggable;
369 4 : cpu->dev.offline = !cpu_online(num);
370 4 : cpu->dev.of_node = of_get_cpu_node(num, NULL);
371 : #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
372 4 : cpu->dev.bus->uevent = cpu_uevent;
373 : #endif
374 4 : cpu->dev.groups = common_cpu_attr_groups;
375 4 : if (cpu->hotpluggable)
376 3 : cpu->dev.groups = hotplugable_cpu_attr_groups;
377 4 : error = device_register(&cpu->dev);
378 4 : if (error) {
379 0 : put_device(&cpu->dev);
380 0 : return error;
381 : }
382 :
383 4 : per_cpu(cpu_sys_devices, num) = &cpu->dev;
384 4 : register_cpu_under_node(num, cpu_to_node(num));
385 4 : dev_pm_qos_expose_latency_limit(&cpu->dev,
386 : PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);
387 :
388 4 : return 0;
389 : }
390 :
391 20 : struct device *get_cpu_device(unsigned cpu)
392 : {
393 20 : if (cpu < nr_cpu_ids && cpu_possible(cpu))
394 20 : return per_cpu(cpu_sys_devices, cpu);
395 : else
396 0 : return NULL;
397 : }
398 : EXPORT_SYMBOL_GPL(get_cpu_device);
399 :
400 0 : static void device_create_release(struct device *dev)
401 : {
402 0 : kfree(dev);
403 0 : }
404 :
405 : __printf(4, 0)
406 : static struct device *
407 20 : __cpu_device_create(struct device *parent, void *drvdata,
408 : const struct attribute_group **groups,
409 : const char *fmt, va_list args)
410 : {
411 20 : struct device *dev = NULL;
412 20 : int retval = -ENODEV;
413 :
414 20 : dev = kzalloc(sizeof(*dev), GFP_KERNEL);
415 20 : if (!dev) {
416 0 : retval = -ENOMEM;
417 0 : goto error;
418 : }
419 :
420 20 : device_initialize(dev);
421 20 : dev->parent = parent;
422 20 : dev->groups = groups;
423 20 : dev->release = device_create_release;
424 20 : device_set_pm_not_required(dev);
425 20 : dev_set_drvdata(dev, drvdata);
426 :
427 20 : retval = kobject_set_name_vargs(&dev->kobj, fmt, args);
428 20 : if (retval)
429 0 : goto error;
430 :
431 20 : retval = device_add(dev);
432 20 : if (retval)
433 0 : goto error;
434 :
435 : return dev;
436 :
437 0 : error:
438 0 : put_device(dev);
439 0 : return ERR_PTR(retval);
440 : }
441 :
442 20 : struct device *cpu_device_create(struct device *parent, void *drvdata,
443 : const struct attribute_group **groups,
444 : const char *fmt, ...)
445 : {
446 20 : va_list vargs;
447 20 : struct device *dev;
448 :
449 20 : va_start(vargs, fmt);
450 20 : dev = __cpu_device_create(parent, drvdata, groups, fmt, vargs);
451 20 : va_end(vargs);
452 20 : return dev;
453 : }
454 : EXPORT_SYMBOL_GPL(cpu_device_create);
455 :
456 : #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
457 : static DEVICE_ATTR(modalias, 0444, print_cpu_modalias, NULL);
458 : #endif
459 :
460 : static struct attribute *cpu_root_attrs[] = {
461 : #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
462 : &dev_attr_probe.attr,
463 : &dev_attr_release.attr,
464 : #endif
465 : &cpu_attrs[0].attr.attr,
466 : &cpu_attrs[1].attr.attr,
467 : &cpu_attrs[2].attr.attr,
468 : &dev_attr_kernel_max.attr,
469 : &dev_attr_offline.attr,
470 : &dev_attr_isolated.attr,
471 : #ifdef CONFIG_NO_HZ_FULL
472 : &dev_attr_nohz_full.attr,
473 : #endif
474 : #ifdef CONFIG_GENERIC_CPU_AUTOPROBE
475 : &dev_attr_modalias.attr,
476 : #endif
477 : NULL
478 : };
479 :
480 : static struct attribute_group cpu_root_attr_group = {
481 : .attrs = cpu_root_attrs,
482 : };
483 :
484 : static const struct attribute_group *cpu_root_attr_groups[] = {
485 : &cpu_root_attr_group,
486 : NULL,
487 : };
488 :
489 0 : bool cpu_is_hotpluggable(unsigned cpu)
490 : {
491 0 : struct device *dev = get_cpu_device(cpu);
492 0 : return dev && container_of(dev, struct cpu, dev)->hotpluggable;
493 : }
494 : EXPORT_SYMBOL_GPL(cpu_is_hotpluggable);
495 :
496 : #ifdef CONFIG_GENERIC_CPU_DEVICES
497 : static DEFINE_PER_CPU(struct cpu, cpu_devices);
498 : #endif
499 :
500 1 : static void __init cpu_dev_register_generic(void)
501 : {
502 : #ifdef CONFIG_GENERIC_CPU_DEVICES
503 : int i;
504 :
505 : for_each_possible_cpu(i) {
506 : if (register_cpu(&per_cpu(cpu_devices, i), i))
507 : panic("Failed to register CPU device");
508 : }
509 : #endif
510 1 : }
511 :
512 : #ifdef CONFIG_GENERIC_CPU_VULNERABILITIES
513 :
514 0 : ssize_t __weak cpu_show_meltdown(struct device *dev,
515 : struct device_attribute *attr, char *buf)
516 : {
517 0 : return sysfs_emit(buf, "Not affected\n");
518 : }
519 :
520 0 : ssize_t __weak cpu_show_spectre_v1(struct device *dev,
521 : struct device_attribute *attr, char *buf)
522 : {
523 0 : return sysfs_emit(buf, "Not affected\n");
524 : }
525 :
526 0 : ssize_t __weak cpu_show_spectre_v2(struct device *dev,
527 : struct device_attribute *attr, char *buf)
528 : {
529 0 : return sysfs_emit(buf, "Not affected\n");
530 : }
531 :
532 0 : ssize_t __weak cpu_show_spec_store_bypass(struct device *dev,
533 : struct device_attribute *attr, char *buf)
534 : {
535 0 : return sysfs_emit(buf, "Not affected\n");
536 : }
537 :
538 0 : ssize_t __weak cpu_show_l1tf(struct device *dev,
539 : struct device_attribute *attr, char *buf)
540 : {
541 0 : return sysfs_emit(buf, "Not affected\n");
542 : }
543 :
544 0 : ssize_t __weak cpu_show_mds(struct device *dev,
545 : struct device_attribute *attr, char *buf)
546 : {
547 0 : return sysfs_emit(buf, "Not affected\n");
548 : }
549 :
550 0 : ssize_t __weak cpu_show_tsx_async_abort(struct device *dev,
551 : struct device_attribute *attr,
552 : char *buf)
553 : {
554 0 : return sysfs_emit(buf, "Not affected\n");
555 : }
556 :
557 0 : ssize_t __weak cpu_show_itlb_multihit(struct device *dev,
558 : struct device_attribute *attr, char *buf)
559 : {
560 0 : return sysfs_emit(buf, "Not affected\n");
561 : }
562 :
563 0 : ssize_t __weak cpu_show_srbds(struct device *dev,
564 : struct device_attribute *attr, char *buf)
565 : {
566 0 : return sysfs_emit(buf, "Not affected\n");
567 : }
568 :
569 : static DEVICE_ATTR(meltdown, 0444, cpu_show_meltdown, NULL);
570 : static DEVICE_ATTR(spectre_v1, 0444, cpu_show_spectre_v1, NULL);
571 : static DEVICE_ATTR(spectre_v2, 0444, cpu_show_spectre_v2, NULL);
572 : static DEVICE_ATTR(spec_store_bypass, 0444, cpu_show_spec_store_bypass, NULL);
573 : static DEVICE_ATTR(l1tf, 0444, cpu_show_l1tf, NULL);
574 : static DEVICE_ATTR(mds, 0444, cpu_show_mds, NULL);
575 : static DEVICE_ATTR(tsx_async_abort, 0444, cpu_show_tsx_async_abort, NULL);
576 : static DEVICE_ATTR(itlb_multihit, 0444, cpu_show_itlb_multihit, NULL);
577 : static DEVICE_ATTR(srbds, 0444, cpu_show_srbds, NULL);
578 :
579 : static struct attribute *cpu_root_vulnerabilities_attrs[] = {
580 : &dev_attr_meltdown.attr,
581 : &dev_attr_spectre_v1.attr,
582 : &dev_attr_spectre_v2.attr,
583 : &dev_attr_spec_store_bypass.attr,
584 : &dev_attr_l1tf.attr,
585 : &dev_attr_mds.attr,
586 : &dev_attr_tsx_async_abort.attr,
587 : &dev_attr_itlb_multihit.attr,
588 : &dev_attr_srbds.attr,
589 : NULL
590 : };
591 :
592 : static const struct attribute_group cpu_root_vulnerabilities_group = {
593 : .name = "vulnerabilities",
594 : .attrs = cpu_root_vulnerabilities_attrs,
595 : };
596 :
597 1 : static void __init cpu_register_vulnerabilities(void)
598 : {
599 1 : if (sysfs_create_group(&cpu_subsys.dev_root->kobj,
600 : &cpu_root_vulnerabilities_group))
601 0 : pr_err("Unable to register CPU vulnerabilities\n");
602 1 : }
603 :
604 : #else
605 : static inline void cpu_register_vulnerabilities(void) { }
606 : #endif
607 :
608 1 : void __init cpu_dev_init(void)
609 : {
610 1 : if (subsys_system_register(&cpu_subsys, cpu_root_attr_groups))
611 0 : panic("Failed to register CPU subsystem");
612 :
613 1 : cpu_dev_register_generic();
614 1 : cpu_register_vulnerabilities();
615 1 : }
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